500 MW VOLUME 2
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FOREWORD
Power is the most vital necessity for industrial and economical growth of any nation. Electricity can bring sea changes in quality of life of its society members. NTPC in its endeavour for becoming most significant entity once again after 30 years of untiring and relentless efforts, reaffirm its commitment towards making India a self-reliant nation in the field of power generation. Having proven excellence in Operation & Maintenance of 200 and 500MW units; for the first time we are going ahead with the commissioning of 660MW units at our Sipat Project. This is a major step towards technological advancement in power generation. In the present time, efficient and economical power generation is the only answer to realise our ambitious plan. It is the need of the hour that available human resources who are the at the whelm of the affairs managing the large thermal power plants having sophisticated technology and complex controls, is to be properly channelised and trained. NTPC management firmly believes that skill and expertise up-gradation is a continuous process. Therefore, training gets utmost priority in our company. Power Plant Simulators are the most effective tools ever created. This has computer based response, creation incorporating mathematical models to provide real time environment, improves retentivity and confidence level to an optimum level in a risk-free, cost and time effective way.To supplement the hands-on training on panel and make the training more effective an operation manual in two volumes has been brought out. The operation manual on 500MW plant provide the information comprehensively covering all the aspects of Power Plant Operation which can be useful for fresh as well as experienced engineers. It provides a direct appreciation of basics of thermal power plant operation and enables them to take on such responsibility far more sincerely and effectively. I am pleased to dedicate these manuals (volume- I & II), prepared by CSTI members which is a pioneer institute covering more than 7000 participants till date, to the fraternity of engineers engaged in their services to power plant. The volume-I deals with the Plant & system description and II covers the operating instruction in a lucid way. I sincerely hope that readers will find these manuals very useful and the best learning aid to them.
I believe that in spite of all sincere efforts and care of faculty members & staff, some area of improvement might have remained unnoticed. Hence, your valuable suggestions and comments will always be well received and acted upon.
( A. CHAUDHURI ) GENERAL MANAGER
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CONTENTS CHAPTER
TOPIC
PAGE NO
1.
UNIT COLD START-UP PROCEDURE
7-115
2.
UNIT HOT START-UP PROCEDURE
117-127
3.
SHUTDOWN PROCEDURE
129-148
4.
FURNACE SAFEGUARD AND SUPERVISORY SYSTEM
149-198
5.
PROTECTION AND INTERLOCKS
199-222
6.
ANALOG CONTROL SYSTEM
223-233
7.
AUTOMATIC TURBINE RUN-UP SYSTEM (ATRS)
235-270
8.
ELECTRICAL PROTECTIONS
271-284
9.
POWER PLANT CHEMISTRY
285-293
10.
EMERGENCY HANDLING
295-305
11.
LIST OF MALFUNCTION
307-318
NO.
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COLD START-UP PROCEDURE
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CHARGING OF ELECTRICAL SYSTEM 1.
Ensure electrical supply to C.W. Pumps and other associated auxiliaries are available.
2.
Charge Station Transformer TOC or TOD and respective station buses SE/SF.
3.
Ensure that all the electrical breakers are racked IN and OFF Service mode.
4.
Ensure that D.C. Supply to all the breakers is available.
5.
Charge Unit Bus A/B through Station Bus SE.
6.
Charge Unit Service Switch Gear, Emergency Bus through normal Breaker.
7.
Ensure that supply is available to various MCCs, (Turbine MCC, Boiler MCC, TVDC, BVDC, Lub oil MCC).
8.
Charge ESP and Ash Handling Transformers.
9.
Ensure that supply is available to all Electrical Buses.
10.
Check Unit Bus Voltage, Voltage can be adjusted by changing the tap position of Station Transformer.
11.
Normalise MDBFP Breaker through Station Bus SF.
CHARGING OF EMERGENCY BUS THROUGH D.G. SET 1.
Check the D.G.Set physically for fuel level, oil, cooling water.
2.
Control supply and starter motor D.C. voltage are O.K.
3.
Start D.G.Set from CSSAEP (Common Services Supply Auxiliaries Equipment Panel).
4.
Adjust the voltage/Frequency by using switches provided in the panel.
5.
Put the Synchroniser on manual.
6.
Close the D.G.Set Breaker to Emergency Bus.
7.
Check the D.G.Set for any abnormality.
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CHARGING OF AUXILIARY STEAM HEADER OBJECTIVE • To line up and charge auxiliary steam header and charge steam to various equipments. PRE - REQUISITES & STATE OF PLANT 1.
Work permit on 16 ata header, auxiliary PRDS and associated system such as SCAPH, atomising steam, HFO heater, etc., cancelled and men, material removed from these areas.
2.
All drains and manholes are closed and the equipment and system are in service worthy condition.
3.
All level gauges, indicating instruments, pressure and flow switches and other Protective devices are lined up for services.
4.
415 V supply available to valve actuators.
5.
220 V DC supply available.
6.
Control panel supply available
7.
UCB instruments for boiler side available.
8.
Service air and instrument air is charged.
9.
PRE - START CHECKS AND LINE UP
10.
Ensure the output of primary and secondary RAPH A/B cold end temperature control valves are closed.
11.
Ensure the Dearator pressure control by auxiliary steam control valve is closed.
12.
Auxiliary steam header pressure and temperature controller are closed.
13.
Open the auxiliary steam header drain valve from local.
14.
Ensure all the manual isolating valves to fuel oil tank heating, burner atomising, SCAPHs, etc. are close.
15.
Ensure the motorised steam isolation valves to BFP and deaerator
(ASL-004
and ASL-006) are closed. 16.
Ensure the gland sealing steam valve ASH-006 is in closed condition.
17.
Ensure the existing 200 MW unit auxiliary steam is available and inform UCB
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personnel. 18.
Ensure the cold reheat to auxiliary steam block valve ASH - 001 is closed if not turn the switch to close position till green light comes.
OPERATIONAL STEPS 1.
Open the auxiliary steam interconnection form existing 200 MW unit 16 ata header to charge the auxiliary steam header.
2.
Check the pressure and temperature of the 16 ata header comes to normal.
3.
Open the primary and secondary SCAPH A or B inlet and outlet isolating valves.
4.
Open the deaerator pegging motorised valve ASL - 006.
5.
Open the gland steam supply valve ASH-006.
6.
Close the drain of the 16 ata header from local.
*Auxiliary Steam Header is Charged*
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AUXILIARY STEAM SYSTEM
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CHARGING OF RAW COOLING WATER (ARCW) SYSTEM. OBJECTIVE •
To line up and start the auxiliary raw cooling water pumps.
•
To charge the auxiliary raw cooling water to various equipments.
PRE - REQUISITES & STATE OF PLANT 1.
Work permit on circulating water duct, auxiliary cooling
water pump, plate
type heat exchanger and associated system cancelled. 2.
All level gauges, indicating instruments, pressure and flow switches and other protective devices are lined up for service.
3.
All filters and coolers are cleaned and necessary lubrication of equipment’s are done.
4.
415 V supply available for LT drives , valves & actuators.
5.
Control panel supply is available.
6.
6.6KV switch gear charged and breakers are kept in service mode.
7.
Circulating water (CW) pumps are running and CW duct is charged
PRE - START CHECKS AND LINE UP 1.
Ensure that suction valve for all three pumps are open from local.
2.
Check that the gland sealing is in service (i.e.sealing water valves are open), bearing lubrication is satisfactory, pump rotor is free.
3.
Close the pump drain and open the vent to ensure no air is coming.
4.
Line up the discharge filter by opening the isolating valves.
5.
Ensure that isolating valves for the plate type heat (PHE) exchangers are open to CW discharge seal pit.
6.
Ensure the recirculation valve is opened.
7.
Ensure the motorised discharge valves for all three pumps are closed from
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CSSAEP. 8.
Ensure that the EPB (Emergency push button) is released from local.
OPERATIONAL STEPS 1.
Change the selector switch to A position.
2.
Start
ARCW pump Amotor by turning the hand switch position to on and
release it. 3.
Check the starting current and discharge pressure.
4.
The pump discharge valve will start opening and red light will come indicating discharge valve has fully opened.
5.
Close the recirculation valve from local once the discharge valve
is fully
opened. 6.
Check the return flow of the raw cooling water in the CW discharge seal pit.
7.
Check the differential pressure across the discharge strainer.
8.
Ask local operator to check for any abnormal sound from the motor or pump
9.
Check the bearing temperatures
*ARCW pump is in service*
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AUXILIARY RAW COOLING WATER SYSTEM
CHARGING OF EQUIPMENT COOLING WATER (ECW) SYSTEM OBJECTIVE •
To line up and start equipment cooling water pumps.
•
To charge the equipment cooling water to various equipment.
PRE - REQUISITES & STATE OF PLANT 1.
Work permit on equipment cooling system overhead DM water tank, boiler feed pump coolers, auxiliary coolers for generator package, fan coolers, etc., cancelled.
2.
All level gauges, indicating instruments, pressure and flow switches are lined up.
3.
All the filters and coolers are cleaned and necessary lubrication of equipment are done.
4.
415V supply available for LT drives valves & actuators.
5.
Instrument air and service air is charged to the controllers.
6.
ARCW pumps are running normal.
7.
Ensure that 6.6 KV switch gear is charged and the breakers are kept in service mode.
PRE - START CHECKS AND LINE UP 1.
Ensure that suction valve for all three pump is open from local.
2.
Ensure adequate level in the overhead DM water cooling tank.
3.
Check that the gland sealing is in service, bearing lubrication is satisfactory, pump rotor is free.
4.
Open the inlet valve to the suction header from the over head DM water cooling tank.
5.
Close the pump drain and open vent to ensure no air is coming.
6.
Ensure that isolating valves are open for the plate type heat exchanger which is already charged from the auxiliary raw cooling water side.
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7.
Ensure the motorised discharge valves for all the three pumps are closed from CSSAEP.
OPERATIONAL STEPS 1.
Change the selector switch to A position
2.
Start ECW pump A motor by turning the hand switch position to on.
3.
Check the starting current and discharge pressure.
4.
The pump discharge valve to be opened and red light will come indicating discharge valve has fully opened.
5.
Maintain the level in the DM water cooling tank by taking additional make up either from DM plant or from CTP(Condensate Transfer Pump), if running.
6.
Charge the ECW to various auxiliary coolers and check the differential pressure is maintained by the control valve, PCV-1145 for Boiler. package, PCV 1146 for BFP coolers ,PCV - 1144 for CEP, etc.
*ECW pump is in service*
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EQUIPMENT COOLING WATER SYSTEM
START UP OF CONDENSATE SYSTEM OBJECTIVE •
To line up and take hot well make up system in service.
•
To line up and start Condensate Extraction Pumps (CEP) to fill the deaerator.
PRE - REQUISITES & STATE OF PLANT 1.
Unit ECW system in service.
2.
Work permit on various LP heaters, drip system, drain cooler, etc., cancelled and men, material removed from these areas.
3.
Instrument air is charged to various valves and valve actuators.
4.
Local pressure, temperature, flow, level gauges & transmitters charged.
5.
Check that the hot well drains are closed.
6.
Sufficient quantity of DM water available in the unit C.S.T.
7.
Ensure that 6.6 KV switch gear is charged and breakers are kept in the service mode.
8.
Ensure that EPB is released from LOCAL.
PRE - START CHECK AND LINE UP 1. Establish ECW flow to CEP motor cavity air coolers. 2. Open ECW inlet and outlet valves to CEP bearing oil cooler. 3. Line up the hot well normal make up line from local . 4. Line up the hot well emergency make up line from local . 5. Open the GSC minimum flow isolating valve from local . 6. Ensure that condensate spill valve bypass and condensate fill valves are closed. 7. Open the suction valve for all three CEPS from LOCAL 8. Open the recirculation isolation valve from local . 9. Rack in the CEP breakers from Switch gear in service remote position. KORBA SIMULATOR
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10. Open the sealing line valve from common discharge from local . 11. Ensure the common isolation valve for exhaust hood spray and drain manifold is closed from local . 12. Open the manual isolating valves for Deaerator level controller (CO16, CO17) from local . 13. Line up the hot well high level controller from local . 14. Ensure the line up of the LP heaters from water side is through upto the deaerator and water side vent is crack open . 15. Ensure all the CEP discharge valves are closed. 16. Ensure that all the recirculation valves are full open and are in manual mode. OPERATION STEPS 1.
Change the emergency make - up pump A status from manual to auto mode from UCB.
2.
Check that emergency make - up pump A should start.
3.
Start any two hot well make - up pumps from DM plant.
4.
Open the hot well make up emergency control valves to fill the hot well.
5.
Observe the steady rise in the condensate make - up flow and hot well level.
6.
Keep the control mode for emergency make - up pump B in auto.
7.
Close both the controllers when hot well level comes to about +50 mm.
8.
Check the hot well level adequate permissive appears on all the three CEP start permissive indication.
9.
Check that all permissive lamps are on to start CEP.
10.
Start the CEP-A by turning the hand switch to close position and release it.
11.
Check that discharge valve opens and discharge pressure gradually builds up.
12.
Check that the pump is running OK and no abnormal noise at local.
13.
Keep the lead / lag switch of pump B and C to lead and lag mode respectively.
14.
Open the block valve of the Deaerator level control valve CO-014 . KORBA SIMULATOR
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15.
Open the deaerator level control valve to about 20%.
16.
Condensate flow to deaerator increases and condensate discharge pressure drops
17.
Check that deaerator level gradually builds up.
18.
Open the emergency make- up control valve to make - up hot well level to normal value.
19. Close the Deaerator level controller once the Deaerator level has come above normal level. 20. Close the emergency make-up controller as the condensate pump is running on recirculation only. 21. Check the bearing temperature and vibration of the pump. 22. Keep the block valve of Deaerator level controller B station (CO -17) also in open state.
*CEP in service *
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CONDENSATE SYSTEM KORBA SIMULATOR
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MOTOR DRIVEN BOILER FEED PUMP ( BFP - C ) OBJECTIVE •
To line up and take boiler feed pump - in service.
PRE - REQUISITES & STATE OF PLANT 1.
Unit ECW system in service.
2.
Work permit on various HP heaters, drip system, deaerator, etc. cancelled and men, material removed from these areas.
3.
Instrument air is charged to various valves and actuators.
4.
Local pressure, temperature, flow, level gauges and transmitters charged.
5.
Check that deaerator over flow valve and drain valves are closed.
6.
The condensate pump is running on recirculation as per the startup instruction
7.
Check the interlocks of AC & DC LOPs..
PRE - START CHECKS AND LINE UP 1.
Establish the ECW flow to the working oil and lub oil coolers.
2.
Charge the booster pump mechanical seal coolers.
3.
Ensure that seal quench valve is open and seal quench pressure is more than 15 Kg/cm2.
4.
Line up the BFP system from local (Lub oil coolers,working oil coolers etc).
5.
Open the recirculation valve isolating valve for all the three pumps from local
6.
Check that AOP of BFP is taking start from UCB and recirculation valve controller,scoop controller is operative from UCB
7.
Rack in the BFP C breaker from local .
8.
Ensure that HP BP desuperheating station manual valve is in close condition
9.
Open the BFP A/B/C suction valve from local .
10.
Line up the emergency seal quench water pump from local . KORBA SIMULATOR
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11.
Line up the LP dosing and HP dosing system from local .
12.
Ensure that HP heaters are bypassed (valve FW-14 should be opened). Check the analog indication in UCB.
13.
Start the auxiliary oil pump of BFP-C
14.
Ensure that all the permissive lamps are ON in the UCB for boiler feed pump C. OPERATIONAL STEPS
1. Check once more the scoop tube controller is minimum and recirculation valve is full open. 2. Start BFP by turning the hand switch to breaker close position and release it. 3. Open the discharge valve of BFP C (FW-13) opens from local 4. Check the BFP discharge pressure and motor current from UCB 5. Ensure that motor cooling water valve has opened on interlock and red lamp is on. 6. Raise the scoop tube position by about 10% to raise the discharge pressure 7. Check the bearing temperature and vibrations from the UCB indicators. 8. Open the HP BP desuperheating station manual valve from local.
* MD BFP-C is in service. *
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FEED WATER SYSTEM KORBA SIMULATOR
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BOILER FILLING OBJECTIVE •
To line up to fill the water wall, down comers, drum & economiser by boiler feed pump.
PRE - REQUISITES & STATE OF PLANT 1.
Boiler water circulating pumps motor cavity is properly filled and vented.
2.
Sufficient quantity of DM water available in condensate storage tank.
3.
Hot well make-up pump available for chemical mixing and diluting.
4.
Local drum gauge glass charged. Hydrastep and drum level recorder available in UCB.
5.
Unit ECW system in service.
6.
At least one CEP is available to make up the deaerator level.
7.
Hot well make-up system lined up from hot well make-up pump.
8.
DC seal water pump for BFP is available.
9.
MD BFP with all its auxiliaries/controls is available.
10.
Instrument air supply to the entire controller is available.
11.
Sufficient quantity of Ammonia and Hydrazine put in mixing tank and diluted with DM water.
PRE - START CHECKS AND LINE UP 1. Close boiler low point drain valve to IBD tank. Close economiser inlet 2. Header drain and inlet lead drain valves at low point drain
station.
3. Ensure that emergency blow down regulating valves is closed from UCB. 4. Ensure that all the three SGCW pump casing drains are closed. 5. Check SH and RH fill valve at low point drain station are closed. 6. Open all three SGCW pump suction spool vent valves from local. 7. Open all the drain vent valves from UCB.
*Line up for initial boiler filling over. * KORBA SIMULATOR
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DRUM FILLING SGCW PUMPS OBJECTIVE •
To fill the boiler water wall, downcomers, drum and economiser by boiler feed pump.
•
To line up and start SGCW Pump A & B
PRE - REQUISITES & STATE OF PLANT 1. Check that condensate pump discharge header pressure is OK. 2. Equipment cooling water pumps are running. PRE - START CHECKS AND LINE UP 1.
Open the economiser inlet valve E-2 and Economiser recirculation valves from the UCB.
2.
Open the low range feed control station isolating valves, close high range isolating and control valves. Check low range control valve operation.
3.
Check HP heaters feed water bypass valve full open (FW - 14).
4.
Ensure MD BFP/ TD BFP is running
5.
Start LP dosing pump to dose hydrazine and ammonia solution to BFP suction.
OPERATIONAL STEPS 1.
Gradually open the low range feed control valve and control the flow to boiler as per rate of make up to deaerator.
2.
Close the recirculation valve of the BFP if sufficient feed flow is established.
3.
Close the SGCW pump suction spool vents once air free water comes out of them.
4.
Check for level rise in local gauge glass, hydrastep and recorders. KORBA SIMULATOR
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5.
Close the low range feed control valve and open the recirculation valve once the level comes to about 300 mm.
6.
Stop chemical dosing pump and isolate the dosing line.
7.
Ensure the pump discharge valve are fully open, permissive lamp 1 and 2 are ON.
8.
Rack in the breakers of all the three pumps from SWGR.
9.
Ensure the pump cooling water system is lined up from local .
10.
Ensure the status of SG booster pump A as lined up .
11.
Start the SGCW pump -A by turning the hand switch to close position.
12.
Ensure the pump draws about 60 amps if current drawn is less stop the pump immediately and vent thoroughly
13.
Check that drum level is adequate, if not open the low range feed control valve to make it up.
14.
Repeat the procedure for SGCW pump B also.
15.
Check the following ; a) Motor current b) Motor cavity temp c) Pump diff. press. and pump running condition OK at local
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START UP AND WARM UP OF THE FUEL OIL SYSTEM. HEAVY FUEL OIL SYSTEM OBJECTIVE •
To line up and start heavy fuel oil pump.
•
To warm up the fuel oil to required temperature for boiler light up.
PRE - REQUISITES & STATE OF PLANT 1.
Adequate oil level in the HFO storage tank for pump operation.
2.
Auxiliary steam header charged and steam is available.
3.
Local pressure, temperature, flow, level gauges and transmitters charged.
4.
Duplex strainer of the HFO pump is in clean condition.
5.
Work permit on the associated equipment cancelled.
6.
The oil in the day tank is pre-warmed.
7.
Day tank level (indicator at local) checked for proper working.
8.
Ensure that instrument air supply is available. PRE - START CHECKS AND LINE UP
1.
Open the suction valve and discharge valve of any one pump.
2.
Charge the steam tracing system and heat sufficiently before the pump is taken in service.
3.
Vent the pump thoroughly and close the vent valve.
4.
Ensure the recirculation valve is open with its isolating valves.
5.
Since the discharge line is empty crack open the oil valve inlet to the heater, out let may be opened fully.
6.
Ensure that H.O. short recirculation valve HO27is closed and operative from
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UCB 7.
Ensure that H.O. delivery valve (HO18) and inlet to the firing floor (HO25) valves are fully open.
8.
Open the riser vent at GH elevation (HO44) initially.
9.
Ensure that constant circulation orifice is lined up (by pass of HO long recirculation valve).
OPERATIONAL STEPS 1. Start one HFO pump from local. 2. Check the pressure of fuel oil at the boiler front starts increasing gradually as indicated. 3. Once the header is pressurised open the inlet valve to the heater fully. 4. Open the vent of the HFO heater before charging the steam. 5. Crack open the HFO heating steam by pass valve. 6. Close the drain and vent once the heater is thoroughly vented. 7. Open the short recirculation valve HO27 from UCB. 8. Take the temperature controller of the HFO heater in service to maintain the fuel oil temperature to about 125 0 C.
* HFO pump in service *
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LINE UP OF FLUE GAS PATH & APHs OBJECTIVE •
To line up the flue gas path for boiler light up.
•
To line up and take secondary RAPH in service.
PRE - REQUISITES & STATE OF PLANT 1.
Work permit on various boiler areas such as furnace, APH, ID, fans, ESP, ducts, dampers, etc., cancelled and men, material removed from these areas.
2.
Instrument air charged in boiler side pneumatic valves & dampers.
3.
Unit equipment cooling system in running condition with SG side charged.
4.
APH fire sensing device available.
5.
Fire fighting water available for boiler and APHs.
6.
APH soot blowing system available.
7.
All the wall blowers and LRSB are in retracted condition.
8.
Bottom ash equipment such as scrapper conveyer, clinker-grinder, hydraulic oil Pumps, blowers, etc, available for taking into service.
9.
Boiler slag bath, trough seal, economiser hopper, APH hoppers & ESP flushing Apparatus are filled with water and over flowing. HP-LP & service water pump in Service (ASH).
10.
Local pressure, temperature, flow, level gauges and transmitters charged.
11.
Check all peepholes and manholes are closed.
PRE - START CHECKS AND LINE UP 1.
Check oil level in guide bearing and support bearing by dip stick and if necessary top up with the correct oil to bring the level normal.
2.
Establish ECW supply through guide bearing oil coolers.
3.
Open the suction valve of the lub oil pump for APHs.
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4.
Open the inlet/outlet dampers for all the four ESP pass from GD11 to GD 18.
5.
Open the equaliser dampers GD9 and GD10 before ESP from local .
6.
Ensure that flue gas inlet damper and outlet damper to secondary RAPH A, GD 3 and GD 7 are closed.
7.
Ensure that secondary air inlet and out let dampers SAD3
& SAD5 for
secondary RAPH A are closed. 8.
Ensure that primary RAPH A gas inlet/outlet dampers GD1 & GD 2 and GD5, GD6 are fully closed.
9.
Ensure that all the dampers for secondary RAPH B are closed.
10.
Line up the boiler bottom ash hopper system from local .
11.
Switch on any of the three ash slurry pump from local .
OPERATIONAL STEPS 1.
Turn the secondary RAPH - A LOP A for guide bearing to lead mode.
2.
Turn the secondary RAPH -A LOP B for guide bearing to lag mode.
3.
Repeat the above two steps for the support bearing LOPs also
4.
Repeat the above three steps for the secondary RAPH-B also
5.
Check the permissive for secondary RAPH - a are all available
6.
Line up air motor and start RAPH-A on air motor and ensure smooth running of RAPH from local .
7.
With the same sequence take secondary RAPH -B also in service on air motor.
8.
Establish 415V supply and start RAPH electric motor by turning the hand switch to close position.
9.
Ensure that air motor cuts out on interlock.
10.
Open the secondary air out let damper SAD5 followed by the inlet damper SAD
11.
Open the flue gas out let damper GD7 followed by the inlet damper GD3.
* RAPH in service *
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START UP AND LINE UP OF ONE ID FAN OBJECTIVE •
To line up and start ID fan for boiler light up.
PRE - REQUISITES & STATE OF PLANT 1.
Work permit on various boiler areas such as furnace, APH, ID, FD fans, ESP, ducts, damper, etc., cancelled and men material removed from these areas.
2.
Ensure the flue gas path is lined up .
3.
Atleast one secondary air-preheater is running.
4.
HP/LP ash water pumps are running.
5.
Boiler slag bath trough seal, economiser hopper, air preheater hoppers and ESP
flushing apparatus are filled with water and over flowing .
6.
Instrument air is charged to various actuators and dampers, etc.
7.
Boiler man holes, peep holes are in closed condition cooling water charged in access doors through SG booster pumps .
PRE - START CHECKS AND LINE UP 1.
Check that adequate oil level is in the tank, if necessary top up with the correct oil to bring the level to normal.
2.
Charge the hydraulic coupling cooler and one lub oil cooler with Equipment Cooling Water.
3.
Open the suction and discharge valve for the lub oil pump.
4.
Ensure the line up of lub oil through cooler and filter upto the bearing from local.
5.
Ensure that inlet vane position controller is minimum and operative.
6.
Rack in the 6.6 KV motor breaker for ID fan A from switch gear.
7.
Keep the selector of ID fan oil pump in lead mode.
8.
Ensure that hydraulic scoop position is minimum and permissive lamp is on. KORBA SIMULATOR
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OPERATIONAL STEPS 1.
Give ID fan A breaker a start command and check the hydraulic oil pump A takes start, red lamp comes on.
2.
Ensure that inlet/Outlet dampers starts closing on interlock green lamp comes on.
3.
Hydraulic coupling oil pressure adequate permissive lamp comes on.
4.
The moment inlet/outlet dampers get fully closed the fan will take start. Check the starting and no load current.
5.
Check that inlet/outlet dampers for the ID fan A opens after a time delay and inlet/outlet dampers for the other fans close on interlock GD 20,21 and GD23 to GD 25
6.
Check the bearing temperature and vibration from the UCB and are normal. Also motor winding temperature is normal.
7.
The hydraulic oil pump for the non running fans may be put in service after line up.
8.
Increase the inlet vane position to load the fan by raising the controller.
*ID fan taken in service*
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FLUE GAS SYSTEM KORBA SIMULATOR
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START UP AND LINE UP OF ONE FD FAN OBJECTIVE •
To line up and start FD fan for boiler light up.
PRE - REQUISITES & STATE OF PLANT 1.
Work permit on various boiler areas such SCAPHS, wind box, from these
as furnace, APH, ID, FD fans,
burner tilts, etc., cancelled and men, material removed
areas.
2.
Atleast one secondary air preheater is running.
3.
The ID fan is running normal.
4.
Instrument air is charged to all the secondary air damper actuators.
5.
Secondary air damper control (SADC) checked for remote operation.
6.
Wind box manholes are closed.
7.
Unit equipment cooling system is in running condition.
PRE - START CHECKS AND LINE UP 1.
Check that adequate oil level is in the tank, if necessary top up with correct oil to bring the level to normal.
2.
Establish the ECW supply through fan lub oil coolers from local.
3.
Ensure the line up of the lub oil through cooler and filter upto the bearing.
4.
Ensure that blade pitch controller is minimum and operative.
5.
Rack in the 6.6 KV motor breaker for FD fan A from Sw.GR.
6.
Start the lub oil pump B in auto mode once lub oil pressure is adequate.
7.
Keep the lub oil pump B in auto mode once lub oil pressure is adequate.
8.
Interlocks of LOPs motor start/stop to be checked by tripping the running LOP.
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OPERATIONAL STEPS 1.
Give FD fan a start command
2.
Ensure that outlet damper SAD - 1 starts closing and permissive lamp comes on.
3.
All the permissive will be available the moment discharge damper is closed the fan will take start. Check its starting and no load current and also the
motor
winding temperature. 4.
Check that outlet damper for FD fan A reopens after a time delay and discharge damper for FD fan B Closes on inter lock.
5.
Check the bearing temperatures and vibrations from the UCB are normal.
6.
Start the lub oil pump for the FD fan B.
7.
Check the FD fan discharge pressure and wind box pressure should show same value.
8.
Increase the blade pitch of FD fan A to load the fan and observe that air flow should increase.
9.
Open the scanner air fan inlet dampers SID - 1/2 from local.
* FD fan in service *
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LINE UP, CHARGING AND TAKING SCAPHS INTO SERVICE OBJECTIVE •
To charge the SCAPHs from steam side.
PRE - REQUISITES & STATE OF PLANT 1.
The secondary air supply through the SCAPH is established.
2.
Ensure 16 ata steam header is charged .
3.
Ensure that drain valve down stream of SCAPH line supply header is open.
4.
Ensure that final condensate outlet valve to IBD is open.
5.
The instrument air is charged to all the pneumatic actuator.
PRE - START CHECKS AND LINE UP 1.
Open all the four inlet and outlet valves for Secondary air SCAPHs.
2.
Ensure that secondary RAPH - A/B cold end temperature controllers are in closed condition in UCB
3.
Ensure the power supply is available to the motorised SCAPH valves.
OPERATIONAL STEPS 1.
Open the Secondary SCAPH A/B steam inlet valve from local.
2.
Open the motorised valves upstream and downstream of SCAPH control valve
3.
Crack open the Secondary air cold end temperature controller to warm up all the lines.
4.
Throttle drain valves when steam comes out of them.
5.
After sufficient warm up, control valve can be opened more to achieve the required cold end temperature.
6.
Close all the drain valves downstream of the SCAPH
7.
If required, adjust the temperature setter of the cold end temperature controller and transfer the controller in auto mode. * SCAPHS ARE CHARGED *
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LINE UP FOR BOILER LIGHT UP OBJECTIVE • To line up all the associated equipment for boiler light up. PRE - REQUISITES & STATE OF PLANT 1.
Work permit on various boiler areas such as furnace, APH, ID, FD fans, ESP, ducts, damper, etc., cancelled and men, material removed from these areas.
2.
Instrument air charged in boiler side for pneumatic valves and damper operation, oil guns, etc.
3. 4.
Service air charged in boiler side for air heater, air motor ignitor cooling air, etc. Ensure 16 ata steam header is charged
5.
6.6 KV switchgear charged .
6.
415 V supply available for LT drives and valve, damper actuators.
7.
Unit equipment cooling system is in running condition.
8.
Local pressure temperature, flow, level gauges and transmitters charged.
9.
Oil guns and Ignitors checked to be proper fitted.
10.
Secondary air damper control system (SADC) checked for remote operation.
11.
Boiler manholes, peep holes are in closed condition. cooling water charged in access doors.
12.
DC/AC scanner air fan should be in service and interlocks should be checked.
13.
All the wall blowers and LRSB are in retracted condition.
14.
Boiler spring loaded safety valve gags are in removed condition (if light up is being
15.
done after safety valve floating activity).
Bottom ash equipment such as scrapper conveyer, clinker grinder, hydraulic oil pump, blowers, etc. available for taking into service.
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16.
Boiler slag bath, trough seal, economiser hopper, APH hoppers and ESP hoppers, flushing apparatus are filled with water and overflowing.
17.
Following boiler side equipment’s are available for taking in service with their interlocks and protections checked. • At least two numbers of CC pumps. • Both Sec. APHs. • AC scanner air fan. • Atleast one ID fan. • Atleast one FD fan. • Both sec. APH SCAPHs.
18.
Following equipment should also be made ready for requirements at later stage. • Atleast one PA fan and one seal air fan. • 3-4 nos. of coal mills and feeders. • Both primary air preheater’s SCAPHs. • ESP Transfirmers,ESP rectifier transformers,rapping motors, hopprr heaters etc.
19.
Ensure that boiler drum filling is carried out .
20.
Ensure S/H spray and R/H spray station block valves and control valves are closed.
21.
Open the S/H drain header drain valve to IBD full.
PRE - START CHECKS AND LINE UP 1.
Boiler drains and vents should be lined up as follows. •
Low point drain station to IBD isolating valves is closed.
•
Bottom ring header drain valve at low point header is closed.
•
Economiser inlet lead drain valve at low point header is closed.
•
Emergency blow down valves B-127, B128 are operable and are closed.
2.
Ensure both the economiser recirculation valves are open.
3.
Open HP dosing isolating valve at drum level.
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4.
Open S-H steam, saturated steam, CBD water and feed water sampling isolating valves.
5.
Open all S/H header drains full for draining any where in S/H and leave them crack open.
6.
Open the S/H header vents manual valve fully.
7.
Open the motorised boiler drum vent valves from section.
8.
Open all four SH header vent valve
9. 10.
Ensure that main steam stop valve (boiler side)is closed along with bypass valves. Open the motorised RH outlet header vent
11.
Ensure sufficient cold end temperature of the Sec. RAPHs before light up.
12.
Change the status of local oil gun station from local to remote for all four corners and all four elevations.
13.
Line up the boiler CBD lines from local .
14.
Ensure that heavy oil pumps are running and warmed up.
15.
Check that atomising steam is charged upto the firing floor. Also all the steam tracing lines should be charged. * Boiler lined up for light up *
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BOILER LIGHT UP OIL FIRING SYSTEM OBJECTIVE •
To start a purge cycle.
•
To light up the boiler.
PRE - START CHECKS AND LINE UP 1.
All the pre-start checks and line up mentioned earlier .
2.
Ensure that all the operational steps mentioned before are carried out before the boiler is ready for a purge cycle. OPERATIONAL STEPS
1.
Adjust the ID fan and FD fan blade pitch to maintain air flow above 30 % but below 40 %.
2.
Adjust the burner tilt position to horizontal with burner tilt controller
3.
Keep the furnace pressure to about -10 mmwcl with ID inlet valve control.
4.
Ensure that following purge permissives are satisfied : • Mode permit (Nozzle tilt horizontal and air flow less than 40 %). • PA fans off. • Drum level satisfactory. • Air flow > 30% • All feeders off. • All nozzle valves closed • Wind box/furnace DP satisfactory. • No boiler trip command. • Aux. air dampers modulating. • All hot air gates closed. • All scanners sensing no flame. • All pulverisers off.
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• 5.
H.O. Trip valve closed. If wind box/furnace DP permissive is not available wait for all the fuel air dampers to close from top, once air flow is between 30 to 40 % pre-purge damper reset timer will take 5 min.
6.
Ensure that ‘PURGE READY’ & ‘PURGE START’ lamps are glowing at FSSS panel.
7.
Push “Purge start” push button and see ‘purging ‘ lamp comes on the panel. After purging time of 5 min. is over see purge complete lamp glows.
8.
Ensure that master fuel trip relays MFR A and MFR B relay reset and green lamp comes on.
9.
Open H.O. trip valve. Valve opens, if not, open the long recirculation valve and then open the H.O. trip valve.
10.
Increase the H.F.O. pressure controller output.
11.
Adjust the set point of the controller to about 10 - 12 Kg/cm2 and transfer the controller to auto mode.
12.
Wait till HFO temperature at boiler front comes to about 110 o C.
13.
In between once again ensure that superheater vents etc. are fully open and also drains are opened.
14.
Close on oil recirculation valve, green lamp comes on and HFO supply pressure momentarily increases
15.
Insert the furnace probe LHS/RHS till it advances to about 80 to 100 %. Push park button
16.
Depress the ‘Pair 1-3 START’ push button on AB elevation. corner No. 1 is placed in service initially and following occures. •
AB-1 oil gun advances.
•
The spark rod advance yellow lamp comes on.
•
The spark rod lamp comes for 15 sec.
•
Heavy fuel oil nozzle valve start opening.
•
Discriminating scanners starts sensing the flame.
•
HEA ignitor spark signal is removed HEA ignitor is retracted
•
Heavy oil nozzle valve open fully red open lamp comes on
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•
AB-3 gun will advance after 30 sec delay and same seq. as above will follow
17. Depress the pair 2-4 START push button on AB elevation. AB-2 is placed in service similarly to AB-3 mentioned above. 18. The furnace pressure goes up slightly, increase the ID fan loading to maintain the value to about -10 mmwc. 19. Increase the heavy oil controller output to maintain the H.O. supply pressure to about 10 Kg/cm2. (Increase the set point if controller is in auto). 20. HFO temperature may drop as number of guns in service are more. Check the HFO temperature is kept on auto mode at pump house. 21. Check the 16 ata header pressure is also maintained. 22. Adjust the CBD opening as per the chemist recommendations. 23. Maintain the drum level with low range feed control valve. 24. Maintain rate of rise of drum metal temp. less than 2 degree per minute and that of main steam temp. less than 50C by controlling oil firing. 25. At drum pressure of 2 Kg/ cm2 close the boiler drum vents 26. Close all the superheater header manual vents and drains once pressure exceeds 2 Kg/cm2 Perform APH soot blowing to avoid deposition of oil unburnts. 27. Ensure that S.H. header vents (start up vents) are full open. 28. Check the furnace temperature by the furnace probes should not exceed 5400C. 29. Open emergency blow down valves if drum level is swelling to higher level. 30. Check the drum top bottom metal temperatures should not exceed 50oC. ** Boiler lighted up **
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CONDENSER CHARGING OBJECTIVE •
To line up and start CW pumps.
•
To charge condenser from water side.
PRE-REQUISITES & STATE OF PLANT 1.
Work permit on various condenser/circulating water equipment’s such as travelling water screen, circulating water pumps, ducts, condenser water box, seal
pit, etc., cancelled and men, material removed from these areas.
2.
Adequate water level in the CW intake canal.
3.
Electrical power available for circulating water pumps and associated auxiliaries.
4.
One condensate pump is running on recirculation .
5.
CW priming pump is available.
6.
Check that travelling water screen is clear and cleaning system is available for operation.
PRE - START CHECKS AND LINE UP 1.
Open the CW duct vents.
2.
Close the condenser water box drains .
3.
Establish the 415 V supply to the condenser inlet valves.
4.
Ensure that discharge valves for all the three pumps are in closed position.
OPERATIONAL STEPS 1.
Start any one of the CW pump.
2.
Line up the CW priming pump.
3.
Open the CW inlet valve at condenser A and B.
4.
After the system is filled up gradually open the condenser inlet valve to ensure complete priming of the condenser water box.
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5.
Close duct outlet vents when water flows continuously from the vents.
6.
Start the condenser water box priming pump
7.
Line up and start the second CW pump and open the condenser inlet valve to maintain the condenser water box pressure within limits .
8.
After sometime switch off the condenser water box priming pump.
9.
Close the CW duct vents also.
* Condenser charged *
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CONDENSER COOLING WATER SYSTEM
LINE UP AND CHARGING OF TURBINE LUB OIL/SEAL OIL SYSTEM LUB OIL / SEAL OIL SYSTEM OBJECTIVE •
To line up the turbine lub oil system.
•
To start the generator seal oil system.
PRE - REQUISITES & STATE OF PLANT 1.
Work permit on various turbine lubricating equipment’s such centrifuge system, main oil tank, turbine lub oil coolers, vapour extractors, injectors, main oil pump and associated pipe line thrust bearing filter etc., cancelled and men, material removed.
2.
Equipment cooling water pumps are running.
3.
Instrument air is charged to various actuators.
4.
Local pressure, temperature, flow, level gauges and transmitters charged.
5.
Control power to turbine side instruments in UCB available.
6.
415 V power to various TG MCC ,TVDCcharged.
7.
Adequate oil in the main oil tank is available.
8.
The centrifuge and other oil purifier system is available.
9.
Both the oil vapour extractors are available. PRE - START CHECKS AND LINE UP
1.
Check that gate valve gearing closed with its SLC off.
2.
Line up the lub oil cooler as per the standard practice (thorough venting of cooler should be carried out).
3.
Line up the thrust bearing lub oil filter and that ensure standby filter is available.
4.
Open the oil temperature controller manually to about 30 %.
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5.
Check the lub oil supply valves to turbine and generator bearings are open. These valves are normally adjusted at the time of commissioning.
6.
Line up the seal oil cooling system from local . OPERATIONAL STEPS
1.
Turn on the oil vapour extractor by pressing from UCB.
2.
Start the generator bearing chamber exhaust fan 1from local.
3.
Start one auxiliary oil pump from the insert
4.
Check the lub oil pressure and AOP current are normal.
5.
Switch on the SLC for the AOP2 and EOP from the control insert
6.
Check the auto start of AOP2/EOP by switching off the AOP1.
7.
Ensure that AOP 1 is running with its SLC on.
8.
Transfer the lub oil temperature controller to auto mode
9.
Line up and take in service seal oil coolers and oil filters .
10.
Line up and start seal oil pumps
11.
Ensure that air is purged out & generator is filled with CO2
12.
Open the hydrogen supply valve to generator from local
13.
Check the hydrogen pressure once the pressure reaches 4 Kg/cm2 then close the valve.
14.
Check the hydrogen purity from indicator in UCB and, get the measurement of moisture in H2 is done
15.
Check that seal oil tank levels are normal. * Hydrogen filling done, seal oil pumps are in service *
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TO TAKE HYDRAULIC BARRING GEAR IN SERVICE JACKING OIL SYSTEM/TURNING GEAR OBJECTIVE •
To line up and start the jacking oil pump.
• To keep the turbine on turning gear. PRE - REQUISITES & STATE OF PLANT 1.
Work permit on various turbine oil system as main oil tank turbine lub oil coolers, vapour extractors, pressurising valves, etc., cancelled and men, material removed from the area.
2.
Local pressure, temperature, flow, level gauges and transmitters charged.
3.
Turbine lub oil system charged.
PRE - START CHECKS AND LINE UP 1.
Check the fine control valve supplying high pressure jacking oil for open.
2.
Check that pressure relief valve is properly set and the bypass valve is closed.
3.
Ensure that turbine lub oil temperature controller is kept on auto.
4.
Ensure the turbine differential expansions are within limits.
OPERATIONAL STEPS 1.
Start jacking oil pump. Check that jacking oil press. is normal.
2.
Standby and DC jacking oil pumps available for service. Check winding temperature locally.
3.
Transfer the SLC mode of all the jacking oil pumps to auto.
4.
Check the jacking oil pressure comes to about 125 Kg/cm2
5.
Turn on the SLC turning gear.
The gate valve gearing starts opening and
turbine speed goes up.
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6.
The speed should come up to approximately 80 RPM without vacuum, check the lub oil temperature controller maintains the set lub oil temperature.
7.
Check that bearing vibrations and bearing temperature are normal and lub oil flow should be normal.
*Turbine on turning gear *
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LINE UP AND START UP OF CONTROL FLUID PUMPS OBJECTIVE •
To lineup and start control fluid pumps.
•
To charge the 8bar and 32 bar fluid to control system.
PRE - REQUISITES & STATE OF PLANT 1.
Work permit on various turbine control oil system such as control fluid tank, governing rack, coolers, accumulator, LP bypass valve’s actuators, pumps and various interconnecting pipe - lines.
2.
Control fluid tank level is adequate.
3.
All the drains in the system are closed.
4.
Local pressure, temperature, flow level gauges and transmitters charged.
PRE - START CHECKS AND LINE UP 1.
Check the line up of the duplex filters provided in the high pressure and low pressure control system.
2.
Charge the control fluid oil coolers from water side.
3.
Open high pressure accumulator isolating valves provided at various high pressure service points.
OPERATIONAL STEPS 1.
Start any one of the control fluid tank vapour extractor.
2.
Start control fluid pump, and check the discharge pressure and motor amps.
3.
Keep the SLC of both the pumps to auto mode from console.
4.
Establish control fluid supply to various services. • Control fluid pump in service *
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CONTROL FLUID SYSTEM WITH REGENERATION PLANT
1. Control Fluid Tank 2. Control Fluid Pump 32/8 Bar 3. Safety Valve 4. Circulating Pump 5. Shut-Off Valve 6. Fuller’s Earth Filter
a. Control Fluid Approx. 8 Bar a1. Control Fluid Approx. 32 Bar C. Return Flow C1. Riser Room Drainage C2. Main Room Drainage
7. Strainer
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VACUUM PULLING OBJECTIVE •
To line up the condenser circulating water system.
•
To line up and start the vacuum pump for establishing the vacuum.
PRE - REQUISITES & STATE OF PLANT 1.
Work permit on various equipment such as condenser water box ,valves, vacuum pumps, flash tanks, hot well, etc., cancelled and men, material removed from the area.
2.
Ensure condenser water box is charged.
3.
Ensure Equipment cooling water is charged.
4.
One condensate pump is running.
5.
Turbine lub oil system is in service and turbine on barring gear.
6.
The auxiliary steam header is charged.
7.
All the possible air paths are blocked, i.e., turbine glands, hot reheat vents and drains vacuum breaker valve, atmospheric lines coming to auxiliary flash box.
PRE - START CHECKS AND LINE UP 1.
Close drains and fill the air/water separator tank of ELMO vacuum pump.
2.
Line up tank level controller by opening isolating valve.
3.
Vacuum pump A/B system lined up from local.
4.
Charge, vent and take into service the condensate cooler.
OPERATIONAL STEPS 1.
Open air isolating valve, bypass valve and close the air ejector valve to put the pump in hogging mode.
2.
Open the drain valve of the gland steam supply from console
3.
Open the aux steam block valve ASH-006 to to gland seal system.
4.
Increase the opening of the steam seal supply valve to warm-up the header and watch the gland steam temp. KORBA SIMULATOR
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5.
Switch on the seal steam condenser exhauster from insert
6.
Slowly increase the output of the seal steam pressure controller to maintain pressure of 0.01 Kg/cm2.
7.
Close the vacuum breaker
8.
Pre-select the vacuum pump no. 1 from the selector switch
9.
Open the vacuum pump air isolation valve no. 1.
10.
Start the pump from the UCB console.
11.
Check the vacuum builds up to about - 0.9 Kg/cm2 .
12.
Close the air ejector 1 bypass valve and open the air ejector valve 1 to keep the vacuum pump in hold mode.
13.
Close the gland seal steam drain valve after gland steam temperature reaches 140 to 150 0 C
(Alternatively above steps can be done automatically if SGC evacuation is on Auto.)
* Condenser vacuum pulled *
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VACUUM PUMP FLOW DIAGRAM
MAIN STEAM LINE WARMING AND CHARGING OBJECTIVE •
To warm-up and charge the main steam line up to Emergency stop valves
PRE - REQUISITES & STATE OF PLANT 1.
Work permit on various boiler areas such as main steam stop valve, safety valves, main steam strainer, various lines etc., cancelled and men, material are removed from these areas.
2.
Boiler is in lighted up condition and boiler drum pressure is about 6 to 8 Kg/cm2.
3.
Condenser vacuum is pulled.
4.
Boiler drum vents and superheater vents / drains are closed. PRE - START CHECKS AND LINE UP
1.
Ensure that main steam header drain valve MSD-050 valve is open.
2.
Open the main steam strainer drain valve MSD - 054 to MSD - 060
3.
Open the hot reheat strainer drain valve MSD - 034 to MSD - 040
4.
Check that SLC drain is kept on auto and drains are open as per the logic. OPERATIONAL STEPS
1.
Turn the main steam stop valve’s MS-001 equaliser isolating valve to open position and wait till it is fully open. Repeat the above step for MS - 002 valve also.
2.
Crack open the regulating valve by holding the switch to open position for MS001 and MS - 002.
3.
Wait for sometime; observe the main steam temperature rises before ESV.
4.
Open further the bypass regulating valve to about 50 % and wait.
5.
Open the main steam stop valve 1 and 2 after opening the bypass valve fully.
6.
Check that bypass equaliser valves should close once the main steam stop valves
are full open.
* Main steam line warmed and charged. *
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HP BYPASS CHARGING OBJECTIVE •
To line up HP bypass system.
•
To take HP bypass into service.
PRE - REQUISITES & STATE OF PLANT 1.
Work permit on various HP bypass oil unit, valves, desuperheater, lines, etc., cancelled and men, material removed from the area.
2.
Oil level in HP bypass tank is normal.
3.
Both HP bypass pumps auto start and stop with oil pressure < 110 Kg/cm2 and >160 Kg/cm2 checked OK.
4.
All the five numbers hydraulic operated valves, i.e. BP1/2, BD, BPE1/2 oil line valves are operative.
5.
HP bypass control and instrumentation side checked and made available.
6.
All the five numbers of hydraulic operated valves open and close operation checked from local and control room in manual mode.
7.
ECW system running and bypass valves BP1 and BP2 gland cooling water inlet and outlet valves are in open condition.
8.
Any one of the BFP is running and common feed discharge line is charged to supply HP bypass spray water.
9.
Turbine on barring gear, condenser vacuum pulled.
10.
R/H start up vents electrical supply available. Also LP bypasses system lined up and available to take care of RH steam flow and pressure.
11.
Main steam line in charged condition with line drain open to flash tank - 6 and HP strainer drain open to HP/LP Flash tank.
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PRE - START CHECKS AND LINE UP 1.
Open HP bypass flow nozzle down stream drain manual valves.
2.
Close HP bypass spray water line manual drain valves after BD, BPE-1 and BPE-2 valves.
3.
Ensure that spray water line hydraulic valves BD, BPE1 and BPE2 are in fully closed condition.
4.
Open the HP bypass spray water line manual isolating valve. OPERATIONAL STEPS
1.
Set the pressure setter of HP BP about 12 Kg/cm 2 from the console.
2.
Adjust the temperature set point of BPE-1 and BPE-2 to about 220oC.
3.
Adjust the LP bypass fixed set point to about 4 Kg/cm 2 and ensure that LP bypass is kept on auto.
4.
Ensure that the water spray pressure controller is in manual mode.
5.
Open the BP1 and BP2 valve manually to about 5 % from the console. Check that
6.
BD valves and both BPE valves get transferred to auto mode.
Check that HP Bypass down stream temperature increases, temperature will be maintained by the spray valves BPE1/2 at about 220 0 C.
7.
Raise the boiler firing by raising the heavy oil pressure to increase the steam pressure.
8.
Ensure that LP bypass has opened and hot reheat pressure is maintained as per
9.
fixed set point.
Bypass valves can be put in auto mode with main steam pressure matching the HP bypass pressure setter to have bumpless transfer after adequate boiler firing is achieved.
10. 11.
Close the superheater header vents and start up vents. The downstream temperature set point can be varied depending on the final hot reheat temperature requirements during start up which is about 300oC. (280oC to 340oC) KORBA SIMULATOR
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12.
Close the reheater outlet header vents once the LP bypass valves are sufficiently open to maintain minimum flow through reheater.
13.
The HP bypass pressure setter should be gradually increased to about 40 Kg/cm2 to bring the main steam parameters for rolling the turbine.
Note 1 HP bypass valves will force close / not open under following condition. I)
If the downstream temperature is more than 380oC.
II)
If vacuum is - 0.6 Kg/cm2.
7.
HP bypass lined up and available for service.
8.
Boiler steaming with drum pressure about 6 to 8 Kg/cm2. PRE - START CHECKS AND LINE UP
1.
Open the manual isolation valves for exhaust hood spray and drain manifold.
2.
Open the LP bypass spray manual valve from local.
3.
Injection water pressure switch, low vacuum protection switch in LP by pass rack
4.
are in operating position.
Ensure that all the 8 bar control fluid line and various valves are open and charged condition, e.g. main supply isolating valve to bypass rack, to
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temperature dependent solenoid valves, injection water pressure switch, etc.are open and in charged condition. 5.
Check that individual injection water manual bypass valves are closed.
6.
Check that isolating valves downstream of duplex filter in 32 bar control fluid line
for both LP BP control valves are open.
7.
Check that drains, vents of both duplex filters are closed.
8.
Check the main isolating valve in the injection water line from CEP discharge header is open. OPERATIONAL STEPS
1.
Set the hot reheat pressure set point reference to 4 Kg/cm2 in LP bypass console.
2.
Check that both temperature dependent solenoid valves are in reset condition in LP bypass console, otherwise reset them.
3.
Charge the main steam line and open the HP bypass valves upto 5 %.
4.
With LP bypass valves in manual mode, give increase command to LP bypass controller gradually till the injection water valves 1 and 3 opens full and then both the bypass stop valves opens full as indicated in the console.
5.
Increase the controller further till both the bypass control valves open about 25 %.
6.
As HP and LP Bypass in service, the boiler start up vents, hot reheat vents can be closed.
7.
As HP Bypass valves open more (either in manual or auto), hot reheat pressure will gradually approaches 12 Kg/cm2, raise the LP bypass fixed set point to 12 Kg/cm2.
KORBA SIMULATOR
73
8.
Check the control error deviation in the console. When it becomes zero the LP bypass controller can be switched to auto with automatic control interface (ACI) off.
9.
If LP Bypass downstream flow increases above 45 % , check that second set of injection water valves open automatically and will be indicated on the console.
Note -1 LP bypass operation can be done with automatic interface kept ‘ON’.
It will
automatically open the bypass control valve to 25 % and will hold it till the actual Hot reheat pressure reaches 12 Kg/cm2. The ACI will be switched off. Note – 2 Both the LP bypass stop and control valves will close if i)
Condenser vacuum is less than -0.6 Kg/cm2.
ii)
Injection water pressure after injection valves is less than set value(18Kg/Cm2).
iii) Either of the stop and control valve will close if the corresponding condenser wall temperature is more than 90 o C. Note – 3 When turbine is on load, the LP bypass pressure set point (sliding set point) is a function of HP turbine first stage pressure. The maximum of fixed and sliding set point will be the operating set point and LP bypass will open if in auto mode, when actual reheat pressure is more than this set point.
* LP bypass taken in service *
KORBA SIMULATOR
74
LP BYPASS SYSTEM KORBA SIMULATOR
75
LINE UP FOR TURBINE ROLLING OBJECTIVE •
To line up the turbine governing system and drains for rolling.
•
To line up and charge the stator water system.
PRE - REQUISITES & STATE OF PLANT 1.
Work permits on various turbine side equipments like main oil pump’ HP/IP/LP
turbine, generator, extraction system, drains, reheat steam lines,
extraction
NRVs, etc., are cancelled and men material removed from these
areas. 2.
The turbine lub oil system and jacking oil system charged and turbine is on barring gear.
3.
Atleast one control fluid pump is in running condition and 32 bar and 8 bar fluid
4.
charged to various parts of governing system.
The boiler is lit up condition with HP/LP bypass in operation and main steam pressure/temperature to about 40 Kg /cm 2with 350 OC.
5.
Adequate water level in the primary water tank and nitrogen charging system available.
6.
The control power supply to the governing panels/insert available.
PRE - START CHECKS AND LINE UP 1.
Open the drain before HP control valve 1 to 4 to about 60 % in manual mode from UCB console
2.
Open the drain upstream and before seat of interceptor valve MSD-093 to MSD 096
3.
Open the ESV seat drain MSD-091/92
4.
Check that primary water line drains are closed.
5.
Line up the primary water system by opening the suction and discharge vlv and taking one cooler and one filter in service.
6.
Open the stator water cooling system manual inlet isolating valve from local.
7.
Ensure that generator lockout relay is reset from GRP panel.
KORBA SIMULATOR
76
1.
Ensure that SLC drain is ON.
2.
Check the TSE indicator and recorders are healthy and showing the correct values.
3.
Check the main steam pressure about 40 Kg/cm2 and temperature < 3500C with hot reheat pressure about 12 Kg/cm 2 and temperature around 3600C.
OPERATIONAL STEPS 1.
Start the primary cooling water pump from local .
2.
Open the exciter cooler and hydrogen cooler isolating valves.
3.
Check the primary water flow & temperature from the UCB.
4.
Ensure that unit is on the limit pressure mode with deviation positive on console.
5.
Switch on the tracking device from the insert
6.
Reduce the starting device to zero value. Check that trip oil pressure is built and auxiliary start up oil pressure should come up to more than 5 Kg/cm2.
7.
Ensure the TSE effect is ON.
8.
GT / UAT cooler control system lined up .
9.
Ensure that hydrogen temperature controller and primary water temperature controller are healthy and are available.
10.
Raise the speeder gear to 100 % position.
11.
Adjust the load limiter to about 50 MW
KORBA SIMULATOR
77
TURBINE ROLLING SYNCHRONISATION OBJECTIVE •
To roll and soak the turbine at rated speed.
•
To synchronise the machine and achieve the block load.
PRE- REQUISITES & STATE OF PLANT 1.
Work permit on various generator side equipments such as exciter, AVR, field breaker, generator transformers, unit auxiliary transformers, etc., cancelled and men, material are removed from these area.
2.
The line up for the turbine rolling is done.
3.
The switchyard 400 KV buses are charged with bus coupler close.
4.
The main steam parameters are available and HP / LP bypass in service.
5.
All the lockout relays in the generator protection panel are reset.
6.
A minimum of three / four pulverisers are available to be taken into service.
7.
Steam driven BFPs are also available.
8.
Hydrogen pressure is adequate( 4.0 Kg/cm2 ) and spare bottles are available. PRE-START CHECKS AND LINE UP
1.
Check the excitation not blocked, signal is available in the control panel.
2.
Check that the load limit is greater than 50 MW.
3.
Check that hot reheat and cold reheat drain valves are open
4.
Ensure that main generator voltmeter selector is not in off position.
5.
Check the operation of Gen. Transformer tap position selector.
6.
Close the 400 KV generator - 6 bay’ main bus -2 line isolator (SEM - 6004) from switch yard .
7.
Ensure the Earthing switch ( SEM - 6008 ) is in open condition from switch yard .
KORBA SIMULATOR
78
8.
Close the 400 KV generator -6 bay’ breaker, incoming isolator (SEM-6006).
9.
Ensure all other isolators are in open condition.
10.
Line up the G.T. cooling water circuit from local .
11.
Switch on the generator transformer control supply for all the three phases from local Ensure that exciter air cooler isolating, hydrogen cooler isolating, stator water coolers are charged
12.
Switch on the control supply for both the unit auxiliary transformers by changing the status
13.
Ensure that GT/UAT cooler control system is in lined up condition
14.
Ensure that speed reference set point is zero.
15.
Ensure that turbine is kept on turbine follow mode with the minimum load limited about 100 MW on the coordinated control system insert.
16.
Ensure that trip oil pressure and start up oil pressure values are normal
OPERATIONAL STEPS 1.
Raise the starting device slowly to about 42 % .
2.
Ensure that start up oil pressure has decreased and at about 42 % of the starting device position the HP stop valves open.
3.
Further raise the starting device position to open the hot reheat stop valves.
4.
Checks the temperature of the turbine stop valves at 50 % depth and control valve temperature at 50 % and 100 % depth from TSE recorders.
5.
Keep the warm-up controllers in auto mode. The output of the controller will modulate to maintain the TSE margin for stop valves.
6.
Raise the starting device position to about 80 % and check that secondary oil pressure has build to open the control valves.
7.
Put the load gradient on from UCB console.
KORBA SIMULATOR
79
8.
Ensure the pressure controller deviation is on positive side.
9.
Ensure that drum level is on lower side to avoid sudden swing which may cause water carry over.
10.
Raise the speed reference to about 360 RPM from UCB.
11.
Check the uniform opening of control valves and turbine acceleration rate.
12.
Ensure that gate valve gearing has closed when turbine speed exceeds 240 RPM.
13.
Check that ‘Jacking oil pump’ has switch off at speed of about 540 RPM
14.
Check all the bearing temperature rise and bearing vibrations to be normal.
15.
Check the thrust bearing temperature and the differential expansions.
16.
Soak the turbine at the soaking speed till the HP shaft temperature at 50 % depth (Calculated) reaches to about 1800C with respect to existing main steam temperature as per the X curves.
17.
Check the TSE margin for various channels. First it will reduce and then gradually will increase once the difference between surface and mean temperature reduces.
18.
Raise the speed reference to 3000 RPM in one stroke.
19.
The turbine speed starts increasing opening of IP control valves can be seen at this stage.
20.
At speed of about 2960 RPM the AOP should be switched off as main oil pump takes over (ensure that SLC for all the oil pumps are on).
21.
Soak the turbine at 3000 RPM till IP shaft mean temperature (50 % depth) with respect hot reheat temperature as per the rolling X curves is satisfied.
22.
Check that a minimum of about 30 K margin should be available before unit is to be synchronised.
KORBA SIMULATOR
80
23.
Close the generator field breaker from AVR console.
24.
Raise the AVR set point to build the Generator voltage to about 21.5 KV
25.
Match the auto and manual set point of the AVR and transfer the AVR to auto mode.
26.
Ensure that load controller is on with load gradient kept at 20 MW/min.
27.
Turn on the synchroscope switch to check mode.
All the meters showing
incoming and running voltage and frequency energises. The synchroscope rate of rotation reflects the difference between incoming and running frequency. 28.
Adjust the voltage so that incoming and running voltage values are same.
29.
Adjust the turbine speed so that synchroscope is slowly rotating in clockwise direction showing incoming frequency is slightly higher than grid.
30.
Check the breaker closing permissive green lamp glows once synchroscope is between 11 to 12 O’clock position.
31.
Close the generator breaker when Gen. breaker closing permissive green lamp comes.
The synchroscope indicator locks at the 12 O’clock position.
The
generator breaker closed red lamp comes on. 32.
Immediately raise speed reference to pick up the load on the machine to avoid reverse power trip or low forward power trip.
33.
Increase the load as per the TSE margin and at the earliest close HP/LP bypass valves.
34.
Ensure that warm-up controllers have closed, otherwise close them manually.
35.
Close all the drains which were opened during rolling.
36.
Turn off the synchroscope switch to de-energise the synchroscope.
37.
Check that Prlim value slowly increase. point
Also ensure that load reference set
is higher than the actual load value.
KORBA SIMULATOR
81
38.
Observed that change over from speed controller to load controller takes place once output of load controller is greater than that of speed controller. The load controller active facia glows on the insert.
39.
Raise the starting device position to 100 %. Check the increase in auxiliary secondary oil pressure. Also ensure that tracking device is switched on.
40.
Increase the load limiter value to about 150 MW from insert
41.
Check the generator slot,core, exciter air and hydrogen cold gas temperatures
42.
Check from the multipoint selector switches, generator stator core temperature.
43.
Raise the HP bypass pressure set point to about 160 Kg/cm2 and temperature set point to about 3400 C to avoid HP bypass opening on auto.
44.
Ensure that LP bypass stop valves and spray valves have closed fully.
* Unit synchronised with load controller in service *
KORBA SIMULATOR
82
LP HEATER CHARGING OBJECTIVE • •
To line up LP heater from water side. To charge the LP heater from steam side.
PRE-REQUISITES & STATE OF PLANT 1.
Work permit on various LP heaters, drip valves, level gauges, water side valves, NRVs, etc., cancelled and men, material removed from these areas.
2.
The unit is synchronised and HP/LP bypass valves are closed.
3.
The instrument air is charged to various drip valves and valves are checked for the operation on auto.
4.
All the pressure gauges, local level gauges, root valves and various instrument impulses lines are charged or in service.
5. The 415 V power to various motorised valves are available. PRE-START CHECKS AND LINE UP 1. Check that LPH-1condensate inlet/outlet valves are in open condition and bypass valve is in closed condition. 2. Ensure all the shell side heater vents are in open condition represented 3. Check that all the isolating valves of the LP heater level controllers are full open for all the three heaters. 4. Charge the local level gauges for all the three heaters. OPERATIONAL STEPS 1. For LPH1 put the normal drain valve control switch to control mode from section. The valve starts modulating to maintain the LP heater level. 2. Check that LPH-2 condensate inlet/outlet valves are in open condition and bypass valve close.
KORBA SIMULATOR
83
3. Open the extraction steam isolating valve to LPH2. 4. De-energise the extraction NRV solenoid from ATRS console by pressing the left side push button. The NRV position starts increasing as the steam goes to LPH2. 5. Put the normal drain valve control switch to control mode.
The valve starts
modulating to maintain the LP heater level. 6. Check the condensate inlet / Outlet valves for the LPH3 are open and bypass valve closed. 7. Open the extraction steam isolation valve to LPH3 8. Put the normal drain valve control switch to control mode.
The valve starts
modulating to maintain the heater level. 9. De-energise the extraction NRV solenoid from ATRS console. 10. Check the condensate temperature after LPH-1,2,3. The temperature should gradually increase(in DAS ). 11. Close the heater vents from local .
* LP heaters charged *
KORBA SIMULATOR
84
TO TAKE PULVERISER INTO SERVICE OBJECTIVE • To line up start primary air fans. • To line up and start pulveriser. PRE-REQUISITES & STATE OF PLANT 1. Work permit on various pulveriser side equipment such as seal air fans and valves, pulveriser discharge valves, cold air damper, hot air gate and dampers, feeder, coal bunker mill reject system etc., cancelled and men, material are removed from these areas. 2. The equipment cooling water system is charged and all the coolers are in charged condition. 3. Atleast one set of ID fan and FD fan are running with furnace purging carried out. 4. FSSS start command to start the PA fan should be available. 5. Instrument air is charged to all cold and hot air damper actuators. 6. Primary air preheater is in service with air / gas dampers in open condition. 7. Auxiliary steam should be available for cold End temperature controllers. 8. Secondary air temperature should be adequate (about 2000 C). PRE - START CHECKS AND LINE UP 1. Check that adequate oil level is Ok. 2. Take any one primary RAPH in service and ensure the dampers are open. 3. Establish the equipment cooling water supply through the lub oil coolers for PA fan . 4. Line up the PA fan A lub oil circuit . 5. Rack in the 6.6 KV breaker for PA fan A.The green lamp in UCB glows.
KORBA SIMULATOR
85
6. Switch on the lub oil pump A for PA fan A and keep the selector switch of B in lead mode. Check auto interlocks of the lub oil pumps. 7.
Ensure that blade pitch is minimum and operative.
8.
Ensure that the control / lub oil pressure is adequate.
9.
Open the cooling water inlet valve to PA fan A and B .
10. Lub oil sump level for the pulveriser is normal. 11. The pulveriser discharge valves are open. 12. Open the cold air gate for all the pulverisers. 13. Ensure the tramp iron valve is open. 14. Start the lub oil pump for the pulveriser. 15. Check the lub oil pressure satisfactory permissive appears on the FSSS console. 16. Ensure that both the hot air damper and cold air dampers are operable from UCB. 17. Ensure the feeder inlet gate is open and corresponding permissive lamp is glowing in FSSS console. OPERATIONAL STEPS 1. Take the primary RAPH A in service similar to the secondary RAPH. 2. Give PA fan A start command 3. Ensure that outlet damper PAD-1 starts closing. 4. All the permissive will be available the moment discharge damper is closed the fan will take start. Check its starting and no load current. 5. Check that outlet damper for PA fan A reopens after a time delay and discharge damper for PA fan B closes on interlock. 6. Check the bearing temperature and vibration from UCB are normal.
KORBA SIMULATOR
86
7. Ensure that lub oil pump for PA fan B is running with standby pump in lead mode for both the fans. 8. Increase the blade pitch of PA fan A, and observe that PA fan A discharge pressure increases. 9. Bring the PA header pressure to about 800 mmwcl by raising blade pitch further. 10.
Improve the cold end temperature by charging the SCAPH.
11.
Ensure that 2 nos. of seal air fan are running, otherwise standby fan will get start command from the FSSS console.
12.
Open the pulveriser discharge valve by pressing the open push button.
13.
Ensure that the pulveriser mode is in manual.
14.
Check that ignition permit is available for the pulveriser to be taken into service and all 4 oil guns are in service.
15.
Ensure that the following pulveriser start permissives are satisfied. • Start permit (nozzle tilts horizontal and air flow less than 40 %). • Outlet temperature less than 93 0C. • Coal feeder in remote. • No auto unsuccessful start. • Pulveriser lub oil pressure satisfactory. • Tramp iron valve open. • Ignition permit. • Discharge valves open. • Cold air gate open. • Primary air permit. • No pulveriser trip command. KORBA SIMULATOR
87
• Feeder inlet gate open. 16.
Momentarily press the pulveriser start push button. The following events will occur. • The pulveriser seal air valve opens and red open light comes • Once seal air header to pulveriser under bowl differential pressure is more than 8 inch WCl, seal air pressure OK permissive comes • All the permissive on the console appear and pulveriser ready lamp glows. • Pulveriser ammeter pegs out to draw the starting current and comes down to no load value. • Pulveriser cold air damper opens 100 % and primary air flow to mill comes to 95 T/hr.
17.
Maintain the furnace pressure by raising the ID fan inlet guide vanes.
18.
Open the hot air gate by pressing the ‘Open ‘ push button. Hot air gate opens and
19.
red open lamp comes on.
Open the hot air damper and simultaneously decrease the primary air flow controller to maintain about 95 T/hr of primary air flow.
20.
Check the pulveriser outlet temperature increases gradually since hot primary air is going through the mill.
21.
Start the feeder by depressing the start push button. coal
22.
The feeder starts and
flow rate comes to approximately 12 T/hr
Increase the loading on the mill by raising the feeder speed and maintain the pulveriser outlet temperature to about 770 C.
23.
Check the furnace pressure and maintain it to about - 15 mmwcl by loading the ID fan.
24.
Increase the opening of the fuel air damper as per the feeder speed.
KORBA SIMULATOR
88
Start the feeder B 25.
Check that the fire ball scanners should start sensing flame and flame failure protection gets armed corresponding red lamp comes on
26.
Check the pulveriser bowl differential pressure and mill motor current and raise
27.
the coal feeding accordingly.
The drum level and other parameters are to be maintained during this operation.
28.
Electro Static Precipitator can be put in service, when coal firing has stabilised considerably in 3 to 4 mills.
* Pulveriser taken in service *
KORBA SIMULATOR
89
STEAM TEMPERATURE CONTROL OBJECTIVE •
To line up and charge superheater attemperation system.
•
To line up and charge reheater attemperation system.
PRE-REQUISITES & STATE OF PLANT 1.
Work permit on various attemperating side equipments such as block valve, control valves, impulse pipeline, isolating valves and associated piping cancelled and men, material are removed from these areas.
2.
Minimum one BFP is running with feed water charged upto the feed control station after HP heaters.
3.
Instrument air is charged to all the control valve actuators.
4.
Valve power is available to the SH attemperation/RH spray block valves.
5.
The boiler load (steam flow) is more than 30 % with drum pressure around 80 Kg/cm2
PRE-START CHECKS AND LINE UP 1.
Line up the SH attemperation circuit.
2.
Line up RH attemperation circuit.
3.
Check the trend of the main steam and reheat temperature rise during the load raising operation.
OPERATIONAL STEPS 1.
Open the SH attemperation isolation block valve S - 82.
2.
Open the SH outlet temperature controller LHS isolating block valve S - 83. The
3.
pressure equalising valve opens first and then main valve opens fully.
Open the SH outlet temperature controller RHS isolating block valve S - 86 similarly.
KORBA SIMULATOR
90
4.
Increase the controller output to about 10 % manually. Check the valve position indicator also goes 10 % open.
5.
Check that superheater spray water flow increases on recorder.
6.
Increase the controller output for the RHS also.
Check the valve position
indicator also goes up. 7.
Open the isolating block valve for the RH attemperation control R - 31
8.
Open the isolating valves for each left and right hand side reheater attemperation station R - 32 or R -33 and R - 34 or R - 35
9.
Reduce the burner tilt first by the controller, if the HRH temperature is rising rapidly.
10.
Increase the RH spray on LHS and RHS to maintain the HRH outlet steam temperature.
11.
Check the temperature variation in the recorders, which is a positive indication of spray flow.
12.
Check that rate of increase of SH and RH temperature should slow down, otherwise further raise the attemperation control valves to increase the flow rate.
Note 1 To control RH temperature, first the burner tilts should be used. The attemperation is to be used only in emergency condition.
* SH and RH attemperation is in service *
KORBA SIMULATOR
91
SUPERHEATER SPRAY CONTROL STATION
REHEATER SPRAY CONTROL STATION
KORBA SIMULATOR
92
CHARGING OF UNIT AUXILIARY TRANSFORMERS OBJECTIVE •
To charge 6.6 KV unit bus through unit auxiliary transformers.
PRE-REQUISITES & STATE OF PLANT 1.
Work permit on both the unit auxiliary transformers, associated system cancelled and men, material removed from the areas.
2.
The unit is in synchronised condition with load more than 75 MW.
3.
The unit auxiliary transformer cooler control system in lined up condition.
4.
Ensure that 6.6 KV unit Swgr Normal incomer breaker from UAT is reset.
5.
Ensure that UAT A / B control supply is on.
OPERATIONAL STEPS 1.
Turn the 6.6 KV Unit Swgr No. A, UAT-A incomer Syn. hand switch to check mode.
The synchroscope indicator locks up at 12 O’ clock position and
voltages for incoming and running are shown. 2.
Adjust the voltage of the incoming by changing the excitation set point from AVR
3.
console to match the running station supply voltage
Check the breaker closing permissive green lamp glows as soon as the voltage is matched (Keep the incoming slightly on higher side).
4.
Close the 6.6 KV unit Swgr 6A, UAT-A incomer breaker.
The breaker closes
and ammeter starts showing the current drawn. 5.
Open the 6.6 KV tie breaker.
6.
Switch off the synchroscope by turning it to off position.
7.
Check the UAT A winding temperature & oil temperature.
8.
Repeat the above procedure Sl.No. 1 to charge the Unit Auxiliary Transformer B also.
9.
Check the UAT- B winding temperature & oil temp..
** 6.6 KV buses charged from UATs **
KORBA SIMULATOR
93
LOAD RAISING OPERATION OBJECTIVE •
To remove oil support once coal firing is established.
•
To raise the unit load upto 50 %.
PRE - REQUISITES & STATE OF PLANT 1.
The unit load is about 75 MW with Unit Auxiliary Transformers charged.
2.
Three to four pulverisers are ready with all associated equipments.
3.
The superheater and reheater attemperation is lined up.
4.
Check that sufficient margin is available on TSE to raise the load.
5.
Raise the load limit on both EHG and CCS consoles to about 300 MW. OPERATIONAL STEPS
1.
Checks that the upper load margin in the TSE indicator and IPS temperature margin in TSE recorder are adequate to load the turbine further.
2.
Take two more pulverisers in service as per the standard procedure mentioned earlier.
3.
Increase the loading on all the three pulverisers equally and check for better combustion condition in the furnace.
4.
If oil elevations at AB/CD/EF are in service, then oil guns at EF elevation can be removed for economic operation.
5.
Depress the PAIR 1-3 stop’ push button on’ oil console at EF elevation.
6.
Check that the oil nozzle valve closes and associated ‘closed’ light comes on, spark rod of ignitor advances and sparks for 15 secs then retracts back.
7.
Ensure that oil gun at corner 1 and 3 retracts back once the 5 min scavenge operation of oil gun is complete.
8.
Repeat the same for the pair 2-4 also, check till both the oil guns retracts back.
9.
Reduce the heavy oil pressure.
10.
Increase the feeder speed for all the three feeders beyond 60 % and check the flame intensity at AB as well as BC should improve
11.
Raise the load reference on EHG control insert to pickup the load as the drum pressure increases.
12.
Maintain the SH and RH outlet temperatures by increasing the opening of the attemperation control valves or reducing the burner tilts.
KORBA SIMULATOR
94
13.
Change the set point of mill A outlet temperature and PA flow by turning the knob
14.
till it comes to 770C and 95 T/ hr respectively.
Check the error deviation of the controllers to be zero and transfer the controller in auto mode by pressing the middle A/M push button.
15.
Repeat the above operation for other pulverisers, watch the outlet temperature and bowl differential pressure.
16.
Keep the bias setter for all the three pulverisers at 1 .
17.
Raise the output of the fuel master till the error deviation in each feeder speed comes to zero. (Adjust the bias setter if loading is unequal.)
18.
Transfer all the feeders to auto mode and raise the fuel master output. All the three feeders will get loaded simultaneously.
19.
Keep on increasing the load set point as the parameters are building.
20.
Maintain the air flow / furnace pressure / wind box pressure as the firing is changing by adjusting the respective controls in UCB.
21.
Check
the
loading
of
the
auxiliaries
as
the
load
approaches
50
%
approximately.
* Unit load is brought to 50 % *
KORBA SIMULATOR
95
TAKING SECOND SET OF AUXILIARIES OBJECTIVE •
To start the second set of auxiliaries. •
To keep various control loops on auto.
PRE-REQUISITES & STATE OF PLANT 1.
Work permit on the second set of auxiliaries second stream of flue gas / secondary air and primary air ducts, etc., cancelled and men, material are removed from these areas.
2.
The unit load is about 50 % .Cold reheat pressure is more than 12 Kg / cm2 to start TD BFP.
3.
TD BFP and its associated auxiliary are normalised and a re available.
OPERATIONAL STEPS 1.
Keep the selector switch of second condensate pump in normal mode.
2.
Ensure the suction valve and recirculation valve of CEP- B are full open.
3.
Start the condensate pump B and observe that motor current is normal.
4.
Check the condensate pump discharge header pressure increases slightly.
5.
Adjust the set point of the recirculation controller and transfer the controller to auto mode.
6.
Start the TD BFP A Auxiliary oil pump A .
7.
Ensure that the BFPT-A Exhaust valve to condenser is open.
8.
Open the suction valve, recirculation isolation valve.
9.
Reduce the starting device to zero from BFPT governing console.
10.
Select the EHTC mode from the insert.
11.
Open the cold reheat steam to BFPT-A block valve Ex-20.
KORBA SIMULATOR
96
12.
Raise the starting device position to about 60 % to open the stop valve and further increase the speed of the BFP.
13.
Raise the speed reference to increase the BFP discharge pressure. Check that BFP suction flow also increases.
14.
Stop the motor driven boiler feed pump once the TD BFP is taken in service.
15.
Similarly line up and start the TD BFP B for load raising operation.
16.
Line up and start the ID fanB and balance the loading of both the fans.
17.
Line up and start the FD fan B and balance the loading of both the fans.
18.
Increase theoutput of fuel flow control master manually to increase the firing.
19.
Check that all the coal feeder loading has increased and pulveriser amps have increased.
20.
Adjust the output of the boiler master so that deviation on the fuel master and FD Fan blade pitch comes to zero.
21.
Transfer the FD controller in auto for a smooth change over and check that the air flow doesn’t change drastically.
22.
The boiler master can be used now to increase or decrease the load on the boiler. The unit may be kept in Boiler Follow mode with limit pressure mode in operation (after having kept first Fuel Master on Auto and then Boiler Master on Auto).
23.
Start PA fan B along with primary RAPH B.
24.
Take pulveriser D in service and load the feeder.
The coal flow in all three
pulveriser will reduce to compensate additional coal flow. 25.
Increase the Boiler Master output slowly to raise the firing if Boiler Master is kept
manual.
KORBA SIMULATOR
97
26.
The boiler temperature, pressure rapidly increases as a result of increased coal firing.
27.
Raise the load set point Pref.
check that opening of the HP control valve
increases. 28.
Increases the attemperation, if the rate of rise of SH and RH temperature becomes very high.
29.
Increase the maximum load limit set point on the CMC console as well on the EHG panel to about 500 MW.
30.
Adjust the furnace pressure set point to about -15 mmwcl and keep the bias setter to about 1 and transfer the controllers to auto mode.
31.
Remove the oil guns at CD elevation.
32.
Check that both the PA fans are equally loaded.
Raise the set point for PA
header pressure to about 800 mmwcl and set the bias setter to 1.0 by turning the knob. Transfer both the controller to auto mode after ensuring the control deviation is zero. 33.
Repeat the above step for FD fans; note that FD set point is generated by the Boiler Master.
* Second set of auxiliaries in service *
KORBA SIMULATOR
98
TDBFP SYSTEM KORBA SIMULATOR
99
LOAD RAISING OPERATION WITH CCS. OBJECTIVE •
To line up and take HP heater in service.
•
To raise the load to rated value.
PRE-REQUISITES & STATE OF PLANT 1.
Work permit on the HP heaters, drains, control valves, associated piping, etc., cancelled and men, material are removed from these areas.
2.
The unit load is around 50 % with both set of auxiliaries running.
3.
The boiler pressure is around 100 Kg /cm2.
OPERATIONAL STEPS 1.
Ensure that HPH both the streams are charged through water side i.e. HPH inlet
and outlet valves open with bypass valve closed.
2.
Open the extraction steam to HPH 5 block valve EX-008
3.
Open the extraction steam to heater 5A and 5B by opening EX-005 and EX-006 respectively.
4.
De-energise the FC NRVs from ATRS console.
5.
Turn the control switch of HP heater 5A and 5B drip to deaerator valve LCV0712, 034 to control position and release it.
6.
Check that the heater levels are normal and controller modulates to maintain level.
7.
Close the Extraction steam line drain valve after NRV, MSD-063
8.
Check that HPH 5A feed water outlet temperature increases.
9.
Check that HPH 5B feed water outlet temperature increases.
10.
In the same manner charge HPH 6A and 6B also. Check that drip control valve LCV-0701 and LCV-0723 maintains the HP heater level. KORBA SIMULATOR
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11.
HPH 6A and 6B outlet feed water temperature increases.
12.
Take two more pulverisers in service (preferably E and F in continuation) maintain their outlet temperature.
13.
Transfer the feeder control of the above pulverisers to Auto.
14.
Match the load demand signal to actual load by raising the unit master output from coordinated control system console.
15.
Ensure the load gradient to about 5 MW/min for better result.
16.
Increase gradually the throttle pressure set point above the actual pressure value by 2 to 3 Kg/cm2.
17.
Transfer the boiler master to auto mode. Check the output of the boiler master increases to maintain the set throttle pressure.
18.
Ensure the minimum load and maximum load set point are 50 and 500 MW respectively.
19.
Place the unit in coordinated mode.
The Unit control mode Coordinate facia
glows on the insert. 20.
Raise the Unit Master set point to about 350 MW.
21.
Watch all the unit critical parameters carefully and check that they are not going
22.
beyond limit.
Check that the generator reactive power is within limits as per the generator capability curve.
23.
Raise the throttle pressure set point gradully and check that the boiler firing rate
24.
also goes up.
Increase the Unit Master set point to 450 MW and check that sufficient upper margin for load raising is available.
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25.
Check that steam flow, air flow, fuel flow increases as a result of higher load set point as the unit is in Co-ordinated mode.
26.
Adjust the set point of the Reheater and Main steam temperature set points to 540 o C and transfer the spray controllers to auto mode.
27.
Watch the trend of main steam and reheat temperature, it may come down since
HP heaters are charged, however same shall be controlled as spray
controllers are in auto. 28.
Check the unit load limiter on both console is beyond 500 MW. Raise the unit master set point to 500 MW.
29.
Check that the control valve opening increases, load comes to 500 MW.
* Load raised up to 500 MW *
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CURVES FOR COLD START UP Time Min.
Activity
Main STM Press KG/SQCM
Main STM Temp. Deg. C
RH STM Press KG/SQCM
RH STM Temp. Deg. C
Turbine Speed RPM
Main STM Flow T/HR.
Gen Load MW
000
Start Ignitors/ Oil Guns
00
----
----
----
----
----
----
100
Open LP/HP Bypass
08
100140
----
----
----
----
----
315
Start Rolling
54
350
12
340
----
00
----
375
Syncronisation
54
350
12
340
3000
120
30
390
Close LP/HP BP
54
350
12
340
3000
200
50
400
Cut In 1-st Mill
60
350
15
340
3000
275
70
450
Cut In HP Heaters
85
375
20
370
3000
700
175
460
Cut In 2-nd. Mill
90
380
22
375
3000
740
190
480
Cut In 3-rd Mill
110
405
26
400
3000
820
270
510
Cut In 4-th Mill
125
430
30
425
3000
1020
320
550
Cut In 5-th Mill
150
450
34
450
3000
1300
400
600
Cut In 6-th Mill And Reach Full Load
170
475
40.5
475
3000
1600
500
660
Reach Rated Parameters
170
535
40.5
535
3000
1530
500
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CURVES AFTER 48 HRS SHUTDOWN Time Min.
Activity
Main STM Press KG/SQCM
Main STM Temp. Deg. C 130160
RH STM Press KG/SQCM
000
Light Boiler &
00
51
Charges HP/LP Bypass 180
Turbine Speed RPM
----
RH STM Temp. Deg. C ----
Gen Load MW
----
Main STM Flow T/HR. ----
365375
----
----
----
----
----
----
210
Start Rolling
60
400
12
340
----
----
----
219
Syncronisation
60
405
12
347
3000
140
----
225
Close HP/LP BP
60
407
14
355
3000
220
22
246
Cut In 1-st Mill
78
420
18
377
3000
460
110
264
Cut In HP Heaters
95
430
22
395
3000
680
185
270
Cut In 2-nd. Mill
100
435
24
400
3000
760
210
282
Cut In 3-rd Mill
112
442
26
415
3000
900
255
297
Cut In 4-th Mill
125
452
30
430
3000
1080
320
309
Cut In 5-th Mill
137
460
32
444
3000
1220
365
324
Cut In 6-th Mill
150
470
36
460
3000
1400
425
342
Reach Full Load
170
480
40
480
3000
1620
500
420
Reach Rated Parameters
170
535
40.5
535
3000
1530
500
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CURVES AFTER 8 HRS SHUT DOWN Time Min.
Activity
Main STM Press KG/SQCM
000
Light Boiler &
76
Charge HP/LP Bypass
Main STM Temp. Deg. C 415430
RH STM Press KG/SQCM
Turbine Speed RPM
----
RH STM Temp. Deg. C ----
Gen Load MW
----
Main STM Flow T/HR. ----
----
040
Cut In 1-st Mill
84
485490
----
----
----
----
----
046
Cut In 2-nd. Mill
86
495
----
----
----
----
----
050
Start Rolling
87
500
12
----
3000
----
----
056
Syncronisation
87
500
12
460
3000
130
----
060
Close HP/LP BP
87
500
14
465
3000
240
40
065
Cut In 3-rd Mill
96
500
20
480
3000
500
130
068
Cut In HP Heaters
106
500
22
485
3000
640
170
070
Cut In 4-th Mill
114
500
24
495
3000
740
210
073
Cut In 5-th Mill
124
500
26
500
3000
880
260
076
Cut In 6-th Mill
132
500
32
500
3000
1060
320
086
Reach Full Load
170
500
40.5
500
3000
1610
500
135
Reach Rated Parameters
170
535
40.5
535
3000
1530
500
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TURBINE START-UP CURVES WARMING-UP AND STARTING THE TURBINE TEMPERATURE CRITERIA
Fig: 1
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Fig: 2 RECOMMENDED MINIMUM CURVE (CURVE-A) AND MAXIMUM (CURVE-B) MAIN STEAM TEMPERATURE AHEAD OF TURBINE WHEN OPENING THE MAIN STOP VALVES.
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Fig: 3 ALLOWABLE MAXIMUM MAIN STEAM PRESSURE AHEAD OF TURBINE WHEN OPENING THE MAIN STEAM STOP VALVES.
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Fig: 4 RECOMMENDED MINIMUM MAIN STEAM TEMPERATURE AHEAD OF TURBINE BEFORE OPENING THE MAIN CONTROL VALVES
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Fig: 5 RECOMMENDED MINIMUM REHEAT TEMPERATURE AHEAD OF IP TURBINE BEFORE OPENING THE REHEAT CONTROL VALVES
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Fig: 6 RECOMMENDED MAXIMUM MAIN STEAM TEMPERATURE AHEAD OF TURBINE BEFORE THE TURBINE IS BROUGHT TO RATED SPEED
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Fig: 7 RECOMMENDED MAXIMUM MAIN REHEAT TEMPERATURE BEFORE TURBINE IS LOADED
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HOT START-UP PROCEDURE
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HOT START UP PROCEDURE Check the following conditions exist immediately after the Unit Tripping. Generator /Field Breaker are tripped. UAT’s Supply to Unit Buses are tripped and Station Supply takes over automatically. Generator AVR trips to manual mode. All the turbine Stop valves are closed. CRH NRV at HPT Exhaust closed. Turbine trip oil , Aux Sec oil & Secondary oil pressure became Zero. All the Feed Water Heaters Extraction Block valves are closed automatically. Drain before HP control valves are closed. Verify Main Turbine Aux.Oil Pump1 starts automatically (if SLC is on). Turbine Gate valve Gearing is opened automatically at 210 rpm(if SLC is on ). JOP1 starts automatically if at 510 rpm if SLC is on. Turbine Gate valve gearing is opened automatically at 210 rpm(if SLC is on). Drum, SH/RH pressures rise on interruption of steam to turbine. HP/LP by pass open, if on Auto with proper set points. Condenser vacuum breaker may open if tripping is because of fire protection or Axial shift. SH/RH attemperation Block valves are closed if spray control valves are less than 5% open. Drum level may sink. All mills & Feeders with both PA fans tripped. HFO trip valve may close as per oil gun logics. Furnace vacuum dips to very low value due to implosion.
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All wind box dampers open up after unit tripping. Stop one set of ID/FD fans to avoid forced cooling of the boiler.Stablise & maintain the draught & air flow. BOILER PURGE: Ensure all purge permissives are available & do furnace purging for 5 minutes. Boiler MFR (A&B) gets reset after a time delay of 5 minutes. The first cause of unit tripping gets reset along with the MFR reset. Deaerator: Ensure Deaerator pressure is maintained at 3.5 Kg/cm2 & auxiliary steam pressure is 14 Kg/cm2 Condenser: Establish condenser vacuum if it has deteriorated on protection. Turbo Generator reset: Reset Generator trip relay & Turbine trip. Starting device is brought to 0% and trip oil pressure comes to 6.8 Kg/cm2(approximately). Boiler Light up: Light up the boiler with the upper elevation oil guns and a mill or two is put in service if required to hold the temperature. Ensure that minimum stable fire is established in the boiler. Charging steam lines and heating: Open the following drain valves: 1.
Drain before ESV seats.
2.
Drain before IV seats.
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3.
MS strainer drain valves.
4.
MS header drain valves.
5.
HRH header drain valves.
6.
CRH header drain valves.
7.
Drain before Extraction NRVs and HPT exhaust NRV.
8.
Drain after control valves.
9.
HP casing drain.
10.
Drain before and after IP control valves.
HP/LP BP charging and temperature raising: Open HP Bypass valves so as to establish 15% flow through them,taking care to see that temperature control loop is funtioning normally. Ensure LP Bypass system is functioning normally on Auto.Adjust the fixed set point to 8 Kg/cm2. Steam flow thus established shall assist in heating Main Steam, Cold Reheat and Hot Reheat lines. HPBypass valves can further be opened to assist in increasing steam parameters. TURBINE ROLLING AND SYNCHRONISING: Turbine can be rolled to rated speed either by ATRS rolling or manual rolling through Electro Hydraulic Governor. The following conditions are to be checked before rolling. The turbine should be on barring gear(115 rpm). Condenser pressure is less than 0.5 Kg/cm2 At least one condensate extaction pump is on. Trip fluid pressure is more than 5 Kg/ cm2.
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Differential temperature between HP casing mid section top and bottom is less than 300C. Differential temperature between IP casing mid section top/bottom (Both front and rear) is less than 300C. HP control fluid temperature is maintained between 500C to 550C. Lub oil temperature after cooler is more than 350C.(38-470C) Degree of superheat of Main Steam before HP Bypass is more than midmetal temperature of H.P.Control valves. Main Steam pressure before turbine is function of
mid wall temperature of
H.P.Control Valves. Raise the Starting Device above 42% and then to 56%. 1) Verify that all ESVs have opened. 2) Verify that drains before HP Control valves are in Auto and these valves have opened. 3) Put Seal Steam controller on Auto. 4) Verify that the following Generator conditions are fulfilled. Any Generator bearing vapour Exhaust fan is on. Hydrogen Temperature controller is in auto. Hydrogen purity is more than 97%. Hydrogen pressure is more than 3 Kg/cm2. One Air side Seal oil pump is on. One Hydrogen Seal oil pump is on. Differential pressure between Seal oil Air side and Hydrogen side (both turbiine and Exciter end is more than 0.7 Kg/cm2)
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Turbine side prechamber level is low. Generator bushing box liquid level is low(less than 90mm) One Primary water pump is on. Primary water temperature controller is on Auto Primary water conductivity is less than 1.5 Micro mho/cm. Primary water flow is adequate (>13.3dm3/sec) Before Opening the control valves, verify the following: a)
The degree of Superheat of Main steam before turbine is more than 50°c.
b)
M.S.Temperature before turbine is more than either midwall temperature of HP casing or Simulated mid section temperature of HP Shaft.
c)
HRH temperature before turbine is more than simulated mid section temperature of IP Shaft.
During the warm up and hot start up of the turbine, observe the following parameters. •
Differential Expansions.
•
Axial Shift
•
Temperature difference between top and botttom of the HP/IP casings.
•
Bearing temperature and vibration.
•
Steam parameters.
•
TSE margin recorders for the following components HPS/HPC/IPS.
•
Operating parameters of condensing system.
•
Operating parameters of turbine oil & control fluid systems.
Maintain MS Temperaurte and Pressure at turbine inlet as per Start up Curve. Turbine Rolling Raise the speed set point so as to admit steam to steam to the turbine & Start rolling. Raise the speed to 360 rpm for warming up the casing.
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Verify that Gate valve gearing has closed. Close all the drains valves as mentioned earlier for warm up of steam lines. While admitting steam to the turbine, ensure that permissible wall temperature of limit curves are not exceeded. Hold the speed at 360 rpm for soaking purpose. Close the drains before HPCVs. Close the drains after HPCV if differential temperature between HPCV & Saturated steam is more than 50°C. Raise the speed to 3000 rpm provided the following parameters are with in the limits. a.
The Differential Expansion of the casing.
HP Turbine +5mm to -3mm b.
IP Turbine +8mm to -2mm
LP Turbine +30mm to -3mm
The differential temperature between the top & bottom of the casing less than + 450C.
c.
Bearing temperature and vibration are less than 900C and 45 microns respectively.
d.
HP Turbine exhaust hood temperature is less than 5000C.
AT 3000 rpm Verify that the following conditions are fulfilled. 1)
Both AOP’s are off.
2)
HRH temperature before LP bypass is greater than IP shaft mid metal temperature.
3)
Cold Hydrogen gas temperature is less than 450C.
4)
Main Exciter hot air temperaurte is less than 450C.
5)
Cold primary water temperature is less than 500C.
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6)
Cold Primary water flow through bushing is more than 0.37 dm3/sec and windings is more than 13.3 dm3/sec.
7)
Differential temperature between primary water & Hydrogen is more than 10C.
Synchronising and Load Raising: a)
Put AVR on Auto & Switch on field Breaker.
b)
Verify that Generator terminal voltage is 95%.
c)
Switch on the Synchroniser & synchronise the Generator with Grid when incoming Frequency, Voltage and Phase sequence match with the running system.
d)
Raise the Starting device and take a block load of 10% by raising Nref from AVR console/Turbine console.
e)
Close HP Bypass and check LP Bypass closes on Auto, when sliding set point is more than Hot reheat Pressure.
f)
Charge Unit Auxiliary Transformer to change over 6.6 KV supplies from Station to UAT.
g)
Raise the Turbine inlet Main Steam Pressure at the rate of 0.8 Kg/cm2 per minute up to Kg/cm2 at 25 % load and after wards at 1.65 Kg/cm2 per minute such that rated throttle pressure is achieved at 55 % load.
h)
Raise turbine inlet Main steam temperature at the rate of 1.60C /minute upto 485°C at 50% load.
i)
Close HP casing drain valve provided HP casing bottom temperature is more than
j)
3000C.
Verify that drains before HP Turbine exhaust NRVs have closed with the opening of
NRVs.Close the drains before and after IPCVs when difference
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between IPCV and Hot Reheat steam is more than 500C.Open the Extraction steam block valves to LPH 2, 3 & Deaerator. Main steam temperature can be raised at the rate 1.60C up to 4850C and at the rate of 0.60C above 4850C till it reaches 5400C. Raise the turbine load at the rate of 4 MW/min up to 125 MW. Verify that drain before LPH 2&3 closed when opening of respective extraction NRV is more than 15%. Verify that drain before Deaerator extraction line NRV closes when opening extraction NRV is more than 15% & differential pressure across NRV is more than
300mm wc.
Put Hot well level control and deaerator level control on auto. Above 20% Boiler Load Index, drum level three element control can be put on auto. Raise the Turbine load at the rate of 2 MW/min to 485 MW. AT 27% Turbine load, cut in the first mill and at 43% turbine cut in the second mill. AT 40% Turbine load, combustion controls can be put on auto. HP Heaters 5 & 6 can be taken into service. Around 50 % Turbine load, cut in the second set of Boiler and Turbine Auxiliaries such as I.D.Fan, F.D.Fan, P.A.Fan, Boiler Circulating Pump, Condensate Extraction Pump and the second Boiler Feed Pump. Mills are put in operation in the following sequence: No of mills
Turbine load
IIIrd
50%
IVth
60%
Vth
70%
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Vth
74%
Above 55% Boiler MCR,SH,RH temperature controls can be put on Auto. Between 50% and 75% load,maintain turbine inlet main steam temperature at 4850C. From 97% to 100% turbine load, raise the turbine inlet temperature at the rate of 0.60C per minute to 5350C.
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SHUT-DOWN PROCEDURE
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SHUTDOWN PROCEDURE TURBINE LOAD REDUCTION WITH COORDINATED CONTROL SYSTEM(CCS) OBJECTIVE •
To reduce the loading on the turbine for a planned shut down.
OPERATIONAL STEPS 1.
Ensure that unit is on coordinated mode with limit pressure mode in service and boiler master in auto mode.
2.
Check the load gradient is set at 5 MW/min on both the consoles.
3.
Reduce the unit master set point (load demand) to 400 MW.
4.
Take the attemperation control in manual mode and slightly raise the controller output to bring down the main steam and reheat temperature.
5.
Check that the load reference set point comes down and boiler master reduces its output to reduce firing.
6.
Reduce the AVR set point by pressing the lower button on AVR insert.
7.
Check that all the pulveriser coal flow reduced equally.
8.
Check that all HP control valve opening reduces and load come down to 400 MW.
9.
Gradually reduce the throttle pressure set point to about 130 Kg/cm2.
10.
Turn the burner tilts to lower side by decreasing the controller output.
11.
Check that fuel flow starts coming down followed by the air flow and steam flow.
12.
Check that the main steam pressure and cold reheat pressure also starts dropping.
13.
The
ESV
surface
temperature
starts
dropping
followed
by
the
mean
temperature, same is the case for the control valve also. 14.
Further drop the main steam and reheat temperature to cool the turbine. The points shown by the TSE 12 point recorder shows the decreasing trend.
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15.
Take unit on Turbine Follow Mode
16.
Stop the topmost pulveriser to reduce the firing.
Reduce the output of fuel
master manually. 17.
Close the extraction block valves to HP heater 6B and 5B from steam side. The valve starts closing, the drain control valve also starts closing since there is no steam flow to the heater.
18.
The boiler pressure increases momentarily then drops down as the feed water temperature has reduced.
19.
Further reduce the output of the fuel master to reduce the firing and steam temperatures.
Ensure that the unit is in turbine follow mode with initial
pressure control mode in service. 20.
The load will drop automatically in turbine follow mode to maintain the pressure set point.
21.
Stop one more pulveriser to reduce the firing.
Reduce the out put of fuel
master manually. 22.
Maintain the furnace pressure, boiler drum level and primary air header pressure during this transient.
23.
Check that HP casing temperature and HP shaft temperature (calculated) drops as per the main steam temperature.
24.
Check the flame intensity at elevation corresponding to running feeders and also the furnace pressure. * Unit load reduced to 75 % *
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PULVERISER SHUT DOWN OBJECTIVE •
To reduce the loading and take out the pulveriser in service.
OPERATIONAL STEPS 1.
Select the pulveriser which is at the top most elevation.
2.
Take the feeder speed control in the manual mode and reduce the loading of the feeder to minimum.
3.
Close the hot air gate from the FSSS console. Cold air damper opens 100 % and hot air damper closes fully.
4.
Check that mill outlet temperature drops rapidly and Mill current also comes down.
5.
Stop the feeder by depressing the feeder stop button.
The coal flow drop to
zero. The loading in other pulverisers will increase to compensate the lost coal supply. 6.
Wait till the pulveriser grinding current comes to no load current. Check that mill outlet temperature and bowl differential pressure comes down.
7.
Decrease the fuel air damper opening to almost close condition.
8.
Check that feeder voted light (no flame)comes once the feeder is stopped.
9.
Open the tramp iron gate to remove any rejects accumulated in pulveriser.
10.
Stop the pulveriser by depressing pulveriser stop push button. Check that the cold air damper closes full and mill air flow drops down.
11.
Maintain the PA header pressure to normal value.
12.
The pulveiser seal air valve will close on interlock.
13.
Close the pulveriser cold air gate from local.
14.
Close the pulveriser discharge valves by depressing the close push button from FSSS console.
15.
Close bunker gate (Silo gate) * Pulveriser taken out from service *
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LOAD REDUCTION AND HP/LP BYPASS OPERATION OBJECTIVE •
To reduce the load below 50 % and stop one set of auxiliaries.
•
To take HP/LP bypass in service to avoid oil support.
OPERATIONAL STEPS 1.
This step is in continuation with the operating instructions given earlier where the unit load is 75 % with four pulverisers.
2.
Check that the turbine pressure controller is active and unit is in turbine follow mode from coordinated control system CCS.
3.
Reduce the fuel input by decreasing the fuel master controller.
4.
Check the overall flame stability within furnace and the analog output of the scanner flame indication.
5.
Reduce the set point of AVR.
6.
Reduce the main steam temperature and hot reheat steam temperature by raising the attemperation flow.
7.
Reduce the throttle steam pressure set point gradually by lowering the S/P on coordinated control system console.
8.
Transfer the furnace pressure controller to manual mode and reduce the loading on one ID fan and load the other fan.
9.
Transfer the FD blade pitch control to manual mode and unload the FD fan corresponding to above ID fan which is unloaded .
10.
Maintain the furnace pressure and air flow during above operation.
11.
Stop one ID fan and one PA fan by giving a stop command from UCB control desk hand switch. The breaker opens, green off indication lamp comes.
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12.
Ensure the flame stability within the furnace, if necessary cut in the oil support. Three feeders with loading above 75 % may
not need the oil
support. 13.
Check that the inlet/outlet dampers of ID fan and discharge damper of the FD fan closes on auto.
14.
Adjust the HP bypass pressure set point to match existing throttle pressure.
15.
Transfer the initial pressure mode to limit pressure mode and reduce the throttle pressure set point to keep the deviation positive.
16.
Reduce the target load set (load reference) value from the governing console i.e., pr ref. & pr lim comes down at a rate set by the load gradient.
17.
Ensure that LP bypass controller is kept on auto with fix set point slightly below the sliding set point.
18.
As the throttle pressure increases on reduction of load the HP bypass valves will
open on auto causing the cold reheat pressure to go up.
Once this
pressure exceeds the sliding set point, LP bypass valves will also open. 19.
Further reduce the load set point from governing console.
Check that the
opening of HP bypass valves increases further. The hot reheat temperature can be controlled by controlling cold reheat temperature by HPbypass attemperation valves. 20.
Change over from unit supply to station supply for 6.6 KV A and B buses using synchroscope.
21.
Cut in oil support at AB elevation with minimum oil pressure to stabilise the flame.
22.
Transfer all the three running feeders to manual mode by pressing the middle switch and reduce the loading in one of the pulverisers.
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23.
Take out top pulveriser.
24.
Close the extraction steam block valves to LPH1, 2 & 3 once load has come below 20 %. Check that the drain control valve closes. Open the drains of the extraction line.
25.
Transfer the low load feed regulating station to auto mode and take the three element feed water control to manual mode.
26.
Stop one CEP also by giving a stop command from the UCB hand switch after opening the recirculation valve fully.
27.
Cut in one more oil elevation and maintain the oil pressure & temp.
28.
Change over the 16 ata header from existing unit by opening the tie valve.
29.
reduce the attemperation if the main steam temperature has come to around 3800C.
30.
Maintain the hot well, deaerator level during this transient operation. * Unit load reduced below 50 % with HP / LP bypass in service. *
TURBINE ON BARRING GEAR OBJECTIVE •
Putting turbine on barring gear
OPERATIONAL STEPS 1.
At about 540 RPM ensure that jacking oil pump takes start and jacking oil pressure comes to about 125 Kg/cm2.
2.
At about 210 RPM check that the barring gear valve starts opening and turbine speed is maintained to about 190 RPM.
3.
Open the HP casing drain manually after switching off the SLC.
4.
Open all the four drains upstream interceptor valve at valve seat.
5.
Open the main steam header drain valve
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6.
Open the drains upstream of ESV at valve seat
7.
Ensure the SLC drain for various drain valve in ‘ON’.
8.
Check the differential expansions of all the three casing within limits.
9.
Check the bearing temperature for all the bearing should start coming down.
10.
Stop one pulveriser and maintain the PA header pressure.
11.
Check that the seal steam pressure is maintained and condenser vacuum satisfactory.
12.
Reduce the fixed set point of LP bypass to maintain flow through reheaters. The opening of the LP bypass control valve increases.
13.
Reduce the attemperation controllers to minimum for SH and RH. * The turbine on barring gear *
BOILER SHUT DOWN OBJECTIVE • •
To trip the boiler and carry out the purging. To fill the boiler to highest drum level.
OPERATIONAL STEPS 1.
Ensure that unit status is safe.
2.
Take the HP/LP bypass valves in manual mode and reduce the opening of HP / LP bypass.
3.
Stop bottom pulveriser as per the instruction given earlier.
4.
Check that all the fuel air dampers close from top to bottom.
5.
Bring the burner tilt to horizontal position.
6.
Check that start permit is available, burner tilt horizontal and air flow less than
40 %.
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7.
Remove the oil guns at CD elevation by pressing pair 1-3 and 2-4 stop push buttons.
8.
Check that 5 min. scavenging operation is complete and gun retracts back.
9.
Remove the oil guns at AB elevation.
10.
The moment oil nozzle valve for 4th corner closes, the boiler will trip and loss of all fuel to furnace alarm will come.
11.
MFR tripped alarm comes. Both the MFR A/B relays trip red lamp comes.
12.
Check that HOTV closes and green lamp comes on.
13.
Bring the air flow to less than 40 % by FD fan blade pitch.
14.
Check that all the purge permissives are satisfied and purge ready lamp comes.
15.
Close the HP/LP bypass manually and increase the set pressure higher than the existing pressure.
16.
Push the ‘Push to purge’ switch from FSSS console. The purging light glows and
stays for 5 mins. and purge complete light comes once purging is over.
The MFR A and B relays reset. 17.
Wait till the fuel air damper starts closing from top. Maintain the air flow in between 30 to 40 %.
18.
Raise the BFP discharge pressure by raising the speed of BFP turbine.
19.
Open the low range feed control valve to start the drum filling . Check that the level in drum which will gradually increases.
20.
Stop the drum filling once all the ports of the hydrastep are indicating water (green lamps on). emergency
21.
Ensure that blow down valves are closed including
blow down.
Stop the HP dosing system from local.
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22.
Stop the boiler feed pump A by pressing the turbine trip push button. Check that
the EHC position drops to zero and control valve closes.
23.
Ensure that barring gear of the BFP turbine engages.
24.
Close the auxiliary steam block valve to TDBFP
25.
Stop the LP dosing pump from CSSAEP.
26.
Close the manual isolating valve to HP bypass desuperheating valve from local.
27.
Check that BFP discharge pressure and flow drops to zero.
28.
Close the equipment cooling water to MD BFP motor.
* Turbine on barring gear with boiler in tripped condition, drum filled upto the top *
SHUT DOWN OF AIR AND FLUE GAS SYSTEM. OBJECTIVE •
To stop the ID fans, air preheaters.
•
To stop the FD fans, scanner air fans.
OPERATIONAL STEPS 1.
Check the plant status with boiler in tripped condition and purging carried out.
2.
In manual mode reduce the FD fan blade pitch to 0 %. Check that the air flow reduces and generates an alarm below 30 %.
3.
Check that first cause of trip red flags comes on FSSS console as air flow is less than 30 %. Both the MFR trip and red lamp comes on.
4.
Stop the FD fan by turning the switch to OFF position.
5.
Check that the fan current drops down to zero and discharge pressure starts dropping down.
6.
Check that discharge dampers of both the fans open fully.
7.
Check that scanner fan emergency damper from atmosphere opens KORBA SIMULATOR
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8.
Stop the ID fan by turning the switch to OFF position .
9.
Check that the fan amps drops down to zero and inlet/outlet pressure decreases.
10.
Ensure that the dampers for all three fans GD-20 to GD-25 opens fully on interlock .
11.
Keep the lub oil pumps of all the fan running till the bearing temp. of the fans come down.
12.
Check that the flue gas temp. entering the air heater goes less than 120oC. Stop sec. RAPH A and B motor from UCB manually. [ Note that air motor will not take auto start.]
13.
Similarly stop the primary SCAPH A and B
14.
Keep open all the flue gas inlet/outlet dampers on air side as well as flue gas side in order to allow the natural air circulation for cooling.
15.
Check and close all air preheater cold end temp. controllers.
16.
Close the steam inlet valves to primary and secondary RAPH A and B.
17.
Stop the ash slurry pumps and bottom ash transport pumps.
18.
Ensure that ESP fields are not charged .
19.
Stop the DC scanner air fan from FSSS console, once the furnace is sufficiently cooled. * Flue gas and air path equipments taken out of service *
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SHUT DOWN OF TURBINE SIDE AUXILIARIES OBJECTIVE •
To kill vacuum and stop vacuum pumps.
•
To stop control fluid pumps.
•
To stop the turbine lub oil system
OPERATIONAL STEPS 1.
Check that the plant is in safe condition.
2.
Ensure that turbine is on barring gear with circulating water system in service. JOP should also be in service.
3.
Transfer the SLC drain to auto mode and check the drain valves are modulating
as per their logic.
4.
Stop the vacuum pump No. 1 from the oil console insert.
5.
Close the air isolation valve and hold the command till the valve is fully closed.
6.
Open the vacuum breaker from the insert. Check that vacuum falls rapidly.
7.
Take the gland seal steam controller to manual mode and close it fully. Open the gland seal steam drain valve fully.
8.
Close the block valve for seal steam supply to glands ASD-006.
9.
Stop the seal steam exhauster.
10.
Change the status of the vacuum pump ‘lined up’.
11.
Switch off the SLC of both the pumps .
12.
Stop the control fluid pump.Check that the pump current drops down to zero. The control fluid discharge pressure starts dropping.
13.
Switch off the HP control fluid heater No. 1 from the console insert.
14.
Isolate the control fluid cooler from water side by closing the inlet outlet valves and open the drain.
15.
Isolate the high pressure accumulator by closing the isolating valves. KORBA SIMULATOR
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16.
Close the high pressure and low pressure discharge valves.
17.
Check that turbine side temperatures (e.g. HP shaft, HP casing, IP shaft etc.) has come down below 75oC. from TSE recorder.
18.
Check that the differential expansions for all the three casing are within limit.
19.
Ensure from DAS and local also that turbine metal temperatures are below 75oC.
20.
Switch off the SLC of the gate valve gearing.
21.
Close the gate valve gearing by pressing the left side push button.
22.
Check that turbine speed gradually comes down.
23.
Once the turbine is stand still the jacking oil pump can be stopped.
24.
Switch off the SLC for jacking oil pumps.
25.
Switch off the jacking oil pump N0. 1 by pressing the left side push button. Check that the pump current drops down to zero.
26.
Purge the hydrogen from the generator and fill with the carbon di-oxide.
27.
Ensure that Hydrogen is removed before stopping the barring gear.
28.
Ensure that CO2 occupies the generator space. This can be checked from the CO2/O2 purity meter.
29.
De-pressurise the generator by removing the carbon dioxide. Ensure that no hydrogen cylinder is connected at gas filling header.
30.
Stop the seal oil pumps from local.
31.
Isolate seal oil cooling system from local.
32.
Close the stator water cooling system manual isolating valve from local. (Stator water running in bypass conditions)
33.
Stop the generator bearing chamber exhaust fan.
34.
Isolated the G.T cooling water circuit from local .
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35.
Switch off the SLCs of the AOP 1 & 2 and EOP. Check that left side amber lamp comes.
36.
Check from the local (exciter end) that turbine has come to stand still.
37.
Switch off the auxiliary oil pump. Check that the current drops down to zero.
38.
Ensure that lube oil pressure drop down slowly
39.
Check that EOP and AOP-2 do not take start as their SLCs are off.
40.
Isolate the turbine lube oil coolers from water side.
41.
Switch off the oil vapour extractor by pressing left side push button.
42.
Take the oil temperature controller in manual and close it.
* The condenser vacuum killed. Turbine / Control oil and lube oil system taken out of service. * SHUT DOWN OF CONDENSATE SYSTEM OBJECTIVE •
To stop the condensate pump this is in service.
•
To stop the make up pumps and associated system.
OPERATIONAL STEPS 1.
Check that the plant status is safe, with turbine side equipments stopped.
2.
Ensure that the Dea.
Level controller is in closed condition and in manual
mode. 3.
Close the block valve of the Dea. Level controller station CO-14 CO-17.
4.
Close the emergency make up controller as the condensate pump is running on recirculation only.
5.
Keep the selector switch of the CEP - B and C in normal position to prevent their
6.
auto start on low discharge header pressure.
Stop the CEP- A by turning the switch to stop position.
The CEP stops and
breaker off green lamp comes on. KORBA SIMULATOR
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7.
Check that CEP discharge flow and current comes down to zero.
8.
Ensure that discharge valves of all the three CEP should close.
9.
Check that vent valve on turbine oil system opens on auto as all the CEPs are off.
10.
Check that hotwell level is in steady state, if increasing then check the make up controllers, if open, close them.
11.
Ensure that all the recirculation controllers are full open and are in manual mode .
12.
Close the sealing line valve from common discharge from local .
13.
Ensure that condenser spill valve bypass and condensate fill valves are closed
14.
Rack out the breakers of CEP from swgr .
15.
Close the suction valve for all three CEPs from local .
16.
Close the ECW inlet and outlet valve of the CEP bearing oil coolers
17.
Close the GSC minimum flow isolating valve from local .
18.
Ensure that all the make up control valves along with there by-pass valves are in closed condition from UCB.
19.
Change the emergency make up pump control status from auto to manual .
20.
Stop the hotwell make up pump from local .
21.
Stop the emergency make up pump- A from DM plant .
22.
Check that make up flow to hotwell shows zero value. * Condensate pump taken out of service *
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SHUT DOWN OF CIRCULATING WATER SYSTEM. OBJECTIVE •
To stop the circulating water pumps and associated system.
OPERATIONAL STEPS 1.
Check that condenser vacuum is killed.
2.
Close the CW-inlet valve at condenser - A & B
3.
After a time delay gradually throttle the condenser outlet valve.
4.
Stop any one of the CW pumps. Both pumps should not be stopped as ARCW pumps are still running and the suction is taken from CW inlet duct.
5.
Check that the discharge valve of CW pump which is taken out of service closes.
6.
Stop the travelling water screen corresponding to CW pump which is off.
7.
If required open the water box vents on the condenser
Note : Both the CW pumps should not be taken out of service till the ARCW pumps are in service. * Circulating water system taken out of service* SHUT DOWN OF FUEL OIL SYSTEM. OBJECTIVE •
To stop heavy fuel oil pumps and associated system.
OPERATIONAL STEPS 1.
Close the oil temperature control valve to reduce the steam supply to HFO heaters.
2.
Close the short recirculation valve HO - 27 from UCB
3.
Stop one HFO pump from local .
4.
Check that HFO pressure drops slightly on UCB indicator
5.
Close the discharge valve of the HFO pump to isolate the HFO heater. KORBA SIMULATOR
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6.
Open the heater drain and vent after closing the steam valve to the heater.
7.
Repeat the above steps to take second pump out of service.
8.
Close the HFO delivery valve (HO - 18) and inlet to the firing floor (HO - 25) valves.
9.
Isolate the suction valves to both the pumps and drain the pump.
10.
Isolated the steam lines going to pump jacket and strainers.
11.
Stop the HFO tank heating if long shut down is expected.
12.
Isolate the auxiliary steam supply to the HFO pump house and open the various line drains. * HFO pump taken out of service *
SHUT DOWN OF ECW SYSTEM OBJECTIVE •
To stop the DMCW pumps and associated systems.
•
To stop the ARCW pumps and associated systems
OPERATIONAL STEPS 1. Check that the plant status is safe and no major auxiliaries running. 2.
Isolate the cooling water inlet valve to ID fan A/B/C.
3.
Isolate the cooling water inlet valve to FD fan A/B/C lub oil systems from local.
4.
Isolate the various auxiliary cooler and isolate the differential pressure regulators such as PCV-1145,PCV-1144 for BFP, CEP etc.
5.
Select the pump which is to be stopped from the selector switch.
6.
Stop one DMCW pump by turning the hand switch to off position.
7.
Check that the motor current drops down to zero and discharge pressure drops slightly.
8.
Close the pump discharge valve from CM-1101 of CSSAEP. KORBA SIMULATOR
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9.
Repeat the above steps to stop the second DMCW pump.
10.
Check that the discharge pressure & the motor current drops down to zero.
11.
Stop CW pumps from local .
12.
Keep the selector switch to off position for ARCW pump from CSSAEP
13.
Stop ARCW pump A by turning the switch to off position.
14.
Check that the current drops down to zero and main CW pressure at heat exchanger outlet drops slightly.
15.
Stop ARCW pump B also by turning the switch to off position.
16.
Close the discharge valves of ARCW pump A & B, both valve close and green lamp
comes on.
17.
Unit - 6 ARCW pump discharge header pressure low alarm comes in.
18.
Isolate the plate type heat exchanger by closing the inlet and outlet valves.
19.
Open the pump drain and vent valve to drain the pump.
20.
Close the suction valve of the ARCW pumps.
21.
Switch off the electrical power to the ARCW pump since the suction valve is closed.
• ARCW pump and ECW pumps taken out of service * • SHUT DOWN OF AUXILIARY STEAM SYSTEM. OBJECTIVE •
To isolate the 16 ata steam header and associated system.
OPERATIONAL STEPS 1.
Check that the plant status is safe with boiler in tripped condition and turbine auxiliaries taken out of service.
2.
Close the primary SCAPH A / B steam inlet valves if not done earlier.
3.
Close the auxiliary steam to burner atomising and HFO heating. KORBA SIMULATOR
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4.
Close the deaerator pegging steam valve from auxiliary steam, if open and ensure that pressurisation of D/A due to aux. steam does not take place any further.
5.
Reduce the auxiliary steam pressure controller output manually, if the auxiliary
Note :
steam is still through the cold reheat line.
Since the auxiliary steam header can be charged either from cold reheat line
or from unit 7 or also from the existing 20 MW aux. boiler should be isolated by closing the respective valve through which it is charged. 6.
Ensure that motorised isolating valves to TDBFP, ASL-004 and gland steam ASH-
006 are closed.
7.
Open the header drain valve AS-73 from local.
8.
Check that the temperature control valve is fully closed.
9.
Check that the auxiliary steam pressure shown by UCB indicator comes down to zero.
10.
Open various steam traps and drains for the atomising line and steam tracing line
11.
all over the
boiler.
Ensure that gland steam line drains from auxiliary steam are opened. * Auxiliary steam header isolated. *
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FURNACE SAFEGUARD AND SUPERVISORY SYSTEM
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FURNACE SAFEGUARD SUPERVISORY SYSTEM (FSSS) INTRODUCTION The Furnace Safeguard Supervisory System (FSSS) is designed to ensure the execution of a safe, orderly operating sequence in the start-up and shutdown of fuel firing equipment and to prevent errors of omission or commission in the following such as safe operating procedure. The system provides protection against malfunction of fuel firing equipment and associated air systems. The safety features of the system are designed for protection in most common emergency situations; however, the system cannot supplant the intelligent and reasonable judgement of the operator in all situations. In some phases of operation, the Furnace Safeguard Supervisory System provides permissive interlocks only to ensure safe start-up sequences of equipment. Once the equipment is in service, the operator must use normally acceptable safe operating practices. It is important that the operator is familiar with the overall operation of the unit and the operation of individual equipment, as outlined in the section “Unit Operating Procedures” and the various individual equipment sections in this manual. It is essential that all parts of the Furnace Safeguard Supervisory System are operable and in service at all times if the system is to provide the protection for which it is designed. Adequate maintenance and periodic inspection of the system and associated hardware is essential for its continued proper operation. This instruction section of the manual gives a complete description of the Furnace Safeguard Supervisory System furnished for this Unit as it relates to the various unit operating phases and the operation of the fuel firing equipment and associated air systems. Basically the system is designed to perform the following functions : a.
Prevent any fuel firing unless a satisfactory furnace purge sequence has first been completed.
b.
Prevent start-up of individual fuel firing equipment unless certain permissive interlocks have first been satisfied.
c.
Monitor and control proper component sequencing during start-up and shut down of fuel firing equipment.
d.
Subject continued operation of fuel firing equipment to certain safety interlocks remaining satisfied.
e.
Provide component status feedback to the operator and, in some cases to the unit control system and/or data logger.
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f.
Provide flame supervision when fuel firing equipment is in service and effect an elevation fuel trip or Master Fuel Trip upon certain conditions of unacceptable firing/load combinations.
g.
Effect a Master Fuel Trip upon certain adverse Unit operating conditions.
The method of accomplishing the logic in this unit is with C - E / Sulzer solid state logic system. There is a Logic Cabinet Assembly which contains control hardware in separate sections of the cabinet. Each section controls the following functions in the unit. 1.
Power Distribution section.
2.
Two sections for the unit.
3.
Each of the four oil elevation (AB,CD,EF and GH) has a section for the oil elevation and associated Safe Scan equipment.
4.
There are separate sections for each coal elevation (“A” thru “H”).
5
“Fireball” flame scanner section.
There is also a Unit Simulator panel assembly located on a swing panel in the Unit section. There are also four Oil Elevation Simulator panel assemblies. Each Simulator is located on a swing panel located in the associated oil elevation section. Each of the eight coal elevation sections has a Coal Elevation Simulator which is located on a swing panel in the associated coal elevation section. The Unit contains four (4) elevations of HEA ignitors, four (4) warm-up elevations and eight (8) coal elevations. Flame monitoring is accomplished with four (4) elevation of “Safe Scan” equipment and five (5) elevations of “Fireball” (Series 510) flame scanners. The “Safe Scan” equipment is used as discriminating flame scanner. This equipment is the Safe Scan 1-”Rear Access” model. OIL RECIRCULATION When all heavy oil nozzle valves are closed (PURGE PERMITS (White)”NOZL VALVS CLOSED” light is on), the heavy oil recirculation valve can be opened to head the heavy oil to obtain the proper viscosity for efficient combustion. This is accomplished by depressing the H.O. RECIRC. VLV “OPEN” push button. When the heavy fuel oil recirculation valve is moved from the closed position, the associated (red) “OPEN” push button is illuminated. The recirculation valve is proven KORBA SIMULATOR
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fully open when the associated (green) “ CLOSE” light goes off. When the recirculation valve is proven fully open, the heavy oil trip valve can be opened to heat the oil to the “proper” temperature (see “Heavy Oil Trip Valve Operation” section for specifics). The heavy oil recirculation valve can be closed by depressing the H.O. RECIRC. VLV “CLOSE” push button. The heavy oil recirculation valve is closed automatically when any heavy oil nozzle valve is not closed (PURGE PERMITS (WHITE) “ NOZL VALVES CLOSED” light goes off). UNIT START-UP FURNACE PURGE Before any fuel firing can take place (initially or following a boiler trip), a satisfactory purge cycle must be completed. All of the conditions listed below must be satisfied. To start a furnace purge cycle, proceed as follows: 1.
The A.C. and D.C. power requirements are satisfied when the following conditions are satisfied :
A.
Loss of ACS power for more than two seconds does not exit. The “LOSS OF ACS POWER” signal at the Data Logger is removed.
B.
Loss of customer 220 VDC Battery power for more than two seconds does not exist. The “LOSS OF 220 VDV> 2 SEC” signal at the Data Logger is removed.
C.
Loss of customer 220 VDC Battery power for more than two seconds does not exist.
The “LOSS OF UNIT CRITICAL POWER” signal at the Data Logger is removed. 2.
The “Mode Permit” signal is proven established when the PURGE PERMITS (white) “MODE PERMIT “ light is on.
3.
A “ Simulator Trip” signal does not exist. The “SIMULATOR TRIP” signal at the Data Logger is removed.
4.
Both “Drum level high” signals from the Acs or the HYDRA STEP do not exist for more than ten seconds. The “DRUM LEVEL LOW” signal at the Data logger is removed (See Note 1).
5.
Both “drum level low” signals from the Acs or the HYDRA STEP do not exist for more than ten seconds. The “DRUM LEVEL LOW” signal at the Data logger is removed (See Note 1).
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NOTE 1 When items 4 and 5 above are simultaneously satisfied, the PURGE PERMITS (White) “DRUM LVL. SATIS.” light comes on. 6.
When at least one boiler feed pump is not off, the “BOILER FEED PUMPS TRIPPED” signal at the Data Logger is removed.
7.
The “inadequate waterwall circulation” signal does not exit. The “INADEQUATE W.W. CIRCULATION” signal at the Data Logger is removed.
8.
Both P.A. (primary air) fans are proven off when the PURGE PERMITS (White) “P.A. FANS OFF” light is on.
9.
When at least one of the three (Induced Draft) fans are proven not off, the “All I.D. FANS OFF” signal at the Data Logger is removed.
10. When at least one of the two F.D. (Forced Draft) fan is proven not off, the “BOTH F.D. FANS OFF” signal at the Data Logger is removed. 11. When the air flow is greater than 30%, the “AIR FLOW < 30% TRIP” signal at the Data logger is removed and the PURGE PERMITS (White) “AIR FLOW > 30 %” light comes on. 12. The auxiliary air dampers are proven modulating on all nine elevations when the PURGE PERMITS (White) “AUX AIR DMPRS MOD” light comes on (See “Post Purge Excursion Protection” section for specifics. 13
The windbox to furnace differential pressure is proven satisfied when the PURGE PERMITS (White)”W/B FURN P SATIS” light comes on.
14
The Deaerator Level is “not low-low” when the “LOW/LOW DEAERATOR LEVEL” signal at the Data Logger is removed.
15
When all of the purge requirements are proven satisfied, the PURGE CYCLE (White) “PURGE READY” light comes on (See Note 2).
NOTE 2 If the light does not come on after items 1 thru 14 mentioned above have been satisfactorily completed, check to ensure that all of the following conditions are satisfied. A.
A “furnace pressure high trip” signal does not exist. The “FURN PRESS HIGH” signal at the Data Logger is removed.
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B.
A “furnace pressure low trip” signal does not exist. signal at the Data Logger is removed.
The “FURN PRESS LOW”
C.
The heavy fuel oil (H.F.O) trip valve is proven closed when PURGE PERMITS (White) “TRIP VLV CLOSED” light is on.
D.
The H.F.O nozzle valves on all four oil elevation are proven closed when the PURGE PERMITS (White) “NOZL VALVES CLOSED” light is on.
E.
The pulverizers on all eight coal elevations are proven off when the PURGE PERMITS (White) “PULVS OFF” light is on.
G.
All hot air gates are proven closed when the PURGE PERMITS (white) “HOT AIR GATES CL.” light is on.
H.
The flame scanners on all nine elevations indicate “no flame” when the PURGE PERMITS (white) “SCANRS NO FLAME” light is on
I
A “no boiler trip command” exists. This is indicated by the PURGE PERMITS (white) “ NO B.T.” light being on.
When items 2,11,15c,15d,15e,15f and 15h mentioned above are satisfied, a five minute counting period is started (see “ Post Purge Excursion Protection” section for specifics). After the “PURGE READY” light comes on, the furnace purge cycle can be started. The PURGE CYCLE (green) “ PUSH TO PURGE” light will also be on because a master fuel trip memory signal exists at MFT “ A” and/or MFT “B” (the (red))” MFT A TRIP” and /or “MFT A TRIP” and / or “MFT B TRIP” lights are on). The furnace purge cycle is started when the “PUSH TO PURGE” illuminated push button is momentarily depressed. This action will turn on the PURGE CYCLE (amber) “PURGING” light and start a five minute counting period. The “PURGING” light remains on during the entire counting period (see Note 3) NOTE 3 If the “PURGING” light goes off before the five minute counting period expires, this indicates that at least one purge permissive is no longer satisfied (item 1 thru 15 above). The purge permissive must be re-established (“PURGE READY” light is on) and another furnace purge cycle started by momentarily depressing the “ PUSH TO PURGE “ push button. When the five minute counting period expires (and the “PURGING” light remained on), a successful furnace purge cycle has been completed and the following events will now occur: 16
The PURGE CYCLE (yellow) “ PURGE COMPLETE” light comes on.
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17
The Data Logger receives a “PURGE COMPLETE” signal.
18 Two separate “no master fuel trip” memory signals are established, causing the following events to occur: A. B.
The (green) “MFT A RESET” and “MFT B RESET” lights come on. The (red) “MFT A TRIP” and “MFT B TRIP” lights go off.
C.
The PURGE CYCLE (green) “ PUSH TO PURGE” light goes off.
D.
The (amber) “PURGE “ light goes off.
E.
The “ boiler load greater than 30 %” memory is now “armed”.
F.
The “MFT A TRIPPED” and “MFT B TRIPPED” signals at the Data Logger are removed.
G.
The pulverizer’s and feeder’s can now be placed in the AUTO mode of operation, when it is deemed necessary
H.
The pulverizer’s and feeder’s can now be placed in service after other permissives are satisfied.
I.
The “trip primary air fans” signal is removed. The “TRIP P.A. FANS” signal at the Data Logger is removed.
J.
A five minute counting period is reset which allows the primary air (P.A.) fans to be started.
K.
A five second counting period is reset which will allow the “loss of fuel trip arming” memory signal to be established when other permissives are satisfied (see “Oil Elevation Start” section for specifics).
L.
All “cause of trip” memories are reset.
M.
The heavy oil trip valve can now be opened (see “Heavy Oil Trip Valve Operation” section for specifics).
HEAVY OIL TRIP VALVE OPERATION The heavy oil trip valve must be opened to heat the heavy oil before a furnace purge cycle is started and a “master fuel trip” exists (both (red) “MFT A TRIP and “ MFT B TRIP” light are on). This is accomplished by initially opening the heavy oil KORBA SIMULATOR
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recirculation valve (see “Oil Recirculation” section for specifics). When the heavy fuel oil recirculation valve is proven fully open, the heavy oil fuel trip valve can now be opened if all heavy oil nozzle valves remain closed (PURGE PERMITS (White) “NOZL VALVS CLOSED” light remains on). The heavy oil trip valve is energised to “open” when the H.O. TRIP VLV “ OPEN” push button is depressed. When the trip valve is moved from “closed” position, the (red) “OPEN” push button is illuminated. The trip valve is proven fully when the associated (green) “CLOSE” light goes off. The heavy oil is reciruclated so that the heavy fuel oil header temperature is satisfied. The heavy fuel oil supply pressure must also be satisfied. When these two conditions are satisfied, the heavy oil trip valve must be closed before a Furnace Purge can be started (see “Furnace purge” section, item 15c). When a “no master fuel trip” signal is established (both (green) “MFT A RESET” and “MFT B RESET” lights are on), the heavy oil trip valve can now be reopened if all of the following conditions are satisfied: 1.
All heavy oil nozzle valves remain closed (PURGE PERMITS (White)”NOZL VALVS CLOSED” light is on).
2.
The heavy fuel oil header temperature remains satisfactory.
3.
The heavy fuel oil supply pressure remains satisfactory.
The heavy oil trip valve is energised to “Open” when the H.O. TRIP VALV “OPEN” push button is depressed. when the trip valve is moved from “closed” position, the (red) “OPEN” push button is illuminated and the (white) “PURGE READY” light goes off. The “elevation trip” signal at all four oil elevations (AB,CD,EF and GH) is removed and the “elevation start permit” is now “ armed”. The heavy fuel oil trip valve can be closed by depressing the H.O. TRIP VALVE “CLOSE” push button. The heavy fuel oil trip valve will be closed automatically if any of the following conditions exist : 4.
Any heavy oil nozzle is not closed and a “master fuel trip” signal is established.
5.
After any heavy fuel oil nozzle valve is not closed and any of the following conditions exist for more than two seconds.
A.
The heavy fuel oil pressure is “low”, data logger receives a signal.
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- OR B.
The atomising steam pressure is “low”, data logger receives a signal. - OR -
C.
The heavy fuel oil header temperature is “low-low”, data logger receives a signal.
6.
Loss of critical power exists for more than two seconds.
HEAVY OIL ELEVATION “AB” START (Typical for Elevations CD,EF & GH) All heavy oil elevations (AB,CD,EF & GH) are placed in service in the same manner. The “oil elevation start permit” must initially be established. The permit was “armed” when a “no master fuel trip” signal was established and the heavy fuel oil trip valve was proven fully open. The “oil elevation start permit” will now be established when the following condition is satisfied (see Note 4): 1.
The air flow is greater than 30 % and less than 40%. - AND -
The nozzle tilts are horizontal. NOTE 4 When any feeder is “proven” (feeder is on for more than fifty seconds). item 1 above is no longer required to satisfy the “oil elevation start permit”. When the “oil elevation start permit” is established, the oil elevation can be placed in service in the “pairs” or “elevation” firing mode. The firing mode that is selected is automatically determined by the status of the feeders. The “pairs” firing mode is selected when all feeders are off for more than two seconds. The “elevation” firing mode is selected when any feeder is proven or an “auto start support ignition signal is established (see “Pulverizer Auto Start” section for specifics). The following sections describe the operation of these two different firing modes. Pairs Firing Mode Operation The “pairs” firing mode is automatically selected when all feeders are off for more than two seconds. Corners No. 1 and No. 3 are placed in service as one pairs. Corner No. 1 KORBA SIMULATOR
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is placed in service initially and thirty second later Corner No. 2 is placed in service initially and thirty seconds later Corner2& No. 4 are placed in service as one pair. Either pair can be placed in service initially. We will assume that corner pair 1-3 is placed in service initially. Both pairs are placed in service in the same manner. After the “oil elevation start permit” signal is established, the “corner Pair” can be placed in service in the following manner: 1.
Depress the PAIR 1-3 “START” push button (held depressed), the following events occur:
A.
The pair 1-3 “start memory” signal is proven established when the (red) “START” push button is illuminated and the associated (green)”STOP” light goes off.
B.
The “start corner No. 1” signal is established and the “start corner No. 3” signal is “armed”.
C.
The auxiliary air dampers in the associated oil elevation are closed.
D.
The “elevation back-up trip” memory signal is removed.
E.
the “unsuccessful start” memory signal is removed, if it was established.
F.
A thirty second counting period is reset.
G.
A seventy second counting period is reset.
2.
When the “START” push button is released, the following events occur:
A.
The thirty second counting period is started.
B.
The seventy second counting period is started.
Each of the four oil elevation corners are placed in service in the same manner after “start corner” signal is established. The corner no. 1 oil gun is placed in service after the “start corner No. 1” signal is established (see item 1.B. above), if all of the following conditions are satisfied: 3
The associated oil gun is engaged.
4
The associated scavenge valve is closed.
5
The heavy fuel oil isolation valve is proven open-and- the atomising steam isolation valve is open and the local control station the selector switch is proven in the REMOTE position when the LOCAL CONTROL STATION-COR. 1 (red) “REMOTE” light is on. KORBA SIMULATOR
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When these conditions (3 , 4 and 5) are satisfied simultaneously, an “advance oil gun” signal is established. The following events will now occur: 6
The associated high energy arc (HEA) ignitor “advance spark rod” signal is established if the associated corner discriminating flame scanner proved “no flame” (DISC FLAME SCANNER COR 1 (GREEN) “NO FLAME” light is on and the associated (red) “FLAME” light is off). When the HEA ignitor is moved from the “retracted’ position, the HEA IGNITOR - COR 1 (yellow) “ADVD” light comes on. The HEA ignitor is proven advanced when the associated (green) “RETRD” light goes off. The steam atomising valves “open” command is now “armed”.
7
A “scavenge incomplete” memory signal is established which removed the “retract oil gun” signal.
8
When the oil gun is moved from the retracted position, the following events occur:
A.
The OIL GUN COR 1 (red) “ADVD” light comes on.
B.
The “corner no. 1 shutdown” signal is removed.
9.
The oil gun is proven “advanced” when the OIL GUN COR 1 (green) “RETRO” light goes off. The following events will also occur :
A.
The HEA ignitors “spark” signal is now “armed”.
B.
The “corner trip” signal is removed, removing the heavy fuel oil nozzle valves “close” command.
C.
The associated steam atomising valve’s “open” command is now established and the “close” command is removed. The heavy fuel oil nozzle valve’s “open” command is now “armed”.
10. When the steam atomising valve is moved from the closed position, redundant signals are established to ensure that the “retract oil gun” signal and “corner shutdown” signals remain removed. 11. When the steam atomising valve is opened, the following events will occur : A.
The HEA ignitor “spark” signal is proven established when the HEA IGNITOR COR 1 (red) “SPARK” light comes and (see item 9. A. above).
B.
The heavy fuel oil nozzle valve’s “open” command is now established (see item 9.C. above)
12. When the heavy fuel oil nozzle valve is moved from the “closed” position, the following events occur: A.
The OIL VLV COR 1 (red) “OPEN” light comes on.
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B.
When the first heavy oil nozzle valve is not closed, the heavy fuel oil trip valve is closed if the automising steam pressure is “low” or the header pressure is “low” or the oil temperature is “low-low” for more than two seconds.
C.
A twenty five second counting period is started.
13. The heavy fuel oil nozzle valve is proven fully open when the OIL VALVE COR 1 (green) “CLSD” light goes off. 14. The corner oil gun proves flame when the DISC FLAME SCANNER COR 1 (red) “FLAME” light comes on and the associated (green) “NO FLAME” light goes off. When the twenty five second counting period expires (see item 12.C above), the HEA ignitors “spark” signal is removed and the HEA ignitor is retracted. 15. If the corner oil gun does not prove flame when the twenty five second counting period expires, the HEA ignitor’s “spark” signal is removed and the HEA ignitors “spark” signal is removed and the HEA ignitor is retracted and the heavy fuel oil nozzle valve is closed. 16. When the “heavy fuel oil flow satisfactory” signal is established and the heavy oil nozzle valve remains fully open, the associated corner No. 1 oil gun is proven “inservice”. When the thirty second counting period expires (see item 2.A. above), the “start corner No. 3” signal is established and the oil gun at corner No. 3 is placed in service in the same manner as the oil gun at corner No. 1 (starting with item 3 above). When the seventy second counting period expires (see item 2.B. above), a “corner trip’ signal is established if any of the following condition exist at the associated corner. 17. The corner oil gun does not prove flame. 18. The atomising steam valve is not open. 19. The heavy fuel oil nozzle valve is not fully open. Corner pair 2-4 are placed in service in the same manner as corner pair 1-3. When at least three of the four oil guns are “in-service” (heavy fuel oil nozzle valve is fully open a fuel flow is adequate at the associated oil nozzle valve), a “H.F.O. elevation in service” signal established. This is proven when the PULV START PERMITS (white) “IGNITION PERMIT” lights comes on at both adjacent coal elevations. When the seventy second counting period expires for either corner pair (1-3 or 2-4), the Data Logger’s “UNSUCCESSFUL SPARK ROD RETRACTION” signal is established if any HEA ignitor spark rod is not retracted on the associated oil elevations. The auxiliary air dampers “close” command is removed and the auxiliary air dampers on the associated oil elevation are positioned for “oil firing” when any of the following conditions occur: KORBA SIMULATOR
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20. Any heavy fuel oil valve is not closed on the associated oil elevation AND The “ elevation start” memory signal does not exist for both pairs (1-3 and 2-4). OR The seventy second counting period expires for both pairs (1-3 and 2-4). OR At least three of the four oil nozzle valves are proven fully open and fuel flow is adequate the associated oil nozzle valve. Elevation Firing Mode Operation The “elevation” firing mode operation is automatically selected when any feeder is “proven” or “auto start support ignition” signal is established (see “Pulverizer Auto Start” section for specifics). After the “oil elevation start permit” signal is established, the associated oil elevation is placed in service when the PAIR 1-3 or the PAIR 2-4 “START” push button is depressed and then released. The oil corner pair 1-3 are placed in service in the same manner as previously described in the “Pair Firing Mode Operation” starting with item 1 thru item 16. When the thirty second counting period expires, the “start corner No. 3” signal is established and the oil gun at corner No. 3 is placed in service in the same manner as the oil gun at corner No. 1. When the “start corner No. 3” signal is established, a thirty second counting period is started. Thirty seconds later, the pair 2-4 “ started “ memory signal is established. This is indicated by the PAIR 4 (red) “START” light coming on and the associated (green) “STOP” light going off. The second pair (2-4) are now placed in service in the same manner as pair 1-3. Corner No. 2 will be placed in service and then corner No. 4 will be placed in service after a delay of thirty seconds. When both seventy second “elevation pair” counting periods expire, the Data Logger will received “UNSUCCESSFUL START” signal for the associated oil elevation if a “HFO elevation in service” signal is not established for more than two seconds. A “ HFO elevation in service” signal does not exist when less than three of the four oil nozzle valves or the associated oil nozzle valve indicating “inadequate” fuel flow.
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PULVERIZER OPERATION All coal elevation ( A thru H) are placed in service in the same manner. The pulverizers can be placed in service manually or automatically. Both procedures are described in the following sections. Pulverizer ignition Permissives Prior to starting any pulverizer, the pulverizer ignition energy must be adequate to light off coal. The Pulverizer ignition energy is adequate (to support coal firing) for the coal elevation that is selected when the conditions listed below are satisfied. Pulverize “A” : 1.
An “elevation AB H.F.O. elevation in service” signal is extablished.
NOTE 5 A “ HFO elevation in service” signal is established when at least three of the four oil nozzle valves are proven fully open and fuel flow is adequate at the associated oil nozzle valve. OR 2.
Elevation B feeder is “proven” (feeder is on for more than fifty seconds) and the associated feeder speed is operating at greater than 50 % and the boiler load is greater than 30 %.
Pulverizer “B” : 1.
An “elevation AB H.F.O. elevation in service” signal is established (see Note 5). OR
2.
Elevation A or C feeder is “proven” and the associated feeder speed is operating at greater than 50% and the boiler load is greater than 30%.
Pulverizer “C” : 1.
An “elevation CD H.F.O. elevation in service” signal is established (see Note 5). OR
2.
Elevation B or D feeder is “proven” and the associated feeder speed is operating at greater than 50% and the boiler load is greater than 30 %.
Pulverizer “D” :
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1.
An “elevation CD H.F.O. elevation in service” signal is established (see Note 5). OR
2.
Elevation C or E feeder is “proven” and the associated feeder speed is operating at greater than 50 % and the boiler load is greater than 30 %.
Pulverizer “E” : 1.
An “elevation EF H.F.O. elevation in service” signal is established (see Note 5). OR
2.
An “elevation CD H.F.O. elevation in service” signal is established (see Note 5) and the elevation D feeder is proven and the associated feeder speed is operating at greater than 50 %. OR
3.
Elevation D or F feeder is “proven” and the associated feeder speed is operating at greater than 50% and the boiler load is greater than 30 %.
Pulverizer “F” : 1.
An “elevation EF H.F.O. elevation in service” signal is established (see Note 5). OR
2.
Elevation E or G feeder is “proven” and the associated feeder speed is operating at greater than 50 % and the boiler load is greater than 30 %.
Pulverizer “G” : 1.
An “elevation GH H.F.O. elevation in service” signal is established (see Note 5). OR
2.
An “elevation EF H.F.O. elevation in service” signal is established (see Note 5) and the elevation F feeder is proven and the associated feeder speed is operating at greater than 50 %. OR
3.
Elevation F or H feeder is “proven” and the associated feeder speed is operating at greater than 50 % and the boiler load is greater than 30 %.
Pulverizer “H” :
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1.
An “elevation GH H.F.O. elevation in service” signal is established (see Note 5). OR
2.
Elevation G feeder is “proven” and the associated feeder speed is operating at greater than 50 % and the boiler load is greater than 30 %.
The “pulverizer ignition permit” is proven established when the PULV START PERMITS (white) “IGNITION PERMIT” light comes on. The pulverizer on the associated coal elevation can now be placed in service after other permissives are satisfied. Pulverizer Ready Prior to starting a pulverizer, a “Pulverizer Ready” signal for the selected pulverizer must be established. This signal is established when all of the following conditions are satisfied: 1.
A “Pulverizer start permit” signal must be established. established when the following conditions are satisfied.
A.
The air flow is greater than 30 % and less than 40%.
B. C.
This signal is initially
The nozzle tilts are horizontal. A “no master fuel trip” memory signal remains established. The pulverizer start permit” signal is proven established when the PULV START PERMITS (white) “START PERMIT” light is on.
After any feeder is proven, items A & B above are no longer required to satisfy the “pulverizer start permit”. 2. The “primary air permit” signal is satisfied. There are two separate “pulverizer primary air permit” signals. One signal is used for pulverizers A,B,C and D. The other signal is used for pulverizers E,F,G and H. The “primary air permit” signal (for pulverizers A,B,C and D) is established when the following conditions are satisfied : A.
Both F.D. fan is on and both P.A. fans are on OR
At least one F.D. fan is on and at least one P.A fan is on and less than four pulverizers are on B.
The hot primary air duct pressure (for pulverizers A,B, C,D) is “not low”
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AND C.
The hot primary air duct pressure (for pulverizers A,B,C,D) is “not low-low”.
The “primary air permit” signal (for pulverizers E,F,G,H) is established when the following conditions are satisfied: D.
Same as “A” above AND
E.
The hot primary air duct pressure (for pulverizers E,F,G,H) is “not low” AND
F.
The hot primary air duct pressure (for pulverizers E,F,G,H) is “not low-low”. The “primary air permit” signal is proven established when the ‘PULV START PERMITS (white) “P.A. PERMIT” light comes on. After the associated pulverizer is on, the “primary air permit” is no longer required at pulverizer that is on.
3.
The pulverizer discharge valve must be opened. This is accomplished by depressing the DISCH VLV “OPEN” push button. When the discharge valve is moved from the closed position, the (red) “ OPEN” push button is illuminated. The discharge valve is proven open when the associated (green) “CLOSE” light goes off and the PULV START PERMITS (white) “DISCH VLV OP” light comes on.
4.
The pulverizer outlet temperature is proven less than 2000 F when the PULV start permits (white) “ OUTLET < 2000 F light comes on.
5.
At the pulverizer hydraulic journal system, the hydraulic pump control is placed in the REMOTE and AUTO positions. When this condition is satisfied, the PULV START PERMITS (white) “ JRNL CTRL PERMIT” light comes on.
6.
The feeder controller is proven in the REMOTE position when the PULV START PERMITS (white) “FDR IN REMOTE “ light is on.
7.
The cold air gate is proven open when the PULV START PERMITS (white) “COLD AIR GATE OP” light is on.
8
The tramp iron hopper valve is proven open when the PULV START PERMITS (white) “TRAMP IRON VLV OP” light is on.
9.
The feeder inlet gate is proven open when the PULV START PERMITS (white) “FDR INLET GATE OP” light is on.
10. A “ no automatic pulverizer unsuccessful start” memory signal is proven established when the PULV START PERMITS (white) “ NO UNSUC. START” light is on. This signal is established because the associated pulverizer if off. KORBA SIMULATOR
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11. The PULV START PERMITS (white) “LUB PRESS SATIS” light comes on when the pulverizer’s lube oil pressure has remained “not low” for more than five minutes. 12. The PULV START PERMITS (white) “SATIS LUB LVL & TEMP” light comes on when the lube oil sump level is adequate and the lube oil temperature is greater than 320C. After the pulverizer is on, this permissive is not required to keep the “pulverizer ready” signal established at the pulverizer that is on. 13. A “pulverizer trip” signal does not exist when PULV START PERMITS (white) “NO PULV TRIP” light is on (see “Pulverizer in Service” section for specifics). After item’s 1 thru 13 above are satisfied, the PULV START PERMITS (white) “PULV READY” light comes on. This indicates that the pulverizer an now be placed in service if the “pulverizer ignition permit” remains satisfied (PULV START PERMITS (white) “IGNITION PERMIT” light is on). The pulverizer can now be placed in service manually or automatically as described in the following sections. MANUAL START The associated pulverizer can be placed in service manually after the PULV START PERMITS (white) “IGNITION PERMIT” and “PULV. READY” light are on. The pulverizer is placed in the manual mode of operation by depressing the PULV MODE “MANUAL” push button momentarily. The “manual mode” memory signal is proven established when the (green) “MANUAL” push button is illuminated and the associated (red) “AUTO” light is off. The pulverizer can now be placed in service manually in the following manner: 1
Momentarily depressing the PULV “START” push button will establish a “pulverizer start” memory signal (see Note 6).
Note 6 A “pulverizer start” memory signal is also established if a “auto start pulverizer” signal is established“ . The following events will now occur: A.
The “pulverizer start” signal is now “armed”.
B.
The pulverizer seal air valve’s “close” command is removed and the “open command is established. The seal air valve is proven open when the SEAL AIR VLV (red) “OPENED” light is on and the associated (green) “CLOSED” light is off.
C.
The pulverizer hydraulic journal system’s hydraulic pump is placed in service. The pump is proven on when the JOURNAL PUMP (red) “ON” light is on and the associated (green) “OFF” light goes off. KORBA SIMULATOR
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D.
A ten second counting period is started.
2.
After the pulverizer seal air valve is opened and the seal air header to pulverizer underbowl differential pressure is proven greater than 8 inches w.c., the PULV START PERMITS (white) “SEAL AIR PRESS SAT.” light comes on. When this light comes on, the “pulverizer start” signal is established (see item 1.A. above).
3.
When the pulverizer is on, it establishes a “pulverizer on” memory signal. The following events will now occur.
A.
The PULV (red) “START” push button is now illuminated and the associated (green) “STOP” light goes off.
B.
The ten second counting period is reset (see item 1.D. above). If the pulverizer is not on when this ten second counting period expires, the pulverizer is tripped.
C.
The pulverizer discharge valve cannot be closed.
D.
The pulverizer seal air valve cannot be closed.
E.
The associated auxiliary air dampers cannot be closed.
F.
The hot air gate can now be opened.
G.
The feeder can now be started.
H.
The cold air dampers are opened to the “100% pulverizer air flow position” and the “run cold air dampers to < 5% open” signal is removed.
I.
The “close hot air damper” signal is removed.
J.
If the pulverizer lube oil pump is off, the Data Logger receives a “PULV LUBE OIL PRESS. LOW” signal. If this signal remains for more than ten seconds, the pulverizer is tripped.
K.
If the pulverizer air header to pulverizer underbowl differential pressure is less than 5 inch w.c., the Data Logger receives a “PULVERIZER SEAL AIR DP LOW” signal. If this signal remains for more than ten minute, the pulverizer is tripped.
L.
The pulverizer hydraulic journal system is now affected in the following manner.
a.
The Data Logger receives a “PULV JOURNAL HYDRAULIC LEVEL LOW” signal, if the hydraulic fluid level is low.
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b.
The pressure control system is activated.
c.
A 120 second counting period is started.
d.
When the journal hydraulic pressure is satisfactory, the associated feeder can be started.
e.
When the 120 second counting period expires, the Data Logger receives a “PULV. JOURNAL HYDRAULIC PRESSURE LOW” signal if the pressure is low. The associated feeder cannot be placed in service. Corrective action must be taken.
4.
After the pulverizer is proven on, the hot air gate should now be opened to establish the desired coal/air temperature at the pulverizer outlet.
The hot air gate will receive an “open” command after the HOT AIR GATE “OPEN” push button is depressed (see Note 7 ). NOTE 7 The hot air gate will also receive an “open” command automatically (after the pulverizer is on), if a “auto open hot air gate” signal is established. See Pulverizer Operation Auto Start” section. The following events will now occur : A.
When the hot air gate is moved from the closed position, the (red) “OPEN” push button is illuminated. The “ open cold air damper to 100 % pulverizer air flow position” signal is now removed.
B.
The hot air gate is proven open when the associated (green) “CLOSE” light goes off. The pulverizer temperature control will now receive a “release air and temperature control to AUTO” signal.
5.
It should be noted that the feeder can be placed in service in the MANUAL MODE of operation without opening the hot air gate.
6.
The feeder can now be placed in service, if the following conditions remain satisfied:
A.
“Pulverizer ignition permit” remains satisfied.
B.
The associated pulverizer remains on.
C.
The journal hydraulic pressure remains satisfied.
D.
A “no master fuel trip “memory signal remains established.
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E.
The “pulverizer ready” signal remains established.
F.
The pulverizer outlet temperature is greater than 130 F.
G.
The “feeder speed demand at minimum” signal is established because the feeder is off.
The feeder can now be placed in service. 7.
The feeder is now placed in service when the FEEDER “START” push button is held depressed. The following events will occur.
A.
The one hundred eighty “ignition permit required” counting period is reset.
B.
The five second “coal flow” counting period is started.
C.
If the feeder discharge chute is not plugged, the feeder “start” signal is established. The feeder is proven on when the (red) “START” push button is illuminated and the associated (green) “STOP” light goes off. The “feeder seal in “ signal is now established and the “START” push button can be released (after it is illuminated). When the push button is realised the 180 second counting period is started (see item A above).
8.
When the five second counting period expires (see item 7.B. above), the following events can occur :
A.
The Data Logger receives a “NO COAL FLOW” signal if the “coal on belt” signal does not exist.
B.
The feeder is tripped automatically if the following conditions exists.
a.
The “coal on belt” signal does not exist AND
b.
The pulverizer motor power is “low”
9.
After the feeder is proven on, the following events occur :
A.
A fifteen second counting period is started.
B.
A fifty second counting period is started.
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C.
A “feeder on” memory signal is established, the following events occur: a. The “run feeder speed demand to minimum” signal is now removed if pulverizer motor power “not high” and the pulverizer bowl differential pressure is “not high”. b. A three minute counting period is reset. c. A five second counting period is reset.
10. If the feeder goes off after it was on, the five second counting period is started (see item 9.C.c. above). The following events will occur which will minimize the possibility of a pulverizer fire, if the hot air gate is not closed. A.
The hot air dampers are closed.
B.
The cold air dampers are opened to the “ 100% pulverizer air flow” position.
C.
The pulverizer temperature control’s air and temperature control is removed from AUTO.
D.
A thirty second counting period is started. Thirty seconds later, the hot air gate is closed.
E.
When the hot air gate is closed, the hot air dampers “close” signal is removed if the pulverizer outlet temperature remains less than 2000F. The cold air dampers will remain in the “100 % pulverizer air flow “position.
11. When the fifteen second counting period expires (see item 9.A. above), the “include feeder in totalizing circuit” signal is established. 12. When the fifty second counting period expires (see item 9.B. above), a “feeder proven” memory signal is established and the following events occur: A.
The “release feeder speed to auto” signal is now established because the “run feeder speed demand to minimum” signal was previously removed (see item 9.C.a. above).
B.
If at least two of the four scanner indicate flame on the associated flame scanner elevation, the FIREBALL FLAME SCANNERS (red) “ELEV FLAME” light is on and the associated (green) “ELEV NO FLAME “ light is off.
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C.
When the feeder speed is increased above 50 %., a permissive is established which can established a “pulverizer ignition permit” signal (see “Pulverizer Ignition Permissives” section for specifics).
When the 180 second counting period expires (see item 7.C. above), this indicates that the feeder is established and the furnace flame has stabilized. The “Pulverizer ignition energy” that was initially required to support coal firing is no longer required (see “Pulverizer Ignition Permissives” section for specifics) and can now be removed. It is recommended that a minimum of two feeders be established at greater than 50% loading before the ignition support energy is removed (see “Operator Note” below). OPERATOR NOTE A signal feeder in service for more than fifty seconds at its minimum speed on approximately 25 % constitutes a “Fireball Established”. A signal “Fireball” results when an elevation is in service. Additional elevations placed in service merely enlarges this single “Fireball”. The established “Fireball” is monitored by the associated flame scanners. Only in an emergency situation would an operator select and start an elevation remote from one that is already in service. In this case, good operator procedure dictates that the second feeder be placed in service and “pulverizer ignition energy” be maintain unit both feeders are loaded to greater than 50 % before ignition energy is removed. When removing feeders from service, the inverse procedure should be followed. The “pulverizer ignition energy” should be reinstated when only two feeders are in service and operating at less than 50 % loading. Auto Start The associated pulverizer can be placed in service automatically after the PULV START PERMITS (white) “IGNITION PERMIT” and “PULV READY” lights are on. The pulverizer is placed in the automatic mode of operation by depressing the PULV MODE “AUTO” push button momentarily. The “auto mode” memory signal is proven established when the (red) “AUTO” push button is illuminated and the associated (green) “MANUAL” light is off. The pulverizer can now be placed in service automatically in the following manner : 1.
Momentarily depress the PULV “START” push button, the following events will occur:
A.
A 210 second” elevation start” counting period is reset and then started. KORBA SIMULATOR
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B.
The “auto start” memory signal is established.
C.
An “auto start support ignition” signal is established at the associated oil elevation. The oil elevation is placed in service in the same manner as previously described in the “Elevation Fire mode Operation” section, if the “oil elevation start permit” signal is established.
2.
When the “pulverizer ignition permit” signal is established (PULV START PERMITS (white) “IGNITION PERMIT” light is on) at the coal elevation being placed in service and both seventy second counting periods have expired, an “auto start pulverizer” and a “auto open hot air gate” signals are established. A sixty second counting period is now “armed”.
3.
The “auto start pulverizer” signal will now place the pulverizer in service in the same manner as previously described in the “Pulverizer Operation Manual Start” section starting with item 1 (see Note 6).
4.
After the pulverizer is proven on, the “auto open hot air gate” signal will open the hot air gate in the same manner as previously described in the “Pulverizer Operation Manual Start’ section, starting with item 4 (see Note 7)
5.
When the Pulverizer is on, the sixty second counting period is now started (see item 2 above when the sixty second counting period expires, an “auto start feeder’ signal is established for five seconds.
6.
After the hot air gate is proven open (HOT AIR GATE (green) “CLOSE” light is off) AND the “auto start feeder” signal is established, the following events will occur :
A.
The one hundred eighty “ignition permit required” counting period is reset.
B.
The five second “coal flow” counting period is started.
C.
If the feeder discharge chute is not plugged, the feeder “start” signal is established. The feeder is proven on when the FEEDER (red) “START” light is on and the associated (green) “STOP” light is off. The “feeder seal in” signal is now established. If the “feeder seal in signal is not established when the “auto start feeder” signal is removed (after five seconds), the feeder is tripped.
7.
The feeder is placed in service in the same manner as previously described in the “Pulverizer operation - Manual Start” section, starting with item 8. If this signal exists, the following events will also occur:
8.
The air and temperature control is removed from AUTO. KORBA SIMULATOR
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9.
The hot air dampers are closed.
10. The cold air dampers are opened to the “100 % pulverizer air flow” position. 11. The hot air gate is closed after a delay of thirty seconds. 12. When the feeder is off for more than three minutes, the associated pulverizer is stopped. Pulverizer in Service During normal operation as the unit load increases and decreases, the individual pulverizers share the load. When the average loading with pulverizers in service exceeds 80 %, an additional pulverizer should be placed in service. When the average loading with the pulverizers in service is reduced to less than 40 %, a pulverizer should be taken out of service. When pulverizer and associated feeder are in service, they are subject to the following operational checks : 1.
Any of the following conditions will run the feeder speed to minimum until the initiating condition is corrected:
A.
Pulverizer bowl differential pressure high.
B.
Pulverizer motor power high.
2.
Five seconds after the “feeder start” command is established, “no coal on belt” and “pulverizer power less than min. “will trip the feeder. The Operator should take appropriate corrective action, then restart the feeder. If the hydraulic oil pressure is inadequate, the feeder will be tripped.
3.
A high pulverizer outlet temperature (above 200 F) will close the hot air gates and open the cold air dampers to the “100 % pulverizer air flow” position after the air and temp. control are released form auto control. The high temperature signal will then close the hot air gate after a time delay of thirty seconds. (see Caution Note).
CAUTION A HIGH PULVERIZER OUTLET TEMPERATURE ON AN OPERATING PULVERIZER COULD BE INDICATION OF A PULVERIZER FIRE..
4.
Any of the following condition will cause an individual pulverizer to trip:
A.
Elevation power or Unit power is lost for more than two seconds.
B.
Any pulverizer discharge valve not open. KORBA SIMULATOR
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C.
Pulverizer on and seal air underbowl differential pressure is low (< 5" W.C.) for more than sixty seconds
D.
Pulverizer lube oil pressure is not on and associated pulverizer is on for more than ten seconds.
E.
Pulverizer lube oil pressure is “not adequate” and pulverizer is on for more than ten seconds.
F.
Pulverizer ignition energy not available when support ignition is required (before expiration of the three minute ignition time period).
G.
A “primary air trip” signal exists (see Note 8)
NOTE 8 A “primary air trip” exists when the following conditions exists at the elevations listed below: Elevations A,B,C,D: 1.
Any pulverizer is on AND All F.D. fans are off or all P.A. fans are off OR
2.
For Pulverizer A,B,C,D, the hot primary air duct pressure is “Low - Low” OR
3.
For Pulverizer A, B, C, D, the hot primary air duct pressure is “low” for more than five seconds. Elevations E,F,G,H:
4.
Same as item 1 above OR
5.
For Pulverizer E,F,G,H, the hot primary air duct pressure is “Low - Low” OR
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6.
For Pulverizer E,F,G,H the hot primary air duct pressure is “low” for more than five seconds. If at least five pulverizers are on and less than two F.D. fans are on or less than two P.A. fans are on, the following events occur:
7.
Pulverizer “H” is tripped immediately, then at two second intervals pulverizer G,F and E are tripped. After pulverizer “H” is tripped, the pulverizers will only be tripped until four pulverizers remain in service. The “primary air trip” signal is then removed. More than four pulverizers can only be placed in service when both F.D. and both P.A. fans are on. A “pulverizer trip” signal is proven established when the PULV START PERMITS (white) “NO PULV TRIP” light goes off.
UNIT SHUTDOWN When the unit is shutdown, the pulverizers should be removed from service and then the oil elevation are shutdown. PULVERIZER SHUTDOWN The pulverizers can be removed from service in the “manual” or “automatic” mode of operation. The loading should be reduced and then the pulverizer is shutdown. All coal elevations (“A” thru “H”) are removed from service in the same manner. The following sections describe both shutdown procedures. Manual Shutdown When the pulverizer is in the auto mode of operation (PULV MODE (green)”MANUAL” light is on and the associated (red) “AUTO” light is off), the pulverizer on the associated coal elevation is removed from service in the following manner: 1.
If the associated oil elevation is not in service, start the oil elevation.
2.
Reduce the feeder speed to minimum. This will automatically remove the feeder speed from AUTO control.
3.
Close the hot air gate by depressing the associated HOT AIR GATE “CLOSE” push button. The hot air dampers are closed, the air and temperature control is removed from AUTO control and cold air dampers are opened to the “100 % pulverizer air flow” position. Thirty seconds later, the hot air gate “close” command is established. When the hot air gate is moved from the fully open position the HOT AIR GATE (green) “CLOSE” light comes on. The hot air gate is proven closed when the associated (red) “OPEN” light goes off.
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4.
When the pulverizer outlet temperature is reduced below 130 F, shut down the feeder by depressing the FEEDER “STOP” push button. The following events will now occur:
A.
The “start feeder” signal is removed and two seconds later the “feeder seal in” signal is removed.
B.
The feeder is proven off when the (green) “STOP’ push button is illuminated and the associated (red) “START” light is off.
C.
The “feeder off” memory signal is established and the “feeder proven” memory signal is removed.
D.
The fifteen second counting period is reset which removes the “include feeder in totalizing circuit” signal.
E.
The fifty second “feeder proven” counting period is reset.
F.
A fifty second counting period is started. elevation of fuel air dampers are closed.
5.
Allow the pulverizer to run until it is completely empty of coal, then shut down the pulverizer by depressing the associated PULV “STOP” push button. The pulverizer is proven off when the associated (green) “STOP” push button is illuminated and the associated (red) “START” light is off. The pulverizer seal air valve is closed, the pulverizer hydraulic journal system’s hydraulic pump is shutdown and the pulverizer discharge valve can now be closed, if it is deemed necessary.
6.
The pulverizer discharge valve should be left open to allow air flow to exist through the pulverizer when it is not in operation.
7.
The associated oil elevation is shutdown once furnace conditions have stabilized (see “Oil Elevation Shutdown” section for specifics).
Fifty seconds later, the associated
Auto Shutdown When the pulverizer is in the auto mode of operation (PULV MODE (red) “AUTO” light is on and the associated (green) “MANUAL” light is off), the pulverizer on the associated coal elevation is removed from service in the following manner: 1.
Depressing the PULV “STOP” push button momentarily will cause the following events to occur simultaneously:
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A.
The “auto start” memory signal is removed.
B.
The “auto stop” memory signal is established.
C.
A ten minute “elevation stop” counting period is reset and then started.
D.
An “auto start support ignition” signal is established and the associated oil elevation is placed in service in the “elevation firing mode”.
2.
When the “pulverizer ignition permit” signal for the associated coal elevation is established (PULV START PERMITS (white) “IGNITION PERMIT” light is on) AND both seventy second counting periods have expired, the following events occur:
A.
A “run feeder speed demand to minimum “ signal is established which removes the feeder speed control from AUTO and reduces the feeder speed to minimum.
B.
A “auto close hot air gate” signal is established, causing the following events to occur:
a.
The hot air dampers are closed.
b.
The air and temperature control are released from AUTO control.
c.
The cold air dampers are opened to the “100 % pulverizer air flow” position.
d.
A thirty second counting period is started. Thirty seconds later, the hot air gate is closed.
3.
When the hot air gate is proven closed (HOT AIR GATE (red) “OPEN” light is off) AND the pulverizer outlet temperature is less than 130 F , an “ auto stop feeder signal is established.
4.
The feeder is now shutdown in the same manner as previously described in the “Manual shutdown” section , item 4.
5.
When the feeder is off, a three minute counting period is started. Three minutes later, a “auto stop pulverizer” signal is established.
6.
The pulverizer is now shutdown in the same manner as previously described in the “Manual Shutdown” section, item 5.
7.
When the ten minute counting period expires (see item 1.C. above). The Data Logger will receive a “UNSUCCESSFUL AUTO PULVE SHUTDOWN” signal if the following conditions are satisfied.
A.
The hot are gate is not closed OR
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B.
The feeder is on OR
C
The pulverizer is on.
8.
The pulverizer discharge valve can now be closed, if it is deemed necessary. The pulverizer discharge valve should be left open to allow air flow to exist through the pulverizer when it is not in operation.
9.
The associated oil elevation is shutdown once furnace conditions have stabilized.
OIL ELEVATION SHUTDOWN All oil elevation (AB, CD,EF,GH) are shutdown in the same manner. The oil elevations can only be shutdown manually. The oil elevation can be shutdown if the “elevation” firing mode exists or if the “pair” firing mode exists. The shutdown procedure for both firing modes is described in the following sections. “Pair” Firing Mode Shutdowns If all feeders are off for more than two seconds, the “pairs firing mode is automatically selected. When “pairs” firing mode is selected, either pair (1-3 or 2-4) can be initially removed from services. Both pairs are shutdown in the same manner. Initially, it is assumed that pair 1-3 will be shutdown. This pair is shutdown in the following manner: 1.
Momentarily depress the PAIR 1-3 “STOP” push button, the following events will occur simultaneously:
A.
The “pair stop” memory signal is proven established when the (green) “STOP” push button is illuminated and the associated (red) “START” light is off.
B.
A thirty second counting period is reset and then started.
C.
A 340 second counting period is reset and then started.
D.
The “stop corner No. 1” signal is established.
E.
The “stop corner No. 3” signal is “armed”.
2.
Corner No. 1 is shutdown in the following manner after “stop corner No. 1” signal is established.
A.
The heavy fuel oil nozzle valve at corner No. 1 receives “close: command.
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B.
When the oil nozzle valve is moved from the fully open position, the OIL VALVE COR 1(green) “CLSD” light comes on. The oil nozzle valve is proven closed when the associated (red) “OPEN” light goes off.
3.
When the oil nozzle valve is proven closed, the steam scavenge valve receives an “open” command and the steam automizing valve receives a redundant “open” command (atomizing valve is open). The HEA ignitor “spark rod” receives an “advance” signal for fifteen seconds.
4.
When the HEA spark rod is moved from the retracted position, the HEA IGNITOR COR 1 (yellow) “ADVD” light comes on. The HEA spark rod is proven advanced when the associated (green) “RETRO” light goes off. The spark rod is now energized. When the fifteen second counting period expires, the “spark” is extinguished and the spark rod is retracted.
5.
The steam scavenge valve is proven fully open when the OIL VALVE COR 1 (white) “SCAV” light comes on. A five minute counting period is now started.
6.
When the five minute counting period expires, a “scavenge complete” memory signal is established. This signal causes the following events to occur:
A.
The (white) “SCAV” light goes off and the steam scavenge valve is closed.
B.
A “corner trip” signal is now established because the associated corner discriminating flame scanner indicates “no flame” (DISCR FLAME SCANNER COR 1 (green) “NO FLAME” light is on and the associated (red) “FLAME” light is off).
7.
The “corner trip” signal sends redundant “close” signals to the heavy fuel oil nozzle valve and the steam scavenge valve to reinsure that they are closed. A “close” command is now established at the steam atomizing valve.
8.
When the steam atomizing valve is closed, the oil gun receives a “retract” signal.
9.
When the oil gun is moved from the advanced position, the OIL GUN COR 1 (green) “RETRD” light comes on and a redundant “ corner trip” signal is established to ensure that the fuel oil, steam atomizing and scavenge valves are closed.
10. The oil gun is proven retracted when the associated (red) “ADVD” light goes off. The “scavenge incomplete” memory signal is now reestablished and a “corner shutdown” signal is now established for corner No. 1. The oil gun at corner no. 1 is now successfully shutdown. When the thirty second counting period expires (see item 1.B. above) , the “stop corner No. 3” signal is now established which was previously “armed” (see item 1. E. above). Corner No. 3 oil gun is now shutdown in the same manner as previously described for the oil gun at corner No. 1 starting with item 2 above.
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When corner No. 1 and No. 3 were shutdown and the 340 seconds counting period expires (see item 1.C. above), the “elevation stopped and time expired” signal is “armed”. The second corner pair (2-4) are removed from service in the same manner as corner pair (1-3) when the PAIR 2-4 “STOP” push button is momentarily depressed. The oil gun at corner No 2 is removed from service and thirty seconds later corner No, 4 is removed from service in the same manner as previously described for corner No. 1. When the 340 seconds counting period for corners 2-4 is also expired, the “elevation stopped and time expired” signal that was previously “armed” is now established. The following events will now occur: 11. The Data logger receives a “UNSUCCESSFUL FUEL OIL ELEV. SHUTDOWN” signal if the corner shutdown” signal was not established at any of the four corners (see item 10 above). 12. The Data Logger receives a “UNSUCCESSFUL SPARK ROD RETRACTION” signal if any of the four corner HEA ignitor spark rods were not retracted (HEA IGNITOR COR (yellow) “ADVD” light is on). 13. An “elevation back up trip” memory signal is now established which establishes redundant “corner trip” signals at all four corners on the associated oil elevation. The auxiliary air dampers on the associated oil elevation can now be closed if other permissives are satisfied. “Elevation” Firing Mode Shutdown If any feeder is “proven” the “elevation” firing mode is automatically selected. If any feeder remains “proven” when the oil elevation is removed from service, the associated oil elevation is removed form service in the following manner: 1.
Depressing the pair 1-3 or the PAIR 2-4 “STOP” push button momentarily will cause the following events to occur:
A.
Corner pair 1-3 are removed from service in the same manner as previously described in the “Pair. Firing Mode Shutdown” section, starting with item 1 and through item 10.
B.
When the “stop corner no. 3” signal is established, corner no. 3 is removed from service and simultaneously a thirty second counting period is started.
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C.
When the thirty second counting period expires, a corner pair 2-4 “stop” signal is established. Corner No. 2 is then removed from service and then corner No. 4 is removed from service after a delay of thirty seconds. All four corners are removed from service in the same described in the “Pair Firing Mode Shutdown” section.
manner as previously
CORNER SHUTDOWN Any corner oil gun can be removed from service at the corner local control station. IF the associated corner atomizing steam isolation valve remains open, a “stop corner” signal can be established when the selector switch at the local control station is placed in the “SCAVENGE” position. This is indicated by the LOCAL CONTROL STATION COR (white) “SCAV” light coming on. The “stop corner” signal is now established and the associated corner oil gun is removed from service in the same manner as previously described in the “Pair Firing Mode Shutdown” section starting with item 2. If the local control station selector switch is placed in the “OFF” position, the LOCAL CONTROL STATION COR (green) “OFF” light comes on. A “corner trip” signal is established and the oil gun is shutdown without scavenging. The oil gun must then be retracted by another procedure. BOILER TRIP A “boiler trip’ command stops all fuel inputs by tripping all of the pulverizers and feeders and closing all heavy oil nozzle valves on all elevations. There are two separate “boiler trip” commands in this unit. Both “no boiler trip” command signals must be established before a furnace purge cycle can be initiated. A “boiler trip” command will establish a “master fuel trip” memory signal. This is indicated by the (red) “ MFT TRIP” light being on and the (green) “MFT RESET” light being off. When a “master fuel trip” memory signals established (red, “MFT TRIP” light is on), the following events occur: 1.
The (red) “MFT A TRIP” and MFT B TRIP” lights come on and the associated (green) “MFTA RESET” and “MFT B RESET” lights go off.
2.
The Data Logger receives a “MFT A TRIPPED” AND MFT B TRIPPED” SIGNALS.
3.
The “boiler load greater than 30 %” memory signal is removed. When the “master fuel trip” memory signal is established (red, “MFT A TRIP” or MFT B TRIP” LIGHT IS ON), the following events occur:
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4.
Both of the (red ) “BOILER TRIP” light come on and the “PUSH TO PURGE” AND “PURGING” light are “armed”.
5.
The PULV MODE (green) “MANUAL” light comes on, if it was off.
6.
All pulverizers are tripped as indicated by the PULV START PERMITS (white) “NO PULV TRIP” lights going off.
7.
A five minute counting period is started. Five minutes latter, all cold air dampers are opened to the “100 % pulverizer air flow position”.
8.
The “permit to start P.A. fans” signal is removed.
9.
The “oil elevation trip” memory signal is established at all oil elevations.
10. If all heavy fuel oil nozzle valves are not closed, the heavy fuel oil trip valve is closed. The heavy fuel oil trip valve can then be reopened after all heavy fuel oil nozzle valves are closed and the heavy fuel oil recirculation valve is opened. 11. A five second counting period is started. Five seconds later, the “loss of fuel trip arming” signal is removed. 12. The CAUSE OF TRIP memories cannot be reset. 13. All feeders are shutdown. 14. The upper and lower fuel air dampers are opened. 15. The auxiliary air control is transferred to MANUAL control and all auxiliary air dampers are opened. 16. The primary air (P.A.) fans are tripped. 17. The “feed forward to furnace draft control” signal is established for thirty seconds if the following conditions are satisfied: A.
The unit critical power is available for more than six seconds AND
B.
The “loss of fuel trip arming” signal is established.
When this signal is established, item “B” is no longer required to keep this signal established. Thirty seconds later, the “feed forward to furnace draft control” signal is removed. 18. The furnace pressure recorder changes to a higher speed for thirty seconds.
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When the thirty second counting period expires, the furnace pressure recorderwill remain at the higher speed if a “high furnace pressure alarm” or a “low furnace pressure alarm” signal is established. When both of these signals do not exist for more than thirty seconds, the furnace pressure recorder reverts to its original speed. The recorder will revert to the higher speed if either of these signals are reestablished. A “boiler trip signal is established if any of the following conditions exist: 19. Loss of ACS power for more than two seconds. 20
Loss of customer’s 220 VDC Battery power for more than 2 ) seconds.
21. Loss of unit critical power for more than two seconds. 22. A “simulator trip” signal exists. 23. The water drum level is “low” for more than ten seconds. 24. The water drum level is high” for more than ten seconds. 25
All boiler feed pumps are off.
26. “Inadequate waterwall circulation” signal exists. 27. All I.D. (Induced Draft) fans are off. 28. ALL F.D. (Forced Draft) fans are off. 29. The air flow is less than 30 % before the boiler load exceeds 30 %. 30. The deaerator level is “low-low”. 31. At least two of the three pressure switches indicate a “high furnace pressure trip” condition. 32. At least two of the three pressure switches indicate a “low furnace pressure trip” condition. 33. Both BOILER TRIP (emergency) push buttons are depressed simultaneously. 34. All feeders are off and loss of power exists at the elevation that is in service. 35. A loss of reheat protection occurs. 36
A “loss of fuel trip” signal is established (see Note 9). KORBA SIMULATOR
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NOTE 9 The “loss of fuel trip” signal becomes “armed” when the first oil elevation that is placed in service has at least three of the four heavy oil nozzle valves proven fully open (OIL VALVE COR (green) “CLOSED” lights are off). After the “loss of fuel trip” signal is “armed”, a “loss of fuel trip” signal will be established if all of the following conditions occur simultaneously: A.
At all coal elevation, the feeder is off or loss of elevation power exists. condition exists for more than two seconds
This
AND At all four oil elevations all oil nozzle valves are closed or an “elevation trip” signal is established at the associated oil elevation. The “loss of fuel trip” signal is proven established when the receives a “LOSS OF ALL FUEL TRIP” signal. B.
Data Logger
At all coal elevations, the feeder is off or loss of elevation power exists. condition exists for more than two seconds.
This
AND The heavy fuel oil trip valve is not fully open AND At all four oil elevations, all oil nozzle valves are closed. When the “master fuel trip” memory signal exists for more than five seconds the “loss of fuel trip arming” memory signal is removed. The Data Logger’s “LOSS OF ALL FUEL TRIP” signal will remain established if item B above is satisfied. When the heavy oil trip valve is proven fully open (for oil recalculation), this signal is removed. 37. A “unit flame failure” signal is established (see Note 10). NOTE 10 During light off and before any feeder is “proven” for more than two seconds, the “fireball” flame scanners do not take part in the overall flame failure protection systems. When any feeder is “proven” for more than two seconds, the system automatically changes from flame failure protection of an individual fuel nozzle to a
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“FIREBALL” supervision of the furnace. The system is designed to initiate a “boiler trip” when any feeder is “proven for more than two seconds and all five fireball flame scanner elevations vote “no flame” simultaneously. After any feeder is “proven” for more than two seconds, the UNIT FLAME FAILURE (amber) “ARMED” light comes on. After this light is on, a “unit flame failure “signal is established when all five UNIT FLAME FAILURE (amber) “GH” and “FG” and “DF” and “BC” and “AB” lights are all on simultaneously. This is indicated when the Data Logger receives a “FLAME FAILURE TRIP” signal. This signal causes a “master fuel trip” memory signal to be established (both (red) “BOILER TRIP” lights come on). When each fireball flame scanner elevation votes “no flame”, the associated UNIT FLAME FAILURE (amber) light comes on at the associated fireball flame scanner elevation. Listed below are the conditions that will cause this (amber)light to be illuminated for the various fireball flame scanner elevations. Elevation “AB”: 1.
Feeder A is off or loss of elevation A power and Feeder B is off or loss of elevation B power. This condition exists for more than two seconds. OR
2.
At elevation AB, less than three of the four heavy fuel oil nozzle valves are fully open or fuel flow is not adequate at the associated oil nozzle valve or elevation AB power is not available for more than two seconds and less than two of the four “fireball” flame scanners indicate flame on elevation “AB” OR
3.
At elevation AB, less than three of the four heavy fuel oil nozzle valves are fully open or fuel flow is not adequate at the associated oil nozzle valve or elevation AB power is not available for more than two seconds and any elevation AB heavy fuel oil nozzle valve is not closed or elevation AB power is not available for more than 2 seconds.
Elevation “BC”: 1.
Feeder B is off or loss of elevation B power and Feeder C is off or loss of elevation C power. This condition exists for more than two seconds.
2.
Less than two of the four “fireball” flame scanners indicate flame on elevation “BC”. KORBA SIMULATOR
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Elevation “DE”: 1.
Feeder D is off or loss of elevation D power and Feeder E is off or loss of elevation E power. This condition exists for more than two seconds.
2.
Less than two of the four “fireball” flame scanners indicate flame on elevation “DE”.
Elevation “FG”: 1.
Feeder F is off or loss of elevation F power and Feeder G is off or loss of elevation G power. This condition exists for more than two seconds.
2.
Less than two of the four “fireball” flame scanners indicate flame on elevation “FG”.
3.
One elevation GH, any heavy fuel oil nozzle valve is not closed or elevation GH power is not available for more than two seconds.
Elevation “GH”: 1.
Feeder G is off or loss of elevation G power and Feeder H is off or loss of elevation H power. This condition exists for more than two seconds. OR
2.
At elevation GH, less than three of the four heavy fuel oil nozzle valves are fully open or fuel flow is not adequate at the associated oil nozzle valve or elevation GH power is not available for more than two seconds and less than two of the four “fireball” flame scanners indicate flame on elevation “GH” OR
3.
At elevation GH, less than three of the four heavy fuel oil nozzle valves are fully open or fuel flow is not adequate at the associated oil nozzle valve or elevation GH power is not available for more than two seconds and any elevation GH heavy fuel oil nozzle valve is not closed or elevation GH power is not available for more than 2 seconds.
CAUSE OF TRIP SYSTEM A “Cause of Trip” system has been incorporated which allows the Operator to determine the cause of a master fuel trip which was initiated by a boiler trip command.
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The boiler trip commands that can cause a “master fuel trip” memory signal to be established . The first boiler trip command that causes a master fuel trip (both (red) “BOILER TRIP” lights come on), will illuminate the appropriate indicator in the CAUSE OF TRIP section on the console insert. The Data Logger will also receive a corresponding signal. Any successive boiler trip commands to the other indicators are blocked. There will be only one indicator that is illuminated. When the furnace purge cycle is successfully completed (PURGE CYCLE (yellow) “PURGE COMPLETE” light is on) and a “ no master fuel trip” memory signal is established (both (red) “BOILER TRIP” lights are off), all CAUSE OF TRIP memories are reset and there are no illuminated indicators. POST PURGE EXCURSION PROTECTION A post purge excursion circuit has been designed into the Furnace Safeguard Supervisory System. It operates as described below: 1.
During the Furnace Purge Cycle, the following conditions are satisfied: A.
The mode permit is satisfied
B.
All heavy fuel oil nozzle valves are closed
C.
The heavy fuel oil trip valve is closed,
D.
All pulverizers are off
E.
All feeders are off
F.
All flame scanners (discriminating and fireball) indicate no flame
G.
Air flow is greater than 30 %
2.
When all of these conditions are satisfied simultaneously, a five minute counting period is started. After the five minute counting period expires, the following events will occur:
A.
A “post purge time expired” memory signal is established and a “post purge fan trip” signal is established if a “high or low furnace pressure trip” signal is established. This is indicated when the Data Logger receives a “FURNACE PRESSURE HIGH” or a “FURNACE PRESSURE LOW” signal.
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The “post purge fan trip” signal is proven established if the Data Logger receives “POST PURGE FAN TRIP” signal. If this signal is established, the I.D. and F.D. fans are tripped. B.
The “open upper fuel air dampers” memory signal is removed, closing the upper fuel air dampers. Simultaneously, a thirty second counting period is started. When the thirty second counting period expires, the “open lower fuel air dampers” memory signal is removed, closing the lower fuel air dampers. Simultaneously, a five second counting period is started. When the five second counting period expires, the auxiliary air dampers are now released from manual to the auxiliary air control system and the “open auxiliary air dampers” signal is removed. When all auxiliary air dampers are modulating, item 12 in the “Furnace Purge” section is satisfied. When any heavy fuel oil elevation has at least three of the four oil nozzle valves fully open, the “post purge time expired” memory signal is removed which will now prevent the “post purge fan trip” signal from being established. When the heavy oil trip valve is moved form the closed position (for oil recalculation), the five minute counting period is reset.
PRIMARY, SCANNER AND SEAL AIR FAN OPERATION The operation of the various air fan control systems are described in the following sections. PRIMARY AIR FAN CONTROL There are two primary air fans serving the unit. The primary air fans are used primarily to transport the pulverized coal to the respective coal nozzles at each coal elevation. When a “master fuel trip” memory signal is established, the primary air fans are tripped. When the “master fuel trip” signal exists for more than five minutes, all cold air dampers are opened to the “ 100% pulverizer air flow position”. When the furnace purge cycle is successfully completed and a “no master fuel trip’ signal is established (both (red) “BOILER TRIP” lights are off), the primary air fans can be placed in service. This is accomplished when the customer supplies a “any primary air fan start command”. When this signal is established, the “open cold air dampers to 100% pulverizer airflow position” memory signal is removed and all cold air dampers on all coal elevations (“A” thru “H”) are positioned to “less than 5 % open” because the associated pulverizers are off. When all elevation coal air dampers are positioned to “less than 5 % open”, the “permit to start P.A. fans” signal is established.
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The primary air fan can now be placed service. After a primary fan is on, a signal is established which keeps the “permit to start P.A. fans” signal established. The “cold air dampers opened to less than 5 %” is no longer required. The second primary air fan can now be placed in service, when it is required. A “primary air permit” signal is required before a pulverizer can be started. There are two separate “pulverizer primary air permit” signals. One signal is used for pulverizers A, B, C, D. The other signal is used for pulverizers E,F,G,H. The “primary air permit” signal (for pulverizers A,B,C and D) is established when the following conditions are satisfied: 1.
Both F.D. fans are on and both P.A. fans are on OR At least one F.D. fan is on and at least one P.A. fan is on and less than four pulverizers are on AND
2.
The hot primary air duct pressure (for pulverizers A,B,C,D) is “not low” AND
3.
The hot primary air duct pressure (for pulverizers A,B,C,D) is “not Low-Low”
The “primary air permit” signal (for pulverizers E,F,G,H) is established when the following conditions are satisfied: 4.
Same as “1” above AND
5.
The hot primary air duct pressure (for pulverizers E,F,G,H) is “not low” AND
6.
The hot primary air duct pressure (for pulverizers E,F,G,H)is “not Low- Low” The “primary air permit” signal is proven established when the PULV START PERMITS (white) “P.A. PERMIT” light comes on. After the associated pulverizer is
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on, the “primary air permit” signal is no longer required at the pulverizer that is on. A “primary air trip” signal will trip any pulverizer that is in service (PULV START PERMITS (White) “NO PULV TRIP” light goes off). A “primary air trip” signal is established at pulverizers A,B,C and D when the following condition exists: 7.
Any purlveriser is on AND All P.A. fans are off or all F.D. fans are off OR
8.
For pulverizers A,B,C, D: The hot primary air duct pressure is “low” for more than five seconds or the hot primary air duct pressure is “low-low”. A “primary air trip” signal is established at pulverizers E,F,G AND H when the following conditions exists:
9.
Same as item 7 above OR
10. For pulverizers E,F,G,H: The hot primary air duct pressure is “low” for more than five seconds or the hot primary air duct pressure is “low-low”. If a “primary air trip” signal is established at pulverizers E,F,G, and H, the pulverizers are removed form service in the following manner: 11. If at least five pulverizers are on and less than two F.D. fans are on or less than two P.A. fans are on, the following events will occur: A.
Pulverizer “H” is tripped immediately; then at two second intervals, pulverizers G,F and E are tripped.
B.
After pulverizer “H” is tripped, the pulverizers will only be tripped until four remain in service. The “primary air trip” signal for pulverizers E,F,G,H is now removed.
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C.
More than four pulverizers can only be placed in service when both F.D. and both P.A. fans are on. When this is acco,plished, the “primary air permit” sigfnal is reestablished and the remaining pulverizers can then be placed in service. The Data Logger will receive signals when any of the following conditions exist:
12. Hot primary duct pressure is “low” for pulverizers A,B,C,D. 13. Hot primary duct pressure is “low” for pulverizers E,F,G,H. 14. Both P.A. fans are off and any pulverizer is on. SCANNER AIR FAN CONTROL The are two (2) scanner air fans service the unit. The scanner air fans can be placed in service manually or automatically. Both procedures are described in the following sections. When both F.D. fans are off, the scanner air emergency dampers are opened. The dampers are proven open when the SCANNER AIR (red) “EMERG DAMPR OP” light is on and the assocaited (green) “EMERG DMPR CL” light is off. When a least one F.D. fan is not off (“on”), the scanner air emergency dampers are closed. Manual Operation Either scanner air fan can be placed in service manually in the following manner: 1.
Momentarily depress the SCANNER AN A or the SCANNER FAN B “START FAN” push button. The following events occur:
2.
A “scanner start” memory signal is established. The associated scanner air fan recieves a “start” command. Simultaneously, a two second counting period is started if both scanner fans are off.
3.
The associated scanner air fan motor is started. The scanner air fan is proven on when the SCANNER FAN (red) “START FAN” push button is illuminated. The associate (green) “STOP FAN” light goes off. The following events will also occur:
A.
The associated scanner air fan outlet damper receives an “open” command. The scanner fan outlet damper is proven open when the (red) “FAN OUTLET DAMPER OPEN” light comes on.
B.
A five second counting period is started if the other scanner air fan is off. Five seconds later, the associated scanner air fan’s outlet damper receives a “close” command and is closed. The outlet damper is proven closed when the associated (red) “FAN OUTLET DAMPER OPEN” light goes off.
4.
If bothscanner air fans remain off when the two second counting period expires (see item 2 above), the “LOSS OF EITHER SCANNER FAN” signal at the Data
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logger is established. If this signal is established, both scanner air fans ( A and B) receive “start” commands and are placed in service simultaneously. Either scanner air fan can be removed from service manually if the scanner duct to furnace differential pressure is greater than 6 inches w.g. This is accomplished in the following manner. 5.
Momentarily depress the SCANNER FAN “STOP FAN” push button. The following events will occur:
A.
The “scanner start” memory signal is removed. This removes the scanner air fans “start” command.
B.
The scanner air fan is proven off when the (green) “STOP FAN” push button is illuminated and the associated (red) “START FAN” light is off.
C.
If the other scanner air fan is on, the scanner air fan outlet damper at the scanner air fan that stopped will be closed after a delay of five seconds.
D.
If the other scanner air fan is off, the scanner air fan outlet damper at the scanner air fan that was stopped will remain open even though the “open” command was removed.
Automatic Operation The scanner air fans will be placed in service automatically if the scanner duct to furnace differential pressure is less than six inches w.g. (see note 11). NOTE 11 If the scanner duct to furnace differential pressure remains at less than six inches w.g. for more than ten seconds, the Data Logger receives a “LOSS OF SCANNER COOLING AIR “ signal. The scanner air fans are placed in service in the following manner: 1.
Scanner air fan “A” “scanner start” memory signal is established and scanner air fan “A” is placed in serivice in the same manner as previously described in the “Manual Operation “section, starting with item 2. Simultaneously, a five second counting period is started.
2.
When the five second counting period expires, scanner air fan “B” is placed in the same manner as previously described in the “Manual Operation” section, starting with item 2. If loss of unit critical power exists for more than two seconds, both scanner air fans ( A and B) are started and both scanner air fan outlet dampers are opened simultaneously. KORBA SIMULATOR
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The scanner air fans are removed from service in the following manner: 3.
The “scanner start” memory signal at scanner for “B” is removed and a ten second counting period is started.
4.
“Scanner air fan “B” is removed from service in the same manner as previously described in the “Manual Operation” section, starting with item 5.
5.
When the ten second counting period expires (see item 3 above) the “scanner start” memory signal at scanner fan “A” is removed if the scanner duct to furnace differential pressure remains greater than 24 inches w.g. Scanner air fan “ A” is removed from service in the same manner as previously described in the “Manual Operation” section, starting with item 5.
SEAL AIR FAN CONTROL There are four seal air fans that serve the unit. Two seal air fans are used for pulverizers A,B,C,D and the other two seal air fans are used for pulverizers E,F,G,H. Both pair of seal air fans are placed in service and removed from service in the same manner. Seal air fans No. 1 and No. 2 are used with pulverizers A,B,C,D. Seal Air fans No. 3 and No. 4 are used with pulverizers E,F,G,H. The air fans can be placed in service and removed from service manually or automatically. Both procedures are described in the following sections. The operation of seal air fans No. 1 and No. 2 will only be described. Seal air fans No. 3 and No. 4 operation is indentical. Manual Operation Either seal air fan can be placed in service manually in the following manner: 1.
Momentarily depress the SEAL AIR FAN No.1 or the SEAL AIR FAN No. 2 push button. The following events occur:
2.
A “seal start” memory segnal is established. The associated seal air fan receives a “start” command. Simultaneously, a two second counting period is started if both seal air fans (No. 1 and No. 2) are off.
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3.
The associated seal air fan motor is started. The seal air fan is proven on when the SEAL AIR FAN NO. (red) “START FAN” push button is illuminated. The associated (green) “STOP FAN” light goes off. The following events will also occur:
A.
The associated seal air fan discharge damper receives an “open” command. The seal air fan discharge damper is proven open when the associated (green) “FAN OUTLET DMPR CL” . light is off. The associated (red) “FAN OUTLET DMPR OP” light came on when the discharge damper was not closed.
4.
If both seal air fans remain off when the two second counting period expires (see item 2 above), the “SEAL AIR FAN 1 & 2 OFF > 2 SEC” signal at Data logger is established. If this signal is established, both seal air fans (No. 1 and No. 2) receive “start” commands and are placed in service simultaneously. If both seal air fans are on (No. 1 and No. 2) , only one of the seal air fans can be stopped. This is accomplished in the following amnner:
5.
Momentarily depress the SEAL AIR FAN NO. “STOP FAN” push button. following events will occur:
The
A.
The “seal start” memory signal is removed and the “seal stop” memory signal is established.
B.
The seal air fan is proven off when the (green) “STOP FAN” push button is illuminated and the associated (red) “START FAN” light goes off.
C.
The associated seal air fan discharge damper is closed.
Automatic Operation The seal air fans will be placed in service automatically in the following amnner: 1.
When either P.A. fan is on, a two “start” command is established and a “seal start” memory signal is established at seal air fan No. 1 and seal air fan No. 1 is placed in service in the same manner as previously described in the “Manual Operation” section, starting with item 2.
2.
When either P.A. fan is on and if the seal air header to cold air duct differential pressure is less than four inches w.g. (pulverizers A,B,C,D) for more than ten seconds, the Data logger recieves a “SEAL AIR HEADER/COLD AIR DUCT P LOW > 10 SEC (PULV’S A,B,C,D)” signal and a “seal start” memory signal is established at seal air fan No. 2. Seal air fan No. 2 is then placed in service in the same manner as previously described in the “Manual Operation” section. starting with item 2.
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The seal air fans are removed from service automatically when both P.A. fans are off more than fifteen seconds. When the seal air fan is off, the associated seal air fan discharge damper is closed. PULVERIZER LUBE OIL PUMP OPERATION Each coal elevation’s pulverizer has an associated lube oil pump system. The pulverizer lube oil pump must be operating properly before the associated pulverizer can be placed in service. Initially, the lube oil tempreture must be greater than 32 C and the lube oil sump level must be adequate. When this condition is satisfied, the PULV START PERMITS (white) “STATIS LUBE LVL & TEMP” light comes on (See “Pulverizer Ready “section, item 12). If the lube oil sump level is not adequate for more then ten secondsm the date Logger receives a “PULV LUBE OIL LELVEL LOW > 10 SEC.” signal. If the lube oil temperature is “low”, the Data Logger receives a “PULV LUBE OIL TEMP. LOW” signal. The lube oil pump is proven on when the LUBE PUMP (red) “ON” light is on and the associated (green) “OFF” light is off. When the lube oil pressure is “not low” for more than five minutes, the PULV START PERMITS (white) “LUBE PRESS SATIS” light comes on (See “Pulverizer Ready” section, item 11). After other permissive are also satisfied, the pulverizer can be placed in service. When the pulverizer is on, the “lube oil temperature greater than 32 C” and “lube oil sump level adequate” requirements are no longer required to satisfy the “pulverizer ready” permissive. When the pulverizer is on, the pulverizer will be tripped after a delay of ten seconds if the lube oil pump is off, When the pulverizer lube oil pump is on and the lube oil pressure is “low” the Data Logger recieves a “PULV LUBE OIL PRESS LOW” signal. If this signal exists for more than ten seconds, the pulverizer is tripped. SECONDARY AIR CONTROL For a complete and detailed description of the secondary air damper controls, refer to the manufacturer’s instructions. Operation of auxiliary and fuel air dampers as affectedby the Furnance Safeguard Supervisory System are described below. AUXILIARY AIR DAMPERS All elevations of auxiliary air dampers are transferred to manual control and are opened when any of the following events occur: 1.
All I.D. or F.D. fans are off.
2.
A “master fuel trip” memory signal is established.
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3.
Loss of unit critical power for more than two seconds exists. When the five minute “post purge” counting period expires (see “Post Purge Excursion Protection” section for specifics), a thirty second counting period is started. When the thirty second counting period expires, a five second counting period is started. Five seconds later, the auxiliary air control is removed from “MANUAL” operation and the “open auxiliary air dampers” command is removed. The auxiliary air control can now be placed in “AUTO” conrol. After the auxiliary air control is in “AUTO” contol and at least one I.D. fans is on and at least one F.D. fan is on, all elevation of auxiliary air dampers modulate to maintain a pre-determined set point differential pressure between the windbox and furnace. This is indicated by the DAMPERS MODE (red) lights coming on. When all nine elevations are modulating, the PURGE PERMITS (white) “AUX AIR DMPRS MOD” light comes on. this condition exists during the furnace purge cycle and initial operation of the unit up to 30 % loading. The auxiliary air dampers on a heavy fuel oil elevation are closed for a high energy arc (HEA) oil start when the following conditions are satisfied:
1.
The boiler load is less than 30 % AND
2.
An “elevation start” memory signal is established and both seventy second “elevation pair” counting periods have not expired and less than three of the four oil nozzle valves are fully open or oil flow is not adequate at the associated oil nozzle valve. The auxiliary air dampers on a heavy fuel oil elevation are positioned to the “warm up firing” position when the following conditions are satisfied:
3.
At least one corner oil nozzle valve on the associated oil elevation is not closed AND
4.
At least three of the four oil nozzle valves are fully open and oil flow is adequate at the associated oil nozzle valve or both seventy second “elevation pair” counting periods have expired. When the unit loading exceeds 30 %, the differential set point is gradually increased to a higher set point as the boiler loading is increased. The rate of
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increase (“slope”) of the differential pressure is controlled by the Auxiliary Damper Control. Simultaneously (above 30 % loading), the auxiliary air dampers on elevations “HH”, “FG” , “DE”, “BC” and “AA” close in a timed sequence (ten second intervals), if the pulverizers on adjacent elevations are off. The auxiliary air dampers on elevations “GH”, “EF”, “CD” and “AB” close in time sequence (ten second intervals), if the pulverizers on adjacent elevations are off and a “heavy fuel oil elevation back up trip” signal is established on the associated elevation. The “close” commands are initially sent to the upper elevation not in service and progressing to the lowest elevation. When the until load is reduced below 30 %, the auxiliary air dampers open in a timed sequence (ten second intervals), starting with the lowest elevation of auxiliary air dampers. Simultaneously, the differntial set point reverts to its lower setting. FUEL AIR DAMPERS 1.
All I.D. or F.D. fans are off.
2.
A “master fuel trip” memory signal is established.
3.
Loss of unit critical power for more than two seconds exists. When the five minute “post purge” counting period expires (see “Post Purge Excursion Protection” section for specifics), the upper fuel air dampers “open” command is removed which closes the upper fuel air dampers. Simultaneously, a thirty second counting period is started. Thirty seconds later, the lower fuel air dampers “Open” command is removed which closes the lower fuel air dampers. When the feeder is “proven” (feeder is on for more than 50 seconds), the feeder speed is released AUTO control and the fuel air dampers modulates as a function of feeder speed. This is indicated by the DAMPERS MODE (red) light coming on at the associated coal elevation. The associated CL (green) light will be off. When a feeder is off for more than fifty seconds, the associated elevation of fuel air dampers are closed.
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PROTECTION AND INTERLOCKS
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PROTECTION AND INTERLOCKS ID FANS INTERLOCKS ID FAN - A START PERMISSIVES 1.
Inlet Guide Vane Position minimum.
2.
Hyd. coupling scoop position minimum.
3.
SAPH A / B Running and Inlet / Outlet dampers open & any FD discharge damper open (SAD 1 / 2).
4.
Hyd. coupling oil Pump ON and pr. adequate. > 1.2 Kg / cm2
5.
Inlet / Outlet dampers fully closed.
6.
Hyd. coupling oil level normal.
7.
Hyd. coupling oil temp. at cooler inlet normal. < 95 0C
8.
Hyd. coupling oil temp. at cooler outlet normal. < 65 0C
9.
Temp. of Motor , Fan & 8 H.C. bearings are normal. 85 0C
2.
Hyd. coupling oil temp at cooler inlet very high. >100 0C
3.
Hyd. coupling oil temp at cooler outlet very high. > 75 0C
4.
Fan/motor bearing temp. Hi - Hi > 85 0C
5.
Hyd. coupling oil pressure lo - lo < 0.5 Kg/cm2
6.
Discharge dampers / gate does not open fully within specified time. 3 min after the fan start
7.
Post purge furnace pressure hi/lo from FSSS
8.
ID - A trips when both FD fans are running & FD Fan A trips KORBA SIMULATOR
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9.
Electrical Protection Trip
10. Emergency PB Pressed ID FAN - B (BUS - B) START PERMISSIVES 1.
Same as ID Fan - A for 1 to 9
2.
ID Fan C not running and ID Fan B not running on BUS - A
TRIP CONDITIONS 1.
Same as ID - A for 1 to 7
2.
ID Fan B (BUS-B) trips when both FD fans are running and FD Fan B trips.
ID FAN - B (BUS-A) START PERMISSIVES : 1.
Same as ID Fan A for 1 to 9
2.
ID Fan A not running and ID Fan B not running on BUS - B
TRIP CONDITIONS 1.
Same as ID Fan A for 1 to 10
2.
ID Fan B (BUS - A) trips when both FD fans are running and FD Fan A trips.
ID FAN - C : START PERMISSIVES 1.
Same as ID Fan A for 1 to10
2.
ID Fan B not running on Bus - B.
TRIP CONDITIONS 1.
Same as ID Fan A for 1 to 7 KORBA SIMULATOR
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2.
ID Fan C trips when both FD fans are running and FD Fan B trips.
HYDROCOUPLING OIL PUMP INTERLOCKS The Pump Selected To Lead starts under the following conditions : 1.
When the ID fan start command is given the pump starts and runs for 40 secs.
2.
The pump starts if the oil pr. is less than specified limit < 1.8 Kg/cm2
3.
The pump starts and runs for 25 mins after the ID fan stops
The Pump Selected To Lead stops under the following Conditions : 1.
Stops after 40 Secs of ID fan start command and oil pr. reaches the specified limit. > 2.2 Kg / cm2 [NB The pump selected to lag starts when lead pump fails to start.]
FD FAN-A START PERMISSIVE 1.
Blade pitch position min
2.
Control oil pressure adequate > 8 Kg / cm2
3.
Lub 0il presssur adequate > 0.5 Kg/cm2
4.
Any ID fan running AND no FD fan running - OR Two ID fans running
5.
Discharge damper fully closed.
TRIP CONDITIONS 1.
No ID fan is running
2.
Fan / motor bearing temp. Hi-Hi > 85 0 C
3.
Discharge damper does not open fully within specified time after 2 min starting fan
4.
Post Purge furnace Pr. Hi / Lo from FSSS KORBA SIMULATOR
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5.
FD fan B running, ID fanB running on BUS B & running ID fan A trips
FD FAN - B START PERMISSIVES 1.
Same as FD - A
TRIP CONDITIONS 1.
Same as ID - A for 1 to 7
2.
FD - A running and ID - A running, ID-B running on BUS - B trips.
F.D.Fan oil pump interlocks When the selector switch is in Auto, the oil pump starts under the following conditions. 1. LEAD pump starts when FD fan start command is given. 2. Fan running and control oil pr. is < 6 Kg / cm2 3. When the LEAD pump trips, LAG pump starts within 1 sec. PA FAN - A START PERMISSIVES : 1.
F.D. fan A or B running but PA fan B not running or both FD fan A & B running.
2.
Lub / Control oil pressure adequate. > 8 Kg / cm2
3.
Blade pitch position minimum
4.
Outlet damper fully closed.
5.
Start permit from FSSS (Purge cycle complete & MFR reset.
TRIP CONDITIONS 1.
Fan / motor bearing temp Hi-Hi > 85 0 C
2.
Discharge damper does not fully open within 100 Secs.
3.
Trip from FSSS (MFT)
4.
Both PA - A & B running, on FD - A trip PA - A trip
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5.
Electrical Protection trip
6.
Emergency PB pressed
PA FAN - B START PERMISSIVES : 1.
F.D. fan A or B running but PA fan A not running or both FD fan A & B running.
2.
Others same as PA fan A
TRIP CONDITIONS 1.
Same as PA fan A for 1 to6
2.
Both PA fan A & B running, on FD fan B trip PA fan B trip
PA fan oil pump interlocks : When the selector switch is in Auto the oil pump starts under the following conditions. 1.
Pump selected to LEAD pump starts when fan start command is given.
2.
Stand by ( LAG ) pump starts when fan is running and control 32 GPM < 57.2oC < 37.8 0 C
TRIP CONDITIONS 1. 2. 3.
Any of the discharge valves not fully open. Motor cavity temp. high for more than 5 sec. Electrical protection trip / EPB pressed
57.2
O
C
AUTO START Pump selected auto starts when
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1.
Any running pump tripsand 2 secs not over.
2.
Boiler load > 60 % & only 1 pump is effective (i.e. second pumps not running & DP low ( < 10 Psi )
AIR HEATERS ELECTRIC / AIR MOTOR DRIVE INTERLOCK (PAPH & SAPHS) START PERMISSIVE FOR ELECTRIC MOTOR 1.
Both hand switches of SB Lop are not OFF
2.
Both hand switches of GB Lop are not OFF
3.
Air Motor Hand Switch on Auto
4.
Air preheater receiver air pr. Adequate
START PERMISSIVE FOR AIR MOTOR 1.
Start Hand switch of Electric motor should not in off position.
2.
Air motor starts when electric motor trips.
G.B. AND S.B. LOP OF AIR HEATERS : STARTS WHEN : 1.
Oil temp > 550C, lead pump starts.
2.
Lag pump starts if the lead pump is OFF and Oil temp > 550C
3.
Running Oil pump will stop when oil temp. falls below 450C
CAUSES OF BOILER TRIP Boiler trips if any of the following happens. 1.
Loss of 220 V D.C. Power Supply > 2 Secs.
2.
Loss of unit critical power supply > 2 Secs. (Unit critical power consists of unit logic Voltage and unit critical interrogate scan Voltage, which scans All MFT I / P Contracts)
3.
A ‘Simulator Trip’ signal exists (All oil & coal elevations OR Unit not in operate mode)
4.
Drum level is Lo - Lo. for 10 Secs
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5.
Drum level is Hi-Hi. for 10 Secs
6.
All BFP OFF
7.
“Inadequate water wall circulation” signal exists. ( i.e. if Boiler Load is > 60 % and atleast two B.C.W. Pumps are ineffective (Pump is ‘ON & its DP between suction & discharge is < 10 psi 5 Sec OR Pump is OFF) OR Boiler load is < 60 % AND (No B.C.W. Pump is ON OR Pump ON AND DP is low)
8.
All ID fans are off
9.
All FD fans are off
10. Air flow is less than 30 % of rated air flow, before the Boiler load exceeds 30 % < 624 T / hr 11. The deaerator level is Lo-Lo (2/3 logic, Two from< - 2134 mm 12. 2 out of 3 Furnace Pressure Hi-Hi 5 Sec. a) Boiler working but all HP ESVs OR all IP ESVs are closed AND (both the HPBP valves closes or both the LPBP valves closes) - OR b) Boiler working AND (Generator ckt. br. opened or turbine tripped) AND (Both HPBP valves are closed (open < 2 %) or both LPBP valves are closed (Open < 2 %). 17. “A loss of fuel trip “Signal is established (This signal is established following condition)
under
the
After loss of fuel trip signal is “armed” (i.e. when any oil elevation that is placed in services has atleast 3 / 4 HONVS proven open for > 2 Secs.) this signal will be established if. A)
All feeders OFF or Loss of elevation. Power in all coal elevation > 2 Secs AND (All HONVS closed at all four oil elevations or any elevation trip signal is established at the elevation in services. KORBA SIMULATOR
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OR B)
(All feeders OFF or Loss of elevation. Power > 2 Secs. AND HOTV valve not fully open AND All 4 oil elevations HONVS are closed.
18. A “Unit flame failure “ siganl is established (This trip is “armed” only if a feeder is proven for > 2 Secs. This trip is established when unit flame failure is armed AND All elevations scanner Vote ‘NO FLAME’ simultaneously) INTERLOCKS FOR COAL ELEVATIONS MILL DISCHARGE VALVE (MDV) Does not accept stop command if Pulv is ‘ON’ MILL INTERLOCKS (A)
:
START PERMISSIVES :
Mill starts after the ‘ON’ push button is pressed if following conditions are fulfilled 1.
Pulveriser Ready is available. This signal will be available if following conditions are fulfilled a) M.D.V. is open (all four) b) Mill outlet temp < 93 0 C c) Feeder local switch in Remote d) Pulv. start permit (if Nozzle tilt Horizontal & air flow < 40 % ) OR ( Any feeder proven and NO MFT ) e) Cold air gate open f) Tramp iron valve open g) Feeder inlet gate open h) Lub oil level & temp. adequate i) Lub oil pressure not low for more than 300 sec KORBA SIMULATOR
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j) No Mill trip existing k) P.A. permit available (i.e. (i) Hot P.A. duct Pressure. not low ( > 625 mm wc) (ii) P.A. duct pr. not lo-lo ( > 500 mmWc AND (iii) Both FD s ON and both PA fans ‘ON’ or (Any PA fan ON and any FD Fan ‘ON’ and > 4 mills not ON) AND 2.
No Auto pulv unsuccessful start
3.
Seal air Header to mill under bowl DP satisfactory > 8" wc
4.
Mill not ‘ON’
5.
Pulv Ignition permit available. For Mill A: a ) AB elevation 3/4 HONV’s open OR b) Boiler load > 30 % and
Feeder - B speed > 50 % ( > 30 T/hr.)
For Mill B: a) AB elevation proven OR b) Boiler load > 30 % and Feeder A or Feeder C proven. For Mill C: a) CD elevation proven OR b) AB oil elevation and feeder B proven OR c) Boiler load > 30 % & either feeder B or Feeder D proven.
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For Mill D : a) CD elevation proven OR b) Boiler load > 30 % and either feeder C or feeder E proven. For Mill E,F,G & H identical logic. Mill TRIPS / STOPS: a)
Auto / manual mode selected to manual & stop PB depressed. OR
b)
Pulv. start command given & not ‘ON’ for > 2 Secs. OR
c)
Loss of Elevation poer OR Unit critical power for >2 Secs OR
d)
Pulv ‘ON’ & seal air / under DP Low < 5” wc for more than 1 minute. OR
e)
Pulv ‘ON’ and lub oil pump OFF > 10 sec.
f)
Pulv ‘ON’ and lub oil pr. low > 10 secs. < 1.76 Kg/cm2
g)
Ignition permit required (> 180 secs) & ignition permit lost (i.e. with -in 180 sec of feeder start)
h)
Any of the MDV is not fully open OR
i)
Hot PA duct. pr. Lo & Lo - Lo occures simultaneously LoLo = 2 secs OR
ii)
Pulv. off OR
iii)
Pulv. outlet temp > 93 0 C
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OR iv)
Close P.B. depressed
v)
Feeder ON Time delay of 5 secs & Feeder Trips. OR
vi)
Auto pulv. unsuccessful start OR
vii)
Auto pulv. run feeder speed to minimum.
FEEDER START / STOP INTERLOCKS I.
Pulv. Ready is available
II.
Feeder speed demand at minimum
III.
Pulv. manual mode
IV.
Pulv. ignition permit available
V.
No feeder stop command is there
VI.
No MFT
VII. Pulv ‘ON’ Feeder stops when : a) Ignition energy removed within 180 secs of feeder start OR b) Feeder in manual mode & stop PB depressed OR c) Auto Pulv. Feeder stop command d) Pulv. OFF OR
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e) MFT OR f) No coal on belt OR g) discharge plugged PULV TEMP CONTROL A)
Release air & temp control to auto if a) Pulv is ‘ON’ AND b) No HAG close command and c) HAG is open
B)
Open CAD to 100 % a) 5 min. after MFT OR b) Pulv ‘ON’ and HAG Close command or HAG closed on inter locks.
C) Run CAD to < 5 % open (close) a) Pulv is OFF AND b) No command open CAD to 100 % D)
CLOSE HAD a) Pulv. off OR b) HAG CLOSE command and HAG not closed
E)
RUN FEEDER SPEED TO MIN. : a) Auto pulv. run feeder speed to min. OR b) Pulv. motor current HI. > 62 amps. c) Pulv. bowl DP High OR d) Feeder OFF KORBA SIMULATOR
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F) Release Feeder Speed to auto. a) Feedeer proven AND b) No run feeder speed to minimum command. G)
Include Feeder in Totalising Circuit. a) Feeder ‘ON’ AND b) Feeder not OFF > 15 secs.
INTERLOCKS FOR Heavy oil Trip Valve ( HOTV) & Heavy Oil Recirculation Valve (HORTV) 1.
HORV :
(A)
This can be opened by pressing the Push button (PB) from Console if All the HONV s are closed.
(B)
HORV closes automatically when any HONV is not closed OR by pressing close PB.
2.
HOTV : (A) TO OPEN HOTV : Permissives SET I : 1. No. Boiler Trip persisting 0
2. HFO Header temperature satisfactory >93 C 3. HFO supply press satisfactory > 15 Kg/cm2 4. All HONV’s closed 5. No close / Trip command 6. Open PB depressed OR SET II : 1. All HONV’s closed
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2. MFT acted 3. HORTV open 4. Open PB depressed (B) HOTV closes automatically if any of the following conditions exists :
1.
Any HONV not closed AND a) HFO pressure low < 3 Kg/cm2 b) Atom. steam Pr. low < 3.5 Kg/cm2 0
c) HFO Header Temperature Lo-Lo for > 2 secs. < 95 C 2.
Any HONV not closed and MFT acted
3.
Loss of critical power > 2 Secs
FLAME FAILURE VOTE LOGIC : ‘AB’ ELEVATION : a) Feeder A is OFF or LOSS of elevation ‘A’ Power > 2 sec and Feeder B is OFF or LOSS of elevation B Power > 2 Secs. OR b) Elevation AB 2 out of 4 nozzle valves not proven or loss of power for >2 sec. AND Elevation AB 3 out of 4 fire ball scanners sensing no flame OR c) Elevation AB 2 out of 4 nozzle valves not proven or loss of power for >2 secs AND Elevation AB any nozzle valve not closed or elevation started and power loss for 2 secs. KORBA SIMULATOR
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BC ELEVATION a) Feeder ‘B’ off or loss of elevation power for >2 secs andFeeder ‘C’ off or loss of elevation Powerfor >2 secs OR b) Elevation BC 3 out of 4 fire ball scanners sencing no flame GH is same as AB elevation. FG & DE Elevation same as BC elevation SCANNER AIR FANS 1.
No fan running for 2 secs. A.C. Fan starts and if A.C. fan fails to start, D.C. Fan starts
2.
A.C. Fan running and Scanner Duct / furnace DP low (< 6" WC) D.C scanner Fan takes start.
DISCHARGE DAMPERS 1.
A.C. Fan running and D.C. fan off A.C. Fan discharge damper opens and D.C. fan damper closed.
2.
D.C. Fan ON and A.C. FAN OFF - D.C. fan’s discharge damper opens and A.C. fans damper closes.
3.
Scanner air Emergency damper opens on both FD fans are off.
TURBINE TRIPS TRIP REASON (A)
ELECTRICAL TRIPS :
I)
Emergency Trip From UCB Push Button
II)
FIRE PROTECTION a)
MOT LEVEL VERY LOW LOW< -150 mm in 2 out of 3 sonar probe
b) Push Buttons 1. 2. 3. 4.
At UCB console AT MCT room Near HP turbine AT LPBP rack
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III)
BOILER TRIP from FSSS
VI) V)
MCB TRIP OPERATED during ATRS S/ D CONDENSER VACUUM LO LO > 0.3 bar
VI)
LUBE OIL PRESSURE LO LO < 1.1 bar
VII) EXTENDED TURBINE PORTECTION (2 / 2 LOGIC) a) Generator Bushing level hi-hi > 90 mm b) Cold gas temp. behind cooler hi-hi > 55 0 C c) Warmair main exciter temp hi-hi > 80 0 C d) Seal oil temp. behind cooler hi-hi > 60 0 C e) Primary water flow stator outlet Lo-Lo
< 3.3dm3/S (47.88T/Hr)
f) Primary water flow at Main Bushing Phase U lo-lo
+ 450 K
i) I.P. casing front top - bottom 50 % diff. temp hi-hi >+450 K j) I.P. casing Rear top - bottom 50 % diff. temp hi-hi >+450 K k) Primary water temp. behind cooler hi-hi
> 60 0 C
l) Primary water flow at main bushing phase W Lo-Lo < 0.37d m3 / S m) H.P. Exhaust steam temp. hi-hi
> 500 0 C
B.
MECHANICAL TRIPS
I)
OVER SPEED 11 % OF 3000 RPM
II)
THRUST BEARING SHIFT
III)
CONDENSER VACUUM LO-LO
IV)
LOCAL TRIP DEVICE OPERATED FROM GOVERNING RACK
TDBFP START PERMISSIVES
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1.
Lub Oil Pressure Normal
> 2 Kg / cm2
2.
Deareator Level Normal
- 610 mm
3.
Seal Quench Pressure Normal
> 15 Kg / cm2
4.
Diff. Temp. Across Top & Bottom Of Pump > 15 C Barrel Normal
5.
Suction Valve Open
100 %
6.
Recirculation Valve Open
100 %
7.
No Turbine Trip
0
TDBFP TRIP CONDITIONS 1.
Lube Oil Pressure Lo Lo
< 1 Kg/cm2
2.
Exhaust Steam Pressure Hi Hi
> -0.7 Kg/cm2
3.
Live Steam Pressure Hi Hi (Live Steam)
> 10 Kg/cm2
4.
Gov. Oil Pressure Lo Lo
< 4.5 Kg/cm2
5.
Exhaust Steam Temp. Hi Hi
> 120 0 C
6.
Axial Shift Hi Hi
> 0.7 MM
7.
Eccentricity Hi Hi
> 200 m
8.
Bearing Temp. Hi Hi
> 105 0 C
9.
Turbine Speed Hi Hi
> 6330 rpm
10. Seal Quench Water pressure very low
< 10 Kg/cm2
11. Suction & Discharge Diff. Temp Of Main Pump Hi Hi 12. Deareator Level Lo Lo
> 16 0 C - 2134 mm
13. Suction Valve Closed 15. A) Emergency Trip From UCB B) Emergency Trip From LCP (Local control Panel)
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MDBFP START PERMISSIVES 1.
Lube Oil Pressure Normal
> 2 Kg/cm2
2.
Seal Quench Pressure Normal
> 15 Kg/cm2
3.
Deareator Level Normal
- 610 mm
4.
Diff Temp Top-Bottom of BFP Barrel Normal
< 15 0 C
5.
Suction Valve Full Open
100 %
6.
Recirculation Valve Full Open
100 %
7.
Hydraulic Coupling Scoop minimum
8.
Trip Command Not Persisting
MDBFP TRIP CONDITIONS 1.
Deareator Level Lo - Lo
- 2134 mm
2.
Lub. Oil Pressure Lo - Lo
< 0.8 Kg/cm2
3.
Suction Discharge Diff. Temp. Hi-Hi
> 15 0 C
4.
Working Oil Pressure Lo- Lo
< 2.2 Kg/cm2
5.
Working Oil Temp. Hi Hi
> 130 0 C
6.
Seal Quench Pressure Lo- Lo
< 10 Kg/ cm2
7
Suction valve closed
CEP START PERMISSIVE 1.
DC Control Supply On / Available
2.
Breaker Selector Switch at Switch gear in Service
3.
E.P.B. in Release Position
4.
Recirculation Valve Open
5.
Discharge Valve Closed or Any CEP On KORBA SIMULATOR
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6.
Suction Valve Open
7.
Breaker Not Closed
8.
Hot Well Level Normal
9.
Cooling Water Flow Normal
100 %
10. Switch Gear Selector Switch In ‘Remote’ Position C.E.P. PROTECTION 1.
Emergency Trip From Local Push Button
2.
Under Voltage Trip From Switch Gear
3.
Protection Relay Contact Operated In Switch Gear
4.
Hot Well Level Lo Lo
5.
Suction Valve Close
6.
Pump Running & Discharge Pressure Lo (for 5 secs Time Delay)
-1290 mm 0%
< 20 Kg /cm 2
ARCW & DMCW START PERMISSIVE 1.
D.C. Control Supply On/Available
2.
Switch Gear Selector Switch To Be In Service Position
3.
EPB in Released Position
4.
Suction Header Pressure Ok
5.
Start Command Not Persisting
6.
Discharge Valve Closed
> 2 Kg / cm2
0%
HP BYPASS INTERLOCKS For BP Valves : KORBA SIMULATOR
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1.
If Condenser vacuum reaches -0.8 Kg/cm2, Manual Trip Command will go for both BP1 & BP2 valves to close.
2.
If HPBP downstream steam temp. goes beyond 3800C , BP1 & BP2 will close on temperature protection.
3.
In case of Hydraulic oil pr. low, BP valves control changes to manual and it will become inoperative (it will remain stay put)
4.
If BP valves position drops to 2% open, it will receives a close command (for positive shut off)
5.
Manual Trip command will initiate incase of CRH pot level High alarm.
For BPE Valves : 1.
HP Bypass valves opening less than 2 % will automatically close the spray valves.
2.
If opening of either of the bypass valves goes to 2%, BP1 & BP2 , valves will switch over to Auto.
3.
If hydraulic oil pressure is low BPE valves control will go to Manual and remain stayput.
4.
In case of fast opening of BP valves irrespective to temp. BPE valves will open by 20 % till fast open command is persisting.
Fast Opening OF HP Bypass 1.
If set pressure and actual pressure deviation exceeds 20 Kg/cm2.
2.
Gen breaker gets open.
3.
Load shedding relay operated.
4.
Depressing Fast Open push button (Fast open pulse will persist for 5 Sec.)
BD Valve : In case of low Hydraulic oil pressure, it will be forced to Manual. *
Actual Pr. & Set Pr. deviation +20 Kg/cm2 will initiate “HPBP Pr. Limit exceeded alarm”.
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Reheat Protection
:
Boiler will trip when any one or more of the following conditions occur : 1.
Turbine Tripped or Gen CB open and HP or LP Bypass valves opening < 2% then after 5 sec of Time delay.
2.
Turbine working (control valves >2 %) and Load shedding relay actuated and if HP or LP Bypass opening is < 2 % Reheat protection will act after 10 sec. delay.
3.
If Turbine not working (HP or IP control valves < 2%) and boiler working (No. contact of loss all fuel arming relay from FSSS) and HP or LP Bypass valves < 2 % with a time delay of 5 Sec. Reheat Proctection will act. Arming of Reheat Protection - Once HP & LP Bypass are open 2 % and steam flow increases beyond 200T/hr Reheater protection will be armed .
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ANALOG CONTROL SYSTEM
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ANALOG CONTROL SYSTEM In power plant industries, the four basic variables namely Pressure, Temperature, Level, and Flow of the process media needed to be continuously controlled for maintaining them within desired /required limits .Solid state electronics based Analog control system is provided in the plant for controlling various process variables (e.g. main steam pressure ,temp, flow drum level, air flow etc.)at desired value. In this type of control system analoge electrical signals (4 -20mA) are generated to represent the value of process variables using primary elements /transducers. These signals are conditioned and transmitted to electronic control system for further processing. Output of this system is used to activate the final control element e.g. control valves, dampers, guide vanes etc. so as to maintain the process variables at desired set point. This system is called Analog Control System because throughout the control starting from monitoring to conditioning ,to processing and till operating the final control element there exists a definite analogy between the input and output of various subsystems (i.e. transducer, transmitter etc.).Here the signals being processed /used for control are nothing but physical quantities current ,voltage etc. which are similar to the process variables being controlled. It is totally different from digital system wherein ,instead of physical quantities, discrete numbers are used for processing. It is necessary that all the parameters should have optimum values throughout the range of unit operation. For having control on parameters of various subsystem several control loops are in service with specific objectives. Description of following important control loops is covered here under : 1.
Hotwell level control
2.
Drum level control / Feed water control
3.
PA header pressure control
4.
R/H temperature control
5.
SH temperature control
6.
Draft control
Acs has got two operating channels which are simultaneously active i.e. Teleperm - M & Teleperm - C Teleperm C - is the control system which is purely hardware based electronic wherein controls all the related logics & computation are done through electronic cards/modules only. Teleperm M - This the control which uses software in addition to hardware electronic cards. Wherein part of the computation logics are performed through software. During KORBA SIMULATOR
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normal operation if Tel. C fails for a particular system, that control will transfer to Tel M automatically however reverse is not possible. Selection of any of these two channel can be done from UCB depending on the healthiness of control system. Hotwell Level Control Condenser hotwell level shall be controlled by regulating the make up water flow to the condenser. The make up to condenser is primarily provided through the make up line from demineralisation plant. If the condenser make up demand exceeds the flow in DM water make up line ,the additional requirement of make up water shall be supplied from condensate storage tank. Accordingly ,the low level in hotwell shall be controlled by modulating: (a)
Normal make up valve in DM water make up line.
(b)
Emergency make up valve in emergency make up line from CST.
Hotwell level control system is provided with three separate controllers termed as Hotwell high level controller, Hotwell normal level controller and Hotwell low level controller. For high level and normal or low level there are two separate level transmitters. In all the three controllers actual Hotwell level is measured through level transmitters, Output of which is inturn converted into corresponding current signal and then voltage signal through two converters .The available voltage signal is compared with Hotwell level set value in terms of voltage. Net available voltage is fed to a PI controller and output of this used for opening or closing of respective pneumatic control valves provided for Normal, Emergency or spill control thereby controlling the makeup flow as per the demand. Actual position feed back of the valve is available in the UCB. Control circuit is provided with hard hold memory card which retains the last available value and provides smooth change over to manual whenever auto control fails. Auto control fails giving a flashing lamp on the controller module when actual level goes beyond the level transmitter range. Drum Level Control / Feed Water Control This control loop is used for controlling of drum level. Depending on the feed water flow path two separate control loops are used. Namely, single element control & three element control. Single element control :- This control system gets selected when BLI(Boiler load index)is below < 20 % and feed water flow is controlled through low range line. In this control system actual level of drum, after pressure correction, is compared with the set point and available net voltage is processed through a PID controller. Output of this controller is used for generation of pneumatic pressure for actuation of low range feed water control valve. Actual valve position is displayed in UCB. If running BFP scoop/speed is kept on auto it will slowly bring the speed to a constant value which is already preset in the control system and the feed flow will be controlled through pneumatic control valves. KORBA SIMULATOR
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Three element control :- Three element control is selected for higher load operation. In this control the feed flow is controlled by varying BFP speed. The set demand for scoop is achieved as follows Actual drum level and set point difference, after taking into account input of BLI, is compared with sum of feed water flow & SH spray flow signal . The net resultant output is fed to a PI controller and subsequently the output of feed master controller sets the speed demand for TDBFP and MDBFP. Primary Air Pressure Control It is needed to maintain sufficient primary air pressure under all condition as this is essential for carrying coal from pulveriser to furnace. Under this control system actual pressure developed by PA fans is converted into voltage and is compared with the set voltage (in terms of PA header pressure)then the net available output is separately processed through two PI controllers meant for individual control loop, the output of these controllers is used to set the demand position of blade pitch of each fans. Actual position of blade pitch is available in UCB. Moreover biasing is provided for adjusting the loading between two fans. Control loop includes following interlocks 1.
Control system is released for auto operation only after outlet damper has opened fully.
2.
Control system switches to manual when fan is stopped.
3.
Blade pitch operation is blocked on control oil pr. LO. LO.
Reheater temperature control : Reheater temperature control is achieved through burner tilt and spray. In the process of reheat temperature control, it is ensured that burner tilt operates first for bringing down the temperature and after certain time spray comes in service, likewise when reheat temperature is going down then first spray is cut-off and thereafter burner tilt is operated. Reheat temperature Control system consists of two Thermocouples one each for left and right reheat temperature measurement. For generating temp. demand set point ,output of a function generator, based on BLI and output of a manual setter on the control desk, are fed to a minimum selector. Minimum of these two signals is used as final temp. set point for burner tilt. The set point for spray control can be given with a bias from the panel itself in the range from 0 to 50c. Biasing between left and right spray valve is also provided which can be set from panel. Spray block valve will close if control valve opening becomes less than 5 %. In the control system actual reheat temp is compared with set value for temp and output is KORBA SIMULATOR
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processed through separate PID controllers for spray control & the demand position of spray valve and burner tilt. Demand position of RH spray valves are displayed on the panel and average tilt position along with the position feedback of all the four corners tilt position is shown separately on UCB panel. SH temperature Control In this control system SH steam outlet temp. is maintained at set point which is equal to the minimum of (1)
set point manually set from UCB.
(2)
Set point derived through a function generator based on BLI (Boiler Load Index).
Thus derived temp. set point is compared with signal corresponding to actual main steam temp. measured through thermocouple at SH outlet. Separate comparison is done for SH left and right streams . Error signals thus developed are further influenced by feedforward signals from burner tilt position and BLI. These corrected error signals are now compared with respective error signals derived by desuperheater control loop and the final error signals are given as input to two separated PID controllers ,one each for left and right streams, for finally controlling the superheater spray through pneumatically operated control valves. The controler output is displayed in UCB. An interlock is provided for closing the inlet block valve below 5% opening of control valves.. Co - ordinated Control System : As electrical energy cannot be stored in a large quantity it is necessary to balance its generation with momentary consumption. The grid frequency is the factor which indicates the degree of balance between production (generation) and the consumption. In absence of storage capacity for electrical energy it is a must for a modern power plant to have adequate control system to respond to rapid load changes and at the same time control the process/the equipments so that no part of the plant runs into a dangerous operating state i.e. the pressure, temperature and other process parameters must not cross the designed/safe limits of a particular equipment , otherwise, the availability and required safety of the man and machine will be reduced / endangered. In order to achieve best efficiency and best availability with requisite safety, it is necessary that operation of both the main plant equipments ( i.e. Boiler and Turbine) is co-ordinated using suitable control system and there should be a possibility of decoupling them during disturbances by means of bypass system. Boiler and Turbine have a number of equipments which must be able to follow their demands during unit start-up / shutdown and load variations. As a result, the power plant process has a hierarchial structure and in order to match with the process best KORBA SIMULATOR
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the control/automation concept adopted is also hierarchial. A typical scheme is shown in following block diagram. The above hierarchial control concept is implemented through Teleperm ‘C’ & Teleperm ‘M’ series of Siemens AG, WG make control system in case of Singrauli 500MW units. As the 500MW Simulator is designed as replica of Singrauli’s 500MW unit, the control system of the same is taken as base for discussion here. However, the general philosophy is similar to hierarchial control systems of other projects. A simple scheme of control system for unit co-ordination is shown in drawing. Depending upon various conditions/limitations of the plant equipments, different control configurations/modes are selected to carry out the unit co-ordination function. Followings are the four basic operating modes available in the control system :• Co-ordinated Master Control (CMC) Mode • Boiler Follow Mode (BFM) • Turbine Follow Mode (TFM) • Run Back Mode The basic task of achieving balance between energy generated (supply) and its instantaneous consumption (demand) calls for generating a load set point depending upon instantaneous grid demand and permissible/allowable limits/conditions of the various plant equipments at that moment. This is called Target Load Set Point. This set point is used as guidance signal for monitoring/controlling various plant equipments/process parameters to accomplish the desired task of energy balance. The process of generating this target load set point guidance signal is discussed in following section along with four modes of unit co-ordination . Working philosophy of some of the important individual control loops of the hierarchial control system is already covered under Analog Control System above. Generation Of Load Demand Signal Load Demand is the MW set point signal for boiler combustion control and turbine (EHC). This signal is generated as follows: Target Load (MW set point) for the unit is set either by UCB operator or in auto mode from load despatch centre. Digital display is provided for target load. This target load is subject to MIN & MAX Limits, set by the UCB operator. After this limiting, target load is subjected to a rate control which various the MW set point signal at the rate set by the UCB operator or as permitted by the TSE whichever is lower. In CMC both turbine and Boiler Master (BM) are on auto hence the input to the rate controller (Known as SPCM) will be the target load set point. To this rate controlled set point a frequency influence correction signal is added and Load Demand signal is formed.
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To ensure that the unit is following the load set point closely, an inhibit increase / decrease feature is provided. If any of MW, Throttle steam pressure, FW flow, Fuel flow & PA Header pressuredeviates from set point significantly or has reached the MAX/MIN limits, the load demand is inhibited from increasing or decreasing as the case may be. Air flow & turbine load limit active are two additional signals to inhibit increase of load demand. Boiler master and generation of fuel / air set point: The function of the boiler master auto / manual station in CMC Console is to provide a set point for fuel and air flow i.e. fuel demand and air demand signals. In Coordinated mode, it is equal to sum of boiler load set point and master controller (PID) output. In this mode Boiler master controller acts on DP error. The fuel demand as generated is compared with actual air flow and a minimum of the two is selected as the fuel set point. The air demand as generated is compared with fuel flow & 30 % of air flow and maximum is selected as air set point. This MIN/MAX selection ensures an air rich furnace. When fuel/air demand increases the MAX gate first increases the air set point and when fuel demand decreases the MAX gate permits reduction of air flow only after fuel has decreased. Fuel Flow control : Oil flow to burners and feeders speed (which is the measure of coal flow) along with Calorific Value(C.V) corrections added to get total fuel flow. Cabinet adjustments are provided to take care of individual calorific values to obtain total fuel flow as fuel oil equivalent (FOE). The total fuel flow (FOE) is compared with fuel set point to generated fuel control error. This control error is fed through (Pl) controller (Master Fuel Controller) to all feeders in auto and Each feeder is provided with a bias and an auto /manual station. Secondary Air Flow Control As mentioned earlier, air demand is generated as the MAX of the following:1)
Air demand from Boiler Master
2)
Air flow as calculated based on actual fuel flow
3)
A safe minimum 30 % air setting
At SSTPS secondary air flow is measured by aerofoil near the windbox (left & right) by two transmitters, sum of the two transmitters give the secondary air flow. Primary air flow is added to this to give total air flow which is used for combustion control, purge logic & SADC (Secondary Air Damper Control). This actual air flow is compared with the air set point and then modified by O2 trim to generate the air flow control error. This signal is doubled in case only one, out of two running fans available for automatic control. An equalising and biasing signal is added to equalise and bias the individual fan air flows. Control signal thus formed operates on the individual controller (for KORBA SIMULATOR
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each fan) whose output fires the thyristor drives of the 415 V AC motors for blade pitch control. An auto / manual station is provided for each fan. O2 TRIM A selection station and a setter for oxygen set point are provided to achieve the desired excess air. If variable O2 set point (SP) is selected, set point is generated by a function generator which is a function of MAX (air flow SP and total air flow). In other mode SP is set from UCB. O2 in flue gas is compared with this SP and error is fed to PI controller, output of which is limited between 0.8 and 1.2 times of total air flow. O2 PI controller output is now multiplied by total air flow and the resultant O / P signal is given to makes the FD fans blade pitch controllers for achieving desired air flow. O2 probes are provided at the outlet of economiser for measurement and control of the flue gas O2. These probes are zirconium oxide probes working on the principle of partial pressure of oxygen.Thus the input signal to FD Fan blade pitch controllers is trimmed by O2 signal to get desired Excess air / O2 set point Generation of DP / DMW Signals The pressure set point compared with actual throttle steam pressure to obtain the control error signal DP. Three pressure transmitters are provided for redundancy along with deviation monitoring and middle of the three is selected as actual pressure. In case of two transmitters fault, the control is put to manual. The pressure set point generated in this circuit is also sent to HP Bypass Control. Actual MW signal (middle value of O/P of 3 transducer) is sent from turbine control panel to CMC console where DMW signal is formed as the difference between load demand and actual MW. Selection of CMC 1.
Put Air Master on Auto i.e. atleast one FD fan blade pitch controller on auto.
2.
Put feeders speed control on auto after varying Fuel Master (FM) output and making feeder speed controller error zero.
3.
Vary Boiler Master Output so that FM error becomes zero. Then put FM on auto.
4.
Make throttle pre. set point and actual pr. difference zero .
5.
Put BM on auto
6.
Increase / decrease unit master output so that it becomes equal to actual load. (wait until load set value and load actual value matches as shown in the CMC console digital indicator)
7.
From Turbine desk put turbine control on auto.
8.
Press co-ordinated push button along with manual release on CMC desk.
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Boiler Follow Mode In this mode turbine is in manual and the load is set at the turbine desk. The boiler in auto follows the turbine and fires to maintain the throttle pressure. It means boiler master has to be on Auto. If for any reason or other,the load demand set point signal is not available the turbine load has to be set manually and the system can be switched to boiler follow mode. In Boiler follow mode, set point = sum of boiler load index and Master controller output (PID) acting on DP. In Boiler Follow Mode as turbine is on manual so input to SPCM will be turbine load set point. . Selection of Boiler Follow Mode : 1)
Put Air, FW & Fuel Master Controller on Auto.
2)
Put Boiler Master Controller on Auto. Note
: While putting any controller on auto ensure corresponding error signal is zero.
If the unit is in co-ordinated mode automatic change over to Boiler Follow Mode occurs under following conditions a)
Turbine goes to manual because of any reason. OR
b)
(PrCMC - Pr lim) > 60 MW [i.e. when difference between set point guidance signal and load set point for EHC is more than 60 MW ]
Turbine Follow Mode It means turbine control has to be on Auto. On turbine follow mode the unit load is controlled through boiler, acting on the firing rate in the same manner as the steam pressure control described in CMC mode. The pressure is controlled by Pr.controller of EHC utilising the pressure deviation formed in the boiler master control system. In turbine follow mode turbine operates in initial pressure mode. In TFM set point = Sum of boiler load set point and master controller output (acting on DMW Error) Selection of Turbine follow mode: 1)
Boiler master on manual
2)
Confirm that throttle pressure deviation is zero
3)
Put turbine in Auto from turbine desk
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4) Press “ Turbine follow” push button along with manual release on CMC desk and turbine goes to initial pressure mode from limit pressure modes by itself. 5)
Now load set point can be changed by varying the boiler master manually.
Runback Mode Under runback condition the firing rate for the boiler must be reduced to pre-set values, as close as possible to the tolerable limits. Therefore the swings of firing rate caused by the action of the PID controller must be avoided. As consequence of this condition the system has to be switched to pure feed forward control, where the firing rate set point is directly proportional to the load capability signal. To avoid any mismatch between steam production of the boiler and the turbine load, the turbine has to be switched to initial pressure control, as with TFM. Runback Resetting 1)
Let the boiler master be in auto
2)
Reduce load set point from the turbine desk to a value slightly less than Unit capability so that 1 0 “Runback in Operation” resets.
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AUTOMATIC TURBINE RUN-UP SYSTEM
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OPERATION INSTRUCTION OF SGC TURBINE The operator should have clear knowledge of the logic sequences and various criteria requirements. This is an essential prerequisite for smooth trouble free and safe operation. The operating staff should have thorough experience of operation of the turbine and its sub-systems. The sub groups (SGC) can be started in any sequence but it is suggested to switch on the four SGCs one after other, i.e. the SGC control fluid system first, SGC oil system there after SGC vacuum system, and then SGC Turbine. Before starting a particular SGC in ‘Operation or Shutdown’ direction, it is recommended to check from ATRS control console, that all the relevant enabling criteria, necessary for release of programme is available, have been actually accomplished / achieved. For this, press the push button of start up or shutdown of the particular SGC, without pressing the manual release push button. If all the criteria have been fulfilled, the fault lamp (the middle push button) should not glow by pressing this button of start up or shutdown of that particular SGC. If few criteria or a criterion is not fulfilled, then the fault lamp along with the lamps for unfulfilled criteria will glow as long as the start up or shut down button is kept pressed. After checking that all the release criteria are fulfilled, simultaneously press the manual push button of start up or shutdown in the SGC title and push button for manual release. The lamp start up or shut down shall start flickering. the programme would come to first step. The lamp for first step shall continue to glow so long as the programme stays in that step. Along with this, the lamps for unfulfilled criteria shall also glow until the same gets fulfilled as desired by the process. If the criteria do not get fulfilled within the specified monitoring time of that particular step, an alarm “SGC Monitoring Time Exceeded” will appear. In case the criteria of a particular step get fulfilled after the elapse of the monitoring time, the programme shall go ahead automatically but it will leave behind the lamp of the ‘step’ & ‘criteria’ glowing as a trace of Tell-tale story. Once the monitoring time exceeds for any step, then following shall be observed: i)
Fault lamp starts flashing.
ii) iii)
Start lamp or shutdown lamp starts flashing. The lamps for step and unfulfilled criteria get locked up. That means if criteria are achieved after the monitoring time has exceeded, the lamps do not go off by themselves. Note down the step and criteria number for which the lamp continued to glow and investigate the cause for the delay in getting criteria. By once pressing the push button ON/OFF (without pressing the manual release push button) these lamps can be put off, after the criteria have been achieved.
iv) An alarm is given in case the running time of any step is exceeded.
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When the SGC in one Step by Step mode, all the drives controlled by ATRS get switched ‘ON’ and OFF automatically by the SGC logic sequence. These drive can be operated manually also pressing the manual release push button and at the same time ON and OFF push button control interface title of the drive. The condition of the driven equipment shall be displayed by the three lamps as has been explained earlier. OPERATOR GUIDE MODE : In this mode of operation, the function group control does not have any automatic command to the control interfaces, nevertheless the logic programme is followed since sub group control receives data from the plant and control sections, but the command output is blocked. The commands to the control interface are to be given manually at the control interface tiles. For operating the unit under this mode, a lockable stay - push type switch ‘Operated Guide Mode’ has been provided on the control console. It should be turned On with the help of its key. Then start up or shutdown push button on SGC tile alongwith the manual release push button are to be pressed to bring the operation to first step of start-up/shutdown programme. Then the commands of the first step are given manually at control interface level. The programme will seek the checkback criteria and when they are fulfilled, shall just go to second step. Then again the commands for that steps are to be given at control interface level, and so on. Thus although the commands at each step are given manually, the operators strictly follow the programme and can closely watch the sequences, which otherwise in automatic mode runs through. Due to obvious reasons, in this operation mode, the alarm for “Monitoring exceeded” is blocked.
Time
STEP BYPASS This mode of operation suggested only in very special cases for simulating the missing criteria for any particular step. When some criteria are missing due to some fault in transmitter etc., while the plant is in healthy state and actually the criteria have been fulfilled, a deliberate decision can be taken to electrically simulate the missing criteria. For this purpose a lockable spring return switch ‘step by step mode’ has been provided on the control console. When the programme is stuck up at any step, the switch ‘step by step mode’ is to be turned with the help of its key. Simultaneously once press the push button start up or shutdown of SGC tile, without pressing the manual release push button. This will electrically simulate the criteria for that particular step where the programme got stuck up and thereby programme shall proceed forward. Before simulating the criteria, the healthiness of plant and actual fulfilment of all the criteria must be ascertained. Automatic Runup of Turbine with ATRS should only be tried after the unit has been successfully run with manual methods and all auxiliaries, auto controls etc., have undergone successful reliable operation.
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Even when the unit is under automatic runup, the operators should not totally withdraw their supervision on the equipments and the process parameters like vibrations, turbo-visory parameter oil flow through bearings and any other abnormality. ATRS START UP PROGRAMME (SGC TURBINE) OPERATION RELEASE: 1.
Starting device 0%
2.
Position set point turbine controller < 0%
3.
Field breaker OFF.
4.
Generator breaker OFF.
5.
Drain HP control valve1 not closed.
6.
Drain HP control valve2 not closed.
7.
Drain HP control valve3 not closed.
8.
Drain HP control valve4 not closed.
9.
Limit pressure operation ON.
10.
Load controller is ON.
11.
Synchroniser is OFF.
STEP 1 Commands : 1.
SLC drains ON.
2.
AVR switched to AUTO. Monitoring time - 2 Secs
CRITERIA FOR STEP 2 1.
SLC drains ON.
2.
HP ESV1 closed.
3.
HP ESV2 closed.
4.
HP ESV3 closed.
5.
HP ESV4 closed.
6.
INTCPT ESV1 closed. KORBA SIMULATOR
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7.
INTCPT ESV2 closed.
8.
INTCPT ESV3 closed.
9.
INTCPT ESV4 closed. or Starting device > 42 % & ESVS open.(Bypass criteria for 2 to 9)
10.
HP control valve1 closed.
11.
HP control valve2 closed.
12.
HP control valve3 closed.
13.
HP control valve4 closed.
14.
INTCPT valve1 closed.
15.
INTCPT valve2 closed.
16.
INTCPT valve3 closed.
17.
INTCPT valve4 closed.
18.
CRH NRV left closed.
19.
CRH NRV right closed. or Starting device is >56% and position set point of turbine controller >0% (Bypass criteria for 10 to19)
20.
Extraction NRV A5 < 5%
21.
Extraction NRV A4.1 < 5%
22.
Extraction NRV A4.2 < 5%
23.
Extraction NRV A3 < 5%
24.
Extraction NRV A2 < 5% or Generator load >10% (Bypass criteria for 20 to 24)
25.
AVR is on auto.
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STEP 2 Commands: No command is issued. Monitoring time - 500 Secs CRITERIA FOR STEP 3 1.
Turbine speed > 15 rpm.
2.
Condenser pressure < 0.5Kg/cm2.
3.
Any one CEP is ON.
4.
Drains no fault.
5.
DT HPT casing mid top/bottom < 30 0K
6.
DT IPT casing front top/bottom < 30 0K
7.
DT IPT casing rear top/bottom < 30 0K
8.
Trip fluid pressure is > 5 Kg/ cm2
9.
Drain main steam stainer1 not closed.
10.
Drain main steam stainer2 not closed.
11.
Drain main steam stainer3 not closed.
12.
Drain main steam stainer4 not closed.
13.
Drain HRH stainer1 not closed.
14.
Drain HRH stainer2 not closed.
15.
Drain HRH stainer3 not closed.
16.
Drain HRH stainer4 not closed. Or Turbine speed is >300 rpm(Bypass criteria for 9-16)
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17.
Drain DW2 LPBP not closed.
18.
Drain DW4 LPBP not closed.
STEP 3 Commands: 1.
Drain before HPCV1 close.
2.
Drain before HPCV2 close.
3.
Drain before HPCV3 close.
4.
Drain before HPCV4 close.
Monitoring time - 60 Secs. CRITERIA FOR STEP 4 1.
Drain before HPCV1 closed.
2.
Drain before HPCV2 closed.
3.
Drain before HPCV3 closed.
4.
Drain before HPCV4 closed. or ESVs open.
STEP 4 Commands: No command is issued. Monitoring time is blocked. CRITERIA FOR STEP 5 1.
Boiler fire is ON.
2.
Steam before HP BP1 > 30 0K superheat.
3.
Steam before HP BP2 > 30 0K superheat.
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4.
Steam before LP BP1 > 30 0K superheat.
5.
Steam before LP BP2 > 30 0K superheat or (Bypass criteria for 2 to 5) HPCV1 mean temp TM is < 100 0C HPCV2 mean temp TM is < 100 0C
6.
DT (HP bypass1 - HPCV1 /TM) > X1.1
7.
DT (HP bypass2 - HPCV2 /TM) > X1.2
8.
DT (Wet steam1 - HPCV1) < X 2.1
9.
DT (Wet steam2 - HPCV2) < X 2.2
10.
Temp LSTM is < Max. or LSTM TEMP BEF HPESV > 400 0C or DT (HP BP1 - HPCV1 /TM) < X3
11.
Temperature H.P control fluid > 50 0C.
12.
Oil temperature after cooler > 35 0C.
STEP 5 Commands : 1. Starting device raise. Monitoring time 30 secs. CRITERIA FOR STEP 6: 1.
Any one ESV is not closed. Or
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Starting Device Position >42%. STEP 6 Commands: No command is issused. Monitoring time - 60 Secs CRITERIA FOR STEP 7: 1.
HP ESV1 is open.
2.
HP ESV2 is open.
3.
HP ESV3 is open.
4.
HP ESV4 is open.
STEP 7 Commands: No Command is issued. Monitoring time - Blocked. CRITERIA FOR STEP 8 1.
Main steam flow > 15% or MS Strainer 1&3 and 2/4 are open. or Turbine speed > 2850 rpm.
2.
Steam before HP BP1 > 30 0K.superheat
3.
Steam before HP BP2 >30 0K.superheat
4.
Steam before LP BP1 >30 0K superheat.
5.
Steam before LP BP2 >30 0K superheat.
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Commands : 1.
HPCV Drain Controller switched to Auto Mode. Monitoring time - 2 Secs
CRITERIA FOR STEP 9: 1.
HPCV Drain Controller on Auto. or Gen Brkr is ON. or Turbine speed > 540 rpm.
STEP 9 Commands : 1.
Tracking device is switched ON. Monitoring time - 20 Secs
CRITERIA FOR STEP 10 1.
Tracking device is ON.
2.
INTCPT ESV1is open.
3.
INTCPT ESV2 is open.
4.
INTCPT ESV3 is open.
5.
INTCPT ESV4 is open.
STEP 10 Commands : No command is issued. Monitoring time - 30 Secs CRITERIA FOR STEP 11
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1.
Drains no fault.
2.
Speeder gear position is 100 %.
3.
Seal steam pressure controller on.
4.
Lub oil temperature control valve on AUTO.
5.
Any One oil vapour extractor fan is ON.
6.
Any one Generator bearing Exh. Fan is ON.
7.
Generator bearing extractor fan 1 available.
8.
Generator bearing extractor fan 2 available.
9.
Hydrogen temperature controller is on AUTO.
10.
Hydrogen concentration is > 94%.
11.
Hydrogen Pressure (manifold) > 3 Kg/cm2
12.
DP seal oil Air-Hydrogen side (T.E.) > 0.7 Kg/cm2
13.
DP seal oil Air-Hydrogen side (E.E) > 0.7 Kg/cm2
14.
Pressure seal oil behind pump Hydrogen side > 3 Kg/cm2
15.
Seal oil pre-chamber turbine side level < MAX.
16.
Seal oil pre-chamber excitor side level < MAX.
17.
Liquid Level in Generator < MAX.
18.
Liquid Level in Generator < MAX.
19.
Liquid Level in Generator lead < MAX.
20.
Liquid Level in Generator lead < MAX.
21.
Any one seal oil pump Air side is ON.
22.
Seal oil pump hydrogen side is ON
23.
Seal oil pump 3 Air side voltage is available.
24. 25
Primary water temperature controller is on AUTO. Generator cooling water conductivity < 1.5mS/cm.
26.
Any one Primary water pump is ON. KORBA SIMULATOR
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27.
Pressure after Primary water pump is > MIN.
STEP 11 Commands: No command is issued.. Monitoring time is Blocked. CRITERIA FOR STEP 12 1.
Generator conditions are fulfilled (Step 10).
2.
Steam before HP ESV1 SUPERHEAT > X4.1
3.
Steam before HP ESV2 SUPERHEAT > X4.2
4.
DT (HP ESV1 - HP CASING) > X5.1
5.
DT (HP ESV2 - HP SHAFT) > X5.2
6.
Turbine speed is > 15 rpm.
7.
DT (LP bypass1 - IP CASING ) > 30 0K.
8.
DT (LP bypass2 - IP CASING ) > 30 0K. or
9.
Steam temperature before LP BP1 > 480 0 C
10.
Steam temperature before LP BP2 > 480 0 C
11.
Drain before HPCV1is not closed.
12.
Drain before H.PCV2 is not closed.
13.
Drain before HPCV3 is not closed.
14.
Drain before HPCV4 is not closed. or Turbine speed is > 2850 rpm
15.
Load reference is > 10 %. KORBA SIMULATOR
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16.
Condenser pressure < 0.2 Kg/cm2
STEP 12 Commands : 1.
Turbine speed reference raise. Monitoring time - 40 Secs.
CRITERIA FOR STEP 13 1.
Turbine speed > 360 rpm. or Gen Bkr is ON.
STEP 13 No Command is issued. Monitoring time is Blocked. CRITERIA FOR STEP 14 1.
Turbine speed is > 300 rpm.
STEP 14 Commands: 1.
Wall stress test programme - Block. Monitoring time - 180 Secs Waiting time - 180 Secs.
CRITERIA FOR STEP 15 1.
Wall stress test programme - Block. Waiting time 180 secs lapsed. or
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Wall temp HP Turbine Casing >250 0C 2.
TSE Margins are > 30 0K or Turbine Speed 2850 rpm.
3.
DT (HP BP1 - HP SHAFT) < X 6
STEP 15 Commands : 1.
HPCV Drain Controller switched to manual mode. Monitoring time - 1 Sec.
CRITERIA FOR STEP 16 1.
HPCV Drain Controller on manual.
2.
Gate valve Gearing is Closed.
STEP 16 Commands : 1.
Turbine speed set point raise.
2.
Drain before HPCV1 close.
3.
Drain before HPCV2 close.
4.
Drain before HPCV3 close.
5.
Drain before HPCV4 close. Monitoring time – 200 Secs.
STEP 17 Commands : No Command issued. Monitoring time is Blocked. CRITERIA FOR STEP 18 KORBA SIMULATOR
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1.
Turbine speed is > 2950 rpm. or Gen Brkr is ON.
2.
Bearing vibration Casing & Generator < Max.
3.
Shaft vibration < Max..
4.
Bearing Temperature < Max.
STEP 18 Commands : 1.
AVR is switched to Auto.
2.
Field Brkr is switched ON. Monitoring time 40 Secs.
CRITERIA FOR STEP 19 1.
Field Bkr / AVR ON/AUTO or Gen Bkr ON.
STEP 19 Commands : 1.
Drain before HPCVs (1-4) close . Monitoring time is Blocked.
CRITERIA FOR STEP 20 1.
Both AOPs are OFF (timer 0- 10 secs).
2.
DT (LP BP1-IP shaft) < X7.
3.
H2 Casing Pressure > 3 Kg/cm2 KORBA SIMULATOR
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4.
Temp cold gas after H2 Cooler A/B < 45 0C.
5.
Temp cold gas after H2 Cooler C/D < 45 0C.
6.
Excitation cold air temperature < 45 0C.
7.
Drain before HPCV1 is closed.
8.
Drain before HPCV2 is closed.
9.
Drain before HPCV3 is closed.
10.
Drain before HPCV4 is closed.
11.
One Seal Oil Pump Air side is ON.
12.
Seal oil Pump1 Air side is available.
13.
Seal oil Pump2 Air side is available.
14.
Primary Water Temperature is < 50 0C.
15.
Conductivity main filter is < 1.5 mS/cm.
16.
Primary Water flow in Gen. & Bushing not low.
17.
DT( Primary Water- H2) > 1 0K
STEP 20 Commands : 1.
AVR is switched to Auto. Monitoring time - 15 Secs. Waiting time - 15 Secs.
CRITERIA FOR STEP 21 1. 2.
Waiting time is lapsed.. AVR on Auto.
3.
Generator voltage > 95%). KORBA SIMULATOR
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Or Generator breaker is on and Gen load >10% (Bypass criteria for 1,2,&3) STEP 21 Commands : 1.
Synchroniser ON. Monitoring time - 60 Secs.
CRITERIA FOR STEP 22 1.
Generator Breaker is ON.
STEP 22 Commands : 1.
Load Reference raise. Monitoring time - 1 Sec. Waiting time - 1 Sec.
CRITERIA FOR STEP 23 1.
Waiting time 2 seconds. or
2.
Generator load > 10 %
STEP 23 Commands: No command is issued. Monitoring time -2Secs. END OF PROGRAMME
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S.G.C TURBINE SHUT DOWN PROGRAMME STEP 51 Commands : 1.
SLC drains is switched ON. Monitoring time - 2 Secs.
CRITERIA FOR STEP 52 1.
SLC drains is ON.
STEP 52 Commands : 1.
Load reference lower. Monitoring time - 60 Secs.
CRITERIA FOR STEP 53 1.
Generator load is 0%.
2.
Speed controller in Action.
STEP 53 Commands : 1.
Turbine speed set point lower. Monitoring time - 60 Secs.
CRITERIA FOR STEP 54 1.
Gen Brkr is OFF.
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STEP 54 Monitoring time - 2 Secs. Commands : 1.
Electrical Turbine Trip Channel 1.
2.
Electrical Turbine Trip Channel 2.
3.
Synchroniser OFF.
4.
Field Breaker OFF.
5.
Tracking Device OFF.
CRITERIA FOR STEP 55 1.
Synchroniser is OFF.
2.
HP ESV1 closed.
3.
HP ESV2 closed.
4.
HP ESV3 closed.
5.
HP ESV4 closed.
6.
INCPTESV1 closed.
7.
INCPTESV2 closed.
8.
INCPTESV3 closed.
9.
INCPTESV4 closed.
10.
Trip fluid pr < 5 Kg/cm2 or Starting device 0%
11.
Tracking device is off.
12.
Overspeed Trip 1 off.
13.
Overspeed Trip 2 off.
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14.
Shaft position Trip off.
STEP 55 Commands: 1.
Starting device lower.
2.
Drains HPCV(1- 4) open. Monitoring time 120 secs.
CRITERIA FOR STEP 56: 1.
Drains HPCV(1- 4) closed.
2.
Startind device 0%.
3.
Drains no fault.
STEP 56: No command issued. Monitoring time blocked. END OF SHUT DOWN
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SUB GROUP CONTROL OIL OPERATION START-UP PROGRAMME OPERATION RELEASE: 1.
Any one Oil vapour extractor is ON.
STEP 1: Commands: No command is issued. Monitoring time blocked. STEP 2: Commands: 1.
Auxiliary oil pumps 1 ON. Monitoring time - 5 Secs.
CRITERIA FOR STEP 3 1.
Auxiliary oil pump is ON or Auxiliary oil pump 2 is ON. or Turbine speed is >2850 rpm.
2.
Pressure oil pressure is > 4.8 Kg/cm2
STEP 3 Commands: 1.
Lub Oil temperature controller on Auto. Monitoring time - 20 Secs.
CRITERIA FOR STEP 4 1.
Lub Oil temperature controller on Auto.
2.
DP seal oil (Air - H2) Turbine end > 0.7 Kg/ cm2 KORBA SIMULATOR
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3.
DP seal oil (Air - H2) Exciter end > 3 Kg/cm2
4.
Pressure seal oil behind pump H2 side > 3 Kg/ cm2
5.
H2 concentration is > 94%
6.
H2 pressure in the generator casing > 3 Kg/ cm2
7.
Liquid level in generator < Max.
8.
Liquid level in generator < Max.
9.
Liquid level in generator lead < Max.
10.
Liquid level in generator lead < Max.
11.
Any one Generator bearing chamber Exhauster Fan is ON.
STEP 4 Commands : 1.
SLC Turning gear ON (Monitoring time 60 seconds).
CRITERIA FOR STEP 5: 1.
Gate valve gearing is OPEN. or Turbine speed >240 rpm.
2.
SLC Turning gear is ON.
STEP 5 Commands : 1.
SLC AOP1 ON.
2.
SLC AOP2 ON.
3.
SLC EOP ON.
4.
SLC JOPs ON.
5.
SLC JOP3 ON. KORBA SIMULATOR
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Monitoring time - 200 Secs CRITERIA FOR STEP 6: 1.
SLC AOP1 is ON.
2.
SLC AOP2 is ON.
3.
SLC EOP is ON.
4.
SLC JOPs is ON.
5.
SLC JOP3 is ON.
6.
Turbine speed > 15 rpm.
STEP 6 Commands: No command is issued. Monitoring time - Blocked. CRITERIA FOR STEP 7: 1.
Turbine speed is > 540 rpm.
STEP 7 Commands : JOPs are switched off. Monitoring time 60 secs. CRITERIA FOR STEP 8: 1.
JOP1 OFF.
2.
JOP2 OFF.
3.
JOP3 OFF.
4.
Gate valve gearing is closed.
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STEP 8 Commands: No command is issued. Monitoring time is Blocked. CRITERIA FOR STEP 9: 1.
Turbine speed is > 2850 rpm.
2.
Pilot oil pressure > 7 Kg/ cm2
STEP 9 Commands : 1.
Auxiliary oil pump1 off.
2.
Auxiliary oil pump2 off. Monitoring time - 5 Secs. Waiting time - 0.5 secs.
CRITERIA FOR STEP 10: 1.
Waiting time over..
STEP 10 Commands : No command is issued. Monitoring time - 10 Secs. Waiting time 10 secs. CRITERIA FOR STEP 11: 1.
Waiting time is over. or Generator Load is >10%.
2.
Auxiliary oil pump1 is off.
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3.
Auxiliary oil pump2 is off.
4. EOP is off. STEP 11: Commands : No command is issued. Monitoring time is Blocked SGC OIL SHUTDOWN PROGRAMME. RELEASE CRITERIA 1.
Temperature HP casing TOP 50% < 100 0C.
2.
Temperature HP casing BOTTOM 50% < 100 0C.
STEP 51 Commands : 1.
SLC Turning gear OFF.
2.
Gate valve gearing closed. Monitoring time - 60 Secs
CRITERIA FOR STEP 52: 1.
SLC Turning gear is OFF.
2.
Gate valve gearing is closed.
STEP 52 Commands : No Command is issued. Monitoring time is blocked. CRITERIA FOR STEP 53: 1.
Turbine speed is < 10 rpm.
STEP 53 Commands : KORBA SIMULATOR
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No command is issued. Waiting time - 1000 Secs. CRITERIA FOR STEP 54: 1.
Waiting time 1000 Secs is lapsed . or a.
SLC AOP1 is off.
b.
SLC AOP2 is off.
c.
SLC EOP is off.
d.
AOP1 is off.
e.
AOP2 is off
f.
Lub oil temp. control valve is closed.
STEP 54 Commands : 1.
SLC JOPs off.
2.
JOP1 off.
3.
JOP2 off.
4.
SLC JOP3 OFF.
5.
Oil temperature control valve on manual. Monitoring time - 30 Secs.
CRITERIA FOR STEP 55: 1.
SLC JOPs off.
2.
JOP1 off.
3.
JOP2 off.
4.
SLC JOP3 off.
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5.
Oil temperature control valve on manual.
6.
JOP3 OFF.
STEP 55 Commands : 1.
SLC AOP1 off.
2.
SLC AOP2 off.
3.
SLC EOP off.
4.
AOP1 off.
5.
AOP2 off.
6.
Oil temperature control valve closed. Monitoring time - 30 Secs
CRITERIA FOR STEP 56: 1.
SLC AOP1 off.
2.
SLC AOP2 off.
3.
SLC EOP off.
4.
AOP1 is off.
5.
AOP2 is off.
6.
Oil temperature control valve is closed.
7.
EOP is off.
STEP 56 Commands: No command is issued. Monitoring time - Blocked. END OF PROGRAMME
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SGC - EVACUATION START-UP:RELEASE 1.
Any one Seal steam exhauster fan is on.
2.
Any one CEP is on.
3.
Air header1 air isolating valve IV open.
4.
Air header2 air isolating valve IV open.
STEP 1 Commands : 1.
SLC Drains switched on. Monitoring time - 2 Secs.
CRITERIA FOR STEP 2: 1.
SLC Drains on. Or Condenser Pressure 15 rpm.
2.
Condenser pressure < 0.85 Kg/ cm2
STEP 5 Commands : 1.
Gland steam pressure controller on auto. Monitoring time - 30 Secs
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CRITERIA FOR STEP 6: 1.
Gland steam pressure controller on auto.
2.
Shaft seal steam pressure is not high.
3.
Shaft seal steam pressure is not low.
STEP 6 Commands : No command is issued. Monitoring time - Blocked. CRITERIA FOR STEP 7: 1.
Condenser pressure is < 0.12 Kg/ cm2
2.
Generator Load > 5 %.
STEP 7 Commands : 1.
Vacuum pump 1 or 2 OFF.
2.
Air valve 1 or 2 closed. (If the vacuum pump 1 or 2 pre-selected respectively) Monitoring time - 60 Secs.
CRITERIA FOR STEP 8: 1.
Vacuum pump 1 is OFF, Air IV 1 closed. Or
2.
Vacuum pump 2 is OFF, Air IV 2 closed.
STEP 8 Commands: No command is issued.
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Monitoring time - Blocked. CRITERIA FOR STEP 9: 1.
Condenser pressure > 0.12 Kg/ cm2
STEP 9 Commands: 1.
Vacuum pump 1 ON & Air IV1 open.
2.
Vacuum pump 2 ON & Air IV2 open.
Monitoring time -120 Secs. CRITERIA FOR STEP 10: 1.
Vacuum pump1 ON & Air IV1 open.
2.
Vacuum pump2 ON & Air IV2 open.
Commands: No command is issued. Monitoring blocked. SGC EVACUATION SHUTDOWN :Release Conditions: Nil. CRITERIA FOR STEP 51: 1.
Turbine speed < 200 rpm.
STEP 51 Commands : 1.
Vacuum pump1 OFF.
2.
Air IV1 close.
3.
Vacuum pump2 OFF.
4.
Air IV2 close. Monitoring time - 60 Secs
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CRITERIA FOR STEP 52: 1.
Vacuum pump1 OFF.
2.
Air IV1 closed.
3.
Vacuum pump2 OFF.
4.
Air IV2 closed.
STEP 52 Commands : 1.
Vacuum breaker open. Monitoring time - 30 Secs.
CRITERIA FOR STEP 53: 1.
Vacuum breaker open.
STEP 53 Commands : 1.
SLC drains ON.
2.
Gland steam pressure controller on manual.
3.
Gland steam control valve closed.
CRITERIA FOR STEP 54: 1.
SLC drains ON.
2.
Gland steam pressure controller on manual.
3.
Gland steam control valve closed.
STEP 54: Commands : 1.
No command is issued.
2.
Monitoring time is blocked. END OF SHUT DOWN PROGRAMME KORBA SIMULATOR
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SGC HP CONTROL FLUID - START UP RELEASE:
HP Control fluid tank temp.> 20 0C.
STEP1 Commands : 1.
SLC CTRL FLUID PUMPS ON.
CRITERIA FOR STEP2: 1.
HP Control Fluid pr is > 30 Kg/cm2.
STEP 2 Commands : 1.
HP C/F Control valve on Auto.
2.
SLC Ctrl Fluid Heater ON.
3.
HP C/F Circ P/P1 ON.
SGC HP CONTROL FLUID SHUT DOWN SHUT DOWN RELEASE : 1.
Boiler Fire is off
2.
Seal Steam pr Control is off.
3.
Condenser 1& 2 Abs pressure is >.4 Kg/cm2
4.
Gland Steam valve is closed.
STEP 1 Commands: 1.
HP Control Fluid Pump 1 & 2 off
2.
HP Control Fluid Circulating Pump 1 & 2 off
3.
SLC HP Control Fluid Off
4.
HP Control Fluid Temp. control valve Manual
5.
HP Control Fluid Temp. control valve close.
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SGC GENERATOR EXCITER Drying: Generator exciter drying is switched on automatically if SLC is on and turbine speed is less then 210 rpm. The exciter dome and frame flapper are closed on interlock with drying ON. Similarly if turbine speed is more than 240 rpm, and the SLC is on the Gen. Exciter dryer is switched off. Heating: If SLC Exciter dryer is on & the speed of turbine is 240 rpm and top casing temp >500C Heating is switched off. Also if dryers are off, Heating is switched off on interlock. If the heating is switched on, it shall also, automatically close exciter dome flap and flaps 1 & 2 on frame. Excitor flap(Dome): It is opened automatically on protection if cold air temperature is >450C or manually through P.B. Open command. Exciter flap is closed automatically if exciter heating is On or drying is on. The release for closing is, frame flaps 1 and 2 must be closed. The manual P.B. command for closing can close the exciter flap (dome) if release is available. Exciter Flap Frame(1/2): Release:If exciter flap(dome) is open and cold air temperature is >450C, frame flaps 1 & 2 are opened on protection or through manual push button commands flaps can be opened. Alarms: Exciter drying not ON: When turbine speed is 210 rpm and exciter top casing temperature is 240 rpm and drying or heating is on GENERATOR FIELD BREAKER:
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The field breaker is released for closing only if turbine speed is >2850 rpm. It can be closed by manual “close” command or by auto SGC TURBINE command (step-18) AUTO SYNCHRONISER: It can be switched on if manual synchornise SGC “release “ command is issued and SGC Turbine step 21 Auto synchroniser ON Command is available or manual “on” command P.B. is pressed: provided turbine speed is more than 2850 rpm. The synchorniser is switched ON if any of the following conditions are not present •
Manual “off “command
•
AVR fault
•
EHC speed control fault
•
SGC turbine step 54(Shut down from ATRS)
•
Generator breaker is on.
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ELECTRICAL PROTECTION
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ELECTRICAL PROTECTION 1.
Differential Protection : a. Generator Differential (87GR, 87GY, 87GB) b. GT HV winding differential cum overhead line protection (87HVR, 87HVY, 87HVR) c. UAT differential (87 UTA, 87 UTB) d. GT differential protection (87 T) e. GT Overall Differential Protection (87 GT)
2.
Earth Fault Protection : a. Stator earth fault standby E/F b. ( 64 G1, 64G2, 64 G3) c. GT standby E/F protection (51 MGT)
3.
Stator interturn fault
4.
Negative phase sequence
5.
Generator back-up impedence protection
6.
Loss of excitation
7.
Pole slipping
8.
Over voltage
9.
Over fluxing
10.
Low forward power
11.
Reverse power
12.
Generator LBB protection
13.
Generator transformer protection a) Buchholtz operation b) Winding temperature high c) Oil temperature high KORBA SIMULATOR
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d) Fire protection 14.
UAT protection
DIFFERENTIAL PROTECTION GENERATOR DIFFERENTIAL A direct short circuit between different phases with or without ground fault of the winding causes a severe fault current to flow inside the affected machine and cause highly extensive damage. As a result there is a distinct difference between the current at the neutral and terminal ends of the particular winding. This difference is detected by the differential relay. The current entering and leaving the protected object is determined by current transformers and compared by relays by means of a differential circuits. A fault inside the protected zone is fed from either one side or both sides depending upon the current sources present, thus producing a difference current in the differential circuit. If this differential current exceeds a set percentage of the current flowing in the protected object, the relay picks up. The relays used is designated 87GR, 87GY, 87GB type CAG34. It is set to operate current which corresponds to 1000 Amp fault current . 5% of 5 amp with stabilising resistors. Rstab = 400 ohm. UATS DIFFERENTIAL Since UATs are connected directly to the stator windings, so it has been provided with a biased differential protection in a similar circulating current scheme. The relay are designated 87 UTA and 87 UTB are DTH 31 type. GT OVERHEAD LINE DIFFERENTIAL The 400 KV bushings of the generator transformer are connected to the switchyard by double moose conductor overhead line. Any fault occurring on these lines is detected by overhead line differential protection. The relay designated 87 HVR, 87HVY, 87HVB CAG 34 type 0.1 amp with stabilising resistor of 685 ohm. It picks up at 100 Amp. fault current. G T RESTRICTED EARTH FAULT The H.V. winding of the generator transformer is star connected and the neutral is solidly earthed. The protection is meant for complete protection of H.V. winding of generator transformer. The delta side of the generator transformer is considered as a part of the generator and its earth fault would cause the earth fault current to flow towards the generator neutral and be detected as generator earth fault.
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The relay designated as 64 GT and is CAG 14 type one amp and impedence definite current attracted armature type. G.T. OVERALL DIFFERENTIAL Since generator transformer is directly connected to it would be proper to include the transformer windings including those for UAT HV side and conductors in a current protection scheme. The relay is designated 87 GT and is of DTH 32 type 5 Amp which is a biased differential type relay. Biased setting of 30% is used to prevent the relay operation in case of a through fault when the current transformer may saturate and produce an erroneous secondary current. EARTH FAULT PROTECTION STATOR EARTH FAULT (MAIN) The generator neutral is earthed through the primary winding of neutral grounding transformer of the rating 60 KVA, 18/.24 KV ratio. The secondary winding of the transformer is shorted through loading resistance of 0.410 ohms. For an earth fault in the generator the E/F current flows in the primary of the neutral grounding transformer. As a result a voltage across the resistor is developed which activates stator E/F sensing relay. The reason for this kind of protection is due to the mechanical damages resulting from the insulation fatigue creepage of the conductor bases, vibration of the conductors or other fittings of the cooling systems. The earth fault relay designated is VDG 14 type 64 G 1. The relay has a inverse definite minimum time characteristics. Generally 5% of the generator winding starting from neutral point remains unprotected because a fault in this portion will generate too low a voltage for relay operation. STATOR STANDBY EARTH FAULT The relay is connected across an open delta of the generator PT secondary windings. When there is no E/F the sum of the phase voltages of the generator and hence the voltage across the relay is zero. The voltage across the point A & B will assume a positive value when one phase voltage of the generator drops because of earth fault on that phase. The relay designated is 64 G2 VDG 14 type. It has an inverse time voltage characteristics.
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ROTOR EARTH FAULT Ground leakage in the rotor circuit of a generator does not adversely affect operation, if it occurs only at one point. Danger arises if a second fault occurs causing the current to be diverted in part at least, from the intervening turns which can burn the conductor causing severe damage to rotor. If a large portion of winding is shorted the field flux pattern may change causing the flux concentration at one pole and wide dispensation at the other. The attractive forces which are proportional to the square of the flux density will be stronger at one pole than the other which will cause high vibration and may damage the bearings and may sufficiently displace rotor thereby fouling the stator. Rotor E/F is proved by monitoring the I / R value of rotor winding. < 80 k ohm < 5 K ohm
Alarm Trip
STATOR INTER-TURN FAULT When leakage occurs between the turns in the same phase of a winding the induced voltage is reduced and there will be a voltage difference between the centre of the terminal voltage triangle and the neutral of the machine. Therefore, in a generator having one winding per phase, a voltage transformer is connected between each phase terminal and neutral of the winding, the secondary transformer leads being connected in open delta, when inter-turn leakage occurs at the ends of the open delta, it is detected by a polarised voltage relay. For generators having several parallel windings per phase, the neutral ends are connected together to form as many neutrals as there are parallel windings per phase. These neutrals are then joined through current transformer to current relays, or through voltage transformer to voltage relay. If an inter-turn fault occurs in the machine, the current transformer carries a transient current or alternatively voltage transformer produces a voltage thereby picking up the relay and tripping the generator. The relay is designated 95G, is a VDG 14 type 5 amp attracted armature voltage operated IDMT (Inverse Definite Minimum Time) type . NEGATIVE PHASE SEQUENCE A three phase balanced load produces a reaction field which is constant and rotates synchronously with the rotor field system. Any unbalanced condition could be resolved into positive, negative and zero sequence components. The positive sequence component is similar to the balanced load. The zero sequence components does not produce armature reaction. The negative sequence component is similar to that of positive sequence but the resulting reaction field rotates in the opposite direction. Hence the flux produced by the negative phase sequence current cuts the rotor at KORBA SIMULATOR
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double the rotational speed thereby inducing double frequency current. As a result eddy currents produced are very large and cause severe heating of the rotor windings particularly damper windings. For any current conditions in the three phases the amount of unbalance can be determined from the values of the negative sequence components I2 of current by the method of symmetrical components. The degree of unbalance is taken to be the value of the negative sequence current component expressed as percentage of rated current. The losses in the rotor are proportional to the square of the degree of unbalance. This generator has I22.t =8 characteristics indicating that within the generator is capable of withstanding but beyond it there is time delay of 5 sec. The time delay has to be matched to the machine negative sequence current withstand capability. The relay used is designated 46GA, 46GT and is of solid state design & CTNM+VTT11 type with fixed resistors. GENERATOR BACK-UP IMPEDANCE PROTECTION A three phase zone impedance relay is provided for the back-up protection of generator against external three phase and phase to phase fault in 400 KV system. The zone of impedance relay should be extended beyond 400KV switchyard and it should be connected to trip the generator after a time delay of 2 seconds so that the generator is tripped only when 400KV protection has not cleared the fault even in the second zone. The relay used is designated 21GRY, 21GRB, 21 GBR, type CG15A FIELD FAILURE. Failure of the field system leads to losing of synchronism and resulting in running above synchronous speed. It acts as an induction generator, the main flux being produced by wattless stator current drawn from the system. Operation as an induction generator necessitates the flow of slip frequency current in the rotor, damper winding, slot wedges, excitation under these conditions requires a large reactive component which approaches the value of rated output of the machine. Since rotor would get overheated due to slip frequency current, the machine should not run more than a few seconds without excitation. Also it could overload the grid which may not be able to supply the required excitation MVAR. When loss of excitation is accompanied by under voltage it will initiate class A trip. Otherwise class B trip if the grid is able to sustain the voltage dip. The relay used is designated 40 G YCGF11 type.
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POLE SLIPPING The asynchronous operation of the machine while the excitation is still intact unlike loss of excitation, causes severe shock both to machine and grid due to violent oscillations both active and reactive power. Because of it the machine may fall out of step or usually known as pole slipping trip. The oscillation may disappear in a few seconds in which case it is not desirable to trip the machine. If however the angular displacement of the rotor exceeds the stability limit the rotor will slip a pole pitch. If this disturbance has been sufficiently reduced by the time this has occurred, the machine may regain synchronism, but if it does not, it must be isolated from the system. The swing curves can be detected by an impedance relay. The relay has measuring elements set at two values near the impedance as seen by the relay. As the impedance seen by the relay changes it comes in the operating zone of the two relays one after the other. The sequential operation is observed by auxiliary relays. Since the system faults would suddenly change the system impedance both the relays shall operate within 55 cms. However, during pole slipping the two elements would operate sequentially and a trip command is given when both have operated. The relay can be set to be in operation for swings up plus minus 90 deg. Corresponding to the stability limit of the generator. The relay used is designated 98G and is of solid state design of ZTO11 + YTGM14. In order to discriminate against swings on the grid the tripping is through impedance, relay (98 GY) set with a reach upto the 400KV yard. Current setting is 90% of 5 amp. OVER VOLTAGE The generator winding is rated for 21 KV terminal voltage sustained over voltage would unduly stress the winding insulation and may lead to failure after some time. To protect the machine against over voltage the protection relay senses the voltage at the secondary of the bus duct Pts. The relay is set to operate at 105% rise in the terminal voltage. A time delay of 3 seconds is provided to take care of transient over voltage arising from line charging, switching capacitive faults etc. The relay used is designated 59G & is VTU 21 type 110V A.C. G.T. OVER FLUXING The iron core of the generator transformer carries the flux to produce required emf. If the flux increase unduly the magnetic circuits of the generator, generator transformer become over saturated resulting in high magnetising current. This in turn leads to higher iron losses which will increase the winding temp. of the transformer. Since core can be damaged because of the overheating, protection has to be provided against it. The flux is dependent on ratio of voltage & frequency.
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The condition of over fluxing could arise in case the voltage at the machine terminal rises or its frequency drops or both occurring simultaneously. Practically this condition will arise if the machine AVR misbehaves thereby unduly increasing the voltage even when the grid frequency is low. The relay used is designated 99GT and GTT21 + VTT11 type which senses v/f ratio at the secondary of the bus duct P.T. and gives alarm and trip signals at different time delay. The adopted setting for relay is v/f = 1.18 P.U. i.e. 20% higher than rated v/f ratio. Alarm is set at .5sec and trip at 2 sec.. This v/f relay also generates a AVR ‘ Raise’ block. Surge voltages originating from lines because of switching or atmospheric disturbances are dealt with directly by lightning arrestor and surge diverters. LOW FORWARD POWER PROTECTION When a generator, synchronised with grid, loses its driving force the generator remains in synchronism. The generator should be isolated from the grid after the steam flow ceases and the flow of power to grid reduces to minimum i.e. the point when the generator starts drawing power from the grid and acts as motor. When the load on generator drops to less than 0.5 percent, generator low forward power relay gets energised and with turbine tripped or stop valves closed, trips the generator with a time delay of 2 seconds. This is a protection to trip generator other than electrical faults. Also this protection is used for a few electrical faults where generator trip can be delayed. However, provision for time lag unit is there to prevent undesired operation from transient power reversal. The power relay used is designated 37GA, GB and is a WCD13+VTT11. acts as a final back-up to both L.P.F. protection. Local Breaker Back-up Protection This is a protection against the main generator breaker failure which may occur due to i) Mechanical failure ii) Trip circuits not healthy Hence, this protection acts as a back-up to the main generator by tripping all the breakers connected to that particular bus.
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RELAY SENSING: i)
D.C. to the relay extended through the trip command (either 86G or 286 G or B/B protection trip)
ii)
Over current element senses that generator breaker that generator breaker contacts have failed to open.
When both above conditions satisfied LBB protection acts with a timer ( 0.2 secs.) to trip all other breakers connected to that bus. The LBB protection initiates bus bar protection. (Refer to the bus bar protection scheme). The relay used is designated as 50Z, CTIG39+VTT11 type. GENERATOR TRANSFORMER PROTECTION (A)
G.T. BUCHHOLZ OPERATION
Any internal fault in generator transformer the winding temperature increase rapidly resulting in vaporisation of oil dissociation of oil accompanied by generation of gas. The generator gas is utilised for relay operation., The relay is a gas operated device arranged in the pipe line between the transformer tank and separate oil conservator. In the fig. The vessel is full of oil. It contains two floats B1 and B2 which are to be hinged and to be passed by their buoyancy against two stops. If gas bubbles are generated in the transformer due to fault, they will rise and get trapped in the upper part of the relay chamber thereby displacing the oil and lowering the float B1. This sinks and eventually closes an external contact which operates as an alarm. If the rate of generation of gas is small the lower float B2 is unaffected. When the fault is dangerous and gas production is violent the sudden displacement of oil along with the pipe tips the float B2 and causes a second contact to be closed and making the trip circuit and operating the main switches on both HV & LV side. Gas is not produced until temperature exceeds about 150 deg.c., so momentary overload of transformer does not affect the relay unless the transformer is really hot. Also insufficient oil level in Buchholz relay could lead to inadvertent operation of the same. B)
THERMAL OVERLOAD PROTECTION
Vapour pressure thermometers or resistance temperature detectors are used for this purpose. The transformer winding temperature and oil temperature are continuously monitored; when the temperature reaches a certain value it will give indication. Then the load on the transformer is to be reduced. If the temperature rises still further tripping will take place.
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C) FIRE PROTECTION Sprinkler system is used to protect the transformer from fire hazards. Sprinkler installation comprising a system of interconnected pipes into which sprinkler heads are fitted on a definite basis of distribution, according to the network design. Sprinkler heads are so constructed that the heat arising from fire will cause them to rupture. Generally the sprinkler system consists of a compressed air line and a water line. Sprinkler heads are provided in the compressed air line. The compressed air line will always be in changed condition and prevents the contractor from entering the water line. When the sprinkler heads then the pressure in the water header will open to send the water into the water header, from water will be sprinkled on to the transformer.
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GENERATOR PROTECTION
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GENERATOR PROTECTION
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GENERATOR PROTECTION
POWER PLANT CHEMISTRY
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POWER PLANT CHEMISTRY INTRODUCTION: In a modern Thermal Power Plant, the life expectancy of equipment is about 30-40 years. The plant utilizes the best material and technology in designing the critical plant items such as boiler, turbine generator etc. The control of chemical parameters is an important task to achieve the goal set for the life of a power plant. The control is being done at various stages in operation of the plant. The objectives of water Chemistry control are: 1.
Prevent or minimise corrosion in boiler, feed and steam systems.
2.
To prevent or minimise deposition of oxides or scales on heat transfer Surfaces. To maintain high level of steam purity and thus prevent problems in the super heater, reheater and turbine.
3.
Besides above Power Plant Chemistry covers a vide area of service which affect the station availability and efficiency as well as Operation, Maintenance and Safety. to achieve the objectives the control are divided into following headings: 1.
Water Treatment
2.
Chemical control of Water/Steam cycle
3.
Control of quality of lubricating/control fluids
4.
Control of fuel quality
5.
Monitoring losses, equipment efficiency and environment
WATER TREATMENT : DESIGN The design & operation of W.T. Plant depends upon the feed & boiler water requirement. In Korba Super Thermal Power Station the design parameter for the W.T. Plant are as follows: (for 3 x 500MW units) Sl No
Parameter
pH
Turbidity NTU
Organic ppm
SiO2 ppm
Conductivity ms/cm
1
Clarified Water D.M.Water
7.0-7.5
10-20
Nil
--
--
6.8-7.2
--
Nil
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