Mtps Project Report

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?  Ê? ? ? This is a project report on the basic overview of a THERMAL POWER PLANT and all other systems that are required to carry out the process of power generation. This project was a part of our curriculum of four years B.Tech degree course. This was a training program for 21 days at Mejia Thermal Power Station under Damodar Valley Corporation; carried out by 5 students of Siliguri Institute of Technology, named as 1>Abhishek Mitra Dhananjay Kr. Tiwari Prashant Sharma Anirban Chakroborty and Sayantani Biswas, belonging to Electronics & Instrumentation Engineering Department ,at the end of 4th semester. We have carried out this training under well experienced and highly qualified engineers of MTPS, DVC of various departments viz. Mechanical, Electrical, Chemical and Control & Instrumentation depts. This report covers an overview of a thermal power station, detailed specifications of MTPS,DVC, mechanical overview, electrical overview, various cycles and processes (viz. Steam Generation, Turbo Generation and Balance of Plant) of power generation and details of control and instrumentation required in thermal power plant. We have taken the opportunity to explore the Control & Instrumentation Department, its use, necessity in power plant and maintenance of various instruments used for monitoring and controlling the numerous processes of power generation. We have tried our best to cover all the instruments and their brief detailing in this project report. We have also included our field experiences of MTPS and maintenance section of C&I(Control & Instrumentation) of MTPS and Logic Panels provided by BHEL (known as FSSS) and DCS/Microprocessor based system provided by SIEMENS and also Logic and Microprocessor based system by MAX-DNA. We have also covered a section on SMART TRANSMITERS and ANALYTICAL INSTRUMENTATION. All the above mentioned topics will be presented in the preceding pages of this report. The main aim to carryout this training was to familiarize ourselves with the real industrial scenario, so that we can relate what we study in our textbooks and their practical applications. This project report will also help us in our future in many ways when we face the industrial world.

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1. Dhananjay kumar Tiwari 2. Abhishek Mitra 3. Anirban Chakraborty 4. Prashant Sharma 5. Sayantani Biswas have carried out this dissertation training report based on the vocational training done by us in the highly appraised, one of the most technically advanced and one of the largest thermal power station in West Bengal the Mejia Thermal Power Station ,under DVC . We would like to express our heartfelt gratitude to the authority of SILIGURI INSTITUTE OF TECHNOLOGY&MEJIA THERMAL POWER STATION for providing us the rare opportunity to undertake training in the power plant. We would also want to thanks the highly supporting and experienced engineers without whom we could not have know the plant better. We would personally like to thanks to 1. Mr. K.C ROY (DEPUTY CHIEF ENGINEER) 2. Mr.P.K.DUBEY 3. Mr. TAPAS SENGUPTA (AE) 4. Mr. Gunjan Kr.Chowdary (AE) 5. Mr. Tarun Prasad (AE) We would also like to thanks the maintenance department of C&I (unit iii) to make us understand the instruments better and the staff of MTPS to help us learn

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?? ? ? ? ? Damodar Valley Corporation was established on 7th July 1947.It is the most reputed company in the eastern zone of India..DVC in established on the Damodar River.It also consists of the Durgapur Thermal Power Plant in Durgapur. The HYDEL project in Mython is one of the most flourishing parts of the DVC. The MTPS under the DVC is the second largest thermal plant in West Bengal. It has the capacity of 1340MW with 4 units of 210MW and 2 units of 250MW.With the introduction of another two units of 500MW that is in construction it will be the largest in West Bengal.

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Ê ?  ?Ê ? ??Ê? Ê? ?Ê ? The idea that STEAM has potential energy and can be converted into kinetic energy was given by famous scientist, Sir. James Watt. This idea became the governing principal of many mechanical processes and finally led to the success of Thermal Power Energy. The need of establishing a Thermal Power Plant came to engineers by the realization of the fact that Hydel Power could be utilized only for certain period of time in a year. This section will give the basic requirements for Thermal Power Plant. >? 2       The basic requirements of thermal power plant is determined by the type,size and other specifications of the plant. It is required to know the immediate capacity of the power plant after construction and the extension of capacity in the future, to determine the area required for construction of the plant. The basic things that are taken into consideration are 1>Station Building Coal Store Cooling Towers Switch yard compound Surrounding areas and approaching. >?    The geology of the site should be cost effective and the subsoil must be able to withstand huge load of foundation. >?     Water is required in power plant for two basic needs, first is for steam generation and second is for cooling purpose. Thermal Power Plant requires huge volume of water, nearly of about 3 to 4 Tons/hr/MW only for steam generation. So site of plant must also have reliable and huge water sources located near to it. >?
Coal is the prime requirement of any thermal power plant, it is the main source of fuel as it is most economic and residue of coal after combustion is also used by many industries like cement industries, so the plant must have reliable sources of coal and regular supply in huge amount like 20,000 Tons per week. >? 2   It is one of the another vital factor of the plant as huge burden lies on transportation in daily basis because of huge need of coal, furnace oil, hydrochloric acid and other chemical products along with mechanical products. >? 2 2   2Due to heavy rate of coal combustion residual volume is also high. The main residual product is ash. The plant must have facilities like ash pond to dispose them safely without harming the environment. >? 222 The plant area must have route available for transmission over head cables to the nearest grid lines or load points which will be capable of accepting the generated power output of the power station. >?


   The tropical climate is best for erection of thermal power plant, because areas having high humidity and fluctuating temperature lead to dew point and condensation which as a result damages the electrical machines and corrodes the insulation and over head cables.  >?     2  The airfields must be studied properly to avoid mishaps as the chimney height ranges from 500 to 600 fts and boiler housing is of 200 fts in general. >? 2      2  To run a plant smoothly requirement of skilled and unskilled personnel is very important. So recruitment of workers and skilled personnel should be made carefully and in adequate amount. >?   2Some considerations like availability of hospital, educational institutes and other facilities must be taken into account.   

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Ê? Ê? ? Ê ?Ê?Ê?Ê ? Mejia Thermal Power Station also known as MTPS is located in the outskirts of Raniganj in Bankura District. It is one of the 5 Thermal Power Stations of Damodar Valley Corporation in the state of West Bengal. The total power plant campus area is surrounded by boundary walls and is basically divided into two major parts, first the Power Plant area itself and the second is the Colony area for the residence and other facilities for MTPS͛s employees. š? 

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 1)? Total number of Units

: - 4*210 MW with Brush Type Generators

????????????????????????????????????????????2*250 MW with Brush less Type Generators

2)? 3)? 4)? 5)? 6)? 7)?

Total Energy Generation :Source of Water : - Damodar River Sources of Coal : - B.C.C.L and E.C.L, also imported from Indonesia Required Water Consumption : Approximate coal requirement : - 73,00,000Tons/annum at 75% PLF(Plant Load Factor) Ash Deposited per annum : - 1.30 million Tons/annum

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 2       1)? The plant is designed and engineered by both Bharat Heavy Electricals Ltd (BHEL) and Damodar Valley Corporation. 2)? Pipelines of 17km long and 1473mm in diameter spiral welded MS pipes laid to transport river water from upstream of Durgapur barrage by pump sets of 500KV pump motor set. 3)? Rail cum Road Bridge across Damodar River near Raniganj Station. 4)? 2KM Merry Go Round Railway System. 5)? 20mtr high RCC multiple flue stack. 6)? Direct ignition of pulverized coal introduced for reduction in consumption of fuel oil. 7)? Ball and Tube type Mills for more mill rejects and less maintenance cost. 8)? Boiler of 200ft height and four corner firing system for better combustion. 9)? All major and hazardous systems like Steam Generation and Turbo Generation section are incorporated with FSSS (Furnace Safety Supervisory System) for better safety. 10)?Other logic systems like EAST and ATRS are also incorporated. 11)?Water treatment Plants along with two artificial water reservoirs and Two Demineralization Plants loaded with PLC system. 12)?Chimney height upto 600fts for less pollution. 13)?The plant is loaded with latest technology sensor, transducers and transmitters for more accurate analyzing of various processes. 14)?All the units are loaded with intelligent smart microprocessor based systems known to be DCS systems provided by KELTRON, SIEMENS and MAX-DNA for process control. 15)?Station Service Transformers of 6.6KV step-down type are also available for better distribution of power inside the plant for various requirements. 16)?Switchyard with individual step-up generator transformers of ONAN/ANOF/AFOF cooling Transformers of 220KV for supply to national grid, along with other safety instruments.

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? ?? ? ? THE BASIC SCHEMATIC OF THERMAL POWER PLANT COMPRISING OF ALL SYSTEMS IS GIVEN BELOW

THE ABOVE DIAGRAM IS SELF EXPLANOTORY.DETAILED EXPLANATION OF EACH SYSTEM IS GIVEN BELOW.

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      Boiler is the main section where the steam is produced by coal combustion. Boiler consists of boiler drum, water walls, wind box, heaters. The boiler has 13 elevations named as AA-A-AB-B-BC-C-CDD-DE-E-EF-F-FF. Coal is inserted into the boiler from A-B-C-D-E-F elevations. BC is used for insertion of Heavy Oil and Light Oil after atomization with steam and air respectively. DF is used for insertion of oil i.e. only heavy oil. Both the elevations have Oil Gun mounted for insertion of oil in proper ratio into the boiler. Liquid fuel (viz. Heavy Oil and Light Oil) is used for initial light up process. Other elevations are used to insert secondary air from wind box. The furnace is divided into two sections named as first pass and second pass separated by Goose Neck. The combustion takes place in the first pass and the heating of steam through super heaters takes place in the second pass.

š?    Boiler Drum is the part of boiler where the dematerialized water is stored and is inserted into the boiler. It is also houses the steam that is formed in the boiler. Water stored in the drum comes down to the top of the boiler and forms a ͞Water Ring͟ which is then inserted into the boiler through the water walls. Water Walls are basically tubes along the walls of the furnace, it is here where the water is converted into steam at 1300϶C and then the produced steam is taken back to the boiler drum. The drum has a propeller that rotates at high speed and makes the steam and water separated due to centrifugal force. The pressure of boiler drum is 150kg/sq.cm and must be always maintained. Water in the drum comes from feed control station via economizer. 



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Courtesy SIEMENS DCS SYSTEM and C&I Dept, MTPS, DVC

š? 2   2  2 One most important point is to be always kept in mind that all the heaters that are used in thermal power plant are mechanical type heaters, i.e. heat exchange phenomena heats one medium by exchanging heat from another hotter medium. Super heaters are actually suspended pipes in the second pass section of the boiler, the flue gas having very high temperature heats the steam that comes from the drum before they hit the turbines. The steam from drum is carried by these pipes and flue gas heats them to raise their temperature upto 540϶C.

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 There are three super heaters named as Primary Super heater, Platinum Super heater and Final Super heater. The steam is cascaded through the above heaters where the pressure is kept constant and the temperature is raised up to 540϶C. The main concept behind making the steam super heated is to make the steam absolutely moisture free before they hit the turbines because moisture content of steam will damage the blades of turbine by corrosion.

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   The turbine section consists of three parts named as High Pressure Turbine (HPT), Intermediate Pressure Turbine (IPT) and Low Pressure Turbine (LPT). The super heated steam from the super heaters enters the HPT and hits the blades at 150kg/sq.cm and 540϶C and rotates the shaft. The exhaust steam of HPT is taken to high pressure heater and the other part enters the IPT through a reheating section called reheater for enabling the steam to regain its previous state. The exhaust steam of IPT is used for several purposes, one part is taken to deareator, another to high pressure heaters and the left out part is taken to LPT. The exhaust of LPT is taken to condenser.  š?    The turbines are attached through a single shaft which is finally coupled with the generator͛s rotor. The details of the generator are explained later in the Turbo Generation section.  š?
 2 The exhaust steam of LPT is fed to the condenser where the steam is converted into water by the principal of condensation. The condenser has two extraction pumps known as Condensate Extraction Pumps (CEP-A & CEP-B); these pumps create a negative pressure i.e. vacuum in the condenser for better suction of the condensate. The outlet of the CEP is connected to Low Pressure Heaters (LPHS); where the temperature of the condensed water is raised to little higher temperature for better efficiency of the overall unit/plant.

š?    The condensed water from the condenser is taken to deareator where the water is made free from oxygen mainly i.e. free from air. The deareator is a direct heat exchanger because the steam from IPT is sprayed to the condensed water from the bottom and the water is sprayed from the top part of the deareator. This results in de-oxyfication i.e. removal of oxygen from the water.

 š?      2   - The outlet of the deareator is connected to boiler feed pumps, there are three BFP in a row out of which two are in running condition and one is at standby. These pumps have the highest pressure through out the plant i.e. 160kg/sq.cm and consume the highest power of 3MW/pump. It is so because the BFP pumps the deareated water back to the boiler drum which has a pressure of 150kg/sq.cm, and in order to pump the water to the drum it needs higher pressure than the drum. The BFP assembly consists of 3 main parts, booster pump to raise the pressure of water from deareator from 7kg/sq.cm to 17-20kg/sq.cm; asynchronous motor and hydro-coupling of shaft of motor and pump for speed control and longevity and finally the main pump that raises the pressure from 17-20kg/sq.cm to 160kg/sq.cm. The inlet and outlet of the main pump is connected in a feedback system that practically equalizes the pressure of inlet and outlet and as a result the huge jerk that may damage the BFP due to huge pressure difference at inlet and outlet is avoided.



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š?    22   2

2 The high pressure heaters are also mechanical heaters that receive their heating medium from exhaust of HPT & IPT. The BFP outlet is connected to HPHS, there are two HPH named as HPH-5 and HPH-6. HPH-5 receives steam from IPT and HPH-6 receives steam from HPT. The BFP outlet is connected to HPH-5 and HPH-6 is connected to HPH-5. Steam of HPT & IPT heats the water up to 200϶C and the pressure is also increased up to 175kg/sq.cm, which is then passed through economizer. This is done to increase the efficiency of the boiler. These heaters are sometimes bypassed during the process if required by the operator with the help of three way cock/valve of pneumatic type.

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    Economizer is another heat exchanger type heater. Here the water from HPHs comes to get more heated up for better steam production and high enthalpy resulting in greater efficiency of the boiler and unit as well. The economizer receives the heat for heating the water from the flue gas. The flue gas which has very high temperature comes from the air pre-heaters (explained later) to the economizer and heats up the water mechanically which finally reaches the boiler drum.

   2    š?     The flue gas produced as a result of combustion of fossil fuel in the furnace is taken to the air-preheater. The air-preheater is used to heat up the atmospheric air to make hot air used for combustion and transport of coal dust from mill to furnace; which is called secondary air. This heater has a unique process of heating, it has a shaft attached to a rotating wheel type structure (like turbine but arrangement of blades are different). Atmospheric air sucked by FD fans passes through one side of the rotating shaft and the hot flue gas passes through another side. This way heat of the flue gas gets transferred to the atmospheric air and it gets heated. There are two air-preheaters named as AH-A and AH-B. These heaters can be found beside the boiler in the burner floor.

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   2  The flue gas after passing through the air-preheaters comes down to lower temperature that is feasible for releasing into the atmosphere, but one vital job remains still left out, i.e. to remove the carbon content of the gas so that it does not harm the atmosphere. This job is done by ESP, the flue gas after air-preheater comes to the ESP unit. ESP actually works on the principal of ͞CORONA DISCHARGE EFFECT͟; the ESP unit houses two electrode plates called emitting plate and collecting plate. The emitting plate is supplied with a very high DC negative potential (in order of**), this results into ionizing of air molecules surrounding the emitting plate which is called corona effect. The collecting plate is grounded and a positive potential develops on it, as a result when the flue gas pass through between them the carbon particles are attracted to the collecting plates. The collecting plates are attached to hopper where the ashes get deposited by hammering action on the collecting plate. For a 210MW unit 24 such hoppers are present in each ESP; these hoppers have mechanical transport system for proper disposal of ash. For better corona effect the emitting plate is made corrugated because this way more air molecules get ionized as corona discharge points are more in number in corrugated plate. 

 š? 2THERE ARE BASSICALLY 4 TYPES OF FANS IN A THERMAL POWER UNIT >? 
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  This fan is used to create negative pressure in the furnace, i.e. furnace pressure is lower than the atmospheric pressure, as a result of which the fire ball inside the furnace cannot come out of the furnace. ID fan also drives the flue gas through out its path and above processes and finally ejects it out of the chimney. It sucks air from inside the furnace and ejects it to the atmosphere. Mechanically ID fan consists of one 3-phase asynchronous type motor, a hydro coupling unit for coupling rotor shaft of the motor and the rotor shaft of the fan, scoop unit, a pair of journal bearings and lubrication oil system. It is the only fan which have hydro coupling because this gives more accurate control to its speed for maintaining the negative pressure more precisely since controlling of negative pressure is the most vital factor in any thermal power unit. The lube-oil system has two motors out of which one remains standby; for maintaining perfect pressure of lubrication through out the ID fan assembly. The second motor automatically starts up when the oil pressure drops below a certain level; this motor increases the oil pressure in the system. The lubrication oil is cooled by mechanical heat exchangers; this system is mounted in the lube-oil system itself. Water cools down the oil flowing in the tubes inside the coolers. There are three ID Fans in each unit of thermal power plant, named as ID-A, ID-B, ID-C.

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      - Unlike the ID fan, the FD fan is meant for creating positive pressure in the furnace and also supplies air for PA fan and secondary air for combustion. The FD fans take air from atmosphere and expel it to the plant (i.e. in the furnace, wind box etc). The outlet of the FD fan divides into 5 ways; 2 goes to the air-preheater, and remaining 3 goes to the PA fan supplying cold air. Mechanically FD fans consist of one 3-phase asynchronous type motor, a pair of journal bearings and lube-oil system. Unlike ID fan these fans have direct coupling of rotor shaft of the motor and rotor shaft of the fan. The lube-oil system is designed same as ID fans. There are 2 FD fans in a single unit.

   THE SYNCHRONIZATION OF ID-FAN AND FD-FAN IS VERY IMPORTANT AS THESE TWO FANS COMBINELY BALANCE THE PLANT. WHEN WORKING TOGETHER IT IS CALLED BALACED DRAFT.  ?    - Primary air fan is used for mixing of cold air of FD fan outlet and hot air of air-preheater outlet. The main function of this is to transport the pulverized͛ coal from the mill to the furnace via classifier. Mixing of hot and cold air is necessary because it is needed to maintain the temperature of the pulverized coal from 80϶C-90϶C for better transport of coal and better combustion in the furnace. Mechanically the construction of PA fan is same as FD fans along with the lube-oil system. There are 3 PA fans in a single mill of ball and tube type.

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   2  - The scanner air fans are relatively smaller in size and consume low power as compared to the above mentioned fans. These are simple motor operated fans that suck air from atmosphere and utilize it to cool the flame scanners (explained in C&I section later) inside the furnace. 

 

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Ê?Ê  ?Ê ? ?Ê ?? >?
    The coal handling plant comprises of track hopper, crusher house, conveyer belt system and bunker. For running of each unit at a minimum of 75% PLF requires 20,000Tons of coal per day. The huge demand coal is mitigated by B.C.C.L and E.C.L collieries, extra demand of coal is sometimes fulfilled by imported coal from Indonesia. The main transportation system is railways and trucks. The coal is directly unloaded in the track hopper, which have bottom discharging system. Coal of size up to 20mm diameter is passed on to crusher house and the rest is manually crushed up to 20mm diameter size. In the crusher house the coals are further crushed down to 5mm diameter by mechanical procedure. These crushed coals are passed through strainers to the conveyor belt system for dropping them into the bunker above the feeder through STACKERS and RECLAIMERS. After this process the coal in the CHP is handed over to the MILL.

 >? The MILL consists of FEEDER, MILL for pulverization of coal (BALL & TUBE TYPE MILL) and CLASSIFIER. The stacked coal in the bunker is dropped to the feeder automatically; the feeder is housed with a conveyor belt system with motors and pulleys. The feeder actually governs the amount of coal to be transferred to the ball & tube mill for pulverizing. The flow of coal is maintained by the speed/rpm of the conveyor belt of the feeder. The coal from the bunker drops to the feeder͛s conveyor belt at a constant rate determined by the bunker level, in this condition higher the rpm of the conveyor belt greater will be the rate of volume of the coal transferred to the mill. In the same way if the rpm is lower than lesser will be the volume of coal transferred to the mill.

 Thus the coal from the feeder is transported to the mill where the pulverization takes place. Here the ball & tube method is utilized for pulverizing of coal to 20micron diameter size. This type of mill consists of arrangement of iron alloy balls inside a tube like structure that is rotated by its auxiliaries. The coal is fed to the tube at its two ends where it is crushed to the above mentioned size, these pulverized coal is taken back from the mill to the classifier. In case of ball and tube type mills, there are 3 mill units; out of which 2 must be running and 1 for standby while the unit is running on load. The classifier consists of strainers; the primary air brings the coal from the mill to the classifier where the pulverized coal is passed through strainers. The strainers allow 80 %(approx) of the coal to pass from 200 mesh and rest is fed back to the mill for further pulverization. Here the primary air is utilized to maintain the temperature of the coal up to 80϶C-90϶C for better combustion. The classifier has 4 outlets and each ball and tube type mills have 6 such classifier (2 for each mill unit). The coal from each outlets of a classifier goes to each of the 4 corners of the furnace; therefore coal from each outlets of all the 6 classifier goes to all the 24 elevations (A-BC-D-E-F of each corner) of furnace in all. All transport of coal from mill to the furnace is done by the primary air produced by PA fans.

    BALL AND TUBE TYPE MILL IS STILL IN USE BECAUSE OF LOW MAINTAINANCE COST AND HIGHER MILL REJECTS.

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 Courtesy SIEMENS DCS SYSTEM and C&I Dept, MTPS,DVC

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  2     š?    Water comes from the water reservoir to the demineralization plant (DM Plant) for removal of all minerals present in normal water for making it non-conductive and increasing the efficiency of the overall system. After DM plant water goes to the boiler drum via condenser and the feed control station.   š? 2     
22  Water from the boiler drum comes down to the top of the boiler and forms a ring head and finally goes to the boiler through the water walls. The boiler/furnace is lit up by ͞four corner firing͟ technique; this produces a ball of fire and reaches a temperature of 1200϶C. This as a result converts the water in the water walls into steam at high pressure. This steam is sent back to the boiler drum where it is separated from the water with the help of high speed propeller. The steam is taken to the super heaters via water pipes where it is converted to superheated steam for total moisture removal. After superheaters the steam divides into two ducts called Main Steam Left (L) and Main Steam Right(R) and finally reaches the turbines. 

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       TURBINES are form of engine and hence it requires suitable fluid for working, a source of high grade energy and a sink of low grade energy, the fluid when flows through the turbine the energy content of it is continuously extracted and converted into its useful mechanical work. The turbines used in thermal power plants are of STEAM GAS type which uses the heat energy of the steam for its working. Turbine Cycle is the most vital part of the overall process; this is where the mechanical energy of the steam is converted to electrical energy via turbine assembly. The turbine assembly comprises of three turbines named as High Pressure Turbine (HPT), Intermediate Pressure Turbine (IPT) and the Low Pressure turbine (LPT). The steam that is generated in the SG section comes to the HPT through main steam lines via control valves. The steam when strikes the HPT have 540϶C at 150kg/sq.cm pressure. This high pressure

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 superheated steam rotates the turbine, the speed of the turbines is controlled by the controlling the amount of steam through control valves. Generally only 3%-4% steam is enough to rotate the turbine at 3000rpm at no load. The HPT is a single head chamber type of turbine. One part of the exhaust steam from HPT is taken to reheaters through cold reheat line (CRH line) which are again of mechanical type; for restoring the superheated properties of the steam for further use. The reheated steam is brought back to the IPT via HRH (hot reheat steam) line. And the other part of the exhaust steam is taken to the HP heaters (i.e. to HPH-6). The reheated steam͛s mechanical energy is utilized by the IPT which is a double head chamber type turbine, where steam enters from the top-mid section of the turbine and leaves the turbine from the front and back section. The exhaust of IPT is divided into 3 parts, one goes for the HP heaters (HPH-5), another goes to the deareator and the last part goes to the LPT. The exhaust steam of the LPT Is divided into 4 parts, 3 of them goes for the Low Pressure Heaters (LPH1, LPH-2, LPH-3) for heating the condensate, and the last part goes to the condenser for the steam condensation process and regeneration of water. The condensation is done to minimize the production of DM water to make the process cost effective. The steam is converted to water and extracted by CEP from the condenser and transported to Gland Sealing Coolers (GSC) via Ejectors (EJE). The GSC cools the sealing of the ducts; the condensate is taken to the LPH from the GSC for heating at lower pressure to increase the enthalpy of the water for better efficiency. Water after LPH reaches the deareator where the oxygen is removed from it and is taken to the BFPs, the BFPs increases the pressure of the water up to 160kg/sq.cm and sends it the high pressure heaters (HPH-5 & HPH-6). HPH increases the temperature of the water once more and transfers it to the Economizer, in economizer the temperature of water is again increased by the flue gas and is finally is transported to the steam generation process via the Feed Control Station.   "#$%%%&'()&*(+"+&*,,-".'/+0.1$+0.("&0&"'"."2."$03+*.'" ,,,04/3.)'$."& 40&($).4&5.0'"6, 7#0.1$.*)8"2.04/0.1$+0.(+ ,,,9




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 The 200/210 MW turbine installed in MTPS is of condensing-tandom-compound, three cylinder, horizontal, disc and diaphragm, reheat type with nozzle governing and regenerative system of feed water heating and is directly coupled with the A.C generator. TURBINE CASING: - The turbine assembly comprises of three types of casing. 1)? High Pressure Casing 2)? Intermediate Pressure Casing 3)? Low Pressure Casing OTHER TURBINE COMPONENTS: >? ROTOR: - The rotor is basically the main rotating part of the turbine which is also called the shaft and is attached with the rotor of the A.C generator via coupling. Rotor is basically divided into 3 categories and they are as follows: 1)? HIGH PRESSURE ROTOR: - This is basically made of single Cr-Mo-V steel forged with internal disc attached to T-shoot fastening designed specially for stabilizing the HPT and preventing the axial shift. 2)? INTERMEDIATE PRESSURE ROTOR: - This is made from high creep resisting Cr-Mo-V steel forging and the shrunk fit disc are machined from nickel-steel forging. This basically adjusts the frequency of the blades. 3)? LOW PRESSURE ROTOR: - This is made from the above mention alloy used in IP Rotors; blades are secured to the respective disc by riveted fork root fastening. Wires are provided in all stages of this to adjust the frequency of the blades. >? BLADES: - Blades are single most costly element fitted in the turbine. Blades fitted in the stationary part are called guide blades and those fitted in the rotor are called moving or working blades. Blades are of basically three types, they are as follows: 1)? Cylindrical ( constant profile) blade 2)? Tapered cylindrical blade 3)? Twisted and varying profile blade. >? SEALING GLANDS: - To eliminate the possibility of steam leakage to the atmosphere from the inlet and the exhaust end of the cylinder, labyrinth glands of the radial clearance type are provided which provide a trouble free frictionless sealing. >? EMERGENCY STOP VALVES AND CONTROL VALVES: - Turbine is equipped with emergency stop valves to cut off steam supply and with control valve regulate steam supply. Emergency stop valves are provided in main stream line and control valves are provided in the hot reheat line. >? COUPLING: - Since the rotor is made in small parts due to forging limitations and other technological and economic reasons, the couplings are required between any two rotors. The coupling permits angular misalignment, transmits axial thrust and ensures axial location.

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 >? BEARING: - ›
  are manufactured in two halves and usually consist of bearing body faced with anti friction tin based habiting to decrease coefficient of friction. Bearings are usually force lubricated and have provision for admission of jacking oil.   
   is normally Mitchell type and is usually combined with a journal bearing, housed in spherically machined steel shell. The bearing between HP and IP rotor is of this type. The rest is of journal type. >? BARRING GEAR: - The barring gear is mounted on the L.P rear bearing cover to mesh with spur gear L.P rotor rear coupling. The primary function of the barring gear is to rotate the rotor of the turbo generator slowly and continuously during the start-up and shut sown process when the temperature of the rotor changes. At the time of shut down the cooling of the inner parts of the turbo-generator continues for many hours. If the rotor is allowed to stand still during cooling process then it will suffer from shagging due to the temperature difference between the upper and lower portion of the turbine. It is therefore kept in barring gear for maintaining constant temperature through out the turbine. The same phenomena is observed during the start up of the turbine, because when the steam is supplied to the sealings to create vacuum, the stand still rotor will suffer from un-uniform heating and hence suffer from shagging. It is therefore kept in barring gear to avoid such damage and it prevents the breaking away of the turbine blades with sudden flow of steam into the turbine assembly. >? TURBINE LUBRICATION OIL SYSTEM: - The LUB-OIL system of turbine comprises of following category. 1)?      It is mounted on the front bearing pedestal and coupled through gear coupling to the rotor. When the turbine is running at its normal speed of 3000rpm then the oil to the governing system (at 20kg/sq.cm) and to the lubrication system (at 1kg/sq.cm) is supplied by this pump. 2)? 2     It is a multi staged centrifugal oil pump driven by A.C powered electric motor. It provides the oil requirement for starting up and stopping of the turbine. It provides oil to the governing system and to the lubrication system until the turbine is running at speed lower than 2800rpm. 3)? 2    This is a centrifugal pump driven by A.C motor. It runs for initial 10 minutes at the starting to remove air from the governing system and fill up oil to it. 4)?   
    This is a centrifugal pump driven by D.C motor. This pump is foreseen as a backup oil pump to A.C oil pumps. This pump automatically cuts in when the A.C power fails in the power station. 5)? 
:     This pump enables the complete rotor assembly to be raised up or to be floated in the bearing assembly during the start-up and shut down process of the process. Thus this prevents the damage to the bearings when the shaft is too low for hydrodynamic lubrication to take place. JOP sucks and delivers oil to the journal bearings at 120kg/sq.cm for lifting of the rotor. 6)? 
 2The oil of governing and lubrication system is cooled in the oil coolers by the circulating water. There are five such coolers,4 are for continuous operation and 1 for standby.

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? ? Ê ? ? ?    THE MENTIONED CYCLES CAN BE EXPLAINED BY THE SELF-EXPLANATORY DIAGRAMS GIVEN BELOW >?
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Courtesy SIEMENS OS220EA, C&I, MTPS, DVC

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Courtesy SIEMENS OS220EA, C&I, MTPS, DVC

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? Ê?  ? ? ELECTRICAL SYSTEM OF A THERMAL POWER PLANT BASICALLY CONSISTS OF THE FOLLOWING PARTS Õ? GENERATOR (For generation of A.C Power) Õ? SWITCHYARD (For transfer of produced power to the grid) Õ? POWER DISTRIDUTION SYSTEM (For power distribution inside the plant) >?     2. transformation of mechanical energy into electrical energy is carried out by generator. The A.C generator or alternator is based on the principal of electromagnetic induction and generally consists of a stationary part called stator and a rotating part called rotor. The stator houses the armature windings and the rotor houses the field windings. A D.C voltage is applied to the field winding in the rotor through slip rings, when the rotor is rotated, the lines of magnetic flux is cut through the stator windings. This as a result produces an induced e.m.f (electromotive force) in the stator winding which is tapped out as output. The magnitude of this output is determined by the following equation. ;!9!!