Vol.01
April 8, 2017 | Author: Ehsan Hozhabri | Category: N/A
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g GEPS Oil & Gas
Nuovo Pignone
INSTRUCTION , OPERATION AND MAINTENANCE MANUAL (MS5002D)
Volume I Description & Operation NUOVO PIGNONE JOB CUSTOMER N.P. SERIAL NUMBER SERVICE PLANT LOCATION NAME OF PLANT
MANUFACTURER
: : : : : :
:
160.5810÷16 MEHRAS G06887÷89-G06921-G06868÷70 TURBOCOMPRESSION AGHAJARI AGHAJ.GAS INJ.PLANT
GEPS Oil & Gas Nuovo Pignone
Via F. Matteucci, 2 50127 Florence - Italy Telephone (055) 423211 Telefax (055) 4232800
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INSTRUCTIONS MANUAL Status and description of the revisions
Stato di revisione
Data
Eseguito
Controllato
Approvato
Descrizione della revisione
Revision Status
Date
Prepared
Checked
Approved
Description of the revisions
00
01-04
G.D.S.
ISSUE
© 2001 Nuovo Pignone S.p.A., tutti i diritti riservati NUOVO PIGNONE PROPRIETARY INFORMATION Questo documento include informazioni confidenziali e di proprietà di Nuovo Pignone e non può essere riprodotto, copiato, o fornito a terza parte senza il preventivo consenso scritto di Nuovo Pignone. I destinatari accettano di prendere ogni ragionevole precauzione per proteggere tali informationi da uso non autorizzato o dalla loro divulgazione.
© 2001 Nuovo Pignone S.p.A., all rights reserved NUOVO PIGNONE PROPRIETARY INFORMATION This document includes proprietary and confidential information of Nuovo Pignone and may not be reproduced, copied, or furnished to third parties without the prior written consent of Nuovo Pignone. Recipient agrees to take reasonable steps to protect such information from unauthorized use or disclosure.
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Nuovo Pignone After Sales Service
Introduction to Nuovo Pignone after-sales service Nuovo Pignone organization is structured in such a way as to guarantee a comprehensive and effective after-sales service for its machinery. Here is briefly described the organization of the company, based on its experience as a manufacturer and on a continuos effort to meet customers needs. Being aware of the importance of maintenance in all operational activities, Nuovo Pignone deals with its various aspects from the design stage, through: - the use of design criteria that enhance maintainability, - the continuos research of innovative solutions to improve availability, - the selection of components and advanced technologies to enhance equipment maintenance, - the inspection procedures and topics, to be used in connection with a detailed schedule of maintenance operations, - the choice of the spare parts to be kept in stock, optimizing investment cost vs plant downtime. In late years Nuovo Pignone after-sales service has also been brought up-to-date to guarantee the best support to its customers. In more details: - worldwide, where Nuovo Pignone has been operating for tens of years, the structure consists of a service network which is the natural expansion of the "Customer Service Division" in Florence. There are localized Service Units and authorized Service Shops at strategic points of the world, to cover areas where plants with Nuovo Pignone machinery are located. - in Florence, ( Headquarters) specialized depts. which are active from the receipt of the enquiry, to the issue of the offer and, in case of an order, to the management of all activities connected with the job, up to its completion. This organization, available for all customers, ensures a qualified interface to refer to for any requirements in connection with operation/maintenance of machinery. The names and address for localized Service Units and authorized Service Shops are available at GE POWER SYSTEM WEB SITE (URL: http://www.gepower.com) selecting from its home page the following choices: Business sites/GE Nuovo Pignone/Sales Organization (complete URL: http://www.gepower.com/geoilandgas/oil_gasbrands/nuovo_pignone/sales_org.html) . In the section “Service” of this page are available the names and addresses of localized Service Units divided into geographical areas. In the above indicated web site, in the section “New Units” are available the names and addresses of the Branch Offices Abroad divided into geographical areas.
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Nuovo Pignone has been managing for many years special after sales "Support Packages". These packages typically include: - diagnostic analysis of machines in operation - consultancy in scheduling maintenance based on operational requirements - field maintenance - refurbishing of worn components - original spare parts supplies - technical expertise in updating machines Product engineering departments are staffed with experts in analysing machinery operating data, who provide users with technical consulting services aimed at optimizing use of equipment. The entire service organization guarantees users get the most suitable maintenance to restore original design conditions and the total information relevant to all technological innovations introduced in Nuovo Pignone's products as applicable to the installed machinery. Full flexibility allows us to adapt each maintenance contract upon User's needs.Service Agreements in force today, range from "On call" basis to "Global Service"
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Job: 160.5810÷16
VOLUME INDEX
The complete instructions of the gas turbine are subdivided into volumes as follows:
G.T. DESCRIPTION & OPERATION....................................................................... Vol. I
G.T. MAINTENANCE............................................................................................... Vol. II
ILLUSTRATED PARTS BREAKDOWN (GAS TURBINE)........................................................................................................ Vol. III
AUXILIARY EQUIPMENT & INSTRUMENTATION............................................. Vol. IV
BATTERY CHARGER PANEL & DC DISTRIBUTION PANEL .................................................................................... Vol. V
UNIT CONTROL PANEL (INSTRUCTION)....................................................................................................... Vol. VI REFERENCE DRAWINGS & DOCUMENTS OF THE JOB .................................................................................... Vol. VII
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Job: 160.5810÷16 INDEX
Page 1.
CONTENTS ........................................................................................................ 1-1 1.1 1.2 1.3 1.4 1.5 1.6
2.
DESCRIPTION................................................................................................... 2-1 2.1 2.2 2.3 2.4
3.
GENERAL.............................................................................................. 2-1 TURBINE BASE..................................................................................... 2-1 TURBINE SUPPORTS .......................................................................... 2-2 ACCESSORY BASE AND SUPPORTS ................................................ 2-3
COMPRESSOR SECTION ............................................................................... 3-1 3.1 3.2 3.3 3.4 3.5 3.6
4.
INTRODUCTION .................................................................................. 1-1 EQUIPMENT DATA SUMMARY......................................................... 1-3 PERFORMANCE CURVE..................................................................... 1-7 RECEIVE STAGE EQUIPMENT........................................................... 1-8 INSTALLATION.................................................................................... 1-9 TURBINE TWO SHAFT DIAGRAM................................................... 1-19
GENERAL.............................................................................................. 3-1 COMPRESSOR ROTOR ....................................................................... 3-1 COMPRESSOR STATOR...................................................................... 3-2 INLET CASING..................................................................................... 3-2 COMPRESSOR CASING...................................................................... 3-3 COMPRESSOR DISCHARGE CASING............................................... 3-3
DCOMBUSTION SECTION ............................................................................. 4-1 4.1 4.2 4.3
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GENERAL.............................................................................................. 4-1 COMBUSTION WRAPPER (SHORT) .................................................. 4-1 COMBUSTION CHAMBERS ............................................................... 4-2
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5.
TURBINE SECTION ......................................................................................... 5-1 5.1 5.2 5.3 5.4 5.5 5.6
6.
BEARINGS ......................................................................................................... 6-1 6.1 6.2 6.3
7.
ACCESSORY GEAR ASSEMBLY ....................................................... 7-1
COUPLING......................................................................................................... 8-1 8.1 8.2 8.3 8.3A 8.4 8.5
9.
GENERAL.............................................................................................. 6-1 LUBRICATION...................................................................................... 6-2 G.E BEARING PUBLICATION............................................................. 6-3
GEARS ................................................................................................................ 7-1 7.1
8.
GENERAL.............................................................................................. 5-1 TURBINE STATOR ............................................................................... 5-1 FIRST STAGE NOZZLE ........................................................................ 5-2 SECOND STAGE NOZZLE................................................................... 5-2 DIAPHRAGM ASSEMBLY................................................................... 5-3 TURBINE ROTOR AND WHEELS ....................................................... 5-3
GENERAL.............................................................................................. 8-1 CONTINUOUSLY LUBRICATED ACCESSORY GEAR COUPLING............................................................................................ 8-2 CONTINUOUSLY LUBRICATED LOAD COUPLING....................... 8-2 NON LUBRICATED LOAD COUPLING............................................. 8-2 LUBRICATION...................................................................................... 8-2 TOOTHWEAR ....................................................................................... 8-3
INLET AND EXHAUST SYSTEM.................................................................... 9-1 9.1 9.2 9.3
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GENERAL.............................................................................................. 9-1 AIR INLET ............................................................................................. 9-1 INLET COMPARTMENT...................................................................... 9-2
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9.4 9.5 9.6 9.7
10.
STARTING SYSTEM (ELECTRIC STARTING MOTOR)......................... 10-1 10.1 10.2 10.3 10.4 10.5 10.6 10.7
11.
GENERAL............................................................................................ 10-1 FUNCTIONAL DESCRIPTION .......................................................... 10-1 START-UP FUNCTIONS AND SEQUENCES................................... 10-2 TORQUE CONVERTER ASSEMBLY ................................................ 10-2 HYDRAULIC RATCHET SYSTEM..................................................... 10-3 RATCHET SYSTEM OPERATION..................................................... 10-3 STARTING JAW CLUTCH ................................................................. 10-4
GAS FUEL SYSTEM ........................................................................................ 11-1 11.1 11.2 11.3 11.4 11.5 11.6
12.
INLET DUCTING AND SILENCING................................................... 9-2 EXHAUST SYSTEM AND SILENCER................................................. 9-3 EXHAUST PLENUM............................................................................. 9-3 VENTILATION SYSTEM...................................................................... 9-3
GENERAL............................................................................................ 11-1 FUNCTIONAL DESCRIPTION .......................................................... 11-2 GAS STOP/RATIO AND CONTROL VALVE.................................... 11-3 GAS STRAINERS ................................................................................ 11-3 PROTECTIVE DEVICES ..................................................................... 11-4 OFF-BASE FUEL GAS SKID.............................................................. 11-5
LUBE OIL SYSTEM ........................................................................................ 12-1 12.1 12.2 12.3 12.4 12.5 12.6 12.7 12.8
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GENERAL............................................................................................ 12-1 FUNCTIONAL DESCRIPTION .......................................................... 12-1 LUBE OIL TANK AND PIPING ......................................................... 12-2 LUBE OIL PUMPS............................................................................... 12-3 MAIN LUBE OIL PUMP ..................................................................... 12-3 AUXILIARY LUBE OIL PUMP........................................................... 12-3 EMERGENCY LUBE OIL PUMP........................................................ 12-4 VALVES............................................................................................... 12-5
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12.9 12.10 12.11 12.12 12.13 12.14
13.
HYDRAULIC SUPPLY SYSTEM.................................................................... 13-1 13.1 13.2
14.
GENERAL............................................................................................ 14-1 FUNCTIONAL DESCRIPTION .......................................................... 14-1 SECOND STAGE NOZZLE CONTROL............................................. 14-2 INLET GUIDE VANE CONTROL ASSEMBLY ................................. 14-4
COOLING AND SEALING AIR SYSTEM .................................................... 15-1 15.1 15.2 15.3 15.4
16.
GENERAL............................................................................................ 13-1 FUNCTIONAL DESCRIPTION .......................................................... 13-1
CONTROL AND TRIP OIL SYSTEM ........................................................... 14-1 14.1 14.2 14.3 14.4
15.
LUBE OILTEMPERATURE CONTROL ............................................. 12-7 OIL FILTERS ....................................................................................... 12-8 PRESSURE AND TEMPERATURE PROTECTIVE DEVICES ........... 12-9 HYDROCARBON BASE LUBRICATING OIL RECOMMENDATIONS FOR GAS TURBINE SOM 17366/4 ......... 12-11 COOLER(S) ....................................................................................... 12-12 LUBE OIL VAPOUR SEPARATOR.................................................. 12-12
GENERAL............................................................................................ 15-1 TENTH STAGE EXTRACTION AIR................................................... 15-1 COMPRESSOR HIGH PRESSURE SEAL LEAKAGE AIR ................ 15-2 AIR EXTRACTION FOR START-UP AND SHUT-DOWN AXIAL COMPRESSOR PULSATION PROTECTION....................... 15-2
FIRE PROTECTION SYSTEM (CO2 ) ............................................................ 16-1 16.1 16.2 16.3
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GENERAL............................................................................................ 16-1 FUNCTIONAL DESCRIPTION .......................................................... 16-1 FIRE FIGHTING SYSTEM OPERATION........................................... 16-2
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17.
OPERATION .................................................................................................... 17-1 17.1 17.2 17.3 17.4 17.5 17.6 17.7
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OPERATOR RESPONSIBILITY ......................................................... 17-1 GENERAL OPERATING PRECAUTIONS ......................................... 17-1 PREPARATIONS FOR NORMAL LOAD OPERATION ................... 17-7 STANDBY POWER REQUIREMENTS .............................................. 17-8 CHECKS PRIOR TO OPERATION .................................................... 17-8 CHECKS DURING START UP AND INITIAL OPERATION ......... 17-10 ROUTINE CHECKS DURING NORMAL OPERATION................. 17-13
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CONTENTS
1.1
INTRODUCTION 1.1.2
General The Model Series 5002 two-shaft, mechanical drive gas turbine is a machine that is used to drive a centrifugal load compressor. One air inlet compartment, with ducting, is attached to the forward end of the gas turbine base. Inside the air inlet compartment, a self-cleaning inlet air filtration system attenuates the high frequency noise and an inertial air separator removes foreign particles from the air before its admission into the turbine.
1.1.3
Gas turbine The gas turbine is that part of the mechanical drive gas turbine, exclusive of control and protection devices, in which fuel and air are processed to produce shaft horsepower. The air compressor rotor has 17 stages. The gas turbine has two mechanically independent turbine wheels. The firststage or high-pressure turbine wheel drives the compressor rotor and the shaft driven accessories. The second stage or low-pressure turbine wheel drives the load compressor. The purpose of unconnected turbine wheels is to allow the two wheels to operate at different speeds to meet the varying load requirements of the centrifugal compressor. The gas turbine incorporates a four-bearing design that utilizes pressurelubricated elliptical and tilting pad journal bearings. Bearings Nos. 1 and 2 support the compressor rotor and the first-stage turbine wheel. Bearings Nos. 3 and 4 support the second-stage turbine wheel and the load shaft. The fourbearing design assures that the critical speeds of the rotating parts will be higher than the turbine operating speed range. It also permits rapid starting, loading and stopping.
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In addition, it allows close clearances between the turbine wheel buckets and the rotor bladesfor increased efficiency of the turbine component parts and higher output of the turbine. Both turbine wheels have precision-cast, long-shank buckets. This innovation effectively shields the wheel rims and bucket bases from the high temperature of the main gas stream. Air, extracted from the tenth-stage of the compressor, and leakage air from the compressor high-pressure seals cool the turbine wheels. Thermocouples monitor wheelspace temperatures. The turbine casings are split for easier disassembly. A separately fabricated outer shell contains the compressor discharge air. The MS-5002, two-shaft turbine at this site is designed to operate on fuel gas.
1.1.4
Gas Turbine Operating Principles A starting device initially accelerates the compressor/high pressure turbine to 20% speed. Atmospheric air is drawn into the compressor and sent to the combustion chambers, where fuel is delivered under pressure. A high voltage spark ignites the fuel-air mixture (once ignited, combustion will remain continuous inside the chambers). The hot gases increase the speed of the compressor/high pressure turbine rotor. This, in turn, increases the compressor discharge pressure. As the pressure begins to rise, the low-pressure turbine rotor will begin to rotate and both turbine rotors will accelerate to operating speed. The products of combustion, i.e. high pressure and high temperature gases, expand first through the high-pressure turbine, then through the low-pressure turbine and finally are exhausted to atmosphere. As the expanding gases pass through the high-pressure turbine and impinge on the turbine buckets, they cause the turbine to spin; thus rotating the compressor and applying a torque output to the driven accessories. The gases also spin the low-pressure turbine before exhausting, thus rotating the load. The rotor spins in a counterclockwise direction when viewed from the inlet end.
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EQUIPMENT DATA SUMMARY GENERAL DESIGN DATA Gas - turbine model series.............................MS-5002D Gas turbine application..................................Mechanical drive Cycle............................................................Simple Shaft rotation................................................Counterclockwise Type of operation .........................................Continuous Shaft speed...................................................5100 rpm high pressure and 4670 rpm low pressure Control.........................................................Mark VI SPEEDTRONIC solid-state electronic control system Protection (basic types).................................Overspeed, overtemperature, vibration and flame detection Cool down mechanism..................................Reduction gear with ratchet Sound attenuation.........................................Inlet and exhaust silencers to meet site requirements
COMPRESSOR SECTION Number of compressor stages.......................17 Compressor type ..........................................Axial flow, heavy duty Casing split ...................................................Horizontal flange Inlet guide vanes type....................................Variable
TURBINE SECTION Number of turbine stages ..............................2 (two - shaft) Casing split ...................................................Horizontal First-stage nozzles.........................................Fixed area Second-stage nozzles....................................Variable
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COMBUSTION SECTION Type.............................................................12 multiple combustors, reverse flow type Chamber arrangement...................................Concentrically located around the compressor Fuel nozzle....................................................Gas fuel type 1 per chamber Spark plugs ..................................................2, electrode type, spring-injected, selfretracting Flame detector..............................................4, ultra-violet type
BEARING ASSEMBLIES Quantity........................................................4 Lubrication...................................................Pressure lubricated No. 1 bearing assembly (located in inlet casing assembly) ...................Active and inactive thrust and journal, all contained in one assembly Journal..........................................................Elliptical Active thrust .................................................Tilting pad, self-equalizing Inactive thrust ...............................................Tapered land No. 2 bearing assembly (located in the compressor discharge casing)..........................................................Journal, elliptical No. 3 bearing assembly (located in the exhaust frame)........................Journal, tilting pad
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BEARING ASSEMBLIES (continued) No. 4 bearing assembly (located in the exhaust frame)........................Active and inactive thrust and journal, all contained in one assembly Journal..........................................................Tilting pad Active thrust .................................................Tilting pad, self-equalizing Inactive thrust ...............................................Tilting pad, non-equalizing
STARTING SYSTEM Starting device..............................................Electric Motor Reduction gear type......................................Freestanding with hydraulic device ratchet
FUEL SYSTEM Type.............................................................Natural gas Fuel control signal.........................................SPEEDTRONIC * turbine control panel Gas stop, ratio and control valve ...................Electrohydraulic servo control
LUBRICATION SYSTEM Lubricant ......................................................Petroleum base Total capacity...............................................23530LTS lts Bearing header pressure................................25 PSI (1,72 Bar)
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LUBRICATION SYSTEM (continued) Main lube pump............................................Shaft-driven, integral with accessory gear Auxiliary lube pump ......................................Motor-driven, vertical submerged, centrifugal sump type Emergency lube pump...................................Motor-driven, vertical, submerged, centrifugal sump type
Filter (Lube fluid) Type.............................................................Full flow/with transfer valve Quantity........................................................Dual Cartridge type...............................................12 micron filtration, inorganic fiber
HYDRAULIC SUPPLY SYSTEM Main hydraulic supply pump..........................Accessory gear-driven, variable displacement axial piston Auxiliary hydraulic supply pump ....................Motor driven, gear-rotor type Hydraulic supply filter(s) Type.............................................................Full flow Quantity........................................................Dual with transfer valve Cartridge type...............................................5 micron filtration, ....................................................................inorganic fiber
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PERFORMANCE CURVE See volume “Reference Drawings”.
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EQUIPMENT RECEIPT 1.4.1
Storage of equipment If the equipment is not to be installed immediately, it should be stored carefully, preferably in a clean, weather-tight building or enclosure.
1.4.2
Uncrating of equipment Before uncrating the equipment, it is strongly recommended that adequate protection be provided to avoid mechanical damage and atmospheric corrosion. Any damage to the equipment shall be immediately reported to the carrier and to our service representative. To uncrate the equipment, remove the crate top cover, then the front, back and side covers.
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INSTALLATION
Subject:
POSITIONING AND GROUTING OF ANCHOR BOLTS AND SUBPLATES POSITIONING OF GAS TURBINE BASES
This document describes the major operations to be carried out for positioning and grouting the subplates and anchor bolts as well as the procedures for positioning the gas turbines on their bases.
1.5.1
Positioning and grouting anchor bolts and subplates 1.5.1.1 When grouting anchor bolts separately from the main casting, leave parallelepiped pockets in the base, whose sizes must be appropriate to the size of the bolt. 1.5.1.2 The civil works building management must visibly mark level zero on the base using a leveled and walled plate. 1.5.1.3 The civil works building management must indicate the machine reference axes on the base and, perpendicularly to them, the suction filter axis and the metal cladding axis, if any (making them visible by marked or similar plates). 1.5.1.4 By accurate chipping and cleaning, dress the walls and bottom of the pockets to ensure perfect adherence between the pour and the existing base. 1.5.1.5 If no metallic template is available, lay two harmonic-steel wires (0.5-mm thick) parallel to the unit axis, keeping them stretched with counterweights. These two wires serve to align the bolts and to determine their height with respect to the zero level. 1.5.1.6 Position the anchor bolts aligning them in accordance with the design levels and anchor the sleeves (see FIGURE 1-2) to the reinforcement iron bars, which should be previously left in the pockets. 1.5.1.7 Perform casting "B" (see FIGURE 1-3). Protect the sleeve inside to prevent any cement from inserting between the bolt and the sleeve.
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1.5.1.8 Wait for the cement to shrink following the standard procedures concerning cement castings in relation to ambient temperature and humidity. If using different or accelerating cements, the civil works building management shall indicate the shrinkage times.. 1.5.1.9 Check again bolt alignment and correct the centerline values by bending the bolt if necessary or by inserting metal shims between the bolt and the sleeve. 1.5.1.10 Position the subplates laying them on the first-casting cement using screws and leveling plates screwed in the three nuts that are already present in the subplates; then, lock them with the anchor bolt (see FIGURE 1-2). 1.5.1.11 Level the subplates with a ruler and a precision level or an optical level, using point "0" of the base as reference. Fill in the form provided (see FIGURE 1-5). 1.5.1.12 After 72 hours (unless otherwise specified), accurately clean the subplates, removing any traces of cement, oxide, etc., then remove the leveling screws. 1.5.1.13 Protect the subplates with protective grease. 1.5.1.14 Using the probes, measure the clearance between the plate and the shim pack. If any clearance is found, let the base settle for some days, then check again and, if required, add shims. 1.5.1.15 Once the base has been positioned, tighten the bolt nuts to the tightening torques indicated on the drawing (usually, 28 kg/m). 1.5.1.16 Leave the base locked for 24 hours. Then, loosen the bolts and re-lock it to 8 kg/m tightening torque; at the same time, check with a magnetic comparator that the base has not sunk by more than 0.10 mm, otherwise correct with appropriate shims.
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Equipment required 1.5.2.1 1
Ruler with scraped control planes, length: 5 m, admissible tolerance: + 0.03 mm.
1.5.2.2 2
Square levels, sensitivity: 0.03 per mm per meter; length of sides: 200 - 250 mm.
1.5.2.3 Harmonic steel wire; length 50 mm, Ø 0.5 mm. 1.5.2.4 1
Outside micrometer caliper, 0 to 25 mm.
1.5.2.5 1
Steel metric measuring tape; tape length: 20 m.
1.5.2.6 2
JOHNSON blocks 20x20x50
1.5.2.7 Thickness gauges L = 200 mm
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NOTES
1.5.3
A)
Before loading the subplates with the static weight of the turbine, the cement must have appropriately set. As an indication, the minimum time required is 10 days after casting; however, specific instructions shall be provided depending on the material used.
B)
As an indication, the operations related to positioning and grouting of bolts and subplates require at least 30 days. The turbine can be let down onto the foundation 40 days after starting the bolt and subplate positioning operation.
Positioning the gas turbine base on the foundations 1.5.3.1 Preparing the foundation
1.5.4
1.5.3.1.1
Check the centerlines of the anchor bolts and write the relevant values on the appropriate forms.
1.5.3.1.2
Using a ruler and a water level, check the actual position (height) of the subplates starting from point zero. Write down the values on the appropriate forms.
1.5.3.1.3
Prepare the shim packs required to reach the level indicated on the foundation drawing (take into account the thickness of spherical washers and the differences resulting from the check described at para. 1.5.1).
Positioning the base on the foundation 1.5.4.1 After placing the turbine base over the foundation at approx. 300 mm height, insert the spherical washer and apply the shim pack onto each bolt. 1.5.4.2 Then, lower the base until it rests on the shims.
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ILLUSTRATIONS 1 TO 5 FIGURE 1-1 -
Typical drawing of foundation kit.
FIGURE 1-2 -
Positioning of anchor subplate.
FIGURE 1-3 -
Grouting with unshrinking cement from inside the sleeve up to the base "0" level.
FIGURE 1-4 -
Subplate identification with reference to foundation drawing.
FIGURE 1-5 -
Form for dimensional check of anchor bolts by diagonals.
NOTES * FIGURE 1-2
-
Do not grout the sleeve inside.
** FIGURE 1-2
-
The dashed line indicates the base casting, in the case that pockets have been made for anchor bolts and subplates.
*** FIGURE 1-2-
**** FIGURE 1-3-
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Standard-cement casting after positioning the anchor bolts. Subplate and sleeve casting, with unshrinking cement.
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Nuovo Pignone - FOUNDATION KIT -
1
- ANCHOR BOLT
2
- SLEEVE
3
- ANCHOR SUBPLATE
4
- SPHERICAL WASHER
5
- SHIM PACK
6
- BACKING PLATE FOR LIFTING SCREW
7
- TURBINE BASE
8
- WASHER
9
- KEEP PLATE
10 - LIFTING SCREW
FIGURE 1-1
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FIGURE 1-2
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FIGURE 1-3
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SURVEY OF HEIGHT BY:
RULER AND PRECISION LEVEL _____________(1) OPTICAL LEVEL__________________________(2)
SUBPLATE IDENTIFICATION WITH REFERENCE TO FOUNDATION DRAWING
A. _____________
A1. _____________
___________
B. _____________
B1. _____________
___________
C. _____________
C1. _____________
___________
D. _____________
D1. _____________
___________
E. _____________
E1. _____________
___________
F. _____________
F1.
_____________
___________
G. _____________
G1. _____________
___________
H. _____________
H1. _____________
___________
I. _____________
I1.
_____________
___________
L. _____________
L1. _____________
___________
M. _____________
M1. _____________
___________
N. _____________
N1. _____________
___________
FIGURE 1-4
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P. 1-17
g GEPS Oil & Gas
Nuovo Pignone
FORM TO BE USED FOR THE DIMENSIONAL CHECK OF ANCHOR BOLTS BY DIAGONALS NOTE:
THE ELEVATED LEVEL VALUE OF THE ANCHOR BOLTS REFERRED TO THE PLANT'S "0" POINT WILL BE PROVIDED BY THE CUSTOMER
TYPICAL DRAWING
A. _____________
A1. _____________
Y. _________
B. _____________
B1. _____________
X. _________
C. _____________
C1. _____________
D. _____________
D1. _____________
E. _____________
E1. _____________
without anchor
F. _____________
F1.
bolts
G. _____________
G1. _____________
H. _____________
H1. _____________
_____________
(Y-X)
Subplates
FIGURE 1-5
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P. 1-18
g GEPS Oil & Gas 1.6
Nuovo Pignone
TWO-SHAFT TURBINE DIAGRAM (SYMPLE CYCLE)
FIGURE 1-6 BLOCK DIAGRAM OF A SIMPLE-CYCLE, TWO-SHAFT GAS TURBINE
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P. 1-19
g GEPS Oil & Gas 2.
Nuovo Pignone
GAS TURBINE DESCRIPTION
2.1
GENERAL Component identification This section of the manual describes the various assemblies, systems and components that comprise the gas turbine. Refer to the instructions in this volume, in the Inspection and Maintenance Volume, and in the Parts Lists and Drawings Volume for detailed information on the gas turbine component parts. 2.1.1
Details about orientation Throughout this manual, reference is made to the forward and aft ends, and to the right and left sides of the gas turbine and its components. By definition, the air inlet of the gas turbine is the forward end, while the exhaust stack is the aft end. The forward and the aft ends of each component are determined in like manner with respect to its orientation within the complete unit. Standing forward and looking aft determine the right and left sides of the turbine or of a particular component.
2.2
TURBINE BASE The base that supports the gas turbine is a structural steel frame, fabricated of I-beams and plates. The base frame consists of two longitudinal wide flanged steel beams with three cross members. It forms the bed upon which the vertical supports for the turbine are mounted. There are lifting trunnions and supports, two on each base side, in line with the first two structural cross members of the base frame. Machine pads, three on each side of the base bottom, facilitate its mounting on the site foundation. Machine pads are present on the top of the frame to mount the turbine supports.
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g GEPS Oil & Gas
Nuovo Pignone
The left and right longitudinal I-beams and the forward and aft cross members of the turbine baseare fabricated along the webs. They form lube oil drain channels for the turbine bearing, load coupling and load equipment. The lube oil feed piping is contained within the longitudinal channels.
2.3
TURBINE SUPPORTS Two flexible support plates, one under the inlet casing and the other under the exhaust frame casing, support the gas turbine. These supports prevent lateral or rotational movement of the gas turbine, but allow axial movement dueto thermal expansion of the turbine during operation. The inlet support plate is bolted to the forward cross member of the turbine base. The exhaust frame support plate is bolted to the aft cross member. In order to prevent misalignment of couplings and strain on piping between the bases due to thermal expansion, two centerline supports are present under the forward and middle cross members of the turbine base. The forward support is a steel plate with a keyway that accommodates a square post in the foundation; this prevents lateral movement of the base centerline due to thermal expansion. The support at the middle cross member of the turbine base is a steel plate with a four-inch diameter hole. This plate accommodates a steel pin to prevent movement of the base in all directions. 2.3.1
Gib key and guide block The middle cross member has a gib block welded to it. This houses the gib key, which is an integral part of the lower half exhaust frame. This key is held securely in place with shims, forward and aft, that bear against the gib, yet permit vertical expansion of the exhaust frame. In this arrangement, there is a longitudinal fixed point of the turbine from which it can thermally expand forward and aft.
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g GEPS Oil & Gas 2.4
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ACCESSORY BASE AND SUPPORTS The accessory base is a structural assembly fabricated with steel I-beams and plates; it provides a mounting platform for the accessory drive gear, the starting device and other accessories. The interior of the accessory base forms a self-contained lube oil tank. The tank bottom plates are positioned at a slight angle that slopes toward two drainpipes and plugs at one base side. Lube oil heat exchangers and filters are contained inside the lube oil storage tank. Four lifting trunnions and supports are provided near each corner of the base. Machine pads or sole plates, located at the base bottom, facilitate base installation onto the site foundation: Two centerline supports, similar to those present on the turbine base, are also provided to prevent misalignment due to thermal expansion.
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g GEPS Oil & Gas 3.
Nuovo Pignone
COMPRESSOR SECTION
3.1
GENERAL The axial flow compressor section consists of the compressor rotor and casing. It includes sixteen compression stages, the variable inlet guide vanes and two exit guide vanes. In the compressor, air is confined to the space between the rotor and stator blading. Here, a series of alternate rotating (rotor) and stationary (stator) airfoil-shaped blades compress it in stages. The rotor blades supply the force needed to compress the air in each stage; the stator blades guide the air so that it may enter the following rotor stage at the proper angle. The compressed air exits through the compressor discharge casing and flows to the combustion wrapper and the combustion chambers. Air is also extracted from the compressor to cool the turbine and to seal the bearing lube oil.
3.2
COMPRESSOR ROTOR The compressor rotor is an assembly composed of sixteen wheels, a stub shaft, tie bolts and the compressor rotor blades. Each wheel and the wheel portion of the forward stub shaft have broached slots around their periphery. The rotor blades are inserted into these slots and held in axial position by spacers, which are in turn staked at each end of the slot. These blades are airfoilshaped, designed to compress the air efficiently at high blade tip velocities. The wheels and stub shafts are assembled to each other with mating rabbets for concentricity control. They are held together with tie bolts. Selective wheel positioning permits to reduce balance correction. After assembly, the rotor is dynamically balanced to a fine limit. The forward stub shaft provides the forward and aft thrust faces and the journal for the No. 1 bearing oil seals and the compressor air seal (see Fig. 3.1).
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P. 3-1
g GEPS Oil & Gas 3.3
Nuovo Pignone
COMPRESSOR STATOR The stator (casing) area of the compressor section is composed of three major sections: a.
Inlet casing
b.
Compressor casing
c.
Compressor discharge casing
These sections, in conjunction with the turbine shell, form the primary external structure of the gas turbine. They support the rotor at the bearing points and constitute the outer wall of the gas path annulus. The casing bore is maintained at close tolerances with respect to the rotor blade tips for maximum efficiency (see Fig. 3-2).
3.4
INLET CASING The inlet casing is located at the forward end of the gas turbine. Its prime function is to uniformly direct air into the compressor. The casing also supports the No. 1 bearing assembly. This bearing has a separate lower housing half, flanged and bolted to the casing lower half. Seven airfoil-shaped radial struts and seven axial tie-bars maintain the inner bell mouth in correct position to the outer one. Both the struts and tie-bars are cased in the bell mouth walls: The aft end of the inlet casing houses the variable inlet guide vanes. They permit fast, smooth acceleration of the turbine avoiding compressor surge (pulsation). Hydraulic oil is utilized to activate the inlet guide vanes through a large ring gear and multiple small pinion gears. At start-up, the vanes are set at a 44-degree position, which is the closed position. The inlet casing also transfers structural loads from the adjoining casings to the forward support. The latter is bolted and doweled to the lower half of the casing forward side.
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P. 3-2
g GEPS Oil & Gas 3.5
Nuovo Pignone
COMPRESSOR CASING The compressor casing contains the first ten compressor stator stages. The compressor casing is equipped with two large integrally cast trunnions, which serve to lift the gas turbine off its base. The first four stages of stator blades in the compressor casing are assembled in slotted semi-circular rings. The stator blade and ring assemblies are then installed in dovetail grooves machined in the wall of the compressor casing. Locking keys are installed in a groove machined on the left and right side of the horizontal joint flange of the casing upper half. They prevent these assemblies from rotating in the stator grooves and from falling down when the upper half of the casing is lifted. The fifth to tenth stator blade stages are installed in dovetail grooves machined in the wall of the compressor casing. Long locking keys are installed in grooves machined on the left and right side of the horizontal flange of the casing upper half. They prevent the stator blades from rotating in the stator grooves and from falling down when lifting the upper half of the compressor casing.
3.6
COMPRESSOR DISCHARGE CASING The compressor discharge casing is the rear portion of the compressor section. It is the longest single casing, situated at midpoint between the forward and aft turbine supports. The compressor discharge casing has the function to balance compressor surges. It builds both the inner and outer walls of the compressor diffuser and joins the compressor and turbine stators. It also supports the first-stage nozzles of the turbine. The compressor discharge casing consists of two cylinders: one is an extension of the compressor casing, while the other is an inner cylinder that surrounds the compressor rotor. They are the primary load bearing members in this portion of the gas turbine stator. Eight radial struts flare out to meet the large diameter of the turbine shell; they position the two cylinders concentrically. The inner cylinder houses the supporting structure of the No. 2 bearing. The tapered annulus between the outer cylinder and the inner cylinder of the discharge casing builds the diffuser. This converts some of the compressor exit velocity into added pressure.
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P. 3-3
g GEPS Oil & Gas
Nuovo Pignone
The compressor discharge casing contains the remaining six of the stator blade stages, i.e., stages eleven to sixteen, and the two exit bladed guide vane rows. These are composed of simple blades installed in dovetail grooves machined in the wall of the compressor discharge casing. Locking keys are installed in grooves machined in the horizontal joint flanges of the casing upper half. They prevent the blades from rotating and the stator blades from dropping out of the grooves when lifting the upper half of the discharge casing.
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P. 3-4
g GEPS Oil & Gas
Nuovo Pignone
FIG. 3.1 - VIEW OF COMPRESSOR H.P. TURBINE ROTOR ASSEMBLY
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P. 3-5
g GEPS Oil & Gas
Nuovo Pignone
FIG. 3.2 - MODEL 5002 COMPRESSOR CASING AND H.P. TURBINE ROTOR ASSEMBLY
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160.5810÷16
P. 3-6
g GEPS Oil & Gas 4.
Nuovo Pignone
COMBUSTION SECTION
4.1
GENERAL The gas turbine combustion section comprises the combustion wrapper, twelve outer combustion casings, twelve combustion cap and liner assemblies, twelve transition piece assemblies, twelve fuel nozzles, two spark plugs, two ignition transformers, four flame detectors, twelve crossfire tubes, and miscellaneous hardware and gaskets. The combustion wrapper is a welded fabrication, which surrounds the aft section of the compressor discharge casing and receives the discharge air from the axial flow compressor (see Fig. 4.1). The MS5002D gas turbines utilize combustion wrappers of different design lengths: short wrappers and long wrappers. The combustion casings are positioned externally on the short wrapper assemblies and internally on the long wrapper. One fuel nozzle, mounted on the combustion chamber cover and extending into the liner, feeds the fuel into each combustion chamber liner. Spark plugs initiate the combustion of the fuel and air mixture. . When ignition occurs in one of the two chambers, the hot combustion gases flow through the crossfire tubes to ignite the fuel-air mixture in the other chambers.
4.2
COMBUSTION WRAPPER (SHORT) The combustion wrapper supports the twelve combustion casings and encloses the twelve transition pieces. It is a welded enclosure, which receives the discharge air from the axial flow compressor and transfers it to the combustion chambers. Both upper and lower wrapper halves are assembled to the aft section of the compressor discharge casing. The aft flange of the wrapper assembly is bolted to the forward vertical flange of the turbine shell; the forward flange is bolted to the aft flange of the compressor discharge casing (see Fig. 4-2).
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P. 4-1
g GEPS Oil & Gas 4.3
Nuovo Pignone
COMBUSTION CHAMBERS All twelve combustion chambers (flow sleeves and cap and liners) are assembled inside the combustion wrapper; crossfire tubes interconnect each cap and liner. Fuel nozzles, mounted on the combustion chamber covers, extend into the chambers and provide fuel for combustion. Combustion casings are numbered from one to twelve. To identify them, it is necessary to look downstream from the turbine inlet and to count counter clockwise from a twelve o'clock position. During operation, air flows into the combustion wrapper and into the annular space between the combustion chamber' liners and flow sleeves. This high pressure air flows into the liner, where it is mixed with fuel and ignited. The resulting hot gases flow down the liner and into the transition piece, which is clamped to the first-stage nozzle assembly. Flame detectors, installed in four of the chambers, send a signal to the control system indicating that ignition has occurred (see Figs. 4.1 and 42). 4.3.1
Spark plugs Spark plugs with retracting electrodes initiate the combustion of the fuel and air mixture. Two spark plugs are installed in each of two combustion chambers, (No. 9 and No. 10). They receive power from ignition transformers. The remaining chambers are without spark plugs and are fired with flame from the fired chambers through interconnecting crossfire tubes.
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160.5810÷16
P. 4-2
g GEPS Oil & Gas 4.3.2
Nuovo Pignone
Ultraviolet flame detectors During the starting sequence, it is essential that the control system receive an indication of the presence or absence of flame.. For this reason, a flame monitoring system is used. This consists of four sensors, which are installed on four adjacent combustion chambers, and of an electronic amplifier, which is mounted in the turbine control panel. The ultraviolet flame sensor consists of a flame sensor, containing a gas -filled detector. The gas within this flame sensor detector is sensitive to the presence of ultraviolet radiation, which is emitted by a hydrocarbon flame. A DC voltage, supplied by the amplifier, is applied across the detector terminals. If flame is present, the ionization of the gas in the detector allows conduction in the circuit, which activates the electronics to give an output defining flame. Conversely, the absence of flame will generate an opposite output defining "no flame". After the establishment of flame, if voltage is re-established to the four sensors defining the loss (or lack) of flame, a signal is sent to a relay panel in the turbine electronic control circuitry where auxiliary relays in the turbine firing trip circuit, starting means circuit, etc., shut down the turbine. The FAILURE TO FIRE or LOSS OF FLAME is also indicated on the annunciator: If only one flame detector sensor senses a loss of flame, the control circuitry will cause an annunciation of this condition only. For detailed operating and maintenance information covering this equipment, refer to the Component Description following this gas turbine text.
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P. 4-3
g GEPS Oil & Gas 4.3.3
Nuovo Pignone
Fuel nozzles Each combustion chamber is equipped with a fuel nozzle that emits a metered amount of fuel into the combustion liner. Gaseous fuel is admitted directly into each chamber through metering holes located at the outer edge of the fuel nozzles tip. The liner cap imparts a swirl to the combustion air, which results in more complete combustion and essentially smoke-free operation of the unit. Detailed inspection and maintenance information on the fuel nozzles and other combustion system components is included in the Maintenance section.
4.3.4
Crossfire tubes Crossfire tubes interconnect the 12 combustion chambers. These tubes enable flame to propagate from the fired chambers, containing spark plugs, to the unfired chambers.
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P. 4-4
g GEPS Oil & Gas
Nuovo Pignone
FIG. 4-1 - AIR & GAS FLOW THROUGH COMBUSTION SECTION OF SIMPLE CYCLE GAS TURBINE
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P. 4-5
g GEPS Oil & Gas
Nuovo Pignone
FIG. 4-1a - COMBUSTION WRAPPER, COMPRESSOR DISCHARGE CASING & NO. 2 BEARING ASSEMBLY
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P. 4-6
g GEPS Oil & Gas
Nuovo Pignone
FIG. 4.2 - TYPICAL LOUVER-COOLED LINER
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160.5810÷16
P. 4-7
g GEPS Oil & Gas 5.
Nuovo Pignone
TURBINE SECTION
5.1
GENERAL In the turbine section, the high-temperature gases from the combustion section are converted into shaft horsepower. This section comprises the following components: the turbine shell, the first-stage nozzle, the first-stage turbine wheel, referred to as high-pressure turbine, the second-stage variable vane nozzle and the second-stage turbine wheel, referred to as low-pressure turbine. In addition, the section includes the diaphragm assembly, air seal and inter-stage gas path parts. All stator parts have been fabricated so that they can be split in half horizontally to facilitate maintenance.
5.2
TURBINE STATOR The turbine casing is a main structural member of the gas turbine assembly. Externally, bolts fix its forward end to the struts of the compressor discharge casing and its aft end to the exhaust frame. The turbine casing houses the following assemblies, which build the gas flow path from the combustion chamber through the turbine wheels to the exhaust frame: the first-stage nozzle partitions and shrouds, the inner and outer wall segments of the inter-stage gas path, the second-stage diaphragm and air seal, and the second-stage nozzle partitions and shrouds. The control ring, which operates the second-stage variable-angle nozzle partitions, is supported on rollers mounted on the outside wall of the turbine casing. The inner wall of the turbine casing is insulated from the hot gas path parts, except at the necessary nozzle and shroud locating surfaces. Compressor discharge air leaks past the first-stage nozzle segments into the space between the insulated wall of the turbine case and the outer wall of the inter-stage gas path; in this way, it helps carry off the heat radiated from the gas path outer wall. Eduction holes in the casing flanges mate with holes in the vertically jointed forward flange of the exhaust frame. Ambient air is induced through these holes to cool the aft end of the turbine casing and the exhaust frame struts in the exhaust path (see Fig. 5.1).
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P. 5-1
g GEPS Oil & Gas 5.3
Nuovo Pignone
FIRST-STAGE NOZZLE The first-stage nozzle assembly consists of nozzle segments assembled in a retaining ring. A clamping arrangement in the turbine casing supports the ring in the gas path. The nozzle assembly and the arrangement of its support inside the casing are designed to accommodate the effects of thermal growth due to the hot gases and to keep the assembly properly aligned in the gas path. Another unique design feature allows removal of the lower half of the nozzle assembly without removing the rotor. The nozzle-retaining ring is split into halves on the horizontal plane. Bolts hold the halves together. The nozzle segments have airfoil-shaped partitions, which are contained between an inner and outer sidewall. The nozzle partitions are hollow; bleed holes drilled through the partition wall near the trailing edge provide air to cool the nozzles. Compressor discharge air from the combustion wrapper flows around the retaining ring into the hollow nozzle partitions and cuts through the bleed holes into the exhaust gas path. This airflow cools the nozzle airfoils (see Fig. 5.2).
5.4
SECOND-STAGE NOZZLE The second-stage nozzle is composed of partitions (turning vanes), which form a variable-angle nozzle in the gas path annulus just forward of the second-stage turbine wheel. Shafts protrude through bushings in the turbine casing and turn the partitions in unison. Links connect levers, pinned at the ends of the shafts, with posts in a control ring, which is rotated by a hydraulic cylinder. The nozzle shrouds are designed to maintain proper clearances as the partitions are turned. The partition shafts are installed in the turbine casing in a way to maintain minimum clearances between the partitions and the shrouds when the turbine is at operating temperature (see Fig. 5.3).
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P. 5-2
g GEPS Oil & Gas 5.5
Nuovo Pignone
DIAPHRAGM ASSEMBLY The diaphragm is supported between the first and second stage turbine wheels by six hollow support pins, which extend radially through the turbine casing into holes, drilled in the diaphragm wall. The diaphragm assembly is a barrel-like member split in half on the horizontal plane. An air seal, installed in a groove in the diaphragm assembly, separates the two turbine stages and forms the first-stage turbine aft wheelspace and the secondstage turbine forward wheelspace. Cooling air is fed into the wheelspaces to cool the turbine wheels and to seal the gas path. The end faces of the diaphragm assembly carry the wheel seals, which prevent hot gases from flowing into the wheel spaces. The diaphragm assembly also supports the inner wall of the inter-stage gas path. A groove, machined circumferentially after the aft end of the diaphragm outer wall, retains the inner shrouds of the second-stage nozzle assembly and minimizes gas leakage around the nozzle. Cooling air reaches the second stage diaphragm through the hollow support pins and through the center bore of the first-stage wheel. It flows through holes, which are drilled at an angle through the diaphragm wall just aft of the air deflector groove and intersect the support pin holes. The source of the cooling air supply to the second-stage diaphragm is discussed in text titled "Cooling and Sealing Air Systems". The end faces of the diaphragm support thermocouples. These measure temperature in the first-stage aft wheel space and in the second-stage forward wheel space. The thermocouple leads protrude outside the turbine through one of the hollow support pins.
01-04-E MOD. INPR/SVIL/ P.F. 12/00
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P. 5-3
g GEPS Oil & Gas 5.6
Nuovo Pignone
TURBINE ROTOR AND WHEELS There are two separate turbine rotors in the gas turbine: the first-stage or high-pressure turbine rotor, which drives the axial-flow compressor and the shaft-driven accessories, and the second-stage or low-pressure turbine rotor, which drives the load (see Fig. 5.4). The two turbine rotors are located in line in the turbine section, but are mechanically independent of each other, thus allowing the two turbines to operate at different speeds. The first-stage turbine wheel is bolted directly to the compressor rotor aft stub shaft to form the high-pressure rotor assembly. The second-stage wheel is bolted to a wheel shaft to build the low-pressure/load turbine rotor. Two bearings support the load turbine rotor: the No. 3 journal, bearing located in the forward end of the exhaust frame, and the No. 4 journal and thrust bearing, assembled in a bearing housing that is bolted to the aft end of the exhaust frame. The load turbine shaft contains an overspeed bolt assembly that trips the gas turbine control system mechanically in case of overspeed. The rotor assembly is balanced previously with the overspeed bolt assembly installed in the shaft before final installation. As a result, the final balance requires a minimum of correction (see Fig. 5.5).
5.6.1
Turbine buckets The turbine buckets are assembled in the wheels in axial, pine-tree shaped dovetails. Cover plates are installed over the bucket shanks. Every second cover is a locking cover. The buckets are retained in place by a twist lock, whose head is staked in place.
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g GEPS Oil & Gas
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FIG. 5.1 - TURBINE SHELL ARRANGEMENT
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P. 5-5
g GEPS Oil & Gas
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FIG. 5.2 - FIRST STAGE NOZZLE - VERTICAL CROSS SECTION
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P. 5-6
g GEPS Oil & Gas
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FIG. 5.3 - 2ND STAGE NOZZLE CONTROL RING ASSEMBLY
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160.5810÷16
P. 5-7
g GEPS Oil & Gas
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FIG. 5.4 - VIEWS OF LOW-PRESSURE (LOAD) TURBINE ROTOR ASSEMBLY
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160.5810÷16
P. 5-8
g GEPS Oil & Gas
Nuovo Pignone
FIG. 5.5 - EXHAUST FRAME AND BEARING ARRANGEMENT
01-04-E MOD. INPR/SVIL/ P.F. 12/00
160.5810÷16
P. 5-9
g GEPS Oil & Gas 6.
Nuovo Pignone
BEARINGS
6.1
GENERAL
The gas turbine unit has four main bearings, which support the compressor and turbine rotors. The bearings are numbered 1, 2, 3 and 4. Bearing No. 1 is located in the compressor inlet casing; No. 2 in the compressor discharge casing. Bearings No. 3 and No. 4 are contained in separate bearing housings, bolted to the exhaust frame inner barrel. The Gas Turbine Arrangement drawing shows the location of these bearings. Bearing No. 1 and No. 2 support the compressor/high pressure turbine rotor, while bearings No. 3 and No. 4 support the low pressure/load turbine rotor. The table below lists the bearing types used in the different locations of the gas turbine. The instructional bulletins, referred to in the table, give detailed information on the bearings and are included in the “Equipment Publications” section under "Bearing".
Bearing No.
Kind
Type
Publication
1
Journal
Elliptical
GEI-41020C
Tilting pad (six pads) Self-equalizing Tapered land
2
Thrust (active) Thrust (inactive) Journal
Elliptical
GEI-41020C
3
Journal
Tilting-pad (five pads)
GEK-28100
4
Journal
Tilting-pad (five pads)
GEK-28100
Thrust
Tilting-pad (eight pads) self-equalizing Tilting-pad (four pads) non-equalizing
Thrust
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GEI-41018B GEI-41019B
GEI-41018B GEI-41018B
P. 6-1
g GEPS Oil & Gas 6.2
Nuovo Pignone
LUBRICATION One lube oil header supplies lube oil for pressure lubrication of all main gas turbine bearings. This header is contained inside the lube oil tank, which is fabricated in the accessory base. This connects with a second header in the turbine base. The second header runs aft inside the lube oil drain channel, which is fabricated along the web of the left Ibeam member on the turbine base. Thus, the oil feed piping is completely enclosed, and the system, in effect, is double piped. Branch oil feed and drain piping connect the header and drain channel to each bearing housing, which contains the journal and thrust bearing components. Oil seals and deflectors help direct the flow of lube oil from the bearings into the bearing drains, and thence return it to the lube oil tank. The oil seals are labyrinth packings, installed in the bearing housings outboard from the journal or thrust bearing assemblies, where control of oil seepage along the rotor shaft is required. The oil seals are installed in the bearing housings in a way to leave only a small clearance between the packing teeth and the rotor shaft. The oil seals are designed with double rows of teeth with an annular space between them. Pressured sealing air is fed into this annular space to restrain the lube oil from seeping out of the bearing housing and spreading along the rotor shaft. Some of this sealing air returns with the oil to the lube oil tank and is vented to atmosphere through the lube oil tank vent. All lube oil to the bearings is filtered and supplied at a controlled temperature and pressure. Flow sights and thermocouples are installed in the drain piping from each bearing. The flow sights provide a visual check of the oil flow through the bearings. The thermocouples provide for indication of oil temperature on the temperature indicator in the turbine control panel. The lube oil system is shown on the Schematic Piping Diagram in the “Reference Drawings” volume.
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P. 6-2
g GEPS Oil & Gas 6.3
Nuovo Pignone
G.E. BEARING PUBLICATIONS GEI-41018B GEI-41019B GEI-41020C GEK-28100
01-04-E MOD. INPR/SVIL/ P.F. 12/00
160.5810÷16
P. 6-3
g GEPS Oil & Gas 7.
Nuovo Pignone
GEARS
7.1
ACCESSORY GEAR ASSEMBLY The accessory gear assembly is a gearbox coupled directly with the turbine rotor. It serves to drive the turbine-driven accessory devices. The accessory gear is located on the accessory base. It contains the gear trains necessary to provide gear reductions to drive the accessory devices at the required speeds. One overspeed tripping mechanism for the high-pressure turbine is mounted on the exterior of the casing. This device mechanically dumps the oil from the trip circuit and shuts down the gas turbine unit when the speed of the first-stage turbine exceeds the limit prescribed (by G.E.) in the Control Specifications. The overspeed bolt, which actuates the trip upon overspeed, is installed in the main shaft. The accessories, driven by the accessory gear assembly, include the main hydraulic supply pump and the main lube oil pump. During startup, the accessory gear transmits torque from the starting motor gas expander turbine to the gas turbine. The accessory gear is lubricated from the pressurized bearing header supply and is drained by gravity to the lube oil reservoir. The gear casing is split, at the horizontal plane, into an upper and a lower section for maintenance and inspection purposes. Interconnected shafts are arranged in a parallel axis in the lower casing: except for the lube oil pump shaft, all centerlines are located on the horizontal joint of the casing (see Fig. 7-1-2). The starting clutch assembly is located at the outboard (forward) end of the main accessory gear shaft. It is positioned on the horizontal joint of the casing and connects the starting motor with the gas turbine rotor. The clutch is automatically disengaged when the expansion turbine is shut off and the gas turbine has reached self-sustaining speed. Additional descriptive information on the clutch is presented in this section under “Starting System”.
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The main lubricating oil pump is located on the inboard wall of the lower casing half. A splined quill shaft connected with the lower drive gear drives it. The pump consists of steel gears, which run in a shaped cavity in the wall of the accessory drive gear casing. The pump suction and discharge passages are cored on the bottom surface of the casing. The pump gears are contained in babbitt-lined cast-iron bushings, which are located at the ends of the pump cavity. For more detailed information, see the “Auxiliary Equipment” volume.
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FIG. 7-1 - CUTAWAY VIEW OF ACCESSORY DRIVE GEAR WITH NO. 4 SHAFT AND MAIN LUBE PUMP SHOWN
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FIG. 7-2 - CUTAWAY VIEW OF ACCESSORY DRIVE GEAR SHOWING NO. 1 SHAFT (WITH CLUTCH)
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COUPLING
8.1
GENERAL The basic functions of the flexible gear-type couplings used on this turbine are to:
(a)
connect two rotating shafts in order to transmit torque from one to the other,
(b)
compensate for all three types of misalignment (parallel, angular and a combination of both),
(c)
compensate for any axial movement of the shafts so that neither exerts an excessive thrust on the other.
Parallel misalignment occurs, when the two connected shafts are parallel, but not in the same straight line. Angular misalignment occurs, when two shafts are in the same straight line but their centerlines are not parallel. Combined misalignment occurs, when the shafts are neither parallel nor in the same straight line. Axial movement is when one or both shafts are displaced along their axis (centerline). The couplings used on this turbine are two: (a)
one connects the accessory drive gear with the turbine shaft,
and (b)
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the other connects the turbine shaft with the load equipment.
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CONTINUOSLY LUBRICATED ACCESSORY GEAR COUPLING The coupling is a continuously lubricated flexible gear-type device. It employs a hub with male teeth fitted at each end of a distance piece. The teeth mesh with the female ones of a sleeve at each end to transmit torque. The male teeth are crowned and can slide fore and aft within the female spline. This allows for all three types of misalignment. The sleeve at the accessory gear end is bolted to a flange (hub), which has been shrinkfitted and keyed to the accessory gear shaft. The sleeve at the turbine end is bolted directly to the turbine rotor.
8.3
CONTINUOUSLY LUBRICATED LOAD COUPLING The design of this coupling is similar to that of the coupling that connects the accessory gear with the turbine rotor, except that its male teeth are machined into the distance piece and the sleeves are bolted directly to the turbine and shaft flanges of the load equipment.
8.3A NON-LUBRICATED LOAD COUPLING (IN ALTERNATIVE TO CONTINUOUSLY LUBRICATED LOAD COUPLING) The non-lubricated coupling consists of flexible diaphragms, adapter shafts and a center shaft. The adapter shaft, assembled to the ends of the center shaft, includes flanges, which interface with the load compressor and the load turbine rotor shafts, and also provide support for the flexible diaphragms. The diaphragm sections provide the flexibility needed to compensate for the nominal misalignment between the load equipment and the load turbine rotor, and permit axial movement of the turbine in relation to the load equipment.
8.4
LUBRICATION Whenever gear-type flexible couplings are used, lubrication is a major contributor to their long life. In the continuous-lubrication coupling, lube oil is discharged from the turbine bearing header into the coupling teeth through nozzles. The oil is then caught by the coupling guards and returned to the lube oil tank in the turbine base.
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Couplings with one-half micron filters can be disassembled, cleaned and inspected. If the filter cartridges are not changed at regular intervals, deposits can build up on the coupling teeth and limit the action of the coupling. This condition is the result of particles being centrifuged out of the oil and onto the coupling teeth.
8.5
TOOTH WEAR During the initial operation of gear-type couplings, minor imperfections will be smoothed out and the working surfaces will take on a polished appearance. Under continued normal conditions of operation, the rate of wear will be small.
The pattern of tooth wear can provide maintenance information calling for action. An abnormally wide wear pattern in the axial direction is indicative of excessive running misalignment. The greater the misalignment, the greater the wear rate, since the number of teeth in contact decreases with increasing angularity.
Abrasive wear, characterized by short scratch-like lines or marks on the surface of the teeth, indicates that the lube system is not clean and oil is carrying particles into the coupling teeth.
Corrosive wear is indicative of lubricant contamination or highly active additives. Surface fatigue, characterized by the removal of metal and the formation of cavities, may indicate torsional oscillations in the coupled system.
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INLET AND EXHAUST SYSTEM
9.1
GENERAL Gas turbine performance and reliability is a function of the quality and cleanliness of the inlet air entering the turbine. Therefore, for most efficient operation, it is necessary to treat the atmospheric air entering the turbine and remove contaminants. The air inlet system, fitted with specially designed equipment and ducting, has the function to modify the quality of the air and make it more suitable for use in the unit. This must be done under various temperature, humidity and contamination conditions. Hot exhaust gases produced as a result of combustion in the turbine are ducted through the exhaust system before being released to the atmosphere. The exhaust flow must meet certain environmental standards of cleanliness and acoustic levels depending on site location.
9.2
AIR INLET The air inlet system consists of an elevated air inlet compartment and inlet ducting with silencing equipment; the compartment and ducting are connected to the turbine inlet plenum This system combines the functions of filtering and silencing the inlet air with the function of directing the air into the turbine compressor. Inlet air enters the inlet compartment and flows to the inlet plenum and then into the turbine compressor through the parallel overhead ducting, with built-in acoustic silencers and trash screen. The elevated ducting arrangement provides a compact system and minimizes pickup of dust near the ground level All the external and internal surface areas exposed to the airflow are coated with a protective corrosion preventive primer.
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INLET COMPARTMENT The inlet compartment, which is an all-weather enclosure, is located off-base and connected to the inlet ducting. This compartment contains a first stage self-cleaning filtration unit and a second high-efficiency type filter. The self-cleaning filter system contains highefficiency media filter cartridges that are cleaned sequentially by pulses of pressurized air during turbine operation. The gas turbine compressor supplies discharge air to the selfcleaning inlet filters for use as pulse air during the cleaning cycle. The filtration unit is required to provide adequate protection for the turbine unit from the environmental conditions existing at the turbine site. Proper filtration maintenance is required to ensure that this protection is maintained.
9.4
INLET DUCTING The air inlet ductwork connects the inlet compartment to the inlet plenum. It includes the acoustically treated plenum at the gas turbine compressor inlet, a 90-degree elbow, a silencer module and sections of inlet ducting. Silencing is provided by the use of vertical baffles; the baffles are made of acoustically perforated sheets of encapsulated low-density insulating material. In addition, the interior wall of the ducting and the plenum chamber are lined with the same type of treatment. The vertical parallel baffle design is specifically tuned to eliminate the fundamental compressor tones and to attenuate the noise of other frequencies. The perforated sheet used in the silencers and line ductwork is made of steel and requires no maintenance. The inlet support structure is made of galvanized carbon steel with multiple coats of protective paint.
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EXHAUST SYSTEM
9.5.1
General In the exhaust section the gases, which have been used to power the turbine wheels, are redirected and released to atmosphere. One component of the system is the exhaust plenum, to which an expansion joint and transition duct are vertically mounted, extending from the side of the turbine base. A silencing section is installed between the transition duct and the exhaust duct system.
9.6
EXHAUST PLENUM The exhaust plenum is a rectangular box-like structure that takes the turbine exhaust gases; these gases are then ducted to the silencers and then vented to atmosphere. It is located at the aft end of the turbine base and encloses the exhaust frame, diffuser and turbine vanes. A wrapper covers the top and side and serves to enlarge the plenum volume; it then forces the exhaust gases out of the side opening into the transition duct. Insulation in the plenum fabrication provides thermal and acoustical protection.
9.7
VENTILATION SYSTEM 9.7.1
General The accessory and turbine compartments are equipped with a ventilation system. Both compartments are fitted with thermally insulated side panels and roofs.
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The accessory and turbine compartments are pressurized and cooled by ventilation fans (88BA-1, 2) installed in the pressurized and cooled ventilation ducting after the inlet filter compartment. The ventilation system consists of two separate fans driven by their respective motors; one fan provides ventilating air during normal turbine operation. The other operates as a stand-by fan and starts when, for any reason, the temperature inside the turbine compartment increases and reaches the set point of the RTD (TT-BA-1÷3) switch (26BA). These are mounted on the turbine compartment (TT-BA-2), accessory compartment (TT-BA-1) and coupling compartment (TT-BA-3). The ventilating air exits from the turbine and coupling compartments through the upper opening of each compartment. Two types of dampers are foreseen for the safety of the ventilation system:
9.7.2
a)
gravity dampers, positioned in the filter chamber, held open by the fans of the ventilation system;
b)
manual dampers, positioned on the inlet/outlet ducts of the ventilation system; they are closed automatically by the fire fighting system, by the pressure of the CO2 discharge.
Gas Detection System Four gas detectors are provided on the Gas Turbine. These are located inside the accessory compartment, turbine compartment and coupling compartment. Two set points are provided on each gas detector (set on the control of each gas detector, located on the UCP), one for 30% LEL (alarm indication on Mark V or Mark VI CRT ) and one for 60% of LEL (trip executed by Mark V or Mark VI panel).
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STARTING SYSTEM (ELECTRIC STARTING MOTOR)
10.1 GENERAL Before the gas turbine can be fired and started, it must be rotated or cranked by accessory equipment. An electric induction motor, operating through a torque converter, provides the cranking torque and speed required to start up the turbine. The starting system components also permit slow-speed rotation of the turbine for cooling-down purposes after shutdown. The components of the electric motor starting system include: an induction motor, a torque converter with ratcheting mechanism, a starting jaw clutch and a hydraulic ratchet system. In addition, several supplementary components are required for sequencing and operating the turbine starting system. These are detailed in the following system functional description.
10.2 FUNCTIONAL DESCRIPTION During the starting sequence, the electric starting motor, the torque converter, the output gear and the starting clutch drive the gas turbine through the accessory gear. The starting clutch assembly and the clutch engaging cylinders are mounted on the accessory gear assembly. A flexible coupling permanently couples the accessory gear with the turbine compressor shaft. The torque converter transmits the electric motor output torque to the gas turbine accessory gear through a reversing gear. The torque converter input shaft drives the charge pump, which supplies turbine lube oil to the torque converter. Initially, the charge pump receives oil for the torque converter charge pump from the lube oil header. The charge pump, after building up the lube oil operating pressure, draws the oil from the turbine lube oil tank through a filter. A spring-loaded check valve, installed in the discharge line of the lube oil header, maintains a positive oil pressure on the charge pump during operation. Oil returns to the turbine lube oil tank through drains.
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10.3 STARTUP FUNCTIONS AND SEQUENCES The starting system provides both cranking and turning power during the gas turbine startup and shutdown cycles. In the starting cycle, the starting equipment accomplishes three primary functions: it sets the gas turbine rolling (breakaway from standstill); it accelerates the gas turbine to firing speed; finally, it further accelerates it to self -sustaining speed (a speed at which the gas turbine develops net positive power output). When the electric starting motor is energized, its output torque starts from zero and increases as the torque converter is filled with oil by the charge pump. The torque converter output is directly proportional to the difference between input and output speeds (maximum slip). The torque converter and reversing gear speed ratios were picked to crank the gas turbine at firing speed. When pressurized, the converter demands power from the motor and supplies power to the gas turbine through the starting clutch. The ratchet system may supplement the breakaway torque. The self-sustaining ratchet device, mounted on the reversing gear, starts when it receives pressure oil from the hydraulic self-sequencing control valve module. This oil at higher pressure flows from the hydraulic ratchet pump through a filter to the self-sequencing module.
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10.4 TORQUE CONVERTER ASSEMBLY This assembly includes the torque converter, the hydraulic ratchet mechanism and an output gear unit. Pressurized oil from the converter loop lubricates the gear unit and the clutch in the ratchet mechanism. Drain oil from the assembly returns to the lube oil reservoir by gravity. The converter loop drains during shutdown to unload the converter for engine startup. The torque converter consists of a driven pump rotor that supplies oil to a hydraulic turbine connected with the input shaft of the output gear. The pump rotor requires rated motor horsepower at rated speed, independent of the output load. The power absorption of the pump rotor varies as the cube of the input speed. The hydraulic ratchet mechanism is a rack-pinion rotary actuator connected with the input shaft of the output gear through a roller-ramp type one-way clutch. The output gear unit connects the ratchet mechanism and the output side of the torque converter with the starting clutch.
10.5 HYDRAULIC RATCHET SYSTEM The components of the ratchet system include: a rotary actuator/one-way clutch mechanism in the torque converter assembly; a control valve module; a pump assembly; a relief valve and filters. In the system, the valve module controls the starting clutch engagement and the hydraulic self-sequencing operation of the rotary actuator. The module includes one ON/OFF solenoid valve, one modulating backpressure valve that maintains adequate pressure to the clutch engaging cylinders, two pilot operated valves that control the flow to the rotary actuator, and one limit switch. The hydraulic ratchet pump assembly is made up of a D.C. motor, driving the pump. This assembly pumps lube oil from the unit bearing header to the inlets of the relief valve and to the control valve module.
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10.6 RATCHET SYSTEM OPERATION With the pump in operation and solenoid valve energized, oil from the lubrication system reaches the starting clutch. This causes the ratchet mechanism to operate continuously as the hydraulic self-sequencing control automatically shifts the oil flow between forward and reset strokes of the ratchet mechanism. The electronic control panel automatically sequences the unit cooling down process. Once every three minutes, the ratchet mechanism is operated through one complete cycle. The cycle terminates in the forward stroke position to lock the clutch in engaged position. The action of the ratchet system normally serves to achieve breakaway of the unit rotor system during the unit startup sequence. With the starting system at maximum power, the D.C. motor and the solenoid valve are energized for continuous operation until breakaway is achieved. If breakaway is not achieved within three minutes, the ratchet system is de-energized.
10.7 STARTING JAW CLUTCH A starting clutch connects the output shaft of the torque converter assembly to the main shaft of the accessory gear. Hydraulic cylinders engage the clutch (oil supplied by the ratchet control valve module); return springs in the cylinders disengage it. A torque generated in the torque converter and/or ratchet mechanism maintains the clutch engaged. Because of the one-way clutch in the ratchet mechanism, it is not possible to turn the sliding clutch hub backwards except during a reset stroke of the ratchet mechanism. The system is designed to maintain the clutch engaged at all times, except when the gas turbine is running. A starting clutch solenoid valve actuates two parallel, horizontally oriented hydraulic cylinders. These move the sliding clutch into engagement with the stationary clutch hub. When the gas turbine reaches a predetermined speed, the solenoid valve is de-energized by the 33HR-1 speed relay and dumps the hydraulic oil to drain.
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FUEL GAS SYSTEM
11.1 GENERAL The fuel gas system is designed to deliver fuel gas to the turbine combustion chambers at the proper pressure and flow rates in order to meet all starting, acceleration and loading requirements for gas turbine operation. The major component of a fuel gas system is the gas stop/ratio and control valve assembly, located in the accessory area. Associated with this gas valve are a vent valve, control servo valves, pressure gauges and the distribution piping to the combustion fuel nozzles. See the schematic piping diagram.
The fuel gas system comprises the following major components:
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a.
Fuel gas strainer.
b.
Gas stop ratio valve and control valve (SRV-1, GCV-1).
c.
Fuel gas low pressure alarm switch (63FG-1).
d.
Pressure gauges.
e.
Fuel gas vent valve (20VG-1).
f.
Fuel gas trip valve (VH5-1).
g.
Stop ratio valve-control servo valve (90SR).
h.
Gas control valve-control servo valve (65GC).
i.
Gas valve control LVDTs (96GC-1/2).
j.
Pressure transmitters (96FG-2A/B/C).
k.
Stop - Ratio/valve L.V.D.T. (96SR-1/2)
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11.2 FUNCTIONAL DESCRIPTION A strainer cleans fuel gas as it comes from the supply piping before flowing through the gas valve and into the gas manifold piping. The gas valve (gas stop ratio and control valve) meters and controls fuel gas to provide the required flow of gas to the turbine combustion system. The fuel gas stop ratio and control valve consists of two independent valves (one stop ratio valve and one control valve) assembled together in one housing. Both the gas stop ratio valve and the gas control valve are single-action, electro hydraulically operated valves. A SPEEDTRONIC control signal activates the fuel gas control valve to admit the proper amount of fuel required by the turbine for a given load or speed. The fuel gas stop ratio valve shuts off the flow of fuel to the turbine whenever required. It also controls pressure ahead of the fuel gas control valve. This enables the gas control valve to control fuel flow over the wide range required under various turbine starting and operating conditions.
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11.3 GAS STOP/RATIO AND CONTROL VALVE (SRV-GCV) The gas control valve (GCV-1) part of the gas/stop ratio and control valve provides a fuel gas metering function to the turbine in accordance with its speed and load requirements. The position of the gas control valve (hence fuel gas flow to the turbine) is a linear function of a fuel stroke reference voltage (FSR) generated by the SPEEDTRONIC control system. The control voltage generated either shifts the electro hydraulic servo valve to admit oil or to release it from the hydraulic cylinder. This will position the gas control valve in a way to supply the fuel gas required for a given turbine speed and load situation. The gas stop ratio valve(SRV-1) is similar to the gas control valve. Its plug, however, has a steeper taper in order to provide the high gain necessary to maintain good pressure control. The ratio function of the stop ratio valve provides a regulated inlet pressure for the control valve as a function of turbine speed. The SPEEDTRONIC pressure control loop generates a position signal that positions the stop ratio valve by means of a servo valve-controlled hydraulic cylinder. This provides the required intervalve pressure. In the fuel gas system, the gas stop ratio valve provides a positive fuel shutoff when required by either normal or emergency conditions. Trip oil pressure acts on the piston end of a spool and activates a fuel gas trip valve. When the trip oil pressure is normal, the fuel gas trip valve maintains a position that allows hydraulic oil to flow between the control servo valve and the hydraulic cylinder. In this position, normal control of the stop ratio valve is allowed. If the trip oil pressure should drop below a predetermined limit, a spring in the trip valve shifts the spool to interrupt the flow path of oil between the control servo valve and the hydraulic cylinder. Hydraulic oil is dumped and the stop ratio valve closes, shutting off the flow of fuel gas to the turbine.
11.4 GAS STRAINERS Parallel gas strainer units are installed upstream of the turbine base fuel inlet connection point to facilitate on-site maintenance requirements. Connection of the fuel gas supply is made at the purchaser’s connection in the supply line ahead of the gas strainers. These remove foreign particles that may be in the incoming fuel gas. A blow-down connection on the bottom of each strainer body serves for periodic cleaning of the strainer screen. Cleaning frequency depends on the quality of the fuel gas used. The strainer should be cleaned shortly after full turbine load has been attained for the first time and after any disassembly of the purchaser’s fuel gas line.
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11.5 PROTECTION DEVICES
11.5.1
Fuel Gas Vent Valve (20 VG-1) A solenoid-operated valve 20VG-1 is installed in the vent piping on the casing of the combination gas stop/speed ratio and gas control valve. When the turbine is shut down, any fuel gas that might accumulate in the compartment between the stop/speed ratio and control valve vents to atmosphere through the piping.
11.5.2
Low Fuel Gas Pressure Switch (63FG-1) A low fuel gas alarm pressure switch 63FG-1, installed in the gas piping ahead of the gas stop/speed ratio and control valve assembly, provides alarm protection should the gas pressure drop below the switch setting. The annunciator panel in the control center will display an alarm..
11.5.3
Pressure Transmitter (96FG) Pressure transmitters, 96FG-2A/B/C, are installed in the fuel system on the fuel gas discharge side of the stop/speed ratio valve, to provide the operational pressure signal to the SPEEDTRONIC control system.
11.5.4
Pressure Gauges Three pressure gauges are provided in the fuel gas piping. The upstream gauge measures the pressure of fuel gas entering the stop/speed ratio valve; the intermediate gauge measures the pressure as it leaves the valve. Finally, the downstream gauge measures pressure of the gas leaving the gas control valve and flowing to the gas manifold.
11.6 OFF-BASE FUEL GAS SKID The combustion gas must reach the turbine free from impurities, in predetermined quantity and at preset pressure, therefore a control console is needed to separate condensate and eliminate solid parts.
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The control skid for processing the combustion gas is composed mainly of a calibrated orifice, a condensate separator, two filters, valves and various monitoring and protecting devices. Gas enters the skid through a calibrated orifice that regulates its quantity and permits to increase its pressure. From the calibrated orifice, the gas flows through the condensate separator, provided with an automatic discharge and safety valve, and through filters that separate solid particles, also provided with relief valves. Finally, the gas reaches the combustion gas system on the turbine base plate. For ratings of the calibrated orifice, the condensate separator, filters, the ranges of set point values for the different equipment and instruments, please refer to the INSTRUMENT LIST. For additional information about the gas control console, please refer to VOLUME “Auxiliary Equipment”.
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LUBE OIL SYSTEM
12.1 GENERAL The gas turbine is lubricated by a closed loop, forced feed oil system. This system includes an oil tank, pumps, heat exchangers (oil coolers), filters and valves; in addition, miscellaneous devices control and protect the system. Lube oil circulates through the four main turbine bearings, the turbine accessories and the driven load equipment. Moreover, the lube oil system supplies oil to the hydraulic supply system, the control oil system, and the starting system. The lubrication system is designed to provide an ample supply of filtered lubricant at the proper temperature and pressure for operation of the turbine and its associated equipment. The nominal capacities and ratings of the pumps, the estimated oil flow to the various components and the approximate rating sizes, or setting of the various orifices and control devices are shown on the Device Summary and the Schematic Piping Diagram, in volume "Reference Drawings". Refer to HYDROCARBON BASE LUBRICATING OIL RECOMMENDATIONS FOR GAS TURBINES, SOM 17366/4, (see para. 12.12).
12.2 FUNCTIONAL DESCRIPTION The system is a closed loop, forced feed system. Pumps draw lube oil from the oil tank and force it under pressure through the heat exchangers, oil filters and the bearing header to the bearings. Pressure, regulated at “24.5 PSI” for the bearing header, is discharged from the pumps. Protection devices are incorporated into lube systems, where necessary to protect the equipment against low lubricant supply, low lubricant pressure and high lubricant temperature. The protective devices sound an alarm or shut the unit down if any of the above conditions occur.
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12.3 LUBE OIL TANK AND PIPING The lube oil tank is fabricated as an integral part of the accessory base, in the area under the accessory section. Installed in the tank and mounted on its cover are the lube oil pumps, lube oil filters and the various control and protective devices. A manhole with a bolted-on cover provides access to the tank interior. An oil tank fill connection is provided on either side, near the tank bottom. Welded fabrications of seamless, stainless steel pipe compose most of the lube oil piping. Gaskets prevent leakage at the bolted flanges of this piping. Whenever possible, the lube oil feed piping is contained within the oil tank or drain headers. A pipe, connected to a flanged opening in the drain channel near the aft end of the base, provides a vent to atmosphere for the complete lube oil system. All lubricant pumped by the main or aux. lube oil pump to the lube oil header flows through a water cooler or to an oil/air cooler to remove excess heat and then through a cartridge type filter providing 12-micron absolute filtration. The lubricant pumped by the emergency pump bypasses the cooler.
12.3.1
Drains The drain points of the lube oil system are shown on the Schematic Piping Diagram, and the Purchaser’s Connection Outline and Notes, contained in the “Reference Drawings” Volume.
12.3.2
Flow sights Flow sights are present in the bearing and coupling drains to allow visual check of the oil flow. Check the oil flow when the lube oil pumps are started prior to every turbine startup.
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12.4 LUBE OIL PUMPS The lube oil system utilizes three lube oil pumps: the main pump, which is driven by the accessory gear, the auxiliary pump, driven by a vertical A.C. motor, and the emergency pump, driven by a vertical D.C. motor. Both the auxiliary and emergency pumps are mounted on the oil tank cover. The output of each one of the pumps at rated speed, together with the motor ratings, are included in the Device Summary of this manual. Functional information concerning the pumps is included in the following paragraphs.
12.5 MAIN LUBE OIL PUMP (ACCESSORY GEAR DRIVEN) The main lube oil pump is a positive displacement pump, located on the base of the accessory gear; it is driven by a splined quill shaft connected with the lower drive gear. One backpressure valve VPR-1 limits the output of this pump to the lube oil system . The pressure setting of VPR-1 is given on the Device Summary. Further information on the pump is included in the Gas Turbine Auxiliary Equipment volumes.
12.6 AUXILIARY LUBE OIL PUMP (AC MOTOR DRIVEN) The auxiliary centrifugal lube pump provides pressure during the starting and stopping sequences of the gas turbine, when the main pump cannot supply sufficient pressure for safe operation. Low lube oil pressure switch 63QA-1 or lube oil pressure transmitter 96QA-1 control the auxiliary lube oil pump. This pressure switch or pressure transmitter also signal alarm conditions in addition to the start function. Start signals from this transmitter cause the auxiliary lube oil pump to run under low lube oil pressure conditions as happens during startup or shutdown of the gas turbine. At this time, the main pump, driven by the accessory gear, does not supply sufficient pressure. During the turbine starting sequence, the auxiliary lube oil pump starts on receiving the start signal. The control circuit is operated through the normally closed contacts of the 63QA-1 pressure switch or the 96QA-1 pressure transmitter.
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The pump will run until the turbine reaches operating speed, even though the lube oil header is at rated pressure and the pressure transmitter contacts have opened. If operating speed is reached and proper lube oil pressure is not established in the system, the pump will continue to run (through the contacts of the complete sequence check relay). When the turbine shutdown sequence is on and the control system timer is on as well, pressure switch 63QA-1 or 63QA-2 or pressure transmitter 96QA-1 will signal the auxiliary pump to start running. This happens when the lube oil header pressure falls to the point at which the contacts of the switch or of the transmitter are set to close. The pump will continue to run (if A.C. power is available) throughout the cool down period, during which time the control system timer will be in charge of operation. This sequence of operations is described in the specific turbine mechanical drive operating instructions included in the “Operation” section of this manual.
12.7 EMERGENCY LUBE OIL PUMP (DC MOTOR DRIVEN) The emergency centrifugal lube oil pump intervenes to supply lube oil to the main bearing header during an emergency shutdown, in the event that the auxiliary pump has been forced out of service or is unable to maintain adequate lube oil pressure. The emergency pump is used only during turbine shutdown, since the pump size and the drive motor are incapable of supplying adequate lube oil for normal turbine operation. This pump is started automatically by the action of pressure switches 63QT-1/2 or of pressure transmitter 96QT-1A, whenever the lube oil pressure in the main bearing header falls below the pressure switch setting. If the main or auxiliary lube oil pumps should resume operation, the emergency pump will be stopped (automatically) by pressure transmitter 96QA-1, when the lube oil header pressure exceeds the setting of the switch. Should the auxiliary pump fail during the shutdown sequence because of an A.C. power failure or any other cause, the emergency lube oil pump will be started automatically by action of the low lube oil pressure switches 63QT-1/2 or of the pressure transmitter 96QA-1. The emergency lube oil pump will continue to run until the high-pressure shaft comes to rest. The emergency pump will then be controlled by the control system timer and operated through a cool down period.
01-04-E MOD. INPR/SVIL/ P.F. 12/00
160.5810÷16
P. 12-4
g GEPS Oil & Gas
Nuovo Pignone
The emergency pump can be tested for correct start, independent of the relating control pressure switches, while the lube oil system is operating normally on the main or auxiliary pump.
12.7.1
Cool down Period On units with automatic control, the control circuits are arranged so that the A.C. auxiliary lube oil pump will automatically continue operation after turbine shutdown for a ten-hour cool down period. If A.C. power is not available after shutdown, the D.C. emergency lube oil pump will operate automatically, cycling 30 seconds on and 3 minutes off, until a time of 100 minutes on has been accumulated (total cycle time of ten hours).
12.8 VALVES This system uses various types of valves that regulate pressure and control the flow of lube oil. Please refer to the “Device Summary- Reference Drawings” section, which reports the valve symbols, settings and descriptions.
12.8.1
Check valves Check valves are present in the discharge piping from each of the lube oil pumps. They are also installed in the discharge piping of auxiliary and emergency pumps to prevent lube oil from being circulated back to the oil tank through the standby centrifugal pump The check valve mounted in the discharge piping of the main shaft-driven gear pump prevents loss of auxiliary pump pressure to the lube oil system in case of gear pump failure. The gear pump check valve also contains an orifice, which regulates the flow of lubricating oil to the pump gears during the cranking sequence, when the lube oil pressure is being supplied by the auxiliary pump.
01-04-E MOD. INPR/SVIL/ P.F. 12/00
160.5810÷16
P. 12-5
g GEPS Oil & Gas 12.8.2
Nuovo Pignone
Test valve - low lube oil pressure - auxiliary pump start A test valve, mounted on the gauge cabinet, serves to test the automatic startup of the auxiliary lube oil pump through the signals generated by the low lube oil alarm/pump start pressure switch 63QA-1 or by the pressure transmitter 96QA-1 while the unit is operating normally on the main lube oil pump. By opening the test valve, lube oil pressure falls to the setting of the pressure switch and the auxiliary lube oil pump should start. The annunciator should indicate a condition of ”Auxiliary Lube Oil Pump Running”. When closing the test valve, the pump continues to run (through the contacts of the complete sequence check relay) until manual shutdown. After completing this test, reset the annunciator.
12.8.3
Test valve - low lube oil pressure/emergency pump start A test valve, mounted on the gauge cabinet, serves to check automatic startup of the emergency lube oil pump by pressure switches 63QT-1/2 or by pressure transmitter 96QA-1 (start the pump), which signal a bearing header alarm. It is possible to run this test while the unit is operating normally on the main lube oil pump or when the turbine is operating or shut down and the auxiliary AC pump is supplying pressure to the lube oil system. The pressure transmitters with bleed valves are installed after an orifice in the pressure transmitter a piping connected with the bearing lube oil header. The test valve is installed in the piping after the transmitters and is normally closed. When performing a test, open the bleed valve gradually to lower the lube oil system pressure in the piping where the transmitter is mounted. This oil pressure is indicated on a gauge, connected with the pressure line. This gauge serves to check the pressure points at which the switches operate to indicate a condition of low lube oil pressure on the annunciator and start the emergency pump.
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160.5810÷16
P. 12-6
g GEPS Oil & Gas
Nuovo Pignone
When the oil pressure falls to the setting of pressure switches 63QT-1/2 or of pressure transmitter 96QA-1, the condition of low lube oil pressure will be indicated on the UCP's CRT. Opening the bleed valve further will reduce the oil pressure in the test line piping to the setting of the pressure transmitter 96QT-1; the latter signals and actuates startup of the emergency pump. Upon closing the bleed valve, oil pressure returns to normal and the contacts of pressure switches 63QT-1/2 and pressure transmitters 96QT-1A return to their normal condition. The emergency lube oil pump is shut down. Reset the annunciator when the tests are completed.
12.8.4
Regulating valve VPR2 - lube oil header pressure regulation A diaphragm-operated regulating valve VPR2 maintains the lube oil pressure in the main oil header at approximately 1.75 Bar (25 PSI). This valve is installed in the lube oil discharge line from the oil filters, downstream of the test orifice. The valve diaphragm, connected with the lube header, actuates the valve as required to maintain the specified system pressure level. A bypass orifice is also present in the body of regulating valve VPR2, to permit limited valve travel and damped regulatory control. Moreover, it ensures oil flow to the header in the event of malfunction and closure of the VPR2 valve.
12.9 LUBE OIL TEMPERATURE CONTROL
12.9.1
Standby heaters During standby periods, immersion heaters 23QT-1/2/3, installed in the oil tank, maintain the lubricant at the proper viscosity for turbine startup. . Temperature switches 49QT-1/2/3 switch off the heaters (for setting values, refer to the Device Summary in volume "Reference Drawings”).
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P. 12-7
g GEPS Oil & Gas
Nuovo Pignone
The A.C. motor driven auxiliary lube oil pump always operates during standby heating periods to circulate the oil in the system. The heater control circuitry is shown on the MK V or MK VI "Sequencing Diagram", supplied beforehand, and temperature control settings are noted in the Device Summary included in the “Reference Drawings” volume.
12.10 OIL FILTERS
12.10.1 Main Oil Filter A 12-micron, absolute inorganic fiber filter installed in the lube system just after the lube oil cooler, filtrates all lube oil. Two (dual) filters with a transfer valve, installed between the filters, direct the oil flow through either filter and into the lube oil header. Dual filters are arranged side by side in the tank. They are connected with the pump discharge header through a manual transfer valve. Only one filter at a time is in service; thus, it is possible to clean, inspect and service the second one without interrupting oil flow or shutting down the gas turbine. By means of the manually operated, worm-driven transfer valve, you can put into service one filter and you can take out the second one, without interrupting the oil flow to the main lube oil header. It would be advisable to change filters before the differential pressure gauge indicates a differential pressure of "24 PSI "; pressure switch 63QQ provide an alarm.
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160.5810÷16
P. 12-8
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12.11 PRESSURE AND TEMPERATURE PROTECTIVE DEVICES Pressure switches 63QA-1, 63QT-1/2 or pressure transmitter 96QA-1, detect low lubricating fluid pressure. They respond when the line pressure drops to a specified value. Pressure switches 63QT-1/2 or pressure transmitter 96QA-2, installed in the lubricant header piping, signal an alarm and start the auxiliary pump if the lubricant pressure drops below its predetermined setting. Temperature switches 26QT-1A/B and thermocouples LT-TH-1A/B are installed in the lubricating fluid header piping. They cause an alarm to sound and trip the unit should the temperature of the lubricant to the bearings exceed the preset limit. 12.11.1 Oil level gauge and alarm Displacer type liquid level switches are mounted on the lube oil reservoir. The Schematic Piping Diagram lists the maximum and minimum lube oil levels. If the lube oil level falls below a minimum set point or rises above a maximum set point, an alarm will sound. A reflex type level gauge is mounted on the side of the reservoir for local level indication.
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160.5810÷16
P. 12-9
g GEPS Oil & Gas
Nuovo Pignone
12.11.2 Low lube oil pressure alarm switches, 63QA-1 Pressure switch 63QA-1 senses lube oil pressure in the lube oil pump discharge header. In the event of low oil pressure, this switch transmits a signal that starts the auxiliary lube oil pump and displays an annunciator alarm .
12.11.3 High lube oil temperature alarm and trip switches Temperature switches 26QT-1A and 26QT-1B are installed in the main lube oil header to sense high lube oil temperature. Switches 26QT-1 and 26QT-2 are connected in the master protective sequence circuit; they shut down the turbine on sensing high oil temperature. The control logic is such that two out of the three temperature switches and thermocouples (26QT-1/2, LT-TH-1A/B) must sense high temperature before the turbine is shut down.
01-04-E MOD. INPR/SVIL/ P.F. 12/00
160.5810÷16
P. 12-10
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12.12 HYDROCARBON BASE LUBRICATING OIL RECOMMENDATIONS FOR GAS TURBINE (SOM 17366/4)
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P. 12-11
Nuovo Pignone
TITOLO – TITLE
HYDROCARBON BASE LUBRICATING OIL RECOMMENDATIONS FOR GAS TURBINE
FIRENZE
INTRODUCTIONS
This publication contains information intended to help the purchaser of a Nuovo Pignone gas turbine and the oil vendor to select the proper grade and quality of lubricating oil for the turbine application. The recommendations in this publication apply to Nuovo Pignone gas turbines only. For lubrication recommendations for equipment other than Nuovo Pignone, refer to the instructions provided by the manufacturer of that equipment. The successful operation of gas turbine and driven equipment is vitally dependent upon the lubricating oil system. It is necessary that all factors contributing to correct lubrication be present and that the entire system be maintained in good order. The life of the apparatus depends upon a continuous supply of oil of proper quality, quantity, temperature and pressure. The life of the oil itself, if it is free from solids has the proper viscosity, and is noncorrosive, is of prime importance to the user. Hence, any values relative to oil life are given for reference only.
UTP 004 / I - A (1/1) • 171086 •27/10/94
Any request to use grades or types of oils other than those specified in this publication should be directed to the Nuovo Pignone Field Representative.
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This document is the property of NUOVO PIGNONE. All right are reserved according to law.
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RECOMMENDED PROPERTIES
GENERAL
Three viscosity grades of rust and oxidation inhibited petroleum oils have generally covered the requirements for gas turbines and their load devices. The properties are summarized in Table 1, and they are termed "light, medium, and heavy". The preferred oil for Nuovo Pignone's gas turbine is the light grade oil having a viscosity of 140 to 170 SUS* at a temperature of 100°F. If it is necessary to use the medium or heavy grade oil, equipment changes may be necessary in the lubricating system, pressure regulating system, or orificing of machine bearings. Therefore, it is necessary that the factory review all requests for use of any oil other than the light grade turbine oil. Typical total acid number (TAN) of new oils range from 0.05 to 0.15 MG KOH/g. After a new oil has been in use for a period of time, the TAN will probably decrease as the oil additives, which have acid-like characteristics, plate out (as they should do) on the internal metal surfaces of the oil system. After these additives are depleted from the oil, the neutralization value will gradually increase with age and use. ANTI-WEAR OILS
In some applications the use of anti-wear additives in addition to rust and oxidation inhibitors may be required. The use of these additives may give an initial total acid number much higher than with oils not containing such additives. With use, the acid number will go down as these additives are used. Eventually as the oil oxidizes, the acid number will increase. The properties of three grades of oils containing anti-wear additives are listed in Table 1.
UTP 004 / I - A (1/1) • 171086 •27/10/94
Note:
*
Oils with chlorine or other halogen containing additives are not to be used in Nuovo Pignone's gas turbines. Oils with tricresyl phosphate (TCP) are preferred. Oils with zinc dialkyl dithiophosphate (ZDDP) are acceptable and are being used in these turbines. The operator should be aware that ZDDP is a variable product and is less thermally and hydrolytically stable than other materials such as tricresyl phosphate. Other additives may be satisfactory, but the proper use of these additives should be established between the operator and his supplier, therefore the operator should discuss his particular application with the supplier of the oil.
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LOW POUR POINT OILS
A low pour point oil may be required for some turbines. Generally, those containing direct oil to air heat exchangers should use an oil with a pour point temperature of at least 20°F below the minimum expected ambient temperature. The properties of two such oils, (petroleum base and a synthetic hydrocarbon) are listed in Table 1.
OIL SERVICE LIFE
UTP 004 / I - A (1/1) • 171086 •27/10/94
It is the joint responsibility of the user and the producer of the oil to establish criteria for determining property values for the oil in service. Usually, this may be based on a combination of factors: acid number, viscosity, inhibitor concentration, etc. Nuovo Pignone makes no recommendation in this regard.
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LUBRICATING OIL SYSTEM
The lubricating oil system is designed to provide an ample supply of filtered lubricating oil at the proper temperature and pressure for operation of the turbine and its associated equipment. Protective devices are incorporated into those systems where it is necessary to protect the equipment against low lubricating oil supply, low lubricating oil pressure, and high lubricating oil temperature. The protective devices either sound a warning or will automatically shut down the unit if any of these conditions occur. The particular arrangement of the system, the protective devices, and the system settings are shown on the schematic piping diagram for the specific gas turbine. other sections of the instruction book discuss the system's operation, maintenance, and instructions for the various pieces of equipment included in the system. OPERATING TEMPERATURES
Lubricating oil is exposed to a range of temperature while circulating through the gas turbine. For reliable circulation of oil before starting, the viscosity must be 800 SUS or less. Converting this to temperatures, the minimum oil temperature before starting shall be 50°F, 70°F, or 90°F, respectively for the light, medium, or heavy grades of oil. Figure 1 shows the effect of temperature on the viscosity for three different grades of turbine oil. The viscosities of the three oils at 100°F, are quiet different; at this temperature, the viscosity of oil number 1 is 150 SUS, the viscosity of oil number 2 is 300 SUS, and the viscosity of oil number 3 is 500 SUS. However, the viscosity of the three oils is the same (150 SUS) when the temperature of oil number 1 is 100°F, oil number 2 is 126°F and oil Therefore, the performance of bearings, gears, hydraulic controls, etc. would be similar when any one of the three oils is used, provided the oil temperature is adjusted to maintain the desired operating viscosity.
UTP 004 / I - A (1/1) • 171086 •27/10/94
The normal bearing inlet oil temperature is 130°F, however, because of ambient conditions and/or water temperatures, the actual operating conditions may be different. The cooling equipment for the lubricating system is designed to maintain the nominal 130°F (bearing inlet oil temperature) when raw water is available for cooling. However, when radiator systems are involved, the sizing is such that for the maximum recorded ambient temperature at the site, the bearing header temperature may be i 60°F. The gas turbine bearings are designed to operate satisfactorily at this inlet oil temperature. COMM. - JOB ITEM
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FIRENZE
With radiator Systems, the nominal 130°F bearing header will be maintained for a high percentage of the operating time. In special cases, other design header temperatures are used as dictated by the load devices. Operating bearing temperature rises are discussed in appropriate sections of the instruction book. Typically, the oil temperature rise from inlet to drain is 25°F to 50°F. If reduction gear is involved, this temperature rise may be 60°F. Some gas turbines have bearings that are in an ambient of hot pressurized air. For these turbines, the bearing housing is so sealed with labyrinths and air flow that the bearing housing and drain space are at approximately atmospheric pressure. This ambient and the sealing air may be 500°F to 750°F. A portion of the lubricating oil will be mixed with a small quantity of hot air and will wash metal surfaces between 500°F to 750°F. The lube oil temperature in the tank will be 25°F to 40°F above the bearing header, and the bulk temperature will be 155°F to 200°F during operation.
CORROSION-PREVENTIVE MATERIALS USED FOR SHIPPING
Manufacturing procedures provide for corrosion protection by cleaning and treating all metal surfaces contacting the lubricating oil in the lubrication system. The inside walls of the lubricating oil tank are processed at the factory using an oil-resistant paint. The inner surfaces of all lubricating oil piping, bearings, hydraulic control devices, and surfaces of other components In contact with the turbine lubricating oil are coated with a vapor space rust-inhibited lubricating oil which is used as a combination test and shipping oil. The oil and its vapors which remain on the wetted surfaces after the turbine has completed the factory test run serve as a corrosion-preventive agent. This remaining oil is generally compatible with turbine oils, but it is left to the discretion of the purchaser and oil vendor to decide whether the residue of this test oil should be removed by "field flush". At installation it is expected that most of the remaining oil will be removed and the interior of the oil tank Inspected for cleanliness.
UTP 004 / I - A (1/1) • 171086 •27/10/94
All exterior finished machine surfaces of parts and assemblies which could be exposed to corrosive conditions during storage and shipment are coated with slushing oil. This material is not compatible with turbine oil and must be removed from all surfaces. (Slushing oil can be removed with petroleum spirits or kerosene)
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CLEANING REQUIRED AT INSTALLATION
The reliable operation of controls and machine bearings is dependent upon the cleanliness of the lubricating oil system. During manufacture, considerable care has been taken in processing, cleaning, and flushing this system to maintain cleanliness. Oil filters have been installed to provide filtering of all oil that is used in the system. At installation, the entire lubricating system must be thoroughly cleaned; weld Spatter, metal chips, dirt, and other foreign matter incident to erection and installation of the piping, etc., and any slushing oil which has been applied to metal surfaces contacting the turbine oil, must be totally removed. Any surface, internal or external, contacting the lube oil must be thoroughly cleaned. This is to include any new components to be installed in the system such as, auxiliary oil pumps and oil coolers. If the lubricating oil System becomes contaminated during installation of the gas turbine, it is recommended that the lube oil system, load devices system, and interconnecting piping be flushed with hot oil. During this flush a hot oil and pipe arrangement should be used, and it should be made to by-pass the machine bearings and other critical accessory devices. Careful planning of this flush must be made to prevent any dirt, introduced during the installation, from being flushed into clean, critical devices. The unit lube oil filters should be operative during this flush. For more complete recommendations, refer to ASME Standard LOS-4C1 ASTM-ASME - Recommended Practices for Flushing and Cleaning of Gas Turbine Generator Lubricating Oil Systems.
UTP 004 / I - A (1/1) • 171086 •27/10/94
Certain models of Nuovo Pignone gas turbines are equipped with a completely assembled package of the lubricating system and turbine equipment. It may not be necessary to hot-oilflush these at installation, except when the shipping oil has to be flushed out to satisfy the compatibility considerations of the turbine oil. If it should be decided by the purchaser and the oil vendor that a field flush is not required particular care must be taken during installation to maintain cleanliness of this package, the cleanliness of the load devices, and the cleanliness of the interconnecting piping.
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FIRENZE
RESPONSIBILITY OF OPERATOR
After the unit is installed, and prior to its initial starting, the operator should take all precautions to ensure that:
1.
The lubricating system has been thoroughly flushed and/or is clean.
2.
The supply of turbine oil is ample for operation of the unit.
During operation of the unit, the operator should establish a routine inspection procedure to ensure that:
1.
The temperature and pressure levels of the lube oil system are within the limits specified by the instruction book and the piping schematic diagrams.
2.
The oil purity is maintained by checking for water leaks, by draining sludge, and by adhering closely to the regulation set forth by the oil vendor for sampling purifying, and replenishing the lube oil supply.
RESPONSIBILITY OF OIL VENDOR
It is generally recognized that turbine lubricating oil should be a petroleum derivative free from water, sediment, inorganic acids, or any material which, In the service specified, would be injurious to the oil or the equipment. There should be no tendency toward permanent emulsification or rapid oxidation with the formation of sludge.
UTP 004 / I - A (1/1) • 171086 •27/10/94
The responsibility of supplying the proper oil for the lubricating system rests with the oil vendor and the turbine operator. This responsibility includes specifications for flushing, purifying, inspection, and treatment of the oil to ensure satisfactory performance of the equipment in service.
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TEST METHODS
VISCOSITY
The viscosity of an oil is its resistance to flow. For turbine oils, it is usually reported in Saybolt Universal Seconds (SUS or SSU) at a given temperature and determined per ASTM D88, "Saybolt Viscosity". It is the time in seconds for 60 milliliters of oil to flow from a container through a calibrated orifice at a specified temperature. In the design of lubrication systems consideration is given to the viscosity at which the oil becomes 100 viscous to be pumped. For Nuovo Pignone's gas turbines the viscosity should be less than 800 SUS for proper circulation of the oil before starting.
POUR POINT
The pour point is the lowest temperature at which oil will flow. It is reported In increments of 5°F. It is determined as the temperature at which the oil contained in a tube with an inside diameter of 30 to 33.5 mm. will not flow within five seconds of rotating the tube 90 degrees from the vertical to the horizontal position.
FLASH POINT
Flash point is determined per ASTM D92, "Flash and Fire Points by Cleveland Open Cup". It is the temperature at which the fluid contained in a test cup and heated at a constant rate will flash but not burn when a flame is passed over the cup. It is indirectly a measure of both the volatility of the oil and the flammability of these volatiles. Since there are more accurate ways of determining these; e.g., distillation to determine volatiles, this is mainly of value as a quality control test.
FIRE POINT
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Fire point is the temperature at which the oil in a test cup will continue to burn when tested as indicated under paragraph "Flash Point".
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TOTAL ACID NUMBER
The total acid number is the milligrams of potassium hydroxide (KOH) required to neutralize the acidic constituents in a gram of sample. It is determined per ASTM D974, "Neutralization Number by Color-Indicator Titration". The total acid number (TAN) is sometimes called the neutralization number (NN) or neut number and also the acid number (AN). Turbine oils as well as most other lubricants normally contain additives for oxidation and rust inhibition and other purposes. For this reason the total acid number of a new or used oil should not be considered an indication of a tendency of the oil to corrode. The ASTM procedure states that there is no general correlation between bearing corrosion and acid numbers. The total acid numbers taken from a System over a period of time are a method to follow additive depletion and subsequent decomposition of the base oil. In a lubricant containing additives such as rust inhibitors, anti-wear additives etc., the total acid number should go down in value as the inhibitor is placed out on the surface of the System and then gradually increase as the oil oxidizes.
RUST PREVENTION
The rust prevention characteristics of the oil are determined per ASTM D665. A mixture of 300 ml of oil and 30 ml of distilled water (Procedure A) or synthetic seawater (Procedure B) is stirred, while held at a temperature of 140°F. A carbon steel rod conforming to ASTM specification Al 08, Grade 1018, is immersed in the oil for a period of 24 hours, then examined for rust.
OXIDATION RESISTANCE
This test is run per ASTM D943, "Oxidation Characteristics of Inhibited Steam-Turbine Oils". It is the time in hours for the acidity to reach 2.0 milligrams of potassium hydroxide per gram of sample in a sample of oil containing steel and copper wire coiled together and maintained at a temperature of 95°C (203°F) with oxygen passing, through it and to which water has been added.
UTP 004 / I - A (1/1) • 171086 •27/10/94
This test is used primarily to determine the life of the oxidation inhibitor and does not necessarily indicate the stability of the base oil.
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A
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REV. DESCRIZIONE - DESCRIPTION Il presente documento è di proprietà NUOVO PIGNONE. A termine di legge ogni diritto è riservato. This document is the property of NUOVO PIGNONE. All right are reserved according to law.
REPLACES SOSTITUITO DA – REPLACED BY
Nuovo Pignone
TITOLO – TITLE
HYDROCARBON BASE LUBRICATING OIL RECOMMENDATIONS FOR GAS TURBINE
FIRENZE
LOAD CARRYING CAPACITY
UTP 004 / I - A (1/1) • 171086 •27/10/94
The load carrying capacity is determined per ASTM Dl 947. It is reported as the "pounds per inch of face width" at which the average tooth face scuffing of 22.1/2 percent has been reached. A four-square tester is loaded in specified increments. Standard test speed is 10,000 RPM; inlet oil temperature is 160°F to 170°F
COMM. - JOB ITEM
N. SOM 17366/4 0
EMISSIONE - ISSUE
LINGUA - LANG.
PAGINA - SHEET
A
10 / 11
REV. DESCRIZIONE - DESCRIPTION Il presente documento è di proprietà NUOVO PIGNONE. A termine di legge ogni diritto è riservato. This document is the property of NUOVO PIGNONE. All right are reserved according to law.
REPLACES SOSTITUITO DA – REPLACED BY
Nuovo Pignone
TITOLO – TITLE
HYDROCARBON BASE LUBRICATING OIL RECOMMENDATIONS FOR GAS TURBINE
FIRENZE
TABLE I
TURBINE OIL PROPERTIES
I
Property
Viscosity at 100°F (min.) (max.)
Saybolt Universal Seconds
Viscosity at 210°F (min)
Medium Grade
III
Heavy Grade
IV
V
VI
VII
VIII
Light Grade With AntiWear
Medium Grade With AntiWear
Heavy Grade With AntiWear
Light Grade Low Pour
Add.
Add.
Add.
Point
Synthetic Hydrocarbon Low Pour Point
140 170
270 325
380 560
140 170
270 325
380 560
140 170
140 170
Saybolt Univ. Sec.
43
47
55
43
47
55
43
43
Pour Point (max.)
°F
20
25
30
20
25
30
-25
-65
Flash Point (min.)
°F
330
350
360
330
350
360
330
450
Fire Point
°F
370
390
400
370
390
400
370
490
mg KOH/gm
0.20
0.20
0.20
1.60
1.60
1.60
0.20
0.20
−
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Pass
Hours to TAN of 2.0
1000
1000
1000
1000
1000
1000
1000
1000
Pounds Per Inch
*
*
*
1750
2000
2000
*
*
Total Acid Number (TAN) (max.) Rust Preventing Characteristics Oxidation Characteristics (min.) Load Carrying Capacity (min.)
UTP 004 / I - A (1/1) • 171086 •27/10/94
Units
Light Grade
II
COMM. - JOB ITEM
N. SOM 17366/4 0
EMISSIONE - ISSUE
LINGUA - LANG.
PAGINA - SHEET
A
11 / 12
REV. DESCRIZIONE - DESCRIPTION Il presente documento è di proprietà NUOVO PIGNONE. A termine di legge ogni diritto è riservato. This document is the property of NUOVO PIGNONE. All right are reserved according to law.
REPLACES SOSTITUITO DA – REPLACED BY
Nuovo Pignone
TITOLO – TITLE
HYDROCARBON BASE LUBRICATING OIL RECOMMENDATIONS FOR GAS TURBINE
UTP 004 / I - A (1/1) • 171086 •27/10/94
FIRENZE
FIGURE 1 COMM. - JOB ITEM
N. SOM 17366/4 0
EMISSIONE - ISSUE
LINGUA - LANG.
PAGINA - SHEET
A
12 / 12
REV. DESCRIZIONE - DESCRIPTION Il presente documento è di proprietà NUOVO PIGNONE. A termine di legge ogni diritto è riservato. This document is the property of NUOVO PIGNONE. All right are reserved according to law.
REPLACES SOSTITUITO DA – REPLACED BY
g GEPS Oil & Gas
Nuovo Pignone
12.13 LUBE OIL COOLER(S) The lube oil sent to the turbine lube oil header and to the driven machines must have a temperature that guarantees its correct viscosity. For this purpose, the lube oil system includes a water/oil cooler or an air/oil cooler. The lube oil is sent to the cooler installed downstream of the pump and upstream of the lube oil filters. The water/oil cooler may have either one or two bodies arranged in parallel and utilizing a continuous flow transfer valve. This feature permits either cooler to be cut out of service for inspection or maintenance without interrupting oil flow to the machines. The air/oil cooler is a finned tube heat exchanger provided with electric motor driven fans. 12.13.1 Temperature regulating valve (VTR-1) A temperature regulating valve (VTR-1) controls the lube oil flow through the off-base cooling unit. This valve is installed in the feed line to the cooling unit. Valve actuation is controlled by lube oil header temperature to maintain the lube oil temperature at a predetermined value. During turbine start-up, this valve allows all oil to by-pass the cooler. 12.14 OIL VAPOUR SEPARATOR The vapours produced from heated oil are extremely dangerous, both if emitted into the atmosphere and if induced into the oil circuit, as they are considered highly inflammable. For this reason, a vapour separator is used in order to condense the volatile particles of oil, which, by the action of the gravity force, fall back into the oil casing. The system is composed substantially of the following elements: Electric motor; Centrifugal fan; Level gauge; Differential pressure gauge. For more information on technical characteristics and maintenance of the oil vapour separator console, please refer to “Auxiliary Equipment” volume.
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HYDRAULIC SUPPLY SYSTEM
13.1 GENERAL The hydraulic supply system provides fluid power for operating the control components of the gas turbine fuel system. This fluid provides the means for opening or resetting the fuel stop valve. In addition, it serves to operate the turbine variable inlet guide vanes and the hydraulic trip devices of the turbine protection system. Major system components include: a main hydraulic supply pump; an auxiliary supply pump; system filters; an accumulator assembly and the hydraulic supply manifold assembly. For device settings, adjustments and design features refer to the Piping Device Summary enclosed in volume “Reference Drawings”.
13.2 FUNCTIONAL DESCRIPTION Regulated, filtered lube oil from the bearing header of the gas turbine is used as the highpressure fluid necessary to meet the hydraulic system requirements. A gear type pump, driven by a shaft of the accessory gear, is the primary pump of this high-pressure oil; a motor-driven vane type pump provides the necessary auxiliary backup. Pressure compensator VPR3-1, built in the pump, controls hydraulic oil, pressurized by the main hydraulic pump. The compensator varies the stroke of the pump to maintain a set pressure at the pump discharge. At turbine start-up, while the main pump is not yet at operating speed, the auxiliary pump starts and continues to run until the speed sensor indicates that the minimum governing speed has been reached.
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When the main pump is operating and it fails to maintain adequate pressure, pressure transmitter 96HQ-1A or pressure switch 63HQ-1 sense this condition and the pressure switch gives a signal to start the auxiliary pump. If pressure drops under a predetermined setting of pressure transmitter 96HQ-1B or pressure switch 63HQ-2A, a turbine trip is initiated. A second pressure transmitter 96HQ-1C or pressure switch 63HQ-2B provides a backup if 63HQ-1B or 96HQ-2A should fail. However, at least two of the three switches (96HQ-1A, 96HQ-1B, 96HQ-1C or 63HQ-1, 63HQ-2A, 63HQ-2B) must sense low pressure before the turbine is tripped. Hydraulic fluid is pumped to the hydraulic manifold; this assembly is designed in a way to interconnect a number of small components. Both the main and auxiliary pumps deliver oil to the respective input connections on the hydraulic manifold assembly. This assembly houses two relief valves, two air bleed valves and two check valves. One relief valve (VR22) controls the auxiliary pump output pressure while the other (VR21) protects the main hydraulic pump circuit from damage in the event of a failure of the main pump pressure compensator. Each pump circuit contains a check valve downstream of its relief valve; this valve keeps the hydraulic lines full when the turbine is shut down. Bleed valves vent any air present in the pump discharge lines. A pressure gauge on the assembly reads differential pressure across the manifold. See Control and Trip Oil System for details. From a single output connection on the manifold assembly, the high pressure fluid flows through the system filter(s) and becomes a high pressure control fluid; this fluid operates the turbine control and protection system and the turbine components that admit or shut off fuel. A hydraulic accumulator assembly with three accumulators is also connected with the high-pressure line of the hydraulic supply system to absorb any severe shocks that may occur when the supply pumps are started. Refer to the Trip Oil System text for further information on the accumulators and their function. From the bearing header of the turbine, the lubricating fluid is first filtered and then sent to the hydraulic pumps. The hydraulic supply system filter, installed in the output piping from the hydraulic supply manifold, prevents contaminants and other wear particles of the pumps from entering the trip devices of the turbine protection system.
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Differential pressure gauges are installed on the piping of each filter to provide an indication of oil pressure across the filter. Twin hydraulic supply filters of inorganic fibre with a 5-micron absolute filtration are also installed. A manually operated transfer valve is placed in the hydraulic system to allow filter replacement while the machine is running under load. Before operating the transfer valve, the filter, which is not in use, must be filled with oil and brought to a pressure balanced with the one of the filter in use. This is accomplished by slowly opening the needle valve in the 3/4-inch "fill" line between the filters. The valve in the vent line should be cracked open to allow any entrapped air to escape and then tightly closed. After waiting a few minutes for pressure equalization, it is possible to operate the transfer valve. This feature permits machine operation with one filter, while the other is being serviced or replaced. Differential pressure switch 63HF sound an alarm when the pressure drop across the hydraulic supply system filter is of magnitude that requires replacement of the filter cartridge. Although the filter cartridges are rated to withstand a pressure drop of "5 Bar", the setting of the differential pressure switch must be significantly below this value to ensure that the hydraulic supply system filter cartridge does not fail. For more information concerning the technical characteristics and maintenance of the main and auxiliary hydraulic pumps, please refer to the relative data sheets in Volume “Reference Drawings” and to the relative instruction books in Volume “Auxiliary Equipment”.
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CONTROL AND TRIP OIL SYSTEM
14.1 GENERAL The gas turbine protection system consists of a number of primary and secondary systems, several of which operate at each normal start-up and shutdown. The other systems and components are strictly for abnormal and emergency operating conditions requiring shutdown of the turbine. Some of these protection systems and their components operate through the electrical turbine control panel (SPEEDTRONIC control system). On the contrary, the other systems operate directly on the components of the turbine totally independent of the electrical turbine control panel. The hydraulic trip oil system is the primary protection interface between the turbine control panel and the turbine components that admit or shut off fuel to the turbine. Please refer to MKV or MKVI documentation and to the piping schematic diagram in the “REFERENCE DRAWINGS” volume.
14.2 FUNCTIONAL DESCRIPTION The hydraulic oil system provides for actuation of the variable inlet guide vanes and variable-angle second-stage nozzle partitions. High-pressure oil from the hydraulic supply system serves to pressurize the trip servo valve. The trip oil system uses low-pressure trip circuit oil taken from the turbine lube oil system. The fluid flows through a piping orifice to become the regulated oil. The size of this orifice limits the flow of lube fluid and ensures adequate capacity for the tripping device without causing starvation of the lube system when the trip oil system is activated. The low-pressure trip circuit oil flows through an orifice to the low-pressure trip circuit. From this point, it flows to the turbine fuel system. The low-pressure trip system is also connected directly with the high and lowpressure rotor overspeed trip devices; it commands a shutdown of the turbine whenever an overspeed condition occurs. Limit switches 12HA-1 and 12LA-1 provide the related alarm signal.
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Redundant pressure switches 63HG-1-2 and 3 are installed in the low-pressure trip system; they provide feedback to the turbine control system and permissive circuitry, ensuring the trip oil pressure levels required for turbine operation. The low-pressure system is provided also with a solenoid valve 20HD and a manual emergency trip valve. The primary electronic overspeed protection system releases a trip signal, which energizes solenoid valve 20HD and dumps the lowpressure trip oil to drain. This action, in turn, causes the second-stage nozzle to open and the fuel stop valve to close, shutting down the gas turbine. The manual emergency trip valve also dumps the low-pressure trip oil, with similar results.
14.3 SECOND-STAGE NOZZLE CONTROL ASSEMBLY The second-stage nozzle divides the available energy between the high-pressure and low-pressure turbines. Opening this variable-angle, second-stage nozzle decreases backpressure on the high-pressure turbine; this increases the pressure drop and the torque generated by the high-pressure turbine. The compressor/high pressure turbine speed increases accordingly. The nozzle control ring assembly responds to actuation by a hydraulic cylinder and changes the position of the nozzle partitions as needed. The two-shaft turbine design provides: lower starting torque requirements; high allowable ambient operating levels; no-load operation within load rotor speed/temperature limitations and lower heat rate with high loading. The hydraulic portion of the nozzle control consists of a hydraulic actuating cylinder, servo valve, dump valve, accumulators, transducers, and a combined manifold - mounting plate. High-pressure hydraulic oil enters this control circuit through a supply check valve and a parallel restriction orifice. The latter is designed to allow unrestricted entry of oil, while limiting the rate of pressure drop whenever the supply pressure falls. The piston type accumulators are provided to ensure that sufficient control oil is available to open the nozzle control assembly in the event there is a loss of control oil supply pressure and to meet peak oil demands during transient movement of the cylinder. The arrangement of the accumulators allows either one to be shut off from the circuit (this must be done only with machine at a standstill), to be drained in order to check the gas pre-charge pressure and to be recharged, if necessary. To determine the pre-charge pressure within the accumulator, the shutoff valve is closed and the bleed valve is open. If recharging is required, use only dry nitrogen.
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Hydraulic supply oil, before entering the manifold assembly, passes first through a parallel check valve and orifice; designed to provide a free flow of oil to the nozzle control, while limiting the reverse flow of supply oil (through the orifice). From the orifice-check valve combination, oil reaches the accumulator assembly and the nozzle dump valve. When the trip oil pressure actuates the nozzle dump valve, the servo valve activates the actuator for normal control operation. With the nozzle dump valve in the normal position (no trip oil pressure applied), the manifold supply oil reaches directly the port on the “retract” side of the actuator (vanes open), while the “extend” port (vanes closed) is connected to drain. Both servo valve control ports are blocked for this condition.
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The accumulator assembly serves dual functions: it provides hydraulic supply oil to the servo valve during rapid transient of actuator movement and, more importantly, provides sufficient supply of oil to move the nozzles to the “open” position, when so commanded by the input to the servo valve for either a normal or an emergency turbine shutdown. The system is designed in a way that permits to isolate one accumulator from the system while this is operating, in order to check the pre-charge pressure or to service it.
CAUTION THIS SYSTEM MUST NOT BE OPERATED WITHOUT AT LEAST ONE OF THE ACCUMULATORS HYDRAULICALLY CONNECTED IN THE CIRCUIT WITH THE PROPER PRECHARGE PRESSURE.
The nozzle dump valve is designed to sense low-pressure trip oil (OT), and to allow either control of the hydraulic cylinder by the servo valve, when OT is present, or effectively to bypass the servo valve and cause the hydraulic cylinder to stroke the nozzle full open, whenever loss of OT occurs. Depressurizing the dump valve in this manner redirects high-pressure control oil (OH) to actuate the nozzle assembly to the fully open position. The hydraulic cylinder is a conventional double acting, double extending rod unit; one of its ends is connected with the nozzle ring through a link, while the opposite end drives dual position transducers. The SPEEDTRONIC control system uses the output of the transducers as part of the closed loop position control for the nozzles. The nozzle control assembly, along with a portion of the SPEEDTRONIC control panel, forms a closed loop hydraulic position control, capable of positioning the nozzle.
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14.4 INLET GUIDE VANE CONTROL ASSEMBLY In conjunction with the tenth-stage compressor air bleed system, the variable inlet guide vanes permit rapid and smooth turbine starts and shutdowns without subjecting the compressor to pulsation at low speed. This pulsation is the result of airflow instability and reversal and can cause turbine damage. During start-up, the inlet guide vanes are kept in the low flow position, restricting the airflow. The tenth-stage bleed valves of the compressor bleed air system are open to protect the compressor. When compressor speed is above the pulsation level, the vanes are opened to the high flow position and the tenth-stage bleed valves are closed (refer to the Cooling and Sealing Air System text). Rotation of the inlet guide vane control ring on the compressor varies the chord angle of each individual guide vane. An electro hydraulic actuator, operated by high-pressure control oil, fixes the vanes in a closed position until the turbine is at 95% speed. The cylinder opens the vanes to their normal operating position for loading.
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COOLING AND SEALING AIR SYSTEM
15.1 GENERAL Air is used for cooling the various parts of the turbine section and for pressurizing the bearing oil seals in the gas turbine. This air is obtained from the gas turbine axial-flow compressor and from the ambient air at the gas turbine site. The air-cooled parts of the turbine section consist of: 1) first- and second-stage turbine wheel forward and aft faces; 2) the first-stage nozzle and retaining ring assembly; 3) the turbine rotor case, and 4) the exhaust frame and inner barrel support struts. The combustion chamber liners, elbows and transition pieces are designed to utilize the combustion air (compressed air) for effective cooling of these parts. In general, a description of the cooling and sealing air passages, which are incorporated into the various turbine parts and sections, is included elsewhere in this manual. The cooling and sealing air circuits are shown on the Schematic Piping Diagram. These circuits are described more in detail in the following paragraphs. The air, obtained from the axial-flow compressor, consists of: a) 5th-stage extraction air, b) 11th stage extraction air, c) compressor high-pressure air seal leakage air and d) compressor discharge air.
15.2 FIFTH AND ELEVENTH STAGE EXTRACTION AIR The fifth-stage extraction air serves to seal the No. 1, 3, and 4 bearings against loss of lube oil. The air is vented from the bearings to the lube oil tank through the bearing oil drainpipes. The eleventh-stage extraction air serves also to cool the aft wheel space of the first stage turbine wheel, plus the forward and aft wheel spaces of the second stage turbine wheel. In addition, this same extraction air is piped through manifolds to cool the turbine shell, exhaust frame and support struts in the inner barrel.
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Before sealing air is piped to the No. 1, 3, and 4 bearings, it flows first through a centrifugal dirt separator, which removes any entrained dust particles or other foreign matter that might be injurious to the bearings. A continuous blow-down orifice is provided in order to clean the separator.
15.3 COMPRESSOR HIGH PRESSURE SEAL LEAKAGE AIR High-pressure seal leakage air surrounds the bearing housing in the compressor discharge casing and turbine frame cavity. This air seals the oil deflectors of the No. 2 bearing. This air is vented from the bearing to the turbine lube oil tank through the bearing oil drainpipe. This leakage air serves also to cool the forward wheel space of the first-stage turbine. In addition, it seals the gas path as it escapes past the first-stage turbine wheel seals into the combustion gas stream.
15.4 AIR EXTRACTION SYSTEM FOR STARTUP AND SHUTDOWN COMPRESSOR PULSATION PROTECTION Axial-flow compressors are subject to pulsation at almost any speed, when operated at a pressure ratio that is high compared to no load. This condition can occur either at a high load or at a high rate of turbine acceleration. In a compressor, it results in large pressure fluctuations. In order to prevent compressor pulsation when the unit is accelerated during start-up or decelerated during shutdown, air is extracted from the 11th-stage of the compressor and discharged to the exhaust plenum. There are four 11th-stage extraction connections machined in the compressor casing. Two of the connections are in the top half of the compressor casing and the other two are in the bottom half. Compressor discharge air is piped externally through a porous filter and an air control solenoid valve, 20CB-1, to the actuating piston of the compressor bleed valves (VAB1/2).
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During start-up and shutdown, when the turbine speed is below 90%, solenoid valve 20CB vents the discharge air to the atmosphere, the bleed valves open, and the 11thstage air is bled into the exhaust plenum. When the turbine speed is above 90%, a signal from the control system actuates solenoid valve 20CB-1. The compressor discharge air is then routed to the bleed valves, which close and stop bleed air to the exhaust plenum. Limit switches 33CB-1 and 33CB-2 are mounted on the bleed valves. They provide a signal to the turbine control panel annunciator to indicate the valve position. The switches are included within the permissive starting sequence circuitry of the turbine control system.
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FIRE PROTECTION SYSTEM (CO2 )
16.1 GENERAL The carbon dioxide (CO2 ) Fire Protection System for the gas turbine unit extinguishes fires by reducing the oxygen content of the air in the compartment from an atmospheric normal of 21 percent to less than 15 percent. This concentration is not sufficient to support combustion. To reduce the oxygen content, a quantity of carbon dioxide (CO2 ) equal to or greater than 34 percent of the compartment volume is discharged into the compartment in one minute. In consideration of the reflash potential of combustibles exposed to high temperature metal, there follows another extended discharge of CO2 . This serves to maintain an extinguishing concentration and to minimize the likelihood of a reflash condition.
The system design conforms to the requirements specified in the NFPA Pamphlet No. 12. The system includes CO2 cylinders, discharge pipes and nozzles, solenoid pilot valves, pressure switches and fire detectors. Refer to the schematic diagram located in the volume reference drawings, where all system components are shown in the respective compartments. 16.2 FUNCTIONAL DESCRIPTION The carbon dioxide for the gas turbine unit is supplied from a bank of high pressure cylinders to a distribution system. From here, carbon dioxide reaches the discharge nozzles, located in the various compartments of the gas turbine unit. The solenoid pilot valves, which initiate the carbon dioxide discharge, are located on the discharge heads of the pilot cylinders at the cylinder bank. These are actuated automatically by an electrical signal from the heat-sensitive fire detectors, which are strategically located in the various compartments of the gas turbine unit.
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It is possible also to actuate the system manually by means of a hand wheel located at the top of each pilot carbon dioxide cylinder. Actuation of the system, either automatic or manual, will trip the turbine. Two separate discharges are used for the gas turbine unit: an initial discharge and an extended discharge. Within a few seconds after actuation, sufficient CO2 flows into the compartments of the gas turbine unit to rapidly build up an extinguishing concentration. This concentration is maintained for a prolonged period of time by the gradual addition of more CO2 from the extended discharge compensating for the compartment leakage.
16.3 FIRE FIGHTING SYSTEM OPERATION In order better to understand the fire protection system, the following paragraphs contain a brief description of its operation and distinctive features. Refer to the system schematic diagram located in the volume “Reference Drawings”. Should a fire occur in one of the protected turbine compartments, the contacts of the heat-sensitive fire detectors (45FA 1÷4 and 45FT 1÷9) will close and activate an electrical circuit. This will energize and open the solenoid valves (45CR-1/2).
When the solenoid valves are energized, pilot pressure is applied to the pistons of the pilot cylinder discharge heads, causing their pistons to move down. Consequently, the pistons move down and open the pilot cylinder valves. The cylinder valves are designed to remain open until the cylinders are empty. When the pilot cylinder valves open, they discharge their content through the flexible discharge connectors into the cylinder manifold and the piping network. The pressure developed in the manifold by the pilot cylinder causes the initial discharge cylinder valves to open, thereby discharging their contents into the cylinder manifold and initial discharge pipe network. Manifold pressure is also applied to the extended discharge cylinders through a differential pressure check valve. This causes their valves to open and to discharge their contents through the extended discharge pipe network.
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The differential pressure check valve prevents the CO2 used for extended discharge from entering the initial discharge manifold and piping network. Pressure switch (45CP-1/2), connected with the manifold, serves to perform alarm and shutdown functions. The carbon dioxide flow rate is controlled by the size of the orifices in the discharge nozzles located in the protected compartments. The orifices for the gas turbine compartments initial discharge permit a rapid discharge to quickly build up an extinguishing concentration. . The orifices for extended discharge in the gas turbine compartments are smaller. They permit a relatively slow discharge rate to maintain an extinguishing concentration for a prolonged period of time. By maintaining the extinguishing concentration the likelihood of a fire reigniting is minimized. For installation, inspection and maintenance of the fire protection systems, refer to Vendor instructions in Volume “filter house, ventilation system & fire protection system cabinet”.
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OPERATION
17.1 OPERATOR’S RESPONSIBILITY It is essential that the turbine operators be familiar with: the information contained in the following operating text, the Control Specification (By G.E.), (consult the Control System Settings drawing for the index of Control Specification drawings), the Piping Schematic drawings including the Device Summary, the Reference Drawing section, (consult the Device Summary for the index by model list and drawing number of applicable schematics), the SPEEDTRONIC Elementary, the location and use of indicators and devices mounted on the SPEEDTRONIC panel. The operator must also be aware of the power plant devices, which are tied into the gas turbine mechanically and electrically and could affect normal operation. One should attempt no starts, whether on a new or a newly overhauled turbine, until the following conditions have been met:
1.
the requirements listed under CHECKS PRIOR TO OPERATION have been met.
2.
ALL GENERAL OPERATING PRECAUTIONS have been noted.
17.2 GENERAL OPERATING PRECAUTIONS
17.2.1
Temperature Limits
Refer to the Control Specifications for actual exhaust temperature control settings. It is important to define a “baseline value” of exhaust temperature spread with which to compare future data. This baseline data is established during steady state operation after each of the following conditions: a.
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Initial start-up of unit
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b.
Before and after a planned shutdown
c.
Before and after planned maintenance.
An important point regarding the evaluation of exhaust temperature spreads is not necessarily the magnitude of the spread, but the change in spread over a period of time. The accurate recording and plotting of exhaust temperatures daily can indicate a developing problem. On the MS 5002 units, an average spread of 35°F (19.4 °C) ± 25F (13.8 °C) is expected. If exhaust temperature spread exceeds 60°F (33.3 °C) or a 25°F (13.8 °C) change from the baseline data, one should take corrective action. Turbine wheelspace temperature of 426°C (800°F) indicates the absolute maximum value permissible during operation. The thermocouples are identified together with their nomenclature on the Device Summary. The wheelspace temperature readings should be the average reading of at least two thermocouples, which are located nearly diametrically opposite each other in the wheelspace. If there is a good reason to doubt, one should reject the reading. One should take a reading from another thermocouple (if more than two thermocouples are installed). The faulty thermocouple should be replaced at the earliest convenience. When the average temperature in any wheelspace is higher than the temperature limit set forth above, it is an indication of trouble. High wheelspace temperature may be due to any of the following faults:
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1.
Restriction in cooling air lines
2.
Wear of turbine seals
3.
Excessive distortion of the turbine stator
4.
Improper positioning of thermocouples
5.
Malfunctioning combustion system
6.
Leakage in external piping
7.
Excessive distortion of inner exhaust diffuser.
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Check wheelspace temperatures very closely on initial start-up. If consistently high, and a check of the external cooling air circuits reveals nothing, it is permissible to increase the size of the cooling air orifices slightly. Consult with a Nuovo Pignone field representative and obtain his recommendations as to the size that an orifice should be increased. After a turbine overhaul, one should change all orifices back to their original size, assuming that one has returned all the turbine clearances to normal and corrected all leakage paths.
NOTE: Compressor discharge air, which leaks past the compressor high-pressure air seal, cools the first-stage turbine forward wheel-space. The annular cavity formed by the inner barrel of the discharge casing and the turbine rotor distance piece serves to channel this air internally to the wheel space. There are no orifices to control the airflow.
17.2.2
Pressure Limits Refer to the Device Summary for actual pressure switch settings. Lube oil pressure in the bearing feed header has a nominal value of 25.0 PSIG 1.75 bar g. The turbine will trip at 13.9 PSIG 0.52 bar g. Pressure variations between these values will result from particulate matter entrapped within the lube oil filtering system.
17.2.3
Vibration Limits The maximum overall vibration velocity of the gas turbine should never exceed 1.0 inch (25.4 mm) per second (trip set point) in either vertical or horizontal direction. One should initiate corrective action when the vibration levels exceed 0.5 inch (12.7 mm) per second (alarm set point) as indicated on the SPEEDTRONIC panel CRT (VIDEO). If doubt exists regarding the accuracy of the panel meter or if one desires more accurate and specific vibration readings, it is recommended to make a vibration check using vibration test equipment. If one uses a displacement meter for taking the vibration readings, one should use Vibration
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Analysis Form GL-139 to find the velocity component of the readings taken at a given speed (or frequency).
17.2.4
Load Limit Overloading of Gas Turbine - Facts Involved and Policy. It is practice of Nuovo Pignone to design and build margins of safety into gas turbines to permit meeting the contract commitments and to secure long life and trouble-free operation of the machinery. To secure a maximum degree of trouble-free operation, Nuovo Pignone designs more than ample margins of safety on turbine bucket thermal and dynamic stresses, compressor and turbine wheel stresses, coolers, etc. As a result, these machines are designed somewhat better than strictly necessary, but Nuovo Pignone believe that such margins of design are required, considering the great importance of reliability of these turbines to our customers and to industry. One cannot say, therefore, that one cannot operate these machines safely beyond the load limits. Such operation, however, always encroaches upon the design margins of the machines; consequently, this reduces reliability and increases maintenance. Accordingly, any malfunction that occurs as a result of operation beyond contract limits cannot be the responsibility of Nuovo Pignone. The gas turbines are designed mechanically so that, within prescribed limits, one can take advantage of the increased capability over nameplate rating, which is available at lower ambient temperatures (because of ni creased air density) without exceeding the maximum allowable turbine inlet temperature.
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When the ambient temperature is lower than that at which the load limit of the gas turbine is reached, the load must not be permitted to exceed that limit. Under these conditions, the gas turbine will operate at this load with a lower inlet temperature and the design stresses on the load coupling and turbine shaft will not be exceeded. If the turbine is overloaded so that the turbine exhaust temperature schedule is not followed for reasons of malfunctioning or improper setting of the exhaust temperature control system, the maximum allowable turbine inlet temperature or the maximum allowable exhaust temperature, or both, will be exceeded. This will result in a corresponding increase in maintenance and, in extreme cases, in failure of the turbine parts. The exhaust temperature control system senses the turbine exhaust temperatures and introduces proper bias to limit the fuel flow so that neither the maximum allowable turbine inlet temperature nor the maximum allowable turbine exhaust temperature is exceeded.
17.2.5
Combustion System Operating Precautions The operating personnel should be familiar with the following precautions, related to the gas turbine combustion system:
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1.
Sudden emission of black smoke from MS 5002 (C and D) units may indicate serious combustion difficulties. If black smoke develops suddenly:
a.
The unit should be immediately removed from service, and a combustion inspection performed.
2.
Adhere to the following procedures to reduce the possibility of outer combustion casing failure:
a.
During Operation - Exhaust temperatures are monitored by the SPEEDTRONIC control system. The temperature spread is compared to allowable spreads with alarms resulting if the allowable spread limits are exceeded.
b.
Planned Maintenance - Observe inspection intervals on combustion liners, transition pieces, and fuel nozzles.
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17.2.6 CAUTION:
Nuovo Pignone
3.
Operating a turbine with too many rejected control and overtemperature thermocouples increases the risk of turbine overfiring and prevents diagnosis of combustion problems by use of temperature differential readings. To avoid the above problems, the operator should keep the number of rejected exhaust thermocouples within following limits:
a.
Control Thermocouples Maximum two but no more than one of any three adjacent thermocouples.
Cooldown/Shutdown Precautions IN THE EVENT OF AN EMERGENCY SHUTDOWN IN WHICH INTERNAL DAMAGE OF ANY ROTATING EQUIPMENT IS SUSPECTED, DO NOT TURN THE ROTOR AFTER SHUTDOWN. MAINTAIN LUBE OIL PUMP IN OPERATION, SINCE LACK OF CIRCULATING LUBE OIL FOLLOWING A HOT SHUTDOWN WILL RESULT IN RISING BEARING TEMPERATURES, WHICH CAN RESULT IN DAMAGED BEARING SURFACES. IF THE MALFUNCTION THAT CAUSED THE SHUTDOWN CAN BE QUICKLY REPAIRED, OR IF A CHECK REVEALS NO INTERNAL DAMAGE AFFECTING THE ROTATING PARTS, REINSTATE THE COOLDOWN CYCLE (SEE PARA. 12.7). If there is an emergency shutdown and the turbine is not turned with the ratchet, one should note the following factors:
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a.
Within maximum 20 minutes following turbine shutdown, the gas turbine may be started. Use the normal starting procedure.
b.
Between the twenty-minute period mentioned above and a total of two hours after shutdown, rotor bowing will result in high vibration levels and rubbing that will prohibit startup of the turbine. Do not attempt any restart unless rotation has been performed for one to two hours minimum, so as to reduce rotor bowing.
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CAUTION:
NOTE:
Nuovo Pignone If the unit has been shut down and not turned at all, it must be shut down for approximately 24 hours before it can be restarted without danger of shaft bow.
WHERE THE GAS TURBINE HAS NOT BEEN ON COOLDOWN OPERATION AFTER SHUTDOWN AND A RESTART IS ATTEMPTED, AS UNDER CONDITIONS ABOVE, THE OPERATOR SHOULD MAINTAIN A CONSTANT CHECK ON VIBRATION VELOCITY AS THE UNIT IS BROUGHT UP TO ITS RATED SPEED. IF THE VIBRATION VELOCITY EXCEEDS 1.0 INCH PER SECOND AT ANY SPEED, THE UNIT SHOULD BE SHUT DOWN AND TURNED WITH THE RATCHET FOR AT LEAST ONE HOUR BEFORE A SECOND STARTING ATTEMPT IS MADE. IF SEIZURE OCCURS DURING THE RATCHET OPERATION OF THE GAS TURBINE, THE TURBINE SHOULD BE SHUT DOWN AND REMAIN IDLE FOR AT LEAST 30 HOURS, OR UNTIL THE ROTOR IS FREE. THE TURBINE MAY BE TURNED AT ANY TIME DURING THE 30-HOUR PERIOD IF IT IS FREE; HOWEVER, AUDIBLE CHECKS SHOULD BE MADE FOR RUBS. The vibration velocity must be measured at points near the gas turbine bearing caps.
17.3 PREPARATIONS FOR NORMAL LOAD OPERATION These preparations are described in more detail in the following paragraphs.
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17.4 STANDBY POWER REQUIREMENTS Standby AC power is required to ensure the immediate start-up capability of particular turbine equipment and related control systems when the start signal is given. The functions identified by an asterisk are also necessary for unit protection and should not be turned off except for maintenance work on that particular function: 1. Heating and circulating turbine lube oil at low ambient temperatures in order to maintain proper oil viscosity.
17.5 CHECKS PRIOR TO OPERATION The following checks are to be made before attempting to operate a new turbine or an overhauled turbine. It is assumed that the turbine has been assembled correctly, is in alignment and that calibration of the SPEEDTRONIC system has been performed for the Control Specifications (by G.E.). A standby inspection of the turbine should be performed with the auxiliary lube oil pump operating and emphasis on the following areas: 1. Check that all piping and turbine connections are securely fastened and that all blinds have been removed. Most tube fittings incorporate a stop collar, which ensures proper torquing of the fittings at initial fitting makeup and at reassembly. These collars fit between the body of the fitting and the nut and contact in tightening of the fitting. The stop collar is similar to a washer and can be rotated freely on unassembled fittings. During initial assembly of a fitting with a stop collar, tighten the nut until the collar cannot be rotated by hand. This is the inspection for a proper fitting: the nut should be tightened until the collar cannot be rotated. 2. Inlet and exhaust plenums and associated ducting are clean and rid of all foreign objects. All access doors are secure. 3. Where fuel, air or lube oil filters have been replaced, check that all covers are intact and tight.
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4. Verify that the lube oil tank is within the operating level and, if the tank has been drained, that it has been refilled with the recommended quality and quantity of lube oil. If lube oil flushing has been conducted, verify that all filters have been replaced and any blinds, if used, removed. 5. Check operation of auxiliary and emergency equipment, such as lube oil pumps, water pumps, etc. Check for obvious leakage, abnormal vibration, noise or overheating. 6. Check lube oil piping for obvious leakage. Using also the oil flow sights provided, check visually that oil is flowing from the bearing drains. The turbine should not be started unless flow is visible at each flow sight. 7. Check condition of all thermocouples on the C.R.T. Reading should be approximately ambient temperature. 8. Check spark plugs for proper arcing.
WARNING:
DO NOT TEST SPARK PLUGS WHERE EXPLOSIVE ATMOSPHERE IS PRESENT.
If the arc occurs anywhere other than directly across the gap at the tips of the electrodes or if, by blowing on the arc, it can be moved from this point, the plug should be cleaned, the tip clearance adjusted or, if necessary, replaced. Verify the retracting piston for free operation. 9. Devices requiring manual lubrication are to be properly serviced. 10. Determine that the cooling medium system has been properly flushed and filled with the recommended coolant. Any fine powdery rust, which might form in the piping during short time exposure to atmosphere, can be tolerated. If there is evidence of scaly rust, the cooling system should be power flushed until all scale is removed.
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If it is necessary to use a chemical cleaner, most automobile cooling system cleaners are acceptable and will not damage the carbon and rubber parts of the pump mechanical seals or rubber parts in the piping. 11. At this time, all annunciated ground faults should be cleared. It is recommended that units be not operated when a ground fault is indicated. Immediate action should be taken to locate all grounds and correct the problems.
17.6 CHECKS DURING START UP AND INITIAL OPERATION The following is a list of important checks to be made on a new or newly overhauled turbine with the various modes selected. It is recommended to review the Control Specifications - Operating Sequences prior to operating the turbine. When a unit has been overhauled, those parts or components that have been removed and taken apart for inspection/repair should be critically monitored during the unit startup and operation. This inspection should include: checks for leakage, vibration, unusual noise, overheating, and lubrication.
17.6.1
17.6.2
Crank 1.
Listen for rubbing noises in the turbine compartment. A sound-scope or some other listening type device is suggested. Shut down and investigate if unusual noise occurs.
2.
Check for unusual vibration.
Fire 1.
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Check the entire fuel system and the area immediately around the fuel nozzle for leaks. In particular, check for leaks at the following points:
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Turbine compartment a.
CAUTION:
Gas manifold and associated piping.
ELIMINATION OF FUEL LEAKAGE IS OF EXTREME IMPORTANCE AS A FIRE PREVENTIVE MEASURE.
17.6.3
2.
Use mirrors to view the sight ports in the combustion chambers to visually check that each chamber is fired and that the flame zone is centered within the liner. In addition, assure that the crossfire tube end is not glowing. Plug and stake sight ports once satisfactory flame conditions are obtained.
3.
Monitor the turbine control panel for unusual exhaust thermocouple temperature, wheelspace temperature, lube oil drain temperature, highest to lowest exhaust temperature spreads and “hot spots” i.e. combustion chamber(s) burning hotter than all the others.
4.
Listen for unusual noises and rubbing.
5.
Monitor for excessive vibration.
Automatic, Manual Allow the gas turbine to operate for a 30 to 60 minute period in a full speed, no load condition. This time period allows for uniform and stabilized heating of the parts and fluids. The tests and checks listed below are to supplement those also recorded in Control Specification - Control System Adjustments. Record all data for future comparison and investigation.
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1.
Continue monitoring for unusual rubbing noises and shut down immediately if noise persists.
2.
Monitor lube oil tank, header and drain temperatures continually during the heating period.
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Refer to the Schematic Piping Diagram - Summary Sheets for temperature guidelines. Adjust thermostatic valves (VTRs) as required. 3.
At this time, a thorough vibration check is recommended, using vibration test equipment (IRD Mechanalysis, Inc.) or equivalent with filtered or unfiltered readings. It is suggested that horizontal, vertical and axial data be recorded for: all accessible bearing covers on the turbine turbine forward compressor casing turbine support legs bearing covers on the load equipment.
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4.
Check and record wheelspace, exhaust and control thermocouples for proper indication on the CRT (VIDEO).
5.
Flame detector operation should be tested for the Control Specification Control System Adjustments.
6.
Utilize all planned shutdowns in testing the Electronic and Mechanical Overspeed Trip System for the Control Specifications - Control System Adjustments. Refer to Special Operations section of this text.
7.
Monitor CRT (VIDEO) display for proper operation.
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17.7 ROUTINE CHECKS DURING NORMAL OPERATION To be performed on a regular basis on the running machine.
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-
Oil level in the main reservoir.
-
Oil temperature in the main reservoir.
-
Oil temperature at the inlet and outlet of oil cooler (water or air).
-
Temperature in the lube oil header.
-
Temperature in the bearings.
-
Oil pressure downstream of the lube oil pumps.
-
Oil pressure in the lube oil header.
-
Oil pressure differential through lube oil filters.
-
Oil flow in the accessory gear, accessory coupling, load coupling, load gear and discharge from bearings through flow sight glasses (if applicable).
-
Air pressure at axial compressor discharge.
-
Differential oil pressure through hydraulic oil supply filters.
-
Oil pressure in the hydraulic oil supply header.
-
Oil pressure in the control oil header.
-
Fuel gas differential pressure through fuel gas filters.
-
Fuel gas pressure upstream of stop/ratio valve (SRV).
-
Fuel gas pressure downstream of stop/ratio valve (SRV) and upstream of gas control valve (GCV).
-
Fuel gas pressure in the fuel gas header.
-
H.P. rotor axial displacement.
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NOTE 1:
Nuovo Pignone
-
L.P. rotor axial displacement.
-
Journal bearing N. 1 radial vibrations.
-
Journal bearing N. 4 radial vibrations.
-
Turbine wheel space temperature 1st stage forward.
-
Turbine wheel space temperature 1st stage afterward.
-
Turbine wheel space temperature 2nd stage forward.
-
Turbine wheel space temperature 2nd stage afterward.
-
Flame look in the combustion chambers.
-
Smoke look at the exhaust duct outlet.
-
Unusual rotor noises or rubbings.
-
Air temperature in the inlet duct.
-
Air temperature at the axial compressor discharge.
-
Turbine temperature in the exhaust duct.
-
Periodically operate the transfer valve of the lube oil filters.
-
Periodically operate the hydraulic oil supply filter transfer valve.
-
Periodically take oil samples from the main reservoir for analysis. The operation data not automatically recorded by the instruments shall be indicated in the log data sheet. All data recorded by the instruments or stated in the log sheet by the operator are of no use if they are not compared with the data read previously and if no immediate steps, when necessary, are taken.
NOTE 2:
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Operating reliability should improve if the User’s personnel receive specific training by attending training courses held by Nuovo Pignone at Nuovo Pignone’s or at the User’s shop.
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