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INSTRUCTION , OPERATION AND
MAINTENANCE MANUAL
(MS5002D)
Volume I
Description & Operation
NUOVO PIGNONE JOB : 160.5810÷16
CUSTOMER : MEHRAS
N.P. SERIAL NUMBER : G06887÷89-G06921-G06868÷70
SERVICE : TURBOCOMPRESSION
PLANT LOCATION : AGHAJARI
NAME OF PLANT : AGHAJ.GAS INJ.PLANT
MANUFACTURER : GEPS Oil & Gas Nuovo Pignone Via F. Matteucci, 2 50127 Florence - Italy Telephone (055) 423211 Telefax (055) 4232800
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I INNSSTTRRUUCCTTIIOONNSSMMAANNUUAALL S Sttaattuussaannddddeessccrriippttiioonnoofftthheerreevviissiioonnss Stato di revisione Revision Status Data Date Eseguito Prepared Controllato Checked Approvato ApprovedDescrizione della revisione
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 es sere 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.
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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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After Sales Service
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 &
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Job: 160.5810÷16 I N D E X Page 1. CONTENTS ... 1-1 1.1 INTRODUCTION ... 1-11.2 EQUIPMENT DATA SUMMARY... 1-3
1.3 PERFORMANCE CURVE... 1-7
1.4 RECEIVE STAGE EQUIPMENT... 1-8
1.5 INSTALLATION... 1-9
1.6 TURBINE TWO SHAFT DIAGRAM... 1-19
2. DESCRIPTION... 2-1
2.1 GENERAL... 2-1
2.2 TURBINE BASE... 2-1
2.3 TURBINE SUPPORTS ... 2-2
2.4 ACCESSORY BASE AND SUPPORTS ... 2-3
3. COMPRESSOR SECTION ... 3-1 3.1 GENERAL ... 3-1 3.2 COMPRESSOR ROTOR ... 3-1 3.3 COMPRESSOR STATOR... 3-2 3.4 INLET CASING... 3-2 3.5 COMPRESSOR CASING... 3-3
3.6 COMPRESSOR DISCHARGE CASING... 3-3
4. DCOMBUSTION SECTION ... 4-1
4.1 GENERAL ... 4-1
4.2 COMBUSTION WRAPPER (SHORT) ... 4-1
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Page 5. TURBINE SECTION ... 5-1
5.1 GENERAL ... 5-1
5.2 TURBINE STATOR ... 5-1
5.3 FIRST STAGE NOZZLE ... 5-2
5.4 SECOND STAGE NOZZLE... 5-2
5.5 DIAPHRAGM ASSEMBLY ... 5-3
5.6 TURBINE ROTOR AND WHEELS ... 5-3
6. BEARINGS ... 6-1
6.1 GENERAL ... 6-1
6.2 LUBRICATION... 6-2
6.3 G.E BEARING PUBLICATION... 6-3
7. GEARS ... 7-1
7.1 ACCESSORY GEAR ASSEMBLY ... 7-1
8. COUPLING... 8-1
8.1 GENERAL ... 8-1
8.2 CONTINUOUSLY LUBRICATED ACCESSORY GEAR
COUPLING... 8-2
8.3 CONTINUOUSLY LUBRICATED LOAD COUPLING... 8-2
8.3A NON LUBRICATED LOAD COUPLING... 8-2
8.4 LUBRICATION... 8-2
8.5 TOOTHWEAR ... 8-3
9. INLET AND EXHAUST SYSTEM ... 9-1
9.1 GENERAL ... 9-1
9.2 AIR INLET ... 9-1
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9.4 INLET DUCTING AND SILENCING... 9-2
9.5 EXHAUST SYSTEM AND SILENCER... 9-3
9.6 EXHAUST PLENUM ... 9-3
9.7 VENTILATION SYSTEM... 9-3
10. STARTING SYSTEM (ELECTRIC STARTING MOTOR)... 10-1
10.1 GENERAL ... 10-1
10.2 FUNCTIONAL DESCRIPTION ... 10-1
10.3 START-UP FUNCTIONS AND SEQUENCES... 10-2
10.4 TORQUE CONVERTER ASSEMBLY ... 10-2
10.5 HYDRAULIC RATCHET SYSTEM... 10-3
10.6 RATCHET SYSTEM OPERATION... 10-3
10.7 STARTING JAW CLUTCH ... 10-4
11. GAS FUEL SYSTEM ... 11-1
11.1 GENERAL ... 11-1
11.2 FUNCTIONAL DESCRIPTION ... 11-2
11.3 GAS STOP/RATIO AND CONTROL VALVE... 11-3
11.4 GAS STRAINERS ... 11-3
11.5 PROTECTIVE DEVICES ... 11-4
11.6 OFF-BASE FUEL GAS SKID... 11-5
12. LUBE OIL SYSTEM ... 12-1
12.1 GENERAL ... 12-1
12.2 FUNCTIONAL DESCRIPTION ... 12-1
12.3 LUBE OIL TANK AND PIPING ... 12-2
12.4 LUBE OIL PUMPS... 12-3
12.5 MAIN LUBE OIL PUMP ... 12-3
12.6 AUXILIARY LUBE OIL PUMP... 12-3
12.7 EMERGENCY LUBE OIL PUMP... 12-4
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12.9 LUBE OILTEMPERATURE CONTROL ... 12-7
12.10 OIL FILTERS ... 12-8
12.11 PRESSURE AND TEMPERATURE PROTECTIVE DEVICES ... 12-9
12.12 HYDROCARBON BASE LUBRICATING OIL
RECOMMENDATIONS FOR GAS TURBINE SOM 17366/4 ... 12-11
12.13 COOLER(S) ... 12-12
12.14 LUBE OIL VAPOUR SEPARATOR... 12-12
13. HYDRAULIC SUPPLY SYSTEM ... 13-1
13.1 GENERAL ... 13-1
13.2 FUNCTIONAL DESCRIPTION ... 13-1
14. CONTROL AND TRIP OIL SYSTEM ... 14-1
14.1 GENERAL ... 14-1
14.2 FUNCTIONAL DESCRIPTION ... 14-1
14.3 SECOND STAGE NOZZLE CONTROL... 14-2
14.4 INLET GUIDE VANE CONTROL ASSEMBLY ... 14-4
15. COOLING AND SEALING AIR SYSTEM ... 15-1
15.1 GENERAL... 15-1
15.2 TENTH STAGE EXTRACTION AIR... 15-1
15.3 COMPRESSOR HIGH PRESSURE SEAL LEAKAGE AIR ... 15-2
15.4 AIR EXTRACTION FOR START-UP AND SHUT-DOWN
AXIAL COMPRESSOR PULSATION PROTECTION... 15-2
16. FIRE PROTECTION SYSTEM (CO2) ... 16-1
16.1 GENERAL ... 16-1
16.2 FUNCTIONAL DESCRIPTION ... 16-1
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17. OPERATION ... 17-1
17.1 OPERATOR RESPONSIBILITY ... 17-1
17.2 GENERAL OPERATING PRECAUTIONS ... 17-1
17.3 PREPARATIONS FOR NORMAL LOAD OPERATION ... 17-7
17.4 STANDBY POWER REQUIREMENTS ... 17-8
17.5 CHECKS PRIOR TO OPERATION ... 17-8
17.6 CHECKS DURING START UP AND INITIAL OPERATION ... 17-10
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1. 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 filtra-tion system attenuates the high frequency noise and an inertial air separator re-moves 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 first-stage 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 pressure-lubricated 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 four-bearing 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 continu-ous inside the chambers). The hot gases increase the speed of the compres-sor/high pressure turbine rotor. This, in turn, increases the compressor dis-charge 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, ex-pand first through the high-pressure turbine, then through the low-pressure tur-bine 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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1.2 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, self- retracting
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
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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,
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1.3 PERFORMANCE CURVE
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1.4 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 pro-tection 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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1.5 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
par-allelepiped 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 counter-weights. 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
lev-els 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
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1.5.1.8 Wait for the cement to shrink following the standard procedures
con-cerning cement castings in relation to ambient temperature and humidity. If using different or accelerating cements, the civil works building man-agement 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 pre-sent 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
sub-plates, removing any traces of cement, oxide, etc., then remove the level-ing 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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1.5.2 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
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NOTES
A) Before loading the subplates with the static weight of the turbine, the
ce-ment 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 mate-rial 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 position-ing operation.
1.5.3 Positioning the gas turbine base on the foundations 1.5.3.1 Preparing the foundation
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
indi-cated on the foundation drawing (take into account the thickness of spherical washers and the differences result-ing from the check described at para. 1.5.1).
1.5.4 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.
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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- Standard-cement casting after positioning the
an-chor bolts.
**** FIGURE 1-3- Subplate and sleeve casting, with unshrinking
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- FOUNDATION KIT - 1 - ANCHOR BOLT 2 - SLEEVE 3 - ANCHOR SUBPLATE 4 - SPHERICAL WASHER 5 - SHIM PACK6 - BACKING PLATE FOR LIFTING SCREW 7 - TURBINE BASE
8 - WASHER 9 - KEEP PLATE 10 - LIFTING SCREW
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FIGURE 1
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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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FORM TO BE USED FOR THE DIMENSIONAL CHECK OF AN-CHOR BOLTS BY DIAGONALS
NOTE: THE ELEVATED LEVEL VALUE OF THE ANCHOR BOLTS RE-FERRED TO THE PLANT'S "0" POINT WILL BE PROVIDED BY THE CUSTOMER TYPICAL DRAWING A. _____________ A1. _____________ Y. _________ B. _____________ B1. _____________ X. _________ C. _____________ C1. _____________ D. _____________ D1. _____________ (Y-X) Subplates E. _____________ E1. _____________ without anchor F. _____________ F1. _____________ bolts
G. _____________ G1. _____________ H. _____________ H1. _____________
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1.6 TWO-SHAFT TURBINE DIAGRAM (SYMPLE CYCLE)
FIGURE 1-6
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2. 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 in-formation 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 for-ward 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.
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The left and right longitudinal I-beams and the forward and aft cross members of the tur-bine baseare fabricated along the webs. They form lube oil drain channels for the turtur-bine 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 per-mit vertical expansion of the exhaust frame. In this arrangement, there is a lon-gitudinal fixed point of the turbine from which it can thermally expand forward and aft.
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2.4 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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3. COMPRESSOR SECTION
3.1 GENERAL
The axial flow compressor section consists of the compressor rotor and casing. It in-cludes 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 ex-tracted 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 airfoil-shaped, 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 con-trol. 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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3.3 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 re-spect 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 as-sembly. 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 (pulsa-tion).
Hydraulic oil is utilized to activate the inlet guide vanes through a large ring gear and mul-tiple 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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3.5 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 tur-bine 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 up-per 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 ro-tor. They are the primary load bearing members in this portion of the gas turbine staro-tor. 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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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 com-posed of simple blades installed in dovetail grooves machined in the wall of the compres-sor 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 cas-ing.
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FIG. 3.2 - MODEL 5002 COMPRESSOR CASING AND H.P. TURBINE ROTOR ASSEMBLY
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4. 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 compres-sor (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 cas-ing. 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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4.3 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 be-tween 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 4-2).
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 re-maining chambers are without spark plugs and are fired with flame from the fired chambers through interconnecting crossfire tubes.
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4.3.2 Ultraviolet flame detectors
During the starting sequence, it is essential that the control system receive an in-dication of the presence or absence of flame.. For this reason, a flame moni-toring 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 volt-age, 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 cir-cuit, which activates the electronics to give an output defining flame. Con-versely, 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 de-tector sensor senses a loss of flame, the control circuitry will cause an annuncia-tion of this condiannuncia-tion only.
For detailed operating and maintenance information covering this equipment, refer to the Component Description following this gas turbine text.
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4.3.3 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 noz-zles tip.
The liner cap imparts a swirl to the combustion air, which results in more com-plete 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 un-fired chambers.
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FIG. 4-1 - AIR & GAS FLOW THROUGH COMBUSTION SECTION OF SIMPLE CYCLE GAS TURBINE
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FIG. 4-1a - COMBUSTION WRAPPER, COMPRESSOR DISCHARGE CASING & NO. 2 BEARING ASSEMBLY
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5. TURBINE SECTION
5.1 GENERAL
In the turbine section, the high-temperature gases from the combustion section are con-verted into shaft horsepower. This section comprises the following components: the tur-bine shell, the first-stage nozzle, the first-stage turtur-bine wheel, referred to as high-pressure turbine, the second-stage variable vane nozzle and the second-stage turbine wheel, re-ferred to as low-pressure turbine. In addition, the section includes the diaphragm as-sembly, 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 vari-able-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 radi-ated 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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5.3 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 noz-zle assembly and the arrangement of its support inside the casing are designed to ac-commodate 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 be-tween 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. Com-pressor 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 vari-able-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 mini-mum clearances between the partitions and the shrouds when the turbine is at operating temperature (see Fig. 5.3).
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5.5 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 second-stage 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 ther-mocouple leads protrude outside the turbine through one of the hollow support pins.
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5.6 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 in-dependent 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, assem-bled 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 con-trol system mechanically in case of overspeed. The rotor assembly is balanced previ-ously 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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FIG. 5.4 - VIEWS OF LOW-PRESSURE (LOAD) TURBINE ROTOR ASSEMBLY
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6. 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 com-pressor inlet casing; No. 2 in the comcom-pressor 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 bear-ing types used in the different locations of the gas turbine. The instructional bulletins, re-ferred 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
Thrust (active)
Tilting pad (six pads)
Self-equalizing GEI-41018B
Thrust (inactive)
Tapered land
GEI-41019B
2 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 GEI-41018B
Thrust Tilting-pad (four pads)
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6.2 LUBRICATION
One lube oil header supplies lube oil for pressure lubrication of all main gas turbine bear-ings. This header is contained inside the lube oil tank, which is fabricated in the acces-sory 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 I-beam 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 re-turns 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 pres-sure. 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 thermo-couples provide for indication of oil temperature on the temperature indicator in the tur-bine control panel. The lube oil system is shown on the Schematic Piping Diagram in the “Reference Drawings” volume.
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6.3 G.E. BEARING PUBLICATIONS
GEI-41018B GEI-41019B GEI-41020C GEK-28100
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7. 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 exte-rior 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 pre-scribed (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 sup-ply 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 acces-sory 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. Addi-tional 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.
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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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8. 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
exces-sive 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
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8.2 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 shrink-fitted and keyed to the accessory gear shaft. The sleeve at the turbine end is bolted di-rectly 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 pro-vide support for the flexible diaphragms. The diaphragm sections propro-vide 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 tur-bine 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 nor-mal conditions of operation, the rate of wear will be snor-mall.
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 mis-alignment. 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 cou-pling teeth.
Corrosive wear is indicative of lubricant contamination or highly active additives. Sur-face fatigue, characterized by the removal of metal and the formation of cavities, may in-dicate torsional oscillations in the coupled system.
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9. 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 sys-tem, 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 si-lencing equipment; the compartment and ducting are connected to the turbine inlet ple-num 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 tur-bine 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 pro-tective corrosion preventive primer.