Gas Turbine Operation

g

_{GE Energy Services}

MS9001EA Gas Turbine

Operations Training Manual

ENEL

Ras Laffan, Qatar

Turbine Numbers T9E152, T9E154, T9E155 & T9E160 Tab 1 Gas Turbine Overview

MS9001EA Gas Turbine Functional Description 9E Description

MS9001E Gas Turbine Fundamentals A00203

MS9001EA Cross Section 9001E Cross

Section Tab 2 MS6001B Gas Turbine Unit Description

Gas Turbine Arrangement (ML 0406) 91-104E8224 Gas Turbine Compressor Rotor Assembly 9EA CPSR

Gas Turbine, Turbine Rotor Assembly 9EA TURB

Variable Inlet Guide Vane Arrangement (ML 0811) 91-172D7245

First-Stage Nozzle 9EA NZ1

Second-Stage Nozzle 9EA NZ2

Third-Stage Nozzle 9EA NZ3

No 2 Bearing Arrangement 9EA BRG2

Turbine Control Device System Description (Typical) A00079 Schematic Diagram – Turbine Control Devices (ML 0415) 356B2601 Tab 3 Inlet and Exhaust Systems

System Description (Typical) AEIS 5166

Schematic Diagram – Inlet and Exhaust Flow (ML 0471)

(Typical) 351B7195 Schematic Diagram – Inlet Air Heating (ML 0432) 239C7268 Tab 4 Lubricating Oil System

System Description LubeOil

Schematic Diagram – PP Lube Oil (ML 0416) 202D8427 Tab 5 Hydraulic Supply System

System Description HydOil

Schematic Diagram – PP Hydraulic Supply (ML 0434) 356B2725 Tab 6 Trip Oil System

System Description TripOil

Schematic Diagram – PP Trip Oil 91-316352 Tab 7 Gas Fuel System

Fuel Gas Control System GASSTD00

Schematic Diagram – PP Fuel Gas (ML 0422) 356B2265 Schematic Diagram – PP Fuel Purge (ML 0477) 91-315296

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_{GE Energy Services} Tab 8 Cooling and Sealing Air System

System Description CoolSeal

Schematic Diagram – PP Cooling and Sealing Air (ML 0417) 239C7408

Turbine Cooling Arrangement 9EA Turbine

Cooling Tab 9 Cooling Water System

Cooling Water System Description CoolWater

Schematic Diagram – PP Cooling Water (ML 0420) 360B1319 Tab 10 Compressor Water Wash System

Compressor Water Wash System Description WW5146 Schematic Diagram – PP Wash System (ML 0442) 356B2267

Gas Turbine Compressor Washing GEK 110220A

Field Performance Testing GEK 28166A

Tab 11 Starting System

System Description (Typical) SS0418

Schematic Diagram – Starting Means (ML 0421) 356B2630 Tab 12 Inlet Guide Vane Control System

Guide Vane Control System Description GEK106910 Schematic Diagram – IGV (ML 0469) 91-242B9854 Tab 13 Heating and Ventilating System

System Description VH5166

Schematic Diagram – Heating and Ventilation (ML 0436) 91-313088 Tab 14 Fire Protection System

Fire Protection System Description FP5166

Schematic Diagram – Fire Protection System (ML 0426) 356B2647 Schematic Diagram – Gas Detection (ML 0474) 91-317644 Tab 15 SPEEDTRONICTM _{Mark V Control}

Control Hierarchy 91-318940

Gas Turbine Operator Commands A00052A

Fundamentals of Mark V Control System A00023A

Mark V Turbine Control System GER 3658D

Turbine Control Users Manual GEH 5979D

SPEEDTRONICTM Mark V Annunciator Troubleshooting Chart GEK 107359

Tab 16 Gas Turbine Operation

GE Gas Turbine Performance Characteristics GER 3567H

Unit Operation / Turbine UOGTNODLN1

Tab 17 Reference Drawings

Device Summary (ML 0414) 372A8094

Piping Symbols 277A2415G

Glossary of Terms C00023

Basic Device Nomenclature A00029B

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1 GAS TURBINE FUNDAMENTALS

A00203

GAS TURBINE FUNDAMENTALS

Figure 1 Model Series 9001E

Simple-Cycle, Single-Shaft Heavy-Duty Gas Turbine

id0002

GENERAL

Figure 1 depicts a General Electric simple–cycle single–shaft, heavy–duty gas turbine. It is an inter-nal combustion engine which produces energy through a cycle similar to the Otto or Diesel cycles in that the three cycles consist of the same four stages: compression, combustion, expansion, and exhaust. There are, however, differences in the details of the three cycles which are worth examining.

The Otto Cycle

In the Otto Cycle, Figure 2, the compression stroke (from 1 to 2) is followed by combustion of constant volume (2 to 3) resulting in increased pressure. The pressure causes expansion (3 to 4) with exhaust tak-ing place between points 4 and 1.

3 2 1 4 P = PRESSURE V = VOLUME V P

Figure 2 Otto Cycle

id0021

The Diesel Cycle

The Diesel Cycle, Figure 3, is similar, except that combustion takes place at a constant pressure (2–3). This is accomplished by injecting fuel at a rate suffi-cient to compensate for the volume change. Expan-sion and exhaust then take place as it does in the Otto Cycle.

Figure 3 Diesel Cycle

3 2 1 4 P = PRESSURE V = VOLUME V P id0022

The Brayton Cycle

In both the Otto and Diesel cycles a loss occurs due to the pressure drop involved in the exhaust stroke. This loss is avoided by creating a cycle in which the exhaust stroke is longer than the compression stroke, thus allowing the working fluid to be ex-panded to atmospheric pressure. Such a cycle has been devised, and is called a Brayton Cycle (Figure 4). It is also called a Constant Pressure Cycle since combustion and exhaust both take place at constant

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GAS TURBINE FUNDAMENTALS A00203

pressure. When the Brayton Cycle is worked out for a steady–flow process, we have the simple gas tur-bine cycle. 3 2 1 4 P = PRESSURE V = VOLUME V P

Figure 4 Brayton Cycle

id0010

In the simple gas turbine cycle, combustion and ex-haust occur at constant pressure and compression and expansion occur continuously, rather than inter-mittently as in the Otto or Diesel cycles. This means that gas turbine power is continuously available, whereas in a reciprocating engine power takeoff is available only on the expansion stroke. Figure 5 schematically represents the hardware necessary for the cycle. The points on Figures 4 and 5 are consis-tent. At point 1, air enters the compressor (c). The high pressure compressor discharge air at point 2 is mixed with fuel in the burner (b). The product of this continuous combustion at point 3 enters the turbine (t), and is expanded to atmospheric pressure (point 4). The turbine provides the horsepower to drive the compressor and load (in this case, a generator).

GEN FUEL AIR 2 3 4 c t b c = COMPRESSOR b = BURNERS t = TURBINE 1

Figure 5 Fundamental Gas Turbine

id0017

GENERAL DESCRIPTION

The Model Series 9001E gas turbine is a 3000–rpm, single–shaft, simple–cycle power package that basi-cally requires only fuel and fuel connections, gener-ator breaker connections, and an AC–power source for turbine start–up. The MS9001E is also available in a combined–cycle configuration for applications utilizing a Heat Recovery Steam Generator or simi-lar device.

GAS TURBINE UNIT

The gas turbine unit consists of a 17–stage axial– flow compressor and a 3–stage power turbine. Each section, compressor rotor and turbine rotor, is as-sembled separately and then joined together. Through–bolts connect the compressor rotor wheels to the forward and aft stubshafts. The turbine rotor also utilizes through–bolt construction with spacer wheels between the first– and second–stage and the second– and third–stage wheels.

The assembled rotor is a three–bearing design utiliz-ing pressure–feed elliptical and tilt–pad journal bearings. The three–bearing design assures that ro-tor–critical speeds are above the operating speed and allows for optimum turbine bucket/turbine shell clearances.

TURBINE COMPONENTS –

OVERVIEW

The major components of the gas turbine are the ro-tor components, primarily the axial flow compres-sor and the turbine wheels; the stationary components, primarily the compressor casings, tur-bine shell, and nozzles; and the combustion compo-nents.

Casings

The casings make up the structural backbone of the gas turbine. This structure supports the rotating

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3 GAS TURBINE FUNDAMENTALS

A00203

ments through its bearing housings, functions as a pressure vessel to contain the turbine’s working fluids of compressed air and combustion gases, and provides a surface of revolution for the blading to operate while maintaining minimum radial and axial clearance and, therefore, optimum performance.

Compressor

The function of the axial flow compressor is to fur-nish high pressure air to the combustion chambers for the production of the hot gases necessary to oper-ate the turbine. Since only a portion of its output is used for combustion the compressor also serves as a source of cooling air for the turbine nozzles, turbine wheels, transition pieces, and other portions of the hot–gas path.

Air enters the inlet of the multistage compressor where it is compressed from atmospheric pressure to approximately 8.95 to 12.92 bar (130 to 185 psig), depending on frame size. This gives a Compressor Pressure Ratio of approximately 10:1 to 13.5:1,

C.R.+Atmos Press) Compressor Disch Pressure (Atmospheric Pressure)

again dependent on frame size. The air which con-tinuously discharges from the compressor will occupy a smaller volume at the compressor dis-charge than at the inlet and, due to heating during compression, will have a temperature of 315°C to 360°C (600°F to 680°F).

Turbine

The turbine wheels are an area of primary impor-tance because they are the point at which the kinetic energy of the hot gases is converted into useful rota-tional, mechanical energy by the turbine buckets. This produces the power necessary to meet the load requirements and drive the axial–flow compressor.

Nozzles

General Electric turbines are of the impulse or high– energy stage design (i.e., pressure and heat conver-sion in the nozzle). The high pressure drop across the nozzle imparts a high velocity (kinetic energy) to the combustion gases. This energy is directed to the buckets which use this energy to rotate the shaft, driving the axial compressor and load.

Combustion System

The overall function of the combustion system is to supply the heat energy to the gas turbine cycle. This is accomplished by burning fuel mixed with com-pressor discharge air. The combustion gases are then diluted with excess air to achieve the desired gas temperature at the inlet of the first–stage turbine nozzle.

The combustion system consists of a number of sim-ilar combustion chambers. Compressor discharge air is distributed to these chambers where it is bled into a cylindrical combustion liner. Fuel is injected into the forward end of the liners where it mixes with the compressor discharge air and combustion takes place, thereby creating hot gases with temperatures in excess of 1650°C (3000°F) in the flame zone. As well as being used for combustion, the relatively cool compressor discharge air acts as a blanket to protect the liners from the heat of combustion. In addition to cooling the combustion liners, compres-sor discharge air mixes with the combustion gases downstream of the combustion reaction zone, cool-ing and dilutcool-ing the gases which now pass through transition pieces to the turbine first–stage nozzle. The amount of air necessary to cool the liner wall and dilute the hot gas to the temperature desired at the first–stage nozzle is about four times that re-quired for complete combustion; this “excess air” in the turbine exhaust makes it possible to install auxil-iary burners in a Heat Recovery Steam Generator if so desired.

The schematic operation of the single–shaft simple– cycle gas turbine may be seen in Figure 6.

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GAS TURBINE FUNDAMENTALS A00203

Figure 6 Simple–Cycle Gas Turbine Operation

TORQUE OUTPUT TO DRIVEN ACCESSORIES TORQUE INPUT FROM STARTING DEVICE ATMOSPHERIC AIR COMPRESSOR FUEL ROTOR COMBUSTION CHAMBER HOT GASES EXHAUST TORQUE OUTPUT TO DRIVEN LOAD TURBINE COMPRESSED AIR IGNITION (FOR STARTUP) id0020

GE Power Systems

1 TURBINE CONTROL DEVICES C00079

TURBINE CONTROL DEVICES

MS7001EA

GENERAL DESCRIPTION

The turbine control devices are all of the control

components, sensors, and transducers used to

monitor and control the operation of the

flange-to-flange gas turbine. The devices are located in

the inlet and exhaust plenums and mounted on

the gas turbine unit, with functions including

the following:

a. temperature measurement

b. vibration detection

c. speed measurement

d. flame detection

e. combustion ignition

FUNCTIONAL DESCRIPTION

Inlet Plenum

The devices mounted in the forward wall of the

in-let plenum are the compressor inin-let temperature

thermocouples (CT–IF–1, 2), and are used as an

in-dication of the ambient temperature to the

com-pressor inlet.

Exhaust Plenum

The devices mounted in the exhaust plenum are the

turbine exhaust control and protection

thermocou-ples (TT–XD–1 thru 18), and the primary function

is to provide turbine exhaust temperature

measure-ments 360

°

around all ten (10) combustors.

Se-lected groupings of six (6) thermocouples are wired

to the three (3) <RST> controllers in the

Speedtron-ic control panel to provide temperature inputs to the

combustion monitor and exhaust temperature

con-trol, alarm, and trip functions.

Flange–to–Flange Gas Turbine

The remaining devices mounted on the turbine

it-self are grouped in the following categories:

Bearing Vibration Detection – using

veloc-ity (seismic) type sensors:

#1 Bearing Housing – (39V–1A, 1B)

#2 Bearing Housing – (39V–2A)

#3 Bearing Housing – (39V–3A, 3B)

These devices function are to monitor and protect

the turbine rotor and bearings from excessive

vibration and damage.

Turbine Shaft Speed Detection – using

magnetic type pickups:

Forward Compressor Stub Shaft –

(77NH–1, 2, 3)

This function is to provide a speed signal reference

for the Speedtronic controls during start–up,

load-ing, and shutdown of the turbine unit.

Temperature Detection – using precision

thermocouples:

Compressor discharge – (CT–DA–1, 2)

This function provides a compressor discharge

temperature corrected reference for Pcd bias

con-trol during IGV operation and speed concon-trol.

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TURBINE CONTROL DEVICES C00079

Turbine Wheelspaces as:

First stage aft outer (TT–WS1AO–1, 2)

First stage forward inner (TT–WS1FI–1, 2)

First stage forward outer (TT–WS1FO–1, 2)

Second stage aft outer (TT–WS2AO–1, 2)

Second stage forward outer (TT–

WS2FO–1, 2)

Third stage aft outer (TT–WS3AO–1, 2)

Third stage forward outer (TT–

WS3FO–1, 2)

Turbine inner barrel (TT–IB–1)

This function is to protect the turbine hot section

parts such as nozzles, buckets, and wheels from

damage due to excessive temperatures during

start–up, normal operation, and shutdown.

Flame Detection–using ultraviolet radiation

type sensors:

flame detectors (28FD–2, 3, 7, 8) in

com-bustors # 2, 3, 7, 8

This function is to indicate the presence of flame in

the combustors during turbine start–up and normal

operation.

Combustion Ignition–using devices as:

spark plugs (95SP–1, 10) in combustors #

1 & 10

ignition transformers (95TR–1, 10)

mounted on turbine base

This function is to light–off the combustors and

es-tablish combustion during turbine start–up.

SPECIAL CUSTOMER OPTIONS

Bearing Vibration Monitoring – using

prox-imity (non–contacting) type position sensors:

#1 Bearing Housing – (39VS–11, 12)

[ra-dial] & (96VC–11, 12) [axial]; (77RP–11)

[key phasor]

#2 Bearing Housing – (39VS–21, 22, 23,

24) [radial]

#3 Bearing Housing – (39VS–31, 32)

[radial]

Bearing Metal Thermocouples

The turbine unit journal and thrust bearings are

equipped with bearing metal thermocouples

em-bedded into the bearing babbitt metal with the

function to monitor the “actual” bearing

tempera-tures during operation and give an alarm

indica-tion if the metal temperature is too high. This

function is to protect the turbine bearings and

ro-tor journal surfaces from overheating and failure

(i.e. “wiped”). The thermocouples are placed in

the following locations:

#1 main journal bearing – (BT–J1–1A, 1B,

2A, 2B)

#2 main journal bearing – (BT–J2–1A, 1B,

2A, 2B)

#3 main journal bearing – (BT–J3–1A, 1B,

2A, 2B)

Thrust Bearing – Active Lands – (BT–

TA1–1A, 1B, 2A, 2B)

Thrust Bearing – Inactive Lands – (BT–

TI1–1A, 1B, 2A, 2B)

Turbine Performance Monitor

The compressor inlet bellmouth area has total

pres-sure probes included as well as an RTD mounted to

monitor the compressor performance during

tur-bine unit operation. The compressor inlet pressure

and temperature values must be measured in order

to perform this function. The system includes the

following equipment:

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3 TURBINE CONTROL DEVICES C00079

b. Total and static pressure probes

c. Performance monitor manifold with valving

& condensate drain traps

d. Pressure transducers to measure:

inlet air total pressure (96CS)

bellmouth differential pressure (96BD)

barometric pressure (96AP)

compressor discharge pressure (96CD–2)

exhaust pressure (96EP)

inlet filter differential pressure (96TF)

The above pressure transducers are mounted on the

performance monitor manifold, that is located off–

base in close proximity to the turbine compartment

inlet and exhaust plenums. The pressure sensing

lines are run from the plenums to the monitor

man-ifold connections for the transducers.

General Electric Company One River Road

Schenectady, NY 12345

GE Power Systems Training

GE Power Systems

4

GE Power Systems

Gas Turbine

AIES5166

August 1996

These instructions do not purport to cover all details or variations in equipment nor to provide for every possible contingency to be met in connection with installation, operation or maintenance. Should further information be desired or should particular problems arise which are not covered sufficiently for the purchaser’s purposes the matter should be

referred to the GE Company.

_

1994 GENERAL ELECTRIC COMPANY

Inlet and Exhaust Systems

I. INTRODUCTION

Gas turbine performance and reliability are 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 filter out contaminants. It is the function of the air inlet system with its specially designed equip-ment and ducting to modify the quality of the air under various temperature, humidity, and contamination situations and make it more suitable for use in the unit.

Hot exhaust gases produced as a result of combustion in the turbine are cooled and attenuated in the exhaust system ducting before being released to atmosphere. These exhaust emissions must meet certain environ-mental standards of cleanliness and acoustic levels depending on site location.

The noise generated during gas turbine operation is attenuated by means of absorptive silencing material and devices built into the inlet and exhaust sections which dissipate or reduce the acoustical energy to an accept-able level.

II. AIR INLET SYSTEM A. General

The air inlet system consists of a multi–stage filter house and support structure, inlet ducting system, and inlet plenum leading to the compressor section of the turbine.

Inlet air enters the inlet compartment and flows through the ducting, with built–in acoustical silencer and trash screen, to the inlet plenum and then into the turbine compressor. The elevated intake arrangement provides a compact system and minimizes the pickup of dust concentrated in the air near the ground. All external and internal surface areas of the inlet system are stainless steel or coated with a protective corrosion inhibiting primer or galvanized for corrosion protection.

The general arrangement of the inlet compartment with respect to the gas turbine inlet plenum is shown on the mechanical outline drawing in the Outlines and Diagrams tab of this manual.

System Description

Gas Turbine

2

B. Inlet Compartment Description

The inlet filtration compartment and its integrated support structure sit on a separate foundation just up-stream of the control compartment. The system has been sized for additional airflow due to the use of filtered air for compartment pressurization and exhaust frame cooling. The compartment has two–sided, arrowhead design feeding a clean air plenum. The clean air plenum has an aft outlet flange which con-nects to the inlet ducting.

The inlet filter compartment contains three stages of inlet air filtration. The first stage consists of a mois-ture separator. The second and third stages consist of a pre–filter and a high efficiency filter respectively.

C. Inlet Air Treatment Equipment

1. Weather Hoods

The air intakes at each end of the compartment are fitted with large weather hoods. These hoods minimize the ingestion of water into the inlet compartment during rainy conditions.

2. Moisture Separator

The moisture separator is a PVC drift eliminator designed to eliminate 90% of 50 micron particles and above. This stage uses a series of bends in the flow path to coalesce the moisture from the flow. It is positioned such that water droplets will form and roll down the weather hoods.

3. Pre–Filter

The pre–filters are installed directly in front of the high efficiency filters. They are a low grade syn-thetic material designed to remove large particles and resist the effects of moisture. This extends the life of the final filter. The pre–filter is typically replaced three or four times before a high effi-ciency filter.

4. High–Efficiency Filters

The high–efficiency barrier filters use a special media to achieve good collection efficiency for all particles, including those smaller than 1 micron. The panel filters contain a depth loading media. Particles are actually trapped within the body of the media itself.

High–efficiency filters have an initial pressure drop which depends upon their construction, instal-lation and the quantity of air passed through each filter element. Filters normally use pleated media in order to increase the available surface area; this decreases pressure drop and increases dust hold-ing capacity. As dust is accumulated, pressure drop rises. The rise is relatively slow at first, but in-creases more rapidly as the filter nears the end of its useful life. A typical design would have a new and clean pressure drop of about an inch of water; the final pressure drop depends upon a trade off between filter life and gas turbine performance. General Electric recommends a final pressure drop of 2.5 inches of water as a good compromise for panel filters.

D. Operation and Maintenance

For additional information on the operation and maintenance of the inlet filtration system, refer to the manufacturer’s operation and maintenance manual contained in this section. If specific recommended maintenance and inspection schedules are not included as part of the manufacturer’s manual, refer to the section on Inlet Air System Maintenance in the Inspection and Maintenance volume.

Gas Turbine

System Description

E. Inlet Ducting and Silencing

The inlet air ductwork system contains the compressor noise silencing and connects the inlet compart-ment to the compressor inlet plenum. It consists of 2 inlet plenum extensions, a transition duct, an acous-tically treated expansion joint, a 90 degree elbow, 8 feet of parallel baffle silencing and horizontal un-lined ducting that connects to the filter house.

The inlet silencer consists of an acoustically lined duct containing silencing baffles constructed of a low density insulating material which is encapsulated by perforated sheet steel. The acoustic lining in the walls of the silencer duct and the walls of the ducting downstream of the silencer have a similar construc-tion. The vertical parallel baffle is specifically designed to eliminate the fundamental compressor tone as well as attenuating the noise at other frequencies.

There is a stationary trash screen within the elbow duct which can be accessed for cleaning and inspec-tion through a removable panel on the side of the elbow.

The horizontal ducting has flanged connections on top to allow filtered air to be pulled off for compart-ment pressurization and exhaust frame cooling.

The inlet ducting makes use of materials and coatings in their construction which are designed to make them maintenance free. The entire system has been constructed from 304 stainless steel. The perforated sheet is also stainless steel for corrosion resistance.

III. EXHAUST SYSTEM

The exhaust system is the system of ductwork that directs the gas turbine exhaust gases from the power tur-bine exit to the atmosphere. The system is thermally insulated to maintain structural and exterior paint integ-rity while providing personnel protection. It is acoustically insulated to maintain guaranteed overall gas tur-bine noise levels. This configuration consists of the exhaust plenum, plenum top and side covers, an expansion joint, a horizontal transition duct, a horizontal silencer, an up elbow, an exhaust stack, and a rain damper mounted in the stack.

Refer to the “Mechanical Outline, Gas Turbine and Load” drawing, in the Outline and Diagrams tab for de-tails of the configuration.

IV. PLENUM

The plenum captures the exhaust gas leaving the gas turbine and directs it radially away from the turbine. The top and side covers close the opening on the top and non–discharge side of the plenum. These openings provide directional options for exhaust gas flow in other configurations. The plenum is welded in place to an extension from the turbine base. It encloses the turbine exhaust frame, diffuser and turning vanes. Ther-mocouples, mounted in the plenum, provide exhaust gas temperature feedback to the SPEEDTRONICt Mark V control system.

V. EXPANSION JOINTS

Exhaust system expansion joints allow for the thermal growth of adjacent steel duct components while main-taining the integrity of a leak free flowpath. One joint is supplied with this system, located between the ple-num and the lateral transition duct.

System Description

Gas Turbine

4

VI. TRANSITION DUCTS

Transition ducts provide a gradual change in flowpath cross–section between major exhaust system compo-nents to help minimize total system pressure drop.

VII. SILENCER

The silencer is a parallel baffle design where the exhaust gasses pass between the horizontally mounted si-lencer panels before entering the atmosphere. The panels contain sound absorbing ceramic fiber fill encased in perforated metal lagging. The panel thickness and length is sized to absorb enough of the high and low frequency sound energy from the exhaust to meet overall gas turbine noise level guarantees.

VIII. ELBOW

Once the exhaust gas passes through the silencer, it flows into the elbow and is directed up into the exhast stack.

IX. EXHAUST STACK

The exhaust stack is a hollow duct welded to the top of the elbow. It is designed to release exhaust gases to the atmosphere well above ground level at a velocity suited for the proper dispersal of combustion prod-ucts. Provisions for collecting exhaust gas samples are built into the stack. Sampling ports are accessible from the ground level via an arrangement of ladders and platforms.

X. RAIN DAMPER

A rain damper is mounted in the stack to prevent water from entering the horizontal ductwork. The damper is an electrically driven device. The damper consists of a gutter system with a stack–mounted drain pipe that runs to the ground.

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GE Power Systems

LUBRICATION SYSTEM

1. GENERAL

The lubricating requirements for the gas turbine power plant are furnished by a common forced feed lubrication system. This lubrication system, complete with tank, pumps, coolers, filters, valves and various control and protection devices, furnishes normal lubrication and absorption of heat rejection load of the gas turbine. Lubricating fluid is circulated to the three main turbine bearings and to the turbine accessory gear. Also, lubricating fluid is supplied to the starting means torque converter for use as hydraulic fluid as well as for lubrication. Additionally, a portion of the pressurized fluid is diverted and filtered again for use by hydraulic control devices as control fluid.

Major system components include:-

a. Lube reservoir in the accessory base.

b. Main lube oil pump (shaft driven from the accessory gear). c. Auxiliary lube oil pump.

d. Emergency lube oil pump.

e. Pressure relief valve VR 1 in the main pump discharge. f. Lube oil heat exchangers.

g. Lube oil filters.

h. Bearing header pressure regulator VPR2.

Lube oil temperatures are indicated on the thermometers which are located in the bearing header and the oil tank.

For turbine starting, a maximum of 800 SSU is specified for reliable operation of the control system and for bearing lubrication.

Lubricating fluid for the main, auxiliary and emergency lube pumps is supplied from the reservoir, while lubricating fluid used for control is supplied from the bearing header. This lubricant must be regulated to the proper, predetermined pressure to meet the requirements of the main bearings and the accessory lube system, as well as the hydraulic control and trip circuit. All lubricating fluid is filtered and cooled before being piped to the bearing header.

2. FUNCTIONAL DESCRIPTION a. Lubricant Reservoir and Piping

The reservoir and sump for the lubrication system is the 3300 gallon (12491 litres) tank which is fabricated as an integral part of the accessory base. Lubricating fluid is pumped from the reservoir by the main shaft driven pump (part of the accessory gear) or auxiliary or emergency pumps to the bearing header, the accessory gear and the hydraulic supply system. After lubricating the bearings, the lubricant flows back through various drain lines to the lube oil reservoir. The total system capacity is approximately 4000 gallons (15000 litres).

All lubricant pumped from the lube oil reservoir to the bearing header flows through the lube oil heat exchangers to remove excess heat and then through the cartridge type filters.

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GE Power Systems Filtration of all lube oil is accomplished by filter vessels installed in the lube oil system just after the lube oil heat exchangers. Two (dual) coolers and filters are used with a transfer valve installed between the coolers and filters to direct oil flow through either cooler or filter and into the lube oil header.

The dual lube oil filters have removable 5-micron (nominal) synthetic media filter elements. A differential pressure gauge indicates the filter pressure drop. There is also a pressure switch (63QQ-1) which signals when the differential pressure reaches the recommended level for element change.

Lubricant from the No. 1 turbine bearing assembly is piped through an internal drain line to the lube oil reservoir. Drain from the other turbine bearing assemblies is piped to an externally routed drain header that interconnects the accessory base and turbine base. The lube oil drain flows forward through this common drain header to the lube oil reservoir.

A lube oil level gauge and alarm system, a hermetically sealed float arm operated device, is mounted to the side of the lube oil reservoir above the maximum expected level of the lube oil. The float mechanism energizes an annunciator circuit of the turbine control panel, through a dial gauge and switches, to operate an annunciator drop and an audible alarm if the liquid level rises above or drops below a predetermined level.

A lubricant drain connection is located on the side of the accessory base to drain the lube oil reservoir.

Note: The oil level gauge indicates F (Full) or E (Empty) before the annunciator alarm is sounded.

The lubricant oil system is vented through a mist eliminator. This device removes oil mist from the air before it goes to the atmosphere.

b. Standby Heaters

During standby periods the lubricating fluid is maintained at a viscosity proper for turbine start up by heaters installed in the lube oil reservoir. Temperature switches sense reservoir fluid temperature and control the heaters to maintain fluid temperature to achieve allowable viscosity. Another temperature switch senses reservoir temperature and will not permit the turbine to be started if the fluid temperature drops below that to maintain the viscosity required for start up.

c. Lubricating oil pumps

Lubrication to the bearing header is supplied by three lube oil pumps:-

1. The main lube oil supply pump is a positive displacement type pump mounted in and driven by the accessory gear.

2. The auxiliary lube oil supply pump is a submerged centrifugal pump driven by an ac motor.

3. The emergency lube oil supply pump is a submerged centrifugal pump driven by a dc motor.

1. Main Lube Oil Pump

The main lube oil pump is built into the inboard wall of the lower half casing of the accessory gear. It is driven by a splined quill shaft from the lower drive gear. The output pressure to the lubrication system is limited by a back pressure valve to maintain system pressure.

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GE Power Systems

2. Auxiliary Lube Oil Pump

The auxiliary lube oil pump is a submerged centrifugal type pump driven by an ac motor. It provides lubricant pressure during start up and shutdown of the gas turbine when the main pump cannot supply sufficient pressure for safe operation. Operation of this pump is as follows:-

a. The auxiliary lube oil pump is controlled by a low lube oil pressure alarm switch (63QA-I). This switch causes the auxiliary pump to run under low lube oil pressure conditions as is the case during start up or shutdown of the gas turbine when the main pump, driven by the accessory drive device. does not supply sufficient pressure. It also indicates an alarm condition on the annunciator panel.

b. The auxiliary pump continues to operate until the turbine reaches approximately 95 percent of operational speed. At this point. the auxiliary lube pump shuts down and system pressure is supplied by the shaft driven, main lube oil pump.

During the turbine starting sequence the pump starts when the start signal is given. The control circuit is through the normally closed contacts of pressure switch 63QA-l. The pump will run until the turbine operating speed is reached (operating speed relay 14HS picks up), even though the lube oil header is at rated pressure and the pressure switch (63QA-1) contacts have opened.

When the turbine is on the shutdown sequence, this pressure switch will signal for the auxiliary pump to start running when the lube oil header pressure falls to the point at which the contacts of the switch are set to close.

3. Emergency Lube Oil Pump

The emergency lube oil pump is a dc motor driven pump of the submerged centrifugal type. This pump supplies lube oil to the main bearing header during an emergency shutdown in the event the auxiliary pump has been forced out of service because of loss of ac power, or for other reasons. It operates as follows:-

a. This pump is started automatically by the action of pressure switch 63QL-1 whenever the lube pressure in the main bearing header falls below the pressure switch setting.

b. If the auxiliary lube oil pump should resume operation, the emergency pump will be stopped by pressure switch (63QL-1) when the header pressure exceeds the setting of the switch.

c. Should the auxiliary pump fail during the shutdown sequence, because of an ac power failure, or any other cause, the emergency lube oil pump will be started automatically by the action of low lube oil pressure switch 63QL-l and continue to run until the turbine shaft comes to rest.

d. Test Valve - Low Lube Oil Pressure - Emergency Pump Start

A test valve, mounted on the gauge cabinet, provides the means of checking automatic start up of the emergency lube oil pump and pressure switch 63QL-1. This can be done while the unit is operating nor-mally on the main lube oil pump.

The test valve is normally closed and maintains lubricating system pressure on the switch. When per-forming a test, the test valve should be opened gradually to lower lubricating system pressure in the tub-ing to the switch. This provides the means of checktub-ing the pressure points at which the switch operates to start the pump.

Upon closing the test valve, lube oil pressure is returned to normal and the pump should stop as a result of the restoration of pressure on the 63QL-l switch.

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e. Test Valve For Low Lube Oil Pressure - Auxiliary Pump Start

A gauge mounted test valve is also used to provide the means of checking the automatic operation of the auxiliary lube oil pump and pressure switch 63QA-l while the unit is operating normally on the main lube oil pump.

The test valve is installed in the tubing at the switch and is normally closed holding the lube system pressure on the switch. When performing a test, the test valve should be opened gradually to lower the lube oil system pressure on the switch. This oil pressure is indicated on a gauge connected into the pressure line. The gauge provides a means of checking the pressure point at which the switch operates and starts the pump running. When the oil pressure falls to the setting of switch 63QA-1, this pump is started.

f. Heat Exchangers

All lubricant pumped from the lube reservoir to the bearing header flows through either of the dual lube oil heat exchangers to remove excess heat. The dual heat exchangers have a transfer valve between them which directs oil solely through either of the two heat exchangers. This permits the heat exchangers to be operated singly so that one heat exchanger can be removed for servicing without shutting down the turbine. See section below on oil filters with regard to operating the transfer valve.

g. Oil Filters

Filtration of all lube oil is accomplished by a five-micron (nominal), synthetic media element filters installed in the lube oil system just after the lube oil heat exchanger. Two (dual) filters are used with a transfer valve installed between the filters to direct oil flow through either filter and into the lube oil header. Only one filter will be in service at a time, thus cleaning, inspection. and maintenance of the second one can be performed without interrupting oil flow or shutting the as turbine down. By means of the manually operated transfer valve, one filter can be put into service as the second is taken out without interrupting the oil flow to the main lube oil header. The transfer of operation from one filter to the other should be accomplished as follows:-

1. Open the cross fill valve and fill the standby filter until a solid oil flow can be seen in the flow sight glass in the filter vent pipe. This will indicate a "filled" condition.

2. Operate the transfer valve to bring the standby filter into service. 3. Close the cross fill valve.

A differential pressure gauge is connected across the filters to indicate when the filter element needs replacement. Filters should be changed when the differential pressure gauge indicates a differential pressure of 15 psi (103.47 kPa).

Pressure switch 63QQ-l is provided to alarm at a differential pressure of 15 psi (103.47 kPa), indicating that a change of filter is required.

h. Pressure Regulation

Two regulating valves are used to control lubrication system pressure. A back pressure relief valve, VR 1, limits the positive displacement main pump discharge header pressure and relieves excess fluid to the lube oil reservoir. The lube oil pressure in the bearing header is maintained at approximately 25 psig (172.36 kPa) by the diaphragm operated regulating valve, VPR2. The diaphragm valve is operated by sensing fluid pressure in the bearing header.

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j. Pressure And Temperature Protective Devices

The condition of low lubricating oil pressure is detected by a pressure switch that opens after a decrease of line pressure to a specified value and trips the unit. Pressure switches 63QT-2A and transmitter 96QT-2A installed in the turbine bearing feed piping shut the turbine down if the lubricant pressure drops to an unacceptable level. Likewise, temperature switches 26QT-IA and -26QT-IB are installed in the lubricating fluid header piping and cause the unit to trip should the temperature of the lubricant to the bearings exceed a preset limit. Before this limit is reached, switch 26QA-l in the piping will cause an alarm.

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HYDRAULIC SUPPLY SYSTEM

1. GENERAL

Fluid power, required for operating the control components of the gas turbine fuel system and the inlet guide vane system is provided by the hydraulic supply system. This fluid furnishes the means for opening or resetting the fuel stop valves, in addition to the variable turbine inlet guide vanes and the hydraulic control and trip devices of the gas turbine.

Major system components include the main hydraulic supply pump, an auxiliary supply pump, the system filters, an accumulator assembly, and the hydraulic supply manifold assemblies.

2. FUNCTIONAL DESCRIPTION

Regulated and filtered lube oil from the bearing header of the gas turbine is used as the oil supply to provide the high pressure fluid necessary to meet the hydraulic system requirements.

A pressure compensated variable displacement pump, driven by a shaft of the accessory gear, is the primary pump that pumps oil from the lube system to the hydraulic supply manifold. An auxiliary motor driven hydraulic pump is also provided as the backup to the primary pump. The fluid supply for these hydraulic pumps is taken from the bearing lube oil header, this fluid having been filtered previously. Hydraulic oil, pressurized by the hydraulic pumps, is controlled by pressure compensators, VPR3−1 and VPR3−2 built into the pumps. The action of the compensator varies the stroke of the pump to maintain a set pressure at the pump discharge.

The auxiliary hydraulic pump operates whenever the main hydraulic pump pressure output level is inadequate for turbine operation, such as during start up or low speed conditions. When the main pump is operating and it fails to maintain adequate pressure, the condition will be sensed by pressure switch 63HQ−1, and the auxiliary pump will be started by a signal from this switch.

Hydraulic fluid is pumped to the hydraulic supply manifold. This manifold is an enclosure designed to provide a means of interconnecting a number of small components. Contained within the manifold assembly are relief valves, air bleed valves, and check valves. Each pump has a pressure compensator built into it which regulates pressure. There are also relief valves, VR21−1 and VR22−1, which will relieve pressure should the pressure regulator fail. Check valves VCK3−1 and VCK3−2 prevent oil from flowing into the out of service pump. The check valves also keep the hydraulic lines full when the turbine is shut down. The air bleed valves vent any air present in the pump discharge lines.

From the output connections of the manifold assembly the high pressure fluid is piped through the system filters (FH2−1 and FH2−2) and now becomes a high pressure control fluid. The hydraulic supply system filters prevent contaminants from entering the control devices of the inlet guide vane system, the fuel control servovalves and other hydraulic devices. Only one filter is in service at any time during system operation.

The dual filter assembly, complete with cross fill valve and transfer valve, is provided to permit changeover to the second filter without interrupting the operation of the system. A differential gauge is provided to indicate the oil pressure drop across the filters. When the gauge indicates a pressure differential of 60 psid (413 kPad), or annually (whichever occurs first) the filter cartridge should be replaced. There is also a differential pressure switch, 63HF−1, which alarms at high differential pressure.

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GE Power Systems The following procedure should be used when transferring from one filter to the other :

1. Open the air bleed valve on the unused filter. 2. Open the cross fill valve.

3. When oil with air comes out of the air bleed, operate the transfer valve. 4. Close the cross fill valve.

5. When no air is contained in the oil coming from the air bleed, close the bleed valve.

A hydraulic accumulator assembly, having two accumulators, is also connected in the high pressure line of the hydraulic supply system to absorb any severe shock that may occur when the supply pumps are started. In addition. the accumulator supplies the necessary transient demands for operation of all of the hydraulic control and protection components required in the control and protection of the gas turbine. The output of the hydraulic supply system is a high pressure control fluid, a primary hydraulic interface between the turbine control and protection system and the fuel system servovalves that control or shut off fuel. This high pressure supply fluid is also used as the hydraulic fluid in the variable inlet guide vane actuating cylinders and IGV control system.

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TRIP OIL SYSTEM

1. GENERAL

The gas turbine protection systems consist 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.

The trip oil system is the primary protection interface between the turbine control and protection system circuits (SPEEDTRONIC Control System) and the components on the turbine which admit or shut off fuel to the turbine. The system contains devices which are electrically operated through the turbine control panel by SPEEDTRONIC signals as well as others that are completely mechanical devices that operate directly on the turbine components totally independent of the turbine control panel.

2. FUNCTIONAL DESCRIPTION a. General

Low pressure oil, taken from the turbine lube oil system, is used in the trip oil system. Lube oil is passed through a piping orifice to become the trip oil (OLT). The orifice is located in the pipe running from the bearing header supply to the trip oil system. This orifice is sized to limit the flow of lube oil into the trip oil system and ensure an adequate capacity for all tripping device operations without causing a starvation of the lube oil system when the trip oil system is activated.

The devices that cause a turbine shutdown through the trip system do so by dumping fluid pressure from the system either directly or indirectly through electrohydraulic dump valves, 20FG-1 or 20TV-1. When oil in the trip oil line is dumped, fuel stop valves close by spring return action.

When the turbine is started the dump valves are energized to reset at the desired point in the starting sequence permitting oil pressure to open the fuel stop valves and inlet guide vanes. The fuel stop valves remain open until some trip action occurs or until the unit is shut down.

An orifice is installed in the trip oil lines to the liquid fuel stop valve to permit operation. Since inlet guide vane activation is also part of the trip oil system, the orifice will permit inlet guide vane operation when the fuel system is in its tripped state.

Pressure switches 63HG−1, 63HG−2 & 63HG−3 monitor trip oil pressure to the liquid fuel system. If the pressure to the fuel system becomes too low for reliable operation, the switch will trip the unit and cause annunciation of low trip oil pressure.

1. Fuel Gas Stop Ratio Valve Solenoid Valve (20FG-1)

Liquid fuel solenoid dump valve 20FG-1 is a spring biased spool valve which relieves trip oil pressure causing the liquid fuel stop valve to trip shut. The dump valve is energized to run and de-energized to trip from the SPEEDTRONIC panel. Since this dump valve is spring biased to trip, it protects the turbine during all normal situations as well as those times when loss of dc power occurs.

2. Variable Inlet Guide Vane System

3.

The modulated inlet guide vane system is activated by the action of the trip oil system using low pressure trip oil (OLT) in conjunction with high pressure oil (OH) from the hydraulic supply system. Electronic

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GE Power Systems control signals activate and position the inlet guide vanes, both during normal operation and under trip conditions, through the action of servovalve 90TV-1, hydraulic dump valve VH3, position sensors 96TV−I and 96TV−2 and hydraulic activating cylinder ACV 1.

During normal operation trip oil (OLT) is pressurized and dump valve VH3 is energized which allows hydraulic oil from the hydraulic supply system to flow through servovalve 90TV-1. The controlled, or modulated, position of inlet guide vane servovalve 90TV-1 determines the flow of hydraulic oil through the servovalve and dump valve VH3 to the inlet guide vane hydraulic actuator ACV 1. The hydraulic pressure applied to the actuator determines the position of the inlet guide vane control ring.

In a trip condition trip oil is dumped by action of dump valve 20TV-1. This causes inlet guide vane dump valve VH3 to move to the dump position by action of the spring return feature thereby dumping actuator cylinder oil which closes the inlet guide vanes.

When the turbine is at rest, the inlet guide vane angle position is at the designed closed position. This closed guide vane angle is the position established to limit the air flow through the compressor during the turbine accelerating and decelerating sequence.

MOOG2 9/97

SUPPLY PRESSURE

FILTERED 1st STAGE SUPPLY PRESSURE

1st STAGE CONTROL PRESSURE

CONTROL PORT PRESSURES

RETURN PRESSURE

INTERNAL DRAIN PRESSURE

Servovalve Overview

Moog CONTROLS

TORQUE MOTOR

PERMANENT MAGNET COILS TOP POLE PIECE ARMATURE

FLEXURE SLEEVE BOTTOM POLE PIECE FLAPPER NOZZLE FILTER MOTOR SHIM END CAP ORIFICE, INLET FEEDBACK SPRING SPOOL STOP BUSHING (SLEEVE) SPOOL (SLIDE) ORIFICE, RETURN BODY (HOUSING) DRAIN 1350 PSI LVDT TO < RST >

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GE Power Systems

COOLING AND SEALING AIR SYSTEM

1. GENERAL

The cooling and sealing air system provides the necessary air flow from the gas turbine compressor to other parts of the gas turbine rotor and stator to prevent excessive temperature build up in these parts during normal operation and for sealing of the turbine bearings. Atmospheric air from off base centrifugal type blowers is used to cool the turbine exhaust frame.

Cooling and sealing functions provided by the system are as follows: a. Sealing of the turbine bearings.

b. Cooling of internal turbine parts subjected to high temperature. c. Cooling of the turbine outer shell and exhaust frame.

d. Providing an operating air supply for air operated valves.

The cooling and sealing air system consists of specially designed air passages in the turbine casing, turbine nozzles and rotating wheels, piping for the compressor extraction air and associated components. Associated components used in the system include:

a. Turbine Exhaust Frame Cooling Blowers b. Air Filter (with poro-stone element) c. Pressure Gauge

d. Dirt Separator

2. FUNCTIONAL DESCRIPTION a. General

Air from the axial flow compressor, extracted from several points, is used for sealing the bearings, cooling turbine internal parts and to provide a clean air supply for air operated control valves. Compressor extraction air is also used for pulsation protection of the compressor during turbine start up and shut down.

Bearing sealing air is extracted from the fifth stage of the compressor. Internal cooling air is extracted from the discharge of the compressor including the internal flow of cooling air through the turbine rotating and stationary parts. Air used in cooling the turbine external casing is ambient air supplied by off base motor driven blowers.

b. Bearing Cooling and Sealing

Cooling and sealing air is provided from two connections on the compressor casing at the fifth stage and is piped externally to each of the three turbine bearings. Orifices in the air lines to the turbine bearings limit the flow of air and the pressure to the proper value. The centrifugal dirt separator located in the fifth stage piping removes any particles of dirt or foreign matter that might be injurious to the bearings. This pressurised air cools and seals the bearings by containing any lubricating fluid within the bearing housing that otherwise might seep past the mechanical seals. Air is directed to both ends of each bearing housing providing a pressure barrier to the lubricating fluid. After performing this function, the air is vented via the oil drain passage from the No. 1 and No. 3 bearings while air from the No. 2 bearing is vented to atmosphere.

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c. Exhaust Frame and Turbine Shell Cooling

Cooling of the exhaust frame and turbine shell is accomplished by two electric motor driven, centrifugal blowers, 88TK-1 and 88TK-2, which are mounted external to the turbine. An inlet screen is provided with each blower and the discharge of each passes through a back draft damper (check valve), VCK7-1 or VCK7-2 before entering openings in the exhaust frame outer sidewall cavity. The cooling air flow splits, with part of the air passing along and cooling the turbine shell and the other portion flowing through the exhaust frame strut passages. The air flow through the struts divides, with a portion directed through passages to cool the third stage turbine aft wheelspace and the remainder flowing into the load shaft tunnel where it discharges through a duct to atmosphere.

Air for cooling the exhaust frame and turbine shell is normally provided by the two blowers operating simultaneously in parallel. Each blower has a pressure switch, 63TK-l or 63TK-2, to sense blower discharge pressure. If one of the blowers should fail, the loss of blower discharge pressure will cause contacts of the respective 63TK pressure switch to close and an alarm will be annunciated. The turbine will continue to run with the other blower providing cooling air at a reduced flow rate. If both blowers should fail, the turbine will be shut down in a normal shutdown sequence.

d. Pulsation Protection

The pressure, speed and flow characteristics of the gas turbine compressor are such that air must be extracted from the 11th stage and vented to atmosphere to prevent pulsation of the compressor during the acceleration period of the turbine starting sequence and during deceleration of the turbine at shutdown. Pneumatically operated 11th stage air extraction valves, controlled by a three way solenoid valve, are used to accomplish the pulsation protection function.

Eleventh stage air is extracted from the compressor at four flanged connections on the compressor casing. Each of these connections is piped through a normally open, piston operated, butterfly or vee ball type valve, VA2-1, VA2-2, VA2-3, and VA2-4, to the turbine exhaust plenum. Limit switches 33CB-1, 33CB-2, 33CB-3, and 33CB-4 are mounted on the valves to give an indication of valve position.

Compressor discharge air controlled by solenoid valve 20CB-1 is used to close the compressor bleed valves. Air from 11th stage compressor discharge is piped to a porous air filter which removes dirt and water from the compressor discharge air, by means of a continuous blowdown orifice, before the air enters solenoid valve 20CB. From the solenoid valve, the air is piped to the piston housings of the four extraction valves.

During turbine startup, 20CB-1 is de-energised and the 11th stage extraction valves are open allowing 11th stage air to be discharged into the exhaust plenum thereby eliminating the possibility of compressor pulsation. Limit switches, 33CB-1 through 33CB-4, on the valves provide permissive logic in the starting sequence and ensure that the extraction valves are fully opened before the turbine is fired. The turbine accelerates to full speed and when the generator circuit breaker closes, the 20CB-1 solenoid valve is energised to close the extraction valves and allow normal running operation of the turbine. When a turbine shutdown signal is initiated and the generator circuit breaker is opened, 20CB is de-energised and 11th stage air is again discharged into the exhaust plenum to prevent compressor pulsation during the turbine deceleration period.

e. Pressurized Air Supply

Compressor discharge air is also used as a source of air for operating various air operated valves in other systems. Air for this purpose is taken at the discharge of the compressor and is then piped to the various air operated valves.

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f. Water Wash Provisions

When water washing the gas turbine compressor or turbine section, it is important to keep water out of the components that are actuated by compressor discharge air and out of the turbine bearings. To prevent water from entering these components and the bearings, isolation valves are provided in the sealing lines to the No. 1, No. 2, and No. 3 bearings, and in 20CB-1 and 96CD-1A 1B and 1C feed lines.

During normal operation of the gas turbine, all isolation valves are to be open. Before initiating water wash, the isolation valves must be closed and the drain and air separator blowdown valves opened. At the conclusion of the water wash, the isolation valves must be opened and the drain and separator blowdown valves closed to allow normal operation of the turbine.

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GE Power Systems

COOLING WATER SYSTEM

1. GENERAL

The cooling water system is designed to accommodate the heat dissipation requirements of :- 1. Lube Oil System.

2. Atomizing Air System. (if liquid fuel is used) 3. Turbine Support Legs

The cooling water system comprises both on base and off base mounted components. The on base components include the lube oil heat exchangers, atomizing air precooler, flow regulating valves, orifices and isolating valves. Included in the off base components is a water to air fin-fan cooling module and a cooling water pump skid comprising pumps, valves and various flow control devices.

2. ON BASE COOLING WATER SYSTEM

The cooling water is circulated through the system by a centrifugal type pump. After absorbing the heat rejected by the lube oil and atomizing air heat exchangers and the turbine support legs, the cooling water flows to the off base mounted finned tube heat exchanger.

The cooling water circuits for the lube oil heat exchanger and atomizing air precooler each have a temperature actuated three way valve installed in the cooling water supply line. Valve (VTR-l) is provided for the lube oil heat exchangers and valve (VTR-2) is provided for the atomizing air precooler. This type of valve, which controls cooling water flow to the heat exchanger, has a manually operated device which can be used to override the thermal element. The manual override device should be used only when the thermal element of the valve is inoperative, and Gas Turbine operation is required.

Valves (VTR-l) and (VTR-2) automatically control the flow of cooling water passing through the heat exchangers. The valves respond to temperature changes in the atomizing air compressor inlet line and the lube oil feed header. These changes are sensed by a control bulb connected to each valve. Each bulb contains a thermal sensitive liquid which expands when heated. This generates pressure within the bulb. The pressure is transmitted through a capillary tube to a bellows arrangement which positions the valve plug to control the flow of cooling water through the related heat exchanger.

The valves are closed during turbine start up and will start to open as the temperature of the sensed fluid approaches the control setting. Valve (VTR-2), installed in the cooling water line to the atomizing air pre-cooler, has a small bypass orifice drilled into the valve body to ensure that the pre-cooler is flooded at all times.

Isolating valves are installed in the cooling water piping to the lube oil heat exchangers to enable the exchangers to be serviced. Valves are not installed in the piping to the atomizing air pre-cooler due to the severe consequences of inadvertently shutting off cooling water flow to this component.

3. CORROSION INHIBITOR

In order to reduce the corrosive properties of water it is necessary to add a corrosion inhibitor to the cooling water system.