2.3.2 GT Details

8/9/2019 2.3.2 GT Details

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2.3.2 Gas Turbine Details of Construction and Operation

GT2-0 2.3.2-1

8/9/2019 2.3.2 GT Details


8/9/2019 2.3.2 GT Details


2.3.2 Gas Turbine Details of Construction and Operation

The Siemens V94.2 is a single shaft, cold end drive industrial gas turbine engine designed to drive the electric generator from thecompressor end intermediate shaft. The three major sections of the engine are:

Compressor Section Combustor Section Turbine Section

The sixteen stage axial flow compressor and the four stage turbine are mounted on a common shaft and supported radially by two journal bearings. The bearings are housed in the compressor inlet case and the turbine exhaust case. The compressor end bearing is also providedwith two thrust bearing disc to absorb the axial loads of the engine when the electric generator is not magnetically locked to the utility grid.The engine is designed to operate at a constant speed of 3,000 rpm (Revolutions per minute).

This section of the manual will review the details of the engine's construction after a simplified description of the engine's basic control

and operation scheme.

GT2-3 2.3.2-2

8/9/2019 2.3.2 GT Details


GT2-3BJ

GAS TURBINE ENGINE

BASIC FUEL CONTROL SCHEME

IGNITION GAS

FUEL SUPPLYSHUT OFF VALVE

RETURN FUEL CONTROL /

SHUT OFF VALVE

EGT

CIT

CG

CIP

CG

BE

NT

CDP

CDT

S

PDT

HUM

CG

8

FROM MEGAWATTTRANSMITTER

AUTOMATICSYNCHRONIZER

FUEL MANAGEMENTCONTROL SYSTEM

(SIMADYN)

LIQUIDFUEL SUPPLY

LIQUIDFUEL RETURN

EXHAUST GAS TEMPERATURE

COMBUSTOR HUMMING PROTECTIONOPTICAL FLAME DETECTOR

COMBUSTORDIFFERENTIAL

PRESSURE

VALVE POSITION

VALVE POSITION

VALVE POSITION

FUEL DEMAND SIGNAL

COMPRESSOR INLET TEMPERATURE

COMPRESSOR INLET PRESSURE

TURBINESPEED

COMPRESSORDISCHARGEPRESSURE

COMPRESSORDISCHARGE

TEMPERATURE

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2.3.2 Gas Turbine Details of Construction and Operation ( Continued )

Basic Fuel Control Scheme

The illustration above depicts the basic fuel and mass flow control of the gas turbine engine. The fuel management fuel/mass flowcontroller (SIMADYN) receives input signals of the various engine operating parameters and outputs a fuel demand signal for control ofthe fuel supply and return control valves. It also outputs an inlet guide vane (IGV) demand signal for control of the inlet guide vane position from minimum open position to maximum open position. During a normal start up sequence the engine is accelerated by thestarting frequency converts, up to and through 480rpm. At this point the control system initiates a light off command for the ignition gassystem to establish an ignition gas flame within the combustor. At approximately 540 RPM the fuel supply and return control valves areopened to minimum flow. The supply valve controls the supply pressure to the combustor. The return valve is positioned for the correctliquid fuel flow for initial light off , by the ignition gas flame.

The control logic energized two timers when the light off command was initiated. One timer will de-energize the ignitors 9 seconds afterthe light off command. The other timer will initiate a gas turbine trip 12 seconds after the light off command, if optical detectors 1 and 2(B.E) fail to verify the presence of flame within the combustor.

Once flame verification is accomplished and NT speed is greater than 1,080 RPM, the SIMADYN will ramp the fuel return control valvetowards its closed position. This is a time ramp signal produced by the run up ramp generator control logic. As the return control valve isramped toward closed, the amount of fuel to the combustor and thereby combustion hot gas increases. This along with the torque applied by the SFC accelerates the engine toward design operating speed (3,000rpm).

During this acceleration the rotor speed exceeds 2,520 rpm (NT) and the SFC is deenergized. The engine continues to accelerate on fuelscheduling by the run up ramp generator. A protection circuit in the SIMADYN prevents the run up ramp generator from injecting to muchfuel into the combustor for a given rotor speed.

GT2-3 2.3.2-3

8/9/2019 2.3.2 GT Details


GT2-3BJ

GAS TURBINE ENGINE

BASIC FUEL CONTROL SCHEME

IGNITION GAS

FUEL SUPPLYSHUT OFF VALVE

RETURN FUEL CONTROL /

SHUT OFF VALVE

EGT

CIT

CG

CIP

CG

BE

NT

CDP

CDT

S

PDT

HUM

CG

8

FROM MEGAWATTTRANSMITTER

AUTOMATICSYNCHRONIZER

FUEL MANAGEMENTCONTROL SYSTEM

(SIMADYN)

LIQUIDFUEL SUPPLY

LIQUIDFUEL RETURN

EXHAUST GAS TEMPERATURE

COMBUSTOR HUMMING PROTECTIONOPTICAL FLAME DETECTOR

COMBUSTORDIFFERENTIAL

PRESSURE

VALVE POSITION

VALVE POSITION

VALVE POSITION

FUEL DEMAND SIGNAL

COMPRESSOR INLET TEMPERATURE

COMPRESSOR INLET PRESSURE

TURBINESPEED

COMPRESSORDISCHARGEPRESSURE

COMPRESSORDISCHARGE

TEMPERATURE

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Basic Fuel Control Scheme ( Continued )

When the run up ramp generator accelerates the rotor through approximately 2,900rpm (NT), the speed controller logic, within theSIMADYN takes control of the return control valve and continues to accelerate the rotor to design operating speed (3,000rpm). The runup ramp generator is a simple time ramp of the fuel demand signal. The speed controller, however is a true speed governor. Its objective isto control the amount of fuel flow to the combustor to maintain the actual turbine speed (NT) equal to the speed set point of the speedcontroller. The speed controller set point is adjustable and is varied by the automatic synchronizer to achieve phase match between theelectric generator and the utility electrical distribution system.

When synchronization is achieved the teleperm control logic closes the main generator circuit breaker and the load control logic in theSIMADYN assumes control of the return control valve. The load controller immediately increases fuel flow to the engine to achieve aminimum generator load output of approximately 20 megawatts. When the step load to 20 megawatts occurred it was because more fuelas added into the combustor. The speed of the gas turbine generator did not increase, however because the generator rotor is magnetically

coupled with the utility electrical distribution system. The load controller set point can be adjusted by the operator to increase load or ifthe desired load set point is pre-selected, the control system will automatically load the machine.

During loading of the machine above 20 megawatts, exhaust gas temperature is maintained at a constant exhaust gas temperature (EGT) by a combination of fuel scheduling and control of air flow through the engine, with the inlet guide vanes (IGV).

GT2-3 2.3.2-4

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Basic Fuel Control Scheme ( Continued )

The compressor inlet temperature sensor (CIT) is used by the SIMADYN as a bias to calculate corrected exhaust gas temperature. Rotorspeed is used for the EGT correction as well.

The compressor discharge temperature sensor (CDT) is used by the SIMADYN to limit the maximum allowable compressor dischargetemperature. The SIMADYN uses the compressor discharge pressure sensor (CDP) to limit the maximum allowable compressordischarge pressure, limit fuel scheduling during acceleration and in conjunction with the compressor inlet pressure sensor (CIP), limit thecompression ratio of the compressor. The combustor pressure differential sensor (PDT) monitors for abnormal combustor pressuredifferentials. The humming sensor is monitored by the SIMADYN and will automatically reduce load if humming is detected.

In a normal shutdown sequence the control system will automatically unload the gas turbine generator using the SIMADYN loadcontroller. When load is reduced to approximately 1.5 megawatts, the main generator breaker is opened and the fuel supply and shut offvalves are closed. This shuts down the gas turbine and the rotor speed coast down to approximated 180 rpm, and the turning gear is thenengaged for a 24 hour cool down period. Continual turning gear speed is approximately 120 rpm.

GT2-4A 2.3.2-5

8/9/2019 2.3.2 GT Details


GT2-4aBJ

SIEMENS V94.2 GAS TURBINE ENGINE

ELEVATION DIAGRAM

TURBINE EXHAUSTCASE

IGRS

COUPLING FLANGECOMPRESSOR INLET

BEARING

TURBINE INLETCASE

COMPRESSORROTOR

COMPRESSORSTATOR HOUSING NO. 1


TURBINESTATOR

CASE

TURBINEROTOR

COMBUSTOR

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Rotor and Cases

The rotor carries the moving blades of the compressor (16 stages). In the compressor section, moving blades convert torque into kineticenergy. In the turbine section, moving blades convert kinetic energy to torque. A coupling flange at the compressor end harnesses excesstorque, developed by the turbine section, to drive the electric generator.

The rotor, which is supported in bearings at its two ends, is comprised of the following:

Front hollow shaft 16 compressor disks The inner hollow shaft 4 turbine disks The rear hollow shaft Central tie bolt Conical springs and tie bolt nut

The hollow shafts and disks are held together by the tie bolt and the tie bolt nut. The tie bolt is supported in the disks at several locationsalong its length by truncated conical springs. Hirth facial serrations, which permit unrestricted radial expansion and torque transmit, alsocenter the individual rotor items. The rotor is mounted on bearings at both ends. The rotor runs in the journal bearings on the smallest barrel surface of the front hollow shaft. The adjacent end faces form the bearing surfaces of the thrust bearing.

The rotor runs in the turbine end journal bearing on the smallest barrel surface of the rear hollow shaft. The rear compressor section of therotor supplies the turbine section with cooling air. Balancing weights can be added to the shaft at seven locations, three of which are

available for rebalancing in the power plant if necessary. All compressor and turbine moving blades can be removed without having to liftthe rotor out of its bearings.

GT2-4A 2.3.2-6

8/9/2019 2.3.2 GT Details


GT2-4aBJ


ELEVATION DIAGRAM

TURBINE EXHAUSTCASE

IGRS


BEARING

TURBINE INLETCASE

COMPRESSORROTOR



TURBINESTATOR

CASE

TURBINEROTOR

COMBUSTOR

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Rotor and Cases ( Continued )

The rotor comprises a number of disks, each of which carries one row of blades and three hollow shafts, which are held together by acentral tie rod. Hirth facial serrations mesh at the interfaces between disks and hollow shaft sections. These serrations center the rotordisks while permitting unrestricted radial expansion and transmitting torque. This rotor configuration results in a self supporting drum ofgreat stiffness, high critical speed and a relatively low weight. The turbine rotor is internally cooled. A portion of the compressed air flowis extracted from the compressor and used to cool turbine moving blades. Air extracted from the compressor outlet is fed through bores inthe center hollow shaft to the first row of turbine blades. Downstream turbine blades are supplied with air at a lower pressure andtemperature.

The cooling air flow enters the interior of the rotor through bores in two compressor disks and flows through bores in the disk hubs ofdownstream compressor disks, through pipes between the final compressor disk and the first turbine disk and through hub bores in theturbine disks to the turbine stages 2, 3 and 4. Cooling air then enters the flow of hot gas and forms a film of cooling air, which surrounds the

hub to cool blade roots. This flow of cooling air flow ensures that the rotor drum, is bathed in cooling air, even in the turbine section, preventing additional thermal stresses, which could cause shaft distortion during load changes and rapid starts.

GT2-4A 2.3.2-7

8/9/2019 2.3.2 GT Details


GT2-4aBJ


ELEVATION DIAGRAM

TURBINE EXHAUSTCASE

IGRS


BEARING

TURBINE INLETCASE

COMPRESSORROTOR



TURBINESTATOR

CASE

TURBINEROTOR

COMBUSTOR

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Rotor and Cases ( Continued )

Horizontal casing joints facilitate maintenance work. The front bearing pedestal contains the combined journal and thrust bearing. Itsouter cone also directs the flow of intake air. The bearing assembly is supported in the flow path by six radial struts connected to lateralfeet. Air is drawn in from the intake structure located upstream of the compressor. The exhaust casing comprises a rigid, one-piece innercylinder, which supports the turbine bearing. Five radial struts directly connect the hub to the outer casing. The exhaust gas flow is guided by the lining of the exhaust gas casing, which is supported in such a way as to allow for thermal expansion. The exhaust casing connectsthe turbine stator case to the exhaust gas diffuser. The turbine rear bearing can be removed axially in the downstream direction.

GT2-5 2.3.2-8

8/9/2019 2.3.2 GT Details


GT2-5BJ

COMPRESSOR INLET CASE WITH INTERMEDIATE SHAFT

GENERATOR SHAFT

COUPLING BOLTS

COUPLING FLANGEAT GENERATOR END

INTERMEDIATE SHAFTSHAFT GLAND

IMPELLER BLADE(PELTON WHEEL

HYDRAULIC OILMANIFOLD

COUPLING

COVER

STRUT

COMBINED JOURNALAND THRUST

OIL SEAL RING

COMPRESSOR INLET CASE

COMPRESSORBEARINGHOUSING

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Compressor Inlet Case

The compressor inlet case contains the compressor inlet bearing and is the major support structure for the compressor inlet end of theengine. Air enters the engine through the annular space between the outer circumference of the case and the compressor inlet bearinghousing. An accelerometer type vibration sensor is mounted externally at the 3:00 o'clock position of the compressor inlet case.

The intermediate shaft is coupled between the compressor shaft and the shaft of the electric generator. Six magnetic speed sensors aremounted on the bearing housing and measure the frequency of the slots on the intermediate shaft.

The function of the compressor inlet bearing casing is to support the compressor turbine rotor at the compressor end of the shaft. The bearing housing and compressor inlet case comprises an outer and inner shell, which forms the compressor air intake duct and areconnected by radial struts. The inner shell accommodates the bearing and turning gear impeller. The shaft is sealed by a bearing seal ringat the front end and an oil seal ring at the rear. The hydraulic oil manifold of the hydraulic turning gear is installed in the cover. The blades

of the hydraulic turning gear impeller are attached to the intermediate shaft.

GT2-6 2.3.2-9

8/9/2019 2.3.2 GT Details


GT2-6BJ

COMPRESSOR INLET BEARING

SIDE VIEW END VIEW

JOURNAL ANDTHRUST BEARING THRUST BEARING

PIN

THRUST PADS

BEARING SHELLSUPPORT

THRUST PADS

THRUST PADS

BORE

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Compressor Inlet Bearing

The combined journal and thrust bearing is a split plain bearing. Two bearing shells lined with babbitt metal are inserted into the journal bearing bore. Their inner surfaces are shaped such that supporting oil wedges form between the bearing shells and support the shaft duringoperation. Lubricating oil is fed under pressure into oil pockets machined into the babbitt metal through bores. At low speeds, jacking oilis fed through the bore holes at high pressure to ensure that complete lubrication is maintained. This extends the service life of the babbittmetal linings and facilitates turning of the shaft. Three thermocouples monitor the temperature of the babbitt metal in the bearing shell,which is subjected to the greatest thermal loadings.

The thrust bearing is comprised of individual thrust pads, which are lined with babbitt metal on their contact surfaces. Thrust pads areattached to the bearing shell support sleeve by hollow pins, which also function as injection nozzles. Tilting edges on the contact facesensure self alignment of the pads and proper oil wedge formation. The temperature of the babbitt metal of the thrust pads is monitored bythermocouples located on both sides of the upper and lower bearing shells.

GT2-4 2.3.2-10

8/9/2019 2.3.2 GT Details


GT2-4BJ

ADJUSTING RING

VANE LEVER

PUSH ROD

BEARING

STATIONARYBLADE CARRIER I

PUSHROD

ACTUATOR

COMPRESSOR INLET GUIDE VANES LEVER

PUSHROD

ADJUSTABLE INLET GUIDE VANE LEVER ARRANGEMENT

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Inlet Guide Vanes (IGVs)

The flow of air through the gas turbine is controlled by adjusting the pitch of the compressor inlet guide vanes. When the inlet guide vanesare “opened”, the air flow through the gas turbine increases. When they are “closed” the air flow decreases. This makes it possible tomaintain a constant corrected turbine exhaust temperature (Tatk) over a limited load range. As a result, the part load efficiency ofcombined cycle operation is improved. The force of an actuator mounted on the compressor support, is transmitted with a push rod torotate the adjusting ring in the circumferential direction. The adjusting ring, which is supported on a stationary blade carrier by eight bearings, adjusts the blade pitch of inlet guide vanes (IGVs) with the push rod and levers.

GT2-7 2.3.2-11

8/9/2019 2.3.2 GT Details


GT2-7BJ

COMPRESSOR ROTOR and STATOR ASSEMBLY

COMPRESSOR BLADES and DISKS

BLADES

DISK

BLADE

DISK

DOVE TAIL ROOT

HIRTH SERRATIONS FOR CENTERINGAND TRANSMITTING TORQUE

CENTER LINE OF ROTOR

DISK AND BLADE ASSEMBLY

STATOR ASSEMBLY

OUTER RING

ROOT

HOOK

STATORBLADE

LABYRINTH

DOVE TAIL ROOT

DISK

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Compressor Blades and Stationary Vanes

The compressor moving blades convert mechanical energy to kinetic and potential energy of the compressed air and thus together with the

stationary blades contribute to pressure increase. Each moving blade is manufactured from a single blank of rustproof material. The vane profile of the blade is optimized in terms of flow characteristics and strength by selecting the appropriate length to width ratio. Dovetail blade roots are used, which are dimensioned to vane length. Moving blades are fitted into corresponding slots in the rotor disks. Lockingwashers ensure that the roots of the blades, at the front end of the compressor rotor, do not shift in their rotor disk slots. Blade roots at therear end of the compressor rotor are fixed in position by caulking blade root material, into corresponding recesses in the disk slots.

This design enables removal or insertion of blades in the event that the rotor must be disassembled. A special surface coating is applied to blades in the first compressor stages to prevent corrosion. The compressor stator blades deflect the air stream passing through the blade passages in a direction opposite to the direction of rotation of the rotor. The resulting deceleration causes static pressure to increase. Thevariable inlet guide vanes make it possible to decrease the inlet air flow. This results in an improved efficiency of the engine under part

load conditions. The stator blades are made in one piece. The airfoils of the first stages are coated for protection against corrosion.

The stator blades are assembled in an outer ring and a split inner ring to form a vane ring. All other stator blades are held in place in theradial and circumferential directions by dovetails inserted into corresponding grooves in the stator blade carriers and locked in the axialdirection. The inner rings join the blades on the inner periphery and support the seal strips for shaft sealing. Except for the variable inletguide vanes, the stator blades are an attached to the inner rings by a double hook arrangement.

GT2-7B 2.3.2-12

8/9/2019 2.3.2 GT Details


GT2-7bBJ

COMPRESSOR SHAFT SEALS and DISCHARGE AIR

CompressedAir

Compressor Discharge Air

COMBUSTOR

TH16 STAGE

TH16 STAGE COMPRESSORDISCHARGE

TH12 STAGE

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Compressor Shaft Seals

The turbine shaft labyrinth seals minimize air leakages. They prevent leakage of oil laden air from the bearing areas, reduce reverse flowsin the compressor and protect the turbine rotor, in the turbine area, from flows of hot gases between casing and blading. The shaft labyrinthseals of the compressor are designed as non contact seals. The function of the labyrinth seals in the front hollow shaft section is to preventthe intake of oil laden air from the compressor bearing into the air flow path. To this end, the labyrinth seals are supplied with air atatmospheric pressure. This flow of air enters through a duct in the bearing casing. The amount of leakage air through the labyrinths is sosmall that there is only slight pressure loss in the channel in the bearing casing. This pressure loss is lower than the vacuum generated bythe lube oil systems tank vapor extractor.

Some of the leakage air thus flows through the oil seal ring into the bearing space. The rest of the leakage air is fed to the intake duct, whichis at sub atmospheric pressure. Labyrinth seals are located between the rows of stationary and moving blading of the compressor tominimize the reverse flow of compressed air.

GT2-9 2.3.2-13

8/9/2019 2.3.2 GT Details


GT2-9BJ

FUEL INJECTIONNOZZLES

DIAGONALSWIRLERS

FLAMEDETECTOR

(TOTAL OF 2)

FLAMEDETECTOR

(TOTAL OF 2)

LEFTCOMBUSTOR

FIRST STAGETURBINE

COMPRESSORDISCHARGE AIR

RIGHTCOMBUSTOR

FLAMECYLINDER

FLAMECYLINDER

AIRAPERTURES

DILUTIONAIR

PRIMARYAIR

COMBUSTOR

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Combustor

The gas turbine engine is designed with two silo type combustors. One is on the left side of the engine and the other is on the right side ofthe engine. Each combustor is provided with eight fuel burners that inject the fuel into the combustor to establish and maintain a flamewithin the combustor. The fuel burners have diagonal swirlers to atomize the fuel. An electrical ignitor is installed in each of the eight fuel

burners. Compressor discharge air flows to the top of the combustor between the outer case and inner liner of the combustor. It thenreverses its direction of flow downwards through the diagonal swirlers of the eight fuel burners and is mixed with fuel to establish theflame in the center of the combustor. The hot gas ( Heated air ) leaves the combustor through a convergent duct and flows to the turbine ofthe engine.

The combustor is provided with electric motor driven air apertures that are used to control the fuel air ratio within the flame cylinder.Under low air flow conditions the apertures are open, which increase the amount of dilution air that bypasses the flame area of thecombustor and decreases the amount of primary air that atomizes and mixes with the fuel from the fuel burners. The inverse will occur

under high air flow conditions. The control logic uses the engine’s exhaust gas temperature to control the position of the apertures. Thehigher the EGT ( Exhaust gas temperature ), the more closed the apertures.

The combustor flame is monitored by two optical flame sensors. These are located on the combustion chamber jacket and are eachdirected at two flame axes through a flame cylinder opening. If the loss of flame is detected by both detectors, the flame sensors initiate agas turbine trip. The ring shaped combustion space is enclosed by the inside and outside flame cylinder wall. The internal items of thecombustor chamber form the boundary of the region, in which the combustion gases are generated, mixed and fed downstream. The ringshaped combustion space is enclosed by the inside and outside flame cylinder wall.

GT2-10 2.3.2-14

8/9/2019 2.3.2 GT Details


GT2-10BJ

BURNER ASSEMBLY

IGNTION GASINLET

FUEL OIL RETURN

FUEL OIL INLET

AXIAL SWIRLERDIAGONAL SWIRLER

FUEL GASFOR DIFFUSION

(ALSO IGNITION GAS FORLIQUID FUEL LIGHT OFF)

(NOT USED)

FUEL GASFOR PREMIX(NOT USED)

PREMIX FUELOIL INLET

(NOT USED)

8/9/2019 2.3.2 GT Details



Burner Assembly

The burner assembly for liquid and gaseous fuels is comprised of the following characteristics.

Liquid fuel burner Liquid fuel premix burner ( Not used ) Gas fuel diffusion burner ( Not used ) Gas fuel premix burner ( Not used ) Gas fuel pilot gas burner ( Not used ) Nox water orifice ( Not used ) One ignitor

Fuel Oil Burner

The amount of fuel oil injected into the combustion region through the fuel oil burner is controlled by the back pressure of the fuel oilreturn line. The total amount of fuel oil supplied by the fuel oil injection pump enters the burner and from there is fed to the axial swirlchamber. Here the flow splits and is thoroughly swirled and injected into the combustion chamber. The remaining fuel, which is not fedinto the combustion chamber, is fed to the return line of the fuel oil burner.

Ignition Gas

The main flame of the fuel oil burner is ignited with an ignition gas flame generated by the ignition transformer and ignitor that are provided on each of the eight fuel burner for each of the two combustors.

GT2-11 2.3.2-15

8/9/2019 2.3.2 GT Details


GT2-11BJ

TURBINE SECTION

1st Stage Nozzles 2nd Stage Nozzles

3rd Stage Nozzles

4th Stage Nozzles

1 Stage Blades

2 Stage Blades

3 Stage Blades4 Stage Blades

th16 Stage

th16 StageCompressor

Bleed Air

th10 Stage Compressor Bleed Air

th12 Stage

Turbine Case

ST

ND

RD

Th

Seals

Compressor Discharge

Axial Fixing

Stator BladeCarrier

Nozzles

Shroud

Blades

8/9/2019 2.3.2 GT Details



Turbine Section

The turbine case stationary blade assembly fixes the stationary blades (nozzles) in position and transmits the reaction forces of flow and pressure to the outer casing. The turbine case stationary blade assembly comprises the stationary blade carrier, the stationary blades andthe seal rings. The stationary blade carrier is suspended in the outer casing so as to accommodate thermal expansion. Its vertical alignmentrelative to the rotor is set with two opposed eccentric bolts. Lateral alignment and fixing of both upper and lower sections is also by meansof eccentric bolts. This makes it possible to change the position of the stationary blade carrier relative to the rotor, in the event of clearancechanges, without having to open the outer casing. All four eccentric bolts transmit torque from the stationary blade carrier to the casing.

The axial position is fixed by a circumferential groove in the stationary blade carrier and a corresponding partition plate / collar in thecasing, with associated shims. Axial forces are transmitted to the outer casing by these items. Jack screws in tapped bores are used tosupport the lower section during installation of the upper sections. Stationary blades are held in place by inserting their outer shrouds intocorresponding grooves in the stationary blade carriers. They are fixed circunferentially by locking pins so as to allow clearances for

thermal expansion. Gaps between adjacent blades are closed with seal elements. The inner blade shrouds of rows 1 through 4 are held in place by segmented seal rings.

Cooling air flows through the hollow spaces between the stationary blade carriers and the hollow blades of rows 1 through 4. A portion ofthis flow of cooling air is used as seal air for the seal rings in rows 2 and 3. The full volume flowing through the row 4 blades is used as sealair.

GT2-12 2.3.2-16

8/9/2019 2.3.2 GT Details


GT2-12BJ

1ST STAGE STATIONARY NOZZLE and ROTATING BLADE

NOZZLE(VANE)

BLADE

COOLING AIR

FIR TREE ROOTCOOLING AIR

COOLING AIR

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Turbine Blade and Nozzle Cooling

The stationary turbine blades (nozzles) convert the pressure energy of the hot gas flow into kinetic energy and ensure optimal flow to thenext row of turbine blades. The turbine nozzles are comprised of an outer shroud, the vane and the inner shroud or root plate. The innershroud forms the inner boundary of the hot gas path and. Stationary blade rows 2, 3 and 4, carries a ring with the shaft glands. The vanecross-section is optimized in terms of flow characteristics and strength. The vanes of all four stationary rows are hollow cast and aircooled to ensure that the maximum permissible metal temperatures specified for the materials used are not exceeded. The four stationary blade rows are cooled in a variety of ways with air under a variety of conditions. With regard to the 1st stage nozzle, thefront of the vane, the outer shroud and root plate are cooled by a combination of convection and film cooling, using sheet metal bladeinserts. The cooling air flow passes through numerous small bores in the sheet metal blade insert, impinges on the inner vane surfaceimmediately behind the insert and is mixed with the hot gas flow through bores in the vane surface. The shape and slant of the surface bores further ensure that the film of cooling air exiting these bores protects certain areas on the surface of the blade.

The rear of the vane is convection cooled, with the cooling air fed into the hot gas flow partly through slots in the trailing edge. The coolingair for the front of the vane and the root plate is introduced at the hub end between the protective shell and combustion chamber hub. Thecooling air for the outer shroud and the rear of the vane enters radially from the outside through the turbine stationary blade carrier.

With regard to the 2nd stage vane, only the intakes section of the inner shroud and the tip of the vane are impingement and film cooled. Theremainder of the vane is convection cooled, by a multi-channeled system of airways. Cooling air enters the blade radially from theoutside. From here, some of the air enters the hot gas flow through slots in the trailing edge, some passes through a penetration in the root plate to cool the root plate and some passes into an annular space below the root plate formed by an attached U-shaped seal ring, where it isused for sealing purposes.

GT2-14 2.3.2-17

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GT2-14BJ

2nd STAGE STATIONARY NOZZLE and ROTATING BLADE

TRAILING EDGECOOLING AIR HOLES

COOLING AIR

COOLING AIR FIR TREE ROOT

COOLING AIR

INSERT

NOZZLE(VANE)

BLADE

8/9/2019 2.3.2 GT Details



Turbine Blade and Nozzle Cooling ( Continued )

A sheet metal insert is welded into the vanes of the third stage to permit convection and impingement cooling. The required cooling airenters through a channel in the leading edge of the vane. A portion of this cooling air is diverted through a penetration in the inner shroud tocool the inner shroud and seal the adjoining sealing ring.

The remaining cooling air reverses direction at the inner shroud, flows outward and back to the outer shroud through the central coolingair duct where it again reverses direction and is mixed into the flow of hot gas through slots in the trailing edge.

Cooling air for the fourth stage enters the interior of the blade radially from the outside and is fed as a single flow into the attached sealring, to cool the root plate and form a labyrinth seal. Due to temperature differences between components, sufficiently large expansiongaps are required between the stationary blades in both the axial and circumferential directions.

To minimize the amount of cooling air escaping through these gaps, the circumferential gaps are sealed by inserting seal strips intoappropriate slots. The axial gaps between stationary blade rows 3 and 4 are sealed using snugly fitting covers. The axial gaps betweenstationary blade rows 2 and 3 are again sealed by inserting seal segments into appropriate slots. Guide rings between stationary blade rows1 and 2 and behind stationary blade row 4 separate the hot gas space from the cooling air space. The front guide ring is film andimpingement cooled, whereas only slight convection cooling is provided for the rear ring.

The blades are cast from high temperature alloys due to the severe stress at high metal temperatures. A protective coating is applied asnecessary to the blades to increase their resistance to hot corrosion. The first rows are additionally provided with a thermal barrier ceramiccoating.

GT2-16 2.3.2-18

8/9/2019 2.3.2 GT Details


GT2-16BJ

TURBINE BEARING HOUSING

COVER

OIL CHAMBER

OIL SUPPLY PIPE

DRAIN PIPE

LEAKAGE OIL PIPE

LABYRINTHSEAL

OIL SEAL RING

BEARING CASE

8/9/2019 2.3.2 GT Details



Turbine Case Bearing

The function of the turbine bearing casing is to support the rotor at the turbine end of the engine. The turbine exhaust case and bearingcasing is comprised of an inner cylinder, which is connected by the five radial struts. The bearing shell support sleeve is installed in theinner cylinder of the bearing casing so as to accommodate thermal expansion. The tilting pad journal bearing is bolted to the bearing shellsupport sleeve. The oil chamaber is bounded at the front by a seal ring and by a cover plate at the rear. Oil is supplied to the bearing throughthrough an oil chamber connected to the oil supply pipe. Oil is drained through the pipe screwed into the casing. The cover plate, the bearing shell support sleeve and the bearing casing are protected with a layer of thermal insulation.

The journal bearing supports the shaft in the bearing casing at the turbine end. The journal bearing is a tilting pad journal bearing.Individual tilting pad segments (three total) are lined with babbitt metal and offer optimum operating behaviour due to their sphericalseats. Lube oil is supplied to the injection nozzles through a ring duct. Jacking oil is injected at high pressure through the bottom twotilting pad segments to ensure that complete lubrication is maintained at low speeds. This reduces wear on the babbitt contact surface and

facilitates shaft rotation. Splash guards and seal rings each form the outer boundary of an annular space, in which oil emerging at the twosides of the bearing is collected and drained off.

Thermocouples monitor babbitt metal temperature at those locations subjected to the greatest thermal loading. The bearing shell supportsleeve, containing the journal bearing, is supported vertically and is a self aligning. This permits a uniform bearing clearance between the babbitt metal and the shaft journal. Adjustable wedges and are used for alignment in the vertical and horizontal directions.

TEX2-1 2.3.2-19

8/9/2019 2.3.2 GT Details


GAS TURBINE EXHAUST SYSTEM

TEX2-1

ExhaustStack

Turbine ExhaustCollector

Turbine ExhaustDucting

Silencer

Exhaust Collector

Exhaust DuctingDrain Valves

H11 AAA401

H11 AAA404

H11 - AAA403

H11

AAA402

H11 AAA405

R10 R10R10R10R10R10

CT 108 CT 102CT 103CT 104CT 106CT 107

TETETETE TE TE

8/9/2019 2.3.2 GT Details


8/9/2019 2.3.2 GT Details


Documents

2.3.2 GT Details