9e Gas Turbine PDF [PDF]

Zitiervorschau

GAS TURBINE (PG-9171E) CONTENTS 1.1

1.2

1.2.1 1.2.2 1.2.3 1.2.4 1.3 1.4

1.5

PAGE NO

PROCESS DESCRIPTION 02 1.1.1 GENERAL DETAILS 02 1.1.2 GAS TURBNE CRITERIA 02 1.1.3 CAPTIVE POWER PLANT 03 1.1.4 GAS TURBINE COMBINED CYCLE & COGENERATION 03 1.1.5 GAS TURBINE FUNCTIONAL DESCRIPTION 04 GAS TURBINE CONSTRUCTION FEATURES 05 COMPRESSOR 05 COMBUSTION SYSTEM 08 TURBINE 11 EXHAUST FRAME & DIFFUSER 18 GAS TURBINE EQUIPMENT DATA 23 GAS TURBINE CONTROLS 26 GAS TURBINE OPERATING SYSTEMS 31 1.5.1 LUBE OIL SYSTEM 31 1.5.2 COOLING WATER SYSTEM 36 1.5.3 FUEL OIL SYSTEM 38 1.5.4 ATOMIZING AIR SYSTEM 42 1.5.5 FUEL PURGING SYSTEM ( LIQUID & GAS FUEL) 45 1.5.6 GAS FUEL SYSTEM 47 1.5.7 HYDRAULIC OIL SYSTEM 49 1.5.8 TRIP OIL SYSTEM 50 1.5.9 COOLING & SEALING AIR SYSTEM 51 1.5.10 STARTING SYSTEM 54 1.5.11 FIRE PROTECTION SYSTEM 56

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GAS TURBINE (PG-9171E) HAZARDOUS GAS DETECTION SYSTEM 58 1.5.13 HEATING & VENTILATION SYSTEM 58 1.5.14 WARREN PUMP & LUBRICATION SYSTEM 59 1.5.15 INLET AIR FILTERATION SYSTEM 60 1.5.16 WATER WASH (ON LINE/OFF LINE) SYSTEM 60 GAS TURBINE FUELS 63 START-UP/SHUTDOWN SEQUENCE ON GAS FUEL 71 START UP SEQUENCE ON LIQUID FUEL 74 GAS TURBINE INSTRUMENTATION/PROTECTION 79 GAS TURBINE GENERATOR 84 GENERATOR PROTECTIONS 89 SAFETY 92 1.5.12

1.6 1.7 1.8 1.9 1.10 1.11 1.12

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SYSTEM

GAS TURBINE (PG-9171E) 1.1 PROCESS DESCRIPTION : 1.1.1 GENERAL DETAILS Gas Turbine is a Modern Power generating equipment. It takes the air from atmosphere compresses it to sufficiently high pressure , same pressurized air is then utilized for combustion , which takes place by in combustion chamber by addition of fuel , there by hot combustion products are generated which are expanded in the turbine where Heat energy of hot combustion products is converted in to mechanical energy of shaft which in turn utilized for generating power in Generator. Compression is carried out by Axial Flow compressor , Heat addition is done by Fuel in combustion chambers , Expansion of hot combustible gases is carried out in Turbine and Burnt Gases are exhausted to atmosphere or utilized for steam generation in GTs. All of these four processes are carried out in Only one Factory assembled Unit which is called Gas Turbine. Drawing shows the Typical Brayton cycle and also shows the components of Gas Turbine. Gas Turbine operates on Brayton Cycle. Brayton cycle is having divided in four segments namely Compression, Heat addition, Expansion and Exhaust. Process is explained in following diagram on T-S curve.

1.1.2 GAS TURBINE CRITERIA Gas Turbine had a following advantages • • • • • • • • • •

Capital cost is less . Fewer auxiliaries. Less erection time. Less area. Higher thermal efficiency when operated in combined cycle mode. Quick start. Fuel flexibility ( Liquid / Gas ) Very compact system. Black start facility. Suitable for Base load / Peak load / Part load operation. Page 3 of 98

GAS TURBINE (PG-9171E) • •

No/Less environmental Hazards. Control reliability.

1.1.3 CAPTIVE POWER PLANT Captive power plant has 6 Gas Turbines each is having a capacity of 126 MW. All Gas Turbines are Frame -9E machines controlled. Frame-PG 9171 E PG- Packaged Generator 9- Frame 9 17- 17 * 10,000 HP 1- Single shaft E- Machine series ISO conditions = 1.01325 Bar atm = 15 oC = 60 % RH

of

GE France make and Mark-VI

pressure( MSL)

ISO rating of Frame - 9171 Gas Turbine = 126 MW 1.1.4

COMBINED CYCLE OR CO-GEN MODE

Graph 1.1 ( c ) and will explain the suitability of Gas Turbine based combined cycle power plants over conventional steam turbine based power plant , nuclear power plants etc. In modern days Gas Turbine Based power plants are becoming more and more popular mainly because of it's higher efficiency, Reliability, Quick response. In the modern Power Plants Gas Turbine Exhaust is connected to Heat Recovery Steam Generator where the steam is generated from hot gases and Steam is utilized for running the Steam Turbine such system is known as combined cycle power plants and where steam is utilized for various processes such system is called as Cogeneration system Normally combined cycle power plant efficiency is around 48-50 % and cogeneration system efficiency is around 80 % depending up on application. Reliance Petroleum Limited at Jamnagar has combination of these both combined cycle and co-generation system. Reliance Petroleum Limited has 756 MW captive power plant , which we can call a Combined Cycle Power Plant consists of • •

6 x 126 MW Frame-9E (GE France) supplied by GE Energy Products France 2 x 30 MW MAN TOURBO( Germany ) make back pressure, non condensing steam Turbines. Page 4 of 98

GAS TURBINE (PG-9171E) Gas Turbine operates on Brayton Cycle and Steam Turbine works on Rankine cycle , In combined cycle both these cycles are combined hence such power plants are called combined cycle power plant. Typical combined cycle diagram is explained in drawing. (figure 1.C)

P u m p

3

Gas Turbine

b C om b. C ham b.

E cc o c HRSG

4 Compressor

E xhaust

E v a p S .H .

e

1

d E v a p o ra to r

Ecconomiser

c

b C ondensor

a

2

C o m b C h a m b3

C o n d e n s o r

d

S H

SteamTurbine

Temperature

2

a

4

f e S te a m T u r b in e

A x ia l G a s C o m p r e s s o r T u r b in e

f

G e n e ra to r

E n tro p y

1.1.5 GAS TURBINE FUNCTIONAL DESCRIPTION: When the turbine starting system is actuated and the clutch is engaged, ambient air is drawn through the inlet plenum assembly, filtered, then compressed in the 17th stage, axial flow compressor. For pulsation protection during start-up, the 11 th stage extraction valves are open and the variable inlet guide vanes are in the closed position. When the speed relay corresponding to 95 per cent speed actuates, the 11th stage extraction bleed valves close automatically and the variable inlet guide vane actuator energizes to open the inlet guide vanes (I.G.V.) to the normal turbine operating position. Compressed air from the compressor flows into the annular space surrounding the fourteen combustion chambers, from which it flows into the spaces between the outer combostion casings and the combustion liners. The fuel nozzles introduce the fuel into each of the fourteen combustion chambers where it mixes with the combustion air and is ignited by both (or one, which is sufficient) of the two spark plugs. At the instant one or both of the two spark plugs equipped combustion chambers is ignited, the remaining combustion chambers are also ignited by crossfire Page 5 of 98

GAS TURBINE (PG-9171E) tubes that connect the reaction zones of the combustion chambers. After the turbine rotor approximates operating speed, combustion chamber pressure causes the spark plugs to retract to remove their electrodes from the hot flame zone. The hot gases from the combustion chambers expand into the fourteen separate transition pieces attached to the aft end of the combustion chamber liners and flow towards the three stage turbine section of the machine. Each stage consists of a row of fixed nozzles followed by a row of rotatable turbine buckets. In each nozzle row, the kinetic energy of the jet is increased, with an associated pressure drop, and in each following row of moving buckets, a portion of the kinetic energy of the jet is absorbed as useful work on the turbine rotor. After passing through the 3rd stage buckets, the exhaust gases are directed into the exhaust hood and diffuser which contains a series of turning vanes to turn the gases from the axial direction to a radial direction, thereby minimizing exhaust hood losses. Then, the gases pass into the exhaust plenum ... The resultant shaft rotation is used to turn the generator rotor, and drive certain accessories. 1.2 GAS TURBINE CONSTRUCTION FEATURES Gas Turbine mainly divided in Three sections… • • •

Compressor Combustion system Turbine

1.2.1 COMPRESSOR Introduction : The axial flow compressor is consisting compressor rotor and the enclosing casing. The compressor casing consisting of Inlet Guide Vanes , 17 stages of rotor and stator balding , and 2 exit guide vanes. In the compressor air is compressed in stages by series of alternate rotor and stator airfoil-shaped blades. The rotor blade supply the force needed to compress the air in each stage and stator blade guides the air so that it enters the following rotor stage at proper angle. The compressed air exits through the compressor discharge casing to the combustion chambers. Air is extracted from the compressor for turbine cooling, bearing sealing and during start-up pulsation control. Minimum clearance between the rotor and stator blade gives the best performance, all parts are to be assembled very carefully. Compressor Rotor The compressor rotor is an assembly of 15 individual wheels , 2 stub shaft , through bolts, and compressor rotor blades. The first stage blades are mounted on the wheel portion of the forward stub-shaft.

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GAS TURBINE (PG-9171E) Each wheel and wheel portion of each stub-shaft has slots broached around its periphery : rotor blades are inserted into these slots and they are in axial position by stacking at each end of slot. The seventeenth stage wheel has long extension as a flow passage for turbine cooling air that is extracted from compressor between the sixteenth and seventeenthstage wheels. The air is used to cool: 1, 1st and 2nd stage buckets 2, 2nd stage Aft & 3rd stage forward rotor wheel space 3,Also maintains turbine rotor at Compressor Discharge Temperature(355oC) 4, 1st stage wheel space is cooled by air passes through high pressure pacing seal at aft end of compressor rotor The forward stub shaft is machined to provide the active and inactive thrust faces and journal for No.1 bearing , as well as the sealing surfaces for the No.1 bearing oil seals and the compressor low air pressure seal. Stages 5,6.7 & 8 compressor rotor blades are coated with specialized material to avoid corrosion due to moisture formation at this region Extraction air for rotor & wheel space cooling

17th stage compressor rotor blade Aft stub shaft

17th stage Compressor rotor

Specially coated rotor blades

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GAS TURBINE (PG-9171E)

Compressor stator wheel tie bolts

Compressor Stator: The stator of compressor is mainly consists of Three major sections • • • •

Inlet Casing Forward Compressor Casing Aft compressor Casing Compressor discharge casing. Inlet casing (8 struts)

Location of Combustion Chambers (14 nos)

Compressor discharge casing 11 to 17 th compressor stages, exit guide vanes & support for no:02 bearing

Aft compressor casing (5-10 compressor stages) Forward Compressor casing (4 compressor stages) Fwd leg support

Turbine Aft Leg Support water cooled

These sections, in conjunction with the Turbine shell and exhaust frame form the primary structure of Gas Turbine. They support the rotor at bearing points and constitute the outer wall of gas path. The casing bore is maintained to close tolerances with respect to rotor blade tips for maximum efficiency

The stator blade for stage 1 through 4 are mounted by similar dovetails into ring segments.The ring segments are inserted into circumferential grooves in casing and Page 8 of 98

GAS TURBINE (PG-9171E) are held in place with locking keys. In stages 5 through 17 , the stator blades and exit guide vanes are inserted directly into circumferential grooves in casing. Locking are used as with the blade ring design.

Compressor stator

Compressor stator blades

Speed pick ups probe for turbine speed measurement (total 6 nos) 3- used for normal speed measure 3- used for overspeed measurement

Bearing no:01 Eliptical Journal Loaded thrust bearing Unloaded thrust bearing

1.2.2 COMBUSTION SYSTEM Introduction : The combustion system is the reverse flow type which includes 14 combustion chambers having the components like: • • • • • • •

Combustion Liners Flow sleeves Transition pieces Cross fire Tubes Flame detectors Fuel Nozzles Spark plugs

Hot gases generated from burning the fuel in combustion chambers , are used to drive the Turbine. The photograph shows out side look of combustion system.

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GAS TURBINE (PG-9171E) In reverse flow system high pressure air from compressor discharge is directed around the transition pieces and into the annular spaces that surrounds each of 14 combustion liners. Compressor discharge air which surrounds the liner , flows radially inward through small holes in liner wall and impinges against rings that brazed to liner wall. This air then flows right toward the liner discharge end and forms a film of air that shields the liner wall from the hot combustion gases. Fuel is supplied to each combustion chamber through a nozzle that functions to disperse and mix the fuel with proper amount of combustion air. Combustion chambers Discharge air from axial flow compressor enters the combustion chambers from the cavity at the center of the unit. The air flows upstream along the outside of combustion liner towards liner cap. This air enters the combustion chamber reaction zone through the fuel nozzle swirl tip and through metering holes in both the cap and liner. The hot combustion gases from the reaction zone passes through a thermal soaking zone and then in to dilution zone where additional air is mixed with the combustion gases. Metering holes in dilution zone allow the correct amount of air to enter and cool the gases to the desired temperature. Along the length of the combustion liner and in the liner cap are openings whose function is to provide a film of air for cooling the walls of the liner and cap. The transition pieces direct the hot gases from the liners to the Turbine noz Location of spark plugs

Location of flame detectors

Location of flame detectors

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GAS TURBINE (PG-9171E) Combustion Liner

Transition Piece

Transition pieces attached to first stage nozzle

Spark plugs Combustion is initiated by means of the discharge from two high voltage , retractable electrode spark-plugs installed in adjacent combustion chambers. These spring -injected and pressure retracted plugs receive their energy from ignition transformers. At the time of firing , a spark at one or both of these plugs ignites the combustion gases in the chamber , the gases the remaining chambers are ignited by cross-fire through the tubes that interconnect the reaction zones of remaining chambers. As rotor speed increases, chambers pressure causes the spark plugs to retract and the electrodes are removed from the combustion zones.(spark plug locations at CC: 13 & 14) Ultraviolet flame detectors During the starting sequence , it is essential that an indication of the absence of flame to be transmitted to control system. For this reason , a flame monitoring Page 11 of 98

GAS TURBINE (PG-9171E) system is used consisting of four sensors which are installed on tow adjustment combustion chambers and an electronic amplifier which is mounted in the Turbine control panel. The ultraviolet flame sensor consists of flame sensor , containing a gas filled detector. The Gas within this flame sensor detector is sensitive to the presence of ultraviolet radiation which is emitted by a hydrocarbon flame. A DC voltage , supplied by amplifier, is impressed across the detector terminals. If flame is present , the ionization of gas in the detector allows conduction in the circuit which activates the electronics to give an output defining flame. Conversely , the absence of flame will generate an opposite output defining " No flame ". The four flame detectors are located in the combustion chamber No 4 , 5 , 10 , 11 out of total 14 combustion chambers. Fuel nozzles Each combustion chamber is equipped with a fuel nozzle that emits a metered amount of fuel into the combustion liner. Gases fuel is admitted directly into each chamber through metering holes located at the outer edge of the swirl plate. When liquid fuel is used , it is atomized in the nozzle swirl chamber by means of high pressure air. The atomized fuel/air mixture is then sprayed into the combustion zone. Action of the swirl tip imparts a swirl to the combustion air with the result of more complete combustion and essentially smoke free operation of the unit. Crossfire tubes The 14 combustion chambers are interconnected by means of cross fire tubes , these crossfire tubes propagate the flame to other combustion chambers.

Crossfire tube

1.2.3 TURBINE The three stage turbine section is the area in which energy in the form of high energy , pressurized gas produced by compressor and combustion section is converted in to mechanical energy. Rotor The turbine rotor assembly consists of two wheel shafts: the first, second, and third-stage turbine wheels with buckets; and two turbine spacers. Concentricity Page 12 of 98

GAS TURBINE (PG-9171E) control is achieved with mating rabbets on the turbine wheels, wheel shafts, and spacers. The wheels are held together with through bolts, Selective positioning of rotor members is performed to minimize balance corrections. The forward wheel shaft extends from the first-stage turbine wheel to the aft flange of the compressor rotor assembly. The journal for the no 02 bearing is a part of the wheel shaft. The aft wheel shaft connects from the third-stage turbine wheel to the load coupling. It includes no 03-bearing journal. Spacers between the first and second, and between the second and third-stage turbine wheels determine the axial position of the individual wheels. These spacers carry the diaphragm sealing bands. The spacer forward face includes radial slots for cooling air passages. The 1-2 spacer also has radial slots for cooling air passages on the aft face. Turbine rotor must be cooled to maintain reasonable operating temperatures and, therefore, assure a longer turbine service life. Cooling is accomplished by means of a positive flow of cool air radially outward through a space between the turbine wheel with buckets and the stator, into the main gas stream. This area is called the wheel space. The turbine rotor is cooled by means of a positive flow of relatively cool( relative to hot gas path air) air extracted from the compressor. Air extracted through the rotor, ahead of the compressor 17th stage, is used for cooling the 1st and 2nd stage buckets and the 2nd stage aft and 3rd stage forward rotor wheel spaces. This air also maintains the turbine wheels, turbine spacers, and wheel shaft at approximately compressor discharge temperature to assure low steady state thermal gradients thus ensuring long wheel life. The first stage forward wheel space is cooled by air that passes through the high pressure packing seal at the aft end compressor rotor. The 1st stage aft and 2nd stage forward wheel spaces are cooled by compressor discharge air that passes through the stage-1 shrouds and then radially inward through the stage-2 nozzle vanes. The 3rd aft wheel space cooled by cooling air that exits from the exhaust framecooling unit

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GAS TURBINE (PG-9171E) Turbine first stage rotating buckets

Turbine Rotor

Turbine second stage rotating blades

Turbine third stage rotating blades

Buckets The turbine buckets increase in size from the first stage to the third stage. Because of the pressure reduction resulting from energy conversion in each stage , an increased annulus area is required to accommodate the gas flow . The first stage buckets are the first rotating surfaces encountered by extremely hot gases leaving the first stage nozzle. Each first stage bucket contains a series of longitudinal air passages for bucket cooling. The holes are shaped and sized to obtain optimum cooling of airfoil with the minimum of compressor extraction. Like the first-stage buckets, the second-stage buckets are cooled by span wise air passages the length for the air-foil. Since the lower temperatures surrounding the bucket shanks do not require shank cooling, the second-stage cooling holes are fed by a plenum cast into the bucket shank. Span wise holes provide cooling air to the airfoil at a higher pressure than a design with shank holes. This increases the cooling effectiveness in the airfoil so airfoil cooling is accomplished with minimum penalty to the thermodynamic cycle The third stage buckets are not internally air cooled; the tips of these buckets, like the second-stage buckets, are enclosed by a shroud which is a part of the tip seal. The shrouds interlock from bucket to bucket to provide vibration damping.

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GAS TURBINE (PG-9171E)

Turbine 1st stage rotating buckets with cooling holes Bucket leading edge

Bucket trailing edge

STATOR Turbine shell : The turbine shell controls the axial and radial positions of the shrouds and nozzles. It deter-mines turbine clearances and the relative positions of the nozzles to the turbine buckets.This positioning is critical to gas turbine performance. Hot gases contained by the turbine shell are a source of heat flow into the shell. To control the shell diameter, it is important that the shell design reduces the heat flow into the shelland limits its temperature. Heat flow limitations incorporate insulation, cooling, and multi-layered structures. The external surface of the shell incorporates cooling air passages.Flow through these passages is generated by an off base cooling fan. Structurally, the shell forward flange is bolted to flanges at the aft end of the compressor discharge casing and combustion wrapper. The shell aft flange is bolted to the forward flange of the exhaust frame. Trunnions cast onto the sides of the shell are used with similar trunnions on the forward compressor casing to lift the gas turbine when it is separated fromits base. Turbine 2nd stg nozzle Turbine 3rd stage

Turbine casing

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GAS TURBINE (PG-9171E) Turbine nozzles : In the turbine section, there are three stages of stationary nozzles which direct the high velocity flow of the expanded hot combustion gas against the turbine buckets, causing the rotor to rotate. Because of the high pressure drop across these nozzles, there are seals at both the inside diameters and the outside diameters to prevent loss of system energy by leakage. Since these nozzles operate in the hot combustion gas flow, they are subjected to thermal stresses in addition to gas pressure loadings.

First stage nozzle : The first stage nozzle receives the hot combustion gases from the combustion system via the transition pieces. The transition pieces are sealed to both the outer and inner sidewalls on the entrance side of the nozzle, so minimizing leakage of compressor discharge air into the nozzles. The 18 cast nozzle segments, each with two partitions (or airfoils) are contained by a horizontally split retaining ring which is center-line supported to the turbine shell on lugs at the sides and guided by pins at the top and bottom vertical center-lines. This permits radial growth of the retaining ring, resulting from changes in temperature while the ring remains centered in the shell. The aft outer diameter of the retaining ring is loaded against the forward face of the first stage turbine shroud and acts as the air seal to prevent leakage of compressor discharge air between the nozzle and shell. On the inner sidewall, the nozzle is sealed by direct bearing of the nozzle inner load rail against the first-stage nozzle support ring bolted to the compressor discharge casing. The nozzle is prevented from moving forward by four lugs welded to the aft outside diameter of the retaining ring at 45 degrees from vertical and horizontal centerlines. These lugs fit in a groove machined in the turbine shell just forward of the first stage shroud T-hook. By moving the horizontal joint support block and the bottom centerline guide pine, the lower half of the nozzle can be rolled out with the turbine rotor in place.

Turbine first stage nozzle 18 cast nozzles (18*2)= 36

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GAS TURBINE (PG-9171E) Second stage nozzle : Combustion gas exiting from the first stage buckets is again expanded and redirected against the second stage turbine buckets by the second stage nozzle. The second stage nozzle is made of 16 cast segments, each with three partitions (or air-foils). The male hooks on the entrance and exit sides of the sidewall fit into female grooves on the aft side of the first stage shrouds and on the forward side of the second stage shrouds to maintain the nozzle concentric with the turbine shell and rotor. This close fitting tongue-and-groove fit between nozzle and shrouds acts as an outside diameter air seal.The nozzle segments are held in a circumferential position by radial pins from the shell into axial slots in the nozzle outer sidewall. The second stage nozzle partitions are cooled with compressor discharge air.

Third stage nozzle : The third stage nozzle receives the hot gas as it leaves the second stage buckets, increases its velocity by pressure drop and directs this flow against the third stage buckets. The nozzle consists of 16 cast segments, each with four partitions (or airfoils). It is held at the outer sidewall forward and aft sides in grooves in the turbine shrouds in a manner identical to that used on the second stage nozzle. The third stage nozzle is circumferentially positioned by radial pins from the shell. The turbine shell and the exhaust frame complete the major portion of the Gas Turbine stator structure. The turbine nozzles , shrouds , No-3 bearing and turbine exhaust diffuser are internally supported from these components. The turbine shell controls the axial and radial positions of the shrouds and nozzles. Resultantly, it controls turbine clearances and relative positions of the nozzles to the turbine buckets. This positioning is critical to the gas turbine performance. Hot gases contained by turbine shell are the source of heat flow into the shell. To control the shell diameter , it is important to reduce the heat flow into shell by design and to cool it to limit it's temperature. Heat flow limitations incorporate insulation , cooling, and multi-layered structures. The cylindrical portion of shell is cooled by fifth stage air flowing axially through the shell and out through holes in the aft vertical flange into the exhaust frame. The air is then used for further cooling of exhaust frame and third stage aft wheel space Structurally , the shell forward flange is bolted to the bulk head at the aft end of compressor discharge casing. The shell aft flange is bolted to the exhaust frame cast onto sides of shell are used to aid in lifting the gas turbine when it is separated from its base , should this ever by necessary.

Diaphragms : Attached to the inside diameters of both the second and third stage nozzle segments are the nozzle diaphragms These diaphragms prevent air leakage past the inner sidewall of the nozzles and the turbine rotor. The high/low, labyrinth-type seal teeth are machined into the inside diameter of the diaphragm. They mate with opposing sealing lands on the turbine rotor. Minimal radial clearance between

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GAS TURBINE (PG-9171E) stationary parts (diaphragm and nozzles) and the moving rotor are essential for maintaining low interstage leakage ; this results in higher turbine efficiency.

Shrouds : Unlike the compressor balding, the turbine bucket tips do not run directly against an integral machined surface of the casing but against annular curved segments called turbine shrouds . The primary function of the shrouds is to provide a cylindrical surface for minimizing tip clearance leakage. The secondary function is to provide a high thermal resistance between the hot gases and the comparatively cool shell. By accomplishing this function, the shell cooling load is drastically reduced, the shell diameter is controlled, the shell roundness is maintained, and important turbine clearances are assured. The shroud segments are maintained in the circumferential position by radial pins from the shell. Joints between shroud segments are sealed by interconnecting tongues and grooves.

Stage2 nozzle 16*3=48

3rd stg nozzle 16*4=64

1st stage shroud 2nd stage shroud 2nd stage Diaphragm 3rd stage diaphragm

1st stage bucket

1st stg aft outer wheelspace

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GAS TURBINE (PG-9171E) 1.2.4 EXHAUST FRAME AND DIFFUSER The exhaust frame assembly (figure here after) consists of the exhaust frame and the exhaust diffuser. The exhaust frame is bolted to the aft flange of the turbine shell. Structurally, the frame consists of an outer cylinder and inner cylinder interconnected by ten radial struts. On the inner gas path surfaces of the two cylinders are attached the inner and outer diffusers. The no.3 bearing is supported from the inner cylinder. The exhaust diffuser, located at the extreme aft end of the gas turbine, bolts to, and is supported by, the exhaust frame. The exhaust frame is a fabricated assembly consisting of an inner cylinder and an outer divergent cylinder that flairs at the exit end at a right angle to the turbine centerline. At the exit end of the diffuser between the two cylinders are five turning vanes mounted at the bend. Gases exhausted from the third turbine stage enter the diffuser where velocity is reduced by diffusion and pressure is recovered. At the exit of the diffuser, turning vanes direct the gases into the exhaust plenum. Exhaust frame radial struts cross the exhaust gas stream. These struts position the inner cylinder and n0.3 bearing in relation to the outer casing of the gas turbine. The struts must be maintained at a uniform temperature in order to control the center position of the rotor in relation to the stator. This temperature stabilization is accomplished by protecting the struts from exhaust gases with a metal fairing fabricated into the diffuser and then forcing cooling air into this space around the struts. Turbine shell cooling air enters the space between the exhaust frame and the diffuser and flows in two directions. The air flows in one direction into the turbine shell cooling annulus and also down through the space between the struts and the airfoil fairings surrounding the struts and subsequently into the load shaft tunnel and turbine third-stage aft wheelspace.

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GAS TURBINE (PG-9171E)

Exhaust Frame

Outer cylinder Inner cylinder Exhaust Frame Air Foil strut

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GAS TURBINE (PG-9171E)

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GAS TURBINE (PG-9171E) DESIGN INPUT DATA A. COMBUSTION TURBINE GENERATOR INPUT DATA Cycle description

Combined Cycle with Cogeneration

I. Combustion Turbine a. Nominal Output Rating, MW

116

b. Type of Combustion Turbine:

PG9171E

Compression Ratio

12.65 Gas/12.61 Liquid

1) heavy frame / aeroderivative c. Type of inlet air filter

Heavy frame Self-cleaning, pulse type

e. Material of Individual Inlet Air Filter Elements

Synthetic

f. CTG location (indoors/outdoors)

Outdoors

h. Diluent Injection (for NOx control) i.

Diluent filter rating (microns)

j.

Injection for power augmentation

Water N/A

k. Inlet cooling type

N/A

Effectiveness

N/A

l.

Stack (diameter / height)

30 M Height

m. Fuel Gas Conditioning Equipment n. Liquid fuel filter rating (microns) o. Number of water wash skid(s) p. Type of water wash skid (fixed or portable) q. Starting system type

To be specified by Seller 2 Fixed Motor (1.1 MW)

s. Required purge flow (percentage of ISO base load flow)

≥ 8 percent per NFPA 85

t. Lubrication oil system filter rating (microns)

10

u. Lift oil system filter rating (microns) v. Hydraulic oil system filter rating (microns) II. Generator a. Type of gen. cooling (TEWAC/hydrogen/openair) b. Generator Design Standard (ANSI / IEC) c. Type of Excitation System (static / brush less) d. Generator frequency (50/60 Hz) e. Required operating range, Hz Page 22 of 98

TEWAC IEC Brush less, feed from generator terminals 50 Hz 47.5 Hz to 52.5 Hz

GAS TURBINE (PG-9171E) (at rated voltage) f. Generator power factor range g. Generator rated terminal voltage

0.8 Lag to 0.95 Lead 14.5 KV

h. Generator surge capacitor rating (if applicable) i. Generator lightning arrestor MCOV j. Generator minimum short circuit ratio

0.56

k. Generator Phase Sequence l. Neutral bus grounding resistor assembly rating

Transformer with resistor

m. Generator line side connection 1) Bus duct (isophase/ non-segregated phase)

Iso-phase

2) Mounting location (top, side, bottom) 3) Current transformer accuracy (class) n. Generator neutral side 1) Mounting location (top, side, bottom) 2) Current transformer accuracy (class) o. Generator excitation system response time

Exciter response to be of the High Initial Type, at rated full load condition Less than 0.1 seconds

p. Governor regulation adjustable range

4% - 10%

q. System fault contribution (for power system stabilizer) r. Generator excitation minimum response ratio

2.0 static

s. Generator shaft voltage monitoring b. Bently-Nevada Vibration System (3300/3500) c. Gauges and indicators – system of units (English, SI, or both)

3500 SI

d. Gas Fuel Meter 1) Type (orifice, turbine, ultrasonic) 2) Accuracy 3) Calibration e. Liquid Fuel Flow Meter 1) Type

Coriolis meter

2) Accuracy 3) Calibration Page 23 of 98

GAS TURBINE (PG-9171E) IV. Auxiliaries a. Common lube oil/control oil system acceptable (yes/no)

Common lube oil system

V. Miscellaneous c. Thermal insulation design criteria 1) Maximum surface temperature

60°C

2) Ambient Temperature 3) Wind Velocity VII. Noise Guarantee a. Guaranteed Noise Level (sound pressure level), dBA referenced to 20μPa, measured at a distance of 1 m at a height of 2 m

1.3

85dBA

EQUIPMENT DATA

GAS TURBINE DESIGN DATA CUSTOMER SITE UNIT(S) NUMBER(S) TYPE GAS TURBINE APPLICATION CYCLE TYPE OF OPERATION ALTITUDE COMPRESSOR TURBINE

: Reliance Petroleum Limited : Jamnagar Export Refinery Project : : PG 9171 E : GENERATOR DRIVE : SIMPLE : BASE : Sea level : STAGES : 17 SPEED : 3000 R.P.M. : STAGES : 3 SPEED : 3000 R.P.M.

DESCRIPTIVE GUIDE GAS TURBINE EQUIPMENT DATA SUMMARY COMPRESSOR SECTION Number of compressor stages Compressor type Casing split Inlet guide vanes type TURBINE SECTION Number of turbine stages Casing splits Nozzles COMBUSTION SECTION Type flow

: Seventeen (17) : Axial Flow, Heavy duty : Horizontal, Flange : Modulated : Three(3) single shaft : Horizontal : Fixed Area

: Fourteen (14) multiple combustors, reverse design Page 24 of 98

GAS TURBINE (PG-9171E) Fuel nozzles Spark plugs

: One ( I ) per combustion chamber : Two (2), electrode type. Spring-injected selfretracting

Flame detectors

: Four (4) Ultra Violet Type

BEARING ASSEMBLIES Quantity Lubrication No I bearing assembly (located in inlet casing assembly) contained

: Three : Pressure lubricated : Active and inactive thrust and journal, all in one assembly

Journal Active thrust

: Elliptical : Tilting pad, self-equalizing

Inactive thrust

: Tapered land

No 2 bearing assembly (located in the compressor discharge casing) : Elliptical journal No 3 bearing assembly (located in the exhaust frame) : Journal, Tilting pad STARTING SYSTEM Starting device

: Electrical starting motor

Torque converter

: Hydraulic with adjustor drive

FUEL SYSTEM Operating type

: Natural gas + distillate fuel

Fuel control signal system Fuel pump

: SPEEDTRONIC MARK-VI control : Accessory gear-driven. Continuous Pump

output

screw type

Flow divider (starting motor)

: Circular,

Fuel oil stop valve

: Electro-hydraulic servo-control

Fuel oil filter(s) (H.P.)

: Two (2), full flow, HP strainer

Gas stop/ratio and control

: Electro-hydraulic servo-control

Page 25 of 98

free wheeling, 14 elements

GAS TURBINE (PG-9171E) LUBRICATION SYSTEM Lubricant Total capacity Main lube pump gear Auxiliary lube pump Emergency lube pump

: Petroleum base : 12,491 liters (approx.) : Shaft-driven, integral with accessory : A.C. motor-driven, submerged, centrifugal type : D.C. motor-driven, submerged, centrifugal type

vertical, vertical,

Heat exchanger(s) Type Quantity

:Oil heat to fresh water : Two (2) in parallel

Filter(s) Type Quantity Cartridge type

: Full flow with transfer valve : Two (2) : Five micron filtration pleated paper

HYDRAULIC SUPPLY SYSTEM Main hydraulic supply pump Auxiliary hydraulic supply pump

: Accessory gear-driven, variable positive displacement, axial piston : Driven by electric motor 88 HQ.

COOLING WATER SYSTEM (in closed loop) Pumps : Two (2) water pumps located on the water skid outside of the G.T. building ATOMIZING AIR SYSTEM Main compressor Starting (booster) compressor by an

: Accessory geardriven centrifugal : Axial flow, positive displacement, belt driven electric motor

Air precooler

: Air-to-water heat exchanger

PROTECTION Nox control system

: over temperature, vibration, flame detection : DM water injection method

Page 26 of 98

GAS TURBINE (PG-9171E) Expected Operating Parameters: (on Natural Gas fuel)

Firing Warm up FSNL

TNH % 12 16 100

Base Load 100

FSR % 19.8 9.5 15.7

TNR % ------100

63.2 103.6 6

GCV mm 8.8 4.2 7 28.1

FLOW NM3/hr 1649 809.16 9399.4 4 36400. 5

Expected Operating Parameters: (on Liquid fuel) TNH FSR TNR Flow divider speed % % % Hz Firing 15 19.8 ---33 No Load 100 14.5 100 240 Base Load 100 69.3 104 2277

GCV outlet pr barag --------9.7841 17.3977

FLOW L/min 17.2 126.2 603.3

Fuel Injection pr Barg ----17.2 37

No:03 bearing No: 02 bearing

Crossfire tube location Combustion chamber Total# 14 nos.

1.4

GAS TURBINE CONTROLS

BASIC CONTROL PHILOSOPHY The Gas Turbine has a number of control and protection system designed for reliable and safe operation of Gas Turbine. Control of Turbine is done mainly by start-up , speed , acceleration , synchronization and temperature control. Page 27 of 98

GAS TURBINE (PG-9171E) The figure explains the means of fuel control in relation to fuel command signal sensors monitor the turbine speed , temperature and compressor discharge pressure to determine the operating condition of Gas turbine. When it is necessary for turbine control to alter the turbine operating conditions because of changes in load or ambient conditions , it is performed by modulating the fuel flow to turbine. e.g. if exhaust temperature starts exceeding it's permissible value for given operating conditions temperature control circuit will cause a reduction in fuel supply and limit the exhaust temperature. Gas Turbine control system is designed to monitor the critical parameters which are : Temperature , Vibrations , speed , Flame , Fuel flow etc. SPEEDTRONIC DESIGN The SPEEDTRONIC system is microcomputer based system which provides analog as well as digital signals require to control and protect the turbine. Operating conditions are sensed and utilized as feedback signal to SPEEDTRONIC control system. There are three major control loops --Start-up , Speed and Temperature which may be in control during turbine operation. The output of this control loops is connected to minimum select circuit. The minimum value select circuit connects the speed , temperature and start-up control output signals to the FSR controller. The lowest voltage output of control loops is allowed to pass the gate to fuel control system as controlling FSR ( Fuel Stroke Reference ) voltage. FSR is the command signal for fuel. Switching between the control modes of speed , temperature and start-up control takes place without any discontinuity. FSR CONTROL

START-UP CONTROL BASICS : • • • • •

14 HR - Zero Speed 14 HM - Minimum firing speed 14 HC - Self sustaining speed 14 HA - Accelerating Speed 14 HS - Full Speed ( 95 % )

SPEED CONTROL The speed control system is designed to control the speed and load of turbine operating in response to actual speed signal and speed reference. While on speed control the control mode will be " Droop Speed " Page 28 of 98

GAS TURBINE (PG-9171E) DROOP OPERATION The speed control software will change FSR in proportion to the difference between the actual turbine speed and speed reference ( TNR ). Once the generator breakers are closed on power grid , speed is held relatively constant at synchronous speed , the fuel flow in excess of that necessary to maintain full speed no load , will result not in increased speed but , in increased power produced by generator. The speed control loop is acting as a load control loop and the speed reference is a convenient control of desired load on turbine generator unit. The speed control is proportional and it changes FSR in proportion to the difference between the actual turbine speed and speed reference. Thus any change in frequency will also cause proportional change in load. This proportionality is adjustable to desired regulation which is called DROOP. When entire grid system will overload the grid frequency will reduce and FSR will increase in proportion to droop settings. If all units have the same droop setting all units will share a load increase equally. Load sharing is the main advantage of this method of droop control. If 4 % droop is selected , only 1 % change in speed will produce a change in fuel flow equivalent to 25 % of rated load. Normally 4 % droop is selected and set point is calibrated such that 104 % set point will generate a speed reference which will produce FSR resulting in Base Load at design ambient temperature. See Droop v/s FSR graph Constant Settable Droop : This method of load control is applied where FSR is not predictable as a function of the gas turbine power output. This means , When the gas turbine fuel heating value is varying due to changes in fuel composition or fuel is switched between different combustion system this type of load control method is normally adopted. Constant settable droop is an inner speed control loop and outer megawatt control loop. The inner speed control loop is a proportional plus integral control whose mission is to make turbine speed TNH match the speed reference command TNRL. The outer megawatt loop formulates the droop governor response by creating a speed bias as function of unit power output. When turbine speed is held fixed by electrical grid , the turbine fuel consumption ( FSR ) and megawatt output is modified ( Constantly set ) such that TNRL reference speed command is made equal the turbine speed TNH.

Standar droop

Std droop exersize

Page 29 of 98

GAS TURBINE (PG-9171E) TEMPERATURE CONTROL Gas Turbine Firing temperature is determined by the measured parameters of exhaust temperature and CPD or exhaust temperature and fuel consumption ( FSR ). The temperature control reference program calculates the exhaust temperature control set point based on CPD and other control constants. The algorithm also calculates another set point based on FSR and its set of control constants. CPD bais : When ever CPD increases beyond pre-determined value , the compressor discharge temperature will also increases hence firing temperature will also increase , Now due to metallurgical limitations , firing temperature will not be permitted to increase beyond certain limits hence to control firing temperature CPD bias will reduce the exhaust temperature control set point and thereby reducing firing temperature. FSR bias: Fuel flow to combustion chamber will not be allowed to increase more than predetermined value , hence depending up the quality of fuel ( HSD , Kerosene , Naphtha , Gas ) and calorific value fuel , Fuel flow to the combustion chamber is limited to certain value ( FSR ) , In case fuel flow ( FSR ) increases beyond this limit , the firing temperature is going rise,hence to limit the firing temperature , temperature control set point is reduced to keep acceptable firing temperature. •

Normally this will come in line when CPD signal fails or drastic change in fuel quality. The CPD bias TTK()_C corner and CPD bias TTK()_S slop with the CPD data determines the CPD bias exhaust temperature set point The FSR bias TTK()_K corner and FSR bias TTK()_M slop with the FSR data determines the FSR bias exhaust temperature set point. The temperature-control-bias program also selects the TTK()_I Isothermal set point. The program selects the minimum of the three set points CPD bias , FSR bias and Isothermal set point for the final exhaust temperature control reference. During the normal operation of Gas Turbine with Gas or light fuel , this selection results in CPD bias control with an Isothermal limit. The CPD bias set point is compared with FSR bias set point and alarm occurs when CPD bias set point is higher than the FSR bias set point. During the normal operation of Gas Turbine with heavy fuel , this selection results in FSR bias control with an Isothermal limit. The FSR bias set point is compared with CPD bias set point and alarm occurs when FSR bias set point is higher than the CPD bias set point.

Page 30 of 98

GAS TURBINE (PG-9171E) •

Temperature reference is reduced if compressor discharge pressure signal is less than a calculated operating speed minimum. This failure is alarmed " CPD signal low ". This failure reduces the FSR bias , to permit the operation at rated firing temperature. • Temperature control reference is increased or decreased manually , but this will not affect over temperature trip and alarm set point. The temperature control fuel stroke reference algorithm compares the exhaust temperature control set point with the measured gas turbine exhaust temperature as obtained from T.C. mounted in the exhaust plenum. These signals are accessed by RST as well as by C. • TTXC is the average temperature • TTXM is the median temperature.

temp cont

temp control1

INLET GUIDE VANE AND EXHAUST TEMPERATURE CONTROL. During the normal start-up , the inlet guide vanes are held in the full closed position until the proper temperature corrected speed is reached , at which time IGV begin to open. During the Full Speed No Load or Less than 20 % load operation the IGV will remain minimum Full open position. The compressor bleed valves , which must operate in conjunction with the guide vanes to maintain compressor surge margin , will close when generator breaker is closed. When the IGV temperature control is not activated and IGV is in a simple cycle mode , the guide vanes are held at the minimum full speed angle until the simple cycle IGV exhaust temperature set point is reached. This temperature control set point is programmed in the software at approximately ( 371 deg C ) Wherever GT is installed at the exhaust of Gas Turbine which require exhaust temperature control by inlet guide vanes , the guide vanes are held at the minimum full speed angle until combined cycle IGV exhaust temperature set point is reached. The IGV temperature control set point is programmed at a value slightly lower than the BASE temperature control set point , with the CPD bias. The dark line traces a typical exhaust temperature pattern as the gas turbine output changes. Point "A" is the operating point at the end of the start-up with IGV positioned at the minimum full speed angle. As output increases , the IGV is held at this minimum angle until IGV temperature control set point is reached Point "B". Now between point "B" and point "C" IGV is opened to maintain setpoint temperature as output is further increased. At point "C" IGV is at it's full open position and upon further increase in output the turbine will reach to its Base temperature set point limit "D". The trace of exhaust temperature for IGV in simple cycle mode , from point A* to B' to C' to D for full speed no load to full load. IGV

Page 31 of 98

GAS TURBINE (PG-9171E) 1.5 GAS TURBINE OPERATING SYSTEMS: Lube oil Schematic:

1.5.1 Lube Oil system: Schematic: The lubrication system produces cooled, filtered oil for the bearing of the GT and the Generator. The lubricating provisions for the turbine, generator, torque converter and accessory gear box are incorporated in a common lubrication system which includes a main lubrication oil pump, full size auxiliary lube oil pump driven by AC motor, an emergency lube oil pump driven by a DC motor and oil tank with an oil-to-water heat exchanger, filters, a bearing header pressure regulator and a pressure relief valve The lube oil is supplied by the main lubrication oil pump (shaft driven from accessory gear) during normal stage operation of the unit or by the auxiliary AC motor driven pump during startup, turning, slowing-down and cooling periods, or by the DC motor driven pump which backs up the AC pump in some cases. These pumps are located inside the oil tank with motors on top. Temperature and pressure switches and Page 32 of 98

GAS TURBINE (PG-9171E) pressure gauges are supplied by control, indication and protection of the lube oil system. LUBRICATING OIL PUMPS: Lubrication to the bearing header is supplied by three lube pumps : 1. The main lube supply pump is a positive displacement type pump mounted in and driven by the accessory gear 2. The auxiliary lube supply pump is a submerged centrifugal pump driven by an A.C motor. 3. The emergency lube supply pump is a submerged centrifugal pump driven by a D.C motor

Main lube pump: The main lube pump is built into the inboard wall of the lower half casing of the accessory gear. A splined quill shaft drives it from the lower drive gear. The output pressure to the lubrication system is limited by a back-pressure valve to maintain system pressure.

Auxiliary Lube oil pump: The auxiliary lube pump is a submerged centrifugal type pump driven by an A.C. motor. It provides lubricant pressure during start-up and shut-down of the gas turbine when the main pump cannot supply sufficient pressure for safe operation. Operation of this pump is as follows : A low lube oil pressure alarm transmitter (96 controls the auxiliary lube pump QA-1). This low pressure level alarm causes the auxiliary pump to run under low lube oil pressure conditions as is the case during start-up or shut down of the gas turbine when the main pump, driven by the accessory drive device, does not supply sufficient pressure. At turbine start-up, the A.C. pump starts automatically when the master control switch on the turbine control panel is turned to the START position. The auxiliary pump continues to operate until the turbine reaches approximately 95 per cent of operational speed. At this point, the auxiliary (cool down) lube pump shuts down and system pressure is supplied by the shaftdriven, main lube pump. During the turbine starting sequence, the pump starts when the start signal is given. The control circuit is through the pressure level of pressure transmitter 96 QA-I. The pump will run until the turbine operating speed is reached (operating speed relay 14 HS picks up), even though the lube oil header is at rated pressure and the discharge pressure level (96 QA-1) is above alarm level setting. When the turbine is on the shut-down sequence, this pressure transmitter will signal for the auxiliary pump to start running when the lube oil header pressure falls to the point at which pressure level alarm setting is reached. Page 33 of 98

GAS TURBINE (PG-9171E)

Emergency Lube Oil Pump: The emergency lube pump is a D.C., 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 A.C. power, or for other reasons. It operates as follows : This pump is started automatically by the action of pressure transmitter 96 QA-2 whenever the lube pressure in the main bearing header falls below the pressure switch setting. If the auxiliary lube oil pump should resume operation, the emergency pump will be stopped by a pressure transmitter (96 QA-2) when the header pressure exceeds the alarm setting in speedtronic. If the auxiliary pump fail during the shut-down sequence, because of an A.C. power failure or any other cause, the emergency lube pump will be started automatically by the action of low lube oil pressure transmitter 96 QA-2 and continue to run until the turbine shaft comes to rest.

Pressure regulation: Two regulating valves are used to control lubrication system pressure. A backpressure Relief valve, VR-1, limits the positive displacement main pump discharge header pressure and relieves excess fluid to the lube reservoir. The lube pressure in the bearing Header is maintained at approximately 25 psig (i.e. 1.75 bar) by the diaphragm operated Regulating valve, VPR-2. This valve has an orifice which permits 80 per cent flow. The Diaphragm valve is operated by sensing fluid pressure in the bearing header.

Pressure and temperature protective devices: The condition of low lubricating fluid pressure is detected by a pressure switch and transmitters that open after a decrease of line pressure to a specified value and trips the unit. Pressure switch 63 QT-2A and transmitter 96 QH-1 which are installed in the lubricant feed piping on the generator side signal an alarm if the lubricant pressure drops to an unacceptable level. Likewise, thermocouples LT-TH-lA,-I B, LT-TH-ZA,-2B and LT_TH3A,3B are installed in the lubricating fluid header piping and cause an alarm to sound and the unit to trip should the temperature of the lubricant to the bearings exceed a preset limit. The settings in speedtronic for the thermocouples are such that an alarm is actuated if any one of the thermocouples detects low temperature and the turbine is tripped if any two of the thermocouples detect low temperature. Page 34 of 98

GAS TURBINE (PG-9171E) This unit has a SPEEDTRONIC control system. Before the unit is tripped by either high temperature (LT-TH-lA,-l B, LTPTH-2A,-2B and LTpTH3A,-3B), or low pressure (96 QA-1, 63 QT-2A and 96 QH-I), the cause for the trip has to be sensed by two of the three measuring devices. This ”voting logic” is to prevent a trip due to a malfunctioning sensor. Provisions are made for checking lube flow to the main turbine and generator bearings by means of oil sights and thermocouples.

Other temperature measuring and/or protective devices: There are thermocouples that can be checked by means of the T.C. selector on the gas turbine control panel : LT-TH-IA,-l B, LTPTH-2A,-2B and LT_TH3A,3B for the L.O. turbine header, LT-BI D for bearing no 1 L.O. drain, LT-B2D for bearing no 2 L.O. drain and LT-B3D for bearing no 3 L.O. drain. LT-G1D for the L.O. system bearing no 4 (generator), LT-G2D for the L.O. system bearing no 5 (generator). LT-BT1 D for the no. 1 thrust bearing drain.

Lube fluid heat exchanger : The heat exchanger system is required to dissipate the heat absorbed by the lubricating fluid and to maintain the fluid at the proper bearing header temperature. This is accomplished by circulating cooling water through the cooling tubes of the heat Exchanger as the lubricant flows over the tubes. Cooling water flow through the heat Exchanger is controlled by temperature sensitive flow regulator valve VTR 1, that maintains the correct bearing temperature. The lube fluid heat exchanger system uses a fluid-to-water cooler of the shell and tube bundle design. There is two heat exchangers, flange mounted in the lube reservoir in a horizontal position. A U-tube bundle extends into the center of the shell through which the cooling water is passed. The lube fluid flows in and out of the shell; passing over the cooling tubes of the tube bundle. Cooling water connections are made at the external steel bonnet that bolts to the shell-mounting flange through the tube sheet that supports the tubes of the tube bundle.

Main lube filtering system: Filtration of all lube oil is accomplished by a 5 micron, pleated paper filter installed in the lube system just after the lube oil heat exchanger. Two (duplex) filters are used with a transfer valve installed between the filters to direct oil flow through either filter and into the lube oil header.The duplex filters arranged side by side, are installed on the tank and connected into the pump discharge header through a manual transfer valve. Only one filter will be in service at a time, Page 35 of 98

GAS TURBINE (PG-9171E) thus cleaning, inspection, and maintenance of the second one can be performed without interrupting oil flow or shutting the gas turbine down. By means of the manually operated, worm-driven transfer valve, one filter can be put into service as the second is taken out, without interrupting the oil flow to the main tube oil header. Filters should be changed when the differential pressure transmitter 96 QQ-1 indicates a differential pressure of 15 psig (i.e. about 1.03 bar) ACCESSORY GEAR BOX : The gears are lubricated by the lube oil from the lube oil header only. These gear box contains various gears which reduces / raises speed as per the requirement of various shaft driven drives. Prominent among them were Main oil pump ( MOP ), Main Hydraulic oil pump ( MHOP ), Main atomizing air compressor. Speed of shaft#01 in RPM # Speed of shaft#02 in RPM # Speed of shaft#03A in RPM #

3000 RPM (Driving shaft) 3424.2 RPM (Pinion Shaft) 1554.2 RPM (Warren fuel oil

pump) Speed of shaft#03B in RPM #

6607.2 RPM ( Main Atomizing air

compressor) Speed of shaft#04 in RPM #

1421.9

RPM

(Main Lube oil

pump) Main Lube pump

Main shaft

Main Hydraulic pump

Accessory Gear Box internal view

Main fuel pump

MIST ELIMINATOR The main function of mist eliminator is to remove the oil vapor and to maintain the negative pressure at the tank to avoid the pressurization of tank and preventing the lube oil leakage from tank. The lube comes along with the vapor is filtered and diverted back to tank and oil vapor is thrown out to the atmosphere. Normally tank pressure is to be maintained around 50 mmwc below the atmospheric pressure. Page 36 of 98

GAS TURBINE (PG-9171E)

1.5.2 COOLING WATER SYSTEM: CW system Schematic:

3.5.1. GENERAL The cooling water system is a pressurized, closed system, designed to accommodate the heat dissipation requirements of the turbine, the lubrication system, the atomizing air system, the turbine support legs and the flame detectors. The cooling water system circulates water as a cooling medium to maintain the lubricating oil at acceptable lubrication system temperature levels and to cool several turbine components. The system normally operates at a slightly positive pressure, which results when the liquid in the system expands with the increase in temperature during operation. During operation the coolant is supplied by the owner’s cooling system and circulates through the chosen lube oil, atomizing air heat exchangers and the turbine support legs (in parallel with the other two systems of heat exchangers). After absorbing the heat rejected by these items, the coolant flows through the owner’s water cooling system where it is cooled. Page 37 of 98

GAS TURBINE (PG-9171E)

Flow regulating valves: The coolant circuit for the lube oil and atomizing air heat exchangers each have a tempera-ture actuated 3-way valve (VTR 1 and VTR 2-1, respectively) installed in the coolant inlet line to the heat exchangers. These type valves, which control coolant flow to the heat exchanger, have a manually operated device which can override the thermal element. The manual override device should be used only when the valve’s thermal element is inoperative but machine operation is required. Atomizing air compressor inlet and lube oil feed header temperatures are sensed by the bulb associated with each valve which controls the flow of coolant through the heat exchanger and maintains the air and lube oil temperatures at predetermined values. The valves automatically control flow of the medium passing through them (coolant) to the heat exchanger by responding to temperature changes affecting the bulb. The bulb contains a thermal-sensitive liquid which vaporizes when heated. Pressure thus generated in the bulb is transmitted through the capillary tube to the bellows, which positions the valve disc to control the flow of coolant through the heat exchanger. The valve is closed during turbine startup, and will start to open as the sensed fluid temperature approaches the control setting. Valve VTR 2-1 in the coolant line to the atomizing air heat exchanger has a small bypass orifice drilled into the valve body to assure that the cooler is ”flooded” at all times. At the inlet of each cooling water circuit (lube oil heat exchanger circuit, atomizing air heat exchanger circuit and turbine support legs circuit), an orifice allows water flow rate calibration to the circuit concerned. The flame detector mounts are cooled to extend the life of the flame detectors. The coolant jackets on the flame detector mounts provide a thermal break in heat conduction from the combustion can housing to the flame detector instrument. Temperature regulating valve

Temperature, pressure measuring and/or protective devices: Thermocouples, WT-TL-1,-2 at turbine support legs outlet and WT-TD, located at GT cooling system outlet, give a GT cooling water temperature indication. Page 38 of 98

GAS TURBINE (PG-9171E) Thermocouple, WT-OCD at outlet of GT lube oil heat exchanger, give a GT water temperature indication.

1.5.3 FUEL OIL SYSTEM: Liquid fuel Schematic:

The liquid fuel (distillate oil) system pumps and distributes fuel as supplied from the fuel forwarding system, to the fourteen fuel nozzles of the combustion system. The fuel system filters the fuel and divides the fuel flow into 14 equal parts for distribution to the combustion chambers at the required pressure and flow rates. Controlling the position of the fuel pump bypass valve VC3 regulates the amount of fuel input to the turbine combustion system by varying the amount of bypassed fuel. o Fuel oil strainer. o Fuel oil stop valve VSI . o Liquid fuel pump PFI. o Fuel pump discharge relief valve VR4. o Fuel bypass valve VC3. Page 39 of 98

GAS TURBINE (PG-9171E) o Flow divider or fuel distributor FDI o High-pressure fuel filters FF2-1,-2. o Fuel line check valves. o Fuel nozzle assemblies. o False start drain valves. Control devices also associated with the fuel system include : the liquid fuel pressure transmitter 96 FL-2, servo valve 65 FP that controls the fuel bypass valve, fuel pump clutch solenoid 20 CF-1, and permissive limit switches 33 FL-1 and -2 and trip relay valve VH 4 in the fuel oil stop valve trip control circuits.

Functional description of the fuel oil system: Low fuel oil strainer Fuel oil at low pressure from the fuel forwarding system, flows through a low pressure oil filter and fuel stop valve prior to entering the fuel pump. The type strainer housing contains a filter screen to remove any extraneous particulate residue left in the fuelnlines after installation. The strainer screen is to be removed after the initial 600 hours of operation and the strainer housing must be cleaned and flushed upon removal of the screen prior to placing the turbine into service. Clean fuel is normally supplied to the turbine system ; however, during this initial period the low-pressure fuel strainer prevents contaminants from entering the fuel oil stop valve and the fuel pump, thereby preventing possible damage or improper functioning of these components.

Fuel Oil Stop Valve: The fuel oil stop valve VSI is an emergency valve operated from the protection system used to shut off the supply of fuel to the turbine during normal or emergency shut downs. This stop valve is a special-purpose, hydraulically operated, two-position (open and closed) valve with a venturi disc and valve seat. When the turbine is shut down in the normal sequence, or by emergency trip operation, the fuel oil stop valve will fully close within a 0.5-second total elapsed time. During normal operation of the turbine the stop valve is held open by high pressure hydraulic oil (OH) that passes through a hydraulic trip relay (dump) valve VH4. This dump valve located between the hydraulic supply and the stop valve hydraulic cylinder, is hydraulically operated by trip oil (OLT) from the trip oil system. When the trip oil pressure is low (as in the case of normal or emergency shut-down), the dump valve spring shifts the valve spool to a position which dumps high pressure hydraulic oil (OH) in the stop valve actuating cylinder to the lube oil reservoir. The closing spring in the stop valve assembly then overcomes the oil pressure and closes the valve.

Fuel Oil Pump: The fuel pump PFI is a positive displacement continuous output screw type pump with two sets of opposed screws. The integral shaft screws are end mounted in roller bearings that are oil lubricated. The bearings and timing gears are supplied with lube Page 40 of 98

GAS TURBINE (PG-9171E) oil from the main lube oil header and are sealed off from the fuel oil pumping chamber by internal mechanical seals.

The pump is driven directly from the turbine driven accessory gear ; therefore, fuel pump speed is directly proportional to turbine speed. The fuel pump discharge flow at any given turbine speed is greater than the turbine combustion requirements at that speed. Liquid fuel pressure transmitter 96 FL-2 indicates that inlet fuel pressure is established. It is used as a permissive to energize the fuel pump clutch solenoid 20 CF-I. In case of loss of pressure while the turbine is running, 96 FL-2 will trip the turbine. An alarm 71 FP-1 or a trip 71 FP-2 are activated when appears a seal leakage on the main fuel pump.

Fuel pump discharge relief valve VR4 The fuel pump discharge relief valve, VR4, is located in a loop between the discharge and inlet of the pump. The valve prevents the fuel oil pressure from getting high enough to rupture any lines in the event of a flow divider malfunction or freeze up. This valve is set to operate in the range of 1200 to 1300 psi and relieves back into the inlet pipe.

Fuel bypass valve High pressure flow from the pump is modulated by the servocontrolled bypass valve assembly (VC3). Components of this assembly include the bypass valve body, electrohydraulic servovalve 65 FP, and the hydraulic cylinder. This bypass valve is connected between the inlet and discharge sides of the fuel oil pump and meters the flow of fuel to the turbine by subtracting excess fuel delivered by the pump and bypassing it back to the pump inlet. Servovalve 65 FP controls the bypass valve position according to the difference Requirement and the sensed fuel flow. If the fuel requirement exceeds the actual oil flow, the bypass valve closes to increase the net oil flow to the turbine. The servo valve uses high pressure hydraulic oil (OH) (cleansed of contaminants by a metal filter FH3) to actuate the hydraulic cylinder and thus position the bypass valve.

High pressure fuel filters: Fuel oil pump discharge pressure passes through the secondary (high pressure) fuel filter FF 2-1 as it flows from the fuel pump to the flow divider. This full flow, high pressure filter helps to assure that contaminants and pipe scale are retained and prevented from entering the flow divider, thereby preventing possible damage or improper Page 41 of 98

GAS TURBINE (PG-9171E) operation of this component. There are two filters FF 2-1 and FF 2-2, with a Manuel transfer valve, equipped with isolating valves. A panel mounted differential manometer is connected to indicate directly the pressure drop through the filter. There are two filters equipped with isolating valves. Filter differential pressure is controlled by 63 LF-3 pressure switch. Should the pressure increases above a preset value indicating fouling of the filter, pressure switch 63 LF-3 will cause an alarm to be annunciated.

Flow Divider: The flow divider FDI-1 equally distributes input fuel flow to the 14 combustion nozzles. The continuous flow, freewheeling flow divider consists of 14 gear pump elements in a circular arrangement having a common inlet with a single timing gear. This timing gear serves to maintain true synchronous speed of each pumping element with all other elements. As the fuel enters the flow divider, each pair of gear elements distributes one fourteenth of the fuel flow into each of the lines going to the fuel nozzles. The speed of the flow divider pumping elements is directly proportional to the fuelflow through the flow divider. Three magnetic pickup assemblies 77 FD-1, 77 FD-2 and 77 FD-3, fitted to the flow divider, produce a flow feedback signal at a frequency proportional to fuel flow delivered to the combustion chambers. This signal is fed to the SPEEDTRONIC control panel where it is used in the fuel control system.

Discharg

Flow divider

Suction

FD gear element (14 pairs)

Selector valve indicator: A 16-position selector valve and pressure gauge assembly is located at the flow divider to allow monitoring of selected fuel oil pressure in the nozzle inlet line. Positions 1 through 14 select the fuel nozzles, position 15 selects the fuel pump inlet pressure, and position 16 selects the fuel pump outlet pressure.

Check valves:

Page 42 of 98

GAS TURBINE (PG-9171E) There is a check valve (VCKI -1 to 14) in each line between the flow divider and the fuel nozzles. The check valve is mounted in each discharge line from the flow divider near the input connection to each nozzle. These valves prevent fuel oil from continuing to flow when a stop signal is given resulting in a clean cut-off of fuel to the nozzle. These check valves are set at a pressure which is sufficient to prevent the fuel from the forwarding system from breaking through, should the stop valve not close.

False start drain valves VA 17-1, -2, -5: In the event of an unsuccessful start, the accumulation of combustible fuel oil is drained through false start drain valves provided at appropriate low points in the combus-tion/turbine area. The false start drain valve, normally open, closes as the turbine accelerates during start-up. Air pressure from the discharge of the unit’s axialflow compressor shutdown sequence, the valve opens as compressor speed drops (compressor discharge pressure is reduced).

1.5.4 ATOMIZING AIR SYSTEM: Atomizing Air Schematic:

Page 43 of 98

GAS TURBINE (PG-9171E) The atomizing air system provides sufficient pressure in the air atomizing chamber of the fuel nozzle body to maintain the proper ratio of atomizing air pressure to compressor discharge pressure at approximately 1.2 or greater over the full operating range of the turbine. Since the output of the main atomizing air compressor, driven by the accessory gear, is low at turbine firing speed, a starting atomizing air compressor provides a similar pressure ratio during the firing and warm-up period of the starting cycle, and during a portion of the accelerating cycle. Continuous blowdown to atmosphere is also provided to clear the main gas turbine compressor of accumulated dirt. Major system components includes : the main atomizing air compressor, starting atomizing air compressor motor driven(88AB), atomizing air heat exchanger(s) and an air filter. When liquid fuel oil is sprayed into the turbine combustion chambers it forms large droplets as it leaves the fuel nozzles. The droplets will not burn completely in the chambers and many could go out of the exhaust stack in this state. A low pressure atomizing air system is used to provide atomizing air through supplementary orifices in the fuel nozzle which directs the air to impinge upon the fuel jet discharging from each nozzle. This stream of atomizing air breaks the fuel jet up into a fine mist, permitting ignition and combustion with significantly increased efficiency and a decrease of combustion particles discharging through the exhaust into the atmosphere. It is necessary, therefore, that the air atomizing system be operative from the time of ignition firing through acceleration, and through operation of the turbine. Air taken from the atomizing air extraction manifold of the compressor discharge casing passes through the air-to-water heat exchanger (pre-cooler) HXI to reduce the temperature of the air sufficiently to maintain a uniform air inlet temperature to the atomizing air compressor. The atomizing air pre-cooler (heat exchanger), located in the turbine base under the turbine compartment, uses water from the turbine cooling water system as the cooling medium to dissipate the heat. Thermocouple AAT-IA,-2A is sensitive to the temperature, thermoswitch provided to sound an alarm when the temperature of the air from the atomizing air precooler entering the main atomizing air compressor is excessive. When the atomizing air reaches this temperature setting of this switch, the alarm is activated. Improper control of the temperature may be due to failure of the sensor, the pre-cooler or insufficient cooling water flow. Continued operation above 275°F (i.e. 135" C) should not be permitted for any significant length of time since it may result in failure of the main atomizing air compressor or in insufficient atomizing air to provide proper combustion. Compressor discharge air, now cleaned and cooled reaches the main atomizing air compressor. This is a single stage, flange mounted, centrifugal type compressor driven by an inboard shaft of the turbine accessory gear. It contains a single impeller mounted on the pinion shaft of the integral input speed increasing gear box driven directly by the accessory gear. Output of the main compressor provides sufficient air for atomizing and combustion when the turbine is at approximately 60% speed. Page 44 of 98

GAS TURBINE (PG-9171E) Differential pressure switches 63 AD-lA,-l B and pressure transmitter 96 AD1 located ina bypass around the compressor, monitor the air pressure and indicate an alarm if the pressure rise across the compressor should drop to a level inadequate for proper atomization of the fuel. A quick connection with check valve allows reading of the pressure with a differential pressure gauge. Air, now identified as atomizing air, leaves the compressor and is piped to the atomizing air manifold with "pigtail" piping providing equal pressure distribution of atomizing air to the 14 individual fuel nozzles. When the turbine is first fired, the accessory gear is not rotating at full speed and the main atomizing air compressor is not outputting sufficient air for proper fuel atomization. During this period, the starting (booster) atomizing air compressor, driven by the starting motor 88 AB-I is in operation supplying the necessary atomizing air. The starting atomizing air compressor at this time has a high pressure ratio and is discharging through the main atomizing air compressor which has a low pressure ratio. The main atomizing air compressor pressure ratio increases within increasing turbine speed and at approximately 60 % speed the flow demand of the main atomizing air compressor approximates the maximum flow capability of the starting atomizing air compressor. The check valve in the air input line to the main compressor begins to open allowing air to be supplied to the main compressor simultaneously from both the main air line and the starting atomizing air compressor. The pressure ratio of the starting atomizing air compressor decreases to one and it is shut down at approximately 95 % speed (14 HS pickup). Now all of the air being supplied for atomizing purpose is directed to the main atomizing air main compressor, bypassing the starting air compressor completely. At this time, the 20 AB-1 solenoid is energized and the isolation valve VA 22-1 is closed preventing any air from getting to the booster compressor. This valve VA 22, actuated by regulated air with the pressure regulating valve VPR 68, will be actuated only if the solenoid valve 20 AB-1 is energized.

Recirculation cooling system: On dual fuel (gas and distillate oil) machines, the discharge of the accessory gear driven atomizing air compressor is re-circulated through the atomizing air system when the gas turbine is operating 100 percent on gas fuel ; except for a small amount of air flow that is bled off to purge the oil passages in the oil fuel nozzle. The recirculation air is passed through the atomizing air pre-cooler where it is cooled before it reenters the compressor, thus protecting the compressor against over temperature operation. Piping for the recirculation system includes a normally closed, air-operated-bypass valve (VAI 8), which is controlled by the operation of solenoid valve 20 AA. When the fuel system is set for 100 percent gas fuel operation, solenoid valve 20 AA is energized and operating air from the turbine compressor discharge is passed through filter FA4 and then admitted to the piston of bypass valve VA18. This causes the valve to open allowing the atomizing air to be re circulated back to the piping ahead of the pre-cooler HXI. Page 45 of 98

GAS TURBINE (PG-9171E)

1.5.5 FUEL PURGING SYSTEM: Air is the purge medium, supplied by the atomizing air compressor discharge for the liquid side and by compressor discharge air for the gas side. Liquid fuel purge:

For the liquid side, liquid fuel nozzle purge valve VA 19-1 let the purge air flow to each fuel nozzle. This valve is actuated by SOV 20 PL-1. Check valves VCK 2 restrict liquid fuel from filling the purge lines when the purge system is shutdown during liquid fuel operation. .

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GAS TURBINE (PG-9171E) Gas fuel purge:

Gas fuel purge valves VA 13-1 & VA 13-2 are actuated respective SOV’S hence, air flows through to the gas manifold and fuel nozzles on the turbine when the unit is on liquid fuel. Gas backflow to compressor discharge must be prevented. The gas fuel system purge valves air actuated VA13 must be closed tightly. If it does not happen, protective measures are to be taken: •

The 20 VG-2 valve vents the line to atmosphere between the purge valves VA13-1 & 2 • Pressure transmitter 96 PG will alarm if excessive pressure builds up between the valves, indicating the presence of too much gas. • 33 PG limit switches are used to indicate the position of the VA 13 valve : open or closed. Purge air pressure monitoring Each liquid and water injection purge air line, downstream of purge valve is checked for purge air pressure with respect to compressor outlet air pressure (pcD) by means of three Redundant differential pressure transmitter (I) and switches

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GAS TURBINE (PG-9171E) 1.5.6 GAS FUEL SYSTEM:

General The gas fuel system is designed to deliver gas fuel to the turbine combustion chambers at the proper pressure and flow rates to meet all of the starting, acceleration and loading requirements of gas turbine operation. The major components of a gas fuel system are the gas stop/ratio and gas control valves located in the gas fuel module. Associated with the two gas valves are the necessary inlet piping and filter, fuel vent valve, control servo valves, pressure gauges the final gas filters and the distribution piping to the 14 combustion fuel nozzles. The fuel gas stop ratio valve and the gas control valve, two independent valves, are located side by side in the gas fuel piping of the module. The gas fuel flows through the gas stop/ratio valve and then into the gas control valve on its way to the gas manifold and individual combustion chambers. The position of each valve is servo controlled by electrical signals from the gas turbine SPEEDTRONIC control system. Both the gas stop ratio valve and the gas control valve are actuated by single-acting, hydraulic cylinders. Page 48 of 98

GAS TURBINE (PG-9171E) Functional description of the gas fuel system: General: The gas control valve (GCV) and the gas stop ratio valve(SRV), although similar, each perform separate functions. The GCV meters fuel for use by the combustion chambers. It is activated by a SPEEDTRONIC control signal to admit the proper amount of fuel required by the turbine for a given load or speed. The fuel gas SRV is a dual function valve. It serves as a stop valve to shut off fuel flow to the turbine whenever required during either normal operation or in an emergency shutdown situation. The SRV also serves as a pressure-regulating valve to hold a known fuel gas pressure ahead of the GCV and enable the GCV to control fuel flow over the wide range required under turbine starting and operating conditions. Because of these dual functions the valve is sometimes called a stop/speed ratio valve. Gas Control Valve(GCV) The gas control valve VGC-1 regulates the required control valve area and utilizes an hydraulic cylinder controlled by an electro hydraulic servo-valve. The gas control valve provides a fuel gas metering function to the turbine in accordance with its speed and load requirements. The position of the gas control valve (hence fuel gas flow to the turbine) is a linear function of a Fuel stroke reference voltage (FSR) generated by the SPEEDTRONIC control. The control voltage generated acts to shift the electro hydraulic servo valve to admit oil to, or release it from, the hydraulic cylinder to position the gas control valve so that the fuel gas flow is that which is required for a given turbine speed and load situation. The gas control valve also provides a shut-off of the fuel gas flow when required by either normal operation or emergency conditions. A hydraulic trip relay (dump valve) VH12-1 is located between the electro hydraulic servo valve 65 GC-I and the hydraulic cylinders. The operation of this dump valve is the same as the trip relay (dump valve) VH 5. Gas Control Stop/Speed Ratio Valve(SRV): The gas stop/ratio valve VSR-1 is similar to the gas control valve VGC-1. The ratio function of the stop ratio/valve provides a regulated inlet pressure for the control valve as a function of turbine speed. The SPEEDTRONIC pressure control loop generates a position signal to position the stop ratio valve by means of a servo valve controlled hydraulic cylinder to provide required inter valve pressure.

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GAS TURBINE (PG-9171E) The VGC-I control valve regulates the gas flow to the primary gas manifold. Its downstream pressure is measured by the 96 FG4P pressure transmitters. In case of low pressure, a gas system trip order will be given by the speedtronic Mark VI The gas stop ratio valve VSR-1 functions as a stop valve in the fuel gas system to provide a positive fuel shut off when required by either normal or emergency conditions. Any emergency trip or normal shutdown will trip the valve to its closed position. This is done either by dumping hydraulic oil from the valve’s hydraulic cylinder or driving the position control closed electrically. Trip oil acting operates a dump valve VH 5-1 on the piston end of a spool. An hydraulic trip solenoid valve, 20 FGS-1 & 20FGC are located in the trip oil line to the dump valve. When the trip oil pressure is normal and the 20 FG-1 solenoid valve is energized to reset, the spool of the dump valve is held in a position that allows hydraulic oil to flow between the control servo valve and the hydraulic cylinder. In this position, normal control of the stop ratio valve is allowed. In event of a drop in trip oil below a predetermined limit, a spring in the dump valve shifts the spool to interrupt the flow path of oil between the control servo valve and the hydraulic cylinder. Hydraulic oil is dumped and the ratio valve closes, shutting off gas fuel flow to the turbine. 1.5.7 HYDRAULIC OIL SYSTEM Hydraulic Oil Schematic: Hydraulic oil system is mainly required for Inlet guide vane actuation, controlling liquid fuel by-pass valve and gas control valve. The major components of hydraulic oil systems are • AC motor driven hydraulic oil pump ( AHOP ) • Accessory gear driven hydraulic oil pump ( MHOP ) • Hydraulic oil filters • Relief valve VR21-1 and VR22-1 AC motor driven pump will start during the start-up of the gas turbine or due to drop in hydraulic oil pressure due to some hydraulic oil leakage in running condition. This pump will supply hydraulic oil to the IGV and fuel by-pass valve. During the normal running condition MHOP will supply the required hydraulic oil to the IGV and liquid fuel by-pass valve. Both these hydraulic oil pump takes the oil from lube header and delivers the hydraulic oil to the destination through hydraulic oil filters. Relief valve VA21-1 and VA22-1 will maintain the required hydraulic oil pressure by continuously relieving some oil to maintain the required set pressure to the oil sump. Page 50 of 98

GAS TURBINE (PG-9171E) 1.5.8 TRIP OIL SYSTEM The tripping devices which cause shut down through this system do so by dumping lowpressure oil (OLT). This is done either directly or indirectly through electro hydraulic dump valves 20 FL-I, 20 FG-1 or 20 TV-I. When oil in the trip oil line is dumped, fuel stop valves close by spring return action. At the proper point in the starting sequence, dump valves 20 FL-1,20 FG-I and 20 W-1 are energized 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. In the gas fuel circuit, dump valve VH 5 ports the gas stop/ratio valve hydraulic actuation cylinder to drain to close stop/ratio valve VSR and to servo-valve 90 SR hydraulic oil discharge port to permit stop/ratio valve control of gas fuel. VH5 is pilot operated by trip oil. Likewise, dump valve VH 12 ports the gas control valve hydraulic actuation cylinder todrain to close gas control valve VGC and to servo valve 65 GC hydraulic oil discharge port to permit gas control valve control of gas fuel. VH 12 is pilot operated by trip oil. In the liquid fuel circuit trip valve VH 4 ports the liquid fuel stop valve actuation cylinder to drain to close the stop valve and to high pressure oil to open it. Valve VH 4 is pilot operated by trip oil. The tripping devices which cause selective fuel system shut-down, do so by dumping low pressure oil (OLT). Each individual fuel stop valve may be selectively closed by dumping the flow pressure oil going to it. Dumping valve 20 FL-1 causes the trip relay on the liquid fuel valve to go to the trip state to permit closure of the liquid fuel stop valve by its spring return mechanism. Dumping valve 20 FG-1 causes the trip relays on the gas fuel stop/ratio valve and the gas control valve to go to the trip state, which permits their spring returned closure The orifice network permits independent dumping of each branch of the trip oil system by its dump valve. Tripping all devices other than the individual dump valves, will result in dumping the total trip oil system which shut the unit down. During start-up or fuel transfer, the SPEEDTRONIC panel will close the appropriate dump valve to activate the desired fuel system(s). Both dump valves will be closed only during fuel transfer or mixed fuel operation.

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GAS TURBINE (PG-9171E) 1.5.9 Cooling & Sealing air system: Cooling & Sealing air schematic:

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 buildup in these parts during normal operation and for sealing of the turbine bearings. Air from three centrifugal type blowers(88TK-1 & 88TK-2) is used to cool the turbine exhaust frame. These two motor fans are part of a cooling system located on a base, near the lower part of the gas turbine exhaust system duct. Cooling and sealing functions provided by the system are as follows: • • • •

Sealing of the turbine bearings. Cooling of internal turbine parts subjected to high temperature. Cooling of the turbine outer shell and exhaust frame. 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 : Page 52 of 98

GAS TURBINE (PG-9171E) • • • •

Turbine exhaust frame cooling blowers (88TK-1 & 2) Air filter (with poro-stone element). Pressure gauge. Dirt separator.

2. FUNCTIONAL DESCRIPTION

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 shutdown. 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 motor driven blowers. The schematic flow diagram shows both the internal and external flow of cooling and sealing air.

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 pressurized 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. .

Exhaust frame and turbine shell cooling: Cooling of the exhaust frame and turbine shell is accomplished by three electric motor-driven, centrifugal blowers, 88 TK-1 & 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 backdraft damper (check valve), VCK7-1, 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 three blowers operating simultaneously in parallel. Each blower has a pressure Page 53 of 98

GAS TURBINE (PG-9171E) switches, 63TK-1 & 63 TK-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 63 TK-1 pressure switch to close and an alarm will be annunciated. The turbine will continue to run with the automatic change over starting the blower. If all blowers should fail the turbine will be shutdown in a normal shutdown sequence.

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 shut-down. Pneumatically operated 1 1 th 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, VA 2-1, -2, -3, and -4, to the turbine exhaust plenum. Limit switches 33 CB-I ,-2,-3 & 4 are mounted on the valves to give an indication of valve position. Compressor discharge air controlled by solenoid valve 20 CB-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 blow down orifice, before the air enters solenoid valve 20 CB1. From the solenoid valve, the air is piped to the piston housings of the four extraction valves. During turbine start-up, 20 CB-I is de energized and the I I th-stage extraction valves are open allowing 1 Ith-stage air to be discharged into the exhaust plenum thereby eliminating the possibility of compressor pulsation. Limit switches, 33 CB-1 through –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 20 CB-I solenoid valve is energized to close the extraction valves and allow normal running operation of the turbine. When a turbine shut-down signal is initiated and the generator circuit breaker is opened, 20 CB-1 is de energized and 11th stage air is again discharged into the exhaust plenum to prevent compressor pulsation during the turbine deceleration period.

Pressurized air supply: Compressor discharge air is also used as a source of air for operating various airoperaPage 54 of 98

GAS TURBINE (PG-9171E) ted 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. In addition, compressor discharge pressure is monitored by redundant pressure transducers 96 CD-lA,-I B,-1 C for use in control of the gas turbine. Compressor discharge air is also the source of air used as Atomizing air if the unit has a liquid fuel system.

1.5.10 STARTING SYSTEM Schematic:

Before the gas turbine can be fired and started it must be rotated or cranked by the accessory equipment. This is accomplished by an induction motor, operating through a torque converter to provide the cranking torque and speed required by the turbine for start-up. The starting system consists of an induction motor(1100 KW) and torque converter coupled to the Accessory gear. Page 55 of 98

GAS TURBINE (PG-9171E) A motor driven torque adjustor drive, which is an integral part of the torque converter system, provides the means for adjusting torque output within specified ranges. Also control of the torque converter is achieved via an integrally mounted unloading solenoid valve 20 TU-I and a hydraulically operated dump valve. After a shut down order, when the decreasing speed reaches about 50 R.P.M, the torque converter motor sets it to the minimum torque and a motor specially provided to rotate the turbine for coo down purpose starts. It is the motor provided for turning. Turning speed value is about 120 R.P.M. Start-up function description: In the normal starting sequence, fluid is admitted into the torque converter hydraulic circuit from the lubrication system by the integral 20 TU-1 valve at the same time the starting motor 88 CR-I is energized. Breakaway is achieved and the turbine starts to rotate. The turbine begins to increase in speed and continues to accelerate until firing speed is attained and relay 14 HM picks up. When the turbine has reached this speed (14 HM setpoint), the internal geometry of the torque converter is adjusted by the torque adjustor drive 88 TM-1 to hold firing speed constant through the firing and warm-up cycle. Readjustment of the converter geometry (torque adjustment) at the end of warm-up allows the torque converter to assist in accelerating the unit up to selfsustaining speed. At this speed, (about 60 % normal speed), the torque converter hydraulic circuit is drained, by de-energizing solenoid valve 20 TU-I, at the same time cranking motor 88 CR-1 is de-energized, which effects disconnect. A crank and restart can be initiated at any time below 14 HM speed. Various switches provide, torque adjustment range limits, There are: 33 TM-5 & 6 to limit the torque in case of malfunction of the system. Shutdown: The shutdown order is given and the turbine speed slows down. When relay 14 HM drops out (at about 99 R.P.M), the turning motor88 TG-1 starts. Solenoid valve 20 TU-1 is energized and the torque is adjusted to a value allowing to turn the turbine at a speed of about 120 R.P.M for cool down purposes after shut down. This cool down sequence lasts at least 20 hours. It must be manually stopped. Turning: The turbine is at standstill and all circuits are ready for turning. The operator turns the operation selector switch 43 of the turbine control panel to position TURNING, then gives a START order. The starting motor 88 CR-1 starts and 20 TU1 is energized. When the speed reaches about 120 R.P.M., motor 88 CR-I is stopped. The speed decreases a little and at about 90 R.P.M., turning motor 88 TG-1 starts. Readjustment of the converter geometry (torque adjustment) will allow a turning speed of about 120 R.P.M. Turning will last at least 20 hours. It must be manually stopped. Page 56 of 98

GAS TURBINE (PG-9171E) 88 TM-1 is the motor that operates the buckets. The position transmitter 96 TM-1 indicates the position of the buckets on the wheels of the torque converter. TORQUE CONVERTER AND STARTING DRIVE COMPONENTS The starting motor drives the torque converter input through a flexible coupling. The torque converter output is coupled to the accessory gear and provides the required torque multiplication for the starting motor to drive the turbine. The main parts of the torque converter are the impeller driven by the input shaft, the turbine wheel which drives the output shaft, and the stator which directs fluid from the impeller to the turbine at the correct angle to produce the required output torque. 1.5.11 FIRE PROTECTION SYSTEM: Fire protection system schematic:

The carbon dioxide (CO2) fire protection system supplied is designed to extinguish fires by reducing the oxygen content of the air in a compartment from an atmosphere normal of 21 % to less than 15 % ; an insufficient concentration to support the combustion of turbine fuel or lubricating oil. System design is in accord with the requirements contained in the Fire Protection recommendations and recognizing the reflash potential of combustibles exposed to high temperature metal it Page 57 of 98

GAS TURBINE (PG-9171E) provides an extended discharge to maintain an extinguishing concentration for a prolonged period to minimize the likelihood of a reflash condition. Major system components include : CO2 tank 6000 Kg. Capacity (off-base station), discharge pipes and nozzles, pilot val-ves, fire detectors, and pressure switches. Refer to the schematic diagram CO2 is supplied from an off-base skid where high pressure CO2 from the tank connected to a distribution system which conducts the carbon dioxide through pipes to discharge nozzles located among others in the various compartments of the gas turbine unit. For the gas turbine itself, there four distinctive zones: Initial Discharge Extended Discharge Zone#01 Zone#02 Zone#03 Zone#04 Zone 1 : Accessory compartment and turbine compartment ; Zone 2 : tunnel of bearing number 3 and load shaft compartment. Zone 3 : Generator compartment ( bearing no:01 & Bearing no:02) Zone 4: Gas module compartment Two sorts of discharge are used : initial discharge and extended discharge. Within a few seconds after actuation, sufficient CO2 flows from the initial discharge system into the compartment of the machine to rapidly build up an extinguishing concentration. This concentration is maintained for a prolonged period of time by the gradual addition of more CO2 from the extended discharge system.

Functional Description: Should a fire occur in one of the protected compartments of the unit, the pilot valves in the off-base skid will be energized by one of the heat-sensitive fire detectors, more exactly : 45 FA-IA, -1B, 45 FA-2A, - 2B in the accessory compartment, 45 FA-BA,-BB in the gas module compartment, 45 FT-IA, - l B ; 45 FT-2A, -2B ; 45 FT3A, -3B in the turbine compartment and 45 FT8A, -8B, -9A, -9B in the tunnel of bearing no 3. The CO2 flow rate is controlled by the size of the orifices to the discharge nozzles in each compartment for the initial and extended discharge system. The orifices for the initial discharge must permit a rapid discharge of CO2 to quickly build up an extinguishing concentration. The orifices for the extended discharge are smaller and permit a relatively slow discharge rate in order to maintain the extinguishing concentration over a prolonged period of time. By maintaining the extinguishing concentration, the likelihood of a fire reigniting is minimized. Page 58 of 98

GAS TURBINE (PG-9171E) In the bearing no 3 zone, there is one nozzle for the initial discharge and the other is for the extended discharge. When fire is detected and CO 2 is emitted, CO2 operated latches close the shutter provided for the load shaft compartment. Note that the CO2 latches located in the ventilation path must be opened manually after a fire. the latches are provided with a limit switch preventing a gas turbine restart after a fire.

1.5.12 HAZARDOUS GAS DETECTION SYSTEM: Turbine compartment •

Four Hazardous Gas detector are located below the combustion chambers to sense any Hazardous gas or naphtha vapor.

These detectors will give alarm in the control panel but it is not connected to CO2 extinguishing system. 1.5.13 HEATING & VENTILATION:

Gravity operated dampers are used in the system to automatically provide a tight enclosure when the fire protection system is activated. The gravity closing dampers are normally held open by the pressure-operated latches, which must be manually reset after damper release. When the extinguishing agent is discharged, Page 59 of 98

GAS TURBINE (PG-9171E) pressure on the latch forces a piston against a spring moving a locking lever, which releases the latch allowing the damper to close. In the text that follows, the location of the latches is defined, as is the component on which they are mounted. Turbine compartment: Protection for the turbine compartment area is provided by a high temperature thermocouple alarm AT-TC-I. This device signals an alarm when the area temperature exceeds a preset temperature limit. Load coupling compartment: The load coupling is contained in its own enclosure and situated between the exhaust plenum and the generator. This separate compartment has its own roof section, side panels, and an access door. Thermocouple AT-LC-1 is a high temperature alarm which indicates fan failure. Heated air, after circulating through the compartment, vents upward and is exhausted through a ventilation opening with gravity operated damper closing when the extinguishing system for the turbine is activated. Fan no.

Ventilation type Zone#01 Accessory & turbine 88 BT#01 & Induced draft compartment 02 Zone#02 Load gear compartment 88 VG#01 &02 Forced draft Zone#03 Generator compartment 88 GV#01 & Induced draft 02 Zone#04 Gas valve module compartment 88 GF#01 & Induced draft 02 1.5.14 WARREN PUMP & LUBE OIL SYSTEM In warren pump fuel side and L.O side DP should be around 15-20 psi i.e L.O. pressure should be around 90 psi and fuel pressure should be around 70 psi , these pressure should be maintained throughout the operation of warren pump. There is a separate lube o skid is provided for lubricating warren pump bearings / timing gears. The lube oil used in this skid is having the high viscosity. There is one AC pump and one DC pump is provided to supply lube oil to the warren pump bearings. AC lube oil pump supplies lube oil at 120 psi pressure which passes through lube oil cooler & filter and then delivered to bearings of warren pump.

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GAS TURBINE (PG-9171E) 1.5.15 TURBINE INLET AIR SYSTEM Turbine inlet air system is consisting of 456 filter elements, which are of self cleaning type and cleaned by compressor-pressurized air. This inlet air filter's life is around 18-20 months depending up on the surrounding atmosphere. Once the filter elements are choked they are to be replaced. •

Turbine inlet air filter DP becomes high more than 200 mmwc ,

In this case machine will start unloading and it will go for zero speed. Operating Data: Compressed air: Temperature: Flow: Filtration:

8 to 16 bar 80oC (maximum) 2.9 M3/hr 10 OC 1.6

GAS TURBINE FUELS

INTRODUCTION : There are various kind of fuels can be fired in the Gas Turbine , they are divided in two types 1. Liquid Fuels • • • • •

High Speed Diesel ( HSD ) Light Distillate Oil ( LDO ) Light Cycle Oil ( LCO ) Naphtha Kerosene

2. Gaseous Fuels • •

Natural Gas Refinery Fuel Gas

LIQUID FUEL SPECIFICATIONS Specific Gravity of Fuel: The specific gravity indicates the chemical composition of hydrocarbons. A distillate with low specific gravity will be largely a paraffinic where as high specific gravity will be high aromatics. The high aromatics has a greater tendency to smoke. Specific gravity has an economic significance , normally fuel is purchased by volume. The total heat value decreases with the decreasing specific gravity. Washing of fuel becomes difficult when specific gravity approaches to on higher side i.e. near to the value of water. Flash Point : Page 64 of 98

GAS TURBINE (PG-9171E) It is the lowest temperature at which fuel produces enough vapors to produce a flash in the presence of ignition source. Flash point is the important from the fuel handling view point , other wise it is not critical to the turbine operation , It affects the requirements of auxiliary equipment like motor , relay , heaters etc i.e. they should be explosion proof. Naphtha has low flash point , while HSD has comparatively high flash point. Lower the flash point easier the burning of the fuel in Gas Turbine , hence fuels having lower flash point is preferred. Pour Point : It is the temperature of liquid where it starts flowing freely. Pour point should be in the as minimum as possible normally for HSD pour point is – 20 deg C which is desirable. Wax Content : Wax normally seen in heavy distillates. The wax is the desirable fuel component from the stand point of high heat content and high hydrogen content. It can create problems in the fuel systems, it can clog the filters , or it can clog the fuel transfer valve which needs high load for change-over of filters , It can also clog the fuel lines , flow dividers , warren pumps etc. The fuel contains high wax contents is normally maintained at high temperatures to prevent the crystals clogging. Viscosity : Viscosity of fuel is the measure of the fuel resistance to flow , It is important in the fuel auxiliary equipment and it also determines the pumping temperature , atomizing temperature and fuel pressure. For the proper operation of the Gas Turbine maximum viscosity of the fuel must not exceed 10 cst at 40 deg C , when this limit is exceeded the poor ignition , smoking , unsatisfactory combustion exit temperature , lower combustion efficiency or formation of carbon etc kinds of problems can occur. Naphtha has the lowest viscosity , hence special kinds of precautions are required. For maintaining sufficient viscosity , heating of fuel is also one technique. Sediments : Sediments in the fuel causes fouling in the fuel handling system and also in Gas Turbine fuel system , hence they should be kept as minimum as practicable. Page 65 of 98

GAS TURBINE (PG-9171E) The sediments in the fuel can be gum , resins , asphaltic material , carbon , scale, sand or mud . Poor handling of the fuel can increase the level of sediments , i.e. poor washing of fuels , washing with dirty water , improper blending etc can lead to high concentration of sediments. Normally gas turbine fuel systems are having with 5 microns filtration system which catches all dirt sediments etc. Trace Metals : Trace metals are important to analyze from the view point of deposition of particles on turbine internal parts. Normally Sodium , Calcium , Potacium, Nickel and Vanadium and present in the liquid fuels , these metals are causing Hot corrosion in the Gas Turbine components at the operating temperatures. These salts can also form hard deposits on Gas Turbine blades , which are very difficult to remove. Deposition of salt on turbine and nozzles lead to reduced out put of Gas Turbine. Sodium(Na) ,Potacium(K) , Calcium(Ca) are normally got separated by water washing process and levels of these metals can be brought down to acceptable level. But Nickel and Vanadium can not be removed by water wash as these metals are not soluble in water. These metals are present in the complex oil soluble form. The corrosive effect of vanadium can be prevented by suitable treatment of fuel by magnesium additives. The magnesium compound inhibit the corrosive characteristics of vanadium by forming high melting temperature ash , consists of magnesium sulphate , magnesium oxide , and vanadium pentoxides. Which are finally emitted along with exhaust gases. Boiling Range : Petroleum Products which consists of may components do not have any specific boiling point , these products have boiling range. The lowest temperature in the boiling range is called a Initial Boiling Point ( IBP ). The maximum temperature when all liquid is evaporated is the Final Boiling Point ( FBP ). Sulphur Content : Sulphur is the highly corrosive substance in the fuel. Suphur reacts with fuel bound hydrogen and forms H2S ( Hydrogen sulfide ) which is poisonous gas which is harmful to living substance , hence fuels having high sulphur contents are normally emitted at very high level. Sulphur also reacts with moisture and forms H2SO4 Sulhuric Acid at low stack temperatures which is very corrosive. The stack temperatures are maintained at sufficiently high enough to avoid stack corrosion. Page 66 of 98

GAS TURBINE (PG-9171E) B. FUEL SPECIFICATION

I. Natural Gas: Gas analysis ( by spices ) Component

Performance Mole %

%) Methane Ethane Propane i-Butane n-Butane i-Pentane n-Pentane n-Hexane n-Heptane n-Octane Carbon dioxide Nitrogen Hydrogen Lower heating value

Design Range Min (Vol %) Max (Vol

98.43 0.4400 0.1900 0.0275 0.0275 0.0275 0.0275 0.0000 0.0000 0.0000 0.4150 0.4150 0.0000 11728 kcal/kg

Gas supply pressure:35 Bar upstream of PCV, down stream of PCV- 25 Bar Minimum gas temperature 15°C NOTES: 1. Total butanes plus pentanes shall be within the range of 0.11% 2. Total inerts = 0.83%

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GAS TURBINE (PG-9171E) Backup liquid fuel may be any of the following: 1. 2. 3. 4.

Naphtha Keroscene Light Cycle Oil (LCO) (2-D) diesel

Naphtha Fuel Analysis Characteristic Lower Heating Value (LHV) Higher Heating Value (HHV) Kinematic Viscosity (cSt), 20°C Kinematic Viscosity (cSt), 37.8°C Kinematic Viscosity (cSt), 100°C Specific Gravity, 15.6°C Specific Gravity, 60°C Specific Gravity, 100°C Pour Point (°C) Flash Point (°C) Distillation Range (Not on Residuals) IBP 50% 90% EP Carbon Residue (Wt %) Sulfur (ppm) Hydrogen (Wt %) Nitrogen (Wt ppm) Total Ash (ppm) Trace Metals (ppm) Sodium Potassium Vanadium Calcium Lead Other metals over 5 ppm Aromatics (Vol %) Olefins (Vol %) Parafins (Vol%)

Test Method ASTM D240 ASTM D4809 ASTM D445 ASTM D445 ASTM D445 ASTM D1298 ASTM D1298 ASTM D1298 ASTM D97 ASTM D93 ASTM D86 ASTM D86 ASTM D86 ASTM D86 ASTM D86 ASTM D524 ASTM D4045 ASTM D5291 ASTM D5291 ASTM D482

Value Limits 19,500 BTU/lb

2.412 0.6738 0.67 – 0.71 -100

45 95 130 165 181 15.989 , < S > , < T > . All critical control algorithms , turbine sequencing and primary protective functions are handled by these processors. They also gathers data and generates most of the alarms. An independent protective module < P > is internally triple redundant. It accepts speed sensors , flame detectors and potential transformer inputs to perform emergency electronic over speed , flame detection and synchronizing functions. The hardware voting for < P > solenoid outputs is accomplished on a trip card associated with the module. The trip card merges trip contact signals from the emergency over speed , the main control processors , manual trip push buttons and other hard wired customer trips. Over speed and synchronization functions are independently performed In both triple redundant control and triple-redundant protective hardware, which reduces the probability of machine over speed or out of phase synchronization to the lowest availability values. Common Terminology used in Gas turbine logics: 12# 20 # 23# 26# 33# 39# 43 # 45 # 49 # 63 # 65# 71 #

overspeed mechanism solenoid valve heating device temperature switch limit switch vibration detector manual switch fire detector overload protection pressure switch servo-valve level detecting system

77# 88# 90# 96#

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Speed Sensor Electric Motor Modulating Valve Pressure Transmitter

GAS TURBINE (PG-9171E) Main Protection of Gas Turbines: The GT is tripped always through the master protective trip coil, L4T. The master protective trip includes the following trips: Protective Status Trip (L4PST): L45FTX, L45HH2, L63ETH, L63QTX, L63TFH, L86TGT; L2SFT, L39VT, L3LFLT, L63FD1_ALM, L63FLX1, L4BB; L12HF, L12HFD_C, L12HFD_P, L12H_ACC; L3SFLT (for details please check Device summary) Pre-Ignition Trip: (L4PRET): L3ACS, L27QEL, L28FDX. Post Ignition Trip :

(L4POST): L28FDT, L30SPT, L86TXT, L86TFB, L86CBT, L30BTT

Starting Means trip :

(L3SMT)

IGV trouble Trip :

(L4IGVT)

                

EXHAUST TEMPERATURE LOSS OF FLAME VIBRATION OVER SPEED EXHAUST PRESSURE LUBE OIL PRESSURE / TEMPERATURE BEARING TEMP CONTROL / TRIP OIL PRESSURE FIRE PROTECTION LOW I/L FUEL PRESSURE INLET AIR FILTER DP TURBINE COOLING PRESSURE COMPRESSOR SURGE STARTING DEVICE TRIP INLET GUIDE VANE TROUBLE TRIP FROM DRIVEN EQUIPMENT EXCESSIVE FUEL

L86TXT: Exhaust Over Temperature Trip: TTXM > TTRXB + TTKOT2 (22oC) Or TTXM > TTKOT1 (637oC) L86TFB: Exhaust Thermocouples Open Trip: TTXM < TTKXM4 (121oC) & Turbine Speed > 14HA.

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GAS TURBINE (PG-9171E) L30SPT: High exhaust temperature spread trip S=TTXSPL = (0.145 x TTXM -0.08 x CTD + 16.7) OC. S1=TTXSP1: Highest – Lowest read t/c. S2=TTXSP2: Highest – 2nd lowest read t/c. S3=TTXSP3: Highest – 3rd lowest read t/c. Trip condition…with TD 9 sec. S1>S & S2>0.8S, S1 & S2 are adjacent. S1>5S (Bad TC) & S2>0.8S, S2 & S3 are adjacent. S1, S2, S3 > S Allowable Spread Calculation: TTXSPL =

TTKSPL4 * TTXM - TTKSPL3 * CTDA + TTKSPL5

L28FDT: Loss of Flame trip : If any flame sensor fails to detect a flame, (i.e. the flame intensity goes below 80 counts) it would generate an alarm as ‘Flame Detector Trouble’. If totally 3 flames fail to detect the flame it would immediately trip the machine. L39VT: Vibration High Trip / Fired Shutdown: Vibration High Alarm Set Point Vibration High High Trip Set Point

: :

12.7 mm/sec. 25.4 mm/sec.

Trip: 1 Sensor Exceeds Alarm Level & 1 Sensor Exceeds Trip Level in Same Group. L12H: Electrical Overspeed Trip - HP TNH > 110 % (TNKHOS) L12HBLT_ALM : Over Speed Bolt Trip - HP TNH > 113 % (12HA-1) L12HFD_C: Control Speed Signal Trouble (TNH_OS – TNH) > 5% (TNKHDIF) L12HFD_P: Protective Module Over Speed Trouble – Trip (TNH – TNH_OS) > 5% (TNKDIF) L63ETH: Exhaust Duct Pressure High Trip: 2 out of 3 Trip Logic, (63ETA & 63ET1H / 63ET2H). L63 ETA L63 ET1H L63 ET2H

: 406 mmWC () - Alarm : 508 mmWC () - Trip : 508 mmWC () – Trip Page 82 of 98

GAS TURBINE (PG-9171E) L63QT: Lube Oil Pressure Low Low Trip: 2 out of 3 Trip Logic, (63QA1 & 63QT2A / 63QT2B) L63 QAL: 0.84 Kg/cm2 (↓) - Alarm L63 QT2A: 0.56 Kg/cm2 (↓) - Trip L63 QT2B: 0.56 Kg/cm2 (↓) - Trip L63 QAL: 0.84 Kg/cm2 (63QA2) – AOP Start. L63 QL2: 0.42 Kg/cm2 (63QL1) – EOP Start. L26QT: Lube Oil Header Temperature High Trip 2 out of 3 Trip Logic, (26QA & 26QT1A / 26QT1B). L26QA L26QT1A L26QT1B

: 73.88 OC () - Alarm : 79.44 OC () - Trip : 79.44 OC () – Trip

L30BTT_ALM : Bearing Metal Temperature High Trip. Any one Bearing Metal Temperature ≥ 139 oC. BTKTRP1 to 16 L63HLL / L63HGL: Trip Oil Pressure Low-Low: 2 out of 3 Trip Logic. Separate Liquid and Gas fuel trip oil pressure switches are provided and the trip would be exclusive for each fuel selection For Liquid fuel L63 HL1L: 1.4 kg/cm2 (↓) & L63 HL2L: 1.4 kg/cm2 (↓) OR L63 HL3L: 1.4 kg/cm2 (↓)

For Gas fuel L63 HG1L: 1.4 kg/cm2 (↓) & L63 HG2L: 1.4 kg/cm2 (↓) OR L63 HG3L: 1.4 kg/cm2 (↓)

L45FTX: Fire Detection Trip: Zone – 1: (320 oC) compt. Accessory Compartment Turbine Compartment

Zone-4:

Gas

valve

module

Zone – 2: ( ) Load Gear compartment Zone – 3: (80 & 100 oC) Generator Auxiliary Compartment The tripping is based upon detection by any 2-heat detectors in a single compartment or the actuation of anyone of the field push buttons. Page 83 of 98

GAS TURBINE (PG-9171E) L90TKL: Exh. Frame Cooling Air Pr. Low – Unload Under this protection the machine unloads from whatever load condition and the Generator Circuit Breaker opens on reverse power and machine remains at FSNL. (2 out of 2 Logic). L63 TK1L L63 TK2L

: 300 mmwc (↓) & : 300 mmwc (↓).

L63TFH: Inlet Air Filter DP High – Shutdown 2 out of 3 Trip Logic, (63TF1 & 63TF2A / 63TF2B). L63 TF1 L63 TF2A L63 TF2B

: 110 mmwc () - Alarm : 220 mmwc () - Trip : 220 mmwc () – Trip

L86CBT: Compressor bleed valve trouble trip During Start-Up (before L14HS), if any of the compressor bleed valves ‘CLOSE’ limit switch feedback comes until turbine complete sequence is achieved, GT will trip on Bleed valve position trouble. Conversely, after shutdown command is issued and the bleed valve ‘OPEN’ feedback doesn’t appear within 11 seconds, turbine will trip with the same alarm. L4IGVT : IGV Control Trouble Trip CSRGV – CSGV > 7.5O (during start-up) Or CSGV < 52O, LK4IGVTX (after 14HS is established).

L2SFT: Start-up Fuel Flow Excessive Trip. L2SF2L: While on liquid fuel, during start-up, if the liquid fuel flow divider speed exceeds 15% below warm-up timer gets complete, machine will trip. L2SF2G: While on Gas fuel selection, during start-up, if the GRV position feedback exceeds 10% before establishment of any flame, machine will trip L3SMT: Starting Device Trip This function monitors the speed of the turbine shaft during startup. If the turbine speed has decreased by more than the allowable setting (LK60BOG1= 5%), a time delayed trip of the starting device and turbine is initiated. This trip is not enabled during periods of coasting down from full crank speed for purge before firing.

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GAS TURBINE (PG-9171E) L63FLZ_ALM : Liquid Fuel Pr. Low. Liq. Fuel Pr. < 1 Bar (63FL2). TD 3s. L94GEN: Gen. Ventilation Trouble Shutdown 2 out of 3 Trip Logic Stator RTD: DTGSA4 ≥ 135 OC (TGKSFA) DTGSA5 ≥ 135 OC DTGSA6 ≥ 135 OC 1.10 GAS TURBINE GENERATOR General : The two pole generator uses direct air cooling for rotor winding and indirect cooling for stator winding. The losses in the remaining generator components such as iron losses , friction , windage losses and stray losses also dissipated through air. Generator consists of following components. • • • • • • • • • • • • • •

Stator Stator Frame Stator core Stator winding Stator end covers Rotor Rotor windings Rotor retaining rings Field connections Bearings Foundation frame Air filters Enclosure Generator Auxiliary Compartment

Cooling System : The heat losses arising in the generator interior are dissipated to the cooling air which is circulated through open circuit ventilation system cooling of rotor essentially eliminates hot spots and differential temperatures between adjacent components which could result in mechanical stresses. , particularly to the copper conductors , insulation and rotor body. Indirect cooling is used for the stator windings. Air Cooling System: The cooling air circulated in the generator interior by two axial flow fans arranged on rotor shaft. Cold air is drawn by fans from atmosphere through air filters. The cooling air is divided in three paths. Page 85 of 98

GAS TURBINE (PG-9171E) Flow Path –I: Path –I is directed into rotor end winding space and cools the rotor winding. Part of cooling air flows past the individual coils for cooling the rotor end winding and then leaves the end winding space via bores in the rotor teeth at the end of the rotor body. The other option of cooling air flow is directed from rotor end winding space into the slot bottom ducts from where it is discharged into the air gap via a large number of radial ventilating slots in the coils and bores in the rotor wedges ,along these paths the heat if the rotor winding is directly transferred to cooling air. Flow Path – II Path – II is directed over stator end winding to the cold air ducts and into the cold air compartments in the stator frame space between the generator housing and stator core. The cooling air then flows into the air gap through ventilation slot in the stator core where it absorbs the heat from stator core and stator winding. Flow Path – III Path – III is directed into the air gap via rotor retaining ring. The air then flows past the clamping fingers and mixes with hot air flowing via ventilating slot in the stator core into the outer hot air compartment in the stator compartment in the stator frame being returned to the coolers. The flow path mainly cools the rotor retaining rings, ends of rotor body and the end portion of stator core. The three flows mixes in the air gap. The cooling air flow radially outward through ventilating ducts in the core within range of the hot air components for cooling further portions of the stator core and winding. Stator Frame: The stator frame is of welded construction and supports the laminated core and the windings. Both the air duct pipes and welded radial ribs provide the rigidity of the stator frame. Footings are provided to the stator frame to support the stator on foundation. The stator is firmly fixed to the skid with bolts to through the footing. Stator Core : The stator core is stacked from insulated electrical sheet-steel laminations with a low loss index and suspended in the stator frame from insulated dovetailed guide bars. Axial compression of the stator core is obtained by clamping fingers , pressure plates , and non-magnetic clamping bolts , which are insulated from the core. The clamping fingers ensure a uniform clamping pressure , especially within the range of the teeth and provide for uniform , intensive cooling of the stator core ends. Construction : The stator winding is a short pitch two-layer type consisting of individual bars located in slots of rectangular cross-section which are uniformly distributed on the circumference of the stator core. Page 86 of 98

GAS TURBINE (PG-9171E) In order to minimize the losses, the bars are composed of separately insulated strands which are transposed by 360 degrees Resin-Rich High Voltage Insulation: The high voltage insulation is provided according to proven “ Resin-rich mica base of thermosetting Epoxy ‘ system. Several half –overlapped continuous layers of resin rich mica tape are applied over the bars and the insulation is cured under temperature and pressure in a precisely manufactured mould. The number of layers of thick ness of the insulation depends on the machine voltage. The high voltage insulation obtained is void free and characterized by its excellent electrical , mechanical and thermal properties. Its moisture absorption is extremely low and oil resistant. The behavior of insulation is far superior to any other conventional mica insulation system. To minimize the corona discharge between the insulation and slot wall , a final coat of semi conducting varnish is applied to the surface of all bars within the slot range. In addition , all bars are provided with an end corona protection to control the electric field at transition from the slot to the end winding and to prevent the formation of creepage spark concentrations. Stator Winding Protection: To protect the stator winding against the effects of magnetizing forces due to load and to ensure permanent firm seating of the bars in the slot during operation , the bars are inserted with very small lateral clearances , a curing slot bottom equalizing strip , and top ripple spring located beneath the slot wedge. In the end windings , the stator winding is firmly lashed to supporting brackets with neoprene rubber coated glass sleeves. Spaces Blocks arranged between the bars ensure a short-circuit-proof support structure. The stator winding is connected in the generator interior. The stator winding connections are brought out to output leads located at exciter end. Rotor Shaft : The rotor shaft is a single piece solid forging manufactured from a vacuum cast steel ingot. Slots for insertion of field winding are milled into rotor body. The longitudinal slots are distributed over the circumference so that two solid poles are obtained. To ensure that only high quality forging are used , strength tests , material analysis , and ultrasonic tests are performed during manufacture of the rotor. After completion , the rotor is balanced in various planes at different speeds and then subjected to an over speed test at 20 % of rated speed for two minutes. Rotor Winding and Rotor Retaining Rings : The rotor winding consists of several coils which are inserted into the slots and seriesconnected such that two coil groups form one pole. Each coil consists of several series connected turns which are connected by brazing in the end section. Page 87 of 98

GAS TURBINE (PG-9171E) The rotor winding consists of silver-bearing copper ensuring an inserted thermal stability. The individual turns of the coils are insulated against each other by interlayer insulation. L-shaped strips of laminated epoxy glass fiber fabric with Nomex filler are used for slot insulation. The slot wedges are made of high electrical conductivity material and thus act as damper winding. At their ends the slot wedges are shortcircuited through the rotor body. The centrifugal forces of the rotor end winding are contained by single-piece rotor retaining rings. Retaining rings are made of non magnetic high strength steel in order to reduce stray losses. Each retaining ring with its shrink fitted hub is shrunk on to the rotor body in an overhung position. The retaining ring is secured in the axial position by a snap ring. Field Connections and Multi-Contacts: The field current is supplied to the rotor through multi-contact system arranged at the exciter side shaft end. The generator rotor is supported in two sleeve bearings. To Eliminate shaft currents the exciter end bearing is insulated from the foundation frame and oil piping. The temperature of each bearing is monitored with two RTDs embedded in the lower bearing sleeve so that the measuring point is located directly below the babbitt. Measurement and any required recording of temperature are performed in conjunction with the turbine supervision. All bearings , have provisions for fitting vibration pickups to monitor shaft vibrations. The oil supply to the bearing is obtained form turbine oil system. Exciter : The exciter consists of • Rectifier Wheels • Three-phase main exciter • Three-phase pilot exciter • Metering and supervisory equipment. The three phase pilot exciter has revolving field with permanent magnet poles. The three phase AC is fed to the field of revolving-armature main exciter via stationary regulator and rectifier unit. The three phase AC induced in the rotor of main exciter is rectified by rotating rectifier bridge and fed to the field winding of the generator rotor through the DC lead in the rotor shaft. A common shaft carries the rectifier wheels , the rotor of the main exciter and permanent magnet rotor of the pilot exciter. The shaft is rigidly coupled to the generator rotor and supported on end shield. The generator and exciter rotor are thus supported on a total of three bearings. Mechanical coupling of the two shaft assemblies results in simultaneous coupling of the DC leads in the central shaft bore through the MULTICONTACT electrical contact system consisting of plug-in bolts and sockets. This contact system is also designed to compensate for length variations of the leads due to thermal and sockets. This contact systems is also designed to compensate for length variations of the leads due to thermal expansion. Page 88 of 98

GAS TURBINE (PG-9171E) Rectifier wheels : The main components of the rectifier wheels are silicon diodes , which are arranged in the rectifier wheels in a three phase bridge circuit. The contact pressure for the silicon wafer is produced by a plate spring assembly. The arrangement of diode is such that this contact pressure is increased by the centrifugal force during rotation. One diode each is mounted in each light metal heat sink and thus connected in parallel , associated with each diode is a fuse which serves to switch off the diode if it falls ( Loss of reverse blocking capability ). The R-C ( Resistance –Capacitance ) net work is also provided for suppression of momentary voltage peaks arising from commutation , each wheel. The insulated and shrink fitted wheels serve as a DC bus for negative and positive side of rectifier bridge. This arrangement ensures good accessibility of all components and minimum circuit connections. The three phase alternating current is obtained via copper conductors arranged on the shaft circumference between rectifier wheels and the three phase main exciter . The conductors are attached by means of banding clips and equipped with screw –on lugs for internal diode connection. One three phase conductor is provide for each diode. The conductor originate at bus ring system of main exciter. Three Phase Pilot Exciter : The three phase pilot exciter is a six pole revolving-field unit. The frame accommodates the laminated core with the three phase winding. The rotor consists of a hub with mounted poles. Each pole consists of separate permanent magnets which are housed in a non-magnetic metallic enclosure. The magnets are braced between the hub and the external pole shoe with bolts. The rotor hub is shrunk onto the free shaft end. Three Phase Main Exciter : The three phase main exciter is a six pole revolving armature unit. Arranged in a frame are poles with the field and damper winding. The filed winding is arranged on laminated magnetic poles. At the pole shoe , bars are provided which are connected to form a damper winding. Between two poles a quadrature-axis coil is fitted for inductive measurement of the field current. The rotor consists of stacked laminations which are compressed by through bolts over compression rings. The three phase winding is inserted in the slots of laminated rotor. The winding is inserted in the slots of laminated rotor. The winding conductors are transposed within the core length , and the end turns of rotor winding are secured with steel bands. The connections are made on the side facing the rectifier wheels , the winding ends are run to a bus ring system to which three phase leads leading to the rectifier wheels are also connected. After full impregnation with synthetic resin and curing , the complete rotor is shrunk onto the shaft.

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GAS TURBINE (PG-9171E) 1.11 GENERATOR PROTECTIONS : Gas Turbine generator comprises following protections. Following generator protections are handled by LGPG relay. • • • • • • • • • • • •

Differential Protections Over current Reverse Power Over frequency Under frequency Negative phase sequence Neutral displacement Stand-by earth fault Low forward power PT failure Over voltage Field failure

Following Generator-Transformer protections are handled by KBCH relay. • • • • •

Over all differential Restricted earth fault Over fluxing Transformer alarm Transformer trip

Following Transformer protection is handled by KCGG relay. •

Transformer Stand-by Earth fault

Following Generator protection is handled by M2TU-34 relay. •

Back-up Impedance

Following Generator protection is handled by MYTU-34 relay. • Pole slipping Following Generator protection is handled by 64F MRSU04 relay. •

Rotor Earth fault

Differential Protection : This protection protects the generator against winding faults i.e. phase to phase and phase to ground fault. This protections checks the current across the generator windings , summation of current should always be zero theoretically for normal operation. Page 90 of 98

GAS TURBINE (PG-9171E)

External Faults : This protection does not respond to external fault and overloads , as in case of external fault current sent by Upstream and down-stream CT will be zero hence relay will not operate. Internal Faults : On the contrary it will respond to internal fault ( One phase earthed ) , here current sent by upstream and down stream CT will not be zero hence relay will operate. Thus ,this protection provides complete protection against phase to phases faults and internal faults. This protection provides protection against ground faults to about 80 – 85 % age of generator winding. It does not provide 100 % protection of windings because it is influenced by magnitude of earth fault current which depends up on method of grounding.

Restricted Earth Faults : When neutral is solidly grounded , it is possible to protect complete generator windings against phase to ground faults , but generally neutral is earthed through and impedance to limit the earth fault current. This scheme provides generator windings only against ground faults. It does not protects against phase faults. For this reason this protection is also termed as restricted earth fault. For protecting generator winding by 100 % Restricted earth fault relay is used. Negative Phase Sequence : The negative sequence currents in stator , resulting from unbalance loading , produces a reaction field rotating at twice synchronous speed with respect to rotor and induce double frequency currents in the rotor. This current is very large and result in severe heating of rotor , therefore amount of negative sequence current existing for any appreciable time must be strictly restricted. The length of time that a generator is allowed to operate with unbalance stator current without danger of permanent damage is obtained from equation I22 x T=K where K is constant depending up on the machine. While I2 is the negative phase sequence current over time T second.

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GAS TURBINE (PG-9171E)

Pole Slipping : In case of system disturbances after operation of circuit breaker or when any heavy load throw off , the generator rotor may oscillate. Consequently variations in current , voltage and power factor may take place. Such oscillation may disappear in few seconds , therefore in such situation tripping is not desirable. In some cases angular displacement of rotor exceeds the stability limit and rotor slips a pole , If disturbance is over , generator may regain it’s synchronism. Alternative approach is to trip the field and allow the machine to run as asynchronous machine , thereby removing the oscillations from the machine. Loss of Excitation : Failure of the field system results in a generator operating above synchronous speed as an induction generator , drawing a magnetizing current from the system> provided the system is capable of supplying additional reactive power for excitation , which can be greater than full load rating of the machine there is no risk of system instability , However over loading of stator and over heating of rotor result from continuous operation , therefore machine should be disconnected and shut-down if the field can not be restored. Stator Earth fault : When a generator is earthed through high impedance to limit fault current , differential protection does not protect 100 % of stator winding against the earth fault. Hence a separate sensitive earth fault protection is required. Following two methods are normally used for grounding a generator neutral. • Neutral connected through resistor which limits the earth fault current to much lower value than full load current. • Neutral is grounded through voltage transformer. The earth fault current is limited to magnetizing current of VT plus zero sequence current of generator. In resistance earthing two earth fault relays may be provided on secondary side of neutral CT. The first earth fault relay is set at 10 % and is of instantaneous type. The second earth fault relay is set at 5 % i.e. relay will pick-up when earth fault current is 5 % of full load current. Depending up on the sensitivity , the first earth fault relay would protect about 90 % of stator winding and second earth fault relay will protect about 95 % of stator winding. When neutral is connected through voltage transformer , the rated primary voltage of VT is generally equal to phase to neutral voltage of generator. The grounding resistor is connected to secondary of grounding transformer and relay is connected across the Page 92 of 98

GAS TURBINE (PG-9171E) resistor. During the ground fault , when a set voltage develops across the resistor , the relay operates. The setting of relays is 10 % of rated secondary voltage of VT.

Rotor Earth Fault : Single earth fault on the field winding or in the generator circuit of generator is not in itself very danger to the machine. If second earth fault develops , part of field winding will short circuited resulting in magnetic unbalance of field system with subsequent mechanical damage to the machine bearings. Three methods are available for rotor earth fault protection. • Potentiometer Method • A.C. Injection Method • D.C. Injection Method Potentiometer Method This scheme comprises a central tapped resistor connection in parallel with the main field winding. The center point of the resistor is connected to earth through over voltage relay. Thus , any earth fault on the field winding will produce a voltage across the relay terminals , maximum voltage occurring for faults at extreme end of winding , reducing to aero for faults at the center of winding. A.C. Injection Method It comprises an auxiliary transformer , one side of the secondary being earthed , the other end being connected via a relay and capacitor in series to either the start or finish of main field winding When an earth fault occurs the relay circuit is completed , the current through the relay being independent of the exciter voltage and the function only of the fault resistance D.C. Injection Method This method is similar to AC injection method , and comprises a transformer / rectifier bridge , the positive DC node of the bridge being earthed , the other node being connected via relay and limiting resistor to the positive end of main field winding. 1.12 SAFETY SAFETY PRECAUTIONS Safety is everyone's business. It is to be noted that GTs were operating safely for the last few decades. By observing the following few simple precautions one can have safe and happy operations of GT throughout its life period.

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GAS TURBINE (PG-9171E) Proper installation, operation and maintenance are essential for safe and reliable operation. Precautions taken should consist of but not limited to, hearing protection, eye protection, protective clothing as required for the task being performed.

When replacing instrumentation, always isolate the instrument with root valves and release the pressure with the instrument vent or the blow off line. CAUTION: do not try to repair an instrument when under pressure. Isolate the instruments by closing the tandem valves and make sure that the valves are holding. After this, drain the line if possible and then only try to remove the instrument. GT OUTAGE : Whenever outage of GT for major upgrades or maintenance require the a positive isolation of fuel flow going to the fuel system . CO2 extinguishing system should be isolated as it should not release due to any mal operation as same can affect the people working around. Gas Turbine should be sufficiently cooled down to appropriate temperatures so that working manpower can comfortably work. Gas Turbine Control system Mark-V power supply should be switched off after stopping lube oil system. Ensure all the required blinding , isolation before releasing Gas Turbines for combustion inspection , Hot Gas Path Inspection or Overhauling. Walk Down check Off: One of the most important benefits of a "WALK DOWN CHECK OFF" of a Gas Turbine is derived from the operator keeping his eyes and ears open for any unusual conditions and reporting his findings to his supervisor. Potential damage to equipment can be avoided if abnormal conditions are detected in time. The following are some of the items that an operator should be looking for: General: 1. Look for unusual traces of fuel , oil water on the floor or leaking from fuel lines . 2. Ensure that entire fuel is drained out from the system.. 3. Be on the look out for any unusual condition (discoloration, hot spots etc.) on Gas Turbine parts. 4. Check for unusual noises overheating of bearings and adequate lubrication of all driven motor and equipments. Daily checks Page 94 of 98

GAS TURBINE (PG-9171E) The following are some specific items that should be observed at least once a day: • • • • •

Look for leaks in fuel system. Check for rubbing noise. Look for lube oil level & leaks. Look for any air leak Look for any hot gas leak.

Gas Cylinders : In the refinery complex chlorine, ammonia, CO2, Oxygen, acetylene and other inert gases are supplied, transported and used in cylinders. They are basically two types of containers used for the supply of these gases. The cylinders are small containers with net carrying capacity of 30 kgs to 100 kgs. The bigger containers are having a capacity of 900 kgs to 1000 kgs and are generally termed as tonners. For handling compressed gas cylinders, one should be thoroughly conversant with properties and characteristics of these gases. There are several precautions and safe practices, which should be taken care of considering the nature of the gas and the pressure to which the cylinders are subjected. Handling, storage and transport of the cylinders are covered under gas cylinder rules 1981. Some of the precautions to be taken while handling and storing are given below. 1. Cylinder shall be stored in a cool, dry, well ventilated place under cover away from Gas Turbines, open flames, steam pipes or any potential sources of heat and such place of storage shall be easily accessible. 2. The storage room or shed shall be fire resistant construction. 3. Cylinder containing flammable gases and toxic gases shall be kept separated from each other and from cylinders containing other type of gases by an adequate distance or by suitable partition wall. 4. Cylinder shall not be stored under conditions, which cause them to corrode. 5. Empty cylinders shall be segregated from the filled ones and care shall be taken that all the valves are tightly shut. 6. Cylinders shall not be stored along with any combustible materials. 7. Oxidizing gas cylinders should be stored away from the flammable gas cylinders. 8. Cylinders should be kept in vertical position with chains. 9. They should be transported only on the cylinder trolley. 10. It should not be allowed to collide and rolled on the ground. 11. Colour of the gas cylinders is standardized as per IS code. Hence it should nor never be painted with any colour other than specified. Page 95 of 98

GAS TURBINE (PG-9171E) 12. Welding any gas cutting of any cylinders is prohibited. 13. Magnet should not be used for lifting cylinders. 14. Cylinders having corrosive, toxic gas must be stored in an open godown. 15. While unloading the cylinders from the tricks, it should not be dropped from the height. 16. The cylinders kept must be always fixed to avoid any damage to the cylinder valve. Fire Hydrant System There is a four pumps three diesel engine driven and one is the motor driven pump called a jockey pump which maintain the fire net-work hydrant pressure 10.5 Kg/cm2. Jockey pump start stop automatically as per the hydrant pressure it will start at 8Kg/cm2 and stop at 10.5Kg/cm2 (g). If the hydrant valves open to extinguish the fire water flow is not sufficient then the header pressure drop then Diesel engine driven pump No. C, No. B, No. A will start at header pressure 7,6,5Kg/cm2(g) respectively. Fire hydrant net work drawing is attached herewith Fire water is not to be used for extinguishing fire in Gas Turbine. Portable DCP fire extinguishers are provided around the Gas Turbine like for extinguish the fire chance of firing near a fuel firing skid. Location of the DCP type portable fire extinguisher shown in sketch here attached with. HAZOP and HAZAN Hazard operability (HAZOP) and hazard analysis (HAZAN) by definition are “ the application of a formal systematic critical examination to the process and engineering intentions in order to assess the hazard potential due to the malfunction of individual equipment effect or facility as a whole” HAZOP Study: It is the application of guidewords in systematic and critical study of a process or engineering intentions. This step enables us to discover the following • • • •

conceivable and meaningful deviations their causes visualize their consequent hazard potential Methods to eliminate or mitigate hazards by suggesting suitable hardware or software modifications.

The guide words are in the list below • No Flow • Less Flow Page 96 of 98

GAS TURBINE (PG-9171E) • • • • • • •

Reverse Flow Less Temperature High Temperature Low Pressure High Pressure As Well As Other Than Etc.

These guide words stimulate the persons to discover the deviations from design & operating intentions of the plant. / System. Annalists use std HAZOP sheets to study , record the findings and suggesting solutions (recomm). A team consisting of engineers from the disciplines of project, process, instrument and others with requisite know how handle HAZOP studies. Their start from the conceptualization and continue till plant commissioning. HAZOP studies may be require even in running plants. HAZOP analysis Hazard analysis is the term that describe the application of numerical methods to solve safety problems, which consists of three stages 1. estimating how often the incident will occur 2. Note the consequences of the incident on the employees plants and profit. Use past experience as applicable 3. Comparing the results of (1) and (2) action taken to minims the probability of occurrence or consequences of the hazard. Accident Fire or explosion of various types as discussed below causes most of the accidents in the HC industry. There are basic requirements for a fire or an explosion to occur, namely fuel, air and source of ignition. Fire and gas detection systems: The system detects fire or gas release and initiates audible and visual alarm in the main control room. This helps in immediate fire fighting and eliminating problems Types of fire detectors: Combined UV and IR detectors: Principle: The wavelength of radiation from a flame in the UV-IR range. Light hydrocarbons and coke forms the two extreme ends of the flame category. H to C ratio of the fuel is the factor for the characteristics of a flame like colour and smoke depend on the ratio of H to C. fuels of low hydrogen burn with a highly smoky flame. UV-IR detectors installed in process areas detect all flames except those smoky. These devices are very reliable and hence a single detector for each point is adequate. Page 97 of 98

GAS TURBINE (PG-9171E) Smoke Detectors : There are two kinds of smoke detectors. Ionization type and optical type> they are placed in areas where the flame will be smoky. The smoke hides the flame and renders the UV-IR detectors ineffective. Hence UV-IR are not suitable for such areas. Heat Detectors : These kind of detect are placed in areas like tank farms etc. Flammable Gas Detectors : These detect leaks of flammable gases. The detect initiate alarms if the flammable gas vapors are present in a certain percentage toxic gas detector. These detect the presence of toxic gases such as SO2 and CO2. They are semiconductor devices immune to poisoning. The detectors are placed at a height of 1.5 meter, the breathing zone of human beings. Active Fire Protection system : RPL has an extensive fire fighting system all ovens the plant and port facilities to effectively fight fires should one occur. This way damage to equipments and injuries are prevented. The following facilities are available. Fire Hydrants: These are useful to fight major fires. All plant units have these located 30 meter apart at various points. The height of the hydrant is usually one meter from the ground the most comfortable height for attaching a fire hose. The diameter of the hydrant outlet is 63mm and pressure is 5,25kg/cm2 and the water flow is 600lit / min. Fire Hose Reel: This is a primary fire fighting equipment to fight primary fires. It is a wall mounted drum with hose wound on it. One end of the hose connects to the water source and the other end has a nozzle. Fixed Type Water Monitor: fighting fire in tanks and vessels will take a long time. Fixed type water monitors are handy to fight such long duration major fires. These are located around the vessels and tanks. Their rotation capability of 360 deg in horizontal direction 90 deg in vertical plane (+75 to –15) and jet of 7 kg/cm2 discharging 2400 lit/min reaching a height of 45 m is a boon to fire fighters. DCP (Dry Chemical Powder) It is a primary fire fighting equipment and placed in open field to fight small fires (a B C type) these are not fit for office purposed as it affects the electronic devises. CO2 Extinguisher It is also a primary fire fighting equipment and used to small fire. It does not affect electronic equipments. Thorough aeration is necessary after the fighting. Deluge and sprinkler system: These system id installed near • • •

Non insulated vessels containing more than 7.5 m3 of flammable liquids. manifold handling flammable liquids LPG spheres Page 98 of 98