GT LO System

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GAS TURBO POWER STATION

VIJJESWARAM172MW STAGE - II

GT Lube oil system

Issue No.

01

Issue Date

29/06/2013

Revision

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APGPCL

SOP –

GT Lube

oil System Page 1 of 12

Signature: Signature: Signature:

Prepared by: MVS Janardhanarao

Reviewed by:G.Srinivasa Rao

Approved by: A.Srinivas

Designation: SCE (OMS) Designation: Operation Manager(OMS)

Designation: Vice President(OMS)

Lube oil system Technical Data

Lube oil tank

Make : GENERAL ELECTRIC USA

Capacity : 12.5

Main oil Pump

Make : BUFFALO PUMP INCType : Positive displacementSource of drive : ACC gearCapacity : 163.4m3/hrDischarge pressure : 6.9 bar

Auxiliary lube oil Pump

MOTOR

Make : GENERAL ELECTRIC

Rated power : 75 HPVoltage : 380/415 v, 3 phase 50HzCurrent : 102/97.5 ASpeed : 2955-2695 RPM





GT Lube oil system

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Issue Date

29/06/2013

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Auxiliary lube oil Pump

PUMP:Make : BUFFALO PUMP INCType : centrifugal

Total head : 288 mtsCapacity : 650GPM

Emergency lube oil Pump

MOTOR :

Make : GE motorsPower : 10 Hp

Voltage : 120 vSpeed : 1750 rpmArmature current : 74AField current : 1.0A

Emergency lube oil Pump

PUMP:

Make : BUFFALO PUMP INC.Type : CentrifugalCapacity : 420GPM

:





GT Lube oil system

Issue No.

01

Issue Date

29/06/2013

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Seal oil Pump 88 DC&AC

MOTOR :

Make : GE motorsPower : 7.5 HpVoltage : 120 v

Speed : 3000 rpmArmature current : 63.5A

Field current : .410

Seal oil Pump

PUMP:

Make : AMPCO PITTSBURGH CO

Type : Centrifugal :Head : 134 mt

Capacity : 60GPM.





GT Lube oil system

Issue No.

01

Issue Date

29/06/2013

Revision

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Lube oil coolers :

No of coolers : 2 nos, (1 working& 1 stand by)Make : HEBLER-VICKSBURG CORPORATIONType : Dual lubricating oil to cooler

Water cooled oil coolers : Duplex, shell and tube water cooled.Heat transfer area per cooler : 164 m2Oil flow per cooler : 125m3/hr

Water flow per cooler : 187 m3/hrInlet/outlet oil temp ; 71/54 deg c

Lube oil mist eliminator

Type : Mist eliminatorCapacity of each extractorm3/hr : 225 :Drive motor rating (kw) : 7.5

MOTOR:Rated power : 10HpVoltage : 380/415 V, 3 ph , 50Hz.Current : 13.8/12.8 ASpeed : 2905/2925 rpm.





GT Lube oil system

Issue No.

01

Issue Date

29/06/2013

Revision

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Over View:

The lubricating system for the gas turbine power plant are furnished by

a common forced feed lubrication system.This lubrication system ,

complete with tank, pumps, coolers, filters, valves and various control and

protection devices,furnishes normal lubrication and absorption of heat

rejection load of the gas turbine and generator.

Lubricating oil is circulated to the turbine bearings, generator

bearings,and the accessory gear box.The lubricating oil is also supplied to

the starting means torque converter for use as hydraulic fluid as well as for

lubrication.this same fluid is also used as control oil or trip oil, high

pressure hydraulic oil and generator seal oil.

Major components of the lube oil system include:

1) Lube oil reservoir in the accessory base

2) Main lube oil pump(shaft driven from the accessory gear)

3) Auxiliary lube oil pump

4) Emergency lube oil pump

5) Auxiliary and emergency seal oil pump

6) Lube oil heat exchangers7) Lube oil filters

8) Pressure relief valve VR-1 in the main pump discharge header.

9) Bearing header pressure regulator VPR2-1and mist eliminator.





GT Lube oil system

Issue No.

01

Issue Date

29/06/2013

Revision

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Functional description:

Lubrication to the bearing header is supplied by three pumps:

1)The main lube oil pump is a positive displacement pump mounted on and

driven by the accessory gear.It is rated at 2725lpm(720gpm),

7.0ksc(100psig)

2) The auxiliary lube oil pump is a submerged centrifugal pump driven by

an ac motor rated at 2460lpm(650gpm), 7.5ksc(107psig)The auxiliary

pump has a higher pressure rating than the main pump to accommodate the

needs of the torque convertor during slow-roll and start up operation.Its

lower discharge volum,e is the reason that the auxiliary seal oil pump

needs to operate if the main lube oil pump is not available.

3)The emergency lube oil pump is a submerged centrifugal pump driven by

a Dc motor and is rated at 1590lpm(420gpm), 1.4ksc(20psig).

Start checks & Logics

1) Select Auto and switch on the AC breaker of AOP and AHOP

2) Switch on the DC breaker of EOP.

AOP:

When the turbine attains 95% rated speed during start up the auxiliary

pump stops. Similarly the auxiliary pump starts when unit speed drops

below 14HS( usually 90% rated speed) during shut down.





GT Lube oil system

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Issue Date

29/06/2013

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EOP :

The pump is the back up to the AOP.This pump will come into service

when AC power is not available and auxiliary pump fails during normal

shut down sequence ,the emergency pump will be started by the action

of low lube oil pressure switch 63QL-1 and continue to run until

manually shut off.

Logics:

The condition of dangerously low lubricating oil pressure is detected by

three trip switches 63QA-1, 63QT-2A & 63QT-2B.

Switches 63QT-2A and B are located at the aft end of the generator and

switch 63QL is located at the gauge cabinet in the accessory compartment

Pressure switches 63QT-2A and 2B in the lube oil feeding header to the

generator bearings sense a drop in lube oil header pressure below 0.55

bar(8psi) the unit will trip on low lube oil pressure and the emergency lube

oil pump will start.Pressure switch 63QL-1 acts as a back up to 63QT-

2A&2B, activating the EOP if header pressure drops below 0.41bar(6psi).

Pressure switch 63QA-1 should sense a drop in pump discharge header

pressure ,turn on the AOP and sound an alarm before 63QT-2A& 2B tripthe unit.Pressure switch 63QA-1 is set at

Like wise temperature switches 26QT-1A and 1B are installed in the

lubricating oil header and trip the turbine should the temperature of the





GT Lube oil system

Issue No.

01

Issue Date

29/06/2013

Revision

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Lubricant to the bearings exceed 79.4 degc (175 degF) .Temperature

switch 26QA-1 also located in the bearing header will cause an alarm

before this limit is reached set at 73.9 degc (165degF).

Differential pressure switch 63QQ-1 will cause an alarm at diff pressureacross the oil filters of 1.03 bar(15psi).

The SPEEDTRONIC Mark V Control system requires that both trip

switches 63QT-2A and 2B indicate low pressure.In the event of a failure of

one of those switches the control system is programmed to trigger a turbine

trip on detected low pressure by either of the trip switches and low

pressure alarm switch 63QA-1.

Similarly ,before the unit is tripped on high lube oil header temperature ,both trip temperature switches 26QT-1A and 26QT-1B must indicate high

temperature.This voting logic ensures that a malfunctioning sensor will

neither prevent the turbine protective functions nor cause an unnecessary

trip.

Seal oil pump

The seal oil to the generator bearings is normally supplied by the main

lubricating system through a separate line directly to the seal oil controlunit of the generator.This line is plumbed into the system upstream of

pressure regulating valve VPR2-1 .The seal oil control unit will regulate

the seal oil pressure to maintain it a nominal 0.32ksc(4.5psig) above the

hydrogen gas pressure.





GT Lube oil system

Issue No.

01

Issue Date

29/06/2013

Revision

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Logic;

\The seal oil pump is driven by two motors (one AC and one DC) mounted

in tanden.If Ac power is available ,the pump is driven by the Ac

motor,88QS-1. If Ac power is not available ,the pump is driven by the Dcmotor 88ES-1.If the auxiliary lube oil pump is on or if the unit is above

50% rated speed and pressure switch 63SA-1 senses low seal oil

differential pressure , the Ac motor will start. The Dc motor is activated by

either a low lube oil pressure signal from the bearing header (63QA-1 )or

by the under voltage relay(27MC-2) in the Motor Control Center.

Mist Eliminator:

The Mist eliminator consists of a vessel containing three coalescing

filters(candles) , a motor-driven fan and a bypass valve.oil is separated

from the air stream by the coalescing filters and returned to the main lube

oil tank .The fan overcomes the pressure differential caused by the flow

through the coalescing filters and maintains a slight negative pressure on

the lube oil reservoir.The bypass valve opens to bypass the mist eliminator

should the motor or fan fail; this prevents the tank from being pressurised

in the event of such a failure.The fan should be throttled to provide 0 to 2

inches of water pressure in the tank





GT Lube oil system

Issue No.

01

Issue Date

29/06/2013

Revision

0

Revision Date

0

APGPCL

SOP –

GT Lube








Turning Gear system..

Turning gear:

:

MOTOR:

Make : GE motorsRated power : 26HpVoltage : 380/415 V, 3 ph , 50Hz.Speed : 1465 rpm.

GEAR:

Type : worm gear with AC motorSpeed at which turning gear cut inCut out : 6rpmTurning gear speed : 6-7 rpmMain bearing oil pressure for TG : internal lube oil supply.

Over view:

Like other internal combustion engines, a gas turbine cannot produce

torque at zero speed. The starting means system is used to start the gas

turbine rolling, crank it to firing speed, and assist the fired turbine to self

sustaining speed. This is accomplished by an induction motor driven

turning gear and an induction motor starting device operating through a

torque convertor coupled to the accessory gear.This arrangement provides

the cranking torque required by the turbine for start up.Also at shut down

,this same equipment continues to rotate the turbine at slow speed for cool

down purpose.





GT Lube oil system

Issue No.

01

Issue Date

29/06/2013

Revision

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The starting means system components and control devices are located and

mounted in the accessory compartment.This starting system equipment is

mounted on a seperatebase structure attached to the accessory base top-deck.The turning gear and motor are mounted between the torque

convertor and the accessory gear box.The turning gear motor turns a large

reduction gear that provides the break-away torque for initial rotor

turning.The turning gear also provides the cool down rotation.The turning

gear assembly includes a synchro-self-shifting(SSS) clutch for impact- free

shaft coupling and uncoupling.

Start up functions:

In the normal starting sequence ,the turning gear is the first component

activated.Its electric motor/gear assembly drives through a reduction gear

to provide the break away torque required to turn the rotor.when the

SPEEDTRONIC Mk V control system senses the rotor is no longer at rest it

energises the cranking motor 88CR.This motor drives into a reduction that

the torque convertor input shaft.This gear also drives the charge pump

providing high pressure oil fill for the torque convertor..This oil also

supplies release pressure to the torque output shaft brake.The hydraulic

pressure of the system is sufficient to drive the output shaft and the rotor

assembly begins to turn faster than the speed provided by the turning gear

alone (6rpm).Then the clutch assembly by its design uncouples itself.





GT Lube oil system

Issue No.

01

Issue Date

29/06/2013

Revision

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The turbine begins to increase in speed and continues to accelerate until

minimum speed level (14HM) is attained.

Rotor cool down:

Logic:

To promote even cooling of the rotor and avoid rotor bow after unit shut

down ,the gas turbine rotor is rotated by the slow roll function of the

turning gear. The turning gear energises to initiate slow roll when rotor

speed decreases to approximately 6 rpm as determined by the

SPEEDTRONIC control circuits.

When the rotor is at rest and Cool down on is selected at the primary

operator inter face ,the rotor breaks away in the same manner as during a

normal start. The turning gear is energised and its reduction gear drives

the rotor to 6 rpm





GT Lube oil system

Issue No.

01

Issue Date

29/06/2013

Revision

0

Revision Date

0

APGPCL

SOP –

GT Lube








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