Gas Turbine Startup

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GT START-UP PROCEDURE 3 Fuel GAS/HSD/Naphta. PRE–START CHECKS :

1. Ensure all valve positions and spades / blinds are ok after water wash. 2. Ensure spade provided on water wash inlet line.

3. Check all instruments and lines are fitted with proper support/clamps. 4. Checking of GCV, SRV and Liquid Fuel Control valve strokes.

5. IGV angle stroke check.

6. Check the operation of Purge air three-way valve (VA19).

7. Check False Start drain line and Telltale leak off line for any choking. 8. Check Load gear and turbine compartment vent fans auto changes over. 9. Check free rotation of Liquid fuel Flow Divider.

10. Check lube oil level (should be more than 75%)

11. Line up cooling water to lube oil cooler and atomising air cooler .

12. Keep the atomising air cooler inlet and outlet drain (isolation) valves open up to FSNL. 13. Check the position of compressor bleed valves and confirm that these valves are open. 14. Ensure bearing sealing air isolation isolation valve is open.

15. Ensure that guillotine damper is open and diverter damper is closed.

16. Check the position of IGV and also check for any leaks in the hydraulic oil system. 17. Drain BHAG KOD and BHAG line near GT for any condensate / water.

18. Check that the control interlock and protection DC circuit is free of any ground fault. 19. Check for any alarm existing at MARK V.

20. Put portable fire extinguisher near fuel forwarding skid and also near GT. 21. Check the quality of spark from spark plugs before installing .

22. Check all flame detectors are healthy. ACTIVITIES :

1. Check the lube oil circuit physically. Connect electrically AOP (88QA) and ratchet pump (88HR) and start Ratcheting from the panel. Check the following :

· AOP discharge pressure and lube oil header pressure · Individual bearing i/l header pressure

· proper flow of lube oil through all return line sight glasses · Any leakage in the circuit.

2. check lube oil mist eliminator fan (88QV) is running with ratchet selection and set the vacuum pressure at - 50 mmwc.

3. Following motors are to be electrically connected , kept on auto and manual STOP PB s’ are to be kept in unlock position.

· Load Gear vent fans 88VG1 / 2

· Turbine compartment vent fans 88BT1 / 2 · Accessory compartment vent fans 88BA1 / 2 · Gas compartment vent fan 88VF

· Auxiliary hydraulic oil pump 88HQ · Frame blowers 88TK1 & 88 TK2

· WARREN pump lube oil motor 88QA2 & 88QE2 · Naphtha scavenging fan 88NS.

4. Check the following in Diesel Engine i. DM water level (> 80%)

ii. Lube oil level (F)

iii. Diesel tank level ( > 80% )

iv. Diesel engine cooling water inlet and outlet valves are open . v. Fuel cut off lever position ( pulled out )

5. HSD lining up :

· Check the HSD line up in filter skid and keep the isolation valve u/s of 3 way c/o valve closed. Confirm the long recirculation valve is full open.

· Confirm the vents and drains of the filters which are in line are fully closed. · Line up HSD to HSD pump from the standby Day tank .

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· Prime both the filters and pumps.

· Confirm both the pumps are on MAN on panel. · Keep the PCV KPIC656 on MAN and give 10% MV. · Connect both the pumps electrically.

· Start one pump and slowly open the discharge valve . Check the discharge pressure and also filter DP.

· Open the discharge valve of the other pump and put it on auto. Confirm it’s STOP PB is released.

· Prime the 25 micron & 5 micron filters which are in line. Also, charge the stand by filters , prime and keep ready for change-over.

· Start drain tank sump pumps and empty out so that any leakage in the system can be indicated by the increasing level of the drain tank.

· Prime the HSD line d/s of 3 way c/o valve (88FT) upto the liquid fuel stop valve ( VS1 ). Ø Open the topmost vent inside acc. compartment

Ø Crack open the isolation valve u/s of 3 way c/o valve

Ø Once full bore HSD comes from the vent , close the vent valve fully. Ø Open the isolation valve fully.

6. Check EOP cut-in with ratcheting by stopping AOP by logic forcing .

7. Connect diesel engine starter motor 88DS and give START command to GT.

CHECKS AFTER START COMMAND:

1. Check diesel engine fuel pressure (5 kg./cm2)

2. Check diesel engine cooling water o/l temperature ( max. 85 degree C)

3. Cross check the diesel engine local tachometer reading with the panel reading at different stages.

4. Check the condition of diesel engine exhaust.

5. Check the FSD outlet for any liquid as soon as diesel engine starts accelerating. In case of any liquid coming, cranking to be continued till dry air comes.

6. Check the auto cut-in of warren pump AOP ( 88QA2 ) 7. Check the condition of booster air compressor.

8. Check the general condition of the compartments at cranking speed for any noise or abnormal sounds.

9. Check the liquid pressure at selector valve assembly while firing and control HSD pressure this time.

10. Check the auto cut-in of turbine compartment vent fan after firing takes place. 11. Check the auto cut-in of accessory and load gear compartment vent fan .

12. Continuously monitor flow divider pressure and leaks from ferrule joints of liquid fuel lines. 13. Check that the diesel engine is disengaged at around 60% speed .

14. Check for stopping of diesel engine automatically after cool down. If not, diesel engine to be stopped manually by pushing the fuel cut-off lever in .

15. Monitor the following on panel continuously : · exhaust temperature plot

· spread

· flame detector readings · bearing vibration

· bearing metal and drain temperatures · lube oil and atomising air temperature · opening of IGV

CHECKS TO BE CARRIED OUT AT FSNL: 1. Check the bleed valves are closed.

2. Check the auto cut in of frame blowers one by one with a time delay of 1 min. 3. After removing water contents start self cleaning of air inlet filters.

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( 63QA, 63QL & 63HQ ) on the local gauge panel.

5. Check the mist eliminator suction pressure. Maintain it at –50 mmwc by adjusting the bypass valve.

6. Check the following readings · Flow divider pressures

· MOP discharge pressure, Lube oil header pressure, Hydraulic oil pressure, Trip oil pressure, all filter DPs’ , CPD , Atomising air pressure, all bearing lube oil inlet pressures, warren pump lube i/l and return pressures & filter DP, HP filter DP etc.

7. Check the position of IGV (57-degree angle).

8. Check any hydraulic oil or HSD leaks. Also, monitor the drain tanks level . 9. Commission CO2 fire fighting system.

10. Check all parameters in MARK-V <I> STATION.

11. Check for any flue gas leakage from. the exhaust duct manway or bellows. SYNCHRONIZING:

1. After ensuring all parameters are Normal GT can be synchronise .

2. As soon as GT breaker is closed, Machine will take spinning reserve load of 4 MW. 3. Machine can loaded as per requirement.

4. Due to sudden increase in HSD flow, pressure might come down drastically. So, during this period continuously monitor HSD pressure and control if necessary.

DIESL ENGINE TRIAL ON TEST MODE

GT Staring Diesel Engine can be tried on test mode by disengaging the starting clutch. Following procedure is followed for this test

1. Ensure diesel engine for cooling water, engine oil, and diesel tank levels. 2. Disengaging the clutch

i. Isolate 88DE and 88HR motors modules ii. Open the guard on the clutch assembly. iii. Connect 88HR and start ratcheting

iv. Before the forward stroke put the ‘clutch disengagement manual 4 way valve’ VM2-1 lever on Disengage position.

This will disengage the clutch during reverse stroke. Check it physically also at MARK-V from L33HR-1 position.

3. Once the clutch is disengaged put off the ratcheting immediately otherwise the ratchet mechanism will remain ON continuously.

4. Isolate 88HR motor module. 5. Connect 88DE motor

6. Select “Diesel Engine test mode” on MARK -V panel.

7. Start diesel engine by pressing 43DE-1 (diesel engine test switch) locally. Diesel engine will run till this switch is kept in press condition.

8. After satisfactory run and checking engine parameters release the switch. 9. Isolate the 88DE motor.

10. Come out of “Diesel Engine test mode” on MARK-V panel 11. Normalising Clutch:

-i. Put back the ‘clutch disengagement manual 4 way valve’ VM2-1 lever on Engage position.

ii. Connect 88 HR motor and start ratcheting.

iii. The clutch will get engaged in the forward stroke.

iv. Check the clutch physically and from L33HR-1 position in MARK -V 12. Stop ratcheting and put back the guard on the clutch assembly.

13. Re-Start ratcheting. GT INTERLOCKS

AUXILARY SYSTEMS:

SL NO DESCRIPTION SETTING

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2 Lube oil header temperature high alarm 26 QA-1 740C

3 Lube oil header temperature high trip 26 QT-1A,1B 790C

4 Lube oil pressure low alarm 63QA-1 AOP start 1.1 Kg/Cm2

5 Lube oil pressure low EOP start 63 QL-1. Refer MCC drawing. 0.4 Kg/Cm2

6 Lube oil filter differential pressure high alarm 63QQ-1 0.75 Kg/Cm2

7 Lube oil mist eliminator pressure switch 63QV-1 0.7 Kg/Cm2

2 L63QTX low lube oil pressure trip L63QT 2A, L63QT 2B, & L63QA

(2/3logic )

0.55, 0.55, and

1.1 Kg/Cm2

8 High lube oil level 77QH-1

9 Low Lube oil Level 77 QL-1

10 Turbine exhaust frame cooling air pressure low 63TK-1,2 52.3 MBar

11 Hydraulic trip pressure low gas stop valve 63HG-1,2,3 (2/3 logic) 1.4 Kg/Cm2

12 Hydraulic trip pressure low Liquid Fuel stop valve 63HL-1,2,3 (2/3

logic)

1.4 Kg/Cm2

13 Hydraulic filter differential pressure alarm 63HF-1 3.4 Kg/Cm2

14 Low Hydraulic oil supply press. AHOP start 63HQ-1 72 Kg/Cm2

15 Gas fuel pressure low alarm 63 FG-3 11.6 Kg/Cm2

16 Liquid fuel pressure low trip 63 FL-2 with tome delay of 60 sec. 1 Kg/Cm2

17 Warren LO header temperature high trip (26QT-3) with TD of sec 760C

18 Warren LO pressure low EOP (88QE-2) start 63QA-4 (2 sec time

delay)

6 Kg/Cm2

19 Warren LO pressure low Turbine trip L63 QT: 63 QA-3 and 63QA-4.

Time Delay of 8 sec (2/2 logic).

4.5 & 6 Kg/Cm2 respectively

20 Warren LO tank level low and high alarms 71QL-2, 71QH-2

21 Main AA compr. Diff. Pressure alarm 63AD-1A 0.4 Kg/Cm2

22 CW temperature high alarm DE 26DW 1000C

23 Turb. Comp., Acc Comp., Scavn fan, Gas Valve Comp fan & Load Gear

Comp. Pressure low alarms 63AT-1,2, 63AT-3,4, 63SN, 63VF-1, 63VG-1,2

24 Turbine inlet air filter differential press. High alarm 63TF-1. 152.4 mm Or 6

Inches of WC

25 Turbine inlet air filter differential pressure. High trip 63TF-2A,2B 203 mm Or 8

Inches of WC

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27 Turbine exhaust Duct pressure high trip 63ET-1, 2 (2/2) 508 MMWC

28 CW valves operation at set values VTR-1, VTR-2 54, 1070C

GT TRIP LOGICS: L4PST:

-SL. NO DESCRIPTION AND SETTING

1 L45FTX fir indication trip

2 L63QTX low lube oil pressure trip L63QT 2A, L63QT 2B, & L63QA (2/3logic settings 0.55,

055, and 1.1 Kg/Cm2 respectively))

3 L86TGT generator Lockout trip

4 L4 RLYT relay circuit feedback trip (external Trip)

5 L63ETH exhaust pressure high trip L63EAH, L63ET1H, L63ET2H (2/3 Logic settings 406,

508 & 508 mmWC)

6 L39VT GT trip on high vibration (see the separate sheet)

7 L2SFT Startup fuel excess trip--- L60FFLH liquid fuel flow high FQL1> 9.4%. (in gas

GRV_POS>10 %)

8 L12H_FLT loss of protective HP speed inputs (L14_ZE TCEA HP zero speed.

9 L4CT customer trip input

10 L12HF control speed signal loss (TNH<TNKHF---5%)

11 L12HFD_C control speed signal trouble (TNH_OS-TNH> 6.5%)

12 L12HFD_P protection speed signal trouble (TNH-TNH_OS > 6.5%)

13 L12H_P HP overspeed trip

14 L12H_ACC HP excessive acceleration trip

15 L3SFLT control system fault trip

i. L3COMM_IO common I/O status (1=OK, 0= Lost communication) ii. L14HS and L4

iii. L14HSX & L94X & L4

iv. L1stop command PB—stop turbine

16 L86GCVT gas control valve not following reference trip (!FSR2-FSG! > 5% with TD 5

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L4PRET:

-SL. NO DESCRIPTION

1 L3GRVFB pos feed back trbl (FSGR < -6.67% TD 2SEC Set & Latch

2 L3GRVO GRV Open trbl. (FSGR > 6.67% TD 2SEC)

3 L3GRVSC GRV current trbl (FAGR < 30% TD 2 SEC)

4 L3GFIVP fuel intervalve pressure trbl. ( FPG2 < -5.0 PSI)

5 L3GCVFB GCV Pos feed back Fault ( FSG < -30% TD 2sec)

6 L3GCVO GCV Open trbl alarm logic (FSG > 5% TD 2sec)

7 L3GCVSC GCV servo current Fault (FAG < 30 % TD 2sec)

8 L3LFBSQ liquid Fl B/P valve flow detect. Trbl alarm (FQL1 > 3% TD 2 SEC)

9 L3LFBSC liquid Fl B/P valve servo current Trbl alarm ( FAL < 30 %) TD 2sec)

10 L62TT2 multiple start counter (No of Auto start >= K62TT2---- 2 counts)

11 L2DWZ2 diesel failure to brake turbine Shaft ( after diesel warm-up timer L2DWX if

L14HR not coming within 3 minutes)

L4POST

SL. NO DESCRIPTION

1 L63HLL liqd fuel hudr. trip press. Low (L63HL1L, L63HL2L, L63HL3L 2/3)

2 If L3COM_B is not OK one L63HL1L will trip M/C

3 L63HGL guel gas Hydr. trip press low

4 L26QT L26QT1A, L26QT1B and L26QA 2/3

5 If L3COM_B is not OK one L26QT1A will trip M/C

6 L12H electr. Overspeed trip (TNH > TNKHOS 110%)

7 LCPRERR comp oper limit control at max error

8 L28FD Flame detection goes off (28FDA, B, C, D . 3 out of 4 going blank with TD 1 SEC)

L30SPT high exhaust temp spread trip

9 L86TXT exhaust over temp trip (if TTXM > (TTRXB+TTKOT2) TTKOT2= 400F TTXM >

TTRXB+220C

OR ISO TRIP

TTXM > (TTKOT1) isothermal trip 11100F (6380C)

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i.e. TTXM < 1210C

11 L86CBT compressor Bleed Valve position trouble trip

12 L3SMT starting device trip

13 L4IGVT IGV control trbl trip (before FSNL CSGV-CSRGV > 7.5 DEG A

After FSNL CSGV < 50 DEG A

VIBRATION MONITORING OF GT AND INTERLOCKS

There are total 10 vibration sensors provided for monitoring bearing and Load Gear vibrations of GT. GROUP 1 (Turbine):

-BB1 & BB2 on bearing No. 1 (Turbine Front bearing) BB4 & BB5 on bearing No. 2 (Turbine Rare bearing) GROUP 2 (load Gear):

BB7 & BB8 on Load Gear GROUP 3 (Generator):

-BB9 & BB10 on Generator front bearing BB11 & BB12 on Generator rare bearing

GT trip will be initiated in any one of the following conditions

1. In a group of four sensors of turbine one sensor going up to alarm level (12.5 mm/sec) and other going to trip level (25 mm/sec) will initiate trip.

2. In a group of four sensors of generator one sensor going up to alarm level (12.5 mm/sec) and other going to trip level (25 mm/sec) will initiate trip.

3. To ensure reliability of the machine two sensors (BB7 & BB8) are provided on the load gear instead of one recommended by the manufacturer. Any one of these two sensors going up to trip level or going faulty will not cause tripping of the machine. If one goes to alarm level and other goes up to trip level will trip the machine.

4. If one of the sensors is disabled (considering it is showing a faulty indication), the remaining three sensors will be considered as active and unit trip will take place if out of these three sensors one goes to alarm and other goes to trip level of vibrations.

5. If one of the sensors in load gear is disabled (considering it is showing a faulty indication) then unit trip will take place if the active sensor goes to trip level of vibrations.

6. If majority (two) of the sensors are disabled then only one sensor going to trip level (25 mm/sec) is sufficient to trip the machine.

7. If all the sensors in a group (4 in turbine or 4 in generator or 2 in load gear) are disabled or identified as faulted then turbine Auto Fired Shut Down command will be initiated by MARK V.

· Adjacent sensor differential alarm will come if paired or adjacent sensors (defined by J39R_g) signals are differed by a constant LK39DIFF= 3.8 mm/sec after a time delay of 0.5 sec.

Each sensor channel that is defined as being utilised by KJ39U_g mask is monitored for open circuit sensor faults. If a vibration sensor channel is determined to be faulty an alarm is annunciated to operator. This sensor can be disabled so that an additional transducer fault will not trip machine COMBUSTION MONITORING SYSTEM

All the exhaust temperature thermocouples used for the TTXM calculation are sorted from highest to lowest.

Allowable spread is calculated based on maximum CTDA and system exhaust temperature TTXM

TTXSPL = [0.145*TTXM – 0.08*CTDA + 30]0C

The median of the three 160C, 690C and calculated TTXSPL is taken as allowable spread limit. Three highest spreads are calculated as below

Sprd1= Highest TC – Lowest TC reading Sprd2 = Highest TC – Second Lowest TC reading

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Sprd3 = Highest TC – Third Lowest TC reading

Combustion monitoring trip is enabled at 14HS speed (with Master Protection is not tripped L4 & NORMAL shut down is not selected L94X). This logic L83SPM is through at 14HS with 60 sec time delay.

Based on the three highest spread, calculated above, following six logics are generated in the spread algorithm.

· L60SP1: - If Sprd1 > TTXSPL · L60SP2: - If Sprd1 > 5*TTXSPL · L60SP3: - If Sprd2 > 0.8*TTXSPL · L60SP4: - If Sprd3 > TTXSPL

· L60SP5: - If the lowest and the second lowest temperature readings are of adjacent thermocouples.

· L60SP6: - If the second lowest and the third lowest temperature readings are of adjacent thermocouples.

Based on above logics following alarms are generated:

· If sprd1 > TTXSPL (Logic L60SP1) “COMBUSTION TROUBLE” alarm (only) will be generated after time delay of 3 sec.

· If Sprd1 > 5*TTXSPL (Logic L60SP2) “EXHAUST THERMOCOUPLE TROUBLE” alarm will be generated after time delay of 4 sec.

Even though the Sprd1 becomes normal after reaching to alarm level the alarm will reset (logic normalize) only after giving MASTER RESET

Combustion monitoring trips 1) If Sprd1 > TTXSPL AND

Sprd2 > 0.8*TTXSPL AND

The lowest and the 2nd lowest TCs are adjacent. Then trip the M/C after 9 Sec Time Delay

(I.e. if L60SP1 AND L60SP3 AND L60SP5 are coming simultaneously then trip after 9 seconds) 2) If Sprd1 > 5*TTXSPL

AND

Sprd2 > 0.8*TTXSPL AND

The 2nd & 3rd lowest TCs are adjacent Then trip the M/C after 9 Sec Time Delay

(I.e. if L60SP2 AND L60SP3 AND L60SP6 are coming simultaneously then trip after 9 seconds) 3) If Sprd3 > TTXSPL

Then trip the M/C after 9 Sec Time Delay

(I.e. if L60SP4 comes then trip after 9 seconds)

2000F (930C) as and when FSR is increased or lowered with LOAD RAISE, LOWER commands bias the allowable spread TTXSPL. The bias remains for 60 second and becomes normal with a defined ramp rate.

CO2 FIRE FIGHTING SYSTEM FOR GT

Fire detectors are provided in various compartments as follows · Accessory compartment 6 numbers setting 3150C

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· Turbine compartment 6 numbers setting 3150C.

· Turbine Compartment Exhaust 2 numbers setting 3830C. · Load Gear Compartment 2 numbers setting 3150C. · Load tunnels 2 numbers 3830C

· Generator compartment 12 numbers setting for 6 detectors 1000C and for remaining 6 detectors 800C.

The CO2 fire fighting cylinders are grouped in to two parts.

1. For Accessory and Turbine Compartments. (Total 23 cylinders each of 45 Kg weight. 8 for initial discharge and 15 for extended discharge)

2. For load gear and Generator compartments. (Total 8 cylinders each of 45 Kg weight. 4 main 4 stand by)

As the fire is detected by any two of sensors in the group CO2 will be released in the respective compartments of the group through initial discharge header and extended discharge header. Initial discharge will be at high pressure and will last for 1 minute for extinguishing the flame. The extended discharge, which will start along with initial discharge, will continue for some time with low pressure. In the group of 4 cylinders provided for load gear and Generator compartments a diversion valve assembly is given which will divert the released CO2 to either load gear compartment or the generator compartment depending upon where the fire is detected.

The compartments ventilation fans will be put off as soon as the fire is detected. The CO2 pressure, with the detection of fire will close also all the dampers in the ventilation system.

One bell will ring in the GT hall to alert the operator who is taking round inside the GT compartments before release of the CO2.

The pressure switches (45CP-1A, 2A, 3, 4) mounted on the headers on fire protection system are set at 4.1 Kg/Cm2.On detection of fire MARK V will initiate fire indication trip L45FTX.

Figure

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References

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