MHI 700MW Turbine Rolling

8/19/2019 MHI 700MW Turbine Rolling

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TURBINE ROLLING


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OBJECTIVE

THE OBJECTIVE OF STARTING UP OF

THE TURBOGENERATOR IS TO BRING A

UNIT ON LOAD AND RAISE IT TO THE

RATED OUTPUT WITHIN THE OPTIMUM

TIME BUT WITHOUT UNDUE STRESSES

ON THE TURBINE COMPONENTS.


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Why Rolling is required…..• The starting operations may have an important

influence on the possible curtailment of turbinelife because major thermal and mechanicalstresses will be experienced in the course ofstarting.

• This hazard will be particularly enhanced whenturbine is started from cold.

• Least amount of stresses are observed when thetemperature of live steam during the startingperiod can be matched as closely as possible tothe actual temperature of turbine casing.


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General Start up Considerations

• During the startup the Turbine is subjectedto “Non - Steady state operation”.

• This covers the operating condition where Speed,steam Pressure and temperature change withtime.

• Under these condition turbine components whichare exposed to temperature changes subjected tothermal stress and expansion.

• For turbine life point of view, it is very muchnecessary to limit the extent of thesetemperature changes.


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TURBINE SPECIFICATIONSType Mitsubishi reheat & condensing 3 casing 4 exhaust flow typeCapability Net power output-700 MWSpeed 3000 rpm Direction of rotation-clockwise (view from Gov. End)Design Steam Condition

I. Steam press at main stop valve inlet 247 ataII. Steam temp at main stop valve inlet 565 °C

III. Steam temp at reheat stop valve inlet 593 °CIV. Exhaust pressure LP-1: 0.0771 ataLP-2: 0.0976 ata

No. of extractions for feed water heating 8 stagesBladingHP Turbine Impulse 1 stage

Reaction 9 pairs of rowsIP Turbine Reaction 8 pairs of rowsLP Turbine Reaction 8 pairs of rows


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TURBINE SPECIFICATIONS


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General Preparation of Start up• All the repair works on the turbine are

completed and all PTWs are cancelled.

• All the Turbo-supervisory instruments areavailable.

• Generator excitation system,GT & UATcooling system,seal oil system etc.are OK

• All the interlocks and protections of Turbine& Generator are already checked up andkept I/s.


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Start-up type selection

Turbine start up ( Control stageoutlet metal temperature)

Boiler start up (Water separatorinlet metal temperature)

Cold


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Pre Rolling Requirments• circulating water start-up completed

– Initial Fill (Circulating water pump discharge pipewill be filled by cooling tower make up pump)

– Pump will be started with discharge valve(HOV)closed and condenser inlet and outlet valve’s of atleast one pass open

– Ensure following parameters• Design discharge flow for one pump - 43400 cum/hr• Total developed head for CW pump - 28 mWC(2.79)• Rated current / Rated Power - 294 A/4.3 MW


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Pre Rolling Requirments• ACW and CCW system start up completed

– ACW pump to be started after ensuring availability ofwater in suction(More than 1.2ksc for startpermissive).

– Ensure for ACW pump• Rated flow - 2600 cum/hr• Rated Discharge - 10 ksc

– CCW pump can be started after ensuring DM waterfilled in expansion cum make up tank.

– Ensure for CCW pump• Rated Flow - 1650 cum/hr• Design pressure - 11 ksc


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Pre Rolling Requirments• Service water system ready

– Ensure that clarified water level in suctioncompartment is not low.

–

Adjust discharge valve flow to ensure min. flowthrough pump – Start the pump. – Ensure following parameters

• Capacity - 230 cum/hr• Motor rating - 75 Kw• Discharge head - 60m(6 ksc)


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Pre Rolling Requirments

• Air Compressors Started – Ensure before starting that cooling water temp.

and press. are normal. – Start the compressor with inlet valve open.

• Ensure Instrument air pressure more than 4.5• Ensure Service air pressure more than 4.5


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• DM water system ready – Ensure DM tank and CST level adequate for make-

up water supply during start up. – Ensure availability of Hotwell makeup and DM

transfer pump so that they could be started as andwhen required.


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• LDO system started – Ensure LDO tank level should be adequate. – Ensure suction and discharge valves fully open. – Ensure following parameters

• Capacity - 9500 Kg/hr• Discharge pressure - 15 ksc•

Motor rating - 9.3 Kw


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• Aux. Steam available – Aux. steam could be made available via 2 nd unit(if

running) or Auxiliary boiler. – Ensure steam of following parameters are

available at HT and LT header-• Temp. (HT) - 305 deg•

Temp. (LT) - 215 deg• Operating Press. - 15-16 Ksc


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Pre Rolling Requirments• HFO system started

– HFO tank level should be adequate and mat coilheaters should be operational ( maintaining temp. 50deg).

– HFO pump should be started with suction anddischarge valves fully open. – Ensure heaters in HFO discharge are operational. – Ensure following parameters of pump

•

Flow - 65 cum/hr• Discharge pressure - 27 ksc• Motor power - 75 Kw• Current - 130 Amp


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• Turbine Oil supply started

– After starting TOP, AOP, JOP and EH oil pumpconfirm that following parameters are achieved-:

• TOP discharge pressure: 3.5 KSC• AOP discharge pressure: 10.8 KSC•

JOP discharge pressure: 160 KSC


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• Seal oil system started – Ensure that seal oil system taken in service before

turbine is put on barring. – Ensure that Air side seal oil pressure is 0.85 ksc

above hydrogen pressure at generator seals; andhydrogen side seal oil pressure is same as that ofair side seal oil.


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• Turbine Barring gear in operation – Ensure turning gear ac motor power supply is

available. – Ensure lube oil supply is available to the gear

assembly. – Turning gear speed is 3 RPM


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Pre Rolling Requirments• Hydrogen filling done:

– Make sure ccw water system is available (required forH2 driers)

– Aux. steam is available and heaters in filling areavailable (required for CO2 filling)

– Ensure H2/CO2 purity measuring device condition ishealthy and it is well calibrated.

– Check that the hydrogen pressure is 3.8KSC afterfilling.

– To maintain H2 purity and its dew point temp. EnsureH2 driers are in service. Fill H2 and purge air tomaintain purity.


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Pre Pre Rolling Requirments

• Turbine drains in open condition – Main steam inlet lead pipe drain valve open. – HP turbine inner casing drain motor valve open. – HP turbine outer casing motor drain valve open. – Reheat steam inlet pipe drain motor valve open. – CRH (L&R) drain valve open.


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Pre Rolling Requirements• Vacuum pulling done:

– Ensure turbine is on barring gear and generatorseal oil system is in service.

– Ensure aux steam is available to unit aux PRDSheader

– Ensure gland steam temp. between 120-180 deg –

Condenser vacuum should be:• 0.0976 ksc for HP shell.• 0.0771 ksc for LP shell.


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Ensure Following During Rolling(Turbine constructional limits)

• Steam purity – Presence of unwanted corrosive impurities can

cause damage to turbine components by

corrosion, stress corrosion and corrosion fatigue – Hence continuous monitoring of following must

be made-:


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• Casing expansion – Monitors axial expansion of total HP-IP & LP

casing by measuring relative motion between no.

1 bearing pedestal and seating plate .• Rotor eccentricity

– Rotor eccentricity to be noted till 600 rpm andafter this, eccentricity recorder is cut off. Rotoreccentricity limit is 75 microns . In normaloperating conditions it has to be kept under 25microns.


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Ensure Following During Rolling(Turbine Trip Condition)

• BEARING VIBRATION HIGH HIGH(> 250 µm)• THRUST BEARING WEAR(± 1 mm)• EMERGENCY OIL PRESS LOW(70 BAR)•

BEARING OIL PRESSURE LOW LOW(0.5 BAR)• ELECTRICAL OVERSPEED TRIP• MECHANICAL OVERSPEED TRIP• TURBINE TRIP PB• LP-1 TURB EXH STM TEMP HIGH HIGH(T>120°C)• LP-2 TURB EXH STM TEMP HIGH HIGH(T>120°C)


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Ensure Following During Rolling(Turbine Trip Condition)

• TURB INL MAIN STM TEMP (LEFT) LL(


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Steam Admission Condition

– Turbine steam admission condition OK(P> 87ksc &Temp.- 330


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RESETTING THE TUR INE

•

When the Turbine trips due to Electrical orMechanical Protection Trip oil drains quickly.In the absence of the Trip oil Turbine Stopand Control vlvs closes quickly.

• So the Trip oil is basically required forkeeping the ESVs and IVs in open cond nand getting required Secondary oil press r

for opening the HPCVs and IPCVs.• The Trip oil again can be generated again

by Resetting the Turbine.


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ROLLING PROCEDURE – Give command for 500 rpm for Rub check of turbine, it will

reach 500 rpm and then will try to come at barring speed.Observe turbine vibrations and noise.

– If rub check is Ok, raise turbine speed to 500 rpm and hold

turbine at 500 rpm for 10 minutes for heat soaking. – Raise turbine speed to 1950 rpm and do 3 hours heat

soaking. – Raise turbine speed to 3000 rpm. – Carry out turbine valve transfer from MSV control to GV

control. Now Generator is read for synchronisation. – Observe stator water temperature at winding inlet and

charge stator water cooler.


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Valve operationName of drain

Prewarming

Rolling Put online

20 % load FWHTR inservice

FWHTRout of service

15 % load Takeoffline

Failure position

MSV HP stem leak O O C C C C C O FC

GV HP stem leak C C O O O O O C FO

RSV and ICV stemleak and trip pilotvalve

O O O O O O O O

RSV drain O O O C C C O O FO

Main steam inletpiping

O O O C C C O O FO

HP inner casing O O O C C C O O FO

HP outer casing O O O C C C O O FO

Reheat steam inletpiping

O O O C(CLOSED AT10 %)

C C O (OPENEDAT 7 %)

O FO

Gland sealing andgsc shell drain

O O O O O O O O O


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Start UP TimingsCOLD START-UP WARM START-UP HOT START-UP

Sr No ACTIVITIES DurationCumulative

timeDuration

Cumulativetime

DurationCumulative

time

1 Light-up 0 0 0 0 0 0

Boiler Start-upCurves

2 HP/LP Bypass charging 110 110 35 35 12 12

3 Pr raising to 87 ksc100 210 45 80 18 30

4 MS flow and Temp raising for Steam Admission 100 310 40 120 30 60

50 to 500 rpm for Rub check, again rolling to 500 rpm and hold at500 rpm

20 330 18 138

Not Required

Turbine Start-up

curves

6 500 rpm to 2000 rpm 10 340 Not required7 hold at 2000 rpm for warming 180 520

8 Rolling to 3000 rpm5 525 5 143 10 70

9 Electrical testing at 3000 rpm 240 765 0 143 0 70

10 Synchronisation and block loading 10 775 7 150 8 78

11 Hold at 5% Load 40 815 20 170 12 90

12 Load raising to Full Load 120 935 120 290 65 155


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THANK YOU


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Valve transfer

• The turbinespeed control isautomatically

transferred fromMSV to GV.


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Documents

MHI 700MW Turbine Rolling