Cold start-up

Points to Remember

Ø  maximum of HP casing and HP shaft is less than 150°C(more than 5 days)

Ø  It requires soaking of Turbine at 360 rpm with steam(40ksc,360 Deg)

Ø  An upper limit of 200° C/hr. saturation temp gradients can be allowed, i.e. approximately the boiler pressure can be brought to 20 Kg/ Cm² within an hour of cold start up

Ø  But actual temp gradient is limited by the thick walled Y piece provided in the main steam and HRH lines

Ø  maximum differential temp allowed between inner (98%) and mid wall temp (50%) is ±40°C

Ø  Start only two CC pumps in order to minimize flashing in down comers (and subsequent vibration) when the boiler water is in the range of 85° to 125° C

Ø  third pump should be started before drum pressure reaches 7 Kg/Cm² to minimize the temperature transients experienced by the pump casing ( this is to avoid fast load out back on the boiler in the event of any CC pump tripping).

Ø  To get the rolling parameters, normally two elevation oil guns are taken with approx. 70 to 80 t/hr. flow through HP-LP bypass. At that time MS parameters would be 40 Kg/Cm² and 360° C.

Ø  As soon as the turbine loading has started, HP/LP by pass closes

Ø  First mill is put into operation around 10% of generator load

Ø  Second mill is put into operation around 25%

Ø  Third mill at 40% of generator load

Ø  Fourth and fifth mills are put into operation at 60% and 80% of generator load respectively

Ø  Sixth mill is taken to reach full generator load

Ø  During loading the RH outlet steam temperature has to be kept as close as possible to SH outlet steam temp. Burner tilt, SH spray, RH-spray controls have to be adjusted accordingly

Procedure

SNo	Time	Condition	Action	Follow-up	Status
1		0 ksc	Charge PRDS from other Units (14ksc,>260 Deg)	Open drains at PRDS,TG Floor,8.5 m
			Charge Atomizing steam(Pr 6.5 ksc)	Open drains at 4 elevation
			Fill Water upto +200 mm One CEP i/s LPH,HPH charged from FW side Deaerator Level =175 mm Hotwel b/w -100 to -200 mm FRS 30 % to fill Drum /load upto 180 MW	Drum, SH, RH Vents , SH Drains : Open LPD : Drains Closed BSV : closed Drain Before BSV :Closed MS strainer drains UFT/SDFT: Open HRH strainer Drain UFT/SDFT : Open ECO Recirculation E20 Manual : Open
			Charge LDO upto HOTV
			ESP ready in charge Condition	Open i/l, o/l damper of passes
			Bottom Hopper & Seal Trough Lined-up
			EAST, Excitation panel, GRP Panel Ready
			Generator gas Pr= 3.5 ksc
			H2 cooler,PW system Ready
			Start one CC pump	Drum >+200 mm, Vents B3,B4,B5,B6 Closed
			Start second CC Pump	Drum normal =+50 mm, B3, B4,B5,B6 Closed
			Start Scanner Fan
			Start Both SAPH	Air Motor availability to be checked FG/Air Inlet/Outlet Dampers Open
			Start Both PAPH	Air Motor availability to be checked Air Inlet/Outlet Dampers Open FG Inlet/Outlet Dampers closed
			Start one set ID/FD, Air>30% (600 TPH)	SADC 100 % (auto)
			Charge SCAPH for Running FD Fan	Check for Increase in Air Temp at SAPH i/l
			Start Purge (Duration :  5 min)	HOTV, LOTV got reset SADC will released from 100 % in auto
			Machine on Barring	LO Temp=45 Deg, Speed=80-100 rpm JOP Header Pr=140 ksc Start MOT Centrifuge HPCF Charged, Temp=55 Deg
2	0'	Boiler Ready & turbine on Barring	Start 4 guns in AB elevation  After 30', Start 4 guns in CD elevation To match Drum MTM Raise 2 Deg/Min	LDO control Pressure =9 ksc Start : Pair AB 1/3 and after 7 sec AB 2/4 Check scanner Intensity / Local Verfied Start : Pair CD 1/3 and after 7 sec CD 2/4 Open E20 R/C valve, if MDBFP not feeding in Drum Check Drum Level/ Open CBD Check D/A Level & H/W level
			Start GSC Exhauster fan Charge Seal steam upto Supply Motorized v/v of GS supply  station Start Vacuum Pumps one by one	Open dtain before NRV Steam Temp >250 Deg Drain Casing of Pumps, Fill Receiver tank >80 % in VG
			At -0.2 ksc, charge seal steam	By bringing controller from 50 % towards zero Build Vacuum upto -0.9 ksc
			Open HPBP Warm-Up drains
			Switch on SLC Drains	Verify: Manual v/v  Opened
3	60'	Drum Pr= 2ksc	Close SH/RH Header Vents Close SH Header drains at Dr Pr =10 ksc Open BSV Bypass Lines	To Warm up Ms/CRH/HRH lines
4	100'	Drum Pr= 5ksc	Open LP Bypass 10% Open BSVs Open HPBP by 10% at Dr Pr=7 ksc Start 3rd CC pumps at Dr Pr=9 ksc Take Additional EF gun ( If Required) Close HPBP Warm-up valves	Open 1st HPBP Warm-up valves Close CRH drain Pot at TG 0m
			Rolling through SGC
5	150'	MS =15 ksc/ 180-200 Deg HRH=8 ksc	Switch On start-up Sequence of SGC-turbine	TSE Influence comes ON
6	300'	MS =50  ksc/ 350 Deg HRH=8 ksc/350 Deg Turbine Ready to Roll	Turbine Speed raised to 360 rpm through SGC sequence	Ensure LO TCV on auto with SP=45 Deg Gas Controller on auto PW controller on auto Ensure closure of Barring valve at 240 rpm Monitor TG Vibrations, TSI, Bearing Temp MS Pressure/Temp to be maintained upto load 50 MW
7	360'	MS =50  ksc/ 350 Deg Turbine at 360 rpm	Turbine Speed raised to 3000 rpm through SGC sequence	Check X6 criteria Ensure Tripping of JOP at 540 rpm Ensure Tripping of AOP at 2950 rpm
8	370'	MS =50  ksc/ 350 Deg Turbine at 3000rpm	Switch Off SGC Program Put AVR on auto Close Field Breaker Select Main GCB Switch on Synchroscope after select Check Synchronise unit through synchroscope from OWS Raise Speed SP by 15 rpm Close MAL drains and other HE drains	Check X7 criteria GT Cooler Fan starts on auto/ Verify Load Ref=50 MW . Pr Max=75 MW Turbine Speed will Decrease
9	390'	Load=55 Mw MS Pr=54 ksc/350 Deg HRH=12 /340 Deg	Start PA Fan, Seal air Fans starts in auto Take 1st Mill Start 2nd set of ID/FD Fans Cut in LPH-2, 3 Cut out Deaerator steam from PRDS Peg Deaerator form CRH =2 ksc Cut in all controllers	Open PAPH FG/Air inlet/outlet Damper Open PA Header Pr=800 mmWC, SA Disch Hdr=1500 mmWC
10	420'	Load= 110 MW MS=70ksc/370 Deg	Charge PRDS from CRH Peg D/A upto 4ksc( gradually) Cut in 2nd Mill Start withdrawing Oil support Control MS/HRH Temp with Burner Tilt  and spray(if Required)	Ensure energizing of Trim Device at 100 MW load Ensure Fireball scanners Healthiness
11	440'	Load= 160 MW	Rest as per Hot/Warm start up