Dadri-2: Instrument Air Failure affect

 

INSTRUMENT AIR FAILURE
NCPS Stage-2 (2X490 MW)
·        As Recirculation valves of both TDBFPs will open, immediately start MDBFP and Load it to maintain drum level. Reduce load to around 350 MW. ·        As Recirculation valves of CEPs will open, keep third CEP also in service. ·        Take all pneumatic control valves in manual and match command with feedback before instrument air pressure is restored to avoid command going to 0% or 100%.
Boiler side
Area	Valve/Gate/Damper	Type	Status		action
FIRING FLOOR	HOTV	AIR TO OPEN WITH ALR	Will close if there is any air leakage.		Stop HFO/LDO pump if Header  pressure is  not maintained
	LOTV	AIR TO OPEN WITH ALR	Will close if there is any air leakage.
	HORV	AIR TO CLOSE	Will Open
	HONV	AIR TO OPEN	Will close
	LONV	AIR TO OPEN	Will close
	HFO PR  CV	AIR TO OPEN WITH ALR	Will close if there is any air leakage.
	LDO  PR CV	AIR TO OPEN WITH ALR	Will close if there is any air leakage.
	Atomising Steam CV	AIR TO OPEN WITH ALR	Will close if there is any air leakage.
FOPH	LDO recirculation v/v	AIR TO CLOSE WITH ALR	Will open if there is any leakage.
	HFO recirculation valve	AIR TO CLOSE WITH ALR	Will open if there is any leakage.
	HFO cooler cv	AIR TO OPEN WITH ALR	Will close if there is any air leakage.
	HFO htr stm cv	AIR TO OPEN WITH ALR	Will close if there is any air leakage.
SH Spray	Main block Valve	AIR TO OPEN WITH ALR	Will close if there is any air leakage, MS temp will rise		Control temperature by unloading top mills
	Line block valve	AIR TO OPEN WITH ALR
	Control valve	AIR TO OPEN WITH ALR
RH Spray	Main block Valve	AIR TO OPEN WITH ALR	Will close if there is any air leakage, HRH Steam temp will rise		Control temperature by unloading top mills
	Line block valve	AIR TO OPEN WITH ALR
	Control valve	AIR TO OPEN WITH ALR
Burner Tilt	Burner Tilt	DOUBLE ACTING WITH ALR	Burners will go down if there is any air leakage.
APH	Air motor	Available	If NRV is healthy Air motor will run  for around 30 min.
	PAH FG O/L  damper	DOUBLE ACTING WITH ALR	May open or close slowly if there is any leakage from cylinder.
	SAH FG O/L  damper	DOUBLE ACTING WITH ALR	May open or close slowly if there is any leakage from cylinder.
SADC	SADC	STAYPUT			Monitor windbox/furn DP/ Monitor  air flow/ FD fan current/Furnace pr.
MILLS	HAG (V)	DOUBLE ACTING	May close if NRV is passing		Stop feeders if PA flow to mill reduces
	CAG(V)	DOUBLE ACTING	May close if NRV is passing
	HAD	DOUBLE ACTING WITH ALR	May open or close slowly if there is any leakage from cylinder.
	CAD	DOUBLE ACTING WITH ALR	May open or close slowly if there is any leakage from cylinder.
	Mill seal air valve	DOUBLE ACTING	STAYPUT
	Feeder SEAL AIR VALVE	DOUBLE ACTING	STAYPUT
	FEEER O/L GATE	DOUBLE ACTING	STAYPUT
Seal Air Fans	SEAL AIR FAN S/V	DOUBLE ACTING	STAYPUT
	SEAL AIR FAN D/V	DOUBLE ACTING	STAYPUT
Scanner air fan	SCANNER AIR FAN D/V	DOUBLE ACTING	STAYPUT
	SCANNER AIR EMERGENCY SUCTION DAMPER	DOUBLE ACTING	STAYPUT
Soot blowing	SB CV	AIR TO OPEN WITH ALR	Will close if there is any air leakage.
BCW pump	BCW cavity ECW  emergency v/v	close
	BCW cavity ECW drain v/v	close
SCAPH	SCAPH  STEAM CV	AIR TO OPEN WITH ALR	Will close if there is any air leakage.
Turbine side
Hotwell & D/A	Hotwell Lvl  CV	AIR TO CLOSE WITH ALR				Isolate normal makeup control valve
	Emergency make up valve	AIR TO OPEN WITH ALR				Maintain hotwell level by bypass valve
	D/A LVL  CV	DOUBLE ACTING WITH ALR		May open or close slowly if there is any leakage from cylinder.		·         Start third CEP ·          Maintain de-aerator level by motorised bypass valve. ·         Close D/A over flow manual valve. ·         Monitor condensate flow & maintain load accordingly
	D/A overflow	AIR TO CLOSE		Will Open
	GSC R/C valve	AIR TO CLOSE WITH ALR		Will open if there is any leakage.
	CEP R/C valve	AIR TO CLOSE		Will Open
	Gland seal CV
	CPU
BFP	BFP R/C  valve	AIR TO CLOSE		Will Open		Start MDBFP and maintain drum level.
	FRS  CV	DOUBLE ACTING WITH ALR		May open or close slowly if there is any leakage from cylinder.
	TDBFP GS  SUPPLY CV	AIR TO CLOSE WITH ALR				lube oil temperature
	TDBFP GS  LEAKOFF CV	AIR TO OPEN WITH ALR				Monitor TDBFP gland seal pr & maintain by its bypass v/v
	TDBFP Lube oil Temp CV	AIR TO CLOSE WITH ALR
HPH	HPH normal drip	AIR TO OPEN WITH ALR		Will close if there is any air leakage.		Monitor HPH & LPH level
	HPH  drip to flash box	AIR TO CLOSE WITH ALR		Will open if there is any leakage.
LPH	LPH normal drip	AIR TO OPEN WITH ALR		Will close if there is any air leakage.
	LPH  drip to flash box	AIR TO CLOSE WITH ALR		Will open if there is any leakage.
PRDS	PRDS  CV	close
Vacuum pump	Vacuum pump SIV	AIR TO OPEN WITH ALR		Will close if there is any air leakage		If SIV closes, watch vacuum, Confirm turbine should trip on low vacuum
MOT	Centrifuge 3way valve	bypass				Stop Centrifuge
Turbine	HPT evacuation valve	AIR TO OPEN		Will remain close and become inoperative.