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First boiler light up
A K Das
DGM(OS)
NTPC Ltd
Points of discussion
• Parameters
• General preparation before boiler light up
• System readiness for first light up
• Protection and interlock
Parameters
Parameter Unit Predicted
Load MW 500
Total fuel MT 344
Superheater O/L pressure Kg/sqcm 176.7
Drum pr Kg/sqcm 191.3
First stage pressure Kg/sqcm 157.44
Reheater I/L pressure Kg/sqcm 43
Reheater O/L pressure Kg/sqcm 41
Super heater O/L steam flow T/hr 1498.5
Feed water flow T/hr 1488.5
Superheater spray flow T/hr 13
Reheater spray flow T/hr 0
Parameters
ECO I/L temp degC 253
ECO O/L temp degC 324
Superheater O/L temp degC 540
Reheater O/L temp degC 540
Flue gas temp at Pri APH I/L degC 338
Flue gas temp at Pri APH O/L degC 127
Flue gas temp at Sec APH I/L degC 338
Flue gas temp at Sec APH O/L degC 127
PA fan O/L pr mmWC 830
Primary air flow T/hr 652
Sec air flow T/hr 993
Total air flow T/hr 1847
O2% % 3.6
Preparation for 1st BLU
System readiness for the SIX main systems to be ensured
1. Air system2. Gas system3. Water system4. Fuel system5. Steam system6. FSSS
Preparation for 1st BLU
Trial run of all auxiliaries (Except Mills)Availability of instruments, interlocks and
protections neededRefractory and insulation work completedAvailability of DM waterCommunication at different locationsSufficient illumination Functioning of chemical lab
Preparation for 1st BLU
Ensure fire fighting systemEnsure sufficient stock of fuel oil,
lubricants & commissioning sparesWorking instructions and log sheets
Preparation for 1st BLU
Remove all loose construction materials around boiler
Cut off temporary supports , construction platforms not envisaged in the drgs
All valves marked with tag noAll lines identified by painting by colour
codeInspect water WW,SH,
RH,Eco,APH ,ducts
Preparation for 1st BLU
Retractable soot blowers must be in withdrawn conditions
Instrument tapping point valves must be open
Drum level signaling and instruments should be made operational
READINESS FOR FIRST BOILER LIGHT UP
BOILER PROTECTIONS
FSSS• Furnace Safeguard and Supervisory System:
- A fully digital control system which governs mandatory requirements related to safe startup and safe shutdown of the boiler
- Includes main boiler permissives and protections
- Includes heavy oil and light oil firing interlocks
- Includes permissives and protections (digital logic) related to mills and feeders
TO HAVE ALL THE MFT (03) DPUS HEALTHY. MFT CIRCUIT IS READY.
TO ENSURE NO BOILER TRIP IS PRESENT.
TO PREVENT FUEL TO BOILER.
TO HAVE PROPER AIR FLOW FOR REMOVAL THE UNBURNT FUEL LEFT IN THE FURNACE
NO FLAME IN FURNACE
BOILER PURGE
• A 9 minute mandatory cycle in which FD and ID fans are
run with 30 to 40% air flow, with NO Fuel input to the
furnace, to ensure the removal the unburnt fuel left over in
the furnace area after the last master fuel trip
BOILER FSSS PROTECTIONS
Three contacts each for Individual ID Fan are generated in corresponding VFD circuit when the electronic speed is sensed to be less than minimum (i.e. 90 rpm)
BOILER FSSS PROTECTIONS
Three contacts each for Individual
FD Fan are generated in
corresponding 11kV MCC Motor
Feeder Panel
BOILER FSSS PROTECTIONS
TO FACILITATE OPEARTOR
TO TRIP BOILER MANUALLY
IN IMPENDING SERIOS
CONDITION. BOTH
HARDWIRED & SOFT TRIP.
BOILER FSSS PROTECTIONS
All elevations voted no flame (no
delay) AFTER any feeder is proven
in service for 2 seconds. An
elevation is said to vote for no flame
if the feeder is not proven, OR if 3/4
oil guns are not in service AND 2/4
fireball flame is not sensed
BOILER FSSS PROTECTIONS
All oil and coal inputs to the boiler are sensed as closed or OFF (no delay) i.e.- All LONV closed OR LOTV closed +All HONV closed OR HOTV closed + All Feeders OFF (after any LONV/HONV opens partially)
BOILER FSSS PROTECTIONS
All oil and coal inputs to the boiler are sensed as closed or OFF (no delay) i.e.- All LONV closed OR LOTV closed +All HONV closed OR HOTV closed + All Feeders OFF (after any LONV/HONV opens partially)
BOILER FSSS PROTECTIONS
Boiler ON AND All BCW OFF
(OR)
2/3 running BCWPs sense DP less than 10 psi=0.67 ksc (5 sec delay)
BOILER FSSS PROTECTIONS
Boiler ON AND Drum Pressure > 8 ksc AND Flow through reheater tubes is interrupted (10 sec delay). To maintain flow through reheater, both MS to CRH and HRH to condenser paths should be not fully closed. Either HP Turbine path or HPBP path should be not fully closed AND LP Turbine path or LPBP should be not fully closed
BOILER FSSS PROTECTIONS
Furnace Pressure Very high > +150 mmwc
2 out of 3 logic from 3 pressure switches
BOILER FSSS PROTECTIONS
Furnace Pressure Very low < -175 mmwc
2 out of 3 logic from 3 pressure switches
BOILER FSSS PROTECTIONS
Drum Level Very High 250 mm for 10 sec
2 out of 3 logic. 1 from electronic water level indicators (eg. Hydrastep) and 02 from transmitters limit value (average of left and right)
BOILER FSSS PROTECTIONS
Drum Level Very High -375 mm for 05 sec
2 out of 3 logic from 2 electronic water level indicators (eg. Hydrastep) and transmitter limit value (average of left and right)
BOILER FSSS PROTECTIONS
Loss of 220V DC in MFT circuit for more than 2 sec.
Loss of 220V DC generates software protection
BOILER FSSS PROTECTIONS
Loss of 24V DC in 2 out of 3 MFT panels.
Loss of 24V DC generates hardwired protection.
BOILER FSSS PROTECTIONS
Total air flow (secondary near windbox + primary to individual mills) is less than 30% of full load rated flow I.e. 540 TPH (no delay)
BOILER FSSS PROTECTIONS
All BFPs OFF with 10 sec delay.
03 contacts generated in Station C&I logic and then hardwired to MFT panels. TDBFP trip is sensed as Trip Oil pressure V Low OR ESV Closed.
BOILER FSSS PROTECTIONS
Both Secondary Air Heaters OFF with 5 sec delay
3 contacts generated in Station C&I logic and then hardwired to MFT panels. Air Heater OFF is sensed as Electric Motor OFF AND Air Motor OFF i.e. Solenoid valve exit pressure low.
BOILER FSSS PROTECTIONS
Loss of both communication networks in 2 out of 3 MFT processorsOR Processor failure in 2 out of 3 processorsOR Processor outputs frozen in 2 out of 3 processors
OIL FIRING LDO
OIL BURNER ELEVATION AB ONLY
FUEL OIL SYSTEM MIMIC
HEAVY OIL FIRING MIMIC
Coal firing MIMIC
MFT trip logic diagram
REHEATER PROTECTION LOGIC
FSSS COMMISSIONING PROCEDURE…