Boiler force Cooling

Boiler force Cooling :

In case of tube leakage:

After Tripping the boiler ,stop FD fan and keep ID fan running at minimum load and ensure furnace pressure negative inside boiler.

Reduce pressure as per boiler cooling curve Annex-1 by opening startup vent /HP/LP bypass and maintain drum level by feed water supply. (During pressure reduction maintain Drum Top/Bottom DT below 50 Deg C )

After two hour of Boiler tripping start FD fan and reduce pressure as per boiler cooling curve ( Annex-1) . Limit Drum Top/Bottom DT below 50 Deg C. during depressurisation.

Open SH drain at 10 KSC and open SH Vents at 4 Ksc.

Open Drum Vents at 2 KSc.

Drain boiler when boiler water temperature is below 94 Degree C

Keep ID & FD fans running till temperature inside boiler becomes comfortable for maintenance personnel to go inside boiler and attend the tube leakage.

Other Than Tube leakage :

• Operate Wall Blower and LRSB during Load reduction
• Gradually reduce load and allow pressure drop to accelerate cooling & steam temperature drop as per Turbine manufacturer recommendation
• Trip the Boiler
• After Tripping the boiler ,stop FD fan and keep ID fan running at minimum load and ensure furnace pressure negative inside boiler.
• Reduce pressure as per boiler cooling curve Annex-1 by opening startup vent /HP/LP bypass and maintain drum level by feed water supply. (During pressure reduction maintain Drum Top/Bottom DT below 50 Deg C )
• After two hour of Boiler tripping start FD fan and reduce pressure as per boiler cooling curve ( Annex-1) . Limit Drum Top/Bottom DT below 50 Deg C. during depressurisation.
• Open SH drain at 10 KSC and open SH Vents at 4 Ksc.
• Open Drum Vents at 2 KSc.
• Drain boiler when boiler water temperature is below 94 Degree C
• Keep ID & FD fans running till temperature inside boiler becomes comfortable for maintenance personnel to go inside boiler and attend the tube leakage.

Note:

• Feed water filling and draining should not be done for accelerating cooling.
• In case of tube leakage in Pent house area ,exhaust fan to be put into service.
• Water washing in water wall area should be done only after draining of boiler.
• Water washing inside the boiler should be done only after tube metal temperature in the location where water washing intended falls below 94 deg C in that location.
• Water washing in the penthouse should be done only after header metal temperature in the location where water washing is intended ,falls below 94 deg C in that location.