Boiler Forced Cooling
1 In case of Tube leakage
1.1 After Tripping the boiler ,stop FD fan and keep ID fan running at
minimum load and ensure furnace pressure negative inside boiler.
1.2 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 )
1.3 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.
1.4 Open SH drain at 10 KSC and open SH Vents at 4 Ksc.
1.5 Open Drum Vents at 2 KSc.
1.6 Drain boiler when boiler water temperature is below 94 Degree C
1.7 Keep ID & FD fans running till temperature inside boiler becomes
comfortable for maintenance personnel to go inside boiler and attend
the tube leakage.
2 Other Than Tube leakage
2.1 Operate Wall Blower and LRSB during Load reduction
2.2 Gradually reduce load and allow pressure drop to accelerate cooling &
steam temperature drop as per Turbine manufacturer recommendation
2.3 Trip the boiler & thereafter stop FD fan and keep ID fan running at
minimum load and ensure furnace pressure negative inside boiler.
2.4 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 )
2.5 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.
2.6 Open SH drain at 10 KSC and open SH Vents at 4 Ksc.
2.7 Open Drum Vents at 2 KSc.
2.8 Drain boiler when boiler water temperature is below 94 Degree C if
required
1 In case of Tube leakage
1.1 After Tripping the boiler ,stop FD fan and keep ID fan running at
minimum load and ensure furnace pressure negative inside boiler.
1.2 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 )
1.3 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.
1.4 Open SH drain at 10 KSC and open SH Vents at 4 Ksc.
1.5 Open Drum Vents at 2 KSc.
1.6 Drain boiler when boiler water temperature is below 94 Degree C
1.7 Keep ID & FD fans running till temperature inside boiler becomes
comfortable for maintenance personnel to go inside boiler and attend
the tube leakage.
2 Other Than Tube leakage
2.1 Operate Wall Blower and LRSB during Load reduction
2.2 Gradually reduce load and allow pressure drop to accelerate cooling &
steam temperature drop as per Turbine manufacturer recommendation
2.3 Trip the boiler & thereafter stop FD fan and keep ID fan running at
minimum load and ensure furnace pressure negative inside boiler.
2.4 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 )
2.5 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.
2.6 Open SH drain at 10 KSC and open SH Vents at 4 Ksc.
2.7 Open Drum Vents at 2 KSc.
2.8 Drain boiler when boiler water temperature is below 94 Degree C if
required
- 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.
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