Stopping and Depressurising procedure for Marine Boilers
Boiler needs to be stopped for various reasons like maintenance, survey etc. Depressurising the boiler is a lengthy procedure, before depressurising please read the manual and risk assessment that is to be taken.
> Close main steam stop valve
> Stop the feed water pumps and fuel oil circulating pumps. If there is heater for fuel oil, stop it.
> Make sure that vessel is not in loaded condition. If its loaded there is a chance of sea water flowing back to the boiler while blow down
> After completing the change over, stop EGB circulating pump and close the suction side valve from boiler and discharge side valve to Boiler
> Open the vent for EGB
> Stop the boiler and stop boiler feed water pump
> Close the valve for feed water controller
> Isolate DP transmitter by opening the equalizing line and closing inlet-oulet lines
> Start blow down the boiler until low low water level alarm comes
> Let the boiler pressure comes to 2 bar
> Make sure that boiler body temperature coming down gradually
> When the drum pressure come to 2 bar open the vent
> Wait until the pressure comes down to 0-0.2 bar
> Start draining rest of the water if required give pressurized air through air vent so that all water will get drained out.
You Can Answer Following Questions,
> How to stop the boiler
> Procedure for depressurising the boiler
> Why it is difficult to drain the boiler if the vessel is in loaded condition
> At what pressure you should open air vent while depressurising boiler
> How do you prevent vacuum generating inside the boiler while stopping the boiler?
If you know more or have doubts please comment below
Boiler needs to be stopped for various reasons like maintenance, survey etc. Depressurising the boiler is a lengthy procedure, before depressurising please read the manual and risk assessment that is to be taken.
Must Read: How to Cold Start Marine Boilers
Here you will get a vague idea about boiler depressurising.
> Change over FO to Do, all systems like ME, AE and Boiler. Because with out steam you cannot use HFO
> Turn the switch in to stop position, boiler will automatically stop after post purging. (If it’s required ,purge the furnace manually)> Close main steam stop valve
> Stop the feed water pumps and fuel oil circulating pumps. If there is heater for fuel oil, stop it.
> Make sure that vessel is not in loaded condition. If its loaded there is a chance of sea water flowing back to the boiler while blow down
> After completing the change over, stop EGB circulating pump and close the suction side valve from boiler and discharge side valve to Boiler
> Open the vent for EGB
> Stop the boiler and stop boiler feed water pump
> Close the valve for feed water controller
> Isolate DP transmitter by opening the equalizing line and closing inlet-oulet lines
> Start blow down the boiler until low low water level alarm comes
> Let the boiler pressure comes to 2 bar
> Make sure that boiler body temperature coming down gradually
> When the drum pressure come to 2 bar open the vent
> Wait until the pressure comes down to 0-0.2 bar
> Start draining rest of the water if required give pressurized air through air vent so that all water will get drained out.
You Can Answer Following Questions,
> How to stop the boiler
> Procedure for depressurising the boiler
> Why it is difficult to drain the boiler if the vessel is in loaded condition
> At what pressure you should open air vent while depressurising boiler
> How do you prevent vacuum generating inside the boiler while stopping the boiler?
If you know more or have doubts please comment below