Boiler blow down is one of most important routine jobs done on a main or aux boiler onboard a ship. I have a AALBORG MISSION OC- 2000 Kg/hr steam composite boiler and ALBORG MISSON OC- 20000 Kg/hr aux boiler onboard the vessel i am currently onboard. The boilers are being blown down regularly, when the water tests show an increased chlorine level , when conductivity increases ,or when the boiler water colour changes to reddish brown.
Blow down is needed to remove the sediments which get accumulated in the water ring on the boiler or when chlorine levels increase due to bad quality feed water ( when fresh water generator salinty is high).
PROCESURE TO BLOW DOWN:
1. Keep boiler firing ( this way you will have a better circulation of water inside the boiler)
2. Normally 2 valves are given on boiler side and 2 valves on the sea side for blowdown purpose. The idea behind giving two valves for blowdown in each of the places is that, The valves attached to the ships hull and the boiler body are very difficult to overhaul, when ship is sailing or in port. These valves can be overhauled when ship is in dock only( by adjusting list or blowing down entire boiler you can do this , but you know how hard it is :P). So normally dont play around with these valves and dont keep them throttled( throttling a steam valve or a high pressure line valve causes wire drawing effect which destroys valve seats and it starts leaking). Now, you need to control flow rate for blowing down, and how do u achieve that??? Throttle the valve which is not attached to the boiler body or the ships hull!! This is why 2 valves are given .
3.Open the valve attached to the ships hull and the boiler body fully first.
4.Open the sea side valve .
5.Throttle the flow rate using the second valve given after the valve attached to boiler body.Simple!!!
6. When water level reaches the normal level on guage glass, close the throttled valve first( see which valve is throttled from point no.5)
7. Close other valves.
8. Finish the blowdown.
This is my practise.. if u guys have any new ideas or suggestion please dont forget to leave them in comments. Happy sailing :)
Blow down is needed to remove the sediments which get accumulated in the water ring on the boiler or when chlorine levels increase due to bad quality feed water ( when fresh water generator salinty is high).
PROCESURE TO BLOW DOWN:
1. Keep boiler firing ( this way you will have a better circulation of water inside the boiler)
2. Normally 2 valves are given on boiler side and 2 valves on the sea side for blowdown purpose. The idea behind giving two valves for blowdown in each of the places is that, The valves attached to the ships hull and the boiler body are very difficult to overhaul, when ship is sailing or in port. These valves can be overhauled when ship is in dock only( by adjusting list or blowing down entire boiler you can do this , but you know how hard it is :P). So normally dont play around with these valves and dont keep them throttled( throttling a steam valve or a high pressure line valve causes wire drawing effect which destroys valve seats and it starts leaking). Now, you need to control flow rate for blowing down, and how do u achieve that??? Throttle the valve which is not attached to the boiler body or the ships hull!! This is why 2 valves are given .
3.Open the valve attached to the ships hull and the boiler body fully first.
4.Open the sea side valve .
5.Throttle the flow rate using the second valve given after the valve attached to boiler body.Simple!!!
6. When water level reaches the normal level on guage glass, close the throttled valve first( see which valve is throttled from point no.5)
7. Close other valves.
8. Finish the blowdown.
This is my practise.. if u guys have any new ideas or suggestion please dont forget to leave them in comments. Happy sailing :)
boler is in firing mode?
ReplyDeleteBoiler blowdown work regularly is very heavy, and has to drain 80 times switch valve. Large boiler taking time can be long, and poor working conditions, hot, fine ash, noise.
ReplyDeleteboiler heating treatment company in Ontario
Can you explain bit more , why there are 2 v/v's in ship side?
ReplyDelete