Draining Boiler Feedwater

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rosli Associate Join Date: Jun 2008 Location: Malaysia Posts: 25	Draining Boiler Feedwater 12/08/2009 8:53 AM
	My friend ask me if we need to bring down the temperature,say around 150 deg Celcius of feedwater to below 100 degree Celcius or lower before we can drain the feedwater tank completely for work on the feedwater tank piping.Or we can just drain the feedwater tank at 150 degree Celcius as the drain does not cause any harm.
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tcmtech Guru Join Date: Jun 2009 Location: South of Minot North Dakota Posts: 8376 Good Answers: 775	#1 Re: Draining Boiler Feedwater 12/08/2009 12:34 PM
	doesn't water at 150 C flash into steam when the pressure is released at that temperature?
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PWSlack Guru Join Date: Jan 2007 Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on. Posts: 32175 Good Answers: 839	#5 In reply to #1 Re: Draining Boiler Feedwater 12/09/2009 3:57 AM
	It certainly does. The original poster will want to stand well back! __________________ "Did you get my e-mail?" - "The biggest problem in communication is the illusion that it has taken place" - George Bernard Shaw, 1856
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mike k Guru Join Date: Apr 2008 Location: Bristol, Tennessee Posts: 1177 Good Answers: 58	#2 Re: Draining Boiler Feedwater 12/08/2009 10:20 PM
	When you remove the water at that temperature, the last little bit of water could possibly get overheated by some hot part and just go nuts. I would wait. Add cool water to the boiler to bring the temp down. Not too cool, or you might shrink something. WAIT. __________________ mike k
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b v rao Power-User Join Date: Feb 2009 Location: India Posts: 155	#3 Re: Draining Boiler Feedwater 12/08/2009 10:56 PM
	You should make arrangements for safe flashing of the hot condensate. You can lead it to condensate staorage tank of large capacity of say 100m3 through a spray header immersed at the bottom if you want to conserve it. Or you can lead it to any blow down tank with vent pipe.
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sv13 Commentator Join Date: Jun 2009 Location: Between India & Australia Posts: 71 Good Answers: 3	#4 Re: Draining Boiler Feedwater 12/08/2009 11:30 PM
	Apart from the problem of flashing that someone already pointed out, you should be careful in draining anything above 60 °C to the waste water system. One of the reason is the drain pipes are HDPE/PVC etc. and these can't take more than 60 °C. Even a drain from an atmospheric blowdown vessel is generally cooled to <60°C before being routed to a waterwater system. __________________ Continuous Learning
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beriberi Power-User Join Date: Oct 2007 Location: NW Ohio Posts: 411 Good Answers: 25	#6 Re: Draining Boiler Feedwater 12/09/2009 8:52 AM
	I would question why your feedwater tank is 150C? This is 90psi and if it is a dearator then too high by 85psi or so. At any rate I would be very cautious opening this kind of pressure to atmosphere, plus as a previous poster mentions you could displease your muni operators if you send water to drain at a temp of just below boiling. What is the rush? __________________ Goodness has nothing to do with it.
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b v rao (1); beriberi (1); mike k (1); PWSlack (1); sv13 (1); tcmtech (1)

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