Boiler blowdown flash vapor recuperation.

[jisita]

Hello,

In our factory we have two 13,000 lbs/hr boilers, the blowdown goes into a flash tank, and there the vapor goes to the athmosphere, is it possible to recover this vapor?

One of the engineerings in the factory saids that it isn't possible, because it's low pressure steam, and that we will need an oxigen trap, and that this is not economically viable, did you agree with him?

 

[Joesteam]

You mentioned the size of the boilers you have but not the pressure they operate at. You can flash the blowdown and you will get lower pressure steam than the boiler. The most common use for this low pressure steam is in the deaerator, and this is usually done with the surface (continuous) blowdown and not the bottom blowdown.
Another common method to increase effeciency is to use the continuous blowdown in a waste heat exchanger on the feedwater line. You have the opportunity to grab more heat out of the blowdown because with flashing you only get a small percentage of the BTU's going into the steam flow.