Sudden vaporization of water
Sudden vaporization of water
(OP)
Hello, I am looking to size a relief valve for a case where we contaminate an organic feed with water. This feed would flow through several heat exchangers until it reaches the bubble point of water. Would this be calculated by simply taking the latent heat of vaporization of water at relief pressure and dividing it into the heat duty of the exchanger where it would reach bubble point?
Thanks,
Thanks,





RE: Sudden vaporization of water
Good luck,
Latexman
To a ChE, the glass is always full - 1/2 air and 1/2 water.
RE: Sudden vaporization of water
Bubble point to me is when a dissolved gas is released due to low pressure or maybe when some compound vapourises, but this seems to refer to boiling point?
But where does extra pressure come from? As the steam appears, then the pressure rises and the boiling point increases. It takes quite a high rise in temperature for pressure to climb much above the "normal" pressure such that a pressure relief system can operate successfully.
Unless the water generates some kind of reaction which then runs out of control ("organic feed" is a bit vague) then I think you need to actually work out your pressures and temperatures a bit more here. IMO.
A diagram and a bit more description would help.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Sudden vaporization of water
Use a steam table to find the correspoing BP at your operating prerssure (e.g. 1 bar (a), BP=100ºC and 15.5 bara BP=200ºC etc)
When a liquid boils, adding more heat will not change temperature (assuming the pressure stays constant) - so a volume of water equivalent to the laten heat/heat input will evaporate. The steam table will give you latent heat at your pressure. On the other hand if your volume stays constant (a closed cylinder) so does your average density and you can use this to solve for pressure/temperature using the increase in enthalpy cause by adding heat.
Best regards, Morten
RE: Sudden vaporization of water
Good luck,
Latexman
To a ChE, the glass is always full - 1/2 air and 1/2 water.
RE: Sudden vaporization of water
The equipment and piping is 150# class. Since water boils at 366 deg F at 150 psig, we are concerned with this scenario.
I hope that is a better description, and thank you for the replies so far.
RE: Sudden vaporization of water
Good luck,
Latexman
To a ChE, the glass is always full - 1/2 air and 1/2 water.
RE: Sudden vaporization of water
In general, the equipment would be N2 purged, dead legs blown dry, and slowly heated up as feed is introduced.
Thanks again,
http://www.eng-tips.com/viewthread.cfm?qid=294940
RE: Sudden vaporization of water
Good luck,
Latexman
To a ChE, the glass is always full - 1/2 air and 1/2 water.