Help
Help
(OP)
Dear All,
Background: A closed vessel(3'X 10' horizontal, initial pressure is 520psig,30degC, sweet gas, will be released to flare within 5 mins and finial pressure is 320psig. How to determine the relif pipe size.
The problem i have is when the relief valve open, the inlet stream is closed and th evessel is a closed vessel which means there is no constant flow rate coming to the vessel, only the relief valve is opening. Of course, if there is a constant flow stream continues to feed to the vessel, that's a simple one, but for this closed vessel, pls give any tips.
Thanks in advance
Background: A closed vessel(3'X 10' horizontal, initial pressure is 520psig,30degC, sweet gas, will be released to flare within 5 mins and finial pressure is 320psig. How to determine the relif pipe size.
The problem i have is when the relief valve open, the inlet stream is closed and th evessel is a closed vessel which means there is no constant flow rate coming to the vessel, only the relief valve is opening. Of course, if there is a constant flow stream continues to feed to the vessel, that's a simple one, but for this closed vessel, pls give any tips.
Thanks in advance





RE: Help
Katmar Software
Engineering & Risk Analysis Software
http://katmarsoftware.com
RE: Help
Good luck,
Latexman
RE: Help
http://www.air-dispersion.com/feature2.html
If you label your post properly, Milton Beychok may answer you personally.
Good luck,
Latexman
RE: Help
For sizing a relief valve, you may want to use the instaneous initial flow rate (which is the worst case). In that event, instead of the article referred to by Latex, it is very much simpler to use:
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Milton Beychok
(Visit me at www.air-dispersion.com)
.
RE: Help
I wondered about that, but the OP was pretty precise about stopping at 320 psig within a 5 minute duration, so I wasn't real sure if he wanted a PSV or something else and he didn't explain it fully.
Good luck,
Latexman
RE: Help
You are right, the original poster really needs to give us more explanation. What happens after the 5 minutes and the vessel pressure is reduced to 320 psig?
Milton Beychok
(Visit me at www.air-dispersion.com)
.
RE: Help
David
RE: Help
sorry for delay to provide all details about this thread and appreciate all nice peopel here for great help indeed! Actally, this is a As-build equip rennovation project, the question is coming from process' request, which meams when the inlet stream is closed, the separator shall be isolated and consequently a control valve in the existing 2" line will open to release the gas to the flare. However, the condition are (1)the opening of the control valve will maintain within 5 mins to lowdown the pressure from 520psig to 220psig, (2) as long as the pressure reach to 220psig, the control valve shall be closed. (3) the interesting point here is time, they require about 5 mins to do the job. is it interesting? so, initially, i think this is a simple question, however, while i think about it carefully, i realize this is a quite tough questuion. during the release period, the inside pressure will reduce accordingly, which meams the flow rate will reduce accordingly. it's like a puzzle. this is why i post the thread to ask for help. Now, i calculate the result is 1/4" opening of the control valve can satify the requirement. But, i am still wondering the result. Might be 1/8" opening is ok.
Thanks for all here!