Is it a good idea to relieve in a atmospheric tank?
Is it a good idea to relieve in a atmospheric tank?
(OP)
Hello,
PSV set at 313 psig
Is it a good idea to relief this PSV into a atmospheric closed water tank? I heard that presure will convert into velocity and turbulenace when it exit from the tailpipe of PSV into a 180 barrel water tank.
Thank you!
PSV set at 313 psig
Is it a good idea to relief this PSV into a atmospheric closed water tank? I heard that presure will convert into velocity and turbulenace when it exit from the tailpipe of PSV into a 180 barrel water tank.
Thank you!





RE: Is it a good idea to relieve in a atmospheric tank?
I often see this configuration on sites where there was zero engineering in the exhaust piping (and no one considered the dP in the pipe to the tank changing the setpoint on an conventional PSV) or tank vent.
I have done the engineering on a couple of these and the clients were dumbfounded that I specified a pilot operated PSV (added cost), piping that was generally 2 pipe sizes bigger than they expected, and changes in the tank vent.
David Simpson, PE
MuleShoe Engineering
In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist
RE: Is it a good idea to relieve in a atmospheric tank?
Dejan IVANOVIC
Process Engineer, MSChE
RE: Is it a good idea to relieve in a atmospheric tank?
Depends whether you are relieving liquid or gas, and, as ZDAS04 says, how much / volumetric flow rate compared to the vent size of the tank and volume of the tank
If liquid then it might create turbulence, vapour and impinge on the side of the tank, but with the details you've provided (virtually none), it is very difficult to comment further.
Get it right - can be a good way of collecting whatever is coming out of the PSV.
Get it wrong - can be sudden and catastrophic failure of your water tank (think shrapnel and explosion)
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Is it a good idea to relieve in a atmospheric tank?
Further to the correct points raised above, I am also in the habit of adding 1.5 velocity heads to the vent pipe head loss calculated at the PSV capacity. You might find that a ~1 meter 8"-D gooseneck suddenly becomes 12"-D, or worse.
Pop tanks are common, but the vents are almost always too small for the service people try to put them into. I have often pulled off the thief hatch and added a second vent, where the service is not sour.
RE: Is it a good idea to relieve in a atmospheric tank?
RE: Is it a good idea to relieve in a atmospheric tank?
I am also thinking about what if all the liquid are sent to tanks and pipeline is flowing dry. now you have gas going into the tanl? what will happen in this case?
RE: Is it a good idea to relieve in a atmospheric tank?
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Is it a good idea to relieve in a atmospheric tank?
RE: Is it a good idea to relieve in a atmospheric tank?
Here is the attachment
http://files.engineering.com/getfile.aspx?folder=b...
RE: Is it a good idea to relieve in a atmospheric tank?
RE: Is it a good idea to relieve in a atmospheric tank?
I am not sure why they did not install valves that good for 1000 psig. I think because pressure won't get to 100 psig unless you do not have choke nipple.
however there is a choke nipple which should reduce our pressure from 1000 psig to very less. and the dump valves are not 100% in reality. All the flanges downstream of choke nipple are 150 psi series for some reason. I think it was a mistake. however, we do not want to replace these flanges to 300 # or 600 # since it takes long time to replace all the flanges ( there are probably 14 to 16 of them on each line).
However my question is about does it matter if i send my everything to tank? i am thinking i am inserting all the pressure again to atmospheric tank even though there is hatch to relief excess pressure which i am sure if it is pratical to do it.
RE: Is it a good idea to relieve in a atmospheric tank?
The thing you miss out is what is the venting arrangement on the tanks? given you're dropping 1000 psi across a choke, what you get in the middle / the other side must be an awful lot of gas and not much liquid? Be warned that the PSV sizing for multiphase flow is very difficult as I can't see how you won't have a lot of gas in both the oil and water streams.
However the key point is if the operator does as you say, then how much time / volume has tank 1 got left before it overflows?
You might want to consider a three way valve on the line instead of two tank valves so that if it changes over, then it automatically opens the other tank (lock open the inlet valve).
given that the flow and pressure will be the same whether you flow into the tank via the tank valve or via the PRV, then I would say this is the next best thing to do, but how you guard against overflow is the next problem on your list.
Of course only having one tank connected to the PRV is dangerous if you ever shut that tank off for maintenance as it could either jet liquid in or if it is shutoff then it won't work.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.