PSV for dense phase CO2 pipeline
PSV for dense phase CO2 pipeline
(OP)
I am working on a high pressure dense phase CO2 pipeline.
I am a recent graduate in chemical engineering and have not sized a PSV before. My company has a sizing spreedsheet, but I wanted to make sure I am addressing everything that needs to be addressed. This is the reason for posting to this site. Here are my initial concerns: This PSV will be in an enclosed building. Therefore the PSV will vent outside the building. The operating pressure of the pipeline is 1,800 psig. The JT effect from a DP of 1,800 psig to atm will reduce the temperature to below -50F. How is this temperature drop handled? Do you use low temp steel or heat trace, or is there another way to handle it? Also, what am I missing or what other things do I need to consider when sizing this PSV.
Any comments are greatly appreciated,
Thanks,
Christian
I am a recent graduate in chemical engineering and have not sized a PSV before. My company has a sizing spreedsheet, but I wanted to make sure I am addressing everything that needs to be addressed. This is the reason for posting to this site. Here are my initial concerns: This PSV will be in an enclosed building. Therefore the PSV will vent outside the building. The operating pressure of the pipeline is 1,800 psig. The JT effect from a DP of 1,800 psig to atm will reduce the temperature to below -50F. How is this temperature drop handled? Do you use low temp steel or heat trace, or is there another way to handle it? Also, what am I missing or what other things do I need to consider when sizing this PSV.
Any comments are greatly appreciated,
Thanks,
Christian





RE: PSV for dense phase CO2 pipeline
But its not certain that the steel will acquire the same temperature as the fluid. A resent article in Hydro ´carbon processing addressed this subject and found that in many cases the temperature dint get this low.
Best regards
Morten
RE: PSV for dense phase CO2 pipeline
The problem with a relief valve and its materials of construction will be deciding on its individual materials. Finding low temperature springs that have the allowable stress at 1800 psig is tough. So, again, analyze the risk of a fail using carbon steel and the appropriate material for the spring (or pilot operated parts). ou should be able to stick with a carbon steel valve too.
RE: PSV for dense phase CO2 pipeline
Normal A333 6 SMLS CS for pipe could have a design temp as low as -46deg C/-50 degF. But since its CO2 it may be something more corrosion resitant?
Best regards
Morten
RE: PSV for dense phase CO2 pipeline
For me, normal carbon steel is ASTM A106 Gr B SMLS, which is good to -29 to 200 °C.
If you need to go below -50 °C with CO2, I am thinking 316SS?
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RE: PSV for dense phase CO2 pipeline
Are you going to make your entire pipeline out of 304SS? If you have a line rupture in the middle of nowhere, the whole line, including those portions running through people backyards will auto refrigerate to -100F. Now what, -100 F line made of carbon steel?
RE: PSV for dense phase CO2 pipeline
RE: PSV for dense phase CO2 pipeline
Good point!
Best regards
Morten
RE: PSV for dense phase CO2 pipeline