×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

psv - set pressure higher critical pressure

psv - set pressure higher critical pressure

psv - set pressure higher critical pressure

(OP)
we have a vessel to protect by overpressure during a fire, the fluid has a critical pressure below the set pressure of the PSV so there isn't true latent heat.
How must the flowrate of fire contingency be set?

Tx for replies

RE: psv - set pressure higher critical pressure

Treat this vessel as if it is gas filled, because in a sense, it is.  You need to protect it by means that either don't reseal (rupture disk or buckle pin etc), or thermally.

RE: psv - set pressure higher critical pressure


It's important to understand that safety valves are generally incapable of protecting a vessel from fire exposure unless that vessel is at least partly filled with liquid, and that liquid will boil at a temperature that is not too excessive.

Moltenmetal provided real good advice - treat this supercritical fluid as if it's a gas - a very high density gas. If you're going to rely entirely on a relief device to protect a gas filled vessel from fire, then a non-reclosing device is what you need. A safety valve will not prevent the vessel from failing.

I just wanted to add that there's an alternate solution, if you hate rupture disks as much as I do. Whenever you use disks, you have to worry about premature disk failure, and that in itself can have some pretty unacceptable consequences. The alternative is to use a safety valve, but rely on other means to provide real protection. That is, use one, or any combination of the following protective measures, depending on the severity of the hazard: (1) auto depressurization, (2) water spray, (3) fire resistant insulation.
 

RE: psv - set pressure higher critical pressure

...or a fusible plug, which is what I meant by "thermally".

RE: psv - set pressure higher critical pressure

Ryan Ouderkirk published a paper "Rigorously Size Relief Valves for Supercritical Fluids" in CEP August 2002 that may provided a method  for this case.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources