Flare adequacy check and modification
Flare adequacy check and modification
(OP)
My requirement is to add a PSV discharge to an existing flare system.
My plan is to model the entire existing flare system and then check for the adequacy of the new one.
What is the best way to model the same, is it by Modeling using Flare net or using Hysis dynamics environment.
My plan is to model the entire existing flare system and then check for the adequacy of the new one.
What is the best way to model the same, is it by Modeling using Flare net or using Hysis dynamics environment.





RE: Flare adequacy check and modification
If it does, look at what is % of flow from the new PSV vs. total relief flow in the flare header. If less than 5%, again you have nothing to worry about.
If more than 5%, it is worth checking how the system interacts. If you have access to Flarenet or Flaretot, that is probably the fastest way to check system performance.
I'd say, based on my experience, that only as you approach 0.5 Mach at the flare tip (assuming you operate subsonic flare) things can get more complicated.
Dejan IVANOVIC
Process Engineer, MSChE
RE: Flare adequacy check and modification
Expressions for compressible flow behaviour can be found in the API 520 / 521 and in Perry's Chem Eng Handbook if you want to build up a spreadsheet.
Calculations of this sort ( which also includes the calcs related to the derivation of the controlling case relief load which sets the PSV orifice size) are process safety critical and must always checked and signed off by at least one other senior engineer familiar with how these calculations are done. This checker engineer must be authorised in writing by Plant Engineering Management to sign off such calcs. All process safety related studies / calcs etc should be maintained as part of the overall plant safety case documentation for audit / Plant Operations staff reference material / insurance purposes.
RE: Flare adequacy check and modification
Peak flow case of each Relief system connected to flare is taken as the governing case for Flare sizing.
In the second point, Is it evident from any standards, to convince the client ?
RE: Flare adequacy check and modification
Is there any possibility to get the spread sheet you are mentioning.
RE: Flare adequacy check and modification
You didn't convince me, for example.
Dejan IVANOVIC
Process Engineer, MSChE
RE: Flare adequacy check and modification
Existing flare capacity is 35 MMSCFD and the the rated flow of new PSV is 24MMSCFD (governing case: Tube rupture)
RE: Flare adequacy check and modification
Dejan IVANOVIC
Process Engineer, MSChE
RE: Flare adequacy check and modification