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[S Manikandan]

Dear all 

 

In a flare system analysis, I have query on determining back pressure for a PSV in a particular scenario (eg: Fire scenario, having simultaneous relief of other PSVs in the same fire zone). In my case, the max operating pressure of flare header is 0.35 kg/cm2g. Since, I do not have any information about flare tip at this moment, i have fixed the system back pressure as 0.35 kg/cm2g in flarenet and proceeded for tail pipe sizing. Now my question is, from flarenet how to determine variable superimposed back pressure and built-up back pressure for a particular PSV in fire scenario.

 

Attached is the sceen shot of flarenet model  post-43371-0-04106800-1446216106.png   187.76KB   19 downloads

 P.S: I understand that both system back pressure and constant superimposed back pressure are same (0.35 kg/cm2g).

 

Thanks in advance.

[shan]

A flare system back pressure at a specific location should be varied with the released rates downstream to the flare tip, which is not a constant value.  You are able to get a PSV outlet back pressure from Aspen Flare System Analysis model.