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Flare Back Pressure Estimation At Basic Design

#flare #backpressure

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#1 Mahdi Malek Alaie

Mahdi Malek Alaie

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Posted 10 April 2023 - 03:22 AM

Dear All,


I hope you are doing well.


1- Can anyone explain how we can estimate the flare backpressure at basic engineering when there is no data in hand?


2- as you know, flare backpressure can be specified by user or software in Aspen Flare Net. Which choice is more common? what problems will be happened if all backpressure will be calculated by software?



Thank you in advance !



#2 Pilesar


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Posted 10 April 2023 - 06:54 AM

For a new plant design, there is ability to control flare system back pressure with header sizing. For relief valves, I assumed a conservative back pressure wherever possible to avoid rework and allow for plant expansion later. As long as the vessel operating pressure is away from MAWP, this is no problem. For example, if I expected about 15 psi back pressure at the relief valve, I might assume 25 psi or 30 psi for valve specification. Optimizing too tightly to pressure calculations didn't seem to have much economic payback for safety systems.

#3 Bobby Strain

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Posted 10 April 2023 - 02:36 PM

Occasionally there are both high pressure and low pressure flares. Nothing is better than experience.



#4 shvet1


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Posted 10 April 2023 - 10:47 PM

Depends on combination of [a] MAWP of vessels depressurized, [b] flare type, [c] flare header length, [d] PSVs types.
Note that backpressure is more a result of an economical optimization rather than a blind engineering. Backpressure is a result of calculations/iterations, it is not an input data. As for some kind of an atypical process unit this might become a challenging issue. Therefore as posted above


Nothing is better than experience.



More details = better comments

Edited by shvet1, 10 April 2023 - 10:52 PM.

#5 Mahdi Malek Alaie

Mahdi Malek Alaie

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Posted 10 May 2023 - 06:08 AM

Dear All,

Thanks for your explanation.

I got it. 

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