back-pressure calculation

[farahnaz77]

I need some basics about back-pressure. My problem is about sour gas flowing through a 12” pipe(branch) with pressure of 2 bara @ 39.45 deg.C. can it enter into a 52” or 24” header which sour gas with press. Of 1.5 bara @ 38 deg C is flowing through it?
thanks

 

[Montemayor]

yes

Art Montemayor
Spring, TX

 

[TD2K]

Maybe.

You need to calculate the pressure you need to flow the sour gas through your piping with a delivery pressure of 1.5 bara. If the source pressure you calculate is less than your 2 bara available pressure, you are okay. If it's higher, you won't be able to flow 100% of the gas OR you will have to accept a higher backpressure.

The key question is how much 12" pipe and fittings you have before the larger header.

 

[farahnaz77]

first, thanks
I meant the pressure of gas at connection point is 2bara ( at 12" pipe),i.e. after calculating and considering pressure loss.

 

[MortenA]

Your problem description is quite frankly quite difficult to understand propably due to language difficulties.

The pressure at a branch is allways the same for all connecting pipes.

So you can have 2 bara in the 12" and 1.5 in the header. There will be either or at both the header and the 12" branch.

Calculate your "back pressure" backwards.

E.i. start from the tip (or the drum) with flow from all your sorces calculate to each branch where you have a relief flow backwards. The from each branch to the relief source. Remember then to correct the flow rate if you r backpressure causes this to change.

You must do this systematiccally. Make a special PFD to summarize information.

Best regards

Morten

 

[25362]

The added flow may change your "back" pressure. Thus one should estimate what this back pressure will be upon "injecting" additional sour gas from the 12 in. branch into the larger header.