Gasbuffer in pipeline

[eltjo]

We at work have a discussion about the gas buffering in a pipeline.

The case:
We have a 100 km pipeline 30" with no output @ 25 bar(g). What will happen with the pressure at the end of the pipeline if we assume an output of 10 m/s @ 25 bar(g) (=x kg/hour) by opening a valve and an input of x kg/hour with 25 bar(g)(similar to output).

One of the collegues states that the pressure in the whole pipeline will stay 25 bar(g) and only at the end of the pipeline pressure drop over a valve will occur, but mainly the pressure would stay around 25 bar(g).

An other collegue states that you need a driving force (pressure drop) to move the molecules, therefore you can calculate a static pressure drop with x kg/hour and you have the pressure at the end.
Pin=25 bar(g)
Pout=13.4 bar(g)
Flow=107 kg/s (calculated with 10m/s @ Pout)

But what about the pressure in the beginning, it was 25 bar(g) and it will suddenly change to the calculated value?

Who can tell us what will really happen?

Regards,
Eltjo

 

[MortenA]

A 100 km pipeline will experience a pressure drop when flowing at a velocity of 10 m/sec - so there will be a pressure difference from inlet to outlet.

The steady state pressure profile will take a while to establish. Transient simulations could reveal how long.

Best regards

Morten