About recomended velocities for two phase flow

[belenherminia]

Hi,
I have to size a two phase flow pipe and I need to know what is the general criteria for sizing (velocities max.)
Is a C4/C3 stream With vapor and liquid

Thanks

 

[zdas04]

The decision is economic, not technical. Multiphase flow is very expensive in terms of pressure drop. The faster you try to flow each phase, the higher the pressure drop. If you have a non-zero (gauge) delivery pressure requirement, then you need to determine how much pressure drop you can reasonably afford to tolerate. I've seen systems where this analysis caused us to speed up flow (increase upstream pressure) and others where it caused us to slow the flow down (decrease upstream pressure). If your liquid velocity gets much over 100/sqrt(liquid density) then you have erosion risks, but I've rarely seen a multiphase system with the superficial liquid velocity anywhere close to that (even with the gas superficial velocity approaching Mach 1.0).

David

 

[SeanB]

Generally we try to limit the velocity of a 2 phase system to between 40-70% of the erosional velocity.