Filippo Tamagnini - 2024-07-03

Hi Everyone,

I want to simulate the throttling part of a gas liquefaction process, and I have trouble understanding how the Gas-Liquid separator unit operation handles pressure-flow relationships in dynamic mode.

Specifically, i would expect that the pressure of the separator would change dynamically as the level of liquid increases/decreases, and that the flowrates in and out of the separator would be determined based on this pressure.

Instead, what i see is that the pressure is fixed to some arbitrary value, and that opening/closing the valves around the plant has no effect on the pressure inside the separator (it does change the flowrates though). Furthermore, the accumulation stream of the separator seems to be violating mass balances.

I have tried with no success several options (changing pressure/flow specifications, changing the valve calculation modes, tampering with the thermodynamic model options and enforcing the separator pressure) unsuccessfully, but i'm still not 100% sure if there's something conceptually wrong with what i'm doing..

I attach the simulation i'm working on hoping that you can help me figure this out. Running 8.7.1 on Windows.

Thanks!
Filippo

 
simpleDynValve.dwxmz