1 reply to this topic

[Shauno]

Hi,

I am working on modeling a propane truck loading facility in the Southern US.

The system pumps propane from a storage vessel at saturated conditions to a propane truck loading station.

I want to determine the loading rates over the duration of loading a truck.

I'm assuming that the empty truck is at saturated conditions for ambient temperature when it first hooks up to load. Based on the system hydraulics, I can determine the initial loading rate.

The problem is, how do I know what the pressure is when the truck is ~ 80 % full? I do not think it's just a matter of P1V1=P2V2 as there is some cooling due to flashing, some recondensing, etc. If I know the pressure, I can model the flow rates.

Any help would be much appreciated.

[djack77494]

Shauno,
I think you are overanalyzing the problem. Don't reinvent the wheel. Well known, acceptable, robust solutions to loading and unloading trucks and railcars with liquified gases such as propane were developed and proven long ago. Most of the pump-oriented solutions that I have seen have a vapor return line going from the vehicle being loaded back to the storage vessels that is being unloaded. The problem you are imagining does not exist! As liquid enters the vehicle, an equal volume of gas is displaced back to the unloading vessel. No modeling needed, but a reality check involving seeing what actual successful operations look like is required. Apply this approach frequently.