Stabilizer Flashtank with Slugs

[AggieCHEN04]

I'm currently designing a flashtank that is supposed to handle condensate from the inlet gas and periodic slugs. I am limited on the amount of outlet gas that can come from the flashtank (which will increase significantly as the slug hits). As a result there is a sharp pressure spike in the flash tank to maintain the vapor outlet at its maximum. Eventually the vapor rate and the pressure will return to the normal operating pressure of the stabilizer system.

Do you guys have any suggestions on how to model the pressure of the tank over time.