Pressure Control on Free Water Knockout?

Question

I need to install a self contained pressure control valve on a pressure vessel that will open when the vessel pressure drops to 15 psig. The worst case scenario for outlet is 25,000 bpd of oil and 200,000 bpd of water. How do I size the gas flow rate for the control valve? Do I need to convert the volumetric flow out to an equivalent flow rate of gas in? How do I do this and what part of the calculation does the 15psig come in to?

Answer 1

First, you need a pressure sensor for the 15psig. I assume it is the space above the liquid, so hydrostatic pressure is ignored.

You do indeed need to equate the Q out to the gas flow rate in. Gas is measured in SCFM, you need the SCFM to match the Q out. Adjust SCFM by 15/14.7 psi to match the SCFM to the actual Q. The size matches only if the bpd is the actual instantaneous rate, not the rate averaged over a day.