Purge Gas Rate

There all,

I need solution to the problem below:


A purge gas is connected to a flare header line into a flare scrubber to ensure that there is no ingress of oxygen into the flare through the tip. The vessel is expected to be maintain at a certain pressure. Also, the purge gas pressure is required to maintain the pressure in the vessel when there's no relief load through the vessel. The pressure maintained in the vessel should be capable to push the liquids out through the flare scrubber liquid control valve into the sump tank.

A study was performed to show that at a certain pressure in the vessel, liquid can flow through the liquid line without the aid of a liquid pump. From the study, it was obtained that at 3 psig, liquid can flow from the flare scrubber into the sump tank. The flare scrubber is located on a upper deck and the sump tank is located on lower deck at the oil platform.

I need to validate the purge gas flow rate required for the flare header/ flare system. Also, I need to determine the amount of purge gas required to maintain the estimated pressure expected to be maintained in the vessel.

Is there a relationship between pressure and gas flow rate in a vessel?

Your response is highly appreciated.