The increased emphasis on safety in the petrochemical industries has produced greater sophistication in the analysis of overpressure concerns. One area where this is particularly evident is in the study of two-phase flow in pressure relief devices (PRDs).
Two-phase flow can develop in pressure vessel systems requiring overpressure protection because of fires, control valve failures, runaway reactions, and other process upsets. Of particular concern are situations involving the flashing of liquids through PRDs because the resulting volumetric flowrate will be much more than if the fluid remained in a liquid phase. Not applying proper sizing techniques can result in undersized relief valves, thus resulting in overpressuring equipment.
