Sizing of Safety Relief Valves for Gas/liquid Two-phase Flow

Abstract

Well-established recommendations exist for the sizing of safety valves and the connected inlet and outlet lines for steady-state, single-phase gas/vapor or liquid flow. However, in the case of a two-phase vapor/liquid flow, the required relieving area to protect a system from overpressure is larger than that required for single-phase flow. This report includes a widely usable engineering tool for the sizing of the typical safety valves. It is based on the omega parameter method, which is extended by a thermodynamic non-equilibrium parameter. The recommended sizing procedure starts with the definition of the sizing case and includes a method for the prediction of the mass flow rate required to be discharged and the dischargeable mass flux through a safety valve.