A CFD analysis of the dynamics of a direct-operated safety relief valve mounted on a pressure vessel

Abstract

In this study, a numerical model is developed to investigate the fluid and dynamic characteristics of a direct-operated safety relieve valve (SRV). The CFX code has been used to employ advanced computational fluid dynamics (CFD) techniques including moving mesh capabilities, multiple domains and valve piston motion using the CFX Expression Language (CEL). With a geometrically accurate CFD model of the SRV and the vessel, the complete transient process of the system from valve opening to valve closure is simulated. A detailed picture of the compressible fluid flowing through the SRV is obtained, including small-scale flow features in the seat regions. In addition, the flow forces on the disc and the lift are monitored and analyzed and the comparison of the effects of design parameters, are examined; including the adjusting ring position, vessel volume and spring stiffness. Results from the model allow the fluid and dynamic characteristics of the SRV to be investigated and shows that the model has great potential of assisting engineers in the preliminary design of SRVs, operating under actual conditions which are often found to be difficult to interpret in practice.