Blowdown prediction of a conventional pressure relief valve with a simplified dynamic model

In this research, a simplified dynamic model (SDM) is developed to predict the dynamic characteristics during the reclosing process and blowdown of a conventional pressure relief valve (PRV). The principle of the SDM is based on the equation of motion for one degree of freedom system. The damping effect is ignored due to its little effect on the reclosing time; a pressure drop condition based on lots of experiments is assumed. In addition, it is very novel that the SDM combines the static CFD analysis result, that is, the lift force coefficient of the valve at several fixed lifts is calculated with static CFD analysis, and then imported into the SDM as the inherent characteristics of the valve. The case study proved that the SDM is very reliable to predict the dynamic characteristics and blowdown of the conventional PRV.