Numerical Investigation of Cavitation Erosion/Solid Particle Erosion in High Differential Pressure Control Valves in Coal Liquefaction

The high differential pressure control valves used in commercial direct coal liquefaction are suffered by severe cavitation erosion and solid particle erosion due to the high speed of gas-liquid-solid three-phase flow. Based on the k-ε model, Schnerr and Saur's cavitation model, discrete random walk (DRW) model and erosion model, the parameters including velocity, pressure, vapor volume fraction and erosion rate were obtained under typical opens of the valve by using CFD code. And the computational results also show that a cavitation region occurred near at the circular curve of plug, back-flow region with high velocity and high local pressure existed at the top of the plug. The prediction method for cavitation erosion in valve structure was developed by analyzing the comprehensive function of velocity, cavitation and pressure fields. In addition, the maximum solid particle erosion rate occurred at the top of plug and was increased during the closing process of the valve. The Comparison of the computational results with the failure feature of valve plugs used in coal liquefaction indicates that the present methods can predict the potential locations for cavitation erosion and solid particle erosion with sufficient accuracy. This numerical investigation is expected to provide some guidance on the optimization design of multiphase flow industrial devices.