Abstract: Relief valves used in the coal liquefaction equipment are running in an extremely harsh environment with extraordinarily high pressure differential and intensely slurry flow erosion. Based on the finite volume method (FVM), the pressure and flow distributions of relief valves were analyzed, with K-ε turbulence and Mixture multiphase model. Moreover, for the new-style relief valves, variations of pressure drops with valve apertures and turbulence intensities with depths of valve seat hole were studied. Considering the fluid-erosion theory, optimal design was accomplished and the easywearing positions of the relief valves were accurately predicted to provide theoretical basis for the choice of wear resistant materials. The application results show that the easy-wearing positions are coincide with the predictions. Moreover, the working lifetime is largely elongated up to 1 200 hours and suitable for the practical application.

Key words: coal liquefaction relief valves, multiphase flow, computational fluid dynamics（CFD）, optimal structure designing