Study On Automaticality Flushing Device For Safety Valve Used In Fluid With Particles

Relief valve was wildly used in direct coal liquefaction. After a pressure relief, there always had coal partials on the seal set. A small gap between the disc and the nozzle was made, and the relief valve can not be closed, so inside leaks happened. And then, the seal set was worn much more intensively between the disc and the nozzle, the sealed capability of the relief valve was reduced. Flushing away the particles on the seal set efficiently is the key to solve the problem. So a type of automatically flushing device for relief valve used in fluid with solid particles was proposed, and the flushing process was simulated with Eularian model by FLUENT.The process of flushing online was simulated for the device without oil source. The flushing pipe and relief valve was connected by a three-way tube, chosing a appropriate angle for the tube and setting a reasonable pressure for flushing pipe-inlet were very impotent, After a very short time'flushing, the coal-volume fraction had been lower than 10-6in the flow filed between the disc and the nozzle. it can be considered that, the seal set has been flushed cleanly. The behaviour of the liquid-solid flow and the impact on the slurry-transporting process were also studied.The flushing structure which take accumulator as oil source equipment is studied. In different pressures, accumulator and inlet pipe of relief valve had been connected by three way tube in different angle. Then the flushing process of different devices was simulated with Eularian model, and the effection of flushing process was analyzed by different angle of three way tube and accumulator pressure. Flushing for a few seconds, fraction of the particles between disc and nozzle had been lower than 10-6, and the total quality of oil used for in the process was lower than the designing capacity for accumulator, so it considered the device can flush the salve's seal set. With comparing the result we knew that: in the same pressure, the device with 60°angle three-way tube made the lowest effection to the slurry transporting pipe, and the device with 45°angle three-way tube's effection was higher than the device with 60°angle three-way tube's. In different pressure, the device with 45°angle three-way tube could complete flushing process in lower pressure, and the quality of oil total used in the process and flowing into slurry transporting pipe was much lower, so the device with 45°angle three-way tube was better than the device with 60°angle three way tube.