Use of Cheap, Sacrificial Materials for Valve Trim in Erosive Slurry Applications: Final Report

摘要

Laboratory tests were done to evaluate the feasibility of three novel concepts for high pressure let-down or control valves in abrasive/erosive slurry applications. All three assumed inexpensive, sacrificial materials to be eroded away and continuously replaced in service. A method was established for accelerated observation of erosion phenomena, using slurries of fine quartz dust, several times as hard as coals, in water at ambient temperature, acting on test fixtures of soft materials such as acrylic plastic. By this simulation method, erosion phenomena for novel slurry valve and pump designs can be studied with time and costs reduced by at least an order of magnitude. Of the design concepts studied, the Lathe Valve, used an expendable steel rod closing against the end of a thick-walled tube. Slow rotation of the rod delayed but failed to prevent valve failure by channeling of the plug or seat. With alternate valves in parallel, in a common housing, one can be reground, using the slurry as a grinding medium, while the other is controlling flow. The Mud Turbine involves closely opposing disks of expendable material, with flow spirally inward to an exit through one of the supporting shafts. Fluid friction railed to rotate the disks, as desired for process energy recovery, while seal and bearing problems were excessive. The most successful design was the Gravel Bucket, in which the slurry passes through a packed bed of narrowly sized, continuously replaceable crushed rock, with flow controlled by varying the flow pattern through the bed. No plugging or channeling occurred. (ERA citation 12:034463)