Materials Selection for High-Pressure Letdown Valves in Coal-Liquefaction Systems

摘要

The high pressure letdown valve used in coal liquefaction processes must operate in a coal/ash/solvent slurry at 520 to 720 K and with letdown pressures from 1.0 x 10 exp 7 to 2.0 x 10 exp 7 Pa. The slurry is corrosive and extremely erosive. Proper materials selection which, for this application, has ranged chronologically from stainless steels, to stellite alloys, to cemented carbides is imperative for long lifetime components. The interdependence sound of mechanical design and materials selection is reviewed. The properties that make a given material erosion resistant are presented. Erosion performance of advanced ceramic materials such as SiC, Si sub 3 N sub 4 , B and TiB sub 2 are evaluated, and their possible use as coatings discussed. (ERA citation 06:010139)