SOLIDS PRECIPITATION PROCESS FOR COAL- DERIVED LIQUIDS USING RECYCLED SOLVENT FRACTIONS

摘要

SOLIDS PRECIPITATION PROCESS FOR COAL-DERIVED LIQUIDSUSING RECYCLED SOLVENT FRACTIONSABSTRACTA solids removal step for coal liquefaction-hydrogenatiprocesses utilizes the addition of a selective solvent liquidfraction to coal-derived liquids to produce rapid precipitation ofsolids and thereby achieve a high percentage of solids removalfrom the coal-derived liquids. It uses a selected solvent additiveliquid fraction which is convenient obtained from the coalliquefaction process by distillation, without need for additionalhydrogenation steps or the addition of any extraneous liquids.The solvent liquid used is a coal-derived liquid fraction boilingbetween about 300-550°F, which has a Watson characterizationfactor (K) in the range of 9.5-11, and also has a Kauri-butanolvalue exceeding about 40 and preferably is 50-130. Followingmixing of the two hydrocarbon liquids together, the resultingsettling time for particulate solids in the liquid mixture isrelatively short, usually less than about 45 minutes and undercertain conditions may be about 15-30 minutes.The resulting clarified overflow liquid portion fromthis solids precipitation step contains less than about 0.1 W %ash and unconverted coal solids, while the underflow liquidportion contains 30-50 W % solids and may receive further processingas desired, such as coking. Although this solids precipitationstep is useful with various coal liquefaction processes, it ispreferably used with catalytic hydrogenation processes such asthe H-Coal? process wherein between about 2 and 4 W % hydrogenis chemically combined with the coal derived liquid.