Advanced Direct Liquefaction Concepts for PETC Generic Units Phase II; 12/97; 389110

Pulverized Wyoming subbituminous coal was beneficiated by low-pH oil agglomerationat CONSOL to prepare the coal for direct liquefaction. Conventional cleaning is not veryeffective in cleaning this coal; for example, conventional oil agglomeration only givesabout 20% ash rejection. To improve ash rejection, the coal-water slurry was acidifiedto a pH of about 0.5. Oil agglomeration was effected with 33% (dry coal basis) of a coal-liquefaction recycle oil and high-shear mixing, producing agglomerates, which wereseparated from the rejected and dissolved inorganic matter by screening. The SO -free-3ash content of the coal was reduced by 40% (from 5.5% to 3.3%, dry basis) and theorganic recovery was nearly 100%. The alkaline elements that are potential scaling agentsand catalyst poisons were selectively rejected from the coal. Iron, a potential liquefactioncatalyst, was selectively retained with the coal. A 600 kg batch of coal-oil agglomerateswas produced. The liquefaction performance of this material was compared to that of theraw coal in the Hydrocarbon Technologies Inc. (HTI) 1.5 kg/h continuous-flow bench-unit. The agglomerates handled well and improved solids separation performance. Thecoal conversion with agglomerates (98% MAF) was higher than that with the raw coal(95% MAF), and the product yields (56% C -343 EC distillate and 66% C -524 EC44distillate, MAF basis) were excellent.