Process optimization of close-coupled integrated two-stage liquefaction by the use of cleaned coals

Abstract

Recent advances in the direct liquefaction technology have drastically reduced the estimated price of crude oil from coal and the potential for further cost reductions by process optimization is demonstrated by the most recent data obtained at Wilsonville. The effects of coal cleaning on coal conversion and energy rejection, which are very important parameters in process optimization, are presented. Very high coal conversions (ca. 97 wt.% m.a.f. coal) and very low energy rejections (ca. 8%) are observed with a cleaned bituminous coal. The coal conversion increased with decreasing feed coal ash content, probably due to increased rejection of less reactive coal during cleaning. The energy rejection decreased with decreasing feed coal ash content due to reduced organics loss to ash concentrate. The results indicate that significant benefits with respect to process efficiency, operability and economics could be realized by cleaning coal prior to liquefaction. © 1989.