摘要 |
A multi-stage coal liquefaction method in which coal is slurried with a primary light solvent, such as toluene, hexane and/or cyclohexane, and a process-derived primary heavy solvent. The coal-primary solvent slurry is treated under coal-liquefying conditions to form a first feed solution containing coal liquefaction products. The first feed solution is treated by a multi-stage supercritical solvent extraction procedure. The final heavy phase produced by this procedure is mixed with a secondary solvent, such as pentane, to produce a second feed mixture, which is treated in a second multi-stage supercritical solvent extraction procedure. Heavy phases recovered from the separate stages of both solvent extraction procedures are blended to provide a recycled primary heavy solvent.
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