LIQUEFACTION OF COAL

PURPOSE:To efficiently liquefy coal by hydrogenating coal in the presence of both an iron sulfide-based catalyst and a solvent, distilling and fractionating the hydrolyzed products, treating the distillation residue with a solvent to give an ash-containing solution, adjusting the solution to a proper temperature in a settling tank to separate ash and smoothly removing the ash. CONSTITUTION:Coal is hydrogenated in the presence of both an iron sulfide-based catalyst and a solvent, the hydrolyzed products are distilled and fractionated into a light oil, a middle oil, a heavy material and distillation residue containing ash, the distillation residue is introduced to a dissolver 1, blended with an ash removing solvent and the heavy material is dissolved to give an ash-containing solution. The solution is fed to a settling tank 2 by a solution pipe 3 having an outlet 4 of the solution pipe approximately at the central part of the settling tank 2, temperatures at the upper part and the lower part of the outlet 4 in the settling tank 2 are measured and changes in the temperatures with time are obtained. When difference in the temperatures is reduced, the ash removing condition is controlled, the ash and the insoluble heavy material in the solution in the settling tank 2 are settled, a solution having a low ash concentration is extracted from the top of the settling tank 2 and the ash is removed to efficiently liquefy coal.