Abstract: A starting slurry composed of raw brown coal and a solvent is heated and pressurized, subjected to gas-liquid separation and dehydration and then to hydrogenation/liquefaction. The CO.sub.2 -containing gas produced in the preheating/dehydration step and/or a CO.sub.2 -containing gas supplied from outside the system is blown into the slurry in the above-mentioned preheating/dehydration step, whereby carbonate-forming metal components in the brown coal are converted to the carbonates thereof in advance. In this manner, the hydrogenation/liquefaction efficiency is improved, and stabilized long-term continuous operation is attained.

Abstract: Improvements in a process for reforming coal by subjecting a mixed slurry containing a hydrocarbon solvent and coal fines to hydrogenation reaction under high temperature and pressure conditions, gas-liquid separation, and distillation to obtain a solvent-refined coal, the improvements comprising: maintaining the reaction temperature and total reaction pressure within a hydrogenation reactor at 400.degree. to 500.degree. C. and 50 to 200 atms., and controlling the residence time distribution of reactants, excepting gaseous reactants, in the hydrogenation reaction zone to have an average residence time longer than 17 minutes, and to keep the quantity of the reactants which have a residence time shorter than 10 minutes in a proportion less than 20% by weight of the reactants.

Abstract: A method is disclosed for thermal dehydration of brown coal, by which an excellent heat recovery can be accomplished. The method includes the steps of admixing raw brown coal with a solvent to prepare a slurry, preheating the slurry in a heat exchanger, heating the same at 100.degree. to 300.degree. C., passing it through a gas-liquid separator to separate it into a steam-containing vapor and a dehydrated slurry and recoverying the dehydrated slurry while the steam-containing vapor is recycled to the heat exchanger so as to be utilized as a heating medium for preheating the slurry.