Process for the production of fuel values from coal

A process for the production of methane which comprises in combination the steps of:

• a. forming a slurry of particulate coal in a liquid hydrocarbon solvent predominantly comprising hydrocarbons boiling in the range of from about 300.degree. to about 750.degree. F and generated from the liquefaction of coal in the presence of hydrogen, the weight ratio of the liquid hydrocarbon solvent to coal in the slurry being from about 1:1 to about 3:1;
• b. combining the slurry and a hydrogen containing gas in a liquefaction zone maintained at a temperature from about 700.degree. to about 1000.degree. F and at a pressure up to about 2500 psi for a time sufficient to convert a substantial portion of coal to fluid hydrocarbons and a solid residue of liquefaction;
• c. combining the effluent of fluid hydrocarbons and the solid residue of liquefaction from the liquefaction zone with a synthesis gas in a stripping zone and forming a liquid-solids fraction comprising liquid hydrocarbons having a boiling point above the boiling point of the liquid hydrocarbon solvent and the solid residue of liquefaction and a vapor fraction comprising hydrocarbons, carbon monoxide, carbon dioxide, hydrogen sulfide and hydrogen;
• d. combining, in a gasification zone, the liquid-solids fraction from the stripping zone with steam and oxygen in an amount sufficient to gasify substantially all of the carbon contained in the liquid-solids fraction to generate a synthesis gas comprising hydrogen and the oxides of carbon;
• e. passing at least about 60% of the synthesis gas to the stripping zone to form the vapor fraction;
• f. separating the vapor fraction into the liquid hydrocarbon solvent fraction, a light liquid hydrocarbon fraction and a residual vapor fraction comprising hydrocarbons containing up to about 5 carbon atoms, hydrogen sulfide, carbon dioxide, carbon monoxide and hydrogen;
• g. returning at least a portion of the liquid hydrocarbon solvent fraction to form additional slurry;
• h. converting the balance of the synthesis gas from the gasification zone into a hydrogen rich gas stream;
• i. hydrotreating the light liquid hydrocarbon fraction with at least a portion of the hydrogen rich gas stream to convert bound sulfur to hydrogen sulfide and separating the formed hydrogen sulfide to form a hydrogen sulfide lean light liquid hydrocarbon;
• j. passing another portion of the hydrogen sulfide containing hydrogen rich gas stream as at least part of the hydrogen containing gas to the liquefaction zone;
• k. separating at least a portion of the contained carbon dioxide and hydrogen sulfide from the residual vapor fraction to form a carbon dioxide-hydrogen sulfide lean vapor stream;
• 1. methanating a portion of the carbon dioxide-hydrogen sulfide lean vapor in the presence of a steam supported catalyst containing from about 5 to about 35% by weight of at least one metal of the third period of Group VIII of the Periodic Table on a temperature stabilized, ceramic alumina support in a first methanation zone having an inlet temperature of at least about 900.degree. F and exit temperature up to about 1500.degree. F;
• m. combining, with steam, the effluent of the methanation zone, the balance of the carbon dioxide-hydrogen sulfide lean vapor stream and the hydrogen sulfide lean light liquid hydrocarbon in a catalytic reforming state where, at a temperature from about 1200.degree. to about 1500.degree. F maintained by effluent of the methanation stage, hydrocarbons are reformed to yield an effluent gas stream comprising steam, hydrogen, carbon monoxide, carbon dioxide and methane;
• and
• n. passing the effluent gas stream from the reforming stage to at least one additional methanation stage where the hydrogen and carbon monoxide react to form additional methane.