Process for the catalytic gasification of coal

In a process for the production of synthetic natural gas by the conversion of a solid carbonaceous feed, in the presence of a carbon-alkali catalyst, by contact of said feed in a gasification zone containing a fluidized bed of char, with steam and a mixture of hydrogen and carbon monoxide gases added to said zone to suppress reactions which compete with the formation of equimolar concentrations of methane and carbon dioxide from a stoichiometric equivalent of carbon and water, the improvement comprising

• continuously supplying to a main gasification zone a solid carbonaceous feed, a carbon-alkali catalyst, steam and a mixture of hydrogen and carbon monoxide gases, gasifying said solids carbonaceous feed at temperatures ranging from about 1000.degree. to about 1600.degree. F and pressures ranging from about 100 psia to about 1500 psia by injecting gases upwardly at superficial linear velocities ranging from about 0.5 to about 3 ft/sec. sufficient to devolatilize and react with the solid carbonaceous feed to form char and gaseous effluent, maintain the char in fluidized state and entrain within the gaseous effluent from about 5 to about 30 percent of the fine solid char, based on the weight of total feed to said main gasification zone,
• separating the entrained char from the gaseous effluent, and feeding said char into a secondary gasification zone, recovering from the gaseous effluent a synthetic natural gas consisting essentially of methane and a synthesis gas comprising hydrogen and carbon monoxide,
• removing from said fluidized bed of char of said main gasification zone from about 5 to about 30 percent additional char, based on the weight of total feed,
• feeding said char via dense phase transfer as an admixture of char and carbon-alkali catalyst into said secondary gasification zone,
• continuously supplying to said secondary gasification zone steam and a mixture of hydrogen and carbon monoxide gases, gasifying said char at temperatures ranging from about 1000.degree. to about 1600.degree. F and pressures ranging from about 100 psia to about 1500 psia by injecting gases upwardly at superficial linear velocities below those employed in said main gasification zone and ranging from about 0.05 to about 1 ft/sec. sufficient to maintain the char in fluidized state, but insufficient to entrain any significant amount of the char,
• withdrawing a gaseous effluent from said secondary gasification zone and recovering synthetic natural gas consisting essentially of methane and a synthesis gas comprising hydrogen and carbon monoxide, from said gaseous effluent, recycling the recovered synthesis gases as the hydrogen and carbon monoxide gases supplied to the main and secondary gasification zones,
• whereby more efficient utilization of the feed carbon is achieved than can be obtained by the sole use of the main reaction zone, even when said main reaction zone is operated at the same or conditions more favorable for gasification of the feed carbon.