Combined shift and methanation reaction process for the gasification of carbonaceous materials

Claim 1

IN A PROCESS FOR GASFICATION OF CARBONACEOUS MATERIALS TO PRODUCE HIGH METHANE CONTENT GAS INCLUDING A WATER GAS SHIFT REACTION AND A METHANATION REACTION COMPRISING, GASIFICATION CAARBONACEOUS MATERIALS AND GENERATING A HOT SYNTHESIS GAS COMPRISING A MIXTURE OF METHANE HYDROGEN SULFIDE HYDROGEN AND OXIDES OF CARBON, COOLING SAID HOT SYNTHESIS GAS, ADDING STEAM TO SAID COOLED SYNTHESIS GAS WHEN THE HYDROGEN TO CARBON MONOXIDE RATIO OF SAID SYNTHESIS GAS IS LESS THAN 1.0 TO PRODUCE A MIXTURE OF STEAM AND COOLED SYNTHESIS GAS HAVING A STEAM/GAS RATIO OF ABOUT 0.5, INTRODUCING SAID COOLED SYNTHESIS GAS INTO A COMBINED WATER GAS SHIFT AND METHANATION REACTOR INTO CONTACT WITH A CATALYST AT A TEMPERATURE BETWEEN 550*F AND 1050*F AND AT A PRESSURE BETWEEN 500 PSIG AND 2000 PSIG WHEREBY SIMULTANEOUSLU THE HYDROGEN/CARBON MONOXIDE RATIO IS INCREASED BY CARBON MONOXIDE REACTING WITH WATER PRODUCED FRM THE METHANATION REACTION AND METHANATION OF CARBON MONOXIDE AND HYDROGEN IS ACCOMPLISHED RECOVERING FROM SAID REACTOR A METHANE RICH PRODUCT GAS WHICH INCLUDES ABOVE 40% BY VOLUME METHANE SAID METHANE RICH PRODUCT GAS ALSO INCLUDING HYDROGEN SULFIDE, CARBON OXIDES AND OTHER HIGHER HYDROCARBONS SUCH AS ETHANE AND PROPANE, PASSING SAID METHANE RICH PRODUCT GAS THROUGH A WAST HEAT BOILER TO THEREBY COOL AND DRY SAID METHANE RICH PRODUCT GAS AND THEREAFTER, INTRODUCING SAID METHANE RICH GAS INTO A PURIFICATION UNIT FOR REMOVAL OF ACID GAS SUCH AS HYDROGEN SULFIDE AND CARBON DIOXIDE TO PRODUCE A PURIFIED METHANE RICH PRODUCT GAS, AND RECYCLING A PORTION OF SAID COOLED AND DRIED METHANE RICH PRODUCT GAS FOR MIXTURE WITH SAID MIXTURE OF STEAM AND COOLED SYNTHESIS GAS INTRODUCED INTO SAID COMBINED WATER GAS SHIFT AND METHANATION REACTION IN AN AMOUNT WHICH IS NOT MORE THAN THREE VOLUMES FOR EACH ONE VOLUME OF SAID MIXTURE OF STEAM AND COOLED SYNTHESIS GAS.