Gasification of solid carbonaceous fuel

Claim 1

IN A CYCLIC PROCESS FOR THE PRODUCTION OF FUEL GAS FROM A SOLID CARBONACEOUS FUEL WHEREIN A GASEOUS REACTANT COMPRISING STEAM IS REACTED WITH SAID FUEL AT A GASIFICATION REACTION TEMPERATURE WITHIN THE RANGE OF FROM ABOUT 1500* F. TO ABOUT 2000* F. TO PRODUCE A FUEL GAS COMPRISING CARBON MONOXIDE AND HYDROGEN AS PRINCIPAL CONSTITUENTS, THE FLOW OF REACTANT GAS IS PERIODICALLY INTERRUPTED AND HEAT SUPPLIED TO SAID BED, THE IMPROVEMENT WHICH COMPRISES PASSING SAID GASEOUS REACTANT DOWNWARDLY THROUGH A BED OF SAID SOLID FUEL IN A GAS GENERATION ZONE DURING THE PERIOD OF GAS GENERATION, THEREAFTER DISCONTINUING THE FLOW OF SAID REACTANT GAS THROUGH SAID BED, SUPPLYING HEAT TO SAID BED BY INTRODUCING A STREAM OF HOT FLUE GAS AT A TEMPERATURE ABOVE SAID REACTION TEMPERATURE INTO THE LOWER PROTION OF SAID BED AND PASSING THE FLUE GAS UPWARDLY THERETHROUGH AT A RATE SUFFICIENT TO MAINTAIN THE SOLID PARTICLES IN SAID BED IN A STATE OF DENSE PHASE FLUIDIZTION WHEREBY THE LARGER PARTICLES IN SAID BED GRAVITATE TO THE LOWER PORTION OF SAID BED, REMOVING THE LARGER PARTICLES FROM THE LOWER PORTION OF SAID BED, INTRODUCING FRESH FUEL INTO SAID BED, BURNING SAID PARTICLES REMOVED FROM THE LOWER PORTION OF SAID BED WITH AIR TO SUPPLY SAID STREAM OF HOT FUEL GAS, AND THEREAFTER DISCONTINUING THE FLOW OF HOT FLUE GAS THROUGH SAID BED WHEN SAID BED IS AT A TEMPERATURE IN THE RANGE AFORESAID AND AGAIN PASSING SAID REACTANT GAS DOWNWARDLY THERETHROUGH FOR THE GENERATION OF FUEL GAS.