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Abstract

A process for gasification of cellulosic materials in a single gasification vessel wherein the cellulosic materials are introduced directly into a single back-mixed fluidized bed of high heat capacity inert solids. The fluidized bed is maintained at temperatures of about 1200.degree. to about 1600.degree. F., pressures of up to about 500 psig devolatilizing the cellulosic materials. A substantial portion of the heavier hydrocarbons produced by devolatilization of the cellulosic materials is reformed within the gasification vessel and a substantial portion of the devolatilized cellulosic materials is gasified by reaction with hydrogen and steam within the fluidized bed. Cellulosic materials residue is combusted in an oxygen-rich atmosphere in the lower portion of the fluidized bed to principally form heat and cellulosic materials ash. The highly back-mixed fluidized bed results in temperature variation along the height of the bed, including the combustion zone, of less than 100.degree. F. and preferably less than about 90.degree. F. Introduction of cellulosic materials feed to the fluidized bed is vertically adjustable and maintained at a position where the combustion consumes principally cellulosic materials residue. Formed gases, vapor and biomass ash are removed from the top of the gasification vessel in the gas stream. The process provides high throughput, efficient production of low and medium Btu fuel gas. The medium Btu fuel gas may be readily upgraded to high Btu SNG. At least half of the methane required for SNG is produced in the gasification vessel.

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First Claim