Method for gasifying cellulosic material

摘要

Method for gasifying cellulosic material comprises feeding cellulosic material into the uphill end of an inclined rotary kiln; transporting a bed of cellulosic material through the kiln and continuously tumbling the bed; withdrawing fuel gas from the uphill end of the kiln so it flows countercurrent to the bed and removes moisture in the drying zone and thermally decompose volatiles in the devolatilization zone; admitting air overbed in the devolatilization zone and only underbed in the gasifying zone; and controlling the mass flow rate of air into the devolatilization and gasifying zones respectively as predetermined percentages of that rate of which is stoichiometric to the cellulosic material fed into the kiln to thereby limit temperature rise, prevent agglomeration and minimize entrainment of solid particles. Air is admitted into the gasifying zone underbed through axially spaced sets of shell ports, and the mass flow rates of air therethrough are regulated as a function of the percentages of carbon in the bed in the portions of the kiln in which the sets of shell ports are disposed to thereby efficiently utilize the air in converting carbon into CO2, assure that a high percentage of CO2 is converted into chemical energy in the form of CO, and permit shortening of the kiln.