Steam gasification of coal in a circulating fluidized bed system

Steam gasification of coal was carried out in a circulating dual bubbling fluidized bed reactor (CDBFB), in which a gasifier and a combustor were physically separated. Two types of bed materials were used; one was the silica sand which is inert for the gasification, and the other was porous alumina which can capture tar instantaneously. Using alumina as bed material, the gas yield in the gasifier was larger than that of the silica sand case. This was because almost all the tar was evacuated from the gasifier in the silica sand case while the tar was mostly captured with the alumina and then reformed with steam. System simulation was conducted to evaluate the efficiency of CDBFB. The experimental results combined with the system simulation demonstrated that the plausible condition for thermally stand-alone CDBFB system can be clarified. This is an abstract of a paper presented at the 8th World Congress of Chemical Engineering (Montreal, Quebec, Canada 8/23-27/2009).