LAUSR

The carbon conversion of fluidized bed gasification has been restricted by the entrainment of semichars with high carbon content. Recently, the disposal of the semichar has become an intractable problem. In this study, the ash fusion properties and mineral transformation behavior at high temperature of the semichar from an industrial circulating fluidized bed (CFB) gasifier were investigated under oxidizing condition. In comparison to the raw coal, the total base content increases from 27.92 to 29.45 after partial gasification, which results in a decrease in the ash fusion temperatures (AFTs) of the semichar. Kaolinite decomposed into quartz, alumina, and water via dihydroxylation reaction and anhydrite was transformed into oldhamite in the CFB gasifier. As the particle size increases, the AFTs of the semichar decrease first and then remain almost unchanged, which coincides with the variations in acid-to-base ratio; however, the disparity is relatively small, which favors its melting utilization. Quartz, ...