Sulfur release from coal in fluidized-bed reactor through pyrolysis and partial oxidation with low concentration of oxygen

Yima (YM) and Datong (DT) raw coal were pyrolyzed in a fluidized bed reactor under 0.6%O2–N2, 1.1%O2–N2 and 2.1%O2–N2 atmosphere, and a flue gas analyzer was used to check the SO2 in pyrolysis gas. The product of sulfur removal and char yield is suggested to measure the efficiency of sulfur removal. For YM coal, sulfur removal generally has increasing trend with the increase of oxygen concentration in atmosphere. The char yield of YM coal has no remarkable decrease when the oxygen content is lower than 1.1%. However, in 2.1%O2–N2 less char yield is obtained. For DT coal more sulfur is removed in 0.6%O2–N2 than in N2, and at the same temperature more SO2 is released with increasing oxygen content. It is suggested that the atmospheres used selectively break the C–S bonds other than C–C bonds. Pyrolysis of coal in fluidized-bed reactor under low concentration of oxygen atmosphere is a promising method to greatly remove sulfur, and not remarkably decrease the char yield.