There exists calcium sulphide in char derived from partial coal gasification. Sulphur dioxide would emit due to the oxidation-reduction reactions while the char is combusted in circulating fluidized bed combustor ( CFBC). 煤经过部分气化后的半焦中含有CaS。当半焦在循环流化床燃烧室(CFBC)中燃烧时,其中的CaS发生氧化-还原反应而释放出SO2。