By applying a bubbling fluidized bed reactor

the effect of coal ash on migration and transformation characteristics of sulfur during coal pyrolysis was experimentally studied. The results show that

during the pyrolysis of Xiaolongtan coal

the presence of coal ash inhibited the volatilization of H_2S and COS

which was mainly due to the sulfur fixation reaction of Fe_2O_3 in coal ash with H_2 and COS in gas. The coal ash obviously enhanced the SO_2 release at high temperatures(≥700 ℃)

and the possible reason was that large amount of SO_2 was formed through the reactions between the recuding gas and CaSO_4 in the ash. The coal ash promoted the CH_3SH decomposition at low temperatures(≤700 ℃)

thus reduced the CH_3SH release. The addition of coal ash decreased the formation of organic sulfur through inhibiting the interaction between H_2S and semi coke

and finally reduced the organic sulfur content in the semi coke.