To investigate the effects of different reaction atmospheres on thermal migration and release characteristics of chlorine in high-chlorine coal

thermal conversion processes(i.e. pyrolysis

gasification and combustion) of Wanxiang coal from Hami Xinjiang were experimentally studied on a fixed-bed reactor in different reaction atmospheres. The result indicates that

the release rate of chlorine is accelerated with the increasing temperature in three thermal conversion processes

and the rapid release of chlorine is located at 800～1 000 ℃. At 200 ℃

the release rate of chlorine in air atmosphere is 12.72%

while that in N_2 and CO_2 atmospheres is about 1%. When the temperature is increased to 1 000 ℃

the release rate of chlorine in air atmosphere reaches 99.4%

while that in N_2 atmosphere is only 38.3%

this is probably because the presence of organic carbon in the pyrolysis coke prevents the escape of NaCl crystals at high temperature

thereby reducing the release amount of chlorine during the pyrolysis process. In N_2 and CO_2 atmospheres

the chlorine mainly exists in organic forms in the pyrolysis and gasification coke

while in air atmosphere

the chlorine mainly exists in inorganic forms in the coke. When all the organic species in the coal are combusted

almost all the chlorine in the ash appear in the form of NaCl crystal.