The processes of coal pyrolysis and secondary reactions were separated by using two-stage fixed bed reactor to simulate the product flow and the interactions among reaction particles for coal pyrolysis in the traditional indirect heating reactor and indirect heating reactor with internals

and to investigate the effects of different temperature char on the distribution and quality of pyrolysis products of Xianfeng lignite. The results showed that the drastic secondary reactions occurred when tar flowed through the 500-900℃ char layer

the yield of pyrolysis gas increased

the tar yield and atomic H/C ratio were lower than those of blank control experiment

and the quality of oil decreased. Under the action of 100-400℃ char layer

the slight secondary reaction of the tar occurred

the yield of pyrolysis gas increased slightly

the tar yield had a little decrease

the atomic H/C ratio was higher than that of blank control

and the oil quality increased. The results verified the conclusion that the tar with indirect heating reactor with internals produced higher yield and better quality.