Effects of coal pretreatment on the products of co-pyrolysis of caking bituminous coal and corn stalks mixed in equal proportion

Abstract

Aim at the problems that the higher heavy tar yield of caking bituminous coal (CBC) pyrolysis and the synergistic effect of its co-pyrolysis with biomass. The changes of gas evolution during the pretreatment process of CBC with oxygen in the atmosphere, and the strengthening effects of the co-pyrolysis of pre-treated coal sample and corn stalk mixed in equal proportion on the pyrolysis products under different carrier gases were studied in this paper. With the increase of the pretreatment temperature, more gas products were obtained than superheated steam from the pretreatment in nitrogen, while yield of gases such as CO2 and CO were much higher with oxygen in the atmosphere and the yield of CO2 increased most. The effects of pretreatment on the destruction of the caking property enhanced as the pretreatment temperature increased with oxygen in the atmosphere, which was beneficial to coal sample pyrolysis reaction, resulting in a 7.01% lower pyrolysis char yield than raw coal char. The equal proportion co-pyrolysis had a synergistic promoting effect on the formation of H2, CO2 and CH4. Compared with other carrier gases, light tar content increased significantly in the mixed carrier gas of CH4+CO2, while the improvement in tar quality should be attributed to the fact that content of phenol oil and anthracene oil increased and the content of asphaltene decreased obviously.