Pyrolysis characteristics and pyrolysis product composition of bituminous coal under weak oxidizing atmosphere

In order to improve the light tar and gas yield, the yield distribution and composition characteristics of pyrolysis products of bituminous coal from Shaanxi Hongliulin in the nitrogen atmosphere and weak oxygen atmosphere were studied in a fixed bed reactor. The results showed that the yield of char and tar were reduced under the weak oxygen atmosphere, and the yield of CO and CO₂ increased significantly, leading to the increase of total gas yield. Due to the oxidation combustion reaction, the yield of H₂, CH₄ and C₂-C₃ gradually decreased with the increase of oxygen content in the pyrolysis atmosphere, and the water content changed little during the process. The decomposition temperature of pyrolysis tar in the micro oxygen atmosphere was more than that of N₂ atmosphere. When the pyrolysis temperature was 800℃ and ER=0.14, the tar yield was 6.22%, the H₂ yield was 14.01 mg/L, and the tar and H₂ product yield reached the best value. The relative content of aliphatic hydrocarbons, phenols and benzene series in pyrolysis tar was lower, and the relative content of PAHs was higher than that of pyrolysis tar in N₂. The graphitization degree of char in the weak oxygen atmosphere was lower than that of pyrolysis char in N₂, and the gasification reactivity of char in micro oxygen atmosphere was greater than that in N₂. The results provide basic data for the preparation of high-value fuel by pyrolysis of bituminous coal in fixed bed.