Study on the formation and dissipation mechanism of gas phase products during rapid pyrolysis of superfine pulverized coal in entrained flow reactor

摘要

As the initial step in coal combustion and gasification, pyrolysis plays an important role in chemical reactions. The influencing mechanism of superfine particle on gas phase products during rapid pyrolysis remains problematic. In this paper, the formation and dissipation mechanism of the gas phase products especially CO, light hydrocarbons and NOx precursors of superfine pulverized coal pyrolyzed in an entrained flow reactor is focused. Pyrolysis experiments are taken out in Ar and N-2 respectively. The influence of particle size, coal rank, pyrolysis atmosphere and the final pyrolysis temperature on the formation and dissipation are analyzed. In addition, pore structures of raw coal and chars are also characterized by synchrotron radiation facility to better reveal the pyrolysis mechanism. Our results indicate that as the particle size decreases, the content of CO, light hydrocarbons and NOx precursors all show a trend of first increase and then decrease. Lower rank coal has larger release concentration of gas phase products. Additionally, with the increment of the final pyrolysis temperature, there is a decrease trend of light hydrocarbons and NOx precursors but an increase trend of CO. The fractal dimension (D-SAXS) increases with the increase of the final pyrolysis temperature. (C) 2019 Elsevier Ltd. All rights reserved.