Structure Characterization and CO2 Gasification Kinetics of Tri-High Coal-Chars Derived from High-Temperature Pyrolysis

The pore structures and chemical composition features of two kinds of tri-high coal and their char samples prepared at a 750 °C temperature were analyzed. The results showed that the pyrolysis process has a great influence on the pore structure and the chemical composition of the char, and the influence is highly related to the coal ranks. The gasification kinetics of the two chars in pure CO2 atmosphere was also studied. The results indicated that the classical random pore model (RPM) cannot be used to explain the gasification kinetics throughout the char gasification. A modified RPM, considering the inhibitory effect of ash on the gasification kinetics, was adopted to estimate the kinetics, and the kinetic constants and the corresponding activation energies were calculated. It was observed that it was necessary to include the effect of ash on the variations of char structures during the char gasification to get an accurate description of reaction rate versus carbon conversion throughout the gasification of the tri-high coal chars.