Kinetics of coal pyrolysis and devolatilization

Research continued on coal pyrolysis and devolatilization. The effects of reaction process on the transient temperature history of a particle have been examined. The reaction process is found to significantly reduce the temperature gradient across a burning particle relative to a nonreactive particle. The pyrolysis process, on the other hand, does not severely affect the temperature history of a heating particle for the kinetic parameters employed. Devolatilization experiments have been performed on various size cuts on an HVA Bituminous coal in entrained flow and heated grid reactors. Weight loss measurements were made in the entrained flow reactor (EFR) and tar yields and molecular weight distributions were measured for the heated grid reactor (HGR) experiments. The results imply the initial phase of the devolatilization of the HVA Bituminous coal is heat transfer controlled because the rate of tar information and evolution is heat transfer controlled. The invariance in EFR ultimate weight loss and low pressure tar yields and characteristics with change in particle size can be explained by morphological considerations of the parent coal particles. The non-symmetric, irregular shapes of the coal particles result in an intraparticle mass distribution much nearer an interphase surface area than that of an equivalent sphere or cube. 5 refs., 37 figs., 9 tabs