Sulfur release during the devolatilization of large coal particles

Abstract

Experimental data are reported on sulfur release rates during the flash pyrolysis of coal particles sized up to 2 mm, at heating rates and temperatures found typically in fluidized bed reactors. Predicted sulfur yields are also reported for pyrolysis conditions studied using an existing model for devolatilization of large coal particles, coupled with kinetics from an earlier study. The predictions of the experimental data were found to be sensitive to the value of the thermal diffusion coefficient used in the model, with each coal and pyrolysis temperature requiring a specific value in order to accurately predict the experimental results. The rate of heat transfer is also shown to be an important rate-controlling mechanism and the transition from reaction-controlled to heat-transfer-controlled pyrolysis is determined as a function of thermal diffusivity, particle size and sulfur release kinetics.