Pyrolysis time correlation for a single biomass particle exposed to high temperatures

Pyrolysis of a single biomass particle is numerically studied using a one-dimensional model which assumes virgin material decomposes through three parallel reactions to light gases, tar and char. In contrast to most past studies in which the heat of pyrolysis is assumed to be endothermic throughout the process, this paper presents a new method of calculating the pyrolysis heat in the simulation of a pyrolyzing particle by accounting for the exothermicity of char formation and the endothermicity of volatiles generation in accordance with the correlations proposed in the literature. The improved model has been validated against various experimental data obtained at high temperatures; and excellent agreement has been obtained between the model predictions and the experiments. The model is further employed to examine the effects of particle size and initial density on conversion time and final char density of a biomass particle at high heating environments. The results enabled us to derive correlations for estimation of the pyrolysis time and the final char density as functions of particle size and density at reactor temperatures of 1450 K and 1650 K, which are expected to be useful design tools for process engineers when designing industrial plants operating at high temperatures.