Char burning kinetics from imaging pyrometry: Particle shape effects

Biomass combustion becomes increasingly important in nowadays energy production. One of the major differences between biomass and coal is the particle shape. Therefore the effect of particle shape variations was calculated to determine the effect of spheroidal or cylindrical particle shapes when determining char burning kinetics of pulverized fuel particles from pyrometric measurements. A model frequently used for char kinetics determination was adapted to spheroidal and cylindrical particles under typical combustion conditions. The impact of the particle shape on the energy balance, which is needed for the determination of kinetics parameters, was calculated for typical particle sizes and length to diameter ratios. As the calculations show, the influence of particle shape effects is not negligible for the determination of biomass char burning parameters by pyrometric measurements. The application of the adapted model on measured data shows, that particle shape effects can be resolved by pyrometric techniques. The results presented indicate that a sound analysis of the particle burning rate should include a three-dimensional particle shape measurement.