Effects of particle shape and size distribution on the overall fluid‐solid reaction rates of particle assemblages

Abstract

The effect of particle size distribution on fluid‐solid reaction kinetics was evaluated for particle assemblages made up of particles of different shapes. The most commonly used size distributions, the Gate‐Gaudin‐Schuhmann (GGS) distribution, the Rosin‐Rammler‐Bennett (RRB) distribution, and the Gamma distribution, were chosen. The effects of the following factors were simulated: the shrinking unreacted‐core reaction mechanism, rate‐controlled either by interface reaction or pore diffusion; the three basic particle shapes; and the coefficient of variation (CV) of the size distributions. It was shown in this work that the effect of size distribution can be represented by the CV value regardless of the type of distribution, which makes the analysis convenient. The results show that the reaction kinetics progressively deviates from those of uniform particles as the CV value increases and the particle shape deviates from spherical toward flat. Additionally, pore diffusion‐controlled kinetics tends to deviate more than interface reaction‐controlled kinetics under the same CV value. For spherical particles under the two rate‐controlling mechanisms, the effect of particle distribution for GGS on the kinetics is insignificant for CV values up to 0.5. For the RRB and Gamma distributions, the effect is tolerable up to the CV value of 0.75.