Evolution of Limestone Particle Size Distribution in an Air-Jet Attrition Apparatus

Attrition is very important in fluidized-bed reactors, especially for limestone-based sorbents used to capture SO2 and CO2. The initial size distribution of the sorbent particles is commonly used to predict the rate of attrition, but the distribution changes during the process. Limestone samples of narrow particle size distributions (PSDs) were tested in an ASTM air-jet attrition apparatus, and the evolution of the PSDs was investigated. The entropies of information on log-normal functions, a measure of the disorder of particles being entrained into the jets, remained almost unchanged during the attrition process. This indicates that particles of greater entropy generally experience attrition at a greater rate in an air-jet apparatus, except for particles which are too large to be mobilized or too small to stay in the bed.