Effect of particle size on flow behavior in fluidized beds

Abstract

The fluidization behaviour depends on particle properties such as particle size, sphericity, density and the properties of the fluidizing agent. In this study, the effects of different particle sizes on fluidization behaviour were investigated. Experiments were done by mixing sand particles of mean diameter 293µm (small particle) and 750 µm (large particle). The experiment with 20% small particles and 80% large particles gave a reduction in minimum fluidization velocity of 60.8% compared to the minimum fluidization velocity with only large particles. CPFD simulations were performed using the commercial software barracuda®. There is a good agreement between the results from the experiments and the simulations. The minimum fluidization velocity is also calculated using different theoretical equations based on the average particle size for the mixture. The obtained experimental results were compared with the minimum fluidization velocity calculated using different equations available in the literature. There are significant differences in minimum fluidization velocities obtained from the different empirical equations. The pressure drop profiles for large and small particles follow the trends presented in the literature. The experimental minimum fluidization velocities were found to be 0.46 and 0.092 m/s for the large and small particles respectively.