Comparative analysis of particle density effects on initial fluidization in gas-solid fluidized beds

Gas-solids fluidization technology is commonly used in chemical engineering processes involving high-density particles, often encountering poor defluidization phenomena. However, there is limited research examining the applicability of flow characteristics and empirical correlations established for low-density, easily fluidizable particles in guiding the flow behavior of high-density particles. This knowledge gap poses significant challenges for designing and operating fluidized beds in relevant processes involving high-density particles. This study comprehensively evaluates the effect of particle density on hydrodynamics during the initial fluidization stage using experimental, empirical correlations and simulation methods. Results of preliminary experiments indicate that empirical correlations for predicting Umf may exhibit significant errors of high-density particles. However, the experiments face challenges in eliminating the influence of different particle size distribution. In contrast, the simulation results present a high consistency with the experiments after sensitivity analysis. Further simulation results illustrate that empirical correlations for Umf may only yield relatively accurate predictions within the narrow density range. As the particle density increases, the predicted errors tend to increase. During the initial fluidization stage, three distinct fluidization stages can be observed, as revealed by both experiments and simulations. These stages can be attributed to the practical particle size distribution. Furthermore, it is noted that as the particle density increases, the fluidization performance tends to deteriorate. This study endeavors to advance the understanding of the effect of particle density on hydrodynamics during the initial fluidization stage. Nonetheless, more studies are still needed to enhance and deepen the current knowledge of the fluidization of high-density particles.