Insight into multi-level fluidization characteristics of a spout-fluid bed under different gas-solid actions: From monodisperse particles to bidisperse particles

In this study, the effects of gas flow and particle parameters on monodisperse and bidisperse particles were systematically modelled with CFD-DEM from multi-level characteristics: fluidity, periodicity and mixing. With increasing spouting gas velocity, the mixing rate increased and overall flow state changed from spout-fluid to the spout. By comparison, the increase of auxiliary gas velocity showed the opposite variation trend. For bidisperse particles, with increasing light and small particle ratios, the dominant particles of fluidization characteristics changed from coarse and heavy to light and small particles, whose variation regularities were similar to those of single particle size and density. Furthermore, the particle fluidity improved continuously and local particle concentration differences increased. Ultimately, the particle segregation mechanism was proposed by summarizing variation regularities of fluidization characteristics under different gas-solid actions. Besides, compared to particle density, the difference in particle size caused greater stratification, which would reduce the local mass transfer efficiency.