Regulation characteristics and law of residence time distribution of polydisperse particles in numbered-up multiple-chamber fluidized bed reactors

How to simultaneously regulate the residence time of polydisperse particles and completely inhibit particle backmixing remains a challenge of fluidization technology. In this study, it is shown that adding elutriation pipes into multiple-chamber fluidized beds to strengthen particle elutriation and entrainment is an effective measure. Coarse-grained CFD-DEM simulation results show that the addition of the elutriation pipe can completely inhibit the particle back-mixing between adjacent chambers, and the mean residence time (MRT) ratio of coarse and fine particles can be regulated to be larger than their diameter ratio. Furthermore, a study on the numbered-up multiple-chamber fluidized beds find that (i) the MRT ratio of coarse and fine particles can be larger than the 1.5th power of their diameter ratio with full suppression of particle back-mixing between adjacent chambers; (ii) the MRT of each size of particles is a linear function of chamber number, whereas the MRT ratio approaches an asymptotic value. The results are of guiding significance for improving the overall conversion rate of polydisperse particles.