Expanding the Controllable\nRange of the Mean Residence\nTime Ratio of Polydisperse Particles in Multiple-Chamber Fluidized\nBeds: A Coarse-Grained CFD-DEM Study

The residence time of polydisperse particles is crucial\nfor their\nsimultaneous conversion in a fluidized bed. This study focuses on\nregulating the residence time of polydisperse particles to expand\ntheir controllable range by optimizing the reactor design and operation\nstep-by-step. The mean residence time (MRT) ratio of coarse and fine\nparticles (tpc/tpf) increased significantly with increasing\nelutriation pipe width of the multiple-chamber fluidized bed, thus\nenabling the MRT ratio to exceed (dpc/dpf)2; however, the MRT ratio of medium and fine\nparticles (tpm/tpf) is only slightly exceeded dpm/dpf. Moreover, by further optimizing the elutriation\npipe gas velocity, the latter can be adjusted to be exceed (dpm/dpf)1.5. Finally, tpc/tpf and tpm/tpf can be simultaneously adjusted to exceed (dp/dpf)2 by increasing the number of elutriation\npipes. Therefore, present study enables the controllable range of\nthe MRT ratio of polydisperse particles covering from dp/dpf2 to (dp/dpf)2 that meets the required reaction time ratio\nof different particle sizes, which is of great interest for realizing\nthe synchronous conversion of polydisperse particles.