Expanding the Controllable Range of the Mean Residence Time Ratio of Polydisperse Particles in Multiple-Chamber Fluidized Beds: A Coarse-Grained CFD-DEM Study

Abstract

The residence time of polydisperse particles is crucial for their simultaneous conversion in a fluidized bed. This study focuses on regulating the residence time of polydisperse particles to expand their controllable range by optimizing the reactor design and operation step-by-step. The mean residence time (MRT) ratio of coarse and fine particles (tcp/tfp$t_p^c/t_p^f$$t_p^c/t_p^f$) increased significantly with increasing elutriation pipe width of the multiple-chamber fluidized bed, thus enabling the MRT ratio to exceed (dcp/dfp)2${(d_p^c/d_p^f)}^2$${(d_p^c/d_p^f)}^2$; however, the MRT ratio of medium and fine particles (tmp/tfp$t_p^m/t_p^f$$t_p^m/t_p^f$) is only slightly exceeded dmp/dfp$d_p^m/d_p^f$$d_p^m/d_p^f$. Moreover, by further optimizing the elutriation pipe gas velocity, the latter can be adjusted to be exceed (dmp/dfp)1.5${(d_p^m/d_p^f)}^{1.5}$${(d_p^m/d_p^f)}^{1.5}$. Finally, tcp/tfp$t_p^c/t_p^f$$t_p^c/t_p^f$ and tmp/tfp$t_p^m/t_p^f$$t_p^m/t_p^f$ can be simultaneously adjusted to exceed (dp/dfp)2${(d_p/d_p^f)}^2$${(d_p/d_p^f)}^2$ by increasing the number of elutriation pipes. Therefore, present study enables the controllable range of the MRT ratio of polydisperse particles covering from dp/dfp2${d_p/d_p^f}^2$${d_p/d_p^f}^2$ to (dp/dfp)2${(d_p/d_p^f)}^2$${(d_p/d_p^f)}^2$ that meets the required reaction time ratio of different particle sizes, which is of great interest for realizing the synchronous conversion of polydisperse particles.