(260b) Theoretical Analysis of Fluidization and Mixing Behaviors in a Rotating Fluidized Bed

Recently, a rotating fluidized bed (RFB) has attracted special interest, since it overcomes the limitations of conventional fluidized bed: it can prevent the growth of large bubbles at any high gas velocities by controlling the vessel rotational speed, and it can fluidized very fine particles such as Geldart group C particles and even nano particles. However, the particle fluidization behaviors have not been well analyzed yet, since these are very complicated. In this study, particle fluidization and mixing behaviors in a RFB were theoretically analyzed. First of all, numerical modeling of particle fluidization behaviors in a RFB was conducted by using a coupling model of discrete element method (DEM) and computational fluid dynamics (CFD). The calculated particle fluidization behaviors showed good agreement with the actual fluidization behavior, which were observed by a high-speed video camera. The estimated minimum fluidization velocity (U_mf) and the bed pressure drop at fluidization condition (ΔP_f) by our proposed model and other available analytical models in literatures were also compared with the experimental results. It was found that our proposed model based on the DEM-CFD coupling model could predict the U_mf and ΔP_f with a high accuracy because our model precisely considered the local downward gravitational effect, while the other analytical models overpredicted the ΔP_f due to ignoring the gravitational effect. In addition, particle mixing behaviors were also theoretically and experimentally analyzed by using the degree of mixing. Accordingly, the experimental results showed good agreement with the calculated ones. Effects of the operating parameters such as gas velocity and vessel rotational speed on particle mixing behaviors were also analyzed.