Numerical analysis of fluid flow and particle entrainment in a novel tapered rotating fluidized bed

Article. Published in Chemical Engineering Science. — 2014. — 116 — P. 725-733A rotating fluidized bed is a promising fluidization technique for handling of fine particles, classified into the Geldart׳s group-C. However, significant particle entrainment has been a major hurdle for its practical use. We here proposed a novel tapered rotating fluidized bed to reduce the particle entrainment. The fluidized bed vessel of the tapered rotating fluidized bed has the geometry of a cylinder with two frustum ends. The main purpose of this paper is to evaluate a performance of the tapered rotating fluidized bed in reducing the particle entrainment. A computer simulation using a computational fluid dynamics and discrete phase model was conducted to numerically analyze how the fluid flow and particle motion ejected to the freeboard are changed when the vessel geometry is altered. The simulation results revealed that by modifying the geometry of the vessel to the tapered geometry the fluid velocity in the radial direction toward the exit is significantly decreased, while the fluid velocity in the tangential direction is increased. The simulation results also revealed that the maximum particle size of the entrained particles is reduced with an increase in the taper angle: the particle entrainment can be effectively reduced by merely changing the vessel geometry to the tapered geometry. The experimental results showed that amount of entrained particles was significantly decreased when the tapered vessel was used, confirming that the proposed tapered rotating fluidized bed is effective to reduce the particle entrainment.