Solids Mixing Intensification in Tapered Fluidized Beds with an Inlet Jet: Experimental Validation and CFD Simulation

Abstract This article investigates the intensification of solids mixing in tapered fluidized beds with an inlet jet and varying apex angles (2.86, 5.71, and 8.53 degrees). The investigation applied a particle segregation number (PSN) and a multi-fluid modeling (MFM) approach. The solid mixtures considered comprise particles with a density of 2500 kg/m³ and diameters of 240 and 510 µm. To validate simulation results, a comparison was made with experimental data from a small-sized tapered bed without an inlet jet. In addition, the simulation outcomes were validated against experimental findings reported by Huilin et al. (2003), incorporating an inlet jet. These validations establish a satisfactory agreement between simulation results and experimental observations. The study reveals that the solids mixing process in a columnar fluidized bed closely resembles that in a tapered fluidized bed with an apex angle of 2.86 degrees. As the apex angle increases, the equilibrium mixing value also rises. Furthermore, the study delves into the effects of inlet jet velocity and nozzle diameter on the solids mixing process. The obtained results clearly indicate that higher inlet jet velocities and larger nozzle diameters lead to increased equilibrium mixing index values. Notably, inlet jet velocities of 0.7 and 0.8 m/s manifest a solids mixing process characterized by three stages: rapid mixing, slow mixing, and equilibrium mixing. In contrast, larger inlet jet velocities only involve rapid and equilibrium mixing stages. Moreover, it was examined how the initial arrangement of solid particles influences the mixing index, prompting appropriate adjustments. In sum, this research sheds light on the factors impacting solids mixing in tapered fluidized beds, offering valuable insights into the solids mixing process in tapered fluidized beds.