Mixing in a Size Segregated Fluidized Bed: Simulations and Experiments

In contrast to the fluidization of mono-disperse particles, where the minimum fluidization velocity is uniquely defined, more than one characteristic velocities are required to define the fluidization behaviour of bi-disperse particles. Literature suggests that there are two characteristic velocities; however, the conclusion is based on only the measurement of bed pressure drop. The aim of the present study is to investigate the fluidization behaviour of initially segregated bi-disperse particles through laboratory scale visualization experiments and numerical simulations. Particles used in the experiments are of the same density but of two different mean diameters. Bed pressure drop is measured and the physical appearance of the bed is recorded simultaneously. In addition, simulations are performed following the continuum description of the particle phase. Simulations are performed on the open-source software MFIX. Experimental observations show that there are at least three characteristic velocities in a fluidized bed with an initial segregated state. The preliminary continuum-based simulations show good agreement with the experimental observations.