A Study of CFD Modeling on Variation of Solid Fraction in a Batch Fluidized Bed

Abstract

Two-dimensional gas–solid batch fluidized bed is simulated in transient conditions using the Eulerian–Eulerian two-fluid model. The grid independent test has been carried out for three different mesh sizes, and the courant number in the range of 0.2–0.4 has been used. The simulated results are compared with the experimental observations. The study is conducted for different sizes of Geldart group D solid particles, different bed heights, and different air velocities in the bubbling regime of fluidization. Two different models, such as the Gidaspow model and the Wen-Yu drag model, have been tested to model the drag at the phase interaction for Geldart group D solid particles. On comparison with experimental results the Gidaspow drag model matches well with experimental results and hence is used for simulation. At the initial stage of fluidization (where a fountain like phenomena was observed), the bed behaves like a spouting bed, and then the bubbling bed behavior follows. These predictions are compared with the experimentally observed bed height of particles of different sizes and air velocities. It is observed that the Gidaspow drag model predictions are in good accordance with the experimental results for particles of different sizes, both in the initial stage and in the bubbling regime of fluidization.