A quasi-three-phase approach for simulating gas-solid fluidized bed under different flow patterns

Abstract

The gas-solid fluidized bed is a complex multiscale system with diverse mesoscale structures such as bubbles and particle clusters. The Euler-Euler two-fluid model is one of the most popular methods in simulating this kind of system. However, when using coarse grids, the mesoscale structures involved can hardly be characterized. In this study, a new quasi-three-phase method was proposed to properly account for the mesoscale structures by using three phases (bubble phase/solid phase/emulsion phase) to represent the gas-solid fluidized bed, and comparative simulations were performed under different gas velocities. It was found that the simulation could reasonably predict the flow changes from bubbling fluidization to turbulent fluidization. The predicted gas velocity at the flow pattern transition is close to that calculated by the empirical equation concerning the bed pressure fluctuation, and the predicted solids fraction distribution fits well with the experimental data in the literature.