3D Simulations of Voidage Distribution in SCW Fluidized Beds Using the EMMS Model

Supercritical water fluidized beds (SCWFBs) are advanced reactors for biomass gasification. In this work, three-dimensional (3D) simulations are carried out using the energy minimization multiscale (EMMS) model developed for SCWFBs. The voidage distribution obtained by the EMMS model is validated by time-averaged experimental results. The effects of superficial inlet velocity (U_f), temperature (T), pressure (P), and particle size (d_p) on the radial and axial voidage, probability density of voidage, and bed expansion are studied. The voidage distribution curves at different radial positions are parabolic due to “core-annular flow” structures. The probability density decreases with increasing voidage of SCWFBs. Bed expansion height is affected by the excess fluid caused by the change in physical properties. The simulation results can provide theoretical guidance for the scaled-up design of SCWFBs.