Mesoscale-Structure-Dependent EMMS Drag Model for an SCW Fluidized Bed: Formulation of Conservation Equations Based on Structures in Subphases

Supercritical water (SCW) fluidized bed reactors release no pollutants in the gasification process of converting biomass into fuel. In this work, a mesoscale-structure-dependent (MSD) energy minimization multiscale system (EMMS) drag model for SCW fluidized beds is proposed. Experimental results and empirical correlations are applied to validate the voidage distribution and bubble hydrodynamics calculated by the MSD-EMMS model. Besides, this study presents a comparison of the properties of computed bubbles between the Gidaspow model, EMMS/bubbling model, and MSD-EMMS model. Bubble properties predicted by the MSD-EMMS model agree better with experimental results and empirical correlations than other drag models. The research work can serve as guidance for the optimization of SCW gasification technology.