CFD modeling of gas–solid flow in a two-stage jetting fluidized bed with an overflow standpipe

The two-fluid model–kinetic theory of granular flow (TFM–KTGF) model and the sub-grid-scale (SGS) model are used to conduct a three-dimensional numerical simulation study on the hydrodynamic characteristics of a two-stage fluidized bed with an integrated overflow pipe. Using various drag models, the gas–solid flows, bed expansions, pressure drop distributions, and equilibrium conditions in the two-stage bed are compared, and the conditions for the formation of a stable overflow in the two-stage bed are thoroughly investigated. In addition, during the simulation of the secondary distribution in the bed, the porous media model simulates the momentum loss caused by the redistribution plate to avoid the direct simulation of the redistribution plate, which requires extensive grid division work and calculation costs. This work can provide technical direction for the industrialization of one-step coal to multistage fluidized bed natural gas technology.