A meso-scale flow model of gas-liquid-solid mini-fluidized beds with improved macro-scale interaction of wall effects

Abstract

Gas-liquid-solid mini-fluidized beds known for high efficiency with controllable mass and heat transfer characteristics, have good application prospects in fields such as multiphase reaction process enhancement and intrinsic kinetic detection. For three-phase mini-flow systems, the bed wall has a significant impact on spatiotemporal distribution of multi-phase flow structure, which influence the motion state of dispersed phase, make predicted phase holdup and residence time deviate from experimental values. However, current research on the quantitative impact of bed walls on flow structures is still limited, which hinders the optimization design and industrial application of such reactors. In this work, a meso-scale flow model of gas-liquid-solid mini-fluidized beds considering macro-scale effects between bed wall and flow is developed based on the principle of meso-scale science and introducing semi-theoretical formulas that take the effects of bed walls on particles and bubbles into account. The calculated values of this model are in good agreement with experimental data, where prediction of phase holdup fits well with experimental results, the deviation of bubble size and terminal velocity are within 10%. Compared to existing models, this model demonstrates a higher level of accuracy in predicting the flow patterns of mini-fluidized beds, particularly those with pronounced wall effect. This research has laid a foundation for the design, scale-up and industrial application of mini-fluidized bed reactors.