HYDRODYNAMIC CHARACTERISTICS OF LIQUID-SOLID AND GAS-LIQUID-SOLID FLUIDIZED BEDS

The hydrodynamic characteristics, specifically, bed expansion, pressure drop and gas hold-up of the gas-liquid-solid fluidized bed systems involving cocurrent and inverse gas-liquid-solid fluidized beds, constrained inverse gas-liquid-solid fluidized beds, cocurrent and inverse gas-liquid-solid semifluidized beds, and cocurrent gas-liquid-solid fluidized beds containing binary mixtures of mixed-size and/or density particles were studied.; For the inverse gas-liquid-solid fluidized beds empirical correlations are presented for the parameters of bed expansion and gas hold-up. For the constrained inverse gas-liquid-solid fluidized beds, Wallis' drift flux model was modified to account for the gas hold-up. Bed voidage in the cocurrent gas-liquid-solid fluidized beds was correlated based on the generalized wake model while the gas hold-up in the same system was correlated based on the modified Nicklin theory for the dispersed bubble flow regime and slug flow regime.; The pressure drop in the cocurrent and inverse gas-liquid-solid semifluidized beds was found to be a linear combination of that in the fluidized section and that in the packed section. Separate experiments were carried out to examine the parameters of pressure drop and gas hold-up in a packed bed with cocurrent upward flows of gas and liquid or with countercurrent flows of gas and liquid. A mathematical model was also proposed to account for the pressure drop in the packed bed. This part of the study simulates the packed section of a cocurrent gas-liquid-solid semifluidized bed and of a inverse gas-liquid-solid semifluidized bed, respectively.; Qualitative and quantitative studies were made for the solid mixing and hydrodynamics of cocurrent gas-liquid-solid fluidized beds containing binary mixtures of mixed-size and/or density particles. The correlation between the solid mixing states and the flow regimes was examined and described.