Three‐Phase (Gas–Liquid–Solid) Fluidization

This chapter describes systems where liquid plays a major role, in addition to gas, in driving the flow. It summarizes the operating modes, applications, and general design and modelling of gas–liquid–solid fluidized beds. The chapter illustrates the application of transport phenomena models to characterize reactor performance for the mode of operation where both gas and liquid flow upwards and liquid is in the continuous wetting phase. It presents a worked example for a three-phase fluidized bed hydrocracker and provides mathematical expressions for the fluid dynamic and interphase mass transport for the bulk fluidized bed region. The performance of three-phase fluidized bed systems can be successfully modelled by understanding the regions of interest (plenum, distributor, bulk bed, and freeboard), relevant scales (time, length), and impact of physical properties and operating conditions on fluid dynamics (incipient fluidization, flow regimes, phase holdups), transport correlations (heat and mass transfer), and reaction rates.