Experimental study and modelling on gas–solid flow in a lab-scale fluidised bed with Wurster tube

A lab-scale fluidised bed with a Wurster tube is designed for investigation of the gas–solid flow hydrodynamic behaviour by experiment and computational fluid dynamics (CFD) simulation. A unique electrical capacitance tomography (ECT) sensor is used to measure the particle concentration both inside and outside of the Wurster tube. CFD simulation is based on computational particle fluid dynamics (CPFD) and Eulerian–Eulerian-based two-fluid model (TFM). Coating processes are measured and key process parameters are analysed, including the solid concentration in a cross-sectional area, the time-averaged capacitance data, the average solid concentration in the chamber and the effect of the Wurster tube on the hydrodynamic behaviour of gas–solid flow. The CFD simulation results using both TFM and CPFD models are compared with the measurement results by ECT for the gas–solid flow in the fluidised bed but without spraying coating solution. The optimum operating range of the Wurster fluidisation process for different particles is discussed based on the CFD simulation and ECT measurement results, demonstrating that the combination of ECT measurement with TFM–CPFD simulation can provide useful information for the process design and operation for a Wurster fluidised bed.