Hydrodynamics of Reduced Pressure Fluidization Employing Particles with Variable Density

Abstract

A series of experiments was carried out to study the hydrodynamics of a fluidized bed operating at reduced pressure and employing particles with variable moisture content; that is, of variable density. In these experiments, four different types of particles were used and fluidization characteristics very similar to the ones encountered in atmospheric pressure operations were observed. A novel method to measure the minimum fluidization velocity of particles with varying density was proposed. The experimental results demonstrated that the minimum fluidization velocity increased with decreased operating pressure, increased operating temperature, and increased particle moisture content. However, the bed voidage under minimum fluidization conditions showed very little sensitivity to variations in operating pressure. Two equations were developed to predict the minimum fluidization velocity and the results were compared with the experimental data as well as with the predictions of equations available in the technical literature.

A CFD Comparative Study of Bubbling Fluidized Bed Behavior with Thermal Effects Using the Open-Source Platforms MFiX and OpenFOAM

“…For the design of fluidized bed systems, the minimum fluidization velocity is arguably the most important variable [1,2] and can be generally defined as the minimum superficial velocity at which the pressure drop through the bed is equal to the bed weight per unit cross-section. A large amount of experimental work has been carried out on this parameter, and many correlations have been proposed for its prediction in the literature [3]. Regarding fluidization with heat transfer, the thermal uniformity is one of the main features of bubbling fluidized beds.…”