471370 Reduced Bubbling and Effect of Cohesive Forces through High-G Operation in Rotating Fluidized Beds in Vortex Chambers

Tuesday, November 15, 2016: 2:46 PM
Golden Gate (Hotel Nikko San Francisco)
Juray De Wilde, Materials and Process Engineering (IMAP), Université Catholique de Louvain (UCL), Louvain-la-Neuve, Belgium

The performance and application range of classical fluidized beds is limited by the role of earth gravity. The formation of meso-scale structures is detrimental for the gas-solid contact. Large (Geldart-D type) and fine (Geldart-C type) particles are poorly fluidized, the latter because of the dominance of the intra-particle van der Waals forces. In rotating fluidized beds in vortex chambers, high-G operation allows increased gas-solid slip velocities and intensification of interfacial mass, heat and momentum transfer. It is shown that the latter allows reducing the formation of meso-scale structures, further intensifying interfacial mass and heat transfer and eventually reactions. Intensified interfacial momentum transfer also reduces the impact of cohesive forces, allowing fluidizing and processing fine cohesive particles and facilitating fluidization of wetted particles. The gas driving the particle bed rotational motion in the static vortex chamber also results in a unique flexibility with respect to the gas flow rate. The fluid dynamics and design of vortex chambers are discussed and the relation with the particle characteristics is explained. Examples of experimental studies demonstrating the advantages and disadvantages of vortex chamber technology in particle drying, coating and granulation are given.

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