High-G fluidization in vortex chambers

High-G fluidization in vortex chambers is discussed. In a first part of the presentation the basic functioning of vortex chambers is explained. Fluidizing gas is introduced via tangential slots and evacuated via a centrally positioned chimney. As a result a strong free vortex is generated in the chamber. Particles introduced in the rotating gas flow are entrained, forming a rotating fluidized bed. The gas flows from the periphery towards the chimney and the particle bed is radially fluidized with a bed density depending on the generated centrifugal force and radial gas-solid drag force. In a second part of the presentation, main fluid dynamics characteristics are illustrated by means of experimental observations and CFD simulations. The fluid dynamics in the chamber is indeed complex with secondary flows being generated by the presence of the end walls of the chamber. Furthermore, the vortex chamber slot design, the solids inlet design and the chimney design can affect the strength of the centrifugal force and related bed density and uniformity. In a last part of the presentation, it is shown how fluidization in a high-G field increases the gas-solid slip velocities, as such intensifying gas-solid mass, heat and momentum transfer. This allows ca. one order of magnitude process intensification by more efficient gas-solid contact, gas-solid separation, and in certain applications particle-particle segregation. Various example applications that have been studied are discussed: particle drying, fine particle coating and spray drying. The advantages and disadvantages of using vortex chamber technology will be highlighted. Keywords: High-G fluidization, vortex chamber technology, process intensification, particle drying, particle coating, spray drying.