Fluidization

Abstract Fluidization is the art of handling a solid as if it were a fluid. To fluidize solid particles, a gas or a liquid flows up through a particle bed at such a rate as to support the weight of particles via drag force such that the weightless particles are free to move and flow akin to molecules in a liquid. Fluidization by a gas is by far the most commonly used technique, although solids can be fluidized by a liquid, or by a gas and a liquid. Often the gas reacts with the particles as it fluidizes them. Commercially, gas‐fluidized beds are used for a multitude of purposes, from drying solids to burning coal and from making plastics to producing gasoline from heavy oils. The important properties of particles that relate to fluidization are discussed along with the different regimes that fluidized beds can exhibit. The isothermal nature of fluidized beds and the high rates of heat and mass transfer are discussed. Design of fluidized beds is introduced as are the various pieces of hardware needed. Circulating fluidized beds are also discussed, as is industrial scale up.