ABSTRACT
The product of the pressure drop and the bed cross-sectional area represents the net upward force acting on the bed, and when this force becomes equal to the weight of the bed, the bed becomes suspended by the fluid. In this state, the particles can move freely within the "bed," which thus behaves much like a boiling liquid. Under these conditions, the bed is said to be "fluidized." Many particles are not spherical and so will not have the same drag properties as spherical particles. The effective diameter for such particles is often characterized by the equivalent Stokes diameter, which is the diameter of the sphere that has the same terminal velocity as the nonspherical particle. Sedimentation, or thickening, involves increasing the solids content of a slurry or a suspension by gravity settling in order to effect separation of the solids and the fluid.
