A fluidized bed consists of discrete particles through which a gas or liquid flows upward. Fluidization is achieved when the gas or liquid velocity is sufficiently high that the drag on the particles is equal to their weight. The particles are suspended in the fluid flow, without being transported, over a significant range of fluid flow rates. Fluidization occurs primarily because of a dynamic balance between forces resulting from the flow of a fluid through a bed of discrete particles and gravitational forces. Practical realization of the fluidized state is achieved in a container having an appropriately constructed porous bottom, termed a distributor. Examples of distributors include a porous plastic sheet, or a steel plate with drilled holes.