Materials processed in a Fluidized Bed Dryer or Cooler float on a cushion of air or gas. The process air is supplied to the bed through a perforated distributor plate and flows through the bed of solids at a sufficient velocity to support the weight of particles in a fluidized state. Bubbles form and collapse within the fluid bed of material promoting intense particle movement. In this state the solids behave like a fee-flowing boiling liquid. Very high heat and mass transfer rates are obtained as a result of the intimate contact between individual particles and the fluidizing gas.
The design of the distributor plate ensures that the fluidizing gas is evenly distributed across the area of the bed. The gas velocity is such that only the very fine material fraction is carried over to the dust collection equipment. A high turndown ratio of production capacity is possible and fluctuations of the feed rate are easily absorbed. In most cases, there are no moving parts in contact with the product.
Design variations include: