ABSTRACT
One of the most unusual types of equipment used by chemical engineers is the fluidized bed, a device in which solid particles, for example sand or catalyst particles, are made to behave like elements of a fluid, and hence are “fluidized”. The state of being fluidized, called “fluidization”, turns out to be advantageous for a number of important chemical and physical processes designed and operated by chemical engineers. Fluidization can occur when a gas or liquid is forced upwards through a bed of particulate material resting on a perforated or porous horizontal plate, for example a plate in which evenly spaced holes have been drilled to occupy typically 3 to 6% of the plate cross sectional area. Fluidized beds are first categorized according to the type of fluid which is causing the fluidization. Gas-liquid fluidized beds are of considerable importance in biochemical engineering, for example in biological wastewater treatment and fermentation.
