Fluidized-Bed Furnace

an industrial furnace for drying, firing, calcination, and other processes, in which the interaction between the solid granules of material and a gas stream occurs in a fluidized bed. Such furnaces have become widespread in various areas of industry in the USSR and abroad during the second half of the 20th century.

Fluidized-bed furnaces are cylindrical or rectangular and consist of a reaction chamber and chambers for the supply of the air or gas blast to the distribution hearth. The hearth, which is designed to provide uniform distribution of the blast over the entire cross section of the reaction chamber, is a metal grating or a concrete plate with openings. It is sometimes made from porous ceramic blocks. The solid granular charge is suspended by the air or gas flowing through the grid and forms a fluidized bed in which the interaction between the solid and gaseous materials takes place. The finished product (for example, sinter) is discharged from the furnace through a door at the upper level of the fluidized bed. Heat exchangers are installed in the fluidized zone to conduct excess heat away from the bed during exothermic processes (firing) or to supply heat to the fluidized bed during endothermic processes (reduction). Multichamber fluidized-bed furnaces with several sequential fluidized beds are used for processes involving treatment of materials in several steps at various temperatures and varying composition of the gaseous phase.

In comparison to furnaces of other types (for example, rotary kilns), fluidized-bed furnaces provide more effective interaction between the gas and the material being treated and a more uniform finished product; they also make possible intensification and automation of the processes taking place in them.