Rotary Kilns are used to heat solids to the point where a required chemical reaction(s) takes place. The Rotary Kiln is basically a rotating inclined cylinder, solids retention time in the kiln is an important factor and is set by proper selection of diameter, length, speed, slope and the internal design. 

 

Standard Construction Features : 
Rotary Kilns are normally direct fired and lined with refractory material to protect the steel shell, reduce radiation losses and transfer heat to the material. A typical Rotary kiln is cylindrical shell, slightly inclined from the horizontal and supported on two or more tyres, which in turn rotate on rollers. One of the tyre is fixed axially by a set of thrust rollers to care of the thrust load during kiln movement. The drum assembly along with the tyres are rotated by a girth gear/ pinion arrangement. Shell diameter and length are generally designed to suit specific products.

Heat Transfer in Rotary kiln : All kilns are heat exchangers and the heat is transferred in a variety of ways by radiation, convection and conduction.