Rotary dryers are a class of dryer commonly used in ind […]
Rotary dryers are a class of dryer commonly used in industry to dry particulate solids. They are made of a long cylindrical shell that is rotated. The shell is usually slightly inclined to the horizontal to induce solids flow from one end of the dryer to the other. In direct heat rotary dryers, a hot gas flowing through the dryer provides the heat required for vaporization of the water.
The main unit of the rotary dryer is an inclined shell supported by four rollers. Materials, which are fed through one end of the shell, move inside the shell along the inclination of the shell and through the rotary movement and are discharged from the other end. Materials, while moving inside the shell, are lifted up by a lifter incorporated in the shell.
Then, the materials fall evenly in the shell space and exchange heat with the hot air flowing through the space to dry. Depending on the method of providing hot air for the materials, this dryer is classified into two types, that is, concurrent flow drying type by which the hot air and materials flow in the same direction and countercurrent flow drying type by which they flow in the opposite direction.