Indirect rotary dryers are continuous, atmospheric contact dryers widely employed in industry for continuously processing large quantities of wet solids. It can handle very high throughputs. It is used when direct rotary dryers are unsuitable. This is because direct contact with hot combustion gases is not permissible for product quality reasons or because of the presence of fine particles, which can easily become entrained in the higher gas flows found in convective rotary dryers. It cannot handle liquids or slurries or adhesive solids. The most common design consists of a cylindrical shell inclined at a small angle to the horizontal. Wet feed is introduced into the upper end and dried product withdrawn at the lower end. Transportation of solids through the dryer is assisted by slowly rotating the shell.