ABSTRACT
The various types of dryers may dry using air, direct heat, indirect heat, or atmospherically or in a vacuum. In dealing with a specific category of dryers, the vacuum rotary dryer, a batch dryer available in different forms, is usually most satisfactory. The most well-known type consists of a stationary jacket cylindrical shell, mounted horizontally, in which a set of paddle arms with blades are mounted on a revolving center tube to stir or agitate the material being dried. The actual size of the vacuum rotary dryer required for any given application or operation will depend upon the characteristics of the feed material, changes in the material that take place during the drying cycle, characteristics of the finished product, desired operating temperatures, and the capacity or batch size. In general, materials dried in a vacuum rotary dryer can, in most cases, be dried in a revolving double-cone dryer.
