Mixer dryers serve well the volume niche between tray dryers and fluid beds or rotary drums. When you have to load trays for 1,000 lb. (500 kg.) per hour, it is a lot of handling. This is where you can automate a small mixer dryer and save the labor.
Drying requires temperature, time, air movement, and contact with the product. A mixer dryer has good temperature control of the product, so friable products can be dried.
The mixer dryer has a big advantage when you have to coat and dry. Because of the PHLAUER™ high randomized particle flow, we have applications where we have reduced dramatically the amount of liquid required to coat, further reducing the amount of drying required, and giving a great payback on the investment.
Mixer dryers do have limitations. For example, max temperature 800 degrees; limited space to flow air; and volume—as a rule of thumb 10 tons per hour. There is also a practical limit on the amount of moisture to be removed, probably less than 10%.
Each application has to be examined.
Conduction, convection and vacuum dryers are available.