Back Mix Dryers
The Back Mix Dryers are one kind of Fluid Bed Dryers. These are usually used for powders that are not fluidizable due to high moisture content. These can also be used for improving thermal efficiency in spray dryers. Sometimes they are seen to be used drying whey and permeate. It's typical usage can be witnessed in connection with Spray Dryers. The moist powder enters the integrated
Back Mix Dryers where powder with lower moisture content is already fluidizing. The product temperature and moisture content remains uniform throughout the fluidized layer. By controlling the powder layer in the Back Mix Dryers, residence time can be controlled. By controlling the amount and temperature of the drying air, the moisture content in the fluidized layer can be controlled. The Back Mix Dryers are typically used as an after dryer in integrated Fluid Bed Dryers. However, it is also used in specially designed dryers such as the lactose dryer. The Back Mix Dryers are typically followed by a plug-flow fluid bed for final drying/cooling.