ABSTRACT
Filtermat is the trade name for a multistage dryer that combines two wellestablished drying technologies: nozzle spray drying and continuous fl ow-through belt drying (Rheinlander, 1982; Anonymous, 2000). In the fi rst stage of drying, the high-moisture feed is atomized into a spray chamber of a uniquely designed (Figure 27.1) dryer and contacted with air at a high inlet temperature. This provides for rapid evaporation of water, short contact time, and low material temperature, which translate into a favorable quality product and better process economics. The Filtermat spray dryer is designed to operate with two inlet air temperatures. Hightemperature air enters the spray chamber around each spray nozzle, while low-temperature air enters the dryer through the out-of-the nozzle area. Such a system of air supply ensures better mixing of the drying and atomizing air with the wet feed. Even when predrying feed conditions are not optimum, the manufacturer claims that product quality and process effi - ciency can be maintained by controlling process variables.
