In the food industry which is so diversified and extensive, there are a great number of different types of dryer would be in use. There are tray dryers, drum dryers, fluidized bed dryers, spray dryers, rotary dryers and freeze dryers, to name a few. Although these dryers differ physically and operates differently for different objectives, they all apply the same principles of mass and heat balances as the basis.
As an example, in tray dryers, the food is thinly spread outon trays in which the drying takes place. Heating may be by an air current sweeping across the trays, by conduction from heated trays or heated shelves on which the trays lie, or by radiation from heated surfaces. Most tray dryers are heated by air, which also removes the moist vapours.
In a spray dryer, on the other hand, liquid or fine solid material in a slurry is sprayed in the form of a fine droplet dispersion into a current of heated air. Air and solids may move in parallel or counterflow. Drying occurs very rapidly, so that this process is very useful for materials that are damaged by exposure to heat for any appreciable length of time. The dryer body is large so that the particles can settle, as they dry, without touching the walls on which they might otherwise stick.Spray drying is applied on a large scale in the dairy industry and for drying coffee.
This SOLTEQ® Tray Dryer is ideally suitable for lab tests on drying of food materials such as spices, chips, nuts, etc. It can also be used for lab test on drying of pharmaceuticals, chemicals, powders, granules, etc. Custom-built models of different sizes and requirements can be designed upon request.
This Spray Dryer is a bench mounted unit which is designed for the rapid spray drying processes involving aqueous emulsions, solutions, suspensions and colloids.