In the production of milk powder products, two types of dryers are commonly used - drum dryers and spray dryers. Each type of dryer has certain advantages.
Spray dryers are more commonly used because they are less damaging to heat and produce a more soluble product. The concentrated liquid dairy product is sprayed into the hot air stream as a fine mist. The air can be heated through a steam-heated "radiator" or directly through sulphur-free natural gas. The drying chamber can be rectangular, conical or silo-shaped. From the drying chamber, the powder passes through a series of cyclones, usually placed in durable paper bags lined with plastic.
Spray-dried milk powder is also difficult to reconstitute or mix with water. Therefore, a process called agglomeration was developed to "instant" the powder or make it more soluble. This process involves rewetting the spray-dried fines with water to approximately 8% to 15% moisture, followed by a second drying cycle. The powder is now granular and dissolves well in water. Almost all nonfat dry milk in retail packages is instantiated in this way.
https://www.stardrying.com/
