**3.4 Industrial spray drying systems**

The development of spray drying equipment and techniques evolved over several decades. With the sudden need to minimize the food materials transport weight, spray drying was established during World War II. This method enables feed transformation from a fluid state into a dried particulate shape by feed spraying into hot drying media. It is a continual particle processing drying operation. The feed could be an emulsion, suspension, solution, or dispersion. The dried product could be in the shape of granules, agglomerates, or powders dependent on feed's chemical and physical characteristics, and the dryer scheme, as well as the final powder properties, desired [47]. Spray drying is a suspended particle processing (SPP) operation. This method uses fluid atomization for creating droplets. The droplets are dried into single particles when transferred to a hot gaseous drying media, generally it is air. It is considered a one-step continual unit processing procedure. Nowadays, over 25,000 spray dryers are used commercially to dry products such as fine and heavy chemicals, dyestuffs, dairy products, agrochemicals, and biotechnology products as well as mineral concentrates used in pharmaceuticals for preparing with evaporation capacities ranging from a few kg/h to over 50 tons/h.

Spray drying advantages:


Spray drying disadvantages:


Spray drying involves of three process phases: (1) atomizing, (2) moisture evaporation and spray-air mixing, and (3) separation of dry product from the exit air. Every phase is conducted according to the operation of the dryer as well as the design or chemical and physical properties of the feed, determining the features of the final product. A spray drying procedure model is illustrated in **Figure 14**.
