Principle of spray drying equipment

Among various drying equipment, spray dryers are one of the most widely used, used for drying solutions, suspensions, or slurries. Their biggest advantage is the ability to directly dry liquids into powders; however, their disadvantages include low thermal efficiency, large size, low production capacity, and high investment cost. Due to its unique advantage of directly producing uniformly powdered products from solutions or suspensions, spray drying is currently widely used in the chemical, light industrial, and food industries, with the dye industry being the most extensive application in the chemical industry.

The working principle of a Spray Dryer is as follows: the material is sprayed into droplets and dispersed in hot air. The material and the hot air come into contact with each other in a parallel, counter-current, or mixed flow manner, so that the moisture evaporates rapidly and the drying purpose is achieved.

This drying method eliminates the need for unit operations such as concentration, filtration, and pulverization, and can obtain granular products with a particle size of 30~500μm. Moreover, the drying time is short, typically 5~30 seconds. Spray drying is suitable for drying highly heat-sensitive materials and materials that are easily dispersed during liquid concentration, resulting in products with good flowability and rapid solubility.