Classification of Spray Dryer and Its Application Range (Part II)——Zhao Xiefang, General Manager of Vanguard Drying Co., Ltd.

2. Pressure spray dryer
The product of pressure spray dryer is in the form of fine particles, and the average particle size can reach 150-200μm. The product has good fluidity, wettability and other application properties.
The working principle of the pressure spray dryer is that the liquid enters the rotating chamber from the tangential channel of the atomizer at a high pressure under the pressure of the high pressure pump, so that the liquid generates a high-speed rotating motion in the rotating chamber. When the rotation speed reaches a certain value, the liquid is formed into a mist group composed of innumerable droplets, and the moisture evaporates to form a particulate product. The dryer is suitable for the following products:
Chemicals: Catalysts, resins, synthetic detergents, oils and fats, ammonium sulfate, dyes, dye intermediates, silica, graphite, ammonium sulfate, pesticides, potassium fluoride, brighteners, etc.
Food categories: seasonings, protein, starch, dairy products, protein, starch, glucose, pectin, maltose, potassium sorbate, pumpkin powder, etc.
Drugs: Chinese patent medicines, antibiotics, traditional Chinese medicines, Chinese medicine extracts, pharmaceuticals, yeasts, vitamins, antibiotics, amylases, lipases, etc.
Ceramics: Magnesium oxide, china clay, various metal oxides, dolomite, kaolin, alumina, talc, etc.
Plastics: ABS emulsion, urine aldehyde resin, adhesive (urea) formaldehyde resin, polyethylene, polyvinyl chloride and so on.
3. Air-flow spray dryer Air-flow spray dryer is mainly used in products requiring finer granularity, such as pharmaceuticals. This equipment is more suitable for some materials with high viscosity and thixotropy. Its working principle is to use high-speed air flow to split the liquid film. When compressed air or steam is sprayed from the atomizer at a high annulus velocity, friction and shear forces are generated between the gas and liquid, and the liquid breaks instantaneously. And the formation of tiny droplets. Then the droplets run with dry hot air and the moisture quickly evaporates, drying the material in a very short time.
The characteristics of the air-flow spray dryer are simple structure, convenient processing, large elasticity of operation, easy adjustment, and is suitable for the drying of liquid materials with good fluidity such as solution, emulsion, suspension, and paste liquid. Its application scope is:
Chemicals: sulfonated phenolic resin, sodium humate, aluminum chloride, silica, potassium fluoride, dyes, pigments, detergents, pesticides, fertilizers, inorganic compounds and organic compounds.
Food categories: chicken, caramel, soy protein isolate, plant hydrolyzed protein.
Medicines: Chinese herbal extracts, peptone, blood meal, yeast extracts, liver plasma, etc.
And the drying of powder coatings, ceramics, mineral products and other materials.