Spray drying is one of the most popular drying equipment in the industry and has a wide range of applications. It can be said to be a dryer that handles solutions, suspensions or slurry materials. The drying effect of spray drying is also very good and the efficiency is high. The product is a powder with uniform particles and no grinding process is required. Now, spray drying has a very high market share in the chemical, light industry and food industries.


1. Characteristics of spray drying:
1. Spray drying Due to the large surface area/volume ratio of the droplet group, the time required for material drying is very short (generally 15-30 seconds, sometimes only a few seconds). Spray drying does not require rigorous equipment. If there is no fiber liquid in the feed liquid, the feed liquid channel will not be blocked. Ability to accommodate high viscosity liquids (compared to pressure spray drying). Since the rotation speed of the atomizer is easy to adjust, the product particle size is easily emptied and the particle size distribution is narrow.


2. Spray drying has large capacity and high quality. The spray volume per hour can reach hundreds of tons, which is one of the dryers with larger capacity. Although the inlet temperature of the drying medium can reach hundreds of degrees Celsius, in most drying processes the material temperature will not exceed the wet bulb temperature of the air. Therefore, spray drying is particularly suitable for drying heat-sensitive materials (such as food, pharmaceuticals, biological products and dyes).


3. Spray drying for easy conditioning. It can change operating conditions within a wide range and control product quality indicators such as particle size distribution, moisture content, biological activity, solubility, color, aroma, taste, etc. When adjusting the processing capacity, there is no need to change the operating status of the atomizer, and the same product can be obtained at the feed rate.


4. Spray drying simplifies the process. It can complete evaporation, crystallization, crushing and other operations in one step with spray drying operation. Since the mist produced by the centrifugal atomizer is basically on the same horizontal plane, the mist droplets move along the radial and tangential composition directions with almost no axial initial speed, so the diameter of the dryer is relatively large.


2. Points to note when spray drying:
1. When the inlet temperature of the drying medium is lower than 150°C, the volumetric heat transfer coefficient of the spray dryer is low, and the volume of the equipment used is relatively large. In addition, low-temperature operation has low heat utilization rate and high drying medium consumption. Therefore, the power consumption is also large. The dispersion disk requires high processing accuracy and should have good dynamic balancing performance. If the balance state is unsafe, the spindle and bearings are easily damaged;
2. For the production of fine powder products, separate equipment is required to prevent product loss and environmental pollution. In spray drying, the product has a lower bulk density.