a) Because the surface area of the mist droplets is large, the drying time required for the material is very short (measured in seconds).
b) In high-temperature airflow, the temperature of the wet material on the surface does not exceed the wet bulb temperature of the drying medium. Due to rapid drying, the final product temperature is not high. Therefore, spray drying is most suitable for heat-sensitive materials.
c) Based on the flexibility of spray drying operation, it can meet the quality indicators of various products, such as particle size distribution, product shape, product properties (dust-free, fluidity, moisture, instant dissolution), product color, aroma, taste, biological activity and moisture content of the final product.
d) Simplify the process flow. The solution can be directly made into powder products in the drying tower. In addition, spray drying can easily achieve mechanization and automation, reduce dust flying, and improve the working environment.
At the same time, spray drying also has the following disadvantages;
(1) When the air temperature is lower than 150°C, the volumetric heat transfer coefficient is low and the equipment used has a large volume.
(2) The separation requirements for gas-solid mixtures are relatively high, and two-stage dust removal is generally required.
(3) Thermal efficiency is not high, generally 30%-50% for co-current tower type and 50%-75% for counter-current tower type.
