Brief And Characteristics Of Centrifugal Spray Dryer

Centrifugal spray dryer is a drying method to obtain the product by using an atomizer to disperse the raw material liquid into mist droplets and drying the droplets with hot gas (air, nitrogen or superheated steam). The raw material liquid may be a solution, an emulsion, or a suspension.

The centrifugal spray dryer disperses the material liquid into mist droplets, which increases the heat and mass transfer rate during the drying process. The atomizer is one of the key components of spray drying. At present, there are three types commonly used, namely pressure atomizer, centrifugal atomizer, and airflow atomizer.

The contact surface area of the atomized liquid and hot airflow is very large. It will quickly conduct heat and mass transfer as soon as it comes into contact with the higher temperature airflow. The water droplets absorb the heat and quickly evaporate into water vapor. As a wet body. In the initial stage of drying, the mist droplets are small, the drying resistance caused by the diffusion and transmission of the moisture content inside the material is almost equal to zero, and the temperature of the material is always at the surface wet bulb temperature of the material, which is a constant speed drying stage.

When the surface of the material is not filled with water, the material starts to heat up and forms a temperature gradient in the interior, which is a slow-drying stage. If the temperature gradient is large and the vapor pressure inside the material is greater than the cohesion of the surface of the material particles, the particles will burst and instantly increase the mass transfer evaporation surface. Therefore, spray-dried powders are mostly non-spherical.

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Characteristics of centrifugal spray dryer

Fast-drying speed. After spraying the material liquid, the surface area is greatly increased. It can evaporate 95% -98% of water, and it only takes a few seconds to complete the drying time.

The co-current spray drying method can be used to make the droplets flow in the same direction as the hot air. Although the temperature of the hot air is high, the hot air enters the drying room and immediately comes into contact with the spray droplets. The indoor temperature drops sharply, and the wet-bulb temperature of the material Basically unchanged, so it is also suitable for drying heat-sensitive materials.

The use of a centrifugal spray dryer is wide. Depending on the characteristics of the material, it can be used in a laboratory spray dryer. Most products with very different characteristics can be produced with this machine.

The entire operation is airtight and the centrifugal spray dryer is suitable for clean production areas. Because the spray drying operation is performed in a closed tower, cross-contamination and dust flying are avoided, which is suitable for the production of APIs in the pharmaceutical industry, especially the production of sterile APIs.

Because the drying process is completed in an instant, the particles of the finished product of the centrifugal spray dryer can basically maintain the approximately spherical shape of the droplets, and the product has good dispersibility, flowability, and solubility.