The principle of spray drying is to pass the material through an atomizer (spray gun) and polymerize into mist particles in direct contact with hot air for heat exchange, and the drying is completed in a short time. Features include:
The drying speed is fast and the time is short, generally 3 30s.
The drying temperature is lower. Although the hot air at a higher temperature is used, because the droplets contain a lot of moisture, the surface temperature will not exceed the wet bulb temperature of the heated air, generally 50 60, and the material stays in the dryer for a short time, so the final temperature of the material will not be too high, which is very suitable for the drying of heat-sensitive materials.
The product has good dispersion and solubility, and the finished product has high purity.
In addition, there are two methods of spray drying: pressure spray drying and centrifugal spray drying. The pressure spray drying method uses a high-pressure pump to polymerize the material into mist particles through an atomizer (spray gun) at a pressure of 70 200 atmospheres, and is in direct contact with the hot air for heat exchange. The centrifugal spray drying method is to use the horizontal direction of the high-speed rotation of the disc to give the solution centrifugal force, so that it can be thrown out at high speed to form a film, filament or droplet, due to the friction, obstruction, tearing of the air, with the rotation of the disc generated by the tangential acceleration and centrifugal force generated by the radial acceleration, so that the droplet to obtain a more uniform droplet.