What are the bases for centrifugal spray dryer flow types

What are the bases for centrifugal spray dryer flow types

1.Downflow Dryer

In a downflow dryer, the spray enters the hot air and passes through the chamber in the same direction. The spray evaporates quickly and the temperature of the drying air is rapidly reduced by water evaporation. The product is not thermally degraded because once the moisture content reaches the target level, the temperature of the particles is not greatly increased because the surrounding air is now colder. Dairy and other heat-sensitive food products are best dried in a downflow dryer.

2. Counterflow Dryer

The design of this spray dryer introduces spray and air into both ends of the dryer, along with nozzles mounted at the top and bottom into the air. Counterflow dryers offer faster evaporation and higher energy efficiency than current designs. This design is not suitable for heat sensitive products due to the contact of dry particles with hot air. Countercurrent dryers typically use nozzles for atomization, where the spray can move against the air. Soaps and detergents are commonly used in counter-current dryers.

3. Mixed-flow drying

This type of dryer combines downflow and counterflow. Mixed-flow dryers have air entry, upper and lower nozzles. For example, in the countercurrent design, the mixed-flow dryer makes hot air for drying particles, so the design is not used for heat-sensitive products.