lab spray dryerIn general, the process can meet the requirements of output and quality (such as particle size distribution, residual wet content, volume density, etc.) and output. The first level process represents the vast majority of spray drying systems. However, in order to improve the yield and quality and improve the thermal efficiency of the dryer, two level and three stage drying systems combined with spray drying and fluidized bed drying or belt drying have been produced.

As for the products with very complex drying, the technical requirements are very strict. When it is difficult to complete the first-level process, the second-level process or the third-level process can be adopted.

second levelExperimental typeSpray dryerTechnological process

The spray dryer is used as the first stage dryer, the fluidized bed as the second stage dryer, or as the dryer and cooler.OneGrade is spray dryer.TwoThe first stage is a vibrating fluidized bed dryer with single point discharge. Secondary drying and primary ratio are energy saving.

Spray drying of nozzle atomizer+Secondary drying of agglomeration granulation in built-in fluidized bed, fine powder returns to tower and adheres to droplets. The dry particles on the fluidized bed and the wet particles coming down from the nozzle stop agglomeration and granulation in the fluidized bed, and the agglomerated products are discharged out of the tower.

Level threeExperimental typeSpray dryerTechnological process

The three stage spray dryer system is widely used in the food industry. It can complete the drying of complex products, such as spray granulation, add some other ingredients, etc. Secondary, tertiary drying and primary ratio can not only improve production and quality, but also save energy.

Spray dryer is another type of three stage drying process used in food industry. In the first stage spray drying, the material is turned into powder and the moisture content is10%～20%It depends on the type of product. The semi dry powder is stacked at the bottom of the spray drying chamber, which is woven by polyester thread. Dry air passes through the dust layer and conveyor belt at a fairly high speed. This is the second stage of drying (through-flow drying). In the second stage of drying, the residence time is very short. The dust is then sent to the third stage of drying. In this section, it is also through-flow drying. In this stage, drying is completed at low temperature to reach regular moisture.

Final product, aggregate particles with instant solubility. The humidity of the exhaust air is higher than the secondary drying temperature.Sixty～Seventy℃It is also lower and has higher thermal efficiency.

The use of secondary or tertiary drying has the following advantages:

①The wet content of the product can be very low.

②The temperature of powder products is low.

③Can change the size of powder dispersion (can gather, can be graded);

④Improve the thermal efficiency of drying process;