The spray drying is, due to its characteristics, one of the more used processes in the actuality.
Its theoretical principles and its operative simplicity, allow the drying of a great variety of products.
The basic criteria in the adoption of the type of drier are:
The process itself involves atomization of the liquid feed, generating, in this way, micro droplets. Two types of systems carry out this effect. One is the atomization through rotative disks of high velocity and the other through nozzle systems.
The liquid feed, when atomized, develops a high surface area, generating in this way, a significant increase in heat and mass transference coefficient with the hot air that enters to the chamber.
It can be resumed that the process consists of pumping of a solution, emulsion or dispersion towards the zone of pulverization where it gets in contact with a flow of hot air. This contact is critical to the performance and the quality of drying. The conditions here established such as, airflow, inlet and outlet air temperature, feed temperature, drop diameter, air velocity, etc., determine the properties of the final product.
Once such particle is obtained it must be separated from the airflow. This separation can be carried out both in cyclones or in baghouses.
There is also the possibility of discharging the particle in an external or internal fluid bed, where post drying of the powder is carried out.
The chosen design determines the powder discharge system, as well as the properties of the same.
