Fluid beds are designed to dry powder particles where the residual moisture content is higher than what is wanted in the final powder.
Hot drying air is distributed through specially designed perforated plates, on which the powder particles/agglomerates are resting. The velocity of the drying air makes the powder ‘fluidize’, i.e. the particles get airborne; however, to the extent that only the finest/smallest particles leave the fluid bed with the air, while the bigger particles/agglomerates are conveyed/transported with the upward flow of drying air directed in a certain angel (due to the perforation technique of the plate) to facilitate fluidization and/or transport of powder into the subsequent section.
Some products are difficult to fluidize due to high moisture content, as is the case when powder is discharged from a spray dryer. Here, a back mix fluid is integrated at the bottom of the spray dryer. The moist powder enters the integrated back mix fluid bed where powder with lower moisture content is already fluidizing. The product temperature and moisture content remains uniform throughout the fluidized layer. By controlling the powder layer in the back mix fluid bed, residence time can be controlled, and by controlling the amount and temperature of the drying air, the moisture content in the fluidized layer can be controlled.
GEA Niro Integrated back mix fluid beds are designed for the solids flow pattern of a spray dryer. It is typically used as an after dryer in integrated fluid bed dryers and followed by a plug-flow fluid bed such as the GEA Niro VIBRO-FLUIDIZER™ for final drying or cooling.
All GEA Niro plants for food and dairy products are designed with focus on hygienic design and construction. All plants can be delivered with integrated CIP cleaning where the goal is fast operation to secure the most production time.
All plants designed and supplied by GEA Process Engineering will enable the end user to obtain approvals put forward by the EU directive.