Fluid bed dryer

Fluidized bed dryers and coolers are parts of a drying system in which air flows through the product against gravity and forms a fluidized bed with it. Other parts are fans and heat exchangers. The dryer and cooler are either separate units or a combined machine with two thirds of the length devoted to drying and one third to cooling. One application is the quick and gentle drying and subsequent cooling of cereal flakes , such as oat flakes , which can be stored with a final moisture content of approx. 11%.

Layout and function

The inclination of the device and the special perforation of the sieve grate cause a movement towards the outlet, whereby moisture and heat are extracted from the material to be treated. The air supply channels under the screen are divided in the direction of flow. The air flow is alternately interrupted by so-called pulsators, which are rotating flaps driven by a gear motor. This ensures that the fluidized bed settles alternately and each particle is washed around by the air flow and treated evenly. At the outlet there is a damper with which the height of the fluidized bed can be adjusted. The inclination adjustment enables the adaptation to different products to be treated. The necessary air flow is generated by fans for cooling air. An air heater, which is usually heated with steam, is arranged in front of the drying section. Air throttles and exhaust air throttles allow the correct choice of air volumes.

literature

• P. Erling (Hrsg.): Manual flour and peeling mill . AgriMedia, 2004, ISBN 3-86037-230-0 .