For products that need long resident times (mainly in the food industry), TEMA PROCESS has designed a sub-fluid bed dryer. The layer thickness of the product with normal continuous fluid bed drying is about 10 – 15 cm. If the layer thickness is increased, the spread of product residence time is increased excessively due to axial mixing of the product during the drying process. With sub-fluid bed drying it is possible to run with thicker layers, up to 60 cm. The amount of air is kept to a minimum to keep the mixing to a minimum. With sub-fluidization, the product outlet is equipped with multiple weirs that continuously controls the residence time and discharge of the dryer. Residence times up to 2 hours are possible without substantial mixing.