Multi Tier Fluid Bed Dryers
These multi tier fluid bed dryers are consist of two or more stacked fluid beds. The upper tier (back-mix or plug flow) is for pre drying and the lower tier (plug flow) for post drying. The drying gas travels counter-current to the solids. The gas leaving the lower tier contains sensible heat which is transferred to the upper tier. Furthermore, each fluid bed may be provided with immersed heating surfaces. These designs result in a low gas throughput and high thermal efficiency which are of great importance in closed cycle drying systems.