Modeling and optimization of fluidized bed and rotary dryers

Fluidized bed and rotary dryers are two popular types of dryers utilized in almost every area of drying. In this study, both dryers are analysed regarding their design and operational performance, so that they could be compared in a straightforward way. The mathematical models describing the convective drying process were evaluated for both types of dryers. Design procedures aiming at the determination of optimum sizing and operational characteristics for each type involved were carried out by appropriately optimizing the total annual cost of each structure for a given production capacity. Both dryer types were compared explicitely by evaluating optimum configurations for a wide range of production capacity values. Once the dryer sizing parameters are defined, its operational performance can be evaluated by comparing the optimum operational cost versus production capacity for predefined optimum designed structures. Rotary dryers rum out to be rather expensive compared to fluidized bed dryers, regarding design. On operational grounds, however, it is the other way around, due to the understandably favored heat transfer achieved in rotary dryers. Characteristic examples covering a wide range of materials - from food products to inorganic minerals - are included in order to demonstrate the performance of each process as well as the effectiveness of the proposed approach.