MODELING AND OPTIMIZATION OF FLUIDIZED-BED AND ROTARY DRYERS

Fluidized bed and rotary dryers are two popular types of dryers utiliz ed in almost every area of drying. In this study, both dryers are anal ysed regarding their design and operational performance, so that they could be compared in a straightforward way. The mathematical models de scribing the convective drying process were evaluated for both types o f dryers. Design procedures aiming at the determination of optimum siz ing and operational characteristics for each type involved were carrie d out by appropriately optimizing the total annual cost of each struct ure for a given production capacity. Both dryer types were compared ex plicitely by evaluating optimum configurations for a wide range of pro duction 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 de signed structures. Rotary dryers rum out to be rather expensive compar ed 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 cove ring a wide range of materials - from food products to inorganic miner als - are included in order to demonstrate the performance of each pro cess as well as the effectiveness of the proposed approach.