DRYING OF SOLIDS - SELECTION OF SOME CONTINUOUS OPERATION DRYER TYPES

Design and study of operational performance of convective industrial d ryers are a strong indicator in the last stages of the selection proce dure. This problem is addressed in a straightforward way for the three most popular types; conveyor-belt, fluidized bed and rotary dryers. D esign was carried out by appropriately optimizing the total annual cos t of each configuration for a given production capacity. All dryer typ es were compared explicitely by evaluating optimal configurations for a wide range of production capacity values. Once the dryer configurati on is specified, its optimal operational performance was evaluated by comparing the optimum operational cost versus production capacity for predefined optimal designed structures. Rotary dryers turned to be rat her expensive compared to fluidized bed dryers, regarding design. On o perational grounds, however, it is the other way around due to the und erstandably favored heat transfer achieved in rotary dryers. Conveyor- belt dryers, when utilized, lie somewhere in between producing satisfa ctory results both on design and on operational grounds. A characteris tic example of food dehydration process is included, to demonstrate th e effectiveness of the proposed approach.