ABSTRACT
The cascading rotary dryer is the workhorse of the solids process industry and is to be found in such diverse plants as fertilizer production, pharmaceutical chemicals manufacture, seaweed drying for alginates, lead or zinc concentrate production for smelting, cement manufacture, and many more industries. The ideal model is one that combines all the relevant design and operating parameters to produce a calculation procedure that will accurately predict the mean residence time for a particular rotary dryer design. In the rotary drying operation, the mechanism is usually described as being simultaneous heat and mass transfer, although strictly speaking they are consecutive processes, with the heat transfer preceding and controlling the mass transfer. The drying medium is either hot air or combustion gases that flow concurrently or countercurrently to the direction of the solids through the drum length.
