Algorithmic approach to process design of direct rotary dryers-coolers

This paper shows how the problem of simulation and design of integrated direct rotary dryer and cooler can be solved in an algorithmic way. In the last few decades dryers and coolers are often assembled in one unit to save space and/or energy (process integration). Several types of construction of such units have been proposed. Since the coupling between models describing both parts of such a unit exists, usually a "trial and error" method is used in the design process to get an acceptable agreement with design specifications. This work shows how to bypass this drawback. Three exemplary cases are studied to illustrate the suggested approach: (1) countercurrent dryer and cooler, (2) cocurrent dryer and countercurrent cooler, (3) double-pass cocurrent dryer and countercurrent cooler. The three cases correspond to typical commercial designs. In addition, an algorithmic way of dimensioning the drum and its interior is presented.