Advanced control strategies for fluidized bed dryers

Generating the best possible control strategy comprises a necessity for ind ustrial processes, by virtue of product quality, cost reduction and design simplicity. Three different control approaches, namely an Input-Output line arizing, a fuzzy logic and a PID controller, are evaluated for the control of a fluidized bed dryer, a typical non-linear drying process of wide appli cability. Base on several closed loop characteristics such as settling time s, maximum overshoots and dynamic performance criteria such as IAE, ISE and ITAE, it is shown that the Input-Ouput linearizing and the fuzzy logic con troller exhibit a better performance compared to the PID controller tuned o ptimally with respect to the IAE, for a wide range of disturbances; yet, th e relevant advantage of the fuzzy logic over the conventional nonlinear con troller issues upon its design simplicity. Typical load rejection and set-p oint tracking examples are given to illustrate the;effectiveness of the pro posed approach.