On the dynamics and control of continuous fluidized bed layering granulation with screen-mill-cycle

Abstract

This paper is concerned with an experimental and theoretical study of dynamics and control of fluidized bed layering granulation with external screen mill cycle. To achieve quantitative agreement between model calculations and experiments an extended dynamic process model is proposed. In contrast to previous work by Dreyschultze et al. [1] specific plant characteristics are taken explicitly into account including a more detailed model of the milling process and a classifying particle withdrawal from the granulation chamber. The model is then used to develop new control strategies. First, a novel bed mass controller is designed and validated. Afterward, a second control loop is introduced to dampen the oscillatory behavior of the particle size distribution. It is shown that the new control concepts achieve stable steady-state operation within a short time and thereby improve the process dynamics significantly. Theoretical predictions and experimental results are shown to be in good agreement.