Temperature profile control of a multiple hearth furnace for kaolin calcination

The main aim of this thesis is to develop a new temperature profile control strategy for kaolin calcination in the multiple hearth furnace (MHF) in order to improve the quality of the product. The overall control strategy for the MHF is developed as a three level control hierarchy: optimizing level, stabilizing level, and basic level. In the literature part of the thesis, first, the kaolin and its formation process is discussed. Next, the general information about calcination process is provided and the calcination of kaolin is discussed. Finally, few past researches having similar objective to this study are reviewed to study the various different control approaches developed so far and the possibility to implement them in our study. In the experimental part, analysis of the process is carried using the experimental data. During the data analysis, activation/ deactivation of the exothermic reaction in the hearth 4 is seen, which is crucial in determining the temperature profile of the furnace. Hence, the soft sensor based on the energy balance to estimate the intensity of the exothermic reaction, which plays a key role in developing the control strategy for the MHF, is developed. Both the static and dynamic energy balance equations are presented, calculated and compared in order to study the dynamic behaviour in the process. It is seen that the dynamic energy balance provides more accurate results than the static energy balance due to the consideration of the transition period