Local Linear Modelling of the Cement Rotary Kiln Based on Mathematical Models by the Method of Weighted Residuals. A study on modeling for control purpose in cement burning process.

The cement rotary kiln process involves the potentiality to utilize a variety of wastes as fuels. Therefore this process itself has been modified to adapt these conditions. Generally these processes are described by a distributed parameter model, therefore, these expressions are rather complicated and not suitable for control purpose. On the other hand the models developed exclusively for control purpose are too much simplified to reproduce the practical process. So it is necessary to develop an adequate model to estimate the dynamic behaviors and to be used in designing optimal control systems. The aim of this paper is to present the local linear models based on mass balance, heat transfer for its control purpose by applying the method of weighted residuals. However, this method does not work favorably under such a condition introducing the mass of feed as a manipulated variable. To apply this method to its condition, both numeric and symbolic computation power were required in modelling. Consequently some local linear models of reduced order were proposed for its control purpose. Especially, the model involving manipulated variables such as the mass of feed has been derived easily by using the MATLAB. Furthermore the authors have also conducted the comparison between the response from this model and that from the exact model. The good agreements between them have proved this approximation method to be adequate.