An intelligent mill load switching control of pulverizing system for an alumina sintering process

The pulverizing system for alumina sintering utilizes the hot air, generated by the remaining heat for cooling clinker, to dry the coal powder. Since the temperature of such hot air is low and varies frequently, it can usually causes either a low temperature condition of coal powder or an overload condition, leading to operational faults such as `powder-enwrapped balls´ and `mill blockage´ as well as unexpected termination of mill operation. Under such fault conditions the existing mill load control system cannot be put into use. To avoid the operational faults, an intelligent switching controller is developed and presented in this paper. This new controller consists of a coordinative controller for the mill load and the mill outlet temperature, a PI controller for the mill load, a rule reasoning based over load controller and a switching mechanism that is also based on rule reasoning. This method has been successfully applied to the mill load control of the pulverizing system for an alumina sintering process. It has been shown that such a control strategy can make the mill outlet temperature be within its required ranges and can guarantee the mill load to be within its range so as to ensure a maximum mill output.