Set-point optimization and control of coal-pulverizing systems with ball-tube mill

Stable control of a coal-pulverizing system with ball-tube mill usually cannot be hold due to some disturbances, such as coal hardness and steel ball wearing, etc. A hierarchical structure with a direct control layer and a set-point optimization layer is applied to this typical system. Based on steady-state gain models of different operating points, a grid search method is employed to calculate optimal set-point values at the optimization layer, and then a block decoupling multivariable controller is easily implemented at the direct control layer. The proposed structure and strategy are readily available to the industrial field engineers. Simulation results demonstrate the effectiveness of this control strategy.