Optimization control of a pulverizing system on the basis of the estimation of the outlet coal powder flow of a coal mill

Abstract This study aimed to master the operating characteristics of a pulverizing system, improve the output control precision of the system, and reduce the fluctuation amplitude of the main operating parameters of coal-fired units. A nonlinear dynamic model of a direct-fired pulverizing system that considers the effect of coal moisture on the energy balance of a coal mill was established. Then, an estimated signal of the outlet coal powder flow of the coal mill was constructed as a new output control target of the pulverizing system. Finally, an output control optimization method for the pulverizing system was designed on the basis of this signal. Simulation results showed that the model effectively reflects the dynamic characteristics of a pulverizing system. In addition, the results of simulation were concordant with those of online measurements. The control scheme reduced the internal disturbances in the coal feed rate, thereby improving the tracking capability and control precision of the pulverizing system's output and enhancing the disturbance suppression capability of the mill outlet temperature. Thus, the designed control scheme can ensure the safe and stable operation of coal-fired units.