Modeling and Simulation of Wide Load Operation of ZGM Medium Speed Coal Mill

In order to meet the demand of rapid response of coal pulverizing system for flexible peak shaving of thermal power units under wide load, aiming at the problem that the dynamic simulation model of ZGM medium speed pulverizer is not accurate enough under wide load conditions, a dynamic mechanism model is established based on the law of conservation of mass and energy. Local sensitivity analysis is used to determine the key parameters (primary air volume, air temperature and heat factor). Combined with the heat balance mechanism, the latent heat and heat dissipation model of vaporization is modified. The results show that the simulation error of the modified model is less than 5% in the wide load range of 40%-90%. On this basis, aiming at the problem of fuel supply lag caused by the start-up window period of the coal pulverizer during the rapid load-raising process, the nonlinear effects of coal feeding slope rate, primary air volume and primary air advance time on key parameters such as response time of pulverized coal output and outlet temperature are analyzed. The grid search multi-parameter optimization is used to obtain the optimal parameter combination method for improving the output of the operating coal pulverizer, which can shorten the response time of pulverized coal flow to 300 s at low load and 350 s at high load, which is about 3.6 min earlier than the start-up mode of the coal pulverizer, and the outlet temperature fluctuation meets the safety constraint requirements. This study provides a reliable model basis and optimal operation scheme for accurate simulation of wide load and rapid variable load operation of coal mill.