Level Measure And Optimum Control Of BBD Coal Mill

BBD Ball Mill is well used in power plant, and it has advantages of low energy consumption, high efficiency, wide application in grinding mill and stable running. However, when the equipment is running, problems such as occasionally asymmetric power, energy consumption becoming larger, even the phenomena that the equipment is jammed or lacked, exist in the Mill because of low precision of the material level detecting equipment. While foreign equipments have higher precision, but the price is high simultaneously. Therefore, it is very meaningful to develop detecting equipment independently to decrease entire cost. The thesis will study on this question.Firstly, the thesis introduces working principle, characteristics of BBD Ball Mill and traditional coal level measuring method, then analyses shortage of low precision of traditional coal level measurement. Therefore, the thesis put forward the subsection measuring method through pressure difference method mixed with noise measuring method. When the Mill works under condition that coal is lacked or jammed, it's difficult for noise method to measure the coal level exactly. And pressure difference measuring method can get well result under this condition. But when the Mill works under the condition that coal level is normal, pressure difference method precision decreases and isn't appropriate for the condition. As in normal level, the noise method gets the highest precision. Therefore, the noise method is adopted. In order to acquire better control effect, the noise measure method needs to be improved. The wavelet packet transformation, which is used to decompose the noise frequency, is adopted to process the Mill noise from the field to find characteristic frequency segment inside the Mill. After that, the decomposed eigenvector is processed by intelligent analysis method, and statistics model of the coal level is built using nerve network. Finally, coal level measurement is achieved.Secondly, in optimum control part, for the consideration of low power consumption, the mill pulverizing optimum control system of BBD Ball Mill is presented in the thesis to guarantee the asymmetric power and the machine to work under best coal level. The coal level control method effectively restrains the shortages of long lagging time and large inertia of the system. Because internal model is obtained by nerve network, and if data are plenty, the system model from above method is better than traditional mechanism modeling. And simulation results demonstrate effectiveness of the method.