Material Measure And Control Of BBD Coal Mill

BBD ball mills are widely used in power plants, but most of them are set in the conservative conditions, with large power consumption and small contribution to the coal-milling system. One of the reasons is that there is still not a practical and accurate method to measure the coal level of the mill (or mill load) accurately. If the mill load overtopped the threshold value, the accident of blocked up and running powder would happen, thus, the engineers have to run the mill uneconomically. The thesis will study on this question. A BBD ball mill material measure method, based on rough set and neural networks information fusion, is proposed in this thesis. And the thesis also brings up the BBD ball mill optimum control system.In this thesis, following works are completed.A BBD ball mill load measure method, based on rough set and neural networks information fusion, is proposed. A group of neural networks are constructed for material measure according to the relative reductions, which is feature-level information fusion. Then using the attribute significance determining method based on rough set theory, the neural networks outputs weights are determined. The weighted sums of all the neural networks outputs are regarded as decision-level information fusion. This scheme speeds up the convergence rate of the neural network learning, moreover, the redundant information is available and the robust performance of the load measure system can be improved. The simulation test shows that the proposed method can accurately reflect the BBD ball mill load, having comparatively high sensitivity.The rough fuzzy hierarchical control method of mill pulverizing optimized control system is presented in this thesis. This hierarchical algorithm can remarkably reduce the rule number of the fuzzy control method. The purpose is to get the equable milling effect in the case of low power wasted. It is proved that the mill can get well effect under proper coal level. The internal model control is adopted in this design. The ball mill pulverizing system has large inertia time constant, time-delay and overshoot. So the traditional control design could solve some problem but that is not satisfying.