Optimizing And Control Of Coal-Pulverizing System With Ball Mill

This dissertation deals with the problem of the optimizing and control of coal-pulverizing system with the ball mill. A new method is proposed to solve the existing problems.The ball mill is widely used in power plant. It is one of the most important assistant devices. It is also one of the energy consuming devices, which takes up to 20% of the total consumption in the power plant. In a long time, due to large time delay, nonlinear property, strong coupled multi-variable and time-varying of the model, the coal-pulverizing has not realized automatic control using general PID control loops. Because the coal-pulverizing system has been in a manual state, it leads to higher power consumption, lower economic value and heavier working intensity.Aiming at this problem, based on the research of 4 ball mills of 300MW in some domestic power plant, the optimization control system is designed that takes the high-performance industrial process computer as the hardware platform, Win2000 Professional as the operating system, AF2000 as the simulation control platform. Auto-control and optimizing running, therefore, are realized.Firstly the structure of the coal-pulverizing system is introduced and the factors affecting the system are analyzed. Also the online simulation model based on milling ability model and heat equalization model is put forward. By measuring data at real time, the online simulation model continuously adjusts output parameters to supervise the online optimizing control system.Secondly, the advanced industry process control technique isdiscussed and the control method is expounded that was adopted in the practical project. In the implementation part of optimizing control scheme, the factor affecting optimizing control and basic condition for optimizing running is analyzed. Then, three control loops have been designed in detail. At last, the essence of se] f- seeking optimization and the implementation scheme are studied.Finally the results of the optimizing control system are analyzed, which include the steady control process, optimizing control process and exceptional control process. The feasibility of optimizing control scheme is explained with the trend chart of control value and status value in different control process.The whole optimizing control software is composed of kinds of control algorithms, merging classical control, intellectual control and human-emulated control. The online optimized control includes the adjustment of the control parameter and algorithms. Traditionally the control method designed fixed control loops for a certain control point, meanwhile the online decision-making control system designs different controlling loops for the same control point and every loop can work solely and achieve different control effect. The software can evaluate on the control effect, current working conditions and historical trend with its self-study algorithm, as a result complete corresponding movements under various working conditions.The software control algorithm software, on the purpose of solving the practical control problems, tested and updated on-spot repeatedly, belongs to none traditional control methods, but combines quintessence of classical and modern control theories.The software, applied in the transformation of 300MWcoal-pulverizing system, runs steadily, improves the systemic contribution, reduces unit consumption of coal-pulverizing, lightens the working intensity, and realizes the automatic control of the coal-pulverizing system with ball mill.It has been proved that the method integrating traditional control method with modern control theory and introducing simulation model is feasible in control large time delay, nonlinear property, strong coupled multi-variable and great inertia industry production process and it has some social and economical value.