Modeling And Control Of Stirring System For Ladle Refining Furnace

Stirring is an important means of accelerating metallurgical reactions, and promote molten steel composition and temperature uniformity. Argon stirring system is applied in the field of steel smelting, because of its good metallurgical effects, such as it also accelerating the rate of chemical reaction for steel and slag, removing the harmful gases and impurities and so on. Bottom blowing argon stirring system has nonlinear, delay, time-varying characteristics, etc, the smelting process of Ladle refining furnace require the working point (set value) of bottom blowing argon system in a furnace is frequent change in time, so the Argon stirring system control precision and response speed are put forward higher request.Through the analysis and study of argon stirring system for ladle refining furnace based on the relevant theories of fluid mechanics and rigorous complicated mathematical deduction, adopt the method of segmentation processing to establish the mathematical model of controlled object, the dynamic mathematical model of each part is deduced respectively in the gas supply pipeline, and then the model is applied to the complete gas pipeline system, established the mathematical model of gas pipeline.In consideration of the controlled object’s time delay characteristics, on the basis of the classical PID controller, the control strategy of Smith predictor is stated to solve the effecting by the time delay, designed the controller with Smith estimates. The superiority of the control strategy is verified after introducing Smith estimates by the simulation.Analysis of object model, found that the major factor in the production of time-varying have the area of ladle porous plugs, air pressure, molten steel static pressure and so on. Considering the time-varying factors and the set values are usually changed in smelting process is known in advance, using feed forward control can improve the response speed of argon stirring system. Because of the traditional feed forward control cannot meet the requirement of the system control, it proposes the thought of a working point migration based on neural network, designs the integrated controller of argon stirring system, this controller can make the argon flow track the set value steadily, quickly, and accurately is verified by the simulation.At last, the thesis shows the design of the control system’s hardware and software, designs the upper computer monitoring system by WinCC, it realizes real-time monitor and survey and dynamic management in argon stirring process, and improves the level of monitor and control of argon stirring.