| In ladle furnace, Argon bottom blowing system is the key device which realizes the stirring to make the molten steel temperature and chemical compositions distributed even, remove the gas and nonmetallic materials, and improve the quality of molten steel.First of all, in 60t LF, a two-equation turbulence model and transmission model are established according to the knowledge of Fluid Mechanics. At the same time, the boundary conditions and numerical solution are determined. Then numerical simulation is done using CFD software Fluent6.3. The steady-state flow field and transient flow field are demonstrated. Through the analysis on the stirring effect, mixing time, entrapped slag and the fluctuation height in the surface, the optimum argon blowing curve of 60t LF is shown.To realize the accurate control of Argon flux and design the flux controller, it is primary to design the model of controlled object. The model is established using System Identification Method. Firstly, determine the model structure by means of the mechanism analysis of Argon bottom blowing system process, then, identify the parameter of the model using the least squares method based on a set of test data; finally the mathematical model of controlled object is achieved. In order to adapt the change of work condition and disturbances, a kind of modified Fuzzy-PID composite serial control system of self-adjustment factor is designed. The self-adjustment factor realizes on-line adjustment according to the deviation of the argon flow, so the control rules of the fuzzy controller are adjusted. This Fuzzy-PID controller makes the full use of both the good dynamic characters of fuzzy controller and eliminating static deviation of PID controller. Through the simulation of the Argon bottom blowing system in MATLAB/SIMULINK which provided rational simulation effect, the accurate control of Argon flux is realized.
|
PDF Full Text Request