Modeling And Identification For Secondary Cooling Process In Continuous Casting

Iron and steel industry plays a key role in a country, because its own technique level affects the level of the whole nation's industry technology to some extent. Therefore, solving the technical difficulties in the iron and steel industry is in great need and of great significance, especially for the continuous casting (CC) process, which serves as the base of the whole iron and steel industry.In order to get the high-qualitied ingot and stabilize the production during the CC process, we must find the suitable controlling parameters to control it. But because of some limits in real production, the solidification process during it can hardly be observed or researched by experimentation, so it is very difficult to seek the suitable controlling parameters by experimentation in the real production. Based on the consideration above, the introduction of the numerical simulation method for that knotty problem is a natural choice. The numerical simulation method has much merit, which can overcome the difficulties and limits of the real production very well. As a matter of fact, a lot of mathematical models for the CC process have been established for numerical simulation and research by former researchers, and the numerical simulation method has become the most important research method for the CC process.The object of my research work is to build a complete mathematical model for the secondary cooling process during CC process, and identify the unknown controlling parameters in it. Though we want to get the optimized values of the unknown controlling parameters in CC process through the surface temperature of the billet, the direct solution is difficult. Of course, those unknown parameters have close relation with the surface heat flux of the billet. So the initial problem can be transferred to two problems: one is to get the surface heat flux through the surface temperature of the billet and the other is to get the optimized value of the unknown parameters through the surface heat flux. Furthermore, how to get the surface heat flux of the billet by itssurface temperature and initial temperature is a typical inverse heat conduction problem (IHCP) in the mathematical sense.Although the boundary element method (BEM) is recognized as the most efficient one to solve this kind of problems, the inherent conflicts between the simplicity of the method and the complexity of the practice block the large-scale application of the BEM. In order to overcome the difficulty mentioned above, this paper provides an improved heat transfer equation and a mended BEM for the problems. First of all, the enthalpy and the 'virtual temperature' are introduced into the paper to eliminate several mutative thermophysical properties in the heat transfer equation. Secondly, the movement of the boundary between the solid and liquid phases in the billet is educed by virtue of the Laplace transform.After that, we deduce a mathematical model of heat conduction mechanism for the CC process and examine the veracity of the model by computer simulations. The results show that the improved math model for the CC process is efficient.