Realization Of Billet Surface Temperature Soft-sensing Based On Heat Transfer Model In Continuous Casting

In the process of continuous casting, continuous, precious and steady measurement of billet surface temperature is the basis of dynamic secondary cooling control system. But it is extremely hard to realize by traditional methods because of the affection of high temperature steam stream and oxide films. So a soft-sensing method based on heat transfer model in continuous casting was presented in this thesis. Aimed at on-line using, a dynamic model is introduced. And its real-time ability, calibration and reliability was analysed and studied, and then application software called NEU-CAST was developed to finish the soft sensing.of billet surface temperature. Applying NEU-CAST, the surface temperature of billet can be calculated and analyzed. The main contents and innovations in this thesis are as followings:(1)Aimed at the unsteady continuous casting process, a dynamic transfer model was developed to execute calculation of soft sensing. According to the variation of process parameters, the dynamic temperature field was calculated with the method by tracing slices and substituting slice by slice in the calculation area. In this way, it laid the foundations of soft-sensing.(2)By combining variable step-length method and non-uniform grid, the real time ability is effectively promoted. A method with variable step-length by sections was developed in this thesis, which can largely reduce the amount of calculation of2-D heat transfer model and promote the real-time ability for on-line using. According to the calculation of some field caster, it shows that the absolute time of calculation of one strand can be reduced to.1.5seconds and the max calculation time is1.63seconds, while the sample time is2seconds. And by using a non-uniform grid with boundary tightend, the precision of model can be promoted form no more than.18℃to no more than10℃, which is close to the precision of solution of independent grid with fixed step-length and uniform grid, no more than8℃.(3)According to the characteristics of frequent fluctuation during continuous casting process, a method by combining dynamic calculation and real-time measurement was developed to calibrate the model. And the model shows a good performance in accuracy and reliability after calibration according to the analysis of reliability and the using in different steel grades. Compared with measured result by using a2color infrared thermometer, the accuracy of the calculation model is no more than2%.(4)An application software called NEU-CAST was developed for the soft sensing of billet surface temperature. By applying NEU-CAST. the calculation of billet surface temperature’s soft sensing can be conducted. And an analysis about GCrl5was conducted in some one filed continuous caster.