Real-time surface temperature measurement of steel continuous casting strand in the steam-filled spray chamber

Accurate measuring strand surface temperature inside the steam-filled spray chamber in steel continuous casting process is important to realize closed-loop control of secondary cooling water and minimize surface cracks. However, the accuracy of radiation temperature measurement is greatly affected by the harsh environment in the steam-filled spray chamber, such as highly concentrated water vapor, water spray, intermittent water film and oxide scale layers on the surface. In this paper, a real-time temperature measurement system was specifically designed for detailed, accurate and reliable monitoring the strand surface temperature in the steam-filled spray chamber and had been implemented on commercial casters. In this system, a linear extrapolation method was applied to correct the effect of highly concentrated water vapor. The optimal combination of air flowrate and distance of sighting tube away from strand surface was chosen to simultaneously achieve the purposes of completely purging water spray and avoiding the overcooling of strand surface. A peak-picking method was employed to mitigate the effects of discontinuous water film and oxide scale layers. Comparison of the measured temperatures with temperature predictions using continuous casting simulation models illustrated the high accuracy of temperature measurements using this system. The test results in steel factories demonstrated the proposed temperature measurement system could meet the requirement of strand surface temperature measurements. Reliability and accuracy of measurement results were discussed.