Research On Infrared Temperature Measurement Technology Of Molten Steel In Complex Environment

With the development of science and technology,the demand for steel in all walks of life is not only increasing,but also the quality requirements are getting higher and higher.Accurately measuring the temperature of molten steel can improve the qualification rate of steel castings and reduce fuel costs,which is an indispensable step to promote the automatic production of steel.At present,infrared temperature measurement technology is usually used to comprehensively monitor the temperature of molten steel in the smelting furnace.However,due to the complex environment of the production site,the working process is affected by various factors such as ambient temperature and humidity,temperature measurement distance,emissivity and dust,which limit the temperature measurement accuracy.Therefore,this thesis will propose an effective temperature compensation method for the main influencing factors to improve the accuracy of infrared temperature measurement.Through the actual inspection of the steel production site,it is found that compared with other influencing factors,the temperature measurement distance and the ambient temperature have the most obvious influence on the infrared temperature measurement accuracy.Therefore,this thesis will conduct a detailed analysis of the influence of temperature measurement distance and ambient temperature.Aiming at the infrared divergence problem caused by the temperature measurement distance,the working principle of the traditional infrared optical system is firstly analyzed,and the optical structure of the common optical path for visual aiming and infrared receiving is improved.The technical parameters of objective lens,field lens,relay lens and eyepiece are given in combination with the optical dimensions.According to the temperature range of molten steel,a reflective filter is designed,which reflects the near-infrared light to the detector and transmits the visible light to the eyepiece.Secondly,for the infrared attenuation problem caused by the temperature measurement distance,software compensation and hardware compensation methods are proposed respectively.Through experiments,the temperature measurement accuracy and temperature measurement field of view are compared,and finally the hardware compensation method is selected.Aiming at the influence of ambient temperature,a variety of temperature calibration methods were compared from the aspects of real-time calibration and calibration accuracy.Finally,the blackbody calibration method was selected for calibration experiments,and the mapping relationship between molten steel temperature and voltage amplitude was obtained.The effects of detector saturation,blackbody gain and circuit magnification on calibration were also analyzed,and a temperature measurement model with high accuracy and wide temperature measurement range was established.Then,on the basis of this model,a thermostated container and a blackbody furnace are used to conduct simulation experiments to find out the influence of ambient temperature on infrared temperature measurement under different blackbody temperatures,and then establish an ambient temperature compensation model.Finally,the optical system and the temperature compensation model are combined to improve the accuracy of infrared temperature measurement and ensure the safety and stability of steel production.In this thesis,the accuracy and stability of the infrared temperature measurement system were tested at the steel production site.The experimental results show that the improved infrared optical system can clearly observe the molten steel position and select the measurement area.And when the infrared temperature measurement system loaded with temperature compensation model measures temperature at different temperature measurement distances and ambient temperatures,the average relative error is less than0.39%.Therefore,the temperature compensation model proposed in this paper can effectively suppress the influence of temperature measurement distance and ambient temperature on the accuracy of infrared temperature measurement,and has important reference value for the study of high-precision infrared temperature measurement technology for molten steel.