Design Of A Portable Verification Device For Continuous Temperature Measurements System For Molten Steel Based On Blackbody Cavity

On the process of steelmaking and continuous casting, the temperature of the molten steel is the main factor which affects the quality of steel products and achieves a closed-loop control. A continuous temperature measurement system of molten steel based on the theory of blackbody cavity, realizes continuous temperature measurement of molten steel in tundish. To get the accurate result on the course of the temperature measurement system, it needs the verification device to test the temperature measurement system periodically. At present, most of the industrial radiation thermometers are tested by the blackbody furnace and standard tungsten strip light. However, due to the restriction of bulkiness, high power consumption, slow heating, poor earthquake-proof; it is impossible to put them into industrial field use.In this paper, considering the limitations in verification continuous temperature measurement system of molten steel based on the theory of blackbody cavity with blackbody furnace or standard tungsten strip light, according to the principle of radiation thermometry, a new verification device using IR LED as the radiation source is introduced. The verification device has lithium powered-battery, small in size, low power consumption, good repeatability and has a good prospect.First, continuous temperature measurement system of molten steel based on the theory of blackbody cavity is discussed in details, the verification system and device of radiation thermometer is introduced. Spectral characteristics for types of LEDs are achieved using the spectrometer and choosing the best one based on the characteristics of photoelectric sensor; designing a portable verification device optical structure and mechanical structure based on the basic theory of blackbody radiation. Designing a high-precision constant current source with an automatic temperature compensation function based on the optical and electrical characteristics of LED. High-capacity rechargeable lithium battery is introduced to power the device. In the end, a relationship between LED radiation intensity, current, and voltage across the PN junction and the ambient temperature is established.Based on the experiments, repeatability, stability and expanded uncertainty of the device is evaluated and the expanded uncertainty for 1100℃ is 2.72℃. This expanded uncertainty is lower than maximum uncertainty requirement. The verification device is of low cost, simple structure, easy to operate, fast in testing to meet the production needs of the iron and steel enterprises, improve economic efficiency and has a good marketing value.