A Fast Response Sensor for Continuously Measuring Molten Steel Temperature

Abstract

Response lag is an outstanding problem of the traditional blackbody cavity sensor for continuously measuring the molten steel temperature, which is due to the thick-walled structure of the sensor, caused by the limitation of the sensor’s Al₂O₃–C material in harsh environment. Thus, a fast response sensor with a thin-walled temperature measuring unit of blackbody cavity has been developed. A new sensor material of Mo–W–ZrO₂ cermet that had a small corrosion rate of about 0.05 mm/h was developed for making the thin-walled sensor with a thickness of 3 mm, while the thickness of the traditional sensor was 20–30 mm. The temperature measuring unit of the cermet tube was supported by an Al₂O₃–C unit. In addition, the structure of the fast sensor was designed to form an online blackbody cavity approximately for a high accuracy (measurement error ≤ 3°C) as the sensor was dipped into molten steel, the length/radius ratio of the temperature measuring unit of the cermet tube should reach 12. Industrial test showed that the fast sensor improved the response speed significantly from 5–6 min to about 55 s. It was helpful to solve the problem for continuously measuring the molten steel temperature of these fields that needed a fast response.