Capacitance Measurement of Molten Metal Level in Continuous Casting System

The accuracy of molten metal level measurement is the base of controlling the molten metal level, which greatly affects the production quality. Due to the oscillation of the caster mold, hot temperature, and noises in the continuous casting system, the accurate level is hard to obtain. Currently used molten metal level measurement technique includes radioisotope transmission, electromagnetic, ultrasound reflection, microwave reflection, computer vision, and capacitive level measurement method. The radioisotope transmission method has potentially hazardous to exposed workers, while the electromagnetic method needs to maintain the coil frequently for the large excitation source needed, the ultrasound reflection method, micro-wave reflection method and computer vision method can be affected by the casting powder used for preventing molten metal splash. In this work, a new structure of the capacitance sensor designed for minimizing the influence of caster mold's oscillation and improving heat dissipation was proposed, the variation of capacitance between the sensor electrode and the caster mold with molten metal level change and the oscillation of the caster mold was calculated in simulation and validate through a grounded simulation tank with capacitance to digital converter FDC1004. The result shows that the proposed capacitance sensor can achieve an accuracy of 1 mm when the distance between the molten metal surface to the sensor within 80 mm with 2 samples per second report speed.