A new
continuous casting slag detection system with a single coil sensor based on eddy current principle is developed. The
sensor is previously embedded in the sea ting block of a 300t
continuous casting ladle which is the largest in China and arranged to be concentric with the ladle nozzle.One of the major requirements on the system for early slag detection in continuous casting is that of its high detection
sensitivity.When the slag starts to enter the ladle nozzle at the end of each ladle teeming,the system can automatically give a signal to shut off the ladle sliding gate to obtain a maximum steel yield at minimum transfer of slag from ladle to tundish.For the sensor coil operating at a temperature as high as 1000℃,it has to be made of some kind of heat resisting alloy wire so as to have a long lifetime.The detection sensitivity of the system will obviously decreased due to the very low Q value of the sensor coil.A possible solution of this problem is to design a special multiplier circuit to remove the effect of the high resistance of the alloy coil on the detection sensitivity.For the multiplier,it is necessary to improve the wave form of the exciting current source of the sensor coil.The hot tests of the system on line have been carried out and the expectant results obtained. It has been verified that the system with early slag detection function is sa tisfied for the high tonnage continuous casting production.