Steel casting characterisation: contactless inductive flow tomography and mutual inductance tomography

Monitoring the steel flow through the submerged entry nozzle (SEN) and in the mould during continuous casting presents a challenge for the instrumentation system because of the high temperature environment and the opaqueness of the liquid steel. In this article we describe the development of two complimentary electromagnetic instrumentation systems which are able to visualise the steel flow profile in the SEN by means of Mutual Inductance Tomography (MIT) and the mean 2D/3D flow structure in the mould by means of Contactless Inductive Flow Tomography (CIFT). The flow structure in both sites is crucial for the quality of steel in respect of cleanliness and surface quality. The article will cover the development of both techniques from first principles and initial tests on a scaled (approx. 1:10) laboratory model of the continuous casting process. The experiments were performed with argon gas and GaInSn as an analogue for liquid steel, which has similar conductive properties as molten steel and allows the measurements at room temperature. The article will close with describing hot tests and subsequent plant tests.