Development of a Non-Contact Electromagnetic Surface Velocity Sensor for Molten Metal Flow

摘要

During continuous casting of steel,knowledge of both direction and magnitude of the velocity at the mold surface is of special interest.However,the surface is covered by a non-transparent layer of mold powder to prevent formation of slag.Thus,this meniscus flow cannot be registered by optical measurement techniques.Non-contact measurement methods are of interest.One of such non-invasive techniques is Lorentz_force_veloeimetry(LFV).It is based on measuring the electromagnetically induced force acting on a magnet system.In this paper we present a series of experiments that aim to demonstrate the feasibility of using two identical velocimeters,termed Time-of-Flight LFV(ToF LFV).Using ToF LFV the free-surface velocity may be purely determined by cross-correlating the two force signals delivered by the two force sensors.We have developed a special prototype of such a measuring device termed meniscus velocity sensor(MVS).It has been designed to record local surface velocities in high-temperature metal melts.At Ilmenau University of Technology,the method has been successfully tested using both solid body movement and Ga^(68%)In^(20%)Sn^(12%)as a low-melting model melt.In the present paper we apply this technique to the case of high-temperature metal melts.In more detail,we present test measurements under industry-relevant conditions using both Sn^(32%)pb^(52%)Bi at 210℃and molten steel at about 1700℃.These experiments were conducted at Key Laboratories on EPM at North Eastern University.The evaluation of the data shows that our prototype of MVS works well in producing reproducible signals of which surface velocity can be determined.