Contactless Flow Rate Sensor for Heavy Liquid Metals

Control of the flow rate of liquid metals is required in a number of technological processes such as the cooling of liquid metal cooled nuclear reactors, transmutation systems and the dosing and casting of liquid metals. Electromagnetic flow meters play an important role in the diagnostics and automatic control of such processes in order to measure the integral flow rate in arbitrary pipes and channels with electrically conducting and non-conducting walls. A number of different electromagnetic flow meter designs have been developed starting from the end of the forties of the last century.
Commercial electromagnetic flow meters are typically based on the flow-induced electrical voltage measurements by electrodes in direct contact to the melt in a steady magnetic field. In view of the typical problems coming along with applications at liquid metal flows such as high temperatures, interfacial effects and corrosion, the main disadvantage of this type of flow meter is the electrical contact to the liquid metal, which is necessary to measure the electric potential difference. Therefore, contactless operating measurement techniques are very attractive for liquid metal applications. Such flow rate sensors are based on the flow-induced disturbance of an externally applied AC or DC magnetic field which manifests itself in modified amplitudes of the field, in a modified phase distribution of the field or in a force or momentum exerted on the source of the magnetic field. This work deals with the development of new concepts for contactless operating measurement techniques. A first commercially available prototype will be presented.