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Liquid metals, such as sodium, have been already successfully used as heat transfer fluids (HTF) in concentrating solar power (CSP) plants up to ~550 °C. Even higher temperatures can be achieved and are envisioned for future CSP plants. The lack of measuring flow rate devices at high temperatures for liquid metals motivated this study. The present paper presents the experimental mock-up and the experimental results obtained with the SOLTEC-2 facility for two test flow sensors, one innovative eddy current flow sensor (ECFM) developed at HZDR, Germany and a built-in permanent magnet fly-wheel sensor for runs up to a sodium temperature of 700 °C. The signals of the sensors are compared also against the power level of the sodium pump.

Measuring the flow velocity of liquid metals is a challenging task due to their high temperatures, their opacity and in many cases their chemical reactivity. There are several inductive methods to measure the flow velocity of liquid metals such as contactless inductive flow tomography (CIFT) [1], the magnetic distortion probe [2], Lorentz force velocimetry [3], the phase shift sensor [4] and eddy current flow meters (ECFM)[5]. ECFMs are often used in liquid metal fast breeder reactors due to their reliability and simple design. A disadvantage of the ECFM is that its output signal is influenced not only by changes in the flow velocity, but also by the electrical conductivity of the liquid metal, which depends on its temperature. Therefore, the ECFM must be calibrated according to the expected range of flow velocities and temperatures of a particular application, while simultaneously determining the temperature to distinguish between velocity and temperature changes. To solve this problem, we propose a new measurement method [6] that allows the simultaneous measurement of flow velocity and electrical conductivity by creating a so-called look-up table (LuT).

The present study presents the experimental measurements of the sodium flow rate in the KASOLA (KArlsruhe SOdium LAboratory) and SOLTEC-2 (SOdium Loop for TEst materials and Corrosion) facilities available at KIT. KASOLA facility is a versatile sodium facility designed for thermal-hydraulic experiments and tests of components at prototypical and industrial scale [1]. The facility has a sodium inventory of 7 m3 and can be operated up to a temperature of 550°C at an overpressure of 2.5 bar. The maximal flow rate is specified at 150 m3/h, which can be achieved with a 75 kW annular linear induction pump. The sodium flow rate measurements have been performed using a Coriolis flowmeter, which has been used as reference for the calibration of a magnetic flow meter. The influence of the temperature field has been considered in the determination of the flow rate curve for the magnetic flow rate sensor. SOLTEC-2 facility is a 720 °C high temperature sodium loop currently used for experimental investigations of sodium corrosion on high temperature steels. The facility has a sodium inventory of ~14 L and it was operated up to 720 °C at an overpressure of 2.5 bar. The maximal mass flow rate specified is 300 kg/h. An innovative eddy current flowmeter (ECFM) sensor developed at HZDR, Dresden [2] has been installed in the high temperature side and operated in the SOLTEC loop. Successful measurements have been performed up to 700 °C, which to our knowledge represent so far a worldwide premiere. A comparison has been made between the results generated by the ECFM sensor with the experimental data delivered by the magnetic fly-wheel that is installed in the low temperature side of the loop. The study discusses the experience gained and the differences between these two flow rate sensors.

We present measurement results for the flow rate of liquid sodium at temperatures up to 700 °C that were obtained with a high temperature prototype of an immersed Eddy Current Flow Meter. The experimental campaign was conducted at the SOLTEC-2 sodium loop at KIT. The main objective of the experiments is the high temperature qualification of the Eddy Current Flow Meter as part of the safety instrumentation of generation IV liquid metal cooled fast reactors. There it is intended to be used for monitoring the flow rate of the coolant and to detect possible blockages of sub assemblies. Due to the large liquid metal volume, the sensor has to be located close to the sub assemblies, therefore measurements from outside of the vessel are not possible and an immersed sensor is required. We demonstrate the successful application of the immersed Eddy Current Flow Meter at such high temperatures and identify the relevant effects with impact on the sensor performance.

Eddy Current Flow Meters (ECFM) are inductive sensors that are commonly used to measure the local flow rate or flow velocity of liquid metals in the vicinity of the sensor. One disadvantage of the ECFM is, that the measured voltage signals depend on the magnetic Reynolds number i.e. they are not only depending on the flow velocity but also on the electrical conductivity of the liquid metal. For applications where the temperature (and therefore also the electrical conductivity) is fluctuating significantly, the ECFM has to be calibrated in order to be able to distinguish between the influence of the flow velocity and the temperature on the measured signals. In this paper we present a method that allows the simultaneous measurement of electrical conductivity and flow velocity by using a so called Look-Up-Table method. When using this method, there is no need to calibrate the ECFM.

The Eddy Current Flow Meter is an inductive flow rate sensor which can be used in many liquid metal applications and is well suited for operation in liquid metal cooled fast reactors. There it can be used as part of the safety instrumentation in order to detect a loss of flow in the reactor core. To further qualify the Eddy Current Flow Meter for use in liquid metal cooled reactors, measurements with a high temperature prototype of the sensor have been performed at the sodium loop SUPERFENNEC for sodium temperatures between 200 °C and 300 °C and flow velocities of up to 2.5 m/s. By measuring the magnitude or phase shift of the output voltage of the sensor, the flow rate or velocity of the liquid sodium in a certain volume around the sensor can be determined. Depending on the frequency of the excitation current, the sensitivity of the sensor is changing. Therefore, measurement results for different frequencies and temperatures are presented as well as the results of a frequency sweep for determining the optimal excitation frequency of the sensor.

The Eddy Current Flow Meter is an inductive velocity sensor which can be used in liquid metal applications, such as liquid metal cooled fast reactors. There it can be used as part of the safety instrumentation in order to monitor the coolant flow through subassemblies under normal operating conditions or to detect and locate blockages in case of a local freezing of the coolant. Typically the Eddy Current Flow Meter is used in pipe flows where the flow is mostly parallel to the sensor axis, whereas the flow angle may change significantly above subassemblies in a liquid metal cooled reactor. In the first part, the paper therefore deals with investigating the influence of varying flow angles on the performance of the Eddy Current Flow Meter. By performing measurements in a model experiment, the effect of different flow angles on the measured velocities will be demonstrated. In the second part of the paper, multiple Eddy Current Flow Meters in an array are used to detect and locate blockages in an array of seven subassemblies in the same model experiment. All experiments are carried out at room temperature with a liquid alloy of gallium, indium and tin.

The Eddy Current Flow Meter is a reliable and robust inductive sensor for the measurement of flowrates in liquid metal flows. This kind of sensor is usually being used in pipe flows where the flow is mostly parallel to the sensor axis. When this sensor is used as part of the safety instrumentation above the subassemblies in liquid metal cooled fast reactors, the flow angle may change rapidly according to the conditions within the reactor. In this paper we investigate the performance of the Eddy Current Flow Meter in flows inclined to the sensor axis by numerical simulations as well as model experiments. We demonstrate that the Eddy Current Flow Meter yields reliable results for flow angles up to 30° while the sensitivity of the sensor is significantly reduced for larger angles.

The determination of the magnesium level in a titanium reduction retort by inductive methods is often hampered by the formation of titanium sponge rings which disturb the propagation of electromagnetic signals between excitation and receiver coils. We present a new method for the reliable identification of the magnesium level which explicitly takes into account the presence of sponge rings with unknown geometry and conductivity. The resulting inverse problem is solved by a look-up-table method, based on the solution of the inductive forward problems for several tens thousands of parameter combinations. The feasibility of that method is demonstrated by performing numerical simulations and measurements on a model experiment. This method is not limited to the production of titanium but can also be applied to other applications in metal production and processing.

In order to determine the magnesium level in a titanium reduction retort by inductive methods, many interfering influences have to be considered to achieve precise measurement results. By using a look-up-table method, the magnesium level can be identified while taking into account the interfering effects of titanium sponge rings that are forming at the walls of the retort during the reduction process with their unknown geometrical and electrical parameters. This new method uses a combination of numerical simulations and measurements, whereby the simulation model is calibrated so that it represents the experimental setup as closely as possible. Previously we have presented purely theoretical studies on this method. Here, we demonstrate the practical feasibility of that method by performing measurements on a model experiment. This method is not limited to the production of titanium but can also be applied to other applications in metal production and processing.

Eddy Current Flow Meters (ECFM) are inductive sensors that are commonly used to measure the local flow rate or flow velocity of liquid metals in the vicinity of the sensor. One disadvantage of the ECFM is, that the measured voltage signals depend on the magnetic Reynolds number i.e. they are not only depending on the flow velocity but also on the electrical conductivity of the liquid metal. For applications where the temperature (and therefore also the electrical conductivity) is fluctuating significantly, the ECFM has to be calibrated in order to be able to distinguish between the influence of the flow velocity and the temperature on the measured signals. In this paper we present a method that allows the simultaneous measurement of electrical conductivity and flow velocity by using a so called Look-Up-Table method. When using this method, there is no need to calibrate the ECFM.

An overview of current research on inductive level measurement techniques in liquid metals at the HZDR.

Eddy Current Flow Meters (ECFM) are inductive sensors that are commonly used to measure the local flow rate or flow velocity of liquid metals in the vicinity of the sensor. One disadvantage of the ECFM is, that the measured voltage signals depend on the magnetic Reynolds number i.e. they are not only depending on the flow velocity but also on the electrical conductivity of the liquid metal. For applications where the temperature (and therefore also the electrical conductivity) is fluctuating significantly, the ECFM has to be calibrated in order to be able to distinguish between the influence of the flow velocity and the temperature on the measured signals. In this paper we present a method that allows the simultaneous measurement of electrical conductivity and flow velocity by using a so called Look-Up-Table method. When using this method, there is no need to calibrate the ECFM.

FIELD: metallurgy. SUBSTANCE: invention relates to the metallurgy industry. Magnesium level and the skull characteristics in the titanium reduction reactor determining method, based on the EMF measurements in the receiving coil, induced by the electromagnetic field from located around the retort the exciting windings set, contains the steps, on which for the determination currents of different frequencies are used, at that, first, by the electrodynamics equations numerical solving, developing the reference base of the EMF calculated values in the located above the reactor receiving coil, with the molten magnesium different specified levels, different titanium skull given positions and sizes for the supply current given set of frequencies in the range of 1–50 Hz, and then, in the process of titanium reduction, with the same set of current parameters in the excitation coils, measuring the EMF values in the receiving coil, which are compared with the reference ones, and the least standard deviation is determined by the smallest standard deviation method, and the molten magnesium level, the titanium skull position and size are judged by it. EFFECT: increase in the molten metal level determining accuracy and the expansion in the method possibilities. 5 cl, 13 dwg

The inductive measurement of the magnesium level in a titanium reduction reactor is a challenging task because the state of the art measurement techniques are hampered by the formation of titanium sponge rings within the reactor. By distorting the magnetic field between excitation and sensor coils, which is used to determine the magnesium level, these rings lead to a considerable measurement error. We present a novel approach to magnesium level detection using the existing infrastructure of the titanium reduction reactor, while considering the unknown size, position and electrical conductivity of the titanium sponge ring. Based on numerical simulations, we demonstrate how to solve the resulting inverse problem by applying a look-up-table method comprising tens of thousands of pre-calculated parameter combinations.

The determination of the Magnesium level in a Titanium reduction retort by inductive methods is often hampered by the formation of Titanium sponge rings which disturb the propagation of electromagnetic signals between excitation and receiver coils. We present a new method for the reliable identification of the Magnesium level which explicitly takes into account the presence of sponge rings with unknown geometry and conductivity. The inverse problem is solved by a look-up-table method, based on the solution of the inductive forward problems for several tens of thousands parameter combinations.

Instrumentation for Liquid Metal Facilities an overview and present work

Eddy current flow meters (ECFM) are widely used for measuring the flow velocity of electrically conducting fluids. Since the flow induced perturbations of a magnetic field depend both on the geometry and the conductivity of the fluid, extensive calibration is needed to get accurate results. Transient eddy current flow metering (TECFM) has been developed to overcome this problem. It relies on tracking the position of an impressed eddy current system which is moving with the same velocity as the conductive fluid. We present an immersed version of this measurement technique and demonstrate its viability by numerical simulations and a first experimental validation.

In this talk a short overview about recent developments of measurement techniques for liquid metal with special focus on liquid metal cooled nuclear reactors is given.

Eddy current flow meters (ECFM) are widely used for measuring the flow velocity of electrically conducting fluids. Since the flow induced perturbations of a magnetic field depend both on the geometry and the conductivity of the fluid, extensive calibration is needed to get accurate results. Transient eddy current flow metering (TECFM) has been developed to overcome this problem. It relies on tracking the position of an impressed eddy current system which is moving with the same velocity as the conductive fluid. We present an immersed version of this measurement technique and demonstrate its viability by numerical simulations and a first experimental validation.