Permanent Magnet Flowmeter Research Articles

A novel Halbach array permanent magnet flowmeter for liquid metal flow measurement. Part Ⅱ: Impact of velocity distribution on measurement signals and optimization design for electrodes

In this paper, the principles of Halbach array permanent magnet flowmeter (HA-PMFM) in reducing the sensitivity of measurement signals to velocity distribution by using arc-shaped electrodes and multi-electrodes, respectively, are analyzed. The impact laws of disturbance amplitudes of three velocity distribution forms (waterfall, skewed, and blockage types) on the measurement signals acquired by HA-PMFM with point electrodes, arc-shaped electrodes, and multiple electrodes, respectively, were investigated by COMSOL Multiphysics software. The results show that, in comparison to HA-PMFM with point electrodes, HA-PMFM with arc-shaped electrodes mitigates the unevenness of the weight function from 0.68 to 0.12. Under strong velocity distribution disturbances at constant flow velocity, optimized arc-shaped electrodes can reduce the measurement error from a maximum of 15 % to within 7 %, and multi- electrodes can reduce the measurement error from a maximum of 15 % to within 5 % compared to the point electrodes. However, when the uniform incoming flow rate is varied, the optimized arc-shaped electrodes can reduce the measurement error from 2 % to within 1 %, and the multi-electrodes can reduce the error from 2 % to within 1.5 %. This study offers valuable insights for enhancing the measurement accuracy of HA-PMFM in engineering applications and provides guidance for the design of liquid metal electromagnetic flowmeters in various fields, particularly for those compact systems using liquid metal as flow medium in which the flowmeter has to be installed on the flow passage with strongly distorted velocity distribution.

High Temperature Sodium Submersible Flowmeter Design and Analysis

This work details the design and analysis of a permanent magnet flowmeter designed to be submerged in a pool type sodium fast reactor environment. Recently developed Samarium Cobalt rare earth magnets were utilized that have demonstrated resilience to temperature and neutron flux up to 550 °C and 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">18</sup> n/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , respectively. This paper will discuss the theory, design, calibration and uncertainty quantification of the flowmeter. The flowmeter was calibrated over a flowrate range of 11.4 - 90.9 LPM at temperatures of 220 and 400 °C, yielding an uncertainty in calibration of 2-3.6%. A finite element model was developed and validated experimentally, yielding <; 3.2% error.

Sodium flow measurement in large pipelines of sodium cooled fast breeder reactors with bypass type flow meters

Liquid sodium flow through the pipelines of sodium cooled fast breeder reactor circuits are measured using electromagnetic flow meters. Bypass type flow meter with a permanent magnet flow meter as sensor in the bypass line is selected for the flow measurement in the 800NB main secondary pipe line of 500MWe Prototype Fast Breeder Reactor (PFBR), which is at the advanced stage of construction at Kalpakkam. For increasing the sensitivity of bypass flow meters in future SFRs, alternative bypass geometry was considered. The performance enhancement of the proposed geometry was evaluated by experimental and numerical methods using scaled down models. From the studies it is observed that the new configuration increases the sensitivity of bypass flow meter system by around 70%. Using experimentally validated numerical tools the volumetric flow ratio for the bypass configurations is established for the operating range of Reynolds numbers.

Numerical evaluation of SmCo permanent magnet flowmeter measuring sodium flow in a low flow rate regime using FLUENT/MHD module

One of the several key subsystems in the test facility of Korean sodium-cooled fast reactor is a plugging meter system, which measures the impurities in the sodium using an indirect online technique. To measure the low flow rate, a permanent magnet flowmeter was developed owing to its inherent fast response time, non-invasive characteristic, relatively accurate flow rate measurements, and excellent linearity between the flow rate and flowmeter signal. However, several limitations have been reported in the experimental evaluation of the flowmeter under low flow rate conditions given the measurement capability of the current experimental facility. Thus, the performance of the flowmeter was evaluated numerically using a commercial computational fluid dynamics tool, a FLUENT/MHD module, based on the finite volume method with the help of electromagnetic analysis software, ANSYS MAXWELL. The FLUENT/MHD module was validated by comparing the simulation results with the experimental results. The relative error of the FLUENT simulation was estimated to be approximately 0.24% compared with the experimental results. After the validation process, MHD simulations were conducted to calculate the flowmeter voltage signals versus flow rates, especially in a low flow rate regime, where the linearity between the flow rate and flowmeter signal was carefully analyzed.

Development of side wall type permanent magnet flowmeter for sodium flow measurement in large pipes of SFRs

Sodium cooled Fast Reactors (SFR) require measurement of liquid sodium flow in its primary and secondary circuits. For the primary system of the pool type concept of SFR design, flowmeters have to be immersed in sodium pool and require flow sensors which can withstand high temperatures up to 550°C, nuclear radiation and chemically reactive sodium environment. Secondary circuits and safety grade decay heat removal (SGDHR) circuits of SFR need flow measurement in stainless steel (SS) pipes of diameter varying from 15mm to 800mm. For small pipes, flowmeters with permanent magnet flowmeter with ALNICO-V magnet assembly is the unanimous choice. Conventional permanent magnet flowmeters (PMFM) for large pipelines become bulky, heavy and have installation problems. For sodium flow measurement in large pipelines a few other alternate methods are considered. In the case of Prototype Fast Breeder Reactor (PFBR), which is at an advanced stage of construction at Kalpakkam, flow in the 800mm diameter secondary main circuit is measured by means of a bypass flowmeter. Other sensors that could be deployed include eddy current flowmeters (ECFM), which are introduced into the pipe to measure flow velocity in the pipe, ultrasonic flowmeters and permanent magnet based side wall flowmeters. In permanent magnet based side wall flowmeter (SWFM), a permanent magnet block is mounted on one side of the large pipe and the magnetic field produced by the magnet penetrates through the pipe and interacts with the flowing sodium and induces an electro motive force (emf) proportional to the flow. This is a compact, cost effective and fairly accurate method for flow measurement in large pipelines of SFR circuits. SWFM is suitable for pipelines of 100mm and above. In the present work a side wall flowmeter for 100mm pipe is designed, manufactured, calibrated and tested in an existing sodium facility. Voltage signal developed in SWFM for different flowrates was simulated with three dimensional Finite Element Model (FEM) and validated with experimental results. Effect of asymmetric magnetic field on flowmeter voltage signal and dependence of flowmeter voltage signal on position of electrodes was also analyzed with model. The feasibility of use of this type of flowmeter for large pipelines of SFRs is demonstrated.

Design and development of samarium cobalt based permanent magnet flow meter for 100 NB pipe in sodium circuits

Liquid sodium is used as coolant in sodium cooled fast reactors (SFR) due to its favorable nuclear properties and excellent heat transfer properties. Good electrical conductivity of sodium is effectively utilized for measurement of flow in primary and secondary circuits of the reactor. Alnico-V based permanent magnet flow meters (PMFM) are used to measure the flow of liquid sodium in stainless steel (SS) pipes of diameter ranging from 15NB (Nominal Bore) to 800NB. These PMFMs become bulky and heavy and are less sensitive for flow measurement in large pipes with diameter above 100NB. To increase the sensitivity and reduce the weight, a new PMFM suitable for 100NB pipe is designed and developed with SmCo magnet. The performance of SmCo based flow meter is evaluated experimentally in an existing sodium loop by varying sodium temperature and flow rate. Overall weight and sensitivity of the new design is compared with Alnico-V flow meters. Three dimensional Finite Element Modeling (FEM) is carried out to establish, modeling as an alternate method for calibration. In modeling and simulation, magnetic field distribution across the flow meter pipe and its effects on flow meter voltage signals are analyzed. The effect of sodium temperature on flow meter voltage signal and its variation with change in sodium flow rate are predicted by modeling and compared with experimental results.

Stabilization of magnet assemblies of permanent magnet sodium flowmeters used in fast breeder reactors

Permanent magnet flow meters (PMFMs) are used to measure the sodium flow in sodium cooled Fast Breeder Reactor Circuits. Prototype fast breeder reactor (PFBR) which is under construction at Kalpakkam is a 500MWe, sodium cooled, pool type reactor. Sodium flow measurement in various loops of the reactor is of prime importance from operational and safety point of view. To measure the flow of electrically conducting liquid sodium, in primary and secondary circuit pipe lines of PFBR, permanent magnet flow meters are used. PMFM is a non-invasive device, which works on the principle of generation of motional EMF by magnetic forces exerted on the charges in a moving conductor. Flowmeters of different pipe sizes ranging from 10mm to 200mm pipe diameter are required for PFBR. Long term performance of the flowmeters mainly depends on stability of permanent magnets used in flowmeters to generate constant magnetic field in stainless steel (SS) pipes. This paper describes the effects of time and temperature on permanent magnet assemblies made of ALNICO-V used in PFBR flowmeters. The stabilization methodology for ALNICO-V permanent magnet assemblies is evolved and established. Loss of magnetic field strength with respect to time and temperatures is determined by experiments and found negligible.

Modelling of induction rotary permanent magnet flowmeters for liquid metal flow control

Modelling of induction rotary permanent magnet flowmeters for liquid metal flow control

In-situ calibration of permanent magnet flow meters in PFBR using noise analysis technique

In Fast Breeder Reactor sodium circuits, permanent magnet flow meters (PMFM) are extensively used to measure the liquid sodium flow rate. The performance of PMFM can degrade with respect to time due to various reasons. This degradation results in reduction in output voltage and affects flow meter stability. The distortion of the magnetic field in the large diameter flow meters makes its characteristics nonlinear. Further, the performance of the flow meter is also affected by vibrations, shocks, temperature and change of reluctance within the magnetic circuit. Hence, it is desirable to calibrate the PMFM at periodic time intervals for ensuring accuracy and stability. However, it is very difficult and almost impossible to calibrate large size flow meters once installed in the system under actual flow conditions in a sodium test loop. Therefore, it is necessary to calibrate the flow meter in-situ without disturbing its normal operating conditions.Experiments were carried out in different sodium loops in Fast Reactor Technology Group (FRTG) and Fast Breeder Test Reactor (FBTR) with permanent magnet flow meters of different sizes to develop an in-situ calibration procedure. Cross-correlation technique is studied and the flow rate is estimated from the transit time with a deviation of ±5.5%, which is comparable with that of calibration of the flow meter in actual sodium test loop. In this paper, in-situ calibration of PMFM is discussed with experimental details, data acquisition, cross-correlation technique and the results obtained.

Modeling of permanent magnet flowmeter for voltage signal estimation and its experimental verification

Prototype Fast Breeder Reactor (PFBR) is a 500MWe, sodium cooled, pool type, mixed oxide (MOX) fueled reactor. Sodium flow measurement in various loops of the reactor is of prime importance from the operational and safety aspects. To measure the flow of electrically conducting liquid sodium in secondary circuits, permanent magnet flowmeters (PMFMs) made up of ALNICO-5 are used in Fast Breeder Test Reactor (FBTR), PFBR and existing sodium loops in Indira Gandhi Centre for Atomic Research (IGCAR). PMFM made up of ALNICO-5 are bulky and heavy, hence to reduce size of flowmeter a PMFM made up of Samarium Cobalt (SmCo) is designed and calibrated in existing sodium loop. Calibration of flowmeter requires dedicated sodium rig with pipe sizes of same dimension as flowmeter pipe, which needs modification in existing system. As an alternate method of sodium calibration, three dimensional Finite Element Modeling of SmCo PMFM is done for its voltage signal prediction. In simulation magnetic field distribution across the flowmeter pipe and effect of sodium flow on magnetic field are analyzed. Effect of sodium temperature on flowmeter voltage signal and its change with change in sodium flow rate is predicted with modeling and compared with experimental tests conducted for use of PMFM.

Development and Testing of PM Flowmeter with Samarium Cobalt Magnet Assembly

Abstract Permanent Magnet Flow Meter (PMFM) made with ALNICO-5 magnet is presently used for measuring flow in sodium circuits. These flowmeters are heavy, bulky and occupies more space in the plant mainly because of the large size of the magnet assembly. Rare earth permanent magnet material like Samarium Cobalt (SmCo) is having higher coercivity and energy product than ALNICO-5. A PMFM suitable for 20 NB pipe was designed and manufactured using SmCo magnet assembly. The magnetic flux density obtained at the center of air gap was 60% higher than the flux density of ALNICO-5 assembly of nearly same size. The 20 NB size PMFM with SmCo magnet assembly was calibrated in sodium against a reference PMFM in 500 kW sodium loop. Calibration runs were conducted at different temperatures of 300 C, 400 C and 500 C and at different flow rates. Sensitivity of the SmCo PMFM was found to be 3.4 mV/m3/h compared to 2.1 mV/m3/h as that of ALNICO-5 PMFM. Two SmCo magnet assemblies from the same lot were used for stability testing of the magnet. Long term stability of the magnet assembly at operating temperature was tested by keeping the magnet assembly in the furnace at 100 °C for 5000 hours and was observed that flux density remains steady. Accelerated long term stability test at 200 °C for 5000 hours was also completed and found that no significant reduction in flux density. The results shows that stability of the magnet with time and temperature is found to be good. Hence the feasibility of manufacturing PM flowmeters suitable for high temperature sodium flow measurement with SmCo magnet assembly was demonstrated. These types of flow meters will be compact compared to ALNICO-5 flowmeters if designed for same sensitivity and can be deployed in future Fast reactors. This paper gives the details of Samarium cobalt flowmeter, sensitivity estimate, stability testing and sodium test results.

Development, computer simulation and performance testing in sodium of an eddy current flowmeter

Abstract Sodium is used as a coolant in Liquid Metal Fast Breeder Reactor (LMFBR). Sodium flow measurement is of prime importance both from the operational and safety aspects of a fast reactor. Various types of flowmeters namely permanent magnet, saddle type and eddy current flowmeters are used in FBRs. From the safety point of view flow through the core should be assured under all operating conditions. This requires a flow sensor which can withstand the high temperature sodium environment and can meet the dimensional constraints and be amenable to maintenance. Eddy current flowmeter (ECFM) is one such device which meets these requirements. It is meant for measuring flow in PFBR primary pump and also at the outlets of the fuel sub-assemblies to detect flow blockage. A simulation model of ECFM was made and output of ECFM was predicted for various flowrates and temperatures. The simulation model was validated by testing in a sodium loop. This paper deals with the design, simulation and tests conducted in sodium for the eddy current flowmeter for use in the Prototype Fast Breeder Reactor (PFBR).

J. Materials Science: R.G. O'Dennell et al (Materials Research Laboratories, Australia) Vol 27, No 23, 1992, 6490–6494

Prototype Fast Breeder Reactor (PFBR) is a 500 MWe, sodium cooled, pool type, mixed oxide (MOX) fueled reactor. Sodium flow measurement in various loops of the reactor is of prime importance from the operational and safety aspects. To measure the flow of electrically conducting liquid sodium in secondary circuits, permanent magnet flowmeters (PMFMs) made up of ALNICO-5 are used in Fast Breeder Test Reactor (FBTR), PFBR and existing sodium loops in Indira Gandhi Centre for Atomic Research (IGCAR). PMFM made up of ALNICO-5 are bulky and heavy, hence to reduce size of flowmeter a PMFM made up of Samarium Cobalt (SmCo) is designed and calibrated in existing sodium loop. Calibration of flowmeter requires dedicated sodium rig with pipe sizes of same dimension as flowmeter pipe, which needs modification in existing system. As an alternate method of sodium calibration, three dimensional Finite Element Modeling of SmCo PMFM is done for its voltage signal prediction. In simulation magnetic field distribution across the flowmeter pipe and effect of sodium flow on magnetic field are analyzed. Effect of sodium temperature on flowmeter voltage signal and its change with change in sodium flow rate is predicted with modeling and compared with experimental tests conducted for use of PMFM.

J. Magnetism and Magnetic Materials: P.G. McCormick et al (University of Western Australia, Australia) Vol 116, No 3, 1992, L320–L324

Prototype Fast Breeder Reactor (PFBR) is a 500 MWe, sodium cooled, pool type, mixed oxide (MOX) fueled reactor. Sodium flow measurement in various loops of the reactor is of prime importance from the operational and safety aspects. To measure the flow of electrically conducting liquid sodium in secondary circuits, permanent magnet flowmeters (PMFMs) made up of ALNICO-5 are used in Fast Breeder Test Reactor (FBTR), PFBR and existing sodium loops in Indira Gandhi Centre for Atomic Research (IGCAR). PMFM made up of ALNICO-5 are bulky and heavy, hence to reduce size of flowmeter a PMFM made up of Samarium Cobalt (SmCo) is designed and calibrated in existing sodium loop. Calibration of flowmeter requires dedicated sodium rig with pipe sizes of same dimension as flowmeter pipe, which needs modification in existing system. As an alternate method of sodium calibration, three dimensional Finite Element Modeling of SmCo PMFM is done for its voltage signal prediction. In simulation magnetic field distribution across the flowmeter pipe and effect of sodium flow on magnetic field are analyzed. Effect of sodium temperature on flowmeter voltage signal and its change with change in sodium flow rate is predicted with modeling and compared with experimental tests conducted for use of PMFM.

Calibration of a miniature permanent magnet flowmeter probe and its application to velocity measurements in liquid sodium

The calibration of a miniature permanent magnet flowmeter probe (MPMF probe) for velocity measurements in liquid metals, such as sodium, and its use in performing velocity measurements are discussed. Velocity measurements were made in a vertical axisymmetric and nonisothermal jet flow, the jet having an initial densimetric Froude number of 521. The jet discharged into a weakly turbulent, coflowing ambient with a Reynolds number of 14 × 10 3. The physical principle of the MPMF probe is the induction law. The electric signals of the probe are proportional to the flow velocity if an electrically conducting fluid passes a constant magnetic field perpendicular to the flow direction. The magnetic field is produced by a miniature permanent magnet inside the probe. Furthermore, a thermoelectric or Seebeck potential influences the probe signals if a temperature field is superimposed on the velocity field. In addition, in the presence of temperature gradients, inhomogeneities in the electrode wires of the probe can generate potentials that are an important source of error. In this paper, a new temperature compensation method of the probe signals is demonstrated that can eliminate these influences. The calibration method and two different velocity measurement methods are described in detail. The sensitivity of the probe is determined. Finally, the velocity data for the sodium jet are compared with data from the literature that are obtained in fluids of common Prandtl number, such as water or gases.

Turbulent convection in buoyant sodium jets

Low Prandtl number convection is investigated in vertical axisymmetric turbulent buoyant jets of sodium discharging into a slowly moving ambient. Measurements of mean velocity and mean temperature profiles are performed. By varying the ratio of momentum to buoyancy flux, that is, the densimetric Froude number, different intensities of buoyancy are obtained. The mixed convection flow is compared with forced convection and plume flow. Using a recently developed temperature-compensated miniature permanent magnet flowmeter probe, Gaussian profiles of velocity and temperature are obtained that are independent of the flow regime at all axial measuring positions. The axial decay of the centerline mean velocity for sodium is the same as for fluids of higher Prandtl number. It shows power laws with powers of −1 for forced convection, −2 3 for a transition region, and −1 3 for plumes. The centerline mean temperature for sodium and a plume decreases with power −1, which is in contrast to the −5 3 decay for plumes and fluids of higher Prandtl number. The results of the sodium experiments are compared with data for water and air flows from the literature.

A Signal Analysis Method Using Cross-Correlation of Turbulence Flow Signals to Determine Calibration of Permanent Magnet Sodium Flowmeters

Permanent magnet flowmeters are used to measure flow in sodium cooled power plants both in the core and in plant piping. In this paper the cross-correlation technique and in particular the transfer function method is used to process the flow turbulence signals from electrodes spaced along the pipe in the vicinity of the magnetic field. Results from a loop flowmeter the EBR-II secondary flowmeter and a 400 mm diameter flowmeter will be presented.

Instruments for measuring pressures, flow rates and levels of molten alkali metals

The construction, design and operation of instruments for pressure, flow and level measurements on liquid metals are discussed. Such instruments are used in reactors with liquid metal coolants. The authors' investigations have shown that the most reliable instruments for these purposes are the two-bellows pressure gauge with an intermediate separating liquid, the permanent magnet flowmeter and the ultra-short wave and potentiometric level indicators. Their construction is simple and they are accurate enough for practical purposes.

Zero Error in Induction Flowmeters Employing a Permanent Magnet

A source of zero error in permanent magnet flowmeters is discussed. The error results from a redistribution of the potential produced at any earthed electrode connected to an experimental animal. It can occur when the blood vessel or connecting tubes are clamped to obtain a baseline of zero flow, and can be eliminated by using matched electrodes of low impedance, together with an amplifier employing matched input circuits of high impedance.

Localised penetrating corrosion of a sintered aluminium powder alloy in high temperature steam

Permanent Magnet Flow Meter (PMFM) made with ALNICO-5 magnet is presently used for measuring flow in sodium circuits. These flowmeters are heavy, bulky and occupies more space in the plant mainly because of the large size of the magnet assembly. Rare earth permanent magnet material like Samarium Cobalt (SmCo) is having higher coercivity and energy product than ALNICO-5. A PMFM suitable for 20 NB pipe was designed and manufactured using SmCo magnet assembly. The magnetic flux density obtained at the center of air gap was 60% higher than the flux density of ALNICO-5 assembly of nearly same size. The 20 NB size PMFM with SmCo magnet assembly was calibrated in sodium against a reference PMFM in 500 kW sodium loop. Calibration runs were conducted at different temperatures of 300 C, 400 C and 500 C and at different flow rates. Sensitivity of the SmCo PMFM was found to be 3.4 mV/m3/h compared to 2.1 mV/m3/h as that of ALNICO-5 PMFM. Two SmCo magnet assemblies from the same lot were used for stability testing of the magnet. Long term stability of the magnet assembly at operating temperature was tested by keeping the magnet assembly in the furnace at 100 °C for 5000 hours and was observed that flux density remains steady. Accelerated long term stability test at 200 °C for 5000 hours was also completed and found that no significant reduction in flux density. The results shows that stability of the magnet with time and temperature is found to be good. Hence the feasibility of manufacturing PM flowmeters suitable for high temperature sodium flow measurement with SmCo magnet assembly was demonstrated. These types of flow meters will be compact compared to ALNICO-5 flowmeters if designed for same sensitivity and can be deployed in future Fast reactors. This paper gives the details of Samarium cobalt flowmeter, sensitivity estimate, stability testing and sodium test results.