[The latest patent of the instrument] a permanent magnet liquid metal flow meter

There is no limit to creativity, and the instrument is invented. Today we introduce a national invention patent for authorization - a permanent magnet liquid metal flow meter. The patent was filed by the China Institute of Atomic Energy and was issued an authorization announcement on October 9, 2018.

Description

The invention belongs to the technical field of flow meters, and in particular relates to a permanent magnet liquid metal flow meter.

Background of the invention

Conventional flow meters cannot be used in the field of liquid metal flow measurement due to the high temperature of liquid metal, the chemical nature of the liquidity and the high radiation environment in most applications. The permanent magnet pipeline liquid metal flow meter is based on the principle of Faraday's law of electromagnetic induction, that is, the liquid metal cuts the magnetic field lines when flowing in a pipe perpendicular to the magnetic field, and generates an induced electromotive force on the two electrodes perpendicular to the direction of movement of the liquid metal and the direction of the magnetic field lines. The magnitude of this induced electromotive force is proportional to the fluid flow rate, so that the flow rate of liquid metal can be obtained by detecting the induced electromotive force of the flow meter.

Because the permanent magnet pipeline liquid metal flow meter has the advantages of simple structure, strong output signal, good linearity, high temperature resistance and insensitivity to fluid flow characteristics, it has been applied to pipeline liquid metal flow measurement at home and abroad. However, the application fields of liquid metals (such as sodium in sodium cooled fast reactors) generally have the characteristics of high temperature and wide temperature range (such as the temperature range of sodium in the fast reactor is 150 ° C ~ 600 ° C), if only guarantee a certain The measured linearity at a temperature does not fully meet the actual measurement requirements.

The currently published Chinese patents (application numbers 200910116768 .4 and 201210556276 .9) are liquid metal flow meters using the permanent magnet principle, both of which use a monolithic magnetic steel component structure, if used as a large diameter (eg DN200) ), the measurement of liquid metal flow in a large-scale pipeline will have the problem that the measurement linearity cannot meet the demand.

In addition, after the installation of the traditional liquid metal flow meter based on safety factors, the welding method is generally adopted, and the calibration is no longer disassembled, and the liquid metal flow meter disclosed at present has not considered how to realize the online calibration of the flow meter.

Summary of the invention

According to the problems existing in the prior art, the present invention provides a liquid metal flow meter suitable for large-scale (>300 m3/h) which can realize on-line calibration, good linearity measurement and small measurement error.

In order to solve the problems existing in the prior art, the technical solution provided by the present invention is as follows: A permanent magnet type liquid metal flow meter, the flow meter comprising a primary sensor, a secondary meter and a related method flow measuring device; the primary sensor comprises The magnetic system measuring component, the temperature measuring component, the supporting positioning component and the shielding component, wherein the shielding component is located outside the measuring part of the magnetic system, is a bell-shaped structure for protection of the flow meter; and a magnetic flux is arranged on the upper part of the shielding component Measuring the blind tube, which serves as a magnetic flux density measurement interface for placing the Tesla meter; the Tesla meter is extended to the bottom of the blind tube during periodic calibration to ensure the consistency of the Tesla meter probe measurement position at different times. After the magnetic flux density measurement of the magnetic steel component is measured, the flow meter graduation characteristic change caused by the change of the magnetic flux density after the long-time operation of the flow meter is corrected by calculation;

The magnetic system measuring component is a core of a primary sensor, which is composed of a plurality of magnetic steel components connected in series, and the plurality of magnetic steel components are connected by a pair of magnetic poles to form a closed magnetic circuit, and provide a stable magnetic field for the permanent magnet pipeline liquid metal flow meter. The magnetic system measuring component further includes an electrode and a pipe assembly; each of the magnetic steel components includes a permanent magnet, a yoke, a permanent magnet, a yoke, and a magnetic pole symmetrically disposed at a radial position of the pipe assembly, and the permanent magnet and The yoke is fixedly connected; the shape of the permanent magnet is a rectangular parallelepiped or a cylinder, and the shape of the yoke is U-shaped, which is located below the pipe assembly, and the two ends of the U-shaped yoke are respectively fixedly connected with the permanent magnet; the shape of the magnetic pole is a flat rectangular parallelepiped, the magnetic pole is fixedly connected with the permanent magnet; the number of pairs of the electrodes is a plurality of pairs, and the center of the two magnetic poles is opposite to the flow direction of the liquid metal; the axis of the pipe assembly, the electrode axis and the magnetic field line are perpendicular to each other;

The temperature measurement point of the temperature measuring component is located on a permanent magnet within the magnetic system measuring component for temperature measurement of the magnetic steel component to compensate for changes in the indexing characteristics of the sensor due to changes in the temperature of the medium. The support positioning assembly is located below the pipe assembly to achieve fixed support of the pipe assembly and prevent circumferential and radial movement of the pipe assembly, ensuring that the pipe assembly axis, the electrode axis, and the magnetic lines of force are perpendicular to each other.

The correlation method flow measurement device includes a data acquisition unit, a correlation analysis machine, and the like, which are connected to the electrodes through a signal cable, which analyzes the flow signals of any two pairs of electrodes, and establishes the transmission time and flow rate of the flow fluctuation signal. Relationship, by measuring the transmission time of the flow fluctuation signal, the flow rate of the liquid metal can be determined, thereby completing the online calibration of the flow meter. Preferably, the magnetic pole and the pipe assembly are air gaps, and the gap has a width of 2 to 6 mm.

Advantageous Effects of Invention: The liquid metal flow meter provided by the present application is different from the conventional flowmeter structure in that it measures the flow rate of liquid metal, especially at a large flow rate (>300 m3/h) by using a tandem split structure. The range of the uniform magnetic field of the measuring part of the magnetic system of the flowmeter is increased, and the linearity of the output is improved; the matched temperature measuring component and the secondary instrument can compensate the change of the indexing characteristic of the flowmeter due to the change of the medium temperature in real time. It ensures the measurement accuracy of liquid metal over the entire operating temperature range. In addition, the related method flow online calibration device matched with the device can realize on-line calibration of the flow meter, and solves the problem that the liquid metal flow meter is inconvenient to disassemble and perform regular calibration.

For further information, please download the full specification of the patent.

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