Liquid metal electromagnetic flowmeter capable of eliminating influence of environmental magnetic field and use method

Abstract

The invention discloses a liquid metal electromagnetic flowmeter capable of eliminating the influence of an environmental magnetic field and a use method. The flowmeter comprises a flow channel, a magnet exciting coil, a first environment magnetic field eliminating coil, a second environment magnetic field eliminating coil, a first signal receiving coil, a second signal receiving coil and a measuring device. Induced electromotive forces generated by an environment magnetic field on the four induction coils are equal, and the electromotive forces of the elimination coil and the signal receiving coil are superposed and counteracted through a specific connection mode, so that the influence of the environment magnetic field is reduced, and the signal-to-noise ratio is improved. When the flow needs to be measured, firstly measuring the phase difference, then adjusting the frequency to determine the working frequency, obtaining the relationship between the flow velocity and the phase difference, inputting the relational expression, finally measuring the phase difference, performing interpolation calculation to obtain the flow velocity, and calculating the volume and mass flow by combining the geometric parameters of the flow channel and the liquid metal density. The device and the method have the advantages of wide measurement range, high precision, strong applicability and the like, are suitable for various environmental magnetic fields and flow channel sizes, are higher in measurement precision and are stable, and measurement signals are not influenced by corrosion of working media.

Description

Technical Field

[0001] The present invention belongs to the technical field of liquid metal flow measurement, and particularly relates to a liquid metal electromagnetic flowmeter for eliminating the influence of environmental magnetic fields and a usage method thereof. Background Technique

[0002] Due to its good electrical conductivity and excellent thermal conductivity, liquid metal has been widely used in many industrial fields such as energy and electronics, as well as scientific research related to materials and aerospace. It can be used in fields such as nuclear reactor cooling and electronic device heat dissipation.

[0003] However, the flow measurement of liquid metal has always been a challenge. Especially in the presence of complex environmental magnetic fields, the interference of the environmental magnetic field will seriously affect the accuracy of flow measurement. Especially at high magnification, the weak signal has a huge impact on the result after amplification, affecting the accuracy of the instrument and the stability of the control system. Existing liquid metal electromagnetic flowmeters are easily interfered by environmental magnetic fields. Especially in a strong electromagnetic environment, even if shielding measures are taken, it may still be impossible to completely eliminate the influence of interference signals, and there are deficiencies in eliminating the influence of environmental magnetic fields, unable to meet the requirements of high-precision measurement.

[0004] Traditional permanent magnet liquid metal electromagnetic flowmeters are suitable for medium and small-sized flow channels. When the flow channel size is relatively large, a magnetic field with a sufficiently large magnetic induction intensity is required, resulting in very bulky, costly, and difficult-to-install permanent magnet electromagnetic flowmeters. In the prior art, a patent (application number: CN202210505110.8) discloses a liquid metal electromagnetic flowmeter, the measured signal of which is the phase difference of the induction signal. When the environmental magnetic field changes, the induced electromotive force of the receiving coil will change. Under the same fluid flow rate, the measurement result of the flowmeter will change with the change of the environmental magnetic field, and the measurement accuracy is poor. Summary of the Invention

[0005] To solve the above technical problems, the present invention provides a liquid metal electromagnetic flowmeter for eliminating the influence of environmental magnetic fields and a usage method thereof, which overcomes the problem of interference of the environmental magnetic field on the receiving coil when measuring the liquid metal flow by the existing electromagnetic induction method, improves the measurement accuracy of the liquid metal electromagnetic flowmeter, and has the advantages of high measurement accuracy and wide application range.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A liquid metal electromagnetic flowmeter for eliminating the influence of environmental magnetic fields, the electromagnetic flowmeter includes: a circular flow channel, an excitation coil, a first environmental magnetic field elimination coil, a first signal receiving coil, a second environmental magnetic field elimination coil, a second signal receiving coil, and a measuring device, wherein,

[0008] The central axes of the first environmental magnetic field cancellation coil, the first signal receiving coil, the second environmental magnetic field cancellation coil, the second signal receiving coil, the excitation coil, and the circular flow channel are all located in the same plane. The first environmental magnetic field cancellation coil and the first signal receiving coil share a common central axis, and the second environmental magnetic field cancellation coil and the second signal receiving coil share another common central axis. The two central axes and the central axis of the excitation coil are perpendicular to the axis of the circular flow channel. The same-polarity ends of the first environmental magnetic field cancellation coil and the second environmental magnetic field cancellation coil are connected, and the first signal receiving coil and the second signal receiving coil are respectively connected to the positive and negative electrodes of the measuring device;

[0009] The liquid metal flows unidirectionally in the circular flow channel.

[0010] On the other hand, a method for using a liquid metal electromagnetic flowmeter that eliminates the influence of the environmental magnetic field includes:

[0011] Step 1: Apply an alternating current to the excitation coil. The liquid metal in the circular flow channel flows under the action of an external force. Connect the same-polarity ends of the first environmental magnetic field cancellation coil and the second environmental magnetic field cancellation coil, and respectively connect the first signal receiving coil and the second signal receiving coil to the positive and negative electrodes of the measuring device, and measure the phase difference of the induced electromotive forces generated by the two receiving coils;

[0012] Step 2: At the same liquid metal flow rate, adjust the input frequency of the alternating current provided by the excitation coil to obtain the phase difference between the first signal receiving coil and the second signal receiving coil at different frequencies, and set the frequency corresponding to the maximum phase difference as the operating frequency of the electromagnetic flowmeter;

[0013] Step 3: Set the frequency of the alternating current of the excitation coil as the operating frequency of the electromagnetic flowmeter, adjust the liquid metal flow rate, and obtain the relationship between the liquid metal flow rate and the phase difference;

[0014] Step 4: Input the relationship into the phase difference conversion module;

[0015] Step 5: For liquid metal with any environmental magnetic field and flow rate, by measuring the phase difference signal and inputting the phase difference signal into the phase difference conversion module, calculate the flow direction, volume flow rate, and mass flow rate of the liquid metal.

[0016] The present invention provides an electronic device including: one or more processors; a memory for storing one or more programs; wherein, when the one or more programs are executed by the one or more processors, the one or more processors implement the aforementioned method for using a liquid metal electromagnetic flowmeter that eliminates the influence of the environmental magnetic field.

[0017] The present invention provides a computer-readable storage medium, on which executable instructions are stored. When the instructions are executed by a processor, the processor can implement the foregoing method for using a liquid metal electromagnetic flowmeter for eliminating the influence of an environmental magnetic field.

[0018] The beneficial effects of the present invention are as follows:

[0019] (1) The present invention pre-eliminates the influence of the environmental magnetic field and can be applied to various environmental magnetic fields, with wide applicability;

[0020] (2) Since the electromagnetic flowmeter signal of the present invention is generated in a non-contact manner, it can be applied to flow channels of various sizes;

[0021] (3) In the present invention, the measurement signal is the phase difference of the alternating electromotive force in the signal receiving coil. The fluid flow direction can be determined according to the positive or negative of the phase difference, which is a non-contact measurement; whether the measurement working medium is corrosive will not affect the measurement signal, ensuring the accuracy and high precision of the measurement result.

[0022] (4) The signal measured by the liquid metal electromagnetic flowmeter of the present invention is the phase difference of the induction signal after eliminating the influence of the environmental magnetic field. The influence generated by the change of the environmental magnetic field will not affect the phase difference of the two measurement coils, and the measurement accuracy is higher and more stable. Description of the Drawings

[0023] Figure 1 It is a schematic structural diagram of a liquid metal electromagnetic flowmeter for eliminating the influence of an environmental magnetic field according to the present invention.

[0024] Reference Signs:

[0025] 1 - Circular flow channel, 2 - Excitation coil, 3 - First environmental magnetic field elimination coil, 4 - First signal receiving coil, 5 - Second environmental magnetic field elimination coil, 6 - Second signal receiving coil, 7 - Measuring device. Detailed Embodiments

[0026] The present invention will be further described below with reference to the drawings and embodiments.

[0027] As Figure 1As shown in the figure, the present invention provides a liquid metal electromagnetic flowmeter for eliminating the influence of environmental magnetic fields. Based on Faraday's law of electromagnetic induction, the electromagnetic flowmeter includes: a circular flow channel 1, an excitation coil 2, a first environmental magnetic field cancellation coil 3, a first signal receiving coil 4, a second environmental magnetic field cancellation coil 5, a second signal receiving coil 6, and a measuring device 7. The structures of the first environmental magnetic field cancellation coil 3, the first signal receiving coil 4, the second environmental magnetic field cancellation coil 5, and the second signal receiving coil 6 are completely the same, and their central axes are all located in the same plane, denoted as the axis plane. The central axis of the excitation coil 2 is also located in the same plane. Further, the first environmental magnetic field cancellation coil 3 and the first signal receiving coil 4 share a central axis, and the second environmental magnetic field cancellation coil 5 and the second signal receiving coil 6 share another central axis. Moreover, the two central axes and the central axis of the excitation coil 2 are all perpendicular to the axis of the circular flow channel 1, and the central axis of the circular flow channel 1 is also located in the above-mentioned axis plane. The excitation coil 2 is located on one side of the circular flow channel 1, and the first environmental magnetic field cancellation coil 3, the first signal receiving coil 4, the second environmental magnetic field cancellation coil 5, and the second signal receiving coil 6 are located on the other side of the circular flow channel 1. The liquid metal flows unidirectionally in the circular flow channel 1. Since the distribution range of the interference magnetic field in the environment is usually very large, and the area of the induction coil is relatively small compared to the range of the interference magnetic field, it can be considered that the environmental magnetic fields contacted by the four induction coils, namely the first environmental magnetic field cancellation coil 3, the first signal receiving coil 4, the second environmental magnetic field cancellation coil 5, and the second signal receiving coil 6, are the same. Therefore, the induced electromotive forces generated by the environmental magnetic field on the four induction coils are equal.

[0028] The circular flow channel 1 is a circular ring-shaped pipe, and the liquid metal flows in the pipe.

[0029] The same-polarity ends of the first environmental magnetic field cancellation coil 3 and the second environmental magnetic field cancellation coil 5 are connected, and the first signal receiving coil 4 and the second signal receiving coil 6 are respectively connected to the positive and negative electrodes of the measuring device 7. In this way, the induced electromotive forces of the first environmental magnetic field cancellation coil 3 and the first signal receiving coil 4 will be superimposed and canceled, and the induced electromotive forces of the second environmental magnetic field cancellation coil 5 and the second signal receiving coil 6 will also be superimposed and canceled. The magnetic field values measured by the first signal receiving coil 4 and the second signal receiving coil 6 are the magnetic field values after the magnetic field generated by the excitation coil 2 passes through the liquid metal, thereby reducing the influence caused by the environmental magnetic field and improving the signal-to-noise ratio. The first signal receiving coil 4 and the second signal receiving coil 6 output induced alternating signals. By detecting the phase difference between the two alternating induced alternating currents, the flow signal of the liquid metal can be obtained.

[0030] When the liquid metal in the circular flow channel 1 does not flow, the magnetic Reynolds number of the liquid metal is zero, and the phase difference of the induced electromotive forces in the first signal receiving coil 4 and the second signal receiving coil 6 is zero; when the liquid metal in the circular flow channel 1 flows, a phase difference is generated in the induced electromotive forces in the first signal receiving coil 4 and the second signal receiving coil 6. At the same temperature of the liquid metal, the phase difference is proportional to the flow velocity of the liquid metal, and after processing, the flow signal of the liquid metal can be obtained.

[0031] Based on different types of measured liquid metals, the optimal measurement frequency of the electromagnetic flowmeter will change. The input frequency of the excitation coil 2 is adjustable to obtain the optimal signal output of the electromagnetic flowmeter.

[0032] The change of the ambient magnetic field around the liquid metal pipeline will cause the change of the induced electromotive force of the receiving coil, and the change of the induced electromotive force of the receiving coil will affect the change of the output phase difference. In order to measure the flow rate of liquid metal under different ambient magnetic fields more accurately, the first ambient magnetic field cancellation coil 3 and the second ambient magnetic field cancellation coil 5 are used to correct the influence of the ambient magnetic field on the measured phase difference signal.

[0033] The present invention provides a method for using a liquid metal electromagnetic flowmeter to eliminate the influence of the ambient magnetic field, which is divided into the following five steps:

[0034] Step 1: Provide an alternating current to the excitation coil 2, and the liquid metal in the circular flow channel 1 flows under the action of an external force. Connect the same-polarity ends of the first ambient magnetic field cancellation coil 3 and the second ambient magnetic field cancellation coil 5, and connect the first signal receiving coil 4 and the second signal receiving coil 6 to the positive and negative poles of the measuring device 7 respectively, and measure the phase difference of the induced electromotive forces generated by the two receiving coils.

[0035] Step 2: At the same flow velocity of the liquid metal, adjust the input frequency of the alternating current provided by the excitation coil 2 to obtain the phase differences between the first signal receiving coil 4 and the second signal receiving coil 6 at different frequencies, and set the frequency corresponding to the maximum phase difference as the operating frequency of the electromagnetic flowmeter.

[0036] Step 3: Set the frequency of the alternating current of the excitation coil 2 as the operating frequency of the electromagnetic flowmeter obtained in Step 2, adjust the flow velocity of the liquid metal, and obtain the relationship between the flow velocity of the liquid metal and the phase difference.

[0037] Step 4: Input the relationship obtained in Step 3 into the phase difference conversion module.

[0038] Step 5: For liquid metal under any ambient magnetic field and flow rate, measure the phase difference, input the phase difference signal into the phase difference conversion module, calculate the flow rate of the liquid metal under this working condition through interpolation calculation, and finally calculate the flow direction, volume flow rate, and mass flow rate of the liquid metal by combining the geometric parameters of the liquid metal flow channel and the density of the liquid metal.

[0039] The present invention provides an electronic device, including: one or more processors; a memory for storing one or more programs; wherein, when the one or more programs are executed by the one or more processors, the one or more processors are caused to implement the foregoing method for using a liquid metal electromagnetic flowmeter to eliminate the influence of the ambient magnetic field.

[0040] The present invention provides a computer-readable storage medium, on which executable instructions are stored, and when the instructions are executed by a processor, the processor can be caused to implement the foregoing method for using a liquid metal electromagnetic flowmeter to eliminate the influence of the ambient magnetic field.

[0041] The specific embodiments described above have further elaborated on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A liquid metal electromagnetic flowmeter that eliminates the influence of environmental magnetic field, characterized in that: The electromagnetic flowmeter comprises: a circular flow channel, an excitation coil, a first environmental magnetic field elimination coil, a first signal receiving coil, a second environmental magnetic field elimination coil, a second signal receiving coil, and a measuring device, wherein: The central axes of the first environmental magnetic field elimination coil, the first signal receiving coil, the second environmental magnetic field elimination coil, the second signal receiving coil, the excitation coil, and the circular flow channel are all located on the same plane, and the first environmental magnetic field elimination coil and the first signal receiving coil share one central axis, and the second environmental magnetic field elimination coil and the second signal receiving coil share another central axis, the two central axes and the central axis of the excitation coil are perpendicular to the axis of the circular flow channel, the first environmental magnetic field elimination coil and the second environmental magnetic field elimination coil are connected to the same polarity end, and the first signal receiving coil and the second signal receiving coil are connected to the positive and negative poles of the measuring device respectively; The liquid metal flows unidirectionally in the circular flow channel.

2. The liquid metal electromagnetic flowmeter for eliminating the influence of environmental magnetic field according to claim 1, characterized in that: The structures of the first environmental magnetic field elimination coil, the first signal receiving coil, the second environmental magnetic field elimination coil, and the second signal receiving coil are completely the same.

3. The liquid metal electromagnetic flowmeter for eliminating the influence of environmental magnetic field according to claim 1, characterized in that: The first environmental magnetic field elimination coil, the first signal receiving coil, the second environmental magnetic field elimination coil, and the second signal receiving coil are exposed to the same environmental magnetic field.

4. The liquid metal electromagnetic flowmeter for eliminating the influence of environmental magnetic field according to claim 1, characterized in that: The excitation coil is located on one side of the circular flow channel, and the first environmental magnetic field elimination coil, the first signal receiving coil, the second environmental magnetic field elimination coil, and the second signal receiving coil are all located on the other side of the circular flow channel.

5. The liquid metal electromagnetic flowmeter for eliminating the influence of environmental magnetic field according to claim 1, characterized in that: The first signal receiving coil and the second signal receiving coil output an induced AC signal, and a flow signal of the liquid metal is obtained by detecting the phase difference between the two induced AC signals.

6. The liquid metal electromagnetic flowmeter for eliminating the influence of environmental magnetic field according to claim 5, characterized in that: When the liquid metal in the circular flow channel does not flow, the magnetic Reynolds number of the liquid metal is zero, and the phase difference between the induced electromotive force in the first signal receiving coil and the second signal receiving coil is zero; when the liquid metal in the circular flow channel flows, the induced electromotive force in the first signal receiving coil and the second signal receiving coil produces a phase difference, and based on the liquid metal at the same temperature, the phase difference is proportional to the flow rate of the liquid metal, and the flow signal of the liquid metal is obtained.

7. The liquid metal electromagnetic flowmeter for eliminating the influence of environmental magnetic field according to claim 5, characterized in that: The optimal measurement frequency of the electromagnetic flowmeter is adjusted according to the change of the type of liquid metal.

8. A method for using a liquid metal electromagnetic flowmeter to eliminate the influence of an environmental magnetic field, characterized in that: include: Step 1: Provide alternating current to the excitation coil, and the liquid metal in the circular flow channel flows under the action of external force. Connect the first environmental magnetic field elimination coil and the second environmental magnetic field elimination coil with the same polarity end, connect the first signal receiving coil and the second signal receiving coil to the positive and negative poles of the measuring device respectively, and measure the phase difference of the induced electromotive force generated by the two receiving coils; Step 2: Under the same liquid metal flow rate, adjust the input frequency of the alternating current provided by the excitation coil to obtain the phase difference between the first signal receiving coil and the second signal receiving coil at different frequencies, and set the frequency corresponding to the maximum phase difference as the operating frequency of the electromagnetic flowmeter; Step 3: setting the frequency of the alternating current of the excitation coil to the operating frequency of the electromagnetic flowmeter, adjusting the flow rate of the liquid metal, and obtaining a relationship between the flow rate of the liquid metal and the phase difference; Step 4: input the relational expression into the phase difference conversion module; Step 5: For liquid metal in any environmental magnetic field and flow rate, the flow direction, volume flow rate and mass flow rate of the liquid metal are calculated by measuring the phase difference signal and inputting the phase difference signal into the phase difference conversion module.

9. An electronic device, characterized in that: include: one or more processors; A memory for storing one or more programs; When one or more programs are executed by the one or more processors, the one or more processors implement the method for using a liquid metal electromagnetic flowmeter that eliminates the influence of environmental magnetic fields as described in claim 8.

10. A computer-readable storage medium, characterized in that: Executable instructions are stored thereon, and when the instructions are executed by the processor, the processor can implement the method for using a liquid metal electromagnetic flowmeter that eliminates the influence of environmental magnetic fields as described in claim 8.

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