Non-contact liquid level measuring method and device

Abstract

The invention relates to the technical field of industrial process detection and electromagnetic measurement, and discloses a non-contact liquid level measurement method and device.The method is used for a signal processing unit, the signal processing unit is connected with a non-contact high-temperature liquid level meter, and the non-contact high-temperature liquid level meter is packaged in a closed tank of liquid metal to be measured; the non-contact high-temperature liquid level meter comprises an inner side coil and an outer side coil; the method comprises the following steps: receiving an induced electromotive force signal of the non-contact high-temperature liquid level meter; based on the induced electromotive force signal, the liquid level height value of the measured liquid metal is obtained through first relational expression processing, and according to the first relational expression, according to the electromagnetic field reciprocity theorem and the electromagnetic induction principle, the eddy current effect caused by the liquid level change of the measured liquid metal is equivalent to coil mutual inductance modulation item determination. Therefore, long-term stable and high-precision non-contact liquid level measurement is realized in a high-temperature, strong-corrosion and high-conductivity liquid metal environment by implementing the non-contact liquid level measurement device and the non-contact liquid level measurement method.

Description

Technical Field

[0001] This invention relates to the field of industrial process detection and electromagnetic measurement technology, specifically to a non-contact liquid level measurement method and device. Background Technology

[0002] In industrial fields such as metallurgy, chemical engineering, and liquid metal-cooled nuclear reactors, it is often necessary to measure the level of high-temperature, highly corrosive liquid metals (such as molten aluminum, molten steel, and liquid sodium) or conductive liquids. Under these extreme conditions, traditional mechanical, optical, or acoustic level gauges all face severe challenges: Mechanical instruments (such as float-type and probe-type) are prone to high-temperature jamming and corrosion damage due to direct contact between moving parts and the medium, resulting in short service life and low reliability; Optical and radiation level gauges suffer from complex safety protection, high equipment costs, and susceptibility to interference from on-site smoke and steam, limiting their application; Acoustic / ultrasonic level gauges face difficulties in selecting waveguide materials in high-temperature environments, and the propagation characteristics of sound waves in high-temperature, high-density media are unstable, making it difficult to guarantee measurement accuracy. When dealing with highly conductive liquid metals, radar level gauges experience near total reflection of their microwave signals at the gas-liquid interface, resulting in poor penetration, and the measurement effect is heavily dependent on the dielectric constant of the medium, making effective detection difficult.

[0003] The inherent defects of the above-mentioned technologies make it difficult for existing solutions to achieve long-term stable and high-precision non-contact liquid level measurement in high-temperature, highly corrosive, and highly conductive liquid metal environments. Summary of the Invention

[0004] This invention provides a non-contact liquid level measurement method and device to solve the problem that existing solutions are difficult to achieve long-term stable and high-precision non-contact liquid level measurement in high-temperature, highly corrosive, and highly conductive liquid metal environments.

[0005] In a first aspect, the present invention provides a non-contact liquid level measurement method for a signal processing unit connected to a non-contact high-temperature liquid level gauge. The non-contact high-temperature liquid level gauge is encapsulated in a closed container of the liquid metal being measured. The non-contact high-temperature liquid level gauge includes an inner coil and an outer coil. The method includes: The induced electromotive force signal of the non-contact high-temperature liquid level gauge is received. The induced electromotive force signal is obtained by applying a sinusoidal alternating current to the inner or outer coil. Based on the induced electromotive force signal, the liquid level height value of the measured liquid metal is obtained after processing by the first relational expression. The first relational expression is determined by equating the eddy current effect caused by the liquid level change of the measured liquid metal to the coil mutual inductance modulation term according to the electromagnetic field reciprocity theorem and the principle of electromagnetic induction.

[0006] The non-contact liquid level measurement method provided by this invention encapsulates a non-contact high-temperature liquid level gauge within a sealed container of the liquid metal being measured, achieving stable installation and sealing of the gauge and avoiding direct corrosion of the sensor by high-temperature and highly corrosive media. Furthermore, by applying a sinusoidal alternating current to the inner or outer coil to obtain an induced electromotive force signal, it overcomes the limitation of the single excitation method in traditional instruments, achieving bidirectional flexible adaptation of coil functions and providing a stable and interference-resistant core electrical signal input for liquid level measurement under extreme conditions. Furthermore, based on the electromagnetic reciprocity theorem and the principle of electromagnetic induction, the eddy current effect caused by the liquid level change of the measured liquid metal is equivalent to the coil mutual inductance modulation term, determining the first relational expression. This overcomes the inherent defects of radar, ultrasonic, and other technologies, such as weak penetration of metal sleeves and dependence on medium characteristics, establishing a precise mapping between the physical quantity of liquid level and the electrical signal. Then, based on the induced electromotive force signal processed by the first relational expression, the liquid level height value is obtained, overcoming the shielding interference of the metal sleeve in principle, realizing direct calculation of liquid level under high-temperature environments, and ensuring the reliability and accuracy of the measurement results. Therefore, by implementing this invention, long-term stable and high-precision non-contact liquid level measurement is achieved in high-temperature, highly corrosive, and highly conductive liquid metal environments.

[0007] In one alternative implementation, the method further includes: When there is no liquid metal to be measured in the closed tank, the initial coil mutual inductance of the non-contact high-temperature liquid level gauge is obtained; when there is liquid metal to be measured in the closed tank, the eddy current effect caused by the liquid level change of the liquid metal to be measured is equivalent to the coil mutual inductance modulation term; the first mutual inductance relationship is established based on the initial coil mutual inductance and the coil mutual inductance modulation term; based on the first mutual inductance relationship and the coil mutual inductance modulation term, the first relationship between the induced electromotive force and the liquid level is established using the electromagnetic field reciprocity theorem and the principle of electromagnetic induction.

[0008] The non-contact liquid level measurement method provided by this invention obtains the initial coil mutual inductance when the sealed tank is free of the liquid metal being measured, establishing the measurement reference parameters and ensuring the consistency of the measurement accuracy. Furthermore, when the sealed tank contains the liquid metal being measured, the eddy current effect caused by the liquid level change is equivalent to the coil mutual inductance modulation term, quantifying the disturbance effect of the liquid level on the electromagnetic field and realizing the transformation of abstract physical effects into calculable electromagnetic parameters. Further, based on the initial coil mutual inductance and the mutual inductance modulation term, a first mutual inductance relationship is established, constructing a quantitative model of the reference mutual inductance and the mutual inductance change related to the liquid level. Then, based on the first mutual inductance relationship and the mutual inductance modulation term, the first relationship between induced electromotive force and liquid level is established using the electromagnetic reciprocity theorem and the principle of electromagnetic induction. This forms a complete derivation chain of liquid level, mutual inductance, and induced electromotive force, ensuring the theoretical rigor and accuracy of the measurement method.

[0009] In one optional implementation, based on the first mutual inductance relationship and the coil mutual inductance modulation term, a first relationship between the induced electromotive force and the liquid level is established using the electromagnetic field reciprocity theorem and the principle of electromagnetic induction, including: Based on the first mutual inductance relationship, the electromagnetic reciprocity theorem is used to transform the coil mutual inductance modulation term into the electric field integral form within the volume of the liquid metal being measured, and the second mutual inductance relationship is determined; based on the principle of electromagnetic induction, the second relationship between induced electromotive force and mutual inductance is determined; based on preset conditions, the first relationship between induced electromotive force and liquid level is established according to the second mutual inductance relationship and the second relationship.

[0010] The non-contact liquid level measurement method provided by this invention, based on the first mutual inductance relationship, utilizes the electromagnetic reciprocity theorem to transform the mutual inductance modulation term into the electric field integral form within the liquid metal volume and determines the second mutual inductance relationship, revealing the microscopic physical essence of mutual inductance changes and providing precise mathematical support for the correlation between liquid level and electromagnetic parameters. Furthermore, based on the principle of electromagnetic induction, the second relationship between induced electromotive force and mutual inductance is determined, establishing a direct correlation between electromagnetic parameters (mutual inductance) and measurable electrical signals (induced electromotive force), bridging the theoretical model and actual measurement. Further, based on preset conditions, a first relationship between induced electromotive force and liquid level is established by combining the second mutual inductance relationship and the second relationship, simplifying the calculation logic, clarifying the direct mapping relationship between liquid level and induced electromotive force, and providing a concise and efficient mathematical model for signal processing.

[0011] In one alternative implementation, the method further includes: Acquire real-time temperature datasets of non-contact high-temperature level gauges and enclosed tanks; based on the real-time temperature datasets, use a preset temperature error correction model to correct the liquid level height value.

[0012] The non-contact liquid level measurement method provided by this invention can capture the influence parameters of the high temperature environment on the measurement system by acquiring the real-time temperature dataset of the non-contact high temperature liquid level gauge and the closed tank. Then, it can combine the preset temperature error correction model to correct the liquid level height, suppress systematic errors such as coil performance drift and changes in medium conductivity caused by high temperature, and thus ensure stable measurement accuracy across the entire temperature range.

[0013] In one alternative implementation, the sinusoidal alternating current is adjusted according to the conductivity of the liquid metal being measured and the thickness of the casing of the enclosed tank.

[0014] The non-contact liquid level measurement method provided by this invention optimizes the skin depth of the electromagnetic field by adjusting the sinusoidal alternating current according to the conductivity of the liquid metal being measured and the thickness of the sleeve of the sealed tank. This ensures that the alternating magnetic field effectively penetrates the metal sleeve, thereby adapting to different media and tank structures and improving the signal-to-noise ratio and measurement reliability.

[0015] In a second aspect, the present invention provides a non-contact liquid level measuring device, the device comprising: a non-contact high-temperature liquid level gauge, a signal processing unit, and a sinusoidal constant current excitation source; the non-contact high-temperature liquid level gauge is encapsulated in a closed tank of the liquid metal being measured, and the non-contact high-temperature liquid level gauge includes an inner coil, an outer coil, and a metal shell; the signal processing unit is used to execute the non-contact liquid level measuring method of the first aspect or any corresponding embodiment described above; A sinusoidal constant current excitation source is used to output a sinusoidal alternating current to the inner coil; the inner coil is used to generate an alternating magnetic field based on the sinusoidal alternating current, and the alternating magnetic field penetrates the metal shell and acts on the liquid metal being measured; the outer coil is used to generate an induced electromotive force signal based on the change in magnetic flux corresponding to the change in liquid level height when the liquid level height of the liquid metal being measured changes, and transmits the induced electromotive force signal to the signal processing unit through a twisted pair. Alternatively, a sinusoidal constant current excitation source is used to output a sinusoidal alternating current to the outer coil; the outer coil is used to generate an alternating magnetic field based on the sinusoidal alternating current, and the alternating magnetic field penetrates the metal shell and acts on the liquid metal being measured; the inner coil is used to generate an induced electromotive force signal based on the change in magnetic flux corresponding to the change in liquid level height when the liquid level height of the liquid metal being measured changes, and transmits the induced electromotive force signal to the signal processing unit through a twisted pair.

[0016] The non-contact liquid level measuring device provided by this invention outputs a sinusoidal alternating current to the inner / outer coil via a sinusoidal constant current excitation source, providing stable excitation energy in terms of frequency and amplitude, thus ensuring the stability of the alternating magnetic field. Furthermore, the inner / outer coil generates an alternating magnetic field based on the sinusoidal alternating current, which penetrates the metal casing and acts on the measured liquid metal, achieving effective transmission and penetration of the magnetic field, overcoming the shielding effect of the metal casing, and ensuring the interaction between the magnetic field and the measured liquid metal. Furthermore, the outer / inner coil generates an induced electromotive force signal based on the change in magnetic flux corresponding to the liquid level change, and transmits it to the signal processing unit via a twisted pair cable. This converts the liquid level change into a transmittable electrical signal while suppressing common-mode interference, ensuring the integrity and stability of signal transmission. Furthermore, the signal processing unit executes a non-contact liquid level measurement method, enabling direct calculation of the liquid level under high-temperature conditions, ensuring the reliability and accuracy of the measurement results.

[0017] In one optional embodiment, the device further includes a fixed flange, wherein the non-contact high-temperature liquid level gauge is tightly fitted and fixed to the closed tank body through the fixed flange, and the lower part of the non-contact high-temperature liquid level gauge is immersed in the tank space and does not come into contact with the liquid metal being measured.

[0018] The non-contact liquid level measuring device provided by this invention achieves stable installation and sealing of the non-contact high-temperature liquid level gauge through a fixed flange, avoiding direct contact between high-temperature corrosive media and the core components of the sensor, ensuring long-term stable operation of the device, and meeting the core requirements of non-contact measurement.

[0019] In one optional embodiment, the non-contact high-temperature level gauge further includes a metal frame, which together with the metal shell constitutes an electromagnetic shielding and mechanical protection structure. The inner coil is wound on the outer surface of the metal frame, and the outer coil is wound on the outside of the inner coil and is insulated and attached to the inner coil.

[0020] The non-contact liquid level measuring device provided by this invention uses a metal frame and a metal shell to form an electromagnetic shielding and mechanical protection structure, which can effectively isolate external stray magnetic field interference, while providing mechanical protection and stable support for the coil assembly, improving signal quality and device durability. Furthermore, the inner coil is wound on the outer surface of the metal frame, and the outer coil is wound on the outside of the inner coil and insulated from it, which optimizes the magnetic field coupling effect, ensures magnetic field transmission efficiency, avoids the risk of short circuits between coils, and guarantees the device's operational safety and measurement sensitivity.

[0021] In one alternative embodiment, both the metal frame and the metal shell are made of stainless steel, with the metal frame being a cylindrical metal frame and the metal shell being a cylindrical metal shell.

[0022] The non-contact liquid level measuring device provided by this invention, by using stainless steel, endows the metal frame and metal shell with high-temperature oxidation and corrosion resistance, while utilizing its high magnetic permeability to enhance electromagnetic shielding, making it suitable for extreme working conditions. Furthermore, by adopting a cylindrical shape, the magnetic field distribution is made more uniform, facilitating the magnetic field to penetrate the metal sleeve, which helps to improve the uniformity and accuracy of the measurement.

[0023] In one alternative implementation, both the inner and outer coils are made of pure nickel wire.

[0024] The non-contact liquid level measuring device provided by this invention uses pure nickel wires to ensure that the inner and outer coils can work stably for a long time in extreme high temperature environments, avoiding wire failure due to high temperature, and thus ensuring the high temperature adaptability and service life of the device. Attached Figure Description

[0025] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the structure of a non-contact liquid level measuring device according to an embodiment of the present invention; Figure 2 This is a flowchart illustrating a non-contact liquid level measurement method according to an embodiment of the present invention. Figure 3 This is a schematic diagram of the structure of a non-contact high-temperature liquid level gauge according to an embodiment of the present invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] It is understood that before using the technical solutions disclosed in the various embodiments of the present invention, users should be informed of the types, scope of use, and usage scenarios of the personal information involved in the present invention and their authorization should be obtained in accordance with relevant laws and regulations through appropriate means.

[0029] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0030] As an optional application scenario of this invention, such as Figure 1 As shown, a non-contact liquid level measuring device 1 is provided. The non-contact liquid level measuring device 1 includes a non-contact high-temperature liquid level gauge 2, a signal processing unit 3, a sinusoidal constant current excitation source 4, and a fixed flange 5.

[0031] Optionally, the non-contact high-temperature liquid level gauge 2 is encapsulated in a closed container (not shown in the figure) of the liquid metal being measured. It can generate an alternating magnetic field through a coil assembly and sense the electrical signal modulated by the liquid level. It has the functions of high temperature resistance, corrosion resistance and electromagnetic shielding.

[0032] In one alternative embodiment, the sealed tank is a container for holding the liquid metal being tested, used to provide a sealed environment for high-temperature and highly corrosive working conditions.

[0033] In one optional embodiment, the sealed tank provides a closed space for the liquid metal being measured. By encapsulating the non-contact high-temperature level gauge 2 within it, it can directly contact the working environment, allowing the alternating magnetic field to effectively act on the liquid metal. Simultaneously, it avoids interference from the external environment on the sensing unit, ensuring measurement stability under high-temperature and highly corrosive conditions.

[0034] Optionally, the non-contact high-temperature liquid level gauge 2 is tightly fitted and fixed to the closed tank body through the fixed flange 5, and the lower part of the non-contact high-temperature liquid level gauge 2 is immersed in the tank space and does not come into contact with the liquid metal being measured.

[0035] In an optional embodiment, the fixed flange 5 can achieve a tight connection between the level gauge and the tank using mechanical fastening structures (such as screws and nuts). On the one hand, this can ensure the stability of the installation and avoid the impact of vibration on the measurement accuracy under high temperature conditions. On the other hand, it can also achieve a sealed fit to prevent leakage of high temperature and corrosive media inside the tank. At the same time, it can also ensure heat conduction efficiency and avoid damage to components caused by local temperature differences.

[0036] Optionally, the non-contact high-temperature level gauge 2 includes an inner coil 21, an outer coil 22, a metal frame 23, and a metal housing 24.

[0037] In an optional embodiment, the inner coil 21, the outer coil 22, the metal frame 23, and the metal shell 24 can form an integrated structure for support, winding, protection, and shielding.

[0038] Specifically, the metal frame 23 provides stable support for the coil, ensuring the coil winding accuracy and the uniformity of the magnetic field distribution; the inner coil 21 and the outer coil 22 are nested together, which can optimize the magnetic field coupling effect and improve the induction sensitivity; the metal frame 23 and the metal shell 24 work together to guide the working magnetic circuit by utilizing the high magnetic permeability of stainless steel, isolate external stray magnetic fields, and at the same time physically protect the coil from corrosion.

[0039] Optionally, the inner coil 21 is wound on the outer surface of the metal frame 23, and the outer coil 22 is wound on the outside of the inner coil 21 and is insulated from and attached to the inner coil 21.

[0040] In an optional embodiment, by bringing the inner coil 21 close to the metal frame 23, the magnetic field strength can be enhanced by utilizing the magnetic permeability of the metal frame 23. Furthermore, by tightly insulating and bonding the outer coil 22 to the inner coil 21, the magnetic field propagation path can be shortened, and the magnetic flux coupling efficiency can be improved.

[0041] Furthermore, by insulating and bonding the outer coil 22 with the inner coil 21, short circuits between the coils can be avoided, ensuring stable current transmission.

[0042] Furthermore, the nested structure of the inner coil 21 and the outer coil 22 can make the magnetic field distribution more concentrated, thereby enhancing the ability to sense changes in liquid level.

[0043] Optionally, the metal frame 23 and the metal shell 24 are made of stainless steel, wherein the metal frame 23 is a cylindrical metal frame and the metal shell 24 is a cylindrical metal shell.

[0044] In an optional embodiment, by using stainless steel to make the metal frame 23 and the metal shell 24, the high magnetic permeability of stainless steel can be utilized to make the metal frame 23 and the metal shell 24 form an effective electromagnetic shielding structure, thereby reducing external magnetic field interference.

[0045] Furthermore, the high-temperature oxidation resistance and corrosion resistance of stainless steel also make the metal frame 23 and the metal shell 24 suitable for high-temperature and highly corrosive working conditions of 0-800℃.

[0046] Furthermore, by adopting a cylindrical structure, the alternating magnetic field generated by the inner coil 21 / outer coil 22 can be axially symmetrically distributed, thereby ensuring that the magnetic field has uniform intensity when penetrating the metal shell and avoiding measurement errors caused by magnetic field distortion.

[0047] Optionally, the metal frame 23 and the metal shell 24 together constitute an electromagnetic shielding and mechanical protection structure.

[0048] In an optional embodiment, the metal frame 23 and the metal shell 24 together form an electromagnetic shielding and mechanical protection structure, which can effectively isolate external stray magnetic field interference, while providing mechanical protection and stable support for the coil assembly, thereby improving signal quality and device durability.

[0049] Specifically, in terms of electromagnetic shielding, the high magnetic permeability of stainless steel allows external stray magnetic fields to be guided and absorbed by the frame and shell, preventing them from interfering with the magnetic field distribution of the internal coil. At the same time, the magnetic field generated by the internal coil is confined within the shielding structure, thereby enhancing the magnetic field penetration efficiency.

[0050] Furthermore, in terms of mechanical protection, the metal frame 23 and the metal shell 24 form a closed chamber, which can physically isolate high temperature and corrosive media from the coil assembly, avoid coil wear and corrosion, and thus extend the service life of the equipment.

[0051] Optionally, both the inner coil 21 and the outer coil 22 are made of pure nickel wire.

[0052] In one alternative embodiment, the pure nickel wire has excellent high temperature resistance and can maintain stable conductivity in high temperature environments of 0-800℃, thereby avoiding equipment failure caused by high temperature oxidation and melting of the wire.

[0053] Meanwhile, pure nickel wire has high conductivity, which can effectively reduce the internal resistance loss of the coil and ensure the strength and stability of the alternating magnetic field.

[0054] Optionally, the sinusoidal constant current excitation source 4 is used to output a sinusoidal alternating current to the inner coil 21.

[0055] In one optional embodiment, the sinusoidal constant current excitation source 4 serves as a dedicated energy supply unit, converting electrical energy into a stable sinusoidal alternating current. After receiving the current, the inner coil further converts the electrical energy into an alternating magnetic field based on the principle of electromagnetic induction. The periodic changes in the current will generate a periodically changing magnetic field around the inner coil 21.

[0056] Furthermore, the sinusoidal constant current excitation source 4 features constant current control, which can precisely maintain the stability of the output current amplitude, thereby avoiding magnetic field strength distortion caused by current fluctuations and ensuring the stability of subsequent magnetic flux modulation and induction signals. Simultaneously, the sinusoidal constant current excitation source 4 supports frequency adjustment, allowing the electromagnetic field skin depth to be changed by optimizing the frequency. This overcomes the shielding effect of the metal casing, enabling the alternating magnetic field to effectively penetrate and act on the measured liquid metal.

[0057] In one optional embodiment, the optimal excitation frequency and current amplitude can be determined based on the conductivity of the liquid metal being measured, the sleeve thickness of the sealed tank, and a preset operating condition adaptation algorithm. The conductivity varies depending on the medium, such as molten aluminum, molten steel, or liquid sodium.

[0058] The frequency is typically selected in the range of several hundred hertz to several thousand hertz, and the current amplitude is set in the range of 10mA to 100mA, which can ensure that the skin depth of the electromagnetic field and the magnetic field strength meet the penetration requirements and measurement sensitivity.

[0059] Furthermore, the sinusoidal constant current excitation source 4 can generate a sinusoidal alternating current with precise and stable frequency and amplitude through an internal oscillation circuit, a power amplifier circuit, and a constant current feedback adjustment circuit, based on the determined optimal excitation frequency and current amplitude. Then, the sinusoidal alternating current is transmitted to the inner coil 21 of the non-contact high-temperature liquid level gauge through a dedicated wire.

[0060] Furthermore, after the inner coil 21 receives a stable sinusoidal alternating current, a uniform and periodically changing alternating magnetic field is formed around its winding, and the conversion of electrical energy into magnetic field energy is completed, preparing for the magnetic field to penetrate the metal shell and act on the liquid metal being measured.

[0061] In an optional embodiment, a monitoring module can also be set inside the sinusoidal constant current excitation source 4 to detect the amplitude, frequency and waveform distortion rate of the output current in real time. If there is a deviation from the preset parameters, it can be corrected in time through the feedback adjustment mechanism, thereby ensuring that the current transmitted to the inner coil always meets the measurement requirements.

[0062] Optionally, the inner coil 21 is used to generate an alternating magnetic field based on a sinusoidal alternating current, and then apply the alternating magnetic field to the liquid metal being measured after penetrating the metal casing.

[0063] In an optional embodiment, the inner coil 21 serves as a current-carrying conductor winding. When a sinusoidal alternating current passes through it, the periodic change of the current will generate a periodically alternating magnetic field around it, i.e., an alternating magnetic field, thereby enabling the efficient conversion of electrical energy into magnetic field energy.

[0064] Furthermore, by combining frequency optimization technology and adjusting the frequency of the sinusoidal alternating current (from several hundred hertz to several thousand hertz), the skin depth of the electromagnetic field can be optimized, the electromagnetic shielding effect of the stainless steel metal shell can be overcome, and the alternating magnetic field can effectively penetrate the metal shell 24, avoiding excessive attenuation of the magnetic field by the shell and ensuring that the magnetic field energy can act on the liquid metal being measured inside the tank.

[0065] In one alternative embodiment, stable electrical energy is converted into an alternating magnetic field that can penetrate a metal barrier by an inner coil. This overcomes the limitation of traditional measurement techniques where magnetic fields / signals have difficulty penetrating a metal casing, enabling the magnetic field to interact effectively with the liquid metal being measured.

[0066] For example, the inner coil 21 receives a sinusoidal alternating current with stable frequency and amplitude output from a sinusoidal constant current excitation source. When this alternating current passes through the coil winding, it forms an alternating magnetic field around the inner coil 21 based on the principle of electromagnetic induction, thus completing the conversion of electrical energy into magnetic field energy.

[0067] Furthermore, the inner coil 21 is wound on the outer surface of the cylindrical stainless steel metal frame. The high magnetic permeability of the metal frame 23 confines the alternating magnetic field generated by the coil within the space between the frame and the metal shell, guiding the magnetic field to form an axisymmetric regular working magnetic circuit, reducing the diffusion of the magnetic field to non-target directions, and increasing the magnetic field energy density.

[0068] Furthermore, the optimized alternating magnetic field can overcome the electromagnetic shielding effect of the stainless steel metal shell. Moreover, the optimized alternating magnetic field penetrates the metal shell 24 walls and enters the enclosed internal space of the tank, where the magnetic field strength remains at the effective threshold, ensuring interaction with the liquid metal inside the tank.

[0069] Furthermore, the alternating magnetic field penetrating the metal shell 24 uniformly covers the area where the liquid metal is located inside the tank. Furthermore, the liquid metal, as a conductive medium, induces eddy currents under the action of the alternating magnetic field, forming an eddy current field and completing the transfer of magnetic field energy to the eddy current energy of the liquid metal.

[0070] Optionally, the outer coil 22 is used to generate an induced electromotive force signal based on the change in magnetic flux corresponding to the change in liquid level height when the liquid level height of the measured liquid metal changes, and transmit the induced electromotive force signal to the signal processing unit 3 through a twisted pair.

[0071] In an optional embodiment, the outer coil 22 is a closed conductor winding. When the magnetic flux passing through it changes periodically, an induced electromotive force, i.e., electromagnetic induction, is generated inside the coil, thereby realizing the conversion of magnetic field energy into electrical energy and converting the change in magnetic flux caused by the change in liquid level into a measurable electrical signal.

[0072] Furthermore, changes in the liquid level of the measured liquid metal alter its occupied volume, thereby adjusting the distribution range and intensity of the eddy current field. Moreover, the superposition of the reverse magnetic field generated by the eddy current field with the original magnetic field of the inner coil 21 results in dynamic modulation of the total magnetic flux passing through the outer coil 22; that is, the liquid level change and the magnetic flux change are correlated.

[0073] In an optional embodiment, when the alternating magnetic field generated by the inner coil 21 penetrates the metal shell 24 and acts on the liquid metal being measured, the liquid metal induces eddy currents to form an eddy current field.

[0074] Furthermore, when the liquid level rises or falls, the volume and distribution range of the liquid metal change accordingly, causing the intensity and coverage area of ​​the eddy current field to be dynamically adjusted, thereby modulating the total magnetic flux passing through the outer coil 22, so that the magnetic flux fluctuates regularly with the change of liquid level.

[0075] Furthermore, according to the principle of electromagnetic induction, when the magnetic flux passing through the outer coil 22 changes, an induced electromotive force signal positively correlated with the rate of change of magnetic flux will be generated at both ends of the coil winding. Specifically, the faster the liquid level changes and the greater the amplitude of the magnetic flux change, the more significant the change in the amplitude (or phase) of the induced electromotive force, meaning that the induced electromotive force signal can accurately reflect the state of liquid level change.

[0076] Furthermore, the lead end of the outer coil 22 is connected to the twisted pair cable, which ensures the stability of the signal transmission link. At the same time, the electromagnetic shielding structure formed by the metal frame 23 and the metal shell 24 reduces the interference of external stray magnetic fields on the induced electromotive force signal, ensuring the purity of the original signal.

[0077] Furthermore, the induced electromotive force signal is transmitted over a long distance to the signal processing unit 3 via a twisted pair cable. The differential transmission characteristics of the twisted pair cable can cancel out common-mode interference encountered during transmission, preventing signal distortion or attenuation. Common-mode interference includes electromagnetic noise generated by equipment operation in high-temperature environments.

[0078] Furthermore, after receiving the induced electromotive force signal, the signal processing unit 3 can further determine the liquid level height value of the liquid metal being measured.

[0079] In an alternative embodiment, the functions of the inner coil 21 and the outer coil 22 can be interchanged, that is, the inner coil 21 is used as an induction coil and the outer coil 22 is used as an excitation coil.

[0080] Specifically, the sinusoidal constant current excitation source 4 is used to output sinusoidal alternating current to the outer coil 22.

[0081] Furthermore, the outer coil 22 generates an alternating magnetic field based on a sinusoidal alternating current, and this alternating magnetic field penetrates the metal casing and acts on the liquid metal being measured. The specific process is described in the functional description of the inner coil 21 above, and will not be repeated here.

[0082] Furthermore, the inner coil 21 is used to generate an induced electromotive force signal based on the change in magnetic flux corresponding to the change in liquid level height when the liquid level height of the measured liquid metal changes, and transmits the induced electromotive force signal to the signal processing unit 3 through a twisted pair. The specific process is described in the functional description of the outer coil 22 above, and will not be repeated here.

[0083] The non-contact liquid level measuring device provided in this embodiment outputs a sinusoidal alternating current to the inner / outer coil via a sinusoidal constant current excitation source, providing stable excitation energy in terms of frequency and amplitude, thus ensuring the stability of the alternating magnetic field. Furthermore, the inner / outer coil generates an alternating magnetic field based on the sinusoidal alternating current, which penetrates the metal casing and acts on the measured liquid metal. This enables effective transmission and penetration of the magnetic field, overcoming the shielding effect of the metal casing and ensuring the interaction between the magnetic field and the measured liquid metal. Further, the outer / inner coil generates an induced electromotive force signal based on the change in magnetic flux corresponding to the liquid level change, and transmits it to the signal processing unit via a twisted pair. This converts the liquid level change into a transmittable electrical signal while suppressing common-mode interference, ensuring the integrity and stability of signal transmission. Finally, the signal processing unit executes a non-contact liquid level measurement method, enabling direct calculation of the liquid level under high-temperature conditions, ensuring the reliability and accuracy of the measurement results.

[0084] According to an embodiment of the present invention, a non-contact liquid level measurement method is provided. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than that shown here.

[0085] This embodiment provides a non-contact liquid level measurement method, which can be used in the signal processing unit 3. Figure 2 This is a flowchart of a non-contact liquid level measurement method according to an embodiment of the present invention, such as... Figure 2 As shown, the process includes the following steps: Step S201: Receive the induced electromotive force signal from the non-contact high-temperature liquid level gauge.

[0086] The induced electromotive force signal is obtained by applying a sinusoidal alternating current to the inner coil 21 or the outer coil 22. The specific process can be found in the functional descriptions of the inner coil 21 and the outer coil 22 described above, and will not be repeated here.

[0087] Step S202: Based on the induced electromotive force signal, the liquid level height value of the liquid metal under test is obtained after processing by the first relational expression.

[0088] In an optional embodiment, the first relation is determined by equating the eddy current effect caused by the change in the liquid level of the measured liquid metal to a coil mutual inductance modulation term, based on the electromagnetic reciprocity theorem and the principle of electromagnetic induction.

[0089] In an optional embodiment, the electromagnetic reciprocity theorem is used to describe the symmetrical interchangeability of electromagnetic responses generated by two different excitation sources in the same electromagnetic system. That is, if the roles of the excitation end and the induction end are interchanged, the final electromagnetic coupling effect of the system (such as mutual inductance and induction signal strength) remains unchanged.

[0090] In one optional embodiment, the principle of electromagnetic induction describes the physical phenomenon that when a conductor is placed in a changing magnetic field, or when a conductor moves in a stationary magnetic field cutting magnetic field lines, an induced electromotive force or induced current is generated in the conductor circuit. Its essence is an energy conversion process from magnetic field energy to electrical energy. The magnitude of the induced electromotive force is directly proportional to the rate of change of magnetic flux.

[0091] In one optional embodiment, the liquid metal under test serves as a conductive medium, and its liquid level change alters the volume it occupies, thereby adjusting the distribution and intensity of the eddy current field induced in the alternating magnetic field. Furthermore, by equating this eddy current effect to the mutual inductance modulation term of a coil system (composed of inner coil 21 and outer coil 22), the physical change in liquid level can be transformed into a change in electromagnetic parameters (mutual inductance), thereby establishing a precise mapping between the physical quantity of liquid level and the electrical signal, i.e., the first relationship.

[0092] Furthermore, based on the induced electromotive force signal, the liquid level height of the measured liquid metal can be calculated using the first relational formula.

[0093] The non-contact liquid level measurement method provided in this embodiment encapsulates a non-contact high-temperature liquid level gauge within a sealed container of the liquid metal being measured, achieving stable installation and sealing of the gauge and avoiding direct corrosion of the sensor by high-temperature and highly corrosive media. Furthermore, by applying a sinusoidal alternating current to the inner or outer coil to obtain an induced electromotive force signal, it overcomes the limitation of the single excitation method in traditional instruments, achieving bidirectional flexible adaptation of coil functions and providing a stable and interference-resistant core electrical signal input for liquid level measurement under extreme conditions. Furthermore, based on the electromagnetic reciprocity theorem and the principle of electromagnetic induction, the eddy current effect caused by the liquid level change of the measured liquid metal is equivalent to the coil mutual inductance modulation term, determining the first relational expression. This overcomes the inherent defects of radar, ultrasonic, and other technologies, such as weak penetration of metal sleeves and dependence on medium characteristics, establishing a precise mapping between the physical quantity of liquid level and the electrical signal. Then, based on the induced electromotive force signal processed by the first relational expression, the liquid level height value is obtained, overcoming the shielding interference of the metal sleeve in principle, realizing direct calculation of liquid level under high-temperature environments, and ensuring the reliability and accuracy of the measurement results. Therefore, by implementing this invention, long-term stable and high-precision non-contact liquid level measurement is achieved in high-temperature, highly corrosive, and highly conductive liquid metal environments.

[0094] In some optional implementations, step S202 above includes: Step S2021: When there is no liquid metal to be measured in the closed tank, obtain the initial coil mutual inductance of the non-contact high temperature level gauge.

[0095] In an optional embodiment, mutual inductance is an inherent electromagnetic parameter generated between two coils due to electromagnetic coupling, and its magnitude is related to the number of coil turns, winding method, relative position and surrounding medium properties.

[0096] Furthermore, when there is no liquid metal being measured in the closed container, only non-conductive media such as air (or vacuum) exist around the coil. At this time, the mutual inductance is not affected by the eddy current effect of the liquid metal and is the reference electromagnetic parameter of the coil system.

[0097] Furthermore, by obtaining the initial coil mutual inductance without liquid metal interference, the influence of the coil's inherent electromagnetic properties on the measurement results can be eliminated.

[0098] In one optional embodiment, it is first ensured that there is no liquid metal being tested inside the sealed tank, and the ambient temperature, air pressure and other conditions of the tank are kept stable in order to avoid environmental factors interfering with the electromagnetic characteristics of the coil.

[0099] Secondly, the sinusoidal constant current excitation source 4 applies a stable sinusoidal alternating current with a preset frequency and amplitude to the inner coil 21.

[0100] Finally, the electromotive force signal induced by the outer coil 22 is detected, and combined with the excitation current parameters, the mutual inductance of the coil system at this time is calculated using the electromagnetic coupling principle, and is defined as the initial coil mutual inductance. .

[0101] Step S2022: When there is liquid metal to be measured in the closed tank, the eddy current effect caused by the change in the liquid level of the liquid metal to be measured is equivalent to the coil mutual inductance modulation term.

[0102] In one optional embodiment, the liquid metal being measured is a conductive medium. When placed in the alternating magnetic field generated by the inner coil, it induces closed eddy currents, forming an eddy current field. Furthermore, changes in the liquid level height alter the volume of space occupied by the liquid metal, thereby adjusting the distribution range and intensity of the eddy current field. The eddy current field generates a reverse magnetic field, which superimposes on the original magnetic field of the inner coil, causing dynamic changes in the mutual inductance of the coil system.

[0103] Furthermore, this change in mutual inductance caused by the eddy current effect due to the change in liquid level can be quantified as a coil mutual inductance modulation term, so as to realize the transformation of the physical change in liquid level into the change in electromagnetic parameters.

[0104] In an optional embodiment, the liquid metal to be measured is injected into the sealed tank, ensuring that the liquid metal does not contact the core components of the level gauge. Furthermore, the sinusoidal constant current excitation source 4 maintains the same excitation parameters (frequency, amplitude) as in step S2021, applying a stable sinusoidal alternating current to the inner coil 21.

[0105] Furthermore, the alternating magnetic field generated by the inner coil 21 penetrates the metal shell and acts on the liquid metal, inducing eddy currents in the liquid metal to form an eddy current field.

[0106] Furthermore, by changing the liquid metal level (e.g., gradually increasing or decreasing it), it was observed that the electromotive force signal induced by the outer coil 22 fluctuated with the liquid level change, indicating that the mutual inductance of the coil system had changed.

[0107] Furthermore, the change in mutual inductance caused by the change in liquid level is defined as the coil mutual inductance modulation term. ,Right now Liquid level The function.

[0108] Step S2023: Establish the first mutual inductance relationship based on the initial coil mutual inductance and the coil mutual inductance modulation term.

[0109] In an alternative embodiment, the initial mutual inductance without liquid metal This is the reference value of the coil system. When liquid metal is present, the total mutual inductance of the coil system is formed by the superposition of the reference mutual inductance and the mutual inductance modulation term caused by the liquid level. Furthermore, the total mutual inductance varies with the liquid level height. Therefore, the first mutual inductance relationship can be formed through the mathematical relationship between the initial mutual inductance and the mutual inductance modulation term, as shown in the following relationship (1): (1) In the formula: Indicates the liquid level height as The total mutual inductance of the time coil system.

[0110] Step S2024: Based on the first mutual inductance relationship and the coil mutual inductance modulation term, the first relationship between the induced electromotive force and the liquid level is established using the electromagnetic field reciprocity theorem and the principle of electromagnetic induction.

[0111] Specifically, step S2024 above includes: Step a1: Based on the first mutual inductance relationship, the electromagnetic reciprocity theorem is used to transform the coil mutual inductance modulation term into the electric field integral form within the volume of the liquid metal being measured, and the second mutual inductance relationship is determined.

[0112] In an optional embodiment, by analyzing the integral relationship between the electric field induced in the liquid metal when only the inner coil is energized and the electric field induced in the liquid metal when only the outer coil is energized within the volume of the liquid metal, the mutual inductance modulation term and the liquid level height can be determined. The direct correlation is that the liquid level change will change the integration region, which allows us to derive the second mutual inductance relationship.

[0113] In an optional embodiment, based on the first mutual inductance relation, the coil mutual inductance modulation term is derived using the electromagnetic reciprocity theorem. The quantitative expression, namely the second mutual inductance relation, is shown in the following relation (2): (2) In the formula: This indicates that only the excitation coil carries current. The electric field induced in liquid metal; This indicates that only the current flowing through the coil is being detected. The electric field generated by time; This indicates the volume of liquid metal.

[0114] Step a2: Based on the principle of electromagnetic induction, determine the second relationship between induced electromotive force and mutual inductance.

[0115] In an optional embodiment, based on the principle of electromagnetic induction, the induced electromotive force of the detection coil is determined by the rate of change of magnetic flux. Further, combining the relationship between mutual inductance and magnetic flux, a second relationship between the induced electromotive force and mutual inductance is derived, as shown in the following equation (3): (3) In the formula: This indicates the induced electromotive force in the detection coil; This represents the imaginary unit, and its core meaning is consistent with the imaginary unit in complex number operations in mathematics, satisfying the following... It is used to describe the phase characteristics of induced electromotive force and is adapted to the periodic variation law of alternating electromagnetic field. This represents the angular frequency of the excitation current.

[0116] Step a3: Based on preset conditions, establish the first relationship between induced electromotive force and liquid level according to the second mutual inductance relationship and the second relationship.

[0117] In an alternative embodiment, by setting a virtual current By simplifying the calculation and utilizing the condition of uniform magnetic field on the outer pipe wall, the volume integral is transformed into a cross-sectional integral in the height direction, and finally the complex integral terms are eliminated. Thus, a direct linear (or quantitative) relationship between induced electromotive force and liquid level height can be established, namely the first relationship.

[0118] In an optional embodiment, substituting the second mutual inductance relation shown in relation (2) into relation (3) shown in relation (3) above, we can obtain the following relation (4): (4) Furthermore, in practice, It is a virtual current, which can be set. For calculation purposes. When the magnetic field around the outer pipe wall is uniform, the induced electromotive force of the detection coil is related to the liquid level. The first relation is shown in relation (5) below: (5) In the formula: Indicates height Cross-sectional integral at the point.

[0119] In some optional implementations, the above method further includes: Step b1: Obtain the real-time temperature dataset of the non-contact high-temperature level gauge and the enclosed tank.

[0120] In one optional embodiment, the real-time temperature dataset represents a set of multi-dimensional temperature data that is strongly correlated with measurement accuracy and is collected in real time by a temperature sensor (such as a high-temperature resistant sensor like PT100) built into the non-contact high-temperature level gauge. This data may include the real-time temperatures of the metal frame, inner and outer coils, metal shell, as well as the real-time temperatures of the internal space of the tank and the surrounding area of ​​the liquid metal being measured.

[0121] In one alternative embodiment, high-temperature environments (0-800°C) can cause changes in multi-dimensional parameters, which in turn can lead to errors in liquid level measurement.

[0122] Specifically, the coil resistance increases with increasing temperature (the temperature coefficient of resistance of pure nickel wire is positive), causing fluctuations in the excitation magnetic field strength; furthermore, the permeability of the stainless steel frame / shell changes with temperature, altering the magnetic field propagation path and magnetic flux coupling efficiency; furthermore, the conductivity of liquid metals decreases with increasing temperature (e.g., the conductivity of liquid sodium decreases linearly with increasing temperature), affecting the eddy current field strength and mutual inductance modulation term.

[0123] Furthermore, by collecting temperature data in real time, the source of the above parameter changes can be captured, providing data support for targeted compensation and thus avoiding systematic errors caused by temperature drift.

[0124] In one optional embodiment, a high-temperature resistant temperature sensor is embedded in the metal frame (close to the coil), the inner wall of the metal shell, and the reserved interface of the sealed tank of the non-contact high-temperature liquid level gauge. The temperature acquisition is triggered synchronously with the level measurement. That is, before each excitation current is applied to the inner coil, the signal processing unit 3 sends a command to start all sensors to collect real-time temperature.

[0125] Step b2: Based on the real-time temperature dataset, the liquid level height value is corrected using a preset temperature error correction model.

[0126] In one optional embodiment, the preset temperature error correction model represents a mathematical model based on experimental calibration and theoretical derivation, which quantifies the correlation between temperature change and measurement error. Its core is to construct an error compensation formula or mapping curve by pre-testing the deviation between the measured liquid level value and the true value at different temperatures within the full temperature range of 0-800℃, and combining this with the influence of temperature on coil resistance, dielectric conductivity, and material permeability.

[0127] In one optional embodiment, a preset temperature error correction model has been experimentally verified to quantify the complete chain of changes in coil resistance → magnetic field strength deviation → induced electromotive force error → liquid level calculation deviation under different temperatures. Therefore, based on the real-time temperature dataset, this model can be used to calculate the liquid level error compensation amount corresponding to the current temperature. Furthermore, this compensation amount is superimposed on the original liquid level height value, which can offset the systematic deviation caused by temperature, making the corrected liquid level value closer to the true value.

[0128] For example, when the temperature rises to 600℃, the coil resistance increases, causing the magnetic field strength to decrease. The original liquid level measurement value is 0.5% lower than the true value. A compensation of +0.5% can be calculated through a preset temperature error correction model, and the accuracy is restored to better than 2% after correction.

[0129] In some alternative implementations, the sinusoidal alternating current in step S201 is adjusted according to the conductivity of the liquid metal being measured and the thickness of the casing of the sealed tank.

[0130] In one alternative embodiment, the skin depth of the alternating magnetic field, i.e., the effective depth to which the magnetic field can penetrate the conductor, is negatively correlated with the current frequency. Specifically, the lower the frequency, the greater the skin depth; the higher the frequency, the smaller the skin depth.

[0131] Furthermore, the thickness of the sleeve of the sealed tank directly determines the thickness of the conductor that the magnetic field needs to penetrate. Therefore, by adjusting the frequency to make the skin depth suitable for the sleeve thickness, it can be ensured that the magnetic field is not excessively attenuated by the sleeve.

[0132] Furthermore, the higher the conductivity of the liquid metal, the stronger the eddy current field induced in the alternating magnetic field, and the more significant the modulation effect on the mutual inductance of the coil. However, excessively high conductivity may also cause the magnetic field to concentrate on the surface of the liquid metal (enhanced skin effect). It is necessary to balance the eddy current intensity and the magnetic field penetration depth by adjusting the frequency to avoid distortion of the induced signal due to excessively strong or weak eddy currents.

[0133] Furthermore, the current frequency must be adapted to the sleeve thickness (magnetic field penetration requirements and liquid metal conductivity (eddy current modulation requirements) so that the alternating magnetic field can penetrate the sleeve to reach the liquid metal and generate a stable eddy current field in the liquid metal, thereby ensuring the electromagnetic coupling efficiency between the coils.

[0134] Therefore, in this embodiment, by adjusting the sinusoidal alternating current according to the conductivity of the liquid metal being measured and the thickness of the sleeve of the sealed tank, the skin depth of the electromagnetic field can be optimized, ensuring that the alternating magnetic field effectively penetrates the metal sleeve. This allows for adaptation to different media and tank structures, thereby improving the signal-to-noise ratio and measurement reliability.

[0135] In one example, a non-contact high-temperature liquid level gauge method is provided. The liquid level gauge consists of an inner coil, an outer coil, a metal casing, and a sealed tank. The coils are all wound with a stainless steel frame and high-temperature resistant pure nickel wire, and are embedded within the liquid metal tank. By applying an adjustable frequency excitation signal, a correspondence model between the liquid level height and the induced voltage is established using the electromagnetic field reciprocity relationship, effectively overcoming the shielding effect of the metal casing on the electromagnetic field, and achieving accurate liquid level detection through the casing. This device can operate stably for extended periods in high-temperature environments of 0–800℃, supports continuous measurement over a wide range of up to 2m, and has an overall accuracy better than 2%. The system, through frequency optimization and temperature compensation mechanisms, suppresses measurement errors introduced by high temperature and the casing, making it suitable for liquid level monitoring under highly corrosive and high-permeability conditions. It has significant application value in nuclear sodium-cooled fast reactors, high-temperature molten salt storage tanks, and the metallurgical industry.

[0136] In an alternative example, based on the electromagnetic reciprocity theorem, the electromagnetic induction liquid level measurement method is derived as follows: To describe the disturbance effect of liquid metal on the magnetic field, this study equates the eddy current effect caused by the liquid level to a modulation term on the mutual inductance of the system. Let the mutual inductance without liquid metal be... When liquid metal is present, the mutual inductance changes as follows: Mutual inductance caused by liquid level The value is determined by the liquid level. According to the electromagnetic reciprocity theorem, It can be expressed as the above relation (2).

[0137] Furthermore, due to changes in liquid level, the integration region Change, therefore dependent Therefore, the induced electromotive force of the detection coil is given by the above relationship (3).

[0138] Furthermore, substituting the above relation (2) into the above relation (3) yields the above relation (4).

[0139] Furthermore, in practice, It is a virtual current, which can be set. For calculation purposes. When the magnetic field around the outer pipe wall is uniform, the induced electromotive force of the detection coil is related to the liquid level. The relationship is given by the above relation (5).

[0140] In an optional instance, such as Figure 3 As shown, the non-contact high-temperature liquid level gauge in the above example has a core sensing unit mainly composed of a metal frame A, a metal shell B, an inner coil C, an outer coil D, and a fixed flange E.

[0141] The metal frame A is a cylindrical solid or hollow stainless steel tube, serving as the core support for the entire coil assembly. The inner coil C is made of high-temperature resistant pure nickel wire, tightly and evenly wound on the outer surface of the metal frame A. The outer coil D also uses pure nickel wire, wound around the outside of the inner coil C, maintaining insulation and a tight fit. The metal outer shell B is a hollow cylindrical stainless steel tube, tightly fitted around the outer coil D, forming a complete electromagnetic shielding and mechanical protection enclosure with the metal frame A, effectively isolating external magnetic field interference and harsh environmental corrosion. The sensing unit is fixed to the reserved interface of the liquid metal tank via the fixing flange E at the upper end of the metal frame A and matching screws and nuts, allowing the lower part of the sensing unit to be immersed in the tank space without contact with the liquid metal. It should be noted that the inner and outer coils are interchangeable; the following description uses the inner coil C as the excitation coil and the outer coil D as the induction coil as an example.

[0142] Measurement process: Step 1: Apply a sinusoidal alternating current with stable frequency and amplitude to the inner coil C. The frequency of this current can be optimized based on the conductivity of the liquid metal being measured and the thickness of the tank casing, typically in the range of several hundred hertz to several thousand hertz, to ensure that the alternating magnetic field can effectively penetrate the metal casing B and act on the liquid being measured. The excitation current source should have constant current characteristics to maintain magnetic field stability.

[0143] Step 2: The alternating magnetic field generated by the inner coil C penetrates the metal outer shell B, forming a working magnetic circuit in its external space. When the liquid metal level changes, it alters the distribution of the eddy current field, thereby modulating the magnetic flux passing through the outer coil D.

[0144] Step 3: An induced electromotive force (EMF) will be generated at both ends of the outer coil D due to the change in magnetic flux. This induced EMF signal is led out to the signal processing unit at the back end through a twisted pair cable (to suppress common-mode interference). The signal processing unit detects the change in the amplitude (or phase) of this induced EMF.

[0145] Step 4: The signal processing unit converts the measured signal value into a precise liquid level height value based on the "change in induced electromotive force - liquid level height" relationship curve established in advance through theoretical calculation or experimental calibration using the above-mentioned relationship (5). Furthermore, the volume, mass, and other derived parameters of the liquid can be calculated by combining the geometric dimensions of the tank.

[0146] This example provides a non-contact high-temperature liquid level gauge method, which has the following advantages: (1) This example can fundamentally avoid direct contact between the sensor and high-temperature, highly corrosive liquid metal, solving the problem of easy corrosion and damage of traditional contact instruments. This method has strong anti-interference ability and high measurement accuracy. In an environment of 0-800℃ and within a 2m range, the accuracy is stable and better than 2%.

[0147] (2) In this example, the inner and outer coils of the liquid level gauge are wound with high temperature resistant pure nickel wire, and the core structure is made of stainless steel, which ensures that the entire sensing unit can still work stably for a long time in a high temperature environment of 800℃.

[0148] (3) The level gauge in this example. The integrated electromagnetic shielding structure formed by the metal shell and the frame can effectively suppress external stray magnetic field interference. At the same time, the electromagnetic field skin depth is adjusted by frequency optimization technology, so that it can effectively penetrate the metal sleeve wall and overcome the inherent defects of radar, ultrasonic and other technologies with large signal attenuation when facing metal shields.

[0149] (4) The level gauge in this example uses a sinusoidal constant current excitation source with adjustable frequency and amplitude. It can actively adapt to fluids with different conductivity, metal sleeves with different thicknesses and tanks of different sizes by flexibly adjusting the excitation parameters (such as frequency, current and number of coil turns). It has strong versatility and is easy to promote in engineering.

[0150] (5) The liquid level gauge structure in this example has the characteristics of wide measurement range and easy installation, and can be flexibly applied to closed tanks and conductive fluids of different sizes.

[0151] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A non-contact liquid level measurement method, characterized in that, A signal processing unit is used, the signal processing unit being connected to a non-contact high-temperature liquid level gauge, the non-contact high-temperature liquid level gauge being encapsulated in a sealed container of the liquid metal being measured, the non-contact high-temperature liquid level gauge including an inner coil and an outer coil; the method includes: The non-contact high-temperature liquid level gauge receives the induced electromotive force signal, which is obtained by applying a sinusoidal alternating current to the inner coil or the outer coil. Based on the induced electromotive force signal, the liquid level height value of the measured liquid metal is obtained after processing by the first relational expression. The first relational expression is determined by equating the eddy current effect caused by the liquid level change of the measured liquid metal to a coil mutual inductance modulation term based on the electromagnetic field reciprocity theorem and the principle of electromagnetic induction.

2. The method according to claim 1, characterized in that, The method further includes: When there is no liquid metal to be measured in the closed tank, the initial coil mutual inductance of the non-contact high temperature level gauge is obtained. When the liquid metal to be tested is in a closed tank, the eddy current effect caused by the change in the liquid level of the liquid metal to be tested is equivalent to the mutual inductance modulation term of the coil. A first mutual inductance relationship is established based on the initial coil mutual inductance and the coil mutual inductance modulation term; Based on the first mutual inductance relationship and the coil mutual inductance modulation term, the first relationship between the induced electromotive force and the liquid level is established using the electromagnetic field reciprocity theorem and the principle of electromagnetic induction.

3. The method according to claim 2, characterized in that, Based on the first mutual inductance relationship and the coil mutual inductance modulation term, using the electromagnetic field reciprocity theorem and the principle of electromagnetic induction, a first relationship between the induced electromotive force and the liquid level is established, including: Based on the first mutual inductance relationship, the electromagnetic field reciprocity theorem is used to transform the coil mutual inductance modulation term into the electric field integral form within the volume of the liquid metal being measured, and the second mutual inductance relationship is determined. Based on the electromagnetic induction principle, a second relationship between induced electromotive force and mutual inductance is determined. Based on preset conditions, and according to the second mutual inductance relationship and the second relationship, the first relationship between induced electromotive force and liquid level is established.

4. The method according to claim 1, characterized in that, The method further includes: Obtain the real-time temperature dataset of the non-contact high-temperature level gauge and the enclosed tank; Based on the real-time temperature dataset, the liquid level height value is corrected using a preset temperature error correction model.

5. The method according to claim 1, characterized in that, The sinusoidal alternating current is adjusted according to the conductivity of the liquid metal being measured and the thickness of the sleeve of the sealed tank.

6. A non-contact liquid level measuring device, characterized in that, The device includes: a non-contact high-temperature liquid level gauge, a signal processing unit, and a sinusoidal constant current excitation source. The non-contact high-temperature liquid level gauge is encapsulated in a closed tank containing the liquid metal being measured. The non-contact high-temperature liquid level gauge includes an inner coil, an outer coil, and a metal casing. The signal processing unit is used to execute the non-contact liquid level measurement method according to any one of claims 1 to 5. The sinusoidal constant current excitation source is used to output a sinusoidal alternating current to the inner coil; The inner coil is used to generate an alternating magnetic field based on the sinusoidal alternating current, and to apply the alternating magnetic field to the liquid metal under test after penetrating the metal shell; The outer coil is used to generate an induced electromotive force signal based on the change in magnetic flux corresponding to the change in liquid level height when the liquid level height of the measured liquid metal changes, and to transmit the induced electromotive force signal to the signal processing unit through a twisted pair. or, The sinusoidal constant current excitation source is used to output a sinusoidal alternating current to the outer coil; The outer coil is used to generate an alternating magnetic field based on the sinusoidal alternating current, and to apply the alternating magnetic field to the liquid metal under test after penetrating the metal shell; The inner coil is used to generate an induced electromotive force signal based on the change in magnetic flux corresponding to the change in liquid level height when the liquid level height of the measured liquid metal changes, and to transmit the induced electromotive force signal to the signal processing unit through a twisted pair.

7. The apparatus according to claim 6, characterized in that, The device further includes a fixed flange, wherein the non-contact high-temperature liquid level gauge is tightly fitted and fixed to the closed tank body through the fixed flange, and the lower part of the non-contact high-temperature liquid level gauge is immersed in the tank space and does not come into contact with the liquid metal being measured.

8. The apparatus according to claim 6, characterized in that, The non-contact high-temperature level gauge also includes a metal frame, which together with the metal shell constitutes an electromagnetic shielding and mechanical protection structure. The inner coil is wound on the outer surface of the metal frame, and the outer coil is wound on the outside of the inner coil and is insulated and attached to the inner coil.

9. The apparatus according to claim 8, characterized in that, Both the metal frame and the metal shell are made of stainless steel. The metal frame is a cylindrical metal frame, and the metal shell is a cylindrical metal shell.

10. The apparatus according to claim 6, characterized in that, Both the inner coil and the outer coil are made of pure nickel wire.

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