Non-contact conductive fluid flow measuring device

Abstract

The invention relates to the technical field of liquid flow measurement, and discloses a non-contact conductive fluid flow measurement device, which comprises a flow passing pipeline, an inner cavity of which is suitable for the circulation of a conductive fluid; the magnet exciting coil is arranged on one side of the overflowing pipeline, and the axis of the magnet exciting coil is perpendicular to the axis of the overflowing pipeline; at least one pair of induction coils are arranged, the induction coils and the magnet exciting coils are arranged on the two sides of the overflowing pipeline respectively, and the induction coils arranged in pairs are symmetrically arranged relative to the axes of the magnet exciting coils; each of the excitation coil and the induction coil comprises a high-temperature-resistant insulation framework and a high-temperature-resistant metal wire wound on the high-temperature-resistant insulation framework. The magnet exciting coil and the induction coil are arranged outside the overflowing pipeline, meanwhile, the magnet exciting coil and the induction coil both adopt the high-temperature-resistant insulating frameworks and the high-temperature-resistant metal wires, and it is ensured that the flow measuring device can conduct flow monitoring on high-temperature and corrosive conductive fluid for a long time; and the flow monitoring accuracy of the flow measuring device is ensured.

Description

Technical Field

[0001] This invention relates to the field of liquid flow measurement technology, and more specifically to a non-contact conductive fluid flow measurement device. Background Technology

[0002] With the increasing demand for precise fluid measurement in modern industrial process control, electromagnetic flowmeters based on Faraday's law of electromagnetic induction have become core instruments for measuring the flow of conductive fluids in petroleum, chemical, metallurgical, and power industries due to their advantages such as no obstruction components, high measurement accuracy, and fast response speed. They work by establishing a magnetic field within the measuring pipe, causing the conductive fluid to cut magnetic field lines and generate an induced electromotive force (EMF) as it flows through the field. The flow rate is then detected by the direct proportionality between the EMF and the fluid velocity.

[0003] However, traditional electromagnetic flowmeters generally employ a contact measurement method, where electrodes are embedded on both sides of the inner wall of the pipe, directly contacting the fluid to collect induced electromotive force signals. Because the electrodes are directly exposed to the fluid, they are susceptible to impacts from impurities or air bubbles, generating spike noise and causing signal distortion. Furthermore, in high-temperature or corrosive media, the electrodes are prone to electrochemical corrosion, which not only shortens the sensor's lifespan but also causes signal drift and decreased stability. This results in significant measurement errors when electromagnetic flowmeters measure high-temperature, corrosive fluids, making accurate measurement of conductive fluids in high-temperature environments difficult. Summary of the Invention

[0004] In view of this, the present invention provides a non-contact conductive fluid flow measurement device to solve the problem that electromagnetic flowmeters in the prior art have large errors when measuring the flow of high-temperature and corrosive conductive fluids.

[0005] In a first aspect, the present invention provides a non-contact conductive fluid flow measurement device, comprising: A flow passageway, the inner cavity of which is suitable for the flow of conductive fluids; An excitation coil is disposed on one side of the flow pipe, and the axis of the excitation coil is perpendicular to the axis of the flow pipe. The induction coil is provided in at least one pair, and the induction coil and the excitation coil are respectively disposed on both sides of the flow pipe. The pair of induction coils are arranged symmetrically with respect to the axis of the excitation coil. Both the excitation coil and the induction coil include a high-temperature resistant insulating frame and a high-temperature resistant metal wire wound on the high-temperature resistant insulating frame.

[0006] When the flow measurement device is working, an alternating current is passed through the excitation coil, establishing an alternating magnetic field inside the flow pipe. When the conductive fluid flows through the alternating magnetic field region, it cuts the magnetic field lines, generating an induced electromotive force related to the flow velocity and forming a secondary magnetic field. The two induction coils arranged in pairs are symmetrically distributed relative to the axis of the excitation coil, inducing an alternating voltage signal containing flow information in the secondary magnetic field. There is a phase difference and amplitude difference between the signals output by the two induction coils that are specifically related to the flow velocity. By detecting and calculating the signal difference of the induced electromotive force on the two induction coils, and combining it with the pre-calibrated mapping relationship, the flow velocity, flow direction, and flow rate information of the fluid can be determined. Both the excitation coil and the induction coil adopt a composite structure of high-temperature resistant insulating frame and high-temperature resistant metal wire, which enables the excitation coil and the induction coil to maintain structural integrity and electromagnetic performance stability in high-temperature environments, thereby realizing non-contact continuous measurement of high-temperature conductive fluids. By arranging the excitation coil and induction coil outside the flow pipe, instead of directly contacting the conductive fluid inside the flow pipe, and by using high-temperature resistant insulating frames and high-temperature resistant metal wires for both the excitation coil and induction coil, the flow measurement device can continuously monitor the flow of high-temperature and corrosive conductive fluid in real time for a long period of time, ensuring the accuracy of the flow measurement device.

[0007] In one optional embodiment, the high-temperature resistant insulating skeleton is a ceramic skeleton, and the high-temperature resistant metal wire is a copper wire with an aluminum oxide insulating layer on its surface.

[0008] The high-temperature resistant insulating frame of the excitation coil and induction coil is made of ceramic, providing mechanical support and electrical insulation. Meanwhile, the high-temperature resistant metal wires are made of copper wire with an alumina-plated insulating layer, maintaining conductivity in high-temperature environments and ensuring stable operation of the excitation coil and induction coil in alternating magnetic fields without short circuits or degradation. The combination of the ceramic frame and alumina-plated copper wire enables the excitation coil and induction coil to withstand temperatures up to 800℃, avoiding the oxidation and corrosion problems of traditional electrode materials at high temperatures, improving the durability and reliability of the measuring device, and ensuring long-term stable operation under extreme conditions.

[0009] In an alternative embodiment, a metal housing is also included, with both the excitation coil and the induction coil mounted inside the cavity of the metal housing.

[0010] The metal casing completely encloses the excitation coil and induction coil within its inner cavity. The metal casing fits tightly with the outside of the flow pipe, forming a physical protective layer that prevents external foreign objects or environmental factors from directly contacting the excitation coil and induction coil. At the same time, the conductivity of the metal casing helps to guide and shield external electromagnetic interference, reducing the impact of external magnetic fields and environmental noise on the signals of the excitation coil and induction coil. This improves the purity and accuracy of the flow measurement signal and enhances the applicability of the device in complex industrial environments.

[0011] In one optional embodiment, the metal housing includes an upper half-shell and a lower half-shell. The upper half-shell and the flow pipe enclose an upper mounting cavity, and the lower half-shell and the flow pipe enclose a lower mounting cavity. The induction coil is installed in the upper mounting cavity, and the excitation coil is installed in the lower mounting cavity. The upper half-shell and the lower half-shell are fixedly connected.

[0012] The upper and lower halves of the casing are respectively fitted to the outer wall of the flow pipe, forming independent upper and lower mounting cavities. The induction coil is fixed in the upper mounting cavity, and the excitation coil is fixed in the lower mounting cavity. The upper and lower halves are connected by fasteners such as screws and nuts, ensuring the overall structure of the metal casing is stable and sealed to the flow pipe. The split-type metal casing is easy to disassemble, facilitating the installation and maintenance of the excitation and induction coils, while ensuring the accuracy and stability of the coil installation position and the symmetry of the magnetic field distribution, thereby improving the repeatability and accuracy of flow measurement.

[0013] In an optional embodiment, a signal processing module is also included, wherein the high-temperature resistant metal wires of the induction coils extend to be connected to the signal processing module, and the signal processing module is used to receive and calculate the induced electromotive force difference on the pairs of induction coils, and calculate the flow rate of the conductive fluid in the flow pipe based on the induced electromotive force difference.

[0014] The high-temperature resistant metal wires of the induction coils are directly connected to the signal processing module. The signal processing module acquires the induced electromotive force signals generated by the paired induction coils in real time. By comparing the differences between these signals and applying a preset algorithm, the induced electromotive force difference is converted into the flow velocity and volumetric flow rate of the conductive fluid in the pipe. The signal processing module enables automatic processing and real-time output of flow data, reducing manual intervention and calculation errors, improving measurement efficiency and accuracy, and allowing the device to adapt to different fluid characteristics, thus enhancing the intelligence and applicability of flow measurement.

[0015] In one alternative embodiment, the high-temperature resistant metal wire of the induction coil is led out in the form of a twisted pair, and the ends of the twisted pair are electrically connected to the signal processing module.

[0016] The high-temperature resistant metal wires of the induction coil are twisted-pair wires during the lead-out process. This means the wires are tightly twisted together in pairs, and the ends of the twisted-pair wires are directly conductively connected to the input of the signal processing module. The twisted-pair structure forms a balanced loop in the signal transmission path, effectively canceling common-mode interference. The twisted-pair wires reduce electromagnetic interference and noise introduction during the transmission of the induced electromotive force signal, improving the signal-to-noise ratio and transmission reliability, thereby ensuring the accuracy and stability of the flow measurement data.

[0017] In one optional embodiment, a variable frequency excitation power supply is further included, electrically connected to the excitation coil, the variable frequency excitation power supply being used to provide the excitation coil with adjustable frequency AC power, the output frequency range of the variable frequency excitation power supply being 50Hz to 800Hz.

[0018] The variable frequency excitation power supply is electrically connected to the excitation coil via a cable, outputting an adjustable frequency sinusoidal alternating current to the excitation coil. Depending on the type of conductive fluid and flow conditions within the pipeline, the output frequency is adjusted within the range of 50Hz to 800Hz to optimize the excitation magnetic field strength and distribution. The variable frequency excitation power supply allows the device to flexibly adapt to the measurement needs of different conductive fluids, obtaining optimal signal output through frequency adjustment, improving the adaptability and accuracy of flow measurement, while avoiding signal attenuation or distortion at a fixed frequency.

[0019] In one alternative embodiment, the inner cross-section of the flow passage is circular.

[0020] When conductive fluid flows within a circular inner cavity, a uniform velocity distribution is achieved. The circular structure matches the magnetic field distribution of the excitation and induction coils, ensuring symmetry and consistency as the magnetic field penetrates the pipe wall. The circular flow pipe simplifies the flow pattern of conductive fluid and the calculation of magnetic fields, improving the convenience and accuracy of flow calibration. Simultaneously, it reduces fluid flow resistance and turbulence effects, making measurement results more reliable.

[0021] In one alternative embodiment, the axis of the induction coil, the axis of the excitation coil, and the axis of the flow passage are coplanar.

[0022] The axes of the induction coil, the excitation coil, and the flow pipe are all located in the same plane, ensuring that the alternating magnetic field generated by the excitation coil and the induced field of the induction coil are spatially symmetrically aligned, thus optimizing the interaction between the magnetic field and the fluid. This coplanar design ensures spatial consistency between the magnetic field and the induced signal, reducing measurement errors and signal asymmetry, and improving the accuracy of flow measurement.

[0023] In one alternative embodiment, the induction coil is arranged parallel to the flow channel. This aligns the plane of the induction coil with the direction of fluid flow, allowing the coil to more effectively capture the induced electromotive force when the magnetic field changes, and to generate coordinated electromagnetic coupling with the fluid flow. This improves the strength and clarity of the induced signal, thereby enhancing the sensitivity and resolution of flow measurement. Attached Figure Description

[0024] 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.

[0025] Figure 1 This is a schematic diagram of the structure of a non-contact conductive fluid flow measurement device provided in an embodiment of the present invention.

[0026] Explanation of reference numerals in the attached diagram: 1. Excitation coil; 2. Induction coil; 3. Metal casing; 4. Flow pipe. 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] The following is combined Figure 1 The following describes embodiments of the present invention.

[0029] According to an embodiment of the present invention, a non-contact conductive fluid flow measurement device is provided, comprising a flow pipe 4, an excitation coil 1, and at least one pair of induction coils 2. The inner cavity of the flow pipe 4 is used for the flow of conductive fluid. The excitation coil 1 is used to generate an excitation magnetic field, and the axis of the excitation coil 1 is arranged on one side of the flow pipe 4, perpendicular to the axis of the flow pipe 4. The induction coils 2 are disposed on the other side of the flow pipe 4, located on opposite sides of the excitation coil 1, with each pair of induction coils 2 arranged symmetrically with respect to the axis of the excitation coil 1. Both the excitation coil 1 and the paired induction coils 2 include a high-temperature resistant insulating frame and high-temperature resistant metal wire wound on the high-temperature resistant insulating frame. The high-temperature resistant insulating frame provides structural support for the coils and ensures insulation performance between the coil windings. The high-temperature resistant metal wire wound on the high-temperature resistant insulating frame forms an electromagnetic induction winding.

[0030] When measuring the flow rate of a high-temperature and corrosive conductive liquid using a non-contact conductive fluid flow measurement device, an alternating current with stable frequency and amplitude is passed through the excitation coil 1. Under the excitation of the alternating current, the excitation coil 1 establishes an alternating magnetic field in the fluid flow region inside the flow pipe 4. When the conductive fluid flows through this alternating magnetic field region at a certain flow rate, the conductive particles in the conductive fluid cut the magnetic field lines, generating an induced electromotive force (EMF) proportional to the flow velocity inside the conductive fluid. The induced EMF further excites a secondary magnetic field related to the fluid flow. The two induction coils 2, arranged in pairs, are symmetrically distributed relative to the axis of the excitation coil 1. The windings of the two induction coils 2 respectively induce alternating voltage signals containing fluid flow velocity information in the secondary magnetic field. There is an interaction between the induced EMF signals output by the two induction coils 2 and the fluid flow velocity. The phase difference and amplitude difference of the flow velocity are in a specific functional relationship; the signal processing unit detects and collects the induced electromotive force signals generated on the two pairs of induction coils 2, calculates the phase difference and amplitude difference between the two induced electromotive force signals, and combines them with the mapping relationship database between the fluid flow velocity and the difference of the induced signal established in advance through experimental calibration. After interpolation and data processing, the flow velocity, flow direction and volumetric flow rate information of the conductive fluid flowing through the flow pipe 4 are finally determined; the excitation coil 1 and the paired induction coils 2 are both made of high-temperature resistant insulating skeleton and high-temperature resistant metal wire composite high-temperature resistant structure. The high-temperature resistant structure enables the excitation coil 1 and the induction coil 2 to maintain structural integrity and electromagnetic performance stability in a continuous high-temperature working environment, thereby realizing non-contact continuous real-time measurement of high-temperature conductive fluid.

[0031] By arranging the excitation coil 1 and the paired induction coils 2 outside the flow pipe 4, the excitation coil 1 and the paired induction coils 2 do not directly come into physical contact with the conductive fluid inside the flow pipe 4. At the same time, both the excitation coil 1 and the paired induction coils 2 adopt a composite high-temperature resistant structure made of a high-temperature resistant insulating frame and a high-temperature resistant metal wire. This ensures that the non-contact conductive fluid flow measurement device can continuously monitor the flow of conductive fluids with high-temperature and corrosive characteristics in real time for a long time. This effectively avoids the conductive fluid from causing corrosion damage or high-temperature damage to the excitation coil 1 and the paired induction coils 2, and ensures the accuracy, reliability and long-term stability of the flow monitoring of the non-contact conductive fluid flow measurement device.

[0032] In one embodiment, the high-temperature resistant insulating skeleton is a ceramic skeleton, which is made of high-purity alumina ceramic material sintered at high temperature and has a dense polycrystalline structure; the high-temperature resistant metal wire is a copper wire with an alumina insulating layer on its surface. After the copper wire is drawn and shaped, an alumina insulating layer is uniformly coated on its surface by chemical vapor deposition process. Then, the copper wire with the alumina insulating layer is tightly wound in the winding groove of the ceramic skeleton to form a coil winding.

[0033] The ceramic skeleton, as a high-temperature resistant insulating skeleton, provides a rigid support structure for the copper wires with an alumina insulating layer. The copper wires with an alumina insulating layer are wound on the ceramic skeleton according to a predetermined number of turns and layers. The ceramic skeleton and the copper wires with an alumina insulating layer together constitute the high-temperature resistant insulating structure of the excitation coil 1 and the induction coil 2, so that the excitation coil 1 and the induction coil 2 can maintain electrical insulation performance and structural integrity in extreme high-temperature environments. The combination of a ceramic frame and copper wires with an alumina-plated insulation layer gives the excitation coil 1 and induction coil 2 excellent high-temperature performance. The ceramic frame has excellent high-temperature mechanical strength and electrical insulation properties, and can maintain shape stability in a high-temperature environment of 800℃. The copper wires with an alumina-plated insulation layer have reliable high-temperature insulation properties and good conductivity. The alumina insulation layer can remain stable in a high-temperature environment of 800℃. The coil structure formed by the combination of the two can operate stably for a long time in a high-temperature environment of 800℃ without structural deformation or insulation failure. This avoids the problems of insulation carbonization and wire oxidation degradation of traditional enameled coils at high temperatures, significantly broadens the temperature application range of the flow measurement device, and ensures that the measurement accuracy is not affected by the high-temperature environment, enabling the device to be used in extreme conditions such as high-temperature molten metal and hot oil.

[0034] In one embodiment, the non-contact conductive fluid flow measurement device further includes a metal housing 3, in which the excitation coil 1 and the induction coil 2 are integrally installed in the inner cavity of the metal housing 3. The metal housing 3 completely covers the excitation coil 1 and the induction coil 2, and the housing of the metal housing 3 forms an electromagnetic shielding layer to isolate the stray magnetic field in the external space from the excitation coil 1 and the induction coil 2. At the same time, the inner wall of the metal housing 3 is tightly attached to the outer wall of the flow pipe 4 to form a closed electromagnetic shielding cavity.

[0035] The metal casing 3 provides physical protection for the excitation coil 1 and the induction coil 2. More importantly, the electromagnetic shielding of the metal casing 3 effectively blocks external electromagnetic interference from affecting the signal acquisition of the induction coil 2. This allows the flow measurement device to maintain the stability and accuracy of the measurement signal in industrial environments with strong electromagnetic interference, improving the device's environmental adaptability and anti-interference capabilities. The metal casing 3 also provides mechanical protection, preventing dust, moisture, and other environmental factors from corroding the coil windings. It prevents external foreign objects or environmental factors from directly contacting the excitation coil 1 and the induction coil 2. At the same time, the conductivity of the metal casing 3 helps guide and shield external electromagnetic interference, reducing the impact of external magnetic fields and environmental noise on the signals of the excitation coil 1 and the induction coil 2, improving the purity and accuracy of the flow measurement signal, and enhancing the device's applicability in complex industrial environments.

[0036] In one embodiment, the metal housing 3 adopts a split structure design, specifically including an upper half-shell and a lower half-shell. The upper half-shell and the outer wall of the flow pipe 4 enclose a closed upper mounting cavity, and the lower half-shell and the outer wall of the flow pipe 4 enclose a closed lower mounting cavity. The induction coil 2 is fixed in the upper mounting cavity, and the excitation coil 1 is fixed in the lower mounting cavity. The upper half-shell and the lower half-shell are fixedly connected at the mating flange surface by fasteners such as bolts and nuts. The induction coil 2 and the excitation coil 1 are fixed at predetermined positions on the outer wall of the flow pipe 4, and the inner cavity walls of the upper half-shell and the lower half-shell are tightly fitted with the outer wall of the flow pipe 4 to form an electromagnetic shielding cavity.

[0037] The split metal casing 3 is easy to disassemble, facilitating the installation and maintenance of the excitation coil 1 and the induction coil 2. It also ensures the accuracy and stability of the coil installation position and the symmetry of the magnetic field distribution, thereby improving the repeatability and accuracy of flow measurement. This allows the device to be repaired and the coil components replaced without interruption of fluid supply.

[0038] In one embodiment, a signal processing module is also included. The high-temperature resistant metal wire of the induction coil 2 is led out from the coil winding and extends to the input port of the signal processing module. The high-temperature resistant metal wire of the induction coil 2 is directly connected to the signal processing module. The signal processing module collects the induced electromotive force signals generated by the pair of induction coils 2 in real time. By comparing the difference between these signals, and applying a preset algorithm, the induced electromotive force difference is converted into the flow rate and volumetric flow rate of the conductive fluid in the flow pipe 4.

[0039] The signal processing module automatically acquires, processes, and calculates the flow rate of the output signal of the induction coil 2, directly converting the induced electromotive force difference into a flow rate value, avoiding errors from manual reading and calculation, and improving measurement efficiency. The signal processing module can process the differential signal of the induction coil 2 in real time, effectively suppressing common-mode interference, improving the accuracy and stability of flow measurement, and realizing the digitalization and intelligentization of flow measurement. The signal processing module can also integrate functions such as temperature compensation and density correction.

[0040] Specifically, during the measurement process, the signal processing module receives the first and second alternating voltage analog signals from the two induction coils 2 in real time and transmits these two analog signals to the pre-amplifier signal conditioning unit. The pre-amplifier signal conditioning unit performs programmable gain amplification on the first and second alternating voltage analog signals respectively, with the gain factor automatically adjusted to the range of 1 to 1000 times according to the signal amplitude. Then, it filters out power frequency interference and high-frequency noise through a built-in active filter. The filtered two analog signals are then sent to the analog-to-digital conversion unit. The analog-to-digital conversion unit simultaneously samples the two analog signals at a sampling frequency of not less than 100kHz, quantizing the analog signals into a 16-bit or higher digital signal sequence. The quantized digital signal sequence is then sent to the central processing unit via a parallel data bus. After receiving the two digital signal sequences, the central processing unit first calculates the correlation between the first alternating voltage digital signal sequence and the second alternating voltage digital signal sequence using a cross-correlation algorithm. The phase difference between two alternating voltage digital signal sequences is calculated, and the amplitude difference between the two signals is also calculated to obtain accurate phase difference and amplitude difference data. The central processing unit then retrieves a pre-calibrated lookup table of the mapping relationship between fluid flow rate and phase difference and amplitude difference from the non-volatile storage unit. The lookup table is obtained through experimental calibration and covers multiple sets of operating condition data within a temperature range of 0-800℃. The central processing unit uses a bilinear interpolation algorithm or a cubic spline interpolation algorithm to perform interpolation calculations on the lookup table based on the actual measured phase difference and amplitude difference values ​​to obtain the real-time flow rate value of the conductive fluid under the current operating condition. After obtaining the flow rate value, the central processing unit combines the geometric parameters of the inner diameter of the flow pipe 4 read from the non-volatile storage unit and calculates the volumetric flow rate using the flow conversion formula. The calculated flow rate data, along with the flow rate and flow direction information, is sent to the data output interface unit, which outputs the measurement results through analog signals or industrial Ethernet communication protocols.

[0041] In one embodiment, the high-temperature resistant metal wire of the induction coil 2 is twisted and wound in a twisted pair form during the lead-out process to form a signal transmission line with a twisted pair structure. The end conductors of the twisted pair are electrically connected to the corresponding terminals of the signal processing module to transmit the alternating voltage signal sensed by the induction coil 2 to the signal processing module.

[0042] The twisted-pair cable design ensures that the two conductors experience equal and opposite external electromagnetic interference during transmission, thus canceling each other out at the input of the signal processing module. This reduces the interference of external electromagnetic noise on the transmission of the induced electromotive force signal, improves the signal-to-noise ratio and the quality of the measurement signal, and ensures the accuracy of flow measurement. The twisted-pair structure can also effectively suppress common-mode interference and crosstalk.

[0043] In one embodiment, the system further includes a variable frequency excitation power supply. The output terminal of the variable frequency excitation power supply is electrically connected to the input terminal of the excitation coil 1 via a high-temperature resistant cable. The variable frequency excitation power supply provides an AC excitation current with adjustable frequency to the excitation coil 1. The output frequency of the variable frequency excitation power supply is steplessly adjustable within the range of 50Hz to 800Hz according to the conductivity characteristics of the conductive fluid and the geometry of the flow channel 4. Under the drive of the variable frequency excitation power supply, the excitation coil 1 generates an alternating magnetic field of corresponding frequency in the flow channel 4.

[0044] The variable frequency excitation power supply enables the device to flexibly adapt to the measurement needs of different conductive fluids. It obtains the optimal signal output through frequency adjustment, improves the adaptability and accuracy of flow measurement, and avoids signal attenuation or distortion at fixed frequencies. The variable frequency excitation power supply can also adopt a constant current output mode, which, together with the feedback control circuit, maintains the stability of the magnetic field strength.

[0045] In one embodiment, the inner cross-section of the flow passage 4 is circular, and the excitation coil 1 and the induction coil 2 are arranged around the outer wall of the circular flow passage 4. The alternating magnetic field generated by the excitation coil 1 is uniformly distributed in the circular cross-sectional area of ​​the circular flow passage 4, and the conductive fluid flows in the circular inner cavity of the circular flow passage 4 and cuts the magnetic field lines.

[0046] The circular flow passage 4 is the most common structural form in industrial pipelines. The circular cross-section allows the flow measurement device to be directly applied to existing industrial pipeline systems without special modifications. The circular geometry has anisotropic symmetry, which is conducive to the formation of a uniform magnetic field distribution in the excitation coil 1 within the circular flow passage 4, ensuring the consistency of measurement results in different flow directions. At the same time, the circular flow passage 4 fits more tightly with the circular coil frame, facilitating coil positioning and installation. The circular cross-section can also reduce fluid flow resistance and turbulence effects.

[0047] In one embodiment, the axes of the induction coil 2, the excitation coil 1, and the flow pipe 4 are arranged coplanarly. That is, the central axes of the induction coil 2, the excitation coil 1, and the flow pipe 4 are located in the same plane. The paired induction coils 2 are symmetrically distributed relative to the axis of the excitation coil 1 within the cross-section of the flow pipe 4. This three-plane layout ensures that the alternating magnetic field generated by the excitation coil 1 has a symmetrical magnetic field line distribution within the plane containing the induction coils 2. The paired induction coils 2 can sense induced electromotive force signals of equal magnitude and opposite or identical phase, facilitating differential calculations by the signal processing module. This coplanar arrangement maximizes magnetic field coupling efficiency, improves the strength of the induced signal, and ensures accurate implementation of the measurement principle.

[0048] In one embodiment, the winding axis of the induction coil 2 is arranged parallel to the axis of the flow pipe 4, that is, the winding plane of the induction coil 2 is parallel to the axial direction of the flow pipe 4. The induction coil 2 extends along the axial direction of the outer wall of the flow pipe 4, and the excitation coil 1 and the induction coil 2 are located on opposite sides of the radial direction of the flow pipe 4. The parallel arrangement of the induction coil 2 and the flow pipe 4 ensures that each turn of the conductor of the induction coil 2 maintains the same relative positional relationship with the fluid flow direction, which can maximize the induction of the axial secondary magnetic field generated by the movement of the conductive fluid, improve the signal strength and signal-to-noise ratio of the induced electromotive force, and at the same time ensure effective electromagnetic coupling between the induction coil 2 and the excitation coil 1.

[0049] The non-contact conductive fluid flow measurement device of this application includes: a flow pipe, an excitation coil, induction coils, and a metal housing. The excitation coil is located below the flow pipe and perpendicular to its central axis. A pair of induction coils are located above the flow pipe and on the same plane, and are centrally symmetrical about the excitation coil. The metal housing consists of upper and lower parts, located outside the excitation coil and the two induction coils respectively, fixing them to both sides of the flow pipe and shielding them from external magnetic field interference.

[0050] This application also provides a non-contact conductive fluid flow measurement method, comprising the following steps: First, generating an alternating magnetic field inside the flow pipe; second, receiving the induced electromotive force generated by paired induction coils when the conductive liquid flows through the alternating magnetic field; third, calculating the conductive liquid flow rate based on the induced electromotive force. Specifically: The steps to generate an alternating magnetic field inside a circular pipe include: applying a sinusoidal alternating current of a specific frequency to an excitation coil to generate an alternating magnetic field inside the circular pipe. (1) In equation (1), μ0 is the free permeability, and N is the number of turns of the excitation coil. is a sinusoidal alternating current, and r is the radius of the excitation coil.

[0051] The steps for receiving the induced electromotive force (EMF) generated by a pair of induction coils when a conductive liquid flows through an alternating magnetic field include: when the conductive liquid flows through the alternating magnetic field, eddy currents are induced within it. These eddy currents then generate a secondary magnetic field, which the induction coils then detect to generate an induced EMF. Given Maxwell's equations: (2) (3) (4) For isotropic materials, the following conditions are met: (5) in .

[0052] A conductive liquid has constant electrical and magnetic permeability and isotropic properties, moving at a velocity v in a flow channel. In the analysis, it is divided into two independent processes: the actual physical process and its reciprocal process. Process one involves the liquid metal moving at velocity v, while process two involves the liquid metal remaining stationary. The excitation coil is used as an induction coil, and the two induction coils are used as excitation coils.

[0053] For process one, the following equation can be written: (6) (7) Similarly, for process two, we can conclude that: (8) (9) Among them, J s1 and J s2 E1 and E2 are the current densities when the excitation coil and induction coil are used as excitation, respectively; E1 and E2 are the electric field strengths when the excitation coil and induction coil are used as excitation, respectively; H1 and B1 are the magnetic field strength and magnetic induction intensity of the magnetic field generated in space when the excitation coil is used as excitation in process one, respectively; H2 is the magnetic induction intensity of the magnetic field generated in space when the induction coil is used as excitation; and μ is the permeability.

[0054] After final derivation and simplification, we can obtain: (10) (11) Among them, I 1B and I 1C and , These are the induced current and induced electromotive force generated by the two paired induction coils 2 when the excitation coil 1 is used as the excitation coil. It refers to the induced electromotive force generated by the excitation coil 1 when one of the two paired induction coils 2 is used as the excitation coil 1. It refers to the induced electromotive force generated by the excitation coil 1 when one of the two paired induction coils 2 is used as the excitation coil. 2B and J 2C These are the current densities of the induced current generated in the overcurrent pipe by the excitation coil 1 when the two paired induction coils 2 are used as excitation during the reciprocal process; simultaneously, since the two paired induction coils 2 are centrally symmetrical with respect to the excitation coil 1, therefore... Therefore, by simultaneously solving equations (10) and (11), we obtain the relationship between the induced electromotive force generated by a pair of induction coils and the flow velocity of the liquid metal: (12) As shown in equation (12), the measured signal is proportional to the flow velocity v, and its sensitivity is defined by the weighting function F. F is the weighting function of the flow velocity v, which is related to the coil parameters, excitation frequency, and flow velocity v.

[0055] The steps for calculating the flow rate of a conductive liquid based on the induced electromotive force include: substituting the induced electromotive force difference monitored in real time by a non-contact conductive fluid flow measurement device into the relationship between the induced electromotive force difference and the liquid flow rate; calculating the flow velocity of the liquid under this operating condition through interpolation; and finally calculating the flow direction, flow velocity, and volumetric flow rate of the liquid by combining the geometric parameters and density of the circular pipe.

[0056] 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 conductive fluid flow measurement device, characterized in that, include: The flow passage (4) has an inner cavity suitable for the flow of conductive fluid; An excitation coil (1) is disposed on one side of the flow pipe (4), and the axis of the excitation coil (1) is perpendicular to the axis of the flow pipe (4); The induction coil (2) is provided in at least one pair. The induction coil (2) and the excitation coil (1) are respectively arranged on both sides of the flow pipe (4). The pair of induction coils (2) are arranged symmetrically with respect to the axis of the excitation coil (1). Both the excitation coil (1) and the induction coil (2) include a high-temperature resistant insulating frame and a high-temperature resistant metal wire wound on the high-temperature resistant insulating frame.

2. The non-contact conductive fluid flow measurement device according to claim 1, characterized in that, The high-temperature resistant insulating frame is a ceramic frame, and the high-temperature resistant metal wire is a copper wire with an aluminum oxide insulating layer on its surface.

3. The non-contact conductive fluid flow measurement device according to claim 1 or 2, characterized in that, It also includes a metal casing (3), and the excitation coil (1) and the induction coil (2) are both installed in the inner cavity of the metal casing (3).

4. The non-contact conductive fluid flow measurement device according to claim 3, characterized in that, The metal housing (3) includes an upper half-shell and a lower half-shell. The upper half-shell and the flow pipe (4) enclose an upper mounting cavity, and the lower half-shell and the flow pipe (4) enclose a lower mounting cavity. The induction coil (2) is installed in the upper mounting cavity, and the excitation coil (1) is installed in the lower mounting cavity. The upper half-shell and the lower half-shell are fixedly connected.

5. The non-contact conductive fluid flow measurement device according to claim 1 or 2, characterized in that, It also includes a signal processing module. The high-temperature resistant metal wires of the induction coil (2) are all extended to connect with the signal processing module. The signal processing module is used to receive and calculate the induced electromotive force difference on the pair of induction coils (2), and calculate the flow rate of the conductive fluid in the flow pipe (4) based on the induced electromotive force difference.

6. The non-contact conductive fluid flow measurement device according to claim 5, characterized in that, The high-temperature resistant metal wire of the induction coil (2) is led out in the form of a twisted pair, and the end of the twisted pair is electrically connected to the signal processing module.

7. The non-contact conductive fluid flow measurement device according to claim 1 or 2, characterized in that, It also includes a variable frequency excitation power supply, which is electrically connected to the excitation coil (1). The variable frequency excitation power supply is used to provide the excitation coil (1) with adjustable frequency AC power. The output frequency range of the variable frequency excitation power supply is 50Hz to 800Hz.

8. The non-contact conductive fluid flow measurement device according to claim 1 or 2, characterized in that, The cross-section of the inner cavity of the flow pipe (4) is circular.

9. The non-contact conductive fluid flow measurement device according to claim 1 or 2, characterized in that, The axis of the induction coil (2), the axis of the excitation coil (1), and the axis of the flow pipe (4) are coplanar.

10. The non-contact conductive fluid flow measurement device according to claim 1 or 2, characterized in that, The induction coil (2) is arranged in parallel with the flow pipe (4).

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