A magnetostrictive guided wave level meter for high temperature liquid

Abstract

The present invention discloses a magnetostrictive waveguide liquid level meter for high-temperature liquid, comprising a ferromagnetic long rod and a magnetostrictive sensor; the magnetostrictive sensor comprises a sensor body formed by an upper yoke and a lower yoke with a permanent magnet, the sensor body is a hollow structure, one end of the ferromagnetic long rod is penetrated by the hollow structure and connected to the magnetostrictive sensor in a detachable manner; the ferromagnetic long rod extends into the sensor body and is wound with a coil, and both ends of the coil are connected to an alternating current; the ferromagnetic long rod is a hollow rod, and a plurality of flanges are evenly arranged in the vertical direction of the inner wall of the ferromagnetic long rod. The liquid level meter of the present invention installs a magnetostrictive sensor on the end face to ensure the stability of waveguide excitation and reception, and secondly, by performing a temperature calibration test on the plurality of flange signals arranged on the ferromagnetic long rod, the propagation speed of the waveguide in the ferromagnetic long rod at different temperatures is detected, thereby realizing the test of the liquid level of the high-temperature liquid. The present invention has a simple structure, is easy to install and disassemble, and has higher measurement accuracy.

Description

Technical Field

[0001] The invention relates to a liquid level measuring device, in particular to a magnetostrictive guided wave level meter for high-temperature liquid. Background Art

[0002] Magnetostrictive level gauges are widely used in liquid temperature measurement. Magnetostrictive level gauges based on waveguide wires mainly excite and receive first-order torsional mode ultrasonic guided waves. Traditional magnetostrictive level gauges mainly use waveguide wires with excellent magnetostrictive performance and an annular magnetic float, in which the magnetization direction of the magnetic float is along the axial direction. When a current signal is passed through the waveguide wire, based on the magnetostrictive effect, torsional mode guided waves can be excited at the magnetic float position of the waveguide wire. The generated torsional guided waves are transmitted along the waveguide wire to the guided wave receiving device on the end face, and the calculation of the liquid level is completed through algorithm writing. When the traditional magnetostrictive level gauge is used for high-temperature liquid level detection, the liquid level cannot be accurately tested. There are two reasons: first, the magnetic float will be demagnetized under high temperature conditions, and it is impossible to generate effective bias magnetism on the waveguide wire, thereby realizing the excitation of torsional mode guided waves; second, under high temperature conditions, the propagation speed of the guided wave in the waveguide wire changes, and the results calculated by the conventional algorithm will cause deviations in the liquid level calculation.

[0003] In view of this, there is an urgent need to provide a magnetostrictive guided wave level meter for high-temperature liquids that is suitable for measuring the liquid level of high-temperature liquids, has higher measurement accuracy, and is easy to use. Summary of the invention

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is to provide a magnetostrictive guided wave level meter for high-temperature liquid, comprising:

[0005] Ferromagnetic long rod, magnetostrictive sensor and control circuit board;

[0006] The magnetostrictive sensor comprises a sensor body formed by an upper yoke and a lower yoke sandwiching a permanent magnet, the sensor body being a hollow structure, one end of the ferromagnetic long rod passing through the hollow structure to achieve a detachable connection with the magnetostrictive sensor; the ferromagnetic long rod extending into the sensor body is wound with a coil, and both ends of the coil are connected to an alternating current;

[0007] The ferromagnetic long rod is a hollow rod, and a plurality of flanges are evenly arranged on the inner wall of the ferromagnetic long rod in the vertical direction;

[0008] After the coil is energized, a dynamic alternating magnetic field and a bias magnetic field in the same direction as the axial direction of the ferromagnetic long rod are generated, thereby generating a longitudinal modal waveguide. When the longitudinal modal waveguide encounters each flange during propagation, a reflected wave is generated. At the same time, the magnetostrictive sensor receives the reflected wave and determines the time when each reflected wave is received. The speed of the waveguide at each position in the ferromagnetic long rod is calculated through the time of the excited longitudinal modal waveguide. A relationship curve between the temperature and the propagation speed of the longitudinal modal waveguide in the ferromagnetic long rod is obtained through a calibration test. Thus, the liquid level position is determined according to the temperature difference above and below the liquid surface.

[0009] The control circuit board includes a power supply circuit, a single chip circuit, a liquid crystal display circuit, a power-on excitation circuit, an ADC acquisition circuit, a signal output circuit and a communication module. The control circuit board is electrically connected to the coil to control the power-on excitation circuit and the ADC acquisition circuit.

[0010] In the above solution, a plurality of protrusions are evenly arranged in the vertical direction on the inner wall of the ferromagnetic long rod to form the flange.

[0011] In the above solution, the flange is formed by a groove formed from the outer side to the inner side of the ferromagnetic long rod body.

[0012] In the above solution, a hook is sleeved on the ferromagnetic long rod.

[0013] In the above solution, the long ferromagnetic rod is a cylindrical ferromagnetic rod with uniform wall thickness.

[0014] The liquid level meter of the present invention installs a magnetostrictive sensor on the end surface to ensure the stability of waveguide excitation and reception, and detects multiple flange signals set on the ferromagnetic long rod, and performs temperature calibration tests on the multiple flange signals set on the ferromagnetic long rod to detect the propagation speed of the waveguide in the ferromagnetic long rod at different temperatures, thereby realizing the test of the high-temperature liquid level. The present invention has a simple structure and is easy to install and disassemble. Compared with the existing magnetostrictive liquid level meter based on waveguide wire, the present invention has higher measurement accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A schematic diagram of the structure provided by the present invention;

[0016] Figure 2 Working principle diagram of magnetostrictive sensor;

[0017] Figure 3 It is a schematic diagram of the structure of a preferred embodiment provided in the present invention;

[0018] Figure 4 It is a schematic structural diagram of another preferred embodiment provided in the present invention;

[0019] Figure 5It is a schematic diagram of the liquid level detection system provided in the present invention;

[0020] Figure 6 This is a time domain signal graph collected by the liquid level meter provided in the present invention. DETAILED DESCRIPTION

[0021] The present invention provides a magnetostrictive level gauge suitable for high-temperature liquid level detection. A magnetostrictive sensor is installed on the end face to ensure the stability of waveguide excitation and reception. Secondly, by performing a temperature calibration test on multiple flange signals arranged on a ferromagnetic long rod, the propagation speed of the waveguide in the ferromagnetic long rod at different temperatures is detected, thereby realizing the test of the high-temperature liquid level. The present invention has a simple structure and is easy to install and disassemble. Compared with the existing magnetostrictive level gauge based on waveguide wire, the present invention has higher measurement accuracy. The level gauge of the present invention can directly detect high-temperature liquids, and the level gauge can also be installed in a fixed position for long-term monitoring of the high-temperature liquid level.

[0022] It should be noted that the terms "vertical", "upper", "lower", "horizontal" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as limiting the present invention. The present invention is described in detail below in conjunction with specific implementation methods and drawings in the specification.

[0023] like Figure 1-2 As shown, the present invention provides a magnetostrictive waveguide level meter for high-temperature liquid, comprising:

[0024] A ferromagnetic long rod 1 extending into the liquid to be tested, and a magnetostrictive sensor 2 detachably connected to the ferromagnetic long rod 1; a control circuit board 4 connected to an external power supply or a central control device;

[0025] The magnetostrictive sensor 2 includes a sensor body formed by an upper yoke 21 and a lower yoke 22 with a permanent magnet 23 sandwiched therebetween. The sensor body is a hollow structure. One end of a ferromagnetic long rod 1 passes through the hollow structure to achieve a detachable connection with the magnetostrictive sensor 2. The ferromagnetic long rod 1 extends into the sensor body and is wound with a coil 3, and both ends of the coil 3 are connected to an alternating current.

[0026] The magnetostrictive sensor is composed of a yoke, a permanent magnet and a coil. The permanent magnet is connected to and installed at the end of a ferromagnetic long rod through a yoke, and an alternating current signal is passed through the coil 3 wound on the ferromagnetic long rod to generate a dynamic alternating magnetic field along the axial direction of the ferromagnetic long rod.

[0027] The control circuit board 4 includes a power supply circuit, a single-chip circuit, a liquid crystal display circuit, an energized excitation circuit, an ADC acquisition circuit, a signal output circuit, and a communication module. The control circuit board 4 is electrically connected to the coil 3, controls the energized excitation circuit and the ADC acquisition circuit, and displays the liquid level information obtained by the single-chip circuit in real time through the liquid crystal display circuit. At the same time, the liquid level information is output through the signal output circuit and the communication module. The signal output can be in a variety of ways such as wired 4-20ma, Hart protocol or wireless communication. The power supply circuit can be powered by a wired external power supply or a lithium battery.

[0028] The ferromagnetic long rod 1 is a hollow rod, and a plurality of flanges 11 are evenly arranged on the inner wall of the ferromagnetic long rod 1 in the vertical direction.

[0029] Figure 2 The working principle diagram of the magnetostrictive sensor is shown in FIG. 2 . The permanent magnet 23 forms a static magnetic field loop with the ferromagnetic long rod 1 through the upper and lower yoke irons. A magnetic field B is generated in the ferromagnetic long rod 1 along the axial direction. DC The single chip microcomputer controls the power-on excitation circuit so that an alternating current signal is passed through the coil 3 wound in the ferromagnetic long rod 1 to generate a dynamic bias magnetic field B in the axial direction. AC , the two magnetic fields are in the same direction. The Joule effect shows that a longitudinal modal waveguide is generated in the ferromagnetic long rod 1. The longitudinal modal waveguide propagates in the axial direction in the ferromagnetic long rod 1. When the longitudinal modal waveguide passes through the flange, part of the energy is transmitted and the other part of the energy is reflected to form a reflected waveguide. The reflected waveguide returns to the position of the coil 3. The inverse Joule effect shows that a voltage signal will be collected in the coil 3. The voltage signal is collected by the ADC acquisition circuit and converted to analog-to-digital. The digital signal is transmitted to the single-chip microcomputer for processing through the single-chip microcomputer circuit. The peak signal is extracted by the single-chip microcomputer. The propagation speed between each point is calculated by the time difference of the peak signal. The temperature change can be obtained according to the speed change, thereby detecting the temperature difference change above and below the liquid surface, and the liquid surface position information is displayed in real time through the liquid crystal display circuit and transmitted to the signal output circuit and the communication module to output the liquid level information.

[0030] like Figure 3 As shown, in this preferred embodiment, a plurality of protrusions are evenly arranged in the vertical direction on the inner wall of the ferromagnetic long rod 1 to form a flange 11.

[0031] The ferromagnetic long rod 1 is provided with a hook 41 which can be adjusted up and down along the ferromagnetic long rod 1 and is hung on the open edge of the liquid device. The position of the hook 41 relative to the ferromagnetic long rod 1 is adjusted according to the liquid level height. The hook 41 ensures that the liquid level meter is stably placed in the liquid.

[0032] like Figure 4 As shown, in this embodiment, preferably, the groove formed from the outer side to the inner side of the body of the ferromagnetic long rod 1 forms a flange 11.

[0033] In the present embodiment, preferably, in order to ensure that the longitudinal modal guided waves and reflected waves propagate uniformly in the ferromagnetic long rod 1 and are not affected by the shape of the ferromagnetic long rod 1, the ferromagnetic long rod 1 is a cylindrical ferromagnetic rod with uniform wall thickness.

[0034] The working process of this embodiment is described in detail below.

[0035] like Figure 5-6 The figure shows the collected groove defect reflection signal. The wave packet signal corresponding to each groove defect corresponds to a time, such as t1, t2, t3 and t4. The time of the adjacent groove defect reflection signal is △t2, △t3 and △t4. The distance between adjacent groove defects is l2, l3 and l4. The speed of the guided wave in two adjacent groove defects can be calculated.

[0036] Before it is put into use, a large number of calibration tests at different temperatures are required. The same ferromagnetic long rod 1 with a length of l is used as the experimental object. The ferromagnetic long rod 1 is placed at different temperatures. The end face signal is collected through the ADC analog-to-digital conversion chip and the single-chip microcomputer, and the time t of the end face wave packet signal is recorded. The propagation velocity v=l / t of the longitudinal modal waveguide in the ferromagnetic long rod at different temperatures can be calculated. The temperature range can be controlled to achieve the propagation velocity of the longitudinal modal waveguide in the ferromagnetic long rod at the target temperature. The temperature of the experiment is used as the horizontal coordinate, and the velocity calculated at each temperature is used as the vertical coordinate, and the fitting relationship between temperature and longitudinal modal waveguide velocity can be obtained.

[0037] In actual operation, the signals collected by ADC and single-chip microcomputer under actual high temperature conditions are processed to obtain the corresponding speed of each adjacent groove defect segment, and then substituted into the calibrated correlation curve to obtain the temperature of the ferromagnetic long rod 1. There is a large temperature difference between liquid and gas, so the area with obvious temperature change measured in the experiment is the interface between liquid and gas, so the liquid level height is obtained.

[0038] The present invention is not limited to the above-mentioned optimal implementation mode. Anyone should be aware that any structural changes made under the inspiration of the present invention, and any technical solutions that are the same or similar to the present invention, fall within the protection scope of the present invention.

Claims

1. A magnetostrictive waveguide level gauge for high temperature liquid, characterized in that: include: A ferromagnetic long rod (1), a magnetostrictive sensor (2) and a control circuit board (4); The magnetostrictive sensor (2) comprises a sensor body formed by an upper yoke (21) and a lower yoke (22) sandwiching a permanent magnet (23); the sensor body is a hollow structure; one end of the ferromagnetic long rod (1) passes through the hollow structure to achieve a detachable connection with the magnetostrictive sensor (2); the ferromagnetic long rod (1) extends into the sensor body and is wound with a coil (3); both ends of the coil (3) are connected to an alternating current; The ferromagnetic long rod (1) is a hollow rod, and a plurality of flanges (11) are evenly arranged in the vertical direction on the inner wall of the ferromagnetic long rod (1); When the coil (3) is energized, a dynamic alternating magnetic field and a bias magnetic field in the same direction as the axial direction of the ferromagnetic long rod (1) are generated, thereby generating a longitudinal modal waveguide. When the longitudinal modal waveguide encounters each flange (11) during propagation, a reflected wave is generated. At the same time, the magnetostrictive sensor (2) receives the reflected wave and determines the time when each reflected wave is received. The speed of the waveguide at each position in the ferromagnetic long rod (1) is calculated based on the time of the excited longitudinal modal waveguide. A relationship curve between the temperature and the propagation speed of the longitudinal modal waveguide in the ferromagnetic long rod (1) is obtained through a calibration test, thereby determining the liquid level position. The control circuit board (4) comprises a power supply circuit, a single-chip computer circuit, a liquid crystal display circuit, a power-on excitation circuit, an ADC acquisition circuit, a signal output circuit and a communication module; the control circuit board (4) is electrically connected to the coil (3) to control the power-on excitation circuit and the ADC acquisition circuit.

2. The magnetostrictive waveguide level gauge for high temperature liquid according to claim 1, characterized in that: The inner wall of the ferromagnetic long rod (1) is evenly provided with a plurality of protrusions in a vertical direction to form the flange (11).

3. The magnetostrictive waveguide level gauge for high temperature liquid according to claim 1, characterized in that: The flange (11) is formed by a groove formed from the outer side to the inner side of the body of the ferromagnetic long rod (1).

4. The magnetostrictive waveguide level gauge for high temperature liquid according to claim 2 or 3, characterized in that: The ferromagnetic long rod (1) is sleeved with a hook (41).

5. The magnetostrictive waveguide level gauge for high temperature liquid according to claim 2 or 3, characterized in that: The ferromagnetic long rod (1) is a cylindrical ferromagnetic rod with uniform wall thickness.

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