Pipeline defect magnetic flux leakage detection device based on magneto-optical imaging

Abstract

The utility model discloses a pipeline defect magnetic flux leakage detection device based on magneto-optical imaging, which is characterized in that a magnetization module couples a magnetic field into a pipeline wall through double poles, and magnetic induction lines are conducted between the pipeline wall and the magnetization module to form a closed magnetic induction line loop; a magnetic induction line leaks into air from the vicinity of the defect to generate a leakage magnetic field; then an ultra-thin light source in the magneto-optical detection module emits light, the light is changed into polarized light after penetrating through a polarizer, the polarized light can deflect the polarization direction of the light under the action of a leakage magnetic field when penetrating through a magneto-optical film, and when the converted light penetrates through an analyzer, only components perpendicular to the polarization direction of the analyzer can penetrate through the analyzer; therefore, optical signals are detected by the image acquisition module, the optical signals are converted into digital signals by the image acquisition module and then transmitted to the data storage module through the communication cable, and data of the stored digital signals are read by the computer and defects are processed and recognized after pipeline detection is finished.

Description

Technical Field

[0001] The present invention belongs to the technical field of pipeline defects, and more specifically, relates to a magnetic flux leakage detection device for pipeline defects based on magneto-optical imaging. Background Art

[0002] Pipelines made of carbon steel undertake important tasks in the transportation of energy such as oil and natural gas in our country. During long-term operation, defects such as pipeline corrosion and cracks are likely to occur. These defects are likely to cause pipeline rupture, and then problems such as leakage and even explosion. It poses a great threat to people's lives and property safety. To prevent such incidents from occurring, magnetic flux leakage detection technology is usually used at home and abroad to detect in-service oil and gas pipelines, timely discover defects, and carry out emergency repairs.

[0003] The current magnetic flux leakage detection technology is commonly used for large-area corrosion detection of pipelines. However, the traditional magnetic flux leakage detection method based on a linear array of magnetic sensors is limited by the sensor size and sampling rate, resulting in insufficient detection spatial resolution. At the same time, there are problems such as jitter interference and transmission noise during movement, and small defects such as cracks cannot be detected. Especially in the field of weld crack detection, the defects are small, there is magnetic flux leakage interference from the weld itself, and the sensor probe is prone to bounce in the weld area. These interferences make it impossible for the traditional magnetic field sensor based on a linear array to correctly detect weld cracks. Summary of the Invention

[0004] The purpose of the present utility model is to overcome the deficiencies of the prior art and provide a magnetic flux leakage detection device for pipeline defects based on magneto-optical imaging, which can detect cracks with a resolution exceeding 0.1 mm and the advantage of surface imaging.

[0005] To achieve the above-mentioned invention purpose, a magnetic flux leakage detection device for pipeline defects based on magneto-optical imaging of the present invention is characterized in that it includes: a magnetization module, a magneto-optical detection module, and a data storage module. Among them, the magnetization module is connected to the magneto-optical detection module through a non-magnetic material, and the data storage module is connected to the magneto-optical detection module through a communication cable;

[0006] The magnetization module is composed of a permanent magnet forming an S-N bipolar and a magnetic conductor connecting member. The magnetization module couples the magnetic field into the pipeline wall, and the magnetic induction lines conduct between the pipeline wall and the magnetization module to form a closed magnetic induction line loop. When there are defects in the pipe wall, the magnetic induction lines will leak into the air near the defects to generate a leakage magnetic field;

[0007] The magneto-optical detection module is composed of an ultra-thin magneto-optical conversion module, an image acquisition module and a housing. Among them, the ultra-thin magneto-optical conversion module is composed of multiple layers of materials, which are, from bottom to top, an ultra-thin light source, a bottom polarizing film, a magneto-optical film and a top polarizing film. Among them, the bottom polarizing film serves as a polarizer, and the top polarizing film serves as an analyzer; the ultra-thin magneto-optical conversion module is located directly below the image acquisition module and then encapsulated in a high-strength housing;

[0008] The ultra-thin light source emits light, which becomes polarized light after passing through the polarizer. When the polarized light passes through the magneto-optical film, the polarization direction of the light will be deflected under the action of the leakage magnetic field. The stronger the magnetic field, the greater the deflection angle; when the deflected light passes through the analyzer, only the component parallel to the polarization direction of the analyzer can pass through the analyzer, so that the light signal can be detected by the image acquisition module. The light signal is then converted into a digital signal by the image acquisition module and transmitted to the data storage module through a communication cable. After the digital signal is stored, the computer reads the data and processes and identifies the defects after the pipeline detection is completed.

[0009] The invention object of the present utility model is realized as follows:

[0010] The magnetic flux leakage detection device for pipeline defects based on magneto-optical imaging of the present utility model first uses the magnetization module to couple the magnetic field into the pipeline wall through a bipolar, and the magnetic induction lines conduct between the pipeline wall and the magnetization module to form a closed magnetic induction line loop. When there are defects on the pipeline wall, the magnetic induction lines will leak into the air near the defects to generate a leakage magnetic field; then the ultra-thin light source in the magneto-optical detection module emits light, which becomes polarized light after passing through the polarizer. When the polarized light passes through the magneto-optical film, the polarization direction of the light will be deflected under the action of the leakage magnetic field. When the deflected light passes through the analyzer, only the component perpendicular to the polarization direction of the analyzer can pass through the analyzer, so that the light signal can be detected by the image acquisition module. The light signal is then converted into a digital signal by the image acquisition module and transmitted to the data storage module through a communication cable. After the digital signal is stored, the computer reads the data and processes and identifies the defects after the pipeline detection is completed.

[0011] At the same time, the magnetic flux leakage detection device for pipeline defects based on magneto-optical imaging of the present utility model also has the following beneficial effects:

[0012] (1) By converting the magnetic field signal into a large-area light signal and collecting it by the image acquisition module, the present utility model can obtain a magnetic field signal with an ultra-high spatial resolution at the pixel level (≤100μm). The ultra-high spatial resolution is helpful for the detection of small crack signals.

[0013] (2) The data collected by the present utility model is image data, and a magnetic field signal of a surface area can be obtained by a single collection. This enables it to perform self-comparison within the detection surface during subsequent offline processing, has strong anti-jitter interference characteristics, and is helpful for the detection of weld cracks.

[0014] (3) The utility model can detect pipeline defects under jitter interference, especially small defects such as cracks, and thus can be used in the field of pipeline weld crack detection.

[0015] (4) The utility model improves the structure of the magneto-optical detection module. It not only adds a high-strength housing for anti-vibration but also adds high-strength filling materials. This can not only ensure the relative stability of the internal devices of the magneto-optical detection module but also ensure that the internal structure is not damaged by impact during movement. Description of the Drawings

[0016] Figure 1 is the structural diagram of the magneto-optical imaging-based pipeline defect magnetic flux leakage detection device of the utility model;

[0017] Figure 2 is the schematic structural diagram of the magneto-optical imaging detection module described in Embodiment 1;

[0018] Figure 3 is another form of the schematic structural diagram of the magneto-optical imaging detection module described in Embodiment 1.

[0019] The reference numerals in the figure are: 1 permanent magnet; 2 magnetic conductor; 3 magneto-optical detection module; 4 data storage module; 5 pipeline wall; 3-1 ultra-thin light source; 3-2 polarizing film; 3-3 magneto-optical thin film; 3-4 polarizing film; 3-5 image acquisition module; 3-6 high-strength housing; 3-7 high-strength filling material. Detailed Embodiment

[0020] The following describes the detailed embodiment of the present invention with reference to the drawings so that those skilled in the art can better understand the present invention. It should be particularly noted that in the following description, when the detailed description of known functions and designs may dilute the main content of the present invention, these descriptions will be omitted here.

[0021] Embodiment

[0022] Figure 1 is the architecture diagram of the magneto-optical imaging-based pipeline defect magnetic flux leakage detection device of the utility model.

[0023] In this embodiment, as Figure 1 shown, a magneto-optical imaging-based pipeline defect magnetic flux leakage detection device of the utility model includes: a magnetization module, a magneto-optical detection module, and a data storage module. Among them, the magnetization module is connected to the magneto-optical detection module through a non-magnetic material, and the data storage module is connected to the magneto-optical detection module through a communication cable;

[0024] The magnetization module is composed of a permanent magnet 1 forming an S-N bipolar and a magnetic conductor 2 connecting member. The magnetic conductor 2 is located between the S-N bipolar, and the S-N bipolar is symmetrically structured;

[0025] The magnetization module couples a magnetic field into the pipe wall 5, and magnetic induction lines conduct between the pipe wall 5 and the magnetization module to form a closed magnetic induction line loop. When there are defects in the pipe wall 5, the magnetic induction lines will leak into the air near the defects, generating a leakage magnetic field;

[0026] In this embodiment, the magnetization module is not limited to magnetization in a single direction. To detect defects in multiple directions, the magnetization module can be designed to magnetize along the axial direction of the pipe, or along the circumferential direction, or at an angle of 45° to the axial direction.

[0027] The magneto-optical detection module 3 is composed of an ultra-thin magneto-optical conversion module, an image acquisition module, and a housing. The ultra-thin magneto-optical conversion module is located directly below the image acquisition module and then encapsulated in a high-strength housing; among them, the ultra-thin magneto-optical conversion module is composed of multiple layers of materials, including an ultra-thin light source 3-1, polarizing films 3-2 / 3-4, and a magneto-optical thin film 3-3, as Figure 2 shown, from bottom to top are the ultra-thin light source 3-1, the bottom polarizing film 3-2, the magneto-optical thin film 3-3, and the top polarizing film 3-4; in addition, as Figure 3 shown, the top polarizing film 3-4 can be replaced with a polarizer and does not need to be attached to the surface of the magneto-optical thin film 3-3.

[0028] In this embodiment, the ultra-thin light source 3-1 is selected as a surface light source with a thickness of ≤1 mm; the magneto-optical thin film 3-3 is selected as a material that can rotate the polarization direction of light under magnetic field conditions (such as: rare earth garnet single crystal, rare earth spinel crystal, etc., crystals with magneto-optical effects); in addition, the bottom polarizing film 3-2 can be regarded as a polarizer, and the top polarizing film 3-4 is regarded as an analyzer. The polarizing film can pass through the polarization component of polarized light and non-polarized light that is the same as the polarization direction of the polarizing film, and the non-polarized light becomes polarized light after passing through;

[0029] The magneto-optical detection module 3 needs to be connected to the magnetization module through a non-magnetic conductive connection structure, so that the magneto-optical detection module 3 is kept as much as possible between the two magnetic poles and close to the pipe wall 5; in addition, the inside of the magneto-optical detection module 3 is filled with a high-strength filling material, preferably epoxy resin, ultraviolet curable glue, glass, and acrylic. In this way, a high-strength housing is added on the outside and a high-strength filling material is filled inside, so as to ensure that the internal structure is not damaged by impact during movement.

[0030] The ultra-thin light source 3-1 emits light, which becomes polarized light after passing through the polarizer. When the polarized light passes through the magneto-optical thin film 3-3, the polarization direction of the light will be deflected under the action of the leakage magnetic field. The stronger the magnetic field, the greater the deflection angle. When the deflected light passes through the analyzer, only the component parallel to the polarization direction of the analyzer can pass through the analyzer, and thus the optical signal is detected by the image acquisition module. After the optical signal is converted into a digital signal by the image acquisition module, it is transmitted to the data storage module 4 through the communication cable. After the digital signal is stored, the computer reads the data and processes it to identify defects after the pipeline detection is completed.

[0031] Although the above description of the illustrative specific embodiments of the present invention is provided for the convenience of those skilled in the art to understand the present invention, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, as long as various changes are within the spirit and scope of the present invention defined and determined by the appended claims, these changes are obvious, and all inventions made using the concept of the present invention are within the scope of protection.

Claims

1. A magnetic flux leakage detection device for pipeline defects based on magneto-optical imaging, characterized in that Including: A magnetization module, a magneto-optical detection module, and a data storage module. Among them, the magnetization module is connected to the magneto-optical detection module through a non-magnetic material, and the data storage module is connected to the magneto-optical detection module through a communication cable; The magnetization module is composed of a permanent magnet forming an S-N bipolar and a magnetic conductor connector. The magnetic conductor is located between the S-N bipolar, and the S-N bipolar has a symmetric structure; The magnetization module couples the magnetic field into the pipe wall, and the magnetic induction lines conduct between the pipe wall and the magnetization module to form a closed magnetic induction line loop. When there is a defect in the pipe wall, the magnetic induction lines will leak into the air near the defect, generating a leakage magnetic field; The magneto-optical detection module is composed of an ultra-thin magneto-optical conversion module, an image acquisition module, and a housing. Among them, the ultra-thin magneto-optical conversion module is composed of multiple layers of materials, which are, from bottom to top, an ultra-thin light source, a bottom polarizing film, a magneto-optical film, and a top polarizing film. Among them, the bottom polarizing film serves as a polarizer, and the top polarizing film serves as an analyzer; The ultra-thin magneto-optical conversion module is located directly below the image acquisition module and then encapsulated in a high-strength housing; The ultra-thin light source emits light, which becomes polarized light after passing through the polarizer. When the polarized light passes through the magneto-optical film, the polarization direction of the light will be deflected under the action of the leakage magnetic field. The stronger the magnetic field, the larger the deflection angle; When the deflected light passes through the analyzer, only the component parallel to the polarization direction of the analyzer can pass through the analyzer, so that the light signal can be detected by the image acquisition module. The light signal is then converted into a digital signal by the image acquisition module and transmitted to the data storage module through a communication cable. After the digital signal is stored, the computer reads the data and processes and identifies the defect after the pipeline detection is completed.

2. The magnetic flux leakage detection device for pipeline defects based on magneto-optical imaging according to claim 1, characterized in that The magnetization module adopts a magnetization method along the axial direction of the pipeline, or along the circumferential direction, or at an angle of 45° to the axial direction.

3. The magnetic flux leakage detection device for pipeline defects based on magneto-optical imaging according to claim 1, wherein The interior of the magneto-optical detection module is filled with a high-strength filling material.

4. The magnetic flux leakage detection device for pipeline defects based on magneto-optical imaging according to claim 1, wherein The top polarizing film can be replaced with a polarizing sheet and does not need to be attached to the surface of the magneto-optical film.

5. The magnetic flux leakage detection device for pipeline defects based on magneto-optical imaging according to claim 1, characterized in that, In the ultra-thin magneto-optical conversion module, the ultra-thin light source selects a surface light source with a thickness of ≤1 mm.

6. The magnetic flux leakage detection device for pipeline defects based on magneto-optical imaging according to claim 1, characterized in that, The magneto-optical film selects a material that can realize the rotation of the light polarization direction under magnetic field conditions.

7. The magnetic flux leakage detection device for pipeline defects based on magneto-optical imaging according to claim 1, wherein The polarizing film can pass through the polarization light component and non-polarized light that are the same as the polarization direction of the polarizing film, and the non-polarized light becomes polarized light after passing through.

8. The magnetic flux leakage detection device for pipeline defects based on magneto-optical imaging according to claim 1, characterized in that, The magneto-optical detection module is held between the S-N bipolar and is closely attached to the pipe wall.

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