A pipeline magnetic flux leakage detection device with a bidirectional combined excitation structure

Abstract

The present invention is a pipeline magnetic flux leakage detection device with a bidirectional combined excitation structure, comprising an armature arranged in a pipeline, a first permanent magnet layer and a second permanent magnet layer correspondingly arranged near both end surfaces on the outer wall of the armature, the first permanent magnet layer and the second permanent magnet layer both comprising a plurality of permanent magnets uniformly circumferentially radiated and mounted on the outer wall of the armature, the magnetization directions of two adjacent permanent magnets in the first permanent magnet layer and the second permanent magnet layer are opposite, the magnetization directions of two corresponding permanent magnets in the first permanent magnet layer and the second permanent magnet layer are opposite, an iron brush is arranged between each permanent magnet and the inner wall of the pipeline, a circumferential sensor is arranged between two adjacent permanent magnets in the first permanent magnet layer and the second permanent magnet layer, and an axial sensor is arranged between two corresponding iron brushes in the first permanent magnet layer and the second permanent magnet layer. The present invention realizes magnetic flux leakage detection of blank areas between permanent magnets through the design of circumferential and axial two-dimensional excitation structures, expands the detection range, and eliminates the measurement blind area.

Description

Technical Field

[0001] The invention relates to the field of electromagnetic detection technology, and in particular to a pipeline magnetic leakage detection device with a bidirectional combined excitation structure. Background Art

[0002] Pipelines are an important means of long-distance oil and natural gas transmission. They are buried deep underground for a long time, and the external geological environment is harsh. Environmental corrosion, deformation, and pipe wall defects caused by human construction have become important factors that endanger pipeline transmission safety. In order to ensure production safety, professionals need to regularly perform in-service maintenance and inspections on pipelines to promptly discover hidden dangers of pipe wall defects, locate them in time, and carry out maintenance.

[0003] As the main method for detecting pipe wall defects, the pipeline magnetic flux leakage detection device is a measurement method that uses electromagnetic effects to detect the transmission characteristics of ferromagnetic materials in a magnetic circuit. Its principle is: using permanent magnets or electromagnets to generate an excitation magnetic field, and forming a closed magnetic circuit through the armature, iron brush, and pipeline to fully magnetize the ferromagnetic pipe wall to a magnetic saturation state; when there are defects in the pipe wall, the magnetic resistance at the defect position increases significantly, resulting in obvious magnetic leakage, and then the defect position and shape are located through magnetic sensitive elements, providing technical conditions for pipeline defect maintenance, with outstanding advantages such as in-service maintenance, rapid defect location, and non-destructive measurement.

[0004] Traditional magnetic flux leakage detection devices often use permanent magnets, armatures, iron brushes, etc. arranged along the axial direction of the pipeline as excitation units. In order to achieve matching of different pipeline inner diameters and fit with the inner wall of the pipeline, multiple excitation units are usually evenly arranged in the circumferential direction, but there are inevitably gaps between the units, which become measurement blind spots. In order to cover the measurement area between the excitation units, some devices use permanent magnets arranged along the circumference as excitation elements, but there is also the problem that magnetic flux leakage detection cannot be carried out at the location of the permanent magnet. In order to further reduce the measurement blind spot, some studies have adopted a staggered arrangement of double detection segments. The two segments compensate for each other's blind spot detection, which effectively expands the detection range, but there are inevitably problems such as the increase in the size of the entire device and the decrease in system reliability.

[0005] Therefore, how to effectively expand the range of the leakage magnetic detection area through improved design of the excitation device without increasing the volume of the device has become a research direction for pipeline leakage magnetic detection devices. It has important engineering application value and is of positive significance to the high-precision measurement, miniaturization design and reliability improvement of the detection device. Summary of the invention

[0006] The present invention aims to solve the deficiencies of the prior art and provides a pipeline magnetic flux leakage detection device with a bidirectional combined excitation structure.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A pipeline magnetic flux leakage detection device with a bidirectional combined excitation structure comprises an armature coaxially arranged inside a pipeline, a first permanent magnet layer and a second permanent magnet layer are correspondingly arranged on the outer wall of the armature near the two end surfaces, the first permanent magnet layer and the second permanent magnet layer both comprise a plurality of permanent magnets uniformly circumferentially radially mounted on the outer wall of the armature, two adjacent permanent magnets in the first permanent magnet layer have opposite magnetization directions, two adjacent permanent magnets in the second permanent magnet layer have opposite magnetization directions, two permanent magnets corresponding to the first permanent magnet layer and the second permanent magnet layer have opposite magnetization directions, an iron brush is arranged between each permanent magnet and the inner wall of the pipeline, a circumferential sensor is arranged between two adjacent permanent magnets in the first permanent magnet layer and between two adjacent permanent magnets in the second permanent magnet layer, and an axial sensor is arranged between two iron brushes corresponding to the first permanent magnet layer and the second permanent magnet layer.

[0009] The armature is a cylindrical tube structure.

[0010] The armature has a plurality of hollow holes uniformly extending through the side wall between the first permanent magnet layer and the second permanent magnet layer, and each hollow hole is located on the outer wall of the armature. Two of the four corners are connected to the inner corners of two adjacent permanent magnets of the first permanent magnet layer, and the other two corners are connected to the inner corners of two adjacent permanent magnets corresponding to the second permanent magnet layer.

[0011] The circumferential sensor and the axial sensor include a Hall sensor and an eddy current sensor.

[0012] The iron brush is made of high magnetic permeability and wear-resistant material, such as a magnetic material composed of multiple strands of steel wire, a magnetic material composed of ferrite or cobalt-vanadium alloy, and is tin-plated or coated with a non-magnetic wear-resistant coating of ceramic polymer.

[0013] The beneficial effects of the present invention are as follows: the present invention realizes leakage magnetic detection of blank areas between permanent magnets through the design of circumferential and axial two-dimensional excitation structures, thereby expanding the detection range and eliminating measurement blind spots; compared with the traditional dual detection device structure, the same range of detection functions is realized in a single detection device, which is conducive to the compactness and high integration of the system; the bidirectional excitation structure is used to increase the number of sensor detection points, and combined with multi-category sensor signal fusion technology, high-precision defect measurement and feature recognition capabilities are achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of the three-dimensional structure of the present invention;

[0015] Figure 2 This is a schematic diagram of the axial overall structure of the present invention;

[0016] Figure 3 It is a schematic diagram of the overall structure of the cross section of the present invention;

[0017] Figure 4 It is a schematic diagram of the structure of the armature;

[0018] Figure 5 It is a schematic diagram of the bidirectional magnetic field trend of a single excitation unit;

[0019] Figure 6 This is the principle diagram of axial area defect detection;

[0020] Figure 7 This is the principle diagram of circumferential area defect detection;

[0021] In the figure: 1-pipe; 2-armature; 3-first permanent magnet layer; 4-second permanent magnet layer; 5-permanent magnet; 6-iron brush; 7-circumferential sensor; 8-axial sensor; 9-hollow hole;

[0022] The following is a detailed description of the embodiments of the present invention with reference to the accompanying drawings. DETAILED DESCRIPTION

[0023] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0024] like Figures 1 to 4 As shown, a pipeline magnetic leakage detection device with a bidirectional combined excitation structure includes an armature 2 coaxially arranged inside a pipeline 1, a first permanent magnet layer 3 and a second permanent magnet layer 4 are correspondingly arranged on the outer wall of the armature 2 near both end surfaces, the first permanent magnet layer 3 and the second permanent magnet layer 4 each include a plurality of permanent magnets 5 uniformly circumferentially radially installed on the outer wall of the armature 2, two adjacent permanent magnets 5 in the first permanent magnet layer 3 have opposite magnetization directions, two adjacent permanent magnets 5 in the second permanent magnet layer 4 have opposite magnetization directions, two permanent magnets 5 corresponding to the first permanent magnet layer 3 and the second permanent magnet layer 4 have opposite magnetization directions, an iron brush 6 is arranged between each permanent magnet 5 and the inner wall of the pipeline 1, a circumferential sensor 7 is arranged between two adjacent permanent magnets 5 in the first permanent magnet layer 3 and between two adjacent permanent magnets 5 in the second permanent magnet layer 4, and an axial sensor 8 is arranged between two iron brushes 6 corresponding to the first permanent magnet layer 3 and the second permanent magnet layer 4.

[0025] The armature 2 is a cylindrical structure.

[0026] The armature 2 has a plurality of hollow holes 9 uniformly extending through the side wall between the first permanent magnet layer 3 and the second permanent magnet layer 4. Two of the four corners of each hollow hole 9 located on the outer wall of the armature 2 are respectively connected to the inner corners of two adjacent permanent magnets 5 of the first permanent magnet layer 3, and the other two corners are respectively connected to the inner corners of two adjacent permanent magnets 5 corresponding to the second permanent magnet layer 4.

[0027] The circumferential sensor 7 and the axial sensor 8 include a Hall sensor and an eddy current sensor.

[0028] The iron brush 6 is made of high magnetic permeability and wear-resistant material, such as a magnetic material composed of multiple strands of steel wire, a magnetic material composed of ferrite or cobalt-vanadium alloy, and is tin-plated or coated with a non-magnetic wear-resistant coating of ceramic polymer.

[0029] The present invention adopts a bidirectional combined excitation structure, and forms a space closed magnetic circuit along the circumferential and axial directions in a single magnetic circuit unit. Figure 5 As shown. For a single permanent magnet 5, it forms a circumferential magnetic circuit with the circumferentially adjacent permanent magnets 5 and an axial magnetic circuit with the adjacent axial permanent magnets 5, thereby realizing a spatial magnetic circuit structure connected end to end in a single magnetic circuit unit composed of four permanent magnets 5 through a clever design of the magnetization direction.

[0030] In order to reduce the internal friction and leakage of the bidirectional magnetic circuit in the armature 2, the armature 2 configuration is designed, and the center of a single magnetic circuit unit is hollowed out, such as Figure 4 As shown, by increasing the magnetic resistance of the air in the diagonal direction, the magnetic path direction is limited to the rectangular magnetic circuit in the first connected armature 2.

[0031] When the present invention is used, it is used in conjunction with an external power device and a recording device, wherein the power device is located at the front end of the present invention, providing power for the unidirectional movement of the present invention along the pipeline 1. The present invention uses electromagnetic effects to detect defects on the inner wall of the pipeline 1 and generates a leakage magnetic model. The recording device collects and analyzes the detection results and running mileage, and produces external output results. As the core part of the pipe wall excitation and leakage magnetic model generation, the present invention plays a decisive role in the system defect detection capability and detection accuracy.

[0032] During the magnetic flux leakage detection process of the pipeline 1, the detection device of the present invention moves along the flow direction of the liquid in the pipeline 1 driven by the power device, and at the same time, the detection device detects the quality of the inner wall of the pipeline using the circumferential sensor 7 and the axial sensor 8. According to the relative position with respect to the detection device, the inner wall defects of the pipeline can be divided into three categories: axial defects: the defects are located on the straight line where the axial permanent magnet is located; circumferential defects: the defects are located on the arc line where the circumferential permanent magnet is located; and defects in other positions.

[0033] For axial defects, since their position is on the line connecting a pair of axial permanent magnets 5, when the defect is located between adjacent permanent magnets 5 as the detection device moves, the axial sensor 8 is triggered to identify the signal characteristics. The adjacent axial permanent magnets 5, iron brushes 6, armature 2, and pipe wall form an axial magnetic circuit, such as Figure 6As shown, the pipe wall is fully magnetized. When there is an axial defect, the pipe wall thickness becomes thinner, causing the already magnetically saturated pipe wall to produce leakage magnetic flux, which is convenient for the axial sensor 8 to collect. The Hall sensor in the axial sensor 8 also includes radial and axial bidirectional collection functions, and the defect characteristics are identified through bidirectional magnetic flux density signals. The eddy current sensor in the axial sensor 8 assists in the defect depth measurement and the identification of internal and external surface defects.

[0034] For circumferential defects, the detection principle is as follows: Figure 7 As shown, the two permanent magnets 5 adjacent to the left and right of the defect position form a circumferential magnetic circuit and fully magnetize the pipe wall. When there is a defect, the thickness of the pipe wall at the defect becomes thinner, causing the magnetic field of the pipe wall that has been magnetically saturated to leak and be sensed by the circumferential sensor 7. The two-axis Hall sensors in the circumferential sensor 7 detect the axial and radial magnetic flux densities respectively, and obtain the leakage magnetic field characteristic distribution corresponding to the current defect, providing a basis for signal extraction and feature recognition. The eddy current sensor in the circumferential sensor 7 assists in judging the defect depth and distinguishing the inner and outer surface defects by measuring the distance between the sensor and the inner wall of the pipeline 1.

[0035] When the location of the defect does not belong to the above two types, as the detection device moves along the pipeline 1, the defect will inevitably be moved to the circumferential magnetic circuit, and the problem can be converted into a circumferential defect for processing. It is worth noting that for circumferential defects, when the defect position is not in the middle of the adjacent circumferential permanent magnets 5 on the left and right, the characteristics and amplitude of the detection signal are affected due to the small angle offset from the action position of the circumferential sensor 7. In this regard, the present invention can adopt the measurement technology of multi-sensor assisted measurement and signal fusion. When the defect is located such as Figure 5 When inside a single spatial magnetic circuit composed of four permanent magnets 5, the two axial sensors 8 and the two circumferential sensors 7 are sensitive to the defect, and the signals reflect the signal characteristics related to the sensor action position. By fusing and dynamically collecting the four sensor signals, multi-dimensional feature extraction and data matching of the defect can be effectively performed, providing technical conditions for high-precision defect positioning and identification.

[0036] The pipeline magnetic flux leakage detection device of the present invention is mainly composed of permanent magnet 5, armature 2, iron brush 6, two-axis Hall sensor, eddy current sensor and other components, which form a complete magnetic circuit with the pipeline 1 of ferromagnetic material to realize the accurate magnetic flux leakage signal acquisition function. Among them, the permanent magnet 5 is an excitation element in the magnetic circuit, which generates a directional magnetic field and magnetization effect to the outside according to the magnetization direction of the permanent magnet 5, fully magnetizes the pipe wall in the detection area, and provides conditions for generating magnetic flux leakage signals. The armature 2 is made of high magnetic permeability metal material, which plays the role of guiding the magnetic field trend and fixing the permanent magnet 5. The iron brush 6 is fixed between the permanent magnet 5 and the pipeline 1, and attracts and contacts the inner side of the pipe wall while guiding the magnetic circuit, reducing the gap between the detection device and the pipeline 1 and playing an anti-wear role. The Hall sensor is arranged between two adjacent permanent magnets 5 to measure the magnetic flux density of the radial and axial degrees of freedom inside the pipeline, thereby obtaining a magnetic flux leakage signal. The eddy current sensor is also arranged between two adjacent permanent magnets 5 to detect the relative position change between the sensor and the pipe wall, thereby assisting in judging the position and shape of the defect. Through the joint action of the above-mentioned core components of the detection section, the accurate detection function of pipeline inner wall defects can be achieved.

[0037] In order to eliminate the detection blind area and expand the detection range and accuracy, the present invention makes an innovative design on the magnetic circuit structure of the detection device and proposes a bidirectional combined excitation structure. The outstanding structural feature is that the traditional circumferential excitation structure is combined with the axial excitation structure, and a double-row alternating magnetized permanent magnet 5 is used to simultaneously generate the excitation magnetic field along the circumferential and axial directions, and the hollow armature 2 is designed according to the direction of the magnetic circuit to further enhance the bidirectional excitation magnetic field strength. Through the design of the above innovative structure, full coverage of the area where the detection node is located is achieved, the measurement blind area is eliminated, and the detection accuracy is improved.

[0038] The advantages of the present invention are:

[0039] Through the design of the circumferential and axial two-dimensional excitation structure, the leakage magnetic field detection of the blank area between the permanent magnets 5 is realized, the detection range is expanded, and the measurement blind area is eliminated;

[0040] Compared with the traditional dual detection device structure, the same range of detection functions are achieved in a single detection device, which is conducive to the development of compact and highly integrated systems;

[0041] The bidirectional excitation structure is used to increase the number of sensor detection points, and combined with multi-category sensor signal fusion technology, high-precision defect measurement and feature recognition capabilities are achieved.

[0042] The present invention is described above by way of example in conjunction with the accompanying drawings. It is obvious that the specific implementation of the present invention is not limited to the above-mentioned method. As long as various improvements are made using the method concept and technical solution of the present invention, or are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. A pipeline magnetic flux leakage detection device with a bidirectional combined excitation structure, characterized in that: The invention comprises an armature (2) coaxially arranged inside a pipe (1); a first permanent magnet layer (3) and a second permanent magnet layer (4) are correspondingly arranged on the outer wall of the armature (2) near both end surfaces; the first permanent magnet layer (3) and the second permanent magnet layer (4) each comprise a plurality of permanent magnets (5) uniformly and circumferentially radially arranged on the outer wall of the armature (2); two adjacent permanent magnets (5) in the first permanent magnet layer (3) have opposite magnetization directions; two adjacent permanent magnets (5) in the second permanent magnet layer (4) have opposite magnetization directions; two corresponding permanent magnets (5) in the first permanent magnet layer (3) and the second permanent magnet layer (4) have opposite magnetization directions; an iron brush (6) is arranged between each permanent magnet (5) and the inner wall of the pipe (1); the first permanent magnet layer (3) A circumferential sensor (7) is provided between two adjacent permanent magnets (5) in the first permanent magnet layer (3) and between two adjacent permanent magnets (5) in the second permanent magnet layer (4); an axial sensor (8) is provided between two iron brushes (6) corresponding to the first permanent magnet layer (3) and the second permanent magnet layer (4); the armature (2) is a cylindrical tube structure; a plurality of hollow holes (9) are evenly penetrated on the side wall of the armature (2) between the first permanent magnet layer (3) and the second permanent magnet layer (4); two of the four corners of each hollow hole (9) located on the outer wall of the armature (2) are respectively connected to the inner corners of the two adjacent permanent magnets (5) in the first permanent magnet layer (3), and the other two corners are respectively connected to the inner corners of the two adjacent permanent magnets (5) corresponding to the second permanent magnet layer (4).

2. A pipeline magnetic flux leakage detection device with a bidirectional combined excitation structure according to claim 1, characterized in that: The circumferential sensor (7) and the axial sensor (8) include a Hall sensor and an eddy current sensor.

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