Permanent magnet structure-based pipeline demagnetization device and application thereof

Abstract

A pipeline demagnetization device based on a permanent magnet structure includes a central piece and permanent magnets distributed on the central piece. A magnetic field with alternating directions is formed in a wall of a pipeline in an axial direction from front to back, and strength of the magnetic field gradually decreases. The pipeline demagnetization device can be applied to the pipeline demagnetization using a built-in structure or an externally-built structure. The pipeline demagnetization device spatially constructs a set of stable alternately-decayed magnetic fields, so that the wall of the pipeline experiences the set of alternately-decayed magnetic fields when the pipeline that is magnetized spatially displaces relative to the set of alternately-decayed magnetic fields, thereby realizing demagnetization.

Claims

1. A pipeline demagnetization device based on a permanent magnet structure, the pipeline demagnetization device comprising a central piece and permanent magnets distributed on the central piece, wherein a magnetic field with alternating directions is formed in a wall of a pipeline in an axial direction from front to back, and strength of the magnetic field gradually decreases, wherein the permanent magnets are series structures composed of double ring magnets, comprising series groups formed by two radially-magnetized ring magnets with opposite magnetization directions.

2. The pipeline demagnetization device based on the permanent magnet structure according to claim 1, wherein the ring magnets are entire radially-magnetized magnetic rings or are formed by splicing a plurality of magnetic steel.

3. The pipeline demagnetization device based on the permanent magnet structure according to claim 1, wherein the series structures composed of the double ring magnets are placed at intervals along the axial direction of the central piece, magnetization directions between the two ring magnets in each of the series structures are opposite, and in two adjacent series structures, magnetization directions between the adjacent ring magnets are same.

4. The pipeline demagnetization device based on the permanent magnet structure according to claim 1, wherein magnetic performances and sizes of the two ring magnets forming the series structure are same; for each series structure, sizes of the ring magnets are gradually reduced, magnetic performances are gradually decreased, and a decaying magnitude of the strength of the magnetic field formed in the wall of the pipeline are 1 to 99%, preferably 10 to 50%.

5. The pipeline demagnetization device based on the permanent magnet structure according to claim 1, wherein the central piece is a magnetically permeable member or a non-magnetically permeable member, and is a solid piece or a hollow piece.

6. An application of the pipeline demagnetization device based on the permanent magnet structure according to claim 1, wherein the pipeline demagnetization device has a built-in structure for demagnetization inside a long pipeline, and is pulled forward by a pressure in the pipeline, so that the pipeline that is magnetized experiences a process of alternatively decaying magnetic fields to realize demagnetization.

7. The application of the pipeline demagnetization device based on the permanent magnet structure according to claim 6, wherein the pipeline demagnetization device is provided in one or plurality, independently arranged in the pipeline or connected to a rear end of a magnetic filter or a rear end of a magnetic flux leakage detector.

8. The application of the pipeline demagnetization device based on the permanent magnet structure according to claim 7, wherein strength of a magnetic field formed by the permanent magnet arranged at a forefront of the pipeline demagnetization device is greater than a coercive force of the pipeline.

9. The application of the pipeline demagnetization device based on the permanent magnet structure according to claim 7, wherein when the plurality of the pipeline demagnetization devices are arranged, the strength of the magnetic field formed in the wall of the pipeline gradually decreases from front to back.

10. The application of the pipeline demagnetization device based on the permanent magnet structure according to claim 6, wherein the pipeline demagnetization device is provided with a support piece that holds the pipeline demagnetization device at a center of the pipeline, that is fixed on the central piece, and that is a magnetically permeable or non-magnetically permeable member.

11. The pipeline demagnetization device based on the permanent magnet structure according to claim 10, wherein the support piece comprises a steel brush, a roller or a cup leather.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a structural diagram of the disclosure in Embodiment 1;

(2) FIG. 2 is a magnetic induction intensity map formed by the disclosure in Embodiment 1;

(3) FIG. 3 is a structural diagram of the disclosure in Embodiment 2;

(4) FIG. 4 is a magnetic induction intensity map formed by the disclosure in Embodiment 2;

(5) FIG. 5 is a diagram showing an application of the disclosure in Embodiment 3;

(6) FIG. 6 is a diagram showing an application of the disclosure in Embodiment 4;

(7) FIG. 7 is a diagram showing an application of the disclosure in Embodiment 5;

(8) FIG. 8 is a diagram showing an application of the disclosure in Embodiment 6;

(9) FIG. 9 is a structural diagram of the disclosure used in Embodiment 7;

(10) FIG. 10 is a structural diagram of and a magnetic induction intensity map formed by the disclosure in Embodiment 7; and

(11) FIG. 11 is a structural diagram of and a magnetic induction intensity map formed by the disclosure in Embodiment 8.

DESCRIPTION OF THE EMBODIMENTS

(12) The disclosure will be elaborated hereafter in connection with the specific embodiments. The following embodiments will help those skilled in the art to further understand the disclosure, but do not limit the disclosure in any form. It should be pointed out those of ordinary skill in the art may further make a plurality of variations and improvements without departing from the concept of the disclosure. These all belong to the protection scope of the disclosure.

Embodiment 1

(13) A pipeline demagnetization device based on a permanent magnet structure 0 has a structure shown in FIG. 1, which consists of an iron core 1 and permanent magnets 2 distributed on the iron core 1.

(14) The iron core 1 may be a magnetically permeable material to form a magnetic circuit, and also may be a partially non-magnetically permeable material. The selected materials are mainly for the purpose of forming a suitable magnetic circuit. Each of the permanent magnets 2 for use is a single ring magnet, which employs a radially-magnetized ring magnet. The ring magnet may be an entire radially-magnetized magnetic ring or is formed by splicing a plurality of magnetic steel. The single ring magnets are placed at intervals along an axial direction of the central piece, and magnetization directions are alternately reversed one by one. Magnetic performances of the single ring magnets arranged along the axial direction of the central piece are gradually decreased, and diameters or thicknesses of the magnets are gradually reduced to form an axially-decayed alternating magnetic field with a decaying magnitude of 1 to 99%. In the present embodiment, the decaying magnitude is 20%, and changes in the intensity of the magnetic induction formed are shown in FIG. 2. A-E in FIG. 1 and FIG. 2 respectively correspond to the position and the strength of the magnetic field at the position.

(15) In addition, in order to facilitate the use of the pipeline demagnetization device 0 in a pipeline 4, the pipeline demagnetization device 0 is further provided with a support piece 3 that holds it at a center of the pipeline, and that is fixed on the iron core 1. The support piece 3 may be a magnetically permeable material, such as a magnetically permeable steel brush, which, while serving as a support, may also be used as part of the magnetic circuit, or may be a non-magnetically permeable material, such as non-magnetic stainless steel brush, polyurethane, roller or cup leather, etc., which only serves as a support piece. Also, locally, no support structure is required. The selected materials are mainly for the purpose of forming a suitable magnetic circuit and serving as the support piece.

Embodiment 2

(16) A pipeline demagnetization device based on the permanent magnet structure 0 has a structure shown in FIG. 3, which consists of the iron core 1 and the permanent magnets 2 distributed on the iron core 1. The structure is the same as that in Embodiment 1, except that the permanent magnet 2 used in the present embodiment is a series structure composed of the double ring magnets, which are two radially-magnetized ring magnets with opposite magnetization directions form a series group. For each set of the double ring magnets, two radially-magnetized ring magnets with opposite magnetization directions form a set. The radial ring magnet may be formed by splicing a plurality of magnetic steel, or may be an entire radially-magnetized magnetic ring. Each set of double ring magnet forms a certain polarity in the wall of the pipeline. A plurality of sets of ring magnets are placed axially at intervals, and the magnetization directions formed in the wall of the pipeline are alternately reversed one by one, forming a magnetic field with alternating polarity in the wall of the pipeline. At the same time, the performance of each set of magnetic rings is reduced one by one, or dimensions such as diameters/thicknesses of the magnetic ring gradually change to realize an alternating magnetic field that gradually decays axially. The series structures composed of the double ring magnets are placed at intervals along the axial direction of the central piece. The magnetization directions between the two ring magnets in the series structure are opposite. In two adjacent series structures, the magnetization directions between the adjacent ring magnets are the same. The magnetic performances and sizes of the two ring magnets forming the series structure are the same. Magnetic performances of the series structures are gradually decreased, such as diameters or thicknesses of the magnets are gradually decreased, and a decaying magnitude of the strength of the magnetic field formed in the wall of the pipeline is 1 to 99%. In the present embodiment, the decaying magnitude is 35%. Grouping double ring magnets in series has advantages of adjusting the strength of the magnetic field of each waveform step by step to achieve precise control on demagnetization, the intensity of the magnetic induction formed are shown in FIG. 4. A-C in FIG. 3 and FIG. 4 respectively correspond to the position and the strength of the magnetic field at the position.

Embodiment 3

(17) For a pipeline demagnetization device based on the permanent magnet structure 0, the device has a built-in structure for demagnetization inside a long pipeline, and is pulled forward by a pressure in the pipeline, so that the pipeline that is magnetized experiences a process of alternatively decaying magnetic fields to realize demagnetization.

(18) When performing magnetic filtering or magnetic flux leakage detection on long-distance natural gas and oil pipelines, the magnetic filter 5 is under the pressure of the pipeline, and the magnetic filter 5 will move forward along the pipeline. A strong magnet is mounted on the magnetic filter 5, so that wherever the magnetic filter 5 goes, the pipeline wall will be saturatedly magnetized, so that the entire long-distance transportation pipeline is severely magnetized.

(19) For long-distance natural gas and oil pipelines, the pipeline demagnetization device 0 has a built-in structure. The demagnetization device may be a single set of device, which is pulled forward by a pressure in the pipeline such that each position of the pipeline experiences a process of alternatively decaying magnetic fields to realize demagnetization. The demagnetization device may also be used as an accessory device, which may be hung on a rear end of the magnetic filter 5, as shown in FIG. 5, so that the demagnetization operation for the pipelines is completed while performing the traditional filtering or magnetic leakage detection operations. It should be noted that strength of a magnetic field formed by the permanent magnet arranged at the forefront of the demagnetization device is greater than a coercive force of the pipeline.

Embodiment 4

(20) For a pipeline demagnetization device based on the permanent magnet structure 0, the device has a built-in structure for demagnetization inside a long pipeline. The structure is the same as that in Embodiment 3, except that in the present embodiment, the pipeline demagnetization device 0 is connected at a rear end of the magnetic flux leakage detector 6, as shown in FIG. 6.

Embodiment 5

(21) For a pipeline demagnetization device based on the permanent magnet structure 0, the device has a built-in structure for demagnetization inside a long pipeline, as shown in FIG. 7. In the present embodiment, one pipeline demagnetization device 0 is arranged for demagnetization.

Embodiment 6

(22) For a pipeline demagnetization device based on the permanent magnet structure 0, the device has a built-in structure for demagnetization inside a long pipeline. As shown in FIG. 8, in the present embodiment, a plurality of pipeline demagnetization devices 0 are connected in series for demagnetization. When the plurality of the demagnetization devices are provided, the strength of the magnetic field formed in the wall of the pipeline gradually decreases from front to back, and for pipelines with different wall thicknesses and materials, the number of waveforms and the decaying magnitude of the required alternating magnetic field are also different. When a large number of waveforms are required, several demagnetization joints may be connected in series to complete operations if one demagnetization joint is not enough to realize these waveforms. Theoretically, the larger the number of the waveforms of the alternating magnetic fields and the smaller the decaying magnitude, the better the demagnetization effect. Actually, in the design, a suitable number of waveforms and decaying magnitude are selected in consideration of manufacturing costs and engineering feasibility.

Embodiment 7

(23) For the application of the pipeline demagnetization device based on the permanent magnet structure, the device has an externally-built structure. As shown in FIG. 9, an anisotropic bonded NdFeB magnetic powder 7 is heated for extrusion forming through a screw and a heating system 8, a forming mould 10 is provided at a rear end, and an orientation magnetic field 9 is provided inside the forming mould 10. During the process of extrusion molding, since the finished fittings are magnetized by the orientation magnetic field, the finished fittings will be magnetic. An externally-built pipeline demagnetization device 0 may be placed at a rear end of the extrusion molding equipment or at an exit of the molding die. The demagnetization may be achieved as long as the finished fittings 11 are passed through the demagnetization device.

(24) In the present embodiment, the demagnetization device used has a structure shown in FIG. 10, each of the permanent magnets is an axially-magnetized magnet 12, and the polarity direction changes alternatively. The permanent magnets may have the same size and are arranged in a manner that the magnet performance gradually decreases, or may have the same performance and are arranged in a manner that the size decreases from large to small, or may be a combination of shapes and sizes to construct a set of alternately-decayed magnetic fields for demagnetization of the extrusion-molded fittings, so that the fittings experience a process of alternatively decaying magnetic fields by passing through the center of the demagnetization device to realize demagnetization. A pole sheet 13 is placed in the middle of the magnet. The pole sheet 13 may be a magnetic conductor to draw more magnetic field lines, or may be a non-magnetic conductor, which is also a means of forming a specific strength of the magnetic field. The formed magnetic induction intensity is shown in FIG. 10, and the strength of the magnetic field formed by the permanent magnet provided at the foremost end of the demagnetization device is greater than the coercive force of the molded fittings.

Embodiment 8

(25) For the application of the pipeline demagnetization device based on the permanent magnet structure, the device has an externally-built structure, and is used in the same way as Embodiment 7. The pipeline demagnetization device has the same structure as that in Embodiment 7, except in that in the present embodiment, some pole sheets 13 may be replaced with magnets 15 that are radially-magnetized, and may also be arranged in a manner that the polarity is alternatively placed, as shown in FIG. 11, so as to draw more magnetic field lines for forming a stronger magnetic field waveform. The formed magnetic induction intensity is shown in FIG. 11.

Embodiment 9

(26) A pipeline demagnetization device based on a permanent magnet structure, consisting of a central piece and permanent magnets distributed on the central piece. A magnetic field with alternating directions is formed in a wall of the pipeline in an axial direction from front to back, and strength of the magnetic field gradually decreases.

(27) The permanent magnet used in the present embodiment is a radially-magnetized ring magnet, and the ring magnet is an entire radially-magnetized magnetic ring. Each ring magnet is placed at intervals along an axial direction of the central piece, and magnetization directions are alternately reversed one by one. Sizes of the single ring magnet arranged along the axial direction of the central piece are gradually reduced, such as diameters or thicknesses of the magnets are gradually reduced, magnetic performances are gradually-decreased, and the strength of the magnetic field formed by the magnet in the pipeline are gradually decayed with a decaying magnitude of 10%. Strength of a magnetic field formed by the permanent magnet arranged at the forefront of the demagnetization device is greater than a coercive force of the pipeline.

(28) The central piece used is a magnetically permeable member or a non-magnetically permeable member, including solid or hollow iron core, aluminum core or copper core, stainless steel core, may be a magnetically permeable material to form a magnetic circuit, and also may be a partially non-magnetically permeable material. The materials selected are mainly for the purpose of forming a suitable magnetic circuit. In the present embodiment, a solid copper core is adopted.

(29) The device may have a built-in structure for demagnetization inside a long pipeline, and is pulled forward by a pressure in the pipeline, so that the pipeline that is magnetized experiences a process of alternatively decaying magnetic fields to realize demagnetization.

(30) When performing magnetic filtering or magnetic flux leakage detection on long-distance natural gas and oil pipelines, the magnetic filter or magnetic flux leakage detector is under the pressure of the pipeline, and the magnetic filter or magnetic flux leakage detector will move forward along the pipeline. A strong magnet may be mounted on the magnetic filter or the magnetic flux leakage detector, so that wherever the magnetic filter or magnetic flux leakage detector goes, the pipeline wall will be saturatedly magnetized, so that the entire long-distance transportation pipeline is severely magnetized.

(31) For long-distance natural gas and oil pipelines, the demagnetization device has a built-in structure. The demagnetization device may be a single set of device, which is pulled forward by a pressure in the pipeline such that each position of the pipeline experiences a process of alternatively decaying magnetic fields to realize demagnetization. The demagnetization device may also be used as an accessory device, which may be hung on a rear end of the magnetic filter or magnetic flux leakage detector such that the demagnetization operation for the pipelines is completed while performing the traditional filtering or magnetic leakage detection operations.

(32) In order to ensure that the demagnetization device is always located at the center of the pipeline so as to ensure the demagnetization effect, a support piece is also fixed on the center piece. The support piece may be a magnetically permeable material, such as a magnetically permeable steel brush, which, while serving as a support, may also be used as part of the magnetic circuit, or may be a non-magnetically permeable material, such as non-magnetic stainless steel brush, polyurethane, roller or cup leather, etc., which only serves as a support piece; also, locally, no support structure is required. The materials selected are mainly for the purpose of forming a suitable magnetic circuit and serving as the support piece. The support piece adopted in the present embodiment is a roller.

Embodiment 10

(33) A pipeline demagnetization device based on a permanent magnet structure has the same structure as Embodiment 9, except in that the permanent magnets used in the present embodiment are radially-magnetized ring magnets formed by splicing a plurality of magnetic steel, and a decaying magnitude for the strength of the magnetic field formed by the magnet in the pipeline is 20%. The center piece used is a hollow aluminum core, and the support for use is a cup leather.

Embodiment 11

(34) A pipeline demagnetization device based on the permanent magnet structure has the same structure as Embodiment 9, except that the permanent magnet used in the present embodiment is a series structure composed of the double ring magnet, which is a series group formed by two radially-magnetized ring magnets with opposite magnetization directions. The ring magnet is an entire radially-magnetized magnetic ring. Employing such series set has advantages of adjusting the strength of the magnetic field of each waveform step by step to achieve precise control on demagnetization. In two adjacent series structures, the magnetization directions between the adjacent ring magnets are the same. The magnetic performances and sizes of the two ring magnets forming the same series structure are the same. Magnetic performances of each series structure are gradually decreased, such as diameters or thicknesses are gradually reduced. A decaying magnitude of the strength of the magnetic field formed in the wall of the pipeline is 5%. In the present embodiment, the support piece may not be adopted.

Embodiment 12

(35) A pipeline demagnetization device based on a permanent magnet structure has the same structure as Embodiment 11, except in that the ring magnets in the present embodiment are formed by splicing a plurality of magnetic steel, and the decaying magnitude is 60%. When the device performs demagnetization, the externally-built structure is adopted, so the support piece is not required. Each of the permanent magnets is axially magnetized for demagnetization of extrusion-molded fittings, so that the fittings experience a process of alternatively decaying magnetic fields by passing through the demagnetization device to realize demagnetization. During the process of extrusion molding, the finished extrusion-molded fittings are magnetized by the orientation magnetic field, so the finished fittings will be magnetic. An externally-built demagnetization device may be placed at the end of the extrusion molding equipment or at the exit of the molding die. The demagnetization may be achieved as long as the finished fittings are passed through the demagnetization device.

(36) The extrusion-molded fittings are magnetized by an orienting magnetic field during an extrusion process, and the pipeline demagnetization device is arranged at a rear portion of the orienting magnetic field. Strength of a magnetic field formed by the permanent magnet arranged at the forefront of the demagnetization device is greater than a coercive force of the molded fittings. The pole sheets may further be provided between the above ring magnets. The pole sheets used are magnetically permeable materials.

(37) The specific embodiments of the disclosure have been described above. It should be understood that the disclosure is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the disclosure.