WO2019056514A1 - 一种基于永磁结构的管道退磁装置及其应用 - Google Patents

一种基于永磁结构的管道退磁装置及其应用 Download PDF

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Publication number
WO2019056514A1
WO2019056514A1 PCT/CN2017/109523 CN2017109523W WO2019056514A1 WO 2019056514 A1 WO2019056514 A1 WO 2019056514A1 CN 2017109523 W CN2017109523 W CN 2017109523W WO 2019056514 A1 WO2019056514 A1 WO 2019056514A1
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Prior art keywords
pipe
permanent magnet
demagnetization
magnetic
demagnetization device
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PCT/CN2017/109523
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English (en)
French (fr)
Inventor
张慧欣
张诗渊
汪小青
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上海杰灵磁性器材有限公司
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Application filed by 上海杰灵磁性器材有限公司 filed Critical 上海杰灵磁性器材有限公司
Priority to US16/649,141 priority Critical patent/US11626230B2/en
Publication of WO2019056514A1 publication Critical patent/WO2019056514A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F13/00—Apparatus or processes for magnetising or demagnetising
    • H01F13/006—Methods and devices for demagnetising of magnetic bodies, e.g. workpieces, sheet material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F7/00—Magnets
    • H01F7/02—Permanent magnets [PM]
    • H01F7/0205—Magnetic circuits with PM in general
    • H01F7/021—Construction of PM
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F7/00—Magnets
    • H01F7/02—Permanent magnets [PM]
    • H01F7/0205—Magnetic circuits with PM in general
    • H01F7/0221—Mounting means for PM, supporting, coating, encapsulating PM

Definitions

  • the invention relates to a demagnetization device, in particular to a pipe demagnetization device based on a permanent magnet structure and an application thereof.
  • MFL Magnetic Flux Leakage
  • the equipment moves along the pipeline under the pressure of the pipeline.
  • the testing device itself carries a section of magnetic poles that saturate the wall of the tube that passes through and form a magnetic circuit with the wall of the tube. If there is a defect in the pipe wall, the magnetic lines of force in the pipe wall will redistribute around the defect, and a part of the magnetic lines leak out to enter the surrounding medium.
  • the leaked magnetic field is detected by a Hall probe located between the magnetic poles and closely placed in the circumferential direction of the tube wall. These signals are filtered, amplified, converted and processed and recorded in the memory. After the detection is completed, the data is analyzed by the data analysis system. The judgment and identification are performed to detect the corrosion state of the pipe.
  • Pipeline magnetic flux leakage detection technology creates a new problem: the oil and gas pipeline is saturated with magnetization during detection, and the residual magnetism remains in the pipeline matrix and is not eliminated. Pipes produced by different processes and different grades of materials will have different magnetic properties and different residual magnetization.
  • Pipeline repair often requires an electric welding process, but Electric welding of pipes with residual magnetism will result in arcing and arcing, which greatly affects the quality of welding.
  • the magnetic field strength in the slits even reaches 2000 Gs or more, which increases the difficulty of demagnetization and fails to form an effective standard operation.
  • API American Petroleum Institute
  • conventional demagnetization methods include high temperature demagnetization, coil demagnetization, and ground demagnetization.
  • High-temperature demagnetization requires heating the ferromagnetic workpiece above the Curie point and demagnetizing it in the absence of an external magnetic field.
  • the coil is demagnetized by winding a coil on the pipe and applying an alternating current to demagnetize.
  • the demagnetization of the ground is to place the magnetic conductive material at the joint of the pipe. Since the magnetic conductive material is equivalent to providing a short-circuit path, the magnetic flux is penetrated into the magnetic conductive material as much as possible, and the magnetic field strength at the welded portion is reduced.
  • Chinese patent CN102866367A discloses a demagnetization detecting device and a demagnetization detecting method thereof.
  • the demagnetization detecting device is used for electrically connecting to the power control unit of the permanent magnet motor to be tested, and the power control unit is electrically connected to the DC power source.
  • the demagnetization detecting device senses the voltage value to be tested and the current value to be measured of the DC power source, and calculates the power value to be tested of the DC power source according to the voltage value to be measured and the current value to be tested.
  • the demagnetization detecting device determines the difference between the power value to be tested and the standard power value, and judges that the permanent magnet motor to be tested exhibits a demagnetization state according to the difference.
  • the device uses an electromagnet for demagnetization and cannot be applied in long-distance pipelines.
  • the object of the present invention is to overcome the above drawbacks of the prior art and to provide a space A permanent magnet structure-based pipe demagnetization device that realizes an alternating attenuation magnetic field.
  • a pipe demagnetization device based on a permanent magnet structure is composed of a center piece and a permanent magnet distributed on the center piece, and a magnetic field alternately changing direction is formed in the pipe wall from the front to the rear, and the magnetic field strength is gradually reduced. small.
  • the permanent magnet is a series structure composed of a single ring magnet or a double ring magnet.
  • the single ring magnet is a radially magnetized ring magnet, which is a magnetic ring that is magnetized in the whole radial direction or is formed by splicing a plurality of magnetic steels.
  • Each of the single ring magnets is axially spaced along the center piece, and the magnetization directions are alternately reversed one by one, and the size of the single ring magnet disposed along the axial direction of the center piece is gradually reduced, for example, the diameter or thickness of the magnet is gradually reduced, and the magnetic properties are Gradually decreasing, the strength of the magnetic field formed by the magnet in the pipe is gradually attenuated, and the attenuation range is 1-99%.
  • the attenuation amplitude is 10-50% to achieve an alternating magnetic field that is gradually attenuated in the axial direction.
  • the series structure composed of the double ring magnets is a series group of two ring magnets having opposite radial magnetization and opposite magnetization directions.
  • the ring magnet is a magnetic ring that is magnetized by the entire radial direction or is formed by splicing a plurality of magnetic steels.
  • the advantage of the double ring magnets being connected in series is that the magnetic field strength of each waveform can be adjusted step by step to achieve precise demagnetization control.
  • each double ring magnet is placed along the axial direction of the center piece, and the magnetization directions between the two ring magnets in the series structure are opposite, and the magnetization between the adjacent ring magnets in the adjacent two series structures In the same direction, the magnetic properties and dimensions of the two ring magnets constituting the series structure are the same, and the magnetic properties of each series structure are gradually reduced.
  • the diameter or thickness of the magnet may gradually decrease, and the magnetic field strength attenuation amplitude formed in the tube wall is 1 -99%.
  • the attenuation amplitude is 10-50% to achieve an alternating magnetic field that is gradually attenuated in the axial direction.
  • the central member is a magnetic conductive member or a non-magnetic conductive member, and comprises a solid or hollow iron core, an aluminum core or a copper core, a stainless steel core, and may be a magnetic conductive material for forming a magnetic circuit; or may be partially non-conductive. Magnetic material. The materials selected are mainly for the purpose of forming a suitable magnetic circuit.
  • the demagnetization device of the pipeline based on permanent magnet structure The device is a built-in structure for demagnetizing the inside of a long pipe, and is subjected to pressure traction in the pipe to cause the magnetized pipe to undergo an alternating decaying magnetic field to realize demagnetization.
  • the magnetic pig or magnetic flux leakage detector moves forward along the pipeline under the pressure of the pipeline.
  • a strong magnet is installed on the magnetic pig or the magnetic flux leakage detector.
  • the tube is saturated and magnetized wherever the device is located, so that the entire long-distance pipeline is severely magnetized.
  • the demagnetization device has a built-in structure.
  • the demagnetization device may be a separate device, which is pulled by pressure in the tube, so that each pipe undergoes a process of alternating attenuating magnetic field, thereby realizing demagnetization; the demagnetization device can also be used as an attachment device to be hung on the magnetic pig Or the back end of the magnetic flux leakage detector, so that the pipe demagnetization operation is completed at the same time as the conventional pigging or magnetic flux leakage detecting operation.
  • the device is provided with one or more, disposed directly in the conduit or connected to the rear end of the magnetic pig or magnetic flux leakage detector.
  • the strength of the magnetic field formed by the permanent magnet disposed at the foremost end of the demagnetization device is greater than the coercive force of the pipe.
  • the strength of the magnetic field formed in the pipe wall gradually decreases from front to back.
  • the number and attenuation degree of the alternating magnetic field waveforms required are also different.
  • the number of waveforms required is large and a demagnetization section is not enough to implement these waveforms, it can be done in series by several demagnetization sections.
  • the more the number of alternating magnetic field waveforms and the smaller the attenuation amplitude the better the demagnetization effect.
  • the pipe demagnetization device is also provided with a support member that holds it in the center of the pipe and is fixed to the center member.
  • the support member may be a magnetic conductive material, such as a magnetic conductive steel brush, which may also serve as a part of the magnetic circuit as a support member, or may be a non-magnetic conductive material such as a non-magnetic stainless steel brush, polyurethane, roller or leather.
  • the bowl or the like is only used as a support member; the support structure may not be required locally.
  • the materials selected are mainly for forming a suitable magnetic circuit and can be used as a support member.
  • the demagnetization device of the pipeline based on the permanent magnet structure
  • the device is an external structure
  • the permanent magnets are axially magnetized for demagnetization of the extruded tubular member
  • the pipe member passes through the interior of the demagnetization device and undergoes an alternating attenuation magnetic field. Process to achieve demagnetization.
  • the extruded tube product is in the process of extrusion molding, due to the magnetization of the oriented magnetic field, so the tube The finished product will be in a magnetic state.
  • An external demagnetization device can be placed at the end of the extrusion forming apparatus or at the exit of the forming mold. Demagnetization can be achieved by passing the finished tube through the demagnetization device.
  • the extruded tubular member is magnetized by an orientation magnetic field during extrusion, and the pipe demagnetization device is disposed at the rear of the orientation magnetic field.
  • the strength of the magnetic field formed by the permanent magnets disposed at the foremost end of the demagnetization device is greater than the coercive force of the shaped tubular member.
  • the permanent magnets are axially magnetized and the polarity directions are alternately replaced.
  • the set of magnets may be of the same size, with a progressively lower performance of the magnets; or may be of the same performance, with a size ranging from large to small; or a combination of size and shape to construct a set of alternating decaying magnetic fields.
  • a pole piece is placed in the middle of the magnet, and the pole piece may be a magnetizer to extract more magnetic lines of force; or a non-magnetic field, which is also a means of constituting a specific magnetic field strength.
  • Part of the pole piece can be replaced by a ferromagnetic magnet, and the polarity is alternately placed in order to extract more magnetic lines of force and form a stronger magnetic field waveform.
  • Magnetic materials are classified into soft magnetic materials, hard magnetic materials, semi-hard magnetic materials, etc., but regardless of the magnetic materials, they all have their own B-H hysteresis loops.
  • H is the applied magnetic field strength and B is the magnetic induction of the material.
  • the trajectory of the hysteresis loop becomes smaller and smaller; when the amplitude of the alternating decay magnetic field gradually decreases to zero, the pipeline The residual remanence Br can be close to zero.
  • alternating decay magnetic field when a set of magnetic fields with alternating polarity and large to small intensity, abbreviated as alternating decay magnetic field, is applied to the workpiece, the workpiece can be effectively demagnetized, and the effect of demagnetization depends on the set of alternating
  • the initial strength of the decaying magnetic field and the magnitude of the gradual attenuation mainly include the following two aspects:
  • the initial strength of the alternating decay magnetic field greater than the intrinsic coercivity of the workpiece material, the reverse magnetization can be achieved, and demagnetization can be achieved.
  • the attenuation of the alternating decay magnetic field should not be too large.
  • the demagnetizing field of the previous waveform will form a new intrinsic coercive force parameter Hci'.
  • the demagnetizing field amplitude of the latter waveform needs to be greater than this Hci' value to achieve reverse magnetization of the workpiece and reduce the residual magnetization. If the attenuation amplitude is too large and the subsequent waveform is not sufficient to reverse the magnetization direction, then the demagnetization is unclean.
  • the demagnetization method described in the present invention is an innovative application based on this basic principle.
  • the demagnetization method is based on a permanent magnet structure, and a set of stable alternating decay magnetic fields are spatially constructed.
  • the group can attenuate the magnetic field to achieve the purpose of demagnetization.
  • the horizontal axis is the spatial distance
  • the vertical axis is the magnetic field strength.
  • the curve is the magnetic field strength that forms the alternating attenuation as the spatial displacement changes, as shown in Figures 2 and 4. This method is especially suitable for online demagnetization of existing network pipes.
  • the present invention creatively proposes a pipe demagnetization device based on a permanent magnet structure.
  • This is a magnetic field that constructs the alternating attenuation attenuation in space.
  • the workpiece is passed through the alternating decay attenuation magnetic field to complete the demagnetization.
  • the invention is based on a permanent magnet structure and does not require a power source, and provides two demagnetization devices, a built-in type and an external type, which can easily achieve the purpose of demagnetization of the entire pipe or pipe.
  • the overall demagnetization of the natural gas pipeline after the completion of the test is of great significance.
  • the pipeline inspection equipment and service industry has not proposed such a technology, and the method of temporary demagnetization during pipeline maintenance is generally adopted.
  • the demagnetization section proposed by the present invention at the end of the pipeline magnetic flux leakage detecting device, the purpose of magnetic flux leakage detection + pipeline demagnetization can be achieved at the same time, which greatly facilitates the maintenance and repair of the pipeline in the later stage.
  • the present invention can be disposed at the end of the pipe production equipment, and the pipe member can directly pass through the demagnetization device after extrusion molding. To achieve the purpose of demagnetization. Since the production of anisotropic bonded NdFeB pipe products using an oriented magnetic field is in the stage of research and development, this demagnetization method has not been proposed in the industry, and the present invention is also innovatively proposed for the first time.
  • Embodiment 1 is a schematic structural view of the present invention in Embodiment 1;
  • Embodiment 2 is a magnetic induction intensity diagram formed by the present invention in Embodiment 1;
  • Figure 3 is a schematic view showing the structure of the present invention in Embodiment 2;
  • Figure 4 is a magnetic induction intensity diagram of the formation of the present invention in Example 2.
  • Figure 5 is a schematic view showing the application of the present invention in Embodiment 3.
  • Figure 6 is a schematic view showing the application of the present invention in Embodiment 4.
  • Figure 7 is a schematic view showing the application of the present invention in Embodiment 5.
  • Figure 8 is a schematic view showing the application of the present invention in Embodiment 6;
  • Figure 9 is a schematic view showing the structure of the present invention used in Example 7.
  • Figure 10 is a schematic view showing the structure of the present invention and a magnetic induction intensity map formed therein;
  • Figure 11 is a schematic view showing the structure of the present invention and a magnetic induction intensity diagram formed in the eighth embodiment.
  • 0-pipe demagnetization device 1-iron core, 2- permanent magnet, 3-support, 4-pipe, 5-magnetic pig, 6-magnetic flux detector, 7-anisotropic bond Iron boron magnetic powder, 8-heating system, 9-oriented magnetic field, 10-forming mold, 11-tube finished product, 12-axial magnetizing magnet, 13-pole piece, 14-shell, 15-radial magnetizing magnet.
  • a pipe demagnetization device 0 based on a permanent magnet structure, the structure of which is shown in FIG. 1, is composed of an iron core 1 and a permanent magnet 2 distributed on the iron core 1.
  • the iron core 1 may be a magnetically permeable material to constitute a magnetic circuit; or may be a partially non-magnetically permeable material.
  • the materials selected are mainly for the purpose of forming a suitable magnetic circuit.
  • the permanent magnet 2 used is a single ring magnet, which is a toroidal magnetized ring magnet, which may be a magnetic ring of the entire radial magnetization, or a plurality of The magnetic steel is spliced together.
  • the single ring magnets are placed along the axial direction of the center piece, and the magnetization directions are alternately reversed one by one.
  • the magnetization performance of the single ring magnet disposed along the axial direction of the center piece is gradually reduced, and the diameter or thickness of the magnet is gradually reduced to achieve the axial direction.
  • the gradually attenuating alternating magnetic field, the magnetic field intensity attenuation amplitude is 1-99%, and the attenuation intensity is 20% in this embodiment, and the change of the magnetic induction intensity formed is as shown in FIG. 2, and the AE in FIG. 1 and FIG. 2 respectively Corresponding position and magnetic field strength at that position.
  • a support member 3 for holding it in the center of the pipe is also provided on the pipe demagnetization device 0, and is fixed to the core 1.
  • the support member 3 may be a magnetic conductive material, such as a magnetic conductive steel brush, which may also serve as a part of the magnetic circuit as a support member, or may be a non-magnetic conductive material such as a non-magnetic stainless steel brush, polyurethane, roller or A cup or the like is only used as a support member; a support structure may not be required locally.
  • the materials selected are mainly for forming a suitable magnetic circuit and can be used as a support member.
  • the series structure in which the permanent magnet 2 used in the embodiment is a double ring magnet constitutes a series group of two ring magnets having opposite radial magnetization and opposite magnetization directions.
  • Each set of double ring magnets is composed of two ring magnets with opposite radial magnetization and opposite magnetization directions.
  • the radial ring magnets may be formed by splicing a plurality of magnetic steels or an entire magnetized magnetic ring.
  • Each set of double ring magnets forms a polarity in one direction in the tube wall.
  • a plurality of sets of ring magnets are axially spaced apart, and the magnetization directions formed in the tube walls are alternately reversed one by one, forming alternating magnetic fields of alternating polarity in the tube walls.
  • the performance of each set of magnetic rings is reduced one by one, or the size of the magnetic ring diameter/thickness is gradually changed to realize an alternating magnetic field which is gradually attenuated in the axial direction, and the series structure composed of the double annular magnets is placed along the axial interval of the center piece.
  • the magnetization direction between the two ring magnets in the series structure is opposite.
  • the magnetization directions between the adjacent ring magnets are the same, and the magnetic properties and dimensions of the two ring magnets forming the series structure are the same.
  • the magnetic properties of each series structure are gradually reduced.
  • the diameter or thickness of the magnet may gradually decrease, and the magnetic field strength formed in the tube wall is attenuated by 1-99%, and the attenuation amplitude is 35% in this embodiment.
  • the advantage of the double-ring magnets being connected in series is that the magnetic field strength of each waveform can be adjusted step by step to achieve precise demagnetization control, and the magnetic induction intensity formed is as shown in FIG. 4, and the ACs in FIG. 3 and FIG. 4 respectively correspond to the positions and The magnetic field strength at this location.
  • a pipe demagnetization device 0 based on a permanent magnet structure, which is a built-in structure for demagnetizing a long pipe, and is subjected to pressure traction in the pipe to cause the magnetized pipe to undergo an alternating attenuation magnetic field to realize demagnetization.
  • the magnetic cleaner 5 moves forward along the pipeline under the pressure of the pipeline.
  • a strong magnet is installed on the magnetic pig 5, and the tube wall is saturated and magnetized wherever the device is located, so that the entire long-distance pipeline is severely magnetized.
  • the pipe demagnetization device 0 has a built-in structure.
  • the demagnetization device may be a separate device, which is pulled by pressure in the tube, so that each pipe undergoes a process of alternating attenuating magnetic field, thereby realizing demagnetization; or as an accessory device, being dragged to the magnetic pig 5
  • the rear end as shown in Fig. 5, is used to complete the pipe demagnetization operation at the same time as the conventional pigging or magnetic flux leakage detecting operation. It should be noted that the strength of the magnetic field formed by the permanent magnets disposed at the foremost end of the demagnetization device is greater than the coercive force of the pipeline.
  • the rear end of the magnetic detector 6 is as shown in FIG.
  • a plurality of pipe demagnetization devices 0 are provided to be connected in series with each other. Perform demagnetization processing.
  • the strength of the magnetic field formed in the pipe wall gradually decreases from front to back.
  • the number and attenuation degree of the alternating magnetic field waveforms required are also different. When the number of waveforms required is large and a demagnetization section is not enough to implement these waveforms, it can be done in series by several demagnetization sections.
  • the application of the pipe demagnetization device based on the permanent magnet structure is an external structure.
  • the anisotropic bonded NdFeB magnetic powder 7 is heated and extruded through a screw and a heating system 8, and is disposed at the end.
  • the molding die 10 is molded, and an orientation magnetic field 9 is disposed in the molding die.
  • the finished tubular product is magnetized by the orientation magnetic field, so that the finished pipe product is in a magnetic state.
  • an external pipe demagnetizing device 0 can be placed at the end of the extrusion forming apparatus, or at the exit of the forming die. Demagnetization can be achieved by passing the tube finished product 11 through the demagnetization device.
  • the structure of the demagnetization device used in this embodiment is as shown in Fig. 10.
  • Each of the permanent magnets is an axial magnetization magnet 12, and the polarity directions are alternately replaced.
  • the permanent magnets may be of the same size and the properties of the magnets are gradually lowered for arrangement; or they may have the same performance, the size is arranged from large to small; or a combination of size and shape, constructing a set of alternating decay magnetic fields for extruding the pipe fittings Demagnetization, the tube passes through the process of undergoing alternating decay of the magnetic field from the center of the demagnetization device to achieve demagnetization.
  • a pole piece 13 is placed in the middle of the magnet, and the pole piece 13 may be a magnetizer to extract more magnetic lines of force; or a non-magnetic field, which is also a means for forming a specific magnetic field strength, and the magnetic induction intensity formed is as shown in FIG.
  • the strength of the magnetic field formed by the permanent magnet at the foremost end of the demagnetization device is greater than the coercive force of the shaped tubular member.
  • the application of the pipe demagnetization device based on the permanent magnet structure is an external structure, and its use is substantially the same as that of the seventh embodiment.
  • the structure of the pipe demagnetization device is also substantially the same as that of the embodiment 7, except that in this embodiment,
  • the partial pole piece 13 can be replaced by a radial magnetizing magnet 15, and also needs to be alternately placed in polarity, as shown in Fig. 11, in order to extract more magnetic lines of force, form a stronger magnetic field waveform, and form a magnetic induction intensity. As shown in Figure 11.
  • a pipe demagnetization device based on a permanent magnet structure comprising a center piece and a permanent magnet distributed on the center piece, and forming a magnetic field alternating in a direction from the front to the rear axial direction in the pipe wall of the pipe, the magnetic field The intensity gradually decreases.
  • the permanent magnet used in this embodiment is a radially magnetized ring magnet which is a magnetic ring that is magnetized in the entire radial direction.
  • Each of the ring magnets is axially spaced along the center piece, and the magnetization directions are alternately reversed one by one, and the size of the single ring magnet disposed along the axial direction of the center piece is gradually reduced, for example, the diameter or thickness of the magnet is gradually reduced, and the magnetic properties are gradually reduced.
  • Decrease the strength of the magnetic field formed by the magnet in the pipe is gradually attenuated and attenuated.
  • the amplitude is 10%, and the strength of the magnetic field formed by the permanent magnet disposed at the foremost end of the demagnetization device is greater than the coercive force of the pipe.
  • the central member used is a magnetic conductive member or a non-magnetic conductive member, including a solid or hollow iron core, an aluminum core or a copper core, a stainless steel core, and may be a magnetic conductive material for forming a magnetic circuit; or may be partially non-magnetically conductive. material.
  • the materials selected are mainly for the purpose of forming a suitable magnetic circuit.
  • a solid copper core is used.
  • the device can adopt a built-in structure for demagnetizing the inside of the long pipe, and is subjected to pressure traction in the pipe to cause the magnetized pipe to undergo an alternating decaying magnetic field to realize demagnetization.
  • the magnetic pig or magnetic flux leakage detector moves forward along the pipeline under the pressure of the pipeline. Strong magnets are installed on the magnetic pig or magnetic flux leakage detector. The tube is saturated and magnetized wherever the equipment is located, so that the entire long-distance pipeline is severely magnetized.
  • the demagnetization device has a built-in structure.
  • the demagnetization device may be a separate device, which is pulled by pressure in the tube, so that each pipe undergoes a process of alternating attenuating magnetic field, thereby realizing demagnetization; the demagnetization device can also be used as an attachment device to be hung on the magnetic pig Or the back end of the magnetic flux leakage detector, so that the pipe demagnetization operation is completed at the same time as the conventional pigging or magnetic flux leakage detecting operation.
  • the support member may be a magnetic conductive material, such as a magnetic conductive steel brush, which may also serve as a part of the magnetic circuit as a support member, or may be a non-magnetic conductive material such as a non-magnetic stainless steel brush, polyurethane, roller or leather.
  • the bowl or the like is only used as a support member; the support structure may not be required locally.
  • the materials selected are mainly for forming a suitable magnetic circuit and can be used as a support member.
  • the support member used in this embodiment is a roller.
  • a pipe demagnetization device based on a permanent magnet structure the structure of which is substantially the same as that of the embodiment 9, except that the permanent magnet used in the embodiment is a radial magnetized ring magnet formed by splicing a plurality of magnetic steels.
  • the magnetic field strength formed by the magnet in the pipe is attenuated by 20%.
  • the center piece used is a hollow aluminum core, and the support member used is a cup.
  • a pipe demagnetization device based on a permanent magnet structure the structure of which is substantially the same as that of Embodiment 9, except that the permanent magnet used in the embodiment is a series structure composed of double ring magnets for two radial magnetization and magnetization
  • the ring magnets of opposite directions form a series group.
  • the ring magnet is a magnetic ring that is magnetized throughout the radial direction.
  • the magnetic field strength of each waveform can be adjusted step by step to achieve precise demagnetization control.
  • the magnetization directions between the adjacent ring magnets are the same, and the magnetic properties and dimensions of the two ring magnets constituting the series structure are the same, and the magnetic properties of the series structures are gradually reduced, for example, may be magnets.
  • the diameter or thickness is gradually reduced, and the strength of the magnetic field formed in the tube wall is attenuated by 5%.
  • the support member may not be used.
  • a pipe demagnetization device based on a permanent magnet structure is substantially the same as that of the embodiment 11, except that the ring magnet in the embodiment is formed by splicing a plurality of magnetic steels with a attenuation amplitude of 60%.
  • an external structure is adopted, so that a support member is not required.
  • Each of the permanent magnets is axially magnetized for demagnetization of the extruded tubular member, and the tubular member passes through the process of undergoing alternating decay of the magnetic field from the inside of the demagnetization device to achieve demagnetization.
  • the finished tube product is magnetized by the orientation magnetic field, so the finished tube product will be in a magnetic state.
  • An external demagnetization device can be placed at the end of the extrusion forming apparatus or at the exit of the forming mold. Demagnetization can be achieved by passing the finished tube through the demagnetization device.
  • the extruded tubular member is magnetized by an orientation magnetic field during extrusion, and the pipe demagnetization device is disposed at the rear of the oriented magnetic field.
  • the strength of the magnetic field formed by the permanent magnets disposed at the foremost end of the demagnetization device is greater than the coercive force of the shaped tubular member.
  • a pole piece is further disposed between the ring magnets. The pole piece used is a magnetically permeable material.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Investigating Or Analyzing Materials By The Use Of Magnetic Means (AREA)
  • Water Treatment By Electricity Or Magnetism (AREA)

Abstract

一种基于永磁结构的管道退磁装置（0）及其应用，由中心件及分布在中心件上的永磁体（2）组成，在管道（4）管壁内由前至后的轴向方向上形成方向交替变化的磁场，磁场强度逐渐减小，该装置（0）可以采用内置式结构或外置式结构应用于管道（4）退磁。该管道退磁装置（0）在空间上构造出一组稳定的交变衰减磁场，当已被磁化的管道（4）与这组交变衰减磁场在空间上产生相对位移，使管道（4）的管壁经历这组交变衰减磁场，即可实现退磁的目的。

Description

一种基于永磁结构的管道退磁装置及其应用 技术领域
本发明涉及一种退磁装置，尤其是涉及一种基于永磁结构的管道退磁装置及其应用。
背景技术
随着石油、天然气等能源和化工工业的发展，输送管道随之在全世界进行了广泛的部署，各种口径的管道总长度难以计数。这些管道受到输送对象和周围环境的作用、或战争等人为因素的破坏，发生了腐蚀减薄、穿孔断裂等情况，造成了泄漏甚至爆炸。
管道内检测技术可在不影响管道正常运营的情况下，在管道内投运带有检测装置的设备，有效检测出管道内的变形、腐蚀等金属缺陷，并进行准确定位，为管道安全运营提供科学的维护依据。管道漏磁检测(MFL:Magnetic Flux Leakage)就是一种行之有效的内检测技术，可以有效对不同口径的天然气、石油等管道进行健康状态检查。
当管道漏磁检测设备被投放到管道内部，设备在管道内压力的作用下沿管线运动。检测设备自身携带有一段磁性节，磁性节可以将所经过的管壁饱和磁化，并与管壁形成磁回路。如果管壁上有缺陷，管壁内的磁力线将围着缺陷重新分布，有一部分磁力线泄漏出来进入到周围介质。泄漏的磁场被位于磁极之间、紧贴管壁周向密布放置的霍尔探头检测，这些信号经过滤波、放大、转换处理后被记录到存储器中，检测结束后经数据分析系统处理，对其进行判断识别，以此来检测管道的腐蚀状态。
管道漏磁检测技术会产生一个新的问题：油气管道在检测时被饱和磁化，并且剩磁残留在管道基体内且未被消除。采用不同工艺、不同牌号材料生产的管道，会有不同的磁性能特性参数，其残留的剩磁大小也不同。
在管道内残留磁性有几个问题：
1)残留磁性的管道，对后续漏磁检测的精度会造成影响。
2)对管道维修电焊产生不利影响。管道维修往往需要采用电焊工艺，但是 对有残余磁性的管道进行电焊，会产生偏弧、飞弧，极大地影响焊接质量。
那么如何给管道退磁，就衍生出了一个新的技术专题。
为了消除这种残余磁性对后期维修焊接的影响，人们在管道切开后只能采用局部退磁的方法。例如，在焊接部位缠绕电缆，用通电电缆产生的磁场来对消原有的残余磁性。但由于管道已经在全线被饱和磁化，即使采用了缠绕法局部退磁，远处的磁性会不断传递过来，难以取得理想的效果。而且管道的牌号各不相同，其残余磁性各不相同，对于磁化较严重的场合，切缝中的磁场强度甚至达到2000Gs以上，更增加了退磁的难度，无法形成有效的标准作业。美国石油协会(API)，对经过电磁检测后油管中的剩磁做了说明和规定，建议检测后的管道剩磁应小于30Gs。
目前，常规退磁方法有高温退磁、线圈退磁、搭铁退磁等几种方法。高温退磁需要将铁磁工件加热到居里点以上，在没有外界磁场的环境下冷却即可退磁。但是由于工程实施、成本等原因，限制了其在工程实际中的应用。线圈退磁通过在管道上缠绕线圈，施加交流电来进行退磁。搭铁退磁是在管道接缝处放置导磁材料，由于导磁材料相当于提供了短路通道，使磁力线尽可能多的穿入导磁材料，而减小了焊接处的磁场强度，以此来实现焊接的目的。这种方法俗称搭铁法。然而，上述方法无法实现将整根管道进行退磁，它们都是在管道维修时临时进行的局部退磁处理，这样既影响工程维修进度，又影响工程实施质量。因此，市场急需解决管道在线退磁的方法，在管道检测完成后就实现退磁的目的，并亟待产生新技术、新设备。
中国专利CN102866367A公开了一种退磁检测装置及其退磁检测方法。退磁检测装置用于电性连接至待测永磁式电动机的功率控制单元中，而功率控制单元电性连接至直流电源。退磁检测装置感测直流电源的待测电压值及待测电流值，并根据待测电压值以及待测电流值计算直流电源的待测功率值。退磁检测装置判断待测功率值与标准功率值的差异，并根据差异判断待测永磁式电机呈现退磁状态。但是该装置采用的是电磁铁进行退磁，在长输管道中无法应用。
发明内容
本发明的目的就是为了克服上述现有技术存在的缺陷，而提供一种空间上 实现交变衰减磁场的基于永磁结构的管道退磁装置。
本发明的目的可以通过以下技术方案来实现：
一种基于永磁结构的管道退磁装置，由中心件及分布在中心件上的永磁体组成，在管道管壁内由前至后的轴向方向上形成方向交替变化的磁场，磁场强度逐渐减小。
所述的永磁体为单环形磁体或双环形磁体组成的串联结构。
所述的单环形磁体为辐向磁化的环形磁体，该环形磁体为整个辐向磁化的磁环或者由多个磁钢拼接而成。
各单环形磁体沿中心件的轴向间隔放置，磁化方向逐个交替反向，沿中心件轴向设置的单环形磁体的尺寸逐渐减小，例如可以是磁体的直径或厚度逐渐减小，磁性能逐渐降低，磁体在管道内形成的磁场强度逐渐衰减，衰减幅度为1-99％。
作为优选的实施方式，衰减幅度为10-50％来实现沿轴向逐步衰减的交变磁场。
所述的双环形磁体组成的串联结构为两个辐向磁化、充磁方向相反的环形磁体构成串联组。
所述的环形磁体为整个辐向磁化的磁环或者由多个磁钢拼接而成，双环形磁体成组串联的优点在于：可以逐级调整每个波形的磁场强度，实现精准退磁控制。
各双环形磁体组成的串联结构沿中心件的轴向间隔放置，串联结构内的两个环形磁体之间的磁化方向相反，相邻的两个串联结构中，邻侧的环形磁体之间的磁化方向相同，构成串联结构的两个环形磁体的磁性能和尺寸相同，各串联结构的磁性能逐渐降低，例如可以是磁体的直径或厚度逐渐减小，在管壁内形成的磁场强度衰减幅度1-99％。
作为优选的实施方式，衰减幅度为10-50％，来实现沿轴向逐步衰减的交变磁场。
所述的中心件为导磁构件或不导磁构件，包括实心或空心的铁芯、铝芯或铜芯、不锈钢芯，可以是导磁材料，用以构成磁路；也可以是部分非导磁材料。选用的材料主要以形成合适的磁路为目的。基于永磁结构的管道退磁装置的应 用，该装置为内置式结构，用于长管道内部退磁，在管道内被压力牵引前进使磁化的管道经历交变衰减磁场的过程，实现退磁。
在对天然气石油长输管道进行磁力清管作业或漏磁检测作业时，磁力清管器或漏磁检测器在管内压力的作用下，设备会沿管道向前运动。磁力清管器或漏磁检测器上安装有强磁体，设备所到之处都会使管壁饱和磁化，从而整条长输管道都被严重磁化。
对于天然气石油长输管道，退磁装置采用内置式的结构。退磁装置可以是单独一套装置，在管内被压力牵引前进，使每处管道都经历交变衰减磁场的过程，以此来实现退磁；退磁装置也可以作为附属装置，拖挂于磁力清管器或漏磁检测器的后端，这样在进行传统清管或漏磁检测作业的同时，一并完成管道退磁作业。
该装置设有一个或多个，直接设置在管道内或连接在磁力清管器或漏磁检测器的后端。设置在退磁装置最前端的永磁体所构成的磁场的强度大于管道的矫顽力。
设置多个退磁装置时，管壁内形成的磁场强度由前至后逐渐减小，对于不同管道壁厚、不同材质的管道情况，所需的交变磁场波形数量和衰减程度也不相同。当所需的波形数较多，一个退磁节不够实现这些波形的话，可以由几个退磁节串联完成。理论上讲，交变磁场波形数越多、衰减幅度越小，则退磁效果越好。实际在设计中，需要考虑制造成本和工程上的可行性，选择合适的波形数量、衰减幅度。
该管道退磁装置还设有将其保持在管道中心的支撑件，固定在中心件上。支撑件可以是导磁材料，如：导磁钢刷，在作为支撑件的同时，还可以作为磁路的一部分；也可以是非导磁材料，如：非导磁不锈钢刷、聚氨酯、滚轮或皮碗等，仅作为支撑件；局部也可以不需要支撑结构。选用的材料主要以形成合适的磁路、并可作为支撑件为目的。
基于永磁结构的管道退磁装置的应用，该装置为外置式结构，各永磁体为轴向充磁，用于挤出成型管件的退磁，管件从该退磁装置内部穿过经历交变衰减磁场的过程，实现退磁。
挤出成形的管件成品在挤出成形的过程中，因受取向磁场的磁化，所以管 件成品会是着磁状态。在挤出成形设备的末端，或者在成形模具的出口处，可以放置外置式的退磁装置。只要使管件成品通过退磁装置，即可实现退磁。
所述的挤出成型管件在挤出过程中通过取向磁场被磁化，所述的管道退磁装置设置在取向磁场的后部。
设置在退磁装置最前端的永磁体所构成的磁场的强度大于成型管件的矫顽力。永磁体轴向充磁，并且极性方向交替更换。这组磁体可以是尺寸相同、磁体性能逐渐降低来进行布置；也可以是性能相同，尺寸由大到小布置；或者尺寸和形状的组合，构造出一组交变衰减磁场。在磁体的中间放置极片，极片可以是导磁体从而引出更多的磁力线；也可以是非导磁体，同样是构成特定磁场强度的手段。
部分极片可以用辐向充磁的磁体代替，并且也需要极性交替放置，目的是为了引出更多的磁力线，形成更强的磁场波形。
磁性材料分为软磁材料、硬磁材料、半硬磁材料等，但无论何种磁性材料，他们都有各自的B-H磁滞回线。H为施加的磁场强度，B为材料的磁感应强度。
对已被磁化的材料施加反向磁场，可以对材料起到退磁的作用，分如下几种情况：
当施加的反向磁场强度低于內禀矫顽力Hci时，则当施加的磁场撤销时，材料原先的剩磁会减小，但磁化方向不改变。
当施加的反向磁场强度等于內禀矫顽力Hci时，则当施加的磁场撤销时，材料原先的剩磁就会消失为零。
当施加的反向磁场强度略大于內禀矫顽力Hci时，则当施加的磁场撤销时，材料原先剩磁的磁化方向会反向，并且剩磁大小会有所减小。
当施加的反向磁场强度远大于內禀矫顽力Hci时，则当施加的磁场撤销时，材料会被完全反向饱和磁化。
根据磁性材料的B-H磁滞回线可以知道，当工件置于交变衰减的磁场中，磁滞回线的轨迹会越来越小；当交变衰减磁场的幅度逐步降为零时，管道中残留的剩磁Br即可接近于零。
正是利用这种原理，当对工件施加一组极性交替、强度由大到小的磁场，简称交变衰减磁场，则可以对工件进行有效退磁，退磁的效果取决于这组交变 衰减磁场的初始强度和逐步衰减量的大小，主要包括以下两个方面：
交变衰减磁场的初始强度：要大于工件材料的內禀矫顽力，才可以实现反向磁化，进而实现退磁。
交变衰减磁场的衰减量：衰减幅度不能过大。前一个波形的退磁场会对材料形成新的內禀矫顽力参数Hci’，后一个波形的退磁场幅度需要大于这个Hci’值，才能对工件实现反向磁化，同时降低了剩磁强度。如果衰减幅度过大，后续波形不足以将磁化方向反向的话，那么会产生退磁不干净的现象。
本发明所述的退磁方法，就是基于这个基本原理的创新性的应用。这种退磁方法基于永磁结构，在空间上构造出一组稳定的交变衰减磁场，当已被磁化的管道与这组交变衰减磁场在空间上产生相对位移，使管道的管壁经历这组交变衰减磁场，即可实现退磁的目的。若要在坐标图中说明这个磁场的特点，那么横轴是空间距离，纵轴是磁场强度，曲线就是随空间位移的改变形成交变衰减的磁场强度，如图2、4中所示。这种方法特别适用于对现网管道进行在线退磁。
与现有技术相比，本发明创造性的提出了一种基于永磁结构的管道退磁装置。这是一种在空间上构造交变衰减衰减的磁场，当工件和交变衰减衰减磁场产生相对位移，使工件穿过交变衰减衰减的磁场，即可完成退磁。区别于传统缠绕线圈+电源提供电流的局部退磁方法，本发明基于永磁结构而且不需要电源，提供了内置式和外置式两种退磁装置，可以轻松实现整根管道或管件的退磁目的。
对天然气石油管道在检测完成后进行整体退磁，其意义重大。目前管道检测设备和服务行业还没有提出这样的技术，普遍采用管道维修时临时退磁的办法。通过在管道漏磁检测装置末端配置本发明提出的退磁节，可以实现漏磁检测+管道退磁同时完成的目的，对后期管道维护和抢修带来极大便利。
对各向异性粘结钕铁硼管件产品的挤出工艺，由于施加的取向磁场会使产品着磁，本发明可配置在管件生产设备的末端，管件在挤出成形之后可直接穿过退磁装置，实现退磁的目的。由于采用取向磁场生产各向异性粘结钕铁硼制造管件产品正处于研发试制阶段，这种退磁方法在行业内还没有被提出过，本发明同样是创新性的首次提出。
附图说明
图1为实施例1中本发明的结构示意图；
图2为实施例1中本发明形成的磁感应强度图；
图3为实施例2中本发明的结构示意图；
图4为实施例2中本发明的形成的磁感应强度图；
图5为实施例3中本发明应用的示意图；
图6为实施例4中本发明应用的示意图；
图7为实施例5中本发明应用的示意图；
图8为实施例6中本发明应用的示意图；
图9为实施例7中使用的本发明的结构示意图；
图10为实施例7中本发明的结构示意图及形成的磁感应强度图；
图11为实施例8中本发明的结构示意图及形成的磁感应强度图。
图中，0-管道退磁装置、1-铁芯、2-永磁体、3-支撑件、4-管道、5-磁力清管器、6-漏磁检测器、7-各向异性粘结钕铁硼磁粉、8-加热系统、9-取向磁场、10-成型模具、11-管件成品、12-轴向充磁磁体、13-极片、14-外壳、15-辐向充磁磁体。
具体实施方式
下面结合具体实施例对本发明进行详细说明。以下实施例将有助于本领域的技术人员进一步理解本发明，但不以任何形式限制本发明。应当指出的是，对本领域的普通技术人员来说，在不脱离本发明构思的前提下，还可以做出若干变形和改进。这些都属于本发明的保护范围。
实施例1
一种基于永磁结构的管道退磁装置0，其结构如图1所示，由铁芯1及分布在铁芯1上的永磁体2组成。
铁芯1可以是导磁材料，用以构成磁路；也可以是部分非导磁材料。选用的材料主要以形成合适的磁路为目的。使用的永磁体2为单环形磁体，采用的是辐向磁化的环形磁体，该环形磁体可以为整个辐向磁化的磁环，或者由多个 磁钢拼接而成。各单环形磁体沿中心件的轴向间隔放置，磁化方向逐个交替反向，沿中心件轴向设置的单环形磁体的磁化性能逐渐降低，磁体的直径或厚度逐渐减小，来实现沿轴向逐步衰减的交变磁场，磁场强度衰减幅度1-99％，本实施例中衰减强度为20％，其形成的磁感强度的变化如图2中所示，图1和图2中的A-E分别对应位置以及该位置的磁场强度。
另外，为了方便该管道退磁装置0在管道4中的使用，在该管道退磁装置0上还设有将其保持在管道中心的支撑件3，固定在铁芯1上。支撑件3可以是导磁材料，如：导磁钢刷，在作为支撑件的同时，还可以作为磁路的一部分；也可以是非导磁材料，如：非导磁不锈钢刷、聚氨酯、滚轮或皮碗等，仅作为支撑件；局部也可以不需要支撑结构。选用的材料主要以形成合适的磁路、并可作为支撑件为目的。
实施例2
一种基于永磁结构的管道退磁装置0，其结构如图3所示，由铁芯1及分布在铁芯1上的永磁体2组成，与实施例1大致相同，不同之处在于，本实施例中采用的永磁体2为双环形磁体组成的串联结构为两个辐向磁化、充磁方向相反的环形磁体构成串联组。每组双环形磁体为两个辐向磁化、充磁方向相反的环形磁体构成一组，辐向环形磁体可以由多个磁钢拼接而成，也可以是一整个辐向磁化的磁环。每组双环形磁体在管壁内形成某一个方向的极性。多组环形磁体沿轴向间隔放置，在管壁内形成的磁化方向成组逐个交替反向，在管壁内形成极性交替变化的磁场。同时，每组磁环的性能逐个降低，或者磁环直径/厚度等尺寸逐渐改变，来实现沿轴向逐步衰减的交变磁场，各双环形磁体组成的串联结构沿中心件的轴向间隔放置，串联结构内的两个环形磁体之间的磁化方向相反，相邻的两个串联结构中，邻侧的环形磁体之间的磁化方向相同，构成串联结构的两个环形磁体的磁性能和尺寸相同，各串联结构的磁性能逐渐降低，例如可以是磁体的直径或厚度逐渐减小，在管壁内形成的磁场强度衰减幅度1-99％，本实施例中衰减幅度为35％。双环形磁体成组串联的优点在于：可以逐级调整每个波形的磁场强度，实现精准退磁控制，其形成的磁感强度如图4所示，图3和图4中的A-C分别对应位置以及该位置的磁场强度。
实施例3
一种基于永磁结构的管道退磁装置0，该装置为内置式结构，用于长管道内部退磁，在管道内被压力牵引前进使磁化的管道经历交变衰减磁场的过程，实现退磁。
在对天然气石油长输管道进行磁力清管作业或漏磁检测作业时，磁力清管器5在管内压力的作用下，设备会沿管道向前运动。在磁力清管器5上会安装强磁体，设备所到之处都会使管壁饱和磁化，从而整条长输管道都被严重磁化。
对于天然气石油长输管道，管道退磁装置0采用内置式的结构。退磁装置可以是单独一套装置，在管内被压力牵引前进，使每处管道都经历交变衰减磁场的过程，以此来实现退磁；也可以作为附属装置，拖挂于磁力清管器5的后端，如图5所示，这样在进行传统清管或漏磁检测作业的同时，一并完成管道退磁作业。需要注意的是，设置在退磁装置最前端的永磁体所构成的磁场的强度大于管道的矫顽力。
实施例4
一种基于永磁结构的管道退磁装置0，该装置为内置式结构，用于长管道内部退磁，与实施例3大致相同，不同之处在于，本实施例中管道退磁装置0连接在或漏磁检测器6的后端，如图6所示。
实施例5
一种基于永磁结构的管道退磁装置0，该装置为内置式结构，用于长管道内部退磁，如图7所示，在本实施例中，设置有一个管道退磁装置0进行退磁处理。
实施例6
一种基于永磁结构的管道退磁装置0，该装置为内置式结构，用于长管道内部退磁，如图8所示，在本实施例中，设置有多个管道退磁装置0来相互串联从而进行退磁处理。设置多个退磁装置时，管壁内形成的磁场强度由前至后逐渐减小，对于不同管道壁厚、不同材质的管道情况，所需的交变磁场波形数量和衰减程度也不相同。当所需的波形数较多，一个退磁节不够实现这些波形的话，可以由几个退磁节串联完成。理论上讲，交变磁场波形数越多、衰减幅度越小，则退磁效果越好。实际在设计中，需要考虑制造成本和工程上的可行性，选择合适的波形数量、衰减幅度。
实施例7
基于永磁结构的管道退磁装置的应用，该装置为外置式结构，如图9所示，各向异性粘结钕铁硼磁粉7经过螺杆以及加热系统8进行加热挤出成型，在末端设置有成型模具10，并且在成型模具内设置有取向磁场9，挤出成形的管件成品在挤出成形的过程中，因受取向磁场的磁化，所以管件成品会是着磁状态。在挤出成形设备的末端，或者在成形模具的出口处，可以放置外置式的管道退磁装置0。只要使管件成品11通过退磁装置，即可实现退磁。
本实施例中使用的退磁装置的结构如图10所示，各永磁体为轴向充磁磁体12，并且极性方向交替更换。永磁体可以是尺寸相同、磁体性能逐渐降低来进行布置；也可以是性能相同，尺寸由大到小布置；或者尺寸和形状的组合，构造出一组交变衰减磁场，用于挤出成型管件的退磁，管件从该退磁装置中心穿过经历交变衰减磁场的过程，实现退磁。在磁体的中间放置极片13，极片13可以是导磁体从而引出更多的磁力线；也可以是非导磁体，同样是构成特定磁场强度的手段，形成的磁感强度如图10所示，设置在退磁装置最前端的永磁体所构成的磁场的强度大于成型管件的矫顽力。
实施例8
基于永磁结构的管道退磁装置的应用，该装置为外置式结构，其使用情况与实施例7大致相同，管道退磁装置的结构与实施例7也大致相同，不同之处在于，本实施例中的部分极片13可以用辐向充磁磁体15代替，并且也需要极性交替放置，如图11所示，目的是为了引出更多的磁力线，形成更强的磁场波形，形成的磁感强度如图11所示。
实施例9
一种基于永磁结构的管道退磁装置，由中心件及分布在中心件上的永磁体组成，在所述的管道管壁内由前至后的轴向方向上形成方向交替变化的磁场，磁场强度逐渐减小。
本实施例中使用的永磁体为辐向磁化的环形磁体，该环形磁体为整个辐向磁化的磁环。各环形磁体沿中心件的轴向间隔放置，磁化方向逐个交替反向，沿中心件轴向设置的单环形磁体的尺寸逐渐减小，例如可以是磁体的直径或厚度逐渐减小，磁性能逐渐降低，磁体在管道内形成的磁场强度逐渐衰减，衰减 幅度为10％，设置在退磁装置最前端的永磁体所构成的磁场的强度大于管道的矫顽力。
使用的中心件为导磁构件或不导磁构件，包括实心或空心的铁芯、铝芯或铜芯、不锈钢芯，可以是导磁材料，用以构成磁路；也可以是部分非导磁材料。选用的材料主要以形成合适的磁路为目的。在本实施例中，采用的是实心的铜芯。
该装置可以采用内置式结构，用于长管道内部退磁，在管道内被压力牵引前进使磁化的管道经历交变衰减磁场的过程，实现退磁。
在对天然气石油长输管道进行磁力清管作业或漏磁检测作业时，磁力清管器或漏磁检测器在管内压力的作用下，设备会沿管道向前运动。磁力清管器或漏磁检测器上会安装强磁体，设备所到之处都会使管壁饱和磁化，从而整条长输管道都被严重磁化。
对于天然气石油长输管道，退磁装置采用内置式的结构。退磁装置可以是单独一套装置，在管内被压力牵引前进，使每处管道都经历交变衰减磁场的过程，以此来实现退磁；退磁装置也可以作为附属装置，拖挂于磁力清管器或漏磁检测器的后端，这样在进行传统清管或漏磁检测作业的同时，一并完成管道退磁作业。
为了使该退磁装置始终位于管道的中心从而能够保证退磁效果，在中心件上还固定有支撑件。支撑件可以是导磁材料，如：导磁钢刷，在作为支撑件的同时，还可以作为磁路的一部分；也可以是非导磁材料，如：非导磁不锈钢刷、聚氨酯、滚轮或皮碗等，仅作为支撑件；局部也可以不需要支撑结构。选用的材料主要以形成合适的磁路、并可作为支撑件为目的。本实施例中采用的支撑件为滚轮。
实施例10
一种基于永磁结构的管道退磁装置，其结构与实施例9大致相同，不同之处在于，本实施例中使用的永磁体为由多个磁钢拼接而成的辐向磁化的环形磁体，磁体在管道内形成的磁场强度的衰减幅度为20％。采用的中心件为空心的铝芯，使用的支撑件为皮碗。
实施例11
一种基于永磁结构的管道退磁装置，其结构与实施例9大致相同，不同之处在于，本实施例中使用的永磁体为双环形磁体组成的串联结构为两个辐向磁化、充磁方向相反的环形磁体构成串联组。环形磁体为整个辐向磁化的磁环，采用这种串联组可以逐级调整每个波形的磁场强度，实现精准退磁控制。相邻的两个串联结构中，邻侧的环形磁体之间的磁化方向相同，构成串联结构的两个环形磁体的磁性能和尺寸相同，各串联结构的磁性能逐渐降低，例如可以是磁体的直径或厚度逐渐减小，在管壁内形成的磁场强度衰减幅度5％，本实施例中可以不采用支撑件。
实施例12
一种基于永磁结构的管道退磁装置，其结构与实施例11大致相同，不同之处在于，本实施例中的环形磁体由多个磁钢拼接而成，衰减幅度为60％。本装置在进行退磁处理时，采用的是外置式的结构，因此不需要支撑件。各永磁体为轴向充磁，用于挤出成型管件的退磁，管件从该退磁装置内部穿过经历交变衰减磁场的过程，实现退磁。挤出成形的管件成品在挤出成形的过程中，因受取向磁场的磁化，所以管件成品会是着磁状态。在挤出成形设备的末端，或者在成形模具的出口处，可以放置外置式的退磁装置。只要使管件成品通过退磁装置，即可实现退磁。
挤出成型管件在挤出过程中通过取向磁场被磁化，管道退磁装置设置在取向磁场的后部。设置在退磁装置最前端的永磁体所构成的磁场的强度大于成型管件的矫顽力。另外，在上述环形磁体之间还设有极片。使用的极片为导磁材料。
以上对本发明的具体实施例进行了描述。需要理解的是，本发明并不局限于上述特定实施方式，本领域技术人员可以在权利要求的范围内做出各种变形或修改，这并不影响本发明的实质内容。

Claims (21)

  1. 一种基于永磁结构的管道退磁装置，其特征在于，该退磁装置由中心件及分布在中心件上的永磁体组成，在管道管壁内由前至后的轴向方向上形成方向交替变化的磁场，磁场强度逐渐减小。
  2. 根据权利要求1所述的一种基于永磁结构的管道退磁装置，其特征在于，所述的永磁体为单环形磁体或双环形磁体组成的串联结构。
  3. 根据权利要求2所述的一种基于永磁结构的管道退磁装置，其特征在于，所述的单环形磁体为辐向磁化的环形磁体，该环形磁体为整个辐向磁化的磁环或者由多个磁钢拼接而成。
  4. 根据权利要求2或3所述的一种基于永磁结构的管道退磁装置，其特征在于，各单环形磁体沿中心件的轴向间隔放置，充磁方向逐个交替反向。
  5. 根据权利要求4所述的一种基于永磁结构的管道退磁装置，其特征在于，沿中心件轴向设置的单环形磁体的尺寸逐渐减小，磁性能逐渐降低，磁体在管道内形成的磁场强度逐渐衰减，衰减幅度为1-99％，优选为10-50％。
  6. 根据权利要求2所述的一种基于永磁结构的管道退磁装置，其特征在于，所述的双环形磁体组成的串联结构为两个辐向磁化、充磁方向相反的环形磁体构成串联组。
  7. 根据权利要求6所述的一种基于永磁结构的管道退磁装置，其特征在于，所述的环形磁体为整个辐向磁化的磁环或者由多个磁钢拼接而成。
  8. 根据权利要求6所述的一种基于永磁结构的管道退磁装置，其特征在于，各双环形磁体组成的串联结构沿中心件的轴向间隔放置，串联结构内的两个环形磁体之间的充磁方向相反，相邻的两个串联结构中，邻侧的环形磁体之间的充磁方向相同。
  9. 根据权利要求6所述的一种基于永磁结构的管道退磁装置，其特征在于，构成串联结构的两个环形磁体的磁性能和尺寸相同，各串联结构的环形磁体的尺寸逐渐减小，磁性能逐渐降低，在管壁内形成的磁场强度衰减幅度1-99％，优选10％-50％。
  10. 根据权利要求1所述的一种基于永磁结构的管道退磁装置，其特征在于，所述的中心件为导磁构件或不导磁构件，为实心件或空心件。
  11. 如权利要求1所述的基于永磁结构的管道退磁装置的应用，其特征在于，该装置为内置式结构，用于长管道内部退磁，在管道内被压力牵引前进使磁化的管道经历交变衰减磁场的过程，实现退磁。
  12. 根据权利要求11所述的一种基于永磁结构的管道退磁装置的应用，其特征在于，该装置设有一个或多个，独立设置在管道内或连接在磁力清管器或漏磁检测器的后端。
  13. 根据权利要求12所述的一种基于永磁结构的管道退磁装置的应用，其特征在于，设置在退磁装置最前端的永磁体所构成的磁场的强度大于管道的矫顽力。
  14. 根据权利要求12所述的一种基于永磁结构的管道退磁装置的应用，其特征在于，设置多个退磁装置时，管壁内形成的磁场强度由前至后逐渐减小。
  15. 根据权利要求11所述的一种基于永磁结构的管道退磁装置的应用，其特征在于，该管道退磁装置还设有将其保持在管道中心的支撑件，固定在中心件上，为导磁或不导磁构件。
  16. 根据权利要求15所述的一种基于永磁结构的管道退磁装置的应用，其特征在于，所述的支撑件包括钢刷、滚轮或皮碗。
  17. 如权利要求1所述的基于永磁结构的管道退磁装置的应用，其特征在于，该装置为外置式结构，各永磁体为轴向充磁，用于挤出成型管件的退磁，管件从该退磁装置内部穿过经历交变衰减磁场的过程，实现退磁。
  18. 根据权利要求17所述的一种基于永磁结构的管道退磁装置的应用，其特征在于，所述的挤出成型管件在挤出过程中通过取向磁场被磁化，所述的管道退磁装置设置在取向磁场的后部。
  19. 根据权利要求18所述的一种基于永磁结构的管道退磁装置的应用，其特征在于，设置在退磁装置最前端的永磁体所构成的磁场的强度大于成型管件的矫顽力。
  20. 根据权利要求17所述的一种基于永磁结构的管道退磁装置的应用，其特征在于，各永磁体之间还设有极片。
  21. 根据权利要求20所述的一种基于永磁结构的管道退磁装置的应用，其特征在于，极片为导磁材料，或者设置为辐向充磁的磁体并成极性交替放置。
PCT/CN2017/109523 2017-09-22 2017-11-06 一种基于永磁结构的管道退磁装置及其应用 WO2019056514A1 (zh)

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