A magnetic flux leakage detection system and method for tee branch pipes

Abstract

This invention discloses a magnetic flux leakage (MF) internal detection system and method for tee branch pipes, belonging to the field of pipeline inspection technology. It addresses at least one of the following problems with existing detection equipment: reliance on unidirectional fluid pressure drive, difficulty in operation within passive tee branch pipes or risers, difficulty in achieving tight adhesion between the magnetized structure and the pipe's inner wall, and difficulty in controlling the operating speed of the detection equipment. The MF internal detection system of this invention includes a MF detection module, a cable reel drive module, a mileage measurement module, and a control module. The MF detection module is fixedly connected to the cable reel drive module. The control module controls the movement of the MF detection module within the pipeline via the cable reel drive module. The mileage measurement module is fixed to one end of the cable reel drive module near the MF detection module and is used to calculate the MF detection module's speed within the pipeline and locate the position of defects within the pipeline. This invention can be used for defect detection on the inner wall of tee branch pipes.

Description

Technical Field

[0001] This invention belongs to the field of pipeline inspection technology, specifically relating to a magnetic flux leakage detection system and method for tee branch pipes. Background Technology

[0002] In the petroleum, chemical, and energy industries, the branch pipes and risers (vertical pipes) of tee pipes are crucial components connecting the main transportation lines to ground terminal equipment (valves, metering stations, storage tanks). Defects such as internal corrosion and wall thinning can cause serious safety hazards. Traditional pipeline inspection technologies are mainly designed for long-distance horizontal main transportation pipelines. The detectors used are usually multi-section series structures, which are quite long, and the detectors rely on the fluid pressure inside the pipeline to drive unidirectional operation.

[0003] Existing magnetic flux leakage detectors mainly suffer from the following drawbacks: It is difficult to apply to scenarios involving T-junctions or risers: T-junctions or risers serve as the connection between the main pipeline and the terminal equipment, and there is no launcher / receiver available. During testing, the magnetic flux leakage detector enters and exits the pipeline from the pipe opening of the terminal equipment. Traditional magnetic flux leakage detectors require complete launcher / receiver equipment at both ends of the pipeline to perform testing. Furthermore, traditional magnetic flux leakage detectors have a unidirectional operating structure, making them difficult to use for testing under the working conditions of T-junctions or risers.

[0004] Difficulty in accurately locating defects inside pipes: Since risers are vertical, gravity plays a significant role when the detector is running inside. When the detector moves downwards, its speed is too fast, making it difficult for the magnetized structure of the detector to fit tightly against the inner wall of the pipe, resulting in distorted detection data or equipment damage. When moving upwards, it needs to overcome its own weight and friction, requiring high driving force. Traditional detectors have difficulty controlling their running speed, making it difficult to accurately locate the corresponding position of the defects detected by the detector inside the pipe. Summary of the Invention

[0005] Based on the above analysis, the present invention aims to provide a magnetic flux leakage internal detection system and method for detecting tee branch pipes, which solves at least one of the problems in the prior art: the detection equipment relies on unidirectional fluid pressure drive, making it difficult to operate in passive tee branch pipes or risers; the magnetized structure is difficult to fit tightly against the inner wall of the pipe; and the detection equipment is difficult to control its operating speed.

[0006] The objective of this invention is mainly achieved through the following technical solutions: This invention provides a magnetic flux leakage detection system for a tee branch pipe, comprising a magnetic flux leakage detection module, a cable reel drive module, a mileage measurement module, and a control module. The magnetic flux leakage detection module is fixedly connected to the cable reel drive module. The control module controls the movement of the magnetic flux leakage detection module within the pipe by controlling the output of the cable reel drive module. The mileage measurement module is fixed to one end of the cable reel drive module near the magnetic flux leakage detection module. The mileage measurement module is used to calculate the travel speed of the magnetic flux leakage detection module within the pipe and to locate the position of defects within the pipe.

[0007] Furthermore, the mileage measurement module includes a cable clamp and mileage arms; the cable clamp is fixed to one end of the cable reel drive module near the leakage magnetic field detection module, and the cable clamp is circumferentially provided with multiple mileage arms, the middle of which is rotatably connected to the cable clamp.

[0008] Furthermore, the mileage measurement module also includes a reset lever, a pulse assembly, and mileage wheels; one end of the mileage arm is rotatably connected to the reset lever, and the other end is rotatably connected to the mileage wheels, and the pulse assembly is fixed on the mileage arm.

[0009] Furthermore, the mileage dual wheel includes a driving wheel and a driven wheel that rotate coaxially. The driving wheel contacts the inner wall of the pipe, and the pulse assembly converts the rotation of the driven wheel into a pulse signal.

[0010] Furthermore, the magnetic flux leakage detection module includes a support structure and multiple magnetization structures arranged circumferentially along the support structure; the support structure includes a double-link structure, and the support structure is connected to the magnetization structure through the double-link structure.

[0011] Furthermore, springs are connected to the adjacent sidewalls of the magnetized structure.

[0012] Furthermore, the cable reel drive module includes a cable reel and a composite cable, the composite cable being wound on the cable reel, and the tail end of the composite cable being fixedly connected to the magnetic flux leakage detection module.

[0013] Furthermore, the composite cable includes multiple transmission cables, a load-bearing layer woven from ultra-high molecular weight polyethylene fibers, and a wear-resistant and corrosion-resistant outer sheath.

[0014] Furthermore, the transmission cable is used to realize data transmission between the control module and the mileage measurement module, as well as between the control module and the magnetic flux leakage detection module.

[0015] Furthermore, the present invention also provides a method for internal detection of magnetic flux leakage in a tee branch pipe, which is used by the internal detection system of magnetic flux leakage to detect the inner wall of the pipe.

[0016] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects: (1) The magnetic flux leakage detection system for tee branch pipes provided by the present invention adopts a magnetic flux leakage detection module and a cable reel drive module fixedly connected. The control module controls the detection module to move back and forth in the pipe through the cable reel drive module. A mileage measurement module is set near the detection module of the cable reel drive module, which realizes that the detector can complete the pipe section detection from the same pipe opening, overcoming the limitation of the prior art that relies on the launch tube or unidirectional fluid drive. The mileage measurement module is arranged close to the magnetic flux leakage detection module, which is conducive to binding the defect detection signal with the position, improving the reliability of defect location, and enhancing the practicality and safety of the detector in the tee branch pipe environment.

[0017] (2) The magnetic flux leakage detection system for tee branch pipe provided by the present invention adopts a double-link support structure in conjunction with the spring between adjacent magnetized structures, so that the magnetized structure can adaptively expand or contract radially in pipes with different inner diameters. The elastic expansion force of the spring ensures that the magnetized structure is always in close contact with the pipe wall. Hard alloy balls are set on the contact surface between the magnetized structure and the pipe wall to transform the surface contact into point contact, reduce the frictional resistance between the magnetized structure and the pipe wall, reduce the attenuation of magnetic flux leakage signal caused by poor contact, and improve the signal-to-noise ratio and defect detection sensitivity.

[0018] (3) The leakage magnetic field internal detection system for tee branch pipe provided by the present invention has a structure of multiple mileage arms set in the circumference of the cable clamp. The mileage arms are rotatably connected to the cable clamp. The multi-point redundant mileage measurement scheme can eliminate abnormal values ​​by comparing multiple sets of data when a single drive wheel slips, there is a local protrusion or dirt interference, thereby improving the stability of mileage measurement.

[0019] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0020] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0021] Figure 1 This is a schematic diagram of the internal magnetic flux leakage detection system for a three-way branch pipe provided in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the magnetic flux leakage detection module and the mileage measurement module in the magnetic flux leakage detection system for a three-way branch pipe provided in Embodiment 1 of the present invention. Figure 3This is a schematic diagram of the leakage magnetic field detection module in the leakage magnetic field detection system for a three-way branch pipe provided in Embodiment 1 of the present invention. Figure 4 This is a schematic diagram of the mileage measurement module in the internal magnetic flux leakage detection system for a three-way branch pipe provided in Embodiment 1 of the present invention. Figure 5 This is a flowchart of the speed control method in the internal magnetic flux leakage detection method provided in Embodiment 2 of the present invention.

[0022] Figure label: 1-Fluorescence detection module; 11-Support structure; 111-Support body; 112-Support base; 113-Double linkage structure; 114-Support cup; 115-Spring; 12-Magnetization structure; 121-Yoke; 122-Permanent magnet; 123-Wear pad; 124-Guide seat; 125-Hard alloy ball; 13-Sensor structure; 14-Acquisition box; 15-Anti-collision head; 2-Cable reel drive module; 21-Cable reel; 22-Composite cable; 3-Mileage measurement module; 31-Cable clamp; 32-Reset rod; 33-Reset spring; 34-Mileage arm; 35-Pulse assembly; 36-Mileage dual wheels; 361-Driving wheel; 362-Driven wheel; 4-Control module; 5-Pipeline. Detailed Implementation

[0023] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0024] Example 1 To address the problem that existing detection devices rely on unidirectional fluid pressure for operation in passive tee branch pipes, a specific embodiment of the present invention discloses an internal magnetic flux leakage detection system for tee branch pipes, such as... Figure 1 As shown, it includes a magnetic flux leakage detection module 1, a cable reel drive module 2, a mileage measurement module 3, and a control module 4. The magnetic flux leakage detection module 1 is fixedly connected to the cable reel drive module 2. The control module 4 controls the movement of the magnetic flux leakage detection module 1 in the pipe 5 through the cable reel drive module 2. The mileage measurement module 3 is fixed to one end of the cable reel drive module 2 near the magnetic flux leakage detection module 1. The mileage measurement module 3 is used to calculate the travel speed of the magnetic flux leakage detection module 1 in the pipe 5 and to locate the position of defects in the pipe 5.

[0025] Furthermore, in order to solve the problem of detecting defects in the inner wall of tee branch pipes of different diameters, such as... Figure 2 and Figure 3As shown, the magnetic flux leakage detection module 1 includes a support structure 11 and a magnetization structure 12. The support structure 11 includes a support body 111, a support base 112, a double-link structure 113, and a support cup 114. Several support bases 112 are circumferentially fixed on the inner surfaces at both ends of the support body 111. The support base 112 is rotatably connected to one end of the double-link structure 113, and the support base 112 serves as the fulcrum for the rotation of the double-link structure 113. The two double-link structures 113 are rotatably connected to the two ends of the bottom surface of the magnetization structure 112. The length of the magnetization structure 112 is... The direction of the angle is parallel to the axis of the support structure 11. The support base 112 and the double linkage structure 113 cooperate to form a movable connection mechanism. When the inner diameter of the pipe 5 changes, the angle of the double linkage structure 113 can be changed freely, causing the magnetization structure 12 to move closer to or away from the center line of the pipe, so as to realize the function of adapting to different pipe diameters. The outer surfaces of both ends of the support body 111 are fixedly connected with support cups 114. The support cups 114 provide auxiliary support for the support structure 11 inside the pipe 5, so that the axis of the leakage magnetic field detection module 1 coincides with the center line of the pipe.

[0026] Furthermore, to address the issue of the magnetized structure's difficulty in achieving a tight fit with the inner wall of the pipe, several springs 115 are connected to the side walls of adjacent magnetized structures 12. When performing defect detection on pipes 5 with different inner diameters, the magnetic flux leakage detection module 1 is placed inside the inner wall of the pipe 5. The inner wall of the pipe 5 radially compresses the magnetized structure 12, reducing the spacing between adjacent magnetized structures 12 and compressing the springs 115. The compression of the springs 115 by the magnetized structure 12 generates an outward elastic expansion force. The expansion force of the springs 115, in conjunction with the double-link structure 113, ensures that the magnetized structure 12 fits tightly against the inner wall of the pipe, reducing the attenuation of the magnetic flux leakage signal due to poor contact between the magnetized structure 12 and the inner wall of the pipe 5. On the other hand, it adjusts the distance between the magnetized structure 12 and the axis of the support structure 11, enabling the magnetic flux leakage detection module 1 to detect pipes 5 with different inner diameters.

[0027] Specifically, the magnetization structure 12 includes an iron yoke 121, a permanent magnet 122, a wear-resistant pad 123, a guide seat 124, and a hard alloy ball 125. The bottom two ends of the iron yoke 121 are rotatably connected to the ends of the two double-link structures 113 away from the support seat 112. Both ends of the upper surface of the iron yoke 121 are provided with permanent magnets 122. The upper surface of the permanent magnets 122 is provided with wear-resistant pads 123. Hard alloy balls 125 are embedded in the wear-resistant pads 123. The hard alloy balls 125 contact the inner wall of the pipe 5 to magnetize the pipe wall and form a magnetic circuit.

[0028] Specifically, the carbide ball 125 transforms the surface contact between the wear-resistant pad 123 and the inner wall of the pipe 5 into point contact, reducing the frictional resistance of the magnetic flux leakage detection module 1 moving within the pipe 5, improving the control of the cable reel drive module 2 over the movement of the magnetic flux leakage detection module 1, and reducing the signal attenuation caused by poor contact between the wear-resistant pad 123 at one end and the inner wall of the pipe 5 due to friction between the wear-resistant pad 123 at one end and the inner wall of the pipe 5. Guide seats 124 are installed on the outer side of the two permanent magnets 122. The guide seats 124 are used to reduce the collision of protrusions or weld beads within the pipe 5 with the permanent magnets 122. The sensor structure 13 is located on the inner side of the two permanent magnets 122. The sensor structure 13 uses a triaxial magnetic sensor to detect changes in the magnetic field of the pipe wall (the principle of magnetic flux leakage detection is existing technology and will not be described in detail here).

[0029] The magnetic flux leakage detection module 1 also includes a sensor structure 13 and a data acquisition box 14. The data acquisition box 14 is installed inside the housing at one end of the support structure 11. The data acquisition box 14 is used to receive data from the sensor structure 13 and transmit the data to the control module 4 through the transmission cable in the composite cable 22. The other end of the support structure 11 is fixedly connected to the composite cable 22. The composite cable 22 drives the magnetic flux leakage detection module 1 to move in the pipe 5 through the support structure 11.

[0030] Specifically, the cable reel drive module 2 includes a cable reel 21 and a composite cable 22. The drive motor is connected to the cable reel 21, and the composite cable 22 is coiled on the cable reel 21. The tail end of the composite cable 22 is fixedly connected to the magnetic flux leakage detection module 1. The composite cable 22 includes at least the following from the inside out: multiple transmission cables, a load-bearing layer woven from Kevlar or ultra-high molecular weight polyethylene fiber, and a wear-resistant and corrosion-resistant outer sheath. The transmission cables are used for bidirectional data communication between the acquisition box 14 and the control module 4, and the load-bearing layer is used to withstand the tension and thrust between the cable reel 21 and the magnetic flux leakage detection module 1.

[0031] Furthermore, in order to solve the problem of collision damage between the magnetic flux leakage detection module 1 and the pipe wall 5, an anti-collision head 15 is fixedly connected to the end of the magnetic flux leakage detection module 1 away from the composite cable 22. The anti-collision head 15 is used to reduce the collision between the magnetic flux leakage detection module 1 and the T-junction branch pipe. A data debugging port is provided in the middle of the anti-collision head 15. The data debugging port is used for the system to read data during the debugging process.

[0032] Furthermore, to address the problem of locating defects within pipelines using existing detection equipment, the magnetic flux leakage internal detection system also includes a mileage measurement module 3, such as... Figure 2 and Figure 4As shown, the mileage measurement module 3 includes a cable clamp 31, a reset lever 32, a reset spring 33, mileage arms 34, a pulse assembly 35, and mileage dual wheels 36. The cable clamp 31 is fixed to one end of the composite cable 22 near the leakage magnetic field detection module 1. At least three mileage arms 34 are evenly arranged around the circumference of the cable clamp 31. The middle part of the mileage arm 34 is rotatably connected to the cable clamp 31. One end of the mileage arm 34 is rotatably connected to the reset lever 32, and the other end is rotatably connected to the mileage dual wheels 36. The reset spring 33 is sleeved on the reset lever 34. Externally, one side of the reset spring 33 contacts the lower surface of the cable clamp 31, and the other side contacts the end face of the reset pull rod 32. The reset spring 33 pushes one end of the reset pull rod 32, and the other end of the reset pull rod 32 pulls the mileage arm 34, so that the mileage double wheel 36 keeps in contact with the inner wall of the pipe 5. The pulse assembly 35 is fixed in the hollow area of ​​the mileage arm 34. The mileage double wheel 36 includes a coaxially rotating drive wheel 361 and a driven wheel 362. The drive wheel 361 contacts the inner wall of the pipe 5, and the driven wheel 362 contacts the pulse assembly 35.

[0033] Specifically, when the mileage measurement module 3 moves inside the pipe 5, the driving wheel 361 rubs against the inner wall of the pipe 5, and the driving wheel 361 drives the driven wheel 362 to rotate. The pulse component 35, through toothed contact with the outer surface of the driven wheel 362, converts the rotation angle of the driven wheel 362 into a pulse signal. The pulse component 35 transmits the pulse signal to the control module 4 through the transmission cable in the composite cable 22. The control module 4 calculates the travel distance and speed of the mileage measurement module 3 based on the number of pulse signals and the size of the driving wheel 361. Multiple mileage arms 34 are set around the cable clamp 31 to form a redundant measurement scheme. Multiple sets of data are compared and calibrated to eliminate errors caused by slippage or abnormality of the driving wheel 361. The detection data of the sensor structure 13 is bound to the position of the corresponding mileage measurement module 3 to mark the specific coordinates of the defect location inside the pipe.

[0034] Furthermore, to address the issue of existing detection equipment's inability to control the operating speed of the magnetic flux leakage detection module 1, the control module 4 employs an incremental digital PID control algorithm, such as... Figure 5 As shown, the voltage of the drive motor is adjusted by the motor controller to control the output speed, thereby controlling the transmission and reception speed of the composite cable 22 driven by the cable reel 21, so as to realize the uniform movement of the leakage magnetic field detection module 1 and the mileage measurement module 3.

[0035] The continuous-time expression output of the PID controller is:

[0036] in, : The drive voltage output by the controller (voltage command for driving the motor); : Proportional coefficient; Integral coefficient; Differential coefficients; (Preliminary tuning is performed using the Ziegler-Nichols method to obtain the critical gain) and oscillation period , and then calculate , , The benchmark value is based on existing experimental methods and will not be elaborated upon here.

[0037]

[0038] Speed ​​error; Initial speed setting; Actual speed of motion;

[0039] The diameter of the drive wheel 361; : Number of pulses within the sampling period; The number of pulses generated when the driven wheel 362 rotates once; Sampling period; This system uses a digital PID controller, discretizing the continuous PID model. Drive voltage at each sampling time The expression is:

[0040] in, : No. The velocity error at each sampling time; previous driving voltage The expression is:

[0041] Since the discrete PID model is computationally intensive and cannot be implemented in hardware, an incremental approach is introduced. It can be derived as follows:

[0042] make:

[0043]

[0044]

[0045] Then the increment Simplified to:

[0046] Control module 4 calculates the drive voltage The expression is:

[0047] To further improve the smooth output of control module 4, control module 4 adds anti-disturbance strategies, including static friction compensation strategy, anti-integral saturation strategy and adaptive fine-tuning strategy. To overcome the static friction force during startup or extremely low-speed operation of the leakage flux detection module 1, a static friction compensation strategy actively applies a control signal to the PID controller. This helps the leakage flux detection module 1 smoothly transition from a stationary state to a moving state. Traditional PID controllers, to overcome static friction during startup or extremely low-speed operation, continuously accumulate the integral term until the output is sufficiently large. When the leakage flux detection module 1 begins to move, the accumulated integral term may cause the module to suddenly overshoot (overshoot), resulting in unsmooth speed control. Therefore, a fixed feedforward compensation voltage U is injected into the PID controller. comp This ensures that the magnetic flux leakage detection module 1 starts up smoothly and quickly, reducing vibration or startup failure caused by static friction.

[0048] Anti-integral saturation strategy: To limit the invalid accumulation of the integral term in the PID controller, when the drive voltage... When saturation has been reached, if the speed error As long as it persists, the integral term will continue to accumulate to a very large value, when the speed error... In the reverse direction, the integral term takes a long time to decrease, resulting in a higher drive voltage. If the system remains in the saturation region, causing control module 4 to experience significant overshoot or prolonged oscillation, a speed error threshold e can be set. max When the velocity error |e(t)| at time t continuously exceeds e max When the integral term is frozen (1%~3% for detection equipment with medium to high precision), the accumulated value of the integral term is no longer updated, the integral value remains unchanged, and the driving voltage is reduced. Saturation, when speed error When the error falls back below the error threshold, the integral term resumes updating.

[0049] To reduce PID controller overshoot caused by the lag of the integral term, the adaptive fine-tuning strategy addresses the issue that due to the lag of the integral term, when the PID controller recovers from a state with a large deviation to the target value, the integral term has already accumulated a large value. Therefore, it is necessary to dynamically fine-tune the integral term according to the error trend to prevent PID controller overshoot. The integral term will automatically weaken when approaching the target. When encountering local resistance that causes a speed drop, the integral term can be adjusted in a timely manner during the recovery process, reducing overshoot oscillations after recovery, resulting in a smoother speed curve, better spatial uniformity of sensor sampling, and more accurate defect location.

[0050] Example 2 This embodiment provides a method for detecting magnetic flux leakage in a three-way branch pipe, using the magnetic flux leakage detection system provided in Embodiment 1.

[0051] Compared with the prior art, the beneficial effects of the internal magnetic flux leakage detection method for the three-way branch pipe provided in this embodiment are basically the same as those of the internal magnetic flux leakage detection system provided in Embodiment 1, and will not be described in detail here.

[0052] Specifically, the above-mentioned internal magnetic flux leakage detection method includes the following steps: Step S1: System deployment and module connection. Connect the magnetic flux leakage detection module 1, cable reel drive module 2, mileage measurement module 3 and control module 4 in the magnetic flux leakage detection system. Fix the tail end of the magnetic flux leakage detection module 1 to the composite cable 22. Fix the mileage measurement module 3 to the end of the composite cable 22 near the magnetic flux leakage detection module 1 by cable clamp 31. The transmission cable in the composite cable 22 connects the control module 4 to the acquisition box 14 and the pulse component 35 respectively. The composite cable 22 is wound on the cable reel 21. The cable reel 21 is connected to the drive motor. The control module 4 controls the drive motor through the motor controller.

[0053] Step S2: System debugging and parameter calibration. Place the magnetic flux leakage detection system into a standard pipeline and use a forward pull method to detect standard defects. Read the detection data through the data debugging port set in the middle of the anti-collision head, compare the detection data with the standard data, and calculate the proportionality coefficient according to the Ziegler-Nichols method. Integral coefficient Differential coefficients The value of .

[0054] Step S3: Forward detection. The calibrated magnetic flux leakage detection module 1 and odometer measurement module 3 are inserted into the pipeline to be tested through a reducer. The constant speed is input to the control module 4. The control module 4 controls the drive motor through the motor controller. The drive motor drives the cable reel 21 to rotate, causing the composite cable 22 to extend into the pipe. The composite cable 22 pushes the leakage magnetic field detection module 1 and the mileage measurement module 3 to move into the pipe at a constant speed.

[0055] Step S4: Return detection. After the magnetic flux leakage detection module 1 reaches the detection endpoint, the control module 4 controls the drive motor to reverse, and the cable reel 21 reverses to pull back the composite cable 22. The composite cable 22 is pulled back to the magnetic flux leakage detection module 1 and the mileage measurement module 3 at a constant speed.

[0056] It should be noted that during steps S3 and S4, the sensor structure 13 continuously detects the changes in the magnetic field of the pipe wall and stores the detection data in the acquisition box 14. The driving wheel 361 is always in contact with the inner wall of the pipe. The driving wheel 361 drives the driven wheel 362 to rotate. The pulse component 35 emits a pulse signal. The control module 4 receives the data from the acquisition box 14 and the pulse component 35 through the composite cable 22.

[0057] To control the leakage flux detection module 1 and the mileage measurement module 3 to move at a constant speed, within each acquisition cycle of the PID controller, such as Figure 5 As shown, control module 4 needs to perform the following steps in sequence: acquire pulse signals - calculate speed using pulse signals. - Calculate speed error -Execute incremental PID calculation-Controller output drive voltage Each acquisition cycle is controlled by adjusting the drive voltage. The speed of the drive motor is adjusted, which in turn adjusts the rotation of the cable reel 21. The cable reel 21 drives the composite cable 22 to increase the speed of the leakage magnetic field detection module 1 and the mileage measurement module 3 within the pipeline.

[0058] Step S5: Data processing and calibration. The data obtained by the control module 4 in steps S3 and S4 are compared, calibrated, and calibrated for mileage. The control module 4 receives two sets of magnetic field signals and location information of the pipeline defect. It should be noted that the data obtained by the control module 4 in step S4 is more reliable than the data obtained by the control module 4 in step S3. Since the cable reel 21 reverses and pulls back the composite cable 22, the composite cable 22 remains taut during the uniform speed pull-back of the magnetic flux leakage detection module 1 and the mileage measurement module 3. At this time, the linear speed of the cable reel 21 is closer to the speed calculated by the mileage measurement module 3. Therefore, the data obtained in step S4 is more reliable.

[0059] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A magnetic flux leakage detection system for a tee branch pipe, characterized in that, It includes a magnetic flux leakage detection module (1), a cable reel drive module (2), a mileage measurement module (3), and a control module (4); the magnetic flux leakage detection module (1) is fixedly connected to the cable reel drive module (2), the control module (4) controls the movement of the magnetic flux leakage detection module (1) in the pipe (5) through the cable reel drive module (2), the mileage measurement module (3) is fixed to one end of the cable reel drive module (2) near the magnetic flux leakage detection module (1), and the mileage measurement module (3) is used to calculate the travel speed of the magnetic flux leakage detection module (1) in the pipe (5) and locate the position of the defect in the pipe (5).

2. The internal magnetic flux leakage detection system for a tee branch pipe according to claim 1, characterized in that, The mileage measurement module (3) includes a cable clamp (31) and mileage arms (34); the cable clamp (31) is fixed to one end of the cable reel drive module (2) near the leakage magnetic detection module (1), and the cable clamp (31) is provided with multiple mileage arms (34) in the circumferential direction, and the middle part of the mileage arm (34) is rotatably connected to the cable clamp (31).

3. The internal magnetic flux leakage detection system for a tee branch pipe according to claim 2, characterized in that, The mileage measurement module (3) also includes a reset lever (32), a pulse assembly (35), and a mileage wheel (36); one end of the mileage arm (34) is rotatably connected to the reset lever (32), and the other end is rotatably connected to the mileage wheel (36); the pulse assembly (35) is fixed on the mileage arm (34).

4. The internal magnetic flux leakage detection system for a tee branch pipe according to claim 3, characterized in that, The mileage dual wheel (36) includes a driving wheel (361) and a driven wheel (362) that rotate coaxially. The driving wheel (361) contacts the inner wall of the pipe (5), and the pulse assembly (35) converts the rotation of the driven wheel (362) into a pulse signal.

5. The internal magnetic flux leakage detection system for a tee branch pipe according to claim 1, characterized in that, The magnetic flux leakage detection module (1) includes a support structure (11) and a plurality of magnetization structures (12) arranged circumferentially along the support structure (11); the support structure (11) includes a double-link structure (113), and the support structure (11) is connected to the magnetization structure (12) through the double-link structure (113).

6. The internal magnetic flux leakage detection system for a tee branch pipe according to claim 5, characterized in that, A spring (115) is connected to the side wall of the adjacent magnetized structure (12).

7. The internal magnetic flux leakage detection system for a tee branch pipe according to claim 1, characterized in that, The cable reel drive module (2) includes a cable reel (21) and a composite cable (22), the composite cable (22) being coiled on the cable reel (21), and the tail end of the composite cable (22) being fixedly connected to the magnetic flux leakage detection module (1).

8. The internal magnetic flux leakage detection system for a tee branch pipe according to claim 7, characterized in that, The composite cable (22) includes multiple transmission cables, a load-bearing layer woven from ultra-high molecular weight polyethylene fibers, and a wear-resistant and corrosion-resistant outer sheath.

9. The internal magnetic flux leakage detection system for a tee branch pipe according to claim 4, characterized in that, The transmission cable is used for data transmission between the control module (4) and the mileage measurement module (3) and between the control module (4) and the magnetic flux leakage detection module (1).

10. A method for detecting magnetic flux leakage in a three-way branch pipe, wherein the magnetic flux leakage detection system described in any one of claims 1 to 9 is used to detect the inner wall of the pipe (5).

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