Water leakage detection system and detection method at water pipe joints based on distributed optical fiber sensing

Abstract

The present invention discloses a water leakage detection system and method for water pipe connections based on distributed optical fiber sensing. The detection system includes a fixed assembly; a leakage collection conduit; the leakage collection conduit is disposed outside the water supply pipe connection via the fixed assembly; a leakage collection and discharge device; the leakage collection and discharge device is mounted at the bottom of the leakage collection conduit; a mechanical structure; the mechanical structure is disposed within the leakage collection and discharge device and is mechanically moved to empty the stored water and reset the device after emptying the stored water; a sensing optical fiber; the sensing optical fiber is connected to the leakage collection and discharge device and / or the mechanical structure; and a demodulation device; the demodulation device receives signals from the sensing optical fiber and determines whether the water supply pipe connection is leaking, the location of the leak, and the severity of the leak based on the signals. The present invention can accurately determine the location of the leak while also analyzing the severity of the leak, thus achieving high detection accuracy.

Description

Technical Field

[0001] The present invention belongs to the field of water supply pipeline leakage detection, and in particular relates to a water leakage detection system and a detection method at a water pipe connection based on distributed optical fiber sensing. Background Art

[0002] Timely and accurate detection of leaks in water supply trunk pipelines allows operators to implement timely and effective maintenance measures, reducing water supply network operation and maintenance costs while ensuring smooth operations for residents and industrial production. Given the length of water supply trunk pipelines, distributed fiber optic sensing technology, capable of simultaneous monitoring over distances of ten kilometers or more, has been widely used for leak detection in these pipelines. However, it still has drawbacks.

[0003] Utility model patent CN213983030U discloses a pipeline monitoring system that combines electrical impedance and distributed optical fiber, which can identify leaks by the temperature difference between the water in the pipe and the surrounding environment at the time of leakage. However, this method cannot handle the small flow leakage in the early stage of water supply pipeline leakage. The distributed optical fiber system cannot work normally when the temperature difference between the water in the pipe and the environment outside the pipe is very small. Utility model patent CN214222756U discloses a water supply pipeline monitoring system based on distributed optical fiber vibration monitoring. The optical fiber is laid along the pipeline and changed to a continuous surrounding layout at the pipeline joints to detect the vibration caused by water leakage to determine the leakage situation. This method does not require a temperature difference between the inside and outside of the pipeline, and can also focus on monitoring the pipeline joints that are most prone to leakage, but it still cannot effectively sense small flow leakage. Utility model patent CN215492313U discloses a pipeline leak detection device based on a carbon fiber and fiber Bragg grating composite sensor. This device, designed with a flow channel to collect leaks, solves the problem of detecting small flow rates. However, this collection method simply immerses the optical fiber in the leaking water, failing to detect more typical features of the leak process, reducing accuracy. Leak detection relies on energizing the carbon fiber and heating the surrounding environment, which poses operational risks such as short circuits. The limited power supply distance of the internal conductor also limits the length of the monitored pipeline. Utility model patent CN215262312U discloses a multi-parameter, multi-modal, high-precision pipeline leak monitoring and location system. This system uses multiple optical fibers and water-swelling materials to simultaneously monitor temperature, humidity, and leak vibration. It eliminates the need for additional electrical heating devices and can accumulate small leaks through the material's water absorption. However, this requires the integration of a multi-parameter demodulation system and multiple sensing fibers, making the system complex to implement. Detecting small leaks using water-swelling materials and optical fibers has poor location accuracy, while vibration detection, while highly accurate, offers lower detection accuracy. Invention patent CN107883192A discloses a leakage detection system based on fiber optic temperature sensing. A water collection tank and a water-absorbing material are provided to send the collected leakage water to a first fiber optic temperature sensor. At the same time, a second fiber optic temperature sensor that does not contact the leakage water is provided. The leakage water absorbs heat due to evaporation, and the temperature difference between the first and second fiber optic temperature sensors is used to determine leakage. No external energy input is required and the positioning is accurate. However, this method cannot determine the severity of the leak, and the water-absorbing material easily absorbs impurities such as rust, which will affect the performance of the system in the long term. Summary of the Invention

[0004] To address the challenges of existing technologies, the present invention provides a water pipe joint leak detection system based on distributed fiber optic sensing. By combining a single distributed fiber optic technology with a collection device, the present invention can accurately detect and locate minute water leaks at each joint in the water supply pipeline, without requiring special requirements such as power supply or water temperature. Furthermore, the present invention also provides a water pipe joint leak detection method based on distributed fiber optic sensing.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A first aspect of the present invention provides a water leakage detection system for water pipe connections based on distributed optical fiber sensing, comprising:

[0007] Fixing components;

[0008] Leakage collection conduit; the leakage collection conduit is arranged outside the water supply pipe connection through a fixing component, the leakage collection conduit is arranged entirely or partially around the water supply pipe, and the leakage collection conduit is provided with a drainage port;

[0009] Leakage collection and discharge device; the leakage collection and discharge device is installed at the lower part of the leakage collection conduit, and the leakage collection conduit is connected to the interior of the leakage collection and discharge device through a drainage port;

[0010] Mechanical structure; the mechanical structure is arranged inside the leakage collection and discharge device, responding to the gravity change of the water stored in the leakage collection and discharge device, and realizing emptying the water and resetting the water after emptying the water through mechanical movement;

[0011] Sensing optical fiber; the sensing optical fiber is connected to the leakage collection and discharge device and / or the mechanical structure, and the sensing optical fiber senses the mechanical movement of the mechanical structure and / or the process of accumulating and draining water in the leakage collection and discharge device;

[0012] Demodulation equipment; the demodulation equipment receives the signal from the sensing optical fiber and determines whether there is a leak at the water supply pipe connection, the location of the leak and the severity of the leak based on the signal.

[0013] Preferably, the demodulation device is a distributed optical fiber vibration sensing demodulation device, which senses the mechanical vibration excitation generated when the mechanical structure is emptied of water and reset.

[0014] Preferably, the demodulation device is a distributed optical fiber strain sensing demodulation device, which senses the strain of the sensing optical fiber affected by the accumulated water when the leakage collection and discharge device accumulates water and drains the accumulated water.

[0015] Preferably, when the amount of water stored in the leakage collection and discharge device reaches a set amount, the mechanical structure is activated to discharge the water in the leakage collection and discharge device, and the mechanical structure is reset after the water in the leakage collection and discharge device is discharged.

[0016] Preferably, the leakage collection and discharge device is located directly below the connection point of the water supply pipe.

[0017] A second aspect of the present invention provides a method for detecting water leakage at a water pipe connection based on distributed optical fiber sensing, which uses the above-mentioned water pipe connection water leakage detection system and is characterized by comprising the following steps:

[0018] Step 1: In the initial state, there is no water in the leakage collection and discharge device, and no signal is input to the sensing optical fiber;

[0019] Step 2: The leakage collection and discharge device continuously collects the leaked water arriving through the leakage collection conduit, and the sensing optical fiber begins to receive signals;

[0020] Step 3: When the water in the leakage collection and drainage device accumulates to a certain volume and the water gravity exceeds a preset threshold, the mechanical structure automatically starts to drain the water. The mechanical structure then resets to its initial state, and the sensing fiber receives the target signal.

[0021] Step 4: The demodulation device identifies, locates, and analyzes the target signal received by the sensing optical fiber in step 2 and / or step 3 to determine whether leakage occurs, the location of leakage, and the severity of leakage.

[0022] Preferably, in step three, the target signal is a characteristic vibration signal.

[0023] Preferably, in step 2 and step 3, the target signal is a strain signal generated by water accumulation.

[0024] Compared with the prior art, the present invention has the following technical effects:

[0025] (1) The present invention uses optical fiber sensors and auxiliary components to effectively detect small leaks at various connections in longer pipelines.

[0026] (2) The system of the present invention can operate and reset automatically without external control and energy input, and is suitable for long-term reliable monitoring.

[0027] (3) The present invention can not only accurately determine the leakage location, but also analyze the severity of the leakage, and has high detection accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0029] Figure 1 This is a side view of the water leakage detection system at the water pipe connection point of Example 1 of the present invention.

[0030] Figure 2 This is a transverse cross-sectional schematic diagram of a water leakage detection system at a water pipe connection according to Example 1 of the present invention.

[0031] Figure 3 This is a workflow diagram of Example 1 of the present invention.

[0032] Figure 4 This is a side view of a water leakage detection system at a water pipe connection according to embodiment 2 of the present invention.

[0033] Figure 5 This is a transverse cross-sectional schematic diagram of a water leakage detection system at a water pipe connection according to embodiment 2 of the present invention.

[0034] Figure 6 This is a workflow diagram of Example 2 of the present invention.

[0035] The specific descriptions of the reference numerals are as follows:

[0036] Example 1: water supply pipe 101, leakage collection conduit 102, fixing assembly 103, leakage collection and discharge device 104, sensing optical fiber 105, distributed optical fiber vibration sensing and demodulation equipment 106, seepage water collection container 107, counterweight 108, rigid connecting rod 109, rotating shaft 110, water inlet 111;

[0037] Example 2: Water supply pipe 401, leakage collection conduit 402, fixing assembly 403, leakage collection and discharge device 404, sensing optical fiber 405, distributed optical fiber strain sensing and demodulation equipment 406, counterweight block 407, rotating shaft 408, baffle 409, water inlet 410. DETAILED DESCRIPTION

[0038] In the description of the present invention, it should be understood that the terms "longitudinal", "transverse", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0039] Example 1

[0040] This embodiment provides a water leakage detection system at the connection of water pipes based on distributed vibration optical fiber sensing. The side view of the system is shown in FIG. Figure 1 As shown, the transverse cross-section is as follows Figure 2As shown, the device comprises: a water supply pipe 101, which is formed by welding several pipe sections together; a leakage collection conduit 102, which is arranged in an arc shape around the connection between adjacent pipe sections of the water supply pipe 101 and collects leaked water from the connection. A drainage outlet is provided at the bottom of the leakage collection conduit 102; and a fixing assembly 103, which is used to secure the leakage collection conduit 102 to the connection between adjacent pipe sections. Leakage collection and drainage device 104; the leakage collection and drainage device 104 is installed at the lower part of the leakage collection conduit 102, and the leakage collection conduit 102 is connected to the interior of the leakage collection and drainage device 104 through a drainage port, and can collect the leakage water gathered by the leakage collection conduit 102, and automatically empty the water and reset after the leakage water reaches a certain amount; the leakage collection and drainage device 104 is provided with a mechanical structure inside, which responds to the gravity change of the water stored in the leakage collection and drainage device 104, and realizes the emptying of the stored water and reset after emptying the stored water through mechanical movement. Sensing optical fiber 105; the sensing optical fiber 105 passes through the leakage collection and drainage device 104 at the connection of each pipe section along the water supply pipe 101 in sequence, but does not affect the water storage and drainage of the leakage collection and drainage device 104. Distributed optical fiber vibration sensing and demodulation equipment 106; continuously monitors the vibration conditions of each position of the sensing optical fiber 105.

[0041] Please continue to refer to Figure 2In this embodiment, the leakage collection and discharge device 104 includes a collection and detection body and a mechanical structure. The collection and detection body is a cavity-type structure. The upper end surface of the collection and detection body is provided with a water inlet 111, and the water inlet 111 is located directly below the drainage port. A mechanical structure is provided inside the collection and detection body. The mechanical structure includes a seepage water collection container 107, a counterweight 108, a rigid connecting rod 109, and a rotating shaft 110. The middle part of the rigid connecting rod 109 is rotatably mounted on the rotating shaft 110. The seepage water collection container 107 is fixedly mounted on one end of the rigid connecting rod 109 and is located directly below the water inlet 111. The end surface of the seepage water collection container 107 away from the rigid connecting rod 109 is tilted from bottom to top in an outward direction. The counterweight 108 is fixedly mounted on the other end of the rigid connecting rod 109. The rigid connecting rod 109 is in the first extreme position or moves from the first extreme position to the second extreme position or returns from the second extreme position to the first extreme position. When the rigid connecting rod 109 is in the first extreme position, the sensing optical fiber 105 is located below the counterweight 108. Specifically, the sensing optical fiber 105 senses the impact of the counterweight 108 on the sensing optical fiber 105 when it returns from the second extreme position to the first extreme position. When the rigid connecting rod 109 is in the first extreme position, it is in a horizontal state. At this time, the opening of the seepage water collection container 107 faces directly upward, which is used to collect leaked water at the connection of the water supply pipe 101. When the rigid connecting rod 109 is in the second extreme position, it is in an inclined state. At this time, the opening of the seepage water collection container 107 is inclined downward, which is used to discharge the water stored in the seepage water collection container 107.

[0042] When the water supply pipe 101 is actually used, the middle part of each section of the pipe is relatively reliable, and leakage usually first appears at the pipe connection, which is manifested as a small flow of leakage. Figure 3 As shown, the specific steps include:

[0043] Step 1-1: Initially, there is basically no water in the leakage collection and discharge device 104, the vibration applied to the sensing optical cable by the collection and detection body and the mechanical structure is basically zero, and the rigid connecting rod 109 is at the first extreme position.

[0044] Step 1-2: The seepage water collection container 107 inside the leakage collection and discharge device 104 continuously collects the leakage water collected by the leakage collection conduit 102 through the water inlet 111. The amount of water stored in the seepage water collection container 107 gradually increases, but the total amount of water stored is small. The rigid connecting rod 109 does not rotate, and the vibration applied to the sensing optical cable is weak.

[0045] Step 1-3: When the volume of water in seepage water collection container 107 exceeds a preset threshold, the seepage water collection container, rigid connecting rod 109, and counterweight 108 begin to rotate counterclockwise about rotation axis 110. After a certain rotation angle, the water begins to drain. At this point, rigid connecting rod 109 continues to rotate counterclockwise due to inertia until the angular velocity drops to zero, reaching the maximum counterclockwise rotation angle, or the second extreme position, at which point all the water is drained.

[0046] In step 1-4, counterweight 108 pulls rigid connecting rod 109 clockwise, accelerating its rotation. After striking the optical sensing cable, it stops due to the restraining action of optical sensing fiber 105. This impact imparts a short, high-amplitude characteristic vibration signal to the optical sensing cable. After this step, leakage collection and drainage device 104, its internal mechanical structure, and the optical sensing cable automatically return to their initial state, returning to step 1-1.

[0047] In step 1-5, the distributed optical fiber vibration sensing and demodulation device 106 identifies and locates the characteristic vibrations involved in step 1-4, determining whether and where leakage has occurred. Simultaneously, the distributed optical fiber vibration sensing and demodulation device 106 continuously monitors leakage vibration events at various locations along the sensing cable. As the amount of water leakage increases, the repetition period of steps 1-1 through 1-4 shortens, and the frequency of the characteristic vibration signal increases. The distributed optical fiber vibration sensing and demodulation device 106 analyzes the frequency of the characteristic vibrations detected by the sensing cable to further determine the severity of the leakage.

[0048] Example 2

[0049] Implementation 1 has a quick response, but the characteristic vibration signal lasts for a short time and is easily disturbed by environmental vibration, making identification difficult. In view of this, this embodiment proposes a water pipe connection micro-leakage detection system based on distributed vibration fiber optic sensing. The side view of the system is shown in FIG. Figure 4 As shown, the transverse cross-section is as follows Figure 5As shown, the device comprises a water supply pipe 401, which is formed by welding several pipe sections together. A leakage collection conduit 402 is provided, which is arranged in an arc shape around the connection between adjacent pipe sections of the water supply pipe 401 and collects leaked water from the connection. A drainage outlet is provided at the bottom of the leakage collection conduit 402. A fixing assembly 403 is provided, which is used to secure the leakage collection conduit 402 to the connection between adjacent pipe sections. Leakage collection and drainage device 404; Leakage collection and drainage device 404 is installed at the lower portion of the leakage collection conduit 402, and the leakage collection conduit 402 is connected to the interior of the leakage collection and drainage device 404 through a drainage port, and can collect the leakage water collected by the leakage collection conduit 402, and automatically drain the water and reset after the leakage water reaches a certain amount; The leakage collection and drainage device 404 is provided with a mechanical structure inside, which responds to the gravity changes of the water stored in the leakage collection and drainage device 404, and realizes the emptying of the stored water and reset after emptying the stored water through mechanical movement. Sensing optical fiber 405; The sensing optical fiber 405 passes through the leakage collection and drainage device 404 at the connection of each pipeline section in sequence along the water supply pipeline 401, but does not affect the water storage and drainage of the leakage collection and drainage device 404. Distributed optical fiber vibration sensing and demodulation equipment; Continuously monitors the vibration conditions of each position of the sensing optical fiber 405.

[0050] Please continue to refer to Figure 5 In this embodiment, the leakage collection and discharge device 404 includes a collection and detection body and a mechanical structure. The collection and detection body is a cavity-type structure. The upper end surface of the collection and detection body is provided with a water inlet 410, and the water inlet 410 is located directly below the drainage port. The sensing optical fiber 405 is arranged along the water supply pipe 401 and fixed in sequence at the bottom of each collection and detection body. At the same time, a drain port is provided at the bottom of the collection and detection body. A mechanical structure is provided at the position of the drain port. The mechanical structure controls the opening or closing of the drain port according to the gravity of the water stored in the collection and detection body. Specifically, the mechanical structure includes a baffle 409, a rotating shaft 408, and a counterweight 407. The rotating shaft 408 is installed on the collection and detection body to provide a fulcrum for the installation of the baffle 409. The middle part of the baffle 409 is installed on the rotating shaft 408 in an axial mounting manner. One side of the baffle 409 is located at the position of the drain port, and the other side of the baffle 409 is installed with a counterweight 407. Under normal conditions, baffles 409 are closed, allowing water to accumulate within the collection and detection bodies. When the water reaches a certain volume, the baffles 409 automatically open under the force of gravity, draining the water and returning to their original position. Optical sensing fibers 405 are sequentially affixed to the bottom of each collection and detection body, ensuring effective strain coupling. These fibers avoid the locations of baffles 409, shaft 408, and counterweight 407, ensuring they do not interfere with the water collection and drainage of the leakage collection and drainage device 404. The demodulation device, a distributed optical fiber strain sensor 406, continuously monitors the strain of the sensing cable.

[0051] When the water supply pipe 401 is actually used, the middle part of each section of the pipe is relatively reliable, and leakage usually first occurs at the pipe connection, which is manifested as a small flow of leakage. Figure 6 As shown, the specific steps include:

[0052] Step 2-1: Initially, there is no water in the collection and detection body, the sensing optical cable does not receive the strain caused by the water, and the baffle 409 is closed.

[0053] Step 2-2: The collection detection body continuously collects the leaked water arriving through the leakage collection conduit 402 , and the internal water storage amount and the strain applied to the sensing optical cable are gradually increased.

[0054] Step 2-3: When the volume of water in the collection and detection body exceeds a certain threshold, the mechanical device consisting of counterweight 407, shaft 408, and baffle 409, similar to a flap-type floor drain, activates. Baffle 409 opens, rapidly draining the water from the collection and detection body and rapidly reducing the strain applied to the sensing optical cable to zero. After the water is drained, counterweight 407, shaft 408, and baffle 409 automatically return to their initial state from step 2-1, and baffle 409 closes.

[0055] Step 2-4: Distributed fiber optic strain sensing and demodulation device 406 continuously monitors the strain of the sensing fiber cable, identifying the strain changes caused by water accumulation and drainage in steps 2-1 and 2-3, and locating the leak at the joint of water supply pipe 401. As the amount of water leakage increases, the time interval between steps 2-1 and 2-3 decreases, shortening the period of slow increase and rapid decrease in strain of sensing fiber 405 caused by water accumulation in the sensing fiber. Distributed fiber optic strain sensing and demodulation device 406 analyzes this periodic variation to assess the severity of the leak.

[0056] Although the above embodiments have been described in detail for the present invention, it should be understood by those skilled in the art that modifications or improvements can be made based on the contents disclosed in the present invention without departing from the spirit and scope of the present invention, and that these modifications and improvements are within the spirit and scope of the present invention.

Claims

1. A water leakage detection system for water pipe connections based on distributed optical fiber sensing, characterized in that: include: Fixing components; Leakage collection conduit; the leakage collection conduit is arranged outside the water supply pipe connection through a fixing component, the leakage collection conduit is arranged entirely or partially around the water supply pipe, and the leakage collection conduit is provided with a drainage port; Leakage collection and discharge device; the leakage collection and discharge device is installed at the lower part of the leakage collection conduit, and the leakage collection conduit is connected to the interior of the leakage collection and discharge device through a drainage port; Mechanical structure; the mechanical structure is arranged inside the leakage collection and discharge device, responding to the gravity change of the water stored in the leakage collection and discharge device, and realizing emptying the water and resetting the water after emptying the water through mechanical movement; Sensing fiber; The sensing optical fiber is connected to the leakage collection and discharge device and / or the mechanical structure, and the sensing optical fiber senses the mechanical movement generated when the mechanical structure is emptied of water and reset and / or the process of water accumulation and emptying in the leakage collection and discharge device; Demodulation equipment; the demodulation equipment receives the signal from the sensing optical fiber and determines whether there is a leak at the water supply pipe connection, the location of the leak and the severity of the leak based on the signal.

2. A water leakage detection system for water pipe connections based on distributed optical fiber sensing as claimed in claim 1, characterized in that: The demodulation device is a distributed optical fiber vibration sensing demodulation device, which senses the mechanical vibration excitation generated when the mechanical structure is emptied of water and reset.

3. The water leakage detection system for water pipe joints based on distributed optical fiber sensing according to claim 1, characterized in that: The demodulation device is a distributed optical fiber strain sensing demodulation device, which senses the strain excitation of the sensing optical fiber affected by the accumulated water when the leakage collection and discharge device accumulates water and drains the accumulated water.

4. The water leakage detection system for water pipe connections based on distributed optical fiber sensing according to claim 1, characterized in that: When the water stored in the leakage collection and discharge device reaches a set amount, the mechanical structure is activated to discharge the water in the leakage collection and discharge device. After the water in the leakage collection and discharge device is discharged, the mechanical structure is reset.

5. The water leakage detection system for water pipe connections based on distributed optical fiber sensing according to claim 1, characterized in that: The leakage collection and discharge device is located directly below the connection point of the water supply pipe.

6. A method for detecting water leakage at a water pipe connection based on distributed optical fiber sensing, using the water pipe connection water leakage detection system according to any one of claims 1 to 5, characterized in that: The following steps are involved: Step 1: In the initial state, there is no water in the leakage collection and discharge device, and no signal is input to the sensing optical fiber; Step 2: The leakage collection and discharge device continuously collects the leaked water arriving through the leakage collection conduit, and the sensing optical fiber begins to receive signals; Step 3: When the water in the leakage collection and drainage device accumulates to a certain volume and the water gravity exceeds a preset threshold, the mechanical structure automatically starts to drain the water. The mechanical structure then resets to its initial state, and the sensing fiber receives the target signal. Step 4: The demodulation device identifies, locates, and analyzes the target signal received by the sensing optical fiber in step 2 and / or step 3 to determine whether leakage occurs, the location of leakage, and the severity of leakage.

7. The method for detecting water leakage at a water pipe connection based on distributed optical fiber sensing according to claim 6, characterized in that: In the step three, the target signal is a characteristic vibration signal.

8. The method for detecting water leakage at a water pipe connection based on distributed optical fiber sensing according to claim 6, characterized in that: In steps 2 and 3, the target signal is the strain signal generated by water accumulation.

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