JP2016095265A - Leakage detection method and leakage detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a leakage detection method and a leakage detection device that are capable of easily responding to a change of a detection object, a change in vibration propagated through a pipe, and the like, and of highly accurately detecting leakage.SOLUTION: The leakage detection method for a pipe uses a housing including an internal space whose natural frequency is adjusted, and a detection unit arranged in the internal space of the housing. In the leakage detection method: the natural frequency of the internal space is adjusted so as to resonate with vibration generated in a pipe when a fluid leaks from the pipe; the natural frequency generated in the internal space is detected and vibration information is outputted using the detection unit; and it is determined, based on the outputted vibration information, whether or not the fluid leaks from the pipe.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a leak detection method and a leak detection device.

  In modern society, facilities such as water and sewage networks, high-pressure chemical pipelines such as gas and oil, high-speed railways, long-span bridges, skyscrapers, large passenger planes, and automobiles have been built and have become the foundation of a prosperous society. If these are damaged by natural disasters such as an unexpected earthquake disaster or a lifespan deterioration resulting in a serious accident, the impact on society will be great, and the economic loss will be great. The members used in the equipment are deteriorated such as damage, wear, rattling and the like according to the use time, and eventually become malfunctions such as damage. For this reason, great efforts are being made to develop technologies that transcend academic fields such as science, engineering, and sociology in order to ensure the safety and security of facilities. In particular, the development of non-destructive inspection technology, which is a low-cost and easy-to-operate inspection technology, has become important in order to prevent serious accidents due to equipment deterioration and damage. Inspection methods using non-destructive inspection techniques are often used to detect leaks in various pipes such as water leaks in water and sewer networks and gas leaks in gas pipes.

  This non-destructive inspection method installs vibration sensors on the ground surface and manholes near pipes and places that come into contact with pipes (for example, places where pipes are buried), and from the vibration that propagates to this vibration sensor, pipes This inspection method detects pipe leaks by detecting vibrations (vibrations caused by pipe leaks) that were not seen during burial. Various techniques for improving the inspection accuracy of the nondestructive inspection method have been proposed so far.

  For example, in Patent Document 1, in a leakage sound detection device that detects water leakage, the detection unit and a pedestal unit are connected via a mechanical resonance member made of a soft material to eliminate extraneous noise and to reduce sensitivity in low-frequency components. A technique for realizing the efficiency of water leakage detection by increasing the value is described.

JP-A-6-281530

  The leakage sound detection apparatus of Patent Document 1 increases the sensitivity in the low-frequency component of the vibration to be detected by connecting the detection unit and the pedestal unit via a mechanical resonance member made of a soft material. Therefore, when the detection target is changed or when the spectrum of the propagation sound propagating through the pipe changes, the mechanical resonance member is selected again according to the change or change, and the mechanical resonance member of the current leakage sound detection device It is necessary to replace the leak detection device using the mechanical resonance member selected again or the current leak detection device.

  The present invention has been made in view of the above problems, and can easily detect a change in a detection target, a change in vibration propagating through a pipe, and the like, and can perform leak detection with high accuracy. It is an object to provide a method and a leak detection device.

  In order to achieve the above object, a leak detection apparatus according to the present invention is a leak detection apparatus for a pipe through which a fluid flows, and is internally resonated with vibration generated in the pipe when the fluid is leaking. A housing with the natural frequency of the space adjusted, and an internal space of the housing, which detects vibration generated in the pipe at the time of leakage and natural vibration generated in the internal space, and outputs vibration information A detection unit and a determination unit that determines whether or not fluid leaks from the pipe based on the output vibration information.

  In order to achieve the above object, a leak detection method in a leak detection apparatus according to the present invention includes a casing in which a natural frequency of an internal space is adjusted, and a pipe using a detection unit disposed in the internal space of the casing. The natural frequency of the internal space is adjusted so as to resonate with vibration generated in the pipe when a fluid leaks from the pipe, and the internal space is detected using the detection unit. It detects the natural vibration generated in step 1, outputs vibration information, and determines whether or not fluid is leaking from the pipe based on the output vibration information.

  ADVANTAGE OF THE INVENTION According to this invention, it can respond easily to the change of the detection target, the change of the vibration which propagates piping, etc., and can perform leak detection with high precision.

It is an example of the block diagram of the leak detection apparatus 100 which concerns on the 1st Embodiment of this invention. It is an example of the state which installed the leak detection apparatus 100 which concerns on the 1st Embodiment of this invention in infrastructure equipment. It is an example of height adjustment of the internal space of the resonance mechanism 103 by the frequency adjustment lever 104 which concerns on the 1st Embodiment of this invention. It is a flowchart which shows an example of the installation of each component of the leak detection apparatus 100 which concerns on the 1st Embodiment of this invention, and a setting process. It is a flowchart which shows an example of the leak detection process of the leak detection apparatus 100 which concerns on the 1st Embodiment of this invention. It is an example of the state which installed the leak detection apparatus 100 which concerns on the 2nd Embodiment of this invention in infrastructure facilities. It is an example of the block diagram of the leak detection apparatus 300 which concerns on the 3rd Embodiment of this invention. It is a flowchart which shows an example of the leak detection process of the leak detection apparatus 300 which concerns on the 3rd Embodiment of this invention. It is an example of the block diagram of the comparison method in verification experiment. It is an example of the block diagram of the method of this invention in a verification experiment. It is a graph which shows the experimental result of the comparison method in this verification experiment, and the method of this invention.

(First embodiment)
A first embodiment of the present invention will be described. FIG. 1 shows a configuration diagram of a leak detection apparatus 100 according to the present embodiment, and FIG. 2 shows an installation diagram when the leak detection apparatus 100 is installed in an infrastructure facility. The infrastructure facilities here are high-pressure chemical pipelines such as gas and oil, and water and sewage networks.

  As shown in FIG. 1, the leak detection apparatus 100 according to the present embodiment includes a detection unit 101, a structure 102, a resonance mechanism 103, a frequency adjustment lever 104, a calculation unit 105, and a wire 106. . As shown in FIG. 2, the leak detection device 100 according to the present embodiment detects a case where the fluid 108 is disposed in a pipe 107 through which the fluid 108 flows and a leak hole 109 is formed in the pipe 107.

  The detection unit 101 detects vibration generated due to the state of the pipe 107 or the fluid 108 via the structure 102. Then, when the detected vibration is vibrated by a sound wave, which will be described later, generated in the resonance mechanism 103, it is converted into an electrical signal and output to the calculation unit 105 through the wire 106 as vibration information. For the detection unit 101, a piezoelectric acceleration sensor, an electrodynamic acceleration sensor, a capacitance acceleration sensor, an optical speed sensor, a dynamic strain sensor, or the like is used.

  The structure 102 is installed to be attached to the pipe 107. When vibration generated due to the state of the pipe 107 or the fluid 108 propagates from the pipe 107, the structure 102 steadily vibrates at a specific frequency, and the vibration is reduced. Tell the detection unit 101. Further, when the structure 102 constantly vibrates at a specific frequency as described above, the structure 102 vibrates the surrounding medium and generates sound waves inside the resonance mechanism 103. In the present embodiment, the surrounding medium that the structure 102 vibrates is air.

  The resonance mechanism 103 is installed so as to surround the detection unit 101. When a sound wave is generated in the mechanism due to vibration of the structure 102, the sound wave is resonated and amplified. This is because the resonance frequency of the resonance mechanism 103 is matched with a leakage vibration band described later by the frequency adjustment lever 104. The resonance mechanism 103 propagates the amplified sound wave to the detection unit 101 through the medium in the mechanism, and vibrates the vibration detected by the detection unit 101. In the present embodiment, the medium in the resonance mechanism 103 is air.

  The frequency adjustment lever 104 adjusts the height of the internal space of the resonance mechanism 103 as shown in FIG. 3 so that the resonance frequency of the resonance mechanism 103 coincides with the leaky vibration band calculated by the calculation unit 105 described later. By adjusting the height of the internal space of the resonance mechanism 103 and matching the resonance frequency of the resonance mechanism 103 with the leakage vibration band as described above, sound waves generated in the resonance mechanism 103 due to vibration of the structure 102 are resonated and amplified. Is done. A detailed description of the height adjustment of the internal space of the resonance mechanism 103 will be described later.

  The calculation unit 105 is connected to the detection unit 101 via the wire 106 and detects the leakage of the fluid 108 from the pipe 107 by frequency-converting and analyzing the vibration information output from the detection unit 101. When the fluid 108 leaks from the pipe 107, the vibration frequency component in a specific range corresponding to the natural frequency of the structure 102 exhibits a larger amplitude than when the fluid 108 does not leak from the pipe 107 in a normal state. The calculation unit 105 detects leakage of the fluid 108 in the pipe 107 using this characteristic. Further, the calculation unit 105 calculates a leakage vibration band based on the vibration propagating through the pipe 107 in order to adjust the height of the internal space of the resonance mechanism 103. Specifically, a leak is caused in a pseudo manner, the detection unit 101 detects vibration, the time waveform of the detected vibration is subjected to frequency conversion, a frequency spectrum is obtained, and calculation is performed based on the obtained frequency spectrum. Note that the leakage vibration band can be calculated from the diameter, material, and structure of the structure 102 or experimentally.

  The wire 106 is a communication cable that connects the detection unit 101 and the calculation unit 105, and propagates vibration information output from the detection unit 11 to the calculation unit 105.

  The pipe 107 transports the fluid 108 and plays a role as a medium for propagating the vibration to the structure 102 when vibration caused by itself or the state of the fluid 108 occurs. The pipe 107 may be embedded in the ground, a wall of a building, or a pillar, or may be installed in the attic or underground of the building.

  The fluid 108 is a fluid such as gas, oil, or water that flows in the pipe 107.

  The leak hole 109 is a hole or crack generated in the pipe 107 and causes the fluid 108 to leak from the pipe 107.

  Next, the installation and setting process of each component of the leakage detection apparatus 100 according to the present embodiment will be described with reference to FIG. This step is performed before the leak detection device 100 starts leak detection.

  An arbitrary number of detectors 101 are installed in the structure 102 and / or the pipe 107 so as to detect vibrations caused by the state of the pipe 107 or the fluid 108 (S101). In addition, although installation of the detection part 101 can consider using a magnet, a special jig | tool, an adhesive agent, etc., the method is not specifically limited. Moreover, the detection part 101 may be permanently installed in the installation location, and may always detect a vibration, or it may be installed for a predetermined period and may detect a vibration intermittently.

  The resonance mechanism 103 is installed so as to surround the detection unit 101 (S102). The resonance mechanism 103 is preferably installed so as to seal the periphery of the detection unit 101. In order to seal, it is conceivable to use a dedicated jig or the like adapted to the resonance mechanism 103, but the method is not particularly limited. The shape of the resonance mechanism 103 is preferably a cube or a cylinder, but is not particularly limited.

  The calculation unit 105 is connected to the detection unit 101 and calculates a leakage vibration band based on the vibration propagating through the pipe 107 in order to adjust the height of the internal space of the resonance mechanism 103 (S103). Specifically, a pseudo leak occurs, the detection unit 101 detects vibration, and a frequency spectrum is obtained by frequency-transforming the detected time waveform of the vibration by Fourier transform or the like, and is calculated based on the obtained frequency spectrum. To do.

  Since the frequency adjustment lever 104 amplifies the sound wave generated in the resonance mechanism 103 due to the vibration of the structure 102, the height of the resonance mechanism 103 is adjusted so that the resonance frequency of the resonance mechanism 103 matches the leakage vibration band. (S104). Here, S104 is considered based on the equation c = fλ. Since c is the speed of sound in the air and is a constant of about 340 m / s, by changing the height of the internal space of the resonance mechanism 103 and controlling the wavelength in the height direction of the resonance mechanism 103, The resonance frequency f and the leakage vibration band can be matched.

  When S104 ends, the leak detection apparatus 100 completes preparations for performing leak detection. In detecting leakage, it is preferable to devise measures such as closing a manhole cover in order to prevent the influence of external disturbance vibration.

  Next, an operation example of leakage detection of the leakage detection device 100 according to the present embodiment will be described with reference to FIG.

  When vibration propagates from the pipe 107, the structure 102 steadily vibrates at a specific frequency and transmits the vibration to the detection unit 101. Further, when the structure 102 constantly vibrates at a unique frequency as described above, the structure 102 vibrates the surrounding medium and generates a sound wave in the resonance mechanism 103 (S201).

  The sound wave generated in the resonance mechanism 103 in S201 is resonated and amplified because its own frequency matches the resonance frequency of the resonance mechanism 103 (S202).

  The sound wave amplified in S202 is propagated to the detection unit 101 via the medium in the resonance mechanism 103, and vibrates the vibration detected by the detection unit 101 (S203).

  When the vibration detected in S203 is vibrated, the detection unit 101 converts the vibration into an electrical signal and outputs the signal as vibration information to the calculation unit 105 via the wire 106 (S204).

  The calculation unit 105 determines whether or not the fluid 108 is leaking through the pipe 107 by performing frequency conversion and analysis on the vibration information output from the detection unit 101 (S205).

  As described above, the leak detection apparatus 100 according to the present invention adjusts the resonance frequency of the resonance mechanism 103 with the frequency adjustment lever 104 so as to coincide with the leak vibration band. And the vibration which the detection part 101 detects is vibrated by installing the resonance mechanism 103 which adjusted the said resonance frequency so that the detection part 101 may be enclosed.

  Therefore, according to the first embodiment of the present invention, since the resonance frequency of the resonance mechanism 103 can be easily adjusted by the frequency adjustment lever 104, it can easily cope with a change in detection target, a change in propagation vibration, and the like. It becomes possible.

  In addition, according to the first embodiment of the present invention, the resonance mechanism 14 whose resonance frequency is adjusted so as to coincide with the leakage frequency band is installed so as to surround the detection unit 101, so that the amount of leakage is very small. Even if the vibration propagating to the detection unit 101 is very small due to the fact that the location of the leak is far away or the like, the vibration detected by the detection unit 101 is vibrated, so the leakage can be performed with high accuracy. Can be detected.

  In the leak detection device 100 according to the present embodiment, the resonance mechanism 103 that can change the height of the internal space by the frequency adjustment lever 104 is used. However, the present invention is not limited to this. For example, it is possible to prepare a plurality of resonance mechanisms having different heights and appropriately change them in accordance with the propagated vibration.

  Further, in the resonance mechanism 103 in the present embodiment, the natural frequency and the vibration frequency band coincide with each other, and the resonance mechanism 103 itself resonates, so that noise or the like may be added to the vibration detected by the detection unit 101. . In that case, if the natural frequency of the resonance mechanism 103 is known, noise or the like can be removed by subsequent processing.

  Moreover, although the frequency adjustment lever 104 in this embodiment changed the height of the resonance mechanism 103 and adjusted the resonance frequency of the resonance mechanism 103, it is not limited to this. For example, the resonance frequency may be adjusted by changing the lateral width of the resonance mechanism 103.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. FIG. 6 shows an installation diagram when the leak detection apparatus 100 according to the present embodiment is installed in infrastructure equipment. The configuration of the present embodiment is the same as the configuration of the first embodiment except that in the leak detection apparatus 100, the medium injection port 201 is attached to the upper part of the resonance mechanism 103 instead of the frequency adjustment lever 104. Note that description of portions having the same configurations and functions as those of the first embodiment is omitted.

  The medium injection port 201 is provided in the upper part of the resonance mechanism 103 and is used for injecting a medium into the resonance mechanism 103. The medium to be injected may be a gas such as oxygen, hydrogen or nitrogen, or a liquid such as water or an aqueous sodium chloride solution.

  Since the medium injection port 201 is provided as described above and the medium in the resonance mechanism 103 can be changed, the frequency of the sound wave generated in the resonance mechanism 103 can be adjusted. Considering based on the equation of c = fλ, the wavelength λ of the sound wave generated in the resonance mechanism 103 is invariant. Therefore, the sound wave frequency f is adjusted by changing the sound velocity c by changing the medium in the resonance mechanism 103. Is possible.

  As described above, the leak detection device 100 according to the second embodiment of the present invention has a resonance mechanism 103 in which the frequency of the sound wave generated in the resonance mechanism 103 matches the resonance frequency of the resonance mechanism 103. Change the medium. Therefore, according to the second embodiment of the present invention, the leak detection device 100 is installed in a place where the height of the resonance mechanism 103 cannot be controlled and the resonance frequency of the resonance mechanism 103 cannot be adjusted, for example, in a narrow manhole. Even in this case, the same effect as in the first embodiment can be obtained.

  In addition, in the leak detection apparatus 100 in the first embodiment and the second embodiment, the wire 106 is used to connect the detection unit 101 and the calculation unit 105. However, the present invention is not limited to this. For example, it is possible to connect by wireless.

(Third embodiment)
Next, a third embodiment of the present invention will be described. FIG. 7 shows a configuration diagram of a leak detection apparatus 300 according to the present embodiment. As shown in FIG. 7, the leak detection apparatus 300 according to the present embodiment includes a housing 301, a detection unit 302, and a determination unit 303.

  The case 301 is a case in which the natural frequency of the internal space is adjusted so as to resonate with vibration generated in the pipe when the fluid is leaking, and when the fluid leaks from the pipe, Resonates and vibrates (hereinafter referred to as natural vibration).

  The detection unit 302 is arranged in the internal space of the housing 301 and detects vibration information generated in the piping when fluid is leaking from the piping and natural vibration generated in the internal space of the housing to obtain vibration information. Output.

  The determination unit 303 determines whether fluid is leaking from the pipe based on the vibration information output from the detection unit 302.

  Next, an operation example of leak detection of the leak detection apparatus 300 according to the present embodiment will be described with reference to FIG.

  When the fluid leaks from the pipe, the casing 301 generates natural vibrations in its internal space (S301).

  The detection unit 302 detects vibration generated in the piping due to fluid leakage and natural vibration generated in the internal space of the housing in S301, and outputs vibration information to the determination unit 303 (S302).

  Based on the vibration information output from the detection unit 302, the determination unit 303 determines whether or not the fluid is leaking from the pipe (S303).

  In the leak detection device according to the present embodiment, the natural frequency of the internal space of the housing is adjusted so as to resonate with the vibration generated in the pipe when the fluid is leaking. It is possible to easily cope with a change in vibration propagating through the. When a fluid leak occurs, the natural vibration of the casing is added to the vibration generated in the pipe, so that the leak detection can be performed with high accuracy.

  The leak detection device 100 in the first embodiment and the second embodiment and the leak detection device 300 in the third embodiment are a CPU, a memory, and a program (leakage device) stored in the memory of an arbitrary computer. In addition to programs stored in memory from 10 shipping stages, including programs downloaded from storage media such as CDs and servers on the Internet), storage units such as hard disks for storing the programs, network connection It is realized by any combination of hardware and software such as an interface. It will be understood by those skilled in the art that there are various modifications to the implementation method and apparatus.

(Verification experiment)
Next, as described in the first embodiment (FIG. 2) and the second embodiment (FIG. 6), when the resonance mechanism 103 is installed so as to surround the detection unit 101, the leak detection of the leak detection device 100 is detected. A verification experiment for verifying whether or not the accuracy of the test is improved will be described.

  Specifically, in this verification experiment, when the resonance mechanism 103 is not installed as shown in FIG. 9 (hereinafter referred to as a comparison method), the resonance mechanism 103 is surrounded by the detection unit 101 as shown in FIG. The effect of the present invention is verified by comparing the frequency spectrum of the vibration propagating through the pipe 107 obtained by the calculation unit 105 in the case where it is installed (hereinafter referred to as the method of the present invention). Note that the resonance frequency of the resonance mechanism 103 according to the present invention and the vibration frequency band of the vibration propagating through the pipe 107 coincide.

  In this verification experiment, a piezoelectric vibration sensor (corresponding to the detection unit 101) is installed in a single-mouthed fire hydrant, a steel pipe having a diameter of 1000 mm is used for the pipe 107, water is used for the fluid 108, and the leak hole 109 is a fire hydrant. The test was performed under the condition that the hole had a diameter of 2 mm generated at a location 100 m away from the installation position (corresponding to the installation position of the leak detection device 100).

  FIG. 11 shows a frequency spectrum of vibration obtained by the calculation unit 105 when leakage detection is performed using the above two methods. Note that the frequency spectrum 401 in FIG. 11 represents the frequency spectrum obtained by the comparison method, and the frequency spectrum 402 represents the frequency spectrum obtained by the method of the present invention.

  From FIG. 11, it can be seen that the method of the present invention effectively enhances the frequency spectrum of vibration and can detect leakage with higher accuracy than the comparative method.

  From the above, as shown in FIGS. 2 and 6, the resonance mechanism 103 is installed so as to surround the detection unit 101, and the structure 102 is configured to vibrate the vibration of the structure 102. The accuracy of leak detection can be improved.

100 Leakage Detection Device 101 Detection Unit 102 Structure 103 Resonance Mechanism 104 Frequency Adjustment Lever 105 Calculation Unit 106 Wired 107 Pipe 108 Fluid 109 Leakage Hole 201 Medium Injection Port 300 Leakage Detection Device 301 Housing 302 Detection Unit 303 Determination Unit 401 By Comparison Method Obtained frequency spectrum 402 Frequency spectrum obtained by the method of the present invention

Claims (5)

A leak detection device for piping in which a fluid flows,
A housing in which the natural frequency of the internal space is adjusted so as to resonate with vibration generated in the pipe when the fluid is leaking;
A detection unit that is arranged in the internal space of the housing and detects vibration generated in the pipe at the time of leakage and natural vibration generated in the internal space, and outputs vibration information;
A determination unit that determines whether or not fluid leaks from the pipe based on the output vibration information;
A leak detection device comprising: A structure that is attached to the pipe and that has a natural frequency when vibration due to fluid leakage occurs in the pipe;
The natural frequency of the internal space is adjusted so that the internal space of the housing resonates with the vibration of the structure.
The leak detection device according to claim 1. The leak detection device according to claim 1, wherein the natural frequency of the internal space is adjusted to resonate with vibration generated in the pipe by adjusting a volume of the internal space of the housing. The leak detection device according to claim 1 or 2, wherein the natural frequency of the internal space is adjusted to resonate with vibration generated in the pipe by filling a predetermined medium in the internal space of the housing. A leak detection method for a pipe using a casing in which the natural frequency of the inner space is adjusted and a detector disposed in the inner space of the casing,
Adjusting the natural frequency of the internal space so as to resonate with vibration generated in the pipe when fluid is leaking from the pipe;
Using the detection unit, the natural vibration generated in the internal space is detected and vibration information is output,
A leakage detection method for determining whether or not fluid is leaking from the pipe based on the output vibration information.

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