Method for detecting leakage

Abstract

To provide a leakage detector for automatically detecting leakage of fluid from a buried tank or from a pipe.SOLUTION: A part of an oil injection pipe 11 which is buried in the ground is a double pipe 30 including a first pipe 31 used as the oil injection pipe and a second pipe 32 covering the first pipe 31. There is a detection sensor 15 for detecting leakage of an organic solvent between the first pipe 31 and the second pipe 32. The detection sensor 15 is connected to a leakage detector 21 of a leakage detector disc 20 through a lead wire 25. With the structure, the leakage detector 21 detects leakage of an organic solvent by the detection sensor 15 when the organic solvent is leaking from the first pipe 31, and causes a buzzer 22 to make sound so that a person in charge can know the leakage.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a leak detection method. [Background technology]

[0002] Some liquids stored in buried tanks or fluids flowing through pipes are considered to be hazardous. Any leakage of hazardous fluids from buried tanks or structures such as pipes, even if only slightly, requires immediate action. In order to detect leakage of such fluids, for example, organic solvents, an organic solvent leakage detection device having an organic solvent leakage detection agent applied to it in a uniform thickness is attached to a buried tank, a pipe, or the like (see, for example, Patent Document 1).

[0003] With this organic solvent leakage detector, it is easy to visually check whether or not an organic solvent is leaking by the presence or absence of color development. However, the reality is that it is difficult to immediately respond to an organic solvent leakage by human visual inspection. This is because having someone constantly stationed to check for leakage is undesirable in terms of costs, etc. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2001-318020 A Summary of the Invention [Problem to be solved by the invention]

[0005] SUMMARY OF THE PRESENT EMBODIMENT The present invention proposes a leakage detection device for automatically detecting leakage of fluid from buried tanks or piping. [Means for solving the problem]

[0006] A leak detection device of one embodiment of the present disclosure forms a first layer and a second layer from inside a structure in which a fluid is stored or flowed so that the fluid does not leak, and places a detection sensor for detecting the fluid between the first layer and the second layer, and detects the fluid leaking from the first layer using the detection sensor. Effect of the Invention

[0007] The present invention can automatically detect leakage of fluid from buried tanks or piping. [Brief description of the drawings]

[0008] [Figure 1] 1A to 1C are diagrams illustrating an application example of a leak detection method according to an embodiment of the present invention. [Diagram 2] 11A to 11C are diagrams illustrating an application example of a leakage detection method according to another embodiment of the present invention. [Diagram 3] 10A and 10B are diagrams illustrating an example of the structure of the inner surface layer at the location where the detection sensor is disposed. [Figure 4] FIG. 2 is a diagram illustrating an example of a method for connecting hollow glass fibers. [Diagram 5] FIG. 2 is a diagram illustrating an example of the structure of an inner surface layer at the end portion of a hollow glass fiber. [Figure 6] 11A to 11C are diagrams illustrating examples of the structure of a through-portion through which a detection sensor penetrates an inner surface layer. [Figure 7] FIG. 13 is a diagram illustrating an example of a connection portion. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. It should be noted that the embodiment described below, including modified examples, is merely an example, and the technical scope of the present invention is not limited to this example. Various modified examples are also included in the technical scope of the present invention.

[0010] FIG. 1 is a diagram for explaining an application example of a leak detection method according to an embodiment of the present invention. The application example shown in FIG. 1 is for detecting leakage in piping for injecting fluid into an underground tank buried underground or for sucking fluid from the underground tank. The fluid is considered to be a hazardous material. Here, the fluid is assumed to be an organic solvent such as toluene or methylcyclohexane, and hereafter referred to as an organic solvent. The pipe for detecting leakage is assumed to be an oil filling pipe.

[0011] Toluene is an organic compound that belongs to aromatic hydrocarbons, with one of the hydrogen atoms of benzene replaced with a methyl group. It is a colorless, transparent liquid that is volatile at room temperature, flammable, has an anesthetic effect on the human body, and is highly toxic. Methylcyclohexane is produced by hydrogenating toluene, and hydrogen can be extracted by dehydrogenation using a catalyst. Therefore, research is being conducted on it as a type of organic hydride and a means of stable storage and transportation of hydrogen. It is less toxic than toluene. It is expected that such organic solvents will be widely used at hydrogen stations, etc. Due to the toxicity of such organic solvents and the background behind them, it is considered important to be able to detect organic solvent leaks reliably and early. For this reason, we will assume that the fluid in this paper is an organic solvent.

[0012] 1 denotes a manhole. The oil filling pipe 11 is buried underground from the middle and is exposed from underground through the manhole 41. It is difficult to visually detect the leakage of organic solvent from the part of the oil filling pipe 11 buried underground. For this reason, this example is applied to enable automatic detection of leakage occurring in the portion of the oil supply pipe 11 buried underground. For this purpose, the portion of the oil supply pipe 11 buried underground is connected to the oil supply pipe 11 by welding or the like, and forms a double pipe 30 having a first pipe 31 (first layer) used as the oil supply pipe, and a second pipe 32 (second layer) covering the first pipe 31.

[0013] The oil supply pipe 11 and the double piping 30 are connected inside the connection box 10. The oil supply pipe 11 is connected to the first pipe 31 via a flange 12. Another flange 42 exists inside the manhole 41, and the double piping 30 is formed between these two flanges 12, 42.

[0014] The connection box 10 is also provided with a pipe 13 into which a lead wire 25 and a detection sensor 15 for detecting leakage are inserted. The detection sensor 15 is, for example, a sensor cable whose capacitance changes depending on an organic solvent. A sealant 14 is provided to prevent water or the like from entering the pipe 13.

[0015] The detection sensor 15 is inserted between the first pipe 31 and the second pipe 32 of the double piping 30, from the flange 12 to the flange 42. This causes the capacitance of the detection sensor 15 to change when a leak occurs in any of the first pipes 31.

[0016] The lead wire 25 is connected to the leak detector panel 20. More specifically, it is connected to the safety barrier 23. The leak detector panel 20 is for automatically detecting leaks that occur in the first pipe 31, and for notifying the user when a leak is detected. For this purpose, it is equipped with a leak detector 21 and a buzzer 22.

[0017] The leak detection device 21 detects, for example, a change in capacitance of the detection sensor 15 as a change in voltage value via the lead wire 25, and identifies the presence or absence of leakage in the first pipe 31 from the detected voltage value. For this purpose, the leak detection device 21 is connected to a DC (Direct Current) terminal 24 to which a direct current voltage is applied, and is also grounded. The presence or absence of leakage is identified by, for example, comparing the detected voltage value with a threshold value determined for each type of organic solvent.

[0018] When the leak detection device 21 determines that a leak has occurred, it notifies the person in charge by sounding the buzzer 22. This enables the person in charge to immediately respond to the organic solvent leak. By responding immediately, it becomes possible to minimize damage caused by the leak.

[0019] In this manner, in this example, the piping portion where leakage should be detected is made into a double pipe 30, and the detection sensor 15 is disposed between the first pipe 31 and the second pipe 32 in the double pipe 30. Thereby, the detection sensor 15 is used to automatically detect leakage occurring in the first pipe 31. Therefore, even if the pipe or a part of it is buried underground, it is possible to automatically detect leakage. When leakage is detected, the buzzer 22 sounds, so that the person in charge can immediately recognize the leakage, which makes it easier to minimize the amount of leaked organic solvent. This also makes it possible to minimize damage caused by the leaked organic solvent.

[0020] Even if damage such as a hole or a crack occurs in the first pipe 31, it does not necessarily mean that damage such as a hole or a crack will also occur in the second pipe 32. Even if damage occurs in the second pipe 32, the amount of organic solvent leaking from the second pipe 32 will be smaller than the amount of organic solvent leaking from the first pipe 31. This also makes it possible to further reduce damage caused by the leakage of organic solvent.

[0021] The type of detection sensor 15 that detects leakage is not particularly limited. The reason why the detection sensor 15 that is a sensor cable is adopted is that it can be easily adapted even if the length of the double pipe 30 is long. The type of detection sensor 15 may be changed depending on the length or area where leakage needs to be detected. Since the outer second pipe 32 only needs to cover the entire first pipe 31, it may be a member that is attached after the first pipe 31 is connected by welding or the like.

[0022] FIG. 2 is a diagram illustrating an application example of a leakage detection method according to another embodiment of the present invention. The application example shown in Figure 2 is for detecting the leakage of organic solvents stored in underground tanks buried underground. In Figure 2, the same or basically the same parts as in Figure 1 are given the same reference numerals.

[0023] In this example, the leak detector panel 20 and the connection hole 41 are connected by a pipe 61, and a lead wire 25 is passed through the pipe 61. In addition, the underground tank 50 has a multi-layered inner layer 52 (first layer) formed on the inner surface of the steel plate 51 (second layer). The detection sensor (sensor cable) 15 is disposed between the inner surface layer 52 and the steel plate 51. The detection sensor 15 is disposed between points A and B in FIG. 2. Therefore, it is sufficient that the inner surface layer 52 is formed at least between points A and B. The detection sensor 15 and the lead wire 25 are connected at a connection portion 45.

[0024] 3 is a diagram for explaining an example of the structure of the inner surface layer at the location where the detection sensor is disposed. Note that this example of the structure of the inner surface layer 52 is just one example, and it is sufficient if the organic solvent stored in the underground tank 50 does not leak unless a malfunction occurs.

[0025] 3, in this example, hollow glass fiber 501 is attached to the inner surface of a steel plate 51. The detection sensor 15 is disposed in a gap where the hollow glass fiber 501 does not exist. A part of the detection sensor 15 is inserted into a split tube 510 and is protected. The split tube 510 into which the detection sensor 15 is inserted is higher (thicker) than the hollow glass fiber 501. For this reason, oil-resistant double-sided tape 502 is attached to the hollow glass fiber 501 adjacent to the split tube 510, and adhesive-treated PET film 504 is attached to the two double-sided tapes 502.

[0026] Putty 503 is applied to the side of double-sided tape 502 opposite to the side facing split tube 510. The outside of inner surface layer 52, i.e., the side that comes into contact with organic solvent, is entirely covered with, for example, ultraviolet-curing type FRP (fiber reinforced plastic) 505. This FRP 505 corresponds to inner surface layer 52 in the narrow sense.

[0027] Fig. 4 is a diagram for explaining an example of a method for connecting hollow glass fibers, and Fig. 5 is a diagram for explaining an example of the structure of the inner surface layer at the end portion of a hollow glass fiber. 4, two hollow glass fibers 501 are connected by attaching a PET film 504 to them. The ends of the hollow glass fibers 501 are coated with putty 503 as shown in FIG.

[0028] FIG. 6 is a diagram illustrating an example of the structure of a penetration portion where a detection sensor penetrates into an inner surface layer. As shown in FIG. 6, at this penetration portion, a split tube 510 in which a detection sensor 15 is inserted penetrates the FRP 505. The FRP 505 is actually formed (for example, pasted) after arranging the detection sensor 15 including the split tube 510. Putty 503 is applied so that the detection sensor 15 including the split tube 510 is stable. The gaps between the FRP 505 and the split tube 510, between the detection sensor 15 and the split tube 510, and between the detection sensor 15 and the split tube 510 are sealed with a sealing material (not shown). In this way, no leakage will occur in the inner surface layer 52 unless a hole or crack occurs in the FRP 505.

[0029] FIG. 7 is a diagram illustrating an example of a connection portion. A plurality of pipes 71 to 73 are connected to the connection portion 45. Both ends of the detection sensor 15 are connected to connectors 74. Lead wires 25 are connected to each connector 74. One of the two connectors 74 is a switching connector 74, to which a communication line 75 is connected in addition to the lead wires 25.

[0030] In this example, similarly to the double piping 30, the leak detection device 21 of the leak detector panel 20 can automatically detect a leak that occurs in the inner surface layer 52 of the underground tank 50. It can be presumed that the occurrence of a leak in the inner surface layer 52 is due to a physical force acting on the steel plate 51, or due to deterioration of the steel plate 51 due to rust or the like. Therefore, the occurrence of a leak in the inner surface layer 52 can be considered to indicate that a leak has occurred from the steel plate 51, or that there is a high possibility that a leak will occur. This embodiment makes it possible to deal with such leakage more reliably at an earlier stage. The inner surface layer 52 functions to reduce the amount of organic solvent leaking from the underground tank 50 even if the steel plate 51 is damaged and the organic solvent leaks from the steel plate 51.

[0031] In this example, it is assumed that a leak in an already existing underground tank 50 is to be detected, but the underground tank 50 may be one that is to be buried in the future. In that case, the detection sensor 15 may be disposed between the steel plate 51 and an outer surface layer formed on the outside of the steel plate 51. [Explanation of symbols]

[0032] 10 connection box, 11 oil filling pipe, 15 detection sensor, 20 leak detector panel, 21 leak detector, 22 buzzer, 25 lead wire, 30 double piping, 31 first pipe, 32 second pipe, 50 underground tank, 51 steel plate, 52 inner surface layer, 505 FRP.

Claims

1. A first layer and a second layer are formed inside a structure in which an organic solvent is stored or flowed, so that the organic solvent does not leak, a detection sensor for detecting the organic solvent is disposed between the first layer and the second layer; A leakage detection method for detecting the organic solvent leaking from the first layer by the detection sensor, comprising: A leak detection method characterized in that hollow glass fibers are attached to the inner surface of the first layer, the detection sensor is placed in a gap where the hollow glass fibers are not present, the detection sensor is inserted into and protected by a separate tube, and the separate tube into which the detection sensor is inserted is formed thicker and higher than the hollow glass fibers.

2. The leak detection method according to claim 1 , wherein the structure is a double pipe having the first layer and the second layer.

3. 2. The leak detection method according to claim 1, wherein the structure is an underground tank buried underground and including the first layer and the second layer.

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