Leak detection devices used in double piping and double-shell structures of buried tanks

Abstract

A leak detection device for automatically detecting fluid leakage from a buried tank or piping is provided. [Solution] The portion of the oil supply pipe (11) that is buried underground is a double pipe (30) that includes a first pipe (31) used as the oil supply pipe and a second pipe (32) that covers the first pipe (31). A detection sensor (15) for detecting organic solvent leaks is placed between the first pipe (31) and the second pipe (32). The detection sensor (15) is connected to a leak detection device (21) on a leak detection panel (20) via a lead wire (25). As a result, when an organic solvent leaks from the first pipe (31), the leak detection device (21) detects the leak using the detection sensor (15) and emits a buzzer (22) to notify the person in charge of the organic solvent leak.

Description

[Technical Field]

[0001] The present invention relates to buried tanks and underground piping that store oils such as gasoline and organic solvents, and to double-shell structures of buried tanks, and in particular to a leak detection device used in double piping and double-shell structures of buried tanks that detects oil leaks and organic solvent leaks, automatically reports oil leaks, etc., and enables prompt maintenance. [Background technology]

[0002] Some liquids stored in buried tanks or fluids flowing through pipes are considered hazardous materials. Even a small leak of a hazardous fluid from a buried tank or pipe or other structure requires immediate action. For this reason, in order to detect leaks of such fluids, a leak detection device with a leak detection agent applied to it in a uniform thickness is attached to buried tanks, pipes, etc. (see, for example, Patent Document 1).

[0003] This leak detector allows easy visual confirmation of, for example, an organic solvent leak based on the presence or absence of color development. However, the reality is that it is difficult to immediately respond to gasoline or organic solvent leaks using human visual inspection alone. Furthermore, having someone constantly on hand to check for leaks is undesirable from a cost perspective, etc. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-318020 Summary of the Invention [Problem to be solved by the invention]

[0005] SUMMARY OF THE INVENTION The present invention proposes a leak detection device for automatically detecting leaks of oils such as gasoline, organic solvents, etc. from buried tanks and pipes. [Means for solving the problem]

[0006] One embodiment of the leak detection device of the present disclosure is a pipe or tank buried underground, and forms a first layer and a second layer from inside the structure in which a fluid is stored or flowed so that the fluid does not leak, and a detection sensor for detecting the fluid is placed between the first layer and the second layer, and the detection sensor detects the fluid leaking from the first layer. [Effects of the Invention]

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

[0008] [Figure 1] 1 is a diagram illustrating an application example of a leak detection device according to an embodiment of the present invention. [Figure 2] FIG. [Figure 3] 2. (a) is a cross-sectional view of the above-mentioned piping (cross-sectional view taken along line BB in FIG. 2), and (b) is an enlarged view of the dotted circled portion A in FIG. 2(a). [Figure 4] FIG. 10 is a diagram showing the structure of a pipe that leads the detection sensor to the outside. [Figure 5] 10A and 10B are diagrams illustrating an application example of a leak detection device according to another embodiment of the present invention. [Figure 6] FIG. 2 is a diagram showing the cross-sectional structure of an underground tank. [Figure 7] 10A and 10B are diagrams illustrating an example of the structure of the inner surface layer at the location where the detection sensor is arranged. [Figure 8] 1A to 1C are diagrams illustrating an example of a method for connecting hollow glass fibers. [Figure 9] 1A and 1B are diagrams illustrating examples of the structure of the inner surface layer at the end portion of a hollow glass fiber. [Figure 10] 10A and 10B are diagrams illustrating an example of the structure of a penetration portion through which a detection sensor penetrates an inner surface layer. [Figure 11] FIG. 10 is a diagram illustrating an example of a connection portion. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The embodiment described below is merely an example, including modifications, and the technical scope of the present invention is not limited to this example. The technical scope of the present invention also includes various modifications.

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

[0011] It is expected that organic solvents will be widely used at hydrogen stations, etc. Given the toxicity of organic solvents and the background to their occurrence, it is considered important to be able to reliably detect organic solvent leaks as early as possible.

[0012] In Figure 1, 41 is an inspection hatch for the buried tank. The oil filling pipe 11 is exposed from underground through the inspection hatch 41 installed at the top of the buried tank. It is difficult to visually detect leaks of gasoline or organic solvents in the part of the oil filling pipe 11 that is buried underground. For this reason, this example is applied to enable automatic detection of leaks that occur in the portion of the oil filling pipe 11 that is buried underground. For this purpose, the portion of the oil filling pipe 11 that is buried underground is connected to the oil filling pipe 11 by welding or the like, and is a double pipe 30 that has a first pipe 31 (first layer) that is used as the oil filling pipe, and a second pipe 32 (second layer) that covers 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 inspection hatch 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 a sensor cable whose capacitance changes depending on, for example, an organic solvent. A seal 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 (primary pipe) 31 and the second pipe (secondary pipe) 32 of the double pipe 30, from the flange 12 to the flange 42. This causes the capacitance of the detection sensor 15 to change if a leak occurs in any of the first pipes 31.

[0016] 2 is a perspective view of the double pipe 30. As shown in the figure, the double pipe 30 has a primary pipe 31 made of resin covered by a secondary pipe 32 made of the same resin, and a gap 9 of a predetermined width is formed between the primary pipe 31 and the secondary pipe 32. The detection sensor 15 described above is disposed in this gap 9. Note that the primary pipe 31 and the secondary pipe 32 are not limited to being made of thermoplastic resin such as polyethylene or polyamide, but may also be made of thermosetting resin such as phenolic resin or epoxy resin.

[0017] Fig. 3(a) is a cross-sectional view of the piping 30 (cross-sectional view taken along line BB in Fig. 2), and Fig. 3(b) is an enlarged view of the dotted circled area A in Fig. 3(a). As described above, the double piping 30 has a double structure, with the secondary piping 32 covering the primary piping 31. Furthermore, as shown in Figs. 3(a) and 3(b), the detection sensor 15 is disposed in the gap 9 between the primary piping 31 and the secondary piping 32 to detect leakage from the primary piping 31.

[0018] This detection sensor 15 is disposed linearly on the lower surface of the primary pipe 31 (on the upper surface of the secondary pipe 32). Therefore, even if toluene, for example, flowing inside the primary pipe 31, leaks from a defect formed in the primary pipe 31, the leaked toluene flows down along the outer surface of the primary pipe 31 and can be reliably detected by the detection sensor 15. Furthermore, the secondary pipe 32 acts as a receiver, preventing leaked substances such as toluene and alcohol from flowing outside and contaminating the soil.

[0019] Figure 4 shows the structure of the piping that takes out the above-mentioned detection sensor 15 to the outside. This double piping 30 is basically a double piping structure consisting of the above-mentioned primary piping 31 and secondary piping 32, but it is provided with a wiring outlet 1 that takes out the detection sensor 15 to the outside, and the detection sensor 15 is taken out to the outside of the double piping 30 from the wiring outlet 1 via an outlet pipe 2.

[0020] In addition, the double pipe 30 (e.g., double pipe 3) shown in the same figure is connected to the front and back of the aforementioned normal double pipe 30 (e.g., double pipe 4), and these double pipes 3 and 4 are connected in multiple numbers, and the above-mentioned detection sensor 15 is wired through all the double pipes.

[0021] By wiring the detection sensor 15 in a straight line along the underside of the double pipe 30 in this way, even if a leak occurs from a defective part of the pipe, the detection sensor 15 can reliably detect the leak and notify the oil leak detection monitor via the cable.

[0022] Specifically, the detection sensor 15 is connected to the safety barrier 23 via a lead wire 25. The leak detector panel 20 is designed to automatically detect leaks that occur in the first pipe 31 and to notify the user when a leak is detected. For this purpose, it is equipped with a leak detection device 21 and a buzzer 22.

[0023] The leak detection device 21 detects, for example, a change in capacitance of the detection sensor 15 as a change in voltage value via a lead wire 25, and determines whether or not a leak has occurred 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 a leak is determined by, for example, comparing the detected voltage value with a threshold value determined for each type of organic solvent.

[0024] When the leak detection device 21 determines that a leak has occurred, it sounds a buzzer 22 to notify the person in charge, allowing the person in charge to immediately respond to the organic solvent leak. By responding immediately, it is possible to minimize damage caused by the leak.

[0025] In this way, in this example, the piping portion where leak detection is required is double piping 30, and detection sensor 15 is placed between first pipe 31 and second pipe 32 in double piping 30. Thus, detection sensor 15 is used to automatically detect leaks that occur in first pipe 31.

[0026] Therefore, even if the pipe or a part of it is buried underground, where it is difficult to see, it is possible to automatically detect a leak. Furthermore, when a leak is detected, the buzzer 22 sounds, allowing the person in charge to immediately become aware of the fact, making it easier to minimize the amount of leaked organic solvent. This also minimizes damage caused by the leaked organic solvent.

[0027] Even if damage such as a hole or crack occurs in the first pipe 31, it does not necessarily mean that damage such as a hole or 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, etc., caused by leakage of the organic solvent.

[0028] The type of detection sensor 15 that detects leaks is not particularly limited. The reason why the detection sensor 15 that is a sensor cable is used is because 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 leaks need to be detected. The outer second pipe 32 only needs to cover the entire first pipe 31, so it may be a component that is attached after the first pipe 31 is connected by welding or the like.

[0029] FIG. 5 is a diagram illustrating an application example of a leak detection method according to another embodiment of the present invention. The application example shown in Figure 5 is for detecting the leakage of organic solvents stored in underground tanks buried underground. In Figure 5, the same or essentially the same components as those in Figure 1 are given the same reference numerals.

[0030] 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. 5. 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 part 45.

[0031] Fig. 6 is a diagram showing the cross-sectional configuration of the underground tank 1, and is a diagram showing the DD' cross section of the underground tank 1 shown in Fig. 5. As shown in the figure, the underground tank 1 is composed of an inner surface layer 52 and a steel plate 51, and hollow glass fibers are arranged in the gap between the inner surface layer 52 and the steel plate 51. These hollow glass fibers are arranged so as to avoid the wiring of the conductors described below. 7 is a diagram illustrating an example of the structure of the inner surface layer where the detection sensor is located. 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.

[0032] 7, in this example, hollow glass fiber 501 is attached to the inner surface of steel plate 51. Detection sensor 15 is placed in a gap where hollow glass fiber 501 does not exist. A part of detection sensor 15 is inserted into and protected by a split tube 510. 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 PET film 504 is attached to the two double-sided tapes 502.

[0033] 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.

[0034] Fig. 8 is a diagram illustrating an example of a method for connecting hollow glass fibers, and Fig. 9 is a diagram illustrating an example of the structure of the inner surface layer at the end of a hollow glass fiber. 8, two hollow glass fibers 501 are connected by attaching a PET film 504 to them. Putty 503 is applied to the ends of the hollow glass fibers 501, as shown in FIG.

[0035] FIG. 10 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. 10, at this penetration portion, a divided tube 510 into which a detection sensor 15 is inserted penetrates the FRP 505. In practice, the FRP 505 is formed (for example, attached) after arranging the detection sensor 15 including the divided tube 510. Putty 503 is applied to stabilize the detection sensor 15 including the divided tube 510. The gaps between the FRP 505 and the divided tube 510, between the detection sensor 15 and the divided tube 510, and between the detection sensor 15 and the divided tube 510 are sealed with a sealing material (not shown). In this way, no leakage occurs in the inner surface layer 52 unless a hole or crack occurs in the FRP 505.

[0036] FIG. 11 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, respectively. 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.

[0037] In this example, as with the double piping 30, the leak detection device 21 of the leak detector panel 20 can automatically detect leaks that occur in the inner surface layer 52 of the underground tank 50. It can be assumed 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 the influence of 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 is occurring from the steel plate 51 or that there is a high risk of a leak occurring. This embodiment makes it possible to deal with such a leak 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.

[0038] 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 thereof. [Explanation of symbols]

[0039] 1 Wiring extraction part, 2 Extraction pipe, 3 Piping, 4 Piping, 7 Gap, 9 Gap, 10 Connection box, 11 Oil filling pipe, 15 Detection sensor, 20 Leak detection panel, 21 Leak detection device, 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. It is a pipe buried underground, forming a first layer and a second layer from inside a structure in which a fluid is stored or flowed so as to prevent the fluid from leaking; a detection sensor for detecting the fluid is disposed between the first layer and the second layer; A leakage detection device that detects the fluid leaking from the first layer using the detection sensor.

2. It is a tank buried underground, forming a first layer and a second layer from inside a structure in which a fluid is stored or flowed so as to prevent the fluid from leaking; a detection sensor for detecting the fluid is disposed between the first layer and the second layer; A leakage detection device that detects the fluid leaking from the first layer using the detection sensor.

3. 3. The leak detection device according to claim 1, wherein the fluid is an organic solvent.

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

5. 3. The leak detection device 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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