JP5902429B2 - Leakage inspection for buried pipelines Gas mixing device, leakage inspection method for buried pipelines - Google Patents

Description

  The present invention relates to a leakage inspection gas mixing device for buried pipelines and a leakage inspection method for buried pipelines using the same.

  In the event of a disaster such as an earthquake, a buried pipeline that supplies gas shuts off the gas distribution upstream of the location of the disaster. In order to resume gas supply to the disaster location after that, it is necessary to check the soundness of the buried pipeline in the entire gas supply stop area, and when the gas supply is stopped over a wide area Therefore, it is required to quickly check the soundness of the buried pipeline and shorten the time from gas supply stop to recovery as much as possible.

  To cope with this, the wide area where the gas supply was stopped was blocked into a plurality of relatively narrow areas, and the gas supply was restarted sequentially from the upstream block where the soundness of the buried pipeline was confirmed. Is possible. According to the gas supply method at the time of a disaster described in Patent Document 1 below, the leaked / damaged portion of the buried pipeline is searched, and gas is supplied to selected locations of all buried pipelines that are upstream of the specified leaked / damaged portion. It has been proposed to block the upstream side of the specified leakage / damage location by filling the blocking member.

JP 2010-139039 A

  After blocking the wide gas supply stop area as in the above-mentioned conventional technology, the leakage of the embedded pipeline was inspected in units of blocks sequentially from the upstream side of the gas supply, and the soundness of the embedded pipeline was confirmed. Restart gas supply for each block. In this leak inspection, inspection gas is injected into the buried pipeline in each block, gas detection is performed on the buried pipeline where the inspection gas is injected, and no gas is detected. Check soundness.

  At this time, the inspection gas injected into the buried pipeline is required to use a non-flammable gas in order to prevent secondary damage. On the other hand, it is required to contain a combustible gas at a predetermined ratio so that the inspection gas leaked by the existing gas detector can be easily detected. For this reason, the test gas is a mixed gas having a combustible gas (methane) ratio of 12% and a nitrogen ratio of 88%, and it is necessary to manage the component ratio of the mixed gas with high accuracy. Become.

  However, until now, it has not been possible to immediately obtain a test gas having such a high-accuracy component ratio at the site where leakage inspection of an embedded pipeline is performed, and methane and nitrogen are mixed into the container at the required ratio, Curing was performed until the components were stabilized throughout the container. According to this, there is a problem that it takes time until the components are stabilized, and the leakage inspection of the buried pipeline in the block cannot be performed quickly.

  This invention makes it an example of a subject to cope with such a problem. That is, the inspection gas having the desired component ratio can be immediately mixed at the site where the leakage inspection of the embedded pipeline is performed, the leakage inspection of the embedded pipeline in the block is quickly performed, and the gas supply stoppage is quickly restored. It is an object of the present invention to make this possible.

  In order to achieve such an object, the present invention comprises at least the following configuration.

A device for mixing a test gas to be injected into the buried pipeline in order to perform a leak test on the buried pipeline, the first flow path having an inlet end connected to the supply source of the first component gas, and a second A second flow path having an inlet end connected to a component gas supply source, and a mixed gas of the first component gas and the second component gas is communicated with the first flow path and the second flow path. And a mixing flow path having an outlet connected to the inlet of the buried pipeline, the first flow path including a first pressure reducing valve for setting a component ratio of the first component gas, and the second flow path. The flow path includes a second pressure reducing valve that sets a component ratio of the second component gas. The first pressure reducing valve and the second pressure reducing valve communicate with each other in pressure control chambers , and the first flow The path includes a bypass flow path straddling the first pressure reducing valve, and the bypass flow path includes the first flow path. Valve and is provided with an auxiliary pressure reducing valve of a different set pressure, the bypass flow path leakage inspection gas buried pipeline, characterized in that it communicates with the pressure control chamber of the second pressure reducing valve and the first pressure reducing valve Mixing equipment.

  The present invention having such a feature makes it possible to immediately obtain a test gas having a desired component ratio at a site where a leakage inspection of an embedded pipeline is performed, and to quickly perform a leakage inspection of the embedded pipeline within a block. In addition, it is possible to realize an early recovery from a gas supply stop.

It is explanatory drawing which showed the leakage inspection gas mixing apparatus of the buried pipeline which concerns on one Embodiment of this invention. It is explanatory drawing which showed the example of the form of the leak test | inspection gas mixing apparatus which concerns on embodiment of this invention. 2A is a front view, FIGS. 2B and 2C are left and right side views, and FIG. 2D is a plan view. It is explanatory drawing which shows the leakage inspection method of the buried pipeline using the leakage inspection gas mixing apparatus which concerns on embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory view showing a leakage inspection gas mixing device for an embedded pipeline according to an embodiment of the present invention. The leakage inspection gas mixing apparatus 1 is an apparatus that manufactures the inspection gas injected into the embedded pipeline by mixing a plurality of component gases in order to perform the leakage inspection of the embedded pipeline. A second flow path 20 and a mixing flow path 30 are provided.

  The first flow path 10 has an inlet end 10A connected to a supply source of a first component gas (not shown), and the second flow path 20 is connected to a supply source of a second component gas (not shown). It has an inlet end 20A. The mixed flow path 30 communicates with the first flow path 10 and the second flow path 20, and a mixed gas of the first component gas flowing through the first flow path 10 and the second component gas flowing through the second flow path 20 is present. It is a flow path that circulates. The mixing channel 30 has an outlet end 30A connected directly or via a supply hose or the like to an inlet in a buried pipeline (not shown).

  The first flow path 10 includes a first pressure reducing valve 11 that sets a component ratio of the first component gas. The second flow path 20 is provided with a second pressure reducing valve 21 that sets the component ratio of the second component gas. The first pressure reducing valve 11 and the second pressure reducing valve 21 are in communication with each other through the communication passage 12 between the pressure control chambers 11 a and 21 a.

  In the illustrated example, flow rate adjusting means 13 and 22 are provided on both the downstream side of the first pressure reducing valve 11 in the first flow path 10 and the downstream side of the second pressure reducing valve 21 in the second flow path 20. The flow rate adjusting means 13 and 22 may be provided in both the first flow path 10 and the second flow path 20 as shown, or may be provided in either one.

  The flow rate adjusting means 13 is provided with two flow paths 13B and 13C via a switching valve 13A, and the two flow paths 13B and 13C merge on the downstream side and communicate with the mixing flow path 30. Flow meters 13B1 and 13C1 and needle valves 13B2 and 13C2 are provided in the two flow paths 13B and 13C, respectively. The flow rate adjusting means 22 is also the same, and two flow paths 22B and 22C are provided via the switching valve 22A, and the two flow paths 22B and 22C are merged downstream and communicated with the mixing flow path 30. . Each of the two flow paths 22B and 22C is provided with flow meters 22B1 and 22C1 and needle valves 22B2 and 22C2.

  In the illustrated example, the first flow path 10 includes a bypass flow path 14 that straddles the first pressure reducing valve 11. The bypass passage 14 is provided with an auxiliary pressure reducing valve 15 having a set pressure different from that of the first pressure reducing valve 11. The bypass flow path 14 communicates with the pressure control chambers 11 a and 21 a of the first pressure reducing valve 11 and the second pressure reducing valve 21 by communicating with the communication path 12. In the bypass channel 14, a pressure relief valve 16 is provided on the downstream side of the communication point with the communication path 12.

  In the illustrated example, pressure gauges 10C and 20C are connected to the downstream sides of the inlet ends 10A and 20A of the first flow path 10 and the second flow path 20 via pressure gauge main valves 10B and 20B. Vent flow paths 10E and 20E are connected via blow valves 10D and 20D. In addition, inlet valves 10F and 20F are provided on the downstream side of the pressure gauge main valves 10B and 20B of the first flow path 10 and the second flow path 20, respectively.

  In the illustrated example, the mixing channel 30 is provided with a mixer (gas mixing means) 31. Furthermore, a safety valve 32 is connected to the downstream side of the mixer 31 in the mixing channel 30 via a safety valve main valve 32A, and a vent channel 34 is connected to the downstream side via a blow valve 33. Yes. A pressure reducing valve 35 is provided downstream of the connection point of the vent flow path 34 in the mixing flow path 30, a pressure gauge 36 is connected to the downstream thereof via a pressure gauge main valve 36 A, and a relief valve is further downstream. A relief valve 37 is connected via the main valve 37A. Further, an outlet valve 38 is provided on the downstream side of the relief valve 37 in the mixing channel 30.

  In the leak test gas mixing apparatus 1 having such a configuration, the supply source of the first component gas is connected to the inlet end 10A of the first flow path 10 directly or via a hose or the like, and the supply source of the second component gas Is connected to the inlet end 20A of the second flow path 20 directly or via a hose or the like, so that the test gas obtained by mixing the first component gas and the second component gas at a set component ratio is discharged from the mixing flow path 30. It can be obtained from the end 30A.

  Here, the component ratio of the first component gas and the second component gas can be set by the set pressure of the first pressure reducing valve 11 and the second pressure reducing valve 21, and the flow rate adjusting means 13 can adjust the finer component ratio. , 22. The leak test gas mixing apparatus 1 is configured such that the pressure control chamber 11a of the first pressure reducing valve 11 and the pressure control chamber 21a of the second pressure reducing valve 21 are communicated with each other by the communication passage 12, so 2 The pressure reduction of the pressure reducing valve 21 is performed in conjunction with each other, and the downstream pressure of the first pressure reducing valve 11 and the second pressure reducing valve 21 can be adjusted while maintaining a desired component ratio with high accuracy. Further, since the interlocking of the first pressure reducing valve 11 and the second pressure reducing valve 21 does not depend on electrical control, a safe device can be realized under the situation where combustible gas is handled.

  The first flow path 10 is provided with a bypass flow path 14, and an auxiliary pressure reducing valve 15 is provided in the bypass flow path 14, and the pressures of the pressure control chamber 11 a of the first pressure reducing valve 11 and the second pressure reducing valve 21 are provided. Since the control chamber 21 a communicates with the bypass flow path 14, the first component gas is set by the set pressure of the auxiliary pressure reducing valve 15 even when the supply pressure of the first component gas supply source or the second component gas supply source decreases. The component ratio of the second component gas can be kept constant. Furthermore, since the mixing channel 30 is provided with a mixer (gas mixing means) 31 for mixing the first component gas and the second component gas, at the outlet end 30A of the mixing channel 30, it is uniform at a desired component ratio. Test gas can be obtained.

  FIG. 2 is an explanatory view showing a form example of a leakage inspection gas mixing apparatus according to an embodiment of the present invention. 2A is a front view, FIGS. 2B and 2C are left and right side views, and FIG. 2D is a plan view.

  In the illustrated example, the leakage inspection gas mixing apparatus 1 includes a frame body 41 with casters 40. The frame 41 has a box-shaped space inside, and the first flow path 10, the second flow path 20, and the mixing flow path 30 are arranged in the space. The inlet end 10 </ b> A of the first channel 10 and the inlet end 20 </ b> A of the second channel 20 are disposed on one side surface (right side surface) of the frame body 41. The outlet end 30 </ b> A of the mixing channel 30 is disposed on the other side surface (left side surface) of the frame body 41. Parts that are the same as those in FIG. By arranging the first flow path 10, the second flow path 20, and the mixing flow path 30 in the frame body 41 with the casters 40, it becomes easy to carry to the work site where the leakage inspection is performed.

As an example of the inspection gas obtained by the leakage inspection gas mixing device 1, the first component gas is nitrogen (N ₂ ), and the second component gas is methane (CH ₄ ). Further, compressed natural gas can be used as the second component gas. And in order to make it possible to detect with the existing gas detector without being flammable, the test gas has a methane component ratio of 12% (nitrogen component ratio of 88%). When the component ratio of methane is 13% or more, it is classified as a combustible gas. When the proportion of methane is less than 11%, it is difficult to detect with a general gas detector. Therefore, the methane component ratio of the inspection gas needs to be maintained in a highly accurate and stable state within a range of −1% or more and less than + 0.5% with respect to 12%. According to the leak test gas mixing apparatus 1, a nitrogen supply source and a methane supply source are arranged at the work site of the leak test, and these are connected to the inlet ends 10A and 20A of the leak test gas mixing apparatus 1 to instantly generate methane components. 12% inspection gas can be obtained with high accuracy and stability.

  Below, based on FIG. 3, the leakage inspection method of the buried pipeline using the leakage inspection gas mixing apparatus 1 which concerns on embodiment of this invention is demonstrated. In the restoration work after the gas supply is cut off in a wide area, first, an area where early restoration is possible is selected, and the buried pipeline in the area is cut off for blocking (S1). Then, in one blocked block, the inspection gas is injected into the buried pipeline using the leakage inspection gas mixing device 1 (S2).

  Gas leakage detection is performed on the ground with respect to the buried pipeline into which the inspection gas has been injected (S3). In this case, the inspection gas leaked from the buried pipeline is captured by placing the gas detector on the ground surface and moving it along the buried pipeline. When the laying distance of the buried pipeline is long, the work can be quickly advanced by capturing the inspection gas while moving the gas detector attached to the moving means such as a bicycle.

  Then, when the inspection gas is captured by the gas detector (leakage S4: YES), the leakage location is specified, repair work is performed by excavation, and the inspection gas is injected again into the buried pipeline (S2). ), Gas leakage detection on the ground is performed (S3). When the inspection gas is not captured by the gas detector (leakage S4: NO), the gas cutoff of the buried pipeline is opened upstream in the block, and the gas supply in the block is resumed (S6). After that, the process moves to the next block (S7).

  According to the leakage inspection method for buried pipelines using the leakage inspection gas mixing apparatus 1 according to the embodiment of the present invention, inspection of 12% methane that does not have flammability and can be detected by an existing gas detector Gas can be obtained immediately at the work site. This makes it possible to quickly perform a safe and low-cost leak inspection.

1: Leakage inspection gas mixing device,
10: 1st flow path, 10A, 20A: Inlet end, 10B, 20B: Pressure gauge main valve,
10C, 20C: pressure gauge, 10D, 20D: blow valve,
10E, 20E: Vent flow path, 10F, 20F: Inlet valve,
11: first pressure reducing valve, 11a: pressure control chamber,
12: Communication path, 13, 22: Flow rate adjusting means, 14: Bypass flow path,
15: auxiliary pressure reducing valve, 16: pressure relief valve,
20: second flow path,
21: second pressure reducing valve, 21a pressure control chamber,
30: mixing channel, 30A: outlet end, 31: mixer (gas mixing means),
32: Safety valve, 33: Blow valve, 34: Vent flow path,
35: Pressure reducing valve, 36: Pressure gauge, 37: Relief valve, 38: Outlet valve,
40: caster, 41: frame,

Claims (6)

A device that mixes the inspection gas injected into the buried pipeline in order to perform leakage inspection of the buried pipeline,
A first flow path having an inlet end connected to a supply source of the first component gas;
A second flow path having an inlet end connected to a supply source of the second component gas;
A mixed flow having an outlet end connected to the inlet of the buried pipeline while the mixed gas of the first component gas and the second component gas circulates in communication with the first flow path and the second flow path With a road,
The first flow path includes a first pressure reducing valve that sets a component ratio of the first component gas, and the second flow path includes a second pressure reducing valve that sets a component ratio of the second component gas, The first pressure reducing valve and the second pressure reducing valve communicate with each other in pressure control chambers ,
The first flow path includes a bypass flow path straddling the first pressure reducing valve, and the bypass flow path is provided with an auxiliary pressure reducing valve having a set pressure different from that of the first pressure reducing valve,
The leakage inspection gas mixing apparatus for an embedded pipeline, wherein the bypass flow path communicates with a pressure control chamber of the first pressure reducing valve and the second pressure reducing valve .   The flow rate adjusting means is provided on one or both of the downstream side of the first pressure reducing valve in the first flow path and the downstream side of the second pressure reducing valve in the second flow path. Leakage inspection gas mixing device for buried pipeline described in 1. 3. The leak inspection gas mixing apparatus for an embedded pipeline according to claim 1, wherein the mixing flow path includes a gas mixing unit that mixes the first component gas and the second component gas. 4. The first component gas is nitrogen, the second gas is methane, and an inspection gas in which 12% methane and 88% nitrogen are mixed is obtained at the outlet of the mixing channel. Item 4. A leakage inspection gas mixing device for an embedded pipeline according to any one of Items 1 to 3 . The leakage inspection gas mixing device for an embedded pipeline according to any one of claims 1 to 3 , wherein the second component gas is compressed natural gas. Leakage inspection method for buried pipelines using the leakage inspection gas mixing device according to any one of claims 1 to 5 ,
Connecting the outlet end of the mixing flow path to an inlet of a blocked buried pipeline, and injecting the inspection gas mixed by the leaky inspection gas mixing device into the buried pipeline;
And a step of detecting a gas leak on the ground with respect to the buried pipeline using a gas detector after injecting the inspection gas.

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