Gas transfer unit and gas transfer system

Abstract

To provide a gas transportation unit and a gas transportation system having a gas leakage detection function for safely transporting gas by using a pipe laid in the ground or an underground space.SOLUTION: A gas transport system comprising: a transport pipe (101) for transporting a gas to be transported; a sheath pipe (102) accommodating the transport pipe; and a shield pipe (103) disposed along an outer wall of the transport pipe in a space formed by the transport pipe and the sheath pipe, the gas transportation unit (10) includes an optical fiber cord (103) acting as a fiber of distributed optical fiber sensing, and a monitoring device (40) connected to the optical fiber cord and configured to determine the occurrence of an event by performing distributed optical fiber sensing using the optical fiber cord.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a gas transport unit and a gas transport system, and more specifically to a gas transport unit and a gas transport system for transporting gas using piping laid underground or in an underground space. [Background technology]

[0002] The commercialization of pipeline transportation of hydrogen gas is being considered as a transportation infrastructure for hydrogen, an energy source that does not emit carbon dioxide, a greenhouse gas (Non-Patent Document 1).

[0003] Generally, gas transportation using pipes laid underground or in underground spaces is mainly carried out using pipes buried by civil engineering work. If a leak of gas occurs during transportation due to a small crack or break in the pipe caused by deterioration over time such as corrosion or an external factor such as an accident, detection is carried out by detecting changes in the readings of pressure gauges or flow meters, manually detecting by smell, or using gas detectors at the gas injection point into the pipe, the gas supply point from the pipe to the consumer equipment, or the pressure adjustment point installed along the pipe (Non-Patent Documents 2 and 3).

[0004] When a gas leak is detected, the location of the leak is identified and necessary repairs or replacement of components are carried out. For underground pipes, the location is bored and the leak location is identified using a gas detector or by smell, while for pipes laid in a tunnel or underground space, someone may go near the pipe and identify the leak location using a gas detector or by smell. A common method for both is to install multiple gas detectors and sensors along the pipe to identify the leak location. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] Ryo Matsuki, "Research for Considering Technical Standards Related to Hydrogen Supply Infrastructure," NEDO Hydrogen and Fuel Cell Results Presentation 2023, Presentation No. B1-6, July 13, 2023. https: / / hydrogen2023.nedo.go.jp / wp-content / uploads / 2023 / 06 / B1-6.pdf [Non-patent document 2] Hideo Hashimoto, "Leak Detection Method", Safety Engineering, Vol. 25, No. 1, 1986 https: / / www.jstage.jst.go.jp / article / safety / 25 / 1 / 25_34 / _pdf / -char / ja [Non-patent document 3] Kawaguchi Liquefied Chemical Co., Ltd. website, "Inspection of Buried Gas Pipes (Propane Gas Edition)" https: / / klchem.co.jp / blog / 2017 / 12 / 4389.php [Non-patent document 4] Naoya Uchida, "Discovery of Hydrogen-Induced Optical Fiber Loss Increase and Establishment of Prevention Measures," Communications Society Magazine No. 25 Summer 2013 Figure 3(b) [Non-patent document 5] Soichi Ishikawa et al.: "Changes in Optical Loss Characteristics of Optical Fibers during Short-Term Exposure to Hydrogen", Transactions of the Institute of Electronics, Information and Communications Technology, B-13-10, (2022-03) Summary of the Invention [Problem to be solved by the invention]

[0006] However, laying gas transmission pipes underground requires not only land acquisition but also large-scale, long-term civil engineering work, which incurs significant costs. Additionally, there may be additional costs (both time and money) associated with explaining the project to local residents and conducting environmental assessments. This can hinder the laying of new gas transmission pipes.

[0007] Furthermore, when odorization is used to detect gas leaks, it is possible to detect the occurrence of a certain amount of gas leakage, but to identify the leak location, manual labor is required, such as drilling and detecting with odor or gas detectors, and the installation of many gas detectors and sensors is necessary, which incurs additional costs.In addition, even if odorization is used, the smell may be diluted by the fact that gas transportation pipes run underground, and in the case of gases with a specific gravity lighter than air, the smell is dispersed into the air, making it difficult to identify the leak location.

[0008] Furthermore, when transporting gases that require high purity, such as hydrogen gas, it is necessary to install and maintain equipment such as filters to remove impurities at the gas supply point, which increases the initial and running costs.

[0009] The need to install a large number of gas detectors and sensors to identify leak locations increases costs, and gas detectors and sensors can deteriorate or break down in humid environments or due to water intrusion.

[0010] Furthermore, when workers go to a place filled with leaked gas to identify the leak location, repair it, or replace parts, safety measures such as explosion / fire prevention and suffocation prevention are essential.

[0011] An object of the present invention is to provide a gas transport unit and a gas transport system equipped with a gas leak detection function, which safely transports gas using pipes laid underground or in underground spaces. [Means for solving the problem]

[0012] In order to achieve the above-mentioned object, one example configuration of a gas transport unit according to the present invention is a gas transport unit having a transport pipe for transporting a gas to be transported, a sheath tube that houses the transport pipe, and an optical fiber cord arranged along the outer wall of the transport pipe within the space formed by the transport pipe and the sheath tube, wherein the optical fiber cord acts as a fiber for distributed optical fiber sensing.

[0013] In one configuration example of the gas transport unit according to the present invention, the gas transport unit further comprises a closure that is connected to the sheath tube and that houses the transport tube together with the sheath tube, a gas detection sensor that is disposed within the closure and configured to detect the gas to be transported, and a pressure sensor that is disposed within the closure and configured to detect the pressure within the closure, wherein the gas detection sensor and the pressure sensor are connected to the optical fiber cord, and the optical fiber cord may further act as input / output fibers for the gas detection sensor and the pressure sensor.

[0014] Furthermore, one configuration example of a gas transport system according to the present invention is a gas transport system comprising: a gas transport unit having a transport pipe for transporting a gas to be transported, a sheath tube that houses the transport pipe, and an optical fiber cord that is arranged along the outer wall of the transport pipe within the space formed by the transport pipe and the sheath tube and acts as a fiber for distributed optical fiber sensing; and a monitoring device that is connected to the optical fiber cord and configured to perform distributed optical fiber sensing using the optical fiber cord to determine the occurrence of an event.

[0015] In one configuration example of the gas transport system of the present invention, the gas transport unit further comprises a closure that is connected to the sheath tube and houses the transport tube together with the sheath tube, a gas detection sensor that is disposed within the closure and configured to detect the gas to be transported, and a pressure sensor that is disposed within the closure and configured to detect the pressure within the closure, wherein the gas detection sensor and the pressure sensor are connected to the optical fiber cord, and the optical fiber cord further acts as an input / output fiber for the gas detection sensor and the pressure sensor, and the monitoring device may be configured to determine the occurrence of an event based on the output of the gas detection sensor and the output of the pressure sensor.

[0016] In addition, in one configuration example of the gas transport system of the present invention, it may be configured to further include an inert gas supply device that supplies an inert gas to the space formed by the transport pipe, the sheath pipe, and the closure that constitute the gas transport unit.

[0017] In one configuration example of the gas transportation system according to the present invention, the monitoring device further monitors the pressure and flow rate of the gas to be transported flowing through the transportation pipe, - occurrence of an event based on distributed optical fiber sensing using the optical fiber cord; - leakage of the gas to be transported based on the output of the gas detection sensor; - the occurrence of an event based on the output of the pressure sensor; It may be configured to detect at least one of the above.

[0018] In one configuration example of the gas transportation system according to the present invention, the optical fiber cord may be wound around the outside of the transportation pipe.

[0019] In one configuration example of the gas transportation system according to the present invention, the wavelength used for the distributed optical fiber sensing may be 1240 nm. [Effects of the Invention]

[0020] According to the present invention, it is possible to provide a gas transport unit and a gas transport system equipped with a gas leak detection function, which safely transports gas using pipes laid underground or in underground spaces. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. 1 is a diagram illustrating the configuration of a gas transportation unit according to an embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view illustrating the configuration of the gas transport unit according to the embodiment of the present invention. [Figure 3] FIG. 3 is a diagram illustrating the configuration of a gas transportation system according to an embodiment of the present invention. [Figure 4] FIG. 4 is a block diagram illustrating the configuration of a sensing device for a gas transportation system according to an embodiment of the present invention. [Figure 5] FIG. 5 is a diagram illustrating an overview of an operation system in a gas transportation system according to an embodiment of the present invention. [Figure 6] FIG. 6 is a flowchart illustrating the operation of the gas transportation system according to the embodiment of the present invention. [Figure 7A] FIG. 7A is a diagram illustrating a combined detection method in a gas transportation system according to an embodiment of the present invention. [Figure 7B] FIG. 7B is a diagram illustrating a combined detection method in a gas transportation system according to an embodiment of the present invention. [Figure 8] FIG. 8 is a diagram illustrating a composite detection method in a gas transportation system according to an embodiment of the present invention. [Figure 9] FIG. 9 is a diagram illustrating a composite detection method in a gas transportation system according to an embodiment of the present invention. [Figure 10] FIG. 10 is a diagram illustrating a composite detection method in a gas transportation system according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0023] [Gas transport unit] The gas transport unit according to this embodiment is a unit-type double pipe that integrates a gas transport pipe (hereinafter sometimes referred to as a "transport pipe") and a sheath pipe that houses this transport pipe. More specifically, as shown in FIG. 1, gas transport unit 10 has a transport pipe 101 for transporting a gas to be transported, such as hydrogen, and a sheath pipe 102 that houses transport pipe 101, and has an optical fiber cord 103 that is disposed along the outer wall of transport pipe 101 within the space formed by transport pipe 101 and sheath pipe 102. Such a gas transport unit 10 is installed within existing piping facilities, such as underground pipes and cable tunnels in buried communication cable conduits and utility tunnels.

[0024] The transport pipe 101 is a composite pipe made by combining a metal pipe made of iron, copper, aluminum, SUS, etc., a reinforcing material such as glass fiber or carbon fiber, and a base material (matrix) such as a thermosetting resin. Depending on the type of gas to be transported, the material of the transport pipe 101 can be appropriately selected as long as it is a material that is difficult for the gas to pass through, such as a metal pipe such as stainless steel or a resin pipe.

[0025] The sheath tube 102 is, for example, a metal or polyethylene tube that covers the transport tube 101. The sheath tube 102 is preferably made of an airtight material that is impervious to rainwater and impermeable to the gas to be transported.

[0026] In the gas transport unit 10 of this embodiment, optical fiber cords 103 are wound around the outer wall of the transport pipe 101, and these optical fiber cords 103 act as fibers for distributed optical fiber sensing, which will be described later, and also act as signal lines for various sensors.

[0027] The gas transport unit 10 further includes a closure 104 that is connected to the sheath pipe 102 and that houses the transport pipe 101 together with the sheath pipe 102. This closure 104 may be disposed, for example, in a manhole when the gas transport unit 10 is disposed in a buried pipe underground.

[0028] A hydrogen detection sensor 105 configured to detect hydrogen, which is the gas to be transported, within the closure 104, and a pressure sensor 106 configured to detect the pressure within the closure 104 are disposed within the closure 104. The hydrogen detection sensor 105 and the pressure sensor 106 are connected to an optical fiber cord 103. In this case, the optical fiber cord 103 acts as an input / output fiber for the hydrogen detection sensor 105 and the pressure sensor 106.

[0029] A cross section perpendicular to the longitudinal direction of the gas transport unit 10 is shown in Figure 2. The transport pipe 101 is placed inside the sheath pipe 102 via a spacer 107, and a gap G is formed between the outer wall of the transport pipe 101 and the sheath pipe 102. In this gap, an optical fiber cord 103 is wound around the outer wall of the transport pipe 101.

[0030] The sheath tube 102 and the closure 104 form an airtight space isolated from the outside air, and pressurized inert gas is filled in the gap G between the transport tube 101 and the sheath tube 102 and the inside of the closure 104. Dry air from which oxygen has been removed can be used as the inert gas. In this way, the transport tube 101 is protected by the sheath tube 102 and the closure 104, and a constant pressure is maintained by pressurizing the inert gas into the gap between the transport tube 101 and the sheath tube 102 and the closure, thereby preventing water intrusion and maintaining an appropriate environment in which a hydrogen sensor or the like can perform detection.

[0031] [Gas Transmission System] Next, a gas transportation system 1 using the above-described gas transportation unit 10 will be described with reference to Figure 3. Note that the description will be given taking as an example a case where hydrogen gas is transported as the gas to be transported.

[0032] [Gas transmission system configuration] The gas transport system 1 of this embodiment is configured to transport hydrogen gas from the hydrogen gas supply system 20 to the demand system 21 by laying a double pipe 100 that transports hydrogen gas from the hydrogen gas supply system 20 to the demand system 21 within an existing piping facility (hereinafter sometimes simply referred to as "existing piping facility") 50, such as an underground pipe or cable tunnel, such as a buried communication cable conduit or utility tunnel.

[0033] The gas transport system 1 also includes an optical fiber cord 103 arranged within the double piping 100, various sensors 105a to 105c, 106a to 106c, 202, 203 provided along the double piping 100, and a sensing device 30 that performs distributed optical fiber sensing using the optical fiber cord 103.

[0034] Furthermore, a monitoring device 40 is provided that monitors the double pipe 100 for any faults or the like that occur based on the outputs of the various sensors 105a to 105c, 106a to 106c, 202, 203 and the output of the sensing device 30.

[0035] [Double piping] Here, the double piping 100 is a combination of the gas transport units 10 described above, and is a unit-type double piping in which a transport pipe 101 for transporting hydrogen gas, a sheath pipe 102, and closures 104a, 104b, and 104c are integrated. The transport pipe 101 holds the applied pressure of hydrogen gas and is made of a non-flammable material that is impermeable to hydrogen and oxygen and does not react with hydrogen. The sheath pipe 102 holds the applied pressure of an inert gas described below and is made of a non-flammable material that is impermeable to hydrogen and oxygen and does not react with hydrogen. Like the sheath pipe 102, the closures 104a, 104b, and 104c also hold the applied pressure of the inert gas and is made of a non-flammable material that is impermeable to hydrogen and oxygen and does not react with hydrogen. The closures 104a, 104b, and 104c are arranged in manholes Ma, Mb, and Mc provided in the existing piping equipment 50. A transport pipe 101 for transporting hydrogen gas is protected by a sheath pipe 102 and closures 104a to 104c.

[0036] In this embodiment, an inert gas supply device is provided on the supply system 20 side, the inert gas supply device comprising an inert gas cylinder 205 storing inert gas and a compressor 206. This inert gas supply device supplies inert gas to a gap G formed by the transport pipe 101, the sheath pipe 102, and the closures 104a, 104b, and 104c of the double pipe 100. The inert gas supply device comprising the inert gas cylinder 205 and the compressor 206 normally pressurizes the gap G formed by the transport pipe 101, the sheath pipe 102, and the closures 104a, 104b, and 104c to atmospheric pressure (approximately 0.1 MPa) or higher. In this way, by pressurizing the space between the transport pipe 101, the sheath pipe 102, and the closures 104a to 104c with inert gas to atmospheric pressure or higher, the inflow of external air and water into the sheath pipe 102 is prevented, and an appropriate environment is maintained in which a hydrogen sensor or the like can perform detection. Furthermore, even if hydrogen leaks from the transport pipe due to poor construction or cracks caused by deterioration, it is possible to prevent leakage into manholes, etc. for a certain period of time, and in the event of a hydrogen leak, the pressure is increased above the hydrogen gas supply pressure, and the leaked hydrogen in the sheath tube 102 and closures 104a, 104b, and 104c is diluted and purged with air, thereby controlling the situation to a safe state.

[0037] [Supply system] The supply system 20 is provided at one end of the double pipe 100 and includes a hydrogen gas supply source and a compressor that sends hydrogen gas to the transport pipe 101. A flow meter 202 and a pressure gauge 203 are installed in the hydrogen gas supply path as pressure and flow rate monitors to measure the flow rate and pressure of the hydrogen gas being supplied. These flow meter 202 and pressure gauge 203 can detect sudden changes such as a rupture in the transport pipe. A shutoff valve 204 is also provided to stop the supply of hydrogen gas.

[0038] [Optical fiber cord and sensor] The optical fiber cord 103 is wound around the outer wall of the transport tube 101 and is housed together with the transport tube 101 in the sheath tube 102 and closures 104a, 104b, and 104c.

[0039] Hydrogen detection sensors 105a, 105b, 105c and pressure sensors 106a, 106b, 106c are installed within closures 104a, 104b, 104c, respectively. These hydrogen detection sensors 105a, 105b, 105c and pressure sensors 106a, 106b, 106c are connected to optical fiber cord 103. FBG (Fiber Bragg Grating) sensors can be used as such hydrogen detection sensors. Furthermore, MEMS (Micro Electro Mechanical Systems) sensors that are optically powered and transmit their results optically can be used as pressure sensors. In gas transportation system 1 according to this embodiment, pressure sensors 106a, 106b, 106c are optically powered and have optical communication capabilities.

[0040] The optical fiber cord 103 serves as a signal line for the sensor and also as a fiber for distributed optical fiber sensing, as described below. That is, the input / output fibers for the hydrogen detection sensors 105a, 105b, and 105c and the pressure sensors 106a, 106b, and 106c are used as fibers for distributed optical fiber sensing.

[0041] Furthermore, by using an optical fiber modified with a hydrogen-sensitive film for the optical fiber cord 103, it is possible to make it function as an optical fiber hydrogen sensor.

[0042] [Distributed optical fiber sensing device] The sensing device 30 uses the optical fiber cord 103 as a sensing unit and is a device that detects sound and vibration, measures strain, and detects loss, bending, and broken positions by distributed optical fiber sensing for monitoring the fiber condition.

[0043] As shown in Figure 4, such a sensing device 30 includes a laser light source 301 that generates laser light and inputs the sensing light from one end of the optical fiber cord 103 on the supply system 20 side via an optical interface circuit 302, and a sensing unit 303 that receives the sensing light reflected at the other end of the optical fiber cord 103, performs distributed optical fiber sensing, and outputs the result to the monitoring device 40.

[0044] Here, the laser light source 301 inputs pulses of laser light, which will serve as sensing light, into the optical fiber code 103. In a gas transport system that transports hydrogen, laser light with a wavelength of 1240 nm may be input into the optical fiber code 103. This is because 1240 nm is the second harmonic of the 2420 nm wavelength with absorption loss that corresponds to the basic stretching motion of hydrogen molecules (Non-Patent Document 4), and is the wavelength band that transmits through optical fibers, which provides the highest sensitivity.

[0045] The sensing unit 303 also functions as an optical time domain reflectometer (OTDR) that measures the intensity of Rayleigh scattering and analyzes the amount of distortion, and is configured to detect the location of loss bending breaks using the OTDR. The sensing unit 303 is further configured to detect distortion using a B-OTDR (Brillouin OTDR) that analyzes the amount of distortion from the amount of frequency shift of Brillouin scattering, and to detect sound and vibration using a C-OTDR (Coherent detection OTDR) that uses a coherent detection method in the receiving system.

[0046] Furthermore, when the gas to be transported is hydrogen, the optical fiber cord 103 itself may be modified with a hydrogen-sensitive film to form an optical fiber hydrogen sensor, and the sensing unit 303 may perform optical sensing of the hydrogen absorption distribution using an optical fiber.

[0047] In addition, the sensing device 30 receives the outputs of the hydrogen detection sensors 105a, 105b, 105c and pressure sensors 106a, 106b, 106c provided in the closures 104a, 104b, 104c through the optical fiber cord 103, separates them using the optical interface circuit 302, and outputs them from the output circuit 304 to the monitoring device 40.

[0048] [Monitoring device] The monitoring device 40 determines whether or not a hydrogen gas leak has occurred and gives instructions on how to respond based on the outputs of the hydrogen detection sensors 105a, 105b, 105c and pressure sensors 106a, 106b, 106c, the outputs of the flow meter 202 and pressure meter 203 provided in the hydrogen gas supply path, the results of hydrogen absorption distribution optical sensing using optical fiber, and the results of distributed optical fiber sensing.

[0049] 5, the monitoring device 40 is a monitoring and control function block that controls the operation of the shutoff valve 204 and the compressor 206 based on signals such as the outputs of the hydrogen detection sensors and pressure sensors 106a, 106b, and 106c, the outputs of the flow meter 202 and the pressure meter 203 provided in the hydrogen gas supply path, the results of hydrogen absorption distribution optical sensing using optical fiber, and the results of distributed optical fiber sensing. More specifically, the monitoring device 40 checks the signals input from the various sensors to determine whether or not there is an abnormality, and if an abnormality is determined to exist, controls the operation of the shutoff valve 204 and the compressor 206 according to the nature of the abnormality.

[0050] Furthermore, the monitoring device 40 may be configured to cooperate with a separately provided facility management DB system, a monitoring system, and a control system via a monitoring and control network (NW).

[0051] Such a monitoring device 40 can be realized by the cooperation of a computer comprising an arithmetic unit, a storage device, and various interface circuits, and a computer program installed on this computer.

[0052] [Gas transmission system operation] Next, the operation of the gas transportation system 1 will be described with reference to FIGS.

[0053] FIG. 6 is a flowchart showing the operation procedure of the gas transportation system 1.

[0054] First, the occurrence of an abnormality is detected based on the outputs of various sensors (S101). When an abnormality is detected, the abnormality status is determined and the location of the abnormality is identified (S102). Depending on the abnormality status, safety measures such as supply cutoff and purging are implemented (S103). After the safety measures have been implemented, repair personnel are dispatched to carry out emergency measures and repairs (S104), and post-recovery monitoring and regular testing are carried out (S105).

[0055] [Event occurs] 7A and 7B show an overview of the stages of an accident in the double pipe 100. FIG.

[0056] As shown in Figure 7A, the events that occurred can be classified into "sheath only damage," "transport pipe crack," "transport pipe failure (pinhole)," "transport pipe failure (perforation / disconnection)," and "disconnection accident." Here, "sheath only damage" is a condition that cannot be left unattended, even though there is no hydrogen leakage. In Figure 7B, the abnormal condition classification (urgency) is "S." "Transport pipe crack" is a condition that is less dangerous and less urgent, but cannot be left unattended for a long period of time. In Figure 7B, the abnormal condition classification (urgency) is "C." In Figure 7A, "transport pipe failure (pinhole)" and "transport pipe failure (perforation / disconnection)" ("small transport pipe pinhole" and "large transport pipe pinhole" in Figure 7B) do not leak hydrogen to the outside, but in the case of "transport pipe failure (pinhole)" ("transport pipe failure (small pinhole)" in Figure 7B), the urgency increases over time, even if it is initially moderate. In Figure 7B, the abnormal condition classification (urgency) of "transport pipe failure (small pinhole)" is "B2." In contrast, "transport pipe failure (perforation / disconnection)" is a highly urgent condition. In Figure 7B, the abnormal condition classification (urgency) of "transport pipe failure (large pinhole)" is "B1." In the case of double piping 100, from "damage to sheath only" to "transport pipe failure (perforation / disconnection)," even if hydrogen gas leaks from the transport pipe 101, it can be stored within the sheath pipe 102 for a certain period of time without leaking to the outside. In contrast, the "cutting accident" in Figure 7A ("transport pipe cut" in Figure 7B) involves external leakage of hydrogen, which is a highly dangerous and urgent condition. The abnormal condition classification (urgency) shown in Figure 7B is "A."

[0057] [Anomaly detection and status determination] The monitoring device 40 collects multiple pieces of information, such as the pressure and flow rate of hydrogen gas supplied to the transport pipe 101, which are monitored by a pressure gauge 202 and a flow meter 203 at the hydrogen gas source (hereinafter sometimes referred to as the "pressure / flow rate monitor"), as well as the results of hydrogen detection sensors 105a-105c and pressure sensors 106a-106c disposed in closures 104a-104c, and hydrogen absorption (1240 nm) distribution light sensing by an optical fiber cord 103, which are input from the sensing device 30, and detects the occurrence of an abnormal condition in a comprehensive manner. This allows for accurate detection of abnormalities and prevents missed detections and false detections (Figure 8).

[0058] For example, consider the case where some damage occurs only to the sheath tube 102. The pressure sensors 106a to 106c normally function as pressure sensors for checking the airtightness of the sheath tube 102 and the closures 104a to 104c. However, if damage occurs to the sheath tube 102, the pressure inside the sheath tube 102 and the closures 104a to 104c, which were filled with pressurized inert gas, will decrease as shown in FIGS. 7A and 7B. Therefore, damage to the sheath tube 102 can be detected by monitoring the output of the pressure sensors. If there is bending or distortion in the optical fiber cord 103, the location of the damage can be identified by distributed optical sensing (fiber sensing). It is also possible to identify the location by the sound of leakage of the inert gas (internal pressure air).

[0059] Even if the sheath tube 102 does not break, if an external force affects the optical fiber cord 103 during, for example, a periodic test, it is possible to detect this.

[0060] On the other hand, if a malfunction (crack, pinhole, perforation / disconnection, etc.) occurs in the transport pipe 101, hydrogen gas will leak into the sheath tube 102, and the hydrogen gas leakage can be directly detected by the hydrogen detection sensors 105a-105c when the hydrogen gas concentration reaches a predetermined level. By identifying the hydrogen detection sensors 105a-105c that have operated within the closures 104a-104c, the location of the leak can be identified to some extent. In addition to direct detection by the hydrogen detection sensors, the accuracy of the determination can be improved by judging the leak sound and the increase in internal pressure detected by the pressure sensors.

[0061] Although it takes some time (approximately 100 hours), it is also possible to identify the location using hydrogen absorption distribution optical fiber sensing. The more serious the fault in the transport pipe 101, the easier it will be to detect it with the hydrogen detection sensor, and the abnormality will also be detectable by the pressure / flow rate monitor and pressure sensors 106a to 106c.

[0062] In the event of an emergency breakage, such as when the transport pipe 101 breaks, triple detection is possible using not only pressure sensors, but also pressure and flow monitors and fiber sensing, and the location of the break can be identified using distributed optical fiber sensing. In such a case, the shutoff valve 204 is immediately closed to shut off the supply of hydrogen.

[0063] The monitoring device 40 performs comprehensive processing based on the outputs (ON / OFF) of the pressure and flow monitor, hydrogen detection sensor, pressure sensor, and hydrogen absorption distributed optical fiber sensing, and when it detects an abnormality, it issues a test command using distributed optical fiber sensing (sound and vibration detection, strain measurement, loss, bending, and broken position detection) to recognize the condition.

[0064] Furthermore, if a hydrogen gas leak is detected, the monitoring device 40 operates the compressor 206 to perform a purge process using an inert gas, i.e., dilution of the leaked hydrogen with the inert gas and air purging. It also sends out an alarm and a message requesting repairs to the relevant parties.

[0065] The relationship between the judgment events based on the output (ON / OFF) of the hydrogen detection sensor, pressure sensor, pressure / flow rate monitor, and hydrogen absorption distribution optical fiber sensing and the test instructions to be performed at that time can be expressed, for example, in tables such as those shown in Figures 9 and 10. Note that "(a)", "(b)", and "(c)" representing "test instructions" in Figures 9 and 10 respectively indicate "detection of optical loss, bending, and breakage position" by OTDR, "tensile strain measurement" by B-OTDR, and "acoustic detection" by C-OTDR, as shown in Figure 9.

[0066] The monitoring device 40 has such a table as part of its monitoring and control function block. More specifically, it can be provided in the format shown in the lower part of Fig. 10. The table shown in the lower part of Fig. 10 indicates, for example, that if "F," which indicates cause 1, is output in NW1-1, then (a) and (b) are executed. By adding arbitrary hierarchical and network information (UC) to the header to identify and manage which hydrogen pipeline network has experienced an abnormality, it is possible to shorten and streamline the execution process, assuming that a large number of hydrogen pipeline networks will be installed across a wide area.

[0067] [Advantages of this embodiment] According to the gas transmission system of this embodiment, modular double piping is laid in existing buried communication cable piping, utility conduits, tunnels, building basements, etc., so there is no need to acquire new land, no large-scale civil engineering work is required, and no explanation to surrounding residents or environmental assessments are required. Therefore, compared to conventional methods, laying can be done in a shorter time and at lower cost, and it is expected that the laying of new hydrogen and other gas piping facilities will be promoted.

[0068] According to the gas transportation system of this embodiment, an inert gas is pumped into the gap between the sheath tube and the transportation pipe to maintain a constant pressure, and a composite detection is performed using an optical fiber cord spirally wrapped around the transportation pipe for transporting the target gas inside the double pipe, a flow / pressure meter, a gas detection sensor, hydrogen absorption distribution optical fiber sensing by optical fiber, and an optical fiber sensing device such as COTDR.When the internal pressure of the inert gas drops, the pressure sensor in the closure detects an abnormality, and the optical fiber sensing device such as COTDR can identify the abnormal condition, probable cause, and break point.This eliminates the need for additional human intervention to identify gas leaks and gas leak locations caused by slight cracks or breaks due to aging or accidents, and the installation of multiple gas detectors and sensors on the pipes.

[0069] Furthermore, because no odor is used, additional equipment such as filters to remove impurities at the supply point is not required when transporting gases that require high purity, such as hydrogen gas. Furthermore, situations in which the odor weakens as the gas diffuses into the air or travels underground, making detection difficult, can be avoided, allowing for more reliable leak detection. In addition, because the leaked gas is sent into a sealed space within the closure and detected by a gas sensor, there is no need to send workers into spaces filled with leaked gas, improving safety.

[0070] Furthermore, by installing the sensor inside the double piping structure, deterioration of the gas sensor due to humidity, rainwater, etc. can be prevented.

[0071] In the present embodiment, hydrogen gas is described as the gas to be transported, but the gas to be transported is not limited to hydrogen.

[0072] (Addendum) The following additional clauses are disclosed in relation to the above-described embodiment.

[0073] (Additional note 1) a transport pipe for transporting the gas to be transported; a sheath tube that accommodates the transport tube; an optical fiber cord disposed in a space formed by the transport tube and the sheath tube along an outer wall of the transport tube; and The optical fiber cord acts as a fiber for distributed optical fiber sensing. Gas transport unit.

[0074] (Additional note 2) In the gas transport unit according to Supplementary Item 1, a closure connected to the sheath tube and accommodating the transport tube together with the sheath tube; a gas detection sensor disposed within the closure and configured to detect the gas to be transported; a pressure sensor disposed within the closure and configured to detect pressure within the closure; Furthermore, the gas detection sensor and the pressure sensor are connected to the optical fiber cord; The optical fiber cord further serves as an input / output fiber for the gas detection sensor and the pressure sensor. Gas transport unit.

[0075] (Additional note 3) a gas transport unit having a transport pipe for transporting a gas to be transported, a sheath pipe that houses the transport pipe, and an optical fiber cord that is disposed along the outer wall of the transport pipe within a space formed by the transport pipe and the sheath pipe and acts as a fiber for distributed optical fiber sensing; a monitoring device connected to the optical fiber cord and configured to perform distributed optical fiber sensing using the optical fiber cord to determine the occurrence of an event; A gas transport system comprising:

[0076] (Additional note 4) In the gas transport system according to Supplementary Item 3, The gas transport unit comprises: a closure connected to the sheath tube and accommodating the transport tube together with the sheath tube; a gas detection sensor disposed within the closure and configured to detect the gas to be transported; a pressure sensor disposed within the closure and configured to detect pressure within the closure; Furthermore, the gas detection sensor and the pressure sensor are connected to the optical fiber cord; the optical fiber cord further serves as an input / output fiber for the gas detection sensor and the pressure sensor; the monitoring device determines the occurrence of an event based on the output of the gas detection sensor and the output of the pressure sensor. Gas transmission system.

[0077] (Additional note 5) In the gas transport system according to supplementary item 3 or 4, The gas transport unit further includes an inert gas supply device that supplies an inert gas to a space formed by the transport pipe, the sheath pipe, and the closure. Gas transmission system.

[0078] (Additional note 6) In the gas transportation system according to any one of Supplementary Items 3 to 5, The monitoring device further monitors the pressure and flow rate of the gas to be transported flowing through the transport pipe; - occurrence of an event based on distributed optical fiber sensing using the optical fiber cord; - leakage of the gas to be transported based on the output of the gas detection sensor; - the occurrence of an event based on the output of the pressure sensor; configured to detect at least one of Gas transmission system.

[0079] (Additional note 7) In the gas transportation system according to any one of Supplementary Items 3 to 6, the optical fiber cord is wound around the outside of the transport pipe; Gas transmission system.

[0080] (Additional note 8) In the gas transportation system according to any one of Supplementary Items 3 to 6, The monitoring device The wavelength used for the distributed optical fiber sensing is 1240 nm; Gas transmission system. [Industrial Applicability]

[0081] The present invention may be utilized in gas transport units and gas transport systems. [Explanation of symbols]

[0082] 1...gas transport system, 10...gas transport unit, 101...transport pipe, 102...sheath tube, 103...optical fiber cord, 104...closure, 105...hydrogen detection sensor, 106...pressure sensor, 20...supply system, 202...pressure gauge, 203...flow meter, 204...shut-off valve, 205...inert gas cylinder, 206...compressor, 30...sensing device, 301...laser light source, 303...sensing unit, 304...output circuit, 40...monitoring device.

Claims

1. a transport pipe for transporting the gas to be transported; a sheath tube that accommodates the transport tube; an optical fiber cord disposed in a space formed by the transport tube and the sheath tube along an outer wall of the transport tube; and The optical fiber cord acts as a fiber for distributed optical fiber sensing. Gas transport unit.

2. 2. The gas transport unit according to claim 1, a closure connected to the sheath tube and accommodating the transport tube together with the sheath tube; a gas detection sensor disposed within the closure and configured to detect the gas to be transported; a pressure sensor disposed within the closure and configured to detect pressure within the closure; Furthermore, the gas detection sensor and the pressure sensor are connected to the optical fiber cord; The optical fiber cord further serves as an input / output fiber for the gas detection sensor and the pressure sensor. Gas transport unit.

3. a gas transport unit having a transport pipe for transporting a gas to be transported, a sheath pipe that houses the transport pipe, and an optical fiber cord that is disposed along the outer wall of the transport pipe within a space formed by the transport pipe and the sheath pipe and acts as a fiber for distributed optical fiber sensing; a monitoring device connected to the optical fiber cord and configured to perform distributed optical fiber sensing using the optical fiber cord to determine the occurrence of an event; A gas transport system comprising:

4. 4. The gas transport system of claim 3, The gas transport unit comprises: a closure connected to the sheath tube and accommodating the transport tube together with the sheath tube; a gas detection sensor disposed within the closure and configured to detect the gas to be transported; a pressure sensor disposed within the closure and configured to detect pressure within the closure; Furthermore, the gas detection sensor and the pressure sensor are connected to the optical fiber cord; the optical fiber cord further serves as an input / output fiber for the gas detection sensor and the pressure sensor; the monitoring device determines the occurrence of an event based on the output of the gas detection sensor and the output of the pressure sensor. Gas transmission system.

5. 5. The gas transport system of claim 4, The gas transport unit further includes an inert gas supply device that supplies an inert gas to a space formed by the transport pipe, the sheath pipe, and the closure. Gas transmission system.

6. 6. The gas transport system of claim 5, The monitoring device further monitors the pressure and flow rate of the gas to be transported flowing through the transport pipe; - occurrence of an event based on distributed optical fiber sensing using said optical fiber cord; - leakage of the gas to be transported based on the output of the gas detection sensor; - the occurrence of an event based on the output of the pressure sensor; configured to detect at least one of Gas transmission system.

7. 7. The gas transport system according to claim 3, the optical fiber cord is wound around the outside of the transport pipe; Gas transmission system.

8. 7. The gas transport system according to claim 3, The monitoring device The wavelength used for the distributed optical fiber sensing is 1240 nm. Gas transmission system.

Images