Hydrogen supply equipment and hydrogen supply system

Abstract

To provide hydrogen a supply facility and a hydrogen supply system with improved safety in the supply of hydrogen through a conduit.SOLUTION: A hydrogen supply facility includes a conduit which is buried and extends in the ground and through which hydrogen flows, a cladding pipe which covers an outer circumference of the conduit and extends along the conduit, branch pipes which branch from the cladding pipe, and a sensor capable of detecting hydrogen. The branch pipes are provided in a plural number and are separate from each other. Each of the plurality of branch pipes is a pipe extending from the underground to the ground surface and has a first end connected to the cladding pipe and a second end opening above the ground. Each of the plurality of branch pipes is equipped with the sensor. The sensor is provided inside the second end or on the back of a lid covering the second end.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a hydrogen supply facility and a hydrogen supply system.

Background Art

[0002] Technologies for transporting hydrogen have been studied. For example, Patent Document 1 discloses means for monitoring hydrogen leakage when transporting hydrogen from a hydrogen production plant to a hydrogen station using a double pipe. In the leakage monitoring system of Patent Document 1, a hydrogen-nitrogen mixed gas is circulated from the hydrogen production plant to the hydrogen station in the inner pipe of the double pipe, and nitrogen is circulated in the opposite direction between the inner pipe and the outer pipe. In addition, a plurality of hydrogen gas detectors with transmission cables are provided in the space between the inner pipe and the outer pipe.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] As the use of hydrogen spreads, the need for infrastructure for supplying hydrogen is increasing. One object of the present invention is to provide a hydrogen supply facility and a hydrogen supply system with improved safety in the supply of hydrogen through a conduit.

Means for Solving the Problems

[0005] The hydrogen supply equipment according to this disclosure comprises a conduit buried underground and extending underground, through which hydrogen flows; a cladding pipe covering the outer circumference of the conduit and extending along the conduit; branch pipes branching off from the cladding pipe; and a sensor capable of detecting hydrogen. A plurality of the branch pipes are provided spaced apart from each other. Each of the plurality of branch pipes is a pipe extending from underground to the surface and has a first end that connects to the cladding pipe and a second end that opens to the surface. Each of the plurality of branch pipes is provided with the sensor. The sensor is provided inside the second end or on the back surface of a cover that covers the second end.

[0006] The hydrogen supply system according to this disclosure comprises a conduit buried underground and extending underground, a cladding pipe covering the outer circumference of the conduit and extending along the conduit, branch pipes branching off from the cladding pipe, and a sensor capable of detecting hydrogen. The branch pipe is a pipe extending from underground to the surface and has a first end connected to the cladding pipe and a second end opening to the surface. The sensor is provided inside the second end or on the underside of a cover covering the two ends. When hydrogen flows through the conduit, the sensor continuously or intermittently detects the hydrogen concentration. When the sensor detects hydrogen above a specified value, a predetermined signal is transmitted. In response to the signal, the flow of hydrogen through the conduit is shut off. [Effects of the Invention]

[0007] According to the above-mentioned hydrogen supply equipment and hydrogen supply system, the supply of hydrogen through conduits is highly safe. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram showing the hydrogen supply equipment related to this disclosure. [Figure 2] This is a schematic cross-sectional view showing a part of the hydrogen supply equipment related to this disclosure. [Figure 3] This is a schematic diagram showing the hydrogen supply system related to this disclosure. [Figure 4]This graph shows the relationship between the interval between handholes and the sensor detection time. [Figure 5] This graph shows the relationship between the interval between handholes and the sensor detection time. [Figure 6] This graph shows the relationship between the interval between handholes and the sensor detection time. [Figure 7] This graph shows the relationship between the interval between handholes and the sensor detection time. [Modes for carrying out the invention]

[0009] [Summary of the Embodiment] First, we will list and explain the outline of the embodiments. The hydrogen supply equipment according to this disclosure comprises a conduit buried underground and extending underground, through which hydrogen flows; a cladding pipe covering the outer circumference of the conduit and extending along the conduit; branch pipes branching off from the cladding pipe; and a sensor capable of detecting hydrogen. A plurality of the branch pipes are provided spaced apart from each other. Each of the plurality of branch pipes is a pipe extending from underground to the surface and has a first end that connects to the cladding pipe and a second end that opens to the surface. Each of the plurality of branch pipes is provided with the sensor. The sensor is provided inside the second end or on the back surface of a cover that covers the second end.

[0010] To realize a hydrogen-based society, research is being conducted on equipment and methods for supplying hydrogen to locations where it will be used. One method of supplying hydrogen is to transport liquefied hydrogen or hydrogen gas contained in tanks or cylinders on vehicles. However, this method has limitations in terms of transport capacity, and handling high-pressure hydrogen cylinders in ordinary households is difficult from both a legal and safety standpoint. For this reason, methods of supplying hydrogen through conduits are being considered. For example, the hydrogen leak monitoring system described in Patent Document 2 uses a double-walled pipe for safety reasons. Furthermore, a hydrogen-nitrogen mixed gas is circulated through the inner pipe, while nitrogen gas is circulated in the opposite direction through the outer pipe. In addition, multiple hydrogen gas detectors with transmission cables are installed in the space between the inner and outer pipes. However, it is predicted that laying and using the system described in Patent Document 2 as infrastructure over a wide area would incur significant costs, and it was considered that its practicality was not necessarily sufficient. Under these circumstances, the inventors have investigated hydrogen supply equipment and hydrogen supply systems that have improved safety.

[0011] City gas is a type of gas supplied through underground pipelines. As is well known, city gas contains odorants in addition to its main components such as methane, making leaks easier to detect by their odor. The improvement in safety due to the addition of odorants was considered advantageous in terms of cost and versatility. However, adding odorants to hydrogen may cause the odorant components to affect hydrogen-using equipment (e.g., fuel cell equipment). For this reason, it was considered preferable to avoid the use of odorants in hydrogen supply.

[0012] Therefore, the inventors proceeded with their research to improve safety using a hydrogen-sensing sensor and to provide a hydrogen supply system that is practical enough to be implemented as infrastructure. To improve safety, they considered it necessary to have a system that could detect leaks early and release the leaked hydrogen gas. In conducting this research, they realized that the diffusion behavior of hydrogen underground requires consideration of many external factors, and the challenge became to have the hydrogen sensor detect leaked hydrogen gas underground early and reliably.

[0013] The hydrogen supply equipment described in this disclosure comprises a conduit through which hydrogen flows, a cladding pipe covering the outer circumference of the conduit, and multiple branch pipes branching off from the cladding pipe. One end of each branch pipe opens to the ground. A hydrogen sensor is also installed near the ground surface of each branch pipe. With this configuration, it has been demonstrated that if hydrogen leaks from the conduit, the leaked hydrogen travels along the cladding pipe, reaches a branch pipe located near the leak point, and is detected by the sensor. It has also been confirmed that placing the hydrogen sensor near the ground surface ensures safety and facilitates the identification of the leak point. Furthermore, placing the sensor near the ground surface makes it highly practical in terms of sensor maintenance, and also enables communication between the sensor and external equipment (control devices, etc.) using general-purpose technology.

[0014] The cladding tube has an arc-shaped portion at least at its uppermost vertical end in a cross-section perpendicular to its extending direction, and the first end of the branch pipe may be connected to the arc-shaped portion. In this configuration, it has been confirmed that leaked hydrogen is prevented from accumulating in the cladding tube and moves quickly from the cladding tube to the branch pipe and is detected by the sensor. This results in a hydrogen supply system with superior safety.

[0015] The conduit is equipped with multiple shut-off mechanisms spaced apart from each other, and the sensor and the shut-off mechanisms may be able to work in conjunction with each other. With this configuration, it is possible to shut off the flow of hydrogen near the location where a leak occurs. Furthermore, by having the sensor and the shut-off mechanisms work together, the leak can be stopped more quickly. This results in a hydrogen supply system that is safer. In addition, since the flow of hydrogen can continue upstream of the shut-off point, the impact of the leak can be suppressed.

[0016] Furthermore, the hydrogen supply system according to this disclosure comprises a conduit buried underground and extending underground, a cladding pipe covering the outer circumference of the conduit and extending along the conduit, branch pipes branching off from the cladding pipe, and a sensor capable of detecting hydrogen. The branch pipe is a pipe extending from underground to the surface and has a first end connected to the cladding pipe and a second end opening to the surface. The sensor is provided inside the second end or on the back of a cover that covers the two ends. In the hydrogen supply system, when hydrogen flows through the conduit, the sensor continuously or intermittently detects the hydrogen concentration, and when the sensor detects hydrogen above a specified value, a predetermined signal is transmitted. In response to the signal, the flow of hydrogen through the conduit is shut off.

[0017] The hydrogen supply system according to the present disclosure detects a leakage of hydrogen from a conduit by a sensor provided near the ground surface. According to the hydrogen supply system of the present disclosure, when a leakage of hydrogen from the conduit occurs, the leaked hydrogen moves along the coating pipe, reaches a branch pipe located near the leakage point, and is detected by the sensor. It has also been confirmed that by providing the sensor near the ground, safety can be ensured and it is easy to identify the leakage point. Further, by providing the sensor near the ground surface, the sensor is highly practical in terms of maintenance, and it is also possible to communicate between the sensor and external equipment (such as a control device) using general-purpose technology. When the hydrogen level exceeds a predetermined value, the flow of hydrogen is blocked by a notification from the sensor. With this configuration, an increase in the hydrogen concentration can be prevented, and the leaked hydrogen can be safely released into the atmosphere. The hydrogen supply system according to the present disclosure can detect a leakage of hydrogen at an early stage and is a hydrogen supply system with excellent safety.

[0018] A plurality of the branch pipes are provided at intervals in the extending direction of the conduit, and each of the plurality of branch pipes may be provided with the sensor. Further, a plurality of shut-off mechanisms may be provided in the conduit at intervals in the longitudinal direction. When hydrogen exceeding a specified value is detected in any of the sensors, a predetermined signal is transmitted, and a hydrogen leakage point can be predicted corresponding to the signal. Any one of the shut-off mechanisms may operate corresponding to the hydrogen leakage point to block the flow of hydrogen in the conduit. According to these configurations, it is possible to promptly detect the occurrence of a leakage and block the flow of hydrogen near the leakage point. Further, by the sensor and the shut-off mechanism operating in conjunction, the leakage can be stopped more promptly. Therefore, a hydrogen supply system with more excellent safety is obtained. Furthermore, since the flow of hydrogen can be continued upstream of the shut-off point, the influence of the leakage can be suppressed.

[0019] [Specific example of the embodiment] Next, an example of an embodiment of the hydrogen supply facility and the hydrogen supply system according to the present disclosure will be described while referring to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals and their descriptions will not be repeated.

[0020] In the hydrogen supply facility and the hydrogen supply system according to the present disclosure (hereinafter, the hydrogen supply facility and the hydrogen supply system may be collectively referred to as the hydrogen supply facility etc.), the hydrogen supplied may be hydrogen gas that does not contain components arbitrarily added other than hydrogen (hereinafter, may also be referred to as 100% hydrogen gas), or may be a hydrogen-containing gas containing components other than hydrogen. Examples of the components added or mixed with hydrogen include inert gases such as nitrogen gas, organic sulfur compounds such as TBM (tertiary butyl mercaptan), THT (tetrahydrothiophene), and DMS (dimethyl sulfide) used as odorants, and sulfur components such as CH (cyclohexene). Hydrogen is preferably 100% hydrogen gas that does not contain an inert gas or an odorant.

[0021] The hydrogen supplied to the hydrogen supply facility etc. according to the present disclosure can be supplied, for example, through a pipeline from a vaporization facility that vaporizes liquefied hydrogen gas or a hydrogen production plant. Also, it may be transported to a hydrogen station in a state of being stored in a tank and supplied from the hydrogen station to the hydrogen supply facility etc. according to the present disclosure. The installation location of the hydrogen supply facility etc. according to the present disclosure is not particularly limited. For example, the hydrogen supply facility etc. according to the present disclosure may be laid between a hydrogen station and a general house, a building, etc. The hydrogen supply facility etc. according to the present disclosure can be developed as infrastructure. Also, the hydrogen supply facility etc. according to the present disclosure can be laid, for example, as part of factory facilities within a factory site.

[0022] Figure 1 is a schematic diagram of the hydrogen supply equipment according to this disclosure. The outline of the hydrogen supply equipment 1 will be explained with reference to Figure 1. The hydrogen supply equipment 1 comprises a pipeline 11 as a conduit through which hydrogen flows, a cover 21 as a cladding pipe provided on the outer circumference of the pipeline 11, and branch pipes 31 branching off from the cover 21. A governor 61 is provided upstream of the pipeline 11. A tank 62 is connected upstream of the governor 61 via a pipeline 71. The tank 62 may be further connected to a hydrogen production plant or the like via a pipeline. Also, the tank 62 may be a replaceable high-pressure tank. Naturally, in addition to those shown, multiple governors and other devices may be provided.

[0023] Pipeline 11 is a buried pipe that is laid underground and extends underground. The burial depth may be, for example, about 0.6 m to 1.2 m below the surface, and is typically 1 m below the surface. The length of pipeline 11 is not particularly limited as long as it achieves the effects of this disclosure, but may be, for example, several tens of meters to several hundred kilometers. Although pipeline 11 is schematically illustrated in Figure 1, pipeline 11 may have curves and branches.

[0024] The pipeline 11 may be a steel pipe made of stainless steel or carbon steel, or it may be made of a resin pipe made of polyethylene or polyvinyl chloride. A covering material such as nonwoven fabric or jute may be attached to the outer surface of the pipeline 11. The diameter of the pipeline 11 can be appropriately set according to the desired flow rate, for example, the inner diameter may be about 50 mm to 750 mm.

[0025] The cover 21 covers the top of the pipeline 11 and extends along the pipeline 11. Although Figure 1 shows only a portion of the cover 21 for ease of understanding, it is preferable that the cover 21 extends along the entire length of the pipeline 11. The cross-section of the cover 21 perpendicular to the longitudinal direction is semicircular. Multiple branch pipes 31 are connected to the cover 21, and the cover 21 and the branch pipes 31 are in communication with each other.

[0026] In the example shown in Figure 1, the cross-section of the cover 21 is semicircular, but the shape of the cover 21 is not limited to this shape and may be, for example, a hollow cylindrical tube. The cover 21 covers at least the upper part of the outer circumference of the pipeline 11. The upper part of the outer circumference of the pipeline 11 means the part that is vertically above the central axis of the pipeline 11. The cross-sectional shape of the cover 21 preferably has an arc-shaped portion at least at the uppermost part in the vertical direction. The uppermost part in the vertical direction of the cross-sectional shape of the cover 21 means the part of the cross-section of the cover 21 that is at the highest point in the vertical direction. The cross-section of the cover 21 may be semicircular, circular, elliptical, inverted U-shaped, etc. When the cross-section of the cover 21 is semicircular, the part corresponding to the chord may be open or may have a bottom surface. Note that a semicircle does not only mean a mathematically precise half-circle, but also includes shapes composed of an arc-shaped portion and a straight portion that are used as a semicircle in practice.

[0027] When hydrogen gas leaks from a pipeline, the leaked hydrogen gas first moves to the upper part of the space formed between the pipeline and the cover. Initially, a triangular cross-section cover was considered, based on the idea that a narrower top section of the cover would be preferable for efficiently collecting the leaked hydrogen. However, during the demonstration process, it became clear that simply collecting the leaked hydrogen was not sufficient for reliable and early detection of the leak; it was crucial that the leaked hydrogen could move easily within the cover without accumulating. It was then confirmed that with a cover cross-section having an arc-shaped section at least at the top in the vertical direction, the leaked hydrogen could quickly reach the sensor in the handhole, allowing the leak to be detected.

[0028] The material of the cover 21 may be a resin pipe such as polyethylene or polyvinyl chloride, or a steel pipe made of stainless steel or carbon steel. Furthermore, a covering material such as nonwoven fabric or jute may be attached to the outer surface. The diameter of the cover 21 can be selected according to the diameter of the pipeline 11, but may be, for example, 52 mm to 800 mm.

[0029] The branch pipe 31 is connected to the top of the cover 21. Preferably, the branch pipe 31 is connected to the top of the cover 21 in the vertical direction. Of the two ends of the branch pipe 31, the first portion 32 as the first end is connected to the cover 21. The handhole 33 as the second end opens to the ground. The top surface of the handhole 33 may be substantially at the same height as the ground surface, and a part of the handhole 33 may protrude above the ground. The cross-sectional area of ​​the first portion 32 is smaller than the cross-sectional area of ​​the cover 21. The first portion 32 is a cylindrical pipe with a circular cross-section. The handhole 33 may have a larger cross-sectional area than the first portion 32 and may be a box-shaped portion with a square cross-section. The handhole 33 may be made of concrete or resin. The handhole 33 is provided with an openable and closable lid 34. The lid 34 may be manually openable and closable, or it may be provided with an opening and closing mechanism that performs the opening and closing operation based on a signal.

[0030] Multiple branch pipes 31 are provided at intervals from each other in the direction in which the pipeline 11 extends. The spacing between adjacent branch pipes 31 may be the same, or they may be different. For example, the spacing between branch pipes 31 may be smaller near the hydrogen gas supply source than downstream. The spacing at which the branch pipes 31 are provided is not limited as long as it achieves the effects of this disclosure, but may be, for example, 5m to 300m, and preferably 100m to 200m. As an example, when hydrogen gas at 0.1MPa to 1.2MPa (gauge pressure) flows through the pipeline 11, the branch pipes 31 may be installed at intervals of 100m to 300m. If the spacing between branch pipes is too large (for example, one every 3km), it will be difficult to quickly detect hydrogen leaks. There are also concerns about hydrogen gas release from the branch pipes. On the other hand, if the spacing between branch pipes is too small (for example, one every 3m), there are concerns about its practicality as infrastructure. In this regard, the hydrogen supply equipment described herein ensures safety because branch pipes are installed at practical intervals, and in the event of a leak, hydrogen gas can be detected immediately, and hydrogen gas can also be released from the branch pipes.

[0031] A sensor 41 capable of detecting hydrogen is provided on the underside of the cover 34 of the branch pipe 31. The sensor 41 may be installed inside the handhole 33. By installing the sensor 41 inside the branch pipe 31, and especially inside the handhole 33, maintenance is made easier and the reliability of communication with ground equipment is improved.

[0032] The sensor 41 can be any sensor capable of detecting hydrogen, such as a catalytic combustion sensor, a thermal conduction sensor, a semiconductor sensor, or a solid electrolyte sensor. From the viewpoint of reaction rate, responsiveness, etc., a catalytic combustion sensor is preferred. The sensor 41 detects, for example, when the hydrogen concentration exceeds a predetermined value. The predetermined value may be, for example, 100 ppm, 4000 ppm, 40000 ppm, etc. The sensor 41 may also detect fluctuations in hydrogen concentration. For example, it may detect when the fluctuation in hydrogen concentration within a predetermined time (e.g., 1 minute, 10 minutes, 30 minutes, 60 minutes) exceeds a certain value (e.g., 2%, 10%, 30%, 50%). The sensor 41 detects the hydrogen concentration, and the detected value may be evaluated by another device.

[0033] A shut-off valve 51 is provided in the pipeline 11 as a shut-off mechanism. In the example in Figure 1, one shut-off valve 51 is provided for each branch pipe 31, but a ratio of one shut-off valve 51 for multiple branch pipes 31 is also possible. Alternatively, it may be provided at one location upstream of the pipeline 11. The shut-off valve 51 has the function of shutting off the flow of hydrogen in the pipeline 11. The shut-off valve 51 may have a communication function and be capable of shutting off in response to a signal from the sensor 41.

[0034] In addition to the above, the hydrogen supply facility 1 is equipped with various devices to ensure a stable supply of hydrogen and safety. For example, it may be equipped with a flow control valve that can be operated automatically or manually, a pressure regulating valve, measuring instruments such as pressure sensors and thermometers, and associated cables, protective devices, etc.

[0035] Figure 2 is a schematic cross-sectional view perpendicular to the longitudinal direction of pipeline 11 in the hydrogen supply facility 1 according to this disclosure. Pipeline 11 is buried underground. Pipeline 11 may be directly buried underground or it may be covered with a protective member. A cover 21 is placed over the outer circumference of pipeline 11. The cover 21 has a semicircular cross-section. A space S is formed between pipeline 11 and cover 21. If the space S is too large, leaked hydrogen gas will mix with air, and there is a risk that the leakage of hydrogen gas may not be detected promptly. The space S is filled with air at normal pressure.

[0036] The branch pipe 31 includes a first section 32 and a handhole 33. The handhole 33 has an openable and closable lid 34. The first section 32 extends vertically upward from the top of the cover 21 and reaches the ground surface. The first section 32 is a small-diameter pipe with a smaller cross-sectional area than the cover 21. This configuration allows leaked hydrogen to be quickly guided to the location of the sensor 41. The handhole 33 is a rectangular box-shaped section with a larger cross-sectional area than the first section 32. The sensor 41 is installed in the handhole 33. In the example in Figure 3, the sensor 41 is installed on the back surface of the lid 34. In addition to the sensor 41, other measuring instruments, communication equipment, power supplies, etc., may be installed inside the branch pipe 31 or the handhole 33. In addition to the first section 32 and the handhole 33, the branch pipe 31 may also include other components such as connecting members and guide pipes of different diameters.

[0037] Figure 3 is a schematic diagram showing the hydrogen supply system according to this disclosure. The hydrogen supply system 100 according to this disclosure is a system that is operated using the hydrogen supply equipment 1 described above. The same reference numerals are used for the components described, and their explanations are omitted. Here, we will mainly describe the operation of the system.

[0038] The hydrogen supply system 100 may extend over the entire area from the hydrogen supply source, such as a hydrogen station or hydrogen production plant, to the hydrogen usage location, such as a private house, building, or factory, or it may be installed only in a part of the area.

[0039] Referring to Figure 3, in the hydrogen supply system 100, hydrogen gas G flows through pipeline 11 in the direction of the arrow in the figure. The pressure of hydrogen G in pipeline 11 is, for example, 0.1 MPa to 1.2 MPa. Typically, it may be less than 0.1 MPa, or between 0.1 MPa and 1.0 MPa. By keeping it within this range, it is considered possible to supply hydrogen from hydrogen stations to hydrogen usage locations such as ordinary houses. In addition, governors may be installed at multiple locations between the hydrogen station and the hydrogen usage location to adjust the pressure to a predetermined level.

[0040] In the example shown in Figure 3, sensors 41 (s1, s2, s3) are provided in all handholes 33. In another embodiment, a sensor 41 may be installed in each of the multiple handholes 33. For example, handholes with sensors and handholes without sensors may be alternated. The sensors 41 installed in the handholes 33 detect the hydrogen concentration continuously or intermittently. All sensors 41 may perform detection operations, or some of the multiple sensors 41 may be configured to operate.

[0041] Sensor 41 is equipped with wireless communication capabilities. Hydrogen data detected by sensor 41 is transmitted wirelessly. The control device 110, which includes a receiver, receives the hydrogen data. Alternatively, the device including sensor 41 can be equipped with a calculation function, allowing sensor 41 to analyze the hydrogen data and, if necessary, transmit a signal to the control device 110.

[0042] The hydrogen data is analyzed by the sensor 41 or the control device 110. The specific method is not limited, but as an example, if it is detected that the hydrogen concentration is below a predetermined value, or that the fluctuation in hydrogen concentration is below a predetermined fluctuation range, it is determined that there is no abnormality and detection continues. On the other hand, if it is detected that the hydrogen concentration is above a predetermined value, or that the fluctuation in hydrogen concentration is above a predetermined range, a predetermined signal is transmitted. The predetermined signal may be, for example, a leak detection signal, a leak location identification signal, or an emergency shutoff alarm.

[0043] Referring to Figure 3, when a rupture X occurs in pipeline 11, hydrogen gas leaks from the rupture X. The leaked hydrogen diffuses within cover 21. At this time, the leaked hydrogen spreads along the top of cover 21 according to the properties of hydrogen, and then rises within branch pipe 31 located closer to the rupture X. The hydrogen that reaches handhole 33 at the top of branch pipe 31 is detected by sensor s2 as a change in hydrogen concentration. Sensor s2, having detected hydrogen, transmits a predetermined signal.

[0044] The control device 110, upon receiving the signal, determines that it is a signal from sensor s2 among the sensors 41 (s1, s2, s3). The control device 110 estimates the location of the rupture X based on the location information of sensor s2 that transmitted the signal. Based on the estimated location of the rupture X, a shut-off signal is transmitted to shut-off valve b2. Alternatively, when the control device 110 receives a signal from sensor 41, it may close shut-off valve b1 installed at the uppermost part. It also transmits a command to open the cover c2 of the branch pipe 31 corresponding to sensor s2 that transmitted the signal. When cover c2 is opened, the branch pipe 31 is connected to the ground, and the leaked hydrogen diffuses into the atmosphere through the branch pipe 31. This prevents the leaked hydrogen from accumulating in the handhole and increasing the hydrogen concentration. In this way, even if a hydrogen leak occurs, the leaked hydrogen can be quickly released and the hydrogen concentration reduced. Furthermore, the hydrogen leak can be stopped by shutting off pipeline 11.

[0045] (Experimental verification) The effectiveness of the hydrogen supply equipment described in this disclosure was demonstrated by following the procedure described below.

[0046] 1. Consideration of cover shape We considered the shape of the pipeline cover. Assuming it will be used as a pipeline cover, the cross-sectional area is 15,000 mm². 2 Therefore, PVC pipes with semicircular, triangular, and square cross-sectional shapes and a length of 1200 mm were prepared. For the triangular-shaped cover, reinforcing plates were installed at regular intervals at the top to ensure strength. A hydrogen sensor (manufactured by Kyushu Keisokuki Co., Ltd., model number: Hydlog10) was installed at the top of the PVC pipes. Next, hydrogen gas (hydrogen: 3.5%, nitrogen: 96.5%, manufactured by Iwatani Gas Co., Ltd.) was circulated through these PVC pipes at a flow rate of 1 L / min to check the diffusion behavior of hydrogen and whether or not hydrogen was retained. As a result, PVC pipes with a semicircular cross-section showed a shorter hydrogen detection time and no hydrogen accumulation compared to other shapes. Based on the above, it was considered preferable to use a pipe with a semicircular cross-section as a pipeline cover.

[0047] 2. Demonstration of hydrogen supply facilities As a model for the pipeline cover, a semi-circular polyvinyl chloride (VP) pipe with an inner diameter of 194 mm was placed on the ground. The length of the PVC pipe was set to 12 m. Branch pipes extending vertically upward from the pipeline were installed at points 3 m, 5 m, and 8 m from the simulated leak point of the PVC pipe. These distances simulate the spacing of handholes. The branch pipes were shaped like a PVC pipe with an inner diameter of 100 mm (length 895 mm) and a rectangular handhole with sides of 216 mm at the top. A hydrogen gas detector (combustible gas detector XP-3160, manufactured by Shin-Cosmos Electric Co., Ltd.) was installed inside the handhole. The end of a PVC pipe was designated as a simulated leak point, and hydrogen gas (100%) was circulated through the PVC pipe from this simulated leak point at flow rates of 1 L / min, 0.75 L / min, 0.5 L / min, and 0.3 L / min. A hydrogen gas detector installed above the handhole was used to measure the change in hydrogen gas concentration above the handhole. The results for a hydrogen gas flow rate of 1 L / min are shown in [Figure 4]. Referring to [Figure 4], it was confirmed that when the flow rate (simulated leak amount) was 1 L / min, and the pitch spacing was 3, 5, and 8 m, the hydrogen detection amount reached 100 ppm at 1 minute 40 seconds, 4 minutes, and 7 minutes 30 seconds, respectively, from the start of the simulated leak. It was also confirmed that this hydrogen detection amount gradually increased.

[0048] Based on the above results, we considered the optimal spacing of the handholes to achieve more practical hydrogen flow rates and pressures. Specifically, assuming a hydrogen leak point as a 5mm diameter pinhole, the hydrogen gas leakage rate (L / min) was calculated at various pressures from 0.1 MPa to 1.2 MPa. Note that underground temperature fluctuates significantly with the seasons, and gas density also varies accordingly. Therefore, the hydrogen gas leakage rate for each hydrogen gas supply pressure was calculated for both summer (underground temperature 25°C) and winter (underground temperature 5°C). The calculation results are shown in [Table 1].

[0049] [Table 1]

[0050] Assuming a hydrogen leakage rate of 1000 L / min based on the above, the relationship between the handhole installation interval and the time it takes for the hydrogen gas detector installed in the handhole to detect 100 ppm (detection time) was calculated by referring to [Figure 4] and the results for other flow rates. The graph obtained from this simulation is shown in [Figure 5]. Similarly, when assuming a hydrogen leakage rate of 500 L / min, the relationship between the handhole installation interval and the time it takes for the hydrogen gas detector installed in the handhole to detect 100 ppm (detection time) was calculated. The graph obtained from this simulation is shown in [Figure 6].

[0051] Referring to [Figure 5], it was confirmed that if a 5mm diameter hole occurs in the pipeline during hydrogen gas transport at medium pressure (0.1MPa to less than 1.0MPa) and low pressure (less than 0.1MPa), detection can be achieved within 170 seconds (less than 3 minutes) from the start of leakage if, for example, the handholes are spaced 300m apart. Referring to [Figure 6], it was also confirmed that even when the hydrogen leakage rate is 1 / 2 (500L / min), detection can be achieved within 320 seconds (less than 6 minutes) from the start of leakage if, for example, the handholes are spaced 300m apart. Furthermore, referring to [Figure 7], it was confirmed that even when the hydrogen leakage rate is 100L / min, detection can be achieved within 1700 seconds (less than 30 minutes) from the start of leakage if, for example, the handholes are spaced 300m apart. Even when assuming an even smaller hydrogen leakage rate, simulations showed that leakage can be quickly detected if handholes are installed at intervals of approximately 100m. Based on these results, it was concluded that the hydrogen supply equipment described in this disclosure can be used to realize a hydrogen supply system that can promptly detect hydrogen leaks at handhole intervals that are practical for use as infrastructure.

[0052] The embodiments disclosed herein should be understood to be illustrative in all respects and not restrictive in any way. The scope of the invention is indicated by the claims and not in the sense described above, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of symbols]

[0053] 1 Hydrogen supply equipment, 11, 71 Pipeline, 21 Cover, 31 Branch pipe, 33 Handhole, 34 Lid, 41 Sensor, 51 Shut-off valve, 61 Governor, 62 Tank, 100 Hydrogen supply system, 110 Control device

Claims

1. A conduit buried underground, extending underground, through which hydrogen flows, A covering tube that covers the outer circumference of the conduit and extends along the conduit, A branch pipe that branches off from the aforementioned cladding pipe, Equipped with a sensor capable of detecting hydrogen, The aforementioned cladding tube has a semicircular cross-section perpendicular to its direction of extension, and is installed so that the arc of the circle faces upward. The branch pipes are provided in multiple locations along the covering pipe at predetermined intervals and spaced apart from each other. Each of the multiple branch pipes is a pipe extending from underground to the surface, and has a first end that connects to the covering pipe and a second end that has a handhole opening to the ground surface. The sensor is provided within the handhole, The sensor is located inside the handhole or on the underside of the cover that covers the handhole. Hydrogen supply facility.

2. The first end of the branch pipe is connected to the uppermost vertical part of the covering pipe. The hydrogen supply equipment according to claim 1.

3. The conduit is equipped with multiple shut-off mechanisms spaced apart from each other. The sensor and the shut-off mechanism can be linked together. A hydrogen supply system according to claim 1 or claim 2.

4. Conduits buried underground and extending underground, A covering pipe that covers the conduit and extends along the conduit, A branch pipe that branches off from the aforementioned cladding pipe, A sensor capable of detecting hydrogen, Equipped with, The branch pipes are arranged in multiple locations along the cladding pipe at predetermined intervals from each other, and are pipes that extend from underground to the ground surface, each having a first end that connects to the cladding pipe and a second end that has a handhole opening to the ground surface. The sensor is located inside the handhole or on the underside of the cover that covers the handhole. When hydrogen flows through the conduit, the sensor continuously or intermittently detects the hydrogen concentration. When the aforementioned sensor detects hydrogen levels exceeding a specified value, a predetermined signal is transmitted. In response to the aforementioned signal, the flow of hydrogen within the conduit is shut off. Hydrogen supply system.

5. Each of the handholes of the plurality of branch pipes is provided with the sensor, The aforementioned conduit is equipped with a plurality of shut-off mechanisms spaced apart from each other in the longitudinal direction. When any of the aforementioned sensors detects a hydrogen level exceeding a specified value, a predetermined signal is transmitted. In response to the aforementioned signal, the location of the hydrogen leak is predicted. In response to the hydrogen leak location, one of the shut-off mechanisms is activated, and the flow of hydrogen within the conduit is shut off. The hydrogen supply system according to claim 4.

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