Insulated piping, water electrolysis system, and piping damage detection method

Abstract

To improve the robustness of a water electrolysis system.SOLUTION: An insulated piping is composed of a double pipe comprising an inner pipe 130 which connects a water electrolysis stack and an auxiliary machine and inside which a fluid circulates, and an outer pipe 12 which is provided outside the inner pipe 130 via the inner pipe 130 and an outer pipe inner space 14. The outer pipe 12 has insulation properties. In the inner pipe 130, the water electrolysis stack and the auxiliary machine are insulated. A dry gas 13 where humidity is lower than or equal to a prescribed value is enclosed by a pressure of a fluid circulating inside the inner pipe 130 and a pressure higher than an atmosphere pressure in the outer pipe inner space 14 which is a space.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to techniques for an insulated pipe, a water electrolysis system, and a method for detecting damage to a pipe. [Background technology]

[0002] In recent years, with the increase in emissions of greenhouse gases such as carbon dioxide, environmental issues such as global warming and energy issues such as the depletion of petroleum resources have been attracting attention. From this perspective, hydrogen energy has been attracting attention as a clean alternative energy source. However, in order to replace existing fossil fuels with hydrogen energy, a large amount of hydrogen is required.

[0003] One method for producing hydrogen is a water electrolysis device. Known water electrolysis devices use an electrolyte membrane, such as a solid polymer membrane, as a diaphragm. Such water electrolysis devices include a water electrolysis stack. The water electrolysis stack includes a plurality of water electrolysis cells. Each water electrolysis cell has an electrolyte membrane, an anode, and a cathode. The electrolyte membrane is used as a diaphragm in water electrolysis. An anode is provided on one side of the electrolyte membrane. A cathode is provided on the other side of the electrolyte membrane. A voltage for water electrolysis is applied between the anode and cathode of each water electrolysis cell.

[0004] When the electrolyte membrane is a proton-conducting membrane, water on the anode side is electrolyzed, and oxygen is generated on the anode side. + Hydrogen is produced on the cathode side by the ions. Oxygen on the anode side is sent out via piping together with excess water. Meanwhile, the electrolyte membrane is - In the case of an ionic conductive membrane, water on the cathode side is electrolyzed, and hydrogen is generated on the cathode side. - The ions produce oxygen and water on the anode side. The hydrogen on the cathode side is sent to the outside via piping together with the water. The oxygen and water on the anode side are sent to the outside via piping. In a typical water electrolysis stack, the efficiency of converting electricity to hydrogen is around 80-90%, with the remainder being converted to heat and generated.

[0005] With the aim of reducing the cost of hydrogen production, efforts are underway to scale up water electrolysis systems, particularly in Europe, with the introduction of water electrolysis systems with a capacity of 500 GW (gigawatts) expected by 2050. Along with this, it is expected that capital costs will be reduced through the mass production efficiency of the water electrolysis stacks required for hydrogen production. However, DC power supplies, which require high current and low voltage, are used for special purposes, and it is predicted that cost reductions will not progress. Therefore, there is a need to reduce the cost of power supplies.

[0006] Non-Patent Document 1 describes the need to operate multiple water electrolysis stacks with a single power supply in large-scale water electrolysis systems with a capacity of over 20 MW (megawatts) in order to operate the power supply efficiently. Non-Patent Document 1 describes a method for operating multiple water electrolysis stacks simultaneously, in which multiple water electrolysis stacks are electrically connected in series (hereinafter referred to as multi-series connection). By connecting multiple water electrolysis stacks in series to increase the voltage, it becomes possible to use a general large-scale DC power supply. This is thought to enable low-cost, large-scale hydrogen production.

[0007] Patent Document 1 also discloses a method and device for determining the service life of a liquefied hydrogen double pipe, which includes "an inner pipe 2, an outer pipe 3 fitted around the inner pipe 2 at a distance, and a vacuum layer 4 formed between the inner pipe 2 and the outer pipe 3, and which allows liquefied hydrogen 5 to pass through the inside of the inner pipe 2, the device comprising: a pressure sensor 11 which periodically detects a first pressure P1 in the vacuum layer 4 multiple times when liquefied hydrogen is not passing through; and an ECU 13 which controls the pressure sensor 11, the ECU 13 having a rise rate calculation unit 14 which calculates a pressure rise rate k1 in the vacuum layer 4 based on the detected multiple first pressures P1; and a determination unit 15 which determines that the liquefied hydrogen double pipe 1 has reached its service life limit, provided that the calculated pressure rise rate k1 is greater than a first threshold value T1" (see abstract).

[0008] Patent Document 2 discloses a hydrogen leak monitoring system for hydrogen pipes, in which "the conduit for supplying hydrogen is double-piped, a hydrogen-nitrogen mixed gas flows through the inner pipe 4 from the hydrogen production plant 1 to the hydrogen station 2, and nitrogen flows in the opposite direction through the space between the inner pipe 4 and the outer pipe 5, and hydrogen leaks are detected by multiple hydrogen gas detectors 7 with transmission cables 9 installed in the space between the inner pipe 4 and the outer pipe 5, and nitrogen leaks are also detected by multiple nitrogen flow meters 8 installed in the same system flow path, and if a leak is detected in either the inner pipe 4 or the space between the inner pipe 4 and the outer pipe 5, the location or section where the leak was detected is transmitted via the transmission cable 9 to a monitoring center 3, and the flow of the hydrogen-nitrogen mixed gas is shut off in response to a command from the monitoring center 3" (see abstract). [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-20914 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-193810 [Non-patent literature]

[0010] [Non-Patent Document 1] IRENA report, “Green Hydrogen Cost Reduction” [online], [Retrieved September 21, 1992], Internet <URL:https: / / www.irena.org / - / media / Files / IRENA / Agency / Publication / 2020 / Dec / IRENA_Green_hydrogen_cost_2020.pdf> Summary of the Invention [Problem to be solved by the invention]

[0011] When high voltage is applied to a water electrolysis stack in multiple series connections, electrical insulation of the piping between the water electrolysis stack to which high voltage is applied and the auxiliary equipment at ground potential becomes an issue. Here, auxiliary equipment refers to pumps, various tanks, etc. The specifications for insulating piping used in water electrolysis stacks must meet the following requirements: (Z1) The water electrolysis stack generates heat, so the piping must be able to withstand high temperatures of around 60 to 90°C. (Z2) The piping must be able to withstand pressures greater than or equal to the water and gas pressures inside the insulating piping. (Z3) The piping must have low hydrogen permeability. (Z4) The piping must have electrical insulation strength when high voltage is applied.

[0012] Patent Document 1 describes a double-walled pipe made of an inner pipe and an outer pipe made of FRP, with a vacuum between the inner and outer pipes. A vacuum between the inner and outer pipes would actively cause hydrogen circulating within the inner pipe to leak if the inner pipe were to be damaged, making this an inappropriate pressure configuration. In other words, if a vacuum is created between the inner and outer pipes, if the inner pipe is damaged, hydrogen circulating within the inner pipe would spray out onto the vacuum side, i.e., outside the inner pipe.

[0013] Furthermore, Patent Document 2 describes a configuration in which nitrogen flows between the inner and outer tubes. However, Patent Document 2 also clearly states that the pressure between the inner and outer tubes is lower than that of the inner tube, and does not prevent hydrogen flowing through the inner tube from leaking to the outside. Furthermore, because the inner tube is made of a steel pipe, electrical insulation between the water electrolysis stack and the auxiliary equipment cannot be achieved. Even if a non-conductive material is used in part of the inner tube, the insulation performance of that part may be reduced due to the influence of moisture and dust in the nitrogen flowing through the outer tube. Furthermore, such a configuration may make it difficult to achieve a robust insulation design.

[0014] In addition, if the insulating piping for the water electrolysis system is damaged, hydrogen gas may leak. For this reason, it is necessary to quickly detect and identify the damaged part of the insulating piping. In other words, a system control is required that identifies the damaged part and determines whether the water electrolysis system needs to be partially or completely shut down.

[0015] The present invention has been made in view of the above background, and an object of the present invention is to improve the robustness of a water electrolysis system. [Means for solving the problem]

[0016] In order to solve the above-mentioned problems, the present invention provides a double pipe including an inner pipe connecting a water electrolysis stack and an auxiliary device and through which a fluid flows, and an outer pipe provided outside the inner pipe with a space between the inner pipe and the inner pipe, wherein the outer pipe has insulating properties, and the water electrolysis stack and the auxiliary device are insulated by the inner pipe, and a dry gas having a humidity of a predetermined value or less is sealed in the space within the outer pipe at a pressure higher than the pressure of the fluid flowing inside the inner pipe and atmospheric pressure. [Effects of the Invention]

[0017] According to the present invention, the robustness of the water electrolysis system can be improved. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a schematic configuration diagram of a water electrolysis system according to an embodiment of the present invention. [Figure 2] 1 is a schematic diagram illustrating an insulating pipe according to an embodiment of the present invention. [Figure 3] FIG. 2 is a diagram illustrating a hardware configuration of a determination device. [Figure 4] 3 is a flowchart showing the procedure of a method for detecting damage to an insulating pipe performed in this embodiment. [Figure 5] 10 is a flowchart showing another procedure of the method for detecting damage to an insulating pipe performed in this embodiment. [Figure 6] FIG. 10 is a diagram showing a state in which the outer pipe of the insulating pipe is damaged. [Figure 7A] FIG. 10 is a diagram showing a time series of the pressure inside the outer tube measured by the pressure sensor. [Figure 7B] FIG. 2 is a diagram showing a time series of gas concentrations measured by a gas concentration meter. [Figure 8] FIG. 10 is a diagram showing a state in which the insulating tube is damaged. [Figure 9A] FIG. 10 is a diagram showing a time series of the pressure inside the outer tube measured by the pressure sensor. [Figure 9B] FIG. 1 is a diagram (part 1) showing the time series of gas concentrations measured by a gas concentration meter. [Figure 9C] FIG. 2 is a diagram (part 2) showing the time series of gas concentrations measured by a gas concentration meter. [Figure 10] 1 is a diagram showing a configuration of an insulating pipe according to an embodiment of the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0019] Next, modes for carrying out the present invention (referred to as "embodiments") will be described in detail with reference to the drawings as appropriate.

[0020] [Water Electrolysis System Z] FIG. 1 is a schematic diagram of a water electrolysis system Z according to this embodiment. The water electrolysis system Z mainly includes a water electrolysis apparatus 100, a determination device 2, and a control device 3. The water electrolysis apparatus 100 includes a water electrolysis stack 101, a hydrogen gas tank 102, an oxygen gas / water separation tank 103, a water tank 104, and a DC power supply 141. The water electrolysis apparatus 100 also includes a water supply pipe 131, a hydrogen gas pipe 132, and an oxygen gas pipe 133. The water electrolysis apparatus 100 also includes a water pump 111, a heat exchanger 113, a flow rate control valve 112, a power cable 142, and insulating pipes 1a and 1b. The hydrogen gas tank 102, the oxygen gas / water separation tank 103, the water tank 104, the water pump 111, the heat exchanger 113, the flow rate control valve 112, and the like may be referred to as auxiliary equipment, as appropriate.

[0021] The system includes a plurality of water electrolysis stacks 101 that electrolyze water. Water (pure water) is stored in a water tank 104. Water supply piping 131 connects the water tank 104 and the water electrolysis stacks 101, and water flows through the water supply piping 131. The water supply piping 131 includes a main water supply pipe 131a connected to the water tank 104 and branch water supply pipes 131b branching from the main water supply pipe 131a and connected to each water electrolysis stack 101. A water pump 111 is provided in the main water supply pipe 131a, and a flow rate control valve 112 and insulating pipe 1b are provided in each branch water supply pipe 131b.

[0022] The hydrogen gas tank 102 stores hydrogen gas G1 produced as a result of electrolysis. The hydrogen gas pipe 132 connects the water electrolysis stacks 101 and the hydrogen gas tank 102, and hydrogen gas G1 flows through the hydrogen gas pipe 132. The hydrogen gas pipe 132 has hydrogen gas branch pipes 132b connected to each water electrolysis stack 101, and a hydrogen gas main pipe 132a where the hydrogen gas branch pipes 132b join and are connected to the hydrogen gas tank 102.

[0023] Furthermore, the oxygen gas / water separation tank 103, which is an oxygen gas tank, stores oxygen gas G2 produced as a result of electrolysis. The oxygen gas piping 133 connects the water electrolysis stacks 101 and the oxygen gas / water separation tank 103, and oxygen gas G2 flows through it. The oxygen gas piping 133 has oxygen gas branch pipes 133b connected to each water electrolysis stack 101, and an oxygen gas main pipe 133a where the oxygen gas branch pipes 133b join and are connected to the oxygen gas / water separation tank 103.

[0024] The hydrogen gas branch pipe 132b and the oxygen gas branch pipe 133b are each provided with an insulating pipe 1a.

[0025] The DC power supply 141 and each water electrolysis stack 101 are connected in series by a power cable 142 (hereinafter referred to as a multi-series connection). The DC power supply 141 applies a DC voltage to each water electrolysis stack 101.

[0026] At least the hydrogen gas branch pipe 132b and the oxygen gas branch pipe 133b are each provided with an insulating pipe 1a. As will be described later, a pressure sensor 31 (see FIG. 2) is provided in the insulating pipe 1a. As will be described later with reference to FIG. 2, a gas concentration meter 32, which is a gas concentration measuring unit, is provided downstream of the insulating pipe 1a. The determination device 2 detects damage to the insulating pipe 1a based on information collected from the pressure sensor 31 and the gas concentration meter 32.

[0027] 1 , the water electrolysis apparatus 100 may include various measuring devices and control valves. However, these components are omitted in this embodiment to avoid complexity. The control device 3 completely or partially stops the water electrolysis apparatus 100 based on damage detection by the determination device 2. The control device 3 also controls, for example, the water pump 111, the flow rate adjustment valve 112, the DC power supply 141, etc.

[0028] The hydrogen production process by the water electrolysis apparatus 100 is similar to that of a general water electrolysis apparatus. Water (pure water) is supplied from a water tank 104 storing water to the oxygen electrode side of each water electrolysis stack 101 by a water pump 111. As described above, a predetermined current and voltage are applied from the DC power supply 141 to each water electrolysis stack 101 via the power cable 142. In this manner, water is electrolyzed in the water electrolysis stack 101 to generate hydrogen gas G1 and oxygen gas G2.

[0029] The hydrogen gas G1 generated as a result of the electrolysis passes through the hydrogen gas pipe 132, is collected in the hydrogen gas tank 102, and is then supplied to the outside of the water electrolysis apparatus 100. Because the hydrogen gas G1 generated by electrolysis contains moisture equivalent to saturated water vapor, a drying facility (not shown) may be provided in the hydrogen gas pipe 132.

[0030] Furthermore, oxygen gas G2 generated as a result of electrolysis, together with water that was not electrolyzed, passes through oxygen gas piping 133 and is collected in oxygen gas / water separation tank 103. Then, the oxygen gas G2 that has been separated into gas and liquid in oxygen gas / water separation tank 103 is supplied to the outside.

[0031] Furthermore, the water separated into gas and liquid in the oxygen gas / water separation tank 103 is cooled by the heat exchanger 113 and collected in the water tank 104. The conversion efficiency of water electrolysis using electricity in the water electrolysis stack 101 is approximately 80 to 90%, with the remainder being converted into heat. As a result, the temperature of the water after gas-liquid separation becomes high. The heat exchanger 113 is provided to lower the temperature of such water. However, if the oxygen gas pipe 133 is sufficiently long and the water is designed to be naturally cooled while flowing through the oxygen gas pipe 133, the heat exchanger 113 does not need to be provided.

[0032] The water collected in the water tank 104 is supplied again to the water electrolysis stack 101 via the water pump 111 .

[0033] Note that the specifications of a typical water electrolysis stack 101 often stipulate that the conductivity of the water supplied to the water electrolysis stack 101 be controlled to 1 μS / cm or less. Therefore, it is preferable to control the conductivity of the water using a conductivity meter, an ion exchange membrane, or the like (not shown), as necessary. Furthermore, as the electrolysis of water progresses, the amount of water inside the water tank 104 decreases, and therefore water is supplied to the water tank 104 from the outside.

[0034] The water supply pipe 131, the hydrogen gas pipe 132, and the oxygen gas pipe 133 are made of materials that are leak-proof and non-brittle to hydrogen gas G1, oxygen gas G2, and water (collectively referred to as fluids). Such materials include SUS (Steel Use Stainless Steel), polyethylene, and FRP (Fiber Reinforced Plastics) lined with plastic. Considering the leak prevention and robustness of the fluids flowing through the water supply pipe 131, the hydrogen gas pipe 132, and the oxygen gas pipe 133, it is desirable to use SUS for the water supply pipe 131, the hydrogen gas pipe 132, and the oxygen gas pipe 133. When SUS is used for the water supply pipe 131, the hydrogen gas pipe 132, and the oxygen gas pipe 133, the water supply pipe 131, the hydrogen gas pipe 132, and the oxygen gas pipe 133, the pipes become conductive.

[0035] When multiple water electrolysis stacks 101 are connected in series as shown in FIG. 1 , the DC power supply 141 applies a voltage equal to (the voltage applied to each water electrolysis stack 101) × (the number of water electrolysis stacks 101). That is, the DC power supply 141 applies a higher voltage as the number of water electrolysis stacks 101 increases. When auxiliary equipment such as the water supply pipe 131, the hydrogen gas pipe 132, and the oxygen gas pipe 133 are made of conductive materials, the water electrolysis stack 101 is electrically connected to the water tank 104, the hydrogen gas tank 102, the oxygen gas / water separation tank 103, the water pump 111, the flow rate control valve 112, etc. The water tank 104, the hydrogen gas tank 102, the oxygen gas / water separation tank 103, the water pump 111, the flow rate control valve 112, etc. are desirably at ground potential because they may be touched by people. In addition, it is desirable that the water supply pipe 131, hydrogen gas pipe 132, and oxygen gas pipe 133 connected to the water tank 104, hydrogen gas tank 102, oxygen gas / water separation tank 103, water pump 111, flow control valve 112, etc. are also at ground potential.

[0036] For these reasons, insulating pipes 1a and 1b having insulation performance according to the applied voltage are required between the water electrolysis stack 101, to which a high voltage is applied, and the auxiliary machinery, which is at ground potential. The following conditions can be considered as specifications for the insulating pipes 1a and 1b used in the water electrolysis system Z. (A1) The water electrolysis stack 101 generates heat, so it must be able to withstand high temperatures of about 60 to 90°C. (A2) The insulating pipes 1a and 1b must be able to withstand pressures equal to or greater than the water pressure of the water flowing through them and the gas pressure (gas pressure). (A3) The hydrogen gas permeability, oxygen gas permeability, and water permeability are low. (A4) It must have electrical insulation strength when high voltage is applied.

[0037] [Insulated pipe 1a and determination device 2] 2 is a schematic diagram of an insulating pipe 1a according to this embodiment, with reference to FIG. The insulating pipe 1a is composed of an inner pipe 130, an insulating pipe 11, and an outer pipe 12. The inner pipe 130 is the hydrogen gas pipe 132 or oxygen gas pipe 133 shown in FIG. 1, and an inner pipe gas G flows through the inner pipe. The inner pipe gas G is hydrogen gas G1 or oxygen gas G2 (predetermined gas). In other words, the inner pipe 130 connects the water electrolysis stack 101 and the auxiliary equipment, and a fluid flows through the inner pipe. It is assumed that a conductive material such as stainless steel is used for the inner pipe 130. The outline arrow in FIG. 2 indicates the flow direction of the inner pipe gas G.

[0038] The inner pipe 130 is divided into two at a location where the insulating pipe 11 is disposed. The insulating pipe 11 is a joint that connects the two divided inner pipes 130a, 130b and also has insulating properties. In FIG. 2, the inner pipe 130a is connected to the water electrolysis stack 101. As a result, the insulating pipe 11 ensures insulation between the two divided inner pipes 130a, 130b. In this way, the insulating pipe 11 insulates the water electrolysis stack 101 from the auxiliary machinery at the inner pipe 130.

[0039] 2, the outer pipe 12 is provided so as to cover a portion of the insulating pipe 11 and the inner pipe 130. A predetermined space, that is, an outer pipe inner space (space) 14, is provided between the outer pipe 12 and the inner pipe 130 and insulating pipe 11. In this manner, the outer pipe 12 is provided outside the inner pipe 130 with the inner pipe 130 and the outer pipe inner space 14 interposed therebetween. That is, in the insulating piping 1a, the outer pipe 12 and the inner pipe 130 form a double pipe.

[0040] Dry gas 13 (predetermined gas) is sealed in the space 14 inside the outer pipe. The dry gas 13 is made of nitrogen gas, air, or the like, and is insulating (having electrical conductivity below a predetermined value) and has a humidity below a predetermined value. The humidity below a predetermined value means that the humidity is low enough that condensation does not occur in the environment in which the insulating pipe 1 is used.

[0041] The insulating tube 11 is made of a material that is not electrically conductive (has insulating properties) and is not permeable to or brittle with respect to the inner-tube gas G (hydrogen gas G1 or oxygen gas G2). For example, the insulating tube 11 is made of ceramics, plastic-lined FRP, resin such as polyethylene, or rubber. The outer tube 12 is made of an insulating material such as FRP or polyethylene. In other words, materials with electrical conductivity below a predetermined value are used for the insulating tube 11 and the outer tube 12. Because the outer tube 12 is not constantly in contact with the inner-tube gas G, there is no need to consider its permeability to or brittleness with respect to the inner-tube gas G.

[0042] When a high voltage is applied to the water electrolysis stack 101 (see FIG. 1), the inner tube 130a connected to the water electrolysis stack 101 has the same potential as the water electrolysis stack 101. This creates a potential difference between the two ends of the insulating tube 11, which generates a DC electric field. If the insulating tube 11 is exposed, the resulting electric field causes the surface of the insulating tube 11 to attract dust and dirt. As a result, the surface of the insulating tube 11 may become soiled or wet with moisture in the air over a long period of operation. If this occurs, the insulating performance of the insulating tube 11 may be reduced.

[0043] Therefore, in this embodiment, the periphery of the insulating tube 11 is covered with an outer tube 12, and dry gas 13 is sealed in the space 14 inside the outer tube. This prevents the insulating performance of the surface of the insulating tube 11 from deteriorating due to changes in the usage environment.

[0044] The magnitude relationship among the gas pressures of dry gas 13, inner-pipe gas G, and atmosphere is set to be (dry gas 13) > (inner-pipe gas G) > (atmosphere). As described above, in this embodiment, dry gas 13 is sealed so that the gas pressure of dry gas 13 is higher than the gas pressure of inner-pipe gas G (the pressure of the fluid flowing inside inner pipe 130) and atmospheric pressure. If connection 15 between inner pipe 130 and insulating pipe 11 or insulating pipe 11 is damaged, the gas pressure of dry gas 13 can prevent inner-pipe gas G flowing inside inner pipe 130 from immediately leaking out into outer-pipe space 14. In this case, by keeping the difference between the gas pressures of dry gas 13 and inner-pipe gas G small, the time it takes for dry gas 13 to leak into inner pipe 130 can be extended while preventing inner-pipe gas G from leaking into outer-pipe space 14. That is, the time required for the dry gas 13 to be replaced by the inner tube gas G in the outer tube space 14 can be delayed.

[0045] In addition, since the insulating tube 11 and the inner tube 130 are surrounded by the outer tube 12, it is possible to prevent the inner tube gas G from leaking to the surroundings. In this way, it is possible to prevent the flammable inner tube gas G (hydrogen gas G1 or oxygen gas G2) from leaking to the outside of the inner tube 130.

[0046] The insulating pipe 1a according to this embodiment shown in FIG. 2 is provided with a pressure sensor 31 and a gas concentration meter 32 to detect damage to the insulating pipe 1a. The pressure sensor 31, which is a state detection unit and a gas pressure measurement unit, is provided in the outer pipe 12. It measures the pressure (gas pressure) of the dry gas 13 sealed in the outer pipe internal space 14 (detects the state of the dry gas 13). The gas concentration meter 32 is provided in the inner pipe 130 downstream of the insulating pipe 1a and measures the concentration of the gas flowing inside the inner pipe 130. In other words, the gas concentration meter 32 is installed in the inner pipe 130 downstream of the installation location of the outer pipe 12. The gas concentration meter 32 measures the concentration of the inner pipe gas G or the dry gas 13. The gas concentration meter 32 measures the concentration of the inner pipe gas G flowing inside the inner pipe 130 or the concentration of the dry gas 13. The type of gas concentration meter 32 is selected depending on the gas whose concentration is to be measured. Note that "downstream" means downstream with respect to the flow of gas G in the inner pipe.

[0047] 2, it is assumed that the gas concentration meter 32 is installed in the hydrogen gas branch pipe 132b or the oxygen gas branch pipe 133b shown in Fig. 1. However, it may be installed in the hydrogen gas main pipe 132a or the oxygen gas main pipe 133a shown in Fig. 1 as long as it is located downstream of the insulating pipe 11. Furthermore, the gas concentration meter 32 may be installed inside the insulating pipe 1a as long as it is located downstream of the insulating pipe 11.

[0048] The pressure sensor 31 and the gas concentration meter 32 are connected to the determination device 2 , and the measurement results by the pressure sensor 31 and the gas concentration meter 32 are transmitted to the determination device 2 .

[0049] The determination device 2 acquires the gas pressure (state) of the dry gas 13 detected by the pressure sensor 31 and the gas concentration measured by the gas concentration meter 32. Then, based on this information, the determination device 2 detects that damage has occurred in the insulating pipe 1a and identifies the location of the damage. As shown in FIG. 2, the determination device 2 includes an information acquisition unit 21, a pressure determination unit 22, a concentration determination unit 23, and a determination processing unit 24. The information acquiring unit 21 acquires pressure information transmitted from the pressure sensor 31 and concentration information transmitted from the gas concentration meter 32 . The pressure determination unit 22 determines whether the pressure information transmitted from the pressure sensor 31 shows a peculiar change. The concentration determination unit 23 determines whether or not the concentration information transmitted from the gas concentration meter 32 shows any unusual change. As a result of the determination by the pressure determination unit 22 and the concentration determination unit 23, it is determined whether or not the insulating pipe 1 is damaged, and if the insulating pipe 1 is damaged, the location of the damage is identified. Then, the determination processing unit 24 transmits to the control device 3 damage information including the presence or absence of damage and the identified damaged location.

[0050] The details of the processes performed by the information acquisition unit 21, the pressure determination unit 22, the concentration determination unit 23, and the determination processing unit 24 will be described later.

[0051] [Hardware configuration of determination device 2] Fig. 3 is a diagram showing the hardware configuration of the determination device 2. Fig. 1 will be referred to as appropriate. The determination device 2 is a PC (Personal Computer) or the like, and includes a calculation device 202 configured with a memory 201, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), etc. The determination device 2 also includes a storage device 203 configured with an HD (Hard Disk), an SSD (Solid State Drive), etc. The determination device 2 also includes a communication device 204 that collects information from the pressure sensor 31 and the gas concentration meter 32, and transmits the results of the determination made by the determination device 2 to the control device 3 as damage information. The determination device 2 also includes an input device 205 such as a keyboard or a mouse, and an output device 206 such as a display.

[0052] A program is stored in the storage device 203, and this program is loaded into the memory 201. The loaded program is then executed by the arithmetic device 202. This embodies the information acquisition unit 21, pressure determination unit 22, concentration determination unit 23, and determination processing unit 24 shown in FIG.

[0053] [How to determine damage to insulated pipe 1a] 4 is a flowchart showing the procedure of the method for detecting damage to the insulating pipe 1a according to this embodiment, with reference to FIGS. First, the information acquisition unit 21 determines whether the current time is the determination time (S101). The determination time is set at intervals of several seconds. If the current time is not the determination time (S101→No), the determination device 2 returns the process to step S101. If the current time is the determination time (S101→Yes), the pressure determination unit 22 monitors the internal pressure of the outer tube 12 (outer tube internal pressure) measured by the pressure sensor 31 (S102). That is, the pressure determination unit 22 collects information (pressure information) on the pressure of the dry gas 13 (outer tube internal pressure) measured by the pressure sensor 31 for a predetermined time. Step S102 is an outer tube internal state information acquisition step in which the pressure determination unit 22 acquires information on the internal state of the outer tube 12 from the pressure sensor 31.

[0054] The pressure determination unit 22 then determines whether or not an unusual change has occurred in the pressure inside the outer tube based on the collected pressure information (S111). An unusual change in the pressure inside the outer tube is, in particular, a decrease in the pressure inside the outer tube. Specifically, in step S111, the pressure determination unit 22 determines whether or not the pressure of the dry gas 13 measured by the pressure sensor 31 is less than a predetermined value. That is, in step S111, the pressure determination unit 22 determines whether or not the pressure inside the outer tube has decreased by a predetermined value or more based on the acquired time series of the pressure inside the outer tube. If the pressure inside the outer tube 12 has decreased, there is a high possibility that damage has occurred to the insulating tube 11, the connection portion 15, or the outer tube 12. As described above, the magnitude relationship between the gas pressures of the dry gas 13, the inner-tube gas G, and the atmosphere is set to (dry gas 13) > (inner-tube gas G) > (atmospheric pressure). Therefore, a decrease in the pressure inside the outer tube indicates that the dry gas 13 has leaked into the inner tube 130 due to damage to the insulating tube 11 or the connection part 15, or that the dry gas 13 has leaked into the atmosphere due to damage to the outer tube 12.

[0055] If there is no unusual change in the pressure inside the outer tube (S111→No), the determination device 2 returns the process to step S101. If there is an unusual change in the pressure inside the outer tube (S111→Yes), the concentration determination unit 23 monitors the gas concentration using a gas concentration meter (S112). In step S112, the concentration determination unit 23 collects the gas concentration of the dry gas 13 or the gas G inside the inner tube measured by the gas concentration meter 32 installed inside the inner tube 130 for a predetermined time. Step S112 is a gas concentration acquisition step in which the concentration determination unit 23 acquires the gas concentration inside the inner tube 130 from the gas concentration meter 32.

[0056] Then, the concentration determination unit 23 determines whether or not there has been an unusual change in the gas concentration since the start of monitoring the pressure inside the outer tube (S113). As an unusual change in the pressure inside the outer tube, a decrease in the gas concentration inside the inner tube or an increase in the dry gas concentration (concentration ratio) is determined, in particular. Specifically, in step S113, the concentration determination unit 23 determines whether or not the gas concentration measured by the gas concentration meter 32 satisfies a predetermined condition.

[0057] Therefore, in step S113, if there is an unusual change in the gas concentration (S113 → Yes; if the predetermined condition is met), the determination processing unit 24 determines that damage has occurred inside the insulating pipe 1a (inside the outer pipe 12) (S114). When the gas concentration meter 32 measures the concentration of the gas G in the inner pipe, if the concentration of the gas G in the inner pipe measured by the gas concentration meter 32 is equal to or lower than a predetermined value, the determination is "Yes" in step S113 (determined that the predetermined condition is met). Also, when the gas concentration meter 32 measures the concentration of the dry gas 13, if the concentration of the dry gas 13 measured by the gas concentration meter 32 is equal to or higher than a predetermined value, the determination is "Yes" in step S113 (determined that the predetermined condition is met). The damage inside the insulating pipe 1a refers to at least one of the insulating pipe 11 and the connection part 15.

[0058] Furthermore, in step S113, if there is no peculiar change in the gas concentration in the inner tube (S113 → No; predetermined condition is not satisfied), the judgment processing unit 24 judges that damage has occurred to the outer tube 12 (S115). In the case where the gas concentration meter 32 measures the concentration of the gas G in the inner tube, if the concentration of the gas G in the inner tube measured by the gas concentration meter 32 is greater than a predetermined value, "No" is judged in step S113. In the case where the gas concentration meter 32 measures the concentration of the dry gas 13, if the concentration of the dry gas 13 measured by the gas concentration meter 32 is less than a predetermined value, "No" is judged in step S113.

[0059] For example, when the gas concentration meter 32 is measuring the concentration of the inner pipe gas G, a decrease in the concentration (decrease in the concentration ratio) of the inner pipe gas G flowing inside the inner pipe 130 indicates that the dry gas 13 is flowing into the inner pipe 130. Also, when the gas concentration meter 32 is measuring the concentration of the dry gas 13, an increase in the concentration (increase in the concentration ratio) of the dry gas 13 inside the inner pipe 130 indicates that the dry gas 13 is flowing into the inner pipe 130. That is, if there is damage to the insulating pipe 11 of the insulating piping 1a or the connection part 15, the dry gas 13 will flow into the inner pipe 130, causing a decrease in the concentration of the inner pipe gas G and an increase in the concentration of the dry gas 13. On the other hand, even though the determination in step S111 is "Yes," there are cases where it is determined that there is no change in the gas concentration measured by the gas concentration meter 32 ("No" in S113). In such a case, it is indicated that the internal pressure of the outer tube 12 is decreasing even though the dry gas 13 is not flowing into the inner tube 130. In such a case, there is a high possibility that the outer tube 12 is damaged.

[0060] Steps S111, and S113 to S115 are damage detection steps in which the determination device 2 detects that damage has occurred in the insulating pipe 1a based on the state of the dry gas 13 detected by the pressure sensor 31 and the gas concentration measured by the gas concentration meter 32, and identifies the location of the damage.

[0061] The determination processing unit 24 then transmits the determination results from steps S114 and S115 to the control device 3 as damage information (S116). The control device 3 completely or partially stops the water electrolysis device 100 based on the received damage information. In step S116, the determination processing unit 24 outputs information indicating that damage has occurred and information regarding the location of the damage (total loss information). The processing of step S116 is a damage information output step.

[0062] [Variations] 5 is a flowchart showing another procedure of the method for detecting damage to the insulating pipe 1a performed in this embodiment, with reference to FIG. The information acquiring unit 21 collects pressure information of the dry air from the pressure sensor 31 (S201), and also collects concentration information, which is information on the concentration of the gas, from the gas concentration meter 32 (S202). Step S201 is an outer pipe internal state information acquiring step in which the information acquiring unit 21 acquires information on the internal state of the outer pipe 12 from the pressure sensor 31. Step S202 is a gas concentration acquiring step in which the information acquiring unit 21 acquires the gas concentration inside the inner pipe 130 from the gas concentration meter 32. Next, the pressure determination unit 22 determines whether the current time has reached the determination time (S211). The determination time is set at intervals of several seconds. If the current time is not the determination time (S211→No), the determination device 2 returns the process to step S201. If the current time is the determination time (S211→Yes), the pressure determination unit 22 determines whether or not there is an unusual change in the internal pressure of the outer tube 12 (outer tube internal pressure), i.e., the gas pressure of the dry gas 13 (S212). In step S212, the unusual change in the outer tube internal pressure is determined to be, in particular, a decrease in the outer tube internal pressure. Specifically, in step S212, the pressure determination unit 22 determines whether or not the pressure of the dry gas 13 measured by the pressure sensor 31 is less than a predetermined value. The process of step S212 is the same as step S111 in FIG. 4, and therefore a detailed description of step S212 will be omitted.

[0063] If there is no unusual change in the pressure inside the outer tube (S212→No), the determination device 2 returns the process to step S201. If there is an unusual change in the pressure inside the outer tube (S212→Yes), the concentration determination unit 23 determines whether there is an unusual change in the gas concentration measured by the gas concentration meter 32 (S213). The process of step S213 is the same as step S113 in Fig. 4, so a detailed description of the process of step S213 will be omitted. That is, in step S213, the concentration determination unit 23 determines whether the gas concentration measured by the gas concentration meter 32 satisfies a predetermined condition.

[0064] Therefore, in step S213, if there is an unusual change in the gas concentration (S213 → Yes; if the predetermined condition is satisfied), the determination processing unit 24 determines that damage has occurred inside the insulating pipe 1a (inside the outer pipe 12) (S214). The damage inside the insulating pipe 1a refers to at least one of the insulating pipe 11 and the connection part 15. Furthermore, in step S213, if there is no peculiar change in the gas concentration (S213→No; predetermined conditions are not satisfied), the determination processing unit 24 determines that damage has occurred in the outer tube 12 (S215).

[0065] Steps S212 to S215 are damage detection steps in which the determination device 2 detects that damage has occurred in the insulating pipe 1a based on the state of the dry gas 13 detected by the pressure sensor 31 and the gas concentration measured by the gas concentration meter 32, and identifies the location of the damage.

[0066] The determination processing unit 24 then transmits the determination results from steps S214 and S215 to the control device 3 as damage information (S216). The control device 3 completely or partially stops the water electrolysis device 100 based on the received damage information. In step S216, the determination processing unit 24 outputs information indicating that damage has occurred and information regarding the location of the damage (total loss information). The processing of step S216 is a damage information output step.

[0067] Incidentally, the possibility that the outer tube 12 and the insulating tube 11 (or the connection portion 15) are damaged at the same time is low. Therefore, the flowcharts shown in Figures 4 and 5 omit the processing to be performed when the outer tube 12 and the insulating tube 11 (or the connection portion 15) are damaged at the same time.

[0068] Next, with reference to Figures 6 to 9B, examples of time series graphs of pressure and gas concentration when the outer tube 12 is damaged and when the insulating tube 11 is damaged are shown. Next, the processing of steps S102 to S115 in Figure 4 and steps S212 to S215 in Figure 5 will be described in detail.

[0069] [If the outer tube 12 is damaged] First, a case where the outer tube 12 is damaged will be described with reference to Figures 6 to 7B. Figures 6 to 7B correspond to the processing of steps S102 → S111 "Yes" → S112 → S113 "No" → S115 in Figure 4, or steps S212 "Yes" → S213 "No" → S215 in Figure 5.

[0070] FIG. 6 is a diagram showing a state in which the outer pipe 12 of the insulating pipe 1a is damaged. 6 shows a case where a gas leakage point CR occurs in the outer pipe 12 of the insulating pipe 1a. In such a case, the dry gas 13 sealed inside the outer pipe 12 is at a higher pressure than the atmosphere outside the outer pipe 12, so the dry gas 13 leaks toward the atmosphere. That is, a pressure sensor 31 provided in the outer pipe 12 observes a decrease in the gas pressure of the dry gas 13 due to damage to the outer pipe 12. Furthermore, because there is no damage to the insulating pipe 11 or the connection part 15, there is no change in the concentration of the inner pipe gas G flowing inside the inner pipe 130. Therefore, no change in the concentration of the gas (inner pipe gas G and dry gas 13) measured by the gas concentration meter 32 provided downstream of the insulating pipe 1a is observed.

[0071] Next, with reference to FIGS. 7A and 7B, the change in pressure inside the outer tube 12 and the change in concentration inside the inner tube 130 when the outer tube 12 is damaged will be described. 7A is a diagram showing a time series of the pressure inside the outer tube measured by pressure sensor 31, and FIG. 7B is a diagram showing a time series of the concentration of the gas measured by gas concentration meter 32. In FIG. 7B, the gas measured by gas concentration meter 32 may be the gas G inside the inner tube or the dry gas 13. 7A and 7B, time t1 indicates the time when the outer tube 12 is damaged. As shown in Fig. 7A, the measured pressure inside the outer tube (gas pressure of the dry gas 13) decreases from the time (time t1) when the outer tube 12 is damaged. In contrast, as shown in Fig. 7A, time series data is obtained in which the gas concentration measured by the gas concentration meter 32 does not change.

[0072] 7A and 7B correspond to a case where the pressure of the dry gas 13 is less than a predetermined value and the gas concentration measured by the gas concentration meter 32 does not satisfy a predetermined condition. In such a case, the determination device 2 determines that the outer tube 12 is damaged.

[0073] [If the insulating tube 11 is damaged] Next, a case where insulating tube 11 is damaged will be described with reference to Figures 8 to 9C. Figures 8 to 9C correspond to the processing of steps S102 → S111 "Yes" → S112 → S113 "Yes" → S114 in Figure 4, or steps S212 "Yes" → S213 "Yes" → S214 in Figure 5.

[0074] Next, a case where the insulating pipe 11 of the insulating piping 1a is damaged will be described with reference to FIGS. 8, 9A, and 9B. Fig. 8 is a diagram showing a state in which the insulating tube 11 is damaged. In Fig. 8, the same components as those in Fig. 2 are given the same reference numerals and the description thereof will be omitted. As shown in Figure 8, when a gas leakage point CR occurs in the insulating tube 11 of the insulating piping 1a, the dry gas 13 sealed in the outer tube 12 leaks toward the inside of the inner tube 130 because it is at a higher pressure than the gas G in the inner tube. That is, a pressure sensor 31 provided in the outer tube 12 observes a decrease in gas pressure due to damage to the insulating tube 11. Furthermore, downstream of the insulating piping 1a, a mixed gas G10 of the dry gas 13 and hydrogen gas G12 flows. As a result, when the gas concentration meter 32 is measuring the concentration of the gas G in the inner tube, a decrease in the concentration of the gas G in the inner tube is observed by the gas concentration meter 32. Alternatively, when the gas concentration meter 32 is measuring the dry gas 13, an increase in the concentration of the dry gas 13 is observed by the gas concentration meter 32.

[0075] Next, with reference to FIGS. 9A to 9C, a change in the pressure inside the outer tube and a change in the gas concentration inside the inner tube 130 when the outer tube 12 and the insulating tube 11 are damaged will be described. 9A is a diagram showing a time series of the pressure inside the outer tube measured by the pressure sensor 31, and FIGS. 9B and 9C are diagrams showing a time series of the gas concentration measured by the gas concentration meter 32. FIG. 9B, the gas concentration meter 32 measures the concentration of the gas G in the inner pipe, and in FIG. 9C, the gas concentration meter 32 measures the concentration of the dry gas 13. That is, FIG. 9B shows the change in concentration of the gas G in the inner pipe 130, and FIG. 9C shows the change in concentration of the dry gas 13 in the inner pipe 130.

[0076] 9A to 9C, time t2 indicates the time when insulating tube 11 is damaged. As shown in Fig. 9A, the pressure inside the outer tube (gas pressure of dry gas 13) decreases from the time (time t2) when insulating tube 11 is damaged. Also, as shown in Fig. 9B, the gas concentration of inner-tube gas G flowing through inner tube 130 decreases from the time (time t2) when insulating tube 11 is damaged. In this way, when insulating tube 11 is damaged, time-series data of the outer tube pressure and the gas concentration of inner-tube gas G can be obtained as shown in Figs. 9A and 9B.

[0077] 9B shows the case where the gas concentration meter 32 measures the concentration of the gas G in the inner pipe. When the gas concentration meter 32 measures the concentration of the dry gas 13, the concentration of the dry gas 13 increases from time t2 as shown in FIG. 9C.

[0078] 8 to 9C correspond to the case where the pressure of the dry gas 13 is less than a predetermined value and the gas concentration measured by the gas concentration meter 32 satisfies a predetermined condition. In such a case, the determining device 2 determines that damage has occurred inside the outer tube 12.

[0079] Although Figures 8 to 9C show an example in which part of insulating tube 11 is damaged, even if connection portion 15 is damaged, the characteristics of the time series of the pressure inside the outer tube, the gas inside inner tube G inside inner tube 130, and the concentration of dry gas 13 are the same as those shown in Figures 9A to 9C.

[0080] [Insulated piping 1b] FIG. 10 is a diagram showing the configuration of an insulating pipe 1b according to this embodiment. In FIG. 10, the same components as those in FIG. 2 are denoted by the same reference numerals and the description thereof will be omitted. As explained in Fig. 1, the insulating pipe 1b is provided in the water supply pipe 131. Therefore, the inner pipe 130 becomes the water supply pipe 131 through which water W flows. In the insulating pipe 1b shown in Fig. 10, the pressure sensor 31 and the gas concentration meter 32 shown in Fig. 2 are omitted. In addition, the dry gas 13 filled in the outer pipe inner space 14 is sealed at a gas pressure equal to or greater than the pressure of the water W flowing inside the inner pipe 130 (water supply pipe 131).

[0081] By providing such insulating pipe 1b in the water supply pipe 131, it becomes possible to insulate the auxiliary equipment (such as the water pump 111, hydrogen gas tank 102, and oxygen gas / water separation tank 103) via the inner pipe 130. Incidentally, the water W flowing through the water supply pipe 131 is pure water and therefore has low conductivity. Therefore, it is not necessary to consider the conduction of the auxiliary equipment through the water W flowing inside the inner pipe 130 (water supply pipe 131).

[0082] As described above, according to this embodiment, the insulating pipe 11 is surrounded by the outer pipe 12, thereby reducing the effects of humidity and dust on the outer surface of the insulating pipe 11. Furthermore, the dry gas 13 is sealed in the space 14 inside the outer pipe, thereby reducing the effects of humidity on the outer surface of the insulating pipe 11. With this configuration, the insulating pipes 1a and 1b according to this embodiment can easily achieve insulation for the water supply pipe 131, the hydrogen gas pipe 132, and the oxygen gas pipe 133.

[0083] Contamination of the insulating pipe 11 can be prevented either by controlling the air conditioner or air purifier, or by sealing in a controlled dry gas 13 as in the present embodiment. The method of controlling the air conditioner or air purifier increases running costs because the water electrolysis stack 101 operates in a large-scale, high-temperature, and high-humidity environment. The insulating pipes 1a and 1b according to the present embodiment can prevent contamination of the insulating pipe 11 without the need for an air conditioner or air purifier. Therefore, the insulating pipes 1a and 1b according to the present embodiment can prevent contamination of the insulating pipe 11 without increasing running costs for the outer pipe 12, in addition to the outer pipe 12 surrounding the insulating pipe 11.

[0084] Furthermore, when the inner pipe 130 is made of SUS or the like and is conductive, it is necessary to make the inner pipe 130 as long as possible in order to insulate the water electrolysis stack 101 from the auxiliary machinery without installing the insulating pipe 11. By providing the insulating pipes 1a and 1b described in this embodiment in the inner pipe 130, it is possible to insulate the water electrolysis stack 101 from the auxiliary machinery without increasing the length of the inner pipe 130.

[0085] Furthermore, dry gas 13 is sealed in outer tube space 14 so that the outer tube internal pressure (gas pressure of dry gas 13) is higher than the gas pressure of inner tube gas G flowing inside inner tube 130. This makes it possible to prevent inner tube gas G from leaking to the outside even if insulating tube 11 or connection part 15 is damaged.

[0086] Furthermore, a pressure sensor 31 and a gas concentration meter 32 are installed in the insulating pipe 1a.

[0087] The determination device 2 analyzes pressure information transmitted from the pressure sensor 31 and concentration information transmitted from a gas concentration meter 32 provided downstream of the insulating pipe 11. This enables detection of damage to the insulating pipe 1a and easy estimation of the damaged location. The determination processing unit 24 of the determination device 2 transmits the damage information to the control device 3 of the water electrolysis system Z (see FIG. 1 ). Upon receiving the damage information, the control device 3 partially or completely suspends operation of the water electrolysis system Z. In this manner, the determination made by the determination device 2 can be utilized in controlling the water electrolysis system Z. The determination of whether to partially or completely suspend operation of the water electrolysis system Z is determined depending on the installation location and damaged location of the insulating pipe 1a. The method for detecting damage to the insulating pipe 1a described in this embodiment enables detection of the installation location and damaged location of the insulating pipe 1a, and can therefore be utilized in determining the operation of the water electrolysis system Z.

[0088] In this manner, in this embodiment, the gas pressure of the dry gas 13 sealed in the outer pipe space 14, and the gas concentrations of the inner pipe gas G flowing inside the inner pipe 130 and the dry gas 13 are monitored. This makes it possible to easily detect the occurrence of damage to the insulating pipe 1a and the damaged portion.

[0089] Due to these effects, in this embodiment, the robustness of the insulating pipes 1a and 1b and the inner pipe 130 can be improved.

[0090] Furthermore, a humidity sensor may be provided instead of the pressure sensor 31 shown in FIG. 2. Hydrogen gas G1 and oxygen gas G2 generated by water electrolysis are characterized by high humidity. Therefore, when a gas leakage point CR as shown in FIG. 8 occurs, the gas G in the inner tube leaks into the space 14 in the outer tube, causing an increase in humidity of the dry gas 13. Furthermore, the humidity of the dry gas 13 is set to be lower than the humidity of the atmosphere. Therefore, even if the outer tube 12 is damaged as shown in FIG. 8, the humidity of the dry gas 13 increases. In this way, an increase in humidity of the dry gas 13 may be detected instead of the gas pressure of the dry gas 13.

[0091] When a humidity sensor is provided instead of the pressure sensor 31, the determining device 2 determines whether the humidity of the dry gas 13 has increased in step S111 in FIG. 4 or step S212 in FIG.

[0092] Alternatively, a pressure sensor 31 and a humidity sensor may be installed in the outer tube 12. In this case, both the gas pressure and humidity in the outer tube inner space 14 are measured.

[0093] The insulating pipes 1a and 1b may be connected to the inner pipe 130 (water supply pipe 131, hydrogen gas pipe 132, oxygen gas pipe 133) as a female joint or a male joint.

[0094] 1, the insulating pipe 1a is installed in the hydrogen gas branch pipe 132b and the oxygen gas branch pipe 133b, but it may also be installed in the hydrogen gas main pipe 132a or the oxygen gas main pipe 133a. Similarly, the insulating pipe 1b is installed in the water supply branch pipe 131b, but it may also be installed in the water supply main pipe 131a.

[0095] The present invention is not limited to the above-described embodiment, and includes various modifications. For example, the above-described embodiment has been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to an embodiment having all of the described configurations.

[0096] Furthermore, the above-described configurations, functions, units 21 to 24, storage device 203, etc. may be partly or entirely implemented in hardware by, for example, designing them as integrated circuits. Furthermore, as shown in Fig. 3, the above-described configurations, functions, etc. may be implemented in software by a processor such as a CPU interpreting and executing a program that implements each function. Information such as the programs, tables, and files that implement each function can be stored in a memory, a recording device such as an SSD (Solid State Drive), or a recording medium such as an IC (Integrated Circuit) card, an SD (Secure Digital) card, or a DVD (Digital Versatile Disc). In addition, in each embodiment, the control lines and information lines shown are those that are considered necessary for explanation, and not all control lines and information lines in the product are necessarily shown. In reality, it can be considered that almost all components are interconnected. [Explanation of symbols]

[0097] 1a, 1b Insulated piping 2 Judgment device 3. Control device 11 Insulating tube 12 Outer tube 13 Dry gas (specified gas) 14 Outer tube inner space 15 Connection 21 Information Acquisition Department 22 Pressure determination unit 23 Concentration determination section 24 Judgment processing unit 31 Pressure sensor (status detection unit, gas pressure measurement unit) 32 Gas concentration meter (gas concentration measurement section) 100 Water electrolysis equipment 101 Water electrolysis stack 102 Hydrogen gas tank (auxiliary) 103 Oxygen gas / water separation tank (oxygen gas tank, auxiliary equipment) 104 Water tank (auxiliary) 131 Water supply piping 132 Hydrogen gas piping 133 Oxygen gas piping 141 DC power supply 130,130a,130b inner pipe G Gas in the inner pipe (specified gas) G1 Hydrogen gas (specified gas) G2 Oxygen gas (specified gas) G10 mixed gas W water Z Water Electrolysis System S101: Monitoring the pressure inside the outer pipe (step for acquiring information on the status inside the outer pipe) S111: Check whether there is any unusual change in the pressure inside the outer pipe (damage detection step) S112 Gas concentration monitoring (gas concentration acquisition step) S113: Is there any unusual change in gas concentration? (Damage detection step) S114 Damage inside the insulating pipe (damage detection step) S115 Damage to outer tube (damage detection step) S116 Send (damage information output step) S201 Pressure information collection (outer pipe status information acquisition step) S202: Gather gas concentration information (gas concentration acquisition step) S212: Check whether there is any unusual change in the pressure inside the outer pipe (damage detection step) S213: Is there any unusual change in gas concentration? (Damage detection step) S214 Damage inside the insulating pipe (damage detection step) S215 Damage to outer tube (damage detection step) S216 Send (damage information output step)

Claims

1. an inner pipe that connects the water electrolysis stack and the auxiliary equipment and through which a fluid flows; an outer tube provided outside the inner tube with a space between the outer tube and the inner tube; It is composed of a double pipe made up of The outer tube has insulating properties, the inner tube insulates the water electrolysis stack from the auxiliary machinery; A dry gas having a humidity of a predetermined value or less is sealed in the space inside the outer tube at a pressure higher than the pressure of the fluid flowing inside the inner tube and atmospheric pressure. An insulated pipe characterized by:

2. The insulating pipe according to claim 1, The inner tube is divided into two parts, The inner pipe is divided into two parts and is connected to the joint by an insulating tube. An insulated pipe characterized by:

3. The insulating pipe according to claim 2, the fluid is a predetermined gas, a state detection unit that detects a state of the dry gas is provided in the outer tube, A gas concentration measuring unit that measures the concentration of the gas is provided in the inner pipe downstream of the installation location of the insulating pipe. The insulating pipe according to claim 1 .

4. The insulating pipe according to claim 3, The state detection unit is a gas pressure measurement unit that measures the pressure of the dry gas sealed in the space inside the outer tube. An insulated pipe characterized by:

5. The insulating pipe according to claim 3, Hydrogen gas or oxygen gas flows through the inner tube, The gas concentration measuring unit measures the concentration of the hydrogen gas or the oxygen gas flowing inside the inner tube. An insulated pipe characterized by:

6. The insulating pipe according to claim 3, The gas concentration measuring unit measures the concentration of the dry gas. An insulated pipe characterized by:

7. The insulating pipe according to claim 2, The dry gas is composed of nitrogen gas or air. An insulated pipe characterized by:

8. The insulating pipe according to claim 3, The insulating tube is made of ceramic, resin, or rubber. An insulated pipe characterized by:

9. a water tank in which water is stored; a plurality of water electrolysis stacks that electrolyze the water; a hydrogen gas tank for storing hydrogen gas produced as a result of the electrolysis; an oxygen gas tank for storing oxygen gas produced as a result of the electrolysis; a DC power supply that applies a DC voltage to each of the water electrolysis stacks; A determination device; and a water supply pipe that connects the water tank and the water electrolysis stack and through which the water flows; a hydrogen gas pipe connecting the water electrolysis stack and the hydrogen gas tank and through which the hydrogen gas flows; an oxygen gas pipe connecting the water electrolysis stack and the oxygen gas tank and through which the oxygen gas flows; and a water electrolysis system in which at least the hydrogen gas pipe and the oxygen gas pipe are provided with insulating pipes, The insulating piping is an inner pipe which is the hydrogen gas pipe or the oxygen gas pipe; an outer tube provided outside the inner tube with a space between the outer tube and the inner tube; It is composed of a double pipe made up of The outer tube has insulating properties, and the inner tube is divided into two parts, an insulating tube is provided as a joint that connects the two divided inner tubes, and has insulating properties; A dry gas having a humidity of a predetermined value or less is sealed in the space inside the outer tube at a pressure higher than the pressure of the gas flowing inside the inner tube and atmospheric pressure, a state detection unit that detects a state of the dry gas is provided in the outer pipe, and a gas concentration measurement unit that measures a concentration of the gas flowing inside the inner pipe is provided in the inner pipe downstream of an installation location of the insulating pipe, The determination device Based on the state of the dry gas detected by the state detection unit and the concentration of the gas measured by the gas concentration measurement unit, damage to the insulating pipe is detected and the location of the damage is identified. A water electrolysis system characterized by:

10. The water electrolysis system according to claim 9, the state detection unit is a gas pressure measurement unit that measures the pressure of the dry gas sealed in the space inside the outer tube, The determination device determining whether the pressure of the dry gas measured by the gas pressure measuring unit is less than a predetermined value, and determining whether the concentration of the gas measured by the gas concentration measuring unit satisfies a predetermined condition; determining that the outer tube is damaged when the pressure of the dry gas is less than a predetermined value and the concentration of the gas measured by the gas concentration measuring unit does not satisfy a predetermined condition; If the pressure of the dry gas is less than a predetermined value and the concentration of the gas measured by the gas concentration measuring unit satisfies a predetermined condition, it is determined that damage has occurred inside the outer tube. A water electrolysis system characterized by:

11. The water electrolysis system according to claim 10, the gas concentration measuring unit measures the concentration of the hydrogen gas or the oxygen gas flowing inside the inner tube, The determination device When the concentration of the hydrogen gas or the oxygen gas measured by the gas concentration measuring unit is equal to or less than a predetermined value, it is determined that the concentration of the gas satisfies a predetermined condition. A water electrolysis system characterized by:

12. The water electrolysis system according to claim 10, the gas concentration measuring unit measures the concentration of the dry gas; The determination device When the concentration of the dry gas measured by the gas concentration measuring unit is equal to or greater than a predetermined value, it is determined that the concentration of the gas satisfies a predetermined condition. A water electrolysis system characterized by:

13. The water electrolysis system according to claim 9, The determination device Outputting information about the occurrence of the damage and the location of the damage A water electrolysis system characterized by:

14. a water tank in which water is stored; a plurality of water electrolysis stacks that electrolyze the water; a hydrogen gas tank for storing hydrogen gas produced as a result of the electrolysis; an oxygen gas tank for storing oxygen gas produced as a result of the electrolysis; a DC power supply that applies a DC voltage to each of the water electrolysis stacks; A determination device; and a water supply pipe that connects the water tank and the water electrolysis stack and through which the water flows; a hydrogen gas pipe connecting the water electrolysis stack and the hydrogen gas tank and through which the hydrogen gas flows; an oxygen gas pipe connecting the water electrolysis stack and the oxygen gas tank and through which the oxygen gas flows; and At least the hydrogen gas pipe and the oxygen gas pipe are provided with insulating pipes, The insulating piping is an inner pipe which is the hydrogen gas pipe or the oxygen gas pipe; an outer tube provided outside the inner tube with a space between the outer tube and the inner tube; It is composed of a double pipe made up of The outer tube has insulating properties, and the inner tube is divided into two parts, an insulating tube is provided as a joint that connects the two divided inner tubes, and has insulating properties; A dry gas having a humidity of a predetermined value or less is sealed in the space inside the outer tube at a pressure higher than the pressure of the gas flowing inside the inner tube and atmospheric pressure, a state detection unit that detects a state of the dry gas is provided in the outer pipe, and a gas concentration measurement unit that measures a concentration of the gas is provided in the inner pipe downstream of an installation location of the insulating pipe, a determination device for a water electrolysis system, the determination device including: a state detection unit that detects a state of the dry gas in the outer pipe; and a gas concentration measurement unit that measures a concentration of the gas in the inner pipe downstream of an installation location of the outer pipe; an outer pipe internal state information acquisition step of acquiring information about the internal state of the outer pipe from the state detection unit; a gas concentration acquisition step of acquiring the concentration of the gas inside the inner tube from the gas concentration measurement unit; a damage detection step of detecting that damage has occurred in the insulating pipe based on the state of the dry gas detected by the state detection unit and the concentration of the gas measured by the gas concentration measurement unit, and identifying the location of the damage; A method for detecting damage to a pipe, comprising:

15. The pipe damage detection method according to claim 14, the state detection unit is a gas pressure measurement unit that measures the pressure of the dry gas sealed in the space inside the outer tube, The determination device In the damage detection step, determining whether the pressure of the dry gas measured by the gas pressure measuring unit is less than a predetermined value, and determining whether the concentration of the gas measured by the gas concentration measuring unit satisfies a predetermined condition; determining that the outer tube is damaged when the pressure of the dry gas is less than a predetermined value and the concentration of the gas measured by the gas concentration measuring unit does not satisfy a predetermined condition; If the pressure of the dry gas is less than a predetermined value and the concentration of the gas measured by the gas concentration measuring unit satisfies a predetermined condition, it is determined that damage has occurred inside the outer tube. A method for detecting damage to a pipe, comprising:

16. The pipe damage detection method according to claim 15, the gas concentration measuring unit measures the concentration of the hydrogen gas or the oxygen gas flowing inside the inner tube, The determination device When the concentration of the hydrogen gas or the oxygen gas measured by the gas concentration measuring unit is equal to or less than a predetermined value, it is determined that the concentration of the gas satisfies a predetermined condition. A method for detecting damage to a pipe, comprising:

17. The pipe damage detection method according to claim 15, the gas concentration measuring unit measures the concentration of the dry gas; The determination device When the concentration of the dry gas measured by the gas concentration measuring unit is equal to or greater than a predetermined value, it is determined that the concentration of the gas satisfies a predetermined condition. A method for detecting damage to a pipe, comprising:

18. The pipe damage detection method according to claim 14, The determination device a damage information output step of outputting information about the occurrence of the damage and the location of the damage after the damage detection step; A pipe damage detection method comprising:

Images