Hydrogen supply and demand system and hydrogen supply and demand method

Abstract

The present invention provides a hydrogen supply and demand system and a hydrogen supply and demand method that make visible a temporal change in hydrogen concentration in a gas grid to enable monitoring and / or control of appropriate hydrogen concentration. The hydrogen supply and demand system and hydrogen supply and demand method according to the present invention: are for a gas grid provided with a gas pipeline filled with a hydrogen gas and another gas; use gas grid fluid information, pipeline / gas injection mechanism shape information, and hydrogen supply base / gas using base operation schedules as inputs, and output a simulation result considering gas flow, convection due to gas extraction / pressure-filling, and diffusion state; and thus make visible a temporal change in hydrogen concentration at an intended point in the gas grid.

Description

[Technical field]

[0001] The present application relates to a hydrogen supply and demand system and a hydrogen supply and demand method involved in managing and controlling the supply situation when hydrogen produced by electrolysis of water using renewable energy or the reforming of natural gas is supplied to hydrogen users. [Background technology]

[0002] The Ministry of the Environment launched a "Demonstration Project for the Production of Renewable Energy Electrolytic Hydrogen and the Supply and Use of Hydrogen Mixed Gas" in 2019 (https: / / www.env.go.jp / press / 106873-print.html). In this project, hydrogen is produced by electrolysis of water using electricity generated by wind power, and this hydrogen is mixed with a simulated gas equivalent to city gas and supplied to the place of use through gas pipes. The mixed gas can be used directly in water heaters, gas colognes, etc.

[0003] Patent Document 1 provides a city gas supply method for supplying a mixed gas containing hydrogen gas and a hydrocarbon gas to a group of consumers via a pipeline network as a method and system that utilizes existing city gas pipelines and a conduit network to enable the use of both equipment without hindrance when hydrogen fuel equipment and existing city gas combustion equipment coexist, characterized in that in a first group of consumers, hydrogen gas is separated from the mixed gas and the separated hydrogen gas is used and the separated gas is returned to the pipeline network, and in a second group of consumers, hydrogen gas is separated from the mixed gas and the separated gas is used and the separated hydrogen gas is returned to the pipeline network.

[0004] When supplying mixed gases through a gas grid (pipe network), unlike conventional supply of gases with uniform components such as city gas, it is necessary to monitor and manage not only the gas flow rate and pressure but also the concentration of each component in the mixed gas. In addition, the required concentration of each component in the mixed gas differs depending on the specification and use of the mixed gas, and an upper limit on the concentration may also be set.

[0005] Furthermore, if gas usage points (consumers) connected to the gas grid use only specific gases, there is a concern that concentration bias will occur within the gas grid. Because the concentration of each component in a mixed gas fluctuates due to the mixing, diffusion, and flow of gases that accompany the injection and withdrawal of gas, it is necessary to monitor and control the composition within the gas grid, taking into account fluctuations over time.

[0006] Patent Document 1 presents a method and system for supplying a mixed gas to a group of consumers via a gas grid, but does not present any means for monitoring and controlling changes over time in the composition of the mixed gas in the gas grid. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP2002-243100A Summary of the Invention [Problem to be solved by the invention]

[0008] When using hydrogen supplied from a gas grid, the required hydrogen concentration and the upper limit of the hydrogen concentration are determined. Therefore, it is necessary to visualize and control the hydrogen concentration in the gas grid. Regarding hydrogen produced as clean energy, there is a need to solve the hydrogen supply and demand issue while satisfying economic efficiency, safety, convenience, and global warming countermeasures.

[0009] Therefore, an object of the present invention is to provide a hydrogen supply and demand system and a hydrogen supply and demand method that visualize changes in hydrogen concentration over time in a gas grid, thereby enabling appropriate monitoring and control of the hydrogen concentration. [Means for solving the problem]

[0010] The present invention provides a hydrogen supply and demand system for a gas grid having a gas pipeline filled with hydrogen gas and other gases, the system being characterized by comprising a hydrogen concentration visualization system which inputs fluid information within the gas grid, information on the shape of the pipelines and gas injection mechanism, and operation schedules for hydrogen supply bases and gas usage bases, and outputs simulation results that take into account gas flow, convection and diffusion states associated with gas extraction and injection, and visualizes changes in hydrogen concentration over time at any point within the gas grid, and a hydrogen supply and demand method which visualizes changes in hydrogen concentration over time at any point within the gas grid. Effect of the Invention

[0011] The hydrogen supply and demand system and hydrogen supply and demand method of the present invention make it possible to visualize changes in hydrogen concentration over time in a gas grid and monitor and control the hydrogen concentration in the grid for hydrogen produced as clean energy, thereby making it possible to supply hydrogen at the required concentration to needed locations. [Brief description of the drawings]

[0012] [Figure 1] Diagram of a hydrogen supply and demand system equipped with a system for visualizing hydrogen concentrations in the gas grid [Diagram 2] Example screen of a system for visualizing hydrogen concentration in a gas grid [Diagram 3] Example screen of a system for visualizing hydrogen concentration when a gas usage site is newly connected to the gas grid [Figure 4] An explanatory diagram explaining the processing flow of the hydrogen concentration visualization system. [Diagram 5] FIG. 1 is a diagram showing the configuration of a hydrogen supply and demand system equipped with a system for visualizing the hydrogen concentration in a gas grid according to the third embodiment. [Figure 6] Processing flow of the control mechanism described in Example 3 [Figure 7] FIG. 1 is a diagram showing the configuration of a hydrogen supply and demand system equipped with a system for visualizing the hydrogen concentration in a gas grid described in Example 4. [Figure 8]FIG. 13 is a diagram showing the configuration of a hydrogen supply and demand system equipped with a system for visualizing the hydrogen concentration in a gas grid described in Example 5. [Figure 9] FIG. 13 is a diagram showing the configuration of a hydrogen supply and demand system equipped with a system for visualizing the hydrogen concentration in a gas grid described in Example 6. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the same reference numerals are used to designate the same components, and if the description is repeated, the description may be omitted. Furthermore, the present invention is not limited to the following embodiment.

[0014] [Example 1] Fig. 1 is an explanatory diagram illustrating the configuration of a hydrogen supply and demand system equipped with a visualization system for hydrogen concentration in a gas grid according to Example 1. Note that, although this example uses all of the components shown in Fig. 1, it is not necessarily necessary to use all of them, and some of them may be used.

[0015] In this embodiment, a visualization system for hydrogen concentration in a gas grid will be described. Fig. 1 is a schematic diagram of a gas grid and a visualization system for hydrogen concentration in this embodiment. In this embodiment, an example of supplying a mixed gas of natural gas and hydrogen gas to a gas grid in which a hydrogen supply base (2), a gas usage base (3a), and a gas usage base (3b) are connected to a gas pipeline (1) will be described.

[0016] In this embodiment, a mixed gas of natural gas and hydrogen gas is assumed, but the gas to be mixed with hydrogen gas is not limited to natural gas. The number of hydrogen supply bases and gas usage bases may be one or more. The hydrogen supply base (2) refers to facilities and equipment that have the function of supplying hydrogen gas to the gas pipeline (1). In this case, the hydrogen gas at the hydrogen supply base (2) may be produced at the hydrogen supply base (2) or may be produced at another location.

[0017] Hydrogen gas (101) is injected from a hydrogen supply base (2) into a gas pipeline (1) filled with natural gas (102), and the hydrogen gas and natural gas are mixed to produce a mixed gas (103) and supplied to gas consumption bases (3a, 3b). The gas consumption bases (3a, 3b) extract the required amount of hydrogen gas (101), natural gas (102), or mixed gas (103) from the gas pipeline (1), and return the return gas (104) to the gas pipeline (1).

[0018] Here, the return gas (104) is a gas that is not used at the gas consumption bases (3a, 3b). For example, when the gas consumption base (3a) uses only hydrogen, the return gas (104) may be only the natural gas (102), or the natural gas (102) may be mixed with an amount of hydrogen gas (101) other than the amount used, and the resulting gas having a different gas composition from the mixed gas may be returned to the gas pipeline (1) as the return gas.

[0019] The gas grid visualization center (4) is provided in association with the gas grid, and includes a hydrogen concentration visualization system (301) and a control mechanism (302). The hydrogen concentration visualization system (301) in the gas grid calculates the composition distribution in the gas grid using periodically acquired fluid information (201) in the gas grid and previously acquired pipeline and gas injection mechanism shape information (202) as input.

[0020] Here, the fluid information refers to information such as the flow rate, flow rate, pressure, and composition at any point in the gas pipeline (1). The number of any points may be one or more. The fluid information may be measured directly by a sensor such as a pressure gauge or flow meter, or may be calculated by a software sensor. Examples of software sensors include a sensor that calculates the flow rate from the difference in pressure at any two points in a gas grid, or a sensor that calculates the flow rate from the gas consumption at all gas usage points connected to the gas grid.

[0021] Furthermore, the visualization system (301) for hydrogen concentration in the gas grid displays the change in hydrogen concentration over time based on the results of a simulation. The simulation is based on fluid analysis that takes into account gas flow, convection and diffusion caused by gas extraction and injection. The composition distribution in the gas grid after any elapsed time is calculated based on the fluid information (201) in the gas grid, the operation schedule (501) of the hydrogen supply base and the operation schedule (502) of the gas usage base, and the previously acquired information on the shape of the pipeline and gas injection mechanism (202). Note that the composition distribution in the gas grid here refers to the concentration and ratio of each component (hydrogen, natural gas) contained in the gas grid.

[0022] The pipeline and gas injection mechanism shape information refers to information on the shape, pipe diameter, dimensions, etc. of the gas pipeline (1) and the mechanism used for gas injection. The pipeline and gas injection mechanism shape information is used as a condition for fluid analysis in the simulation, and is obtained in advance from gas grid design information, actual measurement results, etc.

[0023] 2 shows an example of a screen (1001) of the visualization system for hydrogen concentration in a gas grid. The visualization system for hydrogen concentration in a gas grid (301) displays a gas grid structure display section (1002) that shows the structure of the gas grid, a grid monitoring section (1003) that shows the hydrogen concentration in the gas grid, and a fluid information display section (1004) that displays fluid information in the gas grid.

[0024] The grid monitoring unit (1003) may always display the hydrogen concentration at any point in a predefined gas grid, or may display the hydrogen concentration at any point specified by the operator with a pointer. Also, a color gradation may be used to visually display the change in hydrogen concentration distribution in the gas grid. Furthermore, in addition to the hydrogen concentration distribution, the gas composition and flow rate may be displayed using a color gradation. Furthermore, the hydrogen concentration in the gas grid may be displayed as a video from the current time until an arbitrary elapsed time, or may be displayed as a still image after an arbitrary elapsed time specified by the operator.

[0025] Here, the gas grid structure display section (1002) and the grid monitoring section (1003) may be displayed overlapping each other. Furthermore, a constraint condition display section (1005) that displays the constraint conditions of the gas usage bases connected to the gas grid may also be displayed together. Furthermore, the amount of hydrogen gas supplied to the gas grid from hydrogen supply bases connected to the gas grid, the amount of hydrogen gas used at the gas usage bases, and the amount of natural gas used may also be displayed together.

[0026] The constraints of a gas usage point are conditions that must be met when supplying a mixed gas, such as the gas composition required at the gas usage point, the upper and lower limits of the hydrogen and natural gas concentrations, the flow rate and pressure of the mixed gas, etc. The constraints of a gas pipeline are conditions that must be met when flowing gas through a gas pipeline (1), such as the gas flow rate and pressure.

[0027] The hydrogen concentration visualization system (301) makes it possible to monitor the distribution of hydrogen concentration in the gas grid in real time, and to confirm whether the constraints of the gas usage points and gas pipelines are being met. The hydrogen concentration visualization system (301) can also be used to select gas usage points or hydrogen supply points to be connected to the gas grid. By comparing the hydrogen concentration distribution in the gas grid before and after the installation of a gas usage point or hydrogen supply point using the hydrogen concentration visualization system in the gas grid (301), it is possible to determine whether the constraints of the gas usage points and gas pipelines are being met.

[0028] Figure 3 shows an example screen of the hydrogen concentration visualization system when a gas consuming base is newly connected to the gas grid. As images of the gas grid structure display unit (1002) and grid monitoring unit (1003), an image (1006) before the gas consuming base is added and an image (1007) after the gas consuming base is added are displayed together, making it possible to compare the structure of the gas pipeline (1) before and after the addition and the hydrogen concentration distribution in the gas grid. It is also possible to display them together so that a comparison can be made in the same way when the connection location of the gas consuming base to the gas grid is changed.

[0029] [Example 2] This embodiment describes the processing flow of the visualization system (301) of hydrogen concentration in a gas grid and the supply feasibility determination mechanism described in embodiment 1. According to this embodiment, it is possible to manage gas so as to satisfy the constraints of the gas usage point or gas pipeline.

[0030] 4 is an explanatory diagram illustrating the process flow of the hydrogen concentration visualization system. The supply availability determination mechanism of the hydrogen concentration visualization system (301) first obtains the number of hydrogen supply bases and gas usage bases connected to the gas grid (S1).

[0031] Next, using the fluid information within the gas grid and the previously acquired information on the geometry of the pipelines and gas injection mechanism as inputs, a simulation is performed that takes into account the gas flow, convection due to gas extraction and injection, and the diffusion state, to calculate the current composition distribution within the gas grid (S2).

[0032] Next, the evaluation time is set (S3). In this embodiment, the evaluation time is set from the current time t1 to tn time in the future, and the evaluation interval is set to Δt.

[0033] Next, the operation schedules of the hydrogen supply base stations and the gas consuming base stations are acquired (S4). Here, the operation schedules are the hydrogen gas injection schedules at the hydrogen supply base stations and the mixed gas extraction schedules at the gas consuming base stations during the set evaluation times t1 to tn.

[0034] The hydrogen gas injection schedule is information such as the amount of hydrogen gas injected by time, injection pressure, injection flow rate, etc. The mixed gas withdrawal schedule is information such as the amount of mixed gas withdrawn by time, withdrawal flow rate, and the usage amount of each component of the mixed gas at the gas usage site.

[0035] The usage amount of each component of the mixed gas at a gas usage point is the usage amount of each component (hydrogen gas, natural gas) contained in the mixed gas. When the mixed gas is used as is at the gas usage point, the total usage amount of each component of the mixed gas at the gas usage point will be the same as the usage amount of the mixed gas. On the other hand, when only specific components are used at the gas usage point, the unused components are returned to the gas pipeline as return gas, so the total usage amount of each component of the mixed gas will be the amount of the mixed gas used minus the amount of returned gas.

[0036] Next, a simulation is performed taking into account the gas flow, convection and diffusion states associated with gas extraction and injection using the mixed gas extraction schedule and previously acquired information on the shape of the piping and gas injection mechanism as inputs, and the return gas schedule for the evaluation times t1 to tn is calculated (S5). Here, the return gas schedule is information such as the amount, return pressure, and return flow rate of the return gas for each component contained in the mixed gas at each time.

[0037] Next, a simulation is performed that takes into account the gas flow, convection and diffusion states associated with gas extraction and injection, and the fluid information in the gas grid at the current time, the hydrogen gas injection schedule, mixed gas extraction schedule, and return gas schedule for the evaluation times t1 to tn, and the previously acquired pipeline and gas injection mechanism shape information, and calculates the composition distribution in the gas grid for the evaluation times t1 to tn (S6 to S9). From the composition distribution in the gas grid for the evaluation period t1 to tn, it is confirmed whether the constraints of the gas usage points and gas pipelines are met.

[0038] If the calculation results show that the constraints of the gas usage location and gas pipeline are met (S9: YES), the hydrogen gas injection schedule, mixed gas extraction schedule, and return gas schedule for the evaluation time t1 to tn can be carried out. On the other hand, if the constraints of the gas usage location and gas pipeline are not met (S9: NO), the hydrogen gas injection schedule, mixed gas extraction schedule, and return gas schedule must be changed based on the composition distribution in the gas grid for the evaluation period t1 to tn.

[0039] For changes to the planned hydrogen gas injection, planned extraction of the mixed gas, and planned return gas, the operator may make a judgment and re - set them, or may adopt the results automatically judged by the supply availability judgment mechanism. For example, by assigning priorities to the following change methods, the supply availability judgment mechanism can make an automatic judgment.

[0040] First, when the hydrogen concentration is insufficient at a specific gas - using site during the evaluation period t1 to tn, there is a method of not extracting the mixed gas at a gas - using site with a lower priority. Also, there is a method of increasing the hydrogen gas injection amount and injection frequency to increase the hydrogen concentration in the gas pipeline and at the gas - using sites.

[0041] In addition, when the mixed gas is directly used at a gas - using site where hydrogen gas is not required, there is a method of using only natural gas at the gas - using site where hydrogen gas is not required and returning the hydrogen gas to increase the hydrogen concentration in the gas pipeline. Further, when the hydrogen concentration is insufficient at a specific gas - using site during the evaluation period t1 to tx (tx < tn), there is a method of delaying the planned extraction of the mixed gas at the specific gas - using site to ensure the concentration of the mixed gas in the gas pipeline and at the gas - using sites.

[0042] [Example 3] In this example, a hydrogen supply - demand system will be described in which a control mechanism (303) for adjusting the hydrogen injection amount and the gas flow rate in the gas pipeline (1) is added to the hydrogen - concentration visualization system (301) in the gas grid described in Example 1, instead of the supply availability judgment mechanism. According to this example, it is possible to adjust the hydrogen injection amount from the hydrogen supply site (2) and the flow rate of the gas pipeline (1), and manage to meet the constraint conditions of the gas - using site or the gas pipeline.

[0043] FIG. 5 is an explanatory diagram illustrating the configuration of a hydrogen supply and demand system equipped with a visualization system for hydrogen concentration in a gas grid according to a third embodiment. In this embodiment, as shown in FIG. 5, a natural gas supply base (5) and a gas discharge base (6) are added to the visualization range of the gas grid described in the first embodiment. Natural gas is supplied from the natural gas supply base (5) to a gas pipeline (1), passes through the gas pipeline (1), and is extracted from the gas discharge base (6). As a result, a gas flow is formed in a fixed direction in the gas pipeline (1).

[0044] The control mechanism (302) sends natural gas supply amount information (401) indicating a control target of the natural gas supply amount to the natural gas supply base (5) to control the amount of natural gas supplied. It also sends hydrogen gas supply amount information (402) indicating a control target of the hydrogen gas supply amount to the hydrogen supply base (2) to control the amount of hydrogen gas supplied. It also sends mixed gas extraction amount information (403) indicating a control target of the mixed gas emission amount to the gas discharge base (6) to control the amount of mixed gas extracted.

[0045] 6 is an explanatory diagram illustrating the process flow of the control mechanism of the hydrogen concentration visualization system. First, the hydrogen concentration visualization system (301) calculates the hydrogen concentration distribution in the gas grid during the evaluation period t1 to tn by the processes (S1) to (S9) in FIG. 4 described in the second embodiment (S10).

[0046] If the control mechanism (302) determines from the composition distribution in the gas grid during the evaluation period t1 to tn that the constraints of the gas usage location and the gas pipeline are not satisfied (S11: YES), the control mechanism (302) controls the hydrogen injection amount and gas flow at the hydrogen supply location to satisfy the constraints of the gas usage location and the gas pipeline.

[0047] Next, the difference ΔVh between the amount of hydrogen gas supplied (integrated value) during the evaluation period t1 to tn and the amount of hydrogen gas used (integrated value) scheduled for the entire gas grid is calculated (S12).

[0048] When the absolute value of the difference ΔVh is equal to or greater than the specified value (THh) (S13: YES), the amount of hydrogen injected at the hydrogen supply base is adjusted.

[0049] If the difference ΔVh is a negative value (hydrogen gas supply amount (accumulated value)>hydrogen gas usage amount (accumulated value)) (S14: negative), the amount of hydrogen injection at the hydrogen supply base is decreased so that the absolute value of ΔVh becomes less than a specified value (S15). If the difference ΔVh is a positive value (hydrogen gas supply amount (accumulated value)<hydrogen gas usage amount (accumulated value)) (S14: positive), the amount of hydrogen injection at the hydrogen supply base is increased so that the absolute value of ΔVh becomes less than a specified value (S16).

[0050] If the absolute value of the difference ΔVh is less than the specified value (THh) and the hydrogen gas concentration exceeds the upper limit in part of the evaluation period or in part of the gas grid (S13: NO), the flow rate of the mixed gas is increased to equalize the hydrogen concentration.

[0051] In this embodiment, the case where the hydrogen gas concentration exceeds the upper limit or is insufficient has been described, but similar control is possible when the natural gas concentration exceeds the upper limit or is insufficient.

[0052] [Example 4] This embodiment describes a case where mixed gas is discontinuously extracted from an end of a gas grid by a tank truck as a gas discharge point in the hydrogen supply and demand system described in the embodiment 3. According to this embodiment, when an imbalance occurs in the gas composition in the gas pipeline (1), the gas flow rate in the gas pipeline (1) can be increased to stabilize the gas composition.

[0053] Fig. 7 is an explanatory diagram illustrating the configuration of a hydrogen supply and demand system equipped with a visualization system for hydrogen concentration in a gas grid according to Example 4. Note that, for the sake of visibility, the operation schedule (501) of the hydrogen supply base and the operation schedule (502) of the gas usage base are omitted in Fig. 7.

[0054] When the mixed gas is to be extracted discontinuously from the end of the gas grid by a tanker truck as a gas discharge point, a schedule for extracting the mixed gas is established so that the flow of the mixed gas in the gas pipeline (1) is maintained. By extracting the mixed gas, the gas flow rate in the gas pipeline (1) increases.

[0055] In this embodiment, it is assumed that the gas consuming points (3a, 3b) connected to the gas grid use hydrogen gas. When hydrogen gas is used at the gas consuming points (3a, 3b), the gas consuming points (3a, 3b) extract the mixed gas from the gas pipeline (1), use the hydrogen gas in the mixed gas, and return the unused natural gas as return gas. By repeating this process, the natural gas concentration in the gas pipeline (1) increases and the hydrogen gas concentration decreases.

[0056] When the gas pipeline (1) is filled with natural gas, hydrogen gas is transported to the gas usage points (3a, 3b) by using gas diffusion in the gas pipeline (1) as a driving force. However, if the gas usage points (3a, 3b) are far from the hydrogen gas supply point (2), diffusion takes time, and there is a risk that the necessary amount of hydrogen gas cannot be supplied to the gas usage points (3a, 3b).

[0057] Therefore, in this embodiment, even when the gas pipeline (1) is filled with natural gas, the gas flow rate in the gas pipeline (1) is increased, and hydrogen gas is transported using gas diffusion and the flow of the mixed gas as the driving force, and the required amount of hydrogen gas is supplied to the gas usage points (3a, 3b). The gas flow rate in the gas pipeline (1) is set according to the mixed gas extraction schedule (203) by the tank truck.

[0058] In this embodiment, the mixed gas is directly extracted by a tank truck, but a gas retention section for temporarily storing the mixed gas may be provided at the gas discharge point. The mixed gas can be extracted into the gas retention section and extracted from the gas retention section by a tank truck at regular intervals, thereby allowing the mixed gas to be extracted continuously.

[0059] The hydrogen concentration visualization system makes it possible to confirm changes in the distribution of hydrogen concentration within the grid by changing the flow rate of the mixed gas, making it possible to check in advance whether the constraints of gas usage points and gas pipelines are met.

[0060] [Example 5] In this embodiment, a case where gas retention points (7a, 7b) are installed in place of the natural gas supply point (5) and the mixed gas discharge point (6) of the gas pipeline (1) in the hydrogen supply and demand system described in the embodiment 3 will be described. According to this embodiment, when an imbalance occurs in the gas composition in the gas pipeline (1), the gas flow rate in the gas pipeline (1) can be continuously changed to stabilize the gas composition.

[0061] Fig. 8 shows an explanatory diagram illustrating the configuration of a hydrogen supply and demand system equipped with a visualization system for hydrogen concentration in a gas grid according to Example 5. Note that, for the sake of visibility, the operation schedule (501) of the hydrogen supply base and the operation schedule (502) of the gas usage base are omitted in Fig. 8.

[0062] In this embodiment, it is assumed that the gas usage points (3a, 3b) connected to the gas grid use hydrogen gas, as in the fourth embodiment. When the mixed gas in the gas grid is used and a gas flow is formed in the gas pipeline (1), natural gas is supplied from the upstream gas retention point (7a).

[0063] When the gas pipeline (1) is filled with natural gas due to the use of hydrogen gas in the gas pipeline (1) at the gas usage points (3a, 3b) and the gas flow slows down, gas is extracted from the gas pipeline (1) using the upstream gas retention point (7a) and natural gas is supplied from the downstream gas retention point (7b), thereby reversing the gas flow direction.

[0064] The control mechanism (302) transmits natural gas supply amount information (401) and mixed gas extraction amount information (403) to the upstream gas retention point (7a) to control the gas flow in the gas pipeline (1). Also, the control mechanism (302) transmits mixed gas extraction amount information (403) and mixed gas backflow amount information (404) indicating a control target of the backflow amount of the mixed gas to the downstream gas retention point (7b) to control the gas flow in the gas pipeline (1).

[0065] This makes it possible to increase the gas flow rate in the gas pipeline (1) according to the amount of hydrogen gas supplied and the amount of mixed gas extracted, when the gas pipeline (1) is filled with natural gas and the gas flow slows down.

[0066] In this embodiment, in addition to the effect of the fourth embodiment, the gas flow rate can be changed continuously, and more precise control of the gas flow rate is possible. By changing the flow rate of the mixed gas using the hydrogen concentration visualization system (301), the change in the distribution of hydrogen concentration in the gas grid can be confirmed, and it can be checked in advance whether the constraints of the gas usage point and the gas pipeline are satisfied.

[0067] [Example 6] In this embodiment, a case will be described in which the gas flow rate is controlled by forming the gas pipeline (1) in a ring shape and providing a pressure adjustment mechanism (8) in the hydrogen supply and demand system described in embodiment 3. According to this embodiment, when an imbalance occurs in the gas composition in the gas pipeline (1), the gas flow rate in the gas pipeline (1) can be continuously changed to stabilize the gas composition.

[0068] Fig. 9 is an explanatory diagram illustrating the configuration of a hydrogen supply and demand system equipped with a visualization system for hydrogen concentration in a gas grid according to Example 6. Note that, for the sake of visibility, the operation schedule (501) of the hydrogen supply base and the operation schedule (502) of the gas usage base are omitted in Fig. 9.

[0069] In this embodiment, the gas grid made of the gas pipeline (1) is formed in a ring shape, and the pressure is controlled by a pressure adjustment mechanism (8), so that the mixed gas is constantly circulating in the gas pipeline (1). Since the mixed gas in the gas pipeline (1) flows in a fixed direction, the hydrogen gas supplied at the hydrogen supply base (2) is transported with both gas diffusion and gas flow as the driving force. This makes the hydrogen gas concentration in the gas pipeline (1) in the gas grid uniform, and makes it possible to supply mixed gas with a stable hydrogen concentration to the gas consumption bases (3a, 3b). [Explanation of symbols]

[0070] 1: Gas pipeline 2: Hydrogen supply base 3a: Gas usage location 1 3b: Gas usage location 2 4: Gas grid visualization center 5: Natural gas supply base 6: Gas emission point 7a: Upstream gas accumulation point 7b: Downstream gas accumulation point 8: Pressure regulator 101: Hydrogen gas 102: Natural gas 103: Mixed gas 104: Return gas 201: Fluid information 202: Pipe and gas injection mechanism shape information 203: Mixed gas extraction by tanker truck 301: Hydrogen concentration visualization system 302: Control mechanism 303: Control mechanism 401: Natural gas supply information 402: Hydrogen gas supply information 403: Mixed gas extraction volume information 404: Mixed gas reverse feed amount information 501: Hydrogen supply station operation schedule 502: Gas usage base operation schedule

Claims

1. A hydrogen supply and demand system comprising a hydrogen concentration visualization system that targets a gas grid having a gas pipeline filled with hydrogen gas and other gases, and inputs fluid information within the gas grid, information on the shape of the pipelines and gas injection mechanisms, and operation schedules for hydrogen supply bases and gas usage bases, and outputs simulation results that take into account gas flow, convection and diffusion states associated with gas extraction and injection, and visualizes changes in hydrogen concentration over time at any point within the gas grid.

2. The hydrogen supply and demand system according to claim 1, A hydrogen supply and demand system, characterized in that the composition of gas in the gas grid is controlled by adjusting at least one of the amount of hydrogen gas injected into the gas grid and the flow rate of gas in the gas pipeline.

3. The hydrogen supply and demand system according to claim 2, A hydrogen supply and demand system, characterized in that the flow rate of gas in the gas pipeline is adjusted by the amount of gas extracted discontinuously from an end of the gas grid.

4. The hydrogen supply and demand system according to claim 2, A hydrogen supply and demand system comprising gas retention points at the beginning and end of the gas grid, and adjusting the gas flow rate in the gas pipeline by supplying gas from the gas retention points or extracting gas to the gas retention points.

5. The hydrogen supply and demand system according to claim 2, A hydrogen supply and demand system comprising an annular gas grid equipped with a pressure adjustment mechanism, and circulating gas in the gas pipeline by controlling the pressure in the tubular gas grid.

6. The hydrogen supply and demand system according to claim 5, A hydrogen supply and demand system, characterized in that the pressure adjustment mechanism controls the flow rate of gas within the annular gas grid.

7. The hydrogen supply and demand system according to claim 1, The hydrogen concentration visualization system is characterized in that it comprises a gas grid structure display unit that shows the structure of the gas grid, a grid monitoring unit that presents the hydrogen concentration within the gas grid, a fluid information display unit that displays fluid information within the gas grid, or a constraint condition display unit that displays the constraint conditions of the gas usage base connected to the gas grid.

8. A hydrogen supply and demand method for a gas grid equipped with gas pipelines filled with hydrogen gas and other gases, which inputs fluid information within the gas grid, information on the shape of the pipelines and gas injection mechanisms, and operation schedules for hydrogen supply bases and gas usage bases, outputs the results of a simulation that takes into account gas flow, convection and diffusion states associated with gas extraction and injection, and visualizes changes in hydrogen concentration over time at any point within the gas grid.

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