Gas Distribution Control System

Abstract

To provide a gas distribution control system which controls distribution of a fuel gas required by a customer while causing the fuel gas including hydrogen gas to pass through a fuel gas conduit grid, with suppressed expansion of the system as a whole.SOLUTION: A system includes: a fuel gas conduit grid through which a fuel gas passes; and a plurality of gas separation adjustment stations for adjustment of separation from the fuel gas. At least one of the gas separation adjustment stations is a gas mixture distribution station. The gas mixture distribution station includes a hydrogen gas concentration measurement mechanism, a hydrogen gas separation mechanism, a gas mixture adjustment mechanism, and a gas return mechanism. The system further includes a gas mixture concentration control mechanism which performs predictive computation and control computation of a hydrogen gas concentration in a gas conduit after predetermined time based on data from the hydrogen gas concentration measurement mechanism and, on the basis of a result of the predictive computation and control computation, gives a control signal to the gas mixture adjustment mechanism to cause the gas mixture adjustment mechanism to increase / decrease the hydrogen gas concentration of the gas mixture in an acceptable variation range.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to technology related to hydrogen utilization / a hydrogen society, and in particular to a system that utilizes an existing city gas pipeline grid as a hydrogen gas supply infrastructure to distribute fuel gas containing hydrogen gas while controlling and distributing the type and concentration of gas desired by each consumer. [Background technology]

[0002] In recent years, hydrogen energy has been attracting attention as a clean alternative energy source in light of environmental issues such as global warming caused by the increase in emissions of greenhouse gases such as carbon dioxide. However, as the hydrogen gas supply infrastructure is still underdeveloped at this stage, various technologies have been proposed to build hydrogen supply infrastructure at low cost and to supply hydrogen safely and stably.

[0003] For example, Patent Document 1 discloses a city gas supply method for supplying gas containing hydrogen gas via a pipeline network, characterized in that the hydrogen gas in the city gas is separated at one or more locations in the pipeline network and then at least a portion of the separated city gas is returned to the pipeline network. It also discloses a hydrogen gas separation and return device comprising: a gas introduction means for branching and introducing hydrogen-containing city gas from a pipeline network; a hydrogen gas separation means for separating hydrogen gas from the city gas; and a separated gas return means for returning at least a portion of the separated gas to the pipeline network.

[0004] According to Patent Document 1, based on the premise of a conventional city gas supply system, a certain amount of hydrogen can be mixed into hydrocarbon gas (natural gas), and conventional city gas appliances and hydrogen-using gas appliances (fuel cells, etc.) that selectively use only hydrogen can be used side by side, enabling a smooth transition to the hydrogen gas supply that is expected in the future. Furthermore, it is said that hydrogen can be supplied to homes, businesses, etc., and that it can provide a hydrogen source for hydrogen-fueled fuel cell vehicles without a dedicated gas station, contributing to the promotion of their widespread use.

[0005] Patent Document 2 discloses a city gas supply method comprising mixing 93 to 75 volume % natural gas, 4 to 12 volume % LP gas, 0 to 9 volume % air or inert gas, and 3 to 14 volume % hydrogen gas to supply hydrogen-mixed city gas that complies with the combustion standards for city gas supplied via pipelines, extracting hydrogen gas from this hydrogen-mixed city gas, and then mixing the mixed city gas with 2 to 11 volume % air or inert gas so that the mixed gas after hydrogen removal complies with the combustion standards for city gas, and returning this mixed gas to the city gas supply pipeline.

[0006] According to Patent Document 2, hydrogen gas can be separated and used at hydrogen gas consumers without the need for large-scale facilities such as city gas reformers, and the city gas after extraction can be used under normal conditions with city gas equipment. Furthermore, hydrogen gas can be transported efficiently, and the city gas after extraction can be used without waste or changes in quality. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2002-213695 A [Patent Document 2] JP 2006-169357 A Summary of the Invention [Problem to be solved by the invention]

[0008] The technologies described in Patent Documents 1 and 2 involve circulating a mixed gas of city gas and hydrogen gas through an existing city gas pipeline grid, and separately supplying either city gas or hydrogen gas according to consumer demand. However, the types of gas consumers desire are not necessarily limited to either city gas or hydrogen gas. In other words, in addition to consumers who desire city gas and consumers who desire hydrogen gas, there are also consumers who desire mixed gas, and the concentration of hydrogen gas in the mixed gas may differ depending on the consumer.

[0009] Hereinafter, in this specification, city gas, hydrogen gas and mixed gas will be collectively referred to as "fuel gas."

[0010] Unfortunately, Patent Documents 1 and 2 do not teach or suggest any means for addressing the above-mentioned problems. Furthermore, as a result of research by the present inventors, it has been found that if a control mechanism for distributing fuel gases of different gas types or concentrations is simply added to the gas supply methods described in Patent Documents 1 and 2, the scale of the control mechanism needs to increase as one moves downstream in the fuel gas conduit grid, which leads to the inconvenience of causing the entire system to become bloated (details will be described later).

[0011] Therefore, an object of the present invention is to provide a gas distribution control system that can circulate fuel gas containing hydrogen gas through a fuel gas conduit grid, control the distribution of fuel gas as desired by consumers, and suppress the expansion of the system as a whole. [Means for solving the problem]

[0012] (I) One aspect of the present invention is a system for separating gas having a composition desired by a consumer group from a fuel gas containing hydrogen gas and distributing the gas to the consumer group, comprising: a fuel gas conduit grid through which the fuel gas flows; a plurality of gas separation and adjustment stations connected to the gas pipes of the fuel gas pipe grid for separating and adjusting gas having a composition desired by the consumer group from the fuel gas; and At least one of the plurality of gas separation and adjustment stations is a mixed gas distribution station for distributing a mixed gas containing hydrogen gas, the mixed gas distribution station comprising: a hydrogen gas concentration measuring mechanism that measures the hydrogen gas concentration of the fuel gas flowing through the gas conduit; a hydrogen gas separation mechanism that separates hydrogen gas from the fuel gas; a mixed gas adjusting mechanism that adjusts the mixed gas to match a fluctuation tolerance range set for a hydrogen gas concentration (reference concentration) desired by the consumer group; a gas return mechanism for returning unused excess gas to the gas conduit; The system comprises: The system further comprises a mixed gas concentration control mechanism that performs a prediction calculation of the hydrogen gas concentration in the gas conduit after a predetermined time based on data from the hydrogen gas concentration measurement mechanism and a control calculation for converging the hydrogen gas concentration, and outputs a control signal to the mixed gas adjustment mechanism to increase / decrease the hydrogen gas concentration of the mixed gas within the allowable fluctuation range based on the results of the prediction calculation and control calculation. The present invention provides a gas distribution control system.

[0013] The present invention allows the following improvements and modifications to be made to the gas distribution control system (I) according to the present invention. (i) The mixed gas concentration control mechanism includes an input / output mechanism for inputting and checking various set values, a hydrogen gas concentration range storage mechanism for storing the allowable fluctuation range of the hydrogen gas concentration, a data storage mechanism for storing the data, a prediction and control calculation mechanism for performing a prediction calculation of the hydrogen gas concentration and a control calculation to converge the hydrogen gas concentration, a prediction and control calculation result storage mechanism for storing the results of the prediction calculation and the control calculation, and a transmission / reception mechanism for receiving the data and transmitting the control signal. (ii) The mixed gas distribution station further comprises a hydrogen storage mechanism for storing the hydrogen gas separated by the hydrogen gas separation mechanism, and a other gas storage mechanism for storing other gases (residual gases) separated by the hydrogen gas separation mechanism. (iii) the fuel gas includes hydrogen gas and city gas; at least one of the plurality of gas separation adjustment stations is a hydrogen gas distribution station for distributing the hydrogen gas, the hydrogen gas distribution station including the hydrogen gas concentration measurement mechanism, the hydrogen gas separation mechanism, the hydrogen gas storage mechanism, and the gas return mechanism; At least one of the plurality of gas separation adjustment stations is a city gas distribution station for distributing the city gas, and the city gas distribution station is equipped with the hydrogen gas concentration measurement mechanism, the hydrogen gas separation mechanism, the other gas storage mechanism, and the gas return mechanism. (iv) A return gas flow rate control mechanism is further provided for controlling the flow rate of the gas return mechanism based on data from the hydrogen gas concentration measurement mechanism. (v) The allowable fluctuation range of the hydrogen gas concentration is defined based on the Wobbe index. (vi) each of the plurality of gas separation and conditioning stations is connected to the gas conduit by a fuel gas inlet pipe and an excess gas return pipe; The hydrogen gas concentration measuring mechanism is connected to both the connection between the fuel gas inlet pipe and the gas conduit and the connection between the surplus gas return pipe and the gas conduit. (vii) the system further comprises a city gas supply facility that supplies pure city gas to the fuel gas pipeline grid, a hydrogen gas supply facility that supplies pure hydrogen gas to the fuel gas pipeline grid, and a fuel gas blending mechanism that blends the fuel gas; The mixed gas concentration control mechanism further has a function of outputting a control signal to the fuel gas blending mechanism to increase / decrease the hydrogen gas concentration in the fuel gas based on the results of the prediction calculation and control calculation.

[0014] In this invention, city gas refers to gas distributed and supplied to each consumer via a pipeline grid, and refers to fuel gas that uses liquefied natural gas as its main raw material and is adjusted to meet the standards of the region in which it is used. For example, city gas in Japan is primarily composed of methane gas (usually about 90%), and also contains ethane gas, propane gas, and butane gas. Nitrogen gas and carbon dioxide gas may also be added to adjust the calorific value. Furthermore, a consumer group refers to a group of consumers who use the same gas type / gas concentration. For example, it may be a group of consumers in a region (such as a town or housing complex) who use the same gas type / gas concentration, or it may be a single business such as a manufacturing plant. [Effects of the Invention]

[0015] According to the present invention, it is possible to provide a gas distribution control system that controls the distribution of fuel gas requested by consumers while circulating fuel gas containing hydrogen gas through a fuel gas conduit grid, while suppressing the expansion of the entire system. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a graph showing the relationship between the hydrogen gas mixing ratio and the Wobbe index WI when hydrogen gas is mixed into Japanese city gas standard 13A. [Figure 2] 1 is a schematic diagram showing an example of the general configuration of a gas distribution control system according to the present invention; [Figure 3A] 1 is a position chart showing an example of changes in hydrogen gas concentration in fuel gas flowing through gas conduits of a fuel gas conduit grid. [Figure 3B] 10 is a position chart showing another example of changes in hydrogen gas concentration in fuel gas flowing through gas conduits of a fuel gas conduit grid. [Figure 4] FIG. 2 is a schematic diagram illustrating a configuration example of a mixed gas concentration control mechanism. [Figure 5A] 10 is an example of a time chart of measurement data of hydrogen gas concentration in fuel gas at a point where the fuel gas passes through a city gas distribution station. [Figure 5B]5B is an example of a time chart of hydrogen gas concentration measurement data and prediction calculation results in fuel gas at a point of a fuel gas inlet pipe of a mixed gas distribution station located downstream of the city gas distribution station of FIG. 5A. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, for mechanisms and configurations that have the same meaning (including cases where the differences are small), the same reference numerals will be used and duplicate explanations will be omitted. Furthermore, the present invention is not limited to the embodiments described here, and can be appropriately combined with known technologies or improved based on known technologies within the scope of the technical concept of the invention.

[0018] First, a brief explanation of fuel gas regulations will be given.

[0019] There are various regulations for fuel gases depending on the country or region where they are used, so that they can be burned safely and stably in a combustor, and combustors are designed, manufactured, and supplied to be optimal for the fuel gases that comply with these regulations. One of the regulations for fuel gases is the Wobbe Index (WI). WI is the total calorific value H (unit: MJ / Nm) per unit volume of fuel gas under standard conditions. 3 It is expressed as "WI = H / √s" by dividing the specific gravity (s) of the fuel gas relative to air by the square root of the specific gravity (s) of the fuel gas relative to air, and is an index that indicates flammability. By expressing it as WI, it is possible to indicate the amount of heat emitted regardless of the type of gas.

[0020] For example, in Japan, city gas standard 13A is "WI = 52.7 to 57.8 MJ / Nm 3 " is specified, and in Germany, the standard for low calorific value gas is "WI = 37.8 to 46.8 MJ / Nm 3 ", and the high calorific value gas standard is "WI=46.1~56.5 MJ / Nm 3 " is specified, and in the UK, "WI = 46.5 to 52.85 MJ / Nm 3The standard conditions in Japan are 0°C and 1 atmosphere, while the standard conditions in Europe are 15°C and 1 atmosphere.

[0021] Here, we estimate the change in WI when hydrogen gas is blended into Japanese city gas standard 13A. Figure 1 is a graph showing the relationship between the hydrogen gas blend ratio and the Wobbe index WI when hydrogen gas is blended into Japanese city gas standard 13A. As shown in Figure 1, the WI monotonically decreases with increasing hydrogen gas blend ratio, reaching a minimum at approximately 85% by volume, and then monotonically increases once the hydrogen gas blend ratio exceeds that level. This calculation shows that if a conventional city gas combustor is used to burn the mixed gas, it must be controlled to fall within the fuel gas standard range in order to function and burn properly. Therefore, the following embodiment describes a system that distributes fuel gas that meets a desired WI or hydrogen gas concentration from a gas pipeline grid to each consumer group.

[0022] [First embodiment] 2 is a schematic diagram showing an example of the general configuration of a gas distribution control system according to the present invention. To simplify the drawing, some of the existing devices / configurations (e.g., odorizers, governors (pressure regulators), various control valves, gas meters, etc.) are omitted. Solid arrows indicate the direction of gas flow, and dotted arrows indicate the direction of communication of measurement data / control signals.

[0023] 2 shows an example in which pure city gas (conventional city gas) is supplied from city gas supply facility 60, pure hydrogen gas (for example, purity of 99.9% or more) is supplied from hydrogen gas supply facility 70, fuel gas is blended in fuel gas blending mechanism 65 to achieve a predetermined hydrogen gas concentration (referred to as the rated concentration), and the fuel gas is supplied to gas pipe 50 of the fuel gas pipe grid, and three gas separation adjustment stations 40a to 40c are connected to gas pipe 50. Each of gas separation adjustment stations 40a to 40c is connected to gas pipe 50 by fuel gas inlet pipe 20 and surplus gas return pipe 25, and is connected to consumer groups 35a to 35c by separated gas supply pipe 30.

[0024] The production of pure city gas and pure hydrogen gas may be performed by conventional means. There are no particular limitations on the type of gas pipeline 50, and it may be a high-pressure pipeline (1.0 MPa or higher in Japan), a medium-pressure pipeline (0.1 MPa or higher but less than 1.0 MPa in Japan), or a low-pressure pipeline (less than 0.1 MPa in Japan). Naturally, the number of gas separation and adjustment stations connected to the gas pipeline 50 is not limited to three. In addition, the separated gas supply pipe 30 of the gas separation and adjustment station is not limited to a direct connection to a group of consumers, and may be connected to a "high-pressure to medium-pressure" or "medium-pressure to low-pressure" pressure adjustment facility.

[0025] Each of the gas separation adjusting stations 40a to 40c is equipped with a hydrogen gas concentration measuring mechanism 45 that measures the hydrogen gas concentration of the fuel gas flowing through the gas conduit 50. The hydrogen gas concentration measuring mechanism 45 may be disposed upstream of the gas flow from the fractionating gas flow control mechanism 10, and may be disposed in the fuel gas inlet pipe 20, at the connection between the gas conduit 50 and the fuel gas inlet pipe 20, or in the gas conduit 50.

[0026] The hydrogen gas concentration measuring mechanism 45 is not limited to a hydrogen gas concentration meter, but may be any mechanism capable of converting the measured value into a hydrogen gas concentration. For example, a Wobbe index meter may be used. Furthermore, the preparative gas flow rate control mechanism 10 is not an essential component, but is preferably installed from the viewpoint of overall system stability and redundancy.

[0027] 2, consumer group 35a connected to gas separation adjusting station 40a is a consumer group that uses pure hydrogen gas, consumer group 35b connected to gas separation adjusting station 40b is a consumer group that uses pure city gas, and consumer group 35c connected to gas separation adjusting station 40c is a consumer group that uses a mixed gas containing city gas and hydrogen gas. Consumer group 35c includes a consumer group that uses a combustor designed and manufactured for mixed gas (a consumer group that actively uses mixed gas) and a consumer group that uses a conventional combustor for city gas (a consumer group that does not encounter any problems even if mixed gas is used).

[0028] The configuration of the gas separation and adjusting station varies slightly depending on the type of gas to be separated and distributed, so the general configuration of each gas separation and adjusting station will be explained below.

[0029] As described above, the gas separation adjustment station 40a is a station (hydrogen gas distribution station) for distributing pure hydrogen gas to the consumer group 35a. The fuel gas taken out through the fuel gas inlet pipe 20 is separated into pure hydrogen gas and other gases (here, pure city gas) by the hydrogen gas separation mechanism 1. There are no particular limitations on the hydrogen gas separation mechanism 1, and conventional hydrogen gas separation means (e.g., separation means using a hydrogen separation membrane) can be used as appropriate. The pure hydrogen gas separated by the hydrogen gas separation mechanism 1 is passed through the gas pressure adjustment mechanism 2 and temporarily stored in the hydrogen gas storage mechanism 3 before being distributed to the consumer group 35a. The hydrogen gas storage mechanism 3 is not an essential component, but is preferably installed from the perspective of absorbing fluctuations in consumption in the consumer group 35a and increasing redundancy.

[0030] The pressure of the surplus gas (city gas in this case) that is not used at the gas separation adjustment station 40a drops due to the amount of separated hydrogen gas, so the pressure is adjusted by the gas return mechanism 5a and returned to the gas pipe 50. At this time, since the surplus gas has a lower hydrogen gas concentration than the separated fuel gas, returning the surplus gas to the gas pipe 50 at a large flow rate may cause large local fluctuations in the component concentration of the fuel gas flowing through the gas pipe 50, which may cause problems in use by the group of consumers located downstream of the gas separation adjustment station 40a on the gas pipe 50.

[0031] Therefore, the gas separation adjusting station 40a is preferably equipped with a return gas flow rate control mechanism 15 that controls the flow rate of the return gas so as to prevent excessive local fluctuations in the component concentration of the fuel gas flowing through the gas conduit 50. There are no particular limitations on the return gas flow rate control, but from the perspective of more accurate control, it is more preferable to further equip the station with an other gas storage mechanism 4 and a hydrogen gas concentration measurement mechanism 45. The hydrogen gas concentration measurement mechanism 45 on the gas return side is preferably disposed downstream of the return gas flow rate control mechanism 15 in the gas flow confluence area with the fuel gas, and may be disposed at the connection between the gas conduit 50 and the surplus gas return pipe 25, or may be disposed in the gas conduit 50.

[0032] The configuration and function of the mixed gas concentration control mechanism 80 will be described later.

[0033] As described above, the gas separation and adjusting station 40b is a station (city gas distribution station) for distributing pure city gas to the consumer group 35b, and has a configuration similar to that of the gas separation and adjusting station 40a.

[0034] Specifically, the fuel gas taken out through the fuel gas inlet pipe 20 is separated into pure hydrogen gas and pure city gas by the hydrogen gas separation mechanism 1. The pure city gas separated by the hydrogen gas separation mechanism 1 passes through the gas pressure adjustment mechanism 2 and is temporarily stored in the city gas storage mechanism 4' before being distributed to the consumer group 35b. The city gas storage mechanism 4' is not an essential component, but it is desirable to install it from the perspective of absorbing fluctuations in consumption in the consumer group 35b and increasing redundancy.

[0035] The pressure of the surplus gas (here, hydrogen gas) that is not used at the gas separation adjustment station 40b drops due to the amount of city gas separated, so the pressure is adjusted by the gas return mechanism 5b and returned to the gas pipeline 50. At this time, since the surplus gas has a lower city gas concentration than the separated fuel gas, returning the surplus gas to the gas pipeline 50 at a large flow rate may cause large local fluctuations in the component concentration of the fuel gas flowing through the gas pipeline 50, which may cause problems with use by the group of consumers located downstream of the gas separation adjustment station 40b on the gas pipeline 50.

[0036] Therefore, it is preferable that the gas separation adjustment station 40b also be equipped with a return gas flow rate control mechanism 15 that controls the flow rate of the return gas so as to prevent excessive local fluctuations in the component concentration of the fuel gas flowing through the gas conduit 50. There are no particular limitations on the control of the return gas flow rate, but from the perspective of more accurate control, it is more preferable to further equip the station with a hydrogen gas storage mechanism 3 and a hydrogen gas concentration measurement mechanism 45. The arrangement of the hydrogen gas concentration measurement mechanism 45 on the gas return side is the same as in the case of the gas separation adjustment station 40a.

[0037] As mentioned above, the gas separation adjustment station 40c is a station (mixed gas distribution station) for distributing mixed gas containing hydrogen gas (here, mixed gas containing city gas and hydrogen gas) to the consumer group 35c, and has a more complex configuration than the previous gas separation adjustment stations 40a to 40b.

[0038] Specifically, a portion of the fuel gas taken out through the fuel gas inlet pipe 20 is separated into hydrogen gas and other gases (here, city gas) by the hydrogen gas separation mechanism 1. The hydrogen gas separated by the hydrogen gas separation mechanism 1 passes through the gas pressure adjustment mechanism 2 and is temporarily stored in the hydrogen gas storage mechanism 3, and the separated other gases pass through the gas pressure adjustment mechanism 2 and are temporarily stored in the other gas storage mechanism 4 (here, essentially the city gas storage mechanism 4').

[0039] Another portion of the fuel gas separated by the fuel gas inlet pipe 20, the hydrogen gas stored in the hydrogen gas storage mechanism 3, and the city gas stored in the other gas storage mechanism 4 are adjusted in the mixed gas adjustment mechanism 7 to a mixed gas having the hydrogen gas concentration desired by the consumer group 35c, and then distributed to the consumer group 35c. From the viewpoint of absorbing fluctuations in consumption in the consumer group 35c and increasing redundancy, it is desirable that the mixed gas adjustment mechanism 7 further include a mixed gas storage mechanism 8, although this is not an essential configuration.

[0040] In the gas separation adjustment station 40c, the mixed gas is adjusted by the mixed gas adjustment mechanism 7, so as long as the hydrogen gas concentration of the mixed gas can be appropriately controlled, it is not necessary for the hydrogen gas separation mechanism 1 to completely separate the mixed gas into pure hydrogen gas and pure city gas. For example, if the mixed gas adjustment mechanism 7 is equipped with a hydrogen gas concentration measurement mechanism and can appropriately control the flow rates of each gas used for adjustment, the hydrogen separation capacity of the hydrogen gas separation mechanism 1 of the gas separation adjustment station 40c may be lower than that of the hydrogen gas separation mechanisms 1 of the gas separation adjustment stations 40a-40b (for example, separation at a purity of 90% or higher is sufficient). In this case, there is an advantage that the equipment cost and operating cost of the hydrogen gas separation mechanism 1 of the gas separation adjustment station 40c can be lower than those of the gas separation adjustment stations 40a-40b. Naturally, the hydrogen gas may be completely separated into pure hydrogen gas and pure city gas by the hydrogen gas separation mechanism 1.

[0041] Excess gas not used in the gas separation adjusting station 40c is pressure-adjusted by a gas return mechanism 5c and returned to the gas conduit 50. The gas return mechanism 5c preferably includes a return gas flow rate control mechanism 15 that controls the flow rate of the returned gas so as to prevent excessive local fluctuations in the component concentration of the fuel gas flowing through the gas conduit 50. There are no particular limitations on the control of the return gas flow rate, but from the perspective of more accurate control, it is more preferable to further include a hydrogen gas concentration measurement mechanism 45. The arrangement of the hydrogen gas concentration measurement mechanism 45 on the gas return side is the same as in the gas separation adjusting station 40a.

[0042] Next, the configuration and function of the mixed gas concentration control mechanism 80 will be described.

[0043] First, in order to understand the significance / necessity of the mixed gas concentration control mechanism 80, the following description will be given assuming a state in which the mixed gas concentration control mechanism 80 is not present. As an example, although not shown, it is assumed that the mixed gas concentration control mechanism 80 is not provided in Fig. 2, another mixed gas distribution station 40d is further connected downstream of the gas separation adjustment station 40c (mixed gas distribution station) on the gas conduit 50, and the mixed gas distribution stations 40c and 40d are gas separation adjustment stations that distribute mixed gases having different hydrogen gas concentrations.

[0044] 3A is a position chart showing an example of changes in the hydrogen gas concentration in the fuel gas flowing through the gas conduit 50 of the fuel gas conduit grid. As shown in FIG. 3A, fuel gas that has been blended in the fuel gas blending mechanism 65 to have a predetermined hydrogen gas concentration (rated concentration) flows from the fuel gas blending mechanism 65 to the gas separation adjustment station 40a (hydrogen gas distribution station).

[0045] Since only hydrogen gas is separated and distributed in the gas separation adjustment station 40a (hydrogen gas distribution station), the hydrogen gas concentration in the fuel gas flowing through the gas conduit 50 drops significantly after passing through the gas separation adjustment station 40a.

[0046] Next, since only city gas is separated and distributed at gas separation adjustment station 40b (city gas distribution station) (due to a decrease in the city gas concentration), the hydrogen gas concentration in the fuel gas flowing through gas conduit 50 increases significantly after passing through gas separation adjustment station 40b. At this time, the extent to which the hydrogen gas concentration in the fuel gas increases depends on the ratio of the separated gas flow rate and return gas flow rate at gas separation adjustment station 40a (hydrogen gas distribution station) to the separated gas flow rate and return gas flow rate at gas separation adjustment station 40b (city gas distribution station). Figure 3A shows a case where the separated gas flow rate and return gas flow rate at gas separation adjustment station 40b are smaller than those at gas separation adjustment station 40a.

[0047] The next gas separation and adjustment station 40c (mixed gas distribution station) separates and distributes mixed gas at a rated concentration. In the present invention, the hydrogen gas concentration desired by the mixed gas consumer group is referred to as the reference concentration. In other words, in the gas separation and adjustment station 40c, "reference concentration = rated concentration" is meant.

[0048] As shown in Figure 3A, if the hydrogen gas concentration of the fuel gas that reaches the gas separation adjustment station 40c does not meet the standard concentration (here, the rated concentration), the hydrogen gas is preferentially / actively separated to meet the desired standard concentration, and the hydrogen gas concentration in the fuel gas decreases after passing through the gas separation adjustment station 40c.

[0049] The next gas separation adjustment station 40d (mixed gas distribution station) separates and distributes mixed gas with a hydrogen gas concentration higher than the rated concentration (reference concentration > rated concentration). In the example shown in Figure 3A, when the fuel gas reaches gas separation adjustment station 40d, the hydrogen gas concentration is significantly lower than the rated concentration, and the difference from the reference concentration is increasing. Because hydrogen gas is preferentially / actively separated to match the desired reference concentration, the hydrogen gas concentration in the fuel gas drops even more significantly after passing through gas separation adjustment station 40d.

[0050] From the results of FIG. 3A, it can be said that the fluctuation range of the hydrogen gas concentration in the fuel gas flowing through the gas conduit 50 may increase each time the gas passes through a mixed gas distribution station.

[0051] 3B is a position chart showing another example of changes in the hydrogen gas concentration in fuel gas flowing through the gas pipes of the fuel gas pipe grid. FIG. 3B shows a case where the separated gas flow rate and return gas flow rate at gas separation adjustment station 40b (city gas distribution station) are greater than those at gas separation adjustment station 40a (hydrogen gas distribution station). In this case, because a large amount of city gas is separated at gas separation adjustment station 40b (resulting in a significant decrease in the city gas concentration), it is conceivable that the hydrogen gas concentration in the fuel gas will increase significantly after passing through gas separation adjustment station 40b, exceeding the rated concentration.

[0052] At the gas separation adjustment station 40c (mixed gas distribution station), if the hydrogen gas concentration of the arriving fuel gas exceeds the standard concentration as shown in Figure 3B, in order to separate and distribute a mixed gas of the desired standard concentration, city gas is preferentially / actively separated to match the standard concentration. As a result, the hydrogen gas concentration in the fuel gas further increases after passing through the gas separation adjustment station 40c.

[0053] The next gas separation adjustment station 40d (mixed gas distribution station) separates and distributes mixed gas with a hydrogen gas concentration higher than the rated concentration, but in the example shown in Figure 3B, the hydrogen gas concentration exceeds the desired standard concentration when the fuel gas reaches gas separation adjustment station 40d. Therefore, gas separation adjustment station 40d also preferentially / actively separates city gas to match the standard concentration, so the hydrogen gas concentration in the fuel gas further increases after passing through gas separation adjustment station 40d.

[0054] As described with reference to Figures 3A and 3B, it can be seen that the fluctuation range of the hydrogen gas concentration in the fuel gas flowing through the gas conduit 50 may increase each time the gas conduit passes through a mixed gas distribution station. The increase in the fluctuation range of the hydrogen gas concentration means that a significantly larger fuel gas flow rate must be processed to adjust and distribute the mixed gas of the standard concentration desired by the consumer group. This requires the gas separation and adjustment station to be larger in size as it moves downstream of the gas conduit 50, which leads to the inconvenience of causing the overall system to become larger. Furthermore, if the fluctuation range of the hydrogen gas concentration in the fuel gas increases to a limit, there is a concern that problems may occur in the separation and distribution of the fuel gas itself at other gas separation and adjustment stations connected downstream of the gas conduit 50.

[0055] The inventors have thoroughly investigated the causes of the above-mentioned problems and conducted extensive research to find solutions. As a result, they concluded that the above problems are caused by the fixed hydrogen gas concentration (reference concentration) of the mixed gas distributed to a group of mixed gas consumers. They found a solution: for each mixed gas distribution station, a tolerance range of variation (a range above and below the reference concentration, within which the combustor functions and burns normally) is set around the reference concentration, while taking into account the characteristics of the combustors used by each mixed gas consumer group, and then control the hydrogen gas concentration within that range. Furthermore, to control the hydrogen gas concentration, they developed a method for predicting the hydrogen gas concentration after a specified time based on measurement data of the hydrogen gas concentration in the fuel gas upstream of the mixed gas distribution station being controlled, and then controlling the hydrogen gas concentration within the tolerance range based on the results of this prediction.

[0056] It is important to understand that fluctuations in the concentration of gas components flowing through a gas pipeline do not spread instantly throughout the entire circuit like the current and voltage in an electric circuit, but rather move over time, gradually diffusing and homogenizing, like a meteorological phenomenon. In this invention, "predictive calculation after a predetermined time" refers to a predictive calculation that takes into account the time difference between the upstream point where the hydrogen gas concentration is measured and the time it reaches the mixed gas distribution station that is the target of control.

[0057] 4 is a schematic diagram showing an example of the configuration of a mixed gas concentration control mechanism. As shown in FIG. 4, the mixed gas concentration control mechanism 80 includes an input / output mechanism 81, a hydrogen gas concentration range storage mechanism 82, a data storage mechanism 83, a prediction / control calculation mechanism 84, a prediction / control calculation result storage mechanism 85, and a transmission / reception mechanism 86.

[0058] Each mechanism will now be described in detail.

[0059] The input / output mechanism 81 is a mechanism for inputting and confirming various setting values ​​(for example, the allowable range of fluctuation in hydrogen gas concentration for each consumer group). There are no particular limitations on the devices that make up the input / output mechanism 81, and conventional input / output devices (for example, a keyboard, a display, an input / output port, a printer, etc.) can be used as appropriate.

[0060] The hydrogen gas concentration range storage mechanism 82 is a mechanism that stores the allowable fluctuation range of the hydrogen gas concentration input from the input / output mechanism 81. There are no particular limitations on the device that constitutes the hydrogen gas concentration range storage mechanism 82, and conventional storage devices (for example, flash memory, magnetic storage device, etc.) can be used as appropriate.

[0061] The data storage mechanism 83 is a mechanism for storing measurement data from the hydrogen gas concentration measurement mechanism 45. It is preferable to store historical information (e.g., date, day of the week, time, weather conditions, etc.) in addition to storing the measurement data. There are no particular limitations on the device that constitutes the data storage mechanism 83, and conventional storage devices (e.g., flash memory, magnetic storage device, etc.) can be used as appropriate.

[0062] The prediction / control calculation mechanism 84 is a mechanism that performs a prediction calculation of the hydrogen gas concentration distribution in the fuel gas flowing through the gas conduit 50 and a control calculation to converge the hydrogen gas concentration. Using the measurement data and history information stored in the data storage mechanism 83, it performs a prediction calculation of the hydrogen gas concentration of the fuel gas flowing through the gas conduit 50 after a predetermined time (in other words, it performs a prediction calculation of the hydrogen gas concentration distribution of the fuel gas flowing through the gas conduit 50 after a predetermined time), and calculates appropriate control (how to control the hydrogen gas concentration of the mixed gas separated and distributed at the mixed gas distribution station to be controlled within an allowable fluctuation range) to converge the hydrogen gas concentration based on the prediction calculation results. There are no particular limitations on the device that constitutes the prediction / control calculation mechanism 84, and conventional calculation devices (e.g., computers) can be used as appropriate.

[0063] The prediction and control calculation result storage mechanism 85 is a mechanism for storing the results of the prediction calculation and the control calculation performed by the prediction and control calculation mechanism 84. There are no particular limitations on the device that constitutes the prediction and control calculation result storage mechanism 85, and conventional storage devices (for example, flash memory, magnetic storage device, etc.) can be used as appropriate.

[0064] The transmitting / receiving mechanism 86 is a mechanism that receives measurement data from the hydrogen gas concentration measuring mechanism 45 and transmits control signals to the mixed gas adjusting mechanism 7. There are no particular limitations on the devices that make up the transmitting / receiving mechanism 86, and conventional transmitting / receiving devices (for example, input / output ports, wired transmitting / receiving devices, wireless transmitting / receiving devices, etc.) can be used as appropriate.

[0065] FIG. 5A is an example of a time chart of measurement data of hydrogen gas concentration in fuel gas at a point after passing through a city gas distribution station (e.g., gas separation and adjustment station 40b in FIG. 2). FIG. 5B is an example of a time chart of measurement data of hydrogen gas concentration in fuel gas at a point of a fuel gas inlet pipe of a mixed gas distribution station (e.g., gas separation and adjustment station 40c in FIG. 2) located downstream of the city gas distribution station of FIG. 5A and the predicted calculation results. To facilitate understanding of the following explanation, the figure also shows the reference concentration of hydrogen gas concentration at the mixed gas distribution station of FIG. 5B and the upper and lower limits of the allowable fluctuation range.

[0066] As shown in FIG. 5A, at the point where the city gas distribution station is passed, the fluctuation of the hydrogen gas concentration is sufficiently small from time t1 to time t2 (so-called fluctuation level). p The hydrogen gas concentration fluctuates greatly, exceeding the upper limit of the allowable fluctuation range especially from time t3 to time t4, and from time t5 to the present time t p The fuel gas having such concentration fluctuations reaches the mixed gas distribution station located downstream after a predetermined time.

[0067] On the other hand, looking at FIG. 5B, from time t6 to the current time t p In this time period, the fluctuation in hydrogen gas concentration is sufficiently small. This is because the fuel gas having a concentration fluctuation from time t1 to time t2 in FIG. 5A reaches the mixed gas distribution station. During this time period, the mixed gas distribution station performs normal control operation to distribute mixed gas of the reference concentration. Note that normal control operation is preferably performed when the fluctuation in hydrogen gas concentration is within a predetermined threshold range (for example, within ±2% by volume) of the reference concentration.

[0068] However, as a result of the prediction calculation, the current time t p After that, the fuel gas (time t2 to the present time t) whose hydrogen gas concentration fluctuates greatly pIt is predicted that the fuel gas (which has passed through the city gas distribution station in Figure 5A) will reach the mixed gas distribution station.

[0069] Therefore, the hydrogen gas concentration of the mixed gas is controlled based on the results of the prediction calculation (mixed gas concentration control operation). The mixed gas concentration control operation is preferably performed when it is predicted that the fluctuation of the hydrogen gas concentration will be outside a predetermined threshold range (for example, more than ±2% by volume) with respect to the reference concentration.

[0070] Specifically, the time period in which the hydrogen gas concentration is predicted to be within the tolerance range (current time t p During the period from time t7 to time t7, and from time t8 to time t9), a control calculation is performed to supply mixed gas whose hydrogen gas concentration has been adjusted to a value in accordance with the results of the prediction calculation, and the control signal is sent to mixed gas adjustment mechanism 7. During the period (time t7 to time t8) when it is predicted that the hydrogen gas concentration will exceed the upper limit of the allowable fluctuation range, a control calculation is performed to supply mixed gas whose hydrogen gas concentration has been adjusted to the upper limit of the allowable fluctuation range, and to store excess hydrogen gas in hydrogen gas storage mechanism 3 and / or release city gas stored in other gas storage mechanism 4 to adjust to the upper limit of the allowable fluctuation range, and the control signal is sent to mixed gas adjustment mechanism 7.

[0071] In addition, the time period during which the hydrogen gas concentration is predicted to fall below the lower limit of the allowable fluctuation range (time t9 to time t 10 ) supplies mixed gas adjusted to a hydrogen gas concentration that is the lower limit of the allowable fluctuation range, and performs control calculations to store excess city gas in the other gas storage mechanism 4 and / or release the hydrogen gas stored in the hydrogen gas storage mechanism 3 to adjust to the lower limit of the allowable fluctuation range, and sends the control signal to the mixed gas adjustment mechanism 7.

[0072] By performing control based on the results of the above-described prediction calculations and control calculations, it is possible to prevent negative feedback resulting from the adjustment of the mixed gas at the mixed gas distribution station as described in Figures 3A and 3B. Furthermore, when multiple mixed gas distribution stations are connected to the gas conduit 50, by performing the above-described control at each mixed gas distribution station, it is possible to guide the fluctuation range of the hydrogen gas concentration of the fuel gas flowing through the gas conduit 50 in a direction to reduce (to converge the hydrogen gas concentration). These effects lead to the suppression of the expansion of the entire system.

[0073] In addition, if it is predicted from the measurement data and historical information stored in the data storage mechanism 83 that control based on the results of the above-mentioned predictive calculations and control calculations will be insufficient under certain conditions, a control signal may be sent from the mixed gas concentration control mechanism 80 to the fuel gas blending mechanism 65 during the period under those specific conditions, and adjustments may be made to increase / decrease the rated concentration itself.

[0074] The above-described embodiments have been described to aid in understanding the present invention, and the present invention is not limited to the specific configurations described. For example, it is possible to replace part of the configuration of the embodiments with configurations within the technical common sense of those skilled in the art, and it is also possible to add configurations within the technical common sense of those skilled in the art to the configuration of the embodiments. In other words, it is possible to delete, replace, or add part of the configuration of the embodiments of this specification to the extent that it does not deviate from the technical concept of the invention. [Explanation of symbols]

[0075] 1...hydrogen gas separation mechanism, 2...gas pressure adjustment mechanism, 3...hydrogen gas storage mechanism 4...Other gas storage mechanism, 4'...City gas storage mechanism, 5a to 5c...Gas return mechanism, 7...mixed gas adjustment mechanism, 8...mixed gas storage mechanism, 10... separation gas flow rate control mechanism, 15... return gas flow rate control mechanism, 20...fuel gas inlet pipe, 25...surplus gas return pipe, 30...separated gas supply pipe, 35a-35c: Consumer group, 40a-40c: Gas separation and adjustment station, 45...hydrogen gas concentration measuring mechanism, 50...gas conduit, 60... City gas supply equipment, 65... Fuel gas blending mechanism, 70... Hydrogen gas supply equipment, 80... mixed gas concentration control mechanism, 81... input / output mechanism, 82... hydrogen gas concentration range storage mechanism, 83...data storage mechanism, 84...prediction and control calculation mechanism, 85...prediction and control calculation result storage mechanism, 86...Transmitting and receiving mechanism.

Claims

1. A system for separating gas having a composition desired by a consumer group from a fuel gas containing hydrogen gas and distributing the gas to the consumer group, a fuel gas conduit grid through which the fuel gas flows; a plurality of gas separation and adjustment stations connected to the gas pipes of the fuel gas pipe grid for separating and adjusting gas having a composition desired by the consumer group from the fuel gas; and At least one of the plurality of gas separation and adjustment stations is a mixed gas distribution station for distributing a mixed gas containing hydrogen gas, the mixed gas distribution station comprising: a hydrogen gas concentration measuring mechanism that measures the hydrogen gas concentration of the fuel gas flowing through the gas conduit; a hydrogen gas separation mechanism that separates hydrogen gas from the fuel gas; a mixed gas adjusting mechanism that adjusts the mixed gas to match a fluctuation allowance range set for the hydrogen gas concentration desired by the consumer group; a gas return mechanism for returning unused excess gas to the gas conduit; The system comprises: a mixed gas concentration control mechanism that performs a prediction calculation of the hydrogen gas concentration in the gas conduit after a predetermined time based on data from the hydrogen gas concentration measurement mechanism and a control calculation for converging the hydrogen gas concentration, and outputs a control signal to the mixed gas adjustment mechanism to increase / decrease the hydrogen gas concentration of the mixed gas within the allowable fluctuation range based on the results of the prediction calculation and control calculation; A gas distribution control system comprising:

2. 2. The gas distribution control system of claim 1, The mixed gas concentration control mechanism includes: An input / output mechanism for inputting and checking setting values; a hydrogen gas concentration range storage mechanism that stores the allowable fluctuation range of the hydrogen gas concentration; a data storage mechanism for storing the data; a prediction and control calculation mechanism that performs a prediction calculation of the hydrogen gas concentration and a control calculation for converging the hydrogen gas concentration; a prediction and control calculation result storage mechanism for storing the results of the prediction calculation and the control calculation; a transmitting / receiving mechanism for receiving the data and transmitting the control signal; A gas distribution control system comprising:

3. 3. The gas distribution control system according to claim 2, The mixed gas distribution station comprises: a hydrogen gas storage mechanism that stores the hydrogen gas separated by the hydrogen gas separation mechanism; an other gas storage mechanism that stores other gases separated by the hydrogen gas separation mechanism; A gas distribution control system further comprising:

4. 4. The gas distribution control system according to claim 3, The fuel gas includes hydrogen gas and city gas, At least one of the plurality of gas separation and adjustment stations is a hydrogen gas distribution station for distributing the hydrogen gas, the hydrogen gas distribution station comprising: The hydrogen gas concentration measuring mechanism, the hydrogen gas separation mechanism, the hydrogen gas storage mechanism, and the gas return mechanism are included, At least one of the plurality of gas separation and adjustment stations is a city gas distribution station for distributing the city gas, and the city gas distribution station comprises: A gas distribution control system comprising the hydrogen gas concentration measuring mechanism, the hydrogen gas separation mechanism, the other gas storage mechanism, and the gas return mechanism.

5. 5. The gas distribution control system according to claim 1, The gas distribution control system further comprises a return gas flow rate control mechanism for controlling the flow rate of the gas return mechanism based on data from the hydrogen gas concentration measurement mechanism.

6. 5. The gas distribution control system according to claim 1, A gas distribution control system characterized in that the allowable fluctuation range of the hydrogen gas concentration is defined based on the Wobbe index.

7. 5. The gas distribution control system according to claim 1, each of the plurality of gas separation and adjustment stations is connected to the gas conduit by a fuel gas inlet pipe and an excess gas return pipe; A gas distribution control system characterized in that the hydrogen gas concentration measuring mechanism is connected to both the connection between the fuel gas inlet pipe and the gas conduit and the connection between the surplus gas return pipe and the gas conduit.

8. 5. The gas distribution control system according to claim 1, The system further includes a city gas supply facility that supplies pure city gas to the fuel gas pipeline grid, a hydrogen gas supply facility that supplies pure hydrogen gas to the fuel gas pipeline grid, and a fuel gas blending mechanism that blends the fuel gas; The gas distribution control system is characterized in that the mixed gas concentration control mechanism further has a function of outputting a control signal to the fuel gas blending mechanism to increase / decrease the hydrogen gas concentration in the fuel gas based on the results of the prediction calculation and the control calculation.

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