Storage container for hydrogen carrier and storage container for by-product

Abstract

A pair of planar surface portions 6 are provided on two opposite outer wall surfaces of a storage container 1 in the vertical direction, in the horizontal direction, or in the front-rear direction when the storage container is in an installed state. A recessed portion 15 is formed in a portion of at least one of the planar surface portions 16, and is formed so as to be recessed inward from another portion 16a of the planar surface portion 16, and such that at least a portion of the recessed part 15 is in communication with the outside of the planar surface portion 16 in a direction along the planar surface portion 16. A relief valve 11 is provided in the recessed portion 15, and automatically opens when the pressure inside a storage portion 14 for storing a hydrogen carrier exceeds a predetermined value, thereby releasing the gas inside the storage part 14 to the outside. This makes it possible to suppress a rise in the pressure inside the storage container 1 for storing a hydrogen carrier or a by-product, even if multiple storage containers 1 are stored stacked in the vertical direction or laid out in the horizontal direction or the front-rear direction.

Description

Hydrogen carrier storage vessel and by-product storage vessel

[0001] The present invention relates to a hydrogen carrier storage container and a by-product storage container for storing a hydrogen carrier and a by-product.

[0002] As a storage container for storing gas, a configuration has been proposed in which the top and bottom surfaces are flat and the container can be stacked one on top of the other (Patent Document 1).

[0003] International Publication No. 2019 / 026872

[0004] Here, devices that generate hydrogen by reacting a hydrogen carrier with a liquid containing water are known. It is also known that by-products are generated along with hydrogen during this process. When such hydrogen carriers and by-products are stored in a storage container, there is a risk that gases such as hydrogen may be generated within the storage container, depending on the storage environment. In this case, the pressure within the storage container may increase, potentially causing the container to burst. Therefore, it is considered to provide a relief valve that releases the gas inside the storage container to the outside.

[0005] However, if the storage containers are stored stacked vertically or lined up horizontally or front to back, the relief valve may become blocked, preventing sufficient gas from being discharged from inside the storage container, which may result in an increase in pressure inside the storage container.

[0006] The present invention aims to provide a configuration that can suppress an increase in pressure inside a storage container even when the storage containers for storing hydrogen carriers and by-products are stacked vertically or stored side by side or in the front to back direction.

[0007] The hydrogen carrier storage container of the present invention is a hydrogen carrier storage container capable of storing a hydrogen carrier, and comprises: a storage section for storing the hydrogen carrier; a pair of flat sections provided on both sides of the outer wall surface of the storage container in at least one of the up-down, left-right, and front-to-back directions when the storage container is installed; a recess formed in a portion of at least one of the pair of flat sections, which is recessed inward more than other portions of the flat section and is formed so that at least a portion of the recess is connected to the outside of the flat section in a direction along the flat section; and a relief valve provided within the recess, which automatically opens when the pressure inside the storage section exceeds a predetermined value, to release gas inside the storage section to the outside.

[0008] The by-product storage container of the present invention is a by-product storage container capable of storing by-products produced together with hydrogen when a hydrogen carrier is reacted with a liquid containing water, and comprises: a storage section for storing the by-products; a pair of flat sections provided on both sides of the outer wall surface of the storage container in at least one of the up-down, left-right, and front-to-back directions when the storage container is installed; a recess formed in a portion of at least one of the pair of flat sections, the recess being recessed more inward than other portions of the flat section and having at least a portion communicating with the outside of the flat section in a direction along the flat section; and a relief valve provided within the recess, which automatically opens when the pressure inside the storage section exceeds a predetermined value to release gas inside the storage section to the outside.

[0009] According to the present invention, even if storage containers for storing hydrogen carriers or by-products are stacked vertically or arranged side by side or front to back, an increase in pressure inside the storage containers can be suppressed.

[0010] 1 is a schematic configuration diagram of a hydrogen generation system according to a first embodiment. 2 is a schematic configuration cross-sectional view of a storage container according to the first embodiment. 3 is a schematic configuration perspective view of a storage container according to the first embodiment. 4 is a schematic configuration cross-sectional view showing an example of a storage state of a storage container according to the first embodiment. 5 is a schematic configuration perspective view showing an example of a storage state of a storage container according to the first embodiment. 6 is a schematic configuration cross-sectional view showing a state in which a storage container according to another example of the first embodiment is fitted. 7 is a schematic configuration cross-sectional view showing a state in which a storage container according to another example of the first embodiment is fitted. 8 is a schematic configuration diagram of a hydrogen generation system according to a second embodiment. 9 is a schematic configuration cross-sectional view of a storage container according to the second embodiment.

[0011] First Embodiment A first embodiment will be described with reference to FIGS. 1 to 5. First, hydrogen has attracted attention as an alternative energy source to fossil fuels. This is because, unlike fossil fuels, hydrogen does not produce carbon dioxide, a greenhouse gas that contributes to global warming, when burned. One system that uses hydrogen as an energy source that has been put into practical use is the fuel cell vehicle. A fuel cell vehicle is a vehicle that generates electricity using hydrogen as a raw material and runs on an electric motor using the generated electricity. Many fuel cell vehicles store hydrogen, the energy source, in a hydrogen tank, and generate electricity by feeding the hydrogen from the hydrogen tank into a fuel cell. The hydrogen tank stores hydrogen by compressing it at a high pressure, such as 70 MPa (700 times atmospheric pressure).

[0012] One of the challenges of hydrogen as an energy source is its low energy density. The volumetric energy density of hydrogen is about 1 / 3000 of that of gasoline, so even if a 70 MPa hydrogen tank is used, only about 1 / 5 of the energy of gasoline can be extracted from the same volume. For this reason, fuel cell vehicles using hydrogen tanks generally require more frequent refueling than vehicles using gasoline.

[0013] For this reason, various substances (i.e., hydrogen carriers) that can transport hydrogen at a higher energy density than hydrogen tanks are being investigated. For example, ammonia, methylcyclohexane, and borohydrides such as sodium borohydride are known as hydrogen carriers, and hydrogen carriers are transported instead of hydrogen itself, and hydrogen is extracted from the hydrogen carrier when it is used.

[0014] [Hydrogen Carrier] Among hydrogen carriers, metal hydrides such as sodium borohydride are widely known, from which hydrogen can be easily extracted by adding water. One known method for obtaining hydrogen by hydrolyzing sodium borohydride is to dissolve sodium borohydride in water and use it as an aqueous solution. However, this method requires a larger amount of water than theoretically required by the reaction formula, resulting in a decrease in the actual volumetric energy density. Therefore, in this embodiment, as described below, hydrogen is generated by adding a liquid containing water to the hydrogen carrier in a hydrogen generation device (specifically, by pouring a liquid containing water onto the hydrogen carrier).

[0015] Examples of hydrogen carriers that generate hydrogen when a water-containing liquid is added include the following. For example, solid metal hydrides such as sodium borohydride, potassium borohydride, lithium borohydride, zinc borohydride, lithium aluminum hydride, sodium aluminum hydride, magnesium aluminum hydride, calcium aluminum hydride, magnesium hydride, lithium hydride, sodium hydride, and calcium hydride, and metal powders such as aluminum, zinc, calcium, and magnesium can be used alone or in combination. Organic hydrides such as methylcyclohexane, cyclohexane, and decalin can also be used. Additives such as reaction accelerators and desiccants can also be used together with the hydrogen carrier.

[0016] Furthermore, the hydrogen carrier of this embodiment may be either solid or liquid, but is preferably solid. As a solid hydrogen carrier, a solid such as a powder or granule is desirable, but a solid such as a sheet, pellet, or paste can also be used. As a powder, a particle size of approximately 10 μm to 10 mm can be used, with a particle size of approximately 10 μm to 3 mm, and even more preferably a particle size of approximately 10 μm to 100 μm. Furthermore, when used in sheet or pellet form, it is preferable to increase the surface area and the contact area with the water-containing liquid by subjecting the carrier to surface roughening or porous treatment, etc., in order to enhance reactivity with the water-containing liquid.

[0017] The hydrogen carrier of this embodiment is a substance that generates by-products (reaction products) other than hydrogen, such as liquid, gel, or solid, after hydrogen is generated by a chemical reaction.

[0018] In this embodiment, sodium borohydride powder with an average particle size of 50 μm was used as the solid hydrogen carrier. The powdered sodium borohydride reacts with water to generate hydrogen. The reacted sodium borohydride changes into sodium metaborate, a by-product. Water not used in the reaction remains. This reaction can be expressed by the following chemical formula: NaBH4 (sodium borohydride) + 2H2O (water) → NaBO2 (sodium metaborate) + 4H2 (hydrogen) ... (1)

[0019] This reaction (chemical formula (1)) is known to be accelerated by a Raney catalyst made from a metal such as nickel, cobalt, or copper, or an acidic solution such as citric acid or acetic acid. In this embodiment, when a larger amount of water than that represented by formula (1) is added in order to thoroughly and efficiently carry out the hydrolysis reaction, the by-product becomes a liquid sodium metaborate solution or a gel-like sodium borate hydrate.

[0020] [Water-containing liquid] The "water-containing liquid" in this embodiment is not particularly limited as long as it is a liquid that reacts with the hydrogen carrier when applied and generates hydrogen. That is, the water-containing liquid may be water alone. Furthermore, two or more types of water-containing liquid may be prepared. By preparing two or more types of water-containing liquid, the rate of hydrogen generation can be adjusted.

[0021] The water-containing liquid may contain a water-soluble organic solvent. Examples include alcohols, polyalkylene glycols, glycol ethers, nitrogen-containing compounds, and sulfur-containing compounds. Two or more selected from these may be mixed and used. By including a water-soluble organic solvent, the surface tension and the boiling and melting points of the water-containing liquid can be adjusted, thereby optimizing the reaction with the hydrogen carrier.

[0022] A surfactant can be added to the aqueous liquid, which can reduce the surface tension of the aqueous liquid, increasing the contact area with the hydrogen carrier and enabling an efficient reaction.

[0023] The aqueous liquid may contain a water-soluble acidic substance. The acidic substance acts as a positive catalyst in the reaction between the aqueous liquid and the hydrogen carrier. The hydrogen generation speed can be adjusted by adjusting the amount of the aqueous liquid containing the acidic substance. In particular, the hydrogen generation speed can be increased by adjusting the pH obtained by the aqueous liquid and the hydrogen carrier to less than 9.0. Examples of acids that can be used include, but are not limited to, various acids such as hydrochloric acid, sulfuric acid, nitric acid, boric acid, and organic acids.

[0024] The aqueous liquid may contain a water-soluble basic substance. The basic substance acts as a negative catalyst in the reaction between the aqueous liquid and the hydrogen carrier. The speed of hydrogen generation can be adjusted by adjusting the amount of the aqueous liquid containing the basic substance. In particular, the speed of hydrogen generation can be slowed by setting the pH obtained by the aqueous liquid and the hydrogen carrier to 9.0 or higher. Examples of bases that can be used include, but are not limited to, various bases such as sodium hydroxide, potassium hydroxide, and aqueous ammonia.

[0025] The water-containing liquid may contain a buffer solution. The buffer solution acts to suppress pH changes during the reaction between the water-containing liquid and the hydrogen carrier. The speed of hydrogen generation can be adjusted by adjusting the amount of the buffer-containing liquid. Examples of buffer solutions include, but are not limited to, phosphate buffer, glycine buffer, Good's buffer, Tris buffer, and ammonia buffer.

[0026] In addition to the above components, the water-containing liquid may contain various additives such as antifoaming agents, pH adjusters, viscosity adjusters, rust inhibitors, preservatives, antifungal agents, antioxidants, and antireducing agents, as needed.

[0027] [Hydrogen Generation System] A hydrogen generation system 100 of this embodiment will be described with reference to Fig. 1. Fig. 1 is a block diagram showing a schematic configuration of the hydrogen generation system 100 of this embodiment. The hydrogen generation system 100 includes a hydrogen carrier storage container 1, a hydrogen generation device 32, a water supply unit 33, and a fuel cell system 35.

[0028] The hydrogen carrier storage container 1 is a container that can store a hydrogen carrier (sodium borohydride in this embodiment) and is a container that can be attached and detached to the hydrogen generator 32. The filled hydrogen carrier is sent by its own weight to the hydrogen generation section of the hydrogen generator 32, and the supply amount can be adjusted by an on-off valve attached to the hydrogen generation section side.

[0029] The storage container 1 also includes a relief valve 11 for releasing hydrogen gas generated inside to the outside, and a filter 13. The filter 13 is provided between the relief valve 11 and the inside of the storage container 1. This filter 13 allows hydrogen gas to pass through but does not allow the hydrogen carrier inside the container to pass through. A detailed description of the storage container 1 will be given later.

[0030] The water supply unit 33 has a function of being able to supply "liquid containing water" from a tap, a water tank, etc. to the hydrogen generator 32, and a filter or the like is installed in the flow path to remove foreign matter, etc. In addition, the water supply unit 33 may have a function of adjusting the temperature of the liquid containing water being supplied, such as a heater or chiller, for the purpose of promoting and stabilizing the hydrolysis reaction.

[0031] The hydrogen generator 32 has a hydrogen generating section to which the hydrogen carrier is supplied from the storage container 1 and a liquid containing water is supplied from the water supply unit 33. The hydrogen carrier and the liquid containing water are mixed in the hydrogen generating section to cause a hydrolysis reaction, generating hydrogen and by-products.

[0032] The hydrogen generated in the hydrogen generator 32 is sent to a fuel cell system 35. The fuel cell system 35 generates electricity using the hydrogen generated in the hydrogen generator 32, and is an example of a device that utilizes the hydrogen generated in the hydrogen generator 32. A by-product (sodium metaborate in this embodiment) generated during hydrogen generation is collected in a collection container (not shown).

[0033] In this hydrogen generation system 100, first, after injecting the hydrogen carrier into the storage container 1, if no hydrogen is generated, or if hydrogen is generated but does not exceed a threshold set for safety reasons, the hydrogen is delivered directly to the hydrogen generation device 32. Then, the hydrogen carrier is supplied from the storage container 1, and a liquid containing water is supplied from the water supply unit 33 to the hydrogen generation device 32, where hydrogen gas and by-products are produced.

[0034] If for some reason the hydrogen carrier reacts inside the storage container 1 to generate hydrogen gas, causing the pressure inside the storage container 1 to exceed a predetermined value, the relief valve 11 will automatically open and release the excess hydrogen from inside the storage container 1 to the outside.

[0035] [Storage Container for Hydrogen Carrier] Next, a storage container 1 for a hydrogen carrier will be described with reference to Figure 2 and Figure 3. The storage container 1 has a storage section 14 for storing a hydrogen carrier, and has a cylindrical shape with a polygonal cross section perpendicular to the longitudinal direction. In this embodiment, as shown in Figure 3, the cross section perpendicular to the longitudinal direction of the storage container 1 has a rectangular prism shape. Note that the cross section perpendicular to the longitudinal direction of the storage container 1 may have other shapes besides a rectangle, such as a pentagon, hexagon, or octagon.

[0036] As will be described later, the storage container 1 has a flat surface 16 on at least a portion of the outer wall surface, and when stacked vertically or arranged horizontally, the flat surfaces 16 of adjacent storage containers 1 (flat surfaces) face each other and abut or come close to each other, thereby enabling the arrangement of multiple storage containers 1 in a space-saving manner. The storage container 1 is preferably in the shape of a prism that allows efficient stacking in the up-down, front-rear, and left-right directions, and may have any shape such as a pentagonal prism, hexagonal prism, or octagonal prism as long as this is satisfied.

[0037] Furthermore, from the viewpoint of preventing static electricity buildup, the storage container 1 is preferably made of metal or a resin container with anti-static measures. This prevents ignition due to the metal even if hydrogen gas is generated inside. Furthermore, there is no particular problem with attaching a desiccant or the like to the inner wall of the container as a dehumidification measure inside the storage container 1. This suppresses the reaction between the hydrogen carrier and water inside the storage container 1, thereby suppressing the generation of hydrogen gas.

[0038] Such a storage container 1 has a flat surface 16 as a first flat surface, a flat surface 17 as a second flat surface, a recess 15 as a first recess, a relief valve 11, a filter 13, an opening 12, and a recess 18 as a second recess. The flat surface 16 is provided on both sides of the outer wall surface of the storage container 1 in at least one direction of the up-down direction, the left-right direction, and the front-rear direction when the storage container 1 is installed. By arranging the flat surface 16 in this manner, it is possible to line up the storage containers 1 so that the flat surface portions 16 abut or are close to each other.

[0039] A pair of flat surfaces 16 is preferably provided on the outer wall surface of the storage container 1 in at least two directions among the up-down direction, the left-right direction, and the front-to-rear direction when the storage container 1 is installed. By arranging the flat surfaces 16 in this manner, it becomes possible to line up the storage containers 1 so that the flat surfaces 16 abut or are close to each other in multiple directions. In this embodiment, the storage container 1 has a prismatic shape with a rectangular cross section perpendicular to the longitudinal direction, and therefore a pair of flat surfaces 16 is provided in each of the up-down direction and the left-to-right direction when the storage container 1 is installed. In this embodiment, the longitudinal direction of the storage container 1 is defined as the front-to-rear direction.

[0040] In this way, by providing a pair of flat surfaces 16 in each of the vertical and horizontal directions in the installed state, the storage containers 1 can be stacked vertically so that their flat surfaces 16 abut or are close to each other, and the storage containers 1 can also be arranged side by side in the horizontal direction so that their flat surfaces 16 abut or are close to each other. Furthermore, even if the orientation of the storage container 1 is changed so that the above-mentioned vertical direction becomes the horizontal direction and the horizontal direction becomes the vertical direction, the storage containers 1 can similarly be stacked vertically and arranged side by side in the horizontal direction. The same applies to the relationship between the vertical direction and the front-to-rear direction, and the relationship between the left-to-right direction and the front-to-rear direction.

[0041] Furthermore, the storage container 1 of this embodiment has a flat surface 17 on both sides in the front-to-rear direction. That is, both longitudinal ends of the storage container 1 also have flat surfaces 17. That is, the flat surfaces 17 are provided at positions on the outer wall surface of the storage container 1 that are different from the flat surfaces 16, and in this embodiment, both front-to-rear directions of the storage container 1 are flat surfaces 17. The storage containers 1 can be arranged side by side so that the flat surfaces 17 abut or are close to each other in the front-to-rear direction.

[0042] An opening 12 is formed in one of the flat surface portions 17 on both sides in the front-rear direction. The opening 12 connects the inside and outside of the storage portion 14 and is provided for injecting or discharging the hydrogen carrier into or from the storage portion 14. A recess 18 is formed in a part of the flat surface portion 17 so as to be recessed inward more than the other parts. The opening 12 is provided within the recess 18.

[0043] The opening 12 is formed to fit within the recess 18. The opening 12 can be connected without any gaps to the hydrogen carrier inlet of the hydrogen generator 32, and is structured to be able to supply the hydrogen carrier filled in the storage unit 14 to the hydrogen generating unit of the hydrogen generator 32 without leakage. The opening 12 can also be connected without any gaps to the inlet of an injection device (not shown) for injecting the hydrogen carrier into the storage container 1.

[0044] The opening 12 is closed with a lid (not shown), for example, after the hydrogen carrier is stored in the storage container 1. The recess 18 has a depth such that even when the opening 12 is closed with the lid, the lid does not protrude from the recess 18. Therefore, even if multiple storage containers 1 are arranged in the front-to-rear direction so that the flat surface portion 17 on which the recess 18 is formed and the flat surface portion 17 on which the recess 18 is not formed are in contact with or close to each other, the opening 12 and the lid closing the opening 12 will not interfere with the opposing flat surface portion 17.

[0045] The recess 15 is formed in a portion of at least one of the pair of flat surfaces 16. The recess 15 is formed so as to be recessed inward relative to the other portion 16a of the flat surface 16, and so as to have at least a portion thereof communicate with the outside of the flat surface 16 in the direction along the flat surface 16. In this embodiment, as shown in FIG. 3 , the recesses 15 are formed so as to be recessed all around the same position in the longitudinal direction of the storage container 1. That is, when the storage container 1 is installed, a recess 15 is formed in each of the pair of flat surfaces 16 in the up-down direction, and a recess 15 is also formed in each of the pair of flat surfaces 16 in the left-right direction. These four recesses 15 are continuous all around the storage container 1.

[0046] The recess 15 may be formed in at least one of the planar portions 16. For example, if the recess 15 is formed in the upper planar portion 16 in the installed state, the right or left side, or the front or rear side of the recess 15 may be connected to the outside. However, it is preferable that the recess 15 is connected to the outside on both the left-right side or both the front-rear side. Note that "a portion of the recess 15 is connected to the outside" means that even if a portion of the recess 15 is open and the side facing the bottom of the recess 15 is blocked, gas can pass between the inside and outside of the recess 15. For example, if the recess 15 is formed on the upper side of the storage container 1 and the left and right sides of the recess 15 are connected to the outside, gas can still pass between the inside and outside of the recess 15 in the left-right direction, even if the upper side of the recess 15 is blocked.

[0047] It is preferable that the recess 15 is formed in at least two of the plurality of flat surfaces 16. For example, the recess 15 may be formed in each of the pair of flat surfaces 16 described above. Alternatively, when a pair of flat surfaces 16 is provided on the outer wall surface of the storage container 1 in at least two directions among the up-down direction, the left-right direction, and the front-rear direction when the storage container 1 is installed, the recess 15 may be formed in each of at least two of these flat surfaces 16. For example, the recess 15 may be formed in the upper flat surface 16 and the right or left flat surface 16, respectively.

[0048] However, as will be described later, in order to efficiently discharge the hydrogen gas discharged from the relief valve 11 to the outside, it is preferable that recesses 15 are formed in each of the pair of flat surfaces 16 on both sides in the vertical direction and the pair of flat surfaces 16 on both sides in the horizontal direction. This allows the space formed by the recesses 15 facing each other between adjacent storage containers 1 to communicate with the outside of the area in which the storage containers 1 are arranged, regardless of how the storage containers 1 are arranged.

[0049] The relief valve 11 is provided inside the recess 15 (inside the recess), and automatically opens when the pressure inside the storage unit 14 exceeds a predetermined value to release the gas inside the storage unit 14 to the outside. The relief valve 11 may be provided in at least one recess 15 out of the plurality of recesses 15. As shown in FIG. 2 , the relief valve 11 is formed on the bottom surface 15a of the recess 15, and is provided so as to block the communication port 15b that communicates with the storage unit 14. That is, the relief valve 11 is provided on the bottom surface 15a of the recess 15.

[0050] The recess 15 has a depth that prevents the relief valve 11 installed inside from protruding outside the recess 15. Therefore, even if the storage containers 1 are stacked vertically or lined up horizontally or front-to-back with the flat surfaces 16 on which the recesses 15 are formed abutting or close to each other, the relief valve 11 will not interfere with a part of the adjacent storage container 1. Furthermore, the opening and closing operation of the relief valve 11 will not be hindered.

[0051] As mentioned above, there is a risk that for some reason the hydrogen carrier in the storage container 1 may react with a liquid containing water to generate hydrogen gas. This hydrogen gas may then fill the storage section 14, causing the storage container 1 to burst due to the pressure of the expanding hydrogen gas. In such a case, the relief valve 11 automatically opens due to the pressure, releasing the excess hydrogen gas to the outside, thereby preventing damage to the storage container 1.

[0052] Furthermore, the above-mentioned filter 13 is provided at the communication port 15b between the relief valve 11 and the storage unit 14. The filter 13 is configured to allow hydrogen gas to pass through but not the hydrogen carrier in the storage unit 14. Therefore, it is possible to prevent the hydrogen carrier from leaking to the outside through the communication port 15b during transportation of the storage container 1, and when the pressure of the hydrogen gas in the storage unit 14 increases, it is possible to discharge part of this hydrogen gas to the outside through the filter 13 and relief valve 11 provided at the communication port 15b.

[0053] The relief valve 11 may be installed in at least one of the recesses 15 formed on the four faces perpendicular to the longitudinal direction of the storage container 1, but multiple recesses 15 may also be provided in the recesses 15 on other faces. Furthermore, a recess may be formed on one or both of the flat surfaces 17 on both sides in the front-rear direction of the storage container 1, and the relief valve 11 may be provided in this recess. For example, the relief valve 11 may be provided in the recess 18 in which the opening 12 described above is formed.

[0054] In this embodiment, one relief valve 11 is provided in one recess 15, but it is preferable to provide a relief valve 11 in each of two or more recesses 15. For example, when a pair of recesses 15 are formed in each of a pair of flat surfaces 16 on both sides in the vertical or horizontal direction in the installed state, a relief valve 11 may be provided in each of the multiple recesses 15.

[0055] Alternatively, when a pair of flat surfaces 16 are provided on the outer wall surface of the storage container 1 in at least two directions among the up-down direction, the left-right direction, and the front-rear direction when the storage container 1 is installed, and recesses 15 are formed in at least two of the plurality of flat surfaces 16, it is preferable that the relief valves 11 are provided in each of the plurality of recesses 15. That is, the relief valves 11 may be provided in the respective recesses 15 formed in the pair of flat surfaces 16 on both sides in any of the up-down direction, the left-right direction, and the front-rear direction, or may be provided in the respective recesses 15 formed in the plurality of flat surfaces 16 regardless of the direction. For example, one relief valve 11 may be provided on the upper side and one on the right or left side when the storage container 1 is installed.

[0056] Furthermore, when a pair of flat surfaces 16 are provided on the outer wall surface of the storage container 1 in the up-down direction and the left-right direction when the storage container 1 is in an installed state, and recesses 15 are formed in each of all of the flat surfaces 16, it is preferable to provide relief valves 11 in all of the recesses 15. In this case, relief valves 11 are provided in all of the recesses 15 on the upper, lower, right, and left sides when the storage container 1 is in an installed state.

[0057] Note that since the relief valve 11 automatically opens when the pressure inside the storage container 1 exceeds a predetermined value, at least one relief valve 11 is sufficient, but it is preferable to provide a relief valve 11 in each of the recesses 15 of the multiple flat surfaces 16 as described above, from the viewpoint of more reliably discharging hydrogen gas from the relief valve 11. For example, if the relief valve 11 is located on the lower side in the installed state, there is a risk that hydrogen gas will not be easily discharged from the lower relief valve 11 because the specific gravity of hydrogen gas is smaller than that of air. In this case, if other relief valves 11 are located on the upper, right, left, etc. side in the installed state, hydrogen gas can be efficiently discharged from these relief valves 11.

[0058] Furthermore, from the viewpoint of efficiently discharging hydrogen gas, it is preferable that the relief valve 11 be located on the upper side when the storage container 1 is installed. Therefore, by providing the relief valve 11 on any of the upper, lower, right, and left sides as described above, when installing the storage container 1, it is possible to position any of the relief valves 11 on the upper side without having to consider the orientation of the storage container 1.

[0059] [Storage of Storage Container] The storage state of the above-mentioned storage container 1 will be described using Figures 4 and 5. Figures 4 and 5 each show an example of a storage state in which a plurality of storage containers 1 are arranged side by side. In the storage container 1 shown in Figures 4 and 5, the recesses 15 are formed so that they are continuous in four directions (up and down, left and right) and around the entire circumference when installed. In addition, a relief valve 11 is provided in the upper recess 15 when installed.

[0060] 4 shows a case where multiple storage containers 1 are stacked vertically and arranged side by side in the front-to-rear direction. Since the openings 12 of the storage containers 1 are formed to fit within the recesses 18, the storage containers 1 can be arranged with no gaps in the front-to-rear direction so that the flat surfaces 17 of the storage containers 1 lined up in the front-to-rear direction abut against each other.

[0061] Meanwhile, in the vertical direction of the storage containers 1, multiple storage containers 1 can be stacked one on top of the other without any gaps, so that the upper flat surface 16 of the lower storage container 1 abuts the lower flat surface 16 of the upper storage container 1. In this case, the recess 15 formed in the upper flat surface 16 of the lower storage container 1 faces the recess 15 formed in the lower flat surface 16 of the upper storage container 1, and a space penetrating in the left-right direction is formed between these recesses 15. A relief valve 11 is provided in the recess 15 of the lower storage container 1, and hydrogen gas discharged from the relief valve 11 is discharged through this space to outside the area where multiple storage containers 1 are stacked.

[0062] FIG. 5 shows a case where multiple storage containers 1 are stacked vertically and arranged side by side in the left-right direction. The relationship between the various parts when the storage containers 1 are stacked vertically is as described in FIG. 4 . Meanwhile, with regard to the left-right direction of the storage containers 1, multiple storage containers 1 can be arranged with no gaps between the left and right sides so that the left-side flat surface 16 of the storage container 1 on the right side abuts the right-side flat surface 16 of the storage container 1 on the left side. In this case, the recess 15 formed in the left-side flat surface 16 of the storage container 1 on the right side faces the recess 15 formed in the right-side flat surface 16 of the storage container 1 on the left side, and a vertically penetrating space is formed between these two recesses 15. Therefore, hydrogen gas discharged from the relief valve 11 of the lower storage container 1 is discharged to the outside of the area where the multiple storage containers 1 are stacked and arranged horizontally through the horizontal space formed between the pair of vertically opposing recesses 15 and the vertical space formed between the pair of horizontally opposing recesses 15.

[0063] In this embodiment, recesses 15 are formed in the planar portions 16 that abut or are adjacent to each other when multiple storage containers 1 are stacked or arranged side by side, and relief valves 11 are provided in the recesses 15. The recesses 15 are formed so that at least a portion thereof communicates with the outside of the planar portion 16 in the direction along the planar portion 16. Therefore, hydrogen gas discharged from the relief valves 11 is easily discharged to the outside from the portion that communicates with the recesses 15. Therefore, even if the storage containers 1 are stored stacked vertically or lined up horizontally or front to back, an increase in pressure inside the storage containers 1 can be suppressed. Furthermore, hydrogen gas discharged from the relief valves 11 is prevented from accumulating between multiple storage containers 1, thereby improving the safety of the storage location.

[0064] Another example of the first embodiment will be described with reference to Figures 6A and 6B. In the above example, a configuration in which a plurality of storage containers 1 are simply stacked or lined up has been described. In contrast, this example includes a fitting portion 40 that fits together a plurality of stacked or lined up storage containers 1A, 1B. The fitting portion 40 is provided on the flat surface portion 16, and can be fitted into the fitting portion 40 provided on the other storage container 1B when the storage container 1A and the other storage container 1B are installed so that their flat surfaces 16 face each other.

[0065] In this embodiment, the fitting portion 40 has a protruding portion 41 protruding from the flat surface portion 16 and a bent portion 42 bent from the protruding portion 41 in a direction substantially parallel to the flat surface portion 16. Such fitting portions 40 may be provided on both flat surface portions 16 in the up-down direction when the device is installed, on both flat surface portions 16 in the left-right direction, or on all flat surface portions 16 in the up-down and left-right directions. Regarding the front-rear direction, the fitting portion 40 may be provided on the flat surface portion 17 by, for example, making the recess 18 on the side where the opening 12 is formed smaller or by providing the opening 12 on a different surface. In this example, multiple fitting portions 40 (three in the illustrated example) are provided on each of the flat surface portions 16 in the up-down and left-right directions.

[0066] When stacking storage containers 1A and 1B, as shown in Fig. 6A, the mating portions 40 are shifted from each other in the front-to-rear direction. Then, as shown in Fig. 6B, one of the storage containers 1A and 1B is shifted from the other in the front-to-rear direction to fit the mating portions 40 together. At this time, the bent portions 42 of the storage containers 1A and 1B overlap each other vertically, preventing the storage containers 1A and 1B from separating in the vertical direction. Furthermore, the tip of the bent portion 42 of one container faces the protruding portion 41 of the other container, preventing the storage containers 1A and 1B from shifting in the front-to-rear direction.

[0067] The same applies when the storage containers 1A, 1B are arranged side by side in the left-right direction; since the bent portions 42 of each storage container overlap with each other in the left-right direction, the storage containers 1A, 1B can be prevented from separating in the left-right direction.

[0068] By providing the fitting portion 40 in this manner, the storage containers 1A, 1B can be fixed to each other, which prevents the storage containers 1A, 1B from collapsing due to vibration or being accidentally displaced due to external force when they are stacked or lined up for transport or storage.

[0069] Second Embodiment A second embodiment will be described with reference to Figures 7 and 8. In the first embodiment described above, a storage container 1C for storing a hydrogen carrier was described. In contrast, in this embodiment, a storage container 1C is configured to be able to store by-products as well. Since the other configurations and functions are the same as those of the first embodiment described above, the same components are denoted by the same reference numerals, and their description will be omitted or simplified. The following description will focus on the differences from the first embodiment.

[0070] This embodiment is an example in which the container is used not only to deliver and supply raw materials (hydrogen carriers) to the hydrogen generation device 32, but also as a collection container for the by-products (sodium metaborate when the hydrogen carrier is sodium borohydride) generated after the hydrogen generation reaction in the hydrogen generation device 32.

[0071] FIG. 7 is a block diagram showing a schematic configuration of a hydrogen generation system 100A according to this embodiment. The hydrogen generation system 100A includes a storage container 1C for hydrogen carriers and by-products, a hydrogen generator 32, a water supply unit 33, and a fuel cell system 35. The configuration other than the storage container 1C is the same as that shown in FIG. 1 . In the hydrogen generation system 100A according to this embodiment, similar to the configuration shown in FIG. 1 , the hydrogen carrier is first injected into the storage container 1C. If no hydrogen is generated, or if hydrogen is generated but does not exceed a threshold value set for safety reasons, the hydrogen is delivered directly to the hydrogen generator 32. The hydrogen carrier is then supplied from the storage container 1C, and a liquid containing water is supplied from the water supply unit 33 to the hydrogen generator 32, where hydrogen gas and by-products are produced.

[0072] When the hydrogen generation reaction in hydrogen generator 32 is complete and storage container 1C is used as a by-product collection container, if no hydrogen is generated from the collected by-products, or if hydrogen is generated but does not exceed a threshold set for safety, the hydrogen is collected directly into storage container 1C. If hydrogen is generated from the by-products for some reason and the air pressure inside storage container 1C exceeds a predetermined value, hydrogen gas relief valve 11 automatically opens, releasing the excess hydrogen outside the container.

[0073] The configuration of such a storage container 1C will be described with reference to FIG. 8 . The storage container 1C has a first storage section 14A and a second storage section 23. The first storage section 14A is a section for storing the hydrogen carrier, and the second storage section 23 is a section for storing by-products generated together with hydrogen when the hydrogen carrier is reacted with a water-containing liquid. The second storage section 23 does not allow the by-products to pass through to the first storage section 14A, but allows the gas generated in the second storage section 23 to pass through to the first storage section 14A. In this embodiment, the second storage section 23 is a stretchy bag-like structure and is disposed inside the first storage section 14A. The second storage section 23 may be made of fiber or rubber.

[0074] The storage container 1C is provided with a flat surface 16, a recess 15, a relief valve 11, and the like, similar to the first embodiment described above. A recess 18 is formed in the flat surface 17 on one side in the front-to-rear direction, and an opening 12 is formed therein for injecting or discharging the hydrogen carrier into or from the first storage portion 14A. On the other hand, a flat surface 20 serving as a third flat surface is provided on the other side in the front-to-rear direction. The flat surface 20 is provided at a position on the outer wall surface of the storage container 1C different from the flat surface 16 serving as the first flat surface, and in this embodiment, is provided on the surface opposite the side on which the opening 12 is formed. The flat surface 20 abuts or is adjacent to the flat surface 17 when the storage containers 1C are arranged in the front-to-rear direction.

[0075] A recess 24 serving as a third recess is formed in a portion of the flat surface portion 20 so as to be recessed more inward than the other portions. An opening 21 is formed within the recess 24 as a by-product opening that connects the inside and outside of the second storage portion 23 and is used to inject or discharge by-products into or from the second storage portion 23. The opening 21 is formed to fit within the recess 24. The opening 21 can be tightly connected to a by-product discharge port of the hydrogen generation device 32, allowing the by-products to be recovered from the hydrogen generation device 32 without leakage. The opening 21 can also be tightly connected to a recovery port of a recovery device (not shown) for recovering by-products from the second storage portion 23.

[0076] The stretchable bag-shaped second storage section 23 is connected to the opening 21, and the by-products collected through the opening 21 are sent to the second storage section 23. The second storage section 23 expands due to its stretchability in accordance with the volume of the collected by-products. When the by-products in the second storage section 23 are collected by a collection device (not shown), the second storage section 23 shrinks due to its stretchability.

[0077] The by-products recovered in the second storage section 23 are by-products resulting from the reaction in the hydrogen generation device 32, and may contain moisture or may contain unreacted residual hydrogen carriers. This may result in the generation of residual hydrogen gas within the second storage section 23. For this reason, the second storage section 23 is designed to be bag-like and stretchable, and to allow only hydrogen gas to pass through even if hydrogen is generated from the by-products, while being impermeable to the by-products themselves. The hydrogen gas that has permeated from the second storage section 23 to the first storage section 14A is then discharged to the outside through the relief valve 11.

[0078] In this embodiment, even when the storage container 1C is used to store by-products, hydrogen gas generated inside can be discharged through the relief valve 11. Furthermore, as in the first embodiment, even when the storage containers 1C are stored stacked vertically or lined up horizontally or front-to-back, an increase in pressure inside the storage container 1C can be suppressed. Furthermore, hydrogen gas discharged through the relief valve 11 can be prevented from accumulating between multiple storage containers 1C, thereby improving the safety of the storage location. The storage container 1C of this embodiment may also be provided with the fitting portion 40 described in FIGS. 6A and 6B.

[0079] <Other Embodiments> In the first embodiment described above, the storage container 1 for the hydrogen carrier has been described. However, by-products may also be stored in the storage container 1. That is, the storage container 1 for the hydrogen carrier may also be used as a storage container for by-products. In this case, the by-products are stored in the storage section 14 of the storage container 1.

[0080] The hydrogen carrier storage container and by-product storage container according to the present invention are suitable as storage containers for storing hydrogen carriers and by-products.

[0081] DESCRIPTION OF SYMBOLS 1, 1A, 1B, 1C... Storage container (storage container for hydrogen carrier, storage container for by-product) 11... Relief valve 12... Opening 14... Storage portion 14A... First storage portion 15... Recess (first recess) 16... Flat portion (first flat portion) 16a... Other portion 17... Flat portion (second flat portion) 18... Recess (second recess) 20... Flat portion (third flat portion) 21... Opening (opening for by-product) 23... Second storage portion 24... Recess (third recess) 40... Fitting portion 41... Protruding portion 42... Bent portion

Claims

1. A hydrogen carrier storage container capable of storing a hydrogen carrier, comprising: a storage section for storing a hydrogen carrier; a pair of flat surfaces provided on both sides of an outer wall surface of the storage container in at least one of the up-down, left-right and front-to-back directions when the storage container is installed; a recess formed in a portion of at least one of the pair of flat surfaces, the recess being recessed more inward than other portions of the flat surface and having at least a portion connected to the outside of the flat surface in a direction along the flat surface; and a relief valve provided within the recess, which automatically opens when the pressure inside the storage section exceeds a predetermined value to release gas inside the storage section to the outside.

2. A hydrogen carrier storage container according to claim 1, wherein said recesses are formed in each of said pair of flat surfaces.

3. A storage container for a hydrogen carrier as described in claim 1 or 2, wherein the pair of flat surfaces are provided on the outer wall surface of the storage container in at least two of the vertical, horizontal and front-to-rear directions when the storage container is in an installed state, and the recesses are formed in at least two of the plurality of flat surfaces.

4. A hydrogen carrier storage container according to claim 2 or 3, wherein the relief valve is provided in each of the plurality of recesses.

5. A storage container for a hydrogen carrier as described in claim 1, wherein the pair of flat surfaces are provided on the outer wall surface of the storage container in the vertical and horizontal directions when the storage container is in an installed state, and the recesses are formed in each of all of the flat surfaces.

6. A hydrogen carrier storage container according to claim 5, wherein the relief valve is provided in each of the recesses.

7. A hydrogen carrier storage container as described in any one of claims 1 to 6, further comprising an opening that communicates the inside and outside of the storage section and is used for injecting or discharging the hydrogen carrier into or from the storage section.

8. A storage container for a hydrogen carrier as described in claim 7, wherein the recess is a first recess, the planar portion in which the first recess is formed is a first planar portion, a second planar portion provided on the outer wall surface of the storage container at a position different from the first planar portion, and a second recess formed in a part of the second planar portion so as to be recessed inward more than other parts, and the opening is provided within the second recess.

9. A storage container for a hydrogen carrier as described in any one of claims 1 to 8, further comprising a fitting portion provided on the planar portion, which is capable of fitting with a fitting portion provided on another storage container when the storage container and the other storage container are installed so that their planar portions face each other.

10. A hydrogen carrier storage container as described in claim 9, wherein the fitting portion has a protruding portion protruding from the flat portion and a bent portion bent from the protruding portion in a direction approximately parallel to the flat portion.

11. A storage container for a hydrogen carrier according to any one of claims 1 to 10, wherein the storage container has a cylindrical shape with a polygonal cross section perpendicular to the longitudinal direction.

12. A storage container for a hydrogen carrier as described in any one of claims 1 to 11, wherein the storage section is a first storage section, and further comprises a second storage section for storing a by-product generated together with hydrogen when the hydrogen carrier is reacted with a liquid containing water, and the second storage section does not allow the by-product to pass through to the first storage section, but allows the gas generated in the second storage section to pass through to the first storage section.

13. A storage container for a hydrogen carrier as described in claim 12, comprising: a third planar portion provided on an outer wall surface of the storage container at a position different from the first planar portion; a third recess formed in a part of the third planar portion so as to be recessed inward more than other parts; and a by-product opening communicating the inside and outside of the second storage portion and for injecting by-products into the second storage portion or discharging by-products from the second storage portion, the by-product opening being provided within the third recess.

14. A by-product storage container capable of storing by-products produced together with hydrogen when a hydrogen carrier is reacted with a liquid containing water, comprising: a storage section for storing the by-products; a pair of flat sections provided on both sides of an outer wall surface of the storage container in at least one of the up-down, left-right, and front-to-back directions when the storage container is installed; a recess formed in a portion of at least one of the pair of flat sections, the recess being recessed more inward than other portions of the flat section and having at least a portion thereof communicating with the outside of the flat section in a direction along the flat section; and a relief valve provided within the recess, which automatically opens when the pressure inside the storage section exceeds a predetermined value to release gas inside the storage section to the outside.

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