JP2005147280A - Hydrogen storage device and fuel cell device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inhibit the flow-out of a fibrous nano-carbon material when hydrogen gas is discharged in a hydrogen storage device using the fibrous nano-carbon material as a hydrogen absorption material. <P>SOLUTION: The device is configured so that a container is partitioned into small (N+1) chambers by N partition plates having an opening part; that the partition plates are attached slantly so that the opening part is positioned in a lowermost part with respect to the gravity direction when the hydrogen gas is discharged; and that the small chambers form a bent flowing passage when the hydrogen gas is discharged. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a container structure of a hydrogen storage device, and more particularly to a container structure suitable when a light and fine nanocarbon material is used as a hydrogen storage material.

  In recent years, attempts have been actively made to put a new energy supply device such as a fuel cell into practical use. Among them, the polymer electrolyte fuel cell is an excellent power generation method that takes out electric power through an electrochemical reaction between hydrogen and oxygen and has an extremely low environmental load, in which the exhaust gas is only water vapor.

  Hydrogen used as a fuel in a fuel cell hardly exists in the atmosphere, and since it is a gas, it is dilute and low-density, and since it has a small molecular size, it easily leaks and is associated with an explosion risk. Therefore, whether or not the fuel cell system can be installed in various devices, on-site power generation devices, fuel cell vehicles, etc. depends on how hydrogen, which is a fuel, can be stored and supplied with high density and safety. .

  As hydrogen gas storage methods, high-pressure hydrogen gas cylinders that store in a gaseous state and liquefied hydrogen cylinders that store in a liquid state have been put into practical use, and storage methods using hydrogen storage alloys have been studied for many years. On the other hand, it has been reported that carbon nanotubes, which are a kind of nanocarbon material, occlude 5 to 10% by weight of hydrogen, far surpassing hydrogen-absorbing alloys, and fine powdery carbon-based materials are used as hydrogen-occluding substances. The practical use of the method used is greatly expected.

  A hydrogen storage device using a hydrogen storage alloy or nanocarbon material as a hydrogen storage material fills a hollow container with these hydrogen storage materials, and in addition to a hydrogen gas injection / discharge port, a cooling mechanism and a heating mechanism as required Etc. are attached. Patent Document 1 describes an example of a hydrogen storage device in which a carbon-based hydrogen storage material is housed in a container.

In order to store hydrogen gas in a hydrogen storage device using a hydrogen storage material, it is only necessary to inject hydrogen gas at a certain pressure from the outside. Conversely, to extract hydrogen gas, if the external pressure is reduced, the hydrogen gas is naturally To be released. At this time, in order to improve the occlusion rate and desorption rate, the hydrogen occlusion material is cooled or heated as necessary.
JP 2002-237318 A (FIG. 2)

A nanocarbon material as a hydrogen storage material has a feature of having a large specific surface area and a large amount of hydrogen because it has a fine form of nanometer size. Furthermore, a specific gravity is small compared with the conventional hydrogen storage alloy, and if a nano carbon material is used as a hydrogen storage material, a lightweight and large capacity hydrogen storage device can be realized. However, the unique property of nanocarbon materials with low specific gravity and fineness is considered in conventional hydrogen storage alloys that when hydrogen is released, it is scattered in the container due to the pressure of the hydrogen gas released by itself. It caused new problems that could not be done. Part of the nanocarbon material scattered in the container flows out of the gas discharge port together with hydrogen gas and reaches external devices such as fuel cells, which may cause damage to these external devices. The loss causes a problem that the hydrogen storage capacity is reduced.
In general, as a means for solving such a problem, a filter is inserted into the gas flow path. FIG. 5 is a configuration example of a conventional hydrogen storage device. A filter 9 is attached to the container 7 filled with the nanocarbon material 3 and is filtered by the filter 9 so that the nanocarbon material does not flow out from the hydrogen gas injection / release port 2 when hydrogen gas is released.
In the conventional hydrogen storage device, in order to filter out the nanocarbon material, it is necessary to use a very fine mesh such as a HEPA filter as the filter 9, and the pressure loss increases and the hydrogen gas supply rate decreases. There is a problem. In addition, since the filter is clogged, regular maintenance is indispensable, which increases operating costs. When a fluorinated nanocarbon material with a large hydrogen storage capacity is used as the hydrogen storage material, the filter material is eroded by the liberated fluorine gas or hydrogen fluoride gas, the filter capacity decreases, and stable performance cannot be maintained for a long time. There is a problem.

In order to solve the above problems, the present invention provides:
“A hydrogen storage device in which a nanocarbon material is filled in a container, the container being partitioned into N + 1 chambers by N partition plates having openings, and communicating with each other at the openings of the partition plates. The hydrogen storage device is characterized in that the small chamber that forms a curved flow path when hydrogen gas is released (Claim 1). "
and,
“The partition plate is attached so as to be inclined so that the opening is positioned at the lowest position with respect to the direction of gravity when hydrogen gas is released, and the nanocarbon material is attached to the direction of gravity when hydrogen gas is released. The hydrogen storage device according to claim 1, wherein the lowermost chamber is filled (claim 2). "
and,
“The hydrogen storage device according to claim 2, wherein the container includes a vibration generating device (claim 3)”.
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Further, the present invention is a hydrogen storage device using a hydrogen storage material having an excellent hydrogen storage capacity,
“Hydrogen storage device according to claim 1, wherein the nanocarbon material is a fluorinated nanocarbon material” (Claim 4).
and,
“The hydrogen storage device according to claim 4, wherein the fluorinated nanocarbon material is a fluorinated amorphous nanocarbon material”.
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The present invention also has an excellent hydrogen storage capacity, and as a hydrogen storage device that can maintain stable performance for a long period of time,
“The hydrogen storage device according to claim 4 or 5, wherein the container and the partition plate are made of a material made of at least one of aluminum, aluminum alloy, nickel, nickel alloy, and nickel copper alloy”.
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In addition, the present invention includes the above-described hydrogen storage device, and as a fuel cell device capable of maintaining stable performance for a long time with a small size and light weight,
"Fuel cell device comprising the hydrogen storage device according to any one of claims 1 to 6 (Claim 7)"
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Since the hydrogen storage device according to the present invention uses a nanocarbon material as a hydrogen storage substance, a large amount of hydrogen can be stored while being small and light.

  Since the hydrogen storage device according to the present invention is arranged so that the small chamber divided by the partition plate constitutes a flow path that is bent when hydrogen gas is released, the nanocarbon material scattered in the container when hydrogen gas is released Most of them can be prevented from colliding with the partition plate and falling, diffusing to the hydrogen gas discharge port, and flowing out of the storage device. Therefore, it is not necessary to add a filter to the gas discharge port as in the conventional hydrogen storage device, and the flow rate of hydrogen gas does not decrease due to the permeation resistance of the filter, so that a sufficient hydrogen gas supply rate can be obtained. Further, since the filter cannot be clogged or eroded, periodic maintenance is unnecessary, and the operation cost is reduced.

  If the partition plate is attached so that the opening is at the bottom with respect to the direction of gravity when hydrogen gas is released, and the nanocarbon material is filled in the bottom chamber, it will collide with the partition plate. The dropped nanocarbon material automatically reaches the opening due to gravity, and finally passes through the chambers, and finally returns to the lowermost chamber, that is, the portion where the nanocarbon material is initially filled. For this reason, most of the nanocarbon material always exists in the lowermost chamber, and the probability of flowing out from the hydrogen gas discharge port can be further reduced. At this time, if the entire container is vibrated by the vibration generator, the nanocarbon material can be quickly refluxed to the lower part of the container.

  When a fluorinated nanocarbon material is used as the nanocarbon material, in addition to the above effects, an improvement in the hydrogen storage amount can be expected. In particular, when a fluorinated amorphous nanocarbon material is used, a larger hydrogen storage amount is expected. it can. In the case of using a fluorinated nanocarbon material, if the container and partition plate are made of any material of aluminum, aluminum alloy, nickel, nickel alloy, nickel copper alloy, fluorine or fluoride released from the fluorinated nanocarbon material The container is not eroded by hydrogen, and stable performance can be maintained for a long time.

  The fuel cell device provided with the hydrogen storage device according to the present invention can be reduced in size and weight as a whole, and a sufficient and stable hydrogen supply speed can be obtained at a low operating cost. It can be applied to.

  Hereinafter, the hydrogen storage device according to the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic view showing a first embodiment of a hydrogen storage device according to the present invention, FIG. 1 (a) is a sectional view, and FIG. 1 (b) is a sectional perspective view. A hydrogen gas injection / discharge port 2 for injecting and releasing hydrogen gas is provided at the top of the cylindrical container 1. Five (N = 5) partition plates B1 to B5 are attached to the container 1 so as to protrude from the inner wall, and are partitioned into six small chambers C1 to C6. In the first embodiment, an example in which N = 5 is shown, but there is no particular upper limit to the number N of partition plates in the present invention, and it goes without saying that the higher the number, the higher the effect.

  One end of each partition plate has openings A1 to A5, and the small chambers C1 to C6 communicate with each other through the openings A1 to A5. The larger the opening, the smaller the flow resistance of hydrogen gas released from the nanocarbon material 3, but the effect of suppressing the diffusion of the scattered nanocarbon material is also reduced, so it is selected appropriately according to the target performance do it.

The lowermost chamber C1 is filled with the nanocarbon material 3 as a hydrogen storage material. Nanocarbon material 3 includes fullerene, metal-encapsulated fullerene, nanocarbon particles, single-walled carbon nanotubes, multi-walled carbon nanotubes, amorphous carbon nanotubes, and these nanocarbon materials combined with functional groups that improve hydrogen storage capacity. Any known nanocarbon material having a hydrogen storage capacity can be used without particular limitation. Among the nanocarbon materials, a fluorinated nanocarbon material is particularly suitable as a hydrogen storage material, and a fluorinated amorphous nanocarbon fiber having an amorphous structure as a whole is more preferable. A fluorinated nanocarbon material is a material in which fluorine having high electronegativity is chemically bonded to carbon atoms constituting a carbon fiber, and can absorb a large amount of hydrogen due to a deviation in electron density and has a very low specific gravity. There is a feature. Further, a fluorinated amorphous nanocarbon fiber, which is a kind of fluorinated nanocarbon material, has a high structure defect density because the entire fiber has an amorphous structure, and can absorb a very large amount of hydrogen.

  When a fluorinated nanocarbon material is used as the hydrogen storage material, the container 1 and the partition plates B1 to B5 should be made of a material made of at least one of aluminum, aluminum alloy, nickel, nickel alloy, and nickel copper alloy. Is desirable. This is because these materials have high durability against fluorine and hydrogen fluoride, which may be released from the fluorinated nanocarbon material, and can suppress performance degradation due to corrosion.

A high-pressure hydrogen gas is injected into the hydrogen storage device having the above structure through the hydrogen gas injection / release port 2 to occlude the hydrogen gas in the nanocarbon material 3, and then the hydrogen gas injection / release port 2 is sealed. To store hydrogen. When using the stored hydrogen, an external device such as a fuel cell is connected to the hydrogen gas injection / release port 2 and the hydrogen is released while adjusting the pressure by a pressure reducing valve as necessary. When the pressure in the container 1 decreases due to the release of hydrogen gas, the hydrogen gas automatically desorbs from the nanocarbon material 3, but if the nanocarbon material 3 is heated gently using an appropriate heating means, The gas desorption rate increases, and the hydrogen gas supply rate to the outside can be improved.
When hydrogen gas is released from the hydrogen storage device, a sudden pressure change occurs inside the container 1 due to the hydrogen gas desorbed from the nanocarbon material, and turbulence is generated. Since the nanocarbon material 3 in the lower part of the container 1 has a small specific gravity and has a fine powder form, a part thereof is easily scattered by this turbulent flow. The scattered nanocarbon material starts to diffuse from the lower part in the container 1 to the upper part on the hydrogen gas flow. At this time, since the partition plates B1 to B5 are attached to the inside of the container 1, most of the scattered nanocarbon material first collides with the partition plate B1 and falls to be excluded from the hydrogen gas flow. The nanocarbon material that did not fall here flows in a hydrogen gas flow and sequentially flows into the small chambers C2 to C6 that are in communication with each other through the opening as shown by arrows in FIG. At this time, since the partition plate and the opening are arranged so that the hydrogen gas flow path is bent, most of the nanocarbon material that has flowed in from the opening A1 collides with the partition plate B2 and falls, and so on. This removes the nanocarbon material from the hydrogen gas stream for each chamber. As a result, the probability that the nanocarbon material finally reaches the hydrogen gas injection / release port 2 is extremely small.

  2A and 2B are schematic views showing a second embodiment of the hydrogen storage device according to the present invention. FIG. 2A is a sectional view, and FIG. 2B is a sectional perspective view. FIG. 2 shows the arrangement at the time of hydrogen gas release, and gravity works toward the lower side of the figure. Since the container 1, the hydrogen gas injection / discharge port 2 and the nanocarbon material 3 are the same as those in the example of FIG. In the second embodiment, the partition plates B1 to B5 are attached so as to be inclined so that the openings A1 to A5 are located on the lowermost side.

  In the hydrogen storage device according to the second embodiment, the nanocarbon material scattered when hydrogen gas is released is excluded from the hydrogen gas flow by the partition plate, as in the first embodiment. Since the plates B1 to B5 are attached so as to be inclined so that the openings A1 to A5 are at the bottom, the nanocarbon material dropped on the partition plate moves toward the openings by gravity and finally reaches the bottom. It will return to the lower chamber C1. As a result, most of the nanocarbon material always exists in the lowermost chamber, and the probability of flowing out from the hydrogen gas discharge port can be further reduced.

The movement of the nanocarbon material is automatically performed by gravity, but is accelerated by applying vibration to the container 1. The recovery rate of the scattered nanocarbon material increases as the inclination of the partition plate becomes steeper, but the space utilization rate decreases. Therefore, the inclination may be set in consideration of the efficiency of the entire hydrogen storage device.

  3A and 3B are schematic views showing a third embodiment of the hydrogen storage device according to the present invention. FIG. 3A is a sectional view, and FIG. 3B is a sectional perspective view. FIG. 3 shows the arrangement at the time of hydrogen gas release, and gravity works toward the lower side of the figure. Since the container 1, the hydrogen gas inlet / outlet 2 and the nanocarbon material 3 are the same as those in the first and second embodiments, description thereof will be omitted.

  In the third embodiment, an axially symmetric partition plate is provided in the container. Partition plates D1 to D4 are attached in the cylindrical container 1 and partitioned into a total of five chambers E1 to E5. The nanocarbon material 3 which is a hydrogen storage material is filled in the lowermost chamber E1. Similar to the example of FIG. 1, the number of partition plates (N = 4) is merely an example, and in practice, the larger the number, the more effective.

  Partition plates D1 and D3 have a downwardly convex dish shape, and have openings F1 and F3 in the center. Moreover, the partition plates D2 and D4 form an upwardly convex umbrella shape, and are attached so as to have openings F2 and F4 between the inner wall of the container 1. At this time, when the opening F2 or F4 is provided over the entire circumference of the partition plate D2 or D4, the partition plate D2 or D4 cannot be directly fixed to the container 1, so that the hydrogen gas flow is not hindered. What is necessary is just to fix to the partition plate D1 or the partition plate D3 with the columnar member etc. which have thickness. When the opening F2 or F4 is not provided over the entire circumference of the partition plate D2 or D4, the partition plate D2 or D4 may be fixed to the inner wall of the container 1 at the closed portion.

  The hydrogen gas released from the nanocarbon material 3 sequentially passes through the small chambers E1 to E5 communicating with each other in the openings F1 to F4 and reaches the hydrogen gas injection / discharge port 2. Most of the nanocarbon material scattered by the turbulent flow generated when hydrogen gas is released collides with the partition plate D1 and returns to the lowermost chamber E1. On the other hand, some of the nanocarbon material passes through the opening F1 and diffuses upward, but the gas flow path is bent as shown by the arrow in FIG. Most of the carbon material collides with the partition plate D2 and falls, and is excluded from the hydrogen gas flow. Similarly, most of the nanocarbon material that has passed through the opening F2 is eliminated by the partition plate D3, and the probability of finally reaching the hydrogen gas injection / discharge port 2 is very small.

  The nanocarbon material excluded from the hydrogen gas flow by each partition plate falls on the partition plate located in the lower part, but each partition plate is arranged so as to have an opening at the bottom in the direction of gravity. Therefore, the nanocarbon material dropped on the partition plate automatically moves sequentially through the opening to the lower chamber and finally returns to the lowermost chamber E1.

  In the third embodiment, a vibration generator 4 is provided at the lowermost part of the container 1, and the vibration is transmitted to the partition plates D1 to D4 by vibrating this at an appropriate frequency and amplitude, and the chambers E2 to E4 are transmitted. A certain nanocarbon material can be quickly moved to E1.

  As mentioned above, although the embodiment of the hydrogen storage device according to the present invention has been described with three examples, the embodiment of the present invention is not limited to these examples, and the required hydrogen storage capacity, hydrogen supply rate, and filling The shape of the partition plate and the opening can be changed or the number of partition plates can be increased or decreased in accordance with the characteristics of the nanocarbon material to be performed.

  Next, an embodiment of a fuel cell device according to the present invention will be described.

  FIG. 4 is a schematic view showing an example of a fuel cell device according to the present invention, and shows an example applied to a solid polymer fuel cell.

  A pressure gauge 10 is attached to the hydrogen gas inlet / outlet 2 of the hydrogen storage device 5, and the pressure of the hydrogen gas in the container 1 can be measured. When hydrogen is stored in the hydrogen storage device 5, high-pressure hydrogen gas from an external hydrogen source such as a hydrogen station is injected into the hydrogen storage device 5 through the pipe 11 with the valves 12 and 13 opened and the valve 14 closed. To do. If each valve is closed when the pressure gauge 10 reaches an appropriate pressure, hydrogen is stored in the hydrogen storage device 5.

  When taking out electric power using the stored hydrogen as a fuel, the valve 13 and the valve 14 are opened, and the pressure regulator 15 adjusts the pressure to release hydrogen gas. Hydrogen gas is supplied to the fuel electrode 20 of the fuel cell 19 through the humidifier 17, while air is supplied to the air electrode 21 from the air supply device 18 through the humidifier 16. In the fuel cell, an electromotive force is generated by an electrochemical reaction, and a current can be taken out from the output terminal 22.

  Here, a solid polymer fuel cell has been described as an example. However, the fuel cell device according to the present invention may be of an alkaline type, a phosphoric acid type, a molten carbonate type, or a solid oxide type. By providing the hydrogen storage device, the same effect can be obtained.

It is the schematic which shows an example of the hydrogen storage apparatus which concerns on this invention. It is the schematic which shows an example of the hydrogen storage apparatus which concerns on this invention. It is the schematic which shows an example of the hydrogen storage apparatus which concerns on this invention. It is the schematic which shows an example of the fuel cell apparatus which concerns on this invention. It is the schematic which shows an example of the conventional hydrogen storage apparatus.

Explanation of symbols

1: container, 2: hydrogen gas inlet / outlet, 3: nanocarbon material, 4: vibration generator, 5: hydrogen storage device, 7: container, 9: filter, 10: pressure gauge, 11: piping, 12 to 14: Valve, 15: Pressure regulator, 16: Humidifier, 17: Humidifier, 18: Air supply device, 19: Fuel cell, 20: Fuel electrode, 21: Air electrode, 22: Output terminal, A1 to A5 : Opening, B1 to B5: partition plate, C1 to C6: small chamber, D1 to D4: partition plate, E1 to E5: small chamber, F1 to F4: opening

Claims (7)

A hydrogen storage device in which a container is filled with a nanocarbon material, and the container is partitioned into N + 1 chambers by N partition plates having openings, and communicates with each other at the openings of the partition plates. The hydrogen storage device, wherein the small chamber forms a flow path that is bent when hydrogen gas is released. The partition plate is attached so as to be inclined so that the opening is positioned at the lowest position with respect to the direction of gravity when hydrogen gas is released, and the nanocarbon material is positioned at the highest position with respect to the direction of gravity when hydrogen gas is released. 2. The hydrogen storage device according to claim 1, wherein the lower chamber is filled. The hydrogen storage device according to claim 2, wherein the container includes a vibration generator. The hydrogen storage device according to any one of claims 1 to 3, wherein the nanocarbon material is a fluorinated nanocarbon material. The hydrogen storage device according to claim 4, wherein the fluorinated nanocarbon material is a fluorinated amorphous nanocarbon material. 6. The hydrogen storage device according to claim 4, wherein the container and the partition plate are made of a material made of at least one of aluminum, aluminum alloy, nickel, nickel alloy, and nickel copper alloy. A fuel cell device comprising the hydrogen storage device according to any one of claims 1 to 6.

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