JPH09142801A - Vessel with hydrogen-occluded alloy molding housed therein and method of housing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent hydrogen gas flow into the subject molding from lowering by securing the flow channel of hydrogen gas to the molding housed in a vessel, to absorb the stress of the volume expansion of hydrogen-occluded alloy, and to raise the packing rate of the alloy in the vessel. SOLUTION: Plural hydrogen-occluded alloy moldings are put into a vessel, and hydrogen gas-permeable sheets 3 are sandwiched between these moldings 1. Each of the sheets 3 is placed in between the moldings 1 adjacent to each other from one end of the vessel 2 to the other end and thus made to communicate with both the inlet/outlet 21 for hydrogen gas. The sheet 3 is made of a porous material having buffering effect, thus enabling the stress developed by the volume expansion of the hydrogen-occluded alloy to be absorbed onto the sheets 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to accommodating a hydrogen storage alloy compact in a container.

[0002]

2. Description of the Related Art In recent years, hydrogen has been used as an energy source for heat pumps, fuel cells and the like. As a method of storing and transporting this hydrogen, a hydrogen storage alloy that stores and releases hydrogen has been used. As a method of using the hydrogen storage alloy, a powder obtained by crushing a hydrogen storage alloy ingot is filled in a container, and hydrogen is stored in the container for storage and transportation,
Further, by releasing hydrogen from the container, the heat pump,
It is known to supply to fuel cells and the like. In order to increase the amount of hydrogen storage / release per unit volume of the container, high density packing of hydrogen storage alloy into the container is desired. Therefore,
The powder obtained by crushing the hydrogen-absorbing alloy ingot is not simply packed in a container, but the powder is mixed with a binder in advance and compression molded to prepare a molded body, and the molded body is housed in a container. The method has also been adopted.

[0003]

The hydrogen storage alloy expands in volume due to storage of hydrogen. Therefore, when the molded body is housed in the container, if the outer diameter of the molded body and the inner diameter of the container are made substantially the same, the flow path of hydrogen gas is blocked by the expansion. Therefore, as shown in FIG. 8, the outer diameter of the molded body (c) is set to the container.
It was necessary to make it smaller than the inner diameter of (2) and to secure a gap (4) between the molded body and the container such that hydrogen gas could sufficiently flow.

However, if the volume of the compact is reduced, the filling amount of the hydrogen storage alloy in the container is reduced, and the hydrogen storage / release amount is reduced. Further, when the volume of the compact is reduced, the hydrogen storage alloy near the outer peripheral surface comes into contact with hydrogen gas, but the hydrogen storage alloy near the center of the compact does not have sufficient hydrogen gas flow. Cannot be used as a whole.

The present invention prevents a decrease in the flow rate of hydrogen gas to the molded body by ensuring the flow path of hydrogen gas of the molded body housed in the container, and also stresses due to the volume expansion of the hydrogen storage alloy. The purpose is to absorb. Furthermore, it is intended to increase the filling rate of the hydrogen storage alloy in the container.

[0006]

In order to solve the above problems, in the present invention, a plurality of hydrogen storage alloy molded bodies are placed in a container, and the space between the molded body (1) and the molded body (1) is increased. A sheet (3) permeable to hydrogen gas is sandwiched between the sheet (3) and the sheet (3) is provided between one of the adjacent molded articles (1) and (1). The sheet (3) is arranged from one end to the other so that the sheet (3) communicates with the hydrogen gas inlet / outlet (21). The hydrogen-permeable sheet (3) provided between the molded body (1) and the molded body (1) serves as a flow path for hydrogen gas. Therefore, even if the molded body (1) occludes hydrogen and expands in volume, hydrogen gas circulates through the sheet (3) and the decrease in hydrogen gas flow rate is suppressed. If the hydrogen gas permeable sheet (3) is made of a porous material having a buffering effect, the sheet (3) can absorb the stress generated by the volume expansion of the hydrogen storage alloy.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. In the present invention, the material, shape, and size of the container (2) to be used are not particularly limited, and the same one as the conventional one can be used. The molded body (1) can also be manufactured by a known manufacturing method.

As the hydrogen gas permeable sheet (3), it is possible to use a sheet made of a porous material, for example, a paper filter, a glass fiber filter paper, a urethane porous body, a sponge or the like. It is particularly preferable to form the sheet (3) with a material having a buffering action, since the stress generated when the hydrogen storage alloy molded body (1) stores hydrogen can be buffered and absorbed.

As a specific example of sandwiching the sheet (3) between the molded bodies (1) and (1), a columnar molded body is divided into two in the vertical direction to produce a semi-cylindrical molded body (1) (1). And divided planes (12) (12)
The sheet (3) is scraped off, and the sheet (3) is sandwiched between the cut surfaces as shown in FIGS.
Can be accommodated. Here, the divided planes are respectively cut so that the molded bodies (1) and (1) have a columnar shape when assembled by sandwiching the sheet (3). For example, it is not necessary to grind both of the divided planes, and it is possible to grind only one plane. Alternatively, a semicylindrical shaped body (1) may be manufactured from the beginning. FIG. 4 shows the ratio (x / a) of the thickness of the sheet (3) to the inner diameter of the container and the inside of the container of hydrogen storage alloy, where x is the thickness of the sheet (3) and a is the inner diameter of the container (2). It is a graph which shows the relationship with a filling rate. In FIG. 4, the horizontal axis represents the ratio (x / a) of the thickness of the sheet (3) to the inner diameter of the container,
The filling rate in the container is shown on the vertical axis. The "filling ratio in the container" is represented by m / αV, where V is the container (2), m is the weight of the hydrogen storage alloy, and α is the density of the hydrogen storage alloy. Further, the filling rate in the container when the thickness of the sheet (3) is zero corresponds to the filling rate of the hydrogen-absorbing alloy of the molded body (1), which means that the volume of the molded body (1) is V ′, hydrogen. When the weight of the storage alloy is m'and the density of the hydrogen storage alloy is α ', m' / α '
It is indicated by V '. From FIG. 4, as the sheet (3) is made thicker, the amount of hydrogen storage alloy that can be filled in the container (2) decreases and the amount of hydrogen that can be stored decreases. Therefore, the sheet
It is desirable to adjust the thickness of (3) so that the desired filling rate in the container can be maintained.

Alternatively, as shown in FIG. 5, the cylindrical molded body (10), which is shorter than the axial length of the container (2), is divided into semi-cylindrical shapes, and the divided surfaces are each ground. Sheet (3)
It can also be housed in the container (2) by sandwiching it. Further, when stress relaxation of the container due to alloy expansion is considered important, as shown in FIG. 6, the outer diameter of the molded body shown in FIGS.
The sheet (30) may be wrapped around the periphery of the molded body (1) by making it slightly smaller than the inner diameter of (2).

Although the container (2) has a circular sectional shape in the drawing, it may have a rectangular shape or the like if necessary.
In this case, according to the cross-sectional shape of the container (2), the molded body (1)
May be rectangular or the like.

[0012]

EXAMPLES In order to investigate the effects of the present invention, first, a hydrogen storage alloy compact was prepared by the following method. Molded body preparation alloy Rare earth-Ni binder Binder PTFE (tetrafluoroethylene) mixing ratio Alloy: PTFE = 9: 1 (weight ratio) After alloy and binder are mixed and molded at 1500 kg / cm ² , 37
It is fired at 0 ° C. for 2 hours to produce a cylindrical molded body.

Using the hydrogen storage alloy molded body produced by the above method, two types of conventional molded body (test molded body (b) ( c)) Prepared. Preparation of test compact (a) (Example of the present invention) A large number of cylindrical compacts having a diameter of 22 mm and a height of 10 mm were produced under the above conditions. This molded body is vertically divided into two parts each in a plane passing through a diameter to form a semi-cylindrical molded body, and a 1 mm glass fiber paper sheet (3) is sandwiched between the semi-cylindrical molded bodies. , The divided plane of each molded body is 0.5 mm
I scraped each one. A glass fiberboard sheet (3) was sandwiched between the cut planes of these molded bodies to prepare a test molded body (a). In this embodiment, one sheet (3) is used for one container (see FIG. 5). Manufacture of test compacts (b) and (c) (comparative example) Depending on the conditions for producing the above-mentioned compact, a diameter of 22 mm and a height of 10 mm
A large number of columnar molded bodies of (1) were prepared and used as a test molded body (b). Further, under the same manufacturing conditions, a large number of molded products (diameter 19 mm, height 12 mm) having a smaller diameter than the test molded product (b) were manufactured to obtain a test molded product (c).

The test compacts (a), (b) and (c) are stacked and housed in a stainless steel container (2). The container (2) has an outer diameter of 2
It has a cylindrical shape of 5.4 mm, an inner diameter of 22.1 mm and an inner length of 150 mm, and a hydrogen gas inlet / outlet port (21) is projectingly formed at one end thereof. The test compacts (a), (b) and (c) were vertically stacked in the container (2) in 14-tiers, respectively. FIG. 5 is a vertical cross-sectional view of the test molded body (a) of the present invention housed in a container, in which the molded body is stacked in five stages. The cross-sectional view of FIG. 5 is similar to FIG. 2, which is the cross-sectional view of FIG. or,
FIG. 7 is a cross-sectional view of the container (2) containing the sample molded body (b). The molded body (b) has an outer diameter substantially equal to the inner diameter of the container (2). Almost cannot flow between the container (2) and the molded body (b). Further, FIG. 8 is a cross-sectional view of the container (2) accommodating the test molded body (c). Molded body
Since the outer diameter of (c) is smaller than the inner diameter of the container (2), a gap (4) is formed between the container (2) and the molded body (c).
Are formed.

Comparative Experiments A container (2) containing the test compacts (a), (b) and (c) was charged with hydrogen gas whose pressure difference between the containers was 1.5 atm. The relationship between the hydrogen absorption amount of the molded body, the hydrogen flow rate and the container internal pressure was measured. Table 1 shows the measurement results.

[0016]

[Table 1]

When the measurement results of Table 1 were plotted with the hydrogen absorption amount as the horizontal axis and the hydrogen flow rate as the vertical axis, the graph shown in FIG. 9 was obtained. In addition, through in FIG. 9 correspond to through in Table 1. From Fig. 9, the conventional test compact (b)
Indicates that the hydrogen flow rate decreases in inverse proportion to the increase in the hydrogen absorption amount. This is due to the increase in hydrogen absorption,
This is because the hydrogen storage alloy expands, the volume of the compact increases, and the hydrogen gas flow channel narrows. Regarding the sample molded body (c), when the hydrogen absorption amount is small, the flow path of hydrogen gas is secured by the gap (4) formed between the container (2) and the molded body (c). Therefore, the flow rate of hydrogen is maintained higher than that of the test compact (a) of the present invention. However, when the hydrogen absorption amount increases (particularly, the hydrogen absorption amount is 1.0 wt% or more) and the volume expansion of the molded body (c) proceeds, the gap (4) is closed by the molded body (c), and the flow of hydrogen gas is increased. The road narrows,
It can be seen that the hydrogen flow rate decreases. On the other hand, in the case of the molded article (a) of the present invention, the hydrogen flow rate did not decrease with the increase of the hydrogen absorption amount, and the hydrogen absorption amount was about 1.2 wt% of the weight of the molded product.
It is understood that the flow path of hydrogen gas is stably secured until Further, usually, in a fuel cell or the like, the hydrogen storage alloy is used by absorbing hydrogen gas until the hydrogen absorption amount becomes 1.35 to 1.4 wt%. Test molded article of the present invention (a)
Can stably absorb hydrogen even when the amount of absorbed hydrogen exceeds about 1.0 wt%.
Better than (c). Also, the test compact (a) has a larger contact area with hydrogen gas than the conventional cylindrical compact because the compact is divided into two, and the reaction rate between the hydrogen storage alloy and hydrogen gas is high. Is considered to be faster than the test compacts (b) and (c).

Next, plotting the measurement results in Table 1 using the hydrogen absorption amount as the horizontal axis and the container internal pressure as the vertical axis, the graph shown in FIG. 10 was obtained. 10 to Table 1
Corresponds to the inside. From FIG. 10, it can be seen that in the conventional molded body (b), the internal pressure of the container increases almost in proportion to the amount of absorbed hydrogen. This is because the stress generated when the hydrogen storage alloy stores hydrogen and expands in volume is directly
It is thought that it is because of joining (2). In addition, since the conventional molded body (c) has a gap (4) between the container (2) and the molded body (c), the hydrogen absorption is about 1.0 wt% or less. The volume expansion of the molded body (c) due to occlusion spreads in the gap (4) and is hardly added to the container (2). However,
When the absorption of hydrogen further progresses and the absorbed amount exceeds about 1.0 wt%, the molded body (c) and the container (2) come into contact with each other, and thereafter, like the sample molded body (b), It can be seen that the internal pressure is applied to the container (2) almost in proportion to the increase in the hydrogen absorption amount.
Compared with the sample molded body (b), the sample molded body (a) of the present invention showed an extremely small increase in internal pressure and a hydrogen absorption amount of about 1.3 w.
When it exceeds t%, the internal pressure applied to the container (2) becomes smaller than that of the test molded body (c). At the initial stage, the internal pressure applied to the container (2) increases because the molded body and the container (2) are in contact with each other from the beginning, and the internal pressure hardly increases thereafter between the molded bodies. This is because the sheet (3) sandwiched between the layers absorbs and absorbs the stress due to the volume expansion of the hydrogen storage alloy. Further, as described above, the hydrogen storage alloy is usually used by absorbing hydrogen until the amount of absorbed hydrogen in the hydrogen storage alloy reaches 1.35 to 1.4 wt%. The test molded article (a) of the present invention is particularly superior to the conventional molded articles (b) and (c) because the internal pressure applied to the container (2) hardly changes even when the hydrogen absorption amount increases. There is.

[0019]

EFFECTS OF THE INVENTION According to the container containing the molded article of the hydrogen storage alloy of the present invention, the hydrogen storage alloy absorbs hydrogen and the molded body
Even if the volume of (1) expands, the hydrogen permeable sheet (3) secures the flow path of hydrogen gas, and therefore the decrease in hydrogen flow rate can be suppressed. Further, when the hydrogen permeable sheet (3) is formed of a material having a buffering action, a hydrogen gas flow path is secured even if the molded body expands in volume, and the stress due to the volumetric expansion of the molded body is buffered. Since it can be absorbed, the internal pressure applied to the container can be reduced. Moreover, since the internal pressure applied to the container is reduced due to the volume expansion of the molded body, the filling rate of the hydrogen storage alloy can be increased.

The above description of the embodiments is for explaining the present invention, and should not be construed as limiting the invention described in the claims or reducing the scope. Further, the configuration of each part of the present invention is not limited to the above-described embodiment, and it is needless to say that various modifications can be made within the technical scope described in the claims.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of a container accommodating a molded article of the hydrogen storage alloy of the present invention.

FIG. 2 is a sectional view taken along the line XX of FIG.

FIG. 3 is a perspective view showing an assembly of a molded body and a sheet.

FIG. 4 is a graph showing the relationship between the sheet thickness ratio (x / a) and the filling rate in the container.

FIG. 5 is a sectional view showing another embodiment of the present invention.

FIG. 6 is a sectional view showing still another embodiment of the present invention.

FIG. 7 is a cross-sectional view of a container accommodating a molded article under test (b).

FIG. 8 is a cross-sectional view of a container accommodating a test molded body (c).

FIG. 9 is a graph showing a relationship between a hydrogen absorption amount and a hydrogen flow rate.

FIG. 10 is a graph showing the relationship between hydrogen absorption amount and container internal pressure.

[Explanation of symbols]

 (1) Molded body (2) Container (3) Sheet

Claims (3)

[Claims] 1. A container (2) having a hydrogen gas inlet / outlet (21) for accommodating a plurality of hydrogen storage alloy molded bodies (1), comprising a molded body (1) and a molded body (1) which are adjacent to each other. A hydrogen gas permeable sheet (3) is provided between the one end portion and the other end portion, and the sheet (3) is communicated with the hydrogen gas inlet / outlet port (21). A container containing a storage alloy molded body. 2. The container according to claim 1, wherein the hydrogen gas permeable sheet (3) is composed of a porous material having a buffering action. 3. A container containing a plurality of hydrogen storage alloy compacts (1).
A method of accommodating in (2), comprising a molded body (1) and a molded body (1)
A hydrogen gas permeable sheet (3) is sandwiched between
A method for accommodating a hydrogen storage alloy molded body in a container, characterized in that (3) is housed in a container (2) together with the molded body.