JPS6224679B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is directed to a metal element or an alloy that stores hydrogen in a sealable container having a heat exchanger to form a metal hydride, and also to improve thermal conductivity and air permeability. This invention relates to a hydrogen storage container containing a sponge-like or fibrous metal porous piece.

Conventional technology Conventionally, there are methods for storing hydrogen using high-pressure gaseous hydrogen or liquid hydrogen, but high-pressure gaseous hydrogen requires a heavy pressure-resistant container, and while liquid hydrogen can have a small volume, it is difficult to store ultra-low-temperature liquid. When handling it, sufficient care must be taken to prevent gas loss due to evaporation and safety.

Problems to be Solved by the Invention As a method for solving these problems, a method of solidifying hydrogen, that is, storing it as a metal hydride, has been proposed. When this metal hydride is repeatedly absorbed and released hydrogen, the metal hydride becomes
It is pulverized to ~several 10 microns, and a coarse/dense distribution tends to occur in the fine powder layer inside the hydrogen storage container. for example,
Due to vibrations, shocks, etc., the fine powder layer becomes denser, especially toward the bottom of the container. Since the bulk specific gravity of this portion increases, the space is significantly reduced, hydrogen diffusion is slow, hydrogen filling and discharging time is long, and the hydrogen storage efficiency is also reduced. In order to improve this drawback, it has been proposed to contain inorganic or organic granular fillers such as porous and breathable alumina foam or urethane foam (Japanese Patent Laid-Open No. 51-16279
Publication No.). However, the improvement caused by these fillings was not so remarkable, and when we investigated the cause, we found that the thermal conductivity was very poor, making it extremely inefficient when heat was transferred through the heat exchanger. I understood.

The present invention provides hydrogen diffusion and hydrogen occlusion and
The aim is to simultaneously solve issues such as release rate and thermal conductivity.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides the use of a spongy or fibrous metal material having thermal conductivity and air permeability together with a metal hydride in a sealable container having a heat exchanger. The volume ratio of the porous pieces to the entire filling is 1/4 or less, and the porous pieces are dispersed so that the dispersion density at the top side of the container is smaller than that at the bottom side of the container. The present invention provides a hydrogen storage container.

Effect: By configuring as described above, heat conduction to the entire filling material becomes good, hydrogen diffusion becomes easy, and hydrogen release/occlusion in the metal hydride can be enhanced.

Examples Hereinafter, details of the present invention will be explained along with examples.

In Figure 1, 1 is a hydrogen gas pipe, and valve 2
is connected to a joint 5 at the tip of the metal container 4 via a pressure gauge 3. A serpentine tube 6 for a heat exchanger is attached to the metal container 4, and water or hot water is supplied through an inlet 7 and discharged through an outlet 8. metal container 4
There is a thermally conductive layer inside the metal hydride 9 filling layer.
Porous pieces 10 of breathable spongy or fibrous metal are dispersed therein. Also, hydrogen conduction pipe 1
A pressure gauge 3 is attached to the container 4 so that the pressure inside the container 4 can be determined when hydrogen gas is supplied and transported.

As the metal materials constituting the metal hydride, commercially available titanium and manganese were weighed to have a TiMn composition ratio of _{1.5 and} heated and melted several times in an arc melting furnace.
TiMn _1.5 alloy was used _. Next, this alloy was finely ground into amorphous particles with a major axis of 2 to 3 cm, hydrogenated, and then used as a sample. The weight of the alloy used is 6Kg, and the effective amount of hydrogen in that alloy is 180ml/g, so the effective amount of hydrogen contained in the total weight of the 6Kg alloy is:
It is 1080. Note that the hydrogen storage container has a diameter of approx.
It is a cylindrical container with a length of 70 mm and a height of 500 mm and an internal volume of approximately 2.

In addition, as a sponge-like porous metal piece that has thermal conductivity and air permeability, it is a sponge-like porous nickel material that has relatively fine mesh and three-dimensionally continuous voids, and has a porosity of 90. ~98%, pore size 20
~100μ, thickness 1.5~5.0mm, and major axis 5~20mm were adopted.

A container having the above structure is designated as A, a conventional container using an alumina foam instead of a porous metal material is designated as B, and a container containing only metal hydride is designated as C.

FIG. 2 shows the relationship between the hydrogen component x of the hydride TiMn _{1.5 -H x} and the equilibrium hydrogen dissociation pressure.

Figure 3 shows TiMn _{1.5 −H x} with such characteristics.
This figure shows the hydrogen release characteristics in each of the above containers. The hydrogen release conditions were as follows: 50°C hot water was passed through a heat exchanger to heat the hydride, and the hydrogen release rate was 5/5.
It was a minute. Hydrogen release characteristics were determined by sucking and removing the occluded hydrogen in the container using a vacuum pump, then allowing hydrogen to be occluded to a complete state and releasing hydrogen at an ambient temperature of 25°C and 1 atm.

Comparing these hydrogen release characteristics, C is approximately
Only 700 can release hydrogen gas.
This value is a release rate of approximately 65% of the total hydrogen storage of 1080. B was able to release about 850 hydrogen gas, but the total hydrogen storage was about 1080
The release rate is 80%. On the other hand, A is about 1070
of hydrogen gas, and the total hydrogen storage capacity is 1080
This corresponds to a release rate of almost 100%.

Furthermore, as one of the conventional examples, even when urethane foam particles were substituted for the alumina foam, the hydrogen release rate was only about the same as B. However, when a metal fibrous porous piece according to the present invention was inserted, the hydrogen release rate was 95%.

As described above, according to the present invention, the hydrogen release rate is significantly faster than that of the conventional type, and stored hydrogen can be used effectively. By dispersing porous metal pieces that have good heat conductivity as well as air permeability in the metal hydride in the metal container, heat dissipation or heat supply from the heat exchanger is carried out through the porous metal. This is because the whole metal hydride is heated quickly through the piece, and the heating of the whole metal hydride proceeds smoothly.
Furthermore, since it is a porous metal material with good air permeability, hydrogen diffusion and movement proceed more efficiently.
This is one of the reasons. In addition, the presence of this metal porous body plays an important role in ensuring hydrogen release characteristics, in order to prevent the density from becoming so high that it reaches the bottom of the container due to the load of the metal hydride itself.

On the other hand, in conventional type C, the bottom part becomes denser due to the load of finely divided metal hydride.
Despite preventing hydrogen diffusion and heating with hot water, the amount of hydrogen gas released is reduced. If alumina foam or resin foam is placed in the metal hydride to improve hydrogen diffusion, the amount of hydrogen gas released will increase slightly, but since these have poor thermal conductivity, they will not be able to escape from the heat exchanger. heat transfer is not sufficiently carried out over all metal hydrides, and heating of all metal hydrides does not proceed smoothly, so the effect is small.

Although a TiMn _1.5 alloy was used in the examples, other metal materials can be used, especially _at least Ti and
TiMn-based binary or multi-component systems containing Mn are excellent.

Further, as the metal constituting the sponge-like porous body and the fibrous porous body, iron, copper, zinc, etc. may be used. The volume occupied by these porous bodies is preferably about 1/4 or less of the volume of the entire filling. When it becomes 1/4 or more, the amount of hydrogen storage decreases. Then, it is preferable that the dispersion density of the porous body pieces is decreased and the amount of metal hydride is increased toward the hydrogen supply side in the upper part of the container. That is, the amount of porous material pieces is increased on the bottom side of the metal container, and the amount of metal hydride is relatively reduced. The reason for this is to prevent the metal hydride from becoming denser at the bottom of the container, and because the temperature drop due to the endothermic reaction during hydrogen release restricts hydrogen release from the metal hydride at the bottom. Keep the amount of
This is to ensure that all the hydrogen is released before the temperature drops. By adopting this configuration,
The amount of hydrogen released can be improved.

As described above, the present invention improves both the thermal conductivity and hydrogen gas permeability, which are important for a metal hydride storage container. Comparing this invention with the container described in JP-A-55-126199 in which a metal hydride is held in a sponge-like porous metal body previously proposed by the present inventors, the present invention is a The effective heat transfer area is increased, the thermal conductivity is further improved, and it is possible to provide a storage container that is simple in structure and practical.

Effects of the Invention As described above, according to the present invention, it is possible to facilitate hydrogen diffusion, improve the hydrogen release/storage ability, and increase the speed.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of a hydrogen storage container according to an embodiment of the present invention, FIG. 2 is a diagram showing the relationship between the hydrogen component x of TiMn _{1.5 -H x} and the equilibrium hydrogen dissociation pressure, and FIG. A comparison of hydrogen release characteristics of storage vessels is shown. DESCRIPTION OF SYMBOLS 1... Hydrogen gas pipe, 4... Container, 6... Heat exchange tube, 9... Metal hydride, 10... Porous body piece.

Claims (1)

[Claims] 1 A sealable container having a heat exchanger is filled with particles of a single metal or alloy that absorbs hydrogen and becomes a metal hydride, and the filling layer is filled with a sponge-like or alloy material having thermal conductivity and air permeability. The porous pieces of fibrous metal are dispersed so that the volume ratio of the entire filling is 1/4 or less, and the dispersion density of the porous pieces on the top side of the container is smaller than that on the bottom side of the container. A hydrogen storage container featuring: