JPH0353969B2 - - Google Patents

Description

[Detailed Description of the Invention] Purpose of the Invention Industrial Field of Application The present invention aims to absorb hydrogen into hydrogenated metal powder,
Alternatively, the present invention relates to a moving bed reactor for releasing hydrogen from hydrogenated metal powder that has occluded hydrogen.

Prior Art Attempts have already been made to convert thermal energy into pressure energy using metal hydrides. That is, MH(m+n)MHm+n/2H ₂ ±△
H (M is a hydrogen storage alloy) reaction is used to absorb hydrogen into a metal hydride and then raise the temperature to generate higher pressure hydrogen.

However, the conventionally proposed technology involves supplying low-pressure hydrogen to a reactor filled with metal hydride while cooling it to absorb hydrogen, and then heating the same reactor to release high-pressure hydrogen. This is a batch-type method that repeats the process.

Problems to be Solved by the Invention The above-mentioned prior art has the following problems.
That is, (1) As hydrogen occlusion and release are repeated, the metal hydride gradually becomes pulverized, so clogging of the device by the pulverized powder becomes a major problem.

(2) In order to continuously obtain high-pressure hydrogen, two or more reactors must be installed and the cycles must be staggered for operation. Therefore, the system becomes complicated due to valve switching, etc.

(3) The pressure of hydrogen changes as it is released, so a pressure equalization tank, etc. is required to constantly obtain high-pressure hydrogen.

(4) The entire system must be designed for high pressure operating conditions.

(5) Finely divided metal hydride acts as a heat transfer resistance, and its heat transfer characteristics cannot be quantitatively determined.
Difficult to design.

(6) Since heating and cooling are repeated in one reactor,
Energy conversion efficiency is low.

(7) There is no effective means for separating metal hydride powder entrained in high-pressure hydrogen gas and returning it to the reaction system.

One possible solution to these problems is a continuous process in which a hydrogen storage reactor and a hydrogen release reactor are installed separately and the hydrogenated metal powder is circulated. A suitable reactor had not yet been developed.

Metal hydride generates a large amount of heat when absorbing hydrogen, and absorbs a large amount of heat when releasing hydrogen. As a result, hydrogen storage or desorption reactions are effectively rate-limited by the heat exchange rate. As mentioned above, as metal hydride repeatedly absorbs and desorbs hydrogen, it becomes fine and the heat transfer resistance gradually increases. Therefore, in continuous operation, it is especially important to create a structure that allows for rapid heat exchange and miniaturization of the equipment. This is important in this respect. It is also important to reduce the diffusion resistance of hydrogen in the metal hydride powder layer as much as possible in order to accelerate the reaction rate.

The present invention provides a moving bed reactor for metal hydride that solves these problems.

Means for Solving the Constituent Problems of the Invention Namely, the moving bed reactor of the present invention has the following features: a. It is arranged vertically within the reactor main body, and at least a part of the vertical surface is formed by a gas permeable partition wall. a metal hydride powder flow path, b a hydrogen flow path arranged vertically within the reactor body while being in contact with the metal hydride powder flow path via a gas-permeable partition wall, c a metal hydride powder flow path and heat transfer A heat transfer medium flow path arranged vertically inside the reactor body while in contact with each other through a surface; d) A metal hydride powder inlet provided at the top of the reactor body; A distributor for uniformly distributing the metal hydride powder into the metal hydride flow path, and an outlet located at the bottom of the reactor main body for discharging the metal hydride powder flowing down from the metal hydride flow path. It is composed of

The apparatus of the present invention will be specifically explained below with reference to the accompanying drawings.

Figure 1 is a longitudinal cross-sectional view of a type of device in which hydrogenated metal powder flow channels with a hydrogen flow channel in the center are arranged in the reactor body, and Figure 2 is a cross-sectional view taken along line A-A in Figure 1. It is.

This type of design is basically similar to a shell-and-tube heat exchanger, with a heat transfer medium flow path on the shell side, a metal hydride powder flow path on the tube side, and an additional hydrogen flow in the center of the tube. It is easy to understand if you think of it as a structure with roads installed.

That is, a hydrogen channel 2 formed in a tubular shape with a gas-permeable partition wall 3 is disposed vertically within the reactor body 1 . The metal hydride flow path 4 is formed in an annular shape around the hydrogen flow path, and is arranged vertically within the reactor body. The outer wall of this annular hydrogenated metal powder flow path is a metallic heat transfer surface 5, and a heat transfer medium flow path 6 is provided on the outside thereof.

That is, the annular metal hydride powder flow path 4 has an inner wall, which is a part of its vertical surface, formed by the gas permeable partition wall 3, and the hydrogen flow path 2 passes through the gas permeable partition wall 3 to the metal hydride powder. In contact with the powder flow path 4, the heat transfer medium flow path 6
is in contact with the hydrogenated metal powder flow path via the heat transfer surface 5. FIG. 1 shows a case where four sets of such hydrogenated metal powder passages are installed in the reactor body.

Furthermore, a metal hydride powder inlet 7 and a distributor 8 for uniformly distributing the introduced metal hydride powder to the metal hydride flow path 4 are provided at the upper part of the reactor body.
At the bottom of the reactor main body, there is an outlet 9 for discharging the metal hydride powder flowing down from the metal hydride flow path 4.
is provided.

Symbols 65 and 66 are the heat transfer medium inlet and outlet pipes to the heat transfer medium flow path, respectively. The symbol 67 is a heat exchanger tube provided in the distributor, but this is not an essential requirement.

Reference numeral 10 denotes an outlet pipe for released hydrogen gas, which is necessary when this reactor is used as a hydrogen releasing reactor, but is unnecessary when used as a hydrogen storage reactor. In the latter case, hydrogen may be introduced from the inlet 7 together with the hydrogenated metal powder.

The gas-permeable partition wall used in the device of the present invention is made of a material that does not allow hydrogenation metal powder to pass through, but only allows hydrogen gas to pass through, has the necessary mechanical strength and heat resistance, and does not deteriorate in the reaction atmosphere. You can use anything you like. Examples include porous ceramics, foamed plastics with open pores, molded products made of metal materials, sintered bodies, and cloth-like products made from fibers of these materials, such as mesh-woven stainless steel pipes. Even if a small amount of hydrogenated metal powder leaks into the hydrogen channel through this partition, it is not practical.

In order to improve the heat transfer efficiency, the thickness of the hydrogenated metal powder flow path is preferably about 5 to 30 mm, preferably about 5 to 10 mm. The metal hydride powder introduced from the top of the reactor moves from top to bottom in this thin annular flow path by gravity, where heat is exchanged efficiently.

Any hydrogenation metal can be selected for use in the reactor of the present invention. For example, a lantern
These include nickel-based alloys and iron/titanium-based alloys.

In FIG. 3, hydrogen flow path 21, metal hydride powder flow path 41, hydrogen flow path 22, metal hydride powder flow path 42, and hydrogen flow path 23 are arranged in the order of multiple rings from the center of the reactor. FIG. 4 is a longitudinal cross-sectional view of a type of device in which a large number of heat medium flow paths 61 and 62 are arranged vertically in a metal hydride flow path, and FIG. 4 is a cross-sectional view taken along line A--A in FIG. 3.

In this case, the annular metal hydride powder flow path 41 has both the inner wall surface 31 and the outer wall surface 32, and the annular metal hydride powder flow path 42 has the inner wall surface 3
3 and the outer wall 34 are each formed by a gas-permeable partition.

A large number of heat transfer medium channels 61 and 62 arranged in the vertical direction in the metal hydride powder channel are arranged so that the distance between them is 60 mm or less, that is, the hydrogen flowing down in the metal hydride powder channel is It is preferable that any portion of the chemically modified metal powder be arranged within a distance of 30 mm from the heat transfer surface 51 or 52 of the heat transfer medium flow path.

Function First, the case where the reactor whose specific design is shown in FIGS. 1 and 2 is used for storing hydrogen gas will be explained.

Cooling water or the like is passed through the heat transfer medium channel. When the metal hydride powder and hydrogen are fed into the reactor through the inlet 7, the metal hydride powder is deposited on the distributor 8, and the metal hydride powder is deposited on the metal hydride flow path 4 (41 and 42 in Figures 3 and 4). It is evenly distributed and moves through the flow path by gravity.

Immediately after hydrogen is introduced into the reactor, it flows into the hydrogen channel 2 (21, 22, and 23 in Figures 3 and 4) and flows through the gas permeable partition wall 3 (31, 32, and 3 in Figures 3 and 4).
3 and 34), enters the hydrogenated metal powder flow path, comes into contact with the hydrogenated metal powder, and is occluded. Since the gas-permeable partition wall is provided over the entire length of the metal hydride powder flow path, hydrogen can contact the metal hydride powder with almost no diffusion resistance in the metal hydride powder layer.

On the other hand, the hydrogenated metal powder flow path is also in contact with the heat transfer medium flow path 6 (61 and 62 in Figures 3 and 4) via the heat transfer surface 5 (51 and 52 in Figures 3 and 4), so the hydrogen The amount of heat generated by occlusion is removed by cooling water. By reducing the thickness of the hydrogenated metal powder flow path as described above, heat exchange and hydrogen gas movement can be performed extremely quickly.

In this way, the hydrogenated metal powder, which has absorbed hydrogen and is cooled before reaching the lower part of the reactor, is discharged from the outlet 9 to the outside of the reactor.

Next, a case will be described in which this reactor is used to release hydrogen from hydrogenated metal powder that has occluded hydrogen.

In this case, the reactor of the present invention provided with an outlet pipe 10 for releasing hydrogen gas is used. Hot water or other high temperature medium is passed through the heat transfer medium flow path.

The hydrogenated metal powder that has absorbed hydrogen is fed through the inlet 7, and is passed through the distributor 8 to the hydrogenated metal powder flow path 4 (third,
In Fig. 4, the hydrogen is uniformly distributed to 41 and 42), and is heated as it falls through the flow path, releasing hydrogen. The released hydrogen flows through the hydrogen flow path 2 (21 and 2 in Figures 3 and 4).
2 and 23) and release hydrogen gas outlet pipe 10.
is taken out of the reactor. Again, by reducing the thickness of the metal hydride channel, heat exchange and hydrogen gas release occur very quickly.

Effects of the invention (1) Since the metal hydride powder flow channel can be made thin and the ratio of the heat transfer area to the flow rate of the metal hydride powder can be increased, the transfer of reaction heat is rapid, and as a result, hydrogen storage is reduced. Alternatively, the release reaction becomes rapid and the reactor can be made smaller.

(2) Since the hydrogen flow path is arranged on the side of the thin metal hydride layer, the diffusion resistance of hydrogen is small, and therefore hydrogen absorption and release reactions occur quickly.
This also contributes to downsizing of the reactor.

(3) By using the moving bed reactor of the present invention,
Since it is possible to configure a process in which hydrogen is continuously absorbed and released by the metal hydride, most of the problems associated with palindromic operation can be solved.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view of an example showing a specific design of the reactor of the present invention, FIG. 2 is a cross-sectional view taken along the line A-A in FIG. 1, and FIG. A vertical cross-sectional view of another example showing the design, Figure 4 is A in Figure 3.
- It is a cross-sectional view taken on the A line.

Claims (1)

[Claims] 1 a. Metal hydride powder channel arranged vertically within the reactor body and at least a portion of the vertical surface formed by a gas-permeable partition wall, b. Metal hydride powder channel and gas permeability A hydrogen flow path arranged vertically within the reactor body while in contact with each other through a partition, c. A heat transfer medium flow path that contacts the hydrogenated metal powder flow path through a heat transfer surface, and d. metal hydride powder inlet located at the top;
e. A distributor for uniformly distributing the introduced metal hydride powder into the metal hydride powder flow path, and f. Hydrogen flowing down from the metal hydride powder flow path located at the bottom of the reactor main body. A moving bed reactor for metal hydride, consisting essentially of an outlet for discharging metal hydride powder.