JPS59217601A - Method for operating hydrogen occluding and releasing apparatus - Google Patents

Abstract

PURPOSE:To minimize the number of partition walls for hydrogen occluding metal and heat medium and improve the heat exchange efficiency, by minimizing the pressure difference between the inside and outside of a part containing a hydrogen occluding metal by the pressure equalizing operation to operate the apparatus. CONSTITUTION:In the whole process containing the hydrogen occluding and hydrogen releasing operation, a piston 11 in a pressure equalizing apparatus 4 is pressed to the side of a heat medium (L) and slid to increase the pressure of the heat medium (L) when the hydrogen gas pressure is high. When the hydrogen gas pressure is low, the piston 11 is slid to the side of the hydrogen gas to reduce the pressure of the heat medium (L). Thus, the hydrogen gas pressure pressing heat exchange walls (6a) from the inside surfaces of a hydrogen occluding metal tends to become always the same as the pressure of the heat medium (L) pressing the walls (6a) from the outside surfaces, and the pressure difference between the inside and outside of the heat exchange walls (6a) becomes very small. Thus, there is no fear for deformation nor damage even constituting the walls (6a) of relatively thin walls. The heat transfer through the heat exchange walls (6a) is rapidly carried out, and the heat capacity of the individual vessel for containing the hydrogen occluding metal is small. The loss of sensible heat is remarkably reduced, and the heat exchange efficiency is very high.

Description

[Detailed Description of the Invention] The present invention relates to a method of operating a hydrogen storage/release device, and more specifically, the present invention relates to a method of operating a hydrogen storage/release device, and in particular, a partition wall between a hydrogen storage metal (a general term for metals and metal hydrides; the same shall apply hereinafter) and a heat medium is separated as much as possible. The present invention relates to a method of operating a hydrogen storage/release device that can be made thinner, thereby improving heat exchange efficiency and increasing the storage/release rate of hydrogen gas.

A hydrogen storage/release device constructed by partitioning the hydrogen storage metal storage part and the passage path of the heat medium with a heat exchange wall is shown in Figures 1 and 2 (■-■ in Figure 1).
There is an external heat medium flow path type shown in FIG. 3 and FIG. 4 (a cross-sectional view taken along the line IV--IV in FIG. 3). In Figures 1 to 4, 1 is a shell, 6 is a hydrogen storage metal storage container, 6a is a heat exchange wall, 7 is a hydrogen gas pipe, 7i is a header for hydrogen gas distribution and collection, and 13 is a filter. It has a structure in which hydrogen gas is supplied into the container 6 through the filter 13, and is also discharged. In Figs. 1 and 2, hydrogen gas is stored or released while exchanging heat by flowing a heat medium around the container 6 containing the hydrogen storage metal M, and in Figs. 3 and 4, hydrogen gas is stored or released while exchanging heat. A heat medium passage is formed in the storage container 6, and by flowing the heat medium through the passage as shown by arrows A and B, hydrogen gas is stored or released while exchanging heat. By the way, in this type of hydrogen storage/release device, the heat exchange wall 6a between the hydrogen storage metal M and the heat medium tank is
had to be quite thick. That is, the equilibrium dissociation pressure in the following reaction formula % formula % varies depending on the type of hydrogen storage metal and the operating temperature, but for example, when the hydrogen storage metal is LaNi
, and the operating temperature is 80°C, it is approximately 21kg/c♂
It is known that it extends to On the other hand, the pressure on the heat medium side is generally low, although it depends on the discharge power of the heat medium supply pump.
Since it is usually less than 4 kg/crf, the heat exchange wall 6
The pressure difference across a is 17 kg/c♂ or more. Therefore, it was necessary to design the heat exchange wall 6a to withstand such a large pressure difference. As a result, the thickness of the heat exchange wall 6a had to be increased, and the following drawbacks had to be complied with.

(1) The reaction rates of hydrogen gas storage and desorption in hydrogen storage metals are generally controlled by the heat transfer rate, but because the heat exchange wall is thick, the heat transfer rate decreases and the hydrogen gas The storage and release rate decreases.

(2) When the cycle of hydrogen absorption and release is repeated, the temperature of the storage container also rises and falls repeatedly, but if the thickness of the heat exchange wall is large, the heat capacity of the storage container 9 becomes large. Therefore, sensible heat loss increases and the thermal efficiency of the hydrogen storage/release device decreases.

(3) Hydrogen storage metal is usually filled in the form of fine powder, but by absorbing hydrogen gas, the metal lattice expands and the metal powder becomes even more finely divided, reducing its bulk density. The volume of the entire body expands.

On the other hand, pressure vessels are made of flexible materials, so it is impossible to process them to give them flexibility, and the wall thickness of the vessel must be increased for pressure-resistant design. has almost no elastic deformation ability, and the expansion of the metal powder layer appears as an increased compaction force between the fine powders and a pressing force on the heat exchange wall surface.

These pressures are surprisingly large, for example, LaN1a
In an experiment, it reached as much as 450 kg/cd.

If the pressing force applied to the heat exchange wall surface becomes excessive, the container will undergo plastic deformation, leading to destruction in extreme cases.

(4) When the compressive force applied to the fine powder exceeds a certain value, the metal powder begins to sinter and solidify, increasing the resistance to passage of hydrogen gas. As a result, a pressure distribution is formed inside the storage container in the direction of flow of hydrogen gas. By the way, the hydrogen absorption/desorption reaction rate is affected by the ease of heat absorption and heat generation, and of course is also affected by the hydrogen gas pressure, more precisely, the differential pressure between the hydrogen gas pressure and the equilibrium dissociation pressure.

Therefore, if there is a distribution of hydrogen gas pressure within the storage container, a uniform reaction is difficult to occur and the operating efficiency of the hydrogen storage/release device is reduced. In order to prevent deformation or destruction of the storage container or sintering and solidification of the metal powder layer, there are measures to reduce the filling rate of the hydrogen storage metal in the storage container or to reduce the hydrogen pressure itself. Naturally, these countermeasures come at the expense of the hydrogen gas storage and release ability, which results in the loss of practical value as a hydrogen storage and release device.

As described above, the conventional apparatus has various drawbacks due to the large thickness of the heat exchange wall, and it has been desired to reduce the thickness of the heat exchange wall as much as possible.

The present invention has been made with attention to these circumstances, and it is possible to absorb and release hydrogen without causing wear and tear on the device, and to obtain excellent thermal efficiency and hydrogen storage and release rates. The purpose of this paper is to provide a method for operating a hydrogen storage/release device of various types.

Therefore, the operating method of the present invention is a method of operating a hydrogen storage/release device in which a heat medium is passed through in contact with a hydrogen storage metal storage part, and the pressure difference between the inside and outside of the storage part is equalized. The key point is to operate with as little energy as possible.

The configuration and effects of the present invention will be explained below with reference to the drawings.

FIG. 5 is a flow diagram showing an example of a hydrogen storage/desorption device for carrying out the method of the present invention, in which 1 is a shell, 2 is a heat medium supply pump, 4 is a pressure equalization device, and 9 is a heat medium heating/cooling device. The device (hereinafter referred to as heating/cooling device) is shown below. The illustrated hydrogen storage/release device 5 is of the above-mentioned external heat medium flow path type, and a plurality of containers 6 storing hydrogen storage metals M are disposed in the shell 1, and one of the storage containers 6 is A hydrogen gas pipe 7 is connected to the end side via a header 7a. Furthermore, hydrogen gas pipe 7
An opening/closing pulp 3 is interposed in the opening/closing pulp 3.

Further, a heat medium introduction pipe 8 and a heat medium discharge pipe 8a are attached to the shell 1, and the shell 1, the heating/cooling device 9, and the heat medium supply pump 2 are connected by the heat medium introduction pipe 8, the heat medium discharge pipe 8a, etc. This forms a heat medium circulation system.

On the other hand, the pressure equalizing device 4 in the illustrated example is divided into two chambers by a piston 11 that can slide inside the device, and a branch pipe 8b from the heat medium introduction pipe 8 is in one chamber, and a hydrogen gas pipe is in one chamber. Branch pipes 7b from 7 are connected to the other chamber, respectively.

When performing a hydrogen gas storage operation using the device shown in this figure, hydrogen gas is pressurized into the storage container 6 from the hydrogen gas pipe 7 while the heat medium, which has been cooled by the heating/cooling device 9, is allowed to flow into the shell 1. . On the other hand, when performing a hydrogen gas release operation, hydrogen gas is dissociated from the hydrogen storage metal M in the storage container 6 while flowing a heat medium heated by the heating/cooling device 9 into the shell 1. Collect it in the gas pipe 7 and take it out.

By the way, as mentioned above, since the hydrogen gas pressure and the heat medium pressure are transmitted to the pressure equalizing device 4 via the branch pipes 7b and 8b, all conditions including during each step of the hydrogen storage operation and hydrogen release operation described above In this case, when the hydrogen gas pressure is high, the piston 11 in the pressure equalizing device 4 is pushed and slid toward the heat medium side, increasing the pressure of the heat medium. When the hydrogen gas pressure is lower, the piston 11 slides toward the hydrogen gas side to lower the pressure of the heat medium. In other words, the pressure of the hydrogen gas that presses the heat exchange wall 6a from the inside and the pressure of the heat medium that presses the heat exchange wall from the outside always try to be equal due to the function of the pressure equalization device, so there is a pressure difference between the inside and outside of the heat exchange wall 6a. is extremely small, so there is no need to increase the thickness of the heat exchange wall 6a as in the conventional case. In other words, there is no fear of deformation or breakage even if the structure is made relatively thin. As a result, heat transfer through the heat exchange wall 6a is rapid, the heat capacity of the storage container 6 itself is small, and sensible heat loss is greatly reduced, resulting in extremely high heat exchange efficiency.

Although the basic configuration of the present invention is the above-mentioned power supply, the following embodiments can also be used as specific means and devices for performing the pressure equalization operation.

FIG. 6 shows an example in which a bellows 18 is provided inside the cylinder S. The inside of the bellows 18 is communicated with a hydrogen gas branch pipe 7b, and the space between the cylinder S and the bellows 18 is communicated with a heat medium branch pipe 8b. There is. Note that a diaphragm can also be used in place of the bellows 18.

Further, FIG. 7 shows an example in which the pressure equalizing device is composed of two cylinder chambers S1 and S, and the pistons lla and llb disposed in both cylinder chambers S1 and S2 are connected to each other by a rod 22. One cylinder chamber S1 is communicated with a hydrogen gas branch pipe 7b, and the other cylinder chamber S2 is communicated with a heat medium branch pipe 8b. In addition, if the heat medium is a liquid, the vapor pressure at the above operating temperature is low, and there is no problem even if a small amount of vapor mixes into the hydrogen gas, the piston 11 is omitted in the pressure equalizing device shown in FIG. It may be something that has been done.

In the above embodiments, a pressure equalization device is used, but the point is that the pressure difference between the internal pressure and the external pressure should be reduced as much as possible by sandwiching the heat exchange wall of the metal storage container for hydrogen storage. Therefore, as a means other than the above, for example, in Fig. 5, the installation of the pressure equalization device is omitted, and a pressure detection device is attached to the hydrogen gas pipe 7 and the heating medium introduction pipe 8, respectively, so that the pressure of the hydrogen gas and the pressure of the heating medium are equal. For example, a method may be adopted in which the pressure for pushing the heat medium into the storage shell is adjusted so that the heat medium is pushed into the storage shell.

As described above, by making the hydrogen gas pressure and the pressure of the heat medium substantially equal, it is no longer necessary to design the heat exchange wall to withstand pressure as in the past, which eliminates many constraints and improves the efficiency of the equipment. It has become possible to improve thermal efficiency and equipment efficiency.

Since the method of the present invention has the above-described configuration, it is possible to form a thin heat exchange wall, and it is possible to design and manufacture a device with a structure that has not been previously used in this field. is possible. As a typical example, devices as shown in FIGS. 8 to 19 are exemplified.

FIGS. 8 and 9 (cross-sectional view taken along line IX-IX in FIG. 8) show a metal storage container 6 for hydrogen storage which includes a filter tube 13 with heat transfer fins, and the container 6 has flexibility. The side plate 10 is joined to a corrugated plate 12 made of a thin metal plate, and a filling port 14 for hydrogen storage metal M is formed at one end.
, and a hydrogen gas pipe 7 communicating with the filter pipe 13 is attached to the other end. The filling port 14 is made of metal M for hydrogen storage.
After storing M in the container 12, it is sealed. The reason why the container is formed in the shape of a corrugated plate is that when the hydrogen storage metal M stores hydrogen and expands in volume, the troughs of the corrugated plate 12 swell to absorb the expansion. On the other hand, the heat transfer fins 15 are
A horizontal plate 16 whose end edge is fixed to the filter tube 13, and a vertical plate 17 attached in a direction perpendicular to the horizontal plate 16 at a position corresponding to the bulge of the container 12, for hydrogen storage. It is stored in the container 6 so as to be buried in the metal M.

Such heat transfer fins 15 quickly transfer the heat that has entered through the heat exchange wall to the inside of the storage container 6, i.
By exhibiting the function of homogenizing the heat distribution, the heat transfer effect is further improved, and hydrogen gas can be quickly absorbed and absorbed.
Release cycles are possible.

FIG. 10 shows a hydrogen storage system in which the storage container 6 shown in FIG. 8.9 is combined with a plurality of rod-shaped spacers 18.
This is a partially cutaway side view showing the emitter 5a, in which the heat transfer medium enters the shell 1 from the inlet 8C and the spacer 18 and the container 1.
20, and is further discharged from the discharge port 8d. In addition, when combining the hydrogen storage/release body 5a, it is also possible to fix it with a frame. The combined hydrogen storage/release body 5a is fixed to the inner wall of the shell 1 using a fixture 23 or the like.

FIG. 11 is a partially cutaway perspective view showing another application example, in which a corrugated metal plate 17 acting as a heat transfer member is disposed inside a box-shaped storage container 6b made of a thin metal plate, and a corrugated A hydrogen gas collection passage 19 is formed at one longitudinal end of the metal plate 17 (left front opening in the drawing) via a filter 13, and the hydrogen gas collection passage 19 communicates with the hydrogen gas pipe 7 via a ladder pipe. are doing. The other end of the corrugated metal plate 17 in the longitudinal direction (the right side opening in the figure) communicates with the hydrogen storage metal filling port 14, and the filling port 14 is closed after filling with metal. When a plurality of such storage containers 6 are combined, corrugated spacers 20 having the same shape as the corrugated metal plates 17 are alternately combined so as to be orthogonal to each other to form the hydrogen storage/release body 5.
a is formed.

The heat transfer medium flows in the direction of arrow C along the waves of the spacer 20. Such a hydrogen storage/release body 5a is
As shown in FIG. 2, by incorporating it into the shell 1, an external heat medium flow path type hydrogen storage/release device 5 can be manufactured. Further, FIG. 13 is a schematic side view showing the internal heat medium channel type hydrogen storage/release device 5, which is similar to the hydrogen storage/release device 5 shown in FIG.
A hydrogen storage/discharge body 5b corresponding to the hydrogen gas collection passage 19 omitted in a is used (however, the filter 13a and the spacer 20 are attached as they are), and a small amount of spacer is used at the end opening on the longitudinal side of the spacer 20. A cover plate 21 is attached to seal the space, and a heat medium introduction mse and a heat medium discharge pipe 8f that penetrate the cover plate 21 and communicate with the containment space are attached to the cover plate 21 and housed in the shell 1. It is. Although the hydrogen gas pipe 7 is attached to the shell 1, it is not necessary to attach a ladder pipe to each container 6b.

14 and 15 (cross-sectional view taken along the line X and door W in FIG. 14) show a hydrogen storage/release body formed by combining a plurality of cylindrical storage containers 6 with different diameters in a layered manner with spacers 20 interposed therebetween. 5C is shown, the heating medium is connected from the introduction pipe 8a to the shell 1.
It flows through the inside to the outlet pipe 8b.

Figures 16 and 17 (A1-XXV in Figure 16)
The cross-sectional view (viewed from the arrow) shows an application example in which a flat storage container is curved into a spiral shape, and a filter tube 13 is installed inside along the terminal edge of the outermost layer.

18 and 19 (cross-sectional view taken along the line ■-XIX in FIG. 18) show an example of a spiral storage container similar to the above, but the filter tube 13 is also spirally curved with one spiral end. The edges are well decorated.

The application examples shown in FIGS. 14 to 19 above are all structures that can be adopted because the heat exchange walls are thin, and the storage containers can be arranged densely within the small volume shell, so the unit volume The heat transfer area can be increased and excellent heat transfer efficiency can be obtained.

The present invention is configured as described above.9. We were able to obtain the effects summarized below.

(1) Since the pressure of the hydrogen gas inside the storage container and the pressure of the heat medium are almost equal, the wall thickness of the storage container can be made thinner, and the efficiency of heat transfer through the heat exchange wall is extremely improved. . For example, when using LaNi5 as a hydrogen storage alloy, if it is filled into a stainless steel pipe with an outer diameter of 21.7 mm and heat exchanged with a heat medium at 110°C, the nlG pressure of hydrogen will be 48 kg/c♂G. Therefore, in the conventional method, the wall thickness of the stainless steel pipe needs to be 3 nm or more, but in the method of the present invention, the pressure difference between the heat medium and hydrogen is reduced to 4 kg/3 nm or more.
Since cIT can be kept within 12G, the wall thickness of the pipe only needs to be 1 mm or less. The heat transfer rate improved by about 5 inches.

1 (2) The heat exchange wall thickness of the storage container can be made thinner, so the heat capacity of the storage container is small, and the sensible heat loss associated with the hydrogen absorption/release cycle is small, improving thermal efficiency.

In the above example, 40% of the alloy was placed inside the stainless steel tube.
When filled with a capacity tube, the heat capacity per 1 kg of alloy was 0.37 oil/g in the conventional method, whereas in the present invention, the heat capacity is 0.09 oil/g because the wall thickness of the tube can be made thinner.
m/g], resulting in a 34% reduction in sensible heat loss.

(3) Since the heat exchange wall can be made thin, the processability of the container is improved, and it is possible to freely form a flexible type or a type with a complicated shape.

[Brief explanation of drawings]

FIG. 1 is an explanatory side view showing an external heat medium flow path type storage container;
Fig. 2 is a cross-sectional view taken along the line ■-■ in Fig. 1, Fig. 3 is a side view showing an internal heat medium flow path type storage container, and Fig. 4 is a sectional view taken along the line ■-■ in Fig. 1.
5 is a flow diagram of a hydrogen storage/release device to which the method of the present invention is applied; FIGS. 6 and 7 are illustrations of an embodiment of a pressure equalization device; 8 to 19 The figure is an explanatory diagram of a storage container to which the method of the present invention is applied. 1...Shell 4...Pressure equalization device...Hydrogen storage/release device 6...Storage container 7...Hydrogen gas pipe 8...
Heat medium inlet pipe 8a... Discharge pipe 13... Filter 20... Spacer applicant Toyobo Co., Ltd. Kubota Iron Works Co., Ltd.

Claims (1)

[Claims] A method of operating a hydrogen storage/release device in which a heating medium is allowed to pass through in contact with a hydrogen storage metal storage part, the method comprising reducing the pressure difference between the inside and outside of the storage part as much as possible by pressure equalization operation. A method of operating a hydrogen storage/release device characterized by operating the hydrogen storage/release device.