JPH0692605A - Hydrogen recovery and purification method and apparatus - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a method and apparatus for hydrogen recovery and purification. [Structure] In a state where a hydrogen storage alloy A and a poisoning gas adsorbent B disposed on the hydrogen storage alloy A are housed in a container 1 and the hydrogen storage alloy A is cooled by a heating / cooling device 2, A raw material gas containing hydrogen is supplied through the raw material gas supply line 7, the raw material gas is passed through the poisonous gas adsorbent B and then led to the hydrogen storage alloy A, and the poisonous gas is adsorbed on the poisonous gas adsorbent B. While allowing the hydrogen gas to occlude in the hydrogen occluding alloy A, the toxic gas released from the toxic gas adsorbent B is caused to flow out from the purge gas line 11 to the outside, and then the heating / cooling device 2 occludes the hydrogen gas. With the alloy A heated, the purified hydrogen gas released from the hydrogen storage alloy A is released from the purified hydrogen gas release line 6. [Effect] Poisoning of the hydrogen storage alloy can be suppressed for a long period of time, the life of the hydrogen storage alloy can be extended, and the hydrogen recovery and purification device can be used for a long period of time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for recovering and refining hydrogen.

[0002]

2. Description of the Related Art As a conventional hydrogen recovery and purification apparatus, there is one disclosed in, for example, Japanese Patent Application Laid-Open No. 3-271101. In this hydrogen recovery and purification device, a hydrogen utilization device and a hydrogen recovery container which contains a hydrogen storage alloy and is equipped with a heating device and a cooling device are connected by a source gas supply line having a first valve with a pressure adjusting function. With the second
A purified hydrogen gas release line having a valve and a purge gas line, which is attached to a third valve and releases an impure gas at the start of hydrogen release from the hydrogen recovery container, are each connected to the hydrogen recovery container.

However, in this conventional hydrogen recovery and refining apparatus, when the hydrogen gas from the hydrogen utilizing apparatus is stored in the hydrogen storage alloy in the hydrogen recovery container cooled by the cooling apparatus, There is a technical problem that the poisoning gas mixed for some reason is occluded together with the hydrogen gas, and the poisoning gas is accumulated in the hydrogen occluding alloy, so that the ability of hydrogen recovery and purification gradually decreases.
Such a poisonous gas is a gas that reduces the hydrogen storage capacity of the hydrogen storage alloy, and oxygen, carbon monoxide, carbon dioxide, etc. are known.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional technical problems, and the hydrogen recovery and refining method is configured such that the hydrogen storage alloy and the hydrogen storage alloy are arranged on the hydrogen storage alloy. A state in which a poisonous gas adsorbent composed of an adsorbent or a catalyst is housed in a container and at least the hydrogen storage alloy or at least the hydrogen storage alloy in the poisonous gas adsorbent is cooled by a heating / cooling device. The raw material gas containing hydrogen is supplied through a raw material gas supply line connected to the upper part of the container, and the raw material gas is led to the hydrogen storage alloy after passing through the poisonous gas adsorbent, and the hydrogen storage alloy While adsorbing a poisoning gas that reduces the hydrogen storage capacity to the poisoning gas adsorbent, the hydrogen gas that has passed through the poisoning gas adsorbent is stored in the hydrogen storage alloy, and then released from the hydrogen storage alloy. With purified hydrogen gas The toxic gas released from the toxic gas adsorbent is discharged to the outside from the purge gas line connected to the upper part of the container, and then the hydrogen occluding alloy is heated by the heating / cooling device to heat the hydrogen occluding alloy. It is characterized in that the purified hydrogen gas released from the alloy is released from a purified hydrogen gas release line connected to the upper part of the container. Further, the configuration of the hydrogen recovery and refining device is such that a container, a hydrogen storage alloy that is housed in the container and stores hydrogen as a hydride, and a hydrogen storage alloy that is disposed on the hydrogen storage alloy and that has a hydrogen storage capacity of the hydrogen storage alloy. A poisonous gas adsorbent composed of an adsorbent or a catalyst for removing poisonous gas to be reduced, a source gas supply line connected to the upper part of the container for supplying a source gas containing hydrogen, a purified hydrogen gas release line, and A purge gas line for outflowing a poisonous gas released from the poisonous gas adsorbent, and a heating / cooling device for heating or cooling the hydrogen storage alloy or at least the hydrogen storage alloy in the poisonous gas adsorbent. A first valve interposed in the source gas supply line, a second valve interposed in the purified hydrogen gas release line, and a third valve interposed in the purge gas line. To.

[0005]

According to such a hydrogen recovery / purification method or hydrogen recovery / refining apparatus, the hydrogen storage alloy in the container is cooled by the heating / cooling device, and the first and second valves are closed with the second and third valves closed. The valve is opened, and the raw material hydrogen gas from the hydrogen utilizing device is introduced from the raw material gas supply line and supplied to the container. At this time, depending on the type of the poisonous gas adsorbent, the poisonous gas adsorbent can also be cooled by the heating / cooling device so that the adsorbing ability is exhibited.

As a result, the pressure inside the container rises, and hydrogen gas starts to be occluded in the hydrogen occluding alloy. Along with the storage of hydrogen gas by the hydrogen storage alloy, the raw material hydrogen gas previously passes through the poisonous gas adsorbent placed on the hydrogen storage alloy. At this time, poisonous gases such as oxygen, carbon monoxide, and carbon dioxide are adsorbed or absorbed by the poisonous gas adsorbent or are removed by being allowed to proceed with the reaction to the non-poisonous gas by the catalyst. The raw material hydrogen gas is processed while suppressing the reduction of the hydrogen storage capacity of the hydrogen storage alloy due to the adsorption of the toxic gas. When the hydrogen recovery to the hydrogen storage alloy is completed, the first valve is closed.

In this way, if the high-purity hydrogen gas is recovered and refined in the hydrogen storage alloy from the raw material hydrogen gas discharged from the hydrogen utilization device, the first valve remains closed.
Close the valve and instantly open the third valve. As a result, the inside of the container is opened to the atmosphere through the purge gas line to cause a pressure drop, so that the purified hydrogen gas is slightly released from the hydrogen storage alloy and the poisonous gas is released from the poisonous gas adsorbent. The poisonous gas released from the poisonous gas adsorbent is pushed out of the purge gas line to the atmosphere by the hydrogen gas. At this time, if necessary, the poisoning gas adsorbent can be heated to a predetermined temperature by a heating / cooling device to promote the release of the poisoning gas.

When the poisonous gas floating in the container flows out from the purge gas line into the atmosphere, the third valve is closed and the second valve is opened, and the hydrogen storage alloy is heated to a predetermined temperature by the heating / cooling device. . As a result, a large amount of purified hydrogen gas is released from the hydrogen storage alloy in which hydrogen is stored, and the released high-purity hydrogen gas flows out from the purified hydrogen gas release line. Thus, high-purity hydrogen gas is extracted from the raw material hydrogen gas.

Even if the hydrogen gas is repeatedly collected and purified in this manner, the poisonous gas with respect to the hydrogen storage alloy, which is mixed into the hydrogen utilization device for some reason, is adsorbed or absorbed by the poisonous gas adsorbent. Since it is removed or is reacted with a catalyst to be removed, it is possible to satisfactorily suppress the problem that the hydrogen storage alloy is deposited and accumulated over a long period of time to gradually reduce the storage capacity.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows one embodiment of the hydrogen recovery and purification device. In the figure, reference numeral 1 indicates a hermetically sealed container, and the upper lid 1a is detachable. A hydrogen storage alloy A (metal hydride) is accommodated in the bottom of the container 1, and a poisonous gas adsorbent B composed of an adsorbent or a catalyst is arranged on the hydrogen storage alloy A, and a poisonous gas adsorbent B is placed. A space O is formed above. The adsorbent of the poisonous gas adsorbent B is, for example, activated carbon, molecular sieve, zeolite, alumina, etc., and the catalyst is, for example, a paradium system that promotes the reaction of the poisonous gas into the non-toxic gas. The poisonous gas adsorbent B is composed of these simple substances or a mixture.

The hydrogen storage alloy A in the container 1 is
The heating / cooling device 2 is attached, and the second heating / cooling device 3 is attached to the poisonous gas adsorbent B. In the first and second heating / cooling devices 2 and 3, the heat medium from the heat medium supply device 20 is the pipe 18b or the pipe 19b provided with the opening / closing valve 17.
Is introduced into the heat medium flow path 14 or 15 disposed in the container 1 to heat or cool the hydrogen storage alloy A or the poisonous gas adsorbent B in the container 1 to flow out, and the open / close valve 16 is provided. Heat medium supply device 2 through pipe 18a or pipe 19a
It is set back to 0. By adjusting the temperature of the heat carrier,
The hydrogen storage alloy A or the poisonous gas adsorbent B in the container 1 can be heated or cooled.

As the cooling device, the heat medium from the heat medium supplying device 20, for example, cold water is supplied to the heat medium passages 14 and 15 to cool the hydrogen storage alloy A to a temperature at which hydrogen gas is satisfactorily stored, or It functions by cooling the poisonous gas adsorbent B to a temperature at which the poisonous gas is satisfactorily adsorbed or absorbed or the reaction is advanced by a catalyst to be removed. Also,
As the heating device, a heat medium such as hot water or steam from the heat medium supply device 20 is introduced into the heat medium flow passages 14 and 15,
It functions by heating the hydrogen storage alloy A to a temperature at which hydrogen is released favorably or by heating the poisonous gas adsorbent B at a temperature at which poisonous gas is favorably released.

Further, a connection passage 13 in which an opening / closing valve 12 is interposed is provided between the pipes 18a and 19b so as to connect the heat medium passages 14 and 15. Then,
By closing both open / close valves 16 and 17 and opening the open / close valve 12, both heat medium flow paths 14 and 15 are directly connected, so that heat medium such as cold water or hot water supplied from one heat medium flow path 14 is supplied. Can be passed to the other heat medium flow path 15. The heating device can also be configured with an electric heater separate from the heat medium flow paths 14 and 15.

Here, the poisonous gas adsorbent B, such as activated carbon, can be degassed by raising the temperature,
If the molecular sieve is cooled in order to process the heat of adsorption, the adsorptivity is improved, and the molecular sieve can be heated to 300 ° C. or higher to evaporate water vapor and recover the adsorption performance. Zeolite can adsorb carbon dioxide, oxygen, etc. by cooling, and can adsorb steam, isooctane, neopentane, etc. even at room temperature, and can be regenerated by heating or pressure regeneration at low pressure.

Further, the hydrogen storage alloy A reacts with hydrogen gas to reversibly store or release hydrogen gas, and this reaction causes hydrogen equilibrium pressure-temperature characteristics (P-
Based on the temperature characteristics at the hydrogen equilibrium pressure, hydrogen gas is absorbed when cooled to a low temperature and released when heated to a high temperature. Then, a normal heating device in the hydrogen recovery and refining device is intended to release the hydrogen gas by heating the hydrogen storage alloy A to a maximum of about 150 to 170 ° C. Reference numeral 22 is a pressure sensor for detecting the pressure in the container 1.

Then, the container 1 is connected to one end of a source gas supply line 7 with a first valve 4 having a pressure adjusting function in the container 1 interposed. The other end of the source gas supply line 7 is connected to a hydrogen-utilizing device 10 such as a hydrogen-cooled generator or semiconductor manufacturing facility. However, the hydrogen utilization device 10 here may be any device that releases hydrogen gas used for recovery and purification, and also includes a hydrogen generation device such as an ammonia decomposition device.

Further, one end of a purified hydrogen gas discharge line 6 is connected to the container 1, and a second valve 5 having an opening / closing function is interposed in the purified hydrogen gas discharge line 6. The hydrogen gas released from the hydrogen utilization device 10 is introduced from the source gas supply line 7, recovered and purified by the hydrogen storage alloy A in the container 1, and flows out from the purified hydrogen gas release line 6. A hydrogen utilization device 10 is usually connected to the other end of the purified hydrogen gas discharge line 6 so that the hydrogen gas recovered and purified in the container 1 is circulated and used.

Further, to the container 1, one end of a purge gas line 11 for discharging the poisonous gas released from the poisonous gas adsorbent B to the outside is connected via a third valve 8 having a pressure control function. To do. Specifically, one end of the purge gas line 11 is connected to the purified hydrogen gas release line 6 upstream of the second valve 5. The source gas supply line 7, the purified hydrogen gas release line 6 and the purge gas line 11 are respectively located above the poisonous gas adsorbent B and are connected to the upper end of the container 1 so as to open into the space O. is there.

Next, the operation of the above embodiment will be described. A case where the hydrogen gas released from the hydrogen utilization device 10 has a relatively high purity will be described. As shown by (1) in FIG. 2, while the hydrogen storage alloy A in the container 1 is cooled by the first heating / cooling device 2, the second and third valves 5 and 8 are closed (2 ), The first valve 4 is opened, the raw material hydrogen gas from the hydrogen utilization device 10 is introduced from the raw material gas supply line 7, and is supplied to the container 1. The first valve 4 is set to a pressure that does not hinder the inflow of hydrogen gas into the container 1 due to fluctuations in the gas pressure inside the hydrogen utilization device 10. Further, as shown in (3), the poisoning gas adsorbent B is cooled by the second heating / cooling device 3 so that the adsorption ability is exhibited according to the type of the poisoning gas adsorbent B. When the adsorption capacity of the poisonous gas adsorbent B is exhibited at room temperature, it is not necessary to operate the second heating / cooling device 3.

As a result, the source gas is supplied to the space O, the pressure inside the container 1 rises as shown by (4) in FIG. 2, and the hydrogen gas starts to be occluded in the hydrogen occluding alloy A. As the hydrogen storage alloy A stores hydrogen gas, the raw material hydrogen gas supplied to the space O passes through the poisonous gas adsorbent B disposed on the hydrogen storage alloy A almost uniformly. At that time, a poisonous gas such as oxygen, carbon monoxide, carbon dioxide or the like is adsorbed or absorbed by the poisonous gas adsorbent B to be removed or a reaction to a non-toxic gas can be promoted by a catalyst. The raw material hydrogen gas is treated while suppressing the reduction of the hydrogen storage capacity of the hydrogen storage alloy A due to the adsorption of the poisonous gas. When the hydrogen recovery to the hydrogen storage alloy A is completed, the pressure in the container 1 temporarily rises due to the filling of the hydrogen gas. Therefore, this pressure rise is detected by the pressure sensor 22, and the first valve 4 Close.

Here, the hydrogen storage alloy A containing poisonous gas
The decrease in hydrogen storage capacity of No. 1 will be described with reference to FIGS. FIG. 3 shows the relationship between the hydrogen storage capacity of the hydrogen storage alloy A and the hydrogen storage time, and shows the reduction of the hydrogen storage capacity of the hydrogen storage alloy A due to air adhesion. In the figure, the a curve shows the characteristics of the new hydrogen storage alloy A after activation treatment,
The b curve shows the characteristic after 2 hours of poisoning, the c curve shows the characteristic after 6 hours of poisoning, and the d curve shows the characteristic after 12 hours of poisoning. These poisoning states were given by exposing the hydrogen storage alloy A to the atmosphere for a predetermined time. It can be seen from the figure that the hydrogen storage capacity decreases as the poisoning time increases.

FIG. 4 shows the relationship between the hydrogen storage capacity of the hydrogen storage alloy A and the hydrogen storage time, and shows the reduction of the hydrogen storage capacity of the hydrogen storage alloy A due to the adhesion of carbon dioxide. In the figure, a curve shows characteristics after activating the new hydrogen storage alloy A, e curve shows characteristics after poisoning with carbon dioxide gas of 0.1 MPa, and f curve shows carbon dioxide of 0.2 MPa. The characteristics after poisoning with gas, and the g curve shows the characteristics after poisoning with carbon dioxide gas of 0.4 MPa. These poisonings were given by contacting the hydrogen storage alloy A with carbon dioxide gas for 20 minutes. From Figure 4, the poisoning time is 20
It can be seen that the hydrogen storage capacity significantly decreases as the poisoning pressure increases, even if the same in minutes.

As described above, high-purity hydrogen gas is recovered and refined in the hydrogen storage alloy A from the raw material hydrogen gas discharged from the hydrogen utilization device 10 while suppressing the reduction of the hydrogen storage capacity of the hydrogen storage alloy A. If so, the second valve 5 remains closed, the first valve 4 is closed, and the third valve 8 is opened for a short time as shown by (5) in FIG. As a result, the inside of the container 1 is opened to the atmosphere through the purge gas line 11 as shown in (6) and a pressure drop occurs, so that the hydrogen storage alloy A
A slight amount of purified hydrogen gas is released from the fuel cell and the poisonous gas is released from the poisonous gas adsorbent B. The released hydrogen gas causes the poisoned gas released from the poisoned gas adsorbent B to be pushed out to the atmosphere through the purge gas line 11. At this time, as shown in (7), the poisoning gas adsorbent B can be heated to a predetermined temperature by the second heating / cooling device 3 as required, and the release of the poisoning gas can be promoted.

When the poisonous gas flows into the atmosphere through the purge gas line 11, the third valve 8 is closed, the second valve 5 is opened as shown in (8), and the third valve 8 is opened as shown in (9). 1. The hydrogen storage alloy A is heated to a predetermined temperature by the heating / cooling device 2. As a result, a large amount of purified hydrogen gas is released from the hydrogen storage alloy A in which hydrogen is stored, and the released high-purity hydrogen gas flows out from the purified hydrogen gas release line 6. Thus, high-purity hydrogen gas is extracted from the raw material hydrogen gas. When the purified hydrogen gas is completely released from the hydrogen storage alloy A, the pressure inside the container 1 decreases as indicated by the broken line (10).

By repeating such an operation, even if the hydrogen gas is recovered and refined a plurality of times, the hydrogen storage alloy A mixed in the hydrogen utilizing device 10 for some reason.
Since the poisonous gas is absorbed or absorbed by the poisonous gas adsorbent B or is reacted with a catalyst to be removed, the poisonous gas is deposited and accumulated on the hydrogen storage alloy A for a long period of time to gradually reduce the storage capacity. This problem is suppressed well. The poisonous gas adsorbent B is appropriately replaced when the ability to adsorb the poisonous gas decreases. At that time, the upper lid 1a of the container 1 is removed.

[0026]

As can be understood from the above description,
According to the hydrogen recovery and purification apparatus of the present invention, the raw material gas after removing the poisoning gas is converted into the hydrogen storage alloy by the simple structure of disposing the hydrogen storage alloy and the poisoning gas adsorbent in the container. It will be occluded. As a result, poisoning of the hydrogen storage alloy is suppressed for a long time and the life is extended,
As a result, the hydrogen recovery and purification device can be used for a long period of time.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a hydrogen recovery and purification apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing an operating state of the hydrogen recovery / refining device.

FIG. 3 is a diagram showing a hydrogen storage capacity-hydrogen storage time characteristic of the same.

FIG. 4 is a diagram showing a hydrogen storage capacity-hydrogen storage time characteristic of the same.

[Explanation of symbols]

1: Container, 1a: Top lid, 2: First heating / cooling device, 3:
Second heating / cooling device, 4: First valve, 5: Second valve, 6: Purified hydrogen gas release line, 7: Raw material gas supply line, 8: Third valve, 10: Hydrogen utilization device, 11: Purge gas line , 14 and 15: heat medium flow path, 20: heat medium supply device, A: hydrogen storage alloy, B: poisonous gas adsorbent, O: space.

Claims (2)

[Claims] 1. A toxic gas adsorbent comprising a hydrogen occluding alloy and an adsorbent or a catalyst disposed on the hydrogen occluding alloy is housed in a container, and the hydrogen occluding alloy or the toxic gas adsorbent is stored in the container. In a state in which at least the hydrogen storage alloy is cooled by a heating / cooling device, a raw material gas containing hydrogen is supplied by a raw material gas supply line connected to the upper part of the container,
The source gas is introduced into the hydrogen storage alloy after passing through the poisonous gas adsorbent, and the poisonous gas is adsorbed on the poisonous gas adsorbent while adsorbing the poisonous gas that reduces the hydrogen storage capacity of the hydrogen storage alloy. The hydrogen gas that has passed through the material is stored in the hydrogen storage alloy, and then the poisoned gas released from the poisoned gas adsorbent by the purified hydrogen gas released from the hydrogen storage alloy is connected to the upper part of the container. A purified hydrogen gas release line that connects the purified hydrogen gas released from the hydrogen storage alloy to the upper part of the container while flowing out from the purge gas line to the outside and subsequently heating at least the hydrogen storage alloy by the heating / cooling device. A hydrogen recovery and purification method, characterized in that 2. A container, a hydrogen storage alloy that is stored in the container and stores hydrogen as a hydride, and a poisonous gas that is disposed on the hydrogen storage alloy and reduces the hydrogen storage capacity of the hydrogen storage alloy. A poisonous gas adsorbent comprising an adsorbent or a catalyst for removing hydrogen, a raw material gas supply line connected to the upper part of the container for supplying a raw material gas containing hydrogen, a purified hydrogen gas release line, and a poisonous gas adsorbent A purge gas line for outflowing the poisonous gas released from the outside, and a heating / cooling device for heating or cooling at least the hydrogen storage alloy of the hydrogen storage alloy or the poisonous gas adsorbent,
A hydrogen recovery and refining apparatus comprising a first valve interposed in the source gas supply line, a second valve interposed in the purified hydrogen gas releasing line, and a third valve interposed in the purge gas line.