JPS60161305A - Purification apparatus for gaseous hydrogen - Google Patents

Abstract

PURPOSE:To increase the yield of purification of hydrogen using metal hydride and to reduce hydrogenation cost by purifying purge gas previously and utilizing the purified gas are crude hydrogen gas again. CONSTITUTION:Crude hydrogen gas is fed to the first and second vessels 1, 2 for purifying hydrogen alternately with a specified pressure through a crude hydrogen gas pipe 14 and an ON/OFF control valve 32, 33. After occlusion of H2 by metal hydride is completed, gaseous impurities are discharged as purge gas from a vessel 1, and the purge gas is introduced into one of a purge gas reservoir 5 through a pipe 18. After the purge from the vessel 1 is completed, liberation of H2 from the metal hydride in the vessel 1 is proceeded, and the liberated gas is obtd. as purified gaseous H2 through a pipe 17. When >=2 vessels for the purified H2 are installed in parallel, purified gaseous H2 is obtd., alternately from each vessel, and purge gas is accumulated in the purge gas reservoir 5.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a hydrogen gas purification device, and more particularly, to a hydrogen gas purification device that uses metal hydrides.Hydrogen gas is generally used to decompose hydrocarbons or ammonia, or to convert water into electricity. Hydrogen gas is produced industrially by decomposition, etc., but in addition to inert gases such as helium and argon, hydrogen gas also contains oxygen, water,
Because it contains various impurity gases such as nitrogen, carbon oxide, and carbon dioxide, for example, in the semiconductor industry, metal processing industry, or instrumental analysis, it is used after refining the crude hydrogen gas mentioned in 2. are doing.

(Prior Art) Various methods for purifying hydrogen gas have already been known, but in recent years, certain metals or alloys selectively absorb hydrogen gas to form metal hydrides. It has been proposed to purify hydrogen gas by utilizing the property of metal hydrides to reversibly release hydrogen. This method basically involves filling a container filled with metal hydride with crude hydrogen gas under a predetermined pressure, for example, as described in Japanese Patent Application Laid-open No. 57-156304. After selectively storing hydrogen gas in the metal hydride, some hydrogen is released from the metal hydride, and any impurity gas remaining in the container without being stored in the metal hydride is purged from the container together with this hydrogen gas. After that, hydrogen is released under the hydrogen equilibrium decomposition pressure of the metal hydride to obtain purified hydrogen gas.

According to this method, purified hydrogen gas of extremely high purity can be easily obtained, but on the other hand, 5 to 30% of the hydrogen gas supplied into the container is lost as purge gas, so A'
The yield of N-made hydrogen gas is low, and the purification cost is 101
There are some serious problems.

(Object of the Invention) The present invention was made to solve the above-mentioned problems in hydrogen gas purification using metal hydrides, and the purpose is to pre-purify purge gas and reuse it as hydrogen gas from former No. 1 product. It is an object of the present invention to provide a hydrogen gas purification device that can increase the yield of hydrogen gas purification using metal hydrides and reduce the cost.

(Structure of the Invention) The hydrogen gas purification apparatus of the present invention includes a hydrogen gas purification container filled with a metal hydride capable of absorbing and releasing fa + hydrogen, and a purge gas containing impurity gas released from the hydrogen gas purification container. a purge gas storage container for storing the purge gas, a purge gas prepurifier for removing impurity gas in the purge gas from the purge gas storage container, and a purge gas booster for increasing the +dl purge gas to approximately the same pressure as the crude hydrogen gas, A hydrogen gas purification device characterized in that the hydrogen gas is mixed with crude hydrogen gas.

FIG. 1 shows an example of the apparatus of the present invention.

The first and second hydrogen gas purification vessels 1 and 2, each filled with a metal hydride, are connected in parallel with a crude hydrogen gas supply pipe 14 through a branch pipe 15 on the inlet side thereof, and the crude hydrogen gas is supplied through this pipe 14. is alternately supplied to the containers 1 and 2, and a purified hydrogen gas outlet pipe 17 is provided via a branch pipe 16 on the outlet side.
and the purge gas outlet pipe 18, and purified hydrogen gas and purge gas are alternately sent out from each container to the purified hydrogen gas outlet pipe 17 and the purge gas outlet pipe 18, respectively.

The purge gas outlet pipe 18 is connected to the purge gas reservoir tanks 5 and 6 as purge gas storage containers through branch pipes 19, respectively. The purge gas from the hydrogen gas purification container is stored in one of the reservoir tanks, and when the purge gas reaches a predetermined pressure, the pipe 20 The gas is then led to a parn gas prepurifier 7 or 8. In the illustrated embodiment, the purge gas reservoir tank is connected in parallel to the purn gas outlet pipe;
While purge gas is being sent from one reservoir tank to the pre-purifier, purge gas from the hydrogen gas purification vessel is supplied to the other reservoir tank and stored until a predetermined pressure is reached.

The pre-purifiers 7 and 8 described in - are, for example, an adsorbent filled with an adsorbent or a single membrane unit equipped with a gas separation membrane.
, the impurity gas in the parn gas is removed to make its purity almost equivalent to the crude hydrogen gas.

In the embodiment shown, the prepurifiers are also arranged in two stages in parallel, one of which prepurifies the parn gas while the other device is, for example, 4=I for regeneration.

This pre-storage vessel is connected by a line 23 to a purge gas storage booster vessel 9 or 10. In the embodiment shown, each storage booster vessel consists of a vessel filled with a metal hydride. As described above, in order to store and release the pre-purified purge gas, the metal hydride has heat medium circuits 11 and 12 in which a heat medium at a predetermined temperature is circulated.That is, the metal hydride is pre-purified. A predetermined amount of purge gas is stored at a predetermined temperature, and then heated to a predetermined temperature by a heating medium circuit, thereby releasing the purge gas at approximately the same pressure as the i'Il hydrogen gas.

This purge gas is combined with the crude hydrogen gas. Note that a compressor may be used to increase the pressure of the purge gas.

” The operation of the device described in item 1 will be explained. For simplicity, it is assumed that all valves are initially closed.

When crude hydrogen gas is alternately supplied through the crude hydrogen gas supply pipe 14 to the first and second hydrogen gas purification vessels 1 and 2 at a predetermined pressure by valves 32 and 33 whose opening and closing are controlled, for example, metal hydride absorbs hydrogen at a predetermined temperature and pressure, and impurity gases remain in the container without being absorbed by the metal hydride. Therefore, after the storage by the metal hydride is completed, the crude hydrogen gas supply valve 31 is closed, the valves 34 and 37 are opened, and the impurity gas is discharged from this first container 1 as a purge gas. The purge gas is sent to the purge gas reservoir tank 5. In this way, after the purge gas from the hydrogen gas purification container I is finished, the valve 37 is closed, and the valve 36 is closed.
is opened to release hydrogen from the metal hydride in the container 1, and this is obtained as tFj'A hydrogen gas from the purified hydrogen gas outlet pipe I7. By installing two or more purified hydrogen gas containers in parallel, purified hydrogen gas can be obtained alternately from each container, and purge gas is accumulated in the purge gas reservoir tank 5.

When the purge gas pressure in the purge gas reservoir tank reaches a predetermined value, the valves 39, 41, 43 and 46 are opened, and the purge gas is sent to one of the purge gas prepurifiers 7 through the pipe 20 to remove impurity gases. After that, the purge gas is delivered to one purge gas storage pressure vessel 10. In this container, after a predetermined amount of purge gas is stored in the metal hydride, the metal hydride is heated to a predetermined temperature in the built-in heating medium circuit 12, and the valves 49 and 50 are opened to release the purge gas. It is discharged at a predetermined level of 1JE, and is made to join the crude hydrogen gas in the purified hydrogen gas supply pipe 14 through the pipe 26.

In the illustrated embodiment, a reservoir tank is used as a purge gas storage container, but a container filled with metal hydride may be used as a purge gas storage container to store a predetermined amount of purge gas. Conversely, a reservoir tank can be used as a purge gas storage pressurization container. Furthermore, if necessary, when releasing the purge gas from the hydrogen gas purification vessel, the metal hydride can be heated to a predetermined temperature and the purge gas can be released at a predetermined pressure.

(Effect of the Invention) As described above, according to the apparatus of the present invention, the purge gas containing impurity gas discharged from the hydrogen gas purification container is pre-purified, and its pressure is approximately equal to that of hydrogen gas made in '11. Since the hydrogen gas is raised to the same pressure, combined with the same pressure, -υ, and then sent to the hydrogen gas purification vessel, the yield of purified hydrogen gas is high, and the purification cost is also reduced.

The present invention will be explained below with reference to Examples.

(Example) In the illustrated apparatus, 3.55.0 kg of LaNi as a metal hydride is filled into the first and second hydrogen gas storage containers, and each container is heated by a heating medium circuit. Inlet 4 of each container while holding at 'C'
By controlling the opening and closing of the valves 1 and 1, crude hydrogen gas consisting of 99 mol% hydrogen and 1 mol% methane was supplied to each container from the crude hydrogen gas supply box at a pressure of 9 atmospheres. 114 hours required for one cycle of storing hydrogen gas in each container, releasing part gas, and releasing purified hydrogen gas
: It was 15 minutes.

After the storage of hydrogen gas in each of the four vessels was completed, 10% of the amount of stored hydrogen was purged, and the remainder was discharged as purified hydrogen gas to the purified hydrogen waste outlet pipe. In this way, purified hydrogen gas with a purity of 99.99 mol% was obtained alternately from each container. Is the acquisition speed 2NrI? / It was time.

Purge gas was alternately released from each container and delivered to one purge gas reservoir tank. The average hydrogen purity of the Versicas was 90 mol%.

When the pressure of the purge gas in the reservoir tank reaches 3.5 atmospheres, this purge gas is sent to one adsorption device as a purge gas pre-purification device, and the impurity methane gas is adsorbed and removed, resulting in hydrogen purity of approximately It was purified to 99 mol%.

Then, LaNi4.85AI, as a metal hydride,
, 50, 5 kg each in the purge gas storage booster filled with the above reserve Ii'j'! After introducing the purge gas and storing a predetermined amount, the metal hydride is removed by the heating medium circuit.
heated to 0 °C and boosted the purge gas to a pressure of 9 atmospheres,
The crude hydrogen gas was sent through a pipe to the crude hydrogen gas supply pipe.

[Brief explanation of drawings]

The drawings show examples of apparatus configurations suitable for carrying out the method of the invention. 1.2... Hydrogen gas purification container, 3.4... Heat medium circuit, 5.6... Purge gas reservoir tank, 7.8...
・Purge gas preliminary purification device, 9.10...Purge gas storage pressurization container, 11.12...Heating medium circuit, 14...
Crude hydrogen gas supply pipe, 17... Purified hydrogen gas outlet pipe, 1
Σ)...Purge gas outlet pipe. Patent applicant Mototoshi Numa, Representative Ichi, Sekisui Chemical Co., Ltd.

Claims (1)

[Scope of Claims] +1.1 (a) A hydrogen gas purification container filled with a metal hydride capable of absorbing and releasing hydrogen, and +bl a purge gas for storing purge gas containing impurity gas released from the hydrogen gas purification container. A storage container, (C1) a purge gas pre-purifier for removing impurity residue in the purge gas from this purge gas storage container, and a purge gas booster that raises the purge gas to approximately the same pressure as the tn hydrogen gas, and A hydrogen gas purification device characterized in that the hydrogen gas is mixed with crude hydrogen gas.