JP2966570B2 - Hydrogen gas purification method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to using a hydrogen storage alloy originating
The present invention relates to a method for purifying hydrogen gas for cooling electric machines .

[0002]

2. Description of the Related Art Conventionally, in a method for maintaining the purity of hydrogen for cooling a generator using the function of purifying a hydrogen storage alloy, the hydrogen storage alloy used for this purpose is not subjected to any special pretreatment, and only a general activation treatment is performed. It is currently used. The activation treatment referred to here means that the alloy in a manufactured state is inactive because an oxide film is formed on its surface and does not absorb hydrogen. Therefore, heating and cooling are repeatedly performed in a hydrogen atmosphere (several times to several times). (After 20 times) Pretreatment for adding hydrogen absorbing ability to the alloy, the particle size is as produced.

[0003]

[Problems to be solved by the invention]

(1) The generator is normally inspected once a year, and the hydrogen filling after the open inspection is carried out by first replacing the air inside the machine with carbon dioxide having a large specific gravity and then gradually replacing it with hydrogen gas. ing. The hydrogen purity in the generator increases each time the hydrogen replacement is performed. However, as the purity increases, the efficiency of increasing the purity decreases, and the ultimate purity is naturally limited.

(2) As is understood from the above, the main components of the impurity component in the hydrogen in the generator are air (oxygen, nitrogen), carbon dioxide gas and water (water vapor), oil vapor leaking from a shaft sealing device, and the like. .

[0005] (3) It is known that the hydrogen storage alloy is poisoned due to the above-mentioned impurity components and the like, and it is known that the storage performance is deteriorated. However, when only the activation treatment is performed as a pretreatment of the alloy, the occlusion performance is reduced.

The present invention has been made in view of the above-mentioned state of the art, and an object of the present invention is to provide a method for purifying hydrogen gas for cooling a generator, in which the problems as in the prior art are eliminated.

[0007]

It has been reported that the toxicity of impurity gas depends on the type of alloy in part. However, the present inventors have found that another major factor is the toxicity of alloy gas depending on the alloy particle size. Was found to be very different. That is, it has been found that poisoning is reduced by reducing the alloy particle size.

The present invention has been completed on the basis of the above findings, and comprises a hydrogen gas for cooling a generator containing an impurity gas.
Is purified using a hydrogen storage alloy,
Fill the connected hydrogen storage alloy container with hydrogen storage alloy,
Repeated occlusion and release of hydrogen gas using pure hydrogen gas
By doing so, the average particle diameter of the hydrogen storage alloy is 30 μm or less
A method for purifying hydrogen gas for cooling a generator, characterized by performing a pretreatment .

[0009] In the present invention, the state as manufactured
Hydrogen storage alloy container with the hydrogen storage alloy powder connected to a generator
High-purity from cylinders etc. before operation of the equipment
Using hydrogen gas to repeatedly store and release hydrogen
The average particle size of the hydrogen storage alloy is 30 μm or less.
A pretreatment for miniaturization is performed. An example of alloy particle size reduction is
The cracking Rigyo by the fact to perform the insertion and extraction alternately with a container filled with a pair of alloy if e. According to pure <br/> degree increase maintenance method of the generator cooling hydrogen gas using a hydrogen storage alloy was subjected to the pretreatment may hydrogen impure region <br/> or al efficiency after regular inspection Purity increase can be maintained .

[0010]

[Function] The hydrogen purification function using a hydrogen storage alloy introduces a hydrogen gas containing an impurity gas into a container containing the hydrogen storage alloy, and hydrogen reacts with the hydrogen storage alloy to form a hydride.
The impurity gas is concentrated in the space inside the alloy container. Next, after the concentrated impurity gas is purged out of the system, hydrogen is released from the hydrogen storage alloy, but a part of the impurity gas concentrated in the alloy container space is occluded on the alloy surface. The impurity gas existing in the container space is easily purged out of the system by the pressure difference and the hydrogen released from the hydrogen storage alloy. On the other hand, the impurity gas adsorbed on the alloy surface is separated and separated by hydrogen released from the hydrogen storage alloy. The degree of separation depends on the amount of released gas.
Separation is promoted.

[0011] The hydrogen storage capacity is determined, in part, by the basic performance (pressure P-hydrogen storage capacity C-temperature T) of the alloy and the shape of the container (space volume), that is, the impurities associated with hydrogen storage of the hydrogen storage alloy. The hydrogen storage amount according to the hydrogen partial pressure determined by the gas concentration and the increase of the partial pressure, and the other is the storage inhibition due to the adsorption of the impurity gas to the alloy surface. That is, although the impurity gas is concentrated due to the hydrogen storage of the hydrogen storage alloy, the adsorption of the impurity gas to the alloy surface also progresses, and eventually the contact between the hydrogen gas and the alloy is stopped, and the hydrogenation of the alloy is stopped. This phenomenon is greatly affected by the grain size of the alloy.

The surface area per unit weight of the alloy can be increased by pre-refining the alloy as in the present invention, so that the hydrogen storage capacity can be increased.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG. Reference numeral 1 denotes a generator, and 2 denotes a hydrogen storage alloy container, which comprises a pair of A and B. The container is formed, for example, by a shell-and-tube method, in which a hydrogen-absorbing alloy is accommodated in a tube, and a cooling / heating medium flows on the shell side. Reference numeral 4 denotes a cooling / heating medium switching valve, which is provided with an inlet and an outlet for each container so as to be connected and switched to a cooling / heating medium source (not shown). Reference numeral 3 denotes an occlusion line for guiding hydrogen in the generator 1 to the hydrogen storage alloy container 2. Reference numeral 5 denotes an impurity gas purge line for purging the impurity gas concentrated in the hydrogen storage alloy container 1 to the outside of the system. Reference numeral 6 denotes a discharge line which stores hydrogen in the generator 1 in the hydrogen storage alloy, purges the concentrated impurity gas out of the system, and returns the hydrogen gas generated from the hydrogen storage alloy to the generator 1.

Next, the operation will be described. The hydrogen gas in the generator 1 becomes a three-line system that leads to any of the hydrogen storage alloy containers 2, and a refrigerant is passed through the container 2 to promote storage. After that, the impurity gas concentrated in the container 2 is purged out of the container 2 through the purge line 5, and then the hydrogen is released from the hydrogen storage alloy through the heating medium through the container 2, and returned to the generator 1 through the release line 6. The valves of the pair of containers 2 are controlled so that the valves are alternately inserted and extracted.

Next, the pretreatment method and properties of the hydrogen storage alloy used in this method will be described. Fig. 2
As shown in Fig. 7, after the hydrogen storage alloy container 2 was connected and hydrogen was filled from the inside of the hydrogen cylinder 7, a cooling medium and a heat medium were alternately passed through the hydrogen storage alloy container 2 to repeatedly store or release the hydrogen. FIG. 3 shows the number of repetitions N and the particle size distribution of the alloy at that time. In FIG. 3, the relative volume is defined as 100 where the largest particle size is 100, and the relative volume of each particle size relative thereto is shown.

The alloys and operating conditions are shown below. Alloy: LaMmNi ₅ (Mm: misch metal) Heat medium: Hot water 80 ° C. Refrigerant: Tap water 30 ° C. Average hydrogen pressure in the system: 5 kg / cm ² · G Storage / release cycle time: Storage / release 10 minutes, release 10 minutes

FIG. 4 shows the number of cycles of occlusion and release performed as preprocessing, N = 20, N = 1000, and N = 20.
The relationship between the number of cycles of occlusion and release and the amount of hydrogen occlusion when a generator gas having the following composition is occluded and released for a hydrogen storage alloy with 1500 and N = 2000 is shown.

As shown in FIG. 4, when the number of occlusions / releases N = 20 performed as a pre-treatment, the number of storage occlusions is four, and the amount of hydrogen occlusion decreases to about 13% for the first time, and N = 10.
In the case of 00, similarly, the decrease to about 50% occurs even when the number of storage cycles is four.
The second hydrogen storage amount was maintained. In the case of N = 1500 (average particle size 30 μm), the amount of occlusion decreases at the initial stage, but the amount of occlusion is kept constant after the fourth time.

Generator gas composition H ₂ : 95.5 vol% H ₂ O: 0.04 vol% O ₂ : 0.30 〃 Others: 0.05 Ｎ N ₂ : 1.60 ＣＯ CO ₂ : 0.50 〃

FIG. 5 shows the relationship between the average particle size of the alloy and the rate of decrease in the amount of occlusion. As shown in FIG. 5, the amount of occlusion is stabilized by setting the average particle size of the alloy to 20 μm, but the occlusion rate decreases when the average particle size is 40 μm and 100 μm. Becomes larger. In the case of an average particle size of 30 μm, it is necessary to keep the average particle size of the hydrogen storage alloy to 30 μm or less, preferably 20 μm or less, as can be seen from the fact that a constant storage amount is maintained after the fourth time.

[0021]

According to the present invention, the hydrogen storage alloy is pretreated and the particle size is reduced to an average of 30 μm, particularly 20 μm or less by pretreatment, so that the hydrogen storage amount can be stably maintained from a relatively low hydrogen purity. The operation of the refining device becomes possible, the number of hydrogen gas replacements in the machine after the periodic inspection of the generator is reduced, and the amount of hydrogen consumed for it is also reduced.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of one embodiment of purification of hydrogen gas in a generator to which the present invention is applied.

FIG. 2 is an explanatory view of one embodiment of a process for miniaturizing a hydrogen storage alloy used in the present invention.

FIG. 3 is a chart showing the relationship between the number of repetitions of the refinement treatment and the particle size distribution and relative volume of the hydrogen storage alloy when the treatment is performed in the mode shown in FIG. 2;

FIG. 4 is a table showing the amount of hydrogen occlusion of the hydrogen occlusion alloy with respect to the number of repetitions of the refinement treatment performed in the mode shown in FIG. 2;

FIG. 5 is a table showing a relationship between an average particle diameter of a hydrogen storage alloy and a hydrogen storage rate.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Koji Tokushige, Inventor Koji 4-33, Komachi, Naka-ku, Hiroshima City Inside Chugoku Electric Power Company (72) Inventor Akio Dewa 4--22 Kannon Shinmachi, Nishi-ku, Hiroshima-shi Sanishi Heavy Industries Hiroshima Research Institute, Inc. (72) Hiroshi Miyamoto 4-2-2 Kannon Shinmachi, Nishi-ku, Hiroshima City Mitsubishi Heavy Industries, Ltd.Hiroshima Research Institute Co., Ltd. (72) Sadaji Nishida 5007 Itozakicho, Mihara City, Hiroshima Prefecture Mitsubishi Heavy Industries (56) References JP-A-63-79701 (JP, A) JP-A-63-85001 (JP, A) JP-A-63-264869 (JP, A) JP-A-62-187101 ( JP, A) JP-A-1-246101 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C01B 3/00-3/58

Claims (1)

(57) [Claims] 1. A generator cooling hydrogen gas containing impurity gas hitting the purified using a hydrogen storage alloy, the generator
Filling the hydrogen storage alloy container connected to the machine
And use high-purity hydrogen gas to store and release hydrogen gas.
By repeating, the average particle size of the hydrogen storage
generator cooling, characterized in that pretreated m or less
Of hydrogen gas for industrial use .