JPH0776668B2 - Gas introduction device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas introducing device for introducing gas into a liquefying device for helium, hydrogen and the like.

[0002]

2. Description of the Related Art Conventionally, various devices for cooling and liquefying helium gas, hydrogen gas and the like have been known. However, if the gas is introduced into such a liquefying device as it is, the impurities contained in the gas are solidified in the low temperature heat exchange passage and block the heat exchange passage. When such a situation occurs, a so-called regenerating operation of heating the heat exchange passage to dissolve impurities is required. However, the more impurities in the gas, the more frequently the regenerating operation must be performed. Inevitably, the liquefaction efficiency is significantly reduced.

Therefore, Japanese Patent Publication No. 52-4517 discloses that a gas purifying system for removing impurities in the gas by heat exchange is installed before the gas is introduced into a heat exchanger for liquefying the gas. ing.

[0004]

SUMMARY OF THE INVENTION In the device of the above publication,
Since the gas is purified by the heat exchanger, impurities may freeze inside the heat exchanger for purification itself. In this case, there is an inconvenience that the gas purifying heat exchanger eventually requires a regenerating operation, and the regenerating operation must be performed more frequently as the amount of the impurities increases. That is, with this device, it is difficult to reduce the regeneration frequency in the entire liquefaction system including the purification system.

In view of such circumstances, it is an object of the present invention to provide a gas introduction device which has a simple structure and can greatly reduce the frequency of regeneration of the heat exchanger in the entire liquefaction system.

[0006]

DISCLOSURE OF THE INVENTION The present invention relates to a gas introducing device for introducing a gas into a liquefying device for liquefying the introduced gas by cooling;
A separation membrane that preferentially permeates a gas component for the purpose of liquefaction out of the components of the gas to be pumped, the first passage having the separation membrane provided downstream of the pumping means, and the separation And a second passage that bypasses the membrane,
An open / close switching means for opening and closing both passages, and the concentration of the liquefaction target component in the introduced gas are detected, and when the detected concentration is a certain value or more, the introduced gas is passed through the first passage and the detected concentration is less than the certain value. In this case, switching control means for controlling the switching of the open / close switching means so as to pass the introduced gas through the second passage is provided (Claim 1).

Another object of the present invention is to provide a gas introducing device for introducing a gas into a liquefying device for liquefying the introduced gas by cooling, and a pumping means for pumping the gas and a liquefaction of the components of the gas to be pumped. And a separation membrane that preferentially permeates the gas component, and an introduction passage for introducing the gas into the liquefaction device as it is on the downstream side of the pressure-feeding means, and a separation membrane in the middle, and the gas is fed by the pressure-feeding means. A return passage for returning to the upstream side of the means is provided, and an opening / closing switching means for opening and closing both passages, and the concentration of the liquefaction target component in the introduced gas are detected. And a switching control means for controlling the switching of the opening / closing switching means so that the introduced gas is passed through the reflux passage when the detected concentration is less than a certain value. .

[0008]

According to the apparatus of the first aspect, when the introduced gas passes through the separation membrane, the component gas for the purpose of liquefaction is preferentially permeated in this gas, so that the purity of the gas is improved. By introducing the gas into the liquefaction device in such a high purity state, the freezing of impurities in the liquefaction device is significantly reduced, and the regeneration frequency is also reduced. Moreover, since heat exchange is not used for purifying the gas, the regeneration operation in the gas introduction device is unnecessary.

When the impurity concentration of the recovered gas is less than a certain value, the gas is directly introduced into the liquefaction device, and only when the impurity concentration is more than the certain value, the gas is liquefied after passing through the separation membrane. Introduced into the device.

Further, according to the apparatus of claim 2, when the impurity concentration of the recovered gas is less than a certain value, the gas is directly introduced into the liquefaction device, and only when the impurity concentration is more than the certain value. This gas is refluxed while passing through the separation membrane.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS.

FIG. 2 shows the configuration of the entire helium liquefaction system. This system comprises a liquefaction device 10,
A gas circulation device 12 and a gas recovery device (corresponding to the gas introduction device of the present invention) 14 are provided.

The gas circulation device 12 is a helium gas supply manifold 1 for supplying pure helium gas.
6, a helium compressor 18 for pumping this helium gas,
A recovery tank 20 that absorbs gas pressure fluctuations during operation,
And a ballast tank 22, and when the system is started, the pure helium gas in the helium gas supply manifold 16 is compressed by the helium compressor 18.
The liquid is supplied to the liquefaction device main body 25 of the liquefaction device 10 through the passage 24.

The gas flowing through the passage 24 is pre-cooled by heat exchange with liquefied nitrogen in the first heat exchanger 26, then passes through the adsorber 32 for removing impure gas, and then the second to fifth heat exchangers. After being cooled through 27 to 30 and further liquefied through the JT valve 40, it is supplied into the liquefied helium container 46 through the supply passage 44 in the delivery tube 42. The gas in the liquefied helium container 46 returns to the return passage 48.
Through which heat is exchanged with the supply gas in the heat exchangers 26 to 30 and returned to the gas recirculation device 12. Further, the gas in the passage 24 is guided to the expanders 36 and 38 by opening the valve 34 appropriately, and joins the return passage 48.
By repeating such gas recirculation, liquefaction of the helium gas proceeds.

The liquid helium in the liquefied helium container 46 is drawn to the outside through the transfer tube 50 and used by the user side, but after being gasified by such use, The gas is recovered by the gas recovery device 14 and reintroduced into the liquefaction device 10.

As shown in FIG. 1, the gas recovery device 14 includes an air bag 62 for storing the recovered gas, and a recovered gas compressor (pressure feeding means) 52 and a cooler 54 are provided on the downstream side thereof. It is provided. On the downstream side of the cooler 54, the gas passage is branched into a passage 55 toward the liquefaction device and a passage toward the recovery gas cradle 58, and the passage toward the recovery gas cradle 58 is opened / closed. A valve 56 is provided. The passage between the open / close switching valve 56 and the recovered gas cradle 58 is connected to the gas tank 62 via the open / close switching valve 60.

The passage 55 is branched into a second passage 63 which directly communicates with the liquefaction device 10 and a first passage 64 which is provided with a separation membrane unit 70 on the way, and each passage 6
Opening / closing switching valves 66 and 68 are provided at 3 and 64, respectively.

The separation membrane unit 70 has an appropriate housing, and a semipermeable membrane made of fibers such as cellulose acetate is placed in the housing. , Which has the property of preferentially permeating helium in the flowing gas is used. The separation membrane unit 70 itself is already known, and various types such as that disclosed in JP-B-63-44410 can be applied.

An open / close switching valve 72 is provided in the discharge passage extending from the separation membrane unit 70.

Further, in the downstream passage of the recovered gas compressor 52, a concentration meter (switch control means) 74 for detecting the impurity concentration of the gas flowing in this passage, and on / off depending on the pressure of the gas. A pressure switch 76 is provided. Then, based on these detection results, the following switching control is executed.

(A) During gas introduction, if the detected concentration is less than a predetermined value (less than 2% in this embodiment), the open / close switching valve 66
To open and close the open / close switching valve 68. On the contrary, when the detected concentration is equal to or higher than the predetermined value (2% or more), the open / close switching valve 66 is closed and the open / close switching valve 68 is opened.

(B) When the detected pressure is less than a predetermined value (less than 50 atm in this embodiment), that is, the pressure that can be directly used as the introduced gas has not been reached, the open / close switching valve 56 is closed and the open / close switching valve 60 is opened. open. As a result, the gas is returned to the gas bag 62 and recompressed by the collected gas compressor 52. In other cases, open the switching valve 56,
The open / close switching valve 60 is closed.

(C) The open / close switching valve 72 is opened when the detected concentration exceeds a certain value.

Incidentally, reference numerals 78 to 80 in FIG. 1 are pressure compensation valves.

The gas discharged from the gas recovery device 14 is introduced into the heat exchangers (internal purifiers) 82 and 84 provided in the liquefaction device 10, cooled there, and then introduced into the passage 24. It is designed so that it can be eaten.

Next, the operation of the gas recovery device 14 will be described.

First, in the initial stage, the open / close switching valves 60, 6
6, 68 are closed, and the open / close switching valve 56 is opened.
On the other hand, the recovered impure gas temporarily stays in the gas bag 62, is then compressed to about 150 atm by the recovered gas compressor 52, and is stored in the recovered gas cradle 58.

While this gas is gradually discharged, its concentration is monitored by the densitometer 74. This concentration is 2%
In the case of less than, the open / close switching valve 68 is closed and the open / close switching valve 66 is opened, so that the gas directly passes through the second passage 63, that is, bypasses the separation membrane unit 70, and the heat exchange in the liquefaction device 10 is performed. It is introduced into the vessels 82 and 84. At this time, since the impurity concentration of the gas is less than 2%, the amount of impurities frozen in the heat exchangers 82 and 84 can be suppressed to an extremely small amount.

Here, the opening / closing switching valve 66 is used to prevent some gas from being consumed together with impurities through the opening / closing switching valve 72 when the separation membrane 70 is used and to extend the life of the separation membrane 70. is there.

On the other hand, when the detected concentration is 2% or more, the switching valve 66 is closed and the switching valve 68 is opened, so that the gas is separated into the separation membrane unit 70 provided in the first passage 64. Be led to. In this separation membrane unit 70,
Since the helium gas is preferentially permeated as compared with other impurities, the gas that permeates the separation membrane unit 70 is in a state in which the helium purity is increased. For example, when the separation membrane made of the above-mentioned cellulose acetate was used, it was found that if the concentration of the impure component of the gas before passing through this was 10%, the above-mentioned concentration would be reduced to 2% after passing. is doing.
After the purity is increased in this way, the gas is passed through the heat exchanger 8
The heat exchanger 8 is also introduced by introducing the heat exchangers 2 and 84.
Freezing in 2, 84 is suppressed to a very small level, and this heat exchanger 8
The playback frequency at 2,84 is greatly reduced.

In the separation membrane unit 70, the impure gas accumulated on the upstream side of the separation membrane is appropriately discharged at the inlet concentration through the open / close switching valve 72 to maintain the purity.

Next, a second embodiment will be described with reference to FIG.

In this embodiment, two recovery gas cradle 86, 87 are connected in parallel on the downstream side of the recovery gas compressor 52, and an open / close switching valve 88, 89 is provided on the upstream side of each recovery gas cradle 86, 87. Is provided.

The passage between the upstream recovered gas cradle 86 and the open / close switching valve 88 is connected to the gas bag 62 via the recirculation passage 91, and in the middle of the recirculation passage 91 the same as in the above-described embodiment. Separation membrane unit 70, open / close switching valve 72,
Further, a densitometer 90 for controlling the opening / closing of the opening / closing switching valve 72 is provided. On the other hand, an introduction passage 92 directly connected to the heat exchangers 82 and 84 of the liquefaction device 10 is connected to the passage between the downstream gas recovery card 87 and the open / close switching valve 89.

Also in the apparatus of this embodiment, a densitometer 74 is provided on the downstream side of the recovered gas compressor 52, and the following opening / closing control is executed by the densitometer 74.

First, the recovered gas is stored in the gas bag 62 in the same manner as in the above embodiment, and is recovered by the recovered gas compressor 52 to about 150.
Although compressed to atmospheric pressure, when the impurity concentration of this gas is 2% or more, the open / close switching valve 89 is closed and the open / close switching valve 88 is opened, and the impure gas is temporarily stored in the recovered gas cradle 86. It The gas in the recovered gas card 86 is passed through the separation membrane unit 70 and purified, and then returned to the gas tank 62 to recover the recovered gas compressor 52 again.
Received a compression operation by.

On the other hand, when the impurity concentration is less than 2%, the open / close switching valve 88 is closed and the open / close switching valve 89 is opened, and the collected gas is the collected gas card 8
It is stored in No. 6 and is directly introduced into the heat exchangers 82 and 84 in the liquefaction device 10 through the introduction passage 29.

Even in such an apparatus, the liquefaction apparatus 10
Since the helium gas kept in high purity is always introduced therein, the freezing of impurities in the heat exchangers 82 and 84 is greatly suppressed.

The present invention is not limited to such an embodiment, and the following modes can be adopted as an example.

(1) In the present invention, the gas to be liquefied is not limited to helium gas, but can be easily applied to liquefaction of, for example, hydrogen gas or argon gas. That is, by using a semipermeable membrane that preferentially permeates the gas, the same effect as described above can be obtained.

(2) The liquefaction device to which the gas introduction device of the present invention is applied is applicable to various devices for liquefying the introduced gas by cooling, regardless of the specific configuration thereof. is there.

[0042]

INDUSTRIAL APPLICABILITY As described above, the present invention purifies gas by using the separation membrane that preferentially permeates the gas component for the purpose of liquefaction among the components of the gas to be pumped, and introduces it into the liquefaction device. Therefore, it is possible to suppress clogging due to freezing of impurities in the heat exchanger in the liquefaction device, thereby reducing the regeneration frequency and eliminating the need for the regeneration operation in the gas introduction device itself. There is an effect that the regeneration frequency of the heat exchanger of the entire gas liquefaction system including the gas introduction device can be significantly reduced compared to the conventional case.

Further, according to the apparatus of the first aspect, when the concentration of the recovered gas is equal to or higher than a certain value, the purity of the introduced gas is increased through the first passage provided with the separation membrane to increase the concentration of the recovered gas. When is less than a certain value, the gas can be directly introduced into the liquefier through the second passage, so that the separation membrane can be used only when it is truly necessary, and its life can be extended. .

Also, in the apparatus according to the second aspect, the life of the separation membrane can be extended by refluxing this gas through the separation membrane only when the concentration of the recovered gas is equal to or higher than a certain value.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a gas recovery device according to a first embodiment of the present invention.

FIG. 2 is an overall configuration diagram of a gas liquefaction system including the gas recovery device.

FIG. 3 is an overall configuration diagram of a gas recovery device according to a second embodiment of the present invention.

[Explanation of symbols]

 10 Liquefaction device 14 Gas recovery device (gas introduction device) 52 Recovery gas compressor (pressure feeding means) 63 First passage 64 Second passage 66, 68, 88, 89 Open / close switching valve (open / close switching means) 70 Separation membrane unit 74 Concentration meter (switch control means) 91 Reflux passage 92 Introduction passage

Claims (2)

[Claims] 1. A gas introducing device for introducing gas into a liquefying device for liquefying the introduced gas by cooling,
A pressure-feeding means for pressure-feeding the gas and a separation membrane for preferentially permeating a gas component for the purpose of liquefaction among the components of the gas to be pressure-fed are provided , and the separation membrane is provided downstream of the pressure-feeding means.
The first passage, which is cut off, and the second passage, which bypasses the separation membrane.
And the switching of opening and closing both passages
And the concentration of the target liquefaction component in the introduced gas
However, if the detected concentration is above a certain level, the first passage
When the introduced gas is passed through the
The opening / closing switching hand is provided so that the introduced gas is passed through the second passage.
A gas introduction device, comprising: a switching control unit that controls switching of stages . 2. A liquid for liquefying the introduced gas by cooling
In the gas introduction device for introducing gas into the gasification device,
The pumping means for pumping the gas and the component of the gas to be pumped
Separation that preferentially permeates gas components for liquefaction
It is equipped with a membrane, and the gas is left as it is on the downstream side of the pumping means.
An introduction passage for introducing into the liquefaction device and a separation membrane in the middle
Is provided to return the gas to the upstream side of the pumping means.
A flow passage is provided , an open / close switching means for opening and closing both passages, and the concentration of the liquefaction target component in the introduced gas are detected. When the detected concentration is a certain value or more, the introduced gas is passed through the introduction passage to detect the above. A gas introduction device comprising: a switching control means for controlling the switching of the opening / closing switching means so that the introduction gas is passed through the reflux passage when the concentration is less than a certain value.