JPH05309225A - Helium purifier - Google Patents

Abstract

PURPOSE:To prevent the fluctuation in pressure on the upstream side of a purifying compressor by using simple and low cost structure. CONSTITUTION:Both a gas returning path 16 for returning gas discharged from a gas cylinder 17 to a gas bag 12 and a bypass path 44 for guiding the gas to the outlet side of a purifying compressor 22 are provided. Pressure regulating valves 46, 47 are installed in the paths 16, 44, respectively. When the pressure detected by a pressure regulating valve 48 is equal to or more than the pressure on the outlet side of the purifying compressor 22 on operation, gas is passed through the bypass path 44 and when the former pressure is below the latter, it is passed through the gas returning path 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a helium refining device for recovering impure helium gas and purifying high purity helium gas from the recovered gas.

[0002]

2. Description of the Related Art Usually, the vaporized gas of liquid helium is recovered and then liquefied in a liquefier for reuse, but in order to introduce helium gas into the liquefier, the purity of the introduced gas is required. Must be kept at a high level above a certain level.

Conventionally, as a helium refining apparatus for obtaining such high-purity helium gas, a low temperature adsorption method, a coagulation method, a pressure swing adsorption (hereinafter, referred to as
It is called PSA. ) Method and separation membrane method are known. Among them, the low temperature adsorption method and the coagulation method require refrigeration to adsorb and coagulate impurities, whereas the PSA method and the like can be refined by operating at room temperature, and therefore their development is active. (See, for example, Japanese Patent Laid-Open No. 1-266831).

An example of this type of device is shown in FIG. In the figure, the helium vaporized gas recovered through the helium recovery passage 100 is once collected in a gas bag 102 whose internal pressure is kept constant (approximately atmospheric pressure).
From 02, it is introduced into the gas cylinder 106 in a compressed state through the recovery compressor 104 and is stored therein.

During the liquefaction, the impure gas in the gas cylinder 106 is introduced into the room temperature refining device 108, and the refining compressor 110 causes the CFC refrigerator 112 and the separation membrane device 11 to operate.
Pumped to 6. In the Freon refrigerator 112, water in the gas is removed, and the gas from which the water is removed is PSA.
Introduced into device 114. In this PSA device 114,
Impurity components (such as N _2, O ₂₎ adsorption of the gas, is removed, thereby a high-purity helium gas which has been purified is introduced into the helium liquefier 120 having a compressor 118 and the like. Here, since a certain amount of expensive helium gas remains in the adsorbed impure gas, this impure gas is directly returned to the upstream side of the refining compressor 110 in the discharging and cleaning steps and is again used for refining. It

On the other hand, in the separation membrane device 116, introduced impurity components in a gas (such as N _2, O ₂₎ is concentrated, while being discharged out of the system, the remaining gas, i.e. with a degree of purity The helium purified gas is directly returned to the upstream side of the refining compressor 110.

[0007]

The above-mentioned refining compressor 110.
The inlet side pressure for operating well is determined to a certain rated value, and this rated value is usually set to about atmospheric pressure. Therefore, if the pressurized gas stored in the gas cylinder 106 is directly introduced into the refining compressor 110 in the above apparatus, normal operation of the refining compressor 110 cannot be expected. Therefore, in the conventional device, the gas cylinder 106 is
It is necessary to perform pressure control to reduce the gas discharged from the gas to the rated pressure of the refining compressor 110, but it is extremely difficult to accurately adjust the pressure of the gas from the gas cylinder 106 to the rated pressure in this way. Difficult to do.

As means for performing such pressure adjustment, all the gas discharged from the gas cylinder 106 is once returned to the gas bag 102 and returned to the atmospheric pressure, and a new refining compressor 110 is newly supplied from this gas bag 102. A method of supplying gas to the compressor is conceivable. In this method, however, the gas compressed by the recovery compressor 104 is returned to the atmospheric pressure and compressed by the refining compressor 110 again.
The required power of 04 and 110 becomes very large, and wasteful energy is consumed. In addition, the refining compressor 11
Since a large amount of gas must be compressed at 0, a large compressor must be used as the refining compressor 110, and an increase in initial cost cannot be avoided.

In view of such circumstances, it is an object of the present invention to provide a helium refining device which has a low cost structure and can operate the refining compressor favorably while avoiding the waste of energy.

[0010]

DISCLOSURE OF THE INVENTION The present invention comprises a gas bag in which an internal pressure is kept constant and impure helium gas is introduced, a pressure container for containing the impure helium gas in a pressurized state, and the gas bag A recovery compressor for press-fitting the derived gas into the pressure vessel, a refining compressor for compressing the gas discharged from the pressure vessel, and a residual high-purity helium that adsorbs an impure component in the compressed gas. In a helium purification device equipped with a pressure swing adsorption device for discharging gas, a gas return passage connecting the pressure container and the gas bag, and a gas supply passage connecting the gas bag and the inlet side of the purification compressor. A bypass passage connecting the pressure vessel and the outlet side of the refining compressor, and a gas returned from the pressure vessel is returned to the gas bag through the gas return passage. And a passage switching means for switching the passage between a state in which the gas discharged from the pressure vessel is directly introduced into the outlet side of the refining compressor through the bypass passage (claim 1). ..

Further, the pressure of the gas discharged from the pressure vessel is detected, and when the pressure is equal to or higher than a certain value, the passage is switched to the bypass state and to the return state when the pressure is equal to or lower than the certain value. By providing a switching control means for controlling the switching means (claim 2) or by providing an impure gas return passage for returning the impure gas adsorbed by the pressure swing adsorption device to the gas bag (claim 3). A more excellent effect as described below can be obtained.

[0012]

According to the apparatus of claim 1, for example, when the pressure of the gas discharged from the pressure vessel is equal to or lower than a certain value, more specifically, lower than the outlet side pressure of the refining compressor,
By switching the passage state to the return state by the passage switching means, the gas is introduced into the gas bag, and the gas is introduced into the purification compressor through the gas supply passage. Can be kept at a constant pressure. On the other hand, for example, when the pressure of the gas discharged from the pressure vessel is equal to or higher than a certain value, more specifically, when it is equal to or higher than the outlet side pressure of the refining compressor, the passage state is switched to the bypass state by the passage switching means. By introducing the above gas to the outlet side of the refining compressor, the high-pressure gas can be directly supplied to the PSA device without consuming the power of the refining compressor.

Further, according to the apparatus of the second aspect, the pressure of the gas discharged from the pressure vessel is detected by the switching control means, and the above switching control is automatically performed based on this pressure. ..

In this apparatus, since some expensive helium gas remains in the impure gas adsorbed by the PSA apparatus, it is desirable to return this impure gas to the upstream side of the refining compressor. However, according to the device of claim 3, the return gas from the PSA device is
Since the gas is introduced into the gas bag for recovering the gas, the internal pressure of which is kept constant, the pressure fluctuation on the upstream side of the refining compressor due to the return of the gas can be prevented.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG.

In the figure, 10 is a gas recovery passage,
The gas recovery passage 10 is connected to the gas bag 12. The volume of the gas bag 12 freely changes according to the amount of gas introduced, and therefore the internal pressure is always kept substantially constant (atmospheric pressure).

This apparatus is roughly divided into a gas recovery system and a purification system. As a gas recovery system, a gas cylinder 17 is connected to the gas bag 12 via a gas storage passage 14 and a gas return passage 16, and a recovery compressor 18 is provided in the gas storage passage 14.

As a refining system, an inlet side of a refining compressor 22 is connected to the gas bag 12 via a gas supply passage 20, and an outlet side of the refining compressor 22 is connected to a CFC refrigerator 26 through a gas introduction passage 24. It is connected. The CFC refrigerator 26 is connected via a passage 28 to a PSA device 30 similar to a conventionally known device. This P
The SA device 30 is connected via a purified gas introduction passage 39 to an appropriate passage of a helium liquefier 40 including a compressor 42 and the like. On the other hand, the outlet side of the refining compressor 22 is also connected to a separation membrane device 34 via a gas introduction passage 32.

The PSA device 30 is connected to the gas bag 12 via an impure gas return passage 36 and the gas return passage 16, and the separation membrane device 34 is also connected to the gas via a purified gas return passage 38. It is connected to the bag 12.

Further, as a first feature of this apparatus, in the gas return passage 16, the gas cylinder 1 is provided more than the connecting portion between the gas return passage 16 and the impure gas return passage 36.
A bypass passage 44 branches from a portion near 7 and is connected to the outlet side of the refining compressor 22.
4, the outlet side of the refining compressor 22 and the gas cylinder 17 are directly connected. The gas return passage 16 and the bypass passage 44 are provided with pressure control valves (passage switching means) 46 and 47, respectively, and these pressure control valves 46 and 47 cut off the passages 16 and 44 from the communication state. The state can be switched to.

Further, as a second feature of this apparatus, a pressure regulator (switch control means) 48 for detecting the pressure of the gas discharged from each gas cylinder 17 is connected to the immediate downstream side of each gas cylinder 17. This pressure regulator 48 is
When the detected pressure is lower than the outlet side pressure (15 kg / cm ² in this embodiment; hereinafter simply referred to as the compressor outlet side pressure) during the operation of the refining compressor 22, the pressure control valve 46 is opened. The secondary side pressure is adjusted to substantially atmospheric pressure and the pressure control valve 47 is fully closed. When the detected pressure is equal to or higher than the compressor outlet side pressure, the pressure control valve 46 is fully closed and the pressure control valve 47 is closed. It is configured to open and adjust its secondary pressure to a pressure equivalent to the compressor outlet pressure.

Next, the operation of this device will be described.

First, in a state where the helium liquefier 40 is not liquefied, the impure gas recovered through the gas recovery passage 10 is introduced into the gas bag 12, and further through the gas storage passage 14 and the recovery compressor 18. It is stored in the gas cylinder 17.

Thereafter, when the liquefaction operation is started, the pressure regulator 48 detects the pressure of the exhaust gas from the gas cylinder 17. When the pressure of this exhaust gas exceeds the pressure on the outlet side of the compressor, the pressure control valve 46 is fully closed and the pressure control valve 47 is opened. As a result, the exhaust gas is
Through the bypass passage 44, the refining compressor 2 in a state where the pressure is adjusted to a pressure equivalent to the compressor outlet side pressure by the pressure control valve 47.
It is directly guided to the outlet side of 2 and sent to both the Freon refrigerator 26 and the separation membrane device 34 via the gas introduction passages 24 and 32, respectively.

Water contained in the gas sent to the Freon refrigerator 26 is removed by coagulation in the Freon refrigerator 26 and introduced into the PSA apparatus 30 in a dried state. In this PSA apparatus 30, the impure components such as oxygen and nitrogen in the mixed gas are adsorbed and removed, and the high-purity helium gas purified by this is introduced into the helium liquefier 40 through the purified gas introduction passage 39. Used for liquefaction. On the other hand, the adsorbed impure component contains a certain amount of helium, and is passed through the impure gas return passage and the gas return passage 16 in the discharge and cleaning steps to form the gas bag 1
It is returned to No. 2 and used for refining again.

On the other hand, the gas sent to the separation membrane device 34 is
Only the impure component in it is concentrated and discharged out of the system.
The gas that has not been discharged, that is, the helium purified gas having a certain degree of purity, is returned into the gas bag 12 through the purified gas return passage 38 and is again provided for purification.

While such refining proceeds, the gas cylinder 1
When the amount of gas in 7 decreases and the pressure detected by the pressure regulator 48 falls below the compressor outlet side pressure, the pressure regulating valve 46 is opened and the pressure regulating valve 47 is closed, and the pressure regulating valve 46 brings the pressure to atmospheric pressure. The depressurized gas is introduced into the gas bag 12 through the gas return passage 16. And this gas bag 1
The gas inside 2 is sent to the refining compressor 22 in the gas supply passage 20, and the gas is kept at approximately atmospheric pressure, and after being satisfactorily compressed by the refining compressor 22, the Freon compressor 26 is processed in the same manner as above. And sent to the separation membrane device 34.

As described above, in this device, the pressure of the exhaust gas from the gas cylinder 17 is detected, and when this pressure is lower than the compressor outlet side pressure, this gas pressure is utilized in the gas bag 12 for recovery. By returning the pressure to the atmospheric pressure after introduction to the refining compressor 22, the refining compressor 22 is always operated in a stable state without providing any special means for controlling the pressure on the suction side of the refining compressor 22. can do.

Moreover, when the pressure of the gas discharged from the gas cylinder 17 is equal to or higher than the pressure on the outlet side of the compressor, the pressure of this gas is not reduced and the PSA unit 26 or the separation membrane is directly passed through the purification compressor 22. By supplying gas to the device 30, the power required for the refining compressor 22 can be reduced. Further, by reducing the gas processing amount of the refining compressor 22, a compressor having a processing capacity lower than that of the conventional compressor can be used for the refining compressor 22, and thus the initial cost of the apparatus can also be reduced.

In the apparatus of this embodiment, when all the gas from the gas cylinder 17 is returned to the gas bag 12 without performing the bypass, it is necessary to use a compressor having a processing capacity of 113 Nm ² / h or more as the refining compressor 22. However, when operating by performing the above-mentioned bypass, 72 Nm ² / h of gas is made to flow in the bypass passage 42, so the gas treatment amount of the refining compressor 22 is set to 113 N above.
We were able to confirm that it was possible to reduce from m ² / h to 41 Nm ² / h.

Furthermore, in this embodiment, since the gas adsorbed by the PSA device 30 is returned to the gas bag 12, it is possible to prevent the suction side pressure of the refining compressor 22 from fluctuating due to the return of this gas. Therefore, there is an advantage that the operating state of the refining compressor 22 can be further stabilized.

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

(1) In the above embodiment, the pressure return valves 16 and 47 are provided with the pressure control valves 46 and 47, but when the allowable range of the pressure introduced into the gas bag 12 is relatively wide. May be provided with a simple open / close switching valve instead of the pressure control valve 46.
When the allowable range of the pressure introduced into the device 30 is relatively wide, a simple switching valve may be provided instead of the pressure control valve 47.

(2) In the above embodiment, the passage is automatically switched by the pressure regulator 48, but a simple pressure gauge is provided instead of the pressure regulator 48, and a manual operation is performed based on the measured value. The passage may be switched by. Further, when there is a constant relationship between the pressure of the exhaust gas from the gas cylinder 17 and the elapsed time, a timer is provided instead of the pressure regulator 48, and gas is passed through the bypass passage 47 immediately after the start of operation to operate. The passage may be switched so that the gas is passed through the gas return passage 16 from the time when a predetermined time has passed from the start (that is, the time when the exhaust gas pressure has dropped below the pressure on the outlet side of the compressor).

[0035]

As described above, according to the present invention, when the exhaust gas pressure from the pressure vessel is lower than the outlet side pressure during the operation of the refining compressor, the gas pressure is returned to the gas bag before the refining compressor is operated. Since the purification compressor is introduced, the existing collection gas bag is effectively used without providing any special means for controlling the pressure on the suction side of the purification compressor, and the purification compressor is always in a stable state. Can drive.
On the other hand, when the exhaust gas pressure from the pressure vessel is equal to or higher than the compressor outlet side pressure, this gas is directly supplied to the PSA device without passing through the refining compressor without reducing the pressure. Therefore, the power required for the refining compressor can be reduced by that amount, and by reducing the gas processing amount of this refining compressor, it is possible to use a compressor having a lower processing capacity than before. Therefore, there is an effect that the initial cost of the device can be reduced.

Further, according to the apparatus of the second aspect, the passage switching is automatically performed by the switching control means for detecting the pressure of the gas discharged from the pressure vessel.
There is an effect that automation of the device and further unmanned can be promoted.

Further, in the apparatus according to the third aspect, the impure gas adsorbed by the pressure swing adsorption apparatus is returned to the gas bag, so that the purification compressor upstream side due to the return of the gas. There is an effect that the pressure fluctuation is prevented, and thereby the operation state of the refining compressor can be kept more stable.

[Brief description of drawings]

FIG. 1 is a flow sheet of a helium refining device according to an embodiment of the present invention.

FIG. 2 is a flow sheet of a conventional helium refining device.

[Explanation of symbols]

 12 gas bag 16 gas return passage 18 recovery compressor 20 gas introduction passage 22 purification compressor 30 PSA device (pressure swing adsorption device) 34 separation membrane device 36 impure gas return passage 44 bypass passage 46, 47 pressure control valve (passage switching means) ) 48 pressure controller (switch control means)

Claims (3)

[Claims] 1. A gas bag in which the internal pressure is kept constant and impure helium gas is introduced, a pressure container for containing the impure helium gas in a pressurized state, and a gas derived from the gas bag for the pressure container. A recovery compressor that is press-fitted into the interior, a refining compressor that compresses the gas discharged from the pressure vessel, and a pressure swing adsorption device that adsorbs the impure components in the compressed gas and discharges the remaining high-purity helium gas. In a helium refining apparatus including: a gas return passage that connects the pressure vessel and a gas bag; a gas supply passage that connects the gas bag and an inlet side of the refining compressor; a pressure vessel and the refining compressor. And a return passage in which the gas discharged from the pressure vessel is returned to the gas bag through the gas return passage and the bypass passage connecting the outlet side of the pressure vessel and the bypass passage. A helium refining apparatus comprising: passage switching means for respectively switching the passage to a bypass state in which the discharged gas is directly guided to the outlet side of the refining compressor through the bypass passage. 2. The helium purification device according to claim 1, wherein the pressure of the gas discharged from the pressure vessel is detected,
A helium refining device provided with a switching control means for controlling the passage switching means so that the passage is switched to a bypass state when the pressure is a certain value or more and a return state when the pressure is less than the certain value. .. 3. The helium refining apparatus according to claim 1, further comprising an impure gas return passage for returning the impure gas adsorbed by the pressure swing adsorption apparatus to the gas bag. ..