TWI680791B - Purification method and purification system for helium gas - Google Patents

Abstract

The object of the present invention is to improve the recovery rate when purifying helium gas with high purity using a small-scale facility. In the adsorption towers 2a, 2b, 2c, and 2d of the pressure swing adsorption device 1, the steps of adsorption, desorption, and pressure increase are sequentially performed to adsorb the impurity gas contained in the raw material helium gas to the adsorbent. In the adsorption tower after the adsorption step and before the desorption step, the first gas blowing step of blowing the internal gas is performed, and in the adsorption tower after the desorption step and before the pressure step, the first gas of the introduced gas is carried out Import steps. The second gas blowing step of blowing the internal gas is performed in the adsorption tower after the first gas blowing step and before the desorption step, and the introduction of the blown gas is performed in the adsorption tower after the desorption step and before the first gas introducing step The second gas introduction step. The inside of the adsorption tower in the desorption step was depressurized to a subatmospheric pressure using a vacuum pump.

Description

Helium purification method and purification system

The present invention relates to a method and system for obtaining high-purity helium gas by purifying raw material helium gas containing impurity gas.

For example, helium used as a cooling liquid for MRI (Magnetic Resonance Imaging), as an ambient gas or a cooling gas in the process of forming a porous base material or the wire drawing step in the manufacture of optical fibers, is only used in the United States or countries in the Middle East It is produced as a by-product of natural gas produced overseas. In addition, it is believed that the demand for helium will also increase in the manufacturing industries of emerging countries centered on Asia. However, due to concerns about the stable supply of helium in the future, the price of helium continues to rise. In this way, since helium is highly resourced and expensive, it is useful to recycle it for reuse in the equipment used. Therefore, it is expected that the rare helium gas mixed with a large amount of impurity gases such as air is recovered as the raw material helium gas and purified with high purity.

Previously, as a method for purifying the raw material helium with high purity, the following pressure swing adsorption method (PSA method) is known: by using a pressure swing adsorption device having a plurality of adsorption towers, the impurity gas is adsorbed to the adsorption Agent, and separate from helium (see Patent Document 1). In the pressure swing adsorption method, the purification process cycle in which the following steps are carried out in sequence is performed repeatedly: an adsorption step, which allows the impurity gas contained in the raw material helium gas introduced into the adsorption tower to adsorb to the adsorbent under pressure, and Purify purified helium gas that is not adsorbed on the adsorbent; desorption step At the same time, it desorbs the impurity gas from the adsorbent and is discharged as exhaust gas; and the step of raising pressure, which raises the internal pressure of the adsorption tower.

It is known that in the pressure swing adsorption method, a decompression step for reducing the internal pressure is performed in the adsorption tower in the state after the adsorption step and before the desorption step, and at the same time in the state after the desorption step and before the pressure step In the adsorption tower, a cleaning step is performed after introducing the internal gas of the adsorption tower in the depressurization step and discharging it as exhaust gas. Also, it is known that in any of the adsorption towers in the state after the adsorption step and before the desorption step, the first gas blowing step of blowing the internal gas is performed, while being in the state after the desorption step and before the boosting step The first gas introduction step of introducing the blown internal gas is carried out in any one of the adsorption towers, and the inside of the adsorption tower in the state after the first gas blowing step and before the desorption step is carried out In the second gas blowing step of the gas, at the same time, the second gas introduction step of introducing the blown internal gas is performed in any one of the adsorption towers in the state after the desorption step and before the first gas introduction step (refer to Patent Literature 2). By introducing the internal gas of the adsorption tower for performing the gas blowing step into the interior of the adsorption tower for performing the gas introduction step, the internal pressure difference between the two adsorption towers is reduced. That is, the reduction in the internal pressure difference of the adsorption tower is carried out twice in each purification treatment cycle. In addition, it is also known to reduce the internal pressure difference of the adsorption tower three or more times in each purification treatment cycle (see Patent Document 3).

Furthermore, it is known that in the desorption step of the pressure swing adsorption method, a vacuum desorption step is performed in which the inside of the adsorption tower is depressurized to less than atmospheric pressure by a vacuum pump.

[Prior Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent No. 5372607

[Patent Document 2] US Patent No. 3564816

[Patent Document 3] Japanese Patent Laid-Open No. 52-59073

Because helium is expensive, the industry expects to increase the recovery rate when purifying the raw material helium containing impurity gas. However, according to the pressure swing adsorption method described in Patent Document 1, when helium gas is purified with high purity, helium gas discharged as exhaust gas increases, and the recovery rate of helium gas decreases.

In addition, when reducing the internal pressure difference of the adsorption tower, by introducing the internal gas of the adsorption tower after the adsorption step and before the desorption step into the adsorption tower after the desorption step and before the boosting step, the helium gas can be increased Recovery rate. However, as described in Patent Document 2, even if the internal pressure difference of the adsorption tower is repeatedly reduced in each purification process, the recovery rate cannot be sufficiently improved.

Furthermore, although the performance of the adsorbent can be restored by the vacuum desorption step and the recovery rate is improved, the degree of improvement of the recovery rate by the vacuum desorption step is small.

Therefore, according to the prior art, there is a problem that it is difficult to increase the recovery rate when purifying helium gas with high purity using a small-scale purification system. An object of the present invention is to provide a helium purification method and purification system that can solve the problems of the prior art using the pressure swing adsorption method.

The present invention is based on the following findings.

In the pressure swing adsorption method, the increase in the recovery rate using the reduction in the internal pressure difference of the adsorption tower and the increase in the recovery rate using the vacuum desorption step are respectively smaller. Therefore, it was previously thought that even if the reduction of the internal pressure difference of the adsorption tower is carried out a plurality of times and the vacuum desorption step is combined, the recovery rate will not be greatly improved. In addition, the time required for purification due to the combination increases, and the purification system becomes complicated. Therefore, it is considered that the disadvantage of increased purification cost is greater than the advantage of slightly improved recovery rate. Therefore, in the previous purification method of helium gas using the pressure swing adsorption method, the reduction of the internal pressure difference of the adsorption tower was not combined with the implementation of the vacuum desorption step.

The inventor of the present case found that under such previous technical level, such a combination of In this case, the increase in the recovery rate is greater than the increase in the recovery rate using only the reduction of the internal pressure difference of the adsorption tower and the increase in the recovery rate using the vacuum desorption step, which exerts a synergistic effect, thereby Complete the present invention.

The purification method of the helium gas of the present invention uses a pressure swing adsorption device having a plurality of adsorption towers to purify the raw material helium gas containing impurity gas. Gas adsorbent, and the above-mentioned raw material helium gas is sequentially introduced into each of the above-mentioned adsorption towers, and in each of the above-mentioned adsorption towers, the following steps are sequentially performed: an adsorption step, which causes the The impurity gas contained is adsorbed on the adsorbent under pressure, and purified helium gas that is not adsorbed on the adsorbent is discharged; a desorption step, which desorbs the impurity gas from the adsorbent and discharges it as exhaust gas; and l The pressing step causes the internal pressure to rise. The first gas blowing step of blowing the internal gas from any of the adsorption towers in the state after the adsorption step and before the desorption step is performed, and the introduction of the blown internal gas to the position after the desorption step And the first gas introduction step in any one of the adsorption towers in the state before the pressure increase step. The second gas blowing step of blowing the internal gas from any one of the adsorption towers in the state after the first gas blowing step and before the desorption step is performed, and the introduction of the blown internal gas until the desorption is performed The second gas introduction step of any one of the adsorption towers in the state after the step and before the first gas introduction step. In the above desorption step, the inside of the adsorption tower is depressurized to a subatmospheric pressure using a vacuum pump.

According to the method of the present invention, by introducing the internal gas blown from the adsorption tower in the first gas blowing step into the adsorption tower in the first gas introduction step, the internal pressure difference between the two adsorption towers is reduced. In addition, by introducing the internal gas blown from the adsorption tower in the second gas blowing step into the adsorption tower in the second gas introduction step, the internal pressure difference between the two adsorption towers is reduced. That is, the internal pressure difference of the adsorption tower can be reduced twice in each purification treatment cycle.

By reducing the internal pressure difference of the adsorption tower, the internal gas in the adsorption tower in the first and second gas blowing steps is introduced into the adsorption tower in the first and second gas introduction steps, so it can be made into the internal gas The impurity gas contained is adsorbed on the adsorbent, and the purified helium gas not adsorbed on the adsorbent is recovered. In addition, by depressurizing the inside of the adsorption tower to a subatmospheric pressure using a vacuum pump in the desorption step, a vacuum desorption step can be performed. The performance of the adsorbent can be restored by the vacuum desorption step.

That is, by performing the reduction of the internal pressure difference of the adsorption tower twice in each purification treatment cycle, and recovering the performance of the adsorbent through the vacuum desorption step, the synergistic effect can be utilized to greatly increase the recovery rate of helium.

Although the difference between the internal pressure of the adsorption tower in the first gas blowing step and the internal pressure of the adsorption tower in the first gas introduction step does not need to be eliminated at the end of the first gas blowing step and the first gas introduction step, However, this difference can be eliminated to equalize the two internal pressures. Also, the difference between the internal pressure of the adsorption tower in the second gas blowing step and the internal pressure of the adsorption tower in the second gas introduction step need not be at the end of the second gas blowing step and the second gas introduction step Eliminate, but the difference can be eliminated to equalize the two internal pressures.

The helium purification system of the present invention includes a pressure swing adsorption device having a plurality of adsorption towers, and each of the adsorption towers contains an adsorbent that adsorbs impurity gas in preference to helium. The pressure swing adsorption device includes: a raw material gas introduction flow path for introducing the raw material helium gas to each of the adsorption towers; a purified gas flow path for discharging purified helium gas from each of the adsorption towers; The gas flow path is used to discharge the exhaust gas from each of the adsorption towers; the communication flow path is used to communicate any one of the adsorption towers with the other; the raw gas is introduced into the on-off valve, which opens the above Each of the adsorption towers is individually opened and closed between the raw material gas introduction flow path; the purified gas path on-off valve, which is individually opened and closed between each of the adsorption towers and the purified gas flow path; the exhaust path on-off valve, It separately switches between each of the above adsorption towers and the exhaust gas flow path; and a communication path switching valve, which Each of the adsorption towers is individually switched between the communication channels. Each of the above-mentioned on-off valves is configured as an automatic valve having an on-off actuator so as to be able to perform an on-off operation individually, and is connected to a control device. In each of the above adsorption towers, each of the on-off valves is controlled by the control device to sequentially perform the following steps: an adsorption step that causes the impurity gas contained in the introduced raw material helium gas to be adsorbed under pressure The adsorbent, and the purified helium gas not adsorbed to the adsorbent is discharged; a desorption step, which desorbs the impurity gas from the adsorbent and is discharged as exhaust gas; and a pressure increase step, which raises the internal pressure. In order to perform the first gas blowing step of blowing the internal gas from any of the adsorption towers in the state after the adsorption step and before the desorption step, at the same time, the introduction of the blown internal gas to the desorption step The first gas introduction step of any one of the other adsorption towers in the state before and after the pressure increase step, and the interior of any one of the adsorption towers in the first gas blowing step and in the first In the gas introduction step, the internals of any one of the adsorption towers are communicated, and each of the on-off valves is controlled by the control device. In order to perform the second gas blowing step of blowing the internal gas from any of the adsorption towers in the state after the first gas blowing step and before the desorption step, at the same time, the internal gas blown into After the desorption step and before the first gas introduction step, the second gas introduction step of any one of the other adsorption towers is located inside any one of the adsorption towers of the second gas blowing step Each of the on-off valves is controlled by the control device so as to communicate with the inside of any one of the adsorption towers in the second gas introduction step. It is equipped with a vacuum pump that depressurizes the inside of the adsorption tower in the desorption step to subatmospheric pressure.

According to the inventive system, the inventive method can be implemented.

In the method of the present invention, it is preferable to increase the amount of gas blown from the adsorption tower in the first gas blowing step and introduced into the adsorption tower in the first gas introduction step to the helium of the raw material helium gas High level of concentration.

By this, due to the amount of helium introduced into the adsorption tower in the first gas introduction step The helium concentration of the raw material helium is increased to a high level, so the recovery rate of helium can be improved. Therefore, when the helium concentration of the raw material helium gas changes, for example, when the helium gas discharged from the manufacturing process of the optical fiber is used as the raw material helium gas, the concentration of the raw material gas can be flexibly responded to.

In this case, it is preferable that the system of the present invention includes a flow control valve that adjusts the flow rate of the gas flowing in the communication flow path, and the flow control valve is configured to have an actuator for flow adjustment so that the flow adjustment operation can be performed. The automatic valve of the device is connected to the control device and includes a sensor that detects the helium concentration of the raw material helium gas and is connected to the control device. The first gas blowing step and the first gas introduction step are predetermined A certain execution time is memorized in the control device, the gas from the adsorption tower in the first gas blowing step is blown and introduced into the gas in the adsorption tower in the first gas introducing step in the communication flow path The predetermined correspondence between the flow rate and the helium concentration of the raw material helium gas is memorized in the control device, so that the first gas blowing step and the first gas injection step are performed only at the execution time memorized by the control device In the gas introduction step, the on-off valve is controlled, and the opening degree of the communication flow path is changed by the flow control valve based on the correspondence relationship, so that the adsorption tower from the first gas blowing step is blown and introduced to the 1 The amount of gas in the adsorption tower in the gas introduction step is increased to a level as high as the helium concentration detected by the sensor.

Alternatively, it is preferable that the system of the present invention includes a sensor that detects the helium concentration of the raw material helium gas and is connected to the control device, the execution time of the first gas blowing step and the first gas introduction step, and the raw material helium gas The predetermined correspondence between the helium concentrations in is stored in the control device, and the control device is used to change the execution time of the first gas blowing step and the first gas introduction step based on the correspondence so that The adsorption tower in the first gas blowing step is blown and introduced into the adsorption tower in the first gas introduction step to increase the amount of gas to the sensor The detected helium concentration is as high as it is.

In the method of the present invention, preferably, in any of the adsorption towers in a state after the first gas blowing step and before the second gas blowing step, a decompression step for reducing the internal pressure is performed while In any one of the adsorption towers in the state after the desorption step and before the second gas introduction step, washing performed by introducing the internal gas of the adsorption tower in the depressurization step and discharging it as exhaust gas Net steps.

In this case, it is preferable that the system of the present invention uses the control device to control each of the on-off valves so that any one of the adsorption towers is in a state after the first gas blowing step and before the second gas blowing step Among them, the decompression step for reducing the internal pressure is performed, and at the same time, in any one of the adsorption towers in the state after the desorption step and before the second gas introduction step, the decompression step is carried out The washing step of exhausting the internal gas of the adsorption tower as exhaust gas.

In the method of the present invention, it is preferable to reduce the amount of gas blown from the adsorption tower in the depressurization step and introduced into the adsorption tower in the cleaning step to as high as the helium concentration of the raw material helium gas degree. Further preferably, when the helium concentration of the raw material helium gas is more than a predetermined set value, the washing step is not performed.

By this, the amount of helium gas discharged as exhaust gas after washing the inside of the adsorption tower is reduced to a level as high as the helium concentration of the raw material helium gas, so the recovery rate of helium gas can be improved. Therefore, when the helium concentration of the raw material helium gas changes, for example, when the helium gas discharged from the manufacturing process of the optical fiber is used as the raw material helium gas, the concentration of the raw material gas can be flexibly responded to.

In this case, it is preferable that the system of the present invention uses the control device to control each of the on-off valves so that any one of the adsorption towers is in a state after the first gas blowing step and before the second gas blowing step Among them, the decompression step for reducing the internal pressure is performed, and at the same time, in any one of the adsorption towers in the state after the desorption step and before the second gas introduction step, the decompression step is carried out Suction above A cleaning step of exhausting the internal gas in the tower and exhausting it as exhaust gas, and including a flow control valve that adjusts the flow rate of the gas flowing in the communication channel, and the flow control valve is set to have a flow adjustment operation An automatic valve for an actuator for flow rate adjustment, which is connected to the control device and is provided with a sensor which detects the helium concentration of the raw material helium gas and is connected to the control device, and a predetermined certain execution time of the cleaning step It is memorized in the control device, the flow rate of the gas in the communication flow path from the adsorption tower in the depressurization step and the introduction to the adsorption tower in the washing step, and the flow rate of the raw material helium gas The predetermined correspondence between the helium concentrations is memorized in the control device, the on-off valve is controlled to execute the washing step only at the execution time memorized by the control device, and the flow rate is used based on the correspondence The control valve changes the opening degree of the communication flow path so that the amount of gas that is blown from the adsorption tower in the depressurization step and introduced into the adsorption tower in the cleaning step is reduced to be detected by the sensor As high as the helium concentration.

Alternatively, it is preferable that each of the on-off valves is controlled by the control device so that any of the adsorption towers in a state after the first gas blowing step and before the second gas blowing step is to reduce the internal The depressurization step of the pressure is carried out at the same time in any of the adsorption towers in the state after the desorption step and before the second gas introduction step, by introducing the internal gas of the adsorption tower in the decompression step A cleaning step that is discharged as exhaust gas and is provided with a sensor that detects the helium concentration of the raw material helium gas and is connected to the control device, and the execution time of the cleaning step is between the helium concentration in the raw material helium gas The predetermined correspondence relationship is stored in the control device, and the control device is used to change the execution time of the washing step based on the correspondence relationship, so that the adsorption tower from the decompression step is blown and introduced to the above The amount of gas in the adsorption tower in the washing step is reduced to a level as high as the helium concentration detected by the sensor.

In the method of the present invention, it is preferred that each of the raw material helium gas flows to the adsorption tower. The exhaust gas is introduced into the introduction flow path to reuse the exhaust gas as the raw material helium gas. By this, the helium gas contained in the exhaust gas can be reused, so the recovery rate can be improved. In this case, it is preferable that the system of the present invention includes a reuse flow path for connecting the exhaust gas flow path and the raw material gas introduction flow path.

In the method of the present invention, it is preferable to set the helium concentration of the raw material helium gas introduced into each of the adsorption towers to 15 vol% or more. By this, the waste of helium gas can be reduced and the target purity helium gas can be efficiently obtained. In addition, regarding the helium concentration of the raw material helium gas, when mixed with the recycled exhaust gas, the mixed helium is introduced into the pressure swing adsorption device, so if the mixing is 15 vol% or more, the invention can be used Method to efficiently obtain helium with target purity.

In the method of the present invention, it is preferable to set the pressure swing type adsorption device so that the helium concentration of the purified helium gas discharged from each of the adsorption towers in the adsorption step becomes a target purity, for example, 99.999 vol% or more. The repetition interval of the adsorption step. Furthermore, in order to obtain high-purity helium gas, the adsorption using the pressure swing adsorption device can also be set such that the helium concentration of the purified helium gas discharged from each of the adsorption towers in the adsorption step becomes 99.9999 vol% or more Steps are repeated at intervals.

According to the present invention, it is possible to provide a method and system that can help to improve the recovery rate of helium gas when purifying helium gas containing impurities with high purity by using small-scale equipment.

1‧‧‧ Pressure swing adsorption device

2a‧‧‧Adsorption tower

2a'‧‧‧gas through port

2a"‧‧‧gas through port

2b‧‧‧Adsorption tower

2b'‧‧‧gas through port

2b"‧‧‧gas through port

2c‧‧‧Adsorption tower

2c'‧‧‧gas through port

2c"‧‧‧gas through port

2d‧‧‧adsorption tower

2d'‧‧‧gas through port

2d"‧‧‧gas through port

3‧‧‧ Raw material gas introduction piping (source gas introduction flow path)

4‧‧‧Purified gas piping (purified gas flow path)

5‧‧‧Exhaust piping (exhaust flow path)

6a‧‧‧The first on-off valve (on-off valve of raw material gas introduction path)

6b‧‧‧Second on-off valve (on-off valve for feed gas introduction)

6c‧‧‧ 3rd on-off valve (on-off valve for feed gas inlet)

6d‧‧‧ 4th on-off valve (on-off valve for feed gas inlet)

7a‧‧‧The fifth on-off valve (purified gas circuit on-off valve)

7b‧‧‧Sixth on-off valve (purified gas on-off valve)

7c‧‧‧ 7th on-off valve (purified gas circuit on-off valve)

7d‧‧‧ 8th on-off valve (purified gas circuit on-off valve)

8a‧‧‧ 9th on-off valve (exhaust on-off valve)

8b‧‧‧10th on-off valve (exhaust on-off valve)

8c‧‧‧Eleventh on-off valve (exhaust on-off valve)

8d‧‧‧12th on-off valve (exhaust on-off valve)

9‧‧‧Connecting piping (connecting flow path)

9a‧‧‧The first connection

9b‧‧‧The second connection

9c‧‧‧The third connection

9d‧‧‧The fourth connection

10a‧‧‧th thirteenth on-off valve (communicating on-off valve)

10b‧‧‧14th on-off valve (communicating on-off valve)

10c‧‧‧The 15th on-off valve (communicating on-off valve)

10d‧‧‧16th on-off valve (communicating on-off valve)

11a‧‧‧17th on-off valve (communicating on-off valve)

11b‧‧‧18th on-off valve (communicating on-off valve)

11c‧‧‧19th on-off valve (communicating on-off valve)

11d‧‧‧20th on-off valve (communicating on-off valve)

12a‧‧‧21st on-off valve (communicating on-off valve)

12b‧‧‧22th on-off valve (communicating on-off valve)

12c‧‧‧ 23rd on-off valve (communicating on-off valve)

12d‧‧‧24th on-off valve (communicating on-off valve)

14‧‧‧25th on-off valve (communicating on-off valve)

15‧‧‧The first flow control valve

16‧‧‧26th on-off valve (communicating on-off valve)

17‧‧‧ 2nd flow control valve

18‧‧‧ Third flow control valve

20‧‧‧Control device

21‧‧‧Flow sensor

22‧‧‧Buffer tank

22a‧‧‧Storage sensor

23‧‧‧Compressor

24‧‧‧Concentration sensor

25‧‧‧ 4th flow control valve

26‧‧‧pressure regulating valve

27a‧‧‧pressure sensor

27b‧‧‧pressure sensor

27c‧‧‧pressure sensor

27d‧‧‧pressure sensor

28‧‧‧Input device

29‧‧‧Output device

41‧‧‧The first reuse piping (reuse flow path)

42‧‧‧First switching valve

43‧‧‧The second reuse piping (reuse flow path)

44‧‧‧The first release piping

44'‧‧‧ 2nd release piping

45‧‧‧ 2nd switching valve

46‧‧‧The third reuse piping (reuse flow path)

47‧‧‧ 4th reuse piping (reuse flow path)

48‧‧‧ Third switching valve

49‧‧‧The fifth reuse piping (reuse flow path)

50‧‧‧Vacuum pump

G1‧‧‧raw material helium

G2‧‧‧Purified helium

G3‧‧‧Exhaust

G3'‧‧‧Exhaust

G4‧‧‧gas

G4'‧‧‧Internal gas

α‧‧‧Purification system

FIG. 1 is an explanatory diagram of the structure of a purification system according to an embodiment of the present invention.

2 is an explanatory diagram of the structure of a pressure swing type adsorption device according to an embodiment of the present invention.

3 is an explanatory diagram of a control device of a purification system according to an embodiment of the present invention.

4A is a diagram showing the operating states (a) to (e) of the pressure swing adsorption device according to the embodiment of the present invention.

4B is a diagram showing the operating state (f) of the pressure swing adsorption device according to an embodiment of the present invention. Figure of ~(j).

4C is a diagram showing the operating states (k) to (o) of the pressure swing adsorption device according to the embodiment of the present invention.

4D is a diagram showing the operating states (p) to (t) of the pressure swing adsorption device according to the embodiment of the present invention.

FIG. 5A is a diagram showing the correspondence between the purification process steps in the adsorption towers under the operating states (a) to (e) of the pressure swing adsorption device according to the embodiment of the present invention and the state of the on-off valve.

5B is a diagram showing the correspondence between the purification process steps in the adsorption towers under the operating conditions (f) to (j) of the pressure swing adsorption device according to the embodiment of the present invention and the state of the on-off valve.

5C is a diagram showing the correspondence between the purification process steps and the state of the on-off valve in the adsorption towers in the operating states (k) to (o) of the pressure swing adsorption device according to the embodiment of the present invention.

FIG. 5D is a diagram showing the correspondence between the purification process steps and the state of the on-off valve in each of the adsorption towers in the operating states (p) to (t) of the pressure swing adsorption device according to the embodiment of the present invention.

The helium purification system α of the embodiment of the present invention shown in FIG. 1 includes a pressure swing type adsorption device 1 for purifying a raw material helium gas G1 containing an impurity gas. As shown in FIG. 2, the pressure swing adsorption apparatus 1 has a plurality of adsorption towers 2a, 2b, 2c, and 2d. In this embodiment, the first to fourth adsorption towers 2a, 2b, 2c, 2d are provided, and gas passage ports 2a', 2b' are formed at one end and the other end of each adsorption tower 2a, 2b, 2c, 2d, 2c', 2d', 2a", 2b", 2c", 2d".

In each adsorption tower 2a, 2b, 2c, and 2d, an adsorbent that adsorbs impurity gas in preference to helium gas is stored. As long as the adsorbent is capable of adsorbing impurity gases in preference to helium, there is no Specifically limited, for example, activated carbon, synthetic zeolite, carbon molecular sieve, alumina gel, etc. can be used.

As shown in FIG. 2, the raw material gas introduction piping 3, the purified gas piping 4, and the exhaust piping 5 are connected to each of the adsorption towers 2a, 2b, 2c, and 2d.

One end of the raw material gas introduction piping 3 is connected to a supply source of raw material helium gas G1, for example, an optical fiber manufacturing apparatus. The other end of the raw material gas introduction piping 3 is branched toward the first to fourth adsorption towers 2a, 2b, 2c, 2d, and passes through the first to fourth on-off valves 6a, 6b constituting the on-off valve of the raw gas introduction path , 6c, 6d, and the gas at one end of each of the adsorption towers 2a, 2b, 2c, 2d is connected through the ports 2a', 2b', 2c', 2d'. Thereby, the raw material gas introduction piping 3 constitutes a raw material gas introduction flow path for introducing the raw material helium gas G1 to each of the adsorption towers 2a, 2b, 2c, and 2d. Moreover, each of the adsorption towers 2a, 2b, 2c, 2d and the raw material gas introduction flow path are individually switched by the first to fourth on-off valves 6a, 6b, 6c, 6d, whereby the raw material gas can be passed The introduction flow path individually introduces the raw material helium gas G1 to each of the adsorption towers 2a, 2b, 2c, and 2d.

The raw material helium gas G1 is a mixed gas of helium gas and impurity gas. The helium concentration of the raw material helium gas G1 introduced into each of the adsorption towers 2a, 2b, 2c, and 2d is preferably 15 vol% or more. In the present embodiment, the raw material helium gas G1 supplied from the supply source is defined as a one whose concentration and flow rate vary. For example, the raw material helium gas G1 is a thin helium gas containing air as an impurity gas. When the helium concentration is 30 vol%, the air concentration is 70 vol%, the helium concentration varies from 15 to 70 vol%, and the helium flow rate is 10 to 100 Nm ³ Change between /h.

One end of the purified gas piping 4 is branched toward the first to fourth adsorption towers 2a, 2b, 2c, and 2d, and passes through the fifth to eighth switching valves 7a, 7b, and 7c that constitute the purified gas path switching valve. 7d, the gas at the other end of each of the adsorption towers 2a, 2b, 2c, 2d is connected through the ports 2a", 2b", 2c", 2d". The other end of the purified gas piping 4 is set as the outlet of the purified helium gas G2. Thereby, the purified gas piping 4 constitutes a purified gas flow path for discharging the purified helium gas G2 from each of the adsorption towers 2a, 2b, 2c, and 2d. Also, with the 5th to 8th on-off valves 7a, 7b, 7c, 7d, each of the adsorption towers 2a, 2b, 2c, 2d and the purified gas flow path are individually switched, whereby each of the adsorption towers 2a, 2b, 2c, 2d can be discharged individually The helium gas G2 is purified and recovered. The use of the recovered purified helium gas G2 is not limited.

A pressure regulating valve 26 for back pressure regulation is provided at the other end of the purified gas piping 4, whereby the internal pressure in each of the adsorption towers 2a, 2b, 2c, 2d can be adjusted to the adsorption determined in advance in the adsorption step pressure.

One end of the exhaust pipe 5 is branched toward the first to fourth adsorption towers 2a, 2b, 2c, and 2d, and passes through the ninth to twelfth switching valves 8a, 8b, and 8c that constitute the exhaust path switching valve. 8d is connected to the gas through the ports 2a', 2b', 2c', 2d'. The other end of the exhaust pipe 5 is set as the outlet of the exhaust gas G3, G3'. Thereby, the exhaust piping 5 constitutes an exhaust flow path for exhausting the exhaust gas G3, G3' from each of the adsorption towers 2a, 2b, 2c, 2d. In addition, the ninth to twelfth on-off valves 8a, 8b, 8c, and 8d are used to individually switch the adsorption towers 2a, 2b, 2c, and 2d and the exhaust gas flow path, thereby enabling self-adsorption tower 2a , 2b, 2c, and 2d individually exhaust the exhaust gases G3, G3'.

The first reuse pipe 41 connected to the exhaust pipe 5 is provided with a third flow control valve 18 for flow adjustment. With this, the internal pressure in each of the adsorption towers 2a, 2b, 2c, and 2d can be adjusted to the set pressure. In addition, in the discharge pressure desorption step, it can be adjusted such that the exhaust gas G3 has a predetermined pressure.

There is provided a communication pipe 9 that constitutes a communication flow path that allows any one of the adsorption towers 2a, 2b, 2c, and 2d to communicate with each other. The communication pipe 9 has a first communication portion 9a, a second communication portion 9b, a third communication portion 9c, and a fourth communication portion 9d. One end of the first communication portion 9a is divided into four branches toward the first to fourth adsorption towers 2a, 2b, 2c, and 2d, and passes through the thirteenth to sixteenth on-off valves 10a, 10b, and 10c constituting the on-off valve of the communication path. 10d is connected to the gas through the ports 2a", 2b", 2c", 2d". One end of the second communication portion 9b is divided into four branches so as to face the first to fourth adsorption towers 2a, 2b, 2c, and 2d, and passes through the 17th to 20th switching valves 11a, 11b, and 11c that constitute the communication path switching valve. 11d and gas through the port 2a", 2b", 2c", 2d" connection. One end of the third communication portion 9c is branched toward the first to fourth adsorption towers 2a, 2b, 2c, and 2d, and passes through the 21st to 24th switching valves 12a, 12b, 12c, and 12d are connected to the gas passage ports 2a", 2b", 2c", and 2d". The other end of the second communication portion 9b and the other end of the third communication portion 9c pass through the 25th The on-off valve 14 and the first flow control valve 15 that constitutes the flow control valve that regulates the flow rate of the gas flowing in the communication channel are connected to each other. One end of the fourth communication portion 9d passes through the 26th switching valve 16 that constitutes the communication channel on-off valve And a second flow control valve 17 constituting a flow control valve that regulates the flow rate of the gas flowing in the communication channel is connected to the other end of the first communication portion 9a. The other end of the fourth communication portion 9d is connected to the purified gas piping 4 Therefore, the adsorption towers 2a, 2b, 2c, 2d will be replaced by the 13th to 26th switching valves 10a, 10b, 10c, 10d, 11a, 11b, 11c, 11d, 12a, 12b, 12c, 12d, 14, 16 Switching between each of them and the communication channel individually can switch any one of the adsorption towers 2a, 2b, 2c, 2d and any other into an open and mutually connected state, and each other The room is closed but not connected.

1st to 26th on-off valves 6a, 6b, 6c, 6d, 7a, 7b, 7c, 7d, 8a, 8b, 8c, 8d, 10a, 10b, 10c, 10d, 11a, 11b, 11c, 11d, 12a, 12b Each of 12c, 12d, 14, 16 includes a well-known automatic valve, and has a switching actuator such as a solenoid and a motor for actuating the valve. As shown in FIG. 3, each on-off valve is connected to the control device 20 constituting the purification system α, and is controlled by the control device 20, whereby the switching operation can be performed individually. The control device 20 may include a computer.

Each of the first, second, and third flow control valves 15, 17, and 18 includes a known automatic valve, and has an actuator for adjusting the flow rate such as a motor for actuating the valve. As shown in FIG. 3, each flow control valve is connected to the control device 20 and controlled by the control device 20, whereby the flow adjustment operation can be individually performed. The pressure regulating valve 26 includes a known automatic valve, and has a pressure regulating actuator such as a motor for actuating the valve. As shown in FIG. 3, the pressure regulating valve 26 is connected to the control device 20 and controlled by the control device 20, whereby the pressure can be adjusted individually action.

The raw material gas introduction piping 3 is provided with: a flow sensor 21 which detects the flow rate of the raw material helium gas G1 supplied from the supply source; a buffer tank 22 which temporarily stores the raw material helium gas G1; and a sensor 22a which is For storage capacity measurement of the buffer tank 22; compressor 23; concentration sensor 24, which detects the helium concentration of the raw material helium gas G1 introduced into the adsorption towers 2a, 2b, 2c, 2d; and the fourth flow control valve 25, It is used to adjust the flow rate of the raw material helium gas G1 introduced from the raw material gas introduction pipe 3 to each adsorption tower 2a, 2b, 2c, 2d. The inside of the buffer tank 22 is set to a pressure lower than the internal pressure of each adsorption tower 2a, 2b, 2c, 2d at the end of the discharge pressure desorption step and the end of the washing step and above atmospheric pressure. The compressor 23 sucks the raw material helium gas G1 and boosts it to a predetermined pressure, for example, 0.8 to 0.9 MPa (gauge pressure). The temperature of the raw material helium gas G1 introduced into each of the adsorption towers 2a, 2b, 2c, and 2d is, for example, 0 to 40°C. The fourth flow control valve 25 includes a known automatic valve, and has an actuator for adjusting the flow rate such as a motor for actuating the valve.

One end of the first reuse pipe 41 is connected to the exhaust pipe 5, and the other end of the first reuse pipe 41 is connected to the first switching valve 42. The first switching valve 42 selectively connects the first reuse pipe 41 to one end of the second reuse pipe 43 and one end of the first discharge pipe 44. The other end of the first release piping 44 communicates with the atmospheric space under atmospheric pressure. The other end of the second reuse pipe 43 is connected to the second switching valve 45. The second switching valve 45 selectively connects the second reuse pipe 43 to one end of the third reuse pipe 46 and one end of the fourth reuse pipe 47. The other end of the third reuse pipe 46 is connected to the buffer tank 22. The other end of the fourth reuse pipe 47 is connected to the third switching valve 48. The third switching valve 48 selectively connects the fourth reuse pipe 47 to one end of the fifth reuse pipe 49 and one end of the second discharge pipe 44'. The other end of the fifth reuse pipe 49 is connected to the buffer tank 22, and the other end of the second release pipe 44' communicates with the atmospheric space under atmospheric pressure. A vacuum pump 50 is provided in the middle of the fourth reuse piping 47. In this way, the first to third switching valves 42, 45, and 48 can be used to switch the exhaust gas flow path to the state of communicating with the buffer tank 22 without passing through the vacuum pump 50, and the communication with the buffer tank 22 via the vacuum pump 50. The state, the state of communicating with the normal pressure space through the first release pipe 44, and the state of communicating with the normal pressure space through the second release pipe 44 ′. In addition, the first to third switching valves may be automatic valves connected to the control devices 20 of 42, 45, and 48, and the control device 20 may control the operation. In addition, the vacuum pump 50 may be connected to the control device 20, and the control device 20 may control the operation.

The first to fifth reuse pipes 41, 43, 46, 47, and 49 constitute a reuse flow path for connecting the raw material gas introduction flow path through the exhaust flow path buffer tank 22. Thereby, the exhaust gas G3, G3' can be introduced into the introduction flow path of the raw material helium gas G1 to each of the adsorption towers 2a, 2b, 2c, 2d, and the exhaust gas G3, G3' can be mixed into the raw material helium gas G1 . That is, the exhaust gas G3, G3' can be reused as the raw material helium gas G1. Exhaust gas G3, G3' can also be released to atmospheric space.

As shown in FIG. 3, the flow rate sensor 21, the storage amount measurement sensor 22 a, the concentration sensor 24, and the fourth flow rate control valve 25 are connected to the control device 20. In addition, a pressure sensor 27a, 27b, 27c, 27d, an input device 28 such as a keyboard, and an output device 29 such as a monitor are connected to the control device 20 to detect the internal pressure of each of the adsorption towers 2a, 2b, 2c, and 2d.

By temporarily storing the raw material helium gas G1 in the buffer tank 22, the composition change and the flow rate change of the raw material helium gas G1 can be alleviated. The buffer tank 22 preferably includes a balloon deformed according to the amount of stored gas to make the capacity variable. In addition, the fourth flow control valve 25 is controlled by a signal from the control device 20 to perform a flow adjustment operation to adjust the flow rate of the raw material helium gas G1 introduced into each adsorption tower 2a, 2b, 2c, and 2d. As a result, the flow rate of the raw material helium gas G1 introduced into the adsorption towers 2a, 2b, 2c, and 2d is normally controlled to be consistent with the detection flow rate of the flow sensor 21. When the amount of stored gas in the buffer tank 22 detected by the sensor 22a exceeds the upper limit setting value, the raw material helium gas G1 introduced into each adsorption tower 2a, 2b, 2c, 2d is reduced The flow rate is set to be more than the flow rate detected by the flow sensor 21. When the amount of stored gas in the buffer tank 22 detected by the sensor 22a does not reach the lower limit setting value, the raw material helium gas introduced into each adsorption tower 2a, 2b, 2c, 2d is increased The flow rate of G1 is set to be less than the detection of the flow sensor 21 Trafficker.

In order to purify the raw material helium gas G1 using the pressure swing adsorption apparatus 1, the raw material helium gas G1 is introduced to each of the adsorption towers 2a, 2b, 2c, and 2d in order. In each of the adsorption towers 2a, 2b, 2c, and 2d, a purification process cycle in which a plurality of purification process steps are sequentially performed is repeatedly performed.

In this embodiment, as a plurality of purification processing steps constituting one cycle of the purification processing cycle in the pressure swing adsorption apparatus 1, the adsorption step, the first gas blowing step, the depressurizing step, and the second gas blowing are sequentially performed Step, desorption step, cleaning step, second gas introduction step, first gas introduction step, and pressure increase step. The desorption step of the present embodiment is a discharge pressure desorption step and a vacuum desorption step, but it may also be a vacuum desorption step. In the present embodiment, a standby state is provided between the second gas introduction step and the first gas introduction step, but the standby state may not exist according to the time required for each step. The execution time of each purification treatment step may be determined in advance through experiments and set according to the required purity or recovery rate of the purified helium gas G2. The purification treatment steps in each of the adsorption towers 2a, 2b, 2c, and 2d are performed at different time points. In this way, in the pressure swing adsorption device 1, as shown in FIGS. 4A to 4D, the operation states (a) of the purification treatment steps in each of the adsorption towers 2a, 2b, 2c, and 2d are different from each other in sequence (a) to ( t), and continuously purify the purified helium gas G2. The arrows in FIGS. 4A-4D indicate the direction of gas flow.

In the pressure swing adsorption device 1, in order to sequentially perform the purification process, the control device 20 controls the first to 26th on-off valves 6a, 6b, 6c, 6d, 7a, 7b, 7c, 7d, 8a, 8b , 8c, 8d, 10a, 10b, 10c, 10d, 11a, 11b, 11c, 11d, 12a, 12b, 12c, 12d, 14, 16, first and second flow control valves 15, 17. 5A to 5D show the purification process steps and the 1st to 26th switches performed in each of the adsorption towers 2a, 2b, 2c, and 2d in the operating state (a) to (i) of the pressure swing adsorption device 1. Correspondence between the states of the valves, the ○ symbol indicates the open state of the on-off valve, and the X symbol indicates the closed state of the on-off valve.

In the operating state (a), the 1st, 5th, 11th, 18th, 24th, 25th on-off valves 6a, 7a, 8c, 11b, 12d, 14 are opened, and the remaining on-off valves are closed. When the first and fifth on-off valves 6a and 7a are opened, the adsorption step is performed in the first adsorption tower 2a. When the 11th, 24th, and 25th on-off valves 11b, 12d, and 14 are opened, the first gas introduction step is performed in the second adsorption tower 2b, and the first gas blowing step is performed in the fourth adsorption tower 2d. When the 18th on-off valve 8c is opened, the desorption step is performed in the third adsorption tower 2c. Here, the third adsorption tower 2c is set to communicate with the vacuum pump 50, and the desorption step in the third adsorption tower 2c is set to a vacuum desorption step.

In the operating state (b), the first, fifth, eleventh, fourteenth, nineteenth, twenty-fourth, twenty-fifth, twenty-sixth on-off valves 6a, 7a, 8c, 10b, 11c, 12d, 14, 16 are opened , The rest of the on-off valve is closed. The first, fifth, 14th, and 26th on-off valves 6a, 7a, 10b, and 16 are opened, and the adsorption step is performed after the first adsorption tower 2a is in the relay operation state (a), and in the second adsorption tower 2b. The step-up step is carried out. When the 11th, 19th, 24th, and 25th on-off valves 8c, 11c, 12d, and 14 are opened, a washing step is performed in the third adsorption tower 2c, and a depressurization step is performed in the fourth adsorption tower 2d. Here, the third adsorption tower 2c is set to communicate with the vacuum pump 50, and the exhaust gas G3′ discharged in the washing step is sucked by the vacuum pump 50.

In the operating state (c), the first, fifth, 14th, 19th, 24th, 25th, 26th on-off valves 6a, 7a, 10b, 11c, 12d, 14, 16 are opened, and the remaining on-off valves is closed. The first, fifth, 14th, and 26th on-off valves 6a, 7a, 10b, and 16 are opened, and the adsorption step is performed after the first adsorption tower 2a is in the relay operation state (b), and in the second adsorption tower 2b. After the relay operation state (b), a step-up step is performed. When the 19th, 24th, and 25th on-off valves 11c, 12d, and 14 are opened, the second gas introduction step is performed in the third adsorption tower 2c, and the second gas blowing step is performed in the fourth adsorption tower 2d. Here, since the vacuum pump 50 is unnecessary, it may be stopped.

In the operating state (d), the first, fifth, twelfth, fourteenth, and twenty-sixth on-off valves 6a, 7a, 8d, 10b, and 16 are opened, and the remaining on-off valves are closed. The first, fifth, 14th, and 26th on-off valves 6a, 7a, 10b, and 16 are opened, and relay operation is performed on the first adsorption tower 2a. After the state (c), the adsorption step is performed, and after the second adsorption tower 2b relay operation state (c), the boosting step is performed. The third adsorption tower 2c is set to a standby state without performing any purification process steps. By opening the 12th on-off valve 8d, the desorption step is performed in the 4th adsorption tower 2d. The fourth adsorption tower 2d is assumed not to communicate with the vacuum pump 50, and the desorption step in the fourth adsorption tower 2d is assumed to be a discharge pressure desorption step. Here, since the vacuum pump 50 is unnecessary, it may be stopped.

In the operating state (e), the switching state of the on-off valve is set to be the same as the operating state (d). By this, the adsorption step is performed after the relay operation state (d) of the first adsorption tower 2a, and the boosting step is performed after the relay operation state (d) of the second adsorption tower 2b, and the third adsorption tower 2c is set to standby status. Unlike the operating state (d), in the operating state (e), the fourth adsorption tower 2d is set to communicate with the vacuum pump 50, and the desorption step in the fourth adsorption tower 2d is set to a vacuum desorption step.

In the operating state (f), the second, sixth, twelfth, nineteenth, twenty-first, and twenty-fifth on-off valves 6b, 7b, 8d, 11c, 12a, 14 are opened, and the remaining on-off valves are closed. When the second and sixth on-off valves 6b and 7b are opened, the adsorption step is performed in the second adsorption tower 2b. When the 19th, 21st, and 25th on-off valves 11c, 12a, and 14 are opened, the first gas blowing step is performed in the first adsorption tower 2a, and the first gas introduction step is performed in the third adsorption tower 2c. By opening the 12th on-off valve 8d, the desorption step is performed in the 4th adsorption tower 2d. Here, the desorption step in the fourth adsorption tower 2d following the operation state (e) is a vacuum desorption step.

In the operating state (g), the 2nd, 6th, 12th, 15th, 20th, 21st, 25th, 26th on-off valves 6b, 7b, 8d, 10c, 11d, 12a, 14, 16 are opened , The rest of the on-off valve is closed. By the second, sixth, fifteenth, and twenty-sixth on-off valves 6b, 7b, 10c, and 16 being opened, the adsorption step is performed after the second adsorption tower 2b relay operation state (f), and the third adsorption tower 2c The step-up step is carried out. When the 12th, 20th, 21st, and 25th on-off valves 8d, 11d, 12a, and 14 are opened, a decompression step is performed in the first adsorption tower 2a, and a washing step is performed in the fourth adsorption tower 2d. Here, the fourth adsorption tower 2d is set to be in phase with the vacuum pump 50 In general, the exhaust gas G3′ discharged in the washing step is attracted by the vacuum pump 50.

In the operating state (h), the 2nd, 6th, 15th, 20th, 21st, 25th, 26th on-off valves 6b, 7b, 10c, 11d, 12a, 14, 16 are opened, the remaining on-off valves is closed. By the second, sixth, fifteenth, and twenty-sixth on-off valves 6b, 7b, 10c, and 16 being opened, the adsorption step is performed after the second adsorption tower 2b is in the relay operation state (g), and in the third adsorption tower 2c After the relay operation state (g), a step-up step is performed. When the 20th, 21st, and 25th on-off valves 11d, 12a, and 14 are opened, the second gas blowing step is performed in the first adsorption tower 2a, and the second gas introduction step is performed in the fourth adsorption tower 2d. Here, since the vacuum pump 50 is unnecessary, it may be stopped.

In the operating state (i), the second, sixth, ninth, fifteenth, and twenty-sixth on-off valves 6b, 7b, 8a, 10c, and 16 are opened, and the remaining on-off valves are closed. By the second, sixth, fifteenth, and twenty-sixth on-off valves 6b, 7b, 10c, and 16 being opened, the adsorption step is performed after the second adsorption tower 2b relay operation state (h), and in the third adsorption tower 2c After the relay operation state (h), the step-up step is performed. When the ninth switching valve 8a is opened, the desorption step is performed in the first adsorption tower 2a. The first adsorption tower 2a is not connected to the vacuum pump 50, and the desorption step in the first adsorption tower 2a is a discharge pressure desorption step. Here, since the vacuum pump 50 is unnecessary, it may be stopped. The fourth adsorption tower 2d is set to the standby state.

In the operating state (j), the switching state of the on-off valve is set to be the same as the operating state (h). By this, the adsorption step is performed after the relay operation state (h) of the second adsorption tower 2b, and the boosting step is performed after the relay operation state (h) of the third adsorption tower 2c, and the fourth adsorption tower 2d is set to standby status. Unlike the operating state (h), in the operating state (j), the first adsorption tower 2a is set to communicate with the vacuum pump 50, and the desorption step in the first adsorption tower 2a is set to a vacuum desorption step.

In the operating state (k), the third, seventh, ninth, 20th, 22nd, and 25th on-off valves 6c, 7c, 8a, 11d, 12b, 14 are opened, and the remaining on-off valves are closed. When the third and seventh on-off valves 6c and 7c are opened, the adsorption step is performed in the third adsorption tower 2c. By The 20th, 22nd, and 25th on-off valves 11d, 12b, and 14 are opened, the first gas blowing step is performed in the second adsorption tower 2b, and the first gas introduction step is performed in the fourth adsorption tower 2d. When the ninth switching valve 8a is opened, the desorption step is performed in the first adsorption tower 2a. Here, the desorption step in the first adsorption tower 2a following the operation state (j) is a vacuum desorption step.

In the operating state (l), the 3rd, 7th, 9th, 16th, 17th, 22nd, 25th, 26th on-off valves 6c, 7c, 8a, 10d, 11a, 12b, 14, 16 are opened , The rest of the on-off valve is closed. By the 3rd, 7th, 16th, and 26th on-off valves 6c, 7c, 10d, and 16 being opened, the adsorption step is performed after the relay operation state (k) of the third adsorption tower 2c, and on the fourth adsorption tower 2d The step-up step is carried out. When the 9th, 17th, 22nd, and 25th on-off valves 8a, 11a, 12b, and 14 are opened, a washing step is performed in the first adsorption tower 2a, and a depressurization step is performed in the second adsorption tower 2d. Here, the first adsorption tower 2a is set to communicate with the vacuum pump 50, and the exhaust gas G3' discharged in the washing step is sucked by the vacuum pump 50.

In the operating state (m), the 3rd, 7th, 16th, 17th, 22nd, 25th, 26th on-off valves 6c, 7c, 10d, 11a, 12b, 14, 16 are opened, and the remaining on-off valves is closed. By opening the third, seventh, sixteenth, and twenty-sixth on-off valves 6c, 7c, 10d, and 16 and performing the adsorption step after the relay operation state (l) of the third adsorption tower 2c, in the fourth adsorption tower 2c Following the operating state (1), a step-up step is performed. When the 17th, 22nd, and 25th on-off valves 11a, 12b, and 14 are opened, the second gas introduction step is performed in the first adsorption tower 2a, and the second gas blowing step is performed in the second adsorption tower 2b. Here, since the vacuum pump 50 is unnecessary, it may be stopped.

In the operating state (n), the third, seventh, tenth, sixteenth, and twenty-sixth on-off valves 6c, 7c, 8b, 10d, and 16 are opened, and the remaining on-off valves are closed. By the 3rd, 7th, 16th, and 26th on-off valves 6c, 7c, 10d, and 16 being opened, the adsorption step is performed after the third adsorption tower 2c relay operation state (m), and the fourth adsorption tower 2d After the relay operation state (m), the step-up step is performed. When the tenth switching valve 8b is opened, the desorption step is performed in the second adsorption tower 2b. The second adsorption tower 2b is set not to communicate with the vacuum pump 50, and the second adsorption tower 2b is removed The attachment step is set as the discharge pressure desorption step. Here, since the vacuum pump 50 is unnecessary, it may be stopped. The first adsorption tower 2d is set to a standby state.

In the operating state (o), the switching state of the on-off valve is set to be the same as the operating state (n). By this, the adsorption step is performed after the relay operation state (n) of the third adsorption tower 2c, and the boosting step is performed after the relay operation state (n) of the fourth adsorption tower 2d, and the first adsorption tower 2a is set to standby status. Unlike the operating state (n), in the operating state (o), the second adsorption tower 2b is set to communicate with the vacuum pump 50, and the desorption step in the second adsorption tower 2b is set to a vacuum desorption step.

In the operating state (p), the 4th, 8th, 10th, 17th, 23rd, 25th on-off valves 6d, 7d, 8b, 11a, 12c, 14 are opened, and the remaining on-off valves are closed. When the fourth and eighth switching valves 6d and 7d are opened, the adsorption step is performed in the fourth adsorption tower 2d. By opening the 17th, 23rd, and 25th on-off valves 11a, 12c, and 14, the first gas introduction step is performed in the first adsorption tower 2a, and the first gas blowing step is performed in the third adsorption tower 2c. When the tenth switching valve 8b is opened, the desorption step is performed in the second adsorption tower 2a. Here, the desorption step in the second adsorption tower 2b following the operation state (o) is a vacuum desorption step.

In the operating state (q), the 4th, 8th, 10th, 13th, 18th, 23rd, 25th, 26th on-off valves 6d, 7d, 8b, 10a, 11b, 12c, 14, 16 are opened , The rest of the on-off valve is closed. By opening the fourth, eighth, thirteenth, and twenty-sixth on-off valves 6d, 7d, 10a, and 16 and performing the step-up step in the first adsorption tower 2a, the relay operation state is repeated in the fourth adsorption tower 2d (p ) The adsorption step is then carried out. When the 10th, 18th, 23rd, and 25th on-off valves 8b, 11b, 12c, and 14 are opened, a washing step is performed in the second adsorption tower 2b, and a depressurization step is performed in the third adsorption tower 2c. Here, the second adsorption tower 2b is set to communicate with the vacuum pump 50, and the exhaust gas G3' discharged in the washing step is sucked by the vacuum pump 50.

In the operating state (r), the 4th, 8th, 13th, 18th, 23rd, 25th, 26th on-off valves 6d, 7d, 10a, 11b, 12c, 14, 16 are opened, and the remaining on-off valves is closed. By the 4th, 8th, 13th, 26th on-off valves 6d, 7d, 10a, 16 are opened, The first adsorption tower 2a performs the boosting step after the relay operation state (q), and the fourth adsorption tower 2d performs the adsorption step after the relay operation state (q). When the 18th, 23rd, and 25th on-off valves 11b, 12c, and 14 are opened, the second gas introduction step is performed in the second adsorption tower 2b, and the second gas blowing step is performed in the third adsorption tower 2c. Here, since the vacuum pump 50 is unnecessary, it may be stopped.

In the operating state (s), the fourth, eighth, eleventh, thirteenth, and twenty-sixth on-off valves 6d, 7d, 8c, 10a, and 16 are opened, and the remaining on-off valves are closed. By the 4th, 8th, 11th, and 26th on-off valves 6d, 7d, 10a, 16 being opened, the step-up step is performed after the relay operation state (r) of the first adsorption tower 2a, and in the fourth adsorption tower After 2d relay operation state (r), the adsorption step is performed. When the 11th on-off valve 8c is opened, the desorption step is performed in the third adsorption tower 2c. The third adsorption tower 2c is not connected to the vacuum pump 50, and the desorption step in the third adsorption tower 2c is a discharge pressure desorption step. Here, since the vacuum pump 50 is unnecessary, it may be stopped. The second adsorption tower 2b is set to the standby state.

In the operating state (t), the switching state of the on-off valve is set to be the same as the operating state (s). By this, the boosting step is performed after the first adsorption tower 2a relay operation state (s), and after the fourth adsorption tower 2d relay operation state (s), the adsorption step is performed, and the second adsorption tower 2b is set to standby status. Unlike the operating state (s), in the operating state (t), the third adsorption tower 2c is set to communicate with the vacuum pump 50, and the desorption step in the third adsorption tower 2c is set to a vacuum desorption step.

In the operating state (a), (b), (e), (f), (g), (j), (k), (l), (o), (p), (q), (t) Next, the first reuse pipe 41 and the second reuse pipe 43 are connected via the first switch valve 42, the second reuse pipe 43 and the fourth reuse pipe 47 are connected via the second switch valve 45, and the fourth reuse pipe The pipe 47 is connected to the fifth reuse pipe 49 or the second discharge pipe 44' via the third switching valve 48. With this, the exhaust gases G3 and G3' in the vacuum desorption step and the cleaning step can be introduced into the buffer tank 22 or the normal pressure space through the vacuum pump 50. In the operating states (c), (d), (h), (i), (m), (n), (r), (s), the first reuse piping 41 is switched via the first The valve 42 is connected to the second reuse piping 43 or the first release piping 44, and connects the second reuse piping 43 and the third reuse piping 46 via the second switching valve 45. With this, the exhaust gas G3 in the discharge pressure desorption step can be introduced into the buffer tank 22 or the normal pressure space without passing through the vacuum pump 50.

When the adsorption step is performed in any of the adsorption towers 2a, 2b, 2c, and 2d, the raw material helium gas G1 is introduced into the inside of the adsorption tower through the raw material gas introduction flow path. The inside of the adsorption tower is pressurized to the adsorption pressure due to the pressure of the raw material helium gas G1. The suction pressure can be adjusted by the pressure regulating valve 26. Thereby, the impurity gas contained in the introduced raw material helium gas G1 is adsorbed on the adsorbent under pressure. In addition, the gas not adsorbed to the adsorbent is discharged from the inside of the adsorption tower through the purified gas flow path in the form of purified helium gas G2. It is preferable to set the repetition interval of the adsorption step in the pressure swing adsorption apparatus 1 in such a manner that the helium concentration of the purified helium gas G2 becomes the target concentration. The helium concentration of the purified helium gas G2 is preferably set to 99.999 vol% or more, and more preferably set to 99.9999 vol% or more. For example, as long as the concentration of the raw material helium gas G1 detected by the concentration sensor 24, the flow rate adjusted by the fourth flow control valve 25, the target concentration of the purified helium gas G2, and the adsorption step are obtained through experiments The relationship between the repetition intervals, and based on this relationship, the repetition interval of the detection step, the adjustment flow rate, and the adsorption step corresponding to the target concentration may be set. The repetition interval of the adsorption step in the pressure swing adsorption device 1 can be set by determining the time of one cycle of the purification process cycle, and the setting change can be performed only by changing the execution time and desorption of the adsorption step in one cycle of the purification process cycle The execution time of the attached steps is sufficient.

When the decompression step is performed in any one of the adsorption towers 2a, 2b, 2c, and 2d in the state after the first gas blowing step and before the second gas blowing step, the interior of the adsorption tower is connected to the The inside of the adsorption tower in the washing step communicates with the exhaust gas flow path and the pressure gradually decreases. Since the internal gas G4' in the adsorption tower in the depressurization step is introduced into the adsorption tower in the cleaning step, the reduction in the internal pressure of the adsorption tower in the decompression step is introduced into the adsorption in the cleaning step The amount of gas in the tower corresponds.

When the discharge pressure desorption step is performed in any of the adsorption towers 2a, 2b, 2c, and 2d, the interior of the adsorption tower communicates with the exhaust gas flow path, and the first and second switching valves 42, 45 are switched to A state where it communicates with the buffer tank 22 without passing through the vacuum pump 50 and a state where it communicates with the normal pressure space through the first release piping 44. The internal pressure of the adsorption tower is reduced to the pressure adjusted by the third flow control valve 18, and the impurity gas is desorbed from the adsorbent. The desorbed impurity gas is discharged from the inside of the adsorption tower through the exhaust gas flow path in the form of exhaust gas G3. The pressure inside the adsorption tower at the end of the discharge pressure desorption step is set to a pressure slightly higher than atmospheric pressure, so that in the desorption step, the exhaust gas G3 flows in the reuse flow path due to its own pressure, thereby reaching the buffer tank 22, or from the first release piping 44 to the normal pressure space.

When the vacuum desorption step is performed in any of the adsorption towers 2a, 2b, 2c, and 2d, the interior of the adsorption tower communicates with the exhaust gas flow path, and further, by the first to third switching valves 42, 45, 48 , It is switched to a state where it communicates with the buffer tank 22 via the vacuum pump 50, and a state where it communicates with the normal pressure space via the second release piping 44'. As a result, the internal pressure of the adsorption tower is reduced to less than atmospheric pressure by the vacuum pump 50, and the impurity gas is desorbed from the adsorbent. The desorbed impurity gas is sucked by the vacuum pump 50, and is discharged from the inside of the adsorption tower through the exhaust gas flow path in the form of exhaust gas G3. The exhaust gas G3 flows through the reuse flow path to reach the buffer tank 22, or is discharged from the second discharge pipe 44' to the normal pressure space.

When the pressure-increasing step is performed in any of the adsorption towers 2a, 2b, 2c, and 2d, the inside of the adsorption tower communicates with the inside of the adsorption tower in the adsorption step via the communication flow path. At this time, a part of the purified helium gas G2 discharged from the adsorption tower in the adsorption step is introduced into the adsorption tower in the boosting step. Thereby, the inside of the adsorption tower in the step of increasing pressure is pressurized and the pressure rises to or near the adsorption pressure.

In each purification treatment cycle, the first gas blowing step of blowing internal gas from any one of the adsorption towers 2a, 2b, 2c, 2d in the state after the adsorption step and before the desorption step is carried out, and the blowing The internal gas is introduced into the first gas guide of any one of the adsorption towers 2a, 2b, 2c, 2d in the state after the desorption step and before the pressure step 入步骤。 Steps. By connecting the inside of the adsorption tower at the first gas blowing step with the inside of the adsorption tower at the first gas introduction step, the internal pressure of the adsorption tower at the first gas blowing step and the adsorption tower at the first gas introduction step The difference in internal pressure is reduced. In other words, by introducing the internal gas blown from the adsorption tower in the first gas blowing step into the adsorption tower in the first gas introduction step, the internal pressure of the adsorption tower in the first gas blowing step is reduced to be in the first gas The internal pressure of the adsorption tower in the introduction step rises. In this embodiment, the difference between the internal pressure of the adsorption tower in the first gas blowing step and the internal pressure of the adsorption tower in the first gas introduction step is regarded as the end of the first gas blowing step and the first gas introduction step Time remains, but the two internal pressures can also be equalized.

In each purification treatment cycle, the second gas blowing step of blowing the internal gas from any of the adsorption towers 2a, 2b, 2c, 2d in the state after the first gas blowing step and before the desorption step is carried out, and the The blown internal gas is introduced into the second gas introduction step of any one of the adsorption towers 2a, 2b, 2c, and 2d in a state after the desorption step and before the first gas blowing step. By connecting the inside of the adsorption tower at the second gas blowing step with the inside of the adsorption tower at the second gas introduction step, the internal pressure of the adsorption tower at the second gas blowing step and the adsorption tower at the second gas introduction step The difference in internal pressure is reduced. In other words, by introducing the internal gas blown from the adsorption tower in the second gas blowing step into the adsorption tower in the second gas introduction step, the internal pressure of the adsorption tower in the second gas blowing step is reduced to be in the second gas The internal pressure of the adsorption tower in the introduction step rises. In this embodiment, the difference between the internal pressure of the adsorption tower in the second gas blowing step and the internal pressure of the adsorption tower in the second gas introduction step is eliminated at the end of the second gas blowing step and the second gas introduction step , The two internal pressures are equalized, but the difference between the two internal pressures can also remain.

By this, the difference between the internal pressure of the adsorption tower is reduced between the adsorption step and the decompression step and between the decompression step and the desorption step. By reducing the difference in the internal pressure of the adsorption tower, the internal gas of the adsorption tower in the first and second gas blowing steps is used to 1. The internal pressure of the adsorption tower in the second gas introduction step rises, so that the impurity gas contained in the internal gas can be adsorbed on the adsorbent, and the purified helium gas not adsorbed on the adsorbent can be recovered.

In order to introduce the internal gas of the adsorption tower in the first gas blowing step into the adsorption tower in the first gas introduction step, any one of the on-off valves communicating with the flow path is opened. Therefore, the amount of gas introduced into the adsorption tower in the first gas introduction step corresponds to the product of the execution time of the first gas blowing step or the first gas introduction step and the gas flow rate flowing in the communication channel. The execution time of the first gas blowing step and the first gas introduction step of this embodiment is set to a predetermined fixed time, and the fixed execution time is stored in the control device 20.

In the present embodiment, the amount of gas introduced into the adsorption tower in the first gas introduction step is changed by adjusting the flow rate of the gas flowing in the communication channel using the first flow control valve 15. For this reason, the flow rate of the gas G4 in the communication flow path from the adsorption tower in the first gas blowing step and being introduced into the adsorption tower in the first gas introduction step, and the helium concentration of the raw material helium gas G1 The predetermined correspondence is stored in the control device 20.

In order to execute the first gas blowing step and the first gas introduction step only at the execution time memorized by the control device 20, the on-off valve is controlled, and the adjusted gas flow rate is changed by the first flow control valve 15 based on the memorized correspondence, so that Since the adsorption tower in the first gas blowing step is blown and introduced into the adsorption tower in the first gas introduction step, the amount of gas is increased to as high as the helium concentration of the raw material helium gas G1 detected by the concentration sensor 24 degree.

The amount of gas introduced into the adsorption tower in the first gas introduction step is the internal pressure at the beginning of the first gas blowing step in the adsorption tower in the first gas blowing step and the internal pressure at the end of the first gas blowing step The pressure difference δP' corresponds. Therefore, the amount of gas introduced into the adsorption tower in the first gas introduction step may be optimized by changing the pressure difference δP′ according to the change in the detected helium concentration detected by the concentration sensor 24. example For example, it is determined in advance that the pressure difference δP' becomes 350 kPa when the detected helium concentration is 30 vol% or more, and the pressure difference δP' becomes 50 kPa when the detected helium concentration is 15 vol%. The relationship between the helium concentration of gas G1. The adjustment of the gas flow rate by the first flow control valve 15 may be performed once in one cycle of the purification process step, and if the concentration variation of the raw material helium gas G1 is small, it may also be performed once in multiple cycles .

When the amount of gas introduced into the adsorption tower in the first gas introduction step is increased to such a high level as the helium concentration of the raw material helium gas G1, the start time of the step-up step following the first gas introduction step The internal pressure of the adsorption tower changes. Therefore, it is preferable that when the internal pressure of the adsorption tower in the pressure increasing step is increased to the adsorption pressure, the purified helium from the adsorption tower in the adsorption step is blown and introduced into the adsorption tower in the pressure step The amount of gas G2 changes. In this case, in the boosting step, it is only necessary to set the time of the boosting step to a predetermined fixed value and adjust the flow rate of the gas flowing in the communication flow path by the second flow control valve 17. Therefore, it is only necessary to determine in advance by experiment the relationship between the gas flow rate adjusted by the second flow rate control valve 17 and flowing in the communication channel and the helium concentration of the raw material helium gas G1.

As a variation example for increasing the amount of gas introduced into the adsorption tower in the first gas introduction step to a high level like the helium concentration of the raw material helium gas G1, the first gas blowing step and the first gas introduction step can also be adjusted Implementation time. In this case, since the flow rate of the gas flowing in the communication channel is fixed, the flow rate control by the first flow control valve 15 is not necessary.

That is, since the amount of gas introduced into the adsorption tower in the first gas introduction step corresponds to the product of the execution time of the first gas blowing step and the first gas introduction step and the gas flow rate flowing in the communication flow path, The gas amount can be changed by adjusting the execution time of the first gas blowing step and the first gas introduction step.

For this reason, the execution time of the first gas blowing step and the first gas introduction step The predetermined correspondence between the helium concentrations of the helium gas G1 is stored in the control device 20. The execution time of the first gas blowing step and the first gas introduction step, that is, the control time of the on-off valve for the first gas blowing step and the first gas introduction step is changed based on the correspondence relationship memorized by the control device 20, so that The adsorption tower in the first gas blowing step is blown and the amount of gas introduced into the adsorption tower in the first gas introduction step is increased to a level as high as the helium concentration of the raw material helium gas G1 detected by the concentration sensor 24 . In addition, when the execution time of the first gas blowing step and the first gas introduction step is changed, when the execution time of the adsorption step is not changed, it is only necessary to change the execution time of the step-up and desorption steps. In addition, it suffices to perform the control as in the embodiment.

In order to introduce the internal gas in the adsorption tower in the second gas blowing step into the adsorption tower in the second gas introduction step, any one of the on-off valves of the communication flow path is opened. In this embodiment, the second gas blowing step and the second gas introduction step are performed until the internal pressure of the adsorption tower in the second gas blowing step and the internal pressure of the adsorption tower in the second gas introduction step are equalized.

Perform the decompression step in any of the adsorption towers 2a, 2b, 2c, and 2d, and at the same time in the adsorption towers 2a, 2b, 2c, and 2d in the state after the desorption step and before the second gas introduction step Washing steps are carried out among those. The inside of the adsorption towers 2a, 2b, 2c, 2d in the washing step communicates with the inside of the adsorption towers 2a, 2b, 2c, 2d in the depressurization step through the communication flow path, and communicates with the exhaust gas flow path. Thereby, the internal gas G4' blown from the adsorption tower in the depressurization step is discharged as exhaust gas G3' after being introduced into the adsorption tower in the washing step. The exhaust gas G3' discharged from the adsorption tower in the washing step contains helium gas contained in the internal gas G4' of the adsorption tower in the decompression step. The self-exhaust flow path inside the adsorption tower in the washing step is switched to the state of communicating with the buffer tank 22 via the vacuum pump 50 through the first to third switching valves 42, 45, and 48, and is used for the second release Piping 44' is in a state of communication with the normal pressure space. Thereby, the exhaust gas G3' is attracted by the vacuum pump 50, flows through the reuse flow path to reach the buffer tank 22, or is released from the second release pipe 44' to the normal pressure space. Furthermore, The inside of the adsorption tower in the cleaning step can be set to be not in communication with the vacuum pump 50. In this case, the exhaust gas flow path is switched to not pass through the vacuum pump 50 through the first and second switching valves 42, 45. The state where the buffer tank 22 is in communication and the state where it is in communication with the normal pressure space through the first release piping 44. The exhaust gas G3' reaches the buffer tank 22 through the reuse flow path, or is released to the normal pressure space through the first release piping 44.

In the pressure swing adsorption device 1, the amount of gas that is blown from the adsorption tower in the decompression step and introduced into the adsorption tower in the washing step is reduced to the raw materials introduced into the adsorption towers 2a, 2b, 2c, 2d The helium concentration of helium G1 is as high as it is. For this reason, as described below, the execution time of the washing step is set to be fixed, and the flow rate of the gas flowing in the communication flow path is adjusted by the first flow control valve 15. Furthermore, in this embodiment, when the helium concentration of the raw material helium gas G1 introduced into the adsorption towers 2a, 2b, 2c, 2d does not reach a predetermined set value, a washing step is performed, when the helium concentration is above the set value No cleaning steps are carried out.

In order to introduce the internal gas of the adsorption tower in the depressurization step to the adsorption tower in the cleaning step, any one of the on-off valves communicating with the flow path is opened. Therefore, the amount of gas introduced into the adsorption tower in the washing step corresponds to the product of the execution time of the washing step and the gas flow rate flowing in the communication flow path. The execution time of the washing step of this embodiment is set to a predetermined fixed time, and the fixed execution time is memorized in the control device 20.

The amount of gas introduced into the adsorption tower in the washing step can be changed by adjusting the flow rate of the gas flowing in the communication flow path using the first flow control valve 15. For this reason, the predetermined correspondence between the flow rate of the gas G4' introduced into the adsorption tower in the cleaning step in the communication channel and the helium concentration of the raw material helium gas G1 is stored in the control device 20.

In order to execute the washing step only at the execution time memorized by the control device 20, the on-off valve is controlled, and based on the memorized correspondence, the first gas flow control valve 15 is used to change the adjusted gas flow rate so that the adsorption tower is in the decompression step The amount of gas blown and introduced into the adsorption tower in the washing step is reduced to the raw material helium gas detected by the concentration sensor 24 The helium concentration of G1 is as high as it is. In addition, the predetermined set value of the helium concentration is memorized in the control device 20, and when the detected helium concentration detected by the concentration sensor 24 is more than the memorized set value, the regulated gas controlled by the first flow control valve 15 The flow rate is set to zero without performing the washing step. When the washing step is not performed, the decompression step is not performed.

The amount of gas introduced into the adsorption tower in the cleaning step corresponds to the pressure difference δP between the internal pressure at the beginning of the cleaning step in the adsorption tower at the decompression step and the internal pressure at the end of the cleaning step. Therefore, it is only necessary to optimize the amount of gas introduced into the adsorption tower in the washing step by changing the pressure difference δP according to the change in the detected helium concentration detected by the concentration sensor 24. For example, when the detected helium concentration is 50 vol% or more, the adjusted gas flow rate controlled by the first flow control valve 15 is set to zero so that the pressure difference δP becomes zero, and the washing step is not performed. In addition, when the detected helium concentration does not reach 50 vol%, as long as the pressure difference δP increases corresponding to the decrease in the detected helium concentration, the flow rate adjusted by the first flow control valve 15 to the communication flow is determined in advance by experiment The relationship between the flow rate of the gas flowing in the road and the helium concentration of the raw material helium gas G1 is sufficient. For example, the gas flow rate in the communication channel and the helium concentration of the raw material helium gas G1 are determined in advance, such as the pressure difference δP becomes 50 kPa when the detected helium concentration is 30 vol%, and the pressure difference δP becomes 70 kPa when the detected helium concentration is 15 vol%. The relationship between. The adjustment of the gas flow rate by the first flow control valve 15 only needs to be performed once in one cycle of the purification process step, but if the concentration variation of the raw material helium gas G1 is small, it can also be performed in multiple cycles 1 time.

As an example of a change to reduce the amount of gas that is blown from the adsorption tower in the decompression step and introduced into the adsorption tower in the cleaning step to a high level like the helium concentration of the raw material helium gas G1, the cleaning can also be adjusted Implementation time of the step. In this case, since the flow rate of the gas flowing in the communication channel is fixed, the flow rate control by the first flow control valve 15 is not necessary.

That is, the amount of gas introduced into the adsorption tower in the washing step corresponds to the product of the execution time of the washing step and the gas flow rate flowing in the communication flow path. The amount of gas can be changed to save the time of the cleaning step.

For this reason, the predetermined correspondence between the execution time of the washing step and the helium concentration of the raw material helium gas G1 is stored in the control device 20. The execution time of the washing step, that is, the control time of the on-off valve used for the washing step is changed based on the correspondence relationship memorized by the control device 20, so that the adsorption tower from the depressurization step is blown and introduced to be in the washing The amount of gas in the adsorption tower of the step is reduced to a level as high as the helium concentration of the raw material helium gas G1 detected by the concentration sensor 24. Furthermore, when the execution time of the washing step is changed, and when the execution time of the adsorption step is not changed, it is only necessary to change the execution time of the step-up and desorption steps. In addition, it suffices to perform the control as in the embodiment.

According to the above-described embodiment and modified example, by repeatedly performing the purification process cycle using the pressure swing adsorption apparatus 1, the raw material helium gas G1 can be purified, and purified helium gas G2 can be continuously obtained. In each purification treatment cycle, the internal pressure difference of the adsorption tower is reduced twice. By reducing the internal pressure difference of the adsorption tower, the internal gas in the adsorption tower in the first and second gas blowing steps is introduced into the adsorption tower in the first and second gas introduction steps, so it can be made into the internal gas The impurity gas contained is adsorbed on the adsorbent, and the purified helium gas not adsorbed on the adsorbent is recovered. In addition, by depressurizing the inside of the adsorption tower to a subatmospheric pressure using a vacuum pump in the desorption step, a vacuum desorption step can be performed. The performance of the adsorbent can be restored by the vacuum desorption step. In each purification treatment cycle, the internal pressure difference of the adsorption tower is reduced twice, and the performance of the adsorbent is restored by the vacuum desorption step, whereby the synergistic effect can be used to greatly improve the recovery rate of helium. Furthermore, by increasing the amount of gas introduced into the adsorption tower in the first gas introduction step to a level as high as the helium concentration of the raw material helium gas G1, the recovery rate of helium gas can be improved. In addition, by reducing the amount of gas introduced into the adsorption tower in the washing step to such a high level as the helium concentration of the raw material helium gas G1, the recovery rate of helium gas can be prevented from unnecessarily decreasing. Therefore, for example, in the case of using helium gas discharged from the manufacturing process of the optical fiber as the raw material helium gas, it is possible to flexibly respond to changes in the concentration of the raw material gas, and it is possible to efficiently obtain the target purity helium gas. And, by the helium contained in the exhaust gas G3, G3' Reuse can also increase the recovery rate.

[Example]

[Example 1]

Purification system α using helium gas is used to purify the raw material helium gas G1 according to the above embodiment.

Regarding the raw material helium gas G1, the helium concentration is set to 30.0 vol%, and the concentration of air as an impurity gas is set to 70.0 vol%.

The supply flow rate of the raw material helium gas G1 to the pressure swing adsorption device 1 is set to 300 NL/h.

Each of the adsorption towers 2a, 2b, 2c, and 2d is made of stainless steel, and has a cylindrical shape with an inner diameter of 37 mm and an inner dimension height of 1000 mm, and a capacity of about 1 L. Each of the adsorption towers 2a, 2b, 2c, and 2d is filled with and stacked with about 0.7L of activated carbon as adsorbent and about 0.3L of zeolite.

As a purification treatment step in the pressure swing adsorption apparatus 1, in each of the adsorption towers 2a, 2b, 2c, and 2d, the adsorption step is performed in sequence for 130 seconds, the first gas blowing step for 15 seconds, and the decompression step for 25 seconds Bell, second gas blowing step 15 seconds, discharge pressure desorption step 10 seconds, vacuum desorption step 80 seconds, cleaning step 25 seconds, second gas introduction step 15 seconds, standby state 75 seconds, The first gas introduction step is 15 seconds, and the pressure increase step is 115 seconds. The cycle time from the start of the operating state (a) to the end of the operating state (t) is 520 seconds.

The maximum value of the internal pressure of the adsorption towers 2a, 2b, 2c, 2d in the adsorption step is set to 0.8 MPa (gauge pressure). The pressure difference between the internal pressure of the adsorption tower at the beginning of the first gas blowing step and the internal pressure of the adsorption tower at the end was set to 350 kPa. The pressure difference between the internal pressure of the adsorption tower at the beginning of the decompression step and the internal pressure of the adsorption tower at the end was set to 50 kPa. The second gas blowing step and the second gas introduction step are performed until the internal pressure of the two adsorption towers in the two steps becomes equal. The internal pressure of the adsorption tower at the end of the vacuum desorption step was set to -95 kPa (gauge pressure).

Exhaust gas G3, G3' is released to the normal pressure space without being reused.

The flow rate of purified helium G2 is 65.7 NL/h, and the impurity concentration is 0.8 vol ppm (measured by Shimadzu Corporation's GC (Gas Chromatograph, gas chromatograph)-PDD (Pulse Discharge Detector, pulse discharge detector)) The helium recovery rate is 73.0%.

[Example 2]

From the steady state of Example 1, the repetition interval of the adsorption step was changed by adjusting the adsorption step time in the pressure swing adsorption device 1, the flow rate of the purified helium gas G2 was set to 68.2NL/h, and the impurity concentration was set to 8.5 vol ppm. It is assumed that it is the same as in Example 1. In this case, the helium recovery rate was 75.8%.

[Example 3]

Assuming that the raw helium gas G1 has a concentration change from the steady state of Example 1, the helium concentration of the raw helium gas G1 is changed to 50.0 vol%, and the air concentration is changed to 50.0 vol%. The washing step and decompression step were not implemented. The repetition interval of the adsorption step was changed by adjusting the adsorption step time in the pressure swing adsorption device 1, the flow rate of the purified helium gas G2 was set to 121.4 NL/h, and the impurity concentration was set to 0.9 vol ppm. It is assumed that it is the same as in Example 1. In this case, the helium recovery rate was 80.9%.

[Example 4]

Assuming that the raw helium gas G1 has a concentration change from the steady state of Example 1, the helium concentration of the raw helium gas G1 is changed to 15.0 vol%, and the air concentration is changed to 85.0 vol%. The pressure difference between the internal pressure of the adsorption tower at the beginning of the first gas blowing step and the internal pressure of the adsorption tower at the end was set to 50 kPa. In addition, the pressure difference between the internal pressure of the adsorption tower at the beginning of the decompression step and the internal pressure at the end was set to 70 kPa. The repetition interval of the adsorption step was changed by adjusting the adsorption step time in the pressure swing adsorption device 1, the flow rate of the purified helium gas G2 was set to 27.5 NL/h, and the impurity concentration was set to 0.9 vol ppm. It is assumed that it is the same as in Example 1. In this case, the helium recovery rate was 61.2%.

[Example 5]

Assuming that the raw helium gas G1 has a concentration change from the steady state of Example 1, the helium concentration of the raw helium gas G1 is changed to 50.0 vol%, and the air concentration is changed to 50.0 vol%. The repetition interval of the adsorption step was changed by adjusting the adsorption step time in the pressure swing adsorption device 1, the flow rate of the purified helium gas G2 was set to 116.1 NL/h, and the impurity concentration was set to 0.8 vol ppm. It is assumed that it is the same as in Example 1. In this case, the helium recovery rate was 77.4%.

[Example 6]

50% of the exhaust gases G3 and G3' discharged from the pressure swing adsorption device 1 are mixed into the raw material helium gas G1 through the reuse flow path. The repetition interval of the adsorption step is changed by adjusting the adsorption step time in the pressure swing adsorption device 1, the flow rate of the purified helium gas G2 is set to 72.6 NL/h, and the impurity concentration is set to 0.8 vol ppm. It is assumed that it is the same as in Example 1. In this case, the helium recovery rate of all steps becomes 80.7%.

[Example 7]

From the steady state of Example 1, the pressure difference between the internal pressure of the adsorption tower at the beginning of the first gas blowing step and the internal pressure of the adsorption tower at the end was set to 50 kPa. In addition, the pressure difference between the internal pressure of the adsorption tower at the beginning of the decompression step and the internal pressure at the end was set to 70 kPa. The repetition interval of the adsorption step is changed by adjusting the adsorption step time in the pressure swing adsorption device 1, the flow rate of the purified helium gas G2 is set to 60.7 NL/h, and the impurity concentration is set to 0.9 vol ppm. It is assumed that it is the same as in Example 1. In this case, the helium recovery rate was 67.4%.

[Comparative Example 1]

The first gas blowing step, the first gas introduction step and the vacuum desorption step are not performed, and the internal pressure of the adsorption tower at the end of the discharge pressure desorption step is set to 5 kPa (gauge pressure), and the raw material helium gas G1 is carried out purification. The repetition interval of the adsorption step is changed by adjusting the adsorption step time in the pressure swing adsorption device 1, the flow rate of the purified helium gas G2 is set to 55.6 NL/h, and the impurity concentration is set to 0.9 vol ppm. In addition, it is assumed to be the same as in Example 1. kind. In this case, the helium recovery rate becomes 61.8%.

[Comparative Example 2]

The first gas blowing step and the first gas introduction step were not performed, and the raw material helium gas G1 was purified. The repetition interval of the adsorption step is changed by adjusting the adsorption step time in the pressure swing adsorption device 1, the flow rate of the purified helium gas G2 is set to 57.7 NL/h, and the impurity concentration is set to 0.8 vol ppm. It is assumed that it is the same as in Example 1. In this case, the helium recovery rate becomes 64.1%.

[Comparative Example 3]

The vacuum desorption step was not performed, and the internal pressure of the adsorption tower at the end of the discharge pressure desorption step was set to 5 kPa (gauge pressure), and the raw material helium gas G1 was purified. The repetition interval of the adsorption step was changed by adjusting the adsorption step time in the pressure swing adsorption device 1, the flow rate of the purified helium gas G2 was set to 57.2 NL/h, and the impurity concentration was set to 0.9 vol ppm. It is assumed that it is the same as in Example 1. In this case, the helium recovery rate becomes 63.6%.

[Comparative Example 4]

The first gas blowing step, the first gas introduction step, and the vacuum desorption step were not performed, and the internal pressure of the adsorption tower at the end of the discharge pressure desorption step was set to 5 kPa (gauge pressure), and the raw material helium gas G1 was carried out purification. The repetition interval of the adsorption step was changed by adjusting the adsorption step time in the pressure swing adsorption device 1, the flow rate of the purified helium gas G2 was set to 64.7 NL/h, and the impurity concentration was set to 8.7 vol ppm. It is assumed that it is the same as in Example 1. In this case, the helium recovery rate becomes 71.9%.

[Comparative Example 5]

The first gas blowing step, the first gas introduction step, and the vacuum desorption step were not performed, and the internal pressure of the adsorption tower at the end of the discharge pressure desorption step was set to 5 kPa (gauge pressure), and the raw material helium gas G1 was carried out purification. The repetition interval of the adsorption step was changed by adjusting the adsorption step time in the pressure swing adsorption device 1, the flow rate of the purified helium gas G2 was set to 100.5 NL/h, and the impurity concentration was set to 0.9 vol ppm. In addition, it is assumed to be the same as in Example 3. kind. In this case, the helium recovery rate becomes 67.0%.

[Comparative Example 6]

The first gas blowing step, the first gas introduction step, and the vacuum desorption step were not performed, and the internal pressure of the adsorption tower at the end of the discharge pressure desorption step was set to 5 kPa (gauge pressure), and the raw material helium gas G1 was carried out purification. The repetition interval of the adsorption step was changed by adjusting the adsorption step time in the pressure swing adsorption device 1, the flow rate of the purified helium gas G2 was set to 25.1 NL/h, and the impurity concentration was set to 0.9 vol ppm. The system is the same as in Example 4. In this case, the helium recovery rate becomes 55.7%.

According to the difference between the helium recovery rates of Comparative Examples 1 and 2, the improvement in the helium recovery rate generated by the vacuum desorption step is about 2.3%. According to the difference between the helium recovery rates of Comparative Examples 1 and 3, the increase in the helium recovery rate generated by increasing the number of reductions in the internal pressure difference of the adsorption tower from 1 to 2 is about 1.8%. Therefore, it has been previously thought that even if the increase in the number of reductions in the internal pressure difference of the adsorption tower is combined with the vacuum desorption step, the improvement in recovery rate is about 4.1%. However, according to the difference between the helium recovery rate of Example 1 and the helium recovery rates of Comparative Examples 1 and 3, the improvement of the helium recovery rate generated by this combination is about 8.9% to 9.4%. Therefore, it can be confirmed that the combination exerts a synergistic effect.

In addition, according to Examples 1 and 7, it can be confirmed that by increasing the amount of gas introduced from the adsorption tower in the first gas blowing step to the adsorption tower in the first gas introduction step to a helium concentration as high as the raw material helium gas Degree, and the amount of gas introduced into the adsorption tower in the washing step is reduced to a high level like the helium concentration of the raw material helium, and the recovery rate of helium is increased.

It can be confirmed from Examples 1 and 6 that the exhaust gas G3 and G3' are mixed into the raw material helium gas G1 through the reuse flow path to increase the helium recovery rate.

It can be confirmed from Examples 3 and 5 that the helium recovery rate is improved by not performing the washing step when the raw material gas has a high helium concentration.

It can be confirmed from Examples 1 and 2 that the helium recovery rate can be increased when there is no need to increase the purity of helium.

According to Example 1 and Comparative Example 4, Example 3 and Comparative Example 5, Example 4 and Comparative Example 6, it can be confirmed that by combining the reduction times of increasing the internal pressure difference of the adsorption tower and the vacuum desorption step, Improve the purity and recovery rate of purified helium.

The present invention is not limited to the above-mentioned embodiments, examples, and modified examples, and various changes can be made without departing from the scope of the inventive concept. For example, the number of adsorption towers in the adsorption device is not limited to 4 towers, and may be 3 towers or more than 5 towers. Furthermore, the number of reductions in the internal pressure difference of the adsorption tower in each purification treatment cycle may be more than 3 times. In addition, in the above-mentioned embodiment, the pressure increasing step is performed by introducing purified helium gas into the adsorption tower, but the pressure increasing step may also be performed by introducing raw material gas into the adsorption tower instead of purifying helium gas. Furthermore, not only the internal gas from the adsorption tower in the first gas blowing step but also the raw material gas can be introduced into the adsorption tower in the first gas introduction step.

1‧‧‧ Pressure swing adsorption device

2a‧‧‧Adsorption tower

2b‧‧‧Adsorption tower

2c‧‧‧Adsorption tower

2d‧‧‧adsorption tower

18‧‧‧ Third flow control valve

21‧‧‧Flow sensor

22‧‧‧Buffer tank

22a‧‧‧Storage sensor

23‧‧‧Compressor

24‧‧‧Concentration sensor

25‧‧‧ 4th flow control valve

26‧‧‧pressure regulating valve

41‧‧‧The first reuse piping (reuse flow path)

42‧‧‧First switching valve

43‧‧‧The second reuse piping (reuse flow path)

44‧‧‧The first release piping

44'‧‧‧ 2nd release piping

45‧‧‧ 2nd switching valve

46‧‧‧The third reuse piping (reuse flow path)

47‧‧‧ 4th reuse piping (reuse flow path)

48‧‧‧ Third switching valve

49‧‧‧The fifth reuse piping (reuse flow path)

50‧‧‧Vacuum pump

G1‧‧‧raw material helium

G2‧‧‧Purified helium

G3‧‧‧Exhaust

G3'‧‧‧Exhaust

α‧‧‧Purification system

Claims (17)

A method for purifying helium gas is to use a pressure swing adsorption device with a plurality of adsorption towers to purify the raw material helium gas containing impurity gas, in each of the above adsorption towers, the adsorption is preferentially adsorbed over helium gas The adsorbent of the impurity gas introduces the raw material helium gas into each of the adsorption towers in sequence, and in each of the adsorption towers, the following steps are sequentially performed: an adsorption step that causes the introduced raw material helium gas to be contained The impurity gas is adsorbed on the adsorbent under pressure, and purified helium gas that is not adsorbed on the adsorbent is discharged; a desorption step, which desorbs the impurity gas from the adsorbent and discharges it as exhaust gas; and The step of raising the internal pressure; performing the first gas blowing step of blowing the internal gas from any one of the adsorption towers in the state after the adsorption step and before the desorption step, and simultaneously carrying out the internal gas blown The first gas introduction step of any one of the adsorption towers in the state after the desorption step and before the pressure increase step is performed after the first gas blowing step and before the desorption step The second gas blowing step of blowing the internal gas in any of the adsorption towers in the state, and simultaneously introducing the blown internal gas to the adsorption tower in a state after the desorption step and before the first gas introduction step In the second gas introduction step of any one of the other, in the desorption step, the inside of the adsorption tower is depressurized to a subatmospheric pressure using a vacuum pump. The purification method of helium gas according to claim 1, wherein the amount of gas from the adsorption tower in the first gas blowing step is blown and introduced into the adsorption tower in the first gas introduction step to the raw material helium Elevation of helium concentration of gas degree. A purification method of helium gas as claimed in claim 1 or 2, wherein in any of the adsorption towers in a state after the first gas blowing step and before the second gas blowing step, decompression for reducing the internal pressure is performed At the same time, in any one of the adsorption towers in the state after the desorption step and before the second gas introduction step, it is performed as the exhaust after introducing the internal gas of the adsorption tower in the decompression step And the washing step of discharge. The purification method of helium gas according to claim 3, wherein the amount of gas blown from the adsorption tower in the depressurization step and introduced into the adsorption tower in the cleaning step is reduced to the helium concentration of the raw material helium gas So high. The method for purifying helium gas according to claim 4, wherein when the helium concentration of the raw material helium gas is greater than or equal to a predetermined set value, the above washing step is not performed. The method for purifying helium gas according to claim 1 or 2, wherein the exhaust gas is introduced into the introduction flow path of the raw material helium gas to each of the adsorption towers to reuse the exhaust gas as the raw material helium gas. The method for purifying helium gas according to claim 3, wherein the exhaust gas is introduced into the introduction flow path of the raw material helium gas to each of the adsorption towers to reuse the exhaust gas as the raw material helium gas. The method for purifying helium gas according to claim 4, wherein the exhaust gas is introduced into the introduction flow path of the raw material helium gas to each of the adsorption towers to reuse the exhaust gas as the raw material helium gas. The purification method of helium gas according to claim 5, wherein the exhaust gas is introduced into the introduction flow path of the raw material helium gas to each of the adsorption towers to reuse the exhaust gas as the raw material helium gas. A helium purification system is provided with a pressure swing adsorption device having a plurality of adsorption towers, and In each of the adsorption towers, an adsorbent that adsorbs impurity gas in preference to helium gas is stored, and the pressure swing adsorption device includes a raw material gas introduction flow path for introducing the raw material helium gas to each of the adsorption towers ; Purified gas flow path, which is used to discharge purified helium gas from each of the above adsorption towers; Exhaust flow path, which is used to discharge exhaust gas from each of the above adsorption towers; Communication flow path, which is used to make the above adsorption towers Either one communicates with the other; the raw material gas introduction path on-off valve, which individually switches between each of the adsorption towers and the raw material gas introduction flow path; the purified gas path on-off valve, which connects the adsorption tower Each is individually opened and closed between the purified gas flow path; an exhaust path on-off valve that individually opens and closes each of the adsorption towers and the exhaust flow path; and a communication path on-off valve that controls the adsorption Each of the towers is individually opened and closed between the above-mentioned communication channels; each of the above-mentioned on-off valves is set as an automatic valve having an on-off actuator in such a way that the on-off operation can be performed individually, and is connected to the control device, In each of the adsorption towers, each of the on-off valves is controlled by the control device to sequentially perform the following steps: an adsorption step that causes the impurity gas contained in the introduced raw material helium gas to be adsorbed to the adsorption under pressure Agent, and discharge the purified helium gas that is not adsorbed on the adsorbent; the desorption step, which desorbs the impurity gas from the adsorbent and discharges it as exhaust; and the boosting step, which raises the internal pressure; The first gas blowing step of blowing the internal gas in any of the adsorption towers in the state after the adsorption step and before the desorption step, and simultaneously introducing the blown internal gas after the desorption step and the above The first gas introduction step of any one of the other adsorption towers in the state before the boosting step, and the inside of any one of the adsorption towers in the first gas blowing step and the first gas introduction step Within any of the above adsorption towers In order to communicate with each other, each of the on-off valves is controlled by the control device, in order to perform the second gas blowing of the internal gas from any one of the adsorption towers in the state after the first gas blowing step and before the desorption step In the blowing step, the second gas introduction step of any one of the other of the adsorption towers in the state after the desorption step and before the first gas introduction step is carried out while introducing the blown internal gas is carried out Each of the on-off valves is controlled by the control device so that the inside of any of the adsorption towers in the second gas blowing step communicates with the inside of any of the adsorption towers in the second gas introduction step, Moreover, the helium purification system is equipped with a vacuum pump that depressurizes the inside of the adsorption tower in the desorption step to subatmospheric pressure. The helium purification system according to claim 10, which includes a flow control valve that adjusts the flow rate of the gas flowing in the communication flow path, and the flow control valve is set to have an actuator for flow adjustment in such a manner that the flow adjustment operation can be performed The automatic valve of the device is connected to the control device and includes a sensor that detects the helium concentration of the raw material helium gas and is connected to the control device. The first gas blowing step and the first gas introduction step are predetermined A certain execution time is memorized in the control device, the gas from the adsorption tower in the first gas blowing step is blown and introduced into the gas in the adsorption tower in the first gas introducing step in the communication flow path The predetermined correspondence between the flow rate and the helium concentration of the raw material helium gas is memorized in the control device, so that the first gas blowing step and the first gas injection step are performed only at the execution time memorized by the control device The gas introduction step controls the on-off valve, and changes the opening of the communication flow path using the flow control valve based on the corresponding relationship Degree so that the amount of gas from the adsorption tower in the first gas blowing step is blown and introduced into the adsorption tower in the first gas introduction step to the concentration of helium detected by the sensor To a high degree. The helium purification system according to claim 10, which includes a sensor that detects the helium concentration of the raw material helium gas and is connected to the control device, the execution time of the first gas blowing step and the first gas introduction step, and the above The predetermined correspondence relationship between the helium concentrations in the raw material helium gas is stored in the control device, and the execution time of the first gas blowing step and the first gas introduction step is changed based on the correspondence relationship by the control device to Increase the amount of gas blown from the adsorption tower in the first gas blowing step and introduced into the adsorption tower in the first gas introduction step to a level as high as the helium concentration detected by the sensor . The helium purification system of claim 10, wherein each of the on-off valves is controlled by the control device to be in any of the adsorption towers in a state after the first gas blowing step and before the second gas blowing step Among them, the decompression step for reducing the internal pressure is performed, and at the same time, in any one of the adsorption towers in the state after the desorption step and before the second gas introduction step, the decompression step is carried out A cleaning step of exhausting the internal gas of the adsorption tower as exhaust gas, and including a flow control valve that adjusts the flow rate of the gas flowing in the communication flow path, and the flow control valve is configured to enable a flow adjustment operation An automatic valve with an actuator for flow adjustment, connected to the control device, and equipped with a sensor that detects the helium concentration of the raw material helium gas and is connected to the control device, the predetermined step of the cleaning step is carried out in advance Time is memorized in the above control In the manufacturing apparatus, the flow rate of the gas in the communication flow path from the adsorption tower in the depressurization step is introduced into the adsorption tower in the washing step, and the helium concentration of the raw material helium gas The predetermined correspondence relationship of is stored in the control device, in order to control the on-off valve to execute the washing step only at the execution time memorized by the control device, and the flow control valve is used to change the above based on the correspondence relationship. The opening degree of the communication flow path is such that the amount of gas that is blown from the adsorption tower in the depressurization step and introduced into the adsorption tower in the cleaning step is reduced to the helium concentration detected by the sensor So high. The helium purification system of claim 10, wherein each of the on-off valves is controlled by the control device to be in any of the adsorption towers in a state after the first gas blowing step and before the second gas blowing step Among them, the decompression step for reducing the internal pressure is performed, and at the same time, in any one of the adsorption towers in the state after the desorption step and before the second gas introduction step, the decompression step is carried out A cleaning step of discharging the internal gas of the adsorption tower as exhaust gas, and having a sensor that detects the helium concentration of the raw material helium gas and is connected to the control device, and the execution time of the cleaning step and the raw material helium gas The predetermined correspondence between the helium concentrations in is stored in the control device, and the control device is used to change the execution time of the washing step based on the correspondence so that the adsorption tower that is in the decompression step is subjected to The amount of gas blown and introduced into the adsorption tower in the washing step is reduced to a level as high as the helium concentration detected by the sensor. The helium purification system according to any one of claims 10 to 12, which controls each of the on-off valves using the control device to be in a state after the first gas blowing step and before the second gas blowing step In any of the adsorption towers, a decompression step for reducing the internal pressure is performed, and in any of the adsorption towers in a state after the desorption step and before the second gas introduction step, the introduction is performed The washing step in which the internal gas of the adsorption tower in the depressurization step is discharged as exhaust gas. The helium purification system according to any one of claims 10 to 14 includes a reuse flow path for connecting the exhaust gas flow path and the raw material gas introduction flow path. The helium purification system according to claim 15 is provided with a reuse flow path for connecting the exhaust gas flow path and the raw material gas introduction flow path.

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