JP7112446B2 - How to operate a gas purifier - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method of operating a gas purifier, and more particularly, to a method of operating a gas purifier that purifies hydrogen or helium by the PSA method at startup.

A PSA (Pressure Swing Adsorption) type gas purifier is generally an adsorption tower filled with an adsorbent that adsorbs impurities. step) and a regeneration step in which the adsorbed impurities are desorbed from the adsorbent at low pressure to purify the gas. Further, when a plurality of adsorption towers are provided, continuous gas purification is possible by alternately repeating the adsorption step and the regeneration step with different timings for each adsorption tower.

In particular, the VPSA (Vacuum Pressure Swing Adsorption) type, in which the regeneration step is performed at a pressure lower than atmospheric pressure, can obtain high separation performance even if the adsorption pressure in the adsorption step is low compared to the normal PSA type. Therefore, it is often used, for example, in the case of generating hydrogen that involves risks in compression operations.

In both PSA and VPSA type gas purifiers, once the operation is stopped, the impurities that were adsorbed to the adsorbent during the stop period diffuse away from the adsorbent. Therefore, when the operation is restarted, the diffused impurities flow to the supply side of the refined gas, and the purity of the refined gas is lowered. For this reason, it took a long time for the refined gas to reach the target purity.

In response to this, a method has been proposed in which the concentration of impurities in the adsorption tower that has completed the adsorption process is reduced in advance when the operation is stopped, and the impurity diffusion is suppressed when the operation is restarted (for example, patent Reference 1). Specifically, the residual gas in the adsorption tower during the adsorption process is sent to the adsorption tower during the regeneration process to equalize the pressure in both adsorption towers, and the gas is discharged from the adsorption tower during the adsorption process. The concentration of impurities in the adsorption tower is reduced by depressurizing to reduce the pressure.

JP 2009-154079 A

However, in the method of Patent Document 1, impurities are contained in the gas (pressure equalization gas) flowing from the adsorption tower in the adsorption step to the adsorption tower in the regeneration step due to the pressure equalization operation. In addition, not all the impurities that flowed in are desorbed from the adsorption tower only by the depressurization operation. However, it was not possible to completely prevent the diffusion of impurities after stopping the operation.

In addition, there is also a problem that the concentration of impurities in the adsorption tower cannot be reduced because the pressure equalization operation and the depressurization operation cannot be performed during an emergency shutdown due to a power failure or the like.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a method of operating a gas purifier that can quickly increase the purity of purified gas obtained immediately after the start of operation.

In order to achieve the above object, a first method for operating a gas purifier according to the present invention includes one or more adsorption towers and a vacuum pump, and adsorbs and removes impurities from a raw material gas in the adsorption towers by a PSA method. A method for operating a gas purifier in which gas purification is performed by repeating a purification step to obtain a purified gas and a regeneration step to desorb impurities adsorbed from the adsorption tower, wherein at the start of operation, the purification step is performed next. An evacuation treatment step of evacuating the inside of the adsorption tower to be evacuated by the vacuum pump, and a pressurization treatment step of supplying the raw material gas until the internal pressure reaches a pressure at which impurities are adsorbed. is characterized by

Further, in order to achieve the above object, a second method for operating a gas purifier according to the present invention includes one or more adsorption towers and a vacuum pump, and removes impurities from the raw material gas in the adsorption towers by a PSA method. A method of operating a gas purifier for performing gas purification by repeating a refining step of adsorbing/removing gas to obtain a purified gas and a regeneration step of desorbing impurities adsorbed from the adsorption tower, the method comprising: An evacuation treatment step of evacuating the inside of the adsorption tower in which the purification step is performed by the vacuum pump, and a purified gas or the same type and the same purity or higher as the purified gas until the internal pressure reaches a pressure at which impurities are adsorbed. and a pressure treatment step for supplying the product gas of .

Further, in the evacuation treatment step, a purified gas is supplied from above to the adsorption tower being evacuated, and the purified gas obtained from the gas purification device is hydrogen or helium. there is

According to the present invention, even if the raw material gas remaining in each adsorption tower diffuses during shutdown and impurities are adsorbed in the adsorption tower before the refining process, before restarting operation, Since the adsorbed impurities are removed and the impurities can be immediately adsorbed, the purity of the purified gas obtained immediately after the start of operation can be quickly increased.

BRIEF DESCRIPTION OF THE DRAWINGS It is a system diagram which shows the structure of the gas purification apparatus to which the example of one form of this invention is applied. FIG. 2 is a time chart showing an example of a valve sequence of the gas purifier of FIG. 1; FIG. FIG. 2 is a block diagram showing processing before and after starting the gas purifier of FIG. 1; FIG. 4 is a system diagram showing a gas flow in the evacuation process of FIG. 3; FIG. 4 is a system diagram showing a gas flow of pressurization processing when supplying the raw material gas in FIG. 3 ; FIG. 4 is a system diagram showing a gas flow of pressurization processing when supplying purified gas in FIG. 3 ; FIG. 4 is a graph showing experimental results comparing the difference in gas refining speed with and without the pre-operation treatment of FIG. 3 ; FIG. FIG. 2 is a system diagram showing the configuration of a gas purifier to which another embodiment of the present invention is applied; FIG. 10 is a system diagram showing the gas flow of the evacuation process in the gas purifier of FIG. 9; FIG. 10 is a system diagram showing a gas flow of pressurization processing when supplying raw material gas in the gas purifier of FIG. 9 ; FIG. 10 is a system diagram showing a gas flow of pressurization processing when supplying purified gas in the gas purifier of FIG. 9 ;

FIG. 1 is a system diagram showing the configuration of a gas purifier 11 to which one embodiment of the present invention is applied. The gas purifier 11 is a device that separates impurities from a source gas containing hydrogen or helium by the PSA method to obtain high-purity hydrogen or helium as a purified gas.

As shown in FIG. 1, the gas purifier 11 includes three adsorption towers 12 (adsorption tower 12a, adsorption tower 12b, and adsorption tower 12c) filled with an adsorbent that adsorbs impurities. In addition to receiving the supply of raw material gas from the adsorption tower 12, the off-gas discharged in the regeneration process or the like is sent to the off-gas discharge unit 14, and the purified gas supplied from the adsorption tower 12 in the purification process is temporarily stored in the purified gas storage tank 15. , and then sent to the product gas supply unit 16 as product gas.

A specific piping configuration of the gas purifier 11 is as follows. Each adsorption tower 12 (12a, 12b, 12c) has a lower pipe 17 (17a, 17b, 17c) at its lower end and an upper pipe 18 (18a, 18b, 18c) at its upper end. ing.

Pressure gauges 19 (19a, 19b, 19c) for detecting the gauge pressure in the adsorption tower 12 are attached to the respective upper pipes 18 (18a, 18b, 18c). The refined gas storage tank 15 is also provided with a pressure gauge 19d for detecting the gauge pressure inside the tank.

A source gas supply line 20 is connected to the source gas supply source 13, and source gas branch lines 20a, 20b, and 20c branch off from the source gas supply line 20 and extend therefrom. The raw gas branch line 20a connects to the lower pipe 17a of the adsorption tower 12a, the raw gas branch line 20b connects to the lower pipe 17b of the adsorption tower 12b, and the raw gas branch line 20c connects to the lower pipe 17c of the adsorption tower 12c. connected to.

An offgas discharge line 21 is connected to the offgas discharge portion 14, and offgas branch lines 21a, 21b, and 21c extend from the offgas discharge line 21, respectively. The offgas branch line 21a is connected to the lower pipe 17a of the adsorption tower 12a, the offgas branch line 21b is connected to the lower pipe 17b of the adsorption tower 12b, and the offgas branch line 21c is connected to the lower pipe 17c of the adsorption tower 12c. ing.

A vacuum pump 22 is attached to the offgas discharge line 21, and the inside of each adsorption tower 12 (12a, 12b, 12c) can be evacuated.

The refined gas storage tank 15 and the product gas supply unit 16 are connected via a product gas supply line 23. The refined gas storage tank 15 is provided with a refined gas delivery line 24, a regeneration gas supply line 25, and an equalizer. A pressurized/charged gas delivery line 26 is connected.

The regeneration gas supply line 25 is attached with a flow rate regulator 27 for adjusting the flow rate of the purification gas supplied as the regeneration gas from the purification gas storage tank 15. A needle valve 28 is attached to turn on and off the delivery of purified gas supplied as pressurized gas from the gas storage tank 15 .

Purified gas branch lines 24a, 24b, and 24c extend from the purified gas delivery line 24. The purified gas branch line 24a is connected to the upper pipe 18a of the adsorption tower 12a, and the purified gas branch line 24b is connected to the adsorption tower 12b. The purified gas branch line 24c is connected to the upper pipe 18c of the adsorption tower 12c.

Regenerated gas branch lines 25a, 25b, and 25c extend from the regenerated gas supply line 25. The regenerated gas branch line 25a is connected to the upper pipe 18a of the adsorption tower 12a. The regeneration gas branch line 25c is connected to the upper pipe 18c of the adsorption tower 12c.

From the pressure equalization/pressure gas distribution line 26, pressure equalization/pressure gas branch lines 26a, 26b, and 26c extend, respectively, and the pressure equalization/pressure gas branch line 26a is connected to the upper pipe 18a of the adsorption tower 12a. The pressure equalization/pressure gas branch line 26b is connected to the upper pipe 18b of the adsorption tower 12b, and the pressure equalization/pressure gas branch line 26c is connected to the upper pipe 18c of the adsorption tower 12c.

Raw material gas main valves Va1, Vb1, and Vc1 are attached to the raw material gas branch lines 20a, 20b, and 20c, respectively. Offgas main valves Va2, Vb2, and Vc2 are attached to the offgas branch lines 21a, 21b, and 21c, respectively.

Refined gas main valves Va3, Vb3, Vc3 are attached to the refined gas branch lines 24a, 24b, 24c, respectively. Regenerated gas main valves Va4, Vb4 and Vc4 are attached to the regenerated gas branch lines 25a, 25b and 25c, respectively. Equalization/pressure gas branch lines 26a, 26b, and 26c are provided with equalization/pressure gas source valves Va5, Vb5, and Vc5, respectively.

The gas purifier 11 is provided with a controller 29 capable of controlling the operation of the gas purifier 11 . The control unit 29 can operate the vacuum pump, the flow rate regulator 27, the needle valve 28, each valve (source gas source valves Va1, Vb1, Vc1, off-gas source valves Va2, Vb2, Vc2, refined gas source valves Va2, Vb2, Vc2). Valves Va3, Vb3, Vc3, regeneration gas source valves Va4, Vb4, Vc4, pressure equalization/charge gas source valves Va5, Vb5, Vc5) are configured to be controllable.

Further, the control unit 29 is set to operate the gas purifier 11 based on a preset operation schedule.

FIG. 2 is a time chart showing an example of a valve sequence during normal operation of the gas purifier 11. As shown in FIG. The hatched period in FIG. 2 indicates the state in which the valve is open, and the non-shaded period indicates the state in which the valve is closed.

As shown in FIG. 2, the control unit 29 of the gas purifier 11 in FIG. 1 performs a purification process in each of the adsorption towers 12a, 12b, and 12c based on a preset operation schedule, and The regeneration process, the charging process, and the pressure equalizing process are set to be repeated in a predetermined order and at time intervals.

More specifically, the adsorption tower 12a, the adsorption tower 12b, and the adsorption tower 12c undergo [T1: purification step, pressure filling step, regeneration step → T2: pressure equalization step, purification step, pressure equalization step → T3: regeneration step, purification step, pressure equalization step → T4: pressure equalization step, pressure equalization step, purification step → T5: pressure charge step, regeneration step, purification step →T6: purification step, pressure equalization step, pressure equalization step] , and after the period T6, the process of the period T1 is started again.

In the refining process, the raw material gas main valve Va1 (or Vb1, Vc1) and the refined gas main valve Va3 (or Vb3, Vc3) are opened, so that the raw material gas flows into the adsorption tower 12a (or 12b, 12c). 1, impurities are adsorbed/removed under the pressure at which the adsorbent adsorbs impurities (hereinafter referred to as adsorption pressure), and sent as a refined gas to the refined gas storage tank 15 in FIG.

In the regeneration step, the regeneration gas main valve Va4 (or Vb4, Vc4) and the offgas main valve Va2 (or Vb2, Vc2) are opened, so that the inside of the adsorption tower 12 is evacuated and the refined gas storage tank is opened. Purified gas flows in from 15 as regeneration gas, impurities adsorbed in the adsorption tower 12 are desorbed from the adsorption tower 12 and discharged from the adsorption tower 12 together with the raw material gas remaining in the adsorption tower 12 .

In the pressure charging step, the needle valve 28 in FIG. 1 is opened together with the equalizing/pressure gas main valve Va5 (or Vb5, Vc5) until the adsorption pressure in the adsorption tower 12a (or 12b, 12c) is reached. Purified gas is introduced.

In the pressure equalization step, two of the pressure equalization/pressure gas main valves Va5, Vb5, and Vc5 are opened, so that both adsorption towers 12 are are communicated to equalize the pressure.

FIG. 3 is a block diagram showing the processing before and after starting the gas purifier 11. As shown in FIG. As shown in FIG. 3, the control unit 29 of the gas purification device 11 in FIG. The adsorption tower 12 is set to start normal operation after successively performing the evacuation process 30 and the pressurization process 31 .

Here, the evacuation process 30 is a process of venting the adsorption tower 12 with the offgas discharge line 21 and discharging the gas inside the adsorption tower 12 by the vacuum pump 22. For example, the pressure in the adsorption tower 12 is reduced to -80 kPaG. Continue until decompression.

The pressurization process 31 is a process of introducing the source gas from the source gas supply line 20 into the adsorption tower 12 until the adsorption pressure reaches the adsorption tower 12, for example, until the pressure in the adsorption tower 12 is increased to 70 kPaG. Continued.

FIG. 4 is a system diagram showing the gas flow of the evacuation process 30 in FIG. 3, and FIG. 6 is a system diagram showing the gas flow of the pressurization process 31 when supplying the refined gas in FIG.

In FIGS. 4-6, open valves are white, closed valves are black, ventable lines are solid lines, and non-ventable lines are dashed lines.

As shown in FIG. 4, when the vacuum evacuation process 30 of FIG. is drawn into the adsorption tower 12a, and the gas in the adsorption tower 12a is drawn out as offgas to the offgas discharge section 14 by the vacuum pump 22, and the raw material gas and impurities remaining in the adsorption tower 12a are discharged. The evacuation process may be performed without regeneration gas, or the regeneration gas main valve Va4 may be closed.

As shown in FIG. 5, when the adsorption tower 12a is subjected to the pressure treatment 31 of FIG. The feed gas is introduced until the pressure of reaches the adsorption pressure.

Regarding the pressurization process 31, instead of introducing the raw material gas from the raw material gas supply line 20 to the adsorption tower 12 until the adsorption pressure is reached, the purified gas is supplied from the purified gas storage tank 15 to the adsorption tower 12 at the adsorption pressure. You may introduce it until it becomes. The use of purified gas contributes to rapid gas purification after the start of operation, since impurities contained in the raw material gas are not mixed into the adsorption tower.

In this case, as shown in FIG. 6, when the pressurization process 31 in FIG. Purified gas is introduced from 15 into the adsorption tower 12a until the internal pressure reaches the adsorption pressure.

FIG. 7 is a graph showing the results of an experiment comparing the difference in gas refining speed with and without the pre-operation treatment of FIG. In this experiment, the raw material gas consisted of 75% hydrogen (H2) gas and 25% nitrogen (N2) gas, and the gas purifier 11 was intended to purify the hydrogen gas.

The vertical axis in FIG. 7 represents the concentration of nitrogen gas, which is an impurity contained in the purified gas obtained in the purification process after the start of the gas purification device 11, in logarithmic representation, and the horizontal axis represents the concentration of the gas purification device 11. It represents the operation time after starting.

Further, each data in FIG. 7 shows the time change of the purity of the purified gas obtained by resuming the operation from the period T6 after the gas purifier 11 stops the operation after the period T5 in the valve sequence of FIG. is measured and plotted with and without pre-operation treatment and under different conditions, and is extrapolated by an approximation curve so that the predicted value can be calculated.

For the first data series and the second data series, the operating gas purifier 11 is temporarily stopped when the process of the period T5 is completed, and after three months have passed, it is started and data acquisition is started. is doing.

The first data series is the data when the process of period T6 is started without pre-operation treatment after startup, and the second data series is the data when the adsorption tower is treated as pre-operation treatment after startup. 12a is depressurized to −80 kPaG for 15 minutes by the evacuation process 30, and then the raw material gas is introduced into the adsorption tower 12a until the pressure in the tower reaches 70 kPaG, and then the process of period T6 is started. data.

In the third data series and the fourth data series, the operating gas purifier 11 is temporarily stopped when the process of period T5 is completed, each adsorption tower 12 is evacuated, and each adsorption tower 12 is Nitrogen gas was filled until the pressure reached 70 kPaG, and after 20 hours had elapsed, the system was started and data acquisition was started.

The third data series is the data when the process of period T6 is started without pre-operation treatment after startup, and the fourth data series is the data when the adsorption tower is treated as pre-operation treatment after startup. 12a is depressurized to −80 kPaG for 15 minutes by the evacuation process 30, and then the raw material gas is introduced into the adsorption tower 12a until the pressure in the tower reaches 70 kPaG, and then the process of period T6 is started. data.

As shown in FIG. 7, when comparing the first data series and the second data series, the time required to obtain hydrogen gas with a purification purity of 99.999% or more in the startup operation after a long-term shutdown of 3 months However, about 13 hours were required for the first data series without pre-driving processing, while the second data series with pre-driving processing was shortened to about 5 hours.

In addition, when comparing the third data series and the fourth data series, even under the condition that each adsorption tower 12 is filled with nitrogen gas before startup, as at the time of device delivery, the purification purity is 99.99%. It is estimated that it took about 10 hours to obtain the above hydrogen gas in the third data series without pre-operation treatment, while in the fourth data series with pre-operation treatment shortened to about 10 minutes.

As can be seen from the comparison between the first data series and the second data series, when resuming the temporarily stopped operation, the inside of the adsorption tower 12 in which the purification process is performed next is evacuated by the vacuum pump 22. After that, by supplying the raw material gas until the internal pressure reaches the adsorption pressure, the raw material gas remaining in each adsorption tower 12 during shutdown diffuses and is adsorbed in the adsorption tower 12 before the purification step. It is now possible to shorten the time required for the purity of the purified gas to stabilize due to the impurities that were previously present.

In addition, as can be seen from the comparison between the third data series and the fourth data series, even under conditions where the adsorption tower is filled with nitrogen gas, such as when the equipment was delivered, it is necessary to stabilize the purity of the purified gas. time can be shortened, it can be seen that the operation method of the gas purifier of the present invention is also effective for operation immediately after delivery.

FIG. 8 is a system diagram showing the configuration of a gas purifier 41 to which another embodiment of the invention is applied.

As shown in FIG. 8, the gas purifier 41 separates impurities from the raw material gas containing hydrogen or helium by the PSA method in the same manner as the gas purifier 11 in FIG. As for the apparatus to be obtained, there are two adsorption towers 12, an adsorption tower 12a and an adsorption tower 12b, which differ in that the pressure equalization/pressure gas delivery line 26 is not provided.

In addition, the control unit 29 of the gas purification device 41 is set to perform the same processing as the processing before and after the startup of the gas purification device 11 shown in FIG. When restarting the operation, as a pre-operation process, the adsorption tower 12, which is to be subjected to the next purification process, is subjected to the evacuation process 30 and the pressurization process 31 in succession, and then normal operation is started. is set to

FIG. 9 is a system diagram showing the gas flow of the evacuation process 30 in the gas purifier 41, and FIG. 10 shows the gas flow of the pressurization process 31 in the gas purifier 41 of FIG. FIG. 11 is a system diagram showing the gas flow of the pressurization process 31 when supplying the purified gas in the gas purifier 41 of FIG.

In FIGS. 9-11, open valves are white, closed valves are black, ventable lines are solid lines, and non-ventable lines are dashed lines.

As shown in FIG. 9, when the vacuum evacuation process 30 is performed on the adsorption tower 12a, the off-gas main valve Va2 and the regeneration gas main valve Va4 are opened, and the purified gas is discharged from the purified gas storage tank 15 to the adsorption tower. At the same time, the vacuum pump 22 draws the gas in the adsorption tower 12a as an offgas to the offgas discharge section 14, and the raw material gas and impurities remaining in the adsorption tower 12a are discharged.

As shown in FIG. 10, when the adsorption tower 12a is subjected to the pressure treatment 31 of FIG. The feed gas is introduced until the pressure of reaches the adsorption pressure.

As shown in FIG. 11, when the pressurization process 31 of FIG. 3 is performed on the adsorption tower 12a with the purified gas, the regeneration gas main valve Va4 is opened, and the internal gas from the purified gas storage tank 15 to the adsorption tower 12a Purified gas is introduced until the pressure of reaches the adsorption pressure.

As described above, according to the method of operating the gas purifiers 11 and 41 of the present invention, when resuming the temporarily stopped operation, the inside of the adsorption tower 12, which is next subjected to the purification process, is vacuumed by the vacuum pump 22. After evacuating, the raw material gas or refined gas is supplied until the internal pressure reaches the adsorption pressure.

Therefore, even if the raw material gas remaining in each adsorption tower 12 diffuses during shutdown and impurities are adsorbed in the adsorption tower 12 before the refining process, the impurities are adsorbed before restarting the operation. Since the impurities are removed and the impurities can be immediately adsorbed, the purity of the purified gas obtained immediately after the start of operation can be quickly increased.

It should be noted that the present invention is not limited to the above embodiments, and various modifications are possible within the scope of the invention. For example, in this embodiment, two or three adsorption towers are provided in the gas purifier, but the number of adsorption towers is not necessarily limited to two or three. Any number including

In addition, in this embodiment, in the evacuation process, only the adsorption tower for the next purification step is evacuated. Next, the other adsorption towers may be evacuated together with the adsorption tower for the purification step, or all the adsorption towers may be evacuated.

In addition, in the present embodiment, the source gas or the refined gas is supplied to the adsorption tower in the pressurization treatment, but if the pressure inside the adsorption tower can be increased to the adsorption pressure, another gas can be supplied. Alternatively, for example, it may be supplied from a cylinder filled with a product gas of the same kind and purity as the refined gas. In this case also, similar to the purified gas, introduction from the upper part of the adsorption tower contributes to rapid gas purification.

The reason why hydrogen or helium is used as the object to be purified by the gas purifier to which the operating method of the present invention is applied is that if the molecular diameter is large, it takes time to evacuate. This is because the effects of the present invention can be fully exhibited in hydrogen or helium, which have small molecular diameters.

DESCRIPTION OF SYMBOLS 11... Gas purification apparatus 12... Adsorption tower 12a... Adsorption tower 12b... Adsorption tower 12c... Adsorption tower 13... Source gas supply source 14... Off-gas discharge part 15... Refined gas storage tank 16... Product gas supply part 17 (17a, 17b, 17c) ... Lower piping 18 (18a, 18b, 18c) ... Upper piping 19 (19a, 19b, 19c, 19d) ... Pressure gauge 20 ... Raw material gas supply line 20a, 20b, 20c ... Raw material gas branch line 21 ... Off-gas discharge line 21a, 21b, 21c... Offgas branch line 22... Vacuum pump 23... Product gas supply line 24... Purified gas delivery line 24a, 24b, 24c... Purified gas branch line 25... Regenerated gas supply line 25a, 25b, 25c... Regenerated gas branch Line 26 Pressure equalization/charged gas delivery line 26a, 26b, 26c Pressure equalization/charged gas branch line 27 Flow rate regulator 28 Needle valve 29 Control section 30 Evacuation process 31 Pressurization process 41 gas purifier

Va1, Vb1, Vc1... Source gas main valve Va2, Vb2, Vc2... Off gas main valve Va3, Vb3, Vc3... Refined gas main valve Va4, Vb4, Vc4... Regeneration gas main valve Va5, Vb5, Vc5... Pressure equalization/charging gas valve

Claims (4)

Equipped with one or more adsorption towers and a vacuum pump, a purification step in which impurities are adsorbed and removed from the raw material gas by the PSA method to obtain a purified gas by the adsorption towers, and a regeneration step in which the impurities adsorbed from the adsorption towers are desorbed. A method of operating a gas purifier for gas purification by repeating the steps of
At the start of operation, an evacuation treatment step of evacuating the interior of the adsorption tower, which is to be subjected to the purification step next, by the vacuum pump, and supplying the raw material gas until the internal pressure reaches a pressure at which impurities are adsorbed. A method for operating a gas purifier, characterized in that a pressure treatment step is performed in order. Equipped with one or more adsorption towers and a vacuum pump, a purification step in which impurities are adsorbed and removed from the raw material gas by the PSA method to obtain a purified gas by the adsorption towers, and a regeneration step in which the impurities adsorbed from the adsorption towers are desorbed. A method of operating a gas purifier for gas purification by repeating the steps of
At the start of operation, an evacuation treatment step of evacuating the inside of the adsorption tower where the purification step is performed next by the vacuum pump, and a purified gas or purified gas until the internal pressure reaches a pressure at which impurities are adsorbed and a pressurization step of supplying a product gas of the same kind and purity or higher. 3. The method of operating a gas purifier according to claim 1, wherein, in said evacuation treatment step, a purified gas is supplied from above to said adsorption tower being evacuated. 4. The method of operating a gas purifier according to any one of claims 1 to 3, wherein the refined gas obtained from the gas purifier is hydrogen or helium.

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