TW201821147A - Method for purifying hydrogen or helium, and device for purifying hydrogen or helium - Google Patents

Abstract

This method that purifies hydrogen or helium from a source gas mainly composed of hydrogen or helium and including volatile aromatic compounds as impurities by using a PSA technique performed using adsorption towers (10A to 10C) filled with absorbents repeats a cycle that includes an adsorption step, a depressurization step, a desorption step, and a cleaning step in the adsorption towers (10A to 10C). The adsorption towers (10A to 10C) are divided into a first region, a second region, and a third region in order from the upstream side to the downstream side in a flow direction of the source gas in the adsorption towers. The first region is filled with a silica gel-based first adsorbent 131 having a fill ratio of 15 to 75 vol% relative to the total fill capacity of adsorbents. The second region is filled with a zeolite-based second adsorbent 132 having a fill ratio of 15 to 75 vol%. The third region is filled with an activated carbon-based third adsorbent 133 having a fill ratio of 5 to 30 vol%.

Description

   Method for refining hydrogen or helium and device for refining hydrogen or helium   

The invention relates to a method and a device for refining hydrogen or helium by using a pressure swing adsorption method.

From the viewpoint of pollution prevention, the concentration of volatile aromatic compounds in the gas discharged as exhaust gas is regulated to a low concentration. For example, in the case of a gas containing toluene as an impurity, a certain area has a ground reaching point concentration of 0.7 volppm or less. As a treatment method for the exhaust gas corresponding to such regulations, there may be an absorption method, a cooling method, an adsorption method, a combustion method, and the like (for example, refer to Patent Document 1). In addition, there may be a case where the gas purified by these processes is recovered and reused. In addition, as for an exhaust gas treatment facility, a method that saves space, and has a low introduction cost and operating cost is pursued.

On the other hand, when hydrogen or helium is used as an industrial gas, depending on the application, an additional purification step is necessary in order to obtain a high-purity gas. For example, in the case of hydrogen for a fuel cell vehicle, according to ISO14687-2 (FCV hydrogen fuel specifications, 2012, GradeD) as the allowable concentration of components other than hydrogen, it is necessary to use a total hydrocarbon of 2 volppm or less (equivalent to methane). In this case, space-saving and cheap methods are also pursued. It is difficult to remove hydrocarbons by an absorption method so that the concentration of hydrocarbons in the diffusion gas is 1 vol% or less, which has not yet been achieved. In the cooling method, impurities in the vapor pressure fraction remain on the gas phase side, and it is difficult to purify them to a few ppm level in the case of volatile aromatic compounds. In the combustion method, it is necessary to mix oxygen and the like, and water or carbon dioxide is generated after combustion, so it is not suitable for obtaining high-purity gas.

For the reasons described above, as a method of obtaining high-purity hydrogen or helium, an adsorption method is mainly used. For example, in order to remove volatile aromatic compounds contained in a gas, a pressure swing adsorption method using a synthetic zeolite or a hydrophobic silica gel is used. However, since this method uses a vacuum device for desorption or uses hydrophobicity in silica-rich zeolite or silica gel, there is a problem in terms of cost (for example, refer to Patent Document 1).

In addition, there is also a method of using a pressure swing adsorption method to treat an exhaust gas containing a volatile aromatic compound and reduce a hydrocarbon concentration. If regeneration of the adsorbent is possible by pressure swing adsorption, no heating or cooling is required. However, in this method, a vacuum device is required for desorption, and furthermore, the up-front cost of starting the adsorbent is required, which becomes a problem in terms of cost or complicated operation (for example, refer to Patent Documents 2 and 3).

In the case of purifying a gas containing a volatile aromatic compound as an impurity, a method using activated carbon as an adsorbent has conventionally been used. Volatile aromatic compounds entering the pores of activated carbon are not easily desorbed. Therefore, a method for heating by desorption is adopted, and desorption is promoted by a temperature swing adsorption method or the use of steam. In the case of using a heating means, additional equipment is required along with heating or cooling, and there are many problems in operability such as time required for heat conduction.

Furthermore, the method using the vacuum regeneration method requires a cost for the vacuum regeneration. In addition, in the method using a purge gas (refined high-purity product gas), the use share of the purge gas is also linked to rising costs. Furthermore, with regard to regeneration by heating, the share of energy necessary for the same heating is also linked to rising costs.

    [Previous Technical Literature]         [Patent Literature]    

[Patent Document 1] Japanese Patent Publication No. 9-47635

[Patent Document 2] Japanese Patent Publication No. 11-71584

[Patent Document 3] Japanese Patent Publication No. 2004-42013

The present invention has been conceived based on such matters, and an object thereof is to provide a hydrogen or helium having a reduced cost and a high purity from a source gas containing a volatile aromatic compound as an impurity by a pressure swing adsorption method. Method and device.

According to the first aspect of the present invention, it is provided to repeat the pressure swing adsorption cycle for each adsorption tower by using three or more adsorption towers filled with an adsorbent, and to include a volatile aromatic compound as an impurity. A method for refining hydrogen or helium by using a source gas containing hydrogen or helium as a main component. The cycle includes an adsorption step of using a pressure swing adsorption method using three or more adsorption towers filled with an adsorbent to bring the adsorption tower to a predetermined high pressure state, and introducing the raw material gas into the adsorption tower to make the adsorption tower The volatile aromatic compounds in the raw material gas are adsorbed on the adsorbent, and a product gas having a high concentration of hydrogen or helium is discharged from the adsorption tower; and the pressure-reducing step is performed by the adsorption tower exhausting the residue remaining in the tower. Gas to reduce the pressure in the tower; in the desorption step, the volatile aromatic compound is desorbed by the adsorbent in the adsorption tower that has completed the decompression step, and the gas in the tower is discharged; in the cleaning step, the pressure in the tower is reduced. The gas discharged from other adsorption towers in the step is introduced into the adsorption tower that has completed the desorption step to discharge the gas remaining in the tower. The flow direction of the raw material gas of each of the adsorption towers in the adsorption tower is sequentially divided into a first region, a second region, and a third region from an upstream side to a downstream side. The first region is filled with a silicone-based first adsorbent having a filling ratio in a range of 15 to 75 vol%. The second region is filled with a second zeolite-based adsorbent having a filling ratio in a range of 15 to 75 vol%. The third region is filled with an activated carbon-based third adsorbent having a filling ratio in a range of 5 to 30 vol%.

The first adsorbent is preferably made of a hydrophilic silicone.

According to a second aspect of the present invention, there is provided an apparatus for purifying hydrogen or helium from a source gas containing a volatile aromatic compound as an impurity and hydrogen or helium as a main component. The device includes: an adsorption tower of 3 or more towers, each of which has a first gas passage and a second gas passage, and an adsorbent is filled between the first gas passage and the second gas passage; a storage tank is used for Store product gas; gas-liquid separation means that separates the gas discharged from the first gas passage port of the adsorption tower into a gas phase component and a liquid phase component; a first pipeline having a main line connected to a source of a raw gas supply, and an individual line A plurality of branch lines provided on the adsorption tower and connected to the adsorption tower, the first gas passing port side being individually provided with an on-off valve; a second pipeline having a main line provided with the gas-liquid separation means; A plurality of branch lines of the adsorption tower connected to the adsorption tower, the first gas passing port side being individually provided with an on-off valve; a third pipeline having a trunk line provided with the storage tank, and individually installed in the adsorption tower and A plurality of branch lines of the second gas passing port that are connected to the adsorption tower and are individually provided with on-off valves; a fourth line having a connection to the third line The main line of the main line, and a plurality of branch lines that are individually installed in the adsorption tower and connected to the adsorption tower and the second gas passing port side are individually provided with on-off valves; the fifth line has a connection to the fourth line A trunk line of the trunk line, and a plurality of branch lines each provided on the adsorption tower and connected to the adsorption tower, and the second gas passing port side are individually provided with on-off valves. Each of the adsorption towers is sequentially divided into a first region, a second region, and a third region from the first gas passage to the second gas passage in the adsorption tower. The first region is filled with a silicone-based first adsorbent having a filling ratio in a range of 15 to 75 vol%. The second region is filled with a second zeolite-based adsorbent having a filling ratio in a range of 15 to 75 vol%. The third region is filled with an activated carbon-based third adsorbent having a filling ratio ranging from 5 to 30 vol%.

The first adsorbent is preferably made of a hydrophilic silicone.

The inventors of the present invention conducted a diligent review on a method for separating hydrogen or helium from a raw material gas containing a volatile aromatic compound as an impurity by a pressure swing adsorption method, and found that the rear stage of the silica gel, which adsorbs the volatile aromatic compound, is not filled After the adsorption process of zeolite and activated carbon adsorbing volatile aromatic compounds, the relatively clean gas in the zeolite and activated carbon layer is used to clean the adsorption tower after the desorption process. In some cases, a vacuum device or a heating device is not used, and a highly purified product gas can be obtained, thereby completing the present invention.

According to the present invention, the content of volatile aromatic compounds as impurities in hydrogen or helium can be reduced to 1 volppm or less with an inexpensive and space-saving device.

Other features and advantages of the present invention will be described in detail below with reference to the drawings to make it clearer.

X‧‧‧refining device

10A, 10B, 10C‧‧‧Adsorption tower

11‧‧‧ gas passage (first gas passage)

12‧‧‧ gas passage (second gas passage)

131‧‧‧The first adsorbent

132‧‧‧Second adsorbent

133‧‧‧3rd adsorbent

21‧‧‧ source of raw gas supply

22‧‧‧Product Storage Tank

23‧‧‧ exhaust tank

24‧‧‧Cooler (Gas-liquid separation means)

25‧‧‧Gas-liquid separator (gas-liquid separation means)

31‧‧‧Pipeline (Pipeline 1)

32‧‧‧ pipeline (second pipeline)

33‧‧‧ Pipeline (3rd pipeline)

34‧‧‧ Pipeline (4th pipeline)

35‧‧‧ pipeline (line 5)

31 ', 32', 33 ', 34', 35'‧‧‧ trunk

31A ~ 31C, 32A ~ 32C, 33A ~ 33C, 34A ~ 34C, 35A ~ 35C‧‧‧ branch line

31a ~ 31c, 32a ~ 32c, 33a ~ 33c, 34a ~ 34c, 35a ~ 35c, 341, 351‧‧‧Automatic valve

321, 331‧‧‧pressure regulating valve

342, 352‧‧‧Flow regulating valve

AS‧‧‧Adsorption Process

DP‧‧‧ Decompression process

DS‧‧‧ Desorption Process

RN‧‧‧Cleaning process

PR‧‧‧Boosting process

Eq-DP‧‧‧‧Equal pressure decompression process

Eq-DR‧‧‧ Equalizing voltage step-up process

FIG. 1 shows a schematic configuration of a refining device used for implementing a hydrogen refining method according to an embodiment of the present invention.

FIG. 2 shows a gas flow state in each step of the hydrogen purification method according to the embodiment of the present invention.

The following describes the preferred embodiments of the present invention in detail with reference to the drawings.

FIG. 1 shows a schematic configuration of a refining device X that can be used for implementing a refining method of hydrogen or helium according to the present invention. The refining device X includes three towers of absorption towers 10A, 10B, and 10C, a source gas supply source 21, a product storage tank 22, an exhaust tank 23, a cooler 24, a gas-liquid separator 25, and lines 31 to 35. The purification device X is configured to be capable of concentrating and separating hydrogen or helium from a source gas (crude hydrogen or crude helium) containing hydrogen or helium by a pressure swing adsorption method (PSA method). Examples of the source gas include hydrogen generated from an organic halide as a main component, and examples of the impurity include a gas containing a volatile aromatic compound (for example, toluene, benzene, methylcyclohexane, and the like). The following description is based on the case where the main component of the source gas is hydrogen, but the present invention is not limited to this, and can also be used when the main component of the source gas is helium.

The adsorption towers 10A, 10B, and 10C each have gas passage ports 11 and 12 at both ends, and an adsorbent is filled between the gas passage ports 11 and 12. Specifically, each of the interiors of the adsorption towers 10A, 10B, and 10C is divided into a plurality of (three) regions by a perforated plate (not shown), and these regions are individually filled with different adsorbents. In this embodiment, the first adsorbent 131 is sequentially stacked from the upstream side (gas passage port 11) to the downstream side (gas passage port 12) in the flow direction of the raw material gas in each of the adsorption towers 10A, 10B, and 10C. , A second adsorbent 132, and a third adsorbent 133.

As the first adsorbent 131, an adsorbent having a property of preferentially adsorbing a volatile aromatic compound is used. Examples of such adsorbents include silicone-based adsorbents (hydrophilic silicone, hydrophobic silicone, etc.). Among them, hydrophilic silicone is preferred, and silicone B is particularly preferred. Regarding the second and third adsorbents 132 and 133, an adsorbent having a relatively low adsorption energy of a volatile aromatic compound is used. Examples of the second adsorbent 132 include zeolite-based adsorbents (A-type zeolite, CaA-type zeolite, and Y-type zeolite), and among these, CaA-type zeolite is preferred. Examples of the third adsorbent 133 include activated carbon based materials such as coconut shell based and stone carbon based. These adsorbents are generally commercially available and do not require pretreatment. In addition, since the silicone (or silicon dioxide) has a hydroxyl group on the surface and is originally hydrophilic, it is made hydrophobic by subjecting it to high-temperature heating or a hydrophobizing treatment such as a reaction with an alkyl silicide. This hydrophobizing treatment has been a cause of increased cost in the past.

The first to third adsorbents 131, 132, and 133 are adjusted so as to have a predetermined filling ratio (volume ratio) with respect to the entire filling capacity of the adsorbent. Specifically, the filling ratio of the first adsorbent 131 is 15 to 75 vol%, preferably in the range of 15 to 65 vol%, and the filling ratio of the second adsorbent 132 is 15 to 75 vol%, preferably 25 to 75 vol%. In the range, the filling ratio of the third adsorbent 133 is 5 to 30 vol%, preferably 5 to 20 vol%. The total of the individual filling ratios of the first to third adsorbents 131, 132, and 133 was 100 vol%.

The raw material supply source 21 is a pressure vessel for storing a raw material gas supplied to the adsorption towers 10A, 10B, and 10C. The concentration of the volatile aromatic compound contained in the source gas is not particularly limited, but there is a concern that the volatile aromatic compound may be liquefied in the pipe depending on the pressure of hydrogen or helium and the concentration of the volatile aromatic compound. Therefore, it is preferable to heat the piping (the main line 31 'of the line 31 described later) from the source gas supply source 21 to the adsorption towers 10A, 10B, and 10C, and / or to heat the pipes at the adsorption towers 10A, 10B, and 10C. A mist trap and the like are provided on the previous main line 31 '. The pressure of the raw material gas supplied from the raw material gas supply source 21 is not particularly limited, but is preferably high pressure, and a compressor (not shown) may be installed on the main line 31 ′ if necessary. When hydrogen or helium supplied from the source gas supply source 21 contains water as an impurity, a moisture removal device (not shown) may be provided on the main line 31 'of the line 31. The operating temperature according to the PSA method is not particularly limited, and is, for example, about 10 to 40 ° C. However, it is preferable that it is the temperature (degree of normal temperature or more) to the extent that the volatile aromatic compound does not liquefy.

The product storage tank 22 is a pressure container for storing a gas (a product gas described later) discharged from the gas passage ports 12 of the adsorption towers 10A, 10B, and 10C.

The exhaust gas tank 23 is a pressure vessel for storing exhaust gas discharged from the gas passage openings 11 of the adsorption towers 10A, 10B, and 10C.

The cooler 24 cools the exhaust gas. The gas-liquid separator 25 condenses the exhaust gas passing through the cooler 24 under a predetermined pressure to separate it into a gas phase component and a liquid phase component. The term “gas-liquid separation means” includes the cooler 24 and the gas-liquid separator 25 described above.

The line 31 includes a main line 31 ′ connected to the source gas supply source 21, and branch lines 31A, 31B, and 31C connected to the respective gas passage ports 11 of the adsorption towers 10A, 10B, and 10C. The branch lines 31A, 31B, and 31C are provided with valves (a valve having such a function is hereinafter referred to as an "automatic valve") 31a, 31b, and 31c that can be automatically switched between an open state and a closed state.

The line 32 includes a main line 32 ′ provided with a cooler 24 and a gas-liquid separator 25, and branch lines 32A, 32B, and 32C connected to the respective gas passage ports 11 of the adsorption towers 10A, 10B, and 10C. Further, an exhaust gas groove 23 is provided on the trunk line 32 ′ upstream of the cooler 24. A pressure regulating valve 321 is provided between the exhaust gas groove 23 of the main line 32 ′ and the cooler 24. The branch lines 32A, 32B, and 32C are provided with automatic valves 32a, 32b, and 32c.

The line 33 includes a main line 33 ′ provided with the product storage tank 22, and branch lines 33A, 33B, and 33C connected to the gas passage ports 12 of the adsorption towers 10A, 10B, and 10C, respectively. The branch lines 33A, 33B, and 33C are provided with automatic valves 33a, 33b, and 33c. A pressure regulating valve 331 is provided on the downstream side of the product storage tank 22 of the main line 33 '.

The line 34 is used to supply a part of the product gas flowing through the line 33 (the main line 33 ') to the adsorption towers 10A, 10B, and 10C, and a main line 34' having a main line 33 'connected to the line 33, and individual connections Each gas in the adsorption towers 10A, 10B, and 10C passes through branch lines 34A, 34B, and 34C on the side of the port 12. An automatic valve 341 and a flow adjustment valve 342 are provided on the main line 34 '. The branch lines 34A, 34B, and 34C are provided with automatic valves 34a, 34b, and 34c.

The pipeline 35 is used to connect any two of the adsorption towers 10A, 10B, and 10C to each other. The pipeline 35 has a trunk line 35 'connected to the trunk line 34' of the pipeline 34, and gas passages connected to the adsorption towers 10A, 10B, and 10C. The branch lines 35A, 35B, and 35C on the 12 side. An automatic valve 351 and a flow adjustment valve 352 are provided on the main line 35 '. The branch lines 35A, 35B, and 35C are provided with automatic valves 35a, 35b, and 35c.

The purification method X of the embodiment of the present invention can be performed using the purification device X having the above-mentioned configuration. In the operation of the refining device X, by automatically switching the automatic valves 31a to 31c, 32a to 32c, 33a to 33c, 34a to 34c, 35a to 35c, 341, and 351, and the flow adjustment valves 342 and 352, The desired gas flow state can be repeated in a cycle consisting of steps 1 to 9 below. In one cycle of the method, an adsorption step, a decompression step, a pressure equalization pressure reduction, a desorption step, a cleaning step, a pressure equalization pressure increase, and a pressure increase step are performed in individual adsorption towers 10A, 10B, and 10C. Figures 2a to 2i are patterns showing the flow state of the gas in the purification device X in steps 1 to 9. In addition, in Figs. 2a to 2i, the following symbols are used.

AS: adsorption process

DP: Decompression process

DS: Desorption process

RN: cleaning process

PR: Boost process

Eq-DP: Equal pressure decompression process

Eq-DR: voltage equalization step-up process

Step 1 opens the automatic valves 31a, 33a, 32b, 34b, 35c, 351 and the flow adjustment valve 352 to achieve the gas flow state shown in FIG. 2a.

In the adsorption tower 10A, a raw material gas is introduced from a gas passage 11 through a line 31, and an adsorption process is performed. The predetermined high pressure state is maintained in the adsorption tower 10A in the adsorption process, and mainly volatile aromatic compounds in the raw material gas are adsorbed by the adsorbent in the adsorption tower 10A. Then, the hydrogen-concentrated gas (product gas) is discharged from the gas passage port 12 side of the adsorption tower 10A. The product gas is sent to the product storage tank 22 via the branch line 33A and the main line 33 '. The product gas in the product storage tank 22 is appropriately taken out of the system through the pressure regulating valve 331 and used for a desired application.

Here, the concentration of the volatile aromatics in the raw material gas introduced into the adsorption tower 10A is not particularly limited, but is, for example, about 100 vol ppm to 1 vol%. The maximum pressure (adsorption pressure) inside the adsorption tower 10A in the adsorption step is, for example, 0.1 to 1.0 MPaG (G is expressed as a gauge pressure, the same applies hereinafter), and preferably 0.5 to 0.8 MPaG.

In addition, the individual gas passage ports 12 of the adsorption towers 10B and 10C communicate with each other through the lines 34 and 35 in step 1. For example, if the adsorption tower 10B first performs the desorption step, and the adsorption tower 10C first performs the adsorption step (refer to step 9 shown in FIG. 2i), at the beginning of step 1, the pressure in the adsorption tower 10C is higher than that in the adsorption tower 10B. . Then, after the step 1 starts, the adsorption tower 10C is subjected to a decompression process. A gas having a low impurity concentration (residual concentrated hydrogen) remaining in the tower of the adsorption tower 10C is discharged from the gas passage 12 and the pressure in the tower is reduced. The difference between the pressure in the column of the adsorption column 10C at the beginning and the end of step 1 is, for example, about 300 kPa. On the other hand, the adsorption tower 10B is subjected to a cleaning process. The residual concentrated hydrogen discharged from the adsorption tower 10C is introduced as a cleaning gas through the line 35, the flow adjustment valve 352, and the line 34, and is introduced through the gas passage port 12, and the residual gas in the tower is discharged. . Here, the gas discharged from the adsorption tower 10B is a gas having a high concentration of volatile aromatic compounds, and the gas is sent to the exhaust gas tank 23 via the line 32 as the exhaust gas. At the end of step 1, the internal pressure of the adsorption tower 10C is higher than the internal pressure of the adsorption tower 10B. The operation time of step 1 is, for example, about 75 seconds.

In step 2, the automatic valves 31a, 33a, 34b, 35c, and 351 and the flow adjustment valve 352 are opened to achieve the gas flow state shown in FIG. 2b.

Step 2 continues the adsorption process in the adsorption tower 10A. Moreover, the individual gas passage ports 12 and 12 of the adsorption towers 10B and 10C are also communicated through the lines 34 and 35 in step 2. On the other hand, the adsorption tower 10B closes the automatic valve 32b. Then, at the beginning of step 2, the inside of the adsorption tower 10C is still higher in pressure than the inside of the adsorption tower 10B. Therefore, the adsorption tower 10C performs pressure equalization and pressure reduction, and the adsorption tower 10B performs pressure equalization and pressure increase. More specifically, the gas in the column of the adsorption column 10C is introduced into the adsorption column 10B through the lines 35 and 34, and the pressure in the column of the adsorption column 10 is reduced while the pressure in the column of the adsorption column 10B is increased. As a result, the internal pressures in the adsorption towers 10B and 10C become substantially equal. The operation time of step 2 is, for example, about 15 seconds.

In step 3, the automatic valves 31a, 33a, 34b, 32c, and 341 and the flow adjustment valve 342 are opened to achieve the gas flow state shown in FIG. 2c.

Step 3 continues the adsorption process in the adsorption tower 10A. Further, step 3 blocks the communication between the adsorption towers 10B and 10C. On the other hand, a part of the product gas discharged from the gas passage port 12 of the adsorption tower 10A is introduced into the adsorption tower 10B through the line 34 and the flow adjustment valve 342 to perform the adsorption tower. 10B step-up process.

Further, in step 3, the adsorption tower 10C communicates with the exhaust gas tank 23 through the line 32 by opening the automatic valve 32c. Accordingly, the desorption step of the adsorption tower 10C is performed. The pressure in the adsorption tower 10C is reduced, and impurities (mainly volatile aromatic compounds) are desorbed from the adsorbent. The gas (volatile aromatic compound concentration in the tower is high). Gas) is discharged out of the tower as exhaust gas through the gas passage port 11. The minimum pressure (desorption pressure) inside the adsorption tower 10C in the desorption step is, for example, 0 to 50 kPaG, and preferably 0 to 20 kPaG. The exhaust gas discharged from the adsorption tower 10C is sent to the exhaust gas tank 23 through a line 32. The gas in the exhaust gas tank 23 is appropriately sent to the cooler 24 through the pressure regulating valve 321, and then passed through the gas-liquid separator 25 to liquefy the volatile aromatic compound and recover it as a liquid phase. The operation time of step 3 is, for example, about 135 seconds. The above steps 1 to 3 correspond to 1/3 of the cycle formed according to steps 1 to 9, and the total process time of these steps 1 to 3 is about 225 seconds.

In the subsequent steps 4 to 6, as shown in Figs. 2d to 2f, the adsorption tower 10B is subjected to the operation of the adsorption tower 10A in steps 1 to 3, and the adsorption tower 10C is subjected to the adsorption in steps 1 to 3 In the operation performed on the column 10B, the operation performed on the adsorption column 10C in steps 1 to 3 is performed on the adsorption column 10A.

Step 4 opens the automatic valves 31b, 33b, 32c, 34c, 35a, 351 and the flow adjustment valve 352 to achieve the gas flow state shown in FIG. 2d. Step 5 opens the automatic valves 31b, 33b, 34c, 35a, and 351 and the flow adjustment valve 352 to achieve the gas flow state shown in FIG. 2e. Step 6 opens the automatic valves 31b, 33b, 34c, 32a, and 341 and the flow adjustment valve 342 to achieve the gas flow state shown in Fig. 2f. Although detailed description is omitted, in steps 4, 5, and 6, the adsorption tower 10A performs the same operation as the adsorption tower 10C in steps 1, 2, and 3 in sequence, and the adsorption tower 10B performs the same operations in steps 1, 2, and 3 in sequence. The same operation of the adsorption tower 10A is performed, and the adsorption tower 10C sequentially performs the same operation as the adsorption tower 10B in steps 1, 2, and 3.

In the subsequent steps 7 to 9, as shown in Figs. 2g to 2i, the adsorption tower 10C is subjected to the operation of the adsorption tower 10A in steps 1 to 3, and the adsorption tower 10A is subjected to the adsorption in steps 1 to 3 In the operation performed on the column 10B, the operation performed on the adsorption column 10C in steps 1 to 3 is performed on the adsorption column 10B.

In step 7, the automatic valves 31c, 33c, 32a, 34a, 35b, and 351 and the flow adjustment valve 352 are opened to achieve the gas flow state shown in FIG. 2g. Step 8 opens the automatic valves 31c, 33c, 34a, 35b, and 351 and the flow adjustment valve 352 to achieve the gas flow state shown in FIG. 2h. Step 9 opens the automatic valves 31c, 33c, 34a, 32b, 341 and the flow adjustment valve 342 to achieve the gas flow state shown in FIG. 2i. Although detailed description is omitted, in steps 7, 8, and 9, the adsorption tower 10A sequentially performs the same operation as the adsorption tower 10B in steps 1, 2, and 3, and the adsorption tower 10B performs the same operations as in steps 1, 2, and 3 in sequence. The same operation of the adsorption tower 10C is performed, and the adsorption tower 10C sequentially performs the same operation as the adsorption tower 10A in steps 1, 2, and 3.

Then, by repeating the above-mentioned steps 1 to 9 in the individual adsorption towers 10A, 10B, and 10C, the source gas is continuously introduced into any of the adsorbents 10A, 10B, and 10C, and the concentration is continuously obtained. Hydrogen (product gas).

In the method for purifying hydrogen of this embodiment, regarding the 1 cycle of the PSA method implemented in each of the individual adsorption towers 10A, 10B, and 10C, after the adsorption step, the residual gas in the column is introduced into the other after the desorption step. The adsorption tower performs a cleaning step. The gas in the adsorption tower after the completion of the adsorption step is a gas having a low impurity concentration (residual concentrated hydrogen), and the adsorption tower after the desorption step can be cleaned with this gas efficiently. In addition, since the product gas is not used for cleaning, it is possible to suppress a decrease in the recovery rate of hydrogen.

The adsorbent filled in each of the adsorption towers 10A, 10B, and 10C is filled with a silicone-based adsorbent as the first adsorbent 131 on the most upstream side in the flow direction of the source gas. Silicone-based adsorbents have excellent adsorption energy for impurities (volatile aromatic compounds) at high pressures of 0.1 to 1.0 MPaG (= 100 to 1000 kPaG), and may be desorbed even at a minimum pressure of 0 to 50 kPaG (desorption step) above atmospheric pressure. Attach volatile aromatic compounds and regenerate. The first adsorbent 131 is filled with 15 to 75 vol% of the entire adsorbent capacity. As a result, volatile aromatic compounds can be efficiently removed by adsorption, and since vacuum equipment is not required, cost reduction can be expected. In addition, if a hydrophilic silicone is used as the first adsorbent 131, volatile aromatic compounds can be removed by appropriate adsorption without pretreatment, which is advantageous for cost reduction.

In addition, if the filling ratio of the first adsorbent 131 is less than 15 vol%, there is a concern that volatile aromatic compounds cannot be sufficiently removed. On the other hand, if the filling ratio of the first adsorbent 131 exceeds 75 vol%, the proportion of the cleaning gas remaining in the second adsorbent 132 and the third adsorbent 133 is reduced, the amount of the cleaning gas is reduced, and the cleaning in the cleaning step is not performed. Full of doubts.

The second adsorbent 132 (zeolite-based adsorbent) and the third adsorbent 133 (activated carbon-based adsorbent) laminated on the rear stage (downstream side) of the first adsorbent 131 do not adsorb volatile aromatic compounds. That is, the adsorption step is completed before the volatile aromatic compounds of the first adsorbent 131 are saturated, and the second adsorbent 132 and the third adsorbent 133 do not substantially adsorb the volatile aromatic compounds. On the other hand, the second adsorbent 132 and the third adsorbent 133 adsorb more hydrogen than the first adsorbent. As a result, the adsorption gas discharged from the adsorption tower in the decompression step after the adsorption step is completed, and the purge gas of other adsorption towers used in the desorption step and in the cleaning step are removed, except for the concentrated hydrogen gas remaining in the column at the start of the decompression step ( It is mainly the gas close to the gas passage 12, the filled area of the second adsorbent 132, and the third adsorbent 133), and hydrogen desorbed by the second adsorbent 132 and the third adsorbent 133 is also added. As a result, the adsorption tower after the completion of the desorption step can be efficiently cleaned using a purge gas having a high hydrogen content.

The specific embodiments of the present invention have been described above, but the present invention is not limited to this, and various changes can be made without departing from the spirit of the invention. For example, regarding the configuration of the pipeline (piping) of the gas flow path serving as a device for implementing the method for purifying hydrogen or helium according to the present invention, a configuration different from the above-described embodiment may be adopted. The number of adsorption towers is not limited to the three tower type shown in the above embodiment, and the same effect can be expected in the case of four or more towers.

In addition, the above embodiment is described in the case of purifying hydrogen. The adsorbent (the first adsorbent, the second adsorbent, and the third adsorbent) used by the refining method of the present invention has a helium adsorption energy that is slightly the same as that of hydrogen. . Therefore, even in the case of condensing and purifying helium from a source gas containing helium as a main component and volatile aromatic compounds as impurities, the same effects as those of the above embodiment can be produced.

    [Example]    

Next, the usefulness of the present invention will be described with examples and comparative examples.

[Example 1]

In this embodiment, the purification apparatus X shown in FIG. 1 is used, and the purification method using the pressure swing adsorption method (PSA method) constituted by each step described with reference to FIG. 2 is used. The gas is obtained as concentrated hydrogen as a product gas.

As the adsorption towers 10A, 10B, and 10C, a cylindrical shape having an inner diameter of 35 mm was used, and the filling capacity of the adsorbent was about 1 L (liter). In each of the adsorption towers 10A, 10B, and 10C, a silicone rubber type B (Fuji silicone rubber type B manufactured by Fuji silysia Chemical Co., Ltd.) is sequentially laminated and filled from a gas passage 11 to a gas passage 12 as a first adsorbent 131, and a CaA zeolite ( 5AHP manufactured by Union Showa Corporation) was used as the second adsorbent 132, and activated carbon (PGAR manufactured by Cataler Corporation) was used as the third adsorbent. The filling ratio (volume ratio) of these adsorbents is 30 vol% for the first adsorbent 131, 60 vol% for the second adsorbent 132, and 10 vol% for the third adsorbent 133. As the raw material gas, crude hydrogen containing 8500 vol ppm of toluene as an impurity was used, and the raw material gas was supplied at a flow rate of 5.2 NL / min. The operating conditions of the PSA method are that the temperature of the adsorption tower, etc. is 40 ° C, the adsorption pressure is 0.8 MPaG, the desorption pressure is 20 kPaG, the cleaning pressure difference is 300 kPa, and the cycle time (the time of 1 cycle composed of steps 1 to 9) is 675 seconds. The impurity concentration of the obtained concentrated hydrogen (product gas) was measured by a flame ionization detector (FID). The toluene concentration in the product gas was below the lower limit of quantification (0.1 volppm or less), and the hydrogen recovery rate was 75%. The results of this example are shown in Table 1.

[Example 2]

Hydrogen was purified from the source gas in the same manner as in Example 1 except that the filling ratio of the adsorbent was 40 vol% for the first adsorbent 131, 50 vol% for the second adsorbent 132, and 10 vol% for the third adsorbent 133. The impurity concentration of the obtained concentrated hydrogen (product gas) was measured by a flame ionization detector (FID). The toluene concentration in the product gas was below the lower limit of quantification (0.1 volppm or less), and the hydrogen recovery rate was 70%. The results of this example are shown in Table 1.

[Example 3]

Hydrogen was purified from the source gas in the same manner as in Example 1 except that the filling ratio of the adsorbent was 20 vol% for the first adsorbent 131, 70 vol% for the second adsorbent 132, and 10 vol% for the third adsorbent 133. The impurity concentration of the obtained concentrated hydrogen (product gas) was measured by a flame ionization detector (FID). The toluene concentration in the product gas was below the lower limit of quantification (0.1 volppm or less), and the hydrogen recovery rate was 80%. The results of this example are shown in Table 1.

[Example 4]

Hydrogen was purified from the source gas in the same manner as in Example 1 except that the filling ratio of the adsorbent was 70 vol% for the first adsorbent 131, 20 vol% for the second adsorbent 132, and 10 vol% for the third adsorbent 133. The impurity concentration of the obtained concentrated hydrogen gas (product gas) was measured by a flame ionization detector (FID). The toluene concentration in the product gas was 0.67 volppm, and the hydrogen recovery rate was 92%. The results of this example are shown in Table 1.

[Example 5]

Hydrogen was purified from the source gas in the same manner as in Example 1 except that the filling ratio of the adsorbent was 30 vol% for the first adsorbent 131, 40 vol% for the second adsorbent 132, and 30 vol% for the third adsorbent 133. The impurity concentration of the obtained concentrated hydrogen gas (product gas) was measured with a flame ionization detector (FID). The toluene concentration in the product gas was 0.43 volppm, and the hydrogen recovery rate was 85%. The results of this example are shown in Table 1.

[Comparative Example 1]

Hydrogen was purified from the source gas in the same manner as in Example 1 except that the filling ratio of the adsorbent was 80 vol% for the first adsorbent 131, 10 vol% for the second adsorbent 132, and 10 vol% for the third adsorbent 133. The impurity concentration of the obtained concentrated hydrogen (product gas) was measured with a flame ionization detector (FID). The toluene concentration in the product gas was 2000 volppm, and the hydrogen recovery rate was 90%. The results of this comparative example are shown in Table 1.

[Comparative Example 2]

Hydrogen was purified from the source gas in the same manner as in Example 1 except that the filling ratio of the adsorbent was 10 vol% for the first adsorbent 131, 80 vol% for the second adsorbent 132, and 10 vol% for the third adsorbent 133. The impurity concentration of the obtained concentrated hydrogen (product gas) was measured by a flame ionization detector (FID). The toluene concentration in the product gas was 3000 volppm, and the hydrogen recovery rate was 75%. The results of this comparative example are shown in Table 1.

[Comparative Example 3]

Hydrogen was purified from the source gas in the same manner as in Example 1 except that the filling ratio of the adsorbent was 30 vol% of the first adsorbent 131, 30 vol% of the second adsorbent 132, and 40 vol% of the third adsorbent 133. The impurity concentration of the obtained concentrated hydrogen (product gas) was measured by a flame ionization detector (FID). The toluene concentration in the product gas was 2 volppm, and the hydrogen recovery rate was 75%. The results of this comparative example are shown in Table 1.

[Table 1]     

As is clear from the first table, it was confirmed that the high-purity purified hydrogen can be obtained according to the above-mentioned examples.

Claims (11)

    A method for refining hydrogen or helium by repeating a pressure swing adsorption cycle for each adsorption tower by using three or more towers filled with an adsorbent, and comprising a volatile aromatic compound as an impurity and containing A method for refining hydrogen or helium as a source gas with hydrogen or helium as a main component, the cycle includes an adsorption step of bringing the adsorption tower to a predetermined high pressure state, and introducing the source gas into the adsorption tower to make the above in the source gas A volatile aromatic compound is adsorbed on the adsorbent, and a product gas having a high concentration of hydrogen or helium is exhausted from the adsorption tower; in a decompression step, the gas remaining in the tower is exhausted from the adsorption tower that ends the adsorption step to make Pressure reduction; in a desorption step, the volatile aromatic compound is desorbed by the adsorbent in the adsorption tower that has completed the decompression step, and the gas in the tower is exhausted; and a cleaning step is performed by other adsorption towers in the decompression step. The exhausted gas is introduced into the adsorption tower that has completed the desorption step to exhaust the gas remaining in the tower. Each of the adsorption towers The flow direction of the raw material gas in the adsorption tower is sequentially divided into a first region, a second region, and a third region from the upstream side to the downstream side. The first region is filled with the entire filling capacity of the adsorbent. The silica-based first adsorbent having a filling ratio in the range of 15 to 75 vol% is filled with a zeolite-based second adsorbent having a filling ratio in the range of 15 to 75 vol% and the third area is filled with An activated carbon-based third adsorbent having a filling ratio in the range of 5 to 30 vol%.         The method for purifying hydrogen or helium according to item 1 of the patent application range, wherein the first adsorbent contains a hydrophilic silicone.         The method for purifying hydrogen or helium according to item 1 of the scope of patent application, wherein the second adsorbent contains a CaA zeolite.         The method for purifying hydrogen or helium according to item 1 of the scope of patent application, wherein the third adsorbent contains coconut shell activated carbon or stone carbon activated carbon.         The method for purifying hydrogen or helium according to item 1 of the scope of the patent application, wherein the cleaning step and the adsorption step further include a step-up step to increase the pressure of the adsorption tower to a predetermined adsorption pressure.         The method for purifying hydrogen or helium according to item 5 of the scope of patent application, wherein the decompression step includes a first decompression step, and the residual gas discharged from the adsorption tower is used as a purge gas to be introduced into another adsorption tower in the purge step. And a second decompression step, following the first decompression step, the residual gas discharged from the adsorption tower is introduced into another adsorption tower that is in the pressure increasing step.         The method for purifying hydrogen or helium according to item 6 of the scope of the patent application, wherein the pressure increasing step includes a first pressure increasing step, and the residual gas discharged from other adsorption towers in the first pressure reducing step is introduced into the adsorption tower; And the second pressure increasing step, following the first pressure increasing step, introducing a part of the product gas from another adsorption tower in the adsorption step into the adsorption tower.         A refining device for hydrogen or helium is a device for refining hydrogen or helium from a source gas containing volatile aromatic compounds as impurities and containing hydrogen or helium as a main component. The device includes: an adsorption tower of 3 or more towers, Each has a first gas passage and a second gas passage, and an adsorbent is filled between the first gas passage and the second gas passage; a storage tank for storing the product gas; a gas-liquid separation means will be described above The gas discharged from the first gas passage port of the adsorption tower is separated into a gas phase component and a liquid phase component. The first line has a main line connected to a source gas supply source, and is individually installed in the adsorption tower and connected to the adsorption tower. The above-mentioned first gas passes through a plurality of branch lines on the port side and each is individually provided with an on-off valve; the second line includes a main line provided with the above-mentioned gas-liquid separation means, and the above-mentioned separately installed in the adsorption tower and connected to the adsorption tower The first gas passes through a plurality of branch lines on the port side, each of which is provided with an on-off valve; the third line includes a trunk line provided with the storage tank; A plurality of branch lines of the adsorption tower and the second gas passing port connected to the adsorption tower, each of which is provided with an on-off valve; a fourth pipeline having a trunk line connected to the trunk line of the third pipeline; A plurality of branch lines provided on the adsorption tower and connected to the adsorption tower, the second gas passing port side being individually provided with an on-off valve; and a fifth line having a main line connected to the main line connected to the fourth line, and A plurality of branch lines that are individually installed in the adsorption tower and connected to the second gas passage opening side of the adsorption tower and are individually provided with on-off valves, and each of the adsorption towers passes from the first gas passage opening to the first gas passage opening in the adsorption tower. The 2 gas is sequentially divided into a first region, a second region, and a third region through the mouth. The first region is filled with a silicone-based resin having a filling ratio in a range of 15 to 75 vol% with respect to the entire filling capacity of the adsorbent. The first adsorbent is filled with a zeolite-based second adsorbent in a range of 15 to 75 vol% in the second region, and the third absorbent is filled in a range of 5 to 30 vol%. A third adsorbent of activated carbon.         The hydrogen or helium refining device according to item 8 of the scope of patent application, wherein the first adsorbent is made of hydrophilic silicone.         The hydrogen or helium purification device according to item 8 of the scope of the patent application, wherein the second adsorbent contains a CaA zeolite.         The hydrogen or helium refining device according to item 8 of the scope of the patent application, wherein the third adsorbent contains coconut shell activated carbon or stone carbon activated carbon.