Pressure swing adsorption type gas separation device

Abstract

The purpose of this invention is to provide a pressure swing adsorption (PSA) gas separation device that prevents difficult-to-adsorb components from mixing into the easily-adsorbed component storage tank and separates the easily-adsorbed components with high purity. The provided PSA gas separation device (100) includes: a raw material gas storage tank (1) for storing a mixed gas containing the target component and at least one other component as raw material gas; an easily-adsorbed component storage tank (2) for storing easily-adsorbed components; a difficult-to-adsorbed component storage tank (3) for storing difficult-to-adsorbed components; a compressor (4) for compressing the gas in the raw material gas storage tank (1) or the easily-adsorbed component storage tank (2); a compressor (5) for compressing the gas in the easily-adsorbed component storage tank (2); and four adsorption cylinders: a lower cylinder (10B), a lower cylinder (11B), an upper cylinder (10U), and an upper cylinder (11U).

Description

Technical Field

[0001] This invention relates to a pressure swing adsorption gas separation device. Prior Technology

[0002] In the manufacturing of semiconductor integrated circuits, liquid crystal panels, and other semiconductor products, devices are widely used to generate plasma through high-frequency discharge in a rare gas environment, and to perform various processes on the semiconductor products or display devices using the generated plasma. Argon has traditionally been used as the rare gas in such devices. However, in recent years, krypton and xenon have gained attention due to the need for more sophisticated processing. Previously, argon was used as the sealing gas in lamps, but in recent years, high-value-added products containing krypton or xenon have been manufactured to reduce power consumption and increase brightness. Similarly, argon was previously used as the sealing gas in laminated glass, but in recent years, high-value-added products using krypton have been manufactured to improve thermal insulation performance.

[0003] However, considering the proportion of krypton or xenon in the air as raw materials and the complexity of the separation process, they are extremely rare and expensive gases. Their use could disrupt the supply-demand balance and significantly increase costs.

[0004] For this gas to be economically viable, it is extremely important to recover and reuse the used rare gases. Furthermore, for rare gases to be reused, a concentration of at least 99% by volume is required.

[0005] Regarding the apparatus for separating xenon or krypton, there is a method and apparatus as follows: a raw gas containing xenon or krypton and other components that are impurities is flowed through an adsorption cylinder filled with an adsorbent that is readily adsorbed relative to xenon or krypton and difficult to adsorb relative to other components that are impurities. The readily adsorbed xenon or krypton is adsorbed onto the adsorbent, while the impurities that are difficult to adsorb are separated from the xenon or krypton. The xenon or krypton adsorbed onto the adsorbent is then removed from the adsorbent and recovered in a high concentration.

[0006] Patent Document 1 discloses a pressure swing adsorption (PSA) gas separation method and a PSA gas separation apparatus 101 (Fig. 10) for implementing this method, wherein steps a to e are performed sequentially. Steps a to e are as follows: Step a, the raw material gas in the raw material gas storage tank 1 is pressurized by the compressor 4 and then flows to two adsorption cylinders connected in series (upper cylinder 10U (11U) and lower cylinder 10B (11B)), and the easily adsorbed xenon or krypton is adsorbed onto the adsorbent in the adsorption cylinder, while the impurities that are difficult to adsorb are separated; Step b, the xenon or krypton that has been filled in the easily adsorbed component storage tank 2 is pressurized by the compressor 4 and then introduced into the lower cylinder 10B (11B), and the impurities that are difficult to adsorb and remain in the gaps of the lower cylinder 10B (11B) are discharged to the upper cylinder 10U (11U), and the impurities that are difficult to adsorb are discharged into the upper cylinder 10U (11U). Step c involves depressurizing the lower cylinder 10B (11B) to remove easily adsorbed xenon or krypton from the adsorbent and recovering the difficult-to-adsorb impurities from the upper cylinder 10U (11U); Step d involves depressurizing the upper cylinder 10U (11U) to remove the adsorbed components from the adsorbent and then recovering them to the easily adsorbed component storage tank 2; Step d involves depressurizing the upper cylinder 10U (11U) to remove the components adsorbed on the adsorbent and then introducing them into the lower cylinder 10B (11B), thereby recovering the gas flowing out of the lower cylinder 10B (11B) to the raw material gas storage tank 1; and Step e involves introducing the previously recovered difficult-to-adsorb impurities into the upper cylinder 10U (11U), removing easily adsorbed xenon or krypton from the adsorbent and then introducing them into the lower cylinder 10B (11B), thereby recovering the gas flowing out of the lower cylinder 10B (11B) to the raw material gas storage tank 1.

[0007] The lower cylinder 10B (11B) of the pressure swing adsorption gas separation device 101 shown in Fig. 10 has: a path L4 (L5) for introducing the raw material gas in the raw material gas storage tank 1 or the gas in the easily adsorbable component storage tank 2 after pressurization; a path (unsigned) connected to the upper cylinder 10U (11U); and a path L9 for discharging to the raw material gas storage tank 1 or the easily adsorbable component storage tank 2 after decompression. Furthermore, the path L9 branches into a path L11 connected to the raw material gas storage tank 1 and a path L12 connected to the easily adsorbable component storage tank. Opening and closing valves for controlling the gas flow are provided in each path. In step a, the opening and closing valves V1, V3 provided in the paths L2, L4, and the opening and closing valve V5 provided in the path (unsigned) connecting the lower cylinder 10B and the upper cylinder 10U are opened, and the other opening and closing valves are closed. The paths L2, L4 connect the raw material gas storage tank 1 and the lower cylinder 10B, and after pressurizing the raw material gas in the raw material gas storage tank 1 with the compressor 4, it is introduced into the lower cylinder 10B. In step b, the opening and closing valves V2, V3 provided in the paths L3, L4, and the opening and closing valve V5 provided in the path (unsigned) connecting the lower cylinder 10B and the upper cylinder 10U are opened, and the other opening and closing valves are closed. The paths L3, L4 introduce the gas in the easily adsorbable component storage tank 2 into the lower cylinder 10B after pressurizing it with the compressor 4. In step c, the opening and closing valves V12, V11 provided in the paths L9, L12 connecting the lower cylinder 10B and the easily adsorbable component storage tank 2 are opened, and the other opening and closing valves are closed. After the easily adsorbable component adsorbed on the adsorbent is desorbed by reducing the pressure of the lower cylinder 10B, it is discharged to the easily adsorbable component storage tank 2. In steps d and e, the opening and closing valves V12, V10 provided in the paths L9, L11 connecting the lower cylinder 10B and the raw material gas storage tank 1, and the opening and closing valve V5 provided in the path (unsigned) connecting the upper cylinder 10U and the lower cylinder 10B are opened, and the other opening and closing valves are closed. [Prior Art Documents] [Patent Documents]

[0008] Patent Document 1: Japanese Patent Laid-Open No. 2006-061831 Summary of the Invention Problems to be Solved by the Invention

[0009] The pressure swing adsorption gas separation device 101 (Fig. 10) described in Fig. 1 of Patent Document 1 has the following problems. The paths L9 and L11 connecting the lower cylinder 10B to the raw material gas storage tank 1 and discharging from the lower cylinder 10B to the raw material gas storage tank 1 after depressurization, and the paths L9 and L12 connecting the lower cylinder 10B to the easily adsorbed component storage tank 2 and discharging from the lower cylinder 10B to the easily adsorbed component storage tank 2, are partially connected as shared piping for depressurization discharge. In this configuration, at the beginning of step c, the detached component discharged from the upper cylinder 10U in step d and the difficult-to-adsorb component introduced into the upper cylinder 10U and then discharged from the lower cylinder 10B in step e will be present in the aforementioned shared piping. Therefore, in step c, the difficult-to-adsorb component will be discharged to the easily adsorbed component storage tank 2. Since the difficult-to-adsorb component will mix into the easily adsorbed component storage tank 2, the purity of the easily adsorbed component in the easily adsorbed component storage tank 2 will decrease.

[0010] To explain the above problem in more detail. In step a above, as shown in Figure 1 (Figure 10) of Patent Document 1, the raw material gas introduced from the raw material gas storage tank 1 into the lower cylinder 10B flows from the lower cylinder 10B into the piping between the on / off valve V12 and the lower cylinder 10B. The on / off valve V12 is installed in the piping L9 connected to the easily adsorbed component storage tank 2.

[0011] Next, in step b above, the readily adsorbable component gas system of readily adsorbable component storage tank 2 is introduced into lower cylinder 10B through pipe L14. However, in the aforementioned pipe L9, since readily adsorbable component gas does not flow near the on / off valve V12 between the on / off valve V12 and lower cylinder 10B, the raw material gas continues to exist there.

[0012] As a result, in step c above, the raw material gas system near the on / off valve V12 between the on / off valve V12 and the lower cylinder 10B in the aforementioned piping L9 is discharged to the easily adsorbed component storage tank 2. Since the difficult-to-adsorb components contained in the raw material gas are impurities in the easily adsorbed component gas of the easily adsorbed component storage tank 2, they become the main reason for the decrease in the purity of the separated easily adsorbed components. In particular, when the concentration of the difficult-to-adsorbed components in the raw material gas is high, even if the volume between the on / off valve V12 and the lower cylinder 10B in the aforementioned piping L9 is small, it becomes a major reason for a very large decrease in purity.

[0013] Furthermore, the separation method and apparatus disclosed in Patent Document 1 have the following problems. The compressor pressurizes the gas in the raw material gas storage tank in step a, and pressurizes the xenon or krypton in the easily adsorbed component storage tank in step b. Here, if there is a volume forming a closed pipeline, such as a branch pipe, in the flow path from the easily adsorbed component storage tank to the compressor, the gas flowing in the raw material gas storage tank in step a will remain in the volume forming the closed pipeline. Furthermore, the gas remaining in the volume forming the closed pipeline will mix with the xenon or krypton in the raw material gas storage tank pressurized in step b. Since the gas in the raw material gas storage tank contains a high concentration of impurities that are difficult to adsorb, these impurities will mix with the xenon or krypton in the easily adsorbed component storage tank pressurized in step b. When the xenon or krypton introduced into the lower cylinder in step b contains impurities, the impurities remaining in the gaps of the lower cylinder cannot be discharged to the upper cylinder and remain in the lower cylinder.

[0014] Therefore, in step c, the xenon or krypton is recovered to the readily adsorbable component storage tank while still containing residual impurities. Since the xenon or krypton introduced into the lower cylinder in the subsequent step b contains impurities, and this is combined with the impurities already remaining in the volume forming the closed pipeline, the concentration of impurities in the xenon or krypton recovered to the readily adsorbable component storage tank in step c increases. Repeating these steps will significantly reduce the concentration of xenon or krypton recovered into the storage tank for easily adsorbed components.

[0015] The objective of this invention is to provide a pressure swing adsorption gas separation device that prevents difficult-to-adsorb components from mixing into the storage tank of easily adsorbed components, and separates easily adsorbed components with high purity. The means to solve the problem

[0016] [1] A pressure swing adsorption (PSA) gas separation device, which is a device for separating main components from a raw material gas using a PSA gas separation method, wherein the raw material gas is a mixed gas containing at least two main components, and the PSA gas separation device comprises: At least one adsorption cartridge filled with an adsorbent, wherein the adsorbent is readily adsorbable to at least one major component of the raw material gas and is difficult to adsorb to at least one major component of the raw material gas; The raw material gas storage tank is used to store the aforementioned raw material gas; The storage tank for easily adsorbed components stores easily adsorbed components that have desorbed from the adsorbent in the aforementioned adsorption cylinder; At least one compressor is configured to draw in and compress at least one of the gas in the aforementioned raw material gas storage tank and the gas in the aforementioned easily adsorbed component storage tank, for introducing at least one of the aforementioned raw material gas and the gas in the aforementioned easily adsorbed component storage tank into one of the aforementioned adsorption cylinders; The gas flow path that returns the gas discharged from the aforementioned adsorption cylinder to the aforementioned easily adsorbed component storage tank; and The gas discharged from the aforementioned adsorption cylinder is returned to the aforementioned raw material gas storage tank via a gas flow path; and, The gas flow path that sends the gas discharged from the aforementioned adsorption cylinder back to the aforementioned easily adsorbed component storage tank is a first dedicated flow path, which is connected at one end to the aforementioned adsorption cylinder and at the other end only to the aforementioned easily adsorbed component storage tank. [2] As described in [1], in the pressure swing adsorption gas separation device, one end of the first dedicated flow path is connected to the adsorption cylinder via a gas flow path that introduces gas from the compressor into the adsorption cylinder. [3] The pressure swing adsorption gas separation device as described in [1] or [2] further has a second dedicated flow path, one end of which is connected to the aforementioned adsorption cylinder and the other end is connected only to the aforementioned raw material gas storage tank. [4] As described in [3], in the pressure swing adsorption gas separation device, one end of the aforementioned second dedicated flow path is connected to the aforementioned adsorption cylinder via a gas flow path that introduces gas from the aforementioned compressor into the aforementioned adsorption cylinder.

[0017] [5] The pressure swing adsorption gas separation device as described in [1] has the following features: The first flow path is located between the aforementioned compressor and the aforementioned adsorption cylinder; The second flow path branches off from the first flow path at the first branch point and is located between the first branch point and the aforementioned easily adsorbed component storage tank; and The first opening and closing device is located in the aforementioned second flow path; and, The aforementioned first opening and closing device is located near the aforementioned first branch point. [6] As described in [5], the pressure swing adsorption gas separation device, wherein the aforementioned first branch point is located near the aforementioned adsorption cylinder. [7] The pressure swing adsorption gas separation device as described in [5] or [6] further has the following characteristics: The third flow path branches off from the aforementioned first flow path at the second branch point, and is located between the aforementioned second branch point and the aforementioned raw material gas storage tank; and The second opening and closing device is located in the aforementioned third flow path; and, The aforementioned second opening and closing device is located near the aforementioned second branch point. [8] The pressure swing adsorption gas separation device as described in [7], wherein the aforementioned second branch point is located near the aforementioned adsorption cylinder. [9] The pressure swing adsorption gas separation device as described in [1] has: A flow path that branches into a first flow path, a second flow path, and a third flow path at a branch point. The first flow path is connected to the adsorption cylinder described above, the second flow path is connected to the raw material gas storage tank described above, and the third flow path is connected to the easily adsorbable component storage tank described above; A compressor, located in the flow path described above; and A first opening / closing device, located in the second flow path described above; and, The first opening / closing device is located near the branch point described above.

[10] The pressure swing adsorption type gas separation device as described in [9], wherein the volume of the second flow path from the inside of the first opening / closing device to the branch point is less than or equal to 1 volume percentage of the gas volume sucked by the compressor in one minute.

[11] The pressure swing adsorption type gas separation device as described in [9] or

[10] further includes a second opening / closing device, which is located in the third flow path described above; and, The second opening / closing device is located near the branch point described above.

[12] The pressure swing adsorption type gas separation device as described in any one of [9] to

[11] , wherein the compressor is located near the branch point of the first flow path.

[13] The pressure swing adsorption type gas separation device as described in

[11] includes a first compressor and a second compressor as the compressor described above. The first compressor is located on the primary side of the first opening / closing device in the second flow path, and the second compressor is located on the primary side of the second opening / closing device in the third flow path.

[14] The pressure swing adsorption type gas separation device as described in any one of [1] to

[13] , wherein the raw material gas contains: at least one easily adsorbable component selected from the group consisting of xenon and krypton; and at least one hardly adsorbable component selected from the group consisting of oxygen, nitrogen, argon, helium, neon, and hydrogen. Advantages of the Invention

[0018] [[ID=S24]]According to the present invention, a pressure swing adsorption type gas separation device can be provided, which can reduce the amount of hardly adsorbable components mixed into the easily adsorbable component storage tank and separate the easily adsorbable components with high purity. Brief Explanation of Drawings

[0019] FIG. 1 is a schematic configuration diagram of the pressure swing adsorption type gas separation device of the present invention. FIG. 2 is a step diagram showing half a cycle of the gas separation method using the pressure swing adsorption type gas separation device of the present invention. Figure 3 is a flowchart showing the steps of the gas separation method using the pressure swing adsorption gas separation device of the present invention for the other half of the cycle. Figure 4 is a flowchart showing half a cycle of the gas separation method using the pressure swing adsorption gas separation device of the present invention. Figure 5 shows the steps of the gas separation method using the pressure swing adsorption gas separation device of the present invention for the other half of the cycle. Figure 6 is a schematic diagram showing the configuration of a pressure swing adsorption gas separation device according to a second embodiment of the present invention. Figure 7 is a schematic diagram showing the configuration of a pressure swing adsorption gas separation device according to a third embodiment of the present invention. Figure 8 is a schematic diagram of the pressure swing adsorption gas separation device according to the fourth embodiment of the present invention. Figure 9 is a schematic diagram showing a modified example of the pressure swing adsorption gas separation device according to the fourth embodiment of the present invention. Figure 10 is a schematic diagram of the pressure swing adsorption gas separation device shown in Figure 1 of Patent Document 1 (Japanese Patent Application Publication No. 2006-061831). Implementation

[0020] The following detailed description is provided with reference to the accompanying drawings and with regard to an example of an embodiment of the pressure swing adsorption gas separation device of the present invention. However, it is not limited to the embodiment described below and various modifications can be made without departing from the spirit of the present invention.

[0021] Pressure Swing Adsorption (PSA) Gas Separator Figure 1 shows a schematic configuration of the pressure swing adsorption gas separation device 100 of this embodiment, comprising: a raw material gas storage tank 1 for storing a mixed gas containing a target component and at least one other component; an easily adsorbable component storage tank 2 for storing easily adsorbable components; a difficult-to-adsorb component storage tank 3 for storing difficult-to-adsorb components; a compressor 4 for compressing the gas in the raw material gas storage tank 1 or the easily adsorbable component storage tank 2; a compressor 5 for compressing the gas in the easily adsorbable component storage tank 2; and four adsorption cylinders, a lower cylinder 10B, a lower cylinder 11B, an upper cylinder 10U, and an upper cylinder 11U, filled with an adsorbent that has at least easy adsorption properties for the target component and difficult adsorption properties for the other components.

[0022] Path L1 is the gas flow path that introduces the raw material gas into the raw material gas storage tank 1. Path L2 is a gas flow path that leads the gas from the raw material gas storage tank 1 to the compressor 4. Path L3 is a gas flow path that leads the gas from the storage tank 2 for easily adsorbed components to the compressor 4. Paths L4 and L5 are gas flow paths that introduce gas from compressor 4 into lower cylinder 10B and lower cylinder 11B, respectively. Path L6 is a gas flow path that introduces gas from the upper cylinder 10U and the upper cylinder 11U into the storage tank 3 for difficult-to-adsorb components. Path L7 is a gas flow path that supplies the difficult-to-adsorb components from the difficult-to-adsorb component storage tank 3 to the outside of the device system. Path L8 is a gas flow path that introduces the difficult-to-adsorb components from the difficult-to-adsorb component storage tank 3 as a backflow purging gas into the upper cylinder 10U and the upper cylinder 11U. Paths L9' and L10' are gas flow paths that transport gas from lower cylinder 10B and lower cylinder 11B to path L17, respectively. Paths L11' and L12' are gas flow paths that transport gas from lower cylinder 10B and lower cylinder 11B to path L16, respectively. Path L13 is a gas flow path that supplies the easily adsorbed component from the easily adsorbed component storage tank 2 to the outside of the device system. Path L14 is a pressure equalization line for equalizing pressure between the upper cylinder 10U and the upper cylinder 11U. Path L15 is a gas flow path that delivers gas from compressor 4 to path L4 or path L5. Path L16 is a gas flow path that returns gas from paths L11' and L12' to the easily adsorbed component storage tank 2. Path L16, in combination with path L11' or path L12', forms a first dedicated flow path independent of other gas flow paths. One end of path L16 is connected to the lower cylinder 10B or lower cylinder 11B, and the other end is connected only to the easily adsorbed component storage tank 2. The aforementioned end of path L16, which is the first dedicated flow path, is connected to the lower cylinder 10B or lower cylinder 11B via path L4 (L5), which introduces gas from the aforementioned compressor 4 into the lower cylinder 10B (11B) of the aforementioned adsorption cylinder. Path L17 is a gas flow path that returns gas from paths L9' and L10' to the raw material gas storage tank 1. Path L17, in combination with path L9' or path L10', forms a second dedicated flow path independent of other gas flow paths. One end of path L17 is connected to the lower cylinder 10B or the lower cylinder 11B, and the other end is connected only to the raw material gas storage tank 1. One end of path L17, as the second dedicated flow path, is connected to the lower cylinder 10B or the lower cylinder 11B via path L4 (L5), which introduces gas from the aforementioned compressor 4 into the lower cylinder 10B (11B) of the aforementioned adsorption cylinder. Furthermore, regarding the connection point of path L4 (L5), the connection point of path L16, which is the first dedicated flow path, is closer to the lower cylinder 10B (11B) than the connection point of path L17, which is the second dedicated flow path.

[0023] <Gas Separation Methods> Next, by way of example, a method for separating xenon (which is the target component) and nitrogen (which is a component other than the target component) from a mixed gas containing xenon (the target component) and nitrogen (a component other than the target component) will be described. In this example, activated carbon, a type of equilibrium separation adsorbent, is used as the adsorbent filling the lower cylinder 10B, lower cylinder 11B, upper cylinder 10U, and upper cylinder 11U. Regarding the equilibrium adsorption capacity, activated carbon adsorbs more xenon and less nitrogen. That is, xenon is the easily adsorbed component, while nitrogen is the difficult-to-adsorb component.

[0024] Figure 2 is a diagram showing half a cycle of the gas separation method using the pressure swing adsorption gas separator 100 shown in Figure 1, consisting of two steps: adsorption step (step a) and rinsing step (step b).

[0025] (1) Adsorption step (step a) Close valves V2, V4, V9, V15, V10', V12', and V7, and open valves V1, V3, V5, and V14. Compress the mixed gas from the raw material gas storage tank 1 using compressor 4, and supply it to the lower cylinder 10B via paths L2, L15, and L4. Alternatively, valve V14 can be closed, pressurizing the upper cylinder 10U by supplying only the mixed gas from the raw material gas storage tank 1 until the pressure matches that of the non-adsorbable component storage tank 3. Since the flow between the lower cylinder 10B and the upper cylinder 10U is achieved by opening the on / off valve V5, the pressure in the lower cylinder 10B and the upper cylinder 10U rises at approximately the same rate. Furthermore, the mixed gas in the raw material gas storage tank 1 is a mixture of the raw material gas introduced through path L1 and the gas discharged from the lower cylinder 10B or lower cylinder 11B during the upper cylinder depressurization step and the flushing and regeneration step described later.

[0026] The mixed gas system supplied to the lower cylinder 10B preferentially adsorbs xenon as it moves upwards from the lower cylinder 10B, concentrating nitrogen in the gas phase. The concentrated nitrogen is introduced from the lower cylinder 10B into the upper cylinder 10U, where trace amounts of xenon contained in the nitrogen are further adsorbed. After the pressure in the upper cylinder 10U becomes higher than the pressure in the difficult-to-adsorb component storage tank 3, the nitrogen system further concentrated in the upper cylinder 10U is discharged to the difficult-to-adsorb component storage tank 3 via path L6. The nitrogen system in the difficult-to-adsorb component storage tank 3 is discharged from the system via path L7 at a flow rate corresponding to the nitrogen contained in the feed gas, and the remaining gas is used as countercurrent flushing gas in the flushing and regeneration step.

[0027] (2) Rinsing step (step b) By closing valves V1, V4, V9, V15, V10', V12', and V7, and opening valves V2, V3, V5, and V14, xenon from the readily adsorbable component storage tank 2 is introduced into the lower cylinder 10B. By introducing xenon from the readily adsorbable component storage tank 2 into the lower cylinder 10B, nitrogen co-adsorbed in the adsorbent filling layer of the lower cylinder 10B, along with nitrogen present in the adsorbent voids, is pushed to the upper cylinder 10U, thus saturating the lower cylinder 10B with xenon. During this period, nitrogen is continuously discharged from the upper cylinder 10U to the difficult-to-adsorb component storage tank 3. Similar to the adsorption step described above (step a), a portion of the nitrogen in the difficult-to-adsorb component storage tank 3 is discharged outside the device system, and the remainder is used for backflow purging gas.

[0028] Figure 3 illustrates the steps of the other half of the cycle of the pressure swing adsorption gas separator 100 shown in Figure 1, consisting of three steps: lower cylinder depressurization step (step c), upper cylinder depressurization step (step d), and rinsing and regeneration step (step e). Furthermore, while the lower cylinder 10B and upper cylinder 10U are performing the first two steps shown in Figure 2, the three steps shown in Figure 3 are performed in the lower cylinder 11B and upper cylinder 11U.

[0029] (3) Lower cylinder decompression step (step c) Close valves V4, V6, V11', and V12', and open valve V13'. In this way, the xenon system adsorbed in the lower cylinder 11B during the adsorption step (step a) to the rinsing step (step b) is recovered to the easily adsorbed component storage tank 2 via paths L12' and L16 due to the differential pressure between the lower cylinder 11B and the easily adsorbed component storage tank 2. Since the gas flow path formed by paths L12' and L16 is a dedicated flow path independent of other gas flow paths, and does not mix with gases containing difficult-to-adsorb components from other gas flow paths, the xenon in the gas recovered to the easily adsorbed component storage tank 2 has extremely high purity and very few impurities. The xenon recovered to the easily adsorbed component storage tank 2 is pressurized by compressor 5 and collected from path L13 as a product. The remaining xenon is used as a co-current (also known as "parallel flow") flushing gas in the rinsing step (step b). During this period, the upper cylinder 11U is stopped by closing the on / off valves V6, V8, V9, and V15.

[0030] (4) Upper cylinder decompression step (step d) Close valves V4, V8, V9, V10', V13', and V15, and open valves V6 and V11'. This creates a pressure difference between the upper cylinder 11U (which stopped in the lower cylinder depressurization step (step c)) and the lower cylinder 11B (which has undergone depressurization), causing gas in the upper cylinder 11U to flow into the lower cylinder 11B. The gas introduced into the lower cylinder 11B flushes the lower cylinder 11B and is then returned to the raw material gas storage tank 1 via paths L10' and L17. Since the gas flow path formed by paths L10' and L17 is a dedicated flow path independent of other gas flow paths and does not mix with gas from other gas flow paths, the xenon concentration in the gas flowing through this flow path does not change significantly. Therefore, the xenon concentration in the gas stored in the raw material gas storage tank 1 is very stable. The gas system recovered to the raw material gas storage tank 1 is mixed with the raw material gas introduced from path L1 and then supplied to the lower cylinder again during the adsorption step (step a).

[0031] (5) Rinsing and regeneration step (step e) Close valves V4, V8, V9, V10', and V13', and open valves V6, V11', and V15. The nitrogen system stored in the difficult-to-adsorb component storage tank 3 is introduced as a countercurrent flushing gas into the upper cylinder 11U via path L8. As the nitrogen system introduced into the upper cylinder 11U moves downwards, it displaces and desorbs the adsorbed xenon. The gas system containing a relatively large amount of desorbed xenon is then recovered to the raw material gas storage tank 1 via the lower cylinder 11B, path L10', and path L17. Similar to the upper cylinder depressurization step (step d), the gas system recovered to the raw material gas storage tank 1 is mixed with the raw material gas introduced from path L1 and then supplied to the lower cylinder again during the adsorption step (step a). Here, the nitrogen used for the countercurrent flushing gas can also be nitrogen that is exported from the upper cylinder 10U in the adsorption step (step a) or rinsing step (step b) and directly introduced into the upper cylinder in the flushing and regeneration step (step e) without passing through the difficult-to-adsorb component storage tank 3 (with the on / off valve V8 closed and the on / off valve V9 open).

[0032] By sequentially and repeatedly performing the above five steps in the lower cylinder 10B and upper cylinder 10U, and the lower cylinder 11B and upper cylinder 11U, nitrogen and xenon concentration can be continuously performed. Furthermore, during the period from the adsorption step (step a) to the rinsing step (step b) in the lower cylinder 10B and upper cylinder 10U, the lower cylinder depressurization step (step c) to the rinsing and regeneration step (step e) in the lower cylinder 11B and upper cylinder 11U are performed. Furthermore, during the period from the lower cylinder depressurization step (step c) to the rinsing and regeneration step (step e) in the lower cylinder 10B and upper cylinder 10U, the adsorption step (step a) to the rinsing step (step b) in the lower cylinder 11B and upper cylinder 11U are performed. Furthermore, the introduction of raw material gas from path L1, the removal of nitrogen from path L7, and the extraction of xenon from path L13 are carried out continuously without regard to the steps. However, in manufacturing equipment for semiconductor products or display devices using the gas separation method performed by the pressure swing adsorption gas separator 100 according to this embodiment, situations frequently arise where xenon is not needed, i.e., no exhaust gas flows from the manufacturing equipment as raw material gas. In such cases, the pressure swing adsorption gas separator 100 of this embodiment maintains a state where product gas is always available even when the supply is stopped by returning nitrogen from path L7 and xenon from path L13 to the raw material gas storage tank 1 (not shown).

[0033] Furthermore, as described later, by performing a pressure equalization and decompression step (step b2) after the rinsing step (step b) and a pressure equalization and pressurization step after the rinsing and regeneration step (step e), the power required for pressurization can be reduced.

[0034] (6) Pressure equalization and decompression steps (step b2) Close the on / off valve V14 and open the on / off valve V9. Gas in the upper cylinder 10U is introduced into the upper cylinder 11U via path L14 due to the pressure difference between the upper cylinders 10U and 11U (pressure equalization and depressurization operation). This reduces the pressure in the upper cylinder 10U, causing gas in the lower cylinder 10B to be discharged into the upper cylinder 10U. Through this operation, a small amount of nitrogen remaining in the upper part of the adsorption chamber in the lower cylinder 10B is pushed and flowed into the upper cylinder 10U by the xenon desorbing due to the depressurization. During this period, the supply of xenon from the easily adsorbed component storage tank 2 continues.

[0035] (7) Pressure equalization and pressurization step (step e2) Close valves V4, V8, V11', V13', and V15, and open valve V9. This allows gas from the upper cylinder 10U to be introduced into the upper cylinder 11U (pressure equalization and pressurization operation). Because the nitrogen concentration of the gas introduced into the upper cylinder 11U is higher, it pushes the xenon from the upper cylinder 11U down into the lower part of the upper cylinder and the lower cylinder 11B.

[0036] Figure 4 is a diagram showing half a cycle of the gas separation method using the pressure swing adsorption gas separator 100 of this embodiment, with the addition of a pressure equalization and decompression step (step b2) from the adsorption step (step a) to the washing step (step b). Figure 5 shows the steps of the additional half-cycle from the lower cylinder depressurization step (step c) to the flushing and regeneration step (step e) followed by the equalization and pressurization step (step e2). While the lower cylinder 10B and the upper cylinder 10U are performing the three steps shown in Figure 4, the lower cylinder 11B and the upper cylinder 11U are performing the four steps shown in Figure 5.

[0037] Regarding the adsorbent used in the pressure swing adsorption gas separation device of this embodiment, both equilibrium separation adsorbents (adsorbents with different selectivity depending on the equilibrium adsorption amount) and velocity separation adsorbents (adsorbents with different selectivity depending on the adsorption rate) can be used. In the case of activated carbon, one example of the aforementioned balanced separation adsorbent, the adsorption of xenon is more than 10 times greater than that of nitrogen or argon (298K, 100kPa (abs)). In the case of carbon molecular sieve (MSC), one of the aforementioned velocity separation adsorbents, the adsorption rate ratio of oxygen to nitrogen is approximately 15.

[0038] When activated carbon is used as the aforementioned adsorbent, the readily adsorbed components are, for example, at least one of the groups consisting of xenon and krypton, and the difficult-to-adsorb components are, for example, at least one of the groups consisting of oxygen, nitrogen, argon, helium, neon and hydrogen. When MSC is used as the aforementioned adsorbent, the easily adsorbed component is, for example, oxygen, and the difficult-to-adsorb component is, for example, nitrogen.

[0039] The types of readily adsorbed and poorly adsorbed components vary depending on the adsorbent used. Different adsorbents can result in readily adsorbed components becoming poorly adsorbed, and vice versa. For example, in equilibrium separation adsorbents such as activated carbon, Na-X type zeolite, Ca-X type zeolite, Ca-A type zeolite, and Li-X type zeolite, readily adsorbed components include xenon and krypton, while poorly adsorbed components include nitrogen, oxygen, hydrogen, helium, neon, and argon. Similarly, in velocity separation adsorbents such as Na-A type zeolite and MSC, readily adsorbed components include nitrogen, oxygen, and argon, while poorly adsorbed components include krypton and xenon.

[0040] <Effects> The pressure swing adsorption (PSA) gas separation device of the present invention makes the gas flow path from the adsorption cylinder (lower cylinder 10B, lower cylinder 11B) to the easily adsorbed component storage tank 2 a dedicated flow path (first dedicated flow path) with one end connected to the adsorption cylinder and the other end connected only to the easily adsorbed component storage tank 2. Specifically, the dedicated flow path (first dedicated flow path) is configured as follows: one end is connected to the adsorption cylinder via a gas flow path L4 that introduces gas from the compressor into the adsorption cylinder, and the other end is connected only to the easily adsorbed component storage tank 2. This reduces the amount of difficult-to-adsorb components mixed into the easily adsorbed component storage tank 2, and allows for the acquisition of high-purity easily adsorbed components from the easily adsorbed component storage tank 2.

[0041] Furthermore, the gas flow path that discharges the difficult-to-adsorb components from the adsorption cylinder (lower cylinder 10B, lower cylinder 11B) to the raw material gas storage tank 1 is also made into a dedicated flow path (second dedicated flow path) with one end connected to the adsorption cylinder and the other end connected only to the raw material gas storage tank 1. Specifically, the dedicated flow path (second dedicated flow path) is configured as follows: one end is connected to the adsorption cylinder via the gas flow path L4 that introduces gas from the compressor 4 into the adsorption cylinder, and the other end is connected only to the raw material gas storage tank 1. In this way, the amount of difficult-to-adsorb components mixed into the easily adsorbable component storage tank 2 can be reduced, and high-purity easily adsorbable components can be obtained from the easily adsorbable component storage tank 2.

[0042] <Second Implementation Mode> The pressure swing adsorption (PSA) gas separation device of the second embodiment of the present invention will be described with reference to the schematic diagram. Figure 6 is a schematic diagram showing the configuration of the pressure swing adsorption (PSA) gas separation device 50 of the second embodiment of the present invention. As shown in Figure 6, the pressure swing adsorption gas separation device (hereinafter referred to simply as "PSA device") 50 of this embodiment is generally configured to include: a raw material gas storage tank 1 for storing a raw material gas containing two or more components; a readily adsorbable component storage tank 2 for storing readily adsorbable components; a difficult-to-adsorb component storage tank 3 for storing difficult-to-adsorb components; a compressor 4; a compressor 5; four adsorption cylinders, namely lower cylinders 10B and 11B and upper cylinders 10U and 11U; paths L201 to L217; and on / off valves V201 to V215. The PSA device 50 of this embodiment is a device that uses the pressure swing adsorption gas separation method to separate the components from a raw material gas containing two or more components and recover them as high-concentration gas components.

[0043] The raw material gas storage tank 1, the easily adsorbed component storage tank 2, and the difficult-to-adsorb component storage tank 3 are all containers capable of storing gaseous components (raw material gas, easily adsorbed components, and difficult-to-adsorb components). The shape and size (capacity) of these containers are not particularly limited and can be appropriately selected based on the supply and recovery rates. Furthermore, the material of these containers is not particularly limited if it is a material that will not corrode due to the stored gas.

[0044] The feed gas is a mixture containing two or more components. There is no particular limitation on whether the gas mixture contains two or more gaseous components. Examples of such mixtures include those containing nitrogen and xenon.

[0045] The lower cylinders 10B and 11B and the upper cylinders 10U and 11U are adsorption cylinders in which the space inside the cylindrical container is filled with adsorbent. The shape and size (capacity) of these adsorption cylinders are not particularly limited and can be appropriately selected according to the supply rate, recovery rate, etc. Furthermore, the material of these adsorption cylinders is not particularly limited if it is a material that will not be corroded by the stored gas.

[0046] The lower cylinders 10B and 11B and the upper cylinders 10U and 11U are respectively filled with adsorbent. As for the adsorbent, it is not particularly limited whether it has easy or difficult adsorption of the target component in the raw gas, and difficult or easy adsorption of components other than the target component.

[0047] For example, when the feed gas is a mixture containing both nitrogen and xenon, activated carbon can be used as an adsorbent. In this case, regarding the equilibrium adsorption capacity, activated carbon exhibits the property of adsorbing more xenon (easy adsorption) and less nitrogen (difficult adsorption).

[0048] Paths L201 to L217 are gas paths for introducing gas into or out of the aforementioned components. Path L201 is the path for introducing raw material gas into raw material gas storage tank 1. Path L202 is connected at one end to the raw material gas storage tank 1 and at the other end to path L203 and path L215 at the branch point T. That is, path L202 is part of the gas path that leads the gas from the raw material gas storage tank 1 to the compressor 4. Path L203 is connected at one end to the easily adsorbed component storage tank 2, and at the other end to path L202 and path L215 at the branch point T. That is, path L203 is part of the gas path that leads the gas from the easily adsorbed component storage tank 2 to the compressor 4.

[0049] Path L204 branches off from path L215 and connects to the lower cylinder 10B. That is, path L204 is part of the gas path (first flow path) that introduces the compressed gas from compressor 4 into the lower cylinder 10B. Furthermore, the branch points P and R are located on the primary side of the lower cylinder 10B, respectively, of path L204. Path L205 branches off from path L215 and connects to the lower cylinder 11B. That is, path L205 is part of the gas path (first flow path) that introduces the compressed gas from compressor 4 into the lower cylinder 11B. Furthermore, the branch points Q and S are located on the primary side of the lower cylinder 11B, respectively, of path L205.

[0050] Path L206 is a gas path that merges with paths L204 and L205 respectively, and introduces the difficult-to-adsorb components exported from the upper cylinders 10U and 11U into the difficult-to-adsorb component storage tank 3. Path L207 is the gas path for discharging the difficult-to-adsorb components exported from the difficult-to-adsorb component storage tank 3 to the outside of the device system. Path L208 is part of the gas path from the difficult-to-adsorb components exported from the difficult-to-adsorb component storage tank 3 to the upper cylinders 10U and 11U respectively.

[0051] Path L209 is connected to the lower cylinder 10B via path L204 and to the raw material gas storage tank 1 via path L217. Specifically, path L209 branches off from path L204 at the branch point (second branch point) R located at the first flow path (first flow path), and merges with paths L210 and L217. That is, path L209 is located between path L204 and path L217, and is part of the flow path (third flow path) that returns gas from the lower cylinder 10B to the raw material gas storage tank 1. Path L210 is connected to the lower cylinder 11B via path L205 and to the raw material gas storage tank 1 via path L217. Specifically, path L210 branches off from path L205 at the branch point (second branch point) S located at the first flow path (first flow path), and merges with paths L209 and L217. That is, path L210 is located between path L205 and path L217, and is part of the flow path (third flow path) that returns gas from the lower cylinder 11B to the raw material gas storage tank 1.

[0052] Path L211 is connected to the lower cylinder 10B via path L204 and to the easily adsorbed component storage tank 2 via path L216. Specifically, path L211 branches off from path L204 at the branch point (first branch point) P located in path L204 (first flow path) and merges with paths L212 and L216. That is, path L211 is located between path L204 and path L216 and is part of the flow path (second flow path) that returns gas from the lower cylinder 10B to the easily adsorbed component storage tank 2. Path L212 is connected to the lower cylinder 11B via path L205 and to the easily adsorbed component storage tank 2 via path L216. Specifically, path L212 branches off from path L205 at the branch point (first branch point) Q located in path L205 (first flow path) and merges with paths L211 and L216. That is, path L212 is located between path L205 and path L216 and is part of the flow path (second flow path) that returns gas from the lower cylinder 11B to the easily adsorbed component storage tank 2.

[0053] Path L213 is a path that connects to the easily adsorbed component storage tank 2 and supplies the easily adsorbed component from the easily adsorbed component storage tank 2 to the outside of the device system. Path L214 is a voltage equalization line located between the upper cylinder 10U and the upper cylinder 11U, and which performs voltage equalization between the upper cylinder 10U and the upper cylinder 11U.

[0054] One end of path L215 branches into paths L204 and L205, and is connected to the lower cylinders 10B and 11B respectively via paths L204 and L205. The other end connects to paths L202 and L203 at the branch point T. That is, path L215 is a part of the gas path (first flow path) located between compressor 4 and lower cylinders 10B and 11B (adsorption cylinders), and is used to introduce the compressed gas discharged from compressor 4 into lower cylinders 10B and 11B. One end of path L216 branches into paths L211 and L212, and the other end is connected to the easily adsorbed component storage tank 2. That is, path L216 is part of the flow path (second flow path) located between the branching point (first branching point) P, Q and the easily adsorbed component storage tank 2, and returns the gas from the lower cylinders 10B, 11B to the easily adsorbed component storage tank 2. One end of path L217 branches into path L209 and path L210, and the other end is connected to the raw material gas storage tank 1. That is, path L217 is part of the flow path (third flow path) located between the lower cylinders 10B and 11B and the raw material gas storage tank 1, and which returns the gas from the lower cylinders 10B and 11B to the raw material gas storage tank 1.

[0055] The compressor 4 is located in path L215 and pressurizes (compresses) either the raw material gas that is discharged from the raw material gas storage tank 1 to path L215 via path L2, or the easily adsorbed component that is discharged from the easily adsorbed component storage tank 2 to path L215 via path L203, and then supplies it to the lower cylinder 10B or lower cylinder 11B via path L204 or path L205.

[0056] The compressor 4 is not specifically limited to those capable of increasing the pressure (compressing) of gas components. For example, a diaphragm compressor can be cited as such a compressor 4. Furthermore, the output of compressor 4 is not particularly limited and can be appropriately selected based on the supply and recovery of gas components.

[0057] Compressor 5 is located in path L213 and pressurizes (compresses) the easily adsorbed component discharged from the easily adsorbed component storage tank 2 to path L213 before supplying it outside the system. Compressor 5 is not particularly limited to any type capable of pressurizing (compressing) gas components. For example, a diaphragm compressor can be used as such. Furthermore, the discharge rate of compressor 5 is not particularly limited and can be appropriately selected based on the supply and recovery rates of the gas components.

[0058] The on / off valves V201 to V215 are respectively located in paths L202 to L214, and are on / off devices that open or close the flow path of gas components in the path. In this embodiment of the PSA device 50, among the on / off valves, the on / off valve (first on / off device) V212 located in path L211 is located near the branch point (first branch point) P.

[0059] Here, the so-called "opening and closing valve V212 is located near the branch point P" means that the distance between the opening and closing valve V212 and the branch point P is relatively short. This reduces the volume in the path between the opening and closing valve V212 and the branch point P. In other words, when the gas discharged from the lower cylinder 10B is discharged to the easily adsorbed component storage tank 2, the amount of gas remaining in the path L211 between the opening and closing valve V212 and the branch point P can be reduced.

[0060] Furthermore, the amount of residual gas in path L211 from the on-off valve V212 to the branch point P (residual gas amount) is the sum of the volume of the piping that constitutes path L211 from the on-off valve V212 to the branch point P and the internal volume of the on-off valve V212. In this embodiment of the PSA device 50, the amount of residual gas from the inside of the on / off valve V212 to the branch point P is preferably less than or equal to 0.1% of the volume of gas drawn by the compressor 4 in one minute.

[0061] Similarly, among the on / off valves of the PSA device 50 in this embodiment, the on / off valve (first on / off device) V213 located in path L212 is located near the branch point (first branch point) Q.

[0062] Here, the so-called "opening and closing valve V213 is located near the branch point Q" means that the distance between the opening and closing valve V213 and the branch point Q is relatively short. This reduces the volume in the path between the opening and closing valve V213 and the branch point Q. In other words, when the gas discharged from the lower cylinder 11B is discharged to the easily adsorbed component storage tank 2, the amount of gas remaining in the path L212 between the opening and closing valve V213 and the branch point Q can be reduced.

[0063] Furthermore, the amount of residual gas in path L212 from the on-off valve V213 to the branch point Q (residual gas amount) is the sum of the volume of the piping constituting path L212 from the on-off valve V213 to the branch point Q and the internal volume of the on-off valve V213. In the PSA device 50 of this embodiment, the amount of residual gas from the inside of the on / off valve V213 to the branch point Q is preferably less than or equal to 0.1% of the volume of gas drawn by the compressor 4 in one minute.

[0064] Furthermore, among the opening and closing valves of the PSA device 50 in this embodiment, the opening and closing valve (second opening and closing device) V210 located in path L209 is preferably located near the branch point (second branch point) R.

[0065] Here, the so-called "on / off valve V210 located near the branch point R" means that the distance between the on / off valve V210 and the branch point R is relatively short. This reduces the volume in the path between the on / off valve V210 and the branch point R. In other words, when the gas discharged from the lower cylinder 10B is discharged to the raw material gas storage tank 1, the amount of gas remaining in the path L209 between the on / off valve V210 and the branch point R can be reduced.

[0066] Furthermore, the amount of residual gas in the path L209 from the on-off valve V210 to the branch point R (residual gas amount) is the sum of the volume of the piping that constitutes the path L209 from the on-off valve V210 to the branch point R and the internal volume of the on-off valve V210. In this embodiment of the PSA device 50, the amount of residual gas from the inside of the on / off valve V210 to the branch point R is preferably less than or equal to 0.1% of the volume of gas drawn by the compressor 4 in one minute.

[0067] Similarly, among the on / off valves of the PSA device 50 in this embodiment, the on / off valve (second on / off device) V211 located in path L210 is preferably located near the branch point (second branch point) S.

[0068] Here, the so-called "on / off valve V211 located near the branch point S" means that the distance between the on / off valve V211 and the branch point S is relatively short. This reduces the volume in the path between the on / off valve V211 and the branch point S. In other words, when the gas discharged from the lower cylinder 11B is discharged to the raw material gas storage tank 1, the amount of gas remaining in the path L210 between the on / off valve V211 and the branch point S can be reduced.

[0069] Furthermore, the amount of residual gas in the path L210 from the on-off valve V211 to the branch point S (residual gas amount) is the sum of the volume of the piping that constitutes the path L210 from the on-off valve V211 to the branch point S and the internal volume of the on-off valve V211. In this embodiment of the PSA device 50, the amount of residual gas from the inside of the on / off valve V211 to the branch point S is preferably less than or equal to 0.1% of the volume of gas drawn by the compressor 4 in one minute.

[0070] The on / off valves V210 to V213 are not particularly limited if they can reduce the amount of gas remaining in the piping of the flow path constituting the gas components. Examples of such on / off valves include ball valves, rotary valves, bellows valves, and diaphragm valves. Because these on / off valves can reduce the volume inside the valve, they are preferable. Furthermore, among ball valves, the three-way flow path switching ball valve is superior because it can significantly reduce the piping capacity. Furthermore, among bellows-type and diaphragm-type on / off valves, the block type, such as the three-way diversion type and the double three-way valve which consists of multiple on / off valves in one block, can greatly reduce the piping capacity and has excellent drive durability, so it is particularly good.

[0071] Furthermore, in this embodiment of the PSA device 50, the aforementioned branch point (first branch point) P and branch point (second branch point) R are preferably located near the lower cylinder 10B of the path L204. Similarly, in this embodiment, the aforementioned branch point (first branch point) Q and branch point (second branch point) S of the PSA device 50 are preferably located near the lower cylinder 11B of the path L205.

[0072] Here, the so-called branching points P and R being located near the lower cylinder 10B refers to the shorter distance between branching points P and R and the lower cylinder 10B. This reduces the volume within the path L204 between branching points P and R and the lower cylinder 10B. In other words, when the gas exiting from the lower cylinder 10B is discharged to the raw material gas storage tank 1 or the easily adsorbed component storage tank 2, the amount of residual gas within the path L204 between each branching point P and R and the lower cylinder 10B can be reduced. In this embodiment, the amount of residual gas between each branch point P, R and the lower cylinder 10B of the PSA device 50 is preferably less than or equal to 1% of the volume of gas drawn by the compressor 4 in one minute.

[0073] Similarly, the so-called branching points Q and S being located near the lower cylinder 11B refers to the shorter distance between branching points Q and S and the lower cylinder 11B. This reduces the volume within the path L205 between branching points Q and S and the lower cylinder 11B. In other words, when the gas exiting from the lower cylinder 11B is discharged to the raw material gas storage tank 1 or the easily adsorbed component storage tank 2, the amount of residual gas within the path L205 between each branching point Q and S and the lower cylinder 11B can be reduced. In this embodiment, the amount of residual gas between each branch point Q, S and the lower cylinder 11B of the PSA device 50 is preferably less than or equal to 1% of the volume of gas drawn by the compressor 4 in one minute.

[0074] Furthermore, the PSA device 50 of this embodiment may also be equipped with a concentration meter in each of the above-mentioned flow paths. Regarding the specific locations of the concentration meters, examples include path L204 between the on / off valve V203 and the branch point R, path L211 between the on / off valve V212 and the branch point P, path L209 between the on / off valve V210 and the branch point R, path L205 between the on / off valve V204 and the branch point S, path L212 between the on / off valve V213 and the branch point Q, and path L210 between the on / off valve V211 and the branch point S. Furthermore, the concentration meters are preferably set as follows: near the branch point R in path L204, near the branch point P in path L211, near the branch point R in path L209, near the branch point S in path L205, near the branch point Q in path L212, and near the branch point S in path L210.

[0075] Next, the operation method of the pressure swing adsorption gas separator 50 of this embodiment will be explained. Furthermore, the following description illustrates an example where a mixed gas containing nitrogen and xenon is used as the feed gas, and activated carbon, which is a balanced separation type adsorbent, is used as the adsorbent filling the lower cylinders 10B and 11B and the upper cylinders 10U and 11U.

[0076] The operation method of the PSA device 50 in this embodiment firstly involves the following steps: (1) adsorption step, (2) rinsing step, (3) lower cylinder depressurization step, (4) upper cylinder depressurization step, (5) rinsing and regeneration step, and (6) pressure equalization and pressurization step in the lower cylinder 10B and the upper cylinder 10U.

[0077] (1) Adsorption step First, in the adsorption step, the on / off valves V202, V204, V207, V209, V210, and V212 are closed, and the on / off valves V201, V203, V205, and V214 are opened. The compressor 4 compresses the mixed gas exported from the raw material gas storage tank 1 and introduces it into the lower part of the lower cylinder 10B through paths L215 and L204. Here, the lower cylinder 10B and the upper cylinder 10U are connected by opening the on / off valve V205, so the pressure rises by approximately the same amount. Furthermore, the mixed gas exported from the raw material gas storage tank 1 is a mixture of the raw material gas introduced into the raw material gas storage tank 1 through path L201 and the gas exported from the lower cylinder 10B or lower cylinder 11B in the upper cylinder depressurization step and the flushing and regeneration step described later.

[0078] Next, the mixed gas system introduced into the lower part of the lower cylinder 10B moves upwards, causing xenon to be preferentially adsorbed by the adsorbent, and nitrogen to be concentrated in the gas phase. The concentrated nitrogen is introduced from the upper part of the lower cylinder 10B into the lower part of the upper cylinder 10U, where trace amounts of xenon contained in the nitrogen are further adsorbed. After the pressure in the upper cylinder 10U becomes higher than the pressure in the difficult-to-adsorb component storage tank 3, the nitrogen system further concentrated in the upper cylinder 10U is discharged to the difficult-to-adsorb component storage tank 3 via path L206. In addition, the nitrogen stored in the difficult-to-adsorb components storage tank 3 is discharged from the device system through path L207 at a flow rate corresponding to the nitrogen contained in the raw material gas, and the remaining nitrogen is used as the countercurrent flushing gas in the flushing and regeneration step described later.

[0079] (2) Rinsing steps Next, in the rinsing step, the on / off valve V201 is closed and the on / off valve V202 is opened to introduce xenon from the easily adsorbed component storage tank 2 into the lower part of the lower cylinder 10B. By introducing xenon, which is an easily adsorbed component, into the lower cylinder 10B, nitrogen in the adsorbent packing layer co-adsorbed in the lower cylinder 10B and nitrogen present in the voids of the adsorbent are pushed from the lower cylinder 10B to the upper cylinder 10U, thereby saturating the lower cylinder 10B with xenon. Next, by closing the on / off valves V207, V208, V214, and V215 and opening the on / off valve V209, nitrogen from the upper part of the upper cylinder 10U is transported to the upper cylinder 11U via path L214.

[0080] (3) Lower cylinder decompression step Next, in the lower cylinder depressurization step, on / off valves V203, V205, and V210 are closed, while on / off valve V212 is opened. Thus, the xenon system adsorbed in the lower cylinder 10B during the adsorption to rinsing steps is recovered to the easily adsorbed component storage tank 2 via paths L211 and L216 due to the differential pressure between the lower cylinder 10B and the easily adsorbed component storage tank 2. The xenon recovered to the easily adsorbed component storage tank 2 is pressurized by compressor 5 and collected from path L213 as a product. The remaining xenon is used as a co-current rinsing gas in the rinsing step described above. In addition, during the pressure reduction step of the lower cylinder, the on / off valves V205, V207, V209, and V214 are closed to stop the upper cylinder 10U.

[0081] In this embodiment of the PSA apparatus 50, the on / off valve (first on / off device) V212 of the flow path (second flow path) L211 between the lower cylinder 10B and the easily adsorbed component storage tank 2 is located near the branch point P, reducing the volume of the path L211 from the inside of the on / off valve V212 to the branch point P. This reduces the amount of mixed gas remaining in the path L211 from the inside of the on / off valve V212 to the branch point P during the adsorption step. Therefore, during the lower cylinder depressurization step, when the high-purity xenon exiting from the lower cylinder 10B passes through path L204 and path L211, the amount of impurities mixed is reduced. As a result, during the lower cylinder depressurization step, xenon, which is an easily adsorbed component, can be recovered in high purity to the easily adsorbed component storage tank 2.

[0082] (4) Upper cylinder decompression step Next, in the upper cylinder depressurization step, on / off valves V203, V207, V209, V211, V212, and V214 are closed, while on / off valves V205 and V210 are opened. This allows gas from the upper cylinder 10U to be introduced into the lower cylinder 10B by the pressure difference between the upper cylinder 10U (which was stopped during the lower cylinder depressurization step) and the depressurized lower cylinder 10B. The gas system introduced into the lower cylinder 10B is flushed within the lower cylinder 10B and then discharged from the lower cylinder 10B, being recovered to the raw material gas storage tank 1 via paths L210 and L217. The gas system recovered to the raw material gas storage tank 1 is mixed with the raw material gas introduced from path L201 and used as a mixed gas in the aforementioned adsorption step.

[0083] (5) Rinsing and regeneration steps Next, in the rinsing and regeneration step, valves V203, V209, V212, and V214 are closed, while valves V205, V207, and V210 are opened. This allows the nitrogen system stored in the difficult-to-adsorb component storage tank 3 to be introduced as countercurrent rinsing gas from above the upper cylinder 10U via path L208. As the nitrogen system introduced into the upper cylinder 10U moves downwards, it displaces and desorbs the xenon adsorbed by the adsorbent. The gas system containing a relatively large amount of xenon desorbed from the adsorbent is then discharged from the upper cylinder 10U and recovered to the feed gas storage tank 1 via the lower cylinder 11B, path L210, and path L217. Similar to the upper cylinder depressurization step described above, the gas system recovered to the feed gas storage tank 1 is mixed with the feed gas introduced from path L201 and used as a mixed gas in the aforementioned adsorption step. Alternatively, nitrogen extracted from the upper cylinder 10U in the above-mentioned adsorption step can be used as a countercurrent flushing gas and directly introduced into the upper cylinder 10U in the flushing and regeneration step to replace the nitrogen stored in the storage tank 3 for difficult-to-adsorb components.

[0084] In this embodiment of the PSA apparatus 50, the on / off valve (second on / off device) V210 of the flow path (third flow path) L209 between the lower cylinder 10B and the raw material gas storage tank 1 is located near the branch point R, reducing the volume of the path L209 from the inside of the on / off valve V210 to the branch point R. This reduces the amount of xenon remaining in the path L209 from the inside of the on / off valve V210 to the branch point R during the upper cylinder depressurization step and the flushing and regeneration step. Therefore, in the adsorption step, the mixed gas stored in the raw material gas storage tank 1 can be introduced into the lower cylinder 10B without changing the xenon concentration in the mixed gas.

[0085] (6) Pressure equalization and pressurization steps Next, in the pressure equalization and pressurization step, valves V203, V207, V208, V210, V212, V214, and V215 are closed, while valve V209 is opened. Here, during the pressure equalization and pressurization step in the lower cylinder 10B and upper cylinder 10U, the aforementioned rinsing step is performed in both the lower cylinder 11B and upper cylinder 11U. During the pressure equalization and pressurization step, the nitrogen system derived from the upper cylinder 11U, which is undergoing the rinsing step, is introduced into the upper cylinder 10U and lower cylinder 10B via path L214.

[0086] Furthermore, when returning from the "pressure equalization and pressurization step" to the "adsorption step", the on / off valve V201 is opened and the on / off valve V202 is closed. Next, the mixed gas exported from the raw material gas storage tank 1 is compressed by the compressor 4 and introduced into the lower part of the lower cylinder 10B via paths L215 and L204.

[0087] In this embodiment, the PSA device 50 performs the same six steps as the lower cylinder 10B and upper cylinder 10U in sequence in the lower cylinder 11B and upper cylinder 11U. Here, while the "adsorption step" to the "rinsing step" is being carried out in one adsorption cylinder (lower cylinder 10B and upper cylinder 10U), the "lower cylinder depressurization step" to the "rinsing and regeneration step" to the "pressure equalization and pressurization step" are being carried out in the other adsorption cylinder (lower cylinder 11B and upper cylinder 11U). Furthermore, while one adsorption cylinder is undergoing the "lower cylinder depressurization step" to the "rinsing and regeneration step" to the "pressure equalization and pressurization step", the other adsorption cylinder is undergoing the "adsorption step" to the "rinsing step".

[0088] According to the PSA apparatus 50 of this embodiment, by sequentially and repeatedly performing the above six steps between the lower cylinder 10B and the upper cylinder 10U and between the lower cylinder 11B and the upper cylinder 11U, nitrogen concentration and xenon concentration can be continuously performed.

[0089] Furthermore, in the PSA device 50 of this embodiment, the introduction of raw gas from path L201 to the raw gas storage tank 1, the discharge of nitrogen from the difficult-to-adsorb component storage tank 3 via path L207, and the extraction of xenon from the easily-adsorbed component storage tank 2 via path L213 are performed continuously, regardless of the steps described above.

[0090] According to the PSA device 50 of this embodiment, high-purity xenon can be separated and recovered from the feed gas. Furthermore, the purity of the xenon separated and recovered by the PSA device 50 in this embodiment is not particularly limited, but it is preferably greater than or equal to 99% by volume, more preferably greater than or equal to 99.9% by volume, and even more preferably greater than or equal to 99.95% by volume.

[0091] The PSA device 50 of this embodiment can be used as part of a manufacturing facility for semiconductor products or display devices. According to the PSA device 50 of this embodiment, exhaust gas discharged from the manufacturing facility can be used as a feed gas, and after separating and recovering the xenon contained in the feed gas, high-purity xenon can be supplied to the manufacturing facility.

[0092] Furthermore, when the PSA device 50 of this embodiment is used as part of the aforementioned manufacturing equipment, situations frequently arise where xenon supply is not required or where the raw material gas (i.e., the exhaust gas from the manufacturing equipment) does not flow in. In such cases, the PSA device 50 of this embodiment returns nitrogen discharged from the difficult-to-adsorb component storage tank 3 via path L207, or xenon led out from the easily-adsorbed component storage tank 2 via path L213, to the raw material gas storage tank 1, thereby maintaining a state where product gas (xenon) can always be supplied even when the supply stops.

[0093] As described above, in the PSA apparatus 50 of this embodiment, the on / off valve (first on / off device) V212 located in the path L211 of the flow path (second flow path) between the lower cylinder 10B and the easily adsorbed component storage tank 2 is located near the branch point P. This reduces the volume of the path L211 from the inside of the on / off valve V212 to the branch point P, thus reducing the amount of gas remaining in the path. Therefore, in the PSA apparatus 50 of this embodiment, when the easily adsorbed component (gas) is discharged from the lower cylinder 10B to the easily adsorbed component storage tank 2, the amount of impurities (components other than xenon in the raw material gas) mixed with xenon can be reduced, and high-purity xenon (easily adsorbed component) can be separated and recovered as a product.

[0094] Furthermore, in the PSA device 50 of this embodiment, the branch point P of path L204 is located near the lower cylinder 10B. This reduces the volume of path L204 from branch point P to the lower cylinder 10B. Therefore, in the PSA device 50 of this embodiment, when the easily adsorbed component (gas) is discharged from the lower cylinder 10B to the easily adsorbed component storage tank 2, the amount of gas remaining in the path blocked by the lower cylinder 10B, path L204, path L211, and the on / off valve V212 can be further reduced.

[0095] According to the PSA device 50 of this embodiment, the on / off valve (second on / off device) V210 located in path L209, which forms the flow path (third flow path) between the lower cylinder 10B and the raw material gas storage tank 1, is located near the branch point R. Furthermore, the branch point R in path L204 is located near the lower cylinder 10B. Therefore, when the mixed gas is discharged from the lower cylinder 10B to the raw material gas storage tank 1, the amount of gas remaining in the path blocked by the lower cylinder 10B, path L204, path L209, and on / off valve V210 can be further reduced.

[0096] Furthermore, the PSA device 50 of this embodiment is configured such that easily adsorbed components do not pass through the branch point R (branch point S). This configuration is such that the branch point P (branch point Q) on path L204 (L205) is closer to the lower cylinder 10B (11B) than the branch point R (branch point S) on path L217, which forms the return path to the raw material gas storage tank 1. However, the above configuration is an example, and the present invention is not limited to this configuration. That is, in the PSA device 50 of this embodiment, the positional relationship between the branch point P (branch point Q) and the branch point R (branch point S) on path L204 (L205) can also be reversed. Furthermore, the branch point P (branch point Q) and the branch point R (branch point S) can be located at the same position by using a cross joint.

[0097] <Third Implementation Mode> Next, the PSA device according to the third embodiment of the present invention will be described in detail with reference to FIG7. As shown in Figure 7, compared to the PSA device 50 of the second embodiment, which has a path L209 branching off from the branch point R of path L204, the PSA device of this embodiment has a path L209' directly connected to the lower cylinder 10B. The two differ in this respect, but their other configurations are the same. Therefore, for the PSA device 60 of this embodiment, the same reference numerals are used for components that are identical in configuration to those of the PSA device 50 of the second embodiment, and descriptions are omitted.

[0098] One end of path L209' is connected to the lower cylinder 10B, and the other end merges with paths L210' and L217'. That is, path L209' is part of the flow path (third flow path) located between the lower cylinder 10B and path L217', which sends the gas from the lower cylinder 10B back to the raw material gas storage tank 1. One end of path L210' is connected to the lower cylinder 11B, and the other end merges with path L209' and path L217'. That is, path L210' is part of the flow path (third flow path) located between the lower cylinder 11B and path L217', which sends the gas from the lower cylinder 11B back to the raw material gas storage tank 1.

[0099] One end of path L217' branches to paths L209' and L210', and the other end connects to the raw material gas storage tank 1. That is, path L217' is part of the flow path (third flow path) located between the lower cylinders 10B and 11B and the raw material gas storage tank 1, and which returns the gas from the lower cylinders 10B and 11B to the raw material gas storage tank 1.

[0100] Of the on / off valves in the PSA device 60 of this embodiment, the on / off valve (second on / off device) V210 located in path L209' is preferably located near the lower cylinder 10B.

[0101] Here, the so-called "on / off valve V210 is located near the lower cylinder 10B" means that the distance between the on / off valve V210 and the lower cylinder 10B is relatively short. This reduces the volume within the path L209' between the on / off valve V210 and the lower cylinder 10B. In other words, when the gas discharged from the lower cylinder 10B is discharged to the raw material gas storage tank 1, the amount of gas remaining within the path L209' between the on / off valve V210 and the lower cylinder 10B can be reduced.

[0102] Furthermore, the amount of residual gas in the path L209' from the on-off valve V210 to the lower cylinder 10B (residual gas amount) is the sum of the volume of the piping constituting the path L209' from the on-off valve V210 to the lower cylinder 10B and the internal volume of the on-off valve V210. In this embodiment of the PSA device 60, the volume of the path L209' from the inside of the on / off valve V210 to the lower cylinder 10B is preferably less than or equal to 0.1% of the volume of gas drawn by the compressor 4 in one minute.

[0103] Similarly, among the on / off valves of the PSA device 60 in this embodiment, the on / off valve (second on / off device) V211 located in path L210' is preferably located near the lower cylinder 10B.

[0104] Here, the so-called "on / off valve V211 is located near the lower cylinder 11B" means that the distance between the on / off valve V211 and the lower cylinder 11B is relatively short. This reduces the volume within the path L210' between the on / off valve V211 and the lower cylinder 10B. In other words, when the gas discharged from the lower cylinder 11B is discharged to the raw material gas storage tank 1, the amount of gas remaining within the path L210' between the on / off valve V211 and the lower cylinder 10B can be reduced.

[0105] Furthermore, the amount of residual gas in the path L210' from the on-off valve V211 to the lower cylinder 11B (residual gas amount) is the sum of the volume of the piping that constitutes the path L210' from the on-off valve V211 to the lower cylinder 11B and the internal volume of the on-off valve V211. In this embodiment of the PSA device 60, the volume of the path L210' from the inside of the on / off valve V211 to the lower cylinder 11B is preferably less than or equal to 0.1% of the volume of gas drawn by the compressor 4 in one minute.

[0106] As explained above, the PSA device 60 according to this embodiment can achieve the same effect as the PSA device 50 of the first embodiment described above. Furthermore, according to the PSA device 60 of this embodiment, by having a path L209' directly connected to the lower cylinder 10B and by setting the on / off valve V210 near the lower cylinder 10B, the amount of gas remaining in the path can be further reduced.

[0107] <Fourth Implementation Mode> The pressure swing adsorption (PSA) gas separation device of the fourth embodiment of the present invention will be described with reference to the drawings. Figure 8 is a schematic configuration diagram of the pressure swing adsorption (PSA) gas separation device 70 of the fourth embodiment of the present invention. As shown in Figure 8, the pressure swing adsorption gas separation device (hereinafter referred to simply as "PSA device") 70 of this embodiment is generally configured to include: a raw material gas storage tank 1 for storing a raw material gas containing two or more components; a readily adsorbable component storage tank 2 for storing readily adsorbable components; a difficult-to-adsorb component storage tank 3 for storing difficult-to-adsorb components; a compressor 4; a compressor 5; four adsorption cylinders, namely lower cylinders 10B and 11B and upper cylinders 10U and 11U; paths L301 to L315; and on / off valves V301 to V315. The PSA device 70 of this embodiment is a device that uses the pressure swing adsorption gas separation method to separate the components from a raw material gas containing two or more components and recover them as high-concentration gas components.

[0108] The raw material gas storage tank 1, the easily adsorbed component storage tank 2, and the difficult-to-adsorb component storage tank 3 are all containers capable of storing gaseous components (raw material gas, easily adsorbed components, and difficult-to-adsorb components). The shape and size (capacity) of these containers are not particularly limited and can be appropriately selected based on the supply and recovery rates. Furthermore, the material of these containers is not particularly limited if it is a material that will not corrode due to the stored gas.

[0109] The feed gas is a mixture containing two or more components. There is no particular limitation on whether the gas mixture contains two or more gaseous components. Examples of such mixtures include those containing nitrogen and xenon.

[0110] The lower cylinders 10B and 11B and the upper cylinders 10U and 11U are adsorption cylinders in which the space inside the cylindrical container is filled with adsorbent. The shape and size (capacity) of these adsorption cylinders are not particularly limited and can be appropriately selected according to the supply rate, recovery rate, etc. Furthermore, the material of these adsorption cylinders is not particularly limited if it is a material that will not be corroded by the stored gas.

[0111] The lower cylinders 10B and 11B and the upper cylinders 10U and 11U are respectively filled with adsorbent. As for the adsorbent, it is not particularly limited whether it has easy or difficult adsorption of the target component in the raw gas, and difficult or easy adsorption of components other than the target component.

[0112] For example, when the feed gas is a mixture containing both nitrogen and xenon, activated carbon can be used as an adsorbent. In this case, regarding the equilibrium adsorption capacity, activated carbon exhibits the property of adsorbing more xenon (easy adsorption) and less nitrogen (difficult adsorption).

[0113] Paths L301 to L315 are gas paths for introducing gas into or out of the aforementioned components. Path L301 is the gas flow path that introduces the raw material gas into the raw material gas storage tank 1. Path (second flow path) L302 is connected at one end to the raw material gas storage tank 1 and at the other end to path L303 and path L315 at the branch point T. That is, path L302 is part of the gas path that leads the gas from the raw material gas storage tank 1 to the compressor 4. Path (third flow path) L303 is connected at one end to the easily adsorbed component storage tank 2 and at the other end to path L302 and path L315 at the branch point T. That is, path L303 is part of the gas path that leads the gas from the easily adsorbed component storage tank 2 to the compressor 4. Paths L304 and L305 branch off from path L315 and respectively introduce gas from compressor 4 into the lower cylinders 10B and 11B. Path L306 is a gas path that merges with paths L304 and L305 respectively, and introduces the difficult-to-adsorb components exported from the upper cylinders 10U and 11U into the difficult-to-adsorb component storage tank 3. Path L307 is the gas path for discharging the difficult-to-adsorb components exported from the difficult-to-adsorb component storage tank 3 to the outside of the device system. Path L308 is part of the gas path that introduces the difficult-to-adsorb components exported from the difficult-to-adsorb component storage tank 3 into the upper cylinders 10U and 11U respectively.

[0114] Paths L309 and L310 are respectively connected to the lower cylinders 10B and 11B, and send the gas from the lower cylinders 10B and 11B back to the raw material gas storage tank 1. Paths L311 and L312 are respectively connected to the lower cylinders 10B and 11B, and return the gas from the lower cylinders 10B and 11B to the easily adsorbed component storage tank 2. Path L313 is a path that connects to the easily adsorbed component storage tank 2 and supplies the easily adsorbed component from the easily adsorbed component storage tank 2 to the outside of the device system. Path L314 is a voltage equalization line located between the upper cylinder 10U and the upper cylinder 11U, and which performs voltage equalization between the upper cylinder 10U and the upper cylinder 11U.

[0115] One end of path (first flow path) L315 branches into path L304 and path L305, and is connected to the lower cylinders 10B and 11B respectively via path L304 and path L305. The other end is connected to path L302 and path L303 at the branch point T. In the PSA device 70 of this embodiment, paths L302, L303 and L315 constitute flow paths that branch into three directions at the branching point T.

[0116] The compressor 4 is located in path L315 and pressurizes (compresses) either the raw material gas that is discharged from the raw material gas storage tank 1 to path L315 via path L302, or the easily adsorbed component that is discharged from the easily adsorbed component storage tank 2 to path L315 via path L303, and then supplies it to the lower cylinder 10B or lower cylinder 11B via path L304 or path L305.

[0117] The compressor 4 is preferably located near the branch point T in path L315. Here, "compressor 4 near the branch point T" means that the distance between the compressor 4 and the branch point T is relatively short. This reduces the volume within path L315 on the primary side of the compressor 4. In other words, it reduces the amount of gas remaining in the path from the compressor 4 to the branch point T.

[0118] The compressor 4 is not particularly limited if it is capable of increasing the pressure (compressing) of gas components. For example, a diaphragm compressor can be cited as such a compressor 4. Furthermore, the output of compressor 4 is not particularly limited and can be appropriately selected based on the supply and recovery of gas components.

[0119] Compressor 5 is located in path L313 and pressurizes (compresses) the readily adsorbed component discharged from the readily adsorbed component storage tank 2 to path L313, and then supplies it outside the device system. Compressor 5 is not particularly limited to any type capable of pressurizing (compressing) gas components. For example, a diaphragm compressor can be used as such a compressor 5. Furthermore, the discharge rate of compressor 5 is not particularly limited and can be appropriately selected based on the supply and recovery rates of the gas components.

[0120] The on / off valves V301 to V315 are respectively located in paths L302 to L314, and are on / off devices that open or close the flow path of gas components in the path. In this embodiment of the PSA device 70, among the on / off valves, the on / off valve (first on / off device) V301 located in path L302 is located near the branch point T.

[0121] Here, the so-called "on / off valve V301 located near the branch point T" refers to the short distance between the on / off valve V301 and the branch point T. This reduces the volume within the path between the on / off valve V301 and the branch point T in the three paths L302, L303, and L315 that branch at the branch point T. In other words, when the raw material gas (mixed gas) is discharged from the raw material gas storage tank 1 to the compressor 4, the amount of gas remaining in the path between the on / off valve V301 and the branch point T can be reduced.

[0122] Furthermore, the amount of residual gas in path L302 from the on-off valve V301 to the branch point T (residual gas amount) is the sum of the volume of the piping constituting path L302 from the on-off valve V301 to the branch point T and the internal volume of the on-off valve V301. In the PSA device 70 of this embodiment, the volume of the path L302 from the inside of the on / off valve V301 to the branch point T is preferably less than or equal to 1% of the volume of gas drawn by the compressor 4 in one minute.

[0123] Furthermore, in the PSA device 70 of this embodiment, the on / off valve (second on / off device) V302 located in path L303 is preferably located near the branch point T. Here, the phrase "the on / off valve V302 is located near the branch point T" means that the distance between the on / off valve V302 and the branch point T is relatively short. The amount of residual gas in path L303 from the on-off valve V302 to the branch point T (residual gas amount) is the sum of the volume of the piping that forms path L303 from the on-off valve V302 to the branch point T and the internal volume of the on-off valve V302. In the PSA device 70 of this embodiment, the volume of the path L303 from the inside of the on / off valve V302 to the branch point T is preferably less than or equal to 1% of the volume of gas drawn by the compressor 4 in one minute.

[0124] The on / off valves V301 and V302 are not particularly limited if they can reduce the amount of gas remaining in the piping of the flow path constituting the gas components. Examples of such on / off valves include ball valves, rotary valves, bellows valves, and diaphragm valves. Because these on / off valves can reduce the volume inside the valve, they are preferable. Furthermore, among ball valves, the three-way flow path switching ball valve is superior because it can significantly reduce the piping capacity. Furthermore, among bellows-type and diaphragm-type on / off valves, the block type, such as the three-way diversion type and the double three-way valve which consists of multiple on / off valves in one block, can greatly reduce the piping capacity and has excellent drive durability, so it is particularly good.

[0125] Next, the operation method of the pressure swing adsorption gas separator 70 of this embodiment will be explained. Furthermore, the following description illustrates an example where a mixed gas containing nitrogen and xenon is used as the feed gas, and activated carbon, which is a balanced separation type adsorbent, is used as the adsorbent filling the lower cylinders 10B and 11B and the upper cylinders 10U and 11U.

[0126] The operation method of the PSA device 70 in this embodiment firstly involves the following steps: (1) adsorption step, (2) rinsing step, (3) lower cylinder depressurization step, (4) upper cylinder depressurization step, (5) rinsing and regeneration step, and (6) pressure equalization and pressurization step in the lower cylinder 10B and the upper cylinder 10U.

[0127] (1) Adsorption step First, in the adsorption step, the on / off valves V302, V304, V307, V309, V310, and V312 are closed, and the on / off valves V301, V303, V305, and V314 are opened. The compressor 4 compresses the mixed gas exported from the raw material gas storage tank 1 and introduces it into the lower part of the lower cylinder 10B through paths L315 and L304. Here, the lower cylinder 10B and the upper cylinder 10U are connected by opening the on / off valve V305, so the pressure rises by approximately the same amount. Furthermore, the mixed gas exported from the raw material gas storage tank 1 is a mixture of the raw material gas introduced into the raw material gas storage tank 1 through path L301 and the gas exported from the lower cylinder 10B or lower cylinder 11B in the upper cylinder depressurization step and the flushing and regeneration step described later.

[0128] Next, the mixed gas system introduced into the lower part of the lower cylinder 10B moves upwards, causing xenon to be preferentially adsorbed by the adsorbent, and nitrogen to be concentrated in the gas phase. The concentrated nitrogen is introduced from the upper part of the lower cylinder 10B into the lower part of the upper cylinder 10U, where trace amounts of xenon contained in the nitrogen are further adsorbed. After the pressure in the upper cylinder 10U becomes higher than the pressure in the difficult-to-adsorb component storage tank 3, the nitrogen system further concentrated in the upper cylinder 10U is discharged to the difficult-to-adsorb component storage tank 3 via path L306. In addition, the nitrogen stored in the difficult-to-adsorb components storage tank 3 is discharged from the outside of the device system through path L307 at a flow rate corresponding to the nitrogen contained in the raw material gas, and the remaining nitrogen is used as the countercurrent flushing gas in the flushing and regeneration step described later.

[0129] (2) Rinsing steps Next, in the rinsing step, the on / off valve V301 is closed and the on / off valve V302 is opened to introduce xenon from the easily adsorbed component storage tank 2 into the lower part of the lower cylinder 10B. By introducing xenon, which is an easily adsorbed component, into the lower cylinder 10B, nitrogen in the adsorbent packing layer co-adsorbed in the lower cylinder 10B and nitrogen existing in the voids of the adsorbent are pushed from the lower cylinder 10B to the upper cylinder 10U, thereby saturating the lower cylinder 10B with xenon. Next, by closing the on / off valves V307, V308, V314, and V315 and opening the on / off valve V309, nitrogen from the upper part of the upper cylinder 10U is transported to the upper cylinder 11U via path L314.

[0130] (3) Lower cylinder decompression step Next, in the lower cylinder depressurization step, on / off valves V303, V305, and V310 are closed, while on / off valve V312 is opened. Thus, the xenon system adsorbed in the lower cylinder 10B during the adsorption to rinsing steps is recovered to the readily adsorbed component storage tank 2 via path L311 by the differential pressure between the lower cylinder 10B and the readily adsorbed component storage tank 2. The xenon recovered to the readily adsorbed component storage tank 2 is pressurized by compressor 5 and collected from path L313 as a product. The remaining xenon is used as a co-current rinsing gas in the rinsing step described above. In addition, during the pressure reduction step of the lower cylinder, the on / off valves V305, V307, V309, and V314 are closed to stop the upper cylinder 10U.

[0131] In this embodiment of the PSA apparatus 70, the on / off valve (first on / off device) V301 located in the path (second flow path) L302 connected to the raw material gas storage tank 1 is positioned near the branch point T, reducing the volume of the path L302 from the inside of the on / off valve V301 to the branch point T. This reduces the amount of mixed gas remaining in the path L302 from the inside of the on / off valve V301 to the branch point T during the adsorption step, allowing high-purity xenon to be introduced into the lower cylinder 10B during the rinsing step, thus ensuring high-purity xenon within the lower cylinder 10B. Consequently, during the lower cylinder depressurization step, xenon belonging to the easily adsorbed component can be recovered in high purity to the easily adsorbed component storage tank 2.

[0132] (4) Upper cylinder decompression step Next, in the upper cylinder depressurization step, on / off valves V303, V307, V309, V311, V312, and V314 are closed, while on / off valves V305 and V310 are opened. This allows gas from the upper cylinder 10U to be introduced into the lower cylinder 10B by the pressure difference between the upper cylinder 10U (which was stopped during the lower cylinder depressurization step) and the depressurized lower cylinder 10B. The gas system introduced into the lower cylinder 10B is flushed inside the lower cylinder 10B and then discharged from the lower cylinder 10B, being recovered to the raw material gas storage tank 1 via path L310. The gas system recovered to the raw material gas storage tank 1 is mixed with the raw material gas introduced from path L301 and used as a mixed gas in the aforementioned adsorption step.

[0133] (5) Rinsing and regeneration steps Next, in the rinsing and regeneration step, valves V303, V309, V312, and V314 are closed, while valves V305, V307, and V310 are opened. This allows the nitrogen system stored in the difficult-to-adsorb component storage tank 3 to be introduced as a countercurrent rinsing gas from above the upper cylinder 10U via path L308. As the nitrogen system introduced into the upper cylinder 10U moves downwards, it displaces and desorbs the xenon adsorbed by the adsorbent. The gas system containing a relatively large amount of xenon desorbed from the adsorbent is then discharged from the upper cylinder 10U and recovered to the feed gas storage tank 1 via the lower cylinder 10B and path L310. Similar to the upper cylinder depressurization step described above, the gas system recovered to the feed gas storage tank 1 is mixed with the feed gas introduced from path L301 and used as a mixed gas in the aforementioned adsorption step. Alternatively, nitrogen extracted from the upper cylinder 10U in the above-mentioned adsorption step can be used as a countercurrent flushing gas and directly introduced into the upper cylinder 10U in the flushing and regeneration step to replace the nitrogen stored in the storage tank 3 for difficult-to-adsorb components.

[0134] (6) Pressure equalization and pressurization steps Next, in the pressure equalization and pressurization step, valves V303, V307, V308, V310, V312, V314, and V315 are closed, while valve V309 is opened. Here, during the pressure equalization and pressurization step in the lower cylinder 10B and upper cylinder 10U, the aforementioned rinsing step is performed in both the lower cylinder 11B and upper cylinder 11U. During the pressure equalization and pressurization step, the nitrogen system derived from the upper cylinder 11U, which is undergoing the rinsing step, is introduced into the upper cylinder 10U and lower cylinder 10B via path L314.

[0135] Furthermore, when returning from the "pressure equalization and pressurization step" to the "adsorption step", the on / off valve V301 is opened and the on / off valve V302 is closed. Next, the mixed gas exported from the raw material gas storage tank 1 is compressed by the compressor 4 and introduced into the lower part of the lower cylinder 10B through paths L315 and L304.

[0136] In this embodiment of the PSA device 70, the on / off valve (second on / off device) V302 located in the flow path (third flow path) L303 connected to the easily adsorbed component storage tank 2 is located near the branch point T, reducing the volume of the path L303 from the inside of the on / off valve V302 to the branch point T. This reduces the amount of xenon remaining in the path L303 from the inside of the on / off valve V302 to the branch point T during the aforementioned rinsing step. Therefore, during the adsorption step, the mixed gas stored in the raw material gas storage tank 1 can be introduced into the lower cylinder 10B without changing the xenon concentration in the mixed gas.

[0137] In this embodiment, the PSA device 70 performs the same six steps as the lower cylinder 10B and upper cylinder 10U in sequence in the lower cylinder 11B and upper cylinder 11U. Here, while the "adsorption step" to the "rinsing step" is being carried out in one adsorption cylinder (lower cylinder 10B and upper cylinder 10U), the "lower cylinder depressurization step" to the "rinsing and regeneration step" to the "pressure equalization and pressurization step" are being carried out in the other adsorption cylinder (lower cylinder 11B and upper cylinder 11U). Furthermore, while one adsorption cylinder is undergoing the "lower cylinder depressurization step" to the "rinsing and regeneration step" to the "pressure equalization and pressurization step", the other adsorption cylinder is undergoing the "adsorption step" to the "rinsing step".

[0138] According to the PSA apparatus 70 of this embodiment, by sequentially and repeatedly performing the above six steps between the lower cylinder 10B and the upper cylinder 10U and between the lower cylinder 11B and the upper cylinder 11U, nitrogen concentration and xenon concentration can be continuously performed.

[0139] Furthermore, in the PSA device 70 of this embodiment, the introduction of raw gas from path L301 to the raw gas storage tank 1, the discharge of nitrogen from the difficult-to-adsorb component storage tank 3 via path L307, and the extraction of xenon from the easily-adsorbed component storage tank 2 via path L313 are performed continuously, regardless of the steps described above.

[0140] According to the PSA device 70 of this embodiment, high-purity xenon can be separated and recovered from the feed gas. Furthermore, the purity of the xenon separated and recovered by the PSA device 70 of this embodiment is not particularly limited, but it is preferably greater than or equal to 99% by volume, more preferably greater than or equal to 99.9% by volume, and even more preferably greater than or equal to 99.95% by volume.

[0141] The PSA device 70 of this embodiment can be used as part of a manufacturing facility for semiconductor products or display devices. According to the PSA device 70 of this embodiment, exhaust gas discharged from the manufacturing facility can be used as a feed gas, and after separating and recovering the xenon contained in the feed gas, high-purity xenon can be supplied to the manufacturing facility.

[0142] Furthermore, when the PSA device 70 of this embodiment is used as part of the aforementioned manufacturing equipment, situations frequently arise where xenon supply is not required or where the raw material gas (i.e., the exhaust gas from the manufacturing equipment) does not flow in. In such cases, the PSA device 70 of this embodiment returns nitrogen discharged from the difficult-to-adsorb component storage tank 3 via path L307, or xenon led out from the easily-adsorbed component storage tank 2 via path L313, to the raw material gas storage tank 1, thereby maintaining a state where product gas (xenon) can always be supplied even when the supply stops.

[0143] As described above, in the PSA apparatus 70 of this embodiment, the on / off valve (first on / off device) V301 located in the path (second flow path) L302 connected to the feed gas storage tank 1 is located near the branch point T. This reduces the volume of the path L302 from the inside of the on / off valve V301 to the branch point T, thus reducing the amount of gas remaining in the path. Therefore, in the PSA apparatus 70 of this embodiment, when switching paths during operation, the amount of impurities (components other than xenon in the feed gas) mixed with xenon can be reduced, and high-purity xenon (easily adsorbed components) can be separated and recovered as a product.

[0144] Furthermore, in the PSA device 70 of this embodiment, the compressor 4 located in the path (first flow path) L315 communicating with the lower cylinder 10B and the lower cylinder 11B is located near the branch point T, and the on / off valve (second on / off device) V302 located in the path (third flow path) L303 communicating with the easily adsorbed component storage tank 2 is located near the branch point T. This reduces the volume within the primary side path L315 of the compressor 4 and the volume within the path L303 from the inside of the on / off valve V302 to the branch point T, thereby reducing the amount of residual gas in the paths from the compressor 4 to the branch point T and from the on / off valve V302 to the branch point T. Therefore, according to the PSA device 70 of this embodiment, when the raw material gas (mixed gas) is discharged from the raw material gas storage tank 1 to the compressor 4, or when the easily adsorbed component (gas) is discharged from the easily adsorbed component storage tank 2 to the compressor 4, the amount of gas remaining in the path blocked by the compressor 4, the on / off valve V301 and the on / off valve V302 can be further reduced.

[0145] Furthermore, the scope of the present invention is not limited to the above-described embodiments, but also includes designs that do not depart from the spirit of the present invention. The PSA device 70 described above is illustrated by an example of a configuration in which a compressor 4 is provided in the path (first flow path) L315 communicating with the lower cylinder 10B and the lower cylinder 11B, but it is not limited thereto. For example, as shown in FIG9, the compressor 4 located in the first flow path L315 may be replaced by a configuration in which a first compressor 4a is provided on the primary side of the on / off valve (first on / off valve) V301 located in the flow path (second flow path) L302, and a second compressor 4b is provided on the primary side of the on / off valve (second on / off valve) V302 located in the flow path (third flow path) L303.

[0146] [Example] The present invention will be described in more detail below through embodiments. However, the present invention is not limited to the embodiments described below. Various modifications can be made as long as they do not depart from the spirit of the present invention.

[0147] [Example 1] Using the pressure swing adsorption gas separation device 100 shown in Figure 1 (with a schematic configuration), an experiment was conducted to separate xenon using a mixture of xenon (easily adsorbed component) and nitrogen or argon (difficult-to-adsorb component) as the feed gas.

[0148] Cylindrical containers made of stainless steel (80A, inner diameter 83.1mm, filling height 500mm) filled with 1.5kg of activated carbon were used as lower cylinders 10B and 11B, and upper cylinders 10U and 11U. The apparatus operated with a cycle time of 600 seconds, and the time and valve opening / closing control for each step were performed under the conditions shown in Table 1. Compressor 4 was a diaphragm compressor with a capacity of 20L / min, and compressor 5 was a diaphragm compressor with a capacity of 2L / min. The gas volume was at 0℃ and 1 atm.

[0149] The flow rate of the raw gas introduced into the raw gas storage tank 1 is set to 2 L / min, and the xenon concentration is set to 50, 60, or 70% by volume. Furthermore, the xenon flow rate collected from the easily adsorbed component storage tank 2 is set to 0.2 L / min, and the nitrogen or argon flow rate collected from the difficult-to-adsorb component storage tank 3 is set to 1.8 L / min.

[0150] [Table 1]

[0151] When operating continuously for 24 hours under the above operating conditions, the nitrogen or argon concentration derived from path L7 and the xenon concentration derived from path L13 remain relatively stable and constant, achieving a roughly cyclical constant state. At this time, the concentrations of easily adsorbed components (Xe) in the easily adsorbed component storage tank, the concentrations of easily adsorbed components (Xe) in the difficult-to-adsorb component storage tank, and the recovery rates of easily adsorbed components (Xe) are shown in Table 2.

[0152] [Table 2]

[0153] When using the pressure swing adsorption gas separation device of the present invention, nitrogen or argon, which are difficult-to-adsorb components, will not be discharged into the easily adsorbed component storage tank 2, and xenon, which is an easily adsorbed component, can be separated with high purity (greater than or equal to 99% by volume). Furthermore, the recovery rate of xenon, which is an easily adsorbed component, is also high.

[0154] [Comparative Example 1] Using the pressure swing adsorption gas separation device shown in Figure 10, that is, the pressure swing adsorption gas separation device described in Patent Document 1 (Japanese Patent Application Publication No. 2006-061831), an experiment was conducted to separate xenon using a mixed gas containing xenon (easily adsorbed component) and nitrogen (difficult to adsorb component) as the raw gas.

[0155] Figure 10 shows a schematic configuration of a pressure swing adsorption gas separation device 101, which includes: a raw material gas storage tank 1 for storing a mixture of gas containing the target component and at least one other component as raw material gas; an easily adsorbed component storage tank 2 for storing easily adsorbed components; a difficult-to-adsorb component storage tank 3 for storing difficult-to-adsorb components; a compressor 4 for compressing the gas in the raw material gas storage tank or the easily adsorbed component storage tank 2; a compressor 5 for compressing the gas in the easily adsorbed component storage tank 2; and four adsorption cylinders: a lower cylinder 10B, a lower cylinder 11B, an upper cylinder 10U, and an upper cylinder 11U. Path L1 is a gas flow path that introduces the raw material gas into the raw material gas storage tank 1. Path L2 is a gas flow path that discharges the gas from the raw material gas storage tank 1 to the compressor 4. Path L3 is a gas flow path that discharges the gas from the easily adsorbed component storage tank 2 to the compressor 4. Paths L4 and L5 are gas flow paths that introduce the gas from the compressor 4 into the lower cylinder 10B and lower cylinder 11B, respectively. Path L6 is a gas flow path that introduces the gas from the upper cylinder 10U and upper cylinder 11U into the difficult-to-adsorb component storage tank 3, or discharges the gas from the difficult-to-adsorb component storage tank 3 into the upper cylinder 10U and upper cylinder 11U. Path L7 is a gas flow path that supplies the difficult-to-adsorb component from the difficult-to-adsorb component storage tank 3 to the outside of the device system. Path L8 is a gas flow path that introduces the difficult-to-adsorb component from the difficult-to-adsorb component storage tank 3 as a countercurrent flushing gas into the upper cylinder 10U and upper cylinder 11U. Paths L9 and L10 are gas flow paths that return gas from lower cylinders 10B and 11B to the raw material gas storage tank 1 or the easily adsorbed component storage tank 2, respectively. Path L11 is a gas flow path that returns gas from lower cylinders 10B and 11B to the raw material gas storage tank 1. Path L12 is a gas flow path that returns gas from lower cylinders 10B and 11B to the easily adsorbed component storage tank 2. Path L13 is a gas flow path that supplies easily adsorbed components from the easily adsorbed component storage tank 2 to the outside of the device system. Path L14 is a pressure equalization line that equalizes the pressure between upper cylinders 10U and 11U.

[0156] The pressure swing adsorption gas separator 101 shown in Figure 10 can continuously separate xenon, which is an easily adsorbed component, from nitrogen, which is a difficult-to-adsorb component, by repeatedly performing the seven steps described below in the lower cylinder 10B and upper cylinder 10U, and the lower cylinder 11B and upper cylinder 11U in sequence.

[0157] (1) Step a: Adsorption step The compressor 4 compresses the mixed gas from the raw material gas storage tank 1 and supplies it to the lower cylinder 10B via paths L2 and L4. Since the lower cylinder 10B and the upper cylinder 10U are connected by opening the on / off valve V5, the pressure in the lower cylinder 10B and the upper cylinder 10U rises at approximately the same rate. Furthermore, the mixed gas in the raw material gas storage tank 1 is a mixture of the raw material gas introduced from path L1 and the gas discharged from the lower cylinder 10B or the lower cylinder 11B during the upper cylinder depressurization step and the flushing and regeneration step described later. The mixed gas system supplied to the lower cylinder 10B preferentially adsorbs xenon as it moves upwards from the lower cylinder 10B, concentrating nitrogen in the gas phase. The concentrated nitrogen is introduced from the lower cylinder 10B into the upper cylinder 10U, where trace amounts of xenon contained in the nitrogen are further adsorbed. After the pressure in the upper cylinder 10U becomes higher than the pressure in the difficult-to-adsorb component storage tank 3, the nitrogen system further concentrated in the upper cylinder 10U is discharged to the difficult-to-adsorb component storage tank 3 via path L6. The nitrogen system in the difficult-to-adsorb component storage tank 3 is discharged from the system via path L7 at a flow rate corresponding to the nitrogen contained in the feed gas, and the remaining gas is used as countercurrent flushing gas in the flushing and regeneration step.

[0158] (2) Step b: Rinsing step By closing the on / off valve V1 and opening the on / off valve V2, the gas to be introduced into the lower cylinder 10B is changed to xenon from the readily adsorbable component storage tank 2. By introducing xenon from the readily adsorbable component storage tank 2 into the lower cylinder 10B, nitrogen co-adsorbed in the adsorbent packing layer of the lower cylinder 10B and nitrogen present in the adsorbent voids are pushed to the upper cylinder 10U, thereby saturating the lower cylinder 10B with xenon. During this period, nitrogen is continuously discharged from the upper cylinder 10U to the difficult-to-adsorb component storage tank 3. Similar to the adsorption step described above, a portion of the nitrogen in the difficult-to-adsorb component storage tank 3 is discharged out of the device system, and the remaining gas is used as backflow purging gas.

[0159] (3) Lower cylinder decompression step (step c) The on / off valves V6 and V10 are closed, while the on / off valves V11 and V13 are opened. This allows the xenon system adsorbed in the lower cylinder 11B during the adsorption and rinsing steps described above to be recovered to the easily adsorbed component storage tank 2 via paths L10 and L12 due to the differential pressure between the lower cylinder 11B and the easily adsorbed component storage tank 2. The xenon recovered to the easily adsorbed component storage tank 2 is pressurized by the compressor 5 and collected as a product via path L13. The remaining xenon is used as a co-current flushing gas in the rinsing step described above. During this period, the upper cylinder 11U is stopped by closing the on / off valves V6 and V15.

[0160] (4) Upper cylinder decompression step (step d) Close the on / off valve V11 and open the on / off valves V6 and V10. This creates a pressure difference between the upper cylinder 11U (which has already stopped the pressure reduction step in the lower cylinder) and the lower cylinder 11B (which has undergone pressure reduction), causing the gas in the upper cylinder 11U to flow into the lower cylinder 11B. The gas introduced into the lower cylinder 11B flushes the lower cylinder 11B and is simultaneously returned to the raw material gas storage tank 1 via paths L10 and L11. The gas system returned to the raw material gas storage tank 1 is then mixed with the raw material gas introduced from path L1 and supplied back to the lower cylinder during the adsorption step described above.

[0161] (5) Rinsing and regeneration step (step e) Open the on / off valve V8. The nitrogen system stored in the difficult-to-adsorb component storage tank 3 is introduced into the upper cylinder 11U as a countercurrent flushing gas via path L8. As the nitrogen system introduced into the upper cylinder 11U moves towards the lower part of the adsorption cylinder, it causes the adsorbed xenon to be displaced and desorbed. The gas system containing a relatively large amount of desorbed xenon is recovered to the raw material gas storage tank 1 via the lower cylinder 11B and path L11. Similar to the upper cylinder depressurization step described above, the gas system recovered to the raw material gas storage tank 1 is mixed with the raw material gas introduced from path L1 and supplied to the lower cylinder again during the adsorption step described above. Here, the nitrogen used for the countercurrent flushing gas can also be nitrogen that has been discharged from the upper cylinder 10U in the adsorption step or rinsing step described above, which is directly introduced into the upper cylinder 11U where the above-described flushing and regeneration step is being performed without passing through the difficult-to-adsorb component storage tank 3.

[0162] (6) Pressure equalization and decompression steps Close the on / off valve V14 and open the on / off valve V9. Gas in the upper cylinder 10U is introduced into the upper cylinder 11U via path L14 due to the pressure difference between the upper cylinder 10U and the upper cylinder 11U (pressure equalization and depressurization operation). This reduces the pressure in the upper cylinder 10U, causing gas in the lower cylinder 10B to be discharged into the upper cylinder 10U. Through this operation, a small amount of nitrogen remaining in the upper part of the adsorption chamber in the lower cylinder 10B is pushed and flowed into the upper cylinder 10U by the xenon desorbed due to the depressurization. During this period, the supply of xenon from the easily adsorbed component storage tank 2 continues.

[0163] (7) Pressure equalization and pressurization steps Close the on / off valves V13 and V8, and open the on / off valve V9. This allows the gas in the upper cylinder 10U to be introduced into the upper cylinder 11U (pressure equalization and pressurization operation). Because the nitrogen concentration of the gas introduced into the upper cylinder 11U is higher, it can push the xenon in the upper cylinder 11U down into the lower part of the upper cylinder and the lower cylinder 11B.

[0164] During the three steps of adsorption, rinsing, and pressure equalization / reduction in the lower cylinder 10B and upper cylinder 10U, the lower cylinder 11B and upper cylinder 11U undergo four steps: lower cylinder pressure reduction, upper cylinder pressure reduction, rinsing / regeneration, and pressure equalization / reduction.

[0165] Cylindrical containers made of stainless steel (80A, inner diameter 83.1mm, filling height 500mm) filled with 1.5kg of activated carbon were used as lower cylinders 10B and 11B, and upper cylinders 10U and 11U. The apparatus operated at a cycle time of 500 seconds, and the time and valve opening / closing control for each step were performed under the conditions shown in Table 3. Compressor 4 was a diaphragm compressor with a capacity of 20L / min, and compressor 5 was a diaphragm compressor with a capacity of 2L / min. The gas volume was at 0℃ and 1 atmosphere.

[0166] The flow rate of the raw gas introduced into the raw gas storage tank 1 is set to 2 L / min, and the xenon concentration is set to 50, 60, or 70% by volume. Furthermore, the xenon flow rate collected from the easily adsorbed component storage tank 2 is set to 0.2 L / min, and the nitrogen or argon flow rate collected from the difficult-to-adsorb component storage tank 3 is set to 1.8 L / min.

[0167] [Table 3]

[0168] When operating continuously for 24 hours under the above operating conditions, the nitrogen or argon concentration derived from path L7 and the xenon concentration derived from path L13 remain relatively stable and constant, reaching a roughly cyclical constant state. At this time, the concentration of easily adsorbed component (Xe) in the easily adsorbed component storage tank, the concentration of easily adsorbed component (Xe) in the difficult-to-adsorb component storage tank, and the recovery rate of easily adsorbed component (Xe) are shown in Table 4.

[0169] [Table 4]

[0170] When using the pressure swing adsorption gas separation device described in Patent Document 1 (Japanese Patent Application Publication No. 2006-061831), nitrogen, which is a difficult-to-adsorb component, will be discharged into the easily adsorbed component storage tank 2, and the easily adsorbed component cannot be separated with high purity (greater than or equal to a concentration of 99% by volume).

[0171] [Example 2] Using the PSA device 50 shown in Figure 6, the opening and closing valves are controlled as shown in Table 5 below to separate and recover the product gas from the raw material gas. The configuration of the PSA device 50 is as follows. • Lower cylinder (10B, 11B), upper cylinder (10U, 11U): 80A stainless steel (inner diameter 83.1mm), adsorbent filling height 500mm • Adsorbent: Activated carbon (manufactured by Osaka Gas Chemicals Co., Ltd., Japan), 1.5 kg each. • Compressor 4: Diaphragm compressor (manufactured by KNF Corporation, discharge capacity: 20L / min) • Compressor 5: Diaphragm compressor (manufactured by KNF Corporation, discharge capacity: 0.2L / min) (All of the following are based on 0°C and atmospheric pressure) • Raw material gas: Xenon (Xe) + Nitrogen • The rate of feed gas introduced from path L201 to feed gas storage tank 1: 2.0 L / min • Easily adsorbed component: Xenon • Drainage rate from the easily adsorbed component storage tank 2 to path L213: 0.2 L / min • Difficult-to-adsorb components: nitrogen • Drainage rate from the difficult-to-adsorb component storage tank 3 to path L207: 1.8 L / min

[0172] [Table 5]

[0173] The diaphragm-type two-way valves (metal diaphragm on / off valves manufactured by Fujikin Incorporated; FPR-ND-71-9.52) were used as on / off valves V210, V211, V212, and V213 and operated under the conditions described in Table 5 above. The results are shown in Table 6 below. Furthermore, the total volume of the piping along path L211 between the on / off valve V212 and the branch point P, plus the volume within the on / off valve V212, is 19 mL. This total volume represents 0.10% of the volume of gas drawn by compressor 4 per minute. Furthermore, the total volume of the piping volume of path L212 between on / off valve V213 and branch point Q plus the volume inside on / off valve V213, the total volume of the piping volume of path L209 between on / off valve V210 and branch point R plus the volume inside on / off valve V210, and the total volume of the piping volume of path L210 between on / off valve V211 and branch point S plus the volume inside on / off valve V211 are all 19 mL.

[0174] [Table 6]

[0175] As shown in Table 6, it can be seen that the pressure swing adsorption gas separation device according to the present invention can separate easily adsorbed components with high purity. In particular, when the concentration of easily adsorbed components in the raw material gas storage tank is greater than or equal to 60%, the easily adsorbed component (xenon) can be separated with a high purity of greater than or equal to 99% by volume.

[0176] <Comparative Example 2> A separation experiment was performed using a conventional device (the device described in Patent Document 1 above) in the same manner as in Example 2, as a comparative example of the present invention. In addition, the total volume of the piping in each path plus the volume in the opening and closing valves is 53 mL, which is 0.27% of the volume of gas drawn by compressor 4 in one minute. The results are shown in Table 7 below.

[0177] [Table 7]

[0178] As shown in Table 7, in the prior art devices, the total volume of the piping volume in each path plus the volume in the opening and closing valves is 53 mL, so the concentration of the easily adsorbed component (xenon) does not reach 99% by volume.

[0179] [Example 3] The diaphragm-type three-way diverter valve (metal diaphragm on / off valve manufactured by Fujikin Corporation; FPR-NDTB-71-9.52) was used as on / off valves V210, V211, V212, and V213 and operated under the conditions described in Table 5 above. The results are shown in Table 8 below. Furthermore, the total volume of the piping along path L211 between the on / off valve V212 and the branch point P, plus the volume within the on / off valve V212, is 5 mL. This total volume represents 0.03% of the volume of gas drawn by compressor 4 per minute. Furthermore, the total volume of the pipes along path L212 between the on-off valve V213 and the branch point Q, plus the volume inside the on-off valve V213; the total volume of the pipes along path L209 between the on-off valve V210 and the branch point R, plus the volume inside the on-off valve V210; and the total volume of the pipes along path L210 between the on-off valve V211 and the branch point S, plus the volume inside the on-off valve V211, is 5 mL.

[0180] [Table 8]

[0181] As shown in Table 8, it can be seen that according to the present invention, by setting the total volume of each piping section with residual gas components to 5 mL, it is possible to further separate easily adsorbed components with high purity. In particular, when the concentration of easily adsorbed components in the raw material gas storage tank is greater than or equal to 60%, it is possible to separate the easily adsorbed component (xenon) with a high purity of greater than or equal to 99.95% by volume.

[0182] [Example 4] Three-way ball valves (Swagelok, SS-63XLTS8-A30S4) were used as on / off valves V210, V211, V212, and V213, and were operated under the conditions described in Table 5 above. The results are shown in Table 9 below. In addition, the total volume of the piping volume of path L211 between the on / off valve V212 and the branch point P, plus the volume inside the on / off valve V212, is 5 mL. Furthermore, the total volume of the pipes along path L212 between the on-off valve V213 and the branch point Q, plus the volume inside the on-off valve V213; the total volume of the pipes along path L209 between the on-off valve V210 and the branch point R, plus the volume inside the on-off valve V210; and the total volume of the pipes along path L210 between the on-off valve V211 and the branch point S, plus the volume inside the on-off valve V211, is 5 mL.

[0183] [Table 9]

[0184] As shown in Table 9, it can be seen that according to the present invention, even when using a three-way ball valve as the on / off valve, it is possible to separate the easily adsorbed component with the same high purity as in Example 3 by setting the total volume of each piping section with residual gas components to 5 mL. That is, when the concentration of the easily adsorbed component in the raw material gas storage tank is greater than or equal to 60%, the easily adsorbed component (xenon) can be separated with a high purity of greater than or equal to 99.95% by volume.

[0185] [Example 5] Except that argon was used as the feed gas to replace nitrogen with a component that is difficult to adsorb, the operation was carried out under the same conditions as in Example 3. The results are shown in Table 10 below.

[0186] [Table 10]

[0187] As shown in Table 10, it can be seen that according to the present invention, even when using argon as the difficult-to-adsorb component, the easily adsorbed component can be separated with the same high purity as in Example 3 by setting the total volume of each piping section with residual gas components to 5 mL. That is, when the concentration of the easily adsorbed component in the raw material gas storage tank is greater than or equal to 60%, the easily adsorbed component (xenon) can be separated with a high purity of greater than or equal to 99.95% by volume.

[0188] [Comparative Example 3] Except that argon was used as the feed gas to replace nitrogen with a component that is difficult to adsorb, the operation was carried out under the same conditions as in Example 2. The results are shown in Table 11 below.

[0189] [Table 11]

[0190] As shown in Table 11, even when argon is used as the raw material gas to replace nitrogen with the difficult-to-adsorb components it contains, in conventional devices, the total volume of the piping in each path plus the volume in the opening and closing valves is 53 mL, so the concentration of the easily adsorbed component (xenon) does not reach 99% by volume.

[0191] [Example 6] Using the PSA device 70 shown in Figure 8, the opening and closing valves are controlled as shown in Table 12 below to separate and recover the product gas from the raw material gas. The configuration of the PSA device 70 is as follows. • Lower cylinder (10B, 11B), upper cylinder (10U, 11U): 80A stainless steel (inner diameter 83.1mm), adsorbent filling height 500mm • Adsorbent: Activated carbon, 1.5 kg each • Compressor 4: Diaphragm compressor (discharge rate: 20L / min) • Compressor 5: Diaphragm compressor (discharge rate: 2L / min) (All of the following are based on 0°C and atmospheric pressure) • Raw material gas: Xenon (Xe) + Nitrogen • The rate of feed gas introduced from path L301 to feed gas storage tank 1: 2.0 L / min Easily adsorbed component: Xenon • Drainage rate from the easily adsorbed component storage tank 2 to path L313: 0.2 L / min • Difficult-to-adsorb components: nitrogen • Drainage rate from the difficult-to-adsorb component storage tank 3 to path L307: 1.8 L / min

[0192] [Table 12]

[0193] By changing the distance from the on / off valve V301 located on path L302 to the branch point T, xenon was separated and recovered. Operation was performed by changing the piping volume. The results are shown in Table 13.

[0194] [Table 13]

[0195] As shown in Table 13, based on test examples 1 to 3, since the volume of path L302 from the on / off valve V301 to the branch point T is less than or equal to 200 mL, and is less than or equal to 1% of the volume of gas drawn by compressor 4 in one minute, the concentration of product Xe is greater than or equal to 99% by volume. Furthermore, in Experimental Example 1, since the volume of path L302 from the on / off valve V301 to the branch point T is 10 mL, and is less than or equal to 0.05 percent of the volume of gas drawn by compressor 4 in one minute, the concentration of product Xe is greater than or equal to 99.9% by volume. In contrast, in test example 4, since the volume of path L302 from the on / off valve V301 to the branch point T is 500 mL, which exceeds 1% (2.5%) of the volume of gas drawn by compressor 4 in one minute, the Xe concentration of the product did not reach 99.9% by volume (94.5% by volume).

[0196] [Example 7] In Test Example 1 of the above-mentioned verification test 1, when a diaphragm three-way diverter valve (metal diaphragm on / off valve manufactured by Fujikin Co., Ltd.; FPR-NDTB-71-9.52) was further used as the on / off valve V301, the total volume of the piping from the on / off valve V301 installed in the path L302 to the branch point T was 5 mL. The results of the operation under the conditions in Table 12 showed that the purity of Xe in the product was 99.95% and the Xe recovery rate was 99%. [Industrial Utilization]

[0197] The pressure swing adsorption (PSA) gas separation device of the present invention can be effectively utilized as a device for supplying semiconductor or display device manufacturing equipment, efficiently recovering high-value-added gases such as xenon from the discharged mixed gas after use with high concentration and high recovery rate, and recycling them. Therefore, by combining the PSA gas separation device of the present invention with the manufacturing equipment for semiconductor or display devices to form a cycle, the cost of expensive environmental gases used in semiconductor manufacturing equipment and the like can be significantly reduced.

[0198] 1: Raw material gas storage tank 2: Storage tank for easily adsorbed components 3: Storage tank for difficult-to-adsorb components 4a, 4b: Compressor 10B, 11B: Lower tube 10U, 11U: Upper cylinder L1 to L9, L9', L10, L10', L11, L11', L12, L12', L13 to L17: Path (flow path) V1 to V10, V10', V11, V11', V12, V12', V13', V14, V15: On / off valves (on / off devices) 50, 60, 70: Pressure Swing Adsorption (PSA) gas separator 100, 101: Pressure Swing Adsorption (PSA) Gas Separator V201 to V215: On / off valves (on / off devices) L201 to L207: Path (Flow) P,Q,R,S,T: Bidding Points V301 to V315: On / off valves (on / off devices) L301 to L315: Path (Flow)

Claims

1. A pressure swing adsorption (PSA) gas separation device, which uses a PSA gas separation method to separate main components from a raw material gas, wherein the raw material gas is a mixed gas containing at least two main components, the PSA gas separation device comprising: at least one adsorption cylinder filled with an adsorbent, the adsorbent having both easy adsorption and difficult adsorption properties for at least one main component of the raw material gas; a raw material gas storage tank for storing the raw material gas; an easily adsorbable component storage tank for storing easily adsorbable components desorbed from the adsorbent in the adsorption cylinder; at least one compressor for drawing and compressing at least one of the gas in the raw material gas storage tank and the gas in the easily adsorbable component storage tank, for introducing at least one of the raw material gas and the gas in the easily adsorbable component storage tank into one of the adsorption cylinders; a gas flow path for returning gas discharged from the adsorption cylinder to the easily adsorbable component storage tank; and a gas flow path for returning gas discharged from the adsorption cylinder to the raw material gas storage tank; and, The gas flow path that sends the gas discharged from the aforementioned adsorption cylinder back to the aforementioned easily adsorbed component storage tank is a first dedicated flow path, which is connected at one end to the aforementioned adsorption cylinder and at the other end only to the aforementioned easily adsorbed component storage tank.

2. The pressure swing adsorption gas separator as described in claim 1, wherein, One end of the aforementioned first dedicated flow path is connected to the aforementioned adsorption cylinder via a gas flow path that introduces gas from the aforementioned compressor into the aforementioned adsorption cylinder.

3. The pressure swing adsorption gas separation device as described in claim 1 or 2 further comprises a second dedicated flow path, one end of which is connected to the aforementioned adsorption cylinder, and the other end is connected only to the aforementioned raw material gas storage tank.

4. The pressure swing adsorption gas separator as described in claim 3, wherein, One end of the aforementioned second dedicated flow path is connected to the aforementioned adsorption cylinder via a gas flow path that introduces gas from the aforementioned compressor into the aforementioned adsorption cylinder.

5. The pressure swing adsorption gas separation device as claimed in claim 1, comprising: a first flow path located between the compressor and the adsorption cylinder; a second flow path branching from the first flow path at a first branch point and located between the first branch point and the storage tank for easily adsorbed components; and a first opening and closing device located in the second flow path; and the first opening and closing device being located near the first branch point.

6. The pressure swing adsorption gas separator as described in claim 5, wherein, The aforementioned first divergence point is located near the aforementioned adsorption cylinder.

7. The pressure swing adsorption gas separation apparatus as described in claim 5 or 6 further comprises: a third flow path branching from the aforementioned first flow path at a second branch point and located between the aforementioned second branch point and the aforementioned raw material gas storage tank; and a second opening and closing device located in the aforementioned third flow path; and the aforementioned second opening and closing device is located near the aforementioned second branch point.

8. The pressure swing adsorption gas separator as described in claim 7, wherein, The aforementioned second divergence point is located near the aforementioned adsorption cylinder.

9. The pressure swing adsorption gas separation device as claimed in claim 1, comprising: a flow path that branches into a first flow path, a second flow path, and a third flow path at a branching point, the first flow path being connected to the aforementioned adsorption cylinder, the second flow path being connected to the aforementioned raw material gas storage tank, and the third flow path being connected to the aforementioned easily adsorbed component storage tank; a compressor located in the aforementioned flow path; and a first opening and closing device located in the aforementioned second flow path; and the aforementioned first opening and closing device being located near the aforementioned branching point.

10. The pressure swing adsorption gas separator as described in claim 9, wherein, The volume of the second flow path from the inside of the first opening and closing device to the aforementioned branch point is less than or equal to 1% of the volume of gas drawn by the aforementioned compressor in one minute.

11. The pressure swing adsorption gas separation device as described in claim 9 or 10 further comprises a second opening and closing device located in the aforementioned third flow path; and the aforementioned second opening and closing device is located near the aforementioned branch point.

12. The pressure swing adsorption gas separator as described in claim 9 or 10, wherein, The aforementioned compressor is located near the aforementioned branch point in the aforementioned first flow path.

13. The pressure swing adsorption gas separator as described in claim 11, wherein, The aforementioned compressor is located near the aforementioned branch point in the aforementioned first flow path.

14. The pressure swing adsorption gas separation device as described in claim 11 has a first compressor and a second compressor as the aforementioned compressor, the first compressor being located on the primary side of the aforementioned first opening and closing device in the aforementioned second flow path, and the second compressor being located on the primary side of the aforementioned second opening and closing device in the aforementioned third flow path.

15. The pressure swing adsorption gas separator as described in any one of claims 1, 2, 5, 6, 9, and 10, wherein, The aforementioned raw material gas contains: at least one easily adsorbed component selected from the group consisting of xenon and krypton; and at least one difficult-to-adsorb component selected from the group consisting of oxygen, nitrogen, argon, helium, neon and hydrogen.

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