Gas recovery system and gas recovery method

Abstract

To provide a gas recovery system and a gas recovery method suitable for improving a recovery rate of a specific gas such as carbon dioxide.SOLUTION: The gas recovery system 100 of the present invention includes the first collection unit 11 having the first adsorbent 111 that adsorbs the gas A contained in the mixture gas Gm containing the gas A and the gas B different from the gas A, the second collection unit 12 having the second adsorbent 121 that adsorbs the gas A contained in the mixture gas Gm, and the first recycle path 51 that guides the first non-adsorbed gas G1 discharged from the first collection unit 11 by supplying the mixture gas Gm from the first collection unit 11 to the second collection unit 12. And a second recycle passage 52 for guiding the second non-adsorption gas G2 discharged from the second collection part 12 by supplying the mixture gas Gm from the second collection part 12 toward the first collection part 11.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a gas recovery system and a gas recovery method. [Background technology]

[0002] In recent years, in light of environmental regulations and the like, attention has been focused on technology for recovering a specific gas, such as carbon dioxide, contained in a mixed gas by concentrating it using a separation membrane or the like. The concentrated gas containing a high concentration of the specific gas is, for example, pressurized and filled into a container containing an adsorbent, and transported to a desired location. For example, Patent Document 1 discloses a gas storage container that is easy to transport and install. Patent Document 1 also describes that the inside of the gas storage container may be filled with a porous material for adsorbing the specific gas.

[0003] Concentrated gas obtained by increasing the concentration of a specific gas contained in a mixed gas also contains gases other than the specific gas. When such concentrated gas is pressurized and filled into a storage container such as that described in Patent Document 1, the increase in the partial pressure of the specific gas inside the container is limited, thereby suppressing an increase in the amount of the specific gas adsorbed by the adsorbent. Therefore, various methods have been proposed for circulating concentrated gas through a container containing an adsorbent in order to increase the amount of the specific gas adsorbed by the adsorbent. For example, Patent Document 2 describes adsorbing carbon dioxide to the adsorbent by circulating a carbon dioxide-containing gas through an adsorption tower containing the adsorbent. In Patent Document 2, the non-adsorbed gas (adsorption off-gas) after carbon dioxide separation is released into the atmosphere. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2019 / 026872 [Patent Document 2] Japanese Patent Publication No. 2022-188322 Summary of the Invention [Problem to be solved by the invention]

[0005] Although the concentration is lower than that of concentrated gas, the non-adsorbed gas still contains the specific gas to be recovered. Therefore, if the non-adsorbed gas is discarded after separating the specific gas, the recovery rate of the specific gas that is ultimately obtained will decrease.

[0006] Therefore, an object of the present invention is to provide a gas recovery system and a gas recovery method suitable for improving the recovery rate of a specific gas such as carbon dioxide. [Means for solving the problem]

[0007] According to one aspect, the present invention provides: a first recovery section having a first adsorbent that adsorbs the gas A contained in a mixed gas that includes a gas A and a gas B different from the gas A; a second recovery section having a second adsorbent that adsorbs the gas A contained in the mixed gas; a first recycle path that guides a first non-adsorbed gas discharged from the first recovery section as a result of the mixed gas being supplied from the first recovery section toward the second recovery section; a second recycle path that guides a second non-adsorbed gas discharged from the second recovery section as a result of the mixed gas being supplied from the second recovery section toward the first recovery section; a gas recovery system comprising: to provide.

[0008] From another aspect, the present invention provides a first recovery section having a first adsorbent that adsorbs the gas A contained in a mixed gas that includes a gas A and a gas B different from the gas A; a second recovery section having a second adsorbent that adsorbs the gas A contained in the mixed gas; a first recycle path that guides a first non-adsorbed gas discharged from the first recovery section by supplying the mixed gas from the first recovery section toward the second recovery section; a first supply path that guides the mixed gas to the first recovery section; a second supply path that guides the mixed gas to the second recovery section; a gas recovery system comprising: to provide.

[0009] From yet another aspect, the present invention provides supplying the mixed gas to a first recovery section having a first adsorbent that adsorbs the gas A contained in the mixed gas, the first adsorbent being configured to adsorb the gas A contained in the mixed gas, and introducing a first non-adsorbed gas discharged from the first recovery section into a first recycle path; supplying the mixed gas to a second recovery section having a second adsorbent that adsorbs the gas A contained in the mixed gas, and introducing a second non-adsorbed gas discharged from the second recovery section into a second recycle path; Including, the first recycle path is a path that guides the first non-adsorbed gas from the first recovery section toward the second recovery section, the second recycle path is a path that guides the second non-adsorbed gas from the second recovery section toward the first recovery section; to provide. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a gas recovery system and a gas recovery method that are suitable for improving the recovery rate of a specific gas such as carbon dioxide. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic configuration diagram showing an example of a gas recovery system according to an embodiment of the present invention. [Figure 2] 2 is a flow diagram showing an example of a gas recovery method using the gas recovery system of FIG. 1. [Figure 3A] 2 is a diagram showing the state of the gas recovery system of FIG. 1 during execution of a first adsorption step and a first discharge step. FIG. [Figure 3B] 2 is a diagram showing the state of the gas recovery system of FIG. 1 during execution of a first adsorption step and a second pre-adsorption step. FIG. [Figure 3C] 2 is a diagram showing the state of the gas recovery system of FIG. 1 during execution of a second adsorption step and a second discharge step. FIG. [Figure 3D] 2 is a diagram showing the state of the gas recovery system of FIG. 1 during execution of a second adsorption step and a first pre-adsorption step. FIG. [Figure 4] FIG. 10 is a schematic configuration diagram showing an example of a gas recovery system according to a modified example. [Figure 5] 5 is a flow diagram showing an example of a gas recovery method using the gas recovery system of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0012] The gas recovery system according to the first aspect of the present invention comprises: a first recovery section having a first adsorbent that adsorbs the gas A contained in a mixed gas that includes a gas A and a gas B different from the gas A; a second recovery section having a second adsorbent that adsorbs the gas A contained in the mixed gas; a first recycle path that guides a first non-adsorbed gas discharged from the first recovery section as a result of the mixed gas being supplied from the first recovery section toward the second recovery section; a second recycle path that guides a second non-adsorbed gas discharged from the second recovery section as a result of the mixed gas being supplied from the second recovery section toward the first recovery section; Equipped with.

[0013] In a second aspect of the present invention, for example, the gas recovery system according to the first aspect further includes a first supply path that guides the mixed gas to the first recovery section, and a second supply path that guides the mixed gas to the second recovery section.

[0014] In a third aspect of the present invention, for example, the gas recovery system according to the first or second aspect further comprises a first concentration sensor that measures the content of gas A contained in the first non-adsorbed gas, and a first supply adjustment unit that adjusts the introduction of the first non-adsorbed gas into the first recycle path, and when the content of gas A contained in the first non-adsorbed gas is equal to or greater than a first threshold value, the first non-adsorbed gas is introduced into the first recycle path.

[0015] In a fourth aspect of the present invention, for example, the gas recovery system according to any one of the first to third aspects further comprises a second concentration sensor that measures the content of gas A contained in the second non-adsorbed gas, and a second supply adjustment unit that adjusts the introduction of the second non-adsorbed gas into the second recycle path, and when the content of gas A contained in the second non-adsorbed gas is equal to or greater than a second threshold value, the second non-adsorbed gas is introduced into the second recycle path.

[0016] In a fifth aspect of the present invention, for example, the gas recovery system according to the third or fourth aspect further includes a first exhaust path that leads the first non-adsorbed gas to the outside of the gas recovery system, and when the content of gas A contained in the first non-adsorbed gas is smaller than the first threshold value, the first non-adsorbed gas is introduced into the first exhaust path.

[0017] In a sixth aspect of the present invention, for example, the gas recovery system according to the fourth or fifth aspect further includes a second exhaust path that leads the second non-adsorbed gas to the outside of the gas recovery system, and when the content of gas A in the second non-adsorbed gas is smaller than the second threshold value, the second non-adsorbed gas is introduced into the second exhaust path.

[0018] In a seventh aspect of the present invention, for example, the gas recovery system according to any one of the second to sixth aspects further includes a third supply adjustment unit that adjusts the introduction of the mixed gas into the second supply path, and when it is determined that adsorption by the first adsorbent has been completed, the mixed gas is introduced into the second supply path.

[0019] In an eighth aspect of the present invention, for example, the gas recovery system according to any one of the second to seventh aspects further includes a fourth supply adjustment unit that adjusts the introduction of the mixed gas into the first supply path, and when it is determined that adsorption by the second adsorbent has been completed, the mixed gas is introduced into the first supply path.

[0020] In a ninth aspect of the present invention, for example, the gas recovery system according to any one of the first to eighth aspects further comprises at least one third recovery section having a third adsorbent that adsorbs the gas A contained in the mixed gas, and the at least one third recovery section is provided in at least one path selected from the group consisting of the first recycle path and the second recycle path.

[0021] In a tenth aspect of the present invention, for example, the gas recovery system according to the ninth aspect further includes a third supply path that guides the mixed gas to the at least one third recovery section.

[0022] In an eleventh aspect of the present invention, for example, in the gas recovery system according to any one of the first to tenth aspects, the mixed gas contains carbon dioxide as the gas A and nitrogen as the gas B.

[0023] A gas recovery system according to a twelfth aspect of the present invention comprises: a first recovery section having a first adsorbent that adsorbs the gas A contained in a mixed gas that includes a gas A and a gas B different from the gas A; a second recovery section having a second adsorbent that adsorbs the gas A contained in the mixed gas; a first recycle path that guides a first non-adsorbed gas discharged from the first recovery section by supplying the mixed gas from the first recovery section toward the second recovery section; a first supply path that guides the mixed gas to the first recovery section; a second supply path that guides the mixed gas to the second recovery section; Equipped with.

[0024] A gas recovery method according to a thirteenth aspect of the present invention comprises: supplying the mixed gas to a first recovery section having a first adsorbent that adsorbs the gas A contained in the mixed gas, the first adsorbent being configured to adsorb the gas A contained in the mixed gas, and introducing a first non-adsorbed gas discharged from the first recovery section into a first recycle path; supplying the mixed gas to a second recovery section having a second adsorbent that adsorbs the gas A contained in the mixed gas, and introducing a second non-adsorbed gas discharged from the second recovery section into a second recycle path; Including, the first recycle path is a path that guides the first non-adsorbed gas from the first recovery section toward the second recovery section, The second recycle path is a path that guides the second non-adsorbed gas from the second recovery section toward the first recovery section.

[0025] In a fourteenth aspect of the present invention, for example, in the gas recovery method according to the thirteenth aspect, the step of introducing the first non-adsorbed gas into the first recycle path is performed when the content of gas A contained in the first non-adsorbed gas is equal to or greater than a first threshold value, and the step of introducing the second non-adsorbed gas into the second recycle path is performed when the content of gas A contained in the second non-adsorbed gas is equal to or greater than a second threshold value.

[0026] In a fifteenth aspect of the present invention, for example, a gas recovery method according to the thirteenth or fourteenth aspect includes the steps of introducing the mixed gas into a first supply path and introducing the mixed gas into a second supply path, wherein the first supply path is a path that guides the mixed gas to the first recovery section and the second supply path is a path that guides the mixed gas to the second recovery section, the steps of introducing the mixed gas into the first supply path and introducing the first non-adsorbed gas into the first recycle path are carried out in parallel, and the steps of introducing the mixed gas into the second supply path and introducing the second non-adsorbed gas into the second recycle path are carried out in parallel.

[0027] The present invention will be described in detail below, but the following description is not intended to limit the present invention to a specific embodiment.

[0028] <Gas recovery system> FIG. 1 is a schematic diagram of a gas recovery system 100 according to one embodiment of the present invention. The gas recovery system 100 includes a first recovery section 11, a second recovery section 12, and a first recycle path 51. The first recovery section 11 includes a first adsorbent 111 that adsorbs gas A contained in a mixed gas Gm that includes gas A and a gas B different from gas A. The second recovery section 12 includes a second adsorbent 121 that adsorbs gas A contained in the mixed gas Gm. The first recycle path 51 is a path that guides a first non-adsorbed gas G1, which is discharged from the first recovery section 11 when the mixed gas Gm is supplied to the first recovery section 11, from the first recovery section 11 to the second recovery section 12. In the example of FIG. 1, the first recycle path 51 is a path that guides the first non-adsorbed gas G1 directly to the second recovery section 12.

[0029] In the present embodiment, the gas recovery system 100 further includes a second recycle path 52. The second recycle path 52 is a path that guides the second non-adsorbed gas G2, which is discharged from the second recovery section 12 as a result of the mixed gas Gm being supplied to the second recovery section 12, from the second recovery section 12 toward the first recovery section 11. In the example of FIG. 1 , the second recycle path 52 is a path that guides the second non-adsorbed gas G2 directly to the first recovery section 11.

[0030] In a modified example described later, the gas recovery system according to this embodiment further includes at least one third recovery section provided in at least one path selected from the group consisting of the first recycle path 51 and the second recycle path 52. For example, if at least one third recovery section is provided in the first recycle path 51, the first non-adsorbed gas G1 is guided to at least one third recovery section through the first recycle path 51, but is not guided to the second recovery section 12. For example, if at least one third recovery section is provided in the second recycle path 52, the second non-adsorbed gas G2 is guided to at least one third recovery section through the second recycle path 52, but is not guided to the first recovery section 11. For convenience, in this specification, even in the above-described embodiment, the path that guides the non-adsorbed gas from the first recovery section 11 to the second recovery section 12 will be referred to as the first recycle path 51, and the path that guides the non-adsorbed gas from the second recovery section 12 to the first recovery section 11 will be referred to as the second recycle path 52.

[0031] Hereinafter, the mode in which the mixed gas Gm is brought into contact with the first adsorbent 111 of the first recovery section 11 to cause the gas A contained in the mixed gas Gm to be adsorbed by the first adsorbent 111 will be referred to as the "first adsorption mode." The mode in which the first non-adsorbed gas G1 discharged from the first recovery section 11 is brought into contact with the second adsorbent 121 of the second recovery section 12 to cause the gas A contained in the first non-adsorbed gas G1 to be adsorbed by the second adsorbent 121 will be referred to as the "second pre-adsorption mode." The first adsorption mode and the second pre-adsorption mode can be performed in parallel. The mode in which the mixed gas Gm is brought into contact with the second adsorbent 121 of the second recovery section 12 to cause the gas A contained in the mixed gas Gm to be adsorbed by the second adsorbent 121 will be referred to as the "second adsorption mode." The mode in which the second non-adsorbed gas G2 discharged from the second recovery section 12 is brought into contact with the first adsorbent 111 of the first recovery section 11 to adsorb the gas A contained in the second non-adsorbed gas G2 to the first adsorbent 111 is called the "first pre-adsorption mode." The second adsorption mode and the first pre-adsorption mode can be performed in parallel.

[0032] When the first adsorption mode is performed in the first recovery unit 11, a first non-adsorbed gas G1 is discharged from the first recovery unit 11. Although the first non-adsorbed gas G1 contains gas A at a lower concentration than the mixed gas Gm, the first non-adsorbed gas G1 contains gas A. According to the gas recovery system 100, when the first adsorption mode is performed, the first non-adsorbed gas G1 can be supplied to the second recovery unit 12 via the first recycle path 51. This allows gas A contained in the first non-adsorbed gas G1 to be adsorbed by the second adsorbent 121 of the second recovery unit 12. In other words, the second pre-adsorption mode can be performed. In this way, according to the gas recovery system 100, the first non-adsorbed gas G1 can be reused without being discarded, thereby improving the recovery rate of the gas A finally obtained.

[0033] When the second adsorption mode is performed in the second recovery unit 12, a second non-adsorbed gas G2 is discharged from the second recovery unit 12. Like the first non-adsorbed gas G1, the second non-adsorbed gas G2 contains gas A. According to the gas recovery system 100, when the second adsorption mode is performed, the second non-adsorbed gas G2 can be supplied to the first recovery unit 11 via the second recycle path 52. This allows the first adsorbent 111 in the first recovery unit 11 to adsorb gas A contained in the second non-adsorbed gas G2. In other words, the first pre-adsorption mode can be performed. In this way, according to the gas recovery system 100, the second non-adsorbed gas G2 can be reused without being discarded, thereby improving the recovery rate of the gas A finally obtained.

[0034] In the example of Fig. 1, the first collection section 11 and the second collection section 12 are connected in series by a first recycle path 51. The second collection section 12 and the first collection section 11 are connected in series by a second recycle path 52. The first collection section 11 and the second collection section 12 are connected in series and in a circular manner by the first recycle path 51 and the second recycle path 52.

[0035] The first recycle path 51 can be considered as a path that guides the first non-adsorbed gas G1 to a collection section (e.g., second collection section 12) downstream of the first collection section 11. The second recycle path 52 can be considered as a path that guides the second non-adsorbed gas G2 to a collection section (e.g., first collection section 11) downstream of the second collection section 12.

[0036] A control valve 21b may be provided in the first recycle path 51. With this configuration, the control valve 21b can control the supply of the first non-adsorbed gas G1 to the second recovery section 12. A control valve 21a may be provided in the second recycle path 52. With this configuration, the control valve 21a can control the supply of the second non-adsorbed gas G2 to the first recovery section 11. The control valves 21b and 21a are typically on-off valves. However, the control valves 21b and 21a may also be flow rate adjustment valves having an intermediate opening.

[0037] The content of gas A in the mixed gas Gm is, for example, in the range of 1 to 95 vol%. The lower limit of the content of gas A in the mixed gas Gm may be 10 vol% or more, 20 vol% or more, 30 vol% or more, or even 40 vol% or more. The content of gas A in the mixed gas Gm may be higher than the content of gas B. The first non-adsorbed gas G1 and the second non-adsorbed gas G2 have a lower content of gas A than the mixed gas Gm. The content of gas A in the first non-adsorbed gas G1 and the second non-adsorbed gas G2 is, for example, in the range of 1 to 95 vol%. In this specification, the content (vol%) of gas A in a given gas is the volume ratio of gas A to the given gas under standard conditions (0°C, 101.33 kPa).

[0038] Hereinafter, a mode in which a first adsorption gas containing gas A is desorbed from the first adsorbent 111 of the first recovery section 11 that has adsorbed gas A will be referred to as a "first desorption mode." When the first desorption mode is performed after the first adsorption mode, the content of gas A in the first adsorption gas will be higher than the content of gas A in the mixed gas Gm. A mode in which a second adsorption gas containing gas A is desorbed from the second adsorbent 121 of the second recovery section 12 that has adsorbed gas A will be referred to as a "second desorption mode." When the second desorption mode is performed after the second adsorption mode, the content of gas A in the second adsorption gas will be higher than the content of gas A in the mixed gas Gm.

[0039] The gas recovery system 100 further includes a first supply path 41. The first supply path 41 is a path that guides the mixed gas Gm from an external mixed gas supply source (not shown) to the first recovery unit 11. With this configuration, when the first adsorption mode is performed, the mixed gas Gm can be supplied to the first recovery unit 11 through the first supply path 41. The gas recovery system 100 further includes a second supply path 42. The second supply path 42 is a path that guides the mixed gas Gm from an external mixed gas supply source (not shown) to the second recovery unit 12. With this configuration, when the second adsorption mode is performed, the mixed gas Gm can be supplied to the second recovery unit 12 through the second supply path 42.

[0040] In the example of FIG. 1, the gas recovery system 100 includes one supply path 40 through which the mixed gas Gm is guided, and the supply path 40 branches into a first supply path 41 and a second supply path 42 at a branch position 81. The upstream side of the supply path 40 may be connected to an external mixed gas supply source. As shown in FIG. 1, one supply path 40 may branch into the first supply path 41 and the second supply path 42 at the branch position 81. In this case, the first recovery section 11 and the second recovery section 12 are connected in parallel by the first supply path 41 and the second supply path 42. However, each of the first supply path 41 and the second supply path 42 may be connected to an external mixed gas supply source.

[0041] Examples of external mixed gas sources include gas separation devices and DAC (direct air capture technology) devices.

[0042] A control valve 22a may be provided in the first supply path 41. With this configuration, the control valve 22a can control the supply of the mixed gas Gm to the first recovery section 11. A control valve 22b may be provided in the second supply path 42. With this configuration, the control valve 22b can control the supply of the mixed gas Gm to the second recovery section 12. In the example of FIG. 1, by opening the control valve 22a and closing the control valve 22b, the mixed gas Gm can be supplied only to the first recovery section 11. By opening the control valve 22b and closing the control valve 22a, the mixed gas Gm can be supplied only to the second recovery section 12. However, instead of the control valves 22a and 22b, a switching valve (not shown) may be provided at the branch position 81. The control valves 22a and 22b are typically on-off valves. However, the control valves 22a and 22b may be flow rate adjustment valves having an intermediate opening.

[0043] The gas recovery system 100 may further include a booster 31 provided in the supply path 40. With this configuration, the mixed gas Gm can be pressurized and supplied to the first recovery section 11 or the second recovery section 12 using the booster 31, so that the gas A can be efficiently adsorbed by the first adsorbent 111 or the second adsorbent 121.

[0044] The booster 31 is not particularly limited as long as it can pressurize the mixed gas Gm. The booster 31 is typically a compressor. However, instead of the booster 31, the gas recovery system 100 may include a booster (not shown) provided in the first supply path 41 and a booster (not shown) provided in the second supply path 42.

[0045] Hereinafter, the mode in which the first non-adsorbed gas G1 discharged from the first recovery unit 11 is discharged to the outside of the gas recovery system 100 will be referred to as the "first discharge mode." The mode in which the second non-adsorbed gas G2 discharged from the second recovery unit 12 is discharged to the outside of the gas recovery system 100 will be referred to as the "second discharge mode."

[0046] The gas recovery system 100 may further include a first exhaust path 61. The first exhaust path 61 is a path that guides the first non-adsorbed gas G1 to the outside of the gas recovery system 100. The first exhaust path 61 is typically open to the atmosphere. With this configuration, when the first adsorption mode is performed, the first non-adsorbed gas G1 can be exhausted to the outside of the gas recovery system 100 through the first exhaust path 61 as needed (first exhaust mode).

[0047] The gas recovery system 100 may further include a second exhaust path 62. The second exhaust path 62 is a path that guides the second non-adsorbed gas G2 to the outside of the gas recovery system 100. The second exhaust path 62 is typically open to the atmosphere. With this configuration, when the second adsorption mode is performed, the second non-adsorbed gas G2 can be exhausted to the outside of the gas recovery system 100 through the second exhaust path 62 as needed (second exhaust mode).

[0048] 1, the first discharge path 61 and the second discharge path 62 merge into one discharge path 60 at a merging position 91. As shown in FIG. 1, the first discharge path 61 and the second discharge path 62 may merge into one discharge path 60 at the merging position 91. In this case, the first recovery unit 11 and the second recovery unit 12 are connected in parallel by the first discharge path 61 and the second discharge path 62. However, each of the first discharge path 61 and the second discharge path 62 may be open to the atmosphere, for example.

[0049] A control valve 23a may be provided in the first discharge path 61. With this configuration, the discharge of the first non-adsorbed gas G1 to the outside can be controlled by the control valve 23a. A control valve 23b may be provided in the second discharge path 62. With this configuration, the discharge of the second non-adsorbed gas G2 to the outside can be controlled by the control valve 23b. In the example of FIG. 1, by opening the control valve 23a and closing the control valve 23b, only the first non-adsorbed gas G1 can be discharged to the outside. By opening the control valve 23b and closing the control valve 23a, only the second non-adsorbed gas G2 can be discharged to the outside. However, instead of the control valves 23a and 23b, a switching valve (not shown) may be provided at the confluence position 91. The control valves 23a and 23b are typically on-off valves. However, the control valves 23a and 23b may be flow rate adjustment valves having an intermediate opening.

[0050] The gas recovery system 100 may further include a back pressure valve 32 provided in the discharge path 60. With this configuration, the pressure inside the first recovery section 11 or the pressure inside the second recovery section 12 can be maintained constant using the back pressure valve 32. However, instead of the back pressure valve 32, the gas recovery system 100 may include a back pressure valve (not shown) provided in the first discharge path 61 and a back pressure valve (not shown) provided in the second discharge path 62.

[0051] In the example of FIG. 1, the first recycling path 51 branches off from the first discharge path 61 at a branching position 82. As shown in FIG. 1, the first recycling path 51 may branch off from the first discharge path 61 at the branching position 82. In this case, the first discharge path 61 has a first portion 611 that connects the first collection section 11 and the branching position 82, and a second portion 612 that is downstream of the branching position 82. The second portion 612 may be a portion that connects the branching position 82 and the merging position 91. However, the upstream end of the first recycling path 51 may be directly connected to the first collection section 11.

[0052] A control valve 24a may be provided in the first portion 611 of the first discharge path 61. With this configuration, the control valve 24a can control the discharge of the first non-adsorbed gas G1 from the first recovery section 11. However, instead of the control valve 24a, a switching valve (not shown) may be provided at the branch position 82. The control valve 24a is typically an on-off valve. However, the control valve 24a may also be a flow rate adjustment valve having an intermediate opening.

[0053] In the example of FIG. 1, the first recycling path 51 merges with the second supply path 42 at a merging position 92. As shown in FIG. 1, the first recycling path 51 may merge with the second supply path 42 at the merging position 92. In this case, the second supply path 42 has a first portion 421 connecting the merging position 92 and the second collection section 12, and a second portion 422 upstream of the merging position 92. The second portion 422 may be a portion connecting the branching position 81 and the merging position 92. However, the downstream end of the first recycling path 51 may be directly connected to the second collection section 12.

[0054] A control valve 24b may be provided in the first portion 421 of the second supply path 42. With this configuration, the control valve 24b can control the supply of the first non-adsorbed gas G1 or the supply of the mixed gas Gm to the second recovery section 12. However, instead of the control valve 24b, a switching valve (not shown) may be provided at the confluence position 92. The control valve 24b is typically an on-off valve. However, the control valve 24b may also be a flow rate adjustment valve having an intermediate opening.

[0055] In the example of FIG. 1, the second recycle path 52 branches off from the second discharge path 62 at a branching position 83. As shown in FIG. 1, the second recycle path 52 may branch off from the second discharge path 62 at the branching position 83. In this case, the second discharge path 62 has a first portion 621 that connects the second collection section 12 and the branching position 83, and a second portion 622 that is downstream of the branching position 84. The second portion 622 may be a portion that connects the branching position 83 and the merging position 91. However, the upstream end of the second recycle path 52 may be directly connected to the second collection section 12.

[0056] A control valve 25a may be provided in the first portion 621 of the second discharge path 62. With this configuration, the control valve 25a can control the discharge of the second non-adsorbed gas G2 from the second recovery section 12. However, instead of the control valve 25a, a switching valve (not shown) may be provided at the branch position 83. The control valve 25a is typically an on-off valve. However, the control valve 25a may also be a flow rate adjustment valve having an intermediate opening.

[0057] In the example of FIG. 1, the second recycling path 52 merges with the first supply path 41 at a merging position 93. As shown in FIG. 1, the second recycling path 52 may merge with the first supply path 41 at the merging position 93. In this case, the first supply path 41 has a first portion 411 connecting the merging position 93 and the first collection section 11, and a second portion 412 upstream of the merging position 93. The second portion 412 may be a portion connecting the branching position 81 and the merging position 93. However, the downstream end of the second recycling path 52 may be directly connected to the first collection section 11.

[0058] A control valve 25b may be provided in the first portion 411 of the first supply path 41. With this configuration, the control valve 25b can control the supply of the second non-adsorbed gas G2 or the supply of the mixed gas Gm to the first recovery section 11. However, instead of the control valve 25b, a switching valve (not shown) may be provided at the confluence position 93. The control valve 25b is typically an on-off valve. However, the control valve 25b may also be a flow rate adjustment valve having an intermediate opening.

[0059] Unless otherwise specified, each of the gas paths of the gas recovery system 100 is formed of, for example, a pipe made of metal or resin.

[0060] The gas recovery system 100 may further include a first concentration sensor (not shown) and a first supply adjustment unit. The first concentration sensor measures the content of gas A in the first non-adsorbed gas G1. The first supply adjustment unit adjusts the introduction of the first non-adsorbed gas G1 into the first recycle path 51. In the example of FIG. 1, the first supply adjustment unit adjusts the supply of the first non-adsorbed gas G1 to the second recovery unit 12 and includes at least control valves 24a, 21b, and 24b.

[0061] When the content of gas A in the first non-adsorbed gas G1 measured by the first concentration sensor is equal to or greater than a first threshold, the first supply adjustment unit may adjust the first non-adsorbed gas G1 to be introduced into the first recycle path 51. In the example of FIG. 1 , when the content of gas A in the first non-adsorbed gas G1 is equal to or greater than the first threshold, the first supply adjustment unit adjusts the first non-adsorbed gas G1 to be supplied to the second recovery unit 12 through the first recycle path 51. With this configuration, for example, only the first non-adsorbed gas G1 having a relatively high content of gas A can be selectively supplied to the second recovery unit 12. As a result, the recovery rate of gas A can be further improved.

[0062] When the content of gas A in the first non-adsorbed gas G1 measured by the first concentration sensor is lower than a first threshold, the first supply adjustment unit may adjust the first non-adsorbed gas G1 to be introduced into the first discharge path 61. In the example of FIG. 1 , when the content of gas A in the first non-adsorbed gas G1 is lower than the first threshold, the first supply adjustment unit adjusts the first non-adsorbed gas G1 to be discharged to the outside of the gas recovery system 100 through the first discharge path 61. With this configuration, for example, only the first non-adsorbed gas G1 having a relatively low content of gas A can be selectively discharged to the outside.

[0063] The gas recovery system 100 may further include a second concentration sensor (not shown) and a second supply adjustment unit. The second concentration sensor measures the content of gas A in the second non-adsorbed gas G2. The second supply adjustment unit adjusts the introduction of the second non-adsorbed gas G2 into the second recycle path 52. In the example of FIG. 1, the second supply adjustment unit adjusts the supply of the second non-adsorbed gas G2 to the first recovery unit 11 and includes at least control valves 25a, 21a, and 25b.

[0064] When the content of gas A in the second non-adsorbed gas G2 measured by the second concentration sensor is equal to or greater than a second threshold, the second supply adjustment unit may adjust the second non-adsorbed gas G2 to be introduced into the second recycle path 52. In the example of FIG. 1 , when the content of gas A in the second non-adsorbed gas G2 is equal to or greater than the second threshold, the second supply adjustment unit adjusts the second non-adsorbed gas G2 to be supplied to the first recovery unit 11 through the second recycle path 52. With this configuration, for example, only the second non-adsorbed gas G2 having a relatively high content of gas A can be selectively supplied to the first recovery unit 11. As a result, the recovery rate of gas A can be further improved.

[0065] When the content of gas A in the second non-adsorbed gas G2 measured by the second concentration sensor is lower than a second threshold, the second supply adjustment unit may adjust the second non-adsorbed gas G2 to be introduced into the second discharge path 62. In the example of FIG. 1 , when the content of gas A in the second non-adsorbed gas G2 is lower than the second threshold, the second supply adjustment unit adjusts the second non-adsorbed gas G2 to be discharged to the outside of the gas recovery system 100 through the second discharge path 62. With this configuration, for example, only the second non-adsorbed gas G2 having a relatively low content of gas A can be selectively discharged to the outside.

[0066] The first threshold is preferably set to a range equal to or less than the content of gas A in the mixed gas Gm. The content of gas A in the mixed gas Gm may be set as the first threshold. For example, when the content of gas A in the mixed gas Gm is 10 vol%, the first threshold may be 10 vol%. The second threshold is preferably set to a range equal to or less than the content of gas A in the mixed gas Gm. The content of gas A in the mixed gas Gm may be set as the second threshold. For example, when the content of gas A in the mixed gas Gm is 10 vol%, the second threshold may be 10 vol%. The first threshold and the second threshold may be the same or different.

[0067] The first concentration sensor may be provided in the first discharge path 61. When the first recycle path 51 branches off from the first discharge path 61 at a branch position 83 as shown in FIG. 1 , the first concentration sensor may be provided in the first portion 611 or the second portion 612.

[0068] The second concentration sensor may be provided in the second discharge path 62. When the second recycle path 52 branches off from the second discharge path 62 at a branch position 84 as shown in FIG. 1 , the second concentration sensor may be provided in the first portion 621 or the second portion 622.

[0069] The first concentration sensor and the second concentration sensor may be a single common concentration sensor. In the example shown in FIG. 1, a single common concentration sensor 33 is provided in the discharge path 60. As shown in FIG. 1, a single common concentration sensor 33 may be provided in the discharge path 60. For example, when the control valves 24a and 23a are opened and the control valves 25a and 23b are closed in the first adsorption mode, only the first non-adsorbed gas G1 flows through the discharge path 60. When the control valves 25a and 23b are opened and the control valves 24a and 23a are closed in the second adsorption mode, only the second non-adsorbed gas G2 flows through the discharge path 60. Therefore, by controlling the opening and closing of the control valves, the single common concentration sensor 33 can measure the content of gas A in the first non-adsorbed gas G1 and the content of gas A in the second non-adsorbed gas G2.

[0070] 1, the concentration sensor 33 is disposed downstream of the back pressure valve 32 in the discharge path 60. However, the concentration sensor 33 may also be disposed upstream of the back pressure valve 32 in the discharge path 60.

[0071] The gas recovery system 100 may further include a third supply adjustment unit. The third supply adjustment unit adjusts the introduction of the mixed gas Gm into the second supply path 42. In the example of Fig. 1, the third supply adjustment unit adjusts the supply of the mixed gas Gm to the second recovery unit 12 and includes at least control valves 22b, 21b, and 24b.

[0072] When it is determined that the adsorption of the first adsorbent 111 is complete, the third supply adjustment unit may adjust the mixed gas Gm to be introduced into the second supply path 42. In the example of FIG. 1 , when it is determined that the adsorption of the first adsorbent 111 is complete, the third supply adjustment unit adjusts the mixed gas Gm to be supplied to the second recovery unit 12 through the second supply path 42. With this configuration, the completion time of the first adsorption mode can be managed, so that, for example, the second adsorption mode can be performed consecutively after the first adsorption mode. As a result, the gas A can be recovered efficiently.

[0073] The gas recovery system 100 may further include a first sensor 35. The first sensor 35 detects the adsorption state of the gas A in the first adsorbent 111 of the first recovery section 11. When it is determined that the adsorption of the first adsorbent 111 is complete based on the detection value of the first sensor 35, the third supply adjustment section may adjust the mixed gas Gm to be introduced into the second supply path 42.

[0074] The gas recovery system 100 may further include a fourth supply adjustment unit. The fourth supply adjustment unit adjusts the introduction of the mixed gas Gm into the first supply path 41. In the example of Fig. 1, the fourth supply adjustment unit adjusts the supply of the mixed gas Gm to the first recovery unit 11 and includes at least control valves 22a, 21a, and 25b.

[0075] When it is determined that the adsorption of the second adsorbent 121 is complete, the fourth supply adjustment unit may adjust the mixed gas Gm to be introduced into the first supply path 41. In the example of FIG. 1 , when it is determined that the adsorption of the second adsorbent 121 is complete, the fourth supply adjustment unit adjusts the mixed gas Gm to be supplied to the first recovery unit 11 through the first supply path 41. With this configuration, the completion time of the second adsorption mode can be managed, so that, for example, the first adsorption mode can be performed consecutively after the second adsorption mode. As a result, the gas A can be recovered efficiently.

[0076] The gas recovery system 100 may further include a second sensor 36. The second sensor 36 detects the adsorption state of the gas A in the first adsorbent 121 of the second recovery section 12. When it is determined that the adsorption of the second adsorbent 121 is complete based on the detection value of the second sensor 36, the fourth supply adjustment section may adjust the mixed gas Gm to be introduced into the first supply path 41.

[0077] In this embodiment, the point in time when "adsorption by the adsorbent is completed" may be the point at which breakthrough of the adsorbent begins (breakthrough point) or the point at which the adsorbent reaches adsorption saturation (saturation point). If the point in time when "adsorption by the adsorbent is completed" is the saturation point, the adsorption amount of the adsorbent can be increased to the maximum.

[0078] The first sensor 35 is not particularly limited as long as it can detect the adsorption state of gas A in the first adsorbent 111. The second sensor 36 is not particularly limited as long as it can detect the adsorption state of gas A in the second adsorbent 121. For example, the first sensor 35 and the second sensor 36 can be a temperature sensor, an NDIR (non-dispersive infrared) sensor, a TCD (thermal conductivity detection) sensor, a GC-MS (gas chromatograph mass spectrometer), or the like.

[0079] The first sensor 35 may be a temperature sensor that detects the temperature of the first adsorbent 111. The second sensor 36 may be a temperature sensor that detects the temperature of the second adsorbent 121. When the adsorbent (first adsorbent 111, second adsorbent 121) is brought into contact with the mixed gas Gm, the temperature of the adsorbent rises due to the heat of adsorption associated with the adsorption of gas A. Even if breakthrough of the adsorbent begins, adsorption continues, and after adsorption saturation is reached, the temperature of the adsorbent returns to the temperature of the external atmosphere (e.g., room temperature). If the first sensor 35 and the second sensor 36 are temperature sensors, for example, the point at which the temperature of the adsorbent returns to the temperature of the external atmosphere can be regarded as the saturation point, and therefore the point at which "adsorption by the adsorbent is completed" can be regarded as the saturation point. As a result, the adsorption amount of the adsorbent can be maximized.

[0080] The type of temperature sensor is not particularly limited. The temperature sensor may be a contact temperature sensor or a non-contact temperature sensor. Examples of contact temperature sensors include a temperature sensor using a thermistor and a temperature sensor using a thermocouple. Examples of non-contact temperature sensors include an infrared temperature sensor.

[0081] The first sensor 35 and the second sensor 36 may be TCD sensors. When the first sensor 35 and the second sensor 36 are TCD sensors, for example, the breakthrough point can be considered to be "when adsorption by the adsorbent is completed."

[0082] The mixed gas Gm contains an acidic gas. The mixed gas Gm may contain, for example, carbon dioxide, methane, hydrogen, nitrogen, oxygen, helium, argon, propane, or propylene. The mixed gas Gm contains gas A and gas B that is different from gas A. Examples of gas A and gas B include nitrogen and carbon dioxide. For example, the mixed gas Gm may contain carbon dioxide as gas A and nitrogen as gas B. The mixed gas Gm may contain nitrogen as gas A and carbon dioxide as gas B.

[0083] As the mixed gas Gm, for example, a concentrated gas obtained by using a gas separation device equipped with a separation membrane or the like to increase the concentration of carbon dioxide contained in exhaust gas emitted from combustion equipment such as a factory or power plant, or a concentrated gas obtained by using a DAC (direct air capture technology) device to increase the concentration of carbon dioxide contained in the atmosphere can be used.

[0084] Next, the recovery section (first recovery section 11, second recovery section 12) will be described in more detail.

[0085] The first collection unit 11 has a container 112, a gas inlet 11a, and a gas outlet 11b. The container 112 is filled with a first adsorbent 111 capable of adsorbing gas A contained in the mixed gas Gm. In the first adsorption mode, the first exhaust mode, and the second pre-adsorption mode, the mixed gas Gm is supplied to the first collection unit 11 through the gas inlet 11a, and a first non-adsorbed gas G1 is exhausted from the first collection unit 11 through the gas exhaust port 11b. In the first desorption mode, the first adsorbed gas is exhausted from the first collection unit 11 through the gas exhaust port 11b.

[0086] The second collection unit 12 has a container 122, a gas inlet 12a, and a gas outlet 12b. The container 122 is filled with a second adsorbent 121 capable of adsorbing gas A contained in the mixed gas Gm. In the second adsorption mode, the second exhaust mode, and the first pre-adsorption mode, the mixed gas Gm is supplied to the second collection unit 12 through the gas inlet 12a, and a second non-adsorbed gas G2 is exhausted from the second collection unit 12 through the gas outlet 12b. In the second desorption mode, the second adsorbed gas is exhausted from the second collection unit 12 through the gas outlet 12b.

[0087] A first supply path 41 is connected to a gas inlet 11a of the first recovery section 11. A second recycle path 52 may be further connected to the gas inlet 11a. In the example of Fig. 1, the second recycle path 52 merges with the first supply path 41 at a junction position 93, and a first portion 411 of the first supply path 41 is connected to the gas inlet 11a.

[0088] A first discharge path 61 is connected to the gas discharge port 11b of the first recovery unit 11. A first recycle path 51 may be further connected to the gas discharge port 11b. In the example of Fig. 1, the first recycle path 51 branches off from the first discharge path 61 at a branch position 82, and a first portion 611 of the first discharge path 61 is connected to the gas discharge port 11b.

[0089] A second supply path 42 is connected to the gas inlet 12a of the second recovery section 12. A first recycle path 51 may be further connected to the gas inlet 12a. In the example of Fig. 1, the first recycle path 51 merges with the second supply path 42 at a junction position 92, and a first portion 421 of the second supply path 42 is connected to the gas inlet 12a.

[0090] A second discharge path 62 is connected to the gas discharge port 12b of the second recovery unit 12. A second recycle path 52 may be further connected to the gas discharge port 12b. In the example of Fig. 1, the second recycle path 52 branches off from the second discharge path 62 at a branch position 83, and a first portion 621 of the second discharge path 62 is connected to the gas discharge port 12b.

[0091] The container 112 of the first collection unit 11 and the container 122 of the second collection unit 12 may be configured to be detachable and movable from the gas collection system 100. With this configuration, for example, while the second collection unit 12 is performing the second adsorption mode, the container 112 of the first collection unit 11 that has completed the first adsorption mode can be replaced with another container 112. As a result, for the container 112 that has completed the first adsorption mode, the first desorption mode can be performed, for example, outside the gas collection system 100. Therefore, it is not necessary to stop the supply of the mixed gas Gm to perform the first desorption mode, and, for example, the first adsorption mode and the second adsorption mode can be performed consecutively. Similarly, for example, while the first adsorption mode is being performed in the first collection unit 11, the container 122 of the second collection unit 12 that has completed the second adsorption mode can be replaced with another container 122. As a result, for the container 122 that has completed the second adsorption mode, the second desorption mode can be performed, for example, outside the gas collection system 100. Therefore, it is not necessary to stop the supply of the mixed gas Gm in order to perform the second desorption mode, and for example, the second adsorption mode and the first adsorption mode can be performed consecutively, thereby enabling efficient recovery of the gas A.

[0092] According to the gas recovery system 100, there is no need to stop the supply of the mixed gas Gm in order to perform the desorption modes (first desorption mode, second desorption mode). Therefore, there is no need to stop the operation of a mixed gas supply unit (not shown) such as a gas separation device or a DAC (direct air capture technology) device to increase the concentration of the raw material gas, and gas recovery can be performed efficiently.

[0093] If the container 112 and the container 122 are configured to be detachable and movable from the gas recovery system 100, the gas recovery system 100 can also be made compact.

[0094] The container 112 and the container 122 may be used as a storage and transport container for the gas A. A plurality of the containers 112 and the container 122 may be stacked for storage.

[0095] The shapes of the container 112 and the container 122 are not particularly limited. The container 112 and the container 122 may have, for example, a cubic shape, a rectangular parallelepiped shape, a cylindrical shape, or a prismatic shape. The shape of the container 112 and the shape of the container 122 may be the same or different. If the shape of the container 112 and the shape of the container 122 are the same, there is no need to distinguish between the container 112 and the container 122, which improves ease of handling.

[0096] The capacities of container 112 and container 122 are not particularly limited. The capacities of container 112 and container 122 can be set appropriately according to requirements. The capacities of container 112 and container 122 may be the same or different. If the capacities of container 112 and container 122 are the same, there is no need to distinguish between container 112 and container 122, which improves ease of handling.

[0097] The material of the container 112 and the container 122 is not particularly limited. Examples of materials for the container 112 and the container 122 include metal, alloy, plastic, and a combination thereof. The plastic may be fiber reinforced plastic (FRP). The container 112 and the container 122 may be formed from metal or FRP. In this case, the pressure resistance of the container 112 and the container 122 can be improved. Furthermore, the weight of the container 112 and the container 122 can be reduced, improving handleability.

[0098] The first adsorbent 111 and the second adsorbent 121 are not particularly limited as long as they can adsorb gas A. The first adsorbent 111 and the second adsorbent 121 may be made of, for example, a porous material. Examples of porous materials include activated carbon, zeolite, molecular sieve, mesoporous silica, metal-organic frameworks (MOFs), covalent organic frameworks (COFs), metal-organic polyhedra (MOPs), covalent organic polymers (COPs), porous aromatic frameworks (PAFs), hydrogen-bonded organic frameworks (HOFs), and porous organic polymers (POPs). The porous material may contain one or a combination of two or more materials selected from the group consisting of the above materials. The first adsorbent 111 and the second adsorbent 121 may be made of a polymer having an amino group. Such a polymer is, for example, an amine polymer containing structural units derived from an epoxy monomer.

[0099] The configuration of the first adsorbent 111 and the configuration of the second adsorbent 121 may be the same or different. If the first adsorbent 111 and the second adsorbent 121 are the same, it is easy to manage each mode, such as the first adsorption mode and the second adsorption mode.

[0100] The gas recovery system 100 may further include a control device 34 that controls each component of the gas recovery system 100. The control device 34 is, for example, a DSP (Digital Signal Processor) including an A / D conversion circuit, an input / output circuit, an arithmetic circuit, a storage device, etc. The control device 34 stores a program for appropriately operating the gas recovery system 100. For example, the control device 34 controls the first to fourth supply adjustment units to control the timing of implementing each mode, such as the first adsorption mode, the second pre-adsorption mode, the second adsorption mode, and the first pre-adsorption mode.

[0101] The gas recovery system 100 may further include a flow rate controller 38 provided in the discharge path 60. This configuration allows for more precise management of each mode, such as the first adsorption mode, the second pre-adsorption mode, the second adsorption mode, and the first pre-adsorption mode. The flow rate controller 38 is typically a mass flow controller (mass flow meter).

[0102] According to the gas recovery system of this embodiment, each mode can be performed consecutively, and as a result, gas A can be recovered efficiently.

[0103] <Gas recovery method> Next, a gas recovery method using the gas recovery system of this embodiment will be described.

[0104] The gas recovery method of this embodiment includes the steps of introducing a first non-adsorbed gas G1 discharged from a first recovery unit 11 by supplying a mixed gas Gm into a first recycle path 51, and introducing a second non-adsorbed gas G2 discharged from a second recovery unit 12 by supplying the mixed gas Gm into a second recycle path 52. The first recovery unit 11 has a first adsorbent 111 that adsorbs a gas A contained in the mixed gas Gm. The second recovery unit 12 has a second adsorbent 121 that adsorbs a gas A contained in the mixed gas Gm.

[0105] In the gas recovery method using the gas recovery system 100 shown in Fig. 1, the step of introducing the first non-adsorbed gas G1 into the first recycle path 51 is a step of supplying the first non-adsorbed gas G1 to the second recovery section 12 (second pre-adsorption step). The step of introducing the second non-adsorbed gas G2 into the second recycle path 52 is a step of supplying the second non-adsorbed gas G2 to the first recovery section 11 (first pre-adsorption step). The second pre-adsorption step corresponds to the second pre-adsorption mode, and the first pre-adsorption step corresponds to the first pre-adsorption mode.

[0106] Figure 2 is a flow diagram showing an example of a gas recovery method using the gas recovery system 100 shown in Figure 1. The upper part of Figure 2 shows the flow in the first recovery section 11, and the lower part shows the flow in the second recovery section 12.

[0107] According to this gas recovery method, in the second pre-adsorption step, the first non-adsorbed gas G1 discharged from the first recovery section 11 can be supplied to the second recovery section 12. This allows the gas A contained in the first non-adsorbed gas G1 to be adsorbed by the second adsorbent 121 of the second recovery section 12. In this way, according to this gas recovery method, the first non-adsorbed gas G1 can be used without being discarded, thereby improving the recovery rate of the gas A that is finally obtained.

[0108] According to this gas recovery method, in the first pre-adsorption step, the second non-adsorbed gas G2 discharged from the second recovery section 12 can be supplied to the first recovery section 11. This allows the gas A contained in the second non-adsorbed gas G2 to be adsorbed by the first adsorbent 111 of the first recovery section 11. In this way, according to this gas recovery method, the second non-adsorbed gas G2 can be used without being discarded, thereby improving the recovery rate of the gas A that is ultimately obtained.

[0109] The gas recovery method of this embodiment may further include a step of introducing the mixed gas Gm from an external mixed gas supply source (not shown) into the first supply path 41, and a step of introducing the mixed gas Gm from an external mixed gas supply source (not shown) into the second supply path 42.

[0110] In the gas recovery method using the gas recovery system 100 shown in Fig. 1, the step of introducing the mixed gas Gm into the first supply path 41 is a step of supplying the mixed gas Gm to the first recovery section 11 (first adsorption step). The step of introducing the mixed gas Gm into the second supply path 42 is a step of supplying the mixed gas Gm to the second recovery section 12 (second adsorption step). The first adsorption step corresponds to the first adsorption mode, and the second adsorption step corresponds to the second adsorption mode.

[0111] During the first adsorption step, the pressure in the first recovery section 11 is, for example, in the range of more than 0.1 MPa and not more than 3.0 MPa. The upper limit of the pressure in the first recovery section 11 may be 2.5 MPa or less, 2.0 MPa or less, 1.5 MPa or less, or even 1.0 MPa or less. During the second adsorption step, the pressure in the second recovery section 12 is, for example, in the range of more than 0.1 MPa and not more than 3.0 MPa. The upper limit of the pressure in the second recovery section 12 may be 2.5 MPa or less, 2.0 MPa or less, 1.5 MPa or less, or even 1.0 MPa or less. In this specification, unless otherwise specified, "pressure" refers to absolute pressure.

[0112] The pressure in the first recovery section 11 during the first adsorption process and the pressure in the second recovery section 12 during the second adsorption process can be adjusted, for example, by a booster 31 provided in the supply path 40 and a back pressure valve 32 provided in the discharge path 60.

[0113] The gas recovery method of this embodiment may further include the steps of introducing the first non-adsorbed gas G1 into the first discharge path 61 and introducing the second non-adsorbed gas G2 into the second discharge path 62.

[0114] In the gas recovery method using the gas recovery system 100 shown in Fig. 1, the step of introducing the first non-adsorbed gas G1 into the first discharge path 61 is a step (first discharge step) of discharging the first non-adsorbed gas G1 from the first recovery unit 11 to the outside of the gas recovery system 100. The step of introducing the second non-adsorbed gas G2 into the second discharge path 62 is a step (second discharge step) of discharging the second non-adsorbed gas G2 from the second recovery unit 12 to the outside of the gas recovery system 100. The first discharge step corresponds to the first discharge mode, and the second discharge step corresponds to the second discharge mode.

[0115] The step of introducing the first non-adsorbed gas G1 into the first discharge path 61 (first discharge step) may be performed when the content of gas A in the first non-adsorbed gas G1 is lower than a first threshold value. With this configuration, for example, only the first non-adsorbed gas G1 having a relatively low content of gas A can be selectively discharged to the outside.

[0116] The step of introducing the first non-adsorbed gas G1 into the first recycle path 51 (second pre-adsorption step) may be performed when the content of gas A in the first non-adsorbed gas G1 is equal to or higher than a first threshold. With this configuration, for example, only the first non-adsorbed gas G1 having a relatively high content of gas A can be selectively supplied to the second recovery section 12. As a result, the recovery rate of gas A can be further improved.

[0117] The step of introducing the second non-adsorbed gas G2 into the second discharge path 62 (the second discharge step) may be performed when the content of gas A in the second non-adsorbed gas G2 is lower than a second threshold value. With this configuration, for example, only the second non-adsorbed gas G2 having a relatively low content of gas A can be selectively discharged to the outside.

[0118] The step of introducing the second non-adsorbed gas G2 into the second recycle path 52 (first pre-adsorption step) may be performed when the content of gas A in the second non-adsorbed gas G2 is equal to or higher than a second threshold. With this configuration, for example, the second non-adsorbed gas G2 can be selectively supplied to the first recovery unit 11 only when the content of gas A in the second non-adsorbed gas G2 is relatively high. As a result, the recovery rate of gas A can be further improved.

[0119] Whether the content of gas A in the first non-adsorbed gas G1 is equal to or greater than a first threshold value can be determined, for example, based on a measurement value of a first concentration sensor (not shown) that measures the content of gas A in the first non-adsorbed gas G1. Whether the content of gas A in the second non-adsorbed gas G2 is equal to or greater than a second threshold value can be determined, for example, based on a measurement value of a second concentration sensor (not shown) that measures the content of gas A in the second non-adsorbed gas G2.

[0120] As shown in FIG. 2, in the gas recovery method using the gas recovery system 100 shown in FIG. 1, the first adsorption step and the first exhaust step can be performed in parallel. The first adsorption step and the second pre-adsorption step can be performed in parallel. The second pre-adsorption step can be performed after the first exhaust step. The second adsorption step and the second exhaust step can be performed in parallel. The second adsorption step and the first pre-adsorption step can be performed in parallel. The first pre-adsorption step can be performed after the second exhaust step.

[0121] The step of introducing the mixed gas Gm into the second supply path 42 (second adsorption step) may be performed when it is determined that adsorption by the first adsorbent 111 in the first recovery section 11 has been completed. With this configuration, for example, the second adsorption step can be performed consecutively after the first adsorption step. As a result, the gas A can be recovered efficiently.

[0122] The step of introducing the mixed gas Gm into the first supply path 41 (first adsorption step) may be performed when it is determined that adsorption by the second adsorbent 121 in the second recovery section 12 has been completed. With this configuration, for example, the first adsorption step can be performed consecutively after the second adsorption step. As a result, the gas A can be recovered efficiently.

[0123] Whether or not the adsorption of the first adsorbent 111 is complete can be determined based on, for example, the detection value of the first sensor 35 that detects the adsorption state of the gas A in the first adsorbent 111. Whether or not the adsorption of the second adsorbent 121 is complete can be determined based on, for example, the detection value of the second sensor 36 that detects the adsorption state of the gas A in the second adsorbent 121.

[0124] The gas recovery method may further include a step (first desorption step) of discharging a first adsorbed gas containing gas A from first recovery section 11, and a step (second desorption step) of discharging a second adsorbed gas containing gas A from second recovery section 12. The first desorption step corresponds to the first desorption mode, and the second desorption step corresponds to the second desorption mode.

[0125] When the first desorption step and the second desorption step are performed, the pressure in the first collection section 11 and the pressure in the second collection section 12 may be reduced. In other words, in the first desorption step and the second desorption step, the adsorbed gas may be desorbed from the adsorbents (first adsorbent 111, second adsorbent 121) by reducing the pressure in the collection sections (first collection section 11, second collection section 12). When the first desorption step is performed, the pressure in the first collection section 11 is reduced to, for example, 0.1 MPa. However, the pressure in the first collection section 11 may be reduced to a range below atmospheric pressure (0.1 MPa or less). When the second desorption step is performed, the pressure in the second collection section 12 is reduced to 0.1 MPa. However, the pressure in the second collection section 12 may be reduced to a range below atmospheric pressure (0.1 MPa or less).

[0126] The pressure in the first recovery section 11 during the first desorption step and the pressure in the second recovery section 12 during the second desorption step can be adjusted by, for example, a pressure booster 31 provided in the supply path 40.

[0127] Next, each step of the gas recovery method using the gas recovery system 100 shown in Fig. 1 will be described in detail with reference to Fig. 2 and Fig. 3A to Fig. 3D. In Fig. 3A to Fig. 3D, control valves in an open state are shown in white, and control valves in a closed state are shown in black.

[0128] First, the first adsorption step is performed. In the first adsorption step, the control valves 22a and 25b are opened, and the mixed gas Gm is supplied to the first recovery section 11. The control valves 22b, 24b, 25a, 23b, and 21b are closed.

[0129] During the first adsorption step, the first discharge step is performed while the content of gas A in the first non-adsorbed gas G1 discharged from the first recovery unit 11 is smaller than the first threshold value. That is, the first discharge step is performed in parallel with the first adsorption step (see FIG. 3A). In the first discharge step, the control valves 24a and 23a are opened, and the first non-adsorbed gas G1 is discharged to the outside of the gas recovery system 100.

[0130] During the first adsorption step, if the content of gas A in the first non-adsorbed gas G1 becomes equal to or greater than the first threshold, the second pre-adsorption step is executed. That is, the second pre-adsorption step is executed in parallel with the first adsorption step (see FIG. 3B). In the second pre-adsorption step, the control valves 22a, 25b, and 24a are left open, while the control valve 23a is closed, and the control valves 21b and 24b are opened, to supply the first non-adsorbed gas G1 to the second recovery section 12. The control valve 22b remains closed. In the second pre-adsorption step, the control valves 25a and 23b are opened, and the non-adsorbed gas from the second pre-adsorption step is discharged to the outside of the gas recovery system 100.

[0131] During the execution of the first adsorption step and the second pre-adsorption step, if it is determined that adsorption by the first adsorbent 111 in the first recovery section 11 is complete, the first adsorption step and the second pre-adsorption step are terminated, and the second adsorption step is executed. In the second adsorption step, the control valves 22b and 24b are opened, and the mixed gas Gm is supplied to the second recovery section 12. The control valves 22a, 25b, 24a, 23a, and 21a are closed.

[0132] 2, in parallel with the execution of the second adsorption step, the container 112 of the first collection unit 11 in which the first adsorption step has been completed may be replaced with another container 112. The first desorption step may be executed for the container 112 of the first collection unit 11 in which the first adsorption step has been completed.

[0133] During the second adsorption step, the second discharge step is performed while the content of gas A in the second non-adsorbed gas G2 discharged from the second recovery unit 12 is smaller than the second threshold value. That is, the second discharge step is performed in parallel with the second adsorption step (see FIG. 3C). In the second discharge step, the control valves 25a and 23b are opened, and the second non-adsorbed gas G2 is discharged to the outside of the gas recovery system 100.

[0134] During the second adsorption step, if the content of gas A in the second non-adsorbed gas G2 becomes equal to or greater than the second threshold, the first pre-adsorption step is executed. That is, the first pre-adsorption step is executed in parallel with the second adsorption step (see FIG. 3D). In the first pre-adsorption step, the control valves 22b, 24b, and 25a are left open, while the control valve 23b is closed, and the control valves 21a and 25b are opened, to supply the second non-adsorbed gas G2 to the first recovery section 11. The control valve 22a remains closed. In the first pre-adsorption step, the control valves 24a and 23a are opened, and the non-adsorbed gas from the first pre-adsorption step is discharged to the outside of the gas recovery system 100.

[0135] During the execution of the second adsorption step and the first pre-adsorption step, if it is determined that adsorption by the first adsorbent 121 in the second recovery section 12 is completed, the second adsorption step and the first pre-adsorption step are terminated, and the first adsorption step is executed. In the first adsorption step, the control valves 22a and 25b are opened, and the mixed gas Gm is again supplied to the first recovery section 11. The control valves 22b, 24b, 25a, 23b, and 21b are closed.

[0136] 2, in parallel with the execution of the first adsorption step, the container 122 of the second collection unit 12 in which the second adsorption step has been completed may be replaced with another container 122. The second desorption step may be executed for the container 122 of the second collection unit 12 in which the second adsorption step has been completed.

[0137] According to the gas recovery method of this embodiment, each step can be carried out continuously as shown in Fig. 2. As a result, gas A can be recovered efficiently.

[0138] <Modification of gas recovery system> The gas recovery system according to this embodiment is not limited to the configuration of the gas recovery system 100 shown in Fig. 1. Modifications of the gas recovery system according to this embodiment will be described below. In the following, elements common to the gas recovery system 100 shown in Fig. 1 will be designated by the same reference numerals, and descriptions thereof may be omitted.

[0139] The gas recovery system according to the modified example further includes at least one third recovery section having a third adsorbent that adsorbs gas A contained in the mixed gas Gm. The at least one third recovery section is provided in at least one path selected from the group consisting of the first recycle path 51 and the second recycle path 52. The gas recovery system according to the modified example can also improve the recovery rate of the gas A that is ultimately obtained.

[0140] As described above, in the gas recovery system according to the modified example, for example, if at least one third recovery section is provided in the first recycle path 51, the first non-adsorbed gas G1 is guided to at least one third recovery section through the first recycle path 51, but is not guided to the second recovery section 12. For example, if at least one third recovery section is provided in the second recycle path 52, the second non-adsorbed gas G2 is guided to at least one third recovery section through the second recycle path 52, but is not guided to the first recovery section 11. For convenience, in this specification, even in the above-described embodiment, the path that guides the non-adsorbed gas from the first recovery section 11 to the second recovery section 12 will be referred to as the first recycle path 51, and the path that guides the non-adsorbed gas from the second recovery section 12 to the first recovery section 11 will be referred to as the second recycle path 52.

[0141] FIG. 4 is a schematic diagram showing an example of a gas recovery system according to a modified example. The gas recovery system 200 shown in FIG. 4 includes one third recovery section 13 provided in the first recycle path 51 as at least one third recovery section. However, the gas recovery system according to the modified example may include two or more third recovery sections 13 provided in the first recycle path 51. Furthermore, the gas recovery system according to the modified example may include one or more third recovery sections 13 provided in the second recycle path 52 as at least one third recovery section. Furthermore, the gas recovery system according to the modified example may include one or more third recovery sections 13 provided in the first recycle path 51 and one or more third recovery sections 13 provided in the second recycle path 52 as at least one third recovery section.

[0142] In the example of FIG. 4 , the first recycling path 51 has a first portion 511 upstream of the third recovery unit 13 and a second portion 512 downstream of the third recovery unit 13. The first portion 511 connects the first recovery unit 11 and the third recovery unit 13. The second portion 512 connects the third recovery unit 13 and the second recovery unit 12. The first non-adsorbed gas G1 discharged from the first recovery unit 11 flows through the first portion 511. That is, the first portion 511 is a portion that directly guides the first non-adsorbed gas G1 to the third recovery unit 13. The second portion 512 is a portion that directly guides the third non-adsorbed gas G3 to the second recovery unit 12.

[0143] Hereinafter, the mode in which the first non-adsorbed gas G1 discharged from the first recovery unit 11 is brought into contact with the third adsorbent 131 of the third recovery unit 13 to adsorb gas A contained in the first non-adsorbed gas G1 to the third adsorbent 131 will be referred to as the "third pre-adsorption mode." The first adsorption mode and the third pre-adsorption mode can be performed in parallel. The mode in which the mixed gas Gm is brought into contact with the third adsorbent 131 of the third recovery unit 13 to adsorb gas A contained in the mixed gas Gm to the third adsorbent 131 will be referred to as the "third adsorption mode." The mode in which the third non-adsorbed gas G3 discharged from the third recovery unit 13 is brought into contact with the second adsorbent 121 of the second recovery unit 12 to adsorb gas A contained in the third non-adsorbed gas G3 to the second adsorbent 121 will be referred to as the "second pre-adsorption mode." The third adsorption mode and the second pre-adsorption mode can be performed in parallel. The second adsorption mode and the first pre-adsorption mode can be performed in parallel. The first adsorption mode, the second adsorption mode, and the first pre-adsorption mode are as described above for the gas recovery system 100.

[0144] 4, the first collection section 11, the third collection section 13, and the second collection section 12 are connected in series by a first recycling path 51. The second collection section 12 and the first collection section 11 are connected in series by a second recycling path 52. The first collection section 11, the third collection section 13, and the second collection section 12 are connected in series and in a circular manner by the first recycling path 51 and the second recycling path 52.

[0145] A control valve 21c may be provided in the first portion 511 of the first recycle path 51. With this configuration, the control valve 21c can control the supply of the first non-adsorbed gas G1 to the third recovery section 13. A control valve 21d may be provided in the second portion 512 of the first recycle path 51. With this configuration, the control valve 21d can control the supply of the third non-adsorbed gas G3 to the second recovery section 12. The control valves 21c and 21d are typically on-off valves. However, the control valves 21c and 21d may also be flow rate adjustment valves with an intermediate opening.

[0146] Hereinafter, the mode in which the third adsorption gas containing gas A is desorbed from the third adsorbent 131 of the third recovery section 13 that has adsorbed gas A will be referred to as the "third desorption mode." When the third desorption mode is performed after the third adsorption mode is performed, the content of gas A in the third adsorption gas is higher than the content of gas A in the mixed gas Gm. The first desorption mode and the second desorption mode are as described above for the gas recovery system 100.

[0147] The gas recovery system 200 further includes a third supply path 43. The third supply path 43 is a path that guides the mixed gas Gm from an external mixed gas supply source (not shown) to the third recovery unit 13. With this configuration, when the third adsorption mode is performed, the mixed gas Gm can be supplied to the third recovery unit 13 through the third supply path 43.

[0148] 4, one supply path 40 may branch into a first supply path 41, a third supply path 43, and a second supply path 42 at branch positions 81 and 84. In this case, the first recovery section 11, the third recovery section 13, and the second recovery section 12 are connected in parallel by the first supply path 41, the third supply path 43, and the second supply path 42. However, each of the first supply path 41, the third supply path 43, and the second supply path 42 may be connected to an external mixed gas supply source.

[0149] Although detailed description will be omitted, as shown in FIG. 4, the third supply path 43 may be provided with a control valve, similar to the first supply path 41 and the second supply path .

[0150] Hereinafter, the mode in which the third non-adsorbed gas G3 discharged from the third recovery section 13 is discharged to the outside of the gas recovery system 100 will be referred to as the "third discharge mode." Note that the first discharge mode and the second discharge mode are as described above for the gas recovery system 100.

[0151] The gas recovery system 200 may further include a third exhaust path 63. The third exhaust path 63 is a path that guides the third non-adsorbed gas G3 to the outside of the gas recovery system 200. The third exhaust path 63 is typically open to the atmosphere. With this configuration, when the third adsorption mode is performed, the third non-adsorbed gas G3 can be exhausted to the outside of the gas recovery system 200 through the third exhaust path 63 as necessary (third exhaust mode).

[0152] 4, the first discharge path 61, the third discharge path 63, and the second discharge path 62 may merge into one discharge path 60 at a merging position 94 and a merging position 91. In this case, the first collection section 11, the third collection section 13, and the second collection section 12 are connected in parallel by the first discharge path 61, the third discharge path, and the second discharge path 62. However, each of the first discharge path 61, the third discharge path 63, and the second discharge path 62 may be open to the atmosphere, for example.

[0153] Although detailed description will be omitted, as shown in FIG. 4, the third discharge path 63 may be provided with a control valve, similar to the first discharge path 61 and the second discharge path 62.

[0154] 4, the first portion 511 of the first recycling path 51 branches off from the first discharge path 61 at a branching position 82 and merges with the third supply path 43 at a merging position 95. However, the upstream end of the first portion 511 may be directly connected to the first recovery section 11. The downstream end of the first portion 511 may be directly connected to the third recovery section 13.

[0155] 4, the second portion 512 of the first recycling path 51 branches off from the third discharge path 63 at a branching position 85 and merges with the second supply path 42 at a merging position 92. However, the upstream end of the second portion 512 may be directly connected to the third recovery section 13. The downstream end of the second portion 512 may be directly connected to the second recovery section 12.

[0156] In the gas recovery system 200, the first supply adjustment unit adjusts the introduction of the first non-adsorbed gas G1 into the first portion 511 of the first recycle path 51. In the example of FIG. 4, the first supply adjustment unit adjusts the supply of the first non-adsorbed gas G1 to the third recovery unit 13 and includes at least control valves 24a and 21c.

[0157] In the example of Figure 4, when the content of gas A in the first non-adsorbed gas G1 is equal to or greater than a first threshold value, the first supply adjustment unit adjusts the first non-adsorbed gas G1 to be supplied to the third recovery unit 13 through the first portion 511 of the first recycle path 51.

[0158] The gas recovery system 200 may further include a third concentration sensor (not shown) and a fifth supply adjustment unit. The third concentration sensor measures the content of gas A in the third non-adsorbed gas G3. The fifth supply adjustment unit adjusts the introduction of the third non-adsorbed gas G3 into the second portion 512 of the first recycle path 51. In the example of FIG. 4, the fifth supply adjustment unit adjusts the supply of the third non-adsorbed gas G3 to the second recovery unit 12 and includes at least control valves 21d and 24b.

[0159] When the content of gas A in the third non-adsorbed gas G3 measured by the third concentration sensor is equal to or greater than a third threshold, the fifth supply adjustment unit may adjust the third non-adsorbed gas G3 to be introduced into the second portion 512 of the first recycle path 51. In the example of FIG. 4 , when the content of gas A in the third non-adsorbed gas G3 is equal to or greater than the third threshold, the fifth supply adjustment unit adjusts the third non-adsorbed gas G3 to be supplied to the second recovery unit 12 through the second portion 512.

[0160] When the content of gas A in the third non-adsorbed gas G3 measured by the third concentration sensor is smaller than a third threshold, the fifth supply adjustment unit may adjust the third non-adsorbed gas G3 to be introduced into the third discharge path 63. In the example of Fig. 4, when the content of gas A in the third non-adsorbed gas G3 is smaller than the third threshold, the fifth supply adjustment unit adjusts the third non-adsorbed gas G3 to be discharged to the outside of the gas recovery system 200 through the third discharge path 63.

[0161] The third threshold is preferably set to a range equal to or less than the content of gas A in the mixed gas Gm. The content of gas A in the mixed gas Gm may be set as the third threshold. For example, when the content of gas A in the mixed gas Gm is 10 vol%, the third threshold may be 10 vol%. The first threshold, second threshold, and third threshold may be the same or different.

[0162] The third concentration sensor may be provided in the third discharge path 63.

[0163] The first concentration sensor, the second concentration sensor, and the third concentration sensor may be a single common concentration sensor 33 provided in the discharge path 60.

[0164] The gas recovery system 200 may further include a sixth supply adjustment unit. The sixth supply adjustment unit adjusts the introduction of the mixed gas Gm into the third supply path 43. In the example of FIG. 4, the sixth supply adjustment unit adjusts the supply of the mixed gas Gm to the third recovery unit 13, and includes at least a control valve provided in the third supply path 43.

[0165] When it is determined that the adsorption by the third adsorbent 131 is completed, the sixth supply adjustment unit may adjust the mixed gas Gm to be introduced into the third supply path 43. In the example of Fig. 4, when it is determined that the adsorption by the third adsorbent 131 is completed, the sixth supply adjustment unit adjusts the mixed gas Gm to be supplied to the third recovery unit 13 through the third supply path 43.

[0166] The gas recovery system 200 may further include a third sensor 37. The third sensor 37 detects the adsorption state of the gas A in the third adsorbent 131 of the third recovery section 13. When it is determined that the adsorption of the third adsorbent 131 is completed based on the detection value of the third sensor 37, the sixth supply adjustment section may adjust the mixed gas Gm to be introduced into the third supply path 43.

[0167] The third sensor 37 may be any of the sensors listed for the first sensor 35 and the second sensor 36. The third sensor 37 may be a temperature sensor that detects the temperature of the third adsorbent 131. The third sensor 37 may be a TCD sensor.

[0168] The configuration of the third recovery section 13 can be the same as the configurations of the first recovery section 11 and the second recovery section 12.

[0169] The third adsorbent 131 can be any of the materials listed for the first adsorbent 111 and the second adsorbent 121. The configuration of the first adsorbent 111 may be the same as or different from the configuration of the second adsorbent 121 and the configuration of the third adsorbent 131.

[0170] In the gas recovery system 200, for example, the control device 34 controls the first supply adjustment unit to the sixth supply adjustment unit to control the timing of implementing each mode, such as the first adsorption mode, the third pre-adsorption mode, the third adsorption mode, the second pre-adsorption mode, the second adsorption mode, and the first pre-adsorption mode.

[0171] The gas recovery system according to the modified example also allows each mode to be performed continuously. As a result, gas A can be recovered efficiently. The gas recovery system according to the modified example is particularly advantageous in that each mode can be performed in parallel and continuously, for example, when the adsorption rate of the adsorbent in each recovery section is slow.

[0172] Next, a gas recovery method using a gas recovery system according to a modified example will be described.

[0173] 4 includes the steps of introducing a first non-adsorbed gas G1 discharged from a first recovery section 11 into a first portion 511 of a first recycle path 51, introducing a third non-adsorbed gas G3 discharged from at least one third recovery section into a second portion 512 of the first recycle path 51 by supplying a mixed gas Gm, and introducing a second non-adsorbed gas G2 discharged from a second recovery section 12 into a second recycle path 52. The gas recovery method according to the modified example can also improve the recovery rate of the gas A that is ultimately obtained.

[0174] In the gas recovery method using the gas recovery system 200 shown in FIG. 4, the step of introducing the first non-adsorbed gas G1 into the first portion 511 of the first recycle path 51 is a step of supplying the first non-adsorbed gas G1 to the third recovery section 13 (third pre-adsorption step). The step of introducing the third non-adsorbed gas G3 into the second portion 512 of the first recycle path 51 is a step of supplying the third non-adsorbed gas G3 to the second recovery section 12 (second pre-adsorption step). The step of introducing the second non-adsorbed gas G2 into the second recycle path 52 is a step of supplying the second non-adsorbed gas G2 to the first recovery section 11 (first pre-adsorption step). The first pre-adsorption step corresponds to the first pre-adsorption mode, the third pre-adsorption step corresponds to the third pre-adsorption mode, and the second pre-adsorption step corresponds to the second pre-adsorption mode.

[0175] Figure 5 is a flow diagram showing an example of a gas recovery method using gas recovery system 200 shown in Figure 4. The upper part of Figure 5 shows the flow in first recovery section 11, the middle part shows the flow in third recovery section 13, and the lower part shows the flow in second recovery section 12.

[0176] The gas recovery method may further include a step of introducing the mixed gas Gm into a third supply path 43 in addition to a step of introducing the mixed gas Gm into a first supply path 41 from an external mixed gas supply source (not shown) and a step of introducing the mixed gas Gm into a second supply path 42 from an external mixed gas supply source (not shown).

[0177] 4, the step of introducing the mixed gas Gm into the third supply path 43 is a step (third adsorption step) of supplying the mixed gas Gm to the third recovery section 13. The third adsorption step corresponds to the third adsorption mode.

[0178] During the third adsorption step, the pressure in the third recovery section 13 is, for example, in the range of more than 0.1 MPa and not more than 3.0 MPa. The upper limit of the pressure in the third recovery section 13 may be not more than 2.5 MPa, not more than 2.0 MPa, not more than 1.5 MPa, or even not more than 1.0 MPa.

[0179] The pressure inside the third recovery section 13 during the execution of the third adsorption step can be adjusted by, for example, a pressure booster 31 provided in the supply path 40.

[0180] In addition to the steps of introducing the first non-adsorbed gas G1 into the first exhaust path 61 and the second non-adsorbed gas G2 into the second exhaust path 62, the gas recovery method may further include the step of introducing the third non-adsorbed gas G3 into the third exhaust path 63.

[0181] 4, the step of introducing the third non-adsorbed gas G3 into the third discharge path 63 is a step (third discharge step) of discharging the third non-adsorbed gas G3 from the third recovery section 13 to the outside of the gas recovery system 200. The third discharge step corresponds to a third discharge mode.

[0182] The step of introducing the third non-adsorbed gas G3 into the third discharge path 63 (third discharge step) may be performed when the content of gas A in the third non-adsorbed gas G3 is lower than a third threshold value.

[0183] The step of introducing the third non-adsorbed gas G3 into the first portion 511 of the first recycle path 51 (third pre-adsorption step) may be performed when the content of gas A in the third non-adsorbed gas G3 is equal to or greater than a third threshold value.

[0184] Whether the content of gas A in the third non-adsorbed gas G3 is greater than or equal to the third threshold value can be determined, for example, based on the measurement value of a third concentration sensor (not shown) that measures the content of gas A in the third non-adsorbed gas G3.

[0185] As shown in FIG. 5, in the gas recovery method using the gas recovery system 200 shown in FIG. 4, the first adsorption step and the first evacuation step can be performed in parallel. The first adsorption step and the third pre-adsorption step can be performed in parallel. The third pre-adsorption step can be performed after the first evacuation step. The third adsorption step and the third evacuation step can be performed in parallel. The third adsorption step and the second pre-adsorption step can be performed in parallel. The second pre-adsorption step can be performed after the third evacuation step. The second adsorption step and the second evacuation step can be performed in parallel. The second adsorption step and the first pre-adsorption step can be performed in parallel. The first pre-adsorption step can be performed after the second evacuation step.

[0186] The step of introducing the mixed gas Gm into the third supply path 43 (third adsorption step) may be performed when it is determined that the adsorption by the first adsorbent 111 in the first recovery section 11 has been completed.

[0187] The step of introducing the mixed gas Gm into the second supply path 42 (second adsorption step) may be performed when it is determined that adsorption by the third adsorbent 131 in the third recovery section 13 has been completed.

[0188] Whether or not the adsorption by the third adsorbent 131 has been completed can be determined based on, for example, a detection value of the third sensor 37 that detects the state of adsorption of the gas A by the third adsorbent 131.

[0189] The gas recovery method may further include a step of discharging a third adsorbed gas containing gas A from third recovery section 13 (third desorption step), in addition to a step of discharging a first adsorbed gas containing gas A from first recovery section 11 (first desorption step) and a step of discharging a second adsorbed gas containing gas A from second recovery section 12 (second desorption step). The third desorption step corresponds to a third desorption mode.

[0190] As in the case of the first desorption step and the second desorption step, the pressure in the third collection section 13 is reduced to, for example, 0.1 MPa when the third desorption step is performed. However, the pressure in the third collection section 13 may also be reduced to a region below atmospheric pressure (0.1 MPa or less).

[0191] The gas recovery method according to the modified example also allows the steps to be performed continuously, as shown in Fig. 5. As a result, the gas A can be recovered efficiently. The gas recovery method according to the modified example is particularly advantageous in that the steps can be performed in parallel and continuously, for example, when the adsorption speed of the adsorbent in each recovery section is slow.

[0192] (Other variations) The above examples may be combined with each other unless technically inconsistent. [Industrial Applicability]

[0193] The gas recovery system of this embodiment is suitable for recovering a specific gas such as carbon dioxide from a mixed gas containing the specific gas. [Explanation of symbols]

[0194] 11 First Collection Section 111 1st adsorbent 112 Container 11a Gas inlet 11b Gas outlet 12 Second Collection Section 121 Second adsorbent 122 Container 12a Gas inlet 12b Gas outlet 13 Third Recovery Section 131 Third adsorbent 21a, 21b, 21c, 21d Control valves 22a, 22b Control valve 23a, 23b Control valve 24a, 24b Control valve 25a, 25b Control valve 31 Booster 32 Back pressure valve 33 Concentration sensor 34 Control device 35 First Sensor 36 Second sensor 37 Third Sensor 38 Flow Controller 40 Supply Channels 41 First Supply Route 42 Second Supply Route 43 Third Supply Route 51 First recycling route 511 Part 1 512 Part 2 52 Second recycling route 60 Emission Route 61 First Emission Route 62 Secondary Emission Pathway 63 Third Emission Route 81, 82, 83, 84, 85 Branch position 91,92,93,94,95 Merging position 100,200 Gas recovery system Gm mixed gas G1 First non-adsorbed gas G2 Second non-adsorbed gas G3 Third non-adsorbable gas

Claims

1. a first recovery section having a first adsorbent that adsorbs the gas A contained in a mixed gas that includes a gas A and a gas B different from the gas A; a second recovery section having a second adsorbent that adsorbs the gas A contained in the mixed gas; a first recycle path that guides a first non-adsorbed gas discharged from the first recovery section as a result of the mixed gas being supplied from the first recovery section toward the second recovery section; a second recycle path that guides a second non-adsorbed gas discharged from the second recovery section as a result of the mixed gas being supplied from the second recovery section toward the first recovery section; A gas recovery system.

2. a first supply path that guides the mixed gas to the first recovery section; a second supply path that guides the mixed gas to the second recovery section; The gas recovery system of claim 1 further comprising:

3. a first concentration sensor for measuring the content of the gas A contained in the first non-adsorbed gas; a first supply adjusting unit that adjusts the introduction of the first non-adsorbed gas into the first recycle path; Furthermore, 2. The gas recovery system according to claim 1, wherein when a content of the gas A contained in the first non-adsorbed gas is equal to or greater than a first threshold value, the first non-adsorbed gas is introduced into the first recycle path.

4. a second concentration sensor for measuring the content of the gas A contained in the second non-adsorbed gas; a second supply adjusting unit that adjusts the introduction of the second non-adsorbed gas into the second recycle path; Furthermore, 2. The gas recovery system according to claim 1, wherein when the content of the gas A contained in the second non-adsorbed gas is equal to or greater than a second threshold value, the second non-adsorbed gas is introduced into the second recycle path.

5. a first exhaust path that guides the first non-adsorbed gas to the outside of the gas recovery system; 4. The gas recovery system according to claim 3, wherein when the content of the gas A contained in the first non-adsorbed gas is smaller than the first threshold value, the first non-adsorbed gas is introduced into the first discharge path.

6. a second exhaust path that guides the second non-adsorbed gas to the outside of the gas recovery system; 5. The gas recovery system according to claim 4, wherein when the content of the gas A contained in the second non-adsorbed gas is smaller than the second threshold value, the second non-adsorbed gas is introduced into the second discharge path.

7. a third supply adjusting unit that adjusts the introduction of the mixed gas into the second supply path; 3. The gas recovery system according to claim 2, wherein the mixed gas is introduced into the second supply line when it is determined that the adsorption by the first adsorbent has been completed.

8. a fourth supply adjustment unit that adjusts the introduction of the mixed gas into the first supply path; 3. The gas recovery system according to claim 2, wherein the mixed gas is introduced into the first supply line when it is determined that the adsorption by the second adsorbent has been completed.

9. the mixed gas further includes at least one third recovery unit having a third adsorbent that adsorbs the gas A contained in the mixed gas; The gas recovery system according to claim 1 , wherein the at least one third recovery section is provided in at least one path selected from the group consisting of the first recycle path and the second recycle path.

10. The gas recovery system according to claim 9 , further comprising a third supply line that guides the mixed gas to the at least one third recovery section.

11. 2. The gas recovery system of claim 1, wherein the mixed gas contains carbon dioxide as the gas A and nitrogen as the gas B.

12. a first recovery section having a first adsorbent that adsorbs the gas A contained in a mixed gas that includes a gas A and a gas B different from the gas A; a second recovery section having a second adsorbent that adsorbs the gas A contained in the mixed gas; a first recycle path that guides a first non-adsorbed gas discharged from the first recovery section by supplying the mixed gas from the first recovery section toward the second recovery section; a first supply path that guides the mixed gas to the first recovery section; a second supply path that guides the mixed gas to the second recovery section; A gas recovery system.

13. supplying the mixed gas to a first recovery section having a first adsorbent that adsorbs the gas A contained in the mixed gas, the first adsorbent being configured to adsorb the gas A contained in the mixed gas, and introducing a first non-adsorbed gas discharged from the first recovery section into a first recycle path; supplying the mixed gas to a second recovery section having a second adsorbent that adsorbs the gas A contained in the mixed gas, and introducing a second non-adsorbed gas discharged from the second recovery section into a second recycle path; Including, the first recycle path is a path that guides the first non-adsorbed gas from the first recovery section toward the second recovery section, The gas recovery method, wherein the second recycle path is a path that guides the second non-adsorbed gas from the second recovery section toward the first recovery section.

14. the step of introducing the first non-adsorbed gas into the first recycle path is executed when a content rate of the gas A contained in the first non-adsorbed gas is equal to or greater than a first threshold value; 14. The gas recovery method according to claim 13, wherein the step of introducing the second non-adsorbed gas into the second recycle path is performed when the content of the gas A contained in the second non-adsorbed gas is equal to or greater than a second threshold value.

15. introducing the mixed gas into a first supply path; introducing the mixed gas into a second supply path; Including, the first supply path is a path that guides the mixed gas to the first recovery section, the second supply path is a path that guides the mixed gas to the second recovery section, the step of introducing the mixed gas into the first supply path and the step of introducing the first non-adsorbed gas into the first recycle path are carried out in parallel, The gas recovery method according to claim 13 , wherein the step of introducing the mixed gas into the second supply path and the step of introducing the second non-adsorbed gas into the second recycle path are carried out in parallel.

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