Carbon dioxide recovery device

Abstract

A carbon dioxide recovery device (15) comprises a plurality of separation elements (20), a retention element (28), and a recirculation channel (29). The plurality of separation elements (20) are connected in series and are configured to separate carbon dioxide from air. The retention element (28) is connected to a specific separation element (20) that is at least one of the plurality of separation elements (20) and is configured to retain air that has been separated by the specific separation element (20) and has a high percentage of carbon dioxide. The recirculation channel (29) is configured to recirculate the air that is retained at the retention element (28) and has a high percentage of carbon dioxide to at least one separation element (20) of the plurality of separation elements (20) that is positioned upstream of the retention element (28).

Description

Carbon dioxide recovery device

[0001] The present disclosure relates to a carbon dioxide recovery device.

[0002] In recent years, with the promotion of carbon neutrality, it has been considered to separate and recover carbon dioxide contained in the air from the air and utilize the recovered carbon dioxide in various fields. As a technology for separating and recovering carbon dioxide contained in the air from the air (Direct Air Capture), for example, the carbon dioxide recovery device of Patent Document 1 is known.

[0003] Japanese Patent Application Laid-Open No. 2023-45570

[0004] In such a carbon dioxide recovery device, it is desired to recover high-concentration carbon dioxide.

[0005] The carbon dioxide recovery device according to one aspect of the present disclosure includes a plurality of separation elements, a storage element, and a reflux flow path. The plurality of separation elements are configured to separate carbon dioxide from the air and are connected in series with each other. The storage element is connected to a specific separation element that is at least one of the plurality of separation elements, and is configured to store air with a high proportion of carbon dioxide separated by the specific separation element. The reflux flow path is configured to reflux the air with a high proportion of carbon dioxide stored in the storage element to at least one separation element located upstream of the storage element among the plurality of separation elements.

[0006] FIG. 1 is a circuit diagram for explaining a carbon dioxide recovery system in an embodiment.

[0007] Hereinafter, an embodiment of the carbon dioxide recovery device will be described with reference to FIG. 1. The carbon dioxide recovery device of the present embodiment constitutes a part of a carbon dioxide recovery system. The carbon dioxide recovery system is used, for example, in a factory.

[0008] <Carbon Dioxide Capture System> As shown in Figure 1, the carbon dioxide capture system 10 is equipped with a supply line 11. The supply line 11 supplies compressed air from a compressor 12 to pneumatic equipment 13. The supply line 11 in this embodiment is existing equipment for supplying compressed air from a compressor 12 to pneumatic equipment 13 used in a factory.

[0009] The supply line 11 has a conditioning device 14. The conditioning device 14 removes moisture and foreign matter contained in the air compressed by the compressor 12. The carbon dioxide recovery device 15 is installed between the compressor 12 and the pneumatic device 13 in the supply line 11. The carbon dioxide recovery device 15 separates and recovers carbon dioxide from the air compressed by the compressor 12.

[0010] The compressor 12 has an inlet 12a and a discharge port 12b. The conditioning device 14 has a supply port 14a and an outlet port 14b. The carbon dioxide recovery device 15 has a housing 16. The housing 16 has an inlet 16a and an outlet 16b.

[0011] The carbon dioxide recovery system 10 includes a first supply pipe 17, a second supply pipe 18, and a third supply pipe 19. The first end of the first supply pipe 17 is connected to the discharge port 12b of the compressor 12. The second end of the first supply pipe 17 is connected to the supply port 14a of the conditioning equipment 14. The first supply pipe 17 connects the discharge port 12b of the compressor 12 and the supply port 14a of the conditioning equipment 14 to each other. The first end of the second supply pipe 18 is connected to the discharge port 14b of the conditioning equipment 14. The second end of the second supply pipe 18 is connected to the inlet 16a of the housing 16. The second supply pipe 18 connects the discharge port 14b of the conditioning equipment 14 and the inlet 16a of the housing 16 to each other. The first end of the third supply pipe 19 is connected to the outlet 16b of the housing 16. The second end of the third supply pipe 19 is connected to the pneumatic equipment 13. The third supply pipe 19 connects the outlet 16b of the housing 16 to the pneumatic equipment 13.

[0012] The inlet 16a of the housing 16 is configured to be detachably attached to the second end of the second supply pipe 18. The outlet 16b of the housing 16 is configured to be detachably attached to the first end of the third supply pipe 19. Therefore, the housing 16 is configured to be detachably attached to the second supply pipe 18 and the third supply pipe 19.

[0013] <Carbon Dioxide Recovery Device> The carbon dioxide recovery device 15 is equipped with multiple separation elements 20. Each separation element 20 is located inside the housing 16. The separation elements 20 separate carbon dioxide from air compressed by the compressor 12. The separation elements 20 separate carbon dioxide from air by membrane separation. Therefore, the carbon dioxide recovery device 15 separates carbon dioxide from air by membrane separation. Membrane separation is a method of filtering and extracting carbon dioxide by passing air through a membrane. In this embodiment, the carbon dioxide recovery device 15 has four separation elements 20. In the following description, each of the four separation elements 20 may also be referred to as "first separation element 20A", "second separation element 20B", "third separation element 20C", and "fourth separation element 20D".

[0014] The carbon dioxide recovery device 15 is equipped with a connecting channel 21. The connecting channel 21 is, for example, a pipe. The connecting channel 21 is provided inside the housing 16. In this embodiment, the carbon dioxide recovery device 15 is equipped with three connecting channels 21. In the following description, each of the three connecting channels 21 may be referred to as the "first connecting channel 21A", the "second connecting channel 21B", and the "third connecting channel 21C".

[0015] The first end of the first connecting channel 21A is connected to the first separation element 20A. The second end of the first connecting channel 21A is connected to the second separation element 20B. The first connecting channel 21A connects the first separation element 20A and the second separation element 20B in series. The first end of the second connecting channel 21B is connected to the second separation element 20B. The second end of the second connecting channel 21B is connected to the third separation element 20C. The second connecting channel 21B connects the second separation element 20B and the third separation element 20C in series. The first end of the third connecting channel 21C is connected to the third separation element 20C. The second end of the third connecting channel 21C is connected to the fourth separation element 20D. The third connecting channel 21C connects the third separation element 20C and the fourth separation element 20D in series. In this way, the connecting channel 21 connects two adjacent separation elements 20 of the separation elements 20 in series. In other words, the multiple separation elements 20 are connected in series with each other.

[0016] The first separation element 20A, the second separation element 20B, the third separation element 20C, and the fourth separation element 20D are connected in series in this order in the direction of airflow. Therefore, the fourth separation element 20D is the separation element 20 located furthest downstream among the multiple separation elements 20.

[0017] The carbon dioxide recovery device 15 is equipped with multiple suction pumps 22. In this embodiment, the carbon dioxide recovery device 15 is equipped with three suction pumps 22. In the following description, each of the three suction pumps 22 may be referred to as "first suction pump 22A," "second suction pump 22B," and "third suction pump 22C."

[0018] The first suction pump 22A is provided in the first connecting channel 21A. The first suction pump 22A draws in high-concentration carbon dioxide, i.e., air with a high proportion of carbon dioxide, that has been separated from the air by the first separation element 20A. The second suction pump 22B is provided in the second connecting channel 21B. The second suction pump 22B draws in high-concentration carbon dioxide, i.e., air with a high proportion of carbon dioxide, that has been separated from the air by the second separation element 20B. The third suction pump 22C is provided in the third connecting channel 21C. The third suction pump 22C draws in high-concentration carbon dioxide, i.e., air with a high proportion of carbon dioxide, that has been separated from the air by the third separation element 20C. In this way, suction pumps 22 are provided in each connecting channel 21. Each suction pump 22 draws in high-concentration carbon dioxide, i.e., air with a high proportion of carbon dioxide, that has been separated from the air by the upstream separation element 20 of two adjacent separation elements 20.

[0019] The carbon dioxide recovery device 15 is equipped with multiple tanks 23. In this embodiment, the carbon dioxide recovery device 15 is equipped with three tanks 23. In the following description, each of the three tanks 23 may be referred to as "first tank 23A," "second tank 23B," and "third tank 23C."

[0020] The first tank 23A is located downstream of the first suction pump 22A in the first connecting channel 21A. The first tank 23A stores air with a high proportion of carbon dioxide drawn in from the first separation element 20A by the first suction pump 22A. The second tank 23B is located downstream of the second suction pump 22B in the second connecting channel 21B. The second tank 23B stores air with a high proportion of carbon dioxide drawn in from the second separation element 20B by the second suction pump 22B. The third tank 23C is located downstream of the third suction pump 22C in the third connecting channel 21C. The third tank 23C stores air with a high proportion of carbon dioxide drawn in from the third separation element 20C by the third suction pump 22C. Thus, the tanks 23 are located downstream of each suction pump 22 in each connecting channel 21. Each tank 23 stores air with a high proportion of carbon dioxide drawn in from each separation element 20 by each suction pump 22.

[0021] The carbon dioxide recovery device 15 is equipped with a supply channel 24. The supply channel 24 is, for example, a pipe. The supply channel 24 is located inside the housing 16. The first end of the supply channel 24 is connected to the inlet 16a of the housing 16. The second end of the supply channel 24 is connected to the first separation element 20A.

[0022] The carbon dioxide recovery device 15 is equipped with multiple discharge channels 25. The discharge channels 25 are, for example, pipes. The discharge channels 25 are provided within the housing 16. In this embodiment, the carbon dioxide recovery device 15 is equipped with four discharge channels 25. In the following description, each of the four discharge channels 25 may also be referred to as "first discharge channel 25A", "second discharge channel 25B", "third discharge channel 25C", and "fourth discharge channel 25D".

[0023] The first end of the first discharge channel 25A is connected to the first separation element 20A. The second end of the first discharge channel 25A is connected to the outlet 16b. The first supply pipe 17, the second supply pipe 18, the supply channel 24, the first discharge channel 25A, and the third supply pipe 19 constitute the supply line 11.

[0024] The first end of the second discharge channel 25B is connected to the second separation element 20B. The second end of the second discharge channel 25B is open into the housing 16. The first end of the third discharge channel 25C is connected to the third separation element 20C. The second end of the third discharge channel 25C is open into the housing 16. The first end of the fourth discharge channel 25D is connected to the fourth separation element 20D. The second end of the fourth discharge channel 25D is open into the housing 16.

[0025] The carbon dioxide capture device 15 is equipped with silencers 26. The silencers 26 are provided in each of the second discharge passage 25B, the third discharge passage 25C, and the fourth discharge passage 25D. Each silencer 26 suppresses the exhaust noise of the air flowing through each of the second discharge passage 25B, the third discharge passage 25C, and the fourth discharge passage 25D.

[0026] The carbon dioxide recovery device 15 is equipped with multiple variable apertures 27. In this embodiment, the carbon dioxide recovery device 15 is equipped with three variable apertures 27. In the following description, each of the three variable apertures 27 may be referred to as "first variable aperture 27A," "second variable aperture 27B," and "third variable aperture 27C."

[0027] The first variable throttle 27A is located upstream of the silencer 26 in the second discharge passage 25B. The first variable throttle 27A adjusts the flow path cross-sectional area of ​​the second discharge passage 25B so that the pressure in the portion of the first connecting passage 21A located downstream of the first tank 23A becomes a predetermined pressure. The second variable throttle 27B is located upstream of the silencer 26 in the third discharge passage 25C. The second variable throttle 27B adjusts the flow path cross-sectional area of ​​the third discharge passage 25C so that the pressure in the portion of the second connecting passage 21B located downstream of the second tank 23B becomes a predetermined pressure. The third variable throttle 27C is located upstream of the silencer 26 in the fourth discharge passage 25D. The third variable throttle 27C adjusts the flow path cross-sectional area of ​​the fourth discharge passage 25D so that the pressure in the portion of the third connecting passage 21C located downstream of the third tank 23C becomes a predetermined pressure.

[0028] <Storage Element> The carbon dioxide recovery device 15 is equipped with a storage element 28. The storage element 28 is, for example, a tank. The storage element 28 is connected to the fourth separation element 20D. Therefore, the storage element 28 is connected to the downstream separation element 20 among the plurality of separation elements 20. The storage element 28 stores high-concentration carbon dioxide, i.e., air with a high proportion of carbon dioxide, which has been separated from the air by the fourth separation element 20D. In this way, at least one of the plurality of separation elements 20 is connected to a storage element 28 that stores high-concentration carbon dioxide, i.e., air with a high proportion of carbon dioxide, which has been separated from the air by the separation element 20. The storage element 28 is configured to be detachable from the fourth separation element 20D.

[0029] <Recirculation Channel> The carbon dioxide recovery device 15 is equipped with a recirculation channel 29. The recirculation channel 29 is, for example, a pipe. The recirculation channel 29 is provided inside the housing 16. The first end of the recirculation channel 29 is connected to the storage element 28. The second end of the recirculation channel 29 is connected to the portion of the second connecting channel 21B between the second separation element 20B and the second suction pump 22B. Therefore, the recirculation channel 29 is connected to the portion of the connecting channel 21 between the upstream separation element 20 of two adjacent separation elements 20 and the suction pump 22. The storage element 28 is configured to be detachably attached to the recirculation channel 29.

[0030] [Operation of the Embodiment] Next, the operation of this embodiment will be described. The compressor 12 draws in air from the intake port 12a and compresses the drawn-in air. The air compressed by the compressor 12 is discharged to the first supply pipe 17 via the discharge port 12b. The air discharged to the first supply pipe 17 is supplied to the air conditioning device 14 via the supply port 14a. The air conditioning device 14 removes moisture and foreign matter contained in the supplied air. The air from which moisture and foreign matter have been removed by the air conditioning device 14 flows into the supply flow path 24 via the discharge port 14b, the second supply pipe 18, and the inlet 16a.

[0031] The first separation element 20A separates carbon dioxide from the air supplied from the supply channel 24. The air from which carbon dioxide has been separated by the first separation element 20A flows through the first discharge channel 25A and is supplied to the pneumatic equipment 13 via the outlet 16b and the third supply pipe 19. Meanwhile, the high-concentration carbon dioxide separated from the air by the first separation element 20A, i.e., air with a high proportion of carbon dioxide, is sucked in by the first suction pump 22A and flows through the first connecting channel 21A to be stored in the first tank 23A. Here, the pressure in the portion of the first connecting channel 21A located downstream of the first tank 23A is set to a predetermined pressure by the first variable throttle 27A. Therefore, the air with a high proportion of carbon dioxide stored in the first tank 23A is output to the second separation element 20B via the first connecting channel 21A at a predetermined flow rate.

[0032] The second separation element 20B separates carbon dioxide from the air output from the first connecting channel 21A. The air from which carbon dioxide has been separated by the second separation element 20B is discharged into the housing 16 via the second discharge channel 25B. Meanwhile, the high-concentration carbon dioxide separated from the air by the second separation element 20B, i.e., air with a high proportion of carbon dioxide, is drawn in by the second suction pump 22B and flows through the second connecting channel 21B to be stored in the second tank 23B. Here, the pressure in the portion of the second connecting channel 21B located downstream of the second tank 23B is set to a predetermined pressure by the second variable throttle 27B. Therefore, the air with a high proportion of carbon dioxide stored in the second tank 23B is output to the third separation element 20C via the second connecting channel 21B at a predetermined flow rate.

[0033] The third separation element 20C separates carbon dioxide from the air output from the second connecting channel 21B. The air from which carbon dioxide has been separated by the third separation element 20C is discharged into the housing 16 via the third discharge channel 25C. Meanwhile, the high-concentration carbon dioxide separated from the air by the third separation element 20C, i.e., air with a high proportion of carbon dioxide, is drawn in by the third suction pump 22C and flows through the third connecting channel 21C to be stored in the third tank 23C. Here, the pressure in the portion of the third connecting channel 21C located downstream of the third tank 23C is set to a predetermined pressure by the third variable throttle 27C. Therefore, the air with a high proportion of carbon dioxide stored in the third tank 23C is output to the fourth separation element 20D via the third connecting channel 21C at a predetermined flow rate.

[0034] The fourth separation element 20D separates carbon dioxide from the air output from the third connecting channel 21C. The air from which carbon dioxide has been separated by the fourth separation element 20D is discharged into the housing 16 via the fourth discharge channel 25D. Meanwhile, the high-concentration carbon dioxide separated from the air by the fourth separation element 20D, i.e., air with a high proportion of carbon dioxide, flows through the recirculation channel 29 and is stored in the storage element 28. The air with a high proportion of carbon dioxide stored in the storage element 28 is sucked in by the second suction pump 22B and flows into the second connecting channel 21B via the recirculation channel 29.

[0035] Air with a high proportion of carbon dioxide that flows into the second connecting channel 21B via the recirculation channel 29 is output to the third separation element 20C together with the air with a high proportion of carbon dioxide output from the second separation element 20B. In this way, the recirculation channel 29 recirculates the air with a high proportion of carbon dioxide stored in the storage element 28 to the third separation element 20C. Therefore, the recirculation channel 29 recirculates the air with a high proportion of carbon dioxide stored in the storage element 28 to the separation element 20 located upstream of the storage element 28. The third separation element 20C is a separation element 20 located upstream of the fourth separation element 20D, which is located at the furthest downstream. Therefore, the recirculation channel 29 recirculates the air with a high proportion of carbon dioxide stored in the storage element 28 to the separation element 20 located upstream of the furthest downstream separation element 20 among the multiple separation elements 20. In this manner, the recirculation channel 29 recirculates air with a high proportion of carbon dioxide stored in the storage element 28 to the separation element 20 located upstream of the separation element 20 to which the storage element 28 is connected.

[0036] Air with a high proportion of carbon dioxide that has been recirculated from the recirculation channel 29 to the third separation element 20C has high concentrations of carbon dioxide separated by the third separation element 20C, and even higher concentrations of carbon dioxide are separated by the fourth separation element 20D. The recirculation channel 29 repeatedly recirculates air with a high proportion of carbon dioxide stored in the storage element 28 to the separation element 20 located upstream of the storage element 28. Therefore, the recirculation channel 29 constitutes a circulating loop circuit 30 that repeatedly recirculates air with a high proportion of carbon dioxide stored in the storage element 28 to the separation element 20 located upstream of the storage element 28.

[0037] [Effects of the Embodiment] The above embodiment provides the following effects: (1) The carbon dioxide recovery device 15 is equipped with a recirculation channel 29 that recirculates air with a high proportion of carbon dioxide stored in the storage element 28 to a separation element 20 located upstream of the storage element 28. This allows for further separation of carbon dioxide from air with a high proportion of carbon dioxide stored in the storage element 28, thereby enabling the recovery of high-concentration carbon dioxide.

[0038] (2) The recirculation channel 29 recirculates air with a high proportion of carbon dioxide stored in the storage element 28 to a separation element 20 among the multiple separation elements 20 that is located adjacent to the separation element 20 to which the storage element 28 is connected, on the upstream side. This allows for more efficient separation of carbon dioxide from air with a high proportion of carbon dioxide stored in the storage element 28, thereby enabling the recovery of higher concentrations of carbon dioxide.

[0039] (3) The storage element 28 is connected to the downstream separation element 20 among the multiple separation elements 20. As a result, carbon dioxide is separated from the air by as many separation elements 20 as possible, so that air with a high proportion of carbon dioxide is stored in the storage element 28. As a result, a higher concentration of carbon dioxide can be recovered.

[0040] (4) The recirculation channel 29 recirculates air with a high proportion of carbon dioxide stored in the storage element 28 to a separation element 20 located upstream of the downstream separation element 20 among the multiple separation elements 20. This allows for more efficient separation of carbon dioxide from air with a high proportion of carbon dioxide stored in the storage element 28, thereby enabling the recovery of higher concentrations of carbon dioxide.

[0041] (5) The reflux flow path 29 is connected to a portion between the separation element 20 and the suction pump 22 in the connection flow path 21. According to this, there is no need to separately provide a dedicated suction pump for refluxing the air with a high proportion of carbon dioxide stored in the storage element 28 to the separation element 20 located upstream of the storage element 28 through the reflux flow path 29. Therefore, the configuration of the carbon dioxide recovery device 15 can be simplified.

[0042] (6) The reflux flow path 29 constitutes a circulation loop circuit 30 that repeatedly refluxes the air with a high proportion of carbon dioxide stored in the storage element 28 to the separation element 20 located upstream of the storage element 28. According to this, carbon dioxide can be repeatedly separated from the air with a high proportion of carbon dioxide stored in the storage element 28, so that higher-concentration carbon dioxide can be recovered.

[0043] (7) Since carbon dioxide can be repeatedly separated from the air with a high proportion of carbon dioxide stored in the storage element 28 by the circulation loop circuit 30, there is no need to increase the separation element 20. Therefore, the number of parts of the carbon dioxide recovery device 15 can be reduced. As a result, the operating energy of the entire carbon dioxide recovery system 10 can be reduced.

[0044] (8) The concentration of carbon dioxide can be adjusted by adjusting the time for executing the step of repeatedly separating carbon dioxide from the air with a high proportion of carbon dioxide stored in the storage element 28 using the circulation loop circuit 30.

[0045] [Modification Example] Incidentally, the above embodiment can be implemented with the following modifications. The above embodiment and the following modification examples can be implemented in combination with each other within a technically non - conflicting range.

[0046] - In an embodiment, for example, the reflux channel 29 may reflux the air with a high proportion of carbon dioxide stored in the storage element 28 to the separation element 20 located two upstream of the separation element 20 to which the storage element 28 is connected among the plurality of separation elements 20. In short, the reflux channel 29 may reflux the air with a high proportion of carbon dioxide stored in the storage element 28 to any separation element 20 located upstream of the storage element 28.

[0047] - In an embodiment, the storage element 28 may be connected to a separation element 20 that is not located at the most downstream among the plurality of separation elements 20. - In an embodiment, the reflux channel 29 may not be connected to a part between the separation element 20 and the suction pump 22 in the connection channel 21. In this case, a dedicated suction pump for refluxing the air with a high proportion of carbon dioxide stored in the storage element 28 to the separation element 20 located upstream of the storage element 28 by the reflux channel 29 may be provided separately.

[0048] - In an embodiment, the storage element 28 may also be connected to separation elements 20 other than the fourth separation element 20D. In short, the storage element 28 may be connected to at least one of the plurality of separation elements 20.

[0049] - In an embodiment, the number of separation elements 20 is not particularly limited. - In an embodiment, the separation element 20 may separate carbon dioxide from air by a zeolite separation method or an electric separation method. In short, the carbon dioxide recovery device 15 may separate carbon dioxide from air by any one of a membrane separation method, a zeolite separation method, or an electric separation method. According to this, for example, compared with a method of adsorbing carbon dioxide to an adsorbent and then applying thermal energy to the adsorbent to strip carbon dioxide from the adsorbent, such as a chemical absorption method or a physical absorption method, carbon dioxide can be separated from air with energy savings.

[0050] In this embodiment, the separation element 20 may separate carbon dioxide from the air by a method such as chemical absorption or physical absorption, which involves adsorbing carbon dioxide onto an adsorbent and then applying thermal energy to the adsorbent to detach the carbon dioxide from the adsorbent.

[0051] In this embodiment, the storage element 28 may be, for example, an adsorbent.

Claims

1. A carbon dioxide recovery device comprising: a plurality of separation elements configured to separate carbon dioxide from air and connected in series with each other; a storage element connected to a specific separation element, which is at least one of the plurality of separation elements, and configured to store air with a high proportion of carbon dioxide separated by the specific separation element; and a recirculation channel configured to recirculate the air with a high proportion of carbon dioxide stored in the storage element to at least one of the plurality of separation elements located upstream of the storage element.

2. The carbon dioxide recovery apparatus according to claim 1, wherein the recirculation channel is configured to recirculate air with a high proportion of carbon dioxide stored in the storage element to a separation element among the plurality of separation elements that is located adjacent to the specific separation element on the upstream side.

3. The carbon dioxide recovery apparatus according to claim 1 or claim 2, wherein the storage element is connected to the downstream separation element among the plurality of separation elements.

4. The carbon dioxide recovery apparatus according to claim 3, wherein the recirculation channel is configured to recirculate air with a high proportion of carbon dioxide stored in the storage element to a separation element located adjacent to the downstream separation element among the plurality of separation elements on the upstream side.

5. A carbon dioxide recovery device according to any one of claims 1 to 4, further comprising: a connecting channel that connects two adjacent separation elements in series; and a suction pump provided in the connecting channel and configured to suck up air with a high proportion of carbon dioxide separated by the upstream separation element of the two adjacent separation elements, wherein the recirculation channel is connected to the portion of the connecting channel between the upstream separation element and the suction pump.

6. The carbon dioxide recovery apparatus according to any one of claims 1 to 5, wherein the recirculation channel is configured to repeatedly recirculate air with a high proportion of carbon dioxide stored in the storage element to at least one separation element located upstream of the storage element, forming a circulating loop circuit.

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