Carbon dioxide capture system

Abstract

To provide a carbon dioxide recovery system which can effectively suppress deterioration of adsorption performance of carbon dioxide of an electrochemical cell.SOLUTION: A carbon dioxide recovery system 10 includes information acquisition parts (S200, S220, S300 and S310) for acquiring information on a substance which is included in the atmosphere and can be bonded to an electrochemical cell 12a. A control device 17 is configured to switch whether to execute or not to execute at least control for recovering carbon dioxide, on the basis of information acquired by the information acquisition parts.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a carbon dioxide capture system that captures carbon dioxide from atmospheric air containing carbon dioxide. [Background technology]

[0002] Patent Document 1 proposes a gas separation system that separates carbon dioxide from a mixed gas containing carbon dioxide through an electrochemical reaction. In this gas separation system, a mixed gas containing carbon dioxide is introduced into a housing in which an electrochemical cell is placed. In a charge mode in which electrons are directed toward the negative electrode of the electrochemical cell, the electroactive material provided on the negative electrode is reduced. This causes a bond between the electroactive material at the negative electrode and carbon dioxide, and carbon dioxide is separated from the mixed gas. Meanwhile, in a discharge mode in which electrons flow in the opposite direction to the electron flow during the charge mode, the electroactive material at the negative electrode is oxidized. This causes carbon dioxide to be released from the electroactive material at the negative electrode. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2018-533470 Summary of the Invention [Problem to be solved by the invention]

[0004] In the electrochemical cell described above, the amount of carbon dioxide bound to the electroactive material decreases as the electroactive material repeatedly binds to and releases the bound carbon dioxide. In other words, the carbon dioxide adsorption performance of the electrochemical cell deteriorates with repeated use. An electrochemical cell with deteriorated carbon dioxide adsorption performance requires maintenance, such as cleaning or replacement. Therefore, if the deterioration of the carbon dioxide adsorption performance of an electrochemical cell can be suppressed and the maintenance interval can be extended, it would be of great benefit to users.

[0005] The present disclosure has been made in consideration of the above-mentioned points, and aims to provide a carbon dioxide recovery system that can effectively suppress deterioration of the carbon dioxide adsorption performance of an electrochemical cell. [Means for solving the problem]

[0006] In order to achieve the above object, the carbon dioxide capture system according to the present disclosure comprises: A method for recovering carbon dioxide from atmospheric air containing carbon dioxide by an electrochemical reaction, an electrochemical cell (12a) disposed within the housing, which adsorbs carbon dioxide and desorbs the adsorbed carbon dioxide in response to an applied electric potential; a recovery unit (11, 12, 13, 14, 16) that recovers carbon dioxide desorbed from the electrochemical cell; a control unit (17) that controls the electrochemical cell and the recovery unit so as to apply an adsorption potential to the electrochemical cell to cause carbon dioxide contained in the air introduced into the housing to be adsorbed by the electrochemical cell, and to apply a desorption potential to the electrochemical cell to cause carbon dioxide to be desorbed from the electrochemical cell and recovered by the recovery unit; an information acquisition unit (S200, S220, S300, S310) that acquires information about substances contained in the atmosphere that may adhere to the electrochemical cell; The control unit is configured to switch at least between executing and not executing control for recovering carbon dioxide based on the information acquired by the information acquisition unit.

[0007] One factor that accelerates the deterioration of the carbon dioxide adsorption performance of electrochemical cells is the adhesion of substances contained in the atmosphere, such as salt, yellow sand, and fine particulate matter (e.g., PM2.5), to the electrochemical cell. When such substances adhere to the electrochemical cell, the carbon dioxide adsorption area decreases, accelerating the deterioration of the electrochemical cell's carbon dioxide adsorption performance. Conversely, if the adhesion of such substances to the electrochemical cell can be prevented, it will be possible to suppress the deterioration of the electrochemical cell's carbon dioxide adsorption performance.

[0008] Therefore, the carbon dioxide capture system according to the present disclosure includes an information acquisition unit that acquires information about substances contained in the atmosphere that may adhere to the electrochemical cell. The control unit is configured to switch at least between executing and not executing control for carbon dioxide capture based on the information acquired by the information acquisition unit. In this way, by acquiring information about substances that may adhere to the electrochemical cell and switching between executing and not executing control for carbon dioxide capture according to the acquired information, it is possible to not execute control for carbon dioxide capture in situations where substances are adhering to the electrochemical cell. As a result, it is possible to suppress adhesion of substances to the electrochemical cell and suppress deterioration of the carbon dioxide adsorption performance of the electrochemical cell.

[0009] The reference numbers in parentheses above merely indicate an example of a correspondence with specific configurations in the embodiments described below, in order to facilitate understanding of the present disclosure, and are not intended to limit the scope of the present disclosure in any way.

[0010] Furthermore, the technical features of the present disclosure other than those described above will become apparent from the following description of the embodiments and the accompanying drawings. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a diagram showing a configuration of a carbon dioxide capture system according to an embodiment. [Figure 2] 4 is a flowchart showing the processing in a control device for executing a series of control sequences for carbon dioxide recovery. [Figure 3] 1(a) to 1(c) are explanatory diagrams for explaining an adsorption mode, a scavenging mode, and a desorption / recovery mode included in a series of control sequences. [Figure 4] 1 is a flowchart showing a salt damage prevention process for preventing salt contained in the atmosphere from adhering to an electrochemical cell. [Figure 5]10 is a diagram showing the flow of air when the air introduction direction into the collector is reversed by rotating the blower fan of the blower in the reverse direction. FIG. [Figure 6] 4 is a flowchart showing a particulate adhesion prevention process for preventing particulates such as yellow sand and fine particulate matter contained in the atmosphere from adhering to an electrochemical cell. DETAILED DESCRIPTION OF THE INVENTION

[0012] A carbon dioxide capture system according to an embodiment of the present disclosure will now be described in detail with reference to the drawings. Note that identical or equivalent parts are designated by the same reference numerals throughout the drawings. The carbon dioxide capture system according to this embodiment captures carbon dioxide from the atmosphere containing carbon dioxide. The atmosphere from which the carbon dioxide has been removed is discharged to the outside. Figure 1 shows a schematic configuration of a carbon dioxide capture system 10 according to this embodiment.

[0013] The carbon dioxide capture system 10 shown in Figure 1 includes a flow path opening / closing valve 11, a capture device 12, a pump 13, a flow path switching valve 14, a CO2 sensor 15, a CO2 capture tank 16, a control device 17, a blower 19, a wind direction and wind speed sensor 20, and an external server 21.

[0014] The open / close state of the flow path on-off valve 11 is controlled by the control device 17. When the flow path on-off valve 11 is opened, air containing carbon dioxide can be introduced into the collector 12 through the flow path piping that communicates the atmosphere with the inside of the collector 12. On the other hand, when the flow path on-off valve 11 is closed, the flow path piping that communicates the atmosphere with the inside of the collector 12 is blocked, and the collector 12 is sealed. As a result, air cannot enter the collector 12 through the flow path piping in which the flow path on-off valve 11 is provided.

[0015] Although not shown, the blower 19 has a blower fan rotated by a motor. When the flow path opening / closing valve 11 is open, the blower fan of the blower 19 is rotationally driven by the control device 17. As a result, air containing carbon dioxide is sent into the collector 12 through a flow path piping that connects the atmosphere with the inside of the collector 12. However, the blower 19 may be omitted. Alternatively, the blower fan of the blower 19 may be configured to be rotatably driven in both the forward and reverse directions by the control device 17. When the blower fan is rotationally driven in the forward direction, it sends air into the collector 12 through the flow path piping in which the flow path opening / closing valve 11 is provided. On the other hand, when the blower fan is rotationally driven in the reverse direction, it takes in air into the collector 12 through a flow path piping for discharging air from which carbon dioxide has been desorbed, as described below, and discharges the air from which carbon dioxide has been removed to the outside through the flow path piping in which the flow path opening / closing valve 11 is provided.

[0016] The collector 12 includes an electrochemical cell 12a disposed within a housing made of, for example, a metal. The electrochemical cell 12a is capable of adsorbing carbon dioxide through an electrochemical reaction to separate the carbon dioxide from the atmosphere, or desorbing the adsorbed carbon dioxide and storing the desorbed carbon dioxide in a CO2 capture tank 16 using a pump 13. The collector 12 has two openings. One of the openings is an inlet for introducing atmosphere containing carbon dioxide from the outside into the housing of the collector 12. The other opening is an outlet for discharging atmosphere from which carbon dioxide has been removed and carbon dioxide desorbed from the electrochemical cell 12a. A flow path pipe provided with the above-mentioned flow path opening / closing valve 11 is connected to the inlet, and a flow path pipe provided with the pump 13 is connected to the outlet. Note that the inside of the collector 12 is the same as the inside of the housing.

[0017] A plurality of electrochemical cells 12a are stacked and arranged inside the housing of the collector 12. The stacking direction of the plurality of electrochemical cells 12a is perpendicular to the direction of air flow. Each electrochemical cell 12a is configured in a plate shape and is arranged so that the plate surface intersects with the cell stacking direction. A predetermined gap is provided between adjacent electrochemical cells 12a. The gap provided between adjacent electrochemical cells 12a serves as a flow path for air to flow.

[0018] Each electrochemical cell 12a is configured by stacking, for example, a working electrode current collecting layer, a working electrode, a separator, a counter electrode, and a counter electrode current collecting layer in the listed order. The working electrode is a negative electrode, and the counter electrode paired with the working electrode is a positive electrode. By changing the potential difference applied between the working electrode and the counter electrode, electrons can be supplied to the working electrode to adsorb carbon dioxide to the carbon dioxide adsorbent of the working electrode, or electrons can be released from the working electrode to desorb the adsorbed carbon dioxide. That is, by applying an adsorption potential between the working electrode and the counter electrode of the electrochemical cell 12a, carbon dioxide can be adsorbed into the electrochemical cell 12a (the carbon dioxide adsorbent of the working electrode). Furthermore, by applying a desorption potential different from the adsorption potential between the working electrode and the counter electrode of the electrochemical cell 12a, carbon dioxide can be desorbed from the electrochemical cell 12a.

[0019] The working electrode current collecting layer is made of a porous conductive material having pores through which the air containing carbon dioxide can pass. The working electrode current collecting layer may be formed from any material as long as it is gas permeable and conductive, and may be made from, for example, a metal material or a carbonaceous material.

[0020] The working electrode is formed from a material that is a mixture of a carbon dioxide adsorbent, a conductive material, a binder, and the like. The carbon dioxide adsorbent has the property of adsorbing carbon dioxide by receiving electrons and desorbing the adsorbed carbon dioxide by releasing electrons. Polyanthraquinone, for example, can be used as the carbon dioxide adsorbent. The conductive material forms a conductive path to the carbon dioxide adsorbent. Carbon materials such as carbon nanotubes, carbon black, and graphene can be used as the conductive material. The binder is used to hold the carbon dioxide adsorbent and the conductive material. A conductive resin, for example, can be used as the binder. For example, an epoxy resin containing Ag or the like as a conductive filler, or a fluororesin such as polytetrafluoroethylene (PTFE) or polyvinylidene fluoride (PVDF), can be used as the conductive resin.

[0021] The counter electrode is formed from a material that includes a mixture of an electroactive auxiliary material, a conductive material, a binder, and the like. The conductive material and binder of the counter electrode are similar to those of the working electrode, and therefore will not be described here. The electroactive auxiliary material of the counter electrode is composed of a material that contains an active material that serves as an electron donor. The electroactive auxiliary material of the counter electrode is a supplementary electroactive species that exchanges electrons with the carbon dioxide adsorbent of the working electrode. Examples of the electroactive auxiliary material include metal complexes that enable electron exchange by changing the valence of the metal ions. Examples of such metal complexes include cyclopentadienyl metal complexes such as ferrocene, nickelocene, and cobaltocene, as well as porphyrin metal complexes. These metal complexes may be polymers or monomers. The counter electrode current collecting layer, like the working electrode current collecting layer, is formed from a conductive material such as a metal material or a carbonaceous material.

[0022] The separator is placed between the working electrode and the counter electrode to separate them. The separator is an insulating ion-permeable membrane that prevents physical contact between the working electrode and the counter electrode to prevent electrical short circuits and allows ions to pass through. The separator can be made of a cellulose membrane, a polymer, a composite material of polymer and ceramic, or the like.

[0023] The electrochemical cell 12a is provided with an electrolyte that spans the working electrode and the counter electrode. The electrolyte may be, for example, an ionic liquid. The ionic liquid is a liquid salt that is nonvolatile at room temperature and normal pressure.

[0024] The pump 13 sucks the residual air remaining in the collector 12 from which carbon dioxide has been removed and releases it to the outside (i.e., scavenges the residual air in the collector 12), or sucks the desorbed carbon dioxide from the collector 12 when the carbon dioxide adsorbent desorbs the carbon dioxide, and discharges it toward the CO2 capture tank 16. When the pump 13 scavenges the residual air in the collector 12, the flow path opening / closing valve 11 blocks the flow path piping connecting the outside with the inside of the collector 12. In other words, the flow path opening / closing valve 11 is opened only during an adsorption mode in which the control device 17 executes control for carbon dioxide capture and causes the electrochemical cell 12a (carbon dioxide adsorbent) to adsorb carbon dioxide, and is closed during a scavenging mode in which the residual air is scavenged from the collector 12, and a desorption / capture mode in which the electrochemical cell 12a desorbs the carbon dioxide adsorbed by the electrochemical cell 12a and captures it in the CO2 capture tank 16. Therefore, the residual air in the recovery device 12 is purged by vacuuming using the pump 13. The subsequent discharge of carbon dioxide into the CO2 recovery tank 16 is also carried out in a state closer to a vacuum than the atmosphere.

[0025] The flow path switching valve 14 is a three-way valve that switches the flow path of the gas (air or carbon dioxide) flowing through the pipe downstream of the pump 13. The switching of the flow path by the flow path switching valve 14 is controlled by the control device 17. Specifically, when air containing carbon dioxide is introduced into the collector 12 and when the pump 13 scavenges the remaining air in the collector 12, the control device 17 controls the flow path switching valve 14 to communicate with the outside (air). As a result, the air from which carbon dioxide has been removed and the remaining air in the collector 12 are released to the outside. On the other hand, when the electrochemical cell 12a desorbs carbon dioxide adsorbed by the electrochemical cell 12a, the control device 17 controls the flow path switching valve 14 to communicate with the CO2 capture tank 16 when the pump 13 sucks and discharges the desorbed carbon dioxide from the collector 12. As a result, the carbon dioxide captured by the collector 12 can be accumulated in the CO2 capture tank 16.

[0026] The CO2 sensor 15 detects the carbon dioxide concentration and flow rate of the gas flowing through the pipe connected to the CO2 capture tank 16 at predetermined time intervals. The control device 17 can calculate (detect) the amount of carbon dioxide captured in the CO2 capture tank 16 from the carbon dioxide concentration and flow rate detected by the CO2 sensor 15. The amount of carbon dioxide captured may be calculated by the CO2 sensor 15. In this case, the CO2 sensor 15 outputs the calculated amount of carbon dioxide captured to the control device 17.

[0027] The control device 17 is composed of a well-known microcomputer including a CPU, ROM, RAM, etc., and its peripheral devices. The peripheral devices include a transmitter / receiver that communicates with an external server 21, etc., and a memory unit 18 that has a storage medium. The memory unit 18 stores information regarding the installation location of the carbon dioxide capture system 10 and the direction in which the opening of the flow path piping connected to the inlet of the capture device 12 is facing. In addition to the installation location of the carbon dioxide capture system 10, if the carbon dioxide capture system 10 is installed in a coastal area where salt damage is likely to occur, the memory unit 18 may also store information indicating this. Note that instead of storing the installation location of the carbon dioxide capture system 10 in the memory unit 18, the installation location may be detected, for example, by a GPS receiver.

[0028] The wind direction and wind speed sensor 20 detects information about wind direction and wind speed in the vicinity of the carbon dioxide capture system 10. The detected information about wind direction and wind speed is provided to the control device 17. The external server 21 provides the control device 17 with information about the amount of yellow sand and / or fine particulate matter (e.g., PM2.5) contained in the atmosphere in the area where the carbon dioxide capture system 10 is installed. The external server 21 can obtain information about the amount of yellow sand and / or fine particulate matter (e.g., PM2.5) contained in the atmosphere from information released by, for example, the Ministry of the Environment or the Japan Meteorological Agency.

[0029] The control device 17 performs various arithmetic processes based on a control program stored in a storage medium such as a ROM, and controls the operation of various control target devices such as the flow path on-off valve 11, the recovery device 12, the pump 13, the flow path switching valve 14, and the blower 19. Furthermore, the control device 17 communicates with an external server 21 via a transmitting / receiving unit. The control device 17 switches between executing or not executing control for recovering carbon dioxide based on information stored in the storage unit 18, information detected by the wind direction and wind speed sensor 20, and information acquired through communication with the external server 21. The information stored in the storage unit 18, information detected by the wind direction and wind speed sensor 20, and information acquired through communication with the external server 21 correspond to information acquired by the information acquiring unit.

[0030] When executing control for capturing carbon dioxide, the control device 17 of this embodiment controls the operation of various controlled devices so that a series of control sequences including at least an adsorption mode, a scavenging mode, and a desorption / capture mode are executed in the carbon dioxide capture system 10. Note that the desorption / capture mode indicates that the desorption mode and the capture mode are combined into one mode.

[0031] Below, we will explain a series of control sequences for capturing carbon dioxide, which include at least an adsorption mode, a scavenging mode, and a desorption / capture mode, executed in the carbon dioxide capture system 10. Fig. 2 is a flowchart showing the processing performed by the control device 17 to execute the control sequences. Figs. 3(a)-(c) are explanatory diagrams for explaining the adsorption mode, the scavenging mode, and the desorption / capture mode included in the series of control sequences.

[0032] 2, the control device 17 first starts the adsorption mode, which is the first operation mode of the control sequence, in step S100. In this adsorption mode, as shown in FIG. 3(a), the flow path opening / closing valve 11 is opened to allow air containing carbon dioxide to be introduced into the collector 12. If a blower 19 is provided, the blower 19 is driven at a predetermined constant rotation speed so that a predetermined amount of air is introduced into the collector 12.

[0033] In the adsorption mode, an adsorption potential is applied between the working electrode and the counter electrode of the electrochemical cell 12a of the recovery device 12 so that the carbon dioxide adsorbent of the working electrode can adsorb carbon dioxide. This adsorption potential is a predetermined constant potential. Furthermore, in the adsorption mode, as shown in FIG. 3(a), the flow path switching valve 14 is controlled to connect the flow path piping downstream of the pump 13 to the outside.

[0034] In the adsorption mode, by controlling the flow path opening / closing valve 11, the electrochemical cells 12a of the collector 12, the flow path switching valve 14, and the like, the air containing carbon dioxide passes through the flow path opening / closing valve 11 and enters the collector 12, as shown by the dotted arrow in FIG. 3(a). The carbon dioxide contained in the air that has entered the collector 12 is adsorbed by the multiple electrochemical cells 12a. As a result, the carbon dioxide is removed from the air. The air from which the carbon dioxide has been removed passes through the pump 13, is guided by the flow path switching valve 14 to a flow path piping leading to the outside, and is released to the outside via the flow path piping.

[0035] 2, the control device 17 determines whether or not the adsorption mode execution time has elapsed. The adsorption mode execution time is set by the control device 17. In step S110, it is determined whether or not the set adsorption mode execution time has elapsed.

[0036] If it is determined in the determination process of step S110 that the set adsorption mode execution time has elapsed, the process proceeds to step S120. On the other hand, if it is determined that the set adsorption mode execution time has not elapsed, the determination process of step S110 is repeatedly executed until the adsorption mode execution time has elapsed.

[0037] In step S120, adsorption mode termination processing is executed. Specifically, the control device 17 closes the flow path on-off valve 11 to block air from flowing into the collector 12 from the outside. In addition, if a blower 19 is provided, the control device 17 stops driving the blower 19. The control device 17 also resets the count value of a counter that counts the adsorption mode execution time.

[0038] In step S130, the control device 17 starts a scavenging mode, which is the second operation mode of the control sequence. In this scavenging mode, as shown in FIG. 3(b), the flow path opening / closing valve 11 remains closed. The adsorption potential applied between the working electrode and the counter electrode of the electrochemical cell 12a of the recovery device 12 is maintained. The flow path switching valve 14 also maintains communication between the flow path piping downstream of the pump 13 and the outside.

[0039] In the scavenging mode, the pump 13 starts to be driven. As described above, the flow path on-off valve 11 is closed, so the collector 12 is sealed on the upstream side of the pump 13. When the pump 13 is driven in this state, the residual air, which is the air from which carbon dioxide has been removed and remains in the sealed collector 12, is sucked from the collector 12 and released to the outside. This allows the residual air in the collector 12 to be scavenged. Note that, because the collector 12 on the upstream side of the pump 13 is sealed, scavenging of the residual air in the collector 12 is performed by vacuuming using the pump 13.

[0040] By controlling the flow path opening / closing valve 11, the electrochemical cell 12a of the recovery device 12, the pump 13, and the flow path switching valve 14 in this way, in the scavenging mode, as shown by the dotted arrow in FIG. 3(b), the residual air in the recovery device 12 from which carbon dioxide has been removed passes through the pump 13, is guided by the flow path switching valve 14 to a flow path piping leading to the outside, and is then released to the outside via the flow path piping.

[0041] 2, the control device 17 determines whether the scavenging mode execution time has elapsed. The scavenging mode execution time is predetermined to be a time sufficient to scavenge the remaining air in the collector 12.

[0042] In the determination process of step S140, if it is determined that the predetermined scavenging mode execution time has elapsed, the process proceeds to step S150. On the other hand, if it is determined that the set scavenging mode execution time has not elapsed, the determination process of step S140 is repeatedly executed until the scavenging mode execution time has elapsed. In step S150, a scavenging mode termination process is executed. Specifically, the control device 17 resets the count value of a counter that counts the scavenging mode execution time.

[0043] In step S160, the control device 17 starts the desorption / recovery mode, which is the third operating mode in the control sequence. In this desorption / recovery mode, the flow path opening / closing valve 11 is maintained in a closed state, as shown in FIG. 3(c). The pump 13 also continues to be driven with a drive output equivalent to that in the scavenging mode, in order to suck in carbon dioxide desorbed from the adsorbent of the electrochemical cell 12a in a state closer to a vacuum than the atmosphere.

[0044] Meanwhile, a desorption potential is applied between the working electrode and counter electrode of the electrochemical cell 12a of the recovery device 12, which causes electrons to be emitted from the working electrode, thereby enabling the carbon dioxide adsorbed by the carbon dioxide adsorbent of the working electrode to be desorbed. This desorption potential is a predetermined constant potential. Furthermore, in the desorption / recovery mode, as shown in FIG. 3(c), the flow path switching valve 14 is controlled to connect the piping downstream of the pump 13 to the CO2 recovery tank 16.

[0045] 3(c), by controlling the flow path opening / closing valve 11, the electrochemical cell 12a of the collector 12, the pump 13, and the flow path switching valve 14, carbon dioxide desorbed from the adsorbent of the electrochemical cell 12a passes through the pump 13, is guided by the flow path switching valve 14 to the flow path piping leading to the CO2 capture tank 16, and is accumulated in the CO2 capture tank 16 via the flow path piping. Therefore, the flow path opening / closing valve 11, the collector 12, the pump 13, the flow path switching valve 14, and the CO2 capture tank 16 correspond to a capture unit that captures carbon dioxide desorbed from the electrochemical cell 12a.

[0046] At this time, the concentration and flow rate of carbon dioxide flowing through the flow path piping toward the CO2 capture tank 16 are detected by the CO2 sensor 15. Based on the detection results of the CO2 sensor 15, the control device 17 can calculate the amount of carbon dioxide captured in the CO2 capture tank 16 by executing a series of control sequences. Note that the concentration of carbon dioxide flowing through the flow path piping toward the CO2 capture tank 16 is usually close to 100%. For this reason, a sensor that can only detect the flow rate of carbon dioxide may be used as the CO2 sensor 15.

[0047] In addition, instead of simultaneously performing carbon dioxide desorption and capture in the desorption and capture mode, carbon dioxide desorption from the electrochemical cell 12a may be performed first, and the capture of the desorbed carbon dioxide may begin a predetermined time after the desorption of carbon dioxide. That is, the desorption mode and the capture mode may be separated, and the capture mode may be started later than the desorption mode, thereby shortening the execution time of the capture mode. In this case, the pump 13 is temporarily stopped at the start of the desorption mode. Then, with the pump 13 stopped, a desorption potential is applied between the working electrode and counter electrode of the electrochemical cell 12a to desorb carbon dioxide from the carbon dioxide adsorbent on the working electrode. After a predetermined time has passed since the start of the desorption mode and carbon dioxide desorption has progressed to a certain extent, the capture mode is started, and the pump 13 is restarted. This allows the pump 13 to be driven only in the capture mode, thereby enabling efficient operation of the pump 13. However, even during the recovery mode in which the pump 13 is driven, a desorption potential is applied between the working electrode and the counter electrode of the electrochemical cell 12a, and carbon dioxide continues to be desorbed from the electrochemical cell 12a. That is, when the recovery mode is being executed, the desorption mode is also being executed continuously, and the recovery mode and the desorption mode are executed simultaneously.

[0048] In step S170 of the flowchart in Fig. 2, the control device 17 determines whether the desorption / recovery mode execution time or the recovery mode execution time (hereinafter referred to as the recovery mode execution time) has elapsed. The recovery mode execution time is set by the control device 17. In step S170, it is determined whether the set recovery mode execution time has elapsed.

[0049] If it is determined in the determination process of step S170 that the set collection mode execution time has elapsed, the process proceeds to step S180. On the other hand, if it is determined that the set collection mode execution time has not elapsed, the determination process of step S170 is repeatedly executed until the collection mode execution time has elapsed.

[0050] In step S180, a recovery mode termination process is executed. Specifically, the control device 17 opens the flow path opening / closing valve 11 to connect the recovery device 12 to the outside. However, the flow path opening / closing valve 11 may be opened at the start of the adsorption mode and kept closed at the end of the recovery mode. The control device 17 stops the application of the desorption potential to the electrochemical cell 12a. The control device 17 stops driving the pump 13. The control device 17 switches the flow path switching valve 14 to connect the flow path piping downstream of the pump 13 to the outside. This connection of the flow path piping downstream of the pump 13 to the outside may also be performed at the start of the adsorption mode. Furthermore, the control device 17 resets the count value of a counter that counts the recovery mode execution time.

[0051] Here, the carbon dioxide adsorption performance of the electrochemical cell 12a described above deteriorates with repeated use of the electrochemical cell 12a. An electrochemical cell 12a with deteriorated carbon dioxide adsorption performance requires maintenance such as cleaning or replacement. Therefore, if the deterioration of the carbon dioxide adsorption performance of the electrochemical cell 12a can be suppressed and the maintenance interval can be extended, it would be a great benefit to the user.

[0052] One factor that accelerates the deterioration of the carbon dioxide adsorption performance of the electrochemical cell 12a is the adhesion of substances contained in the atmosphere, such as salt, yellow sand, and fine particulate matter (e.g., PM2.5), to the electrochemical cell 12a. When such substances adhere to the electrochemical cell 12a, the carbon dioxide adsorption area of ​​the adsorbent decreases. This accelerates the deterioration of the carbon dioxide adsorption performance of the electrochemical cell 12a. Conversely, if the adhesion of such substances to the electrochemical cell 12a can be suppressed, it is possible to suppress the deterioration of the carbon dioxide adsorption performance of the electrochemical cell 12a.

[0053] Therefore, the carbon dioxide capture system 10 according to the present disclosure is configured to acquire information about substances contained in the atmosphere, such as salt, yellow sand, and fine particulate matter, and to switch at least between executing and not executing control for carbon dioxide capture based on the acquired information. This allows the control device 17 to not execute control for carbon dioxide capture in situations where there is a high possibility that substances such as salt, yellow sand, and fine particulate matter will adhere to the electrochemical cell 12a. As a result, it is possible to suppress adhesion of substances to the electrochemical cell 12a and suppress deterioration of the carbon dioxide adsorption performance of the electrochemical cell 12a.

[0054] First, the salt damage suppression process for suppressing adhesion of salt contained in the atmosphere to the electrochemical cell 12a will be described with reference to the flowchart of Fig. 4. The salt damage suppression process shown in the flowchart of Fig. 4 can be executed by the control device 17, for example, when the carbon dioxide capture system 10 starts operating, before the carbon dioxide capture system 10 executes the adsorption mode of the series of control sequences, periodically while the series of control sequences are being executed, and / or at a fixed time.

[0055] First, in step S200, the control device 17 acquires information about the installation location of the carbon dioxide capture system 10. As described above, the control device 17 can acquire information about the installation location of the carbon dioxide capture system 10 using the storage unit 18 or the GPS receiver.

[0056] In step S210, the control device 17 determines whether the installation location of the carbon dioxide capture system 10 belongs to a coastal area. Information about coastal areas may be stored in advance by the control device 17, or may be acquired from the external server 21. If the memory unit 18 stores information that the carbon dioxide capture system 10 is installed in a coastal area where salt damage is likely to occur, in step S210, it is determined whether information to that effect is stored. If it is determined that the carbon dioxide capture system 10 is installed in a coastal area, the control device 17 proceeds to the processing of step S220. If it is determined that the carbon dioxide capture system 10 is not installed in a coastal area, there is no need to suppress salt damage, so the control device 17 proceeds to the processing of step S280.

[0057] In step S220, the control device 17 acquires information about the wind direction and wind speed from the detection results of the wind direction and wind speed sensor 20. For example, the control device 17 may acquire information about the wind direction and wind speed by averaging the wind direction and wind speed over a predetermined period. Then, in step S230, the control device 17 determines whether the wind direction is from the sea to the land. In other words, the control device 17 determines whether the wind direction is a direction in which the atmosphere contains a large amount of salt. If it is determined in step S230 that the wind direction is from the sea to the land, the control device 17 proceeds to the processing of step S240. On the other hand, if it is determined that the wind direction is not from the sea to the land, the risk of salt damage occurring is low, and the control device 17 proceeds to the processing of step S280.

[0058] In step S240, the control device 17 determines whether the wind speed is a strong wind equal to or greater than a first reference value. When the wind speed is a strong wind equal to or greater than the first reference value, seawater is stirred up by the wind, and the wind blowing toward the carbon dioxide capture system 10 may contain a large amount of salt. Therefore, if it is determined in step S240 that the wind speed is equal to or greater than the first reference value, the control device 17 proceeds to processing in step S250. In step S250, the control device 17 determines to stop operation of the carbon dioxide capture system 10. As a result, the control device 17 stops execution of the series of control sequences for carbon dioxide capture described above. At this time, the control device 17 closes the flow path on-off valve 11 and / or sets the flow path switching valve 14 to a state in which the piping downstream of the pump 13 communicates with the CO2 capture tank 16, thereby substantially blocking the air introduction path into the capture device 12 and preventing air containing salt from entering the capture device 12.

[0059] On the other hand, if it is determined in step S240 that the wind speed is less than the first reference value, the control device 17 proceeds to the processing of step S260. In step S260, the control device 17 determines whether the wind speed is less than the first reference value and is a slightly strong wind equal to or greater than the second reference value. If the wind speed is less than the first reference value and is a slightly strong wind equal to or greater than the second reference value, the control device 17 proceeds to the processing of step S270. In step S270, the control device 17 determines to operate the carbon dioxide capture system 10 under certain conditions. The condition is that the direction of air introduction into the capture device 12 is opposite to the wind direction from the sea to the land. This makes it possible to prevent air containing a large amount of salt from being introduced into the capture device 12.

[0060] For example, when the opening of the flow path piping connected to the inlet of the collector 12 faces the sea, the control device 17, when executing the adsorption mode of the series of control sequences described above, drives the blower fan of the blower 19 to rotate in the reverse direction so that air is taken in from an outlet opening facing land for discharging air from which carbon dioxide has been removed, and is then discharged to the outside from the opening of the flow path piping connected to the inlet of the collector 12 via the pump 13 and the collector 12, as shown by the dotted arrow in Fig. 5. Alternatively, when the opening of the flow path piping connected to the inlet of the collector 12 faces land, the control device 17, when executing the adsorption mode, drives the blower fan of the blower 19 to rotate in the forward direction so that air is taken in from the opening of the flow path piping connected to the inlet of the collector 12, and is then discharged to the outside from the outlet opening for discharging air from which carbon dioxide has been removed, via the collector 12 and the pump 13, as shown by the dotted arrow in Fig. 3(a).

[0061] On the other hand, if it is determined that the wind speed is less than the first reference value and not a slightly strong wind equal to or greater than the second reference value, that is, the wind speed is weak and less than the second reference value, the risk of salt damage occurring is low, so the control device 17 proceeds to the processing of step S280. In step S280, the control device 17 determines to operate the carbon dioxide capture system 10 normally.

[0062] In this way, the control device 17 determines whether to stop the carbon dioxide capture system 10, operate it conditionally, or operate it normally during salt damage prevention processing. Therefore, in a situation where there is a high possibility that salt will adhere to the electrochemical cell 12a, the control device 17 can prevent the execution of a series of control sequences for capturing carbon dioxide. Furthermore, even when the carbon dioxide capture system 10 is operated in a somewhat strong wind, it is possible to prevent salt from being introduced into the capture device 12 as much as possible. As a result, it is possible to suppress the adhesion of salt to the electrochemical cell 12a and suppress deterioration of the carbon dioxide adsorption performance of the electrochemical cell 12a. Note that in a somewhat strong wind, the carbon dioxide capture system 10 may be stopped rather than operated conditionally.

[0063] Next, a particulate adhesion prevention process for preventing particulates such as yellow sand and fine particulate matter (hereinafter referred to as PM2.5) contained in the atmosphere from adhering to the electrochemical cell 12a will be described with reference to the flowchart of Fig. 6. Similar to the salt damage prevention process, the particulate adhesion prevention process shown in the flowchart of Fig. 6 can be executed by the control device 17, for example, when the carbon dioxide capture system 10 starts operating, before the adsorption mode of the series of control sequences is executed in the carbon dioxide capture system 10, periodically while the series of control sequences is being executed, and / or at a fixed time.

[0064] First, in step S300, the control device 17 acquires information regarding the amount of fine particles (yellow sand and / or PM2.5) contained in the atmosphere. As described above, the control device 17 can acquire information regarding the amount of fine particles in the area where the carbon dioxide capture system 10 is installed by communicating with the external server 21. In step S310, the control device 17 acquires information regarding wind direction and wind speed from the wind direction and wind speed sensor 20.

[0065] Then, in step S320, the control device 17 determines whether the amount of particulate matter contained in the air is equal to or greater than the third reference value, and thus whether the air contains a large amount of particulate matter. If it is determined that the amount of particulate matter is equal to or greater than the third reference value, the control device 17 proceeds to the processing of step S330. In step S330, the control device 17 determines to stop the operation of the carbon dioxide capture system 10. As a result, the control device 17 stops the execution of the series of control sequences for carbon dioxide capture described above. At this time, the control device 17 closes the flow path on-off valve 11 and / or sets the flow path switching valve 14 to a state in which the piping downstream of the pump 13 communicates with the CO2 capture tank 16, thereby substantially blocking the air introduction path into the collector 12 and preventing air containing particulate matter from entering the collector 12.

[0066] On the other hand, if it is determined in step S320 that the amount of particulate matter contained in the atmosphere is less than the third standard value, the control device 17 proceeds to processing in step S340. In step S340, the control device 17 determines whether the amount of particulate matter contained in the atmosphere is less than the third standard value and equal to or greater than the fourth standard value, i.e., whether a slightly large amount of particulate matter is contained in the atmosphere. If the amount of particulate matter is less than the third standard value and equal to or greater than the fourth standard value, the control device 17 proceeds to processing in step S350. On the other hand, if the amount of particulate matter is less than the third standard value but not equal to or greater than the fourth standard value, i.e. ... fourth standard value, the control device 17 proceeds to processing in step S370. In step S370, since the amount of particulate matter contained in the atmosphere is not particularly large, the control device 17 determines to operate the carbon dioxide capture system 10 normally.

[0067] In step S350, the control device 17 determines whether the wind speed is weak and less than a fifth reference value. The fifth reference value may be the same as or different from the second reference value. If the wind speed is weak and less than the fifth reference value, the control device 17 proceeds to the processing of step S360. In step S360, the control device 17 determines to operate the carbon dioxide capture system 10 under certain conditions. The condition is that the direction of air introduction into the capture device 12 is opposite to the wind direction. This makes it possible to prevent air containing a slightly large amount of fine particles from being introduced into the capture device 12. On the other hand, if the wind speed is equal to or greater than the fifth reference value, the control device 17 proceeds to the processing of step S330 and determines to stop the operation of the carbon dioxide capture system 10.

[0068] In this way, the control device 17 determines whether to shut down, conditionally operate, or normally operate the carbon dioxide capture system 10 during the particulate adhesion suppression process. Therefore, in situations where there is a high possibility that particulates such as yellow dust or PM2.5 will adhere to the electrochemical cell 12a, the control device 17 can prevent the execution of a series of control sequences for capturing carbon dioxide. Furthermore, even when the carbon dioxide capture system 10 is operated in situations where the amount of particulates in the atmosphere is somewhat high, by introducing air into the collector 12 from the opposite direction to the wind direction, it is possible to minimize the amount of particulates entering the collector 12. As a result, it is possible to suppress the adhesion of particulates to the electrochemical cell 12a and prevent deterioration of the carbon dioxide adsorption performance of the electrochemical cell 12a. When the amount of particulates in the atmosphere is somewhat high, the carbon dioxide capture system 10 may be shut down rather than operated conditionally.

[0069] The above describes preferred embodiments of the present disclosure, but the present disclosure is not limited to the above-described embodiments and can be implemented in various modifications within the scope of the gist of the present disclosure.

[0070] For example, the above-described embodiment does not mention the number of housings that house the electrochemical cells 12a. The number of housings may be one or more. When multiple housings, each housing an electrochemical cell 12a, are provided, the multiple housings may be connected in parallel to the CO2 capture tank 16. The control device 17 may be configured to be able to execute an individual capture mode in which carbon dioxide is captured individually from each electrochemical cell 12a in the multiple housings, and a simultaneous capture mode in which carbon dioxide is captured simultaneously from each electrochemical cell 12a in at least two or more housings. The simultaneous capture mode may be executed, for example, when the usage time of the carbon dioxide capture system 10 reaches a predetermined time.

[0071] In the above-described embodiment, the storage unit 18 is provided inside the control device 17. However, the storage unit 18 may be provided outside the control device 17. Alternatively, the storage unit 18 may be provided in an external server 21. Furthermore, at least a part of the processing of the control device 17 may be executed by the external server 21.

[0072] Finally, this specification discloses the following technical ideas and their combinations:

[0073] (Technical thought 1) A carbon dioxide recovery system that recovers carbon dioxide from atmospheric air containing carbon dioxide by an electrochemical reaction, an electrochemical cell (12a) disposed within the housing, which adsorbs carbon dioxide and desorbs the adsorbed carbon dioxide in response to an applied electric potential; a recovery unit (11, 12, 13, 14, 16) that recovers carbon dioxide desorbed from the electrochemical cell; a control unit (17) that controls the electrochemical cell and the recovery unit so as to apply an adsorption potential to the electrochemical cell to adsorb carbon dioxide contained in the air introduced into the housing onto the electrochemical cell, and to apply a desorption potential to the electrochemical cell to desorb carbon dioxide from the electrochemical cell and recover it in the recovery unit; an information acquisition unit (S200, S220, S300, S310) that acquires information about substances contained in the atmosphere that may adhere to the electrochemical cell; The control unit is configured to switch at least between executing and not executing control for capturing carbon dioxide based on the information acquired by the information acquisition unit.

[0074] (Technical thought 2) A carbon dioxide recovery system according to Technical Idea 1, wherein the control unit not executing control for recovering carbon dioxide includes blocking the air introduction path into the housing.

[0075] (Technical Thought 3) A carbon dioxide capture system according to Technical Idea 1 or 2, wherein the substances that may adhere to the electrochemical cell include at least one of salt, yellow sand, and fine particulate matter.

[0076] (Technical Thought 4) When the substance that may adhere to the electrochemical cell is salt, the information acquisition unit acquires a location where the carbon dioxide capture system is installed, a wind direction, and a wind speed as information about the substance that may adhere to the electrochemical cell, A carbon dioxide capture system as described in Technical Idea 3, wherein the control unit is configured not to perform control for capturing carbon dioxide when the location where the carbon dioxide capture system is installed is a coastal area, the wind direction is from the sea to the land, and the wind speed is equal to or greater than a first reference value.

[0077] (Technical Thought 5) a blower (19) that blows air into the housing by rotating a fan in the forward direction; the air blowing unit is capable of reversing the flow of air introduced into the housing by rotating the fan in a reverse direction; The carbon dioxide capture system described in Technical Idea 4 is configured such that, when the wind speed is lower than the first reference value and equal to or greater than the second reference value, the control unit controls the blower unit so that the direction of the air flow introduced into the housing is opposite to the wind direction from the sea to the land, while performing control for capturing carbon dioxide.

[0078] (Technical Thought 6) When the substance that may adhere to the electrochemical cell is yellow sand or fine particulate matter, the information acquisition unit acquires information about the amount of yellow sand or fine particulate matter contained in the atmosphere as information about the substance that may adhere to the electrochemical cell, A carbon dioxide capture system described in any one of technical ideas 3 to 5, wherein the control unit is configured not to perform control for carbon dioxide capture when the amount of yellow sand or fine particulate matter contained in the atmosphere is equal to or greater than a third standard value.

[0079] (Technical Thought 7) a blower (19) that blows air into the housing by rotating a fan in the forward direction; the air blowing unit is capable of reversing the flow of air introduced into the housing by rotating the fan in a reverse direction; the information acquisition unit acquires wind direction and wind speed as the information; The carbon dioxide capture system described in Technical Idea 6 is configured so that, when the amount of yellow sand or fine particulate matter contained in the atmosphere is lower than the third standard value but equal to or greater than the fourth standard value, and the wind speed is lower than a fifth standard value, the control unit controls the blower unit while performing control for capturing carbon dioxide so that the direction of the flow of air introduced into the housing is opposite to the acquired wind direction. [Explanation of symbols]

[0080] 10: Carbon dioxide recovery system 10, 11: Flow path opening / closing valve, 12: Recovery device, 12a: Electrochemical cell, 13: Pump, 14: Flow path switching valve, 15: CO2 sensor, 16: CO2 recovery tank, 17: Control device, 18: Memory unit, 19: Fan, 20: Wind direction and wind speed sensor, 21: External server

Claims

1. A carbon dioxide recovery system that recovers carbon dioxide from atmospheric air containing carbon dioxide by an electrochemical reaction, an electrochemical cell (12a) disposed within the housing, which adsorbs carbon dioxide and desorbs the adsorbed carbon dioxide in response to an applied electric potential; a recovery unit (11, 12, 13, 14, 16) that recovers carbon dioxide desorbed from the electrochemical cell; a control unit (17) that controls the electrochemical cell and the recovery unit so as to apply an adsorption potential to the electrochemical cell to adsorb carbon dioxide contained in the air introduced into the housing onto the electrochemical cell, and to apply a desorption potential to the electrochemical cell to desorb carbon dioxide from the electrochemical cell and recover it in the recovery unit; an information acquisition unit (S200, S220, S300, S310) that acquires information about substances contained in the atmosphere that may adhere to the electrochemical cell; The control unit is configured to switch at least between executing and not executing control for capturing carbon dioxide based on the information acquired by the information acquisition unit.

2. The carbon dioxide capture system according to claim 1 , wherein the control unit not executing control for capturing carbon dioxide includes blocking an air introduction path into the housing.

3. The carbon dioxide capture system according to claim 1 or 2, wherein the substances that may adhere to the electrochemical cell include at least one of salt, yellow sand, and fine particulate matter.

4. When the substance that may adhere to the electrochemical cell is salt, the information acquisition unit acquires a location where the carbon dioxide capture system is installed, a wind direction, and a wind speed as information about the substance that may adhere to the electrochemical cell, The carbon dioxide capture system of claim 3, wherein the control unit is configured not to perform control for capturing carbon dioxide when the location where the carbon dioxide capture system is installed is a coastal area, the wind direction is from the sea to the land, and the wind speed is equal to or greater than a first reference value.

5. a blower (19) that blows air into the housing by rotating a fan in the forward direction; the air blowing unit is capable of reversing the flow of air introduced into the housing by rotating the fan in a reverse direction; The carbon dioxide capture system of claim 4, wherein the control unit is configured to perform control for capturing carbon dioxide while controlling the blower unit so that the direction of the flow of air introduced into the housing is opposite to the wind direction from the sea to the land when the wind speed is lower than the first reference value and equal to or greater than the second reference value.

6. When the substance that may adhere to the electrochemical cell is yellow sand or fine particulate matter, the information acquisition unit acquires information about the amount of yellow sand or fine particulate matter contained in the atmosphere as information about the substance that may adhere to the electrochemical cell, The carbon dioxide capture system of claim 3, wherein the control unit is configured not to perform control for capturing carbon dioxide when the amount of yellow sand or fine particulate matter contained in the atmosphere is equal to or greater than a third standard value.

7. a blower (19) that blows air into the housing by rotating a fan in the forward direction; the air blowing unit is capable of reversing the flow of air introduced into the housing by rotating the fan in a reverse direction; the information acquisition unit acquires wind direction and wind speed as the information; The carbon dioxide capture system of claim 6, wherein the control unit is configured to perform control for capturing carbon dioxide while controlling the blower unit so that the direction of the flow of air introduced into the housing is opposite to the acquired wind direction when the amount of yellow sand or fine particulate matter contained in the atmosphere is lower than the third standard value and equal to or greater than the fourth standard value, and the wind speed is lower than a fifth standard value.

Images