Carbon dioxide capture system

Abstract

To provide a carbon dioxide recovery system which can appropriately control application time of an adsorption potential.SOLUTION: A storage part stores a first map and a second map in which a target carbon dioxide adsorption amount and adsorption time for obtaining the target carbon dioxide adsorption amount are associated with each other. The first map and the second map are different in adsorption time associated with the reduced target carbon dioxide adsorption amount. A control device 17 acquires the adsorption time from the first map or the second map, with a correlation value correlated with a recovery amount that is a detection result through a sensor as the target carbon dioxide adsorption amount. The control device 17 holds a current use map, when the recovery amount is in an adsorption amount holding region at Steps S500 and S510. The control device 17 switches the use map, when the recovery amount is outside the adsorption amount holding region at Steps S500 and S520.SELECTED DRAWING: Figure 14

Description

[Technical Field]

[0001] The present disclosure relates to a carbon dioxide capture system that captures carbon dioxide from a gas mixture 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 a carbon dioxide capture system using an electrochemical cell, an adsorption potential is applied to the electrochemical cell to cause the electrochemical cell to adsorb carbon dioxide. Furthermore, in the carbon dioxide capture system, it is desirable to appropriately control the application time of the adsorption potential to achieve a target adsorption amount, which is the amount of adsorption that the electrochemical cell can adsorb, in order to reduce energy loss during adsorption.

[0005] The application time of this adsorption potential can be determined using map data that associates a target adsorption amount with the application time of the corresponding adsorption potential. Furthermore, since it is difficult to directly determine the target adsorption amount, it can be estimated from the amount of carbon dioxide captured. However, in a carbon dioxide capture system that uses map data, the adsorption characteristics of the electrochemical cell are uncertain, so there is a possibility that the application time of the adsorption potential cannot be appropriately controlled.

[0006] The present disclosure has been made in consideration of the above-mentioned points, and aims to provide a carbon dioxide capture system that can appropriately control the application time of the adsorption potential. [Means for solving the problem]

[0007] In order to achieve the above object, the carbon dioxide capture system according to the present disclosure comprises: A carbon dioxide recovery system that recovers carbon dioxide from a mixed gas containing carbon dioxide by an electrochemical reaction, a carbon dioxide capture tank (16) for storing the captured carbon dioxide; a collector (12) having an electrochemical cell including a working electrode containing an adsorbent capable of adsorbing carbon dioxide and a counter electrode paired with the working electrode, and a housing for accommodating the electrochemical cell; a sensor (15) for detecting the amount of carbon dioxide recovered from the recovery device to the carbon dioxide recovery tank; a control device (17) that controls whether to apply a first potential between the working electrode and the counter electrode for an adsorption time corresponding to a target adsorption amount, which is an amount of carbon dioxide adsorbable by the adsorbent, so that the adsorbent adsorbs carbon dioxide when an adsorption mode in which carbon dioxide is adsorbed is performed, or to apply a second potential between the working electrode and the counter electrode for a collection time corresponding to a collection amount, so that the adsorbed carbon dioxide is desorbed by the adsorbent when a collection mode in which carbon dioxide is recovered is performed; a storage unit (18) in which a plurality of adsorption amount change data are stored, each data correlating a target adsorption amount with an adsorption time required to obtain the target adsorption amount; The plurality of pieces of adsorption amount change data are different adsorption times associated with the changed target adsorption amounts, The control device The data on the change in adsorption amount is updated according to the amount of recovery, and The adsorption time is obtained from the adsorption amount change data, using a correlation value that correlates with the recovery amount, which is the detection result via the sensor, as the target adsorption amount, and the data to be used for obtaining the adsorption time is selected from multiple adsorption amount change data depending on the recovery amount.

[0008] According to the carbon dioxide capture system disclosed herein, a plurality of adsorption amount change data, each of which is associated with a target adsorption amount and an adsorption time required to achieve the target adsorption amount, is stored in a storage unit. The plurality of adsorption amount change data have different adsorption times associated with the target adsorption amount. The carbon dioxide capture system then selects data to be used for obtaining the adsorption time from the plurality of adsorption amount change data, depending on the capture amount detected via the sensor. This allows the carbon dioxide capture system to appropriately control the adsorption time, which is the application time of the adsorption potential (first potential).

[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] 3 is a time chart showing the operation of each part when the process shown in the flowchart of FIG. 2 is performed. [Figure 4]FIG. 2 is an explanatory diagram for explaining an adsorption mode, a scavenging mode, and a desorption / recovery mode included in a series of control sequences. [Figure 5] FIG. 4 is a diagram showing an example of adsorption amount change map data. [Figure 6] FIG. 10 is a diagram showing an example of collection amount change map data. [Figure 7] FIG. 7 is an enlarged view of part VII in FIG. 6. [Figure 8] 10 is a flowchart showing a map creation process for creating adsorption amount change map data. [Figure 9] 10A and 10B are explanatory diagrams for explaining an example of a method for estimating the maximum adsorption amount and the maximum adsorption time of an electrochemical cell. [Figure 10] 10 is a flowchart showing a process for setting a target carbon dioxide adsorption amount. [Figure 11] FIG. 10 is a diagram showing the configuration of a carbon dioxide capture system according to a modified example. [Figure 12] 10 is a time chart showing a control sequence of a carbon dioxide capture system according to a modified example. [Figure 13] 10 is a flowchart showing an adsorption time update process according to the second embodiment. [Figure 14] 10 is a flowchart showing a self-learning process according to the second embodiment. [Figure 15] FIG. 10 is a diagram showing a first map and a second map according to a second embodiment. [Figure 16] 10 is a time chart showing processing in a control device according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] A carbon dioxide capture system according to an embodiment of the present disclosure will be described in detail below 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 a mixed gas containing carbon dioxide (e.g., atmospheric gas). The mixed gas from which carbon dioxide has been removed is discharged to the outside (atmosphere). Figure 1 shows the configuration of a carbon dioxide capture system 10 according to this embodiment.

[0013] The carbon dioxide capture system 10 shown in FIG. 1 includes a flow path opening / closing valve 11, a capture device 12, a pump 13, a flow path switching valve 14, a sensor 15, a CO 2 capture tank 16, a control device 17, and a blower 19.

[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, a mixed gas containing carbon dioxide can be introduced into the recovery device 12 through a flow path piping that connects the outside (atmosphere) with the inside of the recovery device 12. On the other hand, when the flow path on-off valve 11 is closed, the flow path piping that connects the outside with the inside of the recovery device 12 is shut off, and the recovery device 12 is sealed from the outside.

[0015] The blower 19 is driven by the control device 17 when the flow path on-off valve 11 is open, and sends the mixed gas containing carbon dioxide into the recovery device 12 through a flow path piping that connects the outside with the inside of the recovery device 12. However, the blower 19 may be omitted. Alternatively, the pump 13 may also serve as the blower 19. In other words, when the flow path on-off valve 11 is open, the pump 13 may be driven to draw the mixed gas containing carbon dioxide into the recovery device 12 from the outside through the above-mentioned flow path piping.

[0016] The collector 12 includes an electrochemical cell disposed inside a housing made of, for example, a metal. The electrochemical cell is capable of adsorbing carbon dioxide through an electrochemical reaction to separate the carbon dioxide from the mixed gas, 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 a mixed gas containing carbon dioxide from the outside into the housing of the collector 12. The other opening is an outlet for discharging the mixed gas from which the carbon dioxide has been removed and the carbon dioxide desorbed from the electrochemical cell. A flow path piping connecting the outside and the inside of the collector 12 is connected to the inlet, and a flow path piping equipped 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 are stacked and arranged inside the housing of the recovery vessel 12. The stacking direction of the plurality of electrochemical cells is perpendicular to the flow direction of the mixed gas. Each electrochemical cell 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. The gap provided between adjacent electrochemical cells becomes a gas flow path through which the mixed gas flows.

[0018] Each electrochemical cell 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 order listed. 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 provided to the working electrode to cause carbon dioxide to be adsorbed by the carbon dioxide adsorbent of the working electrode, or electrons can be released from the working electrode to desorb the adsorbed carbon dioxide. The carbon dioxide adsorbent corresponds to the adsorbent.

[0019] The working electrode current collecting layer is made of a porous conductive material having pores through which a mixed gas containing carbon dioxide can pass. The working electrode current collecting layer only needs to be gas permeable and conductive, and examples of materials that can be used to form the working electrode current collecting layer include metal materials and carbonaceous materials.

[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 includes 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 pressure.

[0024] The pump 13 sucks the residual mixed gas remaining in the collector 12 from the collector 12 and releases it to the outside (i.e., scavenges the residual mixed gas in the collector 12), and when the carbon dioxide adsorbed by the carbon dioxide adsorbent is desorbed, the pump 13 sucks the desorbed carbon dioxide from the collector 12 and discharges it toward the CO2 capture tank 16. When the pump 13 scavenges the residual mixed gas in the collector 12, the flow path open / close valve 11 blocks the flow path piping that connects the outside with the inside of the collector 12. Therefore, scavenging of the residual mixed gas in the collector 12 is performed by drawing a vacuum with the pump 13. Furthermore, the subsequent discharge of carbon dioxide into the CO2 capture tank 16 is also performed 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 flowing through the piping downstream of the pump 13. The flow path switching of the flow path switching valve 14 is controlled by the control device 17. Specifically, when a mixed gas containing carbon dioxide is introduced into the collector 12 and when the pump 13 scavenges the remaining mixed gas in the collector 12, the control device 17 controls the flow path switching valve 14 to communicate the piping downstream of the pump 13 with the outside (atmosphere). As a result, the mixed gas from which carbon dioxide has been removed and the remaining mixed gas in the collector 12 are released to the outside. On the other hand, when the carbon dioxide adsorbent desorbs carbon dioxide, the control device 17 controls the flow path opening / closing valve 11 to communicate the piping downstream of the pump 13 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 stored in the CO2 capture tank 16.

[0026] The 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 sensor 15. This amount of carbon dioxide captured corresponds to the detection result via the sensor. The amount of carbon dioxide captured may also be calculated by the sensor 15. In this case, the sensor 15 outputs the amount of carbon dioxide captured to the control device 17. The amount of carbon dioxide captured can also be said to be a carbon dioxide monitor value. The amount of carbon dioxide captured corresponds to the amount of carbon dioxide captured.

[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 memory unit 18 having a storage medium. This memory unit 18 stores adsorption amount change map data and recovery amount change map data. The adsorption amount change map data corresponds to the adsorption amount change data. The recovery amount change map data corresponds to the recovery amount change data. The adsorption amount change map data associates the adsorption time with the target carbon dioxide adsorption amount, as shown in Figure 5. The recovery amount change map data associates the change in the carbon dioxide recovery amount with the target carbon dioxide adsorption amount, as shown in Figures 6 and 7. The target carbon dioxide adsorption amount is also referred to as the maximum adsorption amount. The adsorption time is also referred to as the adsorption mode execution time. The adsorption amount change map data and the recovery amount change map data will be explained in detail later.

[0028] The control device 17 performs various arithmetic processing based on a control program stored in a storage medium such as a ROM, and controls the operation of various controlled 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. The control device 17 of this embodiment controls the operation of various controlled devices so that a series of control sequences for carbon dioxide recovery, including at least an adsorption mode and a desorption / capture mode, are executed in the carbon dioxide recovery system 10. Note that the control sequence may also include a scavenging mode in addition to the above. The desorption / capture mode indicates that the desorption mode and the capture mode are combined into one mode.

[0029] Below, we will explain a series of control sequences for capturing carbon dioxide, which are executed in the carbon dioxide capture system 10 and include at least an adsorption mode, a scavenging mode, and a desorption / capture mode. Fig. 2 is a flowchart showing the processing performed by the control device 17 to execute the control sequence. Fig. 3 is a time chart showing the operation of each part when the processing shown in the flowchart of Fig. 2 is executed. Fig. 4 is an explanatory diagram for explaining the adsorption mode, the scavenging mode, and the desorption / capture mode included in the series of control sequences. The desorption / capture mode indicates that the desorption mode and the capture mode are combined into one mode.

[0030] As shown in the flowchart of FIG. 2, the control device 17 first starts the adsorption mode, which is the first operating mode of the control sequence, in step S100. In this adsorption mode, as shown in FIG. 3, the flow path on-off valve 11 is opened to allow the mixed gas containing carbon dioxide to be introduced into the recovery device 12. If a blower 19 is provided, the blower 19 is driven to introduce a larger amount of mixed gas into the recovery device 12. If the pump 13 also serves as the blower 19, the pump 13 is driven to suck the mixed gas and draw the mixed gas from the outside into the recovery device 12. In this case, the pump 13 is driven simply to suck the mixed gas from the outside, and therefore the energy required for this suction is less than the energy required for driving the pump for vacuum generation in the scavenging mode or desorption / recovery mode, which will be described later.

[0031] In the adsorption mode, an adsorption potential (corresponding to a first potential) that enables the carbon dioxide adsorbent of the working electrode to adsorb carbon dioxide is applied between the working electrode and the counter electrode of the electrochemical cell of the recovery vessel 12, as shown in Fig. 3. Furthermore, in the adsorption mode, the flow path switching valve 14 is controlled to connect the piping downstream of the pump 13 to the outside, as shown in Fig. 3.

[0032] In the adsorption mode, by controlling the flow path on-off valve 11, the electrochemical cells of the recovery device 12, the flow path switching valve 14, and the like, a mixed gas (atmospheric gas) containing carbon dioxide passes through the flow path on-off valve 11 and enters the recovery device 12, as shown by the dotted arrow in Fig. 4(a). The mixed gas that has entered the recovery device 12 is adsorbed by the multiple electrochemical cells, thereby removing the carbon dioxide from the mixed gas. The mixed gas from which the carbon dioxide has been removed passes through the pump 13 and 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.

[0033] In step S110 of the flowchart in FIG. 2, the control device 17 determines whether the adsorption mode execution time has elapsed. The adsorption mode execution time is not constant but varies for reasons such as estimating the maximum adsorption amount of the electrochemical cell in the map creation process described below and the maximum adsorption amount time, which is the adsorption mode execution time required to obtain that maximum adsorption amount, and optimizing the amount of carbon dioxide captured and energy consumption when the carbon dioxide adsorption performance of the electrochemical cell changes due to environmental changes or aging. This varying adsorption mode execution time is set by the control device 17. In step S110, it is determined whether the set adsorption mode execution time has elapsed. In this embodiment, the maximum adsorption amount is used as the target carbon dioxide adsorption amount. Therefore, hereinafter, the maximum adsorption amount will also be referred to as the target carbon dioxide adsorption amount. The maximum adsorption amount corresponds to the target adsorption amount.

[0034] 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.

[0035] In step S120, adsorption mode termination processing is executed. Specifically, the control device 17 closes the flow path on-off valve 11 to block the mixed gas flowing into the recovery device 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.

[0036] In this way, when the adsorption mode in which carbon dioxide adsorption is performed is executed, the control device 17 applies the adsorption potential so that the carbon dioxide adsorbent adsorbs carbon dioxide. The control device 17 applies the adsorption potential only during the adsorption mode execution time corresponding to the target carbon dioxide adsorption amount.

[0037] The adsorption mode execution time can be obtained from the adsorption amount change map data. The target carbon dioxide adsorption amount can be obtained from the recovery amount change map data. The control device 17 obtains the target carbon dioxide adsorption amount associated with the carbon dioxide recovery amount detected via the sensor 15 from the recovery amount change map data. As shown in Figure 7, the target carbon dioxide adsorption amount in the recovery amount change map data is a correlation value correlated with the carbon dioxide recovery amount detected via the sensor 15. Therefore, it can be said that the control device 17 obtains the correlation value correlated with the carbon dioxide recovery amount detected via the sensor 15 as the target carbon dioxide adsorption amount.

[0038] Then, the control device 17 acquires the adsorption mode execution time associated with the target carbon dioxide adsorption amount from the adsorption amount change map data. In the example of Fig. 5, if the target carbon dioxide adsorption amount is set to 80 [g], the adsorption mode execution time is 80 [s].

[0039] As shown in Fig. 6, the target carbon dioxide adsorption amount is updated according to the amount of carbon dioxide recovered detected via sensor 15. Furthermore, as shown in Fig. 5, the adsorption mode execution time changes each time the target carbon dioxide adsorption amount is updated. The target carbon dioxide adsorption amount may be stored in storage unit 18 or the like as an initial calculation threshold or an update threshold.

[0040] 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, 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 of the recovery device 12 is maintained. The flow path switching valve 14 also maintains communication between the piping downstream of the pump 13 and the outside.

[0041] In the scavenging mode, as shown in Fig. 3, 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 upstream of the pump 13. When the pump 13 is driven in this state, the residual mixed gas from which carbon dioxide has been removed and left in the sealed collector 12 is sucked out of the collector 12 and released to the outside. This allows the residual mixed gas in the collector 12 to be scavenged. In the scavenging mode, an adsorption potential is applied.

[0042] Since the recovery vessel 12 upstream of the pump 13 is sealed, the scavenging of the remaining mixed gas in the recovery vessel 12 is performed by vacuuming with the pump 13. For this reason, for example, when the pump 13 also serves as the blower 19, the driving of the pump 13 continues, but the driving output is increased compared to the suction mode when the scavenging mode starts.

[0043] By controlling the flow path opening / closing valve 11, the electrochemical cell 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 Figure 4(b), the residual mixed gas from which carbon dioxide has been removed in the recovery device 12 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.

[0044] 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 mixed gas in the recovery device 12.

[0045] 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.

[0046] In step S150, a scavenging mode ending process is executed. Specifically, the control device 17 resets the count value of a counter that counts the scavenging mode execution time.

[0047] 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. Furthermore, the pump 13 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 electrochemical cell in a state closer to a vacuum than the atmosphere.

[0048] Meanwhile, a desorption potential (corresponding to a second potential) that causes electrons to be emitted from the working electrode and enables the carbon dioxide adsorbed by the carbon dioxide adsorbent of the working electrode to be desorbed is applied between the working electrode and the counter electrode of the electrochemical cell of the recovery device 12. Furthermore, in the desorption / recovery mode, as shown in Fig. 3, the flow path switching valve 14 is controlled to connect the piping downstream of the pump 13 to the CO2 recovery tank 16.

[0049] By controlling the flow path on-off valve 11, the electrochemical cell of the recovery device 12, the pump 13, and the flow path switching valve 14 in this manner, in the desorption / capture mode, as shown by the dotted arrow in FIG. 4(c), carbon dioxide desorbed from the electrochemical cell passes through the pump 13 and is guided by the flow path switching valve 14 to the flow path piping toward the CO2 capture tank 16, and is accumulated in the CO2 capture tank 16 via the flow path piping. 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 sensor 15. Based on the detection result of the 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 15 capable of detecting the flow rate of carbon dioxide may be used.

[0050] In addition, instead of simultaneously performing carbon dioxide desorption and capture in the desorption and capture mode, carbon dioxide desorption from the electrochemical cell 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 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 operation of 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 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, and carbon dioxide continues to be desorbed from the electrochemical cell.

[0051] In step S170 of the flowchart in FIG. 2, the control device 17 determines whether the desorption / capture mode execution time or the capture mode execution time (hereinafter referred to as the capture mode execution time) has elapsed. The capture mode execution time is not constant but varies for reasons such as optimizing the amount of carbon dioxide captured and energy consumption when the carbon dioxide adsorption performance of the electrochemical cell changes due to environmental changes or aging degradation. This variable capture mode execution time is set by the control device 17. In step S170, it is determined whether the set capture mode execution time has elapsed.

[0052] If it is determined in the determination process of step S170 that the set capture mode execution time has elapsed, the process proceeds to step S180. On the other hand, if it is determined that the set capture mode execution time has not elapsed, the determination process of step S170 is repeatedly executed until the capture mode execution time has elapsed. In this way, when the capture mode in which carbon dioxide is captured is executed, the control device 17 applies a desorption potential so that the carbon dioxide adsorbent desorbs the adsorbed carbon dioxide. Then, the control device 17 applies the desorption potential only during the capture mode execution time corresponding to the target carbon dioxide adsorption amount. The capture mode execution time corresponds to the capture time.

[0053] 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. The control device 17 stops applying the desorption potential to the electrochemical cell. The control device 17 stops driving the pump 13. The control device 17 switches the flow path switching valve 14 to connect the piping downstream of the pump 13 to the outside. Furthermore, the control device 17 also resets the count value of a counter that counts the recovery mode execution time.

[0054] The carbon dioxide adsorption performance of the electrochemical cell is thought to change due to aging and other factors. However, it is not possible to directly detect the upper limit of the amount of carbon dioxide that an electrochemical cell can adsorb. Therefore, it cannot be denied that the adsorption mode may continue even though the amount of carbon dioxide adsorbed by the electrochemical cell has reached its upper limit, or that the capture mode may continue even though the capture of carbon dioxide desorbed from the electrochemical cell has essentially ended.

[0055] Thus, if an attempt is made to maximize the amount of carbon dioxide captured by, for example, always running the adsorption mode for a time sufficient to allow the electrochemical cell to adsorb the maximum amount of carbon dioxide it can adsorb, and running the capture mode for a time sufficient to capture all of the carbon dioxide adsorbed by the electrochemical cell, the carbon dioxide capture system 10 may end up consuming excessive energy relative to the amount of carbon dioxide captured.

[0056] Therefore, in the carbon dioxide capture system 10 according to this embodiment, the storage unit 18 of the control device 17 has a configuration in which adsorption amount change map data and capture amount change map data are stored.

[0057] The adsorption amount change map data and the recovery amount change map data will be described in detail below. First, the map creation process for creating the adsorption amount change map data will be described based on the flowcharts of FIGS.

[0058] When performing the map creation process, the control device 17 executes the adsorption mode multiple times at different adsorption mode execution times (elapsed time), and detects the amount of carbon dioxide captured in the multiple capture modes executed corresponding to each adsorption mode via the sensor 15. For example, Fig. 3 shows an example in which the adsorption mode is executed three times at different adsorption mode execution times. Note that the number of executions of the multiple adsorption modes may be two.

[0059] 3, the execution time of the first adsorption mode is set to be relatively short so that the amount of carbon dioxide adsorbed by the electrochemical cell does not reach the upper limit. Therefore, the amount of carbon dioxide recovered detected when the capture mode corresponding to the first adsorption mode is executed is an amount less than the upper limit of the amount of carbon dioxide adsorbed by the electrochemical cell.

[0060] The execution time of the second adsorption mode is relatively long and is set so that the amount of carbon dioxide adsorbed by the electrochemical cell reaches almost the upper limit. Therefore, the amount of carbon dioxide captured when the capture mode corresponding to the second adsorption mode is executed is almost equal to the upper limit of the amount of carbon dioxide adsorbed by the electrochemical cell.

[0061] The third adsorption mode is executed for the longest time, and is set to continue for a certain period of time even after the amount of carbon dioxide adsorbed by the electrochemical cell reaches its upper limit. Therefore, the amount of carbon dioxide captured when the capture mode corresponding to the third adsorption mode is executed is equal to the upper limit of the amount of carbon dioxide adsorbed by the electrochemical cell.

[0062] Based on the sensor detection results obtained while the adsorption mode is performed multiple times and the recovery mode is performed multiple times corresponding to each adsorption mode, the maximum adsorption amount of the electrochemical cell and the maximum adsorption time, which is the adsorption mode execution time required to achieve that maximum adsorption amount, are estimated. A specific example of a method for estimating the maximum adsorption amount and the maximum adsorption time of the electrochemical cell will be described with reference to Figures 7(a), (b), and (c).

[0063] In step S200, it is determined whether or not the map creation determination conditions are met. The control device 17 determines that it is possible to plot the carbon dioxide capture amounts in the three capture modes for one piece of adsorption amount change map data, and that there are maximum values ​​of the carbon dioxide capture amounts that are not plotted on the same straight line. Note that the same straight line may include a tolerance. If the control device 17 determines that the map creation determination conditions are met, it proceeds to step S210, and if it determines that the conditions are not met, it proceeds to step S240.

[0064] In step S240, a retry is performed. The control device 17 executes the adsorption mode again and detects the amount of carbon dioxide captured in the capture mode executed in response to the adsorption mode via the sensor 15. At this time, the control device 17 sets the execution time of the adsorption mode to be longer than the previous time (third time).

[0065] Then, the control device 17 performs S200 using the amount of carbon dioxide recovered obtained in the retry. The control device 17 repeatedly executes steps S200 and S240 until a YES determination is made in step S200. When step S240 is executed, the control device 17 adopts the amount of carbon dioxide recovered during the retry as the target carbon dioxide adsorption amount in step S220.

[0066] In step S210, the slope is calculated. FIG. 7(a) is a graph showing the amount of carbon dioxide adsorbed by the electrochemical cell based on the amount of carbon dioxide captured when a capture mode corresponding to the first adsorption mode is executed, and the execution time of the first adsorption mode. The amount of carbon dioxide adsorbed by the electrochemical cell can be considered to be equal to the detected amount of carbon dioxide captured. As described above, the execution time of the first adsorption mode is set to be relatively short so that the amount of carbon dioxide adsorbed by the electrochemical cell does not reach its upper limit. Therefore, as shown in FIG. 7(a), based on the amount of carbon dioxide adsorbed by the electrochemical cell during the first execution of the adsorption mode, it is possible to determine an increase gradient line (slope) by assuming that the longer the execution time of the adsorption mode, the more linearly the amount of carbon dioxide adsorbed.

[0067] In step S220, a target carbon dioxide adsorption capacity is calculated. Figure 7(b) is a graph showing the carbon dioxide adsorption capacity of each electrochemical cell based on the carbon dioxide capture capacity detected when the capture modes corresponding to the second and third adsorption modes are executed, and the execution time of the second and third adsorption modes. As described above, the execution time of the second adsorption mode is relatively long and is set so that the carbon dioxide adsorption capacity of the electrochemical cell reaches almost its upper limit. The execution time of the third adsorption mode is the longest and is set so that the adsorption mode is executed for a certain period of time even after the carbon dioxide adsorption capacity of the electrochemical cell reaches its upper limit. Therefore, as shown in Figure 7(b), an upper limit line for the carbon dioxide adsorption capacity of the electrochemical cell can be determined based on the carbon dioxide adsorption capacity of the electrochemical cell after the second and third adsorption modes are executed. The carbon dioxide adsorption capacity corresponding to the upper limit line is the target carbon dioxide adsorption capacity, which is the maximum adsorption capacity that can be adsorbed.

[0068] The upper limit of the carbon dioxide adsorption amount of the electrochemical cell may be determined based on the carbon dioxide adsorption amount of the electrochemical cell obtained through one execution of the adsorption mode and the recovery mode corresponding to that one execution of the adsorption mode.

[0069] In step S230, as shown in FIG. 7(c), the adsorption time, which is the maximum adsorption amount time, which is the adsorption mode execution time for obtaining the maximum adsorption amount, can be determined from the intersection of the increasing gradient line in FIG. 7(a) and the upper limit line in FIG. 7(b).

[0070] In this way, the control device 17 estimates the maximum adsorption amount of the electrochemical cell as the target carbon dioxide adsorption amount based on the amount of carbon dioxide captured as a result of detection in multiple capture modes, and creates adsorption amount change map data by estimating the adsorption time required to achieve the maximum adsorption amount. The control device 17 then stores the created adsorption amount change map data in the storage unit 18. The adsorption amount change map data is updated based on the target carbon dioxide adsorption amount and the adsorption time due to factors such as aging of the electrochemical cell.

[0071] Next, the process of setting the target carbon dioxide adsorption amount in the recovery amount change map data will be described with reference to the flowchart in Fig. 10. By executing the flowchart in Fig. 10, the control device 17 determines whether to maintain the current value of the target carbon dioxide adsorption amount or to update it.

[0072] 6 and 7, the recovery amount change map data associates a different target carbon dioxide adsorption amount with each of the multiple control sequence cycles. Here, an example is used in which the target carbon dioxide adsorption amount is updated every 10 cycles. Furthermore, the recovery amount change map data associates the carbon dioxide recovery amount (carbon dioxide monitor value) detected via sensor 15 with the target carbon dioxide adsorption amount.

[0073] The initial calculation threshold is the initial target carbon dioxide adsorption amount used from cycle 1 to cycle 10. The update threshold is the updated target carbon dioxide adsorption amount. The update threshold is the target carbon dioxide adsorption amount assumed due to aging of the electrochemical cell, etc. Therefore, the update threshold is a value smaller than the initial calculation threshold. Furthermore, the update threshold becomes smaller as the number of cycles increases.

[0074] The area between the initial calculation threshold and the update threshold, and the area between the update threshold and the next update threshold, are adsorption amount holding areas. The adsorption amount holding area is an area where the current target carbon dioxide adsorption amount is held. On the other hand, the area outside the adsorption amount holding area is an adsorption amount update area. The adsorption amount update area is an area where the target carbon dioxide adsorption amount is updated from the current value.

[0075] In step S300, it is determined whether the recovery amount is within the adsorption amount holding region. The control device 17 determines whether the carbon dioxide monitor value as the recovery amount is within the adsorption amount holding region. If the control device 17 determines that the carbon dioxide monitor value is within the adsorption amount holding region, the process proceeds to step S310, and if it determines that the carbon dioxide monitor value is not within the adsorption amount holding region, the process proceeds to step S320.

[0076] In step S310, the target carbon dioxide adsorption amount is maintained. The control device 17 maintains the current target carbon dioxide adsorption amount. In the case of the carbon dioxide monitor value shown by dot hatching in Fig. 7, the control device 17 maintains the current target carbon dioxide adsorption amount.

[0077] In step S320, the target carbon dioxide adsorption amount is updated. The control device 17 updates the current target carbon dioxide adsorption amount to a new target carbon dioxide adsorption amount. In the case of a carbon dioxide monitor value shown by diagonal hatching in Figure 7, the control device 17 updates the target carbon dioxide adsorption amount.

[0078] In step S330, the target carbon dioxide adsorption amount is set. The control device 17 sets the current target carbon dioxide adsorption amount or the updated target carbon dioxide adsorption amount as the target carbon dioxide adsorption amount when setting the adsorption mode execution time. In this way, the control device 17 sets the target carbon dioxide adsorption amount from the carbon dioxide recovery amount.

[0079] As described above, the carbon dioxide capture system 10 includes the control device 17 that detects, via the sensor 15, the amount of carbon dioxide captured from the capture device 12 to the CO2 capture tank 16. The control device 17 then acquires, as a target carbon dioxide adsorption amount, a correlation value that correlates with the carbon dioxide capture amount, which is the detection result via the sensor 15. Thus, the carbon dioxide capture system 10 can grasp the target carbon dioxide adsorption amount.

[0080] Furthermore, the control device 17 executes the adsorption mode multiple times and determines the target carbon dioxide adsorption amount using adsorption amount change map data created using the carbon dioxide recovery amount detected via the sensor 15 in the multiple recovery modes executed corresponding to each adsorption mode. The control device 17 then applies the adsorption potential only during the adsorption mode execution time obtained from the adsorption amount change map data. This allows the control device 17 to apply the adsorption potential only for the time required to obtain the maximum adsorption amount. In other words, the control device 17 can prevent the application of the adsorption potential for a time longer than the time required to obtain the maximum adsorption amount. This allows the control device 17 to appropriately control the application time of the adsorption potential to obtain the maximum adsorption amount.

[0081] Furthermore, the control device 17 updates the adsorption amount change map data in accordance with the amount of carbon dioxide recovered detected via the sensor 15. Therefore, even if the electrochemical cell deteriorates over time, the control device 17 can grasp the optimum target carbon dioxide adsorption amount and appropriately control the application time of the adsorption potential.

[0082] Although the preferred embodiments of the present disclosure have been described above, the present disclosure is not limited to the above embodiments and can be implemented with various modifications within the scope of the gist of the present disclosure. For example, the configuration of the above embodiments may be modified as follows.

[0083] (Variation 1) The adsorption mode execution time is not limited to that obtained from the adsorption amount change map data. The adsorption mode execution time can also be obtained by calculating a predetermined relational expression. The control device 17 may obtain the adsorption mode execution time by multiplying the amount of carbon dioxide recovered [g] detected via the sensor 15 by the carbon dioxide adsorption coefficient [s / g].

[0084] The carbon dioxide adsorption coefficient is a coefficient indicated by the time required for the carbon dioxide adsorbent to adsorb a predetermined amount of carbon dioxide. In other words, the carbon dioxide adsorption coefficient is defined as the time required to adsorb 1 [g] of carbon dioxide. The carbon dioxide adsorption coefficient [s / g] is the adsorption time [s] / the amount of carbon dioxide adsorbed [g]. Modification 1 can achieve the same effects as the above embodiment.

[0085] (Variation 2) 11, the carbon dioxide capture system 10 may include a plurality of capturers 12a to 12c, which may be connected in parallel to the CO2 capture tank 13. In other words, the carbon dioxide capture system 10 may include a plurality of subsystems 10a to 10c. Each of the subsystems 10a to 10c includes one capturer 12a to 12c.

[0086] Subsystem 10a includes a collector 12a, a flow path opening / closing valve 11a, and a switching valve 20a. Subsystem 10b includes a collector 12b, a flow path opening / closing valve 11b, and a switching valve 20b. Subsystem 10c includes a collector 12c, a flow path opening / closing valve 11c, and a switching valve 20c. Note that, here, an example including three subsystems 10a to 10c is used. However, the carbon dioxide capture system 10 may include two subsystems or four or more subsystems.

[0087] The control device 17 can operate in an individual capture mode in which carbon dioxide is captured individually from each electrochemical cell of the multiple capturers 12a to 12c, and in a simultaneous capture mode in which carbon dioxide is captured simultaneously from each electrochemical cell of at least two or more capturers.

[0088] 12, in the individual capture mode, the control device 17 starts a series of control sequences including an adsorption mode and a capture mode for each electrochemical cell of each of the capturers 12a to 12c at different times. Timing t0 is, for example, the start timing of the carbon dioxide capture system 10. The control device 17 starts the control sequence in subsystem 10a at timing t0. The control device 17 starts the control sequence in subsystem 10b at timing t1, a predetermined time after timing t0. The control device 17 starts the control sequence in subsystem 10c at timing t2, a predetermined time after timing t1.

[0089] For this reason, in the individual capture mode, a delay time occurs during which each of the subsystems 10a to 10c does not execute a control sequence. In subsystem 10b, the delay time is the period from timing t0 to t1. In subsystem 10c, the delay time is the period from timing t1 to t2. The delay time corresponds to a period during which the control sequence is not executed. Therefore, the control device 17 executes the adsorption mode and capture mode to estimate the maximum adsorption amount during the delay time. This allows the carbon dioxide capture system 10 to make effective use of the delay time.

[0090] On the other hand, in the simultaneous collection mode, the control device 17 simultaneously starts a series of control sequences including an adsorption mode and a collection mode for each electrochemical cell of each of the collection devices 12a to 12c. The control sequences for the subsystems 10a to 10c are simultaneously started, for example, at timing t0. Therefore, no delay time occurs in the simultaneous collection mode.

[0091] The control device 17 may also switch between the individual collection mode and the simultaneous collection mode depending on the situation. The control device 17 switches between modes for the purpose of shortening the time required to create the adsorption amount change map data.

[0092] Examples of situations include the initial operation of the carbon dioxide capture system 10 (when the equipment is installed), periodic state transitions of the carbon dioxide capture system 10 from a dormant state to an operational state, regular maintenance, recovery from a failure of the carbon dioxide capture system 10, and recovery from an abnormality in the external environment of the carbon dioxide capture system 10. Furthermore, the regular maintenance may involve situations where no electrochemical cells are replaced, where some electrochemical cells are replaced, or where all electrochemical cells are replaced. An abnormality in the external environment may involve a power outage, etc.

[0093] The control device 17 executes the individual recovery mode when the equipment is installed or when the equipment is restored from a fault, and executes the simultaneous recovery mode when the equipment is transitioning from a dormant state to an operating state or when the equipment is restored from an abnormal external environment. The control device 17 also executes the simultaneous recovery mode when no electrochemical cells are replaced or when some of the electrochemical cells are replaced, and the individual recovery mode when all of the electrochemical cells are replaced.

[0094] Furthermore, in the individual collection mode, the control device 17 may use common adsorption amount change map data for the subsystems 10a to 10c, whereas in the simultaneous collection mode, the control device 17 may use individual adsorption amount change map data for each of the subsystems 10a to 10c.

[0095] The carbon dioxide capture system 10 may be configured to be able to execute only one of the individual capture mode and the simultaneous capture mode.

[0096] (Second embodiment) A carbon dioxide capture system 10 of the second embodiment will be described using Figures 13 to 16. Here, differences from the above-mentioned embodiment will be described. The carbon dioxide capture system 10 of the second embodiment differs from the above-mentioned embodiment mainly in that a plurality of adsorption amount change map data is stored in the memory unit 18, and these are switched (selected). The carbon dioxide capture system 10 of the second embodiment has the same components as the above-mentioned embodiment, and is configured to be able to execute the processing described in the above-mentioned embodiment. In other words, the carbon dioxide capture system 10 of the second embodiment can be implemented in combination with the above-mentioned embodiment. Note that Figure 16 shows a time chart illustrating a normal operating state after the map creation processing of Figure 3 has been completed. The normal operating state is a state in which carbon dioxide is actually captured.

[0097] As shown in FIG. 15, the memory unit 18 stores a first map and a second map as adsorption amount change map data. The first map is similar to the adsorption amount change map data of the above embodiment. That is, in the first map, the slope of the increasing gradient line does not change. Therefore, in the first map, the adsorption time (adsorption mode execution time) shortens as the target carbon dioxide adsorption amount decreases. On the other hand, unlike the first map, the slope of the increasing gradient line changes in the second map. Therefore, in the second map, the adsorption time is constant regardless of the decrease in the target carbon dioxide adsorption amount. In this way, the first map and the second map have different adsorption times associated with the same target carbon dioxide adsorption amount. It can also be said that the first map and the second map have different adsorption times associated with a decreased target carbon dioxide adsorption amount. The first map corresponds to the first adsorption amount change data. On the other hand, the second map corresponds to the second adsorption amount change data.

[0098] As shown in Fig. 16, the control device 17 switches (selects) the map in use used to acquire the adsorption time between the first map and the second map. The control device 17 then stores information indicating the map in use currently. The control device 17 stores either map in use information indicating that the first map is currently being used or map in use information indicating that the second map is currently being used as the information indicating the map in use. In other words, the control device 17 updates the information indicating the map in use every time the map in use is switched. The map in use corresponds to the use data.

[0099] The control device 17 uses the first map in the control sequence from timing t10 ​​to t12. Therefore, used map information indicating that the first map is being used is stored. Then, the control device 17 switches from the first map to the second map at timing t13. Therefore, the information indicating the used map is updated to used map information indicating that the second map is being used. Note that there are no particular limitations on the method or destination for storing the used map information. Furthermore, the method for switching (selecting) the used map will be explained later.

[0100] Furthermore, as shown in FIG. 16, the control device 17 determines and updates the target carbon dioxide adsorption amount for each cycle (timings t10 to t13) of the control sequence. The control device 17 then stores an update determination result indicating whether the target carbon dioxide adsorption amount has been updated. The control device 17 stores either information indicating that an update has not been performed or information indicating that an update has been performed as the update determination result. In other words, the control device 17 updates the update determination result each time the target carbon dioxide adsorption amount is updated. The control device 17 did not update the target carbon dioxide adsorption amount at times t10, t11, and t13, and stores information indicating that an update has not been performed. On the other hand, the control device 17 updated the target carbon dioxide adsorption amount at time t12, and stores information indicating that an update has been performed. In other words, in FIG. 16, the carbon dioxide monitor value deviated from the adsorption amount holding region at time t12, so the target carbon dioxide adsorption amount was updated.

[0101] The method and destination for storing the update determination result are not particularly limited. Furthermore, it is sufficient for the control device 17 to know whether the timing at which the carbon dioxide capture amount is detected is the first detection timing after the target carbon dioxide adsorption amount is updated. Therefore, the control device 17 may store information indicating that an update will be performed when the target carbon dioxide adsorption amount is updated, and erase the information indicating that an update will be performed if the target carbon dioxide adsorption amount is not updated in the next control sequence. The first detection timing can also be said to be the first time the carbon dioxide capture amount is obtained.

[0102] As described above, the control device 17 acquires the adsorption time from the adsorption amount change map data in accordance with the target carbon dioxide adsorption. Therefore, the control device 17 may update the adsorption time. The control device 17 then stores an adsorption time update result indicating whether the adsorption time has been updated. The control device 17 stores either information indicating that the adsorption time has not been updated or information indicating that the adsorption time has been updated as the adsorption time update result. In other words, the control device 17 updates the adsorption time update result every time the adsorption time is updated. The control device 17 did not update the adsorption time at times t10, t11, and t13, and stores information indicating that the adsorption time has not been updated. On the other hand, the control device 17 updated the adsorption time at time t12, and stores information indicating that the adsorption time has been updated.

[0103] The method and destination of storing the adsorption time update result are not particularly limited. Furthermore, the control device 17 may store information indicating the adsorption time update when the adsorption time is updated, and may erase the information indicating the adsorption time update if the adsorption time is not updated in the next control sequence.

[0104] The adsorption time update process will now be described with reference to Fig. 13. After updating the target carbon dioxide adsorption amount in step S320, the control device 17 starts the process shown in the flowchart of Fig. 13 .

[0105] In step S400, it is determined whether the second map is currently being used. The control device 17 determines whether the second map is currently being used based on the map-in-use information. If the control device 17 determines that the second map is currently being used, the process proceeds to step S410, and if the control device 17 determines that the second map is not currently being used, the process proceeds to step S420.

[0106] In step S410, the current adsorption time is maintained. When the second map is used, the control device 17 does not update the adsorption time even if the target carbon dioxide adsorption amount is updated.

[0107] In step S420, the adsorption time is calculated. When the first map is used, the control device 17 updates the adsorption time in accordance with the update of the target carbon dioxide adsorption amount. That is, the control device 17 uses the first map to obtain the adsorption time associated with the updated target carbon dioxide adsorption amount.

[0108] In step S430, the adsorption time is determined, and therefore, in the adsorption mode, the control device 17 applies the adsorption potential only for the determined adsorption time.

[0109] Next, the self-learning process, which is a method of switching the map in use, will be described with reference to Fig. 14. The control device 17 starts the process shown in the flowchart of Fig. 14 at the timing of the first detection after updating the target carbon dioxide adsorption amount. It can also be said that the control device 17 selects and determines the map to be used in accordance with the carbon dioxide monitored value only at the timing when the target carbon dioxide adsorption amount is changed and the first carbon dioxide monitored value is obtained. In this embodiment, the control device 17 starts the process shown in the flowchart of Fig. 14 at timing t13. Note that here, an example is adopted in which the currently used map is the first map.

[0110] The carbon dioxide capture system 10 estimates the target carbon dioxide adsorption amount (maximum adsorption amount) from the carbon dioxide monitor value. However, the carbon dioxide capture system 10 does not directly obtain the target carbon dioxide adsorption amount. In other words, the adsorption characteristics of the electrochemical cell can be considered uncertain. The adsorption amount of the electrochemical cell may decrease due to, for example, a decrease in the carbon dioxide concentration of the supplied air due to atmospheric humidity or the amount of air supplied, or due to aging of the electrochemical cell (such as a decrease in the adsorption area). Therefore, it is possible that the electrochemical cell may adsorb carbon dioxide at the same slope and saturate at the adsorption upper limit, or may adsorb carbon dioxide with a change in slope. Therefore, the control device 17 performs a self-learning process to select a map corresponding to the decreasing trend in the adsorption amount.

[0111] In step S500, it is determined whether the amount of recovered carbon dioxide is within the adsorption amount retention region. That is, the control device 17 determines whether the carbon dioxide monitor value detected via the sensor is within the adsorption amount retention region. If the control device 17 determines that the carbon dioxide monitor value is within the adsorption amount retention region, the process proceeds to step S510, and if it determines that the carbon dioxide monitor value is not within the adsorption amount retention region, the process proceeds to step S520. The carbon dioxide monitor value here is the initial carbon dioxide monitor value after the target carbon dioxide adsorption amount has been updated.

[0112] In other words, the control device 17 determines whether the decreasing trend of the carbon dioxide monitor value is flat or has a change in slope. Therefore, if the control device 17 determines that the carbon dioxide monitor value is within the adsorption amount holding region, it considers the decreasing trend of the carbon dioxide monitor value to be flat. If the control device 17 determines that the carbon dioxide monitor value is outside the adsorption amount holding region, it considers the decreasing trend of the carbon dioxide monitor value to have a slope.

[0113] In step S510, the current map in use is maintained. If the control device 17 determines that the carbon dioxide monitor value is within the adsorption amount maintenance region, it determines that there is no need to switch the map in use, and maintains the current map in use. Here, the control device 17 maintains the first map. In other words, the control device 17 selects the first map without switching the map in use.

[0114] In step S520, the map to be used is switched. When the control device 17 determines that the carbon dioxide monitored value is outside the adsorption amount holding region, it determines that the map to be used needs to be switched, and switches the currently used map. Here, the control device 17 switches the map to be used from the first map to the second map. In this way, the control device 17 selects the map to be used for obtaining the adsorption time from the plurality of adsorption amount change map data according to the carbon dioxide monitored value.

[0115] In step S530, the adsorption time currently being used is held. The control device 17 holds the adsorption time calculated (acquired) in step S420. Meanwhile, in step S540, a new adsorption time is calculated. That is, the control device 17 uses the second map to acquire the adsorption time associated with the updated target carbon dioxide adsorption amount. Therefore, in step S540, the adsorption time acquired in step S420 is updated to the adsorption time newly acquired using the second map. Furthermore, the control device 17 newly acquires an adsorption time longer than the adsorption time acquired in step S420 using the second map. Then, the control device 17 determines the map to be used in step S550, and determines the adsorption time in step S560. Note that this embodiment can be implemented in combination with the above-described Modifications 1 and 2.

[0116] The carbon dioxide capture system 10 of this embodiment can achieve the same effects as the above-described embodiment. Furthermore, the carbon dioxide capture system 10 has a first map and a second map stored in the memory unit 18, which have different adsorption times associated with the target adsorption amount. The first map and the second map can also be said to have different adsorption times associated with a decreased target carbon dioxide adsorption amount. Note that the adsorption amount of the electrochemical cell may temporarily increase due to changes over time or cleaning of the electrochemical cell. Therefore, the first map and the second map can be adopted even if they have different adsorption times associated with an increased target carbon dioxide adsorption amount in part. In other words, the first map and the second map can be said to have different adsorption times associated with a changed target carbon dioxide adsorption amount.

[0117] The carbon dioxide capture system 10 then selects the map to be used to obtain the adsorption time from the first map and the second map, depending on the carbon dioxide monitor value. Therefore, the carbon dioxide capture system 10 can appropriately control the adsorption time, which is the application time of the adsorption potential. In other words, the carbon dioxide capture system 10 can appropriately control the adsorption time while estimating the target carbon dioxide adsorption amount and adsorption time from the carbon dioxide monitor value. Furthermore, by selecting the map to be used as described above, the carbon dioxide capture system 10 can appropriately control the adsorption time, even if the electrochemical cell adsorbs carbon dioxide at the same slope and saturates at the adsorption upper limit, or even if the slope changes and the electrochemical cell adsorbs carbon dioxide.

[0118] Furthermore, the carbon dioxide capture system 10 can appropriately control the adsorption time, thereby preventing the adsorption time from becoming longer than necessary. In other words, the carbon dioxide capture system 10 can reduce wasted time. Accordingly, the carbon dioxide capture system 10 can increase the number of cycles of the control sequence. Therefore, the carbon dioxide capture system 10 can increase the amount of carbon dioxide captured.

[0119] By selecting the first map as described above, the carbon dioxide capture system 10 can prevent the adsorption time from becoming longer than necessary, thereby reducing the energy loss associated with the application of the adsorption potential when the adsorption amount in the electrochemical cell changes. Also, by selecting the second map as described above, the carbon dioxide capture system 10 can reduce the carbon dioxide capture loss when the adsorption amount in the electrochemical cell changes.

[0120] Although the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to the embodiments or structures. The present disclosure also encompasses various modifications and modifications within the scope of equivalents. In addition, although various combinations and forms are shown in the present disclosure, other combinations and forms including only one element, more, or less than one element are also within the scope and spirit of the present disclosure.

[0121] Finally, this specification discloses the following technical ideas and their combinations:

[0122] Technical thought 1 A carbon dioxide recovery system that recovers carbon dioxide from a mixed gas containing carbon dioxide by an electrochemical reaction, a carbon dioxide capture tank (16) for storing the captured carbon dioxide; a collector (12) having an electrochemical cell including a working electrode containing an adsorbent capable of adsorbing carbon dioxide and a counter electrode paired with the working electrode, and a housing for accommodating the electrochemical cell; a sensor (15) for detecting the amount of carbon dioxide recovered from the recovery device to the carbon dioxide recovery tank; a control device (17) that controls whether to apply a first potential between the working electrode and the counter electrode for an adsorption time corresponding to a target adsorption amount, which is an amount of carbon dioxide adsorbable by the adsorbent, so that the adsorbent adsorbs carbon dioxide when an adsorption mode in which carbon dioxide is adsorbed is performed, or to apply a second potential between the working electrode and the counter electrode for a collection time corresponding to a collection amount, so that the adsorbed carbon dioxide is desorbed by the adsorbent when a collection mode in which carbon dioxide is recovered is performed; a storage unit (18) in which a plurality of adsorption amount change data are stored, each data correlating a target adsorption amount with an adsorption time required to obtain the target adsorption amount; The plurality of pieces of adsorption amount change data are different adsorption times associated with the changed target adsorption amounts, The control device acquires the adsorption time from the adsorption amount change data, using a correlation value that correlates with the recovery amount, which is the detection result via the sensor, as the target adsorption amount, and selects the data to be used for acquiring the adsorption time from the multiple adsorption amount change data depending on the recovery amount. This is a carbon dioxide recovery system.

[0123] Technical thought 2 the storage unit stores first adsorption amount change data and second adsorption amount change data as the plurality of adsorption amount change data; The first adsorption amount change data is data in which the adsorption time is shortened as the target adsorption amount decreases, The carbon dioxide capture system according to Technical Concept 1, wherein the second adsorption amount change data indicates that the adsorption time is constant regardless of a decrease in the target adsorption amount.

[0124] Technical thought 3 The control device changes the target adsorption amount in accordance with changes in the recovery amount, which is the detection result, and selects and determines the adsorption amount change data in accordance with the recovery amount only at the timing when the target adsorption amount is changed and the first detection result is obtained. This is a carbon dioxide capture system described in Technical Idea 1 or 2.

[0125] Technical thought 4 The control device changes the target adsorption amount when the recovery amount changes and falls outside the target adsorption amount holding region, and holds the current usage data when the recovery amount that is the first detection result after changing the target adsorption amount is within the target adsorption amount holding region, and selects the usage data when the recovery amount that is the first detection result after changing the target adsorption amount falls outside the target adsorption amount holding region.

[0126] Technical thought 5 A carbon dioxide recovery system described in any one of technical ideas 2 to 4, wherein the control device retains the current adsorption time when the usage data is second adsorption amount change data, and acquires the adsorption time associated with the target adsorption amount in the first adsorption amount change data when the usage data is first adsorption amount change data. [Explanation of symbols]

[0127] 10: Carbon dioxide capture system 10a~10c: Subsystem 11, 11a to 11c: Flow path opening / closing valves 12, 12a to 12c: Collector 13: Pump 14: Flow path switching valve 15: Sensor 16: CO2 capture tank 17: Control device 18: Storage part 19: Blower 20a to 20c: Switching valve

Claims

1. A carbon dioxide recovery system that recovers carbon dioxide from a mixed gas containing carbon dioxide by an electrochemical reaction, a carbon dioxide capture tank (16) for storing the captured carbon dioxide; a collector (12) having an electrochemical cell including a working electrode containing an adsorbent capable of adsorbing carbon dioxide and a counter electrode paired with the working electrode, and a housing for accommodating the electrochemical cell; a sensor (15) for detecting the amount of carbon dioxide recovered from the recovery device to the carbon dioxide recovery tank; a control device (17) that controls whether to apply a first potential between the working electrode and the counter electrode for an adsorption time corresponding to a target adsorption amount, which is an adsorption amount of carbon dioxide that the adsorbent can adsorb, when an adsorption mode in which carbon dioxide is adsorbed is performed, so that the adsorbent adsorbs carbon dioxide, or to apply a second potential between the working electrode and the counter electrode for a collection time corresponding to the collection amount, when a recovery mode in which carbon dioxide is recovered is performed, so that the adsorbed carbon dioxide is desorbed; a storage unit (18) in which a plurality of pieces of adsorption amount change data are stored, the data being associated with the target adsorption amount and the adsorption time required to obtain the target adsorption amount; the plurality of pieces of adsorption amount change data are different in the adsorption time associated with the changed target adsorption amount, The control device updates the adsorption amount change data in accordance with the recovery amount, and acquires the adsorption time from the adsorption amount change data using a correlation value correlated with the recovery amount, which is the detection result via the sensor, as the target adsorption amount, and selects data to be used for acquiring the adsorption time from the plurality of adsorption amount change data in accordance with the recovery amount.

2. the storage unit stores first adsorption amount change data and second adsorption amount change data as the plurality of adsorption amount change data, the first adsorption amount change data indicates that the adsorption time is shortened as the target adsorption amount decreases, and The carbon dioxide capture system according to claim 1 , wherein the second adsorption amount change data indicates that the adsorption time is constant regardless of a decrease in the target adsorption amount.

3. The carbon dioxide capture system of claim 1 or 2, wherein the control device changes the target adsorption amount in accordance with a change in the recovery amount, which is the detection result, and selects and determines the adsorption amount change data in accordance with the recovery amount only at the timing when the target adsorption amount is changed and the detection result is first obtained.

4. The control device changes the target adsorption amount when the recovery amount changes and falls outside the target adsorption amount holding region, and holds the current usage data when the recovery amount that is the first detection result after changing the target adsorption amount is within the target adsorption amount holding region, and selects the usage data when the recovery amount that is the first detection result after changing the target adsorption amount falls outside the target adsorption amount holding region.

5. 3. The carbon dioxide capture system of claim 2, wherein the control device holds the current adsorption time when the usage data is the second adsorption amount change data, and acquires the adsorption time associated with the target adsorption amount in the first adsorption amount change data when the usage data is the first adsorption amount change data.

6. A carbon dioxide recovery system as described in claim 1 or 2, wherein the multiple adsorption amount change data are created by the control device by executing the adsorption mode multiple times, estimating the maximum adsorption amount of the electrochemical cell as the target adsorption amount based on the recovery amount detected in the multiple recovery modes executed corresponding to each adsorption mode, and estimating the adsorption time required to obtain the maximum adsorption amount.

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