Carbon dioxide capture system

Abstract

To provide a carbon dioxide recovery system which can suppress consumption of excessive energy for a carbon dioxide recovery amount.SOLUTION: A storage part 18 stores adsorption amount change map data indicating a change in adsorption amount of carbon dioxide accompanying elapse of time in execution of an adsorption mode, and recovery rate change map data indicating a change in ratio of a carbon dioxide recovery amount to a carbon dioxide adsorption amount accompanying the elapse of time in execution of a recovery mode. A control device 17 selects a combination of adsorption mode execution time and recovery mode execution time, in which the carbon dioxide recovery amount becomes relatively large and magnitudes of adsorption mode execution energy and recovery mode execution energy for recovering a predetermined unit amount of carbon dioxide become relatively low, on the basis of the adsorption amount change map data and the recovery rate change map data.SELECTED DRAWING: Figure 1

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, when carbon dioxide is adsorbed, a mixed gas containing carbon dioxide may be sent to the electrochemical cell by a fan or the like, and when carbon dioxide is released, carbon dioxide may be sucked out of the electrochemical cell by a pump or the like. Thus, when carbon dioxide is adsorbed or released, electrical energy is consumed by the fan, pump, etc.

[0005] Therefore, if the carbon dioxide capture system is simply driven so as to maximize the amount of carbon dioxide captured, there is a possibility that the carbon dioxide capture system will consume excessive energy compared to the amount of carbon dioxide captured.

[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 prevent excessive energy consumption relative to the amount of carbon dioxide captured. [Means for solving the problem]

[0007] In order to achieve the above object, the carbon dioxide recovery system according to the present disclosure is 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 pump (13) that, when the adsorbent desorbs the carbon dioxide adsorbed therein, sucks the carbon dioxide desorbed from the adsorbent from the collector and discharges it toward the carbon dioxide capture tank; a control device (17) that controls whether to apply a first potential between the working electrode and the counter electrode so that the electrochemical cell adsorbs carbon dioxide, or whether to apply a second potential between the working electrode and the counter electrode so that the electrochemical cell desorbs the adsorbed carbon dioxide, and that controls the pump so that the pump sucks in and discharges carbon dioxide at least when the electrochemical cell desorbs carbon dioxide; a storage unit (18) for storing, when an adsorption mode is being executed in which carbon dioxide is adsorbed in the carbon dioxide capture system, adsorption amount change data indicating a change over time in the amount of carbon dioxide adsorbed by the adsorbent, and recovery rate change data indicating a change over time in the ratio of the amount of carbon dioxide recovered in the carbon dioxide capture tank to the amount of carbon dioxide adsorbed by the adsorbent, when a capture mode is being executed in which carbon dioxide is captured in the carbon dioxide capture system, The control device determines, based on the adsorption amount change data and the recovery rate change data, that the amount of carbon dioxide recovered becomes relatively large and same Determine a combination of adsorption mode run time and capture mode run time that results in a relatively low magnitude of energy consumption in the capture mode, including the energy consumed by the pump, to capture a unit amount of carbon dioxide. It is something that The adsorption amount change data is divided into a plurality of areas based on time, and the carbon dioxide adsorption amount obtained for each area or over time to each area and the adsorption mode execution energy required for each area or over time to each area are determined; Dividing the capture rate change data into a plurality of areas based on time, determining the carbon dioxide capture rate obtained for each area or over time to each area, and the capture mode execution energy required for each area or over time to each area; Based on the carbon dioxide adsorption amount and adsorption mode execution energy determined for each area of ​​the adsorption amount change data, and the carbon dioxide recovery rate and recovery mode execution energy determined for each area of ​​the recovery rate change data, a total energy of the carbon dioxide recovery amount and adsorption mode execution energy and recovery mode execution energy is calculated for each combination of each area of ​​the adsorption amount change data and each area of ​​the recovery rate change data, and Calculating the total energy of the adsorption mode execution energy and the capture mode execution energy for capturing the same unit amount of carbon dioxide based on the calculated carbon dioxide capture amount and total energy; determining a combination of the adsorption mode execution time and the capture mode execution time based on the amount of carbon dioxide captured and the magnitude of the total energy required to capture the same unit amount of carbon dioxide when each area of ​​the adsorption amount change data is combined with each area of ​​the capture rate change data; It is configured as follows.

[0008] In the carbon dioxide capture system according to the present disclosure, as described above, the control device determines a combination of adsorption mode execution time and capture mode execution time that results in a relatively large amount of carbon dioxide capture and a relatively low amount of capture mode execution energy, including energy consumed by the pump, for capturing a predetermined unit amount of carbon dioxide. The control device then operates the carbon dioxide capture system in the adsorption mode in accordance with the determined adsorption mode execution time, and thereafter operates the carbon dioxide capture system in the capture mode in accordance with the determined capture mode execution time. As a result, it is possible to ensure the amount of carbon dioxide capture while suppressing the energy consumption of the carbon dioxide capture system.

[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] 10 is a flowchart showing the processing in a control device for executing a series of 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 sequences. [Figure 5] 10 is a flowchart showing a map creation process for creating adsorption amount change map data and recovery rate change map data. [Figure 6] FIG. 1 is a diagram showing an example of standard map data showing the tendency of change in the amount of carbon dioxide adsorption of an electrochemical cell over time. [Figure 7] 10A and 10B are explanatory diagrams illustrating an example of a method for estimating the maximum adsorption amount and the maximum adsorption time of an electrochemical cell. [Figure 8] FIG. 10 is a diagram showing an example of collection rate change map data. [Figure 9] 10A to 10C are diagrams showing some examples of vertical and / or horizontal expansion and / or contraction of standard map data. [Figure 10] 10 is a flowchart showing an execution time determination process in which the control device determines a combination of an adsorption mode execution time and a collection mode execution time. [Figure 11] FIG. 10 is a diagram showing an example of adsorption amount change map data divided into three areas. [Figure 12] FIG. 10 is a diagram showing an example in which collection rate change map data is divided into three areas. [Figure 13] 13 is a diagram showing nine cases in which each adsorption area of ​​the adsorption amount change map data of FIG. 11 and each recovery area of ​​the recovery rate change map data of FIG. 12 are combined. [Figure 14]14 is a graph showing an example of the amount of carbon dioxide recovered in each case of FIG. 13 and the total energy required to recover a predetermined unit amount of carbon dioxide in each case. [Figure 15] 10 is a graph showing an example of the amount of carbon dioxide recovered in each case when the carbon dioxide adsorption performance of the electrochemical cell has deteriorated due to aging, and the total energy required to recover a predetermined unit amount of carbon dioxide. 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, a blower 19, and an external server 20.

[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 arranged 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 that communicates the outside with 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.

[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.

[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 accumulated 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 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.

[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 storage unit 18 having a storage medium. This storage unit 18 stores adsorption amount change map data and recovery rate change map data. The adsorption amount change map data and recovery rate change map data will be described in detail later.

[0028] The control device 17 performs various types of 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 opening / closing 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 the various controlled devices so that a series of sequences for carbon dioxide recovery, including at least an adsorption mode, a scavenging mode, and a desorption / capture mode, is executed in the carbon dioxide recovery system 10.

[0029] A series of sequences for capturing carbon dioxide, including at least an adsorption mode, a scavenging mode, and a desorption / capture mode, executed in the carbon dioxide capture system 10, will be described below. Fig. 2 is a flowchart showing the processing performed by the control device 17 to execute the series of sequences for capturing carbon dioxide. 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 sequences.

[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 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 vacuuming 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 opening / closing 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 opening / closing 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, 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] 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 degradation. 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.

[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 step S130, the control device 17 starts a scavenging mode, which is the second operation mode in the sequence. In this scavenging mode, the flow path opening / closing valve 11 remains closed, as shown in FIG. 3. The adsorption potential applied between the working electrode and the counter electrode of the electrochemical cell in 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.

[0037] 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, and therefore the collector 12 is sealed on the upstream side 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 which remains 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.

[0038] 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.

[0039] 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 FIG. 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 then released to the outside via the flow path piping.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] In step S160, the control device 17 starts the desorption / recovery mode, which is the third operating mode in the 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 the carbon dioxide desorbed from the electrochemical cell in a state closer to a vacuum than the atmosphere.

[0044] 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.

[0045] 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 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 capable of only detecting the flow rate of carbon dioxide may be used as the sensor 15.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] The carbon dioxide adsorption performance of the electrochemical cell described above is thought to change due to changes in the external environment, such as temperature, humidity, and atmospheric carbon dioxide concentration, as well as aging of the electrochemical cell. 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.

[0051] 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.

[0052] Therefore, in the carbon dioxide capture system 10 according to this embodiment, the memory unit 18 of the control device 17 is configured to store, when the adsorption mode is executed, adsorption amount change map data that indicates the change over time in the amount of carbon dioxide adsorbed by the electrochemical cell, and capture rate change map data that indicates the change over time in the ratio of the amount of carbon dioxide captured in the CO2 capture tank 16 to the amount of carbon dioxide adsorbed by the electrochemical cell. The control device 17 is configured to determine, based on the adsorption amount change map data and capture rate change map data stored in the memory unit 18, a combination of the adsorption mode execution time and the capture mode execution time that results in a relatively large amount of carbon dioxide capture and a relatively small total amount of adsorption mode execution energy, including energy consumed by the blower 19, and capture mode execution energy, including energy consumed by the pump 13, for capturing a predetermined unit amount of carbon dioxide.

[0053] In the adsorption mode, if the blower 19 is not used and the pump 13 does not also function as the blower 19, the energy required to execute the adsorption mode may be considered to be substantially zero. Therefore, in this case, it is only necessary to consider the magnitude of the energy required to execute the capture mode, including the energy consumed by the pump 13, to capture a predetermined unit amount of carbon dioxide.

[0054] The control device 17 operates the carbon dioxide capture system 10 in the adsorption mode according to the determined adsorption mode execution time, and then operates the carbon dioxide capture system 10 in the capture mode according to the determined capture mode execution time. As a result, it is possible to ensure the amount of carbon dioxide captured while suppressing the energy consumption of the carbon dioxide capture system 10.

[0055] The adsorption amount change map data and the recovery rate change map data will be described in detail below. First, the map creation process for creating the adsorption amount change map data and the recovery rate change map data will be described based on the flowchart in FIG.

[0056] In step S200 of the flowchart in Fig. 5, standard map data showing the tendency of change in the amount of carbon dioxide adsorption of the electrochemical cell over time is received from the external server 20 shown in Fig. 1. An example of the standard map data is shown in Fig. 6. Note that the values ​​shown on the vertical and horizontal axes of the graph in Fig. 6 are merely examples. These values ​​change depending on the capacity of the electrochemical cell and the power consumption of the pump 13. The same applies to the values ​​on the vertical and horizontal axes shown in the other graphs.

[0057] The external server 20 creates standard map data based on experimental results, sensor detection results in multiple carbon dioxide capture systems 10, and the like. This standard map data is changed periodically (e.g., seasonally, monthly, weekly, etc.) for each region. The flowchart of FIG. 5 may be executed, for example, when notification of a change in the standard map data is received from the external server 20, or when it is detected that the amount of carbon dioxide capture calculated from the sensor detection results when the above-described series of sequences is executed has deviated from the target amount of carbon dioxide capture by a predetermined threshold or more. By executing the flowchart of FIG. 5, new adsorption amount change map data and capture rate change map data are created, or the created adsorption amount change map data and capture rate change map data are updated.

[0058] In step S210, the adsorption mode is executed multiple times with different adsorption mode execution times, and the amount of carbon dioxide captured in the multiple capture modes executed corresponding to each adsorption mode is detected via sensor 15. For example, Fig. 3 shows an example in which the adsorption mode is executed three times with different adsorption mode execution times. Note that the number of executions of the multiple adsorption modes may be two.

[0059] In FIG. 3, the execution time of the first adsorption mode is relatively short and is set so that the amount of carbon dioxide adsorbed by the electrochemical cell does not reach its upper limit. Therefore, the amount of carbon dioxide captured detected when the capture mode corresponding to the first adsorption mode is executed is less than the upper limit of the amount of carbon dioxide adsorbed by the electrochemical cell. 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 nearly reaches its upper limit. Therefore, the amount of carbon dioxide captured detected 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. The execution time of the third adsorption mode is the longest and is set so that the adsorption mode continues 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 detected 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.

[0060] In step S220, the maximum adsorption amount of the electrochemical cell and the maximum adsorption time, which is the adsorption mode execution time required to obtain that maximum adsorption amount, are estimated based on the sensor detection results obtained while the adsorption mode is executed multiple times and the recovery mode corresponding to each adsorption mode is executed multiple times. 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).

[0061] 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 adsorption mode execution, an increase gradient line can be determined by assuming that the longer the execution time of the adsorption mode, the more linearly the amount of carbon dioxide adsorbed.

[0062] Although FIG. 7(a) shows an example in which the increasing gradient line is a straight line, the increasing gradient line may be a curved line that curves upward, as shown in the standard map data of FIG. 6.

[0063] Figure 7(b) is a graph showing the carbon dioxide adsorption capacity of each electrochemical cell based on the carbon dioxide capture amount detected when the capture mode corresponding to the second and third adsorption modes was executed, as well as 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 continues 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 during the second and third adsorption modes. The carbon dioxide adsorption capacity corresponding to the upper limit line is the maximum adsorption capacity.

[0064] 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.

[0065] Then, as shown in FIG. 7(c), 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).

[0066] In step S230 of the flowchart in FIG. 5, recovery rate change map data is created and saved based on the sensor detection results during multiple executions of the adsorption mode and multiple executions of the capture mode corresponding to each adsorption mode. An example of the recovery rate change map data is shown in FIG. 8. As described above, 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. Therefore, once the amount of carbon dioxide adsorption by the electrochemical cell in each adsorption mode is known in step S210, recovery rate change map data such as that shown in FIG. 8 can be created based on the progress of the carbon dioxide capture amount calculated from the carbon dioxide concentration and flow rate detected at predetermined time intervals when the capture mode corresponding to each adsorption mode is executed. The created recovery rate change map data is stored in the memory unit 18.

[0067] In step S240, the maximum amount of adsorption in the standard map data (100 [g] in the example shown in FIG. 6) is compared with the maximum amount of adsorption estimated in step S220, and based on the comparison result, it is determined whether or not adjustment of the vertical axis direction of the standard map data is necessary. Specifically, for example, if the difference between the maximum amount of adsorption in the standard map data and the estimated maximum amount of adsorption is equal to or greater than a predetermined first threshold, it is determined that adjustment of the vertical axis direction of the standard map data is necessary. Conversely, if the difference between the maximum amount of adsorption in the standard map data and the estimated maximum amount of adsorption is less than the predetermined first threshold, it is determined that adjustment of the vertical axis direction of the standard map data is not necessary. If it is determined in step S240 that adjustment of the vertical axis direction is necessary, the process proceeds to step S250. If it is determined that adjustment of the vertical axis direction is not necessary, the process proceeds to step S260.

[0068] In step S250, the shape of the standard map data is enlarged or reduced depending on the magnitude and direction of the deviation between the maximum amount of adsorption in the standard map data and the estimated maximum amount of adsorption so that the deviated maximum amount of adsorption in the standard map data matches the estimated maximum amount of adsorption.

[0069] In step S260, the maximum adsorption amount time of the standard map data (100 [s] in the example shown in FIG. 6) is compared with the maximum adsorption amount time estimated in step S220, and based on the comparison result, it is determined whether or not adjustment of the horizontal axis direction of the standard map data is necessary. Specifically, for example, if the difference between the maximum adsorption amount time of the standard map data and the estimated maximum adsorption amount time is equal to or greater than a predetermined second threshold, it is determined that adjustment of the horizontal axis direction of the standard map data is necessary. Conversely, if the difference between the maximum adsorption amount time of the standard map data and the estimated maximum adsorption amount time is less than the predetermined second threshold, it is determined that adjustment of the horizontal axis direction of the standard map data is not necessary. If it is determined in step S260 that adjustment of the horizontal axis direction is necessary, the process proceeds to step S270. If it is determined that adjustment of the vertical axis direction is not necessary, the process proceeds to step S280.

[0070] In step S270, depending on the magnitude and direction of the deviation between the maximum adsorption amount time of the standard map data and the estimated maximum adsorption amount time, the shape of the standard map data is enlarged or reduced so that the deviated maximum adsorption amount time of the standard map data matches the estimated maximum adsorption amount time.

[0071] Some examples of vertical and / or horizontal expansion and / or contraction of the standard map data shape are shown in FIGS. 9(a) to 9(f).

[0072] 9(a) shows reduction pattern 1 in which the estimated maximum adsorption amount is 80 [g] and the shape of the standard map data is adjusted to be reduced in the vertical axis direction. FIG. 9(b) shows reduction pattern 2 in which the estimated maximum adsorption amount time is 80 [s] and the shape of the standard map data is adjusted to be reduced in the horizontal axis direction. FIG. 9(c) shows reduction pattern 3 in which the estimated maximum adsorption amount is 80 [g] and the maximum adsorption amount time is 80 [s] and the shape of the standard map data is adjusted to be reduced in the vertical axis direction and the horizontal axis direction.

[0073] Fig. 9(d) shows an enlarged pattern 1 in which the estimated maximum adsorption amount is 120 [g] and the shape of the standard map data is adjusted to be enlarged in the vertical axis direction. Fig. 9(e) shows an enlarged pattern 2 in which the estimated maximum adsorption amount time is 120 [s] and the shape of the standard map data is adjusted to be enlarged in the horizontal axis direction. Fig. 9(f) shows an enlarged pattern 3 in which the estimated maximum adsorption amount is 120 [g] and the maximum adsorption amount time is 120 [s] and the shape of the standard map data is adjusted to be enlarged in both the vertical axis direction and the horizontal axis direction.

[0074] Although not shown in FIG. 9, a possible pattern for expanding and / or reducing the standard map data in the vertical and / or horizontal directions is to expand the standard map data in one of the vertical and horizontal directions and reduce the standard map data in the other direction.

[0075] By expanding and / or reducing the standard map data in this manner, it is possible to obtain adsorption amount change map data that indicates the tendency of change in the carbon dioxide adsorption amount of the electrochemical cell over time, which is in accordance with the actual maximum adsorption amount and maximum adsorption time of the electrochemical cell. The obtained adsorption amount change map data is stored in the memory unit 18.

[0076] Next, we will explain the process executed by the control device 17 to determine a combination of adsorption mode execution time and recovery mode execution time based on the adsorption amount change map data and recovery rate change map data, which results in a relatively large carbon dioxide recovery amount and a relatively small total amount of adsorption mode execution energy, including energy consumed by the blower 19, and recovery mode execution energy, including energy consumed by the pump 13, required to recover a specified unit amount of carbon dioxide.

[0077] 10 is a flowchart showing an execution time determination process in which the control device 17 determines a combination of the adsorption mode execution time and the collection mode execution time. The flowchart in FIG. 10 is executed at least when the adsorption amount change map data is created or updated.

[0078] 10, the adsorption amount change map data and the recovery rate change map data stored in the storage unit 18 are read. The recovery rate change map data is divided into a plurality of areas based on time.

[0079] For example, Fig. 11 shows an example in which the adsorption amount change map data is divided into three areas based on time. In the example shown in Fig. 11, the range of time 0 to 20 [s] is adsorption area 1, the range of time 20 to 50 [s] is adsorption area 2, and the range of time 50 to 100 [s] is adsorption area 3. Fig. 12 also shows an example in which the recovery rate change map data is divided into three areas based on time. In the example shown in Fig. 12, the range of time 0 to 20 [s] is recovery area 1, the range of time 20 to 50 [s] is recovery area 2, and the range of time 50 to 100 [s] is recovery area 3.

[0080] Next, in step S320, the carbon dioxide adsorption amount and adsorption mode execution energy for each area of ​​the adsorption amount change map data are calculated. For example, in the example shown in Fig. 11, the carbon dioxide adsorption amount of adsorption area 1 is 60 [g], and the adsorption mode execution energy is 600 [W]. The carbon dioxide adsorption amount of adsorption area 2 is 20 [g], and the adsorption mode execution energy is 900 [W]. The carbon dioxide adsorption amount of adsorption area 3 is 20 [g], and the adsorption mode execution energy is 1500 [W]. Note that in the example shown in Fig. 11, the adsorption mode execution energy per unit time (1 second) is 30 [W] due to the energy consumed by the blower 19, etc.

[0081] In step S330, the amount of carbon dioxide captured and the energy required to execute the capture mode are calculated based on the carbon dioxide capture rate for each area in the capture rate change map data. For example, in the example shown in FIG. 12, the amount of carbon dioxide captured in capture area 1 is 20% of the total amount of carbon dioxide adsorbed by the electrochemical cells, and the energy required to execute the capture mode is 3000 [W]. The amount of carbon dioxide captured in capture area 2 is 60% of the total amount of carbon dioxide adsorbed by the electrochemical cells, and the energy required to execute the capture mode is 4500 [W]. The amount of carbon dioxide captured in capture area 3 is 20% of the total amount of carbon dioxide adsorbed by the electrochemical cells, and the energy required to execute the capture mode is 7500 [W]. Note that in the example shown in FIG. 12, the energy required to execute the capture mode per unit time (1 second) is 150 [W] due to factors such as the energy consumed by the pump 13.

[0082] However, the adsorption amount change map data shown in Fig. 11 and the recovery rate change map data shown in Fig. 12, and the division of the areas thereof, are merely examples. For example, the areas may be divided into two, or into four or more. Furthermore, for example, as described above, if the desorption mode and the recovery mode are separated, the shape of the recovery rate change map data may differ significantly.

[0083] In step S340, the amount of carbon dioxide captured and the total energy are calculated for each combination of each adsorption area in the adsorption amount change map data and each capture area in the capture rate change map data. For example, when each adsorption area in the adsorption amount change map data of Fig. 11 is combined with each capture area in the capture rate change map data of Fig. 12, nine combinations, cases 1 to 9, are obtained, as shown in Fig. 13.

[0084] Case 1 is a combination of adsorption area 1 of the adsorption amount change map data and recovery area 1 of the recovery rate change map data. Case 2 is a combination of adsorption areas 1 and 2 of the adsorption amount change map data and recovery area 1 of the recovery rate change map data. Case 3 is a combination of adsorption areas 1, 2, and 3 of the adsorption amount change map data and recovery area 1 of the recovery rate change map data. Case 4 is a combination of adsorption area 1 of the adsorption amount change map data and recovery areas 1 and 2 of the recovery rate change map data. Case 5 is a combination of adsorption areas 1 and 2 of the adsorption amount change map data and recovery areas 1 and 2 of the recovery rate change map data. Case 6 is a combination of adsorption areas 1, 2, and 3 of the adsorption amount change map data and recovery areas 1 and 2 of the recovery rate change map data. Case 7 is a combination of adsorption area 1 of the adsorption amount change map data and recovery areas 1, 2, and 3 of the recovery rate change map data. Case 8 is a combination of adsorption areas 1 and 2 of the adsorption amount change map data and recovery areas 1, 2, and 3 of the recovery rate change map data. Case 9 is a combination of adsorption areas 1, 2, and 3 of the adsorption amount change map data and recovery areas 1, 2, and 3 of the recovery rate change map data.

[0085] In addition, the amount of carbon dioxide recovered in Case 1 is 12 g, and the total energy is 3,600 W. In Case 2, the amount of carbon dioxide recovered is 16 g, and the total energy is 4,500 W. In Case 3, the amount of carbon dioxide recovered is 20 g, and the total energy is 6,000 W. In Case 4, the amount of carbon dioxide recovered is 48 g, and the total energy is 8,100 W. In Case 5, the amount of carbon dioxide recovered is 64 g, and the total energy is 9,000 W. In Case 6, the amount of carbon dioxide recovered is 80 g, and the total energy is 10,500 W. In Case 7, the amount of carbon dioxide recovered is 60 g, and the total energy is 15,600 W. In Case 8, the amount of carbon dioxide recovered is 80 g, and the total energy is 16,500 W. In Case 9, the amount of carbon dioxide recovered is 100 g, and the total energy is 18,000 W.

[0086] When dividing the adsorption amount change map data and the recovery rate change map data into areas, the range of time 0 to 50 [s] may be defined as adsorption area 2 and recovery area 2, respectively, and the range of time 0 to 100 [s] may be defined as adsorption area 3 and recovery area 3. In this way, by calculating the carbon dioxide adsorption amount and adsorption mode execution energy for each area of ​​the adsorption amount change map data, it is possible to simultaneously obtain the carbon dioxide adsorption amount obtained over time to each adsorption area and the adsorption mode execution energy required over time to each adsorption area. Furthermore, by calculating the carbon dioxide capture amount and recovery mode execution energy based on the carbon dioxide adsorption rate for each area of ​​the recovery rate change map data, it is possible to simultaneously obtain the carbon dioxide adsorption amount based on the carbon dioxide capture rate obtained over time to each recovery area and the recovery mode execution energy required over time to each recovery area.

[0087] In step S350, the total energy required to capture a predetermined unit amount of carbon dioxide for each case is calculated. For example, if the predetermined unit amount is 1 g, Case 1 requires a total energy of 300 W to capture the predetermined unit amount of carbon dioxide. Case 2 requires a total energy of 281 W to capture the predetermined unit amount of carbon dioxide. Case 3 requires a total energy of 300 W to capture the predetermined unit amount of carbon dioxide. Case 4 requires a total energy of 169 W to capture the predetermined unit amount of carbon dioxide. Case 5 requires a total energy of 141 W to capture the predetermined unit amount of carbon dioxide. Case 6 requires a total energy of 131 W to capture the predetermined unit amount of carbon dioxide. Case 7 requires a total energy of 260 W to capture the predetermined unit amount of carbon dioxide. Case 8 requires a total energy of 206 W to capture the predetermined unit amount of carbon dioxide. Case 9 requires a total energy of 180 W to capture the predetermined unit amount of carbon dioxide.

[0088] In step S360, a case (combination of areas) that offers an excellent balance between the amount of carbon dioxide captured and the total energy required to capture a specified unit amount of carbon dioxide for each case (combination of areas) is selected.

[0089] For example, the control device 17 can select the case in which the total energy required to recover a specified unit amount of carbon dioxide is the lowest among cases in which the amount of carbon dioxide recovered is equal to or greater than the first CO2 recovery amount standard value (corresponding to the first standard value).

[0090] Figure 14 is a graph showing an example of the amount of carbon dioxide captured in each case and the total energy required to capture a specified unit amount of carbon dioxide in each case. In the example shown in Figure 14, the amount of carbon dioxide captured is equal to or exceeds the CO2 capture amount standard value in three cases: cases 6, 8, and 9. Of these three cases, case 6 has the lowest total energy required to capture a specified unit amount of carbon dioxide. Therefore, case 6 is selected as the case that achieves an excellent balance between the amount of carbon dioxide captured and the total energy required.

[0091] As another example of selecting a case that has an excellent balance between the amount of carbon dioxide recovered and the total energy required, the control device 17 may select the case that has the largest amount of carbon dioxide recovered among cases in which the amount of total energy required to recover a specified unit amount of carbon dioxide is less than the first energy reference value (equivalent to the second reference value).

[0092] In the example shown in Fig. 14, there are three cases in which the magnitude of the total energy is less than the energy reference value: Cases 5, 6, and 9. Of these three cases, Case 9 has the largest amount of carbon dioxide captured. Therefore, in this case, Case 9 is selected as the case that has an excellent balance between the amount of carbon dioxide captured and the total energy required.

[0093] Furthermore, the control device 17 may be configured to select between the two methods described above and select the case that provides the best balance between the amount of carbon dioxide captured and the total energy required. Specifically, the control device 17 may be provided with an instruction unit, such as a selection switch, that allows the user to instruct whether to prioritize energy consumption or carbon dioxide capture. When the instruction to prioritize energy consumption is received, the control device 17 may select the case in which the total energy required to capture a predetermined unit of carbon dioxide is the lowest among cases in which the amount of carbon dioxide captured is equal to or greater than the second CO2 capture amount reference value (corresponding to the third reference value). The second CO2 capture amount reference value may be the same as the first CO2 capture amount reference value, but may be set to a value smaller than the first CO2 capture amount reference value to increase the number of cases in which the total energy required is the lowest.

[0094] For example, Figure 15 is a graph showing an example of the amount of carbon dioxide recovered in each case when the carbon dioxide adsorption performance of the electrochemical cell has deteriorated due to aging, and the total amount of energy required to recover a given unit amount of carbon dioxide.

[0095] 15, only case 9 exceeds the second CO2 capture amount standard value. Therefore, case 9 is selected as the case that has an excellent balance between the amount of carbon dioxide captured and the total required energy.

[0096] On the other hand, when instructed to prioritize the amount of carbon dioxide captured, the control device 17 may select a case in which the amount of carbon dioxide captured is the largest from among a set of cases in which the amount of total energy required to capture a predetermined unit amount of carbon dioxide is less than a second energy reference value (equivalent to a fourth reference value). The second energy reference value may be the same as the first energy reference value, but may be set to a value larger than the first energy reference value in order to increase the number of cases in which the amount of carbon dioxide captured is the largest.

[0097] In the example shown in Fig. 15, three cases, Cases 4, 5, and 6, are less than the second energy standard value. Of these three cases, Case 6 has the largest amount of carbon dioxide captured. Therefore, Case 6 is selected as the case that has an excellent balance between the amount of carbon dioxide captured and the total energy required.

[0098] In step S370 of the flowchart in Figure 10, a combination of pickup mode execution time and collection mode execution time corresponding to the selected case (combination of areas) is determined. For example, if case 6 is selected, the pickup mode execution time is determined to be 100 [s] and the collection mode execution time is determined to be 50 [s]. Also, if case 9 is selected, the pickup mode execution time is determined to be 100 [s] and the collection mode execution time is determined to be 100 [s].

[0099] 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-described embodiments may be modified as follows.

[0100] (Variation 1) In the above-described embodiment, when executing the recovery mode for the determined recovery mode execution time, the control device 17 may reduce the energy used to drive the pump 13 below the recovery energy shown in FIG. 12, for example, when the total energy required to recover a predetermined unit amount of carbon dioxide is equal to or greater than a third energy reference value that is greater than the first energy reference value. As a result, the suction force of the pump 13 is reduced below the specified suction force (for example, the suction force obtained when the pump 13 is driven with a recovery energy of 150 [W] in FIG. 12). However, by driving the pump 13 with the reduced suction force, it is possible to further reduce the energy required to execute the recovery mode.

[0101] The suction force of pump 13 may be reduced regardless of the amount of total energy required to recover a predetermined unit amount of carbon dioxide, for example, when the maximum amount of carbon dioxide adsorption by the electrochemical cell falls below a predetermined value, or when the usage time of carbon dioxide recovery system 10 reaches a predetermined time.

[0102] (Variation 2) In the above-described embodiment, no mention is made of the number of housings that house electrochemical cells. The number of housings may be one or more. When multiple housings, each housing an electrochemical cell, are provided, the multiple housings are connected in parallel to the CO2 capture tank 16. The control device 17 is configured to be able to execute an individual capture mode in which carbon dioxide is captured individually from each electrochemical cell in the multiple housings, and a simultaneous capture mode in which carbon dioxide is captured simultaneously from each electrochemical cell in at least two or more housings.

[0103] When executing the capture mode for the determined capture mode execution time, the control device 17 may execute the individual capture mode if, for example, the total amount of energy required to capture a predetermined unit amount of carbon dioxide when carbon dioxide is captured individually from multiple housings is less than a fourth energy reference value (corresponding to a fifth reference value) that is greater than the first energy reference value. However, if the total amount of energy is equal to or greater than the fourth energy reference value, the control device 17 may execute the simultaneous capture mode to reduce the energy captured by the entire system.

[0104] The simultaneous capture mode may be executed, regardless of the amount of total energy required to capture a predetermined unit amount of carbon dioxide, for example, when the total maximum carbon dioxide adsorption amount of the electrochemical cells in multiple housings falls below a predetermined value, or when the usage time of the carbon dioxide capture system 10 reaches a predetermined time.

[0105] (Variation 3) In the embodiment described above, the map data showing the trend of change over time in the carbon dioxide adsorption amount of the electrochemical cell was acquired as standard data from the external server 20. However, map data showing the trend of change over time in the carbon dioxide adsorption amount of the electrochemical cell can also be created in the carbon dioxide capture system 10. Specifically, in step S210 of the flowchart in FIG. 5 , the adsorption mode is executed multiple times for different adsorption mode execution times within a range in which the carbon dioxide adsorption amount of the electrochemical cell does not reach an upper limit value. Then, the adsorption amount of carbon dioxide adsorbed in the electrochemical cell in each adsorption mode is detected from the carbon dioxide capture amount detected in the capture mode executed corresponding to each adsorption mode. In this way, map data showing the trend of change over time in the carbon dioxide adsorption amount of the electrochemical cell can be created in the carbon dioxide capture system 10.

[0106] (Variation 4) 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 20. Furthermore, at least a part of the processing of the control device 17 may be executed by the external server 20.

[0107] Finally, this specification discloses the following technical ideas and their combinations:

[0108] (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 recovery vessel (12) including an electrochemical cell having 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 pump (13) that, when the adsorbent desorbs the carbon dioxide adsorbed by the adsorbent, sucks the carbon dioxide desorbed from the adsorbent from the collector and discharges it toward the carbon dioxide capture tank; a control device (17) that controls whether to apply a first potential between the working electrode and the counter electrode so that the electrochemical cell adsorbs carbon dioxide, or whether to apply a second potential between the working electrode and the counter electrode so that the electrochemical cell desorbs the adsorbed carbon dioxide, and that controls the pump so that the pump sucks in and discharges carbon dioxide at least when the electrochemical cell desorbs carbon dioxide; a storage unit (18) that stores, when an adsorption mode is being executed in which carbon dioxide is adsorbed in the carbon dioxide capture system, adsorption amount change data that indicates a change over time in the amount of carbon dioxide adsorbed by the adsorbent, and when a capture mode is being executed in which carbon dioxide is captured in the carbon dioxide capture system, recovery rate change data that indicates a change over time in the ratio of the amount of carbon dioxide captured in the carbon dioxide capture tank to the amount of carbon dioxide adsorbed by the adsorbent, The control device determines a combination of adsorption mode execution time and capture mode execution time based on the adsorption amount change data and the capture rate change data, which results in a relatively large amount of carbon dioxide capture and a relatively low amount of capture mode execution energy, including the energy consumed by the pump, to capture a specified unit amount of carbon dioxide.

[0109] (Technical thought 2) The method further includes a blower (19) that sends a mixed gas containing carbon dioxide into the housing when the adsorbent adsorbs carbon dioxide, The carbon dioxide capture system described in Technical Idea 1, wherein the control device determines a combination of adsorption mode execution time and capture mode execution time based on the adsorption amount change data and the capture rate change data, such that the amount of carbon dioxide captured is relatively large and the total energy amount of adsorption mode execution energy, including the energy consumed by the blower, and capture mode execution energy, including the energy consumed by the pump, required to capture a predetermined unit amount of carbon dioxide is relatively low.

[0110] (Technical Thought 3) The carbon dioxide capture system according to Technical Concept 2, wherein the pump also serves as the blower.

[0111] (Technical Thought 4) The control device The adsorption amount change data is divided into a plurality of areas based on time, and the carbon dioxide adsorption amount obtained for each area or over time to each area and the adsorption mode execution energy required for each area or over time to each area are determined; The recovery rate change data is divided into a plurality of areas based on time, and a carbon dioxide recovery rate obtained for each area or over time to each area and a recovery mode execution energy required for each area or over time to each area are determined; Based on the carbon dioxide adsorption amount and adsorption mode execution energy determined for each area of ​​the adsorption amount change data, and the carbon dioxide recovery rate and recovery mode execution energy determined for each area of ​​the recovery rate change data, a total energy of the carbon dioxide recovery amount and adsorption mode execution energy and recovery mode execution energy is calculated for each combination of each area of ​​the adsorption amount change data and each area of ​​the recovery rate change data, and Calculating the total energy of the adsorption mode execution energy and the capture mode execution energy required to capture a predetermined unit amount of carbon dioxide based on the calculated amount of carbon dioxide recovered and the total energy; A carbon dioxide capture system as described in Technical Idea 2 or 3, in which the combination of adsorption mode execution time and capture mode execution time is determined based on the amount of carbon dioxide captured and the amount of total energy required to capture a specified unit amount of carbon dioxide when each area of ​​the adsorption amount change data is combined with each area of ​​the capture rate change data.

[0112] (Technical Thought 5) The control device determines the combination of the adsorption mode execution time and the capture mode execution time from the combination that has the lowest total energy of the adsorption mode execution energy and the capture mode execution energy required to capture a specified unit amount of carbon dioxide, among the combinations that, when each area of ​​the adsorption amount change data is combined with each area of ​​the adsorption amount change data, result in an amount of carbon dioxide captured that is equal to or greater than a first reference value.Technical Idea 4 of the carbon dioxide capture system.

[0113] (Technical Thought 6) The control device is a carbon dioxide capture system described in Technical Idea 4, in which the control device determines the combination of the adsorption mode execution time and the capture mode execution time from the combination that results in the largest amount of carbon dioxide capture among combinations in which the total energy of the adsorption mode execution energy and the capture mode execution energy for capturing a specified unit amount of carbon dioxide is less than a second reference value when each area of ​​the adsorption amount change data is combined with each area of ​​the adsorption amount change data.

[0114] (Technical Thought 7) an instruction unit that instructs the control device whether to prioritize energy consumption or carbon dioxide recovery amount, When a priority is given to energy consumption, the control device determines a combination of the adsorption mode execution time and the capture mode execution time from among combinations in which the amount of carbon dioxide captured is equal to or greater than a third reference value, and from the combination in which the total energy of the adsorption mode execution energy and the capture mode execution energy required to capture a predetermined unit amount of carbon dioxide is the lowest; When priority is instructed to be given to the amount of carbon dioxide captured, the control device determines the combination of adsorption mode execution time and capture mode execution time from the combination that results in the greatest amount of carbon dioxide captured among combinations in which the total energy of the adsorption mode execution energy and the capture mode execution energy required to capture a specified unit amount of carbon dioxide when each area of ​​the adsorption amount change data is combined with each area of ​​the adsorption amount change data and the amount of carbon dioxide captured is less than a fourth reference value.

[0115] (Technical Thought 8) A carbon dioxide capture system described in any one of technical ideas 1 to 7, in which the control device, when executing the capture mode for the selected capture mode execution time, operates the pump with a suction force lower than a specified suction force, thereby further reducing the energy required to execute the capture mode.

[0116] (Technical Thought 9) a plurality of housings for accommodating the electrochemical cells are provided and connected in parallel to the recovery tank; The carbon dioxide capture system described in any one of Technical Ideas 1 to 8, wherein the control device is capable of executing an individual capture mode in which carbon dioxide is captured individually from the electrochemical cells of each of the multiple housings, and a simultaneous capture mode in which carbon dioxide is captured simultaneously from the electrochemical cells of at least two or more housings.

[0117] (Technical Thought 10) The carbon dioxide recovery system described in Technical Idea 9, wherein the control device executes the simultaneous recovery mode when the magnitude of recovery mode execution energy when selecting a combination of adsorption mode execution time and recovery mode execution time is equal to or greater than a fifth reference value.

[0118] (Technical Thought 11) A carbon dioxide capture system according to any one of technical ideas 1 to 10, wherein the adsorption amount change data is based on standard data provided from an external server (20) that indicates the trend of change in the carbon dioxide adsorption amount over time.

[0119] (Technical Thought 12) The control device Executing the adsorption mode a plurality of times at different elapsed times, and detecting the amount of carbon dioxide captured in the plurality of capture modes executed corresponding to each adsorption mode via a sensor; estimating a maximum adsorption amount of the electrochemical cell and a maximum adsorption amount time, which is an adsorption mode execution time required to achieve the maximum adsorption amount, based on multiple detection results of the amount of recovered carbon dioxide; A carbon dioxide capture system as described in Technical Idea 11, in which, if the estimated maximum adsorption amount and / or maximum adsorption amount time deviates from the maximum adsorption amount and / or maximum adsorption amount time in the standard data provided by the external server, the shape of the standard data is enlarged and / or reduced to match the deviated maximum adsorption amount and / or maximum adsorption amount time of the standard data with the estimated maximum adsorption amount and / or maximum adsorption amount time, thereby creating the adsorption amount change data. [Explanation of symbols]

[0120] 10: Carbon dioxide capture system 11: Flow path opening / closing valve 12: Collector 13: Pump 14: Flow path switching valve 15: Sensor 16: CO2 capture tank 17: Control device 18: Storage part 19: Blower 20: External server

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) including an electrochemical cell having 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 pump (13) that, when the adsorbent desorbs the carbon dioxide adsorbed by the adsorbent, sucks the carbon dioxide desorbed from the adsorbent from the recovery device and discharges it toward 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 so that the electrochemical cell adsorbs carbon dioxide, or whether to apply a second potential between the working electrode and the counter electrode so that the electrochemical cell desorbs the adsorbed carbon dioxide, and that controls the pump so that the pump sucks in and discharges carbon dioxide at least when the electrochemical cell desorbs carbon dioxide; a storage unit (18) that stores, when an adsorption mode is being executed in which carbon dioxide is adsorbed in the carbon dioxide capture system, adsorption amount change data that indicates a change over time in the amount of carbon dioxide adsorbed by the adsorbent, and when a capture mode is being executed in which carbon dioxide is captured in the carbon dioxide capture system, recovery rate change data that indicates a change over time in the ratio of the amount of carbon dioxide captured in the carbon dioxide capture tank to the amount of carbon dioxide adsorbed by the adsorbent; Equipped with The control device determines, based on the adsorption amount change data and the recovery rate change data, a combination of an adsorption mode execution time and a recovery mode execution time that results in a relatively large amount of carbon dioxide recovery and a relatively small amount of recovery mode execution energy, including energy consumed by the pump, for recovering the same unit amount of carbon dioxide, The adsorption amount change data is divided into a plurality of areas based on time, and the carbon dioxide adsorption amount obtained for each area or over time to each area and the adsorption mode execution energy required for each area or over time to each area are determined; The recovery rate change data is divided into a plurality of areas based on time, and a carbon dioxide recovery rate obtained for each area or over time to each area and a recovery mode execution energy required for each area or over time to each area are determined; Based on the carbon dioxide adsorption amount and adsorption mode execution energy determined for each area of ​​the adsorption amount change data, and the carbon dioxide recovery rate and recovery mode execution energy determined for each area of ​​the recovery rate change data, a total energy of the carbon dioxide recovery amount and adsorption mode execution energy and recovery mode execution energy is calculated for each combination of each area of ​​the adsorption amount change data and each area of ​​the recovery rate change data, and Calculating the total energy of the adsorption mode execution energy and the capture mode execution energy for capturing the same unit amount of carbon dioxide based on the calculated carbon dioxide capture amount and total energy; A carbon dioxide capture system that determines a combination of adsorption mode execution time and capture mode execution time based on the amount of carbon dioxide captured and the amount of total energy required to capture the same unit amount of carbon dioxide when each area of ​​the adsorption amount change data is combined with each area of ​​the capture rate change data.

2. The method further includes a blower (19) that sends a mixed gas containing carbon dioxide into the housing when the adsorbent adsorbs carbon dioxide, 2. The carbon dioxide capture system of claim 1, wherein the control device determines, based on the adsorption amount change data and the capture rate change data, a combination of adsorption mode execution time and capture mode execution time that results in a relatively large amount of carbon dioxide capture and a relatively small total energy amount of adsorption mode execution energy, including energy consumed by the blower, and capture mode execution energy, including energy consumed by the pump, for capturing the same unit amount of carbon dioxide.

3. The carbon dioxide recovery system according to claim 2 , wherein the pump also serves as the blower.

4. The control device determines the combination of the adsorption mode execution time and the capture mode execution time from the combination that has the lowest total energy of the adsorption mode execution energy and the capture mode execution energy for capturing the same unit amount of carbon dioxide among the combinations that, when each area of ​​the adsorption amount change data is combined with each area of ​​the capture rate change data, result in a carbon dioxide capture amount equal to or greater than the first carbon dioxide capture amount standard value.

5. The control device determines the combination of adsorption mode execution time and capture mode execution time from the combination that maximizes the amount of carbon dioxide captured among combinations in which the total energy of the adsorption mode execution energy and the capture mode execution energy required to capture the same unit amount of carbon dioxide is less than a first energy reference value when each area of ​​the adsorption amount change data is combined with each area of ​​the capture rate change data.

6. an instruction unit that instructs the control device whether to prioritize energy consumption or carbon dioxide recovery amount, When a priority is given to energy consumption, the control device determines a combination of the adsorption mode execution time and the capture mode execution time from the combination that has the lowest total energy of the adsorption mode execution energy and the capture mode execution energy for capturing the same unit amount of carbon dioxide, among combinations that result in a carbon dioxide capture amount equal to or greater than a second carbon dioxide capture amount reference value when each area of ​​the adsorption amount change data is combined with each area of ​​the capture rate change data, 2. The carbon dioxide capture system of claim 1, wherein when priority is instructed for the amount of carbon dioxide captured, the control device determines the combination of adsorption mode execution time and capture mode execution time from the combination that maximizes the amount of carbon dioxide captured among the combinations in which the total energy of the adsorption mode execution energy and the capture mode execution energy for capturing the same unit amount of carbon dioxide is less than a second energy reference value when each area of ​​the adsorption amount change data is combined with each area of ​​the capture rate change data.

7. A carbon dioxide capture system as described in any one of claims 1 to 6, wherein the control device, when executing the capture mode for the selected capture mode execution time, operates the pump with a suction force lower than a specified suction force, thereby further reducing the energy required to execute the capture mode.

8. a plurality of the housings for accommodating the electrochemical cells are provided and connected in parallel to the carbon dioxide recovery tank; 7. The carbon dioxide capture system according to claim 1, wherein the control device is capable of executing an individual capture mode in which carbon dioxide is captured individually from the electrochemical cells of each of the plurality of casings, and a simultaneous capture mode in which carbon dioxide is captured simultaneously from the electrochemical cells of at least two or more of the casings.

9. The carbon dioxide capture system according to claim 8, wherein the control device executes the simultaneous capture mode when the magnitude of the capture mode execution energy when selecting a combination of the adsorption mode execution time and the capture mode execution time is equal to or greater than a third energy reference value.

10. 7. The carbon dioxide recovery system according to claim 1, wherein the adsorption amount change data is based on standard data provided from an external server (20) that indicates the trend of change in the carbon dioxide adsorption amount over time.

11. The control device Executing the adsorption mode a plurality of times at different elapsed times, and detecting the amount of carbon dioxide captured in the plurality of capture modes executed corresponding to each adsorption mode via a sensor; estimating a maximum adsorption amount of the electrochemical cell and a maximum adsorption amount time, which is an adsorption mode execution time required to achieve the maximum adsorption amount, based on multiple detection results of the amount of recovered carbon dioxide; 11. The carbon dioxide capture system of claim 10, wherein, when the estimated maximum adsorption amount and / or maximum adsorption amount time deviates from the maximum adsorption amount and / or maximum adsorption amount time in the standard data provided by the external server, the shape of the standard data is enlarged and / or reduced to match the deviated maximum adsorption amount and / or maximum adsorption amount time of the standard data with the estimated maximum adsorption amount and / or maximum adsorption amount time, thereby creating the adsorption amount change data.

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