JP2024012240A - Carbon dioxide recovery system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a carbon dioxide recovery system capable of suppressing effects of water and foreign matters other than water adhering to an electrochemical cell.

SOLUTION: A system comprises an electrochemical cell 12a, which adsorbs carbon dioxide by application of an adsorption potential and desorbs the adsorbed carbon dioxide by application of a desorption potential, collection units 11, 13, 14, 16, which collect the carbon dioxide desorbed from the electrochemical cell, and a blower 19, which feeds an atmosphere containing carbon dioxide into a housing when the electrochemical cell adsorbs carbon dioxide contained in atmosphere. A controller 17, when not controlling the electrochemical cell and the collection units to adsorb carbon dioxide, activates the blower to force out air to remove water and/or foreign matters other than water adhering to the electrochemical cell.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present disclosure relates to a carbon dioxide recovery system that recovers carbon dioxide from an atmosphere containing carbon dioxide.

Patent Document 1 proposes a gas separation system that separates carbon dioxide from a mixed gas containing carbon dioxide by an electrochemical reaction. In this gas separation system, a gas mixture containing carbon dioxide is introduced into an enclosure in which an electrochemical cell is placed. In a charging mode that directs electrons to the negative electrode of an electrochemical cell, the electroactive material provided at the negative electrode is reduced. Therefore, a bond between the electroactive material and carbon dioxide at the negative electrode occurs, and carbon dioxide is separated from the mixed gas. On the other hand, the electroactive material at the negative electrode is oxidized in the discharge mode, which causes a flow of electrons in the opposite direction to that during the charge mode. This releases carbon dioxide from the electroactive material of the negative electrode.

Special table 2018-533470 publication

However, the atmosphere contains moisture (water vapor) and foreign substances other than moisture (dust, pollen, etc.). For this reason, when an electrochemical cell is exposed to the atmosphere in order to adsorb carbon dioxide from the atmosphere, it is inevitable that moisture and foreign substances other than moisture will adhere to the electrochemical cell. If moisture or foreign matter other than moisture adheres to the electrochemical cell, there is a risk that the electrochemical cell may not be able to sufficiently exhibit its ability to adsorb carbon dioxide, or that the moisture may cause an unintended short circuit.

The present disclosure has been made in view of the above-mentioned points, and aims to provide a carbon dioxide recovery system that is capable of suppressing the effects of moisture and foreign matter adhering to an electrochemical cell. .

In order to achieve the above object, the carbon dioxide capture system according to the present disclosure includes:
Recovers carbon dioxide from the atmosphere containing carbon dioxide by an electrochemical reaction,
an electrochemical cell (12a) disposed within the housing, which adsorbs carbon dioxide by applying an adsorption potential and desorbs the adsorbed carbon dioxide by applying a desorption potential;
a recovery unit (11, 13, 14, 16) that recovers carbon dioxide desorbed from the electrochemical cell;
By applying an adsorption potential to the electrochemical cell, carbon dioxide contained in the atmosphere introduced into the housing is adsorbed to the electrochemical cell, and by applying a desorption potential to the electrochemical cell, carbon dioxide is removed from the electrochemical cell. a control unit (17) that controls the electrochemical cell and the recovery unit to cause the recovery unit to desorb and recover the desorbed carbon dioxide;
A blower unit (19, 13) that is controlled by a control unit and sends atmosphere containing carbon dioxide into the casing when the electrochemical cell adsorbs carbon dioxide contained in the atmosphere,
When the control unit is not controlling the electrochemical cell and recovery unit to recover carbon dioxide, the control unit operates the blower unit to forcefully pass wind into the casing to remove particles that have adhered to the electrochemical cell. The device is configured to remove moisture and/or foreign substances other than moisture.

In this way, the control unit can remove moisture and/or foreign substances other than moisture adhering to the electrochemical cell by forced air blowing by the air blower, so the control unit can remove moisture and/or foreign substances other than moisture attached to the electrochemical cell. It becomes possible to suppress the influence of adhesion.

The reference numbers in parentheses above merely indicate an example of the correspondence with specific configurations in the embodiments described below to facilitate understanding of the present disclosure, and do not limit the scope of the present disclosure in any way. Not what I intended.

Further, technical features described in each claim other than the above-mentioned features of the present disclosure will become clear from the description of the embodiments and the accompanying drawings to be described later.

1 is a schematic configuration diagram schematically showing the configuration of a carbon dioxide recovery system 10 according to an embodiment. It is a flowchart which shows the process performed in a control apparatus in order to perform a series of control sequences for carbon dioxide recovery. (a) to (c) are explanatory diagrams for explaining adsorption mode, scavenging mode, and desorption/recovery mode included in a series of control sequences. 2 is a flowchart showing a foreign matter removal process for removing foreign matter other than water when the foreign matter mainly adheres to an electrochemical cell. It is a flowchart mainly showing a water removal process for removing water when it adheres to an electrochemical cell. 2 is a flowchart illustrating a dew condensation prevention process that detects a situation where there is a high possibility that moisture will adhere to an electrochemical cell and suppresses the attachment of moisture.

Hereinafter, a carbon dioxide recovery system according to an embodiment of the present disclosure will be described in detail with reference to the drawings. In addition, the same reference numerals are given to the same or equivalent parts in the plurality of drawings. The carbon dioxide recovery system according to this embodiment recovers carbon dioxide from the atmosphere containing carbon dioxide. The atmosphere from which carbon dioxide has been removed is exhausted to the outside. FIG. 1 schematically shows the configuration of a carbon dioxide recovery system 10 according to this embodiment.

_{The carbon} dioxide recovery system 10 shown in FIG. 20, a humidity sensor 21, and an external server 22.

The opening/closing state of the channel opening/closing valve 11 is controlled by a control device 17 . When the flow path opening/closing valve 11 is opened, the atmosphere containing carbon dioxide can be introduced into the recovery device 12 via the flow path piping that communicates the atmosphere with the inside of the recovery device 12 . On the other hand, when the channel opening/closing valve 11 is closed, the channel piping communicating between the atmosphere and the inside of the recovery device 12 is cut off, and the recovery device 12 is sealed. As a result, the atmosphere cannot enter into the collector 12 through the flow path piping provided with the flow path opening/closing valve 11.

Although not shown in the drawings, the blower 19 includes a blower fan rotated by a motor. When the channel opening/closing valve 11 is open, the blower fan of the blower 19 is rotationally driven by the control device 17 . As a result, the atmosphere containing carbon dioxide is sent into the collector 12 via the flow path piping that communicates the atmosphere with the interior of the collector 12 . However, the blower 19 may be omitted. Alternatively, the pump 13 may also serve as the blower 19. That is, when the channel opening/closing valve 11 is open, the pump 13 may be driven to draw atmospheric air containing carbon dioxide from the outside into the recovery device 12 via the channel piping. . Therefore, the blower 19 or the pump 13 corresponds to the blower section.

The recovery device 12 includes an electrochemical cell 12a arranged inside a metal case, for example. The electrochemical cell 12a adsorbs carbon dioxide through an electrochemical reaction, separates the carbon dioxide from the atmosphere, desorbs the adsorbed carbon dioxide, and uses the pump 13 to transfer the desorbed carbon dioxide to a CO ₂ recovery tank. 16. The collector 12 has two openings. One of the openings is an inlet for introducing atmospheric air containing carbon dioxide from the outside into the casing of the recovery device 12 . The other opening is an outlet for discharging the atmosphere from which carbon dioxide has been removed and the carbon dioxide desorbed from the electrochemical cell 12a. A flow path piping provided with the above-mentioned flow path opening/closing valve 11 is connected to the inlet, and a flow path piping provided with the pump 13 is connected to the discharge port. Note that the inside of the recovery container 12 is the same as the inside of the casing.

Inside the casing of the recovery device 12, a plurality of electrochemical cells 12a are arranged in a stacked manner. The stacking direction of the plurality of electrochemical cells 12a is perpendicular to the flow direction of the atmosphere. Each electrochemical cell 12a is configured in a plate shape, and arranged so that the plate surface intersects the cell stacking direction. A predetermined gap is provided between adjacent electrochemical cells 12a. The gap provided between adjacent electrochemical cells 12a becomes a flow path through which the atmosphere flows.

Each electrochemical cell 12a is configured by laminating, for example, a working electrode current collecting layer, a working electrode, a separator, a counter electrode, a counter electrode current collecting layer, etc. in the stated order. Note that 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 are given to the working electrode and carbon dioxide is adsorbed to the carbon dioxide adsorbent of the working electrode, or electrons are released from the working electrode. Adsorbed carbon dioxide can be desorbed. That is, by applying an adsorption potential between the working electrode and the counter electrode of the electrochemical cell 12a, carbon dioxide can be adsorbed to the electrochemical cell 12a (the carbon dioxide adsorbent of the working electrode). Further, carbon dioxide can be desorbed from the electrochemical cell 12a by applying a desorption potential different from the adsorption potential between the working electrode and the counter electrode of the electrochemical cell 12a.

The working electrode current collecting layer is made of a porous conductive material having pores through which the atmosphere containing carbon dioxide can pass. The working electrode current collecting layer only needs to have gas permeability and conductivity, and for example, a metal material or a carbonaceous material can be used as the material for forming the working electrode current collecting layer.

The working electrode is formed from a material mixed with a carbon dioxide adsorbent, a conductive substance, 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. As the carbon dioxide adsorbent, for example, polyanthraquinone can be used. The electrically conductive material forms a conductive path to the carbon dioxide adsorbent. As the conductive substance, for example, carbon materials such as carbon nanotubes, carbon black, and graphene can be used. The binder is for holding the carbon dioxide adsorbent and the conductive substance. As the binder, for example, a conductive resin can be used. As the conductive resin, for example, an epoxy resin containing Ag or the like as a conductive filler, a fluororesin such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), or the like can be used.

The counter electrode is formed from a material mixed with an electroactive additive, a conductive material, a binder, and the like. The conductive material and binder of the counter electrode are the same as the conductive material and binder of the working electrode, and therefore their explanation will be omitted. The electroactive auxiliary agent of the counter electrode is composed of a material having an active material that serves as an electron donor. The electroactive auxiliary material at the counter electrode is an auxiliary electroactive species that exchanges electrons with the carbon dioxide adsorbent at the working electrode. As the electroactive auxiliary material, for example, a metal complex that enables transfer of electrons by changing the valence of metal ions can be used. Examples of such metal complexes include cyclopentadienyl metal complexes such as ferrocene, nickelocene, and cobaltocene, and porphyrin metal complexes. These metal complexes may be polymers or monomers. The counter electrode current collecting layer is made of a conductive material such as a metal material or a carbonaceous material, similarly to the working electrode current collecting layer.

The separator is disposed between the working electrode and the counter electrode to separate the working electrode and the counter electrode. The separator is an insulating ion-permeable membrane that prevents physical contact between the working electrode and the counter electrode to suppress electrical short circuits and allows ions to pass therethrough. As the separator, a cellulose membrane, a polymer, a composite material of polymer and ceramic, etc. can be used.

Note that the electrochemical cell 12a is provided with an electrolyte extending over the working electrode and the counter electrode. For example, an ionic liquid can be used as the electrolyte. Ionic liquids are liquid salts that are nonvolatile at room temperature and pressure.

The pump 13 sucks the residual atmosphere left in the collector 12 from which carbon dioxide has been removed from the collector 12 and discharges it to the outside (that is, scavenges the residual atmosphere in the collector 12). When desorbing carbon dioxide adsorbed by the adsorbent, the desorbed carbon dioxide is sucked from the recovery device 12 and discharged toward the CO ₂ recovery tank 16 . When the pump 13 scavenges the residual atmosphere inside the recovery device 12, the flow path opening/closing valve 11 shuts off the flow path piping communicating between the outside and the inside of the recovery device 12. In other words, the flow path opening/closing valve 11 is activated only during the adsorption mode in which the controller 17 executes control for recovering carbon dioxide and causes the electrochemical cell 12a (carbon dioxide adsorbent) to adsorb carbon dioxide. It is opened and closed during a scavenging mode in which residual air is scavenged from inside the collector 12, and a desorption/recovery mode in which the electrochemical cell 12a desorbs carbon dioxide adsorbed and collects it in the CO ₂ recovery tank 16. Therefore, the residual atmosphere in the collector 12 is scavenged by evacuation by the pump 13. Further, the subsequent discharge of carbon dioxide into the CO ₂ recovery tank 16 is also performed in a state closer to a vacuum than to the atmosphere.

The flow path switching valve 14 is a three-way valve that switches the flow path of gas (atmosphere or carbon dioxide) flowing through the piping on the downstream side of the pump 13. Switching of the flow path of the flow path switching valve 14 is controlled by a control device 17. Specifically, the control device 17 controls the piping on the downstream side of the pump 13 when air containing carbon dioxide is introduced into the recovery device 12 and when residual air in the recovery device 12 is scavenged by the pump 13. The flow path switching valve 14 is controlled so as to communicate with the outside (atmosphere). As a result, the atmosphere from which carbon dioxide has been removed and the residual atmosphere in the collector 12 are released to the outside. On the other hand, when the pump 13 sucks and discharges the desorbed carbon dioxide from the recovery device 12 when the electrochemical cell 12a desorbs the carbon dioxide adsorbed, the controller 17 controls the control device 17 on the downstream side of the pump 13. The flow path switching valve 14 is controlled so that the piping is connected to the CO ₂ recovery tank 16 side. Thereby, the carbon dioxide recovered by the recovery device 12 can be accumulated in the CO ₂ recovery tank 16.

The CO ₂ sensor 15 detects the carbon dioxide concentration and flow rate of the gas flowing through the pipe connected to the CO ₂ recovery tank 16 at predetermined time intervals. The control device 17 can calculate (detect) the amount of carbon dioxide recovered in the CO ₂ recovery tank 16 from the carbon dioxide concentration and flow rate detected by the CO ₂ sensor 15 . Note that the CO ₂ sensor 15 may calculate the amount of carbon dioxide recovered. In this case, the CO ₂ sensor 15 outputs the calculated amount of carbon dioxide recovery to the control device 17 .

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 transmitting/receiving unit that communicates with the external server 22 and the like.

The temperature sensor 20 detects the outside temperature around the carbon dioxide recovery system 10. The humidity sensor 21 detects the humidity around the carbon dioxide recovery system 10. The temperature and humidity detected by the temperature sensor 20 and humidity sensor 21 are provided to the control device 17. The external server 22 provides the control device 17 with weather information (for example, weather information such as rain and snow, as well as advisory information such as low temperature and frost) in the area where the carbon dioxide recovery system 10 is installed. . The external server 22 can acquire weather information and various advisory information from, for example, information published by the Japan Meteorological Agency.

The control device 17 performs various arithmetic processing based on a control program stored in a storage medium such as a ROM, and controls various operations such as a flow path opening/closing valve 11, a recovery device 12, a pump 13, a flow path switching valve 14, and a blower 19. Controls the operation of controlled equipment. Further, the control device 17 communicates with an external server 22 via a transmitting/receiving section. Based on the information detected by the temperature sensor 20 and the humidity sensor 21 and the information acquired through communication with the external server 22, the control device 17 determines whether or not it is necessary to perform the foreign matter removal process and the moisture removal process. to decide. Then, if it is determined that it is necessary, the control device 17 executes the foreign matter removal process and/or the moisture removal process. The foreign matter removal process and the water removal process will be explained in detail later.

When executing control for carbon dioxide recovery, the control device 17 of the present embodiment executes a series of control sequences including at least an adsorption mode, a scavenging mode, and a desorption/recovery mode in the carbon dioxide recovery system 10. Controls the operation of various controlled devices to ensure that Note that the desorption/recovery mode indicates that the desorption mode and the recovery mode are one mode.

A series of control sequences for carbon dioxide recovery, including at least an adsorption mode, a scavenging mode, and a desorption/recovery mode, executed in the carbon dioxide recovery system 10 will be described below. FIG. 2 is a flowchart showing the processing performed by the control device 17 to execute a series of control sequences. FIGS. 3A to 3C are explanatory diagrams for explaining the adsorption mode, scavenging mode, and desorption/recovery mode included in a series of control sequences.

As shown in the flowchart of FIG. 2, the control device 17 first starts an adsorption mode, which is the first operation mode in a series of control sequences, in step S100. In this adsorption mode, as shown in FIG. 3(a), the channel opening/closing valve 11 is opened to allow atmospheric air containing carbon dioxide to be introduced into the recovery device 12. If a blower 19 is provided, the blower 19 is driven at a predetermined constant rotational speed so that a predetermined amount of atmospheric air is introduced into the collector 12 . When the pump 13 also serves as the blower 19, a motor (not shown) is driven at a predetermined rotational speed to drive the pump 13 to suck in atmospheric air, thereby drawing the atmospheric air into the collector 12 from the outside. In this case, the pump 13 is simply driven to suck in the atmosphere from the outside, so the energy required for sucking the air is used to drive the pump for evacuation in the scavenging mode and desorption/recovery mode, which will be described later. It requires less energy compared to

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

By controlling the flow path opening/closing valve 11, the electrochemical cell 12a of the recovery device 12, the flow path switching valve 14, etc., in the adsorption mode, carbon dioxide is removed as shown by the dotted arrow in FIG. 3(a). The contained air passes through the flow path opening/closing valve 11 and enters the collector 12 . Carbon dioxide contained in the atmosphere that has entered the collector 12 is adsorbed by the plurality of electrochemical cells 12a. As a result, carbon dioxide is removed from the atmosphere. The atmospheric air from which carbon dioxide has been removed passes through the pump 13, is guided to the flow path piping toward the outside at the flow path switching valve 14, and is discharged to the outside via the flow path piping.

In step S110 of the flowchart of FIG. 2, the control device 17 determines whether or not the adsorption mode execution time has elapsed. The adsorption mode execution time is set by the control device 17. In step S110, it is determined whether the set suction mode execution time has elapsed.

In the determination process of step S110, if it is determined that the set suction mode execution time has elapsed, the process proceeds to step S120. On the other hand, if it is determined that the set suction mode execution time has not elapsed, the determination process of step S110 is repeatedly executed until the suction mode execution time has elapsed.

In step S120, suction mode termination processing is executed. Specifically, the control device 17 closes the flow path opening/closing valve 11 to block atmospheric air from flowing into the recovery device 12 from the outside. Moreover, when the 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.

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

In the scavenging mode, driving of the pump 13 is started. As described above, since the channel opening/closing valve 11 is closed, the recovery vessel 12 is in a sealed state on the upstream side of the pump 13. When the pump 13 is driven in this state, the residual atmosphere, which is the atmosphere from which carbon dioxide has been removed, remaining in the sealed recovery vessel 12 is sucked from within the recovery vessel 12 and discharged to the outside. This makes it possible to scavenge the residual atmosphere within the collector 12. Note that since the recovery vessel 12 on the upstream side of the pump 13 is hermetically sealed, residual air in the recovery vessel 12 is scavenged by evacuation by the pump 13. For this reason, for example, when the pump 13 also serves as the blower 19, the drive of the pump 13 is continued, but the drive output thereof is increased compared to the intake mode by starting the scavenging mode.

By controlling the flow path opening/closing valve 11, the electrochemical cell 12a of the recovery device 12, the pump 13, and the flow path switching valve 14, in the scavenging mode, as shown by the dotted line arrow in FIG. The residual atmosphere in 12 from which carbon dioxide has been removed passes through the pump 13, is guided to the flow path piping toward the outside by the flow path switching valve 14, and is discharged to the outside via the flow path piping. .

In step S140 of the flowchart of FIG. 2, the control device 17 determines whether the scavenging mode execution time has elapsed. This scavenging mode execution time is predetermined to be a time sufficient to scavenge the residual atmosphere in the collector 12.

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

In step S160, the control device 17 starts a desorption/recovery mode, which is the third operation mode in the series of control sequences. In this desorption/recovery mode, as shown in FIG. 3(c), the channel opening/closing valve 11 is maintained in a closed state. Further, since the pump 13 also sucks carbon dioxide desorbed from the adsorbent of the electrochemical cell 12a in a state closer to a vacuum than the atmosphere, the pump 13 continues to be driven with the same drive output as in the scavenging mode.

On the other hand, between the working electrode and the counter electrode of the electrochemical cell 12a of the recovery device 12, there is a desorption mechanism in which electrons are released from the working electrode and carbon dioxide adsorbed by the carbon dioxide adsorbent of the working electrode can be desorbed. A potential is applied. This desorption potential is a predetermined constant potential. Furthermore, in the desorption/recovery mode, as shown in FIG. 3(c), the flow path switching valve 14 is controlled to connect the downstream piping of the pump 13 to the CO ₂ recovery tank 16.

By controlling the flow path opening/closing valve 11, the electrochemical cell 12a of the recovery device 12, the pump 13, and the flow path switching valve 14, in the desorption/recovery mode, as shown by the dotted arrow in FIG. 3(c), , carbon dioxide desorbed from the adsorbent of the electrochemical cell 12a passes through the pump 13, is guided to the flow path piping toward the CO ₂ recovery tank 16 by the flow path switching valve 14, and is passed through the flow path piping. and is accumulated in the CO ₂ recovery tank 16. Therefore, the channel opening/closing valve 11, the pump 13, the channel switching valve 14, and the CO ₂ recovery tank 16 correspond to a recovery section that recovers carbon dioxide desorbed from the electrochemical cell 12a.

At this time, the concentration and flow rate of carbon dioxide flowing through the flow path piping toward the CO ₂ recovery tank 16 are detected by the CO ₂ sensor 15 . Based on the detection result of the CO ₂ sensor 15, the control device 17 can calculate the amount of carbon dioxide recovered in the CO ₂ recovery tank 16 by executing a series of control sequences. Note that the concentration of carbon dioxide flowing through the flow path piping toward the CO ₂ recovery 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 CO ₂ sensor 15.

In addition, in the desorption/recovery mode, instead of desorbing and recovering carbon dioxide at the same time, the desorption of carbon dioxide from the electrochemical cell 12a is performed in advance, and after a predetermined period of time has elapsed since the desorption of carbon dioxide. , recovery of the desorbed carbon dioxide may begin. That is, by separating the desorption mode and the recovery mode and delaying the execution start time of the recovery mode from the execution start time of the desorption mode, the execution time of the recovery mode can be made shorter than the execution time of the desorption mode. Also good. In this case, the drive 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 the counter electrode of the electrochemical cell 12a to desorb carbon dioxide from the carbon dioxide adsorbent of the working electrode. After a predetermined period of time has elapsed since the start of the desorption mode and carbon dioxide has been desorbed to some extent, the recovery mode is started and the pump 13 is driven again. As a result, the pump 13 only needs to be driven in the collection mode, so that the pump 13 can be driven efficiently. However, even during the recovery mode in which the pump 13 is driven, a desorption potential is applied between the working electrode and the counter electrode of the electrochemical cell 12a, and carbon dioxide continues to be desorbed from the electrochemical cell 12a. That is, when the recovery mode is executed, the desorption mode is also continued, and the recovery mode and the desorption mode are executed simultaneously.

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

In the determination process of step S170, if it is determined that the set collection mode execution time has elapsed, the process advances 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.

In step S180, collection mode termination processing is executed. Specifically, the control device 17 opens the channel opening/closing valve 11 to communicate the recovery device 12 with the outside. However, the channel opening/closing valve 11 may be opened at the start of the adsorption mode, and may remain closed at the end of the recovery mode. The control device 17 stops applying the desorption potential to the electrochemical cell 12a. The control device 17 stops driving the pump 13. The control device 17 switches the flow path switching valve 14 to connect the flow path piping on the downstream side of the pump 13 to the outside. The communication of the flow path piping on the downstream side of the pump 13 to the outside may also be performed at the start of the adsorption mode. Furthermore, the control device 17 also resets the count value of a counter that counts the collection mode execution time.

Here, the atmosphere contains moisture (water vapor) and foreign substances other than moisture (dust, pollen, etc.). For this reason, when the electrochemical cell 12a is exposed to the atmosphere to adsorb carbon dioxide from the atmosphere, it is difficult to avoid adhesion of moisture or foreign substances other than moisture to the electrochemical cell 12a. If moisture or foreign matter other than moisture adheres to the electrochemical cell 12a, there is a risk that the electrochemical cell 12a may not be able to fully exhibit its ability to adsorb carbon dioxide, or that an unintended short circuit may occur due to the moisture. be.

Therefore, in the carbon dioxide recovery system 10 according to the present disclosure, the control device 17 controls the electrochemical cell 12a, the flow path on-off valve 11, the pump 13, the flow path switching valve 14, and the CO ₂ recovery tank in order to adsorb carbon dioxide. When the recovery section such as 16 is not controlled, the blower 19 or pump 13 as the blowing section is operated. As a result, the wind is forced to pass through the recovery device 12, so that moisture adhering to the electrochemical cell 12a and foreign substances other than moisture can be removed. As a result, the carbon dioxide recovery system 10 according to the present disclosure can suppress the influence of moisture or foreign matter other than moisture adhering to the electrochemical cell 12a.

First, a foreign matter removal process for removing foreign matter other than water when it adheres to the electrochemical cell 12a will be described with reference to the flowchart of FIG. 4. The foreign matter removal process shown in the flowchart of FIG. 4 may be executed, for example, periodically by the control device 17.

First, in step S200, the control device 17 determines whether conditions for removing foreign substances other than moisture are satisfied. The execution conditions for this foreign matter removal process are, for example, that the amount of carbon dioxide recovered calculated based on the detected value of the CO ₂ sensor 15 has decreased by a predetermined percentage or more from the initial recovery amount, and that the carbon dioxide recovery cycle (a series of control The number of repetitions of the sequence) has reached a predetermined number of times, and the operating time of the carbon dioxide recovery system 10 has reached a predetermined time. If any one of these conditions is satisfied, it can be estimated that foreign matter other than moisture has adhered to the electrochemical cell 12a. That is, an affirmative determination in the determination process of step S200 corresponds to the estimating unit estimating that foreign matter other than moisture has adhered to the electrochemical cell 12a. Note that the conditions for executing the foreign matter removal process are not limited to the conditions described above. For example, even when the user instructs cleaning of the electrochemical cell 12a, it may be determined that the conditions for executing the foreign matter removal process are satisfied. If it is determined in step S200 that the execution condition for the foreign object removal process is satisfied, the control device 17 proceeds to the process in step S210. On the other hand, if it is determined that the execution condition is not met, the control device 17 ends the foreign object removal process shown in FIG. 4 .

In step S210, the control device 17 initializes a timer that counts the execution time of the foreign object removal process, and then starts counting the timer. In step S220, the control device 17 turns on the blower 19, opens the channel on-off valve 11, and controls the channel switching valve 14 to connect the downstream piping of the pump 13 to the outside. Thereby, the air sent out by the blower 19 flows through the recovery device 12 and the pump 13 and is discharged to the outside, as shown in FIG. 3(a). At this time, foreign matter other than moisture adhering to the electrochemical cell 12a in the collector 12 is removed from the electrochemical cell 12a by the wind and discharged to the outside together with the wind. Further, even if some moisture adheres to the electrochemical cell 12a, the wind sent out by the blower 19 releases the moisture to the outside along with foreign substances other than moisture.

In step S230, the control device 17 acquires the outside temperature detected by the temperature sensor 20 and the humidity detected by the humidity sensor 21, and also acquires weather information from the external server 22. Then, in step S240, based on the various information acquired in step S230, the control device 17 determines that there is a possibility that a certain amount of moisture will adhere to the surface of the electrochemical cell 12a, and that the working electrode of the electrochemical cell 12a It is determined whether or not there is a possibility that a short circuit abnormality will occur in the electrochemical cell 12a through moisture attached to the surface when a potential is applied between the electrochemical cell 12a and the counter electrode.

For example, when the acquired weather information indicates rain or snow, or when the humidity is high to a certain extent (e.g., higher than the first threshold), the outside temperature decreases and the temperature of the electrochemical cell 12a and the outside temperature are different. When the temperature difference becomes large (for example, greater than or equal to the second threshold value), there is a possibility that dew condensation will occur on the surface of the electrochemical cell 12a. When dew condensation occurs on the surface of the electrochemical cell 12a, a short circuit abnormality may occur in the electrochemical cell 12a through the moisture adhering to the surface.

When the control device 17 determines in step S240 that there is a possibility that a short circuit abnormality will occur in the electrochemical cell 12a, the control device 17 proceeds to the process of step S260. On the other hand, if it is determined that there is no possibility that a short circuit abnormality will occur in the electrochemical cell 12a, the control device 17 proceeds to the process of step S250.

In step S250, it is considered that a short circuit will not occur in the electrochemical cell 12a even if a potential is applied between the working electrode and the counter electrode of the electrochemical cell 12a. Apply a potential. As a result, carbon dioxide adhering to the electrochemical cell 12a can be desorbed, and at the same time, removal of foreign substances other than water adhering to the electrochemical cell 12a can be promoted. On the other hand, in S260, if a potential is applied between the working electrode and the counter electrode of the electrochemical cell 12a, a short circuit may occur in the electrochemical cell 12a, so the control device 17 controls the voltage applied to the electrochemical cell 12a. Turn off the application. However, also in this case, moisture and foreign matter other than moisture adhering to the electrochemical cell 12a are removed by the air sent out by the blower 19.

In step S270, the control device 17 determines whether the count value of the timer has exceeded a predetermined foreign object removal determination time. If the count value of the timer is less than the predetermined foreign material removal determination time, the control device 17 repeats the process of step S270 until the time reaches or exceeds the predetermined foreign material removal determination time. When the count value of the timer becomes equal to or longer than the predetermined foreign matter removal determination time, it is assumed that sufficient foreign matter removal has been performed, and the control device 17 proceeds to the process of step S280.

In step S280, the control device 17 determines whether to start executing a series of control sequences. For example, if there is a start request from the user or if execution of a series of control sequences after foreign object removal processing is reserved, the control device 17 determines to start execution of the series of control sequences. In this case, the control device 17 proceeds to step S290 and shifts to the suction mode, which is the first operation mode in the series of control sequences.

On the other hand, when not starting execution of a series of control sequences, the control device 17 proceeds to the process of step S300. In step S300, the control device 17 turns off the blower 19, closes the flow path on/off valve 11, turns off the voltage application to the electrochemical cell 12a, turns off the pump 13, and switches the flow path switching valve 14 downstream of the pump 13. The operation of the carbon dioxide recovery system 10 is stopped by controlling the side piping to communicate with the outside.

Next, the water removal process for removing water mainly when it adheres to the electrochemical cell 12a will be described with reference to the flowchart of FIG. 5. The water removal process shown in the flowchart of FIG. 5 can be executed, for example, periodically by the control device 17, similarly to the foreign matter removal process of FIG.

First, in step S400, the control device 17 acquires the outside temperature detected by the temperature sensor 20 and the humidity detected by the humidity sensor 21, and also acquires weather information from the external server 22. Then, in step S410, based on the various information acquired in step S400, the control device 17 determines whether the conditions for performing the moisture removal process are satisfied. The execution conditions for this water removal process are, for example, that the acquired weather information indicates rain or snow, that a frost advisory has been issued, or that the humidity is high to a certain extent (for example, above the first threshold). At least one of the factors can be that the outside temperature sometimes decreases and the temperature difference between the temperature of the electrochemical cell 12a and the outside air temperature becomes large (for example, equal to or higher than the second threshold value). If any one of these conditions is satisfied, it can be estimated that moisture has adhered to the electrochemical cell 12a. That is, an affirmative determination in the determination process of step S410 corresponds to the estimation unit estimating that moisture has adhered to the electrochemical cell 12a. In this way, it can be estimated that moisture has adhered to the electrochemical cell 12a based on the atmospheric temperature (outside temperature) and humidity and/or based on the acquired weather information. Note that the conditions for executing the water removal process are not limited to the conditions described above. For example, if the operation of the carbon dioxide recovery system 10 is stopped at night when the temperature drops, moisture adhesion may be estimated when the system starts operation the next morning. If it is determined in step S410 that the conditions for executing the water removal process are satisfied, the control device 17 proceeds to the process in step S420. On the other hand, if it is determined that the execution conditions are not satisfied, the control device 17 ends the water removal process shown in FIG. 5.

In step S420, the control device 17 initializes a timer that counts the execution time of the water removal process, and then starts counting the timer. In step S430, the control device 17 turns on the blower 19, opens the flow path on-off valve 11, turns off the voltage application to the electrochemical cell 12a, turns off the pump 13, and switches the flow path switching valve 14 downstream of the pump 13. Control the side piping to communicate with the outside. Thereby, the wind sent out by the blower 19 flows through the collector 12 and the pump 13 and is discharged to the outside, as shown in FIG. 3(a). At this time, the moisture adhering to the electrochemical cell 12a in the collector 12 is removed from the electrochemical cell 12a by the wind and discharged to the outside together with the wind. Furthermore, if some foreign matter other than water is attached to the electrochemical cell 12a, the foreign matter other than water is also discharged to the outside together with the water.

In step S440, the control device 17 determines whether the count value of the timer has exceeded a predetermined moisture removal determination time. This water removal determination time may be the same as or different from the foreign matter removal determination time. If the count value of the timer is less than the predetermined water removal determination time, the control device 17 repeats the process of step S440 until the time reaches or exceeds the predetermined water removal determination time. When the count value of the timer exceeds the predetermined water removal determination time, the control device 17 proceeds to the process of step S450.

In step S450, the control device 17 determines whether to start executing a series of control sequences. For example, if there is a start request from the user or if the user has reserved execution of a series of control sequences after the water removal process, the control device 17 determines to start execution of the series of control sequences. In this case, the control device 17 proceeds to step S460 and shifts to the suction mode, which is the first operation mode in the series of control sequences.

On the other hand, if the execution of the series of control sequences is not to be started, the control device 17 proceeds to the process of step S470. In step S470, the control device 17 turns off the blower 19, closes the flow path on/off valve 11, turns off the voltage application to the electrochemical cell 12a, turns off the pump 13, and switches the flow path switching valve 14 downstream of the pump 13. The operation of the carbon dioxide recovery system 10 is stopped by controlling the side piping to communicate with the outside.

Although the preferred embodiments of the present disclosure have been described above, the present disclosure is not limited to the embodiments described above, and can be implemented in various modifications without departing from the gist of the present disclosure.

For example, in the embodiment described above, when the control device 17 estimates that moisture has adhered to the electrochemical cell 12a, it executes a moisture removal process to remove the attached moisture. However, the control device 17 may preventively detect a situation in which there is a high possibility that moisture will adhere to the electrochemical cell 12a, and perform dew condensation prevention processing to suppress the attachment of moisture. An example of the dew condensation prevention process will be described with reference to the flowchart of FIG. 6.

First, in step S500, the control device 17 acquires the outside temperature detected by the temperature sensor 20 and the humidity detected by the humidity sensor 21, and also determines the time zone to which the current time belongs from the external server 22 or internal clock. get. Then, in step S510, based on the various information acquired in step S500, the control device 17 determines whether conditions for performing dew condensation prevention processing to suppress adhesion of moisture are satisfied. The execution conditions for this dew condensation prevention process are, for example, when the outside temperature is low and the electrochemical cell 12a is in a nighttime period when the temperature is low, or when the humidity is high to a certain extent (for example, higher than the third threshold value). At least one of the conditions may be that the temperature difference between the temperature of the current temperature and the outside air temperature is expected to be large (for example, greater than or equal to the fourth threshold value). This is because if any one of these conditions is satisfied, there is a high possibility that moisture will adhere (dew condensation) to the electrochemical cell 12a. In this way, it is possible to determine whether conditions are established in which there is a high possibility that moisture will adhere to the electrochemical cell 12a, based on the atmospheric temperature (outside temperature) and humidity, or the time of day.

If it is determined in step S510 that the execution condition for the dew condensation prevention process is satisfied, the control device 17 proceeds to the process in step S520. On the other hand, if it is determined that the execution condition is not satisfied, the control device 17 ends the dew condensation prevention process shown in FIG. 6 .

In step S520, the control device 17 stops the operation of the carbon dioxide recovery system 10 for carbon dioxide recovery, that is, stops the series of control sequences described above, and causes the blower 19 to blow air. The air blowing by the air blower 19 may be temporary, intermittent, or continuous. By executing such dew condensation prevention control by the control device 17, it is possible to suppress dew condensation from occurring on the surface of the electrochemical cell 12a.

Further, the dew condensation prevention control is not limited to stopping the operation of the carbon dioxide recovery system 10 described above. For example, when the control device 17 determines that there is a high possibility that moisture will adhere to the electrochemical cell 12a based on the temperature and humidity of the atmosphere or the time of day, the control device 17 performs dew condensation prevention control by turning off the electricity for carbon dioxide recovery. The application time of the adsorption potential and/or desorption potential applied to the chemical cell 12a is determined by changing the application time of the adsorption potential and/or desorption potential applied to the electrochemical cell 12a when there is a low possibility that moisture will adhere to the electrochemical cell 12a. It may be shorter than the application time. By shortening the application time of the adsorption potential and/or desorption potential applied to the electrochemical cell 12a, heat generation in the electrochemical cell 12a can be suppressed. As a result, the temperature difference between the outside air temperature and the temperature of the electrochemical cell 12a can be reduced, and it is possible to suppress the formation of dew on the surface of the electrochemical cell 12a.

Furthermore, in the embodiments described above, there is no mention of the number of casings that house the electrochemical cells 12a. The number of the casings may be one or more. When a plurality of casings each housing an electrochemical cell 12a are provided, the plurality of casings may be connected in parallel to the CO ₂ recovery tank 16. The control device 17 operates in an individual recovery mode in which carbon dioxide is recovered individually from the electrochemical cells 12a of each of the plurality of casings, and in an individual recovery mode in which carbon dioxide is recovered simultaneously from each of the electrochemical cells 12a in at least two or more casings. It may be configured to be able to execute a simultaneous collection mode in which the data is collected. The simultaneous recovery mode may be executed, for example, when the usage time of the carbon dioxide recovery system 10 reaches a predetermined time.

In the embodiment described above, the control device 17 was configured to perform arithmetic processing for executing a series of control sequences. However, at least part of the processing of the control device 17 may be executed by a processing device other than the control device 17, for example, the external server 22.

Finally, this specification discloses a plurality of technical ideas listed below and a plurality of combinations thereof.

(Technical thought 1)
A carbon dioxide recovery system that recovers carbon dioxide from the atmosphere containing carbon dioxide by an electrochemical reaction,
an electrochemical cell (12a) disposed within the housing, which adsorbs carbon dioxide by applying an adsorption potential and desorbs the adsorbed carbon dioxide by applying a desorption potential;
a recovery unit (11, 13, 14, 16) that recovers carbon dioxide desorbed from the electrochemical cell;
An adsorption potential is applied to the electrochemical cell to cause carbon dioxide contained in the atmosphere introduced into the casing to be adsorbed to the electrochemical cell, and a desorption potential is applied to the electrochemical cell to cause the electrochemical a control unit (17) that controls the electrochemical cell and the recovery unit to desorb carbon dioxide from the cell and cause the recovery unit to recover the desorbed carbon dioxide;
a blowing unit (19, 13) that is controlled by the control unit and sends atmosphere containing carbon dioxide into the casing when the electrochemical cell adsorbs carbon dioxide contained in the atmosphere;
The control unit operates the air blower to forcibly pass wind into the housing when the electrochemical cell and the recovery unit are not being controlled to recover carbon dioxide. A carbon dioxide recovery system configured to remove moisture and/or non-moisture foreign matter adhering to an electrochemical cell.

(Technical thought 2)
further comprising an estimation unit that estimates that moisture and/or foreign matter other than moisture has adhered to the electrochemical cell,
The control unit operates the air blowing unit in response to the estimation unit estimating adhesion of moisture and/or foreign substances other than moisture, and the control unit operates the air blowing unit to eliminate moisture adhering to the electrochemical cell by wind passing through the casing. and/or the carbon dioxide recovery system according to Technical Idea 1, which removes foreign substances other than water.

(Technical thought 3)
The estimating unit determines that the amount of carbon dioxide recovered by the recovery unit has decreased, that the number of repetitions of carbon dioxide recovery has reached a predetermined number, and that the operating time of the carbon dioxide recovery system has reached a predetermined time. The carbon dioxide recovery system according to Technical Idea 2, wherein it is estimated that a foreign substance other than water has adhered to the electrochemical cell based on at least one of the above.

(Technical thought 4)
When the estimating unit estimates adhesion of foreign matter other than moisture, the control unit operates the blower to pass wind into the casing, and applies a desorption potential to the electrochemical cell. The carbon dioxide recovery system according to technical idea 2 or 3.

(Technical Thought 5)
The control unit stops applying the desorption potential to the electrochemical cell when an external environment including at least weather conditions may cause a short circuit abnormality due to application of the desorption potential to the electrochemical cell. , the carbon dioxide recovery system described in Technical Idea 4.

(Technical Thought 6)
The carbon dioxide according to technical idea 2 or 3, wherein the estimating unit estimates that moisture has adhered to the electrochemical cell based on atmospheric temperature and humidity and/or based on acquired weather information. Carbon capture system.

(Technical Thought 7)
When the control unit determines that there is a high possibility that moisture will adhere to the electrochemical cell based on the temperature and humidity of the atmosphere or the time of day, the control unit stops the operation of the carbon dioxide recovery system and stops the operation of the air blower. The carbon dioxide recovery system according to any one of Technical Ideas 1 to 6, wherein the carbon dioxide recovery system performs ventilation by a part.

(Technical Thought 8)
When the control unit determines that there is a high possibility that moisture will adhere to the electrochemical cell based on the temperature and humidity of the atmosphere or the time of day, the control unit may apply adsorption to the electrochemical cell for carbon dioxide recovery. The application time of the electric potential and/or desorption potential is made shorter than the application time of the adsorption potential and/or desorption potential applied to the electrochemical cell when the possibility of moisture adhering to the electrochemical cell is low. , the carbon dioxide recovery system according to any one of Technical Ideas 1 to 6, which suppresses heat generation of the electrochemical cell.

10: Carbon dioxide recovery system, 11: Channel opening/closing valve, 12: Recovery device, 12a: Electrochemical cell, 13: Pump, 14: Channel switching valve, 15: CO ₂ sensor, 17: Control device, 19: Blower , 20: Temperature sensor, 21: Humidity sensor, 22: External server

Claims (8)

A carbon dioxide recovery system that recovers carbon dioxide from the atmosphere containing carbon dioxide by an electrochemical reaction,
an electrochemical cell (12a) disposed within the housing, which adsorbs carbon dioxide by applying an adsorption potential and desorbs the adsorbed carbon dioxide by applying a desorption potential;
a recovery unit (11, 13, 14, 16) that recovers carbon dioxide desorbed from the electrochemical cell;
An adsorption potential is applied to the electrochemical cell to cause carbon dioxide contained in the atmosphere introduced into the casing to be adsorbed to the electrochemical cell, and a desorption potential is applied to the electrochemical cell to cause the electrochemical a control unit (17) that controls the electrochemical cell and the recovery unit to desorb carbon dioxide from the cell and cause the recovery unit to recover the desorbed carbon dioxide;
a blowing unit (19, 13) that is controlled by the control unit and sends atmosphere containing carbon dioxide into the casing when the electrochemical cell adsorbs carbon dioxide contained in the atmosphere;
The control unit operates the air blower to forcibly pass wind into the housing when the electrochemical cell and the recovery unit are not being controlled to recover carbon dioxide. A carbon dioxide recovery system configured to remove moisture and/or non-moisture foreign matter adhering to an electrochemical cell. further comprising an estimation unit that estimates that moisture and/or foreign matter other than moisture has adhered to the electrochemical cell,
The control unit operates the air blowing unit in response to the estimation unit estimating adhesion of moisture and/or foreign substances other than moisture, and the control unit operates the air blowing unit to eliminate moisture adhering to the electrochemical cell by wind passing through the casing. The carbon dioxide recovery system according to claim 1, wherein the carbon dioxide recovery system removes foreign substances other than moisture. The estimating unit determines that the amount of carbon dioxide recovered by the recovery unit has decreased, that the number of repetitions of carbon dioxide recovery has reached a predetermined number, and that the operating time of the carbon dioxide recovery system has reached a predetermined time. The carbon dioxide recovery system according to claim 2, wherein it is estimated that foreign matter other than moisture has adhered to the electrochemical cell based on at least one of the above. When the estimating unit estimates adhesion of foreign matter other than moisture, the control unit operates the blower to pass wind into the casing, and applies a desorption potential to the electrochemical cell. The carbon dioxide recovery system according to claim 2 or 3. The control unit stops applying the desorption potential to the electrochemical cell when an external environment including at least weather conditions may cause a short circuit abnormality due to application of the desorption potential to the electrochemical cell. , The carbon dioxide recovery system according to claim 4. The carbon dioxide according to claim 2 or 3, wherein the estimation unit estimates that moisture has adhered to the electrochemical cell based on atmospheric temperature and humidity and/or based on acquired weather information. collection system. When the control unit determines that there is a high possibility that moisture will adhere to the electrochemical cell based on the temperature and humidity of the atmosphere or the time of day, the control unit stops the operation of the carbon dioxide recovery system and stops the operation of the air blower. The carbon dioxide recovery system according to claim 1 or 2, wherein the carbon dioxide recovery system performs ventilation by a part. When the control unit determines that there is a high possibility that moisture will adhere to the electrochemical cell based on the temperature and humidity of the atmosphere or the time of day, the control unit may apply adsorption to the electrochemical cell for carbon dioxide recovery. The application time of the electric potential and/or desorption potential is made shorter than the application time of the adsorption potential and/or desorption potential applied to the electrochemical cell when the possibility of moisture adhering to the electrochemical cell is low. The carbon dioxide recovery system according to claim 1 or 2, wherein heat generation of the electrochemical cell is suppressed.

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