Carbon dioxide recovery system

Abstract

This carbon dioxide recovery system is provided with: a carbon dioxide adsorption unit (C) which is disposed in an air flow path (P) and has an adsorbent that has a characteristic such that the carbon dioxide adsorption / desorption performance thereof changes in accordance with the water content; a water adsorption unit (W) which is disposed in the upstream of the carbon dioxide adsorption unit (C) in the air flow path (P) and adsorbs water in the air in the air flow path (P); and heating sources (32, 34) for heating the water adsorption unit (W) so that water is desorbed from the water adsorption unit (W) into the air in the air flow path (P).

Description

Carbon dioxide capture system

[0001] The present disclosure relates to carbon dioxide capture systems.

[0002] There is a carbon dioxide capture system that adsorbs carbon dioxide in the air with an adsorbent and captures the carbon dioxide desorbed from the adsorbent. The carbon dioxide capture system disclosed in Patent Document 1 has an adsorbent whose carbon dioxide adsorption / desorption performance changes depending on the water content. This carbon dioxide capture system uses a sprayer that sprays water as a means for adjusting the water content of the adsorbent.

[0003] JP 2015-12015 A

[0004] The carbon dioxide capture system of Patent Document 1 requires a water source to supply water to the adsorbent.

[0005] The present disclosure provides a carbon dioxide capture system that can eliminate or reduce water sources.

[0006] The first aspect relates to a carbon dioxide capture system. The carbon dioxide capture system includes: a carbon dioxide adsorption unit (C) that has an adsorbent whose carbon dioxide adsorption and desorption performance changes depending on the water content and that is arranged in an air flow path (P); a water adsorption unit (W) that is arranged in the air flow path (P) upstream of the carbon dioxide adsorption unit (C) and that adsorbs water in the air in the air flow path (P); and a heat source (32, 34) that heats the water adsorption unit (W) so that water is desorbed from the water adsorption unit (W) into the air in the air flow path (P).

[0007] In the first aspect, the water adsorption section (W) adsorbs water in the air. The heating source (32, 34) heats the water adsorption section (W) so that water is desorbed from the water adsorption section (W). As a result, the air containing the desorbed water flows through the carbon dioxide adsorption section (C) downstream of the water adsorption section (W). Here, the adsorbent of the carbon dioxide adsorption section (C) has a property in which its carbon dioxide adsorption / desorption performance changes depending on its water content. Therefore, as the water content of the adsorbent increases, carbon dioxide is desorbed from the carbon dioxide adsorption section (C). As described above, in the carbon dioxide capture system of the first aspect, water for desorbing carbon dioxide from the carbon dioxide adsorption section (C) is obtained from the air. This eliminates or reduces the size of a water source.

[0008] In a second aspect, the carbon dioxide capture system of the first aspect includes a capture mechanism (50) that captures carbon dioxide desorbed from the carbon dioxide adsorption section (C), and a control section (100) that controls the heating source (32, 34) and the capture mechanism (50). The control section (100) executes an adsorption operation in which carbon dioxide in the air after water has been adsorbed by the water adsorption section (W) is adsorbed by the carbon dioxide adsorption section (C), and a desorption operation in which air containing water desorbed from the water adsorption section (W) that has been heated by the heating source (32, 34) is sent to the carbon dioxide adsorption section (C) and the carbon dioxide desorbed from the carbon dioxide adsorption section (C) is captured by the capture mechanism (50).

[0009] In the second aspect, in the adsorption operation, the water adsorption unit (W) adsorbs water in the air. The carbon dioxide adsorption unit (C) adsorbs carbon dioxide in the air after the water has been adsorbed by the water adsorption unit (W). Here, the adsorbent of the carbon dioxide adsorption unit (C) has a property in which its carbon dioxide adsorption and desorption performance changes depending on its water content. Therefore, as the water content of the adsorbent decreases, carbon dioxide becomes more easily adsorbed by the carbon dioxide adsorption unit (C).

[0010] In the desorption operation, the heat source (32, 34) heats the water adsorption section (W), causing water to desorb from the water adsorption section (W). Air containing the desorbed water flows through the carbon dioxide adsorption section (C), causing carbon dioxide to desorb from the carbon dioxide adsorption section (C). The recovery mechanism (50) recovers the carbon dioxide desorbed from the carbon dioxide adsorption section (C).

[0011] In a third aspect, the air conditioner according to the second aspect further includes a refrigerant circuit (30) having a compressor (31), a radiator (32, 34) as a heat source, an expansion mechanism (33), and an evaporator (34, 32), in which a refrigerant circulates to perform a refrigeration cycle.

[0012] In the third aspect, the radiator (32, 34) of the refrigerant circuit (30) is used as a heat source for desorbing water from the water adsorption section (W), thereby improving the energy saving of the carbon dioxide capture system.

[0013] In the fourth aspect, in the third aspect, the adsorption operation is an operation in which carbon dioxide in the air cooled in the evaporator (34, 32) is adsorbed in the carbon dioxide adsorption section (C).

[0014] In the fourth aspect, the evaporator (34, 32) cools the air during the adsorption operation. This improves the water adsorption capacity of the water adsorption section (W) during the adsorption operation. In addition, it improves the carbon dioxide adsorption capacity of the carbon dioxide adsorption section (C).

[0015] In a fifth aspect, in the third or fourth aspect, the control section (100) further causes a drying operation to be performed in which the carbon dioxide adsorbing section (C) is dried with air heated by the radiators (32, 34).

[0016] In the fifth aspect, in the drying operation, the radiators (32, 34) heat the air, thereby reducing the humidity of the air. This air flows through the carbon dioxide adsorption section (C), thereby drying the carbon dioxide adsorption section (C). As a result, in the next adsorption operation, the carbon dioxide adsorption capacity of the carbon dioxide adsorption section (C) can be improved.

[0017] In a sixth aspect, in any one of the third to fifth aspects, the refrigerant circuit (30) includes a first adsorption heat exchanger (32) provided with a water adsorption section (W), a second adsorption heat exchanger (34) provided with the water adsorption section (W), and a refrigerant switching mechanism (35) which switches a flow path of the refrigerant circuit (30) to switch between a first refrigeration cycle in which the first adsorption heat exchanger (32) functions as a radiator and the second adsorption heat exchanger (34) functions as an evaporator, and a second refrigeration cycle in which the second adsorption heat exchanger (34) functions as a radiator and the first adsorption heat exchanger (32) functions as an evaporator. The carbon dioxide recovery system further includes a flow path switching mechanism (40) that switches the air flow path (P) between a first flow path state that connects the first adsorption heat exchanger (32) and the carbon dioxide adsorption section (C) and a second flow path state that connects the second adsorption heat exchanger (34) and the carbon dioxide adsorption section (C).

[0018] In the sixth aspect, by performing the first refrigeration cycle, water in the air can be adsorbed onto the water adsorption section (W) of the second adsorption heat exchanger (34) functioning as an evaporator. At the same time, water can be desorbed from the water adsorption section (W) of the first adsorption heat exchanger (32) functioning as a radiator. By performing the second refrigeration cycle, water in the air can be adsorbed onto the water adsorption section (W) of the first adsorption heat exchanger (32) functioning as an evaporator. At the same time, water can be desorbed from the water adsorption section (W) of the second adsorption heat exchanger (34) functioning as a radiator.

[0019] By setting the flow path switching mechanism (40) in the first flow path state, it is possible to send the air cooled in the first adsorption heat exchanger (32) to the carbon dioxide adsorption section (C) and to send air containing water desorbed from the first adsorption heat exchanger (32) to the carbon dioxide adsorption section (C). By setting the flow path switching mechanism (40) in the second flow path state, it is possible to send the air cooled in the second adsorption heat exchanger (34) to the carbon dioxide adsorption section (C) and to send air containing water desorbed from the second adsorption heat exchanger (34) to the carbon dioxide adsorption section (C).

[0020] In the seventh aspect, in the sixth aspect, the control unit (100) controls the refrigerant switching mechanism (35) and the flow path switching mechanism (40) to perform a first operation in which the refrigerant circuit (30) performs a second refrigeration cycle and simultaneously sets the air flow path (P) to a first flow path state, and a second operation in which the refrigerant circuit (30) performs the first refrigeration cycle and simultaneously sets the air flow path (P) to a second flow path state, during the adsorption operation.

[0021] In the seventh aspect, the adsorption operation includes a first operation and a second operation. In the first operation, air that has passed through the first adsorption heat exchanger (32) flows through the carbon dioxide adsorption section (C). The first adsorption heat exchanger (32) functions as an evaporator, and therefore the air can be cooled by the refrigerant. As a result, the water adsorption capacity of the first adsorption heat exchanger (32) and the carbon dioxide adsorption capacity of the water adsorption section (W) of the carbon dioxide adsorption section (C) can be improved. At the same time, in the first operation, the second adsorption heat exchanger (34) functions as a radiator, and therefore the water adsorption section (W) of the second adsorption heat exchanger (34) can be heated by the refrigerant. As a result, the water adsorption section (W) can be regenerated.

[0022] In the second operation, the air that has passed through the second adsorption heat exchanger (34) flows through the carbon dioxide adsorption section (C). The second adsorption heat exchanger (34) functions as an evaporator, and therefore the air can be cooled by the refrigerant. As a result, the water adsorption capacity of the water adsorption section (W) of the second adsorption heat exchanger (34) and the carbon dioxide adsorption capacity of the carbon dioxide adsorption section (C) can be improved. At the same time, in the second operation, the first adsorption heat exchanger (32) functions as a radiator, and therefore the water adsorption section (W) of the first adsorption heat exchanger (32) can be heated by the refrigerant. As a result, the water adsorption section (W) can be regenerated.

[0023] In this way, by performing the first operation and the second operation, low humidity air can be continuously supplied to the carbon dioxide adsorption section (C).

[0024] In an eighth aspect, in the sixth or seventh aspect, the control unit (100) controls the refrigerant switching mechanism (35) and the flow path switching mechanism (40) to perform a third operation in which the refrigerant circuit (30) performs a first refrigeration cycle and simultaneously sets the air flow path (P) to a first flow path state, and a fourth operation in which the refrigerant circuit (30) performs a second refrigeration cycle and simultaneously sets the air flow path (P) to a second flow path state, during the desorption operation.

[0025] In the eighth aspect, the desorption operation includes a third operation and a fourth operation. In the third operation, the air that has passed through the first adsorption heat exchanger (32) flows through the carbon dioxide adsorption section (C). Since the first adsorption heat exchanger (32) functions as a radiator, the water adsorption section (W) of the first adsorption heat exchanger (32) is heated by the refrigerant, and water is desorbed from the water adsorption section (W). The air containing the desorbed water flows through the carbon dioxide adsorption section (C). As a result, the water content of the carbon dioxide adsorption section (C) increases, and water is desorbed from the adsorbent. In the third operation, the second adsorption heat exchanger (34) simultaneously functions as an evaporator, and water in the air can be adsorbed by the water adsorption section (W) of the second adsorption heat exchanger (34).

[0026] In the fourth operation, the air that has passed through the second adsorption heat exchanger (34) flows through the carbon dioxide adsorption section (C). Since the second adsorption heat exchanger (34) functions as a radiator, the water adsorption section (W) of the second adsorption heat exchanger (34) is heated by the refrigerant, and water is desorbed from the water adsorption section (W). The air containing the desorbed water flows through the carbon dioxide adsorption section (C). As a result, the water content of the carbon dioxide adsorption section (C) increases, and water is desorbed from the adsorbent. At the same time, in the fourth operation, the first adsorption heat exchanger (32) functions as an evaporator, and therefore, water in the air can be adsorbed by the water adsorption section (W) of the first adsorption heat exchanger (32).

[0027] In this way, by performing the third and fourth operations, it is possible to continuously supply highly humid air to the carbon dioxide adsorption section (C).

[0028] A ninth aspect is a first operation performed in any one of the sixth to eighth aspects, in which an adsorption operation is performed in which air cooled by the adsorption heat exchanger (32, 34) of the first adsorption heat exchanger (32) or the second adsorption heat exchanger (34) that functions as an evaporator is sent to one of the first carbon dioxide adsorption section (C1) or the second carbon dioxide adsorption section (C2), and at the same time, a desorption operation is performed in which air containing water desorbed from the adsorption heat exchanger (32, 34) of the first adsorption heat exchanger (32) or the second adsorption heat exchanger (34) that functions as a radiator is sent to the other of the first carbon dioxide adsorption section (C1) or the second carbon dioxide adsorption section (C2).

[0029] In the ninth aspect, in the first operation, air cooled in the evaporator is sent to one of the first carbon dioxide adsorption section (C1) and the second carbon dioxide adsorption section (C2), and simultaneously, air heated in the radiator and containing moisture is sent to the other of the first carbon dioxide adsorption section (C1) and the second carbon dioxide adsorption section (C2). As a result, the adsorption operation and the regeneration operation can be performed simultaneously.

[0030] In a tenth aspect, in any one of the sixth to eighth aspects, the control unit (100) performs an adsorption operation in which air cooled by the adsorption heat exchanger (32, 34) of the first adsorption heat exchanger (32) and the second adsorption heat exchanger (34) that functions as an evaporator is sent to one of the first carbon dioxide adsorption section (C1) and the second carbon dioxide adsorption section (C2), and simultaneously performs a drying operation in which air heated by the adsorption heat exchanger (32, 34) of the first adsorption heat exchanger (32) and the second adsorption heat exchanger (34) that functions as a radiator is sent to the other of the first carbon dioxide adsorption section (C1) and the second carbon dioxide adsorption section (C2).

[0031] In a tenth aspect, in the second operation, the air cooled by the evaporator is sent to one of the first carbon dioxide adsorption section (C1) and the second carbon dioxide adsorption section (C2), and at the same time, the air is heated by the radiator and sent to the other of the first carbon dioxide adsorption section (C1) and the second carbon dioxide adsorption section (C2). As a result, the adsorption operation and the drying operation can be performed simultaneously.

[0032] FIG. 1 is an overall configuration diagram of a carbon dioxide capture system according to an embodiment. FIG. 2 is a schematic piping diagram of a refrigerant circuit. FIG. 3 is a block diagram of a controller and major devices. FIG. 4 is a diagram corresponding to FIG. 1 for explaining a first operation of the adsorption operation. FIG. 5 is a diagram corresponding to FIG. 1 for explaining a second operation of the adsorption operation. FIG. 6 is a diagram corresponding to FIG. 1 for explaining a third operation of the desorption operation. FIG. 7 is a diagram corresponding to FIG. 1 for explaining a fourth operation of the desorption operation. FIG. 8 is a diagram corresponding to FIG. 1 for explaining a fifth operation of the drying operation. FIG. 9 is a diagram corresponding to FIG. 1 for explaining a sixth operation of the drying operation. FIG. 10 is an overall configuration diagram of a carbon dioxide capture system according to a modified example. FIG. 11 is a diagram corresponding to FIG. 10 for explaining a first operation (seventh operation). FIG. 12 is a diagram corresponding to FIG. 10 for explaining a second operation (ninth operation).

[0033] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the present disclosure is not limited to the embodiments shown below, and various modifications are possible within the scope of the technical concept of the present disclosure. Since the drawings are intended to conceptually explain the present disclosure, dimensions, ratios, or numbers may be exaggerated or simplified as necessary to facilitate understanding.

[0034] (1) Overall Configuration An embodiment of the present disclosure is a carbon dioxide capture system (1). The carbon dioxide capture system (1) captures carbon dioxide from the air. The carbon dioxide capture system (1) constitutes a DAC (Direct Air Capture) system that separates and captures carbon dioxide directly from outdoor air.

[0035] The carbon dioxide capture system (1) shown in Fig. 1 includes a casing (10), a first adsorption heat exchanger (32), a second adsorption heat exchanger (34), a first fan (36), a second fan (37), a flow path switching mechanism (40) (reference numerals are omitted in Fig. 1), a carbon dioxide adsorption section (C), and a capture mechanism (50). The carbon dioxide capture system (1) is a so-called humidity swing system that performs adsorption and desorption operations by adjusting the water content of the carbon dioxide adsorption section (C).

[0036] (1-1) Casing The casing (10) is installed outdoors. The casing (10) has an air flow path (P) through which outdoor air flows. The casing (10) is formed with a first suction port (11), a second suction port (12), a first discharge port (13), and a second discharge port (14). The first suction port (11), the second suction port (12), the first discharge port (13), and the second discharge port (14) are in communication with each other via the air flow path (P).

[0037] The first suction inlet (11) and the second suction inlet (12) open toward the outdoor space. The first suction inlet (11) and the second suction inlet (12) draw outdoor air from outside the casing (10) into the air flow path (P). The first discharge outlet (13) and the second discharge outlet (14) open toward the outdoor space. The first discharge outlet (13) and the second discharge outlet (14) discharge air from the air flow path (P) to the outdoor space.

[0038] A first humidity control chamber (15), a second humidity control chamber (16), an adsorption chamber (17), a first exhaust flow path (18), a relay flow path (19), and a second exhaust flow path (20) are formed inside the casing (10).

[0039] The first humidity control chamber (15) communicates with the first suction port (11). The first humidity control chamber (15) communicates with the adsorption chamber (17) through the first opening (O1). The first humidity control chamber (15) communicates with the relay flow path (19) through the second opening (O2). The second humidity control chamber (16) communicates with the second suction port (12). The second humidity control chamber (16) communicates with the adsorption chamber (17) through the third opening (O3). The second humidity control chamber (16) communicates with the second exhaust flow path (20) through the fourth opening (O4). The adsorption chamber (17) communicates with the first exhaust flow path (18) through the fifth opening (O5). The relay flow path (19) communicates with the second exhaust flow path (20) through a flow path not shown in FIG. 1 .

[0040] (1-2) Refrigerant Circuit The carbon dioxide capture system (1) of this embodiment has a refrigerant circuit (30). The refrigerant circuit (30) circulates a refrigerant to perform a refrigeration cycle. As shown in FIG. 2 , the refrigerant circuit (30) has a compressor (31), a first adsorption heat exchanger (32), an expansion valve (33), a second adsorption heat exchanger (34), and a four-way switching valve (35). The compressor (31) compresses a refrigerant and discharges the compressed refrigerant. The expansion valve (33) constitutes a pressure reduction mechanism that reduces the pressure of the refrigerant. The expansion valve (33) is an electronic expansion valve whose opening degree is variable. The four-way switching valve (35) is switchable between a first state indicated by a solid line in FIG. 2 and a second state indicated by a dashed line in FIG. 2 .

[0041] The first adsorption heat exchanger (32) and the second adsorption heat exchanger (34) each have a heat exchanger body and a water adsorption section (W) provided on the surface of the heat exchanger body. The heat exchanger body is a fin-and-tube heat exchanger. The water adsorption section (W) is made of a water adsorbent that adsorbs water. The water adsorbent is made of a polymer, silica gel, zeolite, alumina, or the like, and has the property of adsorbing water from the air. The water adsorbent has the property of desorbing the adsorbed water when heated.

[0042] The refrigerant circuit (30) performs a first refrigeration cycle and a second refrigeration cycle. In the first refrigeration cycle, the four-way switching valve (35) is in a first state. In the first refrigeration cycle, the refrigerant compressed by the compressor (31) dissipates heat in the first adsorption heat exchanger (32), is depressurized by the expansion valve (33), and evaporates in the second adsorption heat exchanger (34). In the second refrigeration cycle, the four-way switching valve (35) is in a second state. In the second refrigeration cycle, the refrigerant compressed by the compressor (31) dissipates heat in the second adsorption heat exchanger (34), is depressurized by the expansion valve (33), and evaporates in the first adsorption heat exchanger (32). The four-way switching valve (35) constitutes a refrigerant switching mechanism for switching between the first refrigeration cycle and the second refrigeration cycle in the refrigerant circuit (30).

[0043] (1-3) First Fan, Second Fan, and Flow Channel Switching Mechanism As shown in Fig. 1, the first fan (36) is disposed in the adsorption chamber (17), and the second fan (37) is disposed in the second exhaust flow channel (20). The first fan (36) and the second fan (37) transport air through the air flow channel (P).

[0044] The flow path switching mechanism (40) switches the air flow in the air flow path (P). The flow path switching mechanism (40) has a first damper (D1), a second damper (D2), a third damper (D3), a fourth damper (D4), and a fifth damper (D5). The first damper (D1) opens and closes the first opening (O1), the second damper (D2) opens and closes the second opening (O2), the third damper (D3) opens and closes the third opening (O3), the fourth damper (D4) opens and closes the fourth opening (O4), and the fifth damper (D5) opens and closes the fifth opening (O5). The flow path switching mechanism (40) switches the air flow path (P) between a first flow path state and a second flow path state.

[0045] In the air flow path (P) in the first flow path state, the first damper (D1) is in an open state, the second damper (D2) is in a closed state, the third damper (D3) is in a closed state, and the fourth damper (D4) is in an open state. The air flow path (P) in the first flow path state connects the first adsorption heat exchanger (32) and the carbon dioxide adsorption section (C). Specifically, in the air flow path (P) in the first flow path state, air that has passed through the first adsorption heat exchanger (32) (hereinafter also referred to as "first air") passes through the carbon dioxide adsorption section (C), and simultaneously, air that has passed through the second adsorption heat exchanger (34) (hereinafter also referred to as "second air") is discharged to the outside of the room without passing through the carbon dioxide adsorption section (C).

[0046] In the air flow path (P) in the second flow path state, the first damper (D1) is closed, the second damper (D2) is open, the third damper (D3) is open, and the fourth damper (D4) is closed. The air flow path (P) in the second flow path state connects the second adsorption heat exchanger (34) and the carbon dioxide adsorption section (C). In the air flow path (P) in the second flow path state, the air that has passed through the second adsorption heat exchanger (34) (hereinafter also referred to as second air) passes through the carbon dioxide adsorption section (C), and at the same time, the first air is discharged to the outside without passing through the carbon dioxide adsorption section (C).

[0047] (1-4) Carbon Dioxide Adsorption Unit The carbon dioxide adsorption unit (C) adsorbs carbon dioxide in the air. The carbon dioxide adsorption unit (C) has a substrate and a carbon dioxide adsorbent provided on the surface of the substrate. The substrate has a plurality of pores through which air can flow. The substrate is made of a ceramic material having a plurality of pores, a metal material having a plurality of pores, a porous member having a plurality of pores, metal fiber, carbon fiber, or the like.

[0048] The carbon dioxide adsorption section (C) has the property that its adsorption / desorption performance changes depending on its water content. The carbon dioxide adsorption section (C) becomes more likely to desorb carbon dioxide as its water content increases, and more likely to adsorb carbon dioxide as its water content decreases. Examples of carbon dioxide adsorbents with such properties include carbon dioxide absorption materials containing quaternary ammonium cations. More specifically, carbon dioxide adsorbents include QCPS (quaternized crosslinked polystyrene: porous type), PES (polyethersulfone), IER-PO4 (phosphate ion exchange resin), and QMPRs (quaternary ammonium functionalized mesoporous adsorbents).

[0049] (1-5) Recovery Mechanism The recovery mechanism (50) recovers carbon dioxide desorbed from the carbon dioxide adsorption section (C). The recovery mechanism (50) includes a recovery flow path (51), a pump (52), and a tank (53). One end of the recovery flow path (51) is connected to the adsorption chamber (17), and the other end of the recovery flow path (51) is connected to the tank (53). The pump (52) is provided in the recovery flow path (51). The pump (52) transports carbon dioxide from the recovery flow path (51). When the pump (52) is operated, the carbon dioxide desorbed from the carbon dioxide adsorption section (C) flows into the tank (53) through the recovery flow path (51). The tank (53) stores this carbon dioxide. The recovery mechanism (50) may introduce the desorbed carbon dioxide into another storage section, such as underground.

[0050] (2) Controller As shown in Fig. 3, the carbon dioxide capture system (1) has a controller (100) as a control unit. The controller (100) includes a microcomputer and a memory device that stores software for operating the microcomputer. The controller (100) controls the ON / OFF state of the compressor (31), the rotation speed of the compressor (31), the opening degree of the expansion valve (33), the state of the four-way switching valve (35), the open / closed states of the dampers (D1 to D5), the ON / OFF state of the first fan (36), and the ON / OFF state of the second fan (37).

[0051] (3) Operation Operation of the carbon dioxide capture system (1) will be described. In operation of the carbon dioxide capture system (1), carbon dioxide in the air is captured in a capture unit such as the tank (53). During operation of the carbon dioxide capture system (1), the controller (100) sequentially and repeatedly executes an adsorption operation, a desorption operation, and a drying operation. The adsorption operation is an operation in which moisture in the air is adsorbed by the water adsorption unit (W) and carbon dioxide in the air is adsorbed by the carbon dioxide adsorption unit (C). The desorption operation is an operation in which carbon dioxide adsorbed by the carbon dioxide adsorption unit (C) is desorbed by heating and the carbon dioxide is captured by the capture mechanism (50). In the desorption operation, water is supplied to the carbon dioxide adsorption unit (C). In other words, in the desorption operation, the moisture content of the carbon dioxide adsorption unit (C) increases. In the drying operation, the carbon dioxide adsorption unit (C) is dried. In other words, in the drying operation, the moisture content of the carbon dioxide adsorption unit (C) decreases. This makes it easier for the carbon dioxide adsorption section (C) to adsorb carbon dioxide in the next adsorption operation.

[0052] When a command to start operation is input to the controller (100), the controller (100) operates the carbon dioxide capture system (1). Specifically, the controller (100) first performs an adsorption operation.

[0053] (3-1) Adsorption Operation During the adsorption operation, the controller (100) operates the compressor (31), the first fan (36), and the second fan (37), and adjusts the opening of the expansion valve (33). During the adsorption operation, the controller (100) stops the pump (52) and opens the fifth damper (D5). During the adsorption operation, the recovery mechanism (50) does not operate. During the adsorption operation, the controller (100) alternately executes the first operation and the second operation. Details of the first operation and the second operation will be described. In the drawings illustrating each operation, the adsorption heat exchanger functioning as an evaporator is indicated by a dot, the adsorption heat exchanger functioning as a radiator is indicated by a hatched line, the first air is represented by a hollow arrow, and the second air is represented by a hatched arrow.

[0054] (3-1-1) First Operation In the first operation, the controller (100) sets the four-way switching valve (35) to the second state. In the first operation, the refrigerant circuit (30) performs the second refrigeration cycle. The controller (100) controls the flow path switching mechanism (40) so that the air flow path (P) is in the first flow path state.

[0055] As shown in FIG. 4 , primary air from the outside of the room flows into the first humidity control chamber (15) through the first inlet (11). In the first humidity control chamber (15), the primary air passes through the first adsorption heat exchanger (32) functioning as an evaporator. As a result, water in the primary air is adsorbed by the water adsorption section (W) of the first adsorption heat exchanger (32). The primary air is cooled and dehumidified by the first adsorption heat exchanger (32). The air from the first humidity control chamber (15) flows into the adsorption chamber (17) and passes through the carbon dioxide adsorption section (C). In the carbon dioxide adsorption section (C), carbon dioxide in the air is adsorbed by a carbon dioxide adsorbent. Here, the air is cooled and dehumidified by the first adsorption heat exchanger (32), thereby increasing the carbon dioxide adsorption capacity of the carbon dioxide adsorption section (C). The primary air that has passed through the carbon dioxide adsorption section (C) is discharged to the outside of the room through the first outlet (13).

[0056] The second air from the outside of the room flows into the second humidity control chamber (16) through the second inlet (12). In the second humidity control chamber (16), the second air passes through the second adsorption heat exchanger (34) functioning as a radiator. As a result, water is desorbed from the water adsorption section (W) of the second adsorption heat exchanger (34) and released into the second air. The air in the second humidity control chamber (16) flows through the second exhaust flow path (20) and is discharged to the outside of the room through the second exhaust port (14).

[0057] (3-1-2) Second Operation In the second operation, the controller (100) sets the four-way switching valve (35) to the first state. In the second operation, the refrigerant circuit (30) performs the first refrigeration cycle. The controller (100) controls the flow path switching mechanism (40) so that the air flow path (P) is in the second flow path state.

[0058] As shown in FIG. 5 , secondary air from the outside of the room flows into the second humidity control chamber (16) through the second inlet (12). In the second humidity control chamber (16), the secondary air passes through the second adsorption heat exchanger (34), which functions as an evaporator. As a result, water in the secondary air is adsorbed by the water adsorption section (W) of the second adsorption heat exchanger (34). The secondary air is cooled and dehumidified by the second adsorption heat exchanger (34). The air from the second humidity control chamber (16) flows into the adsorption chamber (17) and passes through the carbon dioxide adsorption section (C). In the carbon dioxide adsorption section (C), carbon dioxide in the air is adsorbed by a carbon dioxide adsorbent. Here, the air is cooled and dehumidified by the second adsorption heat exchanger (34), thereby increasing the carbon dioxide adsorption capacity of the carbon dioxide adsorption section (C). The secondary air that has passed through the carbon dioxide adsorption section (C) is discharged to the outside of the room through the first outlet (13).

[0059] The first air from the outside of the room flows into the first humidity control chamber (15) through the first inlet (11). In the first humidity control chamber (15), the first air passes through the first adsorption heat exchanger (32) functioning as a radiator. As a result, water is desorbed from the water adsorption section (W) of the first adsorption heat exchanger (32) and released into the first air. The air in the first humidity control chamber (15) flows through the relay flow path (19) and the second exhaust flow path (20) and is discharged to the outside of the room through the second exhaust port (14).

[0060] (3-2) Desorption Operation In the desorption operation, the controller (100) operates the compressor (31), the first fan (36), and the second fan (37), and adjusts the opening of the expansion valve (33). In the desorption operation, the controller (100) operates the pump (52) and closes the fifth damper (D5). In the desorption operation, the recovery mechanism (50) is activated. In the desorption operation, the controller (100) alternately executes the third operation and the fourth operation. The third operation and the fourth operation will be described in detail.

[0061] (3-2-1) Third Operation In the third operation, the controller (100) sets the four-way switching valve (35) to the first state. In the third operation, the refrigerant circuit (30) performs the first refrigeration cycle. The controller (100) controls the flow path switching mechanism (40) so that the air flow path (P) is in the first flow path state.

[0062] As shown in FIG. 6 , primary air from the outdoors flows into the first humidity control chamber (15) through the first inlet (11). In the first humidity control chamber (15), the primary air passes through the first adsorption heat exchanger (32), which functions as a radiator. In the first adsorption heat exchanger (32), water desorbed from the water adsorption section (W) is released into the primary air. The primary air is heated and humidified by the first adsorption heat exchanger (32). The air from the first humidity control chamber (15) flows into the adsorption chamber (17) and passes through the carbon dioxide adsorption section (C). As a result, water in the air is applied to the carbon dioxide adsorption section (C), causing carbon dioxide to be desorbed. The carbon dioxide desorbed from the carbon dioxide adsorption section (C) is sucked into the recovery passageway (51) by the pump (52) and recovered in the tank (53).

[0063] The second air from the outside of the room flows into the second humidity control chamber (16) through the second inlet (12). In the second humidity control chamber (16), the second air passes through the second adsorption heat exchanger (34) functioning as an evaporator. In the second adsorption heat exchanger (34), water in the air is adsorbed by the water adsorption section (W) of the second adsorption heat exchanger (34). The air in the second humidity control chamber (16) flows through the second exhaust flow path (20) and is discharged to the outside of the room through the second exhaust port (14).

[0064] (3-2-2) Fourth Operation In the fourth operation, the controller (100) sets the four-way switching valve (35) to the second state. In the fourth operation, the refrigerant circuit (30) performs the second refrigeration cycle. The controller (100) controls the flow path switching mechanism (40) so that the air flow path (P) is in the second flow path state.

[0065] As shown in FIG. 7 , the second air from the outside flows into the second humidity control chamber (16) through the second inlet (12). In the second humidity control chamber (16), the second air passes through the second adsorption heat exchanger (34), which functions as a radiator. In the second adsorption heat exchanger (34), water desorbed from the water adsorption section (W) is released into the second air. The second air is heated and humidified by the second adsorption heat exchanger (34). The air from the second humidity control chamber (16) flows into the adsorption chamber (17) and passes through the carbon dioxide adsorption section (C). As a result, water in the air is applied to the carbon dioxide adsorption section (C), causing carbon dioxide to be desorbed. The carbon dioxide desorbed from the carbon dioxide adsorption section (C) is sucked into the recovery passageway (51) by the pump (52) and recovered in the tank (53).

[0066] The first air from the outside of the room flows into the first humidity control chamber (15) through the first inlet (11). In the first humidity control chamber (15), the first air passes through the first adsorption heat exchanger (32) functioning as an evaporator. In the first adsorption heat exchanger (32), water in the air is adsorbed by the water adsorption section (W) of the first adsorption heat exchanger (32). The air in the first humidity control chamber (15) flows through the relay flow path (19) and the second exhaust flow path (20) and is discharged to the outside of the room through the second exhaust port (14).

[0067] (3-3) Drying Operation In the drying operation, the controller (100) operates the compressor (31), the first fan (36), and the second fan (37), and adjusts the opening of the expansion valve (33). In the drying operation, the controller (100) stops the pump (52) and opens the fifth damper (D5). In the drying operation, the recovery mechanism (50) does not operate.

[0068] The drying operation includes the following fifth and sixth operations: In the drying operation, the controller (100) executes only one of the following fifth and sixth operations.

[0069] (3-3-1) Fifth Operation In the fifth operation, the controller (100) sets the four-way switching valve (35) to the first state. In the fifth operation, the refrigerant circuit (30) performs the first refrigeration cycle. The controller (100) controls the flow path switching mechanism (40) so that the air flow path (P) is in the first flow path state.

[0070] As shown in Figure 8, primary air from the outdoors flows into the first humidity control chamber (15) through the first inlet (11). In the first humidity control chamber (15), the primary air passes through the first adsorption heat exchanger (32) functioning as a radiator. When the drying operation is performed continuously after the desorption operation, the amount of water in the water adsorption section (W) of the first adsorption heat exchanger (32) decreases, and water is no longer desorbed from the water adsorption section (W). As a result, the primary air is heated in the first adsorption heat exchanger (32), and the relative humidity of the primary air decreases.

[0071] The air in the first humidity control chamber (15) flows into the adsorption chamber (17) and passes through the carbon dioxide adsorption section (C). As a result, the moisture content of the carbon dioxide adsorption section (C) decreases, and the carbon dioxide adsorbent is dried. The first air that has passed through the carbon dioxide adsorption section (C) is discharged to the outside of the room through the first outlet (13).

[0072] The second air from the outside flows into the second humidity control chamber (16) through the second inlet (12). In the second humidity control chamber (16), the second air passes through the second adsorption heat exchanger (34) functioning as an evaporator. In the second adsorption heat exchanger (34), the heat of the second air is used to evaporate the refrigerant in the second adsorption heat exchanger (34). In other words, the heat of the second air is used to dry the first air and further to dry the carbon dioxide adsorption section (C). The air in the second humidity control chamber (16) flows through the second exhaust flow path (20) and is discharged to the outside of the room through the second exhaust port (14).

[0073] (3-3-2) Sixth Operation In the sixth operation, the controller (100) sets the four-way switching valve (35) to the second state. In the sixth operation, the refrigerant circuit (30) performs the first refrigeration cycle. The controller (100) controls the flow path switching mechanism (40) so that the air flow path (P) is in the second flow path state.

[0074] As shown in Figure 9, the second air from the outside flows into the second humidity control chamber (16) through the second inlet (12). In the second humidity control chamber (16), the second air passes through the second adsorption heat exchanger (34), which functions as a radiator. If the drying operation is performed continuously after the desorption operation, the amount of water in the water adsorption section (W) of the second adsorption heat exchanger (34) decreases, and water no longer desorbs from the water adsorption section (W). As a result, the second air is heated in the second adsorption heat exchanger (34), and the relative humidity of the second air decreases.

[0075] The air in the second humidity control chamber (16) flows into the adsorption chamber (17) and passes through the carbon dioxide adsorption section (C). As a result, the moisture content of the carbon dioxide adsorption section (C) decreases, and the carbon dioxide adsorbent is dried. The second air that has passed through the carbon dioxide adsorption section (C) is discharged to the outside of the room through the first outlet (13).

[0076] The first air from the outside of the room flows into the first humidity control chamber (15) through the first inlet (11). In the first humidity control chamber (15), the first air passes through the first adsorption heat exchanger (32) functioning as an evaporator. In the first adsorption heat exchanger (32), the heat of the first air is used to evaporate the refrigerant in the first adsorption heat exchanger (32). In other words, the heat of the first air is used to dry the second air and further to dry the carbon dioxide adsorption section (C). The air in the first humidity control chamber (15) flows through the relay flow path (19) and the second exhaust flow path (20) and is discharged to the outside of the room through the second exhaust port (14).

[0077] (3-5) Determination of Switching Between Operations (3-5-1) Adsorption Operation At the start of an adsorption operation, the controller (100) preferably switches the state of the four-way switching valve (35) in the immediately preceding drying operation, in other words, the direction of the refrigeration cycle. For example, when starting an adsorption operation during the fifth operation, the controller (100) executes the first operation. For example, when starting an adsorption operation during the sixth operation, the controller (100) executes the second operation. This allows the adsorption heat exchanger, which was a radiator in the drying operation, to function as an evaporator in the adsorption operation. As a result, the adsorption performance of the water adsorption section (W) can be fully demonstrated in the adsorption operation.

[0078] The execution time ΔT1 of the first operation and the execution time ΔT2 of the second operation may be the same or different. For example, ΔT1 and ΔT2 are set to about several minutes.

[0079] (3-5-2) Desorption Operation At the start of the desorption operation, the controller (100) preferably switches the state of the four-way switching valve (35) for the immediately preceding adsorption operation, in other words, the direction of the refrigeration cycle. For example, when the desorption operation is started during the first operation, the controller (100) executes the third operation. For example, when the desorption operation is started during the second operation, the controller (100) executes the fourth operation. This allows the adsorption heat exchanger, which served as an evaporator in the adsorption operation, to function as a radiator in the desorption operation. As a result, the desorption performance of the water adsorption section (W) can be fully demonstrated in the desorption operation.

[0080] The controller (100) starts the desorption operation, for example, when a predetermined total execution time ΔTa of the adsorption operation has elapsed, where ΔTa is set to be longer than ΔT1 and ΔT2, for example, about several hours.

[0081] The execution time ΔT3 of the third operation and the execution time ΔT4 of the fourth operation may be the same or different. ΔT3 is preferably longer than ΔT1 and ΔT2, and ΔT4 is preferably longer than ΔT1 and ΔT2. The overall execution time ΔTb of the desorption operation is preferably longer than ΔTa.

[0082] (3-5-3) Drying Operation At the start of the drying operation, the controller (100) preferably maintains the state of the four-way selector valve (35) from the immediately preceding desorption operation. For example, when the drying operation is started during the execution of the third operation, the controller (100) executes the fifth operation. For example, when the drying operation is started during the execution of the fourth operation, the controller (100) executes the sixth operation. This allows the adsorption heat exchanger, which served as a radiator in the desorption operation, to function as a radiator in the drying operation. As a result, the moisture content of the water adsorption section (W) can be quickly reduced, and the carbon dioxide adsorption section (C) can be quickly dried.

[0083] The controller (100) starts the drying operation when a predetermined first condition is met during the desorption operation. Here, the first condition is a condition indicating that desorption of carbon dioxide from the carbon dioxide adsorption section (C) has been completed. The first condition includes at least one of the following conditions: the execution time ΔTb of the desorption operation has exceeded a predetermined time ΔTbs; the carbon dioxide concentration in the adsorption chamber (17) has fallen to a predetermined concentration or less; the moisture content of the carbon dioxide adsorption section (C) has risen to a predetermined value or more; and other conditions. The controller (100) may change ΔTbs in accordance with the relative humidity of the outdoor air.

[0084] The controller (100) terminates the drying operation when a predetermined second condition is met during the drying operation. Here, the second condition is a condition indicating that the drying of the carbon dioxide adsorption section (C) has been completed.

[0085] The second condition includes at least one of the following: the total execution time ΔTc of the drying operation exceeds a predetermined time ΔTcs; the humidity in the adsorption chamber (17) falls to a predetermined value or less; the moisture content of the carbon dioxide adsorption section (C) falls to a predetermined value or less; and other conditions. The controller (100) may change ΔTcs in accordance with the relative humidity of the outdoor air.

[0086] The execution time ΔTc of the drying operation is preferably shorter than the execution time ΔTb of the desorption operation and the execution time ΔTa of the adsorption operation.

[0087] (4) Effects of the Embodiment (4-1) The carbon dioxide capture system (1) includes a carbon dioxide adsorption section (C), a water adsorption section (W), and a heat source (heat radiator (32, 34)). The carbon dioxide adsorption section (C) has an adsorbent having a property in which carbon dioxide adsorption / desorption performance changes depending on the water content, and is disposed in the air flow path (P). The water adsorption section (W) is disposed upstream of the carbon dioxide adsorption section (C) in the air flow path (P), and adsorbs water in the air in the air flow path (P). The radiator (32, 34) heats the water adsorption section (W) so that water is desorbed from the water adsorption section (W) into the air in the air flow path (P).

[0088] In this configuration, water in the air can be adsorbed by the water adsorption section (W). By heating the water adsorption section (W) using the radiators (32, 34), water can be desorbed from the water adsorption section (W) into the air. By sending the water-containing air to the carbon dioxide adsorption section (C), carbon dioxide can be easily desorbed from the carbon dioxide adsorption section (C).

[0089] In this way, in this embodiment, water in the air is used as the water for desorbing carbon dioxide from the carbon dioxide adsorption section (C), so a water source can be omitted. Note that if a water source is provided in the carbon dioxide capture system, the water source can be made smaller or the amount of water in the water source can be reduced.

[0090] The heat source (32, 34) is the radiator (32, 34) of the refrigerant circuit (30). This improves the energy saving of the carbon dioxide recovery system (1) compared to when an electric heater is used as the heat source, for example.

[0091] (4-2) The carbon dioxide capture system includes a capture mechanism (50) that captures carbon dioxide desorbed from the carbon dioxide adsorption section, and a control section (100) that controls a heating source (heat radiator (32, 34)) and the capture mechanism (50). The control section (100) executes an adsorption operation in which carbon dioxide in the air after water has been adsorbed by the water adsorption section (W) is adsorbed by the carbon dioxide adsorption section (C), and a desorption operation in which air containing water desorbed from the water adsorption section (W) that has been heated by the heat radiator (32, 34) is sent to the carbon dioxide adsorption section (C) and the carbon dioxide desorbed from the carbon dioxide adsorption section (C) is captured by the capture mechanism (50).

[0092] In this configuration, during the adsorption operation, the water adsorption unit (W) adsorbs water in the air. The carbon dioxide adsorption unit (C) adsorbs carbon dioxide in the air after the water has been adsorbed by the water adsorption unit (W). Here, the adsorbent of the carbon dioxide adsorption unit (C) has a property in which its carbon dioxide adsorption and desorption performance changes depending on its water content. Therefore, as the water content of the adsorbent decreases, carbon dioxide becomes more easily adsorbed by the carbon dioxide adsorption unit (C).

[0093] In the desorption operation, the radiator (32, 34) heats the water adsorption section (W), causing water to desorb from the water adsorption section (W). Air containing the desorbed water flows through the carbon dioxide adsorption section (C), causing carbon dioxide to desorb from the carbon dioxide adsorption section (C). The recovery mechanism (50) recovers the carbon dioxide desorbed from the carbon dioxide adsorption section (C).

[0094] (4-3) The adsorption operation is an operation of adsorbing carbon dioxide in the air cooled by the first adsorption heat exchanger (32) and the second adsorption heat exchanger (34), which function as evaporators, into the carbon dioxide adsorption section (C).

[0095] In this configuration, the first adsorption heat exchanger (32) and the second adsorption heat exchanger (34), which function as evaporators, cool the air during the adsorption operation. This improves the water adsorption capacity of the water adsorption section (W) during the adsorption operation. In addition, it improves the carbon dioxide adsorption capacity of the carbon dioxide adsorption section (C).

[0096] (4-4) The control unit (100) further executes a drying operation of drying the carbon dioxide adsorption section (C) with air heated by the first adsorption heat exchanger (32) and the second adsorption heat exchanger (34) functioning as radiators.

[0097] In this configuration, in the drying operation, the radiators (32, 34) heat the air, thereby reducing the humidity of the air. This air flows through the carbon dioxide adsorption section (C), thereby drying the carbon dioxide adsorption section (C). As a result, in the next adsorption operation, the carbon dioxide adsorption capacity of the carbon dioxide adsorption section (C) can be improved.

[0098] (4-5) The refrigerant circuit (30) includes a first adsorption heat exchanger (32) provided with a water adsorption section (W), a second adsorption heat exchanger (34) provided with the water adsorption section (W), and a refrigerant switching mechanism (35) that switches a flow path of the refrigerant circuit (30) to switch between a first refrigeration cycle in which the first adsorption heat exchanger (32) functions as a radiator and the second adsorption heat exchanger (34) functions as an evaporator and a second refrigeration cycle in which the second adsorption heat exchanger (34) functions as a radiator and the first adsorption heat exchanger (32) functions as an evaporator. The carbon dioxide recovery system further includes a flow path switching mechanism (40) that switches the air flow path (P) between a first flow path state in which the first adsorption heat exchanger (32) and the carbon dioxide adsorption section (C) communicate with each other and a second flow path state in which the second adsorption heat exchanger (34) and the carbon dioxide adsorption section (C) communicate with each other.

[0099] In this configuration, the first adsorption heat exchanger (32) and the second adsorption heat exchanger (34) can be used to continuously perform the adsorption operation and the desorption operation.

[0100] Specifically, the control unit (100) controls the refrigerant switching mechanism (35) and the flow path switching mechanism (40) to perform a first operation in which the refrigerant circuit (30) performs a second refrigeration cycle and simultaneously sets the air flow path (P) to a first flow path state during the adsorption operation, and a second operation in which the refrigerant circuit (30) performs a first refrigeration cycle and simultaneously sets the air flow path (P) to a second flow path state.

[0101] In this configuration, the first adsorption heat exchanger (32) and the second adsorption heat exchanger (34), which function as evaporators, cool and dehumidify the air before sending it to the carbon dioxide adsorption section (C), thereby increasing the adsorption capacity of the carbon dioxide adsorption section (C). At the same time, the first adsorption heat exchanger (32) and the second adsorption heat exchanger (34), which function as radiators, can regenerate the water adsorption section (W).

[0102] Furthermore, the control unit (100) controls the refrigerant switching mechanism (35) and the flow path switching mechanism (40) to perform a third operation in which the refrigerant circuit (30) performs a first refrigeration cycle and simultaneously sets the air flow path (P) to a first flow path state, and a fourth operation in which the refrigerant circuit (30) performs a second refrigeration cycle and simultaneously sets the air flow path (P) to a second flow path state, during the desorption operation.

[0103] In this configuration, the first adsorption heat exchanger (32) and the second adsorption heat exchanger (34), which function as radiators, heat and humidify the air before sending it to the carbon dioxide adsorption section (C), thereby increasing the desorption capacity of the carbon dioxide adsorption section (C). At the same time, the first adsorption heat exchanger (32) and the second adsorption heat exchanger (34), which function as evaporators, can adsorb moisture in the air to the water adsorption section (W).

[0104] (5) Modifications The above-described embodiment may be modified as follows: Differences from the embodiment will be described below.

[0105] 10 shows a modified carbon dioxide capture system (1) including a first adsorption chamber (17A), a second adsorption chamber (17B), and a sixth opening (O6) formed inside a casing (10). The first adsorption chamber (17A) corresponds to the adsorption chamber (17) of the above-described embodiment.

[0106] The first humidity control chamber (15) communicates with the first adsorption chamber (17A) through a first opening (O1). The second humidity control chamber (16) communicates with the first adsorption chamber (17A) through a third opening (O3). The second humidity control chamber (16) communicates with the second adsorption chamber (17B) through a fourth opening (O4). The first adsorption chamber (17A) communicates with the first exhaust flow path (18) through a fifth opening (O5). The relay flow path (19) communicates with the second adsorption chamber (17B) through a flow path not shown in FIG. 1 . The second adsorption chamber (17B) communicates with the second exhaust flow path (20) through a sixth opening (O6).

[0107] The second fan (37) is disposed in the second adsorption chamber (17B). The flow path switching mechanism (40) has a sixth damper (D6) which opens and closes the sixth opening (O6).

[0108] The carbon dioxide recovery system (1) has a first carbon dioxide adsorption section (C1) and a second carbon dioxide adsorption section (C2). The first carbon dioxide adsorption section (C1) corresponds to the carbon dioxide adsorption section (C) in the above-described embodiment and is disposed in the first adsorption chamber (17A). The second carbon dioxide adsorption section (C2) is disposed in the second adsorption chamber (17B).

[0109] The recovery mechanism (50) of the modified example includes a first recovery channel (51a), a second recovery channel (51b), and a merging channel (51c). The first recovery channel (51a) corresponds to the recovery channel (51) of the above-described embodiment. One end of the first recovery channel (51a) is connected to the first adsorption chamber (17A), and the other end of the first recovery channel (51a) is connected to one end of the merging channel (51c). One end of the second recovery channel (51b) is connected to the second adsorption chamber (17B), and the other end of the second recovery channel (51b) is connected to one end of the merging channel (51c). The other end of the merging channel (51c) is connected to a tank (53). A pump (52) is provided in the merging channel (51c). The recovery mechanism (50) includes a first on-off valve (54) and a second on-off valve (55). The first on-off valve (54) is provided in the first recovery passageway (51a), and the second on-off valve (55) is provided in the second recovery passageway (51b).

[0110] In the carbon dioxide capture system (1) of the modified example, the controller (100) executes a first operation and a second operation. The first operation is an operation in which an adsorption operation and a desorption operation are performed simultaneously. The second operation is an operation in which an adsorption operation and a drying operation are performed simultaneously.

[0111] (5-1) First Operation Fig. 11 is an example of the first operation. In the first operation (hereinafter also referred to as the seventh operation) of the example of Fig. 11, an adsorption operation is performed in the first carbon dioxide adsorption section (C1) and a desorption operation is performed in the second carbon dioxide adsorption section (C2). That is, in the seventh operation, an adsorption operation is performed in which air cooled by the first adsorption heat exchanger (32) functioning as an evaporator is sent to the first carbon dioxide adsorption section (C1), and a desorption operation is performed in which air containing water desorbed from the second adsorption heat exchanger (34) functioning as a radiator is sent to the second carbon dioxide adsorption section (C2).

[0112] More specifically, in the first operation, the controller (100) operates the compressor (31), the first fan (36), and the second fan (37), and adjusts the opening of the expansion valve (33). In the first operation, the controller (100) operates the pump (52). In the first operation, the recovery mechanism (50) is activated.

[0113] In the seventh operation, the controller (100) switches the four-way switching valve (35) to the second state. The refrigerant circuit (30) performs a second refrigeration cycle. The controller (100) controls the flow path switching mechanism (40) to switch the air flow path (P) to the first flow path state. In the seventh operation, the controller (100) opens the fifth damper (D5), closes the sixth damper (D6), closes the first on-off valve (54), and opens the second on-off valve (55). In the air flow path (P) in the first flow path state, the first damper (D1) is open, the second damper (D2) is closed, the third damper (D3) is closed, and the fourth damper (D4) is open. In a modified example, in the air flow path (P) in the first flow path state, the first air passes through the first carbon dioxide adsorption section (C1) while the second air passes through the second carbon dioxide adsorption section (C2).

[0114] The first air from the outside of the room flows into the first humidity control chamber (15) through the first inlet (11). In the first humidity control chamber (15), the first air passes through the first adsorption heat exchanger (32) functioning as an evaporator. As a result, water in the first air is adsorbed by the water adsorption section (W) of the first adsorption heat exchanger (32). The first air is cooled and dehumidified by the first adsorption heat exchanger (32). The air from the first humidity control chamber (15) flows into the first adsorption chamber (17A) and passes through the first carbon dioxide adsorption section (C1). In the first carbon dioxide adsorption section (C1), carbon dioxide in the air is adsorbed by a carbon dioxide adsorbent. The first air that has passed through the first carbon dioxide adsorption section (C1) is discharged to the outside of the room through the first outlet (13).

[0115] The second air from the outside of the room flows into the second humidity control chamber (16) through the second inlet (12). In the second humidity control chamber (16), the second air passes through the second adsorption heat exchanger (34), which functions as a radiator. As a result, water is desorbed from the water adsorption section (W) of the second adsorption heat exchanger (34) and released into the second air. The air from the second humidity control chamber (16) flows into the second adsorption chamber (17B) and passes through the second carbon dioxide adsorption section (C2). As a result, water in the air is applied to the second carbon dioxide adsorption section (C2), causing carbon dioxide to be desorbed. The carbon dioxide desorbed from the second carbon dioxide adsorption section (C2) is sucked into the second recovery flow path (51b) by the pump (52) and collected into the tank (53) through the merging flow path (51c).

[0116] The controller (100) may execute a first operation (hereinafter also referred to as an eighth operation) in which the first carbon dioxide adsorption section (C1) performs a desorption operation while the second carbon dioxide adsorption section (C2) performs an adsorption operation. That is, the eighth operation performs an adsorption operation in which air cooled by the second adsorption heat exchanger (34) functioning as an evaporator is sent to the first carbon dioxide adsorption section (C1), and simultaneously performs a desorption operation in which air containing water desorbed from the first adsorption heat exchanger (32) functioning as a radiator is sent to the first carbon dioxide adsorption section (C1). In the eighth operation, the controller (100) sets the four-way switching valve (35) to the first state. The refrigerant circuit (30) performs a first refrigeration cycle. The controller (100) controls the flow path switching mechanism (40) to set the air flow path (P) to the second flow path state. In the eighth operation, the controller (100) closes the fifth damper (D5), opens the sixth damper (D6), opens the first on-off valve (54), and closes the second on-off valve (55). In a modified example, in the air flow path (P) in the second flow path state, the first air passes through the second carbon dioxide adsorption section (C2) and, at the same time, the second air passes through the first carbon dioxide adsorption section (C1).

[0117] (5-2) Second Operation Fig. 12 is an example of the second operation. In the second operation (hereinafter also referred to as the ninth operation) in the example of Fig. 12, an adsorption operation is performed in the first carbon dioxide adsorption section (C1) and a drying operation is performed in the second carbon dioxide adsorption section (C2). That is, in the ninth operation, an adsorption operation is performed in which air cooled by the first adsorption heat exchanger (32) functioning as an evaporator is sent to the first carbon dioxide adsorption section (C1), and a drying operation is performed in which the second carbon dioxide adsorption section (C2) is dried with air heated by the second adsorption heat exchanger (34) functioning as a radiator.

[0118] More specifically, in the second operation mode, the controller (100) operates the compressor (31), the first fan (36), and the second fan (37), and adjusts the opening of the expansion valve (33). In the second operation mode, the controller (100) stops the pump (52) and opens the fifth damper (D5) and the sixth damper (D6). In the second operation mode, the recovery mechanism (50) does not operate.

[0119] In the ninth operation, the controller (100) switches the four-way switching valve (35) to the second state. The refrigerant circuit (30) performs a second refrigeration cycle. The controller (100) controls the flow path switching mechanism (40) so that the air flow path (P) is in the first flow path state.

[0120] The first air from the outside of the room flows into the first humidity control chamber (15) through the first inlet (11). In the first humidity control chamber (15), the first air passes through the first adsorption heat exchanger (32) functioning as an evaporator. As a result, water in the first air is adsorbed by the water adsorption section (W) of the first adsorption heat exchanger (32). The first air is cooled and dehumidified by the first adsorption heat exchanger (32). The air from the first humidity control chamber (15) flows into the first adsorption chamber (17A) and passes through the first carbon dioxide adsorption section (C1). In the first carbon dioxide adsorption section (C1), carbon dioxide in the air is adsorbed by a carbon dioxide adsorbent. The first air that has passed through the first carbon dioxide adsorption section (C1) is discharged to the outside of the room through the first outlet (13).

[0121] The second air from the outside flows into the second humidity control chamber (16) through the second inlet (12). In the second humidity control chamber (16), the second air passes through the second adsorption heat exchanger (34), which functions as a radiator. When the drying operation is performed continuously, the amount of water in the water adsorption section (W) of the second adsorption heat exchanger (34) decreases, and water no longer desorbs from the water adsorption section (W). As a result, the second air is heated in the second adsorption heat exchanger (34), and the relative humidity of the second air decreases.

[0122] The air in the second humidity control chamber (16) flows into the second adsorption chamber (17B) and passes through the second carbon dioxide adsorption section (C2). As a result, the moisture content of the second carbon dioxide adsorption section (C2) decreases, and the adsorbed carbon dioxide is dried. The second air that has passed through the second carbon dioxide adsorption section (C2) is discharged to the outside of the room through the second outlet (14).

[0123] The controller (100) may execute a second operation (hereinafter also referred to as a tenth operation) in which the second carbon dioxide adsorption section (C2) performs an adsorption operation while the first carbon dioxide adsorption section (C1) performs a drying operation. That is, the tenth operation performs an adsorption operation in which air cooled by the second adsorption heat exchanger (34) functioning as an evaporator is sent to the second carbon dioxide adsorption section (C2), while simultaneously performing a drying operation in which the first carbon dioxide adsorption section (C1) is dried with air heated by the first adsorption heat exchanger (32) functioning as a radiator. In the tenth operation, the controller (100) sets the four-way switching valve (35) to the first state. The controller (100) controls the flow path switching mechanism (40) to set the air flow path (P) to the second flow path state.

[0124] (6) Other Embodiments The carbon dioxide capture system (1) does not have to be a DAC system that directly captures carbon dioxide from the atmosphere. For example, the carbon dioxide capture system (1) may capture carbon dioxide from a mixture of air and industrial exhaust gas.

[0125] The carbon dioxide adsorption unit (C) may adsorb carbon dioxide in indoor air instead of outdoor air. The carbon dioxide adsorption unit (C) may be applied to, for example, a ventilation system that ventilates a room.

[0126] The refrigerant switching mechanism (35) does not have to be a four-way switching valve, but may be configured by combining a plurality of on-off valves or a plurality of three-way valves.

[0127] The flow path switching mechanism (40) may be something other than a damper, and may be a slide shutter or a valve such as a ball valve for switching the air flow.

[0128] The capture mechanism (50) may introduce the captured carbon dioxide into the ground. In other words, the capture unit that captures the carbon dioxide may be soil.

[0129] The water adsorption section (W) does not have to be provided in the adsorption heat exchanger (32, 34). The water adsorption section (W) may be, for example, a substrate through which air passes and a water adsorbent supported on the surface of the substrate. The water adsorption section (W) may be a rotary adsorption rotor.

[0130] The heat source for heating the water adsorption section (W) may be a radiator separate from the water adsorption section, or an electric heater.

[0131] The cooling source for cooling the water adsorption portion (W) may be an evaporator separate from the water adsorption portion, or a Peltier element.

[0132] The carbon dioxide capture system (1) may have a cooling unit that cools the air, a water recovery unit that recovers water condensed from the air cooled by the cooling unit, and a water supply unit that supplies the water recovered in the water recovery unit to the carbon dioxide adsorption unit (C). The carbon dioxide capture system (1) may also have a separate water supply source that supplies water to the carbon dioxide adsorption unit (C). In this case, too, the water supply source can be made smaller by using water in the air.

[0133] The casing (10) of the above-described embodiment and modified examples may have one suction inlet for drawing in the target air, and the air drawn in through the suction inlet may be diverted to the two humidity control chambers (15, 16).

[0134] Although the embodiments and modifications have been described above, it will be understood that various modifications in form and details are possible without departing from the spirit and scope of the claims. Furthermore, the above embodiments, modifications, and other embodiments may be combined or substituted as appropriate as long as the functionality of the subject matter of the present disclosure is not impaired.

[0135] The above-mentioned descriptions such as "first," "second," "third," etc. are used to distinguish the words to which these descriptions are attached, and do not limit the number or order of the words.

[0136] As described above, the present disclosure is useful for carbon dioxide capture systems.

[0137] 1 Carbon dioxide recovery system 30 Refrigerant circuit 31 Compressor 32 First adsorption heat exchanger 32, 34 Heat source (radiator) 34 Second adsorption heat exchanger 34, 32 Evaporator 35 Four-way switching valve (refrigerant switching mechanism) 40 Flow path switching mechanism 50 Recovery mechanism 100 Controller (control part) C Carbon dioxide adsorption part C1 First carbon dioxide adsorption part C2 Second carbon dioxide adsorption part P Air flow path W Water adsorption part

Claims

1. A carbon dioxide recovery system comprising: a carbon dioxide adsorption unit (C) having an adsorbent whose carbon dioxide adsorption / desorption performance changes depending on the water content and disposed in an air flow path (P); a water adsorption unit (W) disposed in the air flow path (P) upstream of the carbon dioxide adsorption unit (C) and adsorbing water in the air in the air flow path (P); and a heat source (32, 34) that heats the water adsorption unit (W) so that water is desorbed from the water adsorption unit (W) into the air in the air flow path (P).

2. The carbon dioxide capture system according to claim 1, comprising: a capture mechanism (50) that captures carbon dioxide desorbed from the carbon dioxide adsorption section (C); and a control section (100) that controls the heat source (32, 34) and the capture mechanism (50), wherein the control section (100) executes an adsorption operation in which the carbon dioxide adsorption section (C) adsorbs carbon dioxide in the air after water has been adsorbed by the water adsorption section (W), and a desorption operation in which air containing water desorbed from the water adsorption section (W) that has been heated by the heat source (32, 34) is sent to the carbon dioxide adsorption section (C) and the carbon dioxide desorbed from the carbon dioxide adsorption section (C) is captured by the capture mechanism (50).

3. The carbon dioxide capture system according to claim 2, further comprising a refrigerant circuit (30) having a compressor (31), a radiator (32, 34) as the heat source, an expansion mechanism (33), and an evaporator (34, 32), in which a refrigerant circulates to perform a refrigeration cycle.

4. The carbon dioxide capture system according to claim 3, wherein the adsorption operation is an operation of adsorbing carbon dioxide in the air cooled by the evaporator (34, 32) in the carbon dioxide adsorption section (C).

5. The carbon dioxide capture system according to claim 3 or 4, wherein the control unit (100) further executes a drying operation of drying the carbon dioxide adsorption unit (C) with air heated by the radiator (32, 34).

6. The refrigerant circuit (30) comprises: a first adsorption heat exchanger (32) provided with the water adsorption section (W); a second adsorption heat exchanger (34) provided with the water adsorption section (W); and a refrigerant switching mechanism (35) for switching a flow path of the refrigerant circuit (30) so as to switch between a first refrigeration cycle in which the first adsorption heat exchanger (32) functions as the radiator and the second adsorption heat exchanger (34) functions as the evaporator, and a second refrigeration cycle in which the second adsorption heat exchanger (34) functions as the radiator and the first adsorption heat exchanger (32) functions as the evaporator, and further comprises a flow path switching mechanism (40) for switching the air flow path (P) between a first flow path state in which the first adsorption heat exchanger (32) and the carbon dioxide adsorption section (C) communicate with each other, and a second flow path state in which the second adsorption heat exchanger (34) and the carbon dioxide adsorption section (C) communicate with each other. The carbon dioxide recovery system according to any one of claims 3 to 5.

7. The carbon dioxide capture system according to claim 6, wherein the control unit (100) controls the refrigerant switching mechanism (35) and the flow path switching mechanism (40) so as to perform, in the adsorption operation, a first operation in which the refrigerant circuit (30) performs the second refrigeration cycle and simultaneously sets the air flow path (P) to the first flow path state, and a second operation in which the refrigerant circuit (30) performs the first refrigeration cycle and simultaneously sets the air flow path (P) to the second flow path state.

8. The carbon dioxide capture system according to claim 6 or 7, wherein the control unit (100) controls the refrigerant switching mechanism (35) and the flow path switching mechanism (40) to perform, in the desorption operation, a third operation in which the refrigerant circuit (30) performs the first refrigeration cycle and simultaneously sets the air flow path (P) to the first flow path state, and a fourth operation in which the refrigerant circuit (30) performs the second refrigeration cycle and simultaneously sets the air flow path (P) to the second flow path state.

9. The carbon dioxide capture system according to any one of claims 6 to 8, wherein the carbon dioxide adsorption section (C) includes a first carbon dioxide adsorption section (C1) and a second carbon dioxide adsorption section (C2), and the control section (100) performs the adsorption operation of sending air cooled by the adsorption heat exchanger (32, 34) of the first adsorption heat exchanger (32) or the second adsorption heat exchanger (34) functioning as an evaporator to one of the first carbon dioxide adsorption section (C1) or the second carbon dioxide adsorption section (C2), and simultaneously performs the desorption operation of sending air containing water desorbed from the adsorption heat exchanger (32, 34) of the first adsorption heat exchanger (32) or the second adsorption heat exchanger (34) functioning as a radiator to the other of the first carbon dioxide adsorption section (C1) or the second carbon dioxide adsorption section (C2).

10. The carbon dioxide capture system according to any one of claims 6 to 8, wherein the carbon dioxide adsorption section (C) includes a first carbon dioxide adsorption section (C1) and a second carbon dioxide adsorption section (C2), and the control section (100) performs the adsorption operation of sending air cooled by the adsorption heat exchanger (32, 34) of the first adsorption heat exchanger (32) or the second adsorption heat exchanger (34) functioning as an evaporator to one of the first carbon dioxide adsorption section (C1) and the second carbon dioxide adsorption section (C2), and simultaneously performs a second operation of performing a drying operation of sending air heated by the adsorption heat exchanger (32, 34) of the first adsorption heat exchanger (32) or the second adsorption heat exchanger (34) functioning as a radiator to the other of the first carbon dioxide adsorption section (C1) and the second carbon dioxide adsorption section (C2).

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