DAC device

Abstract

A DAC device (100) for recovering CO2 in the atmosphere comprises: an adsorption chamber (R) provided with an adsorbent that adsorbs or absorbs CO2 and water; a recovery vacuum pump (5) that is connected to the adsorption chamber (R) via a recovery vacuum pipe (50) and suctions a desorbed gas from the adsorbent; a gas-liquid separator (8) that is provided in the recovery vacuum pipe (50) and separates water from the desorbed gas; and a water tank (81) that stores the water separated by the gas-liquid separator (8).

Description

DAC apparatus

[0001] The present invention relates to a DAC (Direct Air Capture) apparatus that captures carbon dioxide (CO2) in the atmosphere.

[0002] For the purpose of mitigating climate change, research and development on DAC technology for capturing CO2, which is a major greenhouse gas, is being conducted. As such DAC technology, a DAC apparatus that captures CO2 in the atmosphere using an adsorbent that adsorbs or absorbs CO2 is known. For example, in the DAC apparatus disclosed in Patent Document 1, atmospheric air is circulated through an adsorption chamber provided with an adsorbent to allow the adsorbent to adsorb CO2 in the atmosphere, then the pressure inside the adsorption chamber is reduced using a vacuum pump to desorb CO2 from the adsorbent, thereby collecting desorbed gas with a high CO2 concentration.

[0003] Japanese Unexamined Patent Publication No. 2024-048937

[0004] However, when CO2 is captured using a vacuum pump as in the DAC apparatus described in Patent Document 1, the pump efficiency decreases due to water desorbed together with CO2, which may reduce the CO2 capture efficiency of the entire apparatus.

[0005] A DAC apparatus for capturing CO2 in the atmosphere which is one aspect of the present invention comprises: an adsorption chamber provided with an adsorbent that adsorbs or absorbs CO2 and water; a recovery vacuum pump connected to the adsorption chamber via a recovery vacuum pipe and sucking desorbed gas from the adsorbent; a gas-liquid separator provided in the recovery vacuum pipe and separating water from the desorbed gas; and a water tank that stores water separated by the gas-liquid separator.

[0006] According to the present invention, the CO2 capture efficiency of the DAC apparatus can be improved.

[0007] A block diagram schematically showing an example of the piping configuration of a DAC apparatus according to an embodiment of the present invention. A block diagram schematically showing an example of the piping configuration around a gas-liquid separator provided in the vacuum piping of FIG. 1. A diagram for explaining the gas-liquid separator of FIG. 2.

[0008] Embodiments of the present invention will be described below with reference to Figures 1 to 3. Figure 1 is a schematic block diagram showing an example of the piping configuration of a DAC device 100 according to an embodiment of the present invention. As shown in Figure 1, the DAC device 100 mainly comprises a plurality of reactors R (Ra, Rb, ...) provided with an adsorbent material for adsorbing or absorbing CO2.

[0009] The reactor R has a housing capable of forming a sealed space (adsorption chamber) inside, and an adsorbent is provided in the adsorption chamber of the reactor R. As the adsorbent, a solid material can be used that is configured to adsorb CO2 at room temperature and pressure and desorb CO2 as the temperature rises. For example, an amine-based solid absorbent, in which an amine-based compound is supported on a suitable carrier, can be used. Such an adsorbent also adsorbs or absorbs water in addition to CO2. The adsorbent is configured in a suitable granular form and is filled into, for example, a mesh-structured filter cartridge and housed in the adsorption chamber of the reactor R.

[0010] The reactor R is provided with atmospheric control valves 1 (1a, 1b, ...) and 2 (2a, 2b, ...) for opening or closing the reactor R to the atmosphere. The atmospheric control valves 1 and 2 may be provided in the piping connecting the adsorption chamber of the reactor R to the outside space, or they may be provided as part of the housing (wall) of the reactor R. When atmospheric control valves 1 and 2 are opened, the adsorption chamber of the reactor R is opened to the atmosphere, and when atmospheric control valves 1 and 2 are closed, the adsorption chamber of the reactor R is sealed. Atmospheric control valves 1 and 2 are provided facing each other with the adsorption chamber in between.

[0011] A fan 3 is connected to the reactor R via either of the atmospheric control valves 1 or 2 (atmospheric control valve 2 in the illustrated example) and appropriate piping (atmospheric piping) 30 to circulate air into the adsorption chamber of the reactor R. In the illustrated example, when atmospheric control valves 1 and 2 are opened and the fan 3 is driven, air is drawn into the reactor R via atmospheric control valve 1, and air is exhausted from the reactor R via atmospheric control valve 2, atmospheric piping 30, and fan 3. As air circulates through the reactor R, CO2 from the air is adsorbed onto the adsorbent material in the adsorption chamber (adsorption stroke). The atmospheric control valves 1 and 2 and the atmospheric piping 30 are configured to have a relatively large diameter so that a large amount of air can circulate through the reactor R. Multiple atmospheric control valves 1 and 2 may be provided.

[0012] Vacuum piping 40 is further connected to the reactor R. The vacuum piping 40 connects the adsorption chamber of the reactor R to the intake port of the vacuum pump 4. More specifically, the vacuum piping 40 includes individual pipes 41 (41a, 41b, ...) that communicate with the adsorption chamber of each reactor R, and a merging pipe 42 that merges the individual pipes 41 and connects the individual pipes 41 to the vacuum pump 4 by communicating with the intake port of the vacuum pump 4.

[0013] Each individual pipe 41 is provided with a vacuum control valve 43 (43a, 43b, ...) that allows or prohibits the flow of gas in the individual pipe 41, i.e., the flow from the reactor R to the vacuum pipe 40. The vacuum control valve 43 may be composed of an on / off valve such as a ball valve, a control valve such as a butterfly valve, or a combination of these.

[0014] When the adsorption process is complete, the atmospheric control valves 1 and 2 are closed and the vacuum control valve 43 is opened, and the gas in the adsorption chamber of the reactor R is drawn out by the vacuum pump 4 via the vacuum piping 40 and exhausted. As a result, the remaining atmosphere in the adsorption chamber of the reactor R, more specifically, gases that have not been adsorbed by the adsorbent material such as oxygen, is drawn out of the reactor R and degassed, and the pressure inside the adsorption chamber of the reactor R is reduced from normal pressure (atmospheric pressure) to the final pressure reached by the vacuum pump 4 (degassing process).

[0015] Vacuum piping 50 is further connected to the reactor R. The vacuum piping 50 connects the adsorption chamber of the reactor R to the intake port of the vacuum pump 5. A storage tank 6 is connected to the exhaust port of the vacuum pump 5 via appropriate piping. More specifically, the vacuum piping 50 includes individual pipes 51 (51a, 51b, ...) that communicate with the adsorption chambers of each reactor R, and a merging pipe 52 that merges the individual pipes 51 and connects the individual pipes 51 to the vacuum pump 5 by communicating with the intake port of the vacuum pump 5.

[0016] Each individual pipe 51 is provided with a vacuum control valve 53 (53a, 53b, ...) that allows or prohibits the flow of gas in the individual pipe 51, i.e., the flow from the reactor R to the vacuum pipe 50. The vacuum control valve 53, like the vacuum control valve 43, may be made up of an on / off valve such as a ball valve, or a control valve such as a butterfly valve, or a combination of these.

[0017] The reactor R is also provided with a heating device for heating the adsorbent and a cooling device for cooling the adsorbent. For example, heat exchangers 7 (7a, 7b, ...) are provided for heating or cooling the adsorbent.

[0018] When the degassing process is complete, the atmospheric control valves 1 and 2 and the vacuum control valve 43 are closed, and the vacuum control valve 53 is opened. The heat exchanger 7 heats the adsorbent in the adsorption chamber, and the vacuum pump 5 draws out the gas in the adsorption chamber of the reactor R via the vacuum piping 50. As a result, the CO2 adsorbed on the adsorbent in the reactor R is desorbed, and the desorbed gas, mainly containing the desorbed CO2, is drawn out of the reactor R and stored in the storage tank 6 for recovery, while the pressure inside the adsorption chamber is maintained near the final target pressure of the vacuum pump 5 (degassing process).

[0019] Once the desorption process is complete, the atmospheric control valves 1 and 2 and the vacuum control valves 43 and 53 are closed, and the adsorbent in the adsorption chamber is cooled by the heat exchanger 7 (cooling process). When the adsorbent is heated during the desorption process, if the adsorbent becomes hot while oxygen is present in the adsorption chamber, there is a risk of oxidative degradation of the adsorbent. By starting the desorption process, in which residual air containing oxygen is removed in the degassing process before heating the adsorbent, and by starting the adsorption process, in which the adsorbent is cooled in the cooling process after the desorption process before air is circulated into the adsorption chamber, oxidative degradation of the adsorbent can be prevented.

[0020] The DAC device 100 is equipped with a controller 10 that controls each part of the DAC device 100, including atmospheric control valves 1 and 2, a fan 3, vacuum pumps 4 and 5, a heat exchanger 7, and vacuum control valves 43 and 53. The controller 10 is composed of a computer having a CPU, ROM, RAM, I / O interface, and other peripheral circuits. The controller 10 controls each part of the DAC device 100 so that the adsorption process, degassing process, desorption process, and cooling process in the multiple reactors R are performed sequentially with time staggers.

[0021] More specifically, with the fan 3 and vacuum pumps 4 and 5 running, the DAC device 100 controls each part such that during the adsorption stroke the atmospheric control valves 1 and 2 are opened and the vacuum control valves 43 and 53 are closed, during the degassing stroke the atmospheric control valves 1 and 2 and vacuum control valve 53 are closed and vacuum control valve 43 is opened, during the degassing stroke the atmospheric control valves 1 and 2 and vacuum control valve 43 are closed and vacuum control valve 53 is opened while the adsorbent is heated, and during the cooling stroke the atmospheric control valves 1 and 2 and vacuum control valves 43 and 53 are closed while the adsorbent is cooled.

[0022] In the desorption process, CO2 and water adsorbed on the adsorbent are desorbed. More specifically, when the temperature of the adsorbent reaches the desorption temperature of water (for example, around 70°C), water is desorbed, and then when it reaches the desorption temperature of CO2, which is higher than the desorption temperature of water (for example, around 100°C), CO2 is desorbed. Therefore, in this embodiment, a gas-liquid separator is provided in the vacuum piping 50 to remove water from the desorbed gas, and the pump efficiency of the vacuum pump 5 is improved, thereby improving the overall CO2 recovery efficiency of the apparatus. The DAC apparatus 100 is configured as follows.

[0023] Figure 2 is a schematic block diagram showing an example of the piping configuration around a gas-liquid separator 8 installed in the vacuum piping 50, and Figure 3 is a diagram for explaining the gas-liquid separator 8. The gas-liquid separator 8 may be installed in the confluence pipe 52 immediately before the vacuum pump 5 in the vacuum piping 50 of Figure 1, or it may be installed in the individual pipes 51 of each reactor R. When multiple reactors R are grouped together as a reactor group, and a group confluence pipe is provided that connects the individual pipes 51 of each reactor group to the confluence pipe 52, the gas-liquid separator 8 may be installed in the group confluence pipe.

[0024] As shown in Figures 2 and 3, the gas-liquid separator 8 is installed in the vacuum piping 50 between the reactor R and the vacuum pump 5 for CO2 recovery, and separates water from the desorbed gas. Hereinafter, the vacuum pump 5 for CO2 recovery may be referred to as the "recovery vacuum pump," and the vacuum piping 50 may be referred to as the "recovery vacuum piping." The gas-liquid separator 8 is a condenser such as a plate heat exchanger that cools and condenses the water vapor in the desorbed gas with a refrigerant such as water, and a flow path is formed inside through which the refrigerant from the cooler 9 and the desorbed gas from the vacuum piping 50 flow alternately.

[0025] A first water tank 81 is connected to the vacuum piping 50 immediately downstream of the gas-liquid separator 8 via an appropriate branch pipe 80, and the water separated by the gas-liquid separator 8 is stored in the first water tank 81. The branch pipe 80 connects the vacuum piping 50 to the top surface of the first water tank 81. The first water tank 81 is equipped with a water level sensor 11 for detecting the water level of condensed water stored in the first water tank 81 and a pressure sensor 12 for detecting the pressure of the gas phase in the first water tank 81. The detected values ​​from the water level sensor 11 and the pressure sensor 12 are transmitted to the controller 10.

[0026] By installing a gas-liquid separator 8 in the vacuum piping 50 between the reactor R and the vacuum pump 5, water (water vapor) can be separated and removed from the desorbed gas. This allows the pressure of the desorbed gas in the vacuum piping 50 to be reduced in proportion to the partial pressure of the water vapor removed by the gas-liquid separator 8. This improves the pumping efficiency of the vacuum pump 5 and the CO2 recovery efficiency, especially in the first half of the desorbing process when the amount of water desorbed is large, thereby improving the overall CO2 recovery efficiency of the system. Furthermore, by removing moisture from the desorbed gas before recovery, the concentration of CO2 recovered in the storage tank 6 can be further increased. Additionally, by using a heat exchanger as the gas-liquid separator 8, water can be separated from the desorbed gas with a simple configuration.

[0027] As shown in Figure 3, the gas-liquid separator 8 and the first water tank 81 are insulated. As a result, when condensed water vaporizes (re-evaporates) in the gas-liquid separator 8 and the first water tank 81, the heat of vaporization lowers the temperature of the gas-liquid separator 8 and the first water tank 81, causing the water vapor to condense immediately, and suppressing the overall re-evaporation of condensed water. In addition, since the gas-liquid separator 8 and the first water tank 81 are maintained at extremely low temperatures (for example, around 0°C), extremely low-temperature condensed water is stored, and this extremely low-temperature condensed water can be used to cool other equipment (for example, vacuum pumps 4 and 5). Alternatively, only one of the gas-liquid separator 8 and the first water tank 81, for example, only the first water tank 81, may be insulated. Even in this case, the re-evaporation of condensed water can be suppressed.

[0028] As shown in Figure 2, a second water tank 82 is connected to the vacuum piping 40 between the reactor R and the vacuum pump 4 for degassing via a suitable branch pipe 44. Hereinafter, the vacuum pump 4 for degassing may be referred to as the "vacuum pump for degassing," and the vacuum piping 40 as the "vacuum piping for degassing." The branch pipe 44 connects the vacuum piping 40 to the top surface of the second water tank 82. The second water tank 82 is equipped with a water level sensor 13 for detecting the water level of condensed water stored in the second water tank 82, and a pressure sensor 14 for detecting the pressure of the gas phase in the second water tank 82. The detected values ​​from the water level sensor 13 and the pressure sensor 14 are transmitted to the controller 10.

[0029] The second water tank 82 is positioned below the first water tank 81 in the direction of gravity. The lower part of the first water tank 81 and the upper part of the side of the second water tank 82 are connected by a connecting passage 83, and the liquid phase of the first water tank 81 and the gas phase of the second water tank 82 are in communication through the connecting passage 83. This allows the condensed water stored in the first water tank 81 to be transferred to the second water tank 82 by gravity via the connecting passage 83. The condensed water transferred from the first water tank 81 to the second water tank 82 is stored in the second water tank 82.

[0030] The second water tank 82 is connected to the vacuum piping 40 via a branch pipe 44 connected to its top surface, and to the first water tank 81 via a connecting passage 83 connected to the upper part of its side surface. By connecting the branch pipe 44 above the connecting passage 83 in this way, it is possible to reliably prevent condensed water transferred from the first water tank 81 to the second water tank 82 from flowing into the vacuum piping 40 via the branch pipe 44.

[0031] As shown in Figure 2, the connecting passage 83 may connect the lower part of the side surface of the first water tank 81 to the upper part of the side surface of the second water tank 82, or it may connect the bottom surface of the first water tank 81 to the upper part of the side surface of the second water tank 82. Furthermore, as shown in Figure 2, the connecting passage 83 may be provided to extend horizontally, to extend vertically, or to be inclined.

[0032] The connecting passage 83 is provided with a check valve 84 and an on-off valve (control valve) 85 to block the flow of fluid from the second water tank 82 to the first water tank 81. An on-off valve (control valve) 86 is provided in the branch piping 44. A pressure-recovering valve (control valve) 87 is provided on the upper surface of the second water tank 82, and a drain valve (control valve) 88 is provided on the lower part of the second water tank 82. The drain valve 88 may be provided on the side of the second water tank 82 as shown in Figure 2, or on the lower surface of the second water tank 82. The pressure-recovering valve 87 and the drain valve 88 may be provided in the piping connecting the storage space of the second water tank 82 to the outside space as shown in Figure 2, or they may be provided directly on the wall surface of the second water tank 82.

[0033] Control valves 85 to 88 are controlled by controller 10. More specifically, on-off valve 85 is opened when the water level in the first water tank 81 detected by the water level sensor 11 exceeds the lower limit water level, and the second water tank 82 is in communication with the vacuum piping 40 for degassing.

[0034] When the DAC device 100 is started, the controller 10 drives the fan 3 and vacuum pumps 4 and 5, and controls the control valves 1, 2, 43, 53, 85-88, so that the vacuum piping 40 and 50 are always maintained near the final pressure reached by the vacuum pumps 4 and 5. Residual air from the reactor R during the degassing process flows periodically into the degassing vacuum piping 40, and desorbed gas from the reactor R during the desorption process flows periodically into the CO2 recovery vacuum piping 50. The degassing process is extremely short compared to the desorption process, and the pressure increase in the vacuum piping 40 due to residual air from the reactor R during the degassing process is extremely small compared to the pressure increase in the vacuum piping 50 due to desorbed gas from the reactor R during the desorption process. For this reason, the pressure in the degassing vacuum piping 40 (for example, about 1 kPa) is lower than the pressure in the CO2 recovery vacuum piping 50 (for example, about 5 kPa).

[0035] As shown in Figures 2 and 3, the gas phase of the first water tank 81 is connected to the vacuum piping 50 for CO2 recovery via the branch pipe 80, so the pressure of the gas phase in the first water tank 81 becomes equal to the pressure of the vacuum piping 50. As shown in Figure 2, when the on-off valve 86 is opened and the on-off valve 85, the pressure-recovering valve 87, and the drain valve 88 are closed, the gas phase of the second water tank 82 is connected to the vacuum piping 40 for degassing via the branch pipe 44, so the pressure of the gas phase in the second water tank 82 becomes equal to the pressure of the vacuum piping 40.

[0036] At this time, when the on-off valve 85 of the communication passage 83 that connects the liquid phase of the first water tank 81 and the gas phase of the second water tank 82 is opened, the condensed water stored in the first water tank 81 is efficiently transferred to the second water tank 82 without backflow, due to gravity and the pressure difference between the gas phase of the first water tank 81 and the gas phase of the second water tank 82.

[0037] When the on-off valves 85 and 86 are closed and the pressure-recovering valve 87 and drain valve 88 are opened, air flows in through the pressure-recovering valve 87, restoring the gas phase of the second water tank 82, and the condensed water stored in the second water tank 82 is drained by gravity through the drain valve 88.

[0038] By opening the on-off valve 85 provided in the communication passage 83, provided that the water level in the first water tank 81 exceeds the lower limit, the liquid phase of the first water tank 81 is secured, and the gas phase of the first water tank 81 is reliably isolated from the second tank and sealed. In this case, it is possible to reliably prevent the vacuum piping 50 for CO2 recovery from communicating with the second water tank 82 via the first water tank 81 and the communication passage 83, and therefore it is not affected by the repressurization of the second water tank 82.

[0039] According to embodiments of the present invention, the following effects can be achieved. (1) The DAC device 100 includes a reactor R provided with an adsorbent that adsorbs or absorbs CO2 and water, a vacuum pump 5 connected to the reactor R via vacuum piping 50 and sucking out desorbed gas from the adsorbent, a gas-liquid separator 8 provided in the vacuum piping 50 and separating water from the desorbed gas, and a first water tank 81 for storing the water separated by the gas-liquid separator 8 (Figures 1 to 3). In this way, by providing the gas-liquid separator 8 in the vacuum piping 50 and separating and removing water from the desorbed gas, the pressure of the desorbed gas in the vacuum piping 50 can be reduced, and the pumping efficiency of the vacuum pump 5 and the CO2 recovery efficiency can be improved, especially in the first half of the desorption process when the amount of water desorbed is large. As a result, the CO2 recovery efficiency of the entire device can be improved.

[0040] (2) The DAC device 100 further comprises a vacuum pump 4 connected to the reactor R via a vacuum pipe 40 for sucking up residual air that has not been adsorbed by the adsorbent, a second water tank 82 connected to the vacuum pipe 40, a connecting passage 83 that connects the first water tank 81 and the second water tank 82, and a check valve 84 provided in the connecting passage 83 that prevents the flow of fluid from the second water tank 82 to the first water tank 81 (Figure 2). As a result, the water stored in the first water tank 81 can be efficiently transferred to the second water tank 82 by the pressure difference between the gas phase of the first water tank 81 connected to the vacuum pipe 50 for CO2 recovery and the gas phase of the second water tank 82 connected to the vacuum pipe 40 for degassing.

[0041] (3) The communication path 83 is further provided with an on-off valve 85 (Fig. 2). The on-off valve 85 is opened on the condition that the water level of the first water tank 81 exceeds the lower limit water level and the second water tank 82 communicates with the vacuum pipe 40 for degassing. This secures the liquid phase in the first water tank 81, so that the vacuum pipe 50 for CO₂ recovery can be reliably prevented from being affected by the pressure restoration of the second water tank 82 via the first water tank 81 and the communication path 83. Furthermore, due to the pressure difference between the gas phase of the first water tank 81 communicating with the vacuum pipe 50 for CO₂ recovery and the gas phase of the second water tank 82 communicating with the vacuum pipe 40 for degassing, the water stored in the first water tank 81 can be efficiently transferred to the second water tank 82 without backflow.

[0042] (4) The second water tank 82 is provided lower than the first water tank 81 in the direction of gravity (Fig. 2). This allows the condensed water stored in the first water tank 81 to be transferred to the second water tank 82 via the communication path 83 by gravity.

[0043] (5) The vacuum pipe 50 communicates with the gas phase of the first water tank 81, and the communication path 83 communicates the liquid phase of the first water tank 81 with the gas phase of the second water tank 82 (Fig. 2). As a result, the gas phase of the first water tank 81 communicating with the vacuum pipe 50 for CO₂ recovery is sealed by the liquid phase in the first water tank 81, so that the vacuum pipe 50 for CO₂ recovery can be reliably prevented from being affected by the pressure restoration of the second water tank 82.

[0044] (6) The gas-liquid separator 8 is a heat exchanger that condenses water contained in desorption gas using a refrigerant (Fig. 3). Therefore, water can be separated from desorption gas with a simple configuration. Furthermore, the condensed water can be used for cooling other devices and the like.

[0045] (7) At least one of the heat exchanger, the gas-liquid separator 8 and the first water tank 81, is insulated (Figure 3). As a result, when condensed water vaporizes (re-evaporates) in the gas-liquid separator 8 and the first water tank 81, the heat of vaporization lowers the temperature of the gas-liquid separator 8 and the first water tank 81, causing the water vapor to condense immediately, and suppressing the re-evaporation of condensed water overall. In addition, the gas-liquid separator 8 and the first water tank 81 are maintained at extremely low temperatures, and extremely low temperature condensed water is stored.

[0046] In the above embodiment, an example was described in which water level sensors 11 and 13 are provided in water tanks 81 and 82 to detect water levels L1 and L2, as shown in Figures 2 and 4. However, the water level in the water tanks is not limited to what is detected by the water level sensors. For example, the water levels L1 and L2 in water tanks 81 and 82 may be estimated based on environmental conditions such as humidity and temperature, or the operating conditions of the DAC device. In this case, the configuration of water tanks 81 and 82 can be simplified, and it is possible to easily maintain a vacuum state or an adiabatic state.

[0047] The above description is merely an example, and the present invention is not limited by the embodiments and modifications described above, as long as the features of the present invention are not impaired. It is also possible to arbitrarily combine one or more of the above embodiments and modifications, and to combine modifications with each other.

[0048] 1,2 Atmospheric control valve, 3 Fan, 4,5 Vacuum pump, 6 Storage tank, 7 Heat exchanger, 8 Gas-liquid separator, 9 Cooler, 10 Controller, 11,13 Water level sensor, 12,14 Pressure sensor, 30 Atmospheric piping, 40,50 Vacuum piping, 41,51 Individual piping, 42,52 Combined piping, 43,53 Vacuum control valve, 44 Branch piping, 80 Branch piping, 81 First water tank, 82 Second water tank, 83 Connecting passage, 84 Check valve, 85,86 On / off valve, 87 Pressure restoration valve, 88 Drain valve, 100 DAC device, R Reactor

Claims

1. A DAC device for recovering CO2 from the atmosphere, comprising: an adsorption chamber provided with an adsorbent for adsorbing or absorbing CO2 and water; a recovery vacuum pump connected to the adsorption chamber via a recovery vacuum pipe for sucking out desorbed gas from the adsorbent; a gas-liquid separator provided in the recovery vacuum pipe for separating water from the desorbed gas; and a water tank for storing the water separated by the gas-liquid separator.

2. The DAC device according to claim 1, wherein the water tank is a first water tank, and further comprises: a vacuum pump for degassing connected to the adsorption chamber via a vacuum pipe for degassing and sucking up residual air that has not been adsorbed by the adsorbent; a second water tank connected to the vacuum pipe for degassing; a connecting passage connecting the first water tank and the second water tank; and a check valve provided in the connecting passage for preventing the flow of fluid from the second water tank to the first water tank.

3. The DAC device according to claim 2, characterized in that an on / off valve is further provided in the communication passage.

4. The DAC device according to claim 3, wherein the on-off valve is opened on the condition that the water level in the first water tank exceeds a predetermined water level and the second water tank is in communication with the degassing vacuum piping.

5. The DAC device according to claim 2, characterized in that the second water tank is provided below the first water tank in the direction of gravity.

6. A DAC apparatus according to claim 2, characterized in that the recovery vacuum piping communicates with the gas phase of the first water tank, and the communication passage communicates the liquid phase of the first water tank with the gas phase of the second water tank.

7. A DAC apparatus according to any one of claims 1 to 6, characterized in that the gas-liquid separator is a heat exchanger that condenses the water contained in the desorbed gas with a refrigerant.

8. A DAC apparatus according to claim 7, characterized in that at least one of the gas-liquid separator and the water tank is insulated.

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