Carbon dioxide removal system

Abstract

The adsorption and desorption of carbon dioxide can be controlled depending on the situation. [Solution] The system comprises a gas acquisition unit for acquiring gas to be treated from a target space, a distribution path for circulating the acquired gas to be treated, a processing unit in which two or more adsorption towers are connected in series to the distribution path along the flow of the gas to be treated, and a control device for switching the path of the gas to be treated. The distribution path includes a first main path for supplying the gas to be treated to the processing unit, a first recovery path for discharging the gas that has passed through the first main path back into the target space, a desorption path connected to a depressurized adsorption tower, a path between the upstream and downstream adsorption towers of the first processing unit, a first branch path connecting to the first recovery path, and a switching mechanism for switching the path through which the gas flows. The desorption path can be connected in parallel to multiple adsorption towers.

Description

Technical Field

[0001] The present disclosure relates to a carbon dioxide removal system for recovering carbon dioxide in the air.

Background Art

[0002] There is a technology for recovering carbon dioxide from a gas. Patent Document 1 describes a system for separating carbon dioxide contained in a raw material gas by adjusting the pressure while adjusting the temperature, using the PSA method in which the pressure of an adsorption tower is increased and decreased to switch between adsorption and desorption.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, a system for separating carbon dioxide performs not only normal pressure and normal temperature during adsorption, but also pressurization and cooling in some cases. Further, when performing cyclic operation of adsorption and desorption, power is consumed because the pressure is reduced and the temperature is raised during desorption for switching the operation. When used in an environment where the available power is limited, there may be restrictions on the operation.

[0005] The present disclosure solves the above-described problems and aims to provide a carbon dioxide removal system that can control the adsorption and desorption of carbon dioxide according to the situation.

Means for Solving the Problems

[0006] To solve the above-mentioned problems and achieve the objective, the carbon dioxide removal system according to this disclosure comprises: a gas acquisition unit for acquiring a gas to be treated from a target space; a distribution path for distributing the acquired gas to be treated; a processing unit in which two or more adsorption towers are connected in series to the distribution path along the flow of the gas to be treated; and a control device for switching the path of the gas to be treated. The distribution path comprises: a first main path for supplying the gas to be treated to the processing unit; a first recovery path for discharging the gas that has passed through the first main path to the target space; a desorption path connected to the adsorption towers which are depressurized; a path between the adsorption tower upstream and the adsorption tower downstream of the first processing unit; a first branch path connecting the first recovery path; and a switching mechanism for switching the path through which the gas flows. The desorption path can be connected in parallel to a plurality of adsorption towers.

[0007] To solve the above-mentioned problems and achieve the objective, the carbon dioxide removal system according to this disclosure comprises: a gas acquisition unit for acquiring a gas to be treated from a target space; a distribution path for circulating the acquired gas to be treated; a first processing unit in which two or more adsorption towers are connected in series to the distribution path along the flow of the gas to be treated; a second processing unit in which two or more adsorption towers are connected in series to the distribution path along the flow of the gas to be treated and is arranged in parallel with the first processing unit; and a control device for switching the path of the gas to be treated, wherein the distribution path comprises: a first main path for supplying the gas to be treated to the first processing unit; and a second processing unit arranged in parallel with the first main path for supplying the gas to be treated to the first processing unit. The control device comprises a second main path supplying to two processing units, a first recovery path discharging the gas that has passed through the first and second main paths into the target space, a desorption path connected to the depressurized adsorption tower, a path between the upstream and downstream adsorption towers of the first processing unit, a first branch path connecting to the first recovery path, and a switching mechanism for switching the path through which the gas flows. The control device controls the switching mechanism located in the flow path and can switch between a mode in which the gas to be treated flows through all the adsorption towers of the first processing unit, and a mode in which the gas to be treated flows through the first branch path, allowing the gas to be treated to flow through the upstream adsorption tower of the first processing unit, but not through the downstream adsorption tower. [Effects of the Invention]

[0008] According to this disclosure, carbon dioxide adsorption and desorption can be suitably performed depending on the situation. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a schematic diagram of the carbon dioxide removal system in this embodiment. [Figure 2] Figure 2 is an explanatory diagram showing an example of the operation of the carbon dioxide removal system according to this embodiment. [Figure 3] Figure 3 is an explanatory diagram showing an example of the operation of the carbon dioxide removal system according to this embodiment. [Figure 4]Figure 4 is an explanatory diagram showing an example of the operation of the carbon dioxide removal system according to this embodiment. [Figure 5] Figure 5 is an explanatory diagram showing an example of the operation of the carbon dioxide removal system according to this embodiment. [Figure 6] Figure 6 is an explanatory diagram showing an example of the operation of the carbon dioxide removal system according to this embodiment. [Figure 7] Figure 7 is an explanatory diagram showing an example of the operation of the carbon dioxide removal system according to this embodiment. [Figure 8] Figure 8 is an explanatory diagram showing an example of the operation of the carbon dioxide removal system according to this embodiment. [Figure 9] Figure 9 is an explanatory diagram showing an example of the operation of the carbon dioxide removal system according to this embodiment. [Figure 10] Figure 10 is an explanatory diagram showing an example of the operation of the carbon dioxide removal system according to this embodiment. [Figure 11] Figure 11 is a schematic diagram of a carbon dioxide removal system in another embodiment. [Figure 12] Figure 12 is an explanatory diagram showing an example of the operation of the carbon dioxide removal system shown in Figure 11. [Modes for carrying out the invention]

[0010] Preferred embodiments of the present invention will be described in detail below with reference to the attached drawings. However, the present invention is not limited to these embodiments, and if there are multiple embodiments, they may be constructed by combining these embodiments.

[0011] FIG. 1 is a schematic diagram of a carbon dioxide removal system according to the present embodiment. The carbon dioxide removal system 10 of the present embodiment acquires a target gas in a target space 8 and removes carbon dioxide contained in the target gas. The carbon dioxide removal system 10 is a system that removes a part of carbon dioxide from the target gas and reduces the carbon dioxide concentration in the target gas. It is also possible to remove all of the carbon dioxide in the target gas. The carbon dioxide removal system 10 of the present embodiment discharges the carbon dioxide removed from the target gas to the outdoor space 6.

[0012] The target space 8 is not particularly limited, but for example, it is a space where people are active. The carbon dioxide removal system 10 can be more preferably used when the target space 8 is a sealed space that cannot take in outside air. For example, when the outdoor space 6 outside the target space 8 is a space where the atmosphere is polluted, underwater, a space with little air, or outer space, it can be preferably used.

[0013] The carbon dioxide removal system 10 includes an intake section (target gas acquisition section) 12, a flow path 14, a first processing unit 20, a second processing unit 22, a first recovery path 24, a desorption path 26, a second recovery path 27, blowers 30 and 32, a vacuum pump 34, a control device 36, and a power source 38.

[0014] The intake section 12 is connected to the target space 8 and takes in the target gas (air) in the target space 8 into the carbon dioxide removal system 10.

[0015] The flow path 14 connects the intake section 12 to the first processing unit 20 and the second processing unit 22, and supplies the target gas intake by the intake section 12 to the first processing unit 20 and the second processing unit 22. The flow path 14 connects the first processing unit 20 and the second processing unit 22 to the first recovery path 24, the desorption path 26, and the second recovery path 27.

[0016] The flow path 14 includes an intake path 40, a first main path 42, a second main path 44, branch paths 100, 102, 104, 106, 108, 110, and connection paths 112, 114, 116, 118, 120. Also, an on-off valve is provided in each path of the flow path 14. The intake path 40 is a pipe connecting the intake section 12 to the first main path 42 and the second main path 44. The first main path 42 and the second main path 44 are pipes arranged in parallel. The first main path 42 connects a plurality of adsorption towers of the first processing unit 20 in series. The first main path 42 has its upstream end connected to the intake path 40 and its downstream end connected to the first recovery path 24. The second main path 44 connects a plurality of adsorption towers of the second processing unit 22 in series. The second main path 44 has its upstream end connected to the intake path 40 and its downstream end connected to the first recovery path 24. The other parts of the flow path 14 will be described after the description of each part connected to the flow path 14.

[0017] The first processing unit 20 has three adsorption towers: an upstream adsorption tower 50a, a middle adsorption tower 52a, and a downstream adsorption tower 54a. In the first processing unit 20, the upstream adsorption tower 50a, the middle adsorption tower 52a, and the downstream adsorption tower 54a are connected in series to the first main path 42. That is, they are arranged in the order of the upstream adsorption tower 50a, the middle adsorption tower 52a, and the downstream adsorption tower 54a along the flow direction, starting from the upstream side of the flow direction of the gas to be processed in the first main path 42, which is the connection side with the intake path 40.

[0018] The second processing unit 22 has three adsorption towers: an upstream adsorption tower 50b, a middle adsorption tower 52b, and a downstream adsorption tower 54b. In the second processing unit 22, the upstream adsorption tower 50b, the middle adsorption tower 52b, and the downstream adsorption tower 54b are connected in series to the second main path 44. That is, they are arranged in the order of the upstream adsorption tower 50b, the middle adsorption tower 52b, and the downstream adsorption tower 54b along the flow direction, starting from the upstream side of the flow direction of the gas to be processed in the second main path 44, which is the connection side with the intake path 40.

[0019] The upstream adsorption towers 50a and 50b, the midstream adsorption towers 52a and 52b, and the downstream adsorption towers 54a and 54b (simply referred to as adsorption towers when no distinction is made between them) are filled with an adsorbent that adsorbs carbon dioxide. The adsorption towers in this embodiment are filled with a solid adsorbent. Various substances that adsorb carbon dioxide can be used as the adsorbent. Preferably, the adsorbent is a material in which adsorption and desorption occur reversibly in response to changes in the partial pressure of CO2. Furthermore, preferably, the adsorbent has the property of becoming more readily desorbable of carbon dioxide as the temperature increases. Examples of adsorbents include amine-impregnated adsorbents and organometallic frameworks (MOFs). Preferably, an amine-impregnated adsorbent is used as the adsorbent.

[0020] The upstream adsorption towers 50a and 50b, the midstream adsorption towers 52a and 52b, and the downstream adsorption towers 54a and 54b in this embodiment have the same diameter and length, and are filled with the same adsorbent. In other words, the upstream adsorption towers 50a and 50b, the midstream adsorption towers 52a and 52b, and the downstream adsorption towers 54a and 54b are adsorption towers with equivalent carbon dioxide adsorption performance.

[0021] The first recovery path 24 is a piping to which the gas to be treated, having passed through the first processing unit 20 and the second processing unit 22, is supplied. One end of the first recovery path 24 is connected to the downstream end of the first main path 42 and the downstream end of the second main path 44, and the other end is connected to the target space 8. The first recovery path 24 sends the gas to be treated, from which carbon dioxide has been removed or reduced by the first processing unit 20 and the second processing unit 22, to the target space 8.

[0022] The desorption / desorption path 26 has one end connected to the flow path 14 and the other end connected to the outdoor space 6. The desorption / desorption path 26 is a pipe that guides the carbon dioxide generated during the process of releasing the carbon dioxide adsorbed by the adsorption tower to the outdoor space 6. The on / off valve 28a is located in the desorption / desorption path 26 and switches between a state in which the outdoor space 6 and the adsorption tower are connected and a state in which they are separated. In this embodiment, the desorption / desorption path 26 is structured to connect to the outdoor space 6, but it may also be structured to connect to a storage tank for storing carbon dioxide.

[0023] The second recovery path 27 has one end connected upstream (towards the adsorption tower) of the on-off valve 28a of the desorption path 26, and the other end connected to the target space 8. The second recovery path 27 is the path through which gas flows when the gas discharged from the adsorption tower that is to be returned to the target space 8 is supplied to the desorption path 26. The on-off valve 28b is located in the second recovery path 27 and switches between a state in which the target space 8 and the adsorption tower are connected and a state in which they are separated.

[0024] Blower 30 is located in the intake path 40. Blower 30 forms a gas flow from the intake section 12 toward the first recovery path 24. Blower 32 is located in the first recovery path 24. Blower 32 forms a gas flow from the first main path 42 and the second main path 44 toward the first recovery path 24. By forming a gas flow with blowers 30 and 32, a gas flow is formed that passes from the intake section 12 through at least one adsorption tower of the first processing unit 20 and the second processing unit 22, and flows from the first recovery path 24 toward the target space 8. In this embodiment, blower 30 is provided on the upstream side of the gas flow path and blower 32 is provided on the downstream side, but only one of them may be provided.

[0025] The vacuum pump 34 is positioned upstream (on the adsorption tower side) of the connection point between the desorption path 26 and the second recovery path 27. The vacuum pump 34 pushes (suctions) the gas from the connected desorption path 26 downstream, reducing the pressure in the space upstream of the connection point of the desorption path 26. In the carbon dioxide removal system 10 of this embodiment, a vacuum pump 34 is provided, but if the outdoor space 6 is a space with a sufficiently lower pressure than the target space 8, for example, a vacuum space, the vacuum pump 34 may not be provided. In this case, the upstream space can also be reduced in pressure by opening and closing the on-off valve 28a.

[0026] Next, we will describe each pipe and valve in the distribution path 14. In the first main path 42, the pipe connecting the upstream adsorption tower 50a and the midstream adsorption tower 52a is the intermediate path 56a, the pipe connecting the midstream adsorption tower 52a and the downstream adsorption tower 54a is the intermediate path 58a, and the pipe connecting the downstream adsorption tower 54a and the first recovery path 24 is the intermediate path 60a. The valve 70a is located between the intake path 40 and the upstream adsorption tower 50a in the first main path 42. The valve 72a is located in the intermediate path 56a. The valve 74a is located on the midstream adsorption tower 52a side of the valve 72a in the intermediate path 56a. The valve 76a is located in the intermediate path 58a. The valve 78a is located on the downstream adsorption tower 54a side of the valve 76a in the intermediate path 58a. The valve 80a is located in the intermediate path 60a. In other words, in the upstream adsorption tower 50a, an on-off valve 70a is located on the upstream side and an on-off valve 72a is located on the downstream side in the first main path 42. In the midstream adsorption tower 52a, an on-off valve 74a is located on the upstream side and an on-off valve 76a is located on the downstream side in the first main path 42. In the downstream adsorption tower 54a, an on-off valve 78a is located on the upstream side and an on-off valve 80a is located on the downstream side in the first main path 42.

[0027] In the second main path 44, the piping connecting the upstream adsorption tower 50b and the midstream adsorption tower 52b becomes the intermediate path 56b, the piping connecting the midstream adsorption tower 52b and the downstream adsorption tower 54b becomes the intermediate path 58b, and the piping connecting the downstream adsorption tower 54b and the first recovery path 24 becomes the intermediate path 60b. The on-off valve 70b is located between the intake path 40 and the upstream adsorption tower 50b of the second main path 44. The on-off valve 72b is located in the intermediate path 56b. The on-off valve 74b is located on the midstream adsorption tower 52b side of the on-off valve 72b in the intermediate path 56b. The on-off valve 76b is located in the intermediate path 58b. The on-off valve 78b is located on the downstream adsorption tower 54b side of the on-off valve 76b in the intermediate path 58b. The on-off valve 80b is located in the intermediate path 60b. In other words, in the upstream adsorption tower 50b, an on-off valve 70b is located on the upstream side and an on-off valve 72b is located on the downstream side in the second main path 44. In the midstream adsorption tower 52b, an on-off valve 74b is located on the upstream side and an on-off valve 76b is located on the downstream side in the second main path 44. In the downstream adsorption tower 54b, an on-off valve 78b is located on the upstream side and an on-off valve 80b is located on the downstream side in the second main path 44.

[0028] Branch piping 100 connects the on-off valve 70a of the first main route 42 to the upstream adsorption tower 50a, and the on-off valve 70b of the second main route 44 to the upstream adsorption tower 50b. Branch piping 102 connects the on-off valves 72a and 74a of the intermediate route 56a, and the on-off valves 72b and 74b of the intermediate route 56b. Branch piping 104 connects the on-off valves 72a and 74a of the intermediate route 56a, and the on-off valves 72b and 74b of the intermediate route 56b. Branch piping 106 connects the on-off valves 76a and 78a of the intermediate route 58a, and the on-off valves 76b and 78b of the intermediate route 58b. The branch pipe 108 connects the on-off valves 76a and 78a in the intermediate route 58a, and the on-off valves 76b and 78b in the intermediate route 58b. The branch pipe 110 connects the downstream adsorption tower 54a and on-off valve 80a in the intermediate route 60a, and the downstream adsorption tower 54b and on-off valve 80b in the intermediate route 60b.

[0029] Connection route 112 connects branch pipe 100 and branch pipe 102. Connection route 114 connects branch pipe 102 and branch pipe 106. Connection route 114 also connects to detachment route 26. Connection route 116 connects branch pipe 104 and discharge pipe 24. Note that in Figure 1, it is connected downstream of the on-off valve 80a of intermediate route 60a, but it is sufficient if it is connected to discharge pipe 24 without going through a valve. Connection route 118 connects branch pipe 106 and branch pipe 110. Connection route 120 connects branch pipe 108 and discharge pipe 24.

[0030] On / off valve 101a is located on the first processing unit 20 side of the connecting pipe 100, beyond the connecting path 112. On / off valve 101b is located on the second processing unit 22 side of the connecting pipe 100, beyond the connecting path 112. On / off valve 103a is located on the first processing unit 20 side of the connecting pipe 102, beyond the connecting paths 112 and 114. On / off valve 103b is located on the second processing unit 22 side of the connecting pipe 102, beyond the connecting paths 112 and 114. On / off valve 105a is located on the first processing unit 20 side of the connecting pipe 104, beyond the connecting path 116. On / off valve 105b is located on the second processing unit 22 side of the connecting pipe 104, beyond the connecting path 116. On / off valve 107a is located on the first processing unit 20 side of the connecting pipe 106, beyond the connecting paths 114 and 118. The on-off valve 107b is located on the second processing unit 22 side of the connecting pipe 106, beyond the connecting paths 114 and 118. The on-off valve 109a is located on the first processing unit 20 side of the connecting pipe 108, beyond the connecting path 120. The on-off valve 109b is located on the second processing unit 22 side of the connecting pipe 108, beyond the connecting path 120. The on-off valve 111a is located on the first processing unit 20 side of the connecting pipe 110, beyond the connecting path 118. The on-off valve 111b is located on the second processing unit 22 side of the connecting pipe 110, beyond the connecting path 118.

[0031] Here, the connection relationships and the arrangement of the on-off valves in the flow path 14 of this embodiment are just examples. The flow path 14 can be any path and valve arrangement that allows switching between an adsorption tower for adsorption processing and an adsorption tower for discharge processing, as described later. For example, a three-way valve may be used as the valve. Alternatively, a control valve with adjustable opening degree may be used as the switching mechanism.

[0032] The control device 36 is a control device that controls the carbon dioxide removal system 10. In this embodiment, the control device 36 is a computer and includes a processor that includes an arithmetic circuit such as a CPU (Central Processing Unit), and a storage unit that stores various information such as the calculations performed by the processor and programs. The control device 36 controls the carbon dioxide removal system 10 by reading a program from the storage unit.

[0033] The control device 36 controls the opening and closing of the on-off valves provided in the flow path 14, the driving of the blowers 30 and 32, and the driving of the vacuum pump 34 to control the adsorption process in the first processing unit 20 and the second processing unit 22, which adsorbs carbon dioxide from the gas to be processed as it passes through, thereby reducing and removing carbon dioxide from the gas to be processed, and the desorption process in which the adsorption towers of the first processing unit 20 and the second processing unit 22 are depressurized, or depressurized along with heating, to desorb the carbon dioxide adsorbed in the first processing unit 20 and the second processing unit 22 from the adsorption towers. The control device 36 switches between the adsorption tower that performs the adsorption process and the adsorption tower that performs the desorption process based on pre-entered settings or detected conditions.

[0034] The power source 38 supplies power to each part of the carbon dioxide removal system 10. The power source 38 includes a battery 38a and a solar power generator 38b. The battery 38a stores the power generated by the solar power generator 38b. The battery 38a supplies the stored power to each part. The solar power generator 38b generates power using energy supplied from the sun. The solar power generator 38b supplies the generated power to each part and the battery 38a.

[0035] Next, the operation of the carbon dioxide removal system of this embodiment, namely the adsorption and desorption processes, will be explained using Figures 2 to 10. Figures 2 to 10 are explanatory diagrams showing examples of the operation of the carbon dioxide removal system according to this embodiment.

[0036] In this embodiment, the carbon dioxide removal system 10 comprises a first processing unit 20 and a second processing unit 22, each having multiple adsorption towers, and these multiple adsorption towers are connected in series. The carbon dioxide removal system 10 can switch the number of adsorption towers through which the gas to be treated passes by switching the flow path of the gas to be treated. The carbon dioxide removal system 10 can also switch the number of adsorption towers that perform the desorption process.

[0037] The carbon dioxide removal system 10 shown in Figure 2 performs adsorption processing in the upstream adsorption tower 50a of the first processing unit 20 and desorption processing in the upstream adsorption tower 50b of the second processing unit 22. The control device 36 opens valves 70a, 72a, and 105a for the adsorption processing and closes valves 70b, 101a, 103a, 74a, 105b, 109a, 109b, 80a, and 80b. As a result, the gas to be treated flows through a path 202 that passes only through the upstream adsorption tower 50a of the first processing unit 20 and not through the other adsorption towers. The control device 36 opens valves 72b, 101b, 103b, and 28a for the attachment / detachment process, and closes valves 70b, 101a, 103a, 105b, 74b, 107a, 107b, 111a, 111b, and 28b. This creates a path 204 in which only the upstream adsorption tower 50b of the second processing unit 20 is depressurized by the vacuum pump 34.

[0038] The carbon dioxide removal system 10 divides the adsorption tower of the processing unit into multiple sections, thereby shortening the length of each individual adsorption tower, reducing pressure loss in each tower, increasing the vacuum level, and maintaining a high desorption force. The carbon dioxide removal system 10 has a structure that allows both the upstream and downstream paths of the adsorption towers performing desorption processing to be connected to the path of the vacuum pump 34, enabling parallel adsorption processing on multiple adsorption towers.

[0039] The carbon dioxide removal system 10 shown in Figure 3 performs adsorption processing in the upstream adsorption tower 50b of the second processing unit 22 and desorption processing in the upstream adsorption tower 50a of the first processing unit 20. The control device 36 opens valves 70b, 72b, and 105b for the adsorption processing and closes valves 70a, 101b, 103b, 74b, 105a, 109a, 109b, 80b, and 80a. As a result, the gas to be treated flows through a path 212 that passes only through the upstream adsorption tower 50b of the second processing unit 22 and not through the other adsorption towers. The control device 36 opens valves 72a, 101a, 103a, and 28a for the attachment / detachment process, and closes valves 70a, 101b, 103b, 105a, 74a, 107a, 107b, 111a, 111b, and 28b. This creates a path 214 in which only the upstream adsorption tower 50a of the first processing unit 22 is depressurized by the vacuum pump 34.

[0040] The carbon dioxide removal system 10 can switch between a mode in which adsorption is performed in the first processing unit 20 and desorption is performed in the second processing unit 22, and a mode in which desorption is performed in the first processing unit 20 and adsorption is performed in the second processing unit 22, by switching between the processing modes shown in Figure 2 and Figure 3 at predetermined intervals. Furthermore, by performing both adsorption and desorption in one adsorption tower of each processing unit, power consumption can be reduced compared to when all adsorption towers of each processing unit are used for both adsorption and desorption. In addition, the desorption time can be shortened.

[0041] The carbon dioxide removal system 10 shown in Figure 4 performs adsorption processing in the upstream adsorption tower 50a, the midstream adsorption tower 52a, and the downstream adsorption tower 54a of the first processing unit 20. The carbon dioxide removal system 10 shown in Figure 4 does not perform desorption processing simultaneously. The control device 36 opens valves 70a, 72a, 74a, 76a, 78a, and 80a for adsorption processing, and closes valves 70b, 101a, 101b, 103a, 103b, 105a, 105b, 107a, 109a, 109b, 111a, and 80b. As a result, the gas to be treated flows through a path 222 that passes through all of the upstream adsorption towers 50a, midstream adsorption towers 52a, and downstream adsorption towers 54a of the first processing unit 20.

[0042] The carbon dioxide removal system 10 shown in Figure 5 performs adsorption processing in the upstream adsorption tower 50b, the midstream adsorption tower 52b, and the downstream adsorption tower 54b of the second processing unit 22. The carbon dioxide removal system 10 shown in Figure 5 does not perform desorption processing simultaneously. The control device 36 opens valves 70b, 72b, 74b, 76b, 78b, and 80b for adsorption processing, and closes valves 70a, 101b, 103b, 105a, 105b, 107b, 109a, 109b, 111b, and 80a. As a result, the gas to be treated flows through a path 224 that passes through all of the upstream adsorption towers 50b, midstream adsorption towers 52b, and downstream adsorption towers 54b of the second processing unit 22.

[0043] The carbon dioxide removal system 10 shown in Figure 6 performs adsorption processing in the upstream adsorption tower 50b, midstream adsorption tower 52b, and downstream adsorption tower 54b of the second processing unit 22, and performs desorption processing in the upstream adsorption tower 50a of the first processing unit 20. The control device 36 opens valves 70b, 72b, 74b, 76b, 78b, and 80b for the adsorption processing, and closes valves 70a, 101b, 103b, 105a, 105b, 107b, 109a, 109b, 111b, and 80a. As a result, the gas to be treated flows through a path 224 that passes through all of the upstream adsorption towers 50b, midstream adsorption tower 52b, and downstream adsorption tower 54b of the second processing unit 22. Furthermore, the control device 36 opens valves 72a, 101a, 103a, and 28a for the attachment and detachment process, and closes valves 70a, 101b, 103b, 105a, 74a, 107a, 107b, 111a, 111b, and 28b. This creates a path 225 through which the upstream adsorption tower 50a of the first processing unit 20 is depressurized by the vacuum pump 34.

[0044] The carbon dioxide removal system 10 shown in Figure 7 performs adsorption processing in the upstream adsorption tower 50a of the first processing unit 20, and desorption processing in the upstream adsorption tower 50b, midstream adsorption tower 52b, and downstream adsorption tower 54b of the second processing unit 22. The control device 36 opens valves 70a, 72a, and 105a for adsorption processing, and closes valves 70b, 101a, 103a, 74a, 105b, 109a, 109b, 80a, and 80b. As a result, the gas to be treated flows through a path 226 that passes only through the upstream adsorption tower 50a of the first processing unit 20 and not through the other adsorption towers. The control device 36 opens valves 72b, 74b, 76b, 78b, 101b, 103b, 107b, 111b, and 28a for the attachment / detachment process, and closes valves 70b, 101a, 103a, 105b, 107a, 109b, 111a, 80b, and 28b. This creates a path 228 through which the upstream adsorption tower 50b, midstream adsorption tower 52b, and downstream adsorption tower 54b of the second processing unit 22 are depressurized by the vacuum pump 34.

[0045] The carbon dioxide removal system 10 performs the processing mode shown in Figure 4, then the processing mode shown in Figure 5, then the processing mode shown in Figure 6, and finally the processing mode shown in Figure 7. Alternatively, after performing the processing mode shown in Figure 7, it is preferable that the carbon dioxide removal system 10 performs adsorption processing in the upstream adsorption tower 50b of the second processing unit 22, and then performs desorption processing in the upstream adsorption tower 50a, midstream adsorption tower 52a, and downstream adsorption tower 54a of the first processing unit 20.

[0046] The carbon dioxide removal system 10 executes the above mode, performing adsorption processing using all the adsorption towers of each processing unit without performing desorption processing on the processing unit that is not performing adsorption processing, and then performing desorption processing. This allows for the removal of carbon dioxide from the target gas for a long period of time while suppressing power consumption in the mode in which all the adsorption towers of each processing unit are used for adsorption processing. The carbon dioxide removal system 10 can perform removal processing for a long period of time because the amount of target gas that can be held in the system increases by using all the adsorption towers of the processing unit. Furthermore, as shown in Figure 6, by performing adsorption processing on all the adsorption towers of one processing unit while performing desorption processing on one adsorption tower of the other processing unit, it is possible to prepare the adsorption tower to be used in the next mode while suppressing an increase in power consumption. For example, if the environment in which power use is restricted continues for a predetermined time even after adsorption processing has been performed on all the adsorption towers, desorption is performed only on the minimum number of adsorption towers necessary for the adsorption processing during that predetermined time. This reduces the power consumption required to prepare the adsorption tower to be used in the next mode. Furthermore, once an environment where electricity is available becomes accessible, the number of usable adsorption towers can be increased in a short time by simultaneously performing desorption processing on multiple adsorption towers, as shown in Figure 7.

[0047] The carbon dioxide removal system 10 shown in Figure 8 performs adsorption processing in the upstream adsorption tower 50a, midstream adsorption tower 52a, and downstream adsorption tower 54a of the first processing unit 20, and performs desorption processing in the upstream adsorption tower 50b, midstream adsorption tower 52b, and downstream adsorption tower 54b of the second processing unit 22. The control device 36 opens valves 70a, 72a, 74a, 76a, 78a, and 80a for the adsorption processing, and closes valves 70b, 101a, 103a, 105a, 105b, 107a, 109a, 109b, 111a, and 80b. As a result, the gas to be treated flows through a path 232 that passes through the upstream adsorption tower 50a, midstream adsorption tower 52a, and downstream adsorption tower 54a of the first processing unit 20. The control device 36 opens valves 72b, 74b, 76b, 78b, 101b, 103b, 107b, 111b, and 28a for the attachment / detachment process, and closes valves 70b, 101a, 103a, 105b, 107a, 109b, 111a, 80b, and 28b. This creates a path 234 through which the upstream adsorption tower 50b, midstream adsorption tower 52b, and downstream adsorption tower 54b of the second processing unit 20 are depressurized by the vacuum pump 34.

[0048] Preferably, after the carbon dioxide removal system 10 performs the processing mode shown in Figure 8, the adsorption processing is reversed, and the adsorption processing is performed in the upstream adsorption tower 50b, midstream adsorption tower 52b, and downstream adsorption tower 54b of the second processing unit 22, and the desorption processing is performed in the upstream adsorption tower 50a, midstream adsorption tower 52a, and downstream adsorption tower 54a of the first processing unit 20.

[0049] As shown in Figure 8, the carbon dioxide removal system 10 can remove more carbon dioxide from the target gas by performing adsorption processing in all adsorption towers of one processing unit and desorption processing in all adsorption towers of the other processing unit. The carbon dioxide removal system 10 is structured so that both the upstream and downstream paths of the adsorption towers performing desorption processing can be connected to the path of the vacuum pump 34, allowing for parallel desorption processing on multiple adsorption towers arranged in series in the main path. As a result, the carbon dioxide removal system 10 can perform adsorption processing on multiple adsorption towers in series and perform parallel desorption processing on multiple adsorption towers connected in series. When there are no restrictions on power consumption and the carbon dioxide concentration of the target gas is high, it is preferable for the carbon dioxide removal system 10 to perform processing in the mode shown in Figure 8.

[0050] In the carbon dioxide removal system 10 shown in Figure 9, desorption processing is performed in the midstream adsorption tower 52b and downstream adsorption tower 54b of the second processing unit 22, but no desorption processing is performed in the upstream adsorption tower 50b. In the mode shown in Figure 9, adsorption processing may or may not be performed simultaneously in the first processing unit 20. The control device 36 opens valves 74b, 76b, 78b, 103b, 107b, 111b, and 28a for desorption processing, and closes valves 72b, 101a, 101b, 103a, 105b, 107a, 109b, 111a, 80b, and 28b. This creates a path 242 through which the midstream adsorption tower 52b and downstream adsorption tower 54b of the second processing unit 20 are depressurized by the vacuum pump 34.

[0051] In the carbon dioxide removal system 10 shown in Figure 10, desorption is performed in the upstream adsorption tower 52a of the second processing unit 22, while no desorption is performed in the midstream adsorption tower 52b and the downstream adsorption tower 54b. In the mode shown in Figure 10, adsorption may or may not be performed simultaneously in the first processing unit 20. The control device 36 opens valves 72b, 101b, 103b, and 28b for desorption, and closes valves 70b, 74b, 101a, 103a, 105b, 107a, 107b, 111a, 111b, and 28a. As a result, the upstream adsorption tower 50b of the second processing unit 20 is depressurized by the vacuum pump 34, and a path 244 is formed through which the treated gas is supplied from the second recovery path 27 to the target space 8.

[0052] The carbon dioxide removal system 10 can also perform the desorption process shown in Figures 9 and 10 in the first processing unit 20. When the carbon dioxide removal system 10 uses a material that adsorbs moisture as an adsorbent, the adsorbed moisture is desorbed and discharged along with the carbon dioxide during desorption, which lowers the humidity of the target space. In addition, with amine-impregnated adsorbents, moisture is preferentially adsorbed in the upstream adsorption tower, resulting in less carbon dioxide adsorption, while carbon dioxide adsorption tends to be dominant in the downstream adsorption tower. In this case, the carbon dioxide removal system 10 can suppress the decrease in humidity of the target space 8 by returning the moisture adsorbed in the upstream adsorption tower to the target space 8. Furthermore, carbon dioxide can be removed from the target space by desorbing the carbon dioxide adsorbed in the downstream adsorption towers, namely the midstream adsorption tower and the downstream adsorption tower, through the desorption path 26.

[0053] As described above, the carbon dioxide removal system 10 allows for processing according to the situation by providing multiple adsorption towers in series and enabling switching of the path. By performing adsorption and desorption processing with a single adsorption tower, adsorption and desorption processing with small pressure loss is possible, processing can be performed with low power consumption required for adsorption and desorption, and power consumption can be leveled out. Furthermore, by performing desorption processing in parallel, desorption processing with small pressure loss is possible, and the number of usable adsorption towers can be increased in a short time. In addition, adsorption processing with multiple adsorption towers connected in series can be used continuously for a longer period compared to the case of a single adsorption tower.

[0054] In this embodiment, the carbon dioxide removal system 10 allows for connections between the vacuum pumps on both the upstream and downstream sides of individual adsorption towers, rather than reducing the pressure across a single, long adsorption tower. This reduces the pressure loss of the adsorbent within the adsorption tower, lowers the target pressure when the pressure inside the adsorption tower is reduced, and allows for efficient desorption of carbon dioxide.

[0055] The carbon dioxide removal system 10 may be equipped with a heater in the adsorption tower, and the adsorption tower that performs the desorption process may be heated by the heater. Heating allows the desorption process of carbon dioxide to be completed in a short time. Also, since heating generates electricity consumption, it is preferable not to heat the carbon dioxide removal system 10 under conditions where electricity consumption needs to be reduced.

[0056] In this embodiment, three adsorption towers are arranged in one processing unit, but any number of adsorption towers is not limited as long as two or more are connected in series. In other words, four adsorption towers may be arranged in series. By connecting two or more adsorption towers in series and making it possible to switch the number of adsorption towers through which the gas to be treated flows, carbon dioxide removal treatment can be performed according to the situation. Also, in this embodiment, two units, the first processing unit 20 and the second processing unit 22, are arranged in parallel, but three or more units may be arranged.

[0057] The carbon dioxide removal system 10 can suitably remove carbon dioxide by switching between modes such as those shown in Figures 2 to 10, based on a schedule pre-set by the operator. Furthermore, if necessary, it can perform processing while reducing power consumption, and if there are no power limitations, it can perform the desorption process in a short time. The carbon dioxide removal system 10 may determine the mode to execute based on information such as the carbon dioxide concentration in the target space 8, the number of people in the target space 8, their activity schedules, the power generation forecast of the power source, and the remaining power.

[0058] Figure 11 is a schematic diagram of a carbon dioxide removal system in another embodiment. The carbon dioxide removal system 10a shown in Figure 11 is the same as the carbon dioxide removal system 10 shown in Figure 1, except for the structure of the flow path 14a. The following describes the points specific to the carbon dioxide removal system 10a. The flow path 14a has switching paths 302a and 302b.

[0059] The switching route 302a has a branch section that connects to the upstream piping of the upstream adsorption tower 50a, the midstream adsorption tower 52a, and the downstream adsorption tower 54a of the first main route 42. The on-off valve 311a is located between the connection section of the first main route 42 with the switching route 302a and the upstream adsorption tower 50a. The on-off valve 312a is located at a branch section that connects the on-off valve 70a of the first main route 42 to the upstream adsorption tower 50a. The on-off valve 314a is located at a branch section that connects the on-off valve 72a and the on-off valve 74a of the intermediate route 56a. The on-off valve 316a is located at a branch section that connects the on-off valve 76a and the on-off valve 78a of the intermediate route 58a.

[0060] The switching route 302b has a branch section that connects to the upstream piping of the upstream adsorption tower 50b, the midstream adsorption tower 52b, and the downstream adsorption tower 54b of the second main route 44. The on-off valve 311b is located between the connection section of the second main route 44 with the switching route 302b and the upstream adsorption tower 50b. The on-off valve 312b is located at a branch section that connects the on-off valve 70b of the second main route 44 to the upstream adsorption tower 50b. The on-off valve 314b is located at a branch section that connects the on-off valve 72b and the on-off valve 74b of the intermediate route 56b. The on-off valve 316b is located at a branch section that connects the on-off valve 76b and the on-off valve 78b of the intermediate route 58b.

[0061] By providing a carbon dioxide removal system 10a and switching paths 302 and 304, the adsorption tower used in each processing unit can be switched.

[0062] Figure 12 is an explanatory diagram showing an example of the operation of the carbon dioxide removal system shown in Figure 11. In the carbon dioxide removal system 10a shown in Figure 12, adsorption treatment is performed in the midstream adsorption tower 52a of the first treatment unit 20, but no adsorption treatment is performed in the upstream adsorption tower 50a and the downstream adsorption tower 54a. The control device 36 opens valves 70a, 312a, 314a, 74a, 76a, and 109a for the adsorption treatment, and closes valves 70b, 311a, 72a, 316a, 103a, 105a, 105b, 107a, 78a, 109b, 80a, and 80b. As a result, the gas to be treated flows through a path 332 that passes through the midstream adsorption tower 52a of the first treatment unit 20, but not through the upstream adsorption tower 50a or the downstream adsorption tower 54a. The carbon dioxide removal system 10a can also be configured to have the gas pass through the downstream adsorption tower 54a of the first treatment unit 20, but not through the upstream adsorption tower 50a or the midstream adsorption tower 52b, by opening the on-off valves 312a and 316a, closing the on-off source 314a, and switching the other on-off valves as appropriate. The adsorption treatment of the second treatment unit 22 is similar. It is also possible to switch the path so that the gas passes through two of the three adsorption towers.

[0063] The carbon dioxide removal system 10a, equipped with switching paths 302 and 304, allows for adsorption treatment using only the midstream adsorption tower or only the downstream adsorption tower. This increases the number of available modes, i.e., the number of combinations of adsorption towers that can be used. Therefore, treatment can be performed in a more suitable mode depending on the situation. Furthermore, even when operating with only one tower, by using the upstream, midstream, and downstream towers evenly, it is possible to equalize the degree of adsorption degradation and stabilize performance.

[0064] (Effects of this disclosure) This disclosure has the following characteristics. However, this disclosure is not limited to the following. (1) A gas acquisition unit that acquires the gas to be processed from the target space, The distribution route for the acquired gas to be processed, A processing unit comprising two or more adsorption towers connected in series in the flow path along the flow of the gas to be processed, The system includes a control device for switching the path of the gas to be processed, The aforementioned distribution route includes a first main route that supplies the gas to be processed to the processing unit, A first recovery path discharges the gas that has passed through the first main path into the target space, A desorption path connected to the adsorption tower which is subjected to reduced pressure, A path between the upstream adsorption tower and the downstream adsorption tower of the first processing unit, and a first branch path connecting the first recovery path, It has a switching mechanism for switching the gas flow path, The aforementioned desorption path is a carbon dioxide removal system that can be connected in parallel with multiple adsorption towers.

[0065] (2) The carbon dioxide removal system according to (1), wherein the desorption path is connectable to both the upstream and downstream of the adsorption tower.

[0066] (3) The carbon dioxide removal system according to (1) or (2), wherein the control device controls a switching mechanism arranged in the flow path and selects a mode in which a path is formed connecting the desorption path and all adsorption towers of the processing unit and all adsorption towers are depressurized, and a mode in which a path is formed connecting the desorption path and only one adsorption tower is depressurized and only one adsorption tower is depressurized.

[0067] (4) The carbon dioxide removal system according to any one of (1) to (3), wherein the adsorption tower is filled with an amine-impregnated adsorbent.

[0068] (5) The attachment / detachment path has a second retrieval path that connects to the target space, The control device is a carbon dioxide removal system according to (4), wherein the gas recovered by depressurizing the upstream adsorption tower is supplied to the target space from a second recovery path.

[0069] (6) The adsorption tower has a heater, The carbon dioxide removal system according to any one of (1) to (5), wherein the control device raises the temperature of the target adsorption tower with the heater when performing a desorption process of the substance adsorbed by the adsorption tower.

[0070] (7) A processing unit comprising: a processing gas acquisition unit that acquires a processing gas from a target space; a distribution path for distributing the acquired processing gas; a first processing unit in which two or more adsorption towers are connected in series to the distribution path along the flow of the processing gas; a second processing unit in which two or more adsorption towers are connected in series to the distribution path along the flow of the processing gas and is arranged in parallel with the first processing unit; and a control device for switching the processing gas path, wherein the distribution path comprises: a first main path that supplies the processing gas to the first processing unit; a second main path arranged in parallel with the first main path that supplies the processing gas to the second processing unit; and the first main path A carbon dioxide adsorption system comprising: a first recovery path for discharging the gas that has passed through a second main path into a target space; a desorption path connected to the adsorption tower which is depressurized; a path between the upstream adsorption tower and the downstream adsorption tower of the first processing unit; a first branch path connecting the first recovery path; and a switching mechanism for switching the path through which the gas flows, wherein the control device controls the switching mechanism located in the flow path and can switch between a mode in which the gas to be treated flows through all the adsorption towers of the first processing unit and a mode in which the gas to be treated flows through the first branch path, the gas to be treated flows through the upstream adsorption tower of the first processing unit, and the gas to be treated does not flow through the downstream adsorption tower.

[0071] (8) The carbon dioxide adsorption system according to (7), wherein the flow path has a path between the adsorption tower upstream of the second processing unit and the adsorption tower downstream of the second processing unit and a second branch path connecting the first recovery path, and the control device is selectable between a mode in which the gas to be treated flows to all the adsorption towers of the second processing unit and a mode in which the gas to be treated flows through the second branch path, the gas to be treated flows to the adsorption tower upstream of the second processing unit, and the gas to be treated does not flow to the adsorption tower downstream of the second processing unit.

[0072] (9) The carbon dioxide adsorption system according to (7) or (8), wherein the first branch path has a path that connects to the first main path located upstream of the upstream adsorption tower, and the control device is selectable to have a mode in which it flows the gas to be treated through the first branch path, flows the gas to be treated through the adsorption tower downstream of the first treatment unit, and does not flow the gas to be treated through the upstream adsorption tower.

[0073] (10) The desorption paths are connected to the upstream and downstream of the adsorption tower, The carbon dioxide removal system according to any one of (7) to (9), wherein the control device can further select a mode to switch to, which involves forming a path connecting the desorption path to only one adsorption tower and reducing the pressure of only one adsorption tower.

[0074] (11) The carbon dioxide removal system according to any one of (7) to (10), wherein the control device simultaneously performs an adsorption process in which the gas to be treated is supplied to at least one of the first and second adsorption towers, and a desorption process in which the adsorption tower not supplied with the gas to be treated is connected to the desorption path to desorb the adsorbed substance.

[0075] (12) The carbon dioxide removal system according to any one of (7) to (11), wherein the adsorption tower is filled with an amine-impregnated adsorbent.

[0076] (13) The carbon dioxide removal system according to (12), wherein the desorption path has a second recovery path connected to the target space, and the control device reduces the pressure of the upstream adsorption tower and supplies the recovered gas to the target space from the second recovery path.

[0077] (14) The carbon dioxide removal system according to any one of (7) to (13), wherein the adsorption tower has a heater, and the control device raises the temperature of the adsorption tower with the heater when performing a desorption process of a substance adsorbed by the adsorption tower.

[0078] Although embodiments of the present invention have been described above, the embodiments are not limited to those described herein. Furthermore, the aforementioned components include those that can be easily conceived by those skilled in the art, those that are substantially the same, and those that fall within the so-called equivalent range. Moreover, the aforementioned components can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the components can be made without departing from the spirit of the embodiments described above. [Explanation of symbols]

[0079] 6. Outdoor space 8. Target space 10. Carbon dioxide removal system 12. Intake section (section for acquiring the gas to be processed) 14 Distribution Channels 20 First Processing Unit 22 Second Processing Unit 24. First Recovery Route 26 Detachable Route 27 Second Recovery Route 28a, 28b Shut-off valves 30, 32 Blower 34 Vacuum pump 36 Control device 38 Power Source 38a battery 38b Solar Power Generation Section 40 Intake path 42. Primary pathway 44 Second primary pathway 50a, 50b Upstream adsorption tower 52a, 52b Midstream adsorption tower 54a, 54b Downstream adsorption towers 56a, 56b, 58a, 58b, 60a, 60b Intermediate routes 70a, 70b, 72a, 72b, 74a, 74b, 76a, 76b, 78a, 78b, 80a, 80b, 101a, 101b, 103a, 103b, 105a, 105b, 107a, 107b, 109a, 109b, 111a, 111b Shut-off valves Branch routes 100, 102, 104, 106, 108, 110

Claims

1. A gas acquisition unit that acquires the gas to be processed from the target space, The distribution route for the acquired gas to be processed, A processing unit comprising two or more adsorption towers connected in series in the flow path along the flow of the gas to be processed, The system includes a control device for switching the path of the gas to be processed, The aforementioned distribution route includes a first main route that supplies the gas to be processed to the processing unit, A first recovery path discharges the gas that has passed through the first main path into the target space, A desorption path connected to the adsorption tower which is subjected to reduced pressure, A path between the upstream adsorption tower and the downstream adsorption tower of the first processing unit, and a first branch path connecting the first recovery path, It has a switching mechanism for switching the gas flow path, The aforementioned desorption path is a carbon dioxide removal system that can be connected in parallel with multiple adsorption towers.

2. The carbon dioxide removal system according to claim 1, wherein the desorption path is connectable to both the upstream and downstream of the adsorption tower.

3. The carbon dioxide removal system according to claim 1, wherein the control device controls a switching mechanism arranged in the flow path and selects a mode in which a path is formed connecting the desorption path and all adsorption towers of the processing unit and all adsorption towers are depressurized, and a mode in which a path is formed connecting the desorption path and only one adsorption tower is depressurized and only one adsorption tower is depressurized.

4. The carbon dioxide removal system according to claim 1, wherein the adsorption tower is filled with an amine-impregnated adsorbent.

5. The aforementioned attachment / detachment path has a second retrieval path that connects to the target space, The carbon dioxide removal system according to claim 4, wherein the control device reduces the pressure of the upstream adsorption tower and supplies the recovered gas to the target space from a second recovery path.

6. The adsorption tower has a heater, The carbon dioxide removal system according to claim 1, wherein the control device raises the temperature of the adsorption tower with the heater when performing a desorption process for a substance adsorbed by the adsorption tower.

7. A gas acquisition unit that acquires the gas to be processed from the target space, The distribution route for the acquired gas to be processed, A first processing unit comprising two or more adsorption towers connected in series in the flow path along the flow of the gas to be processed, Along the flow of the gas to be treated, two or more adsorption towers are connected in series to the flow path, and a second processing unit is arranged in parallel with the first processing unit. The system includes a control device for switching the path of the gas to be processed, The aforementioned distribution route includes a first main route that supplies the gas to be processed to the first processing unit, A second main path is arranged in parallel with the first main path and supplies the gas to be processed to the second processing unit, A first recovery path discharges the gas that has passed through the first main path and the second main path into the target space, A desorption path connected to the adsorption tower which is subjected to reduced pressure, A path between the upstream adsorption tower and the downstream adsorption tower of the first processing unit, and a first branch path connecting the first recovery path, It has a switching mechanism for switching the gas flow path, The control device controls the switching mechanism arranged in the distribution path. A mode in which the gas to be treated is circulated through all the adsorption towers of the first processing unit, A carbon dioxide removal system that can switch between a mode in which the gas to be treated is circulated through the first branch path, the gas to be treated is circulated through the adsorption tower upstream of the first treatment unit, and the gas to be treated is not circulated through the adsorption tower downstream.

8. The distribution path includes a path between the adsorption tower upstream and the adsorption tower downstream of the second processing unit, and a second branch path connecting the first recovery path. The carbon dioxide removal system according to claim 7, wherein the control device is capable of selecting a mode in which the gas to be treated flows through all of the adsorption towers of the second processing unit, and a mode in which the gas to be treated flows through the second branch path, the gas to be treated flows through the upstream adsorption tower of the second processing unit, and the gas to be treated does not flow through the downstream adsorption tower.

9. The first branch path has a path that connects to the first main path located upstream of the upstream adsorption tower, The carbon dioxide removal system according to claim 7, wherein the control device is further capable of selecting, as a switchable mode, a mode in which the gas to be treated is circulated through the first branch path, the gas to be treated is circulated through the adsorption tower downstream of the first treatment unit, and the gas to be treated is not circulated through the adsorption tower upstream.

10. The aforementioned desorption / desorption paths are connected to the upstream and downstream of the adsorption tower, The carbon dioxide removal system according to claim 7, wherein the control device is capable of selecting a mode in which it forms a path connecting the desorption path to only one adsorption tower and depressurizes only one adsorption tower.

11. The carbon dioxide removal system according to claim 7, wherein the control device simultaneously performs an adsorption process in which it supplies a gas to be treated to at least one adsorption tower of the first processing unit and the second processing unit, and a desorption process in which it connects an adsorption tower that is not supplied with a gas to be treated to the desorption path and desorbs the adsorbed substance.

12. The carbon dioxide removal system according to claim 7, wherein the adsorption tower is filled with an amine-impregnated adsorbent.

13. The aforementioned attachment / detachment path has a second retrieval path that connects to the target space, The carbon dioxide removal system according to claim 12, wherein the control device reduces the pressure of the upstream adsorption tower and supplies the recovered gas to the target space from a second recovery path.

14. The adsorption tower has a heater, The carbon dioxide removal system according to claim 7, wherein the control device raises the temperature of the adsorption tower with the heater when performing a desorption process for a substance adsorbed by the adsorption tower.

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