CO2 recovery device

Abstract

To provide a CO2 capture device that can capture CO2 more efficiently than conventional methods. [Solution] In the CO2 recovery device, the water recovery unit adsorbs water and CO2 from the exhaust gas during the first period from the start of exhaust gas introduction, and during the second period, it adsorbs water from the exhaust gas while desorbing the CO2 adsorbed during the first period. The CO2 recovery unit adsorbs CO2 from the exhaust gas as it passes through the exhaust gas that has passed through the water recovery unit. The first detection unit detects the CO2 concentration downstream of the water recovery unit and upstream of the CO2 recovery unit. Based on the CO2 concentration detected by the first detection unit, the control unit switches the water recovery unit into which the exhaust gas is introduced from a water recovery unit into which exhaust gas is being introduced to a water recovery unit into which exhaust gas is not being introduced.

Description

Technical Field

[0001] This disclosure relates to a CO2 recovery device.

Background Art

[0002] A CO2 separation device for an internal combustion engine has been proposed that is provided in the exhaust system of an internal combustion engine and separates CO2 from exhaust gas (see, for example, Patent Document 1). The technology described in Patent Document 1 includes two water adsorbers and two CO2 adsorbers, and the exhaust gas is passed through the water adsorber and then through the CO2 adsorber.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, according to the study by the inventors of the present case, even if the configuration as described in Patent Document 1 is adopted, there may be a case where the adsorption capacity of the CO2 adsorber cannot be fully utilized, and there is room for improvement in this regard in the prior art.

[0005] Specifically, in the technology described in Patent Document 1, the CO2 concentration is measured on the downstream side of the CO2 adsorber, and when the CO2 concentration rises above a certain level, it is determined that the CO2 adsorber is in a saturated state, and the switching of the water adsorber and the CO2 adsorber is carried out. However, as a result of the study by the inventors of the present case, it has been found that switching the water adsorber at a timing different from the timing as described in Patent Document 1 can make use of the characteristics of the water adsorber and increase the amount of CO2 that can be adsorbed by the CO2 adsorber.

[0006] In one aspect of this disclosure, it is desirable to provide a CO2 recovery device that can recover CO2 more efficiently than the conventional method. [Means for solving the problem]

[0007] (A) One aspect of the present disclosure is a CO2 recovery device for recovering CO2 from the exhaust gas of an internal combustion engine, comprising a plurality of water recovery units, a plurality of CO2 recovery units, a first detection unit, and a control unit. The water recovery unit is configured to introduce exhaust gas from the upstream side and pass it through to the downstream side, and during the first period from the start of exhaust gas introduction, it adsorbs water and CO2 in the exhaust gas, and during the second period following the first period, it adsorbs water in the exhaust gas while desorbing the CO2 adsorbed during the first period. The CO2 recovery unit is configured to introduce exhaust gas that has passed through the water recovery unit from the upstream side and pass it through to the downstream side, and adsorbs CO2 in the exhaust gas as it passes through. The first detection unit is configured to detect the CO2 concentration of the exhaust gas in a flow path that is downstream of the water recovery unit and upstream of the CO2 recovery unit. The control unit is configured to perform switching control, based on the CO2 concentration detected by the first detection unit, to switch the water recovery unit into which the exhaust gas is introduced from a water recovery unit into which exhaust gas is being introduced to a water recovery unit into which exhaust gas is not being introduced.

[0008] In the CO2 recovery device configured in this way, the water recovery section adsorbs water and CO2 from the exhaust gas during the first period following the introduction of the exhaust gas. Then, in the second period following the first period, it adsorbs water from the exhaust gas while desorbing the CO2 adsorbed in the first period. Therefore, in the second period, the CO2 desorbed in the water recovery section is added to the exhaust gas passing through the water recovery section, and the CO2 concentration downstream of the water recovery section is higher than that of the exhaust gas introduced into the water recovery section.

[0009] However, the amount of CO2 released from the water recovery section is finite, and after the amount of CO2 released from the water recovery section reaches its maximum, the amount of CO2 released gradually decreases over time, and eventually no more CO2 is released from the water recovery section. Therefore, in a CO2 recovery device as one embodiment of the present disclosure, the CO2 concentration of the exhaust gas is detected by the first detection unit in the flow path that is downstream of the water recovery section and upstream of the CO2 recovery section. Based on the CO2 concentration detected by the first detection unit, the control unit switches the water recovery section into which the exhaust gas is introduced from a water recovery section into which exhaust gas is being introduced to a water recovery section into which exhaust gas is not being introduced.

[0010] With this CO2 recovery system, if the amount of CO2 desorbed in the water recovery section is sufficiently large, the water recovery section is not switched over. However, if the amount of CO2 desorbed in the water recovery section is not as large as expected, the water recovery section is switched over. This makes it possible to increase the CO2 concentration of the exhaust gas after passing through the water recovery section compared to the CO2 concentration of the exhaust gas before passing through the water recovery section. Therefore, exhaust gas with a higher CO2 concentration than the exhaust gas before passing through the water recovery section can be introduced into the CO2 recovery section, improving the CO2 recovery efficiency in the CO2 recovery section.

[0011] (B) In one aspect of the present disclosure, the control unit may be configured to switch the water recovery unit into which the exhaust gas is introduced from a water recovery unit into which exhaust gas is being introduced to a water recovery unit into which exhaust gas is not being introduced when the CO2 concentration detected by the first detection unit changes from a state in which the CO2 concentration is higher than a threshold concentration to a state in which the CO2 concentration is lower than a threshold concentration.

[0012] With a CO2 recovery device configured in this way, by setting a threshold concentration to a desired concentration, the water recovery unit can be switched over when the CO2 concentration falls below that concentration.

[0013] (C) In one aspect of this disclosure, the threshold concentration may be set to a concentration equal to or greater than the CO2 concentration of the exhaust gas flowing into the water recovery unit. With a CO2 recovery system configured in this way, the water recovery unit can be switched over when the CO2 concentration in the water recovery unit falls below the CO2 concentration in the exhaust gas flowing into the water recovery unit.

[0014] (D) In ​​one aspect of the present disclosure, the control unit may be configured to switch the CO2 recovery unit into which exhaust gas is introduced from a CO2 recovery unit that is introducing exhaust gas to a CO2 recovery unit that is not introducing exhaust gas, at a timing synchronized with the switching control.

[0015] With a CO2 recovery system configured in this way, the CO2 recovery unit can be switched over in synchronization with the water recovery unit, without needing to monitor the state of the CO2 recovery unit itself. (E) In one aspect of the present disclosure, a second detection unit may be provided, which is configured to detect the CO2 concentration of the exhaust gas in a flow path downstream of the CO2 recovery unit. The control unit may be configured to switch the CO2 recovery unit into which the exhaust gas is introduced from a CO2 recovery unit that is introducing exhaust gas to a CO2 recovery unit that is not introducing exhaust gas, based on the CO2 concentration detected by the second detection unit.

[0016] With a CO2 recovery system configured in this way, the CO2 concentration can be detected downstream of the CO2 recovery section, allowing for detection of the CO2 recovery section's lifespan being exceeded based on the CO2 concentration. In such cases, measures such as switching out the CO2 recovery section can be taken. [Brief explanation of the drawing]

[0017] [Figure 1] Figure 1 is a schematic diagram showing the general configuration of the CO2 capture device. [Figure 2] Figure 2A is an explanatory diagram showing a state where the first channel system is in the adsorption process and the second channel system is in the regeneration process. Figure 2B is an explanatory diagram showing a state where the first channel system is in the regeneration process and the second channel system is in the adsorption process. [Figure 3] Figure 3 is a flowchart of the flow path switching process. [Figure 4]FIG. 4A is a graph showing an example of the change over time of the CO2 concentration detected by the first detection unit. FIG. 4B is an explanatory diagram showing the adsorption states of water and CO2 in the water recovery unit. [Figure 5] FIG. 5A is a configuration diagram showing a modification of the configuration for switching the flow path of the water recovery unit. FIG. 5B is a configuration diagram showing a modification of the arrangement position of the first detection unit. [Figure 6] FIG. 6 is a configuration diagram showing a modification in which the water recovery unit and the CO2 recovery unit are directly connected one-to-one.

Mode for Carrying Out the Invention

[0018] Next, the above-described CO2 recovery device will be described with exemplary embodiments. [Configuration of CO2 Recovery Device] The CO2 recovery device 1 shown in FIG. 1 is a device that recovers CO2 from the exhaust gas of an internal combustion engine. The CO2 recovery device 1 includes a plurality of water recovery units 11A and 11B, a plurality of CO2 recovery units 13A and 13B, CO2 concentration sensors 15A and 15B as the first detection units, and CO2 concentration sensors 17A and 17B as the second detection units. Further, the CO2 recovery device 1 includes flow path switching valves 19A, 19B, 19C, 19D, 19E, 19F, pumps 21 and 23, a CO2 storage unit 25, and an ECU 27 as a control unit. Note that ECU is an abbreviation for Electronic Control Unit.

[0019] In the case of this embodiment, the plurality of water recovery units 11A and 11B are two water recovery units 11A and 11B. The water recovery units 11A and 11B are configured to introduce exhaust gas from the upstream side and pass it to the downstream side. More specifically, the water recovery units 11A and 11B have a structure in which an adsorbent having an adsorption ability for water and CO2 is filled inside a container having an inlet and an outlet, and are configured to introduce exhaust gas from the inlet and pass it to the outlet.

[0020] The adsorbent used in the water recovery units 11A and 11B is not particularly limited as long as it is an adsorbent having an adsorption capacity for water and CO2. As an example, for instance, silica gel, zeolite, activated alumina, etc. are suitable. When passing the exhaust gas, the water recovery units 11A and 11B adsorb water and CO2 in the exhaust gas during the first period from the start of introduction of the exhaust gas, and while adsorbing water in the exhaust gas during the second period following the first period, desorb the CO2 adsorbed during the first period. This point will be described in detail later.

[0021] In the case of this embodiment, the plurality of CO2 recovery units 13A and 13B are two CO2 recovery units 13A and 13B. The CO2 recovery units 13A and 13B are configured to introduce the exhaust gas that has passed through the water recovery units 11A and 11B from the upstream side and pass it to the downstream side. More specifically, the CO2 recovery units 13A and 13B have a structure in which a container having an inlet and an outlet is filled with an adsorbent having an adsorption capacity for water and CO2.

[0022] The inlet of the CO2 recovery units 13A and 13B is connected to the flow path from the outlet of the water recovery units 11A and 11B, and thus is configured to introduce the exhaust gas that has passed through the water recovery units 11A and 11B from the inlet and pass it to the outlet. The adsorbent used in the CO2 recovery units 13A and 13B is not particularly limited as long as it is an adsorbent having an adsorption capacity for CO2. As an example, for instance, zeolite, MOF (Metal Organic Frameworks), activated carbon, magnesium oxide, solid amine, calcium oxide, etc. are suitable. When passing the exhaust gas, the CO2 recovery units 13A and 13B adsorb CO2 in the exhaust gas.

[0023] CO2 concentration sensors 15A and 15B are configured to detect the CO2 concentration of exhaust gas in the flow path downstream of the water recovery units 11A and 11B and upstream of the CO2 recovery units 13A and 13B. CO2 concentration sensors 17A and 17B are configured to detect the CO2 concentration of exhaust gas in the flow path downstream of the CO2 recovery units 13A and 13B. The CO2 concentrations detected by the CO2 concentration sensors 15A, 15B, 17A, and 17B are input to the ECU 27.

[0024] In this embodiment, the flow path switching valves 19A to 19F are each composed of a three-way valve. The flow path switching valves 19A to 19F are operated under the control of the ECU 27. Pump 21 is a vacuum pump used to evacuate the inside of the water recovery sections 11A and 11B when they are moved to the regeneration process in order to restore their adsorption capacity. The gas sucked out from inside the water recovery sections 11A and 11B by pump 21 when it is operating contains water but almost no CO2, so it is released from pump 21 to the outside (i.e., outside the CO2 recovery device 1 system).

[0025] Pump 23 is a vacuum pump used to evacuate the inside of CO2 recovery units 13A and 13B when they are moved to the regeneration process in order to restore their adsorption capacity. The gas sucked out from inside the CO2 recovery units 13A and 13B by pump 23 when it is operating contains CO2, which is the target of recovery by the CO2 recovery device 1, and is therefore stored in the CO2 storage unit 25.

[0026] As described above, the CO2 storage unit 25 stores the gas sucked from inside the CO2 recovery units 13A and 13B by the pump 23. The CO2 storage unit 25 is filled with gas under high pressure by the pump 23. The inside of the CO2 storage unit 25 may be filled with the same adsorbent material as the CO2 recovery units 13A and 13B. The CO2 storage unit 25 may be equipped with a mechanism to liquefy and store the gas supplied by the pump 23. If the CO2 storage unit 25 becomes full, if the CO2 storage unit 25 is replaceable, it can be replaced with a new CO2 storage unit 25; if the CO2 storage unit 25 is not replaceable, the CO2 in the storage unit 25 can be recovered by a separate device.

[0027] [Switching between adsorption and regeneration processes] Figure 2A shows the state in the CO2 recovery device 1 where the flow path system (hereinafter also referred to as the first flow path system) comprising the water recovery unit 11A and the CO2 recovery unit 13A is in the adsorption process. At this time, the flow path system (hereinafter also referred to as the second flow path system) comprising the water recovery unit 11B and the CO2 recovery unit 13B is in the regeneration process. Figure 2B shows the state in the CO2 recovery device 1 where the second flow path system (comprising the water recovery unit 11B and the CO2 recovery unit 13B) is in the adsorption process. At this time, the first flow path system (comprising the water recovery unit 11A and the CO2 recovery unit 13A) is in the regeneration process.

[0028] In this embodiment, the state shown in Figure 2A and the state shown in Figure 2B are alternately switched by the ECU 27. In this embodiment, as described above, two systems, the first flow path system and the second flow path system, are switched alternately, but it is also possible to configure the system to switch between three or more flow path systems in sequence.

[0029] For example, if the service life of one channel system in the adsorption process is only half the time required for the regeneration process, it is advisable to operate by sequentially switching between three channel systems. In this case, by operating one channel system in the adsorption process while overlapping and operating the other two channel systems in the regeneration process, continuous operation is possible with at least one system always in the adsorption process.

[0030] Furthermore, even if, for example, the service life of one channel system in the adsorption process is twice the time required for the regeneration process, it is advisable to operate by sequentially switching between the three channel systems. In this case, by operating two channel systems in the adsorption process with overlapping configurations while operating one channel system in the regeneration process, continuous operation is possible with two systems always in the adsorption process.

[0031] [Flow path switching process] Next, the flow path switching process performed by ECU27 will be explained based on Figure 3. The flow path switching process described below is a process to switch which of the first and second flow path systems described above will be used in the adsorption process.

[0032] When the flow path switching process is initiated, the ECU27 directs exhaust gas to the first flow path system (S1). Specifically, the ECU27 controls the flow path switching valves 19A, 19B, 19C, and 19D to switch them so that exhaust gas flows to the first flow path system, which includes the water recovery unit 11A and the CO2 recovery unit 13A, as shown in Figure 2A.

[0033] Next, the ECU27 determines whether the CO2 concentration at the outlet of the water recovery unit 11A has transitioned from a state higher than the specified CO2 concentration to a state lower than the specified CO2 concentration (S2). If the CO2 concentration at the outlet of the water recovery unit 11A has not transitioned from a state higher than the specified CO2 concentration to a state lower than the specified CO2 concentration (S2:NO), the process returns to S1.

[0034] If the CO2 recovery device 1 continues to operate in this state, the CO2 concentration detected by the CO2 concentration sensor 15A will change over time as shown in Figure 4A. Specifically, in the water recovery unit 11A, water and CO2 from the exhaust gas are adsorbed during the first period from the start of exhaust gas introduction. Therefore, the CO2 concentration does not rise for a while after the start of exhaust gas introduction.

[0035] At this time, as shown in Figure 4B, water and CO2 are adsorbed inside the water recovery section 11A. However, the water recovery section 11A is filled with an adsorbent that has a stronger adsorption capacity for water than for CO2. Therefore, in the zones where water has been adsorbed, the water is not pushed out of the adsorbent by the CO2, while in the zones where CO2 has been adsorbed, the CO2 is pushed out of the adsorbent by the water.

[0036] As a result, inside the water recovery unit 11A, as shown in the upper, middle, and lower sections of Figure 4B, the water adsorption zone and the CO2 adsorption zone expand over time as they move towards the outlet side of the water recovery unit 11A, and eventually CO2 leaks out from the outlet of the water recovery unit 11A. The amount of CO2 leaking out is the difference between the amount of CO2 adsorbed inside the water recovery unit 11A and the amount of CO2 released, so even if CO2 leaks out of the water recovery unit 11A, the CO2 concentration does not immediately increase, but rather rises gradually.

[0037] When the amount of CO2 desorbed in the water recovery unit 11A exceeds the amount of CO2 adsorbed, the CO2 concentration of the exhaust gas that has passed through the water recovery unit 11A (i.e., the CO2 concentration after water adsorption) exceeds the CO2 concentration before passing through the water recovery unit 11A (i.e., the CO2 concentration before water adsorption). The period during which the CO2 concentration after water adsorption exceeds the CO2 concentration before water adsorption continues for a certain period. However, after the CO2 concentration after water adsorption reaches its maximum value, it gradually decreases and eventually becomes about the same as the CO2 concentration before water adsorption. This is because there is no more CO2 to be desorbed from the water recovery unit 11A.

[0038] As the CO2 concentration gradually decreases after water adsorption, at time T1 shown in Figure 4, the CO2 concentration after water adsorption (i.e., the CO2 concentration at the outlet of the water recovery unit 11A) transitions from a state higher than the specified CO2 concentration to a state lower than the specified CO2 concentration. Therefore, at S2 of the flow path switching process shown in Figure 3, it is determined that the CO2 concentration at the outlet of the water recovery unit 11A has transitioned from a state higher than the specified CO2 concentration to a state lower than the specified CO2 concentration (S2: YES), and the ECU 27 flows exhaust gas to the second flow path system (S3). Specifically, the ECU 27 controls the flow path switching valves 19A, 19B, 19C, and 19D to switch them so that exhaust gas flows to the second flow path system, which includes the water recovery unit 11B and the CO2 recovery unit 13B, as shown in Figure 2B.

[0039] Next, the ECU27 determines whether the CO2 concentration at the outlet of the water recovery unit 11B has transitioned from a state higher than the specified CO2 concentration to a state lower than the specified CO2 concentration (S4). If the CO2 concentration at the outlet of the water recovery unit 11B has not transitioned from a state higher than the specified CO2 concentration to a state lower than the specified CO2 concentration (S4:NO), the process returns to S1. From this point onward, the process in S4 proceeds in the same manner as the process in S2, so redundant explanations will be omitted.

[0040] In S4, if it is determined that the CO2 concentration at the outlet of the water recovery unit 11B has shifted from a state higher than the specified CO2 concentration to a state lower than the specified CO2 concentration (S4: YES), the process returns to S1. As a result, the ECU 27 once again flows exhaust gas into the first flow path system (S1), and thereafter, the state of flowing exhaust gas into the first flow path system and the state of flowing exhaust gas into the first flow path system alternate.

[0041] [effect] According to the CO2 recovery device 1 described above, the ECU 27 switches the water recovery units 11A and 11B into which the exhaust gas is introduced, from the water recovery unit 11A (or water recovery unit 11B) that is introducing exhaust gas to the water recovery unit 11B (or water recovery unit 11A) that is not introducing exhaust gas, based on the CO2 concentration detected by the CO2 concentration sensors 15A and 15B. Therefore, the CO2 concentration of the exhaust gas after passing through the water recovery unit can be increased compared to the CO2 concentration of the exhaust gas before passing through the water recovery unit. Consequently, exhaust gas with a higher CO2 concentration than the exhaust gas before passing through the water recovery unit can be introduced to the CO2 recovery units 13A and 13B, improving the CO2 recovery efficiency in the CO2 recovery units 13A and 13B.

[0042] Furthermore, in this embodiment, the water recovery unit can be switched when the CO2 concentration falls below a specified threshold CO2 concentration. In this embodiment, the specified CO2 concentration is set to be equal to or higher than the CO2 concentration of the exhaust gas flowing into the water recovery units 11A and 11B. Therefore, the water recovery units 11A and 11B can be switched when the CO2 concentration falls below the CO2 concentration of the exhaust gas flowing into the water recovery units 11A and 11B.

[0043] Furthermore, the ECU27 switches the CO2 recovery units 13A and 13B, which receive exhaust gas, from CO2 recovery unit 13A (or CO2 recovery unit 13B) that is currently receiving exhaust gas to CO2 recovery unit 13B (or CO2 recovery unit 13A) that is not currently receiving exhaust gas, at a timing synchronized with the switching control of the water recovery units 11A and 11B. Therefore, the switching of CO2 recovery units 13A and 13B can be performed in synchronization with the switching of the water recovery units 13A and 13B, without monitoring the state of the CO2 recovery units 13A and 13B themselves.

[0044] [Other embodiments] Although the CO2 capture device has been described above with reference to exemplary embodiments, the above-described embodiments are merely illustrative examples of one aspect of the present disclosure. In other words, the present disclosure is not limited to the above-described exemplary embodiments and can be implemented in various forms without departing from the technical idea of ​​the present disclosure.

[0045] For example, in the above embodiment, an example was shown in which each of the flow path switching valves 19A to 19F is composed of a three-way valve. However, as shown in Figure 5A, each of the flow path switching valves 41A, 41B, 41C, and 41D may be composed of a two-way valve. Note that Figure 5A shows only the flow path switching valves 41A to 41D located near the water recovery units 11A and 11B, but each of the flow path switching valves located near the CO2 recovery units 13A and 13B may also be composed of a two-way valve.

[0046] Furthermore, in the above embodiment, an example was shown in which a CO2 concentration sensor 15A is provided downstream of the water recovery unit 11A and a CO2 concentration sensor 15B is provided downstream of the water recovery unit. However, a single CO2 concentration sensor 43A may be provided at the point where the flow paths from the water recovery units 11A and 11B merge.

[0047] Furthermore, in the above embodiment, flow path switching valves 19B and 19C were provided between the water recovery units 11A and 11B and the CO2 recovery units 13A and 13B, but these can be omitted. For example, as shown in Figure 6, the water recovery unit 11A and the CO2 recovery unit 13A may be directly connected one-to-one, and the water recovery unit 11B and the CO2 recovery unit 13B may be directly connected one-to-one.

[0048] However, with a CO2 recovery device 1 configured as shown in Figure 1, the CO2 recovery units 13A and 13B can be switched in synchronization with the timing of switching the water recovery units 11A and 11B, as in the above-described embodiment, and asynchronous switching can also be achieved.

[0049] In other words, in the configuration shown in Figure 6, the water recovery unit 11A and the CO2 recovery unit 13A are always used simultaneously, and the water recovery unit 11B and the CO2 recovery unit 13B are always used simultaneously. In contrast, with the CO2 recovery device 1 configured as shown in Figure 1, it is possible to avoid switching the CO2 recovery units 13A and 13B at the same time as switching the water recovery units 11A and 11B.

[0050] If the switching of CO2 recovery units 13A and 13B is to be performed asynchronously with the switching of water recovery units 11A and 11B, for example, CO2 concentration sensors 17A and 17B located in the flow path downstream of CO2 recovery units 13A and 13B can be used. For example, the ECU 27 should be configured to switch the CO2 recovery unit into which exhaust gas is introduced from a CO2 recovery unit that is introducing exhaust gas to a CO2 recovery unit that is not introducing exhaust gas, based on the CO2 concentration detected by the CO2 concentration sensors 17A and 17B.

[0051] Furthermore, multiple functions realized by one component as exemplified in the above embodiment may be realized by multiple components. One function realized by one component as exemplified in the above embodiment may be realized by multiple components. Multiple functions realized by multiple components as exemplified in the above embodiment may be realized by one component. One function realized by multiple components as exemplified in the above embodiment may be realized by one component. Some of the configurations exemplified in the above embodiment may be omitted. At least a part of the configuration exemplified in one of the above embodiments may be added to or replaced with the configuration exemplified in the other embodiments.

[0052] [Technical concepts disclosed in this specification] [Item 1] A CO2 recovery device that recovers CO2 from the exhaust gas of an internal combustion engine, The system is configured to introduce the exhaust gas from the upstream side and pass it through to the downstream side, and during the passage of the exhaust gas, in the first period from the start of the introduction of the exhaust gas, water and CO2 in the exhaust gas are adsorbed, and in the second period following the first period, water is adsorbed from the exhaust gas while the CO2 adsorbed in the first period is desorbed, and The system is configured to introduce the exhaust gas that has passed through the water recovery unit from the upstream side and pass it downstream, and includes a plurality of CO2 recovery units that adsorb CO2 in the exhaust gas as it passes through, A first detection unit is configured to detect the CO2 concentration of the exhaust gas in a flow path that is downstream of the water recovery unit and upstream of the CO2 recovery unit. A control unit is configured to perform switching control to switch the water recovery unit into which the exhaust gas is introduced, based on the CO2 concentration detected by the first detection unit, from the water recovery unit into which the exhaust gas is being introduced to the water recovery unit into which the exhaust gas is not being introduced. A CO2 capture device equipped with the following features.

[0053] [Item 2] The CO2 capture device described in item 1, The control unit is configured to switch the water recovery unit into which the exhaust gas is introduced from a water recovery unit into which the exhaust gas is being introduced to a water recovery unit into which the exhaust gas is not being introduced, when the CO2 concentration detected by the first detection unit changes from a state where it is higher than a threshold concentration to a state where it is lower than a threshold concentration. CO2 capture device.

[0054] [Item 3] CO2 capture device as described in item 2, The threshold concentration is set to be equal to or greater than the CO2 concentration of the exhaust gas flowing into the water recovery unit. CO2 capture device.

[0055] [Item 4] A CO2 recovery device described in any one of items 1 to 3, The control unit is configured to switch the CO2 recovery unit into which the exhaust gas is introduced, from a CO2 recovery unit that is currently introducing the exhaust gas to a CO2 recovery unit that is not currently introducing the exhaust gas, at a timing synchronized with the switching control. CO2 capture device.

[0056] [Item 5] A CO2 recovery device described in any one of items 1 to 3, A second detection unit is configured to detect the CO2 concentration of the exhaust gas in a flow path downstream of the CO2 recovery unit. Equipped with, The control unit is configured to switch the CO2 recovery unit into which the exhaust gas is introduced, based on the CO2 concentration detected by the second detection unit, from the CO2 recovery unit that is introducing the exhaust gas to the CO2 recovery unit that is not introducing the exhaust gas. CO2 capture device. [Explanation of Symbols]

[0057] 1...CO2 recovery unit, 11A,11B...Water recovery unit, 13A,13B...CO2 recovery unit, 15A,15B,17A,17B,43A...CO2 concentration sensor, 19A,19B,19C,19D,19E,19F,41A,41B,41C,41D...Flow path switching valve, 21,23...Pump, 25...CO2 storage unit, 27...ECU.

Claims

1. A CO2 recovery device that recovers CO2 from the exhaust gas of an internal combustion engine, The system is configured to introduce the exhaust gas from the upstream side and pass it downstream, and during the passage of the exhaust gas, in the first period from the start of the introduction of the exhaust gas, water and CO2 in the exhaust gas are adsorbed, and in the second period following the first period, water is adsorbed from the exhaust gas while the CO2 adsorbed in the first period is desorbed, and The system is configured to introduce the exhaust gas that has passed through the water recovery section from the upstream side and pass it downstream, and includes a plurality of CO2 recovery sections that adsorb CO2 in the exhaust gas as it passes through, A first detection unit is configured to detect the CO2 concentration of the exhaust gas in a flow path that is downstream of the water recovery unit and upstream of the CO2 recovery unit. A control unit is configured to perform switching control to switch the water recovery unit into which the exhaust gas is introduced, based on the CO2 concentration detected by the first detection unit, from the water recovery unit into which the exhaust gas is being introduced to the water recovery unit into which the exhaust gas is not being introduced. A CO2 recovery device equipped with the following features.

2. A CO2 recovery device according to claim 1, The control unit is configured to switch the water recovery unit into which the exhaust gas is introduced from a water recovery unit into which the exhaust gas is being introduced to a water recovery unit into which the exhaust gas is not being introduced, when the CO2 concentration detected by the first detection unit changes from a state where it is higher than a threshold concentration to a state where it is lower than a threshold concentration. CO2 recovery device.

3. A CO2 recovery device according to claim 2, The threshold concentration is set to be equal to or greater than the CO2 concentration of the exhaust gas flowing into the water recovery unit. CO2 recovery device.

4. A CO2 recovery device according to any one of claims 1 to 3, The control unit is configured to switch the CO2 recovery unit into which the exhaust gas is introduced from the CO2 recovery unit that is currently introducing the exhaust gas to the CO2 recovery unit that is not currently introducing the exhaust gas, at a timing synchronized with the switching control. CO2 recovery device.

5. A CO2 recovery device according to any one of claims 1 to 3, A second detection unit is configured to detect the CO2 concentration of the exhaust gas in a flow path downstream of the CO2 recovery unit. Equipped with, The control unit is configured to switch the CO2 recovery unit into which the exhaust gas is introduced, based on the CO2 concentration detected by the second detection unit, from the CO2 recovery unit in which the exhaust gas is being introduced to the CO2 recovery unit in which the exhaust gas is not being introduced. CO2 recovery device.

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