CO2 recovery device

Abstract

It promotes the elimination of H2O. [Solution] The CO2 recovery device comprises an H2O recovery unit, a CO2 recovery unit, an exhaust channel, an air intake channel, and a pump. The H2O recovery unit is configured to recover H2O from the exhaust gas of an internal combustion engine using an H2O adsorbent. The CO2 recovery unit is configured to recover CO2 contained in the exhaust gas from which H2O has been recovered. The exhaust channel connects the H2O recovery unit to the outside. The air intake channel introduces air into the H2O recovery unit. The pump is provided in the exhaust channel and is configured to desorb H2O adsorbed on the H2O adsorbent and to discharge the desorbed H2O to the outside.

Description

Technical Field

[0001] The present disclosure relates to a CO2 recovery device configured to recover CO2 from the exhaust gas of an internal combustion engine.

Background Art

[0002] As described in Patent Document 1, a CO2 separation device for removing CO2 from the exhaust gas of a vehicle's internal combustion engine is known. The CO2 separation device includes a H2O adsorber and a CO2 adsorber. The exhaust gas from the internal combustion engine first flows into the H2O adsorber, and the H2O contained in the exhaust gas is removed by the adsorbent in the H2O adsorber. Then, the exhaust gas that has passed through the H2O adsorber flows into the CO2 adsorber, and the CO2 contained in the exhaust gas is removed by the adsorbent in the CO2 adsorber.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the CO2 separation device of Patent Document 1, the pressure of the H2O adsorber is reduced by a vacuum pump to desorb H2O from the H2O adsorbent in the H2O adsorber, and the desorbed H2O is discharged outside the vehicle. However, as the pressure of the H2O adsorber decreases, the gas flow in the internal space where the H2O adsorbent of the H2O adsorber is arranged is suppressed, and the desorbed H2O stays near the H2O adsorbent. As a result, there is a risk that the desorption of H2O is suppressed.

[0005] In one aspect of the present disclosure, it is desirable to promote the desorption of H2O.

Means for Solving the Problems

[0006] One aspect of the present disclosure is a CO2 recovery device configured to recover CO2 from the exhaust gas of an internal combustion engine, comprising: an H2O recovery unit; a CO2 recovery unit; an exhaust passage; an atmospheric inlet passage; and a pump. The H2O recovery unit is configured to recover H2O from the exhaust gas by adsorbing H2O contained in the exhaust gas with an H2O adsorbent. The CO2 recovery unit is configured to recover CO2 contained in the exhaust gas from which H2O has been recovered in the H2O recovery unit. The exhaust passage is provided in correspondence with the H2O recovery unit and is a passage that connects the H2O recovery unit to the outside. The atmospheric inlet passage is provided in correspondence with the H2O recovery unit and is a passage for introducing atmospheric air into the H2O recovery unit. The pump is provided in the exhaust passage and is configured to reduce the pressure in the H2O recovery unit, thereby desorbing H2O adsorbed on the H2O adsorbent, and to discharge the H2O desorbed from the H2O adsorbent to the outside.

[0007] With the above configuration, when the pressure in the H2O recovery section is reduced to desorb the H2O adsorbed on the H2O adsorbent, air can be introduced into the H2O recovery section via the air intake passage, thereby promoting gas flow in the H2O recovery section. Consequently, the accumulation of desorbed H2O near the H2O adsorbent is suppressed, and the desorption of H2O can be promoted.

[0008] One aspect of the present disclosure may further include a CO2 recovery device comprising a control unit that performs processing for opening and closing an air intake passage, and a determination unit that determines whether the pressure in the H2O recovery unit is below a predetermined opening threshold. The control unit may close the air intake passage corresponding to the H2O recovery unit from the time the pressure in the H2O recovery unit starts to decrease due to the pump until the determination unit determines that the pressure in the H2O recovery unit is below the opening threshold, and when the determination unit determines that the pressure in the H2O recovery unit has reached below the opening threshold, it may open the air intake passage corresponding to the H2O recovery unit and allow air to flow into the H2O recovery unit while maintaining the reduced pressure in the H2O recovery unit.

[0009] With the above configuration, when the pressure in the H2O recovery section is reduced to desorb the H2O adsorbed onto the H2O adsorbent, the flow of gas in the H2O recovery section can be promoted. Therefore, the accumulation of desorbed H2O near the H2O adsorbent can be suppressed, and the desorption of H2O can be promoted.

[0010] One aspect of the present disclosure is that the air intake channel may be configured to allow air to flow into the H2O recovery section while maintaining the reduced pressure in the H2O recovery section when the pump reduces the pressure in the H2O recovery section corresponding to the air intake channel.

[0011] With the above configuration, when the pressure in the H2O recovery section is reduced to desorb the H2O adsorbed onto the H2O adsorbent, the flow of gas in the H2O recovery section can be promoted. Therefore, the accumulation of desorbed H2O near the H2O adsorbent can be suppressed, and the desorption of H2O can be promoted.

[0012] One aspect of this disclosure may further include a plurality of H2O recovery units, a plurality of discharge channels and a plurality of air intake channels provided corresponding to each H2O recovery unit. The plurality of discharge channels may include a common discharge section, which is a section where the plurality of discharge channels merge into one. A pump may be provided in the common discharge section.

[0013] With the above configuration, a common pump can be used for multiple H2O recovery units. Therefore, compared to the case where multiple pumps are provided for each of the multiple H2O recovery units, the number of pumps can be reduced, and thus the CO2 recovery device can be made smaller. [Brief explanation of the drawing]

[0014] [Figure 1] This is a diagram illustrating a CO2 capture device. [Figure 2] This is a flowchart for the atmospheric intake treatment process. [Modes for carrying out the invention]

[0015] Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the drawings. [1. First Embodiment] [(1) Overview] The CO2 recovery device 1 of the first embodiment is mounted on a vehicle equipped with an internal combustion engine and is configured to recover CO2 from exhaust gas emitted from the internal combustion engine (see Figure 1). The vehicle may be, for example, one that uses only an internal combustion engine as a power source, or a hybrid vehicle equipped with an internal combustion engine and a motor. In addition, the CO2 recovery device 1 may be mounted on various machines and equipment equipped with an internal combustion engine instead of a vehicle, for example, on construction machinery equipped with an internal combustion engine. The CO2 recovery device 1 comprises first and second H2O recovery units 2A, 2B, first and second CO2 recovery units 3A, 3B, an H2O desorption pump 4, a CO2 storage unit 5, a CO2 desorption pump 6, and a control unit 7.

[0016] [(2) Configuration of the flow path] The CO2 recovery device 1 comprises gas flow paths formed by pipes and other components, namely the first to seventh flow paths P01 to P07, the first to sixth desorption flow paths P11 to P16, and the first and second atmospheric inlet passages P21 and P22 (see Figure 1). The CO2 recovery device 1 also comprises the first to eighth valves V1 to V8. The first to sixth valves V1 to V6 are configured as three-way valves, for example, to switch the flow path through which the gas passes. The seventh and eighth valves V7 and V8 are configured as two-way valves, for example, to open and close the flow path. Furthermore, the flow rate of gas passing through the flow path can be adjusted by adjusting the opening degree of the seventh and eighth valves V7 and V8.

[0017] The first flow path P01 receives exhaust gas from the internal combustion engine from its starting point, and its end is connected to the first valve V1. The second and third channels P02 and P03 are each connected at their starting end to the first valve V1 and at their ending end to the second valve V2. The second channel P02 is provided with a first H2O recovery section 2A, and the third channel P03 is provided with a second H2O recovery section 2B.

[0018] The fourth flow path P04 has its starting end connected to the second valve V2 and its ending end connected to the third valve V3. The fifth and sixth flow paths P05 and P06 each have their starting ends connected to the third valve V3 and their ending ends connected to the fourth valve V4. Further, the first CO2 recovery section 3A is provided in the fifth flow path P05, and the second CO2 recovery section 3B is provided in the sixth flow path P06.

[0019] The seventh flow path P07 has its starting end connected to the fourth valve V4 and its ending end open to the outside of the vehicle. The first detachment flow path P11 is provided corresponding to the first H2O recovery section 2A. The first detachment flow path P11 has its starting end connected to the first H2O recovery section 2A and its ending end connected to the fifth valve V5.

[0020] The second detachment flow path P12 is provided corresponding to the second H2O recovery section 2B. The second detachment flow path P12 has its starting end connected to the second H2O recovery section 2B and its ending end connected to the fifth valve V5. The third detachment flow path P13 has its starting end connected to the fifth valve V5 and its ending end open to the outside of the vehicle.

[0021] That is, the first and third detachment flow paths P11 and P13 form a first discharge flow path, which is a flow path that communicates the first H2O recovery section 2A and the outside of the vehicle. Also, the second and third detachment flow paths P12 and P13 form a second discharge flow path, which is a flow path that communicates the second H2O recovery section 2B and the outside of the vehicle. That is, the third detachment flow path P13 is a common discharge section where the first and second discharge flow paths merge into one. A H2O detachment pump 4 is provided in the third detachment flow path P13.

[0022] The first end of the fourth detachment flow path P14 is connected to the first CO2 recovery section 3A, and the second end is connected to the sixth valve V6. The first end of the fifth detachment flow path P25 is connected to the second CO2 recovery section 3B, and the second end is connected to the sixth valve V6.

[0023] The first end of the sixth detachment flow path P16 is connected to the sixth valve V6, and the second end is connected to the CO2 storage section 5. In other words, the fourth and sixth desorption channels P14 and P16 form a first storage channel, which is a channel connecting the first CO2 recovery section 3A and the CO2 storage section 5. Also, the fifth and sixth desorption channels P15 and P16 form a second storage channel, which is a channel connecting the second CO2 recovery section 3B and the CO2 storage section 5. That is, the sixth desorption channel P16 is a common discharge section, which is the section where the first and second storage channels merge into one. A CO2 desorption pump 6 is provided in the sixth desorption channel P16.

[0024] The first atmospheric intake passage P21 is provided in correspondence with the first H2O recovery section 2A. The first atmospheric intake passage P21 is open to the outside of the vehicle at its starting end and connected to the first H2O recovery section 2A at its end. A seventh valve V7 is provided in the first atmospheric intake passage P21.

[0025] The second atmospheric intake passage P22 is provided in correspondence with the second H2O recovery section 2B. The starting end of the second atmospheric intake passage P22 is open to the outside of the vehicle, and the end is connected to the second H2O recovery section 2B. An eighth valve V8 is provided in the second atmospheric intake passage P22.

[0026] [(3) First and Second H2O Recovery Sections] The first and second H2O recovery units 2A and 2B are equipped with an H2O adsorbent such as silica gel, zeolite, or activated alumina (see Figure 1). The first H2O recovery unit 2A recovers H2O from the exhaust gas by adsorbing the H2O contained in the exhaust gas flowing in from the second flow path P02 using the H2O adsorbent. The first H2O recovery unit 2A then discharges the exhaust gas from which H2O has been recovered into the second flow path P02. Similarly, the second H2O recovery unit 2B recovers H2O from the exhaust gas flowing down the third flow path P03, and then discharges the exhaust gas into the third flow path P03.

[0027] In other words, the first and second H2O recovery units 2A and 2B remove H2O from the exhaust gas from which CO2 is recovered in the first and second CO2 recovery units 3A and 3B. This prevents the H2O in the exhaust gas from being adsorbed by the CO2 adsorbent in the first and second CO2 recovery units 3A and 3B, thus suppressing a decrease in the CO2 adsorption effect of the CO2 adsorbent.

[0028] [(4) First and Second CO2 Recovery Sections] The first and second CO2 recovery units 3A and 3B are equipped with CO2 adsorbents such as zeolite, MOF, activated carbon, magnesium oxide, solid amine, calcium oxide, etc. (see Figure 1). The first CO2 recovery unit 3A recovers CO2 from the exhaust gas flowing in from the fifth flow path P05 by adsorbing the CO2 contained in the exhaust gas with the CO2 adsorbent. The first CO2 recovery unit 3A then discharges the exhaust gas from which CO2 has been recovered into the fifth flow path P05. Similarly, the second CO2 recovery unit 3B recovers CO2 from the exhaust gas flowing down the sixth flow path P06, and then discharges the exhaust gas into the sixth flow path P06.

[0029] [(5) CO2 storage section] The CO2 storage unit 5 is configured to store the CO2 recovered from the exhaust gas by the first and second CO2 recovery units 3A and 3B (see Figure 1). The CO2 storage unit 5 may, for example, be equipped with a CO2 adsorbent similar to that of the first and second CO2 recovery units 3A and 3B, and store CO2 by adsorption onto the CO2 adsorbent, or it may be configured as a cylinder.

[0030] [(6) H2O desorption pumps and CO2 desorption pumps] The H2O desorption pump 4 is configured to desorb H2O adsorbed onto the H2O adsorbent in the first and second H2O recovery units 2A and 2B, and to discharge the desorbed H2O outside the vehicle (see Figure 1).

[0031] More specifically, the H2O desorption pump 4 depressurizes the space where the H2O adsorbent is located in any of the H2O recovery sections via the first to third desorption channels P11 to P13, thereby creating a vacuum and desorbing H2O from the H2O adsorbent. The H2O desorption pump 4 then discharges the desorbed H2O outside the vehicle via the third desorption channel P13.

[0032] The CO2 desorption pump 6 is configured to desorb CO2 adsorbed on the CO2 adsorbent in the first and second CO2 recovery sections 3A and 3B, and to allow the desorbed CO2 to flow into the CO2 storage section 5.

[0033] More specifically, the CO2 desorption pump 6 depressurizes the space where the CO2 adsorbent is located in any of the CO2 recovery sections via the 4th to 6th desorption channels P14 to P16, thereby creating a vacuum and desorbing CO2 from the CO2 adsorbent. The CO2 desorption pump 6 then flows the desorbed CO2 into the CO2 storage section 5 via the 6th desorption channel P16, and stores the CO2 in the CO2 storage section 5.

[0034] Hereafter, the first and second H2O recovery units will be referred to simply as H2O recovery units, and the first and second CO2 recovery units will be referred to simply as CO2 recovery units. Furthermore, the H2O recovery unit and the CO2 recovery unit will be referred to simply as recovery units. Also, H2O and CO2 will be referred to as recovered gases. Furthermore, the H2O adsorbent and the CO2 adsorbent will be referred to simply as adsorbents.

[0035] [(7) Control Unit] The control unit 7 is configured to control various parts of the CO2 recovery device 1, such as the first to eighth valves V1 to V8, the H2O desorption pump 4, and the CO2 desorption pump 6, by transmitting signals to these parts, and includes a CPU and memory (see Figure 1). The CPU executes a program stored in the memory, thereby realizing various functions of the CO2 recovery device 1. Note that the various functions realized by the control unit 7 are not limited to being realized by program execution; some or all of them may be realized using one or more hardware components.

[0036] [(8) Processing of CO2 recovery equipment] The control unit 7 sets one of the first and second H2O recovery units 2A and 2B in the adsorption state and the other in the desorption state, and switches the H2O recovery unit that becomes the adsorption state and the desorption state at a predetermined switching timing (see FIG. 1). Similarly, the control unit 7 sets one of the first and second CO2 recovery units 3A and 3B in the adsorption state and the other in the desorption state, and switches the H2O recovery unit and the CO2 recovery unit that become the adsorption state and the desorption state at a predetermined switching timing.

[0037] Then, in the H2O recovery unit in the adsorption state, H2O is recovered from the exhaust gas, and in the CO2 recovery unit in the adsorption state, CO2 is recovered from the exhaust gas. On the other hand, in the H2O recovery unit in the desorption state, H2O is desorbed by the H2O desorption pump 4, and in the CO2 recovery unit in the desorption state, CO2 is desorbed by the CO2 desorption pump 6.

[0038] <Switching Timing> The switching timing of the H2O recovery unit may be the timing when the remaining amount of H2O that can be adsorbed in the H2O recovery unit in the adsorption state decreases. Specifically, for example, based on the amount of the H2O adsorbent provided in each H2O recovery unit, the operating time (upper limit time) of the H2O recovery unit when the remaining amount of H2O that can be adsorbed decreases may be determined in advance. Then, after newly setting the H2O recovery unit in the adsorption state, the timing when the operating time of the H2O recovery unit reaches the upper limit time may be used as the switching timing. Also, for example, the control unit 7 detects the concentration of H2O contained in the exhaust gas in the flow path on the downstream side of the H2O recovery unit in the adsorption state by a sensor, and the timing when the concentration becomes equal to or higher than the threshold value may be used as the switching timing.

[0039] Also, the switching timing of the CO2 recovery unit may also be the timing when the remaining amount of CO2 that can be adsorbed in the CO2 recovery unit in the adsorption state decreases. Specifically, similar to the H2O recovery unit, the switching timing may be determined based on the operating time of the CO2 recovery unit or the CO2 concentration of the exhaust gas in the flow path of the CO2 recovery unit in the adsorption state measured by a sensor.

[0040] <Cycle of H2O Recovery Unit> When the first H2O recovery unit 3A is in an adsorption state and the second H2O recovery unit 3B is in a desorption state (hereafter referred to as the first cycle), the control unit 7 controls the valve as follows (see Figure 1).

[0041] Specifically, the first valve V1 connects the end of the first flow path P01 to the beginning of the second flow path P02 and closes the beginning of the third flow path P03. The second valve V2 connects the end of the second flow path P02 to the beginning of the fourth flow path P04 and closes the end of the third flow path P03. The fifth valve V5 connects the end of the second deactivation flow path P12 to the beginning of the third deactivation flow path P13 and closes the end of the first deactivation flow path P11. The seventh valve V7 blocks the first atmospheric intake passage P21. The control of the eighth valve V8 will be described later.

[0042] On the other hand, when the first H2O recovery unit 3A is in a detached state and the second H2O recovery unit 3B is in an adsorption state (hereafter referred to as the second cycle), the control unit 7 controls the valve as follows. Specifically, the first valve V1 connects the end of the first flow path P01 to the beginning of the third flow path P03 and closes the beginning of the second flow path P02. The second valve V2 connects the end of the third flow path P03 to the beginning of the fourth flow path P04 and closes the end of the second flow path P02. The fifth valve V5 connects the end of the first deactivation flow path P11 to the beginning of the third deactivation flow path P13 and closes the end of the second deactivation flow path P12. The control of the seventh valve V7 will be described later. The eighth valve V8 shuts off the second atmospheric intake passage P22.

[0043] Therefore, in the first cycle, the exhaust gas flowing into the first flow path P01 passes through the first valve V1 and the second flow path P02 and flows into the first H2O recovery unit 2A, where H2O is in an adsorbed state. After H2O is recovered in the first H2O recovery unit 2A, the exhaust gas flows out of the first H2O recovery unit 2A and flows into the fourth flow path P04 through the second flow path P02 and the second valve V2.

[0044] After the start of the first cycle, when the control unit 7 operates the H2O desorption pump 4, the H2O adsorbed by the H2O adsorbent in the second H2O recovery unit 2B is desorbed. Specifically, the H2O desorption pump 4 reduces the pressure in the space where the H2O adsorbent in the second H2O recovery unit 2B is disposed via the second and third desorption channels P12 and P13, and performs evacuation to desorb H2O from the H2O adsorbent. Then, the H2O desorption pump 4 discharges the desorbed H2O to the outside of the vehicle via the third desorption channel P13.

[0045] On the other hand, in the second cycle, the exhaust gas that has flowed into the first channel P01 passes through the first valve V1 and the third channel P03 and flows into the second H2O recovery unit 2B in the adsorption state. Then, after the H2O is recovered in the second H2O recovery unit 2B, the exhaust gas flows out from the second H2O recovery unit 2B, passes through the third channel P03 and the second valve V2, and flows into the fourth channel P04.

[0046] After the start of the second cycle, when the control unit 7 operates the H2O desorption pump 4, the H2O adsorbed by the H2O adsorbent in the first H2O recovery unit 2A is desorbed. Specifically, the H2O desorption pump 4 reduces the pressure in the space where the H2O adsorbent in the first H2O recovery unit 2A is disposed via the first and third desorption channels P11 and P13, and performs evacuation to desorb H2O from the H2O adsorbent. Then, the H2O desorption pump 4 discharges the desorbed H2O to the outside of the vehicle via the third desorption channel P13.

[0047] <Cycle of CO2 recovery unit> When the first CO2 recovery unit 3A is in the adsorption state and the second CO2 recovery unit 3B is in the desorption state (hereinafter, the first cycle), the control unit 7 controls the valves as follows (see FIG. 1).

[0048] Specifically, the third valve V3 connects the end of the fourth flow path P04 to the beginning of the fifth flow path P05 and closes the beginning of the sixth flow path P06. The fourth valve V4 connects the end of the fifth flow path P05 to the beginning of the seventh flow path P07 and closes the end of the sixth flow path P06. The sixth valve V6 connects the end of the fifth deactivation flow path P15 to the beginning of the sixth deactivation flow path P16 and closes the end of the fourth deactivation flow path P14.

[0049] On the other hand, when the first CO2 recovery unit 3A is in a desorption state and the second CO2 recovery unit 3B is in an adsorption state (hereafter referred to as the second cycle), the control unit 7 controls the valve as follows. Specifically, the third valve V3 connects the end of the fourth flow path P04 to the beginning of the sixth flow path P06 and closes the beginning of the fifth flow path P05. Also, the fourth valve V4 connects the end of the sixth flow path P06 to the beginning of the seventh flow path P07 and closes the end of the fifth flow path P05. Furthermore, the sixth valve V6 connects the end of the fourth deactivation flow path P14 to the beginning of the sixth deactivation flow path P16 and closes the end of the fifth deactivation flow path P15.

[0050] Therefore, in the first cycle, the exhaust gas that flows into the fourth passage P04 passes through the third valve V3 and the fifth passage P05 and flows into the first CO2 recovery unit 3A, which is in an adsorbed state. After CO2 is recovered in the first CO2 recovery unit 3A, the exhaust gas flows out of the first CO2 recovery unit 3A, passes through the fifth passage P05, the fourth valve V4 and the seventh passage P07, and is discharged outside the vehicle.

[0051] Furthermore, after the start of the first cycle, when the control unit 7 activates the CO2 desorption pump 6, the CO2 adsorbed on the CO2 adsorbent in the second CO2 recovery unit 3B is desorbed. Specifically, the CO2 desorption pump 6 depressurizes the space where the CO2 adsorbent is located in the second CO2 recovery unit 3B via the fifth and sixth desorption channels P15 and P16, thereby creating a vacuum and desorbing CO2 from the CO2 adsorbent. The CO2 desorption pump 6 then flows the desorbed CO2 into the CO2 storage unit 5 via the sixth desorption channel P16.

[0052] Meanwhile, in the second cycle, the exhaust gas that flows into the fourth passage P04 passes through the third valve V3 and the sixth passage P06 and flows into the second CO2 recovery unit 3B, which is in an adsorbed state. After CO2 is recovered in the second CO2 recovery unit 3B, the exhaust gas flows out of the second CO2 recovery unit 3B, passes through the sixth passage P06, the fourth valve V4, and the seventh passage P07, and is discharged outside the vehicle.

[0053] Furthermore, after the start of the second cycle, when the control unit 7 activates the CO2 desorption pump 6, the CO2 adsorbed on the CO2 adsorbent in the first CO2 recovery unit 3A is desorbed. Specifically, the CO2 desorption pump 6 depressurizes the space where the CO2 adsorbent is located in the first CO2 recovery unit 3A via the fourth and sixth desorption channels P14 and P16, thereby creating a vacuum and desorbing CO2 from the CO2 adsorbent. The CO2 desorption pump 6 then flows the desorbed CO2 into the CO2 storage unit 5 via the sixth desorption channel P16.

[0054] [(9) H2O recovery section in the desorbed state] The desorption of H2O in the H2O recovery unit, which is in a desorption state, during the first and second cycles of the H2O recovery unit will be described (see Figure 1). The control unit 7 controls the valve and the H2O desorption pump 4 to desorb H2O from the H2O recovery unit, which is in a desorption state, during each cycle.

[0055] Specifically, first, the control unit 7 closes the atmospheric intake valve, thereby blocking the atmospheric intake passage. The atmospheric intake valve is the valve located in the atmospheric intake passage corresponding to the H2O recovery section, which is in the desorbed state, among the 7th and 8th valves V7 and V8. In other words, the atmospheric intake valve is the 8th valve V8 in the first cycle and the 7th valve V7 in the second cycle.

[0056] Next, the control unit 7 activates the H2O desorption pump 4. The H2O desorption pump 4 reduces the pressure in the space where the H2O adsorbent is located in the H2O recovery section, creating a vacuum. This desorbs H2O from the H2O adsorbent, and the desorbed H2O is discharged outside the vehicle. The control unit 7 also starts the operation of the H2O desorption pump 4 and performs the atmospheric air introduction process described later.

[0057] Then, after the H2O desorption in the H2O recovery unit, which is in a desorption state, is completed, the control unit 7 switches the cycle and recovers H2O from the exhaust gas using the H2O recovery unit from which desorption has been performed. The control unit 7 also similarly desorbs H2O from the H2O recovery unit, which has now entered a desorption state.

[0058] <Atmospheric Intake Treatment> The atmospheric air introduction process performed by the control unit 7 will be explained using the flowchart in Figure 2. In S100, the control unit 7 determines whether the pressure in the space where the H2O adsorbent is placed in the H2O recovery unit (hereinafter also referred to simply as the pressure in the H2O recovery unit) is below a predetermined opening threshold.

[0059] Here, the release threshold may be the following value. That is, immediately after the start of operation of the H2O desorption pump 4 in each cycle, as the pressure in the H2O recovery section decreases, the amount of H2O desorbed per unit time (desorption rate) increases. However, as the pressure in the H2O recovery section decreases further and becomes almost a vacuum, the gas flow in the H2O recovery section is suppressed, and the H2O desorbed from the H2O adsorbent accumulates near the H2O adsorbent. As a result, the desorption of H2O is suppressed, and the desorption rate decreases. The release threshold may be, for example, the pressure in the H2O recovery section when the desorption rate begins to decrease in each cycle.

[0060] Specifically, for example, the time (depressurization time) from the start of operation of the H2O desorption pump 4 until it is estimated that the pressure in the H2O recovery unit has reached below the release threshold may be predetermined. The control unit 7 may then determine that the pressure in the H2O recovery unit has reached below the release threshold when the depressurization time has elapsed from the start of the atmospheric air introduction process in each cycle. Alternatively, for example, the control unit 7 may detect the pressure in the H2O recovery unit using a sensor and determine whether or not the pressure is below the release threshold.

[0061] If the control unit 7 determines that the pressure in the H2O recovery section is higher than the opening threshold (S100: No), it repeats the determination in S100. During this time, the pressure in the H2O recovery section gradually decreases due to the H2O desorption pump 4. On the other hand, if the control unit 7 determines that the pressure in the H2O recovery section is below the opening threshold (S100: Yes), it proceeds to S110.

[0062] In S110, the control unit 7 keeps the H2O desorption pump 4 running, opens the atmospheric intake valve to open the atmospheric intake passage, and introduces atmospheric air from outside the vehicle into the H2O recovery unit. At this time, the opening degree of the atmospheric intake valve is controlled to maintain a state in which the pressure in the H2O recovery unit is reduced.

[0063] Specifically, for example, the opening degree of the atmospheric intake valve may be predetermined so as to maintain a reduced pressure in the H2O recovery section. The control unit 7 may then control the atmospheric intake valve to open by that predetermined amount. Alternatively, for example, the control unit 7 may detect the pressure in the H2O recovery section using a sensor and control the opening degree of the atmospheric intake valve to maintain that reduced pressure.

[0064] Furthermore, a state where the pressure in the H2O recovery section is reduced means that the pressure in the H2O recovery section has decreased to the extent that H2O is being released from the H2O adsorbent. For example, a state where the pressure in the H2O recovery section is reduced may also mean that the pressure in the H2O recovery section is close to the release threshold.

[0065] The control unit 7 then terminates the air intake process. [(10) Effects] (1a) According to the above embodiment, when the pressure in the H2O recovery section, which is in a desorbed state, is reduced to desorb the H2O adsorbed on the H2O adsorbent, air is introduced into the H2O recovery section, thereby promoting the flow of gas in the space where the H2O adsorbent is located in the H2O recovery section. Therefore, it is possible to suppress the accumulation of desorbed H2O near the H2O adsorbent, which reduces the desorption rate, and to promote the desorption of H2O.

[0066] Furthermore, the desorption of H2O is accelerated, allowing more H2O to be desorbed from the H2O recovery section (in other words, the amount of H2O desorbed per unit weight in the H2O adsorbent increases). Therefore, when recovering H2O from exhaust gas in the H2O recovery section after desorption, the amount of H2O adsorbed per unit weight in the H2O adsorbent can be increased. Thus, the amount of H2O adsorbent can be reduced while maintaining the amount of H2O recovered in the H2O recovery section. Consequently, the CO2 recovery device 1 can be made lighter.

[0067] Furthermore, by promoting the desorption of H2O, the amount of H2O desorbed per unit time in the H2O recovery section can be increased. Therefore, the time required to desorb H2O from the H2O adsorbent can be shortened. In other words, the operating time of the H2O desorption pump 4 can be shortened. Therefore, the energy consumed by the H2O desorption pump 4 can be reduced.

[0068] (1b) Furthermore, according to the above embodiment, in each cycle, the control unit 7 operates the H2O desorption pump 4 and then closes the atmospheric intake valve and blocks the atmospheric intake passage until the pressure in the H2O recovery section in the desorption state reaches below the release threshold. Therefore, when the H2O desorption pump 4 is operated, the pressure in the H2O recovery section can be reduced more quickly compared to when the atmospheric intake valve is open from the beginning. Therefore, the time required to desorb H2O from the H2O adsorbent can be shortened, and the energy consumed by the H2O desorption pump 4 can be reduced.

[0069] (1c) Furthermore, according to the above embodiment, by switching between the first and second cycles, H2O and CO2 can be desorbed from the recovery unit in the desorption state while H2O and CO2 can be recovered from the exhaust gas using the recovery unit in the adsorption state. Therefore, by operating the CO2 recovery device 1 while switching between the first and second cycles, H2O and CO2 can be continuously recovered from the exhaust gas. In other words, interruptions in the recovery of H2O and CO2 from the exhaust gas can be suppressed.

[0070] (1d) Furthermore, according to the above embodiment, the H2O desorption pump 4 is provided in a common discharge section where the first and second discharge channels merge into one. The H2O desorption pump 4 is used in both cases when desorbing H2O from the first and second H2O recovery sections 2A and 2B. Therefore, compared to the case where a pump for desorbing H2O is provided for each H2O recovery section, the number of pumps can be reduced, and thus the CO2 recovery device can be made smaller.

[0071] Furthermore, according to the above embodiment, the CO2 desorption pump 6 is installed in a common storage section where the first and second storage channels merge into one. The CO2 desorption pump 6 is used in both cases when desorbing CO2 from the first and second CO2 recovery sections 3A and 3B. Therefore, compared to the case where a pump for desorbing CO2 is provided for each CO2 recovery section, the number of pumps can be reduced, and thus the CO2 recovery device can be made smaller.

[0072] [(11) Correspondence between wordings] In the first embodiment, the H2O desorption pump 4 corresponds to an example of a pump, the first to third desorption channels P11 to P13 correspond to an example of a discharge channel, and the third desorption channel P13 corresponds to an example of a common discharge section. Also, S100 corresponds to an example of a determination unit.

[0073] [2. Second Embodiment] [(1) Overview] The CO2 recovery device 1 of the second embodiment differs from the first embodiment in the control of valves, etc., by the control unit 7 when H2O is removed from the H2O recovery unit, which is in a desorbed state. The differences between the CO2 recovery device 1 of the second embodiment and the first embodiment will be described below.

[0074] [(2) H2O recovery section in the desorbed state] The desorption of H2O in the H2O recovery unit, which is in a desorption state, during the first and second cycles of the H2O recovery unit will be described (see Figure 1). The control unit 7 controls the valve and the H2O desorption pump 4 to desorb H2O from the H2O recovery unit, which is in a desorption state, during each cycle.

[0075] Specifically, first, the control unit 7 opens the atmospheric intake valve to open the atmospheric intake passage. The opening degree of the atmospheric intake valve is controlled in the same manner as in the first embodiment, to an opening degree that can maintain a reduced pressure in the H2O recovery section.

[0076] Next, the control unit 7 activates the H2O desorption pump 4. The H2O desorption pump 4 reduces the pressure in the space where the H2O adsorbent is located in the H2O recovery section, creating a vacuum. This desorbs H2O from the H2O adsorbent, and the desorbed H2O is discharged outside the vehicle.

[0077] Furthermore, during this process, while the pressure in the H2O recovery section remains reduced, air flows into the H2O recovery section via the air intake passage. In other words, the air intake passage is configured to allow air to flow into the H2O recovery section from outside the vehicle while maintaining the reduced pressure in the H2O recovery section when the H2O desorption pump 4 reduces the pressure in the H2O recovery section.

[0078] Then, after the H2O desorption in the H2O recovery unit, which is in a desorption state, is completed, the control unit 7 switches the cycle and recovers H2O from the exhaust gas using the H2O recovery unit from which desorption has been performed. The control unit 7 also similarly desorbs H2O from the H2O recovery unit, which has now entered a desorption state.

[0079] [(3) Variant] In the second embodiment described above, the control unit 7 controls the opening degree of the atmospheric intake valve and adjusts the amount of air flowing into the H2O recovery section via the atmospheric intake passage, thereby maintaining a reduced pressure in the H2O recovery section. However, the reduction in pressure in the H2O recovery section may also be maintained by limiting the amount of air flowing into the H2O recovery section via the atmospheric intake passage, for example, by changing the shape of the atmospheric intake passage itself.

[0080] Specifically, the CO2 recovery device 1 does not necessarily have to be equipped with first and second valves V7 and V8. Also, the first and second air intake passages P21 and P22 may be configured to limit the amount of air flowing into the H2O recovery section from outside the vehicle so that the pressure in the H2O recovery section remains reduced when the H2O desorption pump 4 reduces the pressure in the H2O recovery section. For example, the first and second air intake passages P21 and P22 may be formed by pipes having a constricted section. A constricted section is a part of the pipe that is recessed radially inward. Since the flow path cross-sectional area of ​​the first and second air intake passages P21 and P22 is reduced at the constricted section, the amount of air flowing through the first and second air intake passages P21 and P22 is limited. However, the first and second air intake passages P21 and P22 may be formed, for example, by pipes of a small diameter, or by through holes of a small diameter that connect the space for the H2O adsorbent in the H2O recovery section with the outside of the vehicle.

[0081] [(4) Effects] According to the second embodiment described in detail above, the same effects as those of the first embodiment (1a), (1c), and (1d) can be obtained.

[0082] [3. Other Embodiments] While embodiments of this disclosure have been described above, it goes without saying that this disclosure is not limited to the embodiments described above and can take various forms.

[0083] (1) In the first and second embodiments, the CO2 recovery device 1 comprises first and second H2O recovery units 2A, 2B and first and second CO2 recovery units 3A, 3B. However, it is not limited to this, and the number of H2O recovery units in the CO2 recovery device 1 may be one or three or more, and the number of CO2 recovery units in the CO2 recovery device 1 may be one or three or more.

[0084] (2) In the first and second embodiments, the CO2 recovery device 1 includes a CO2 storage unit 5 and a CO2 desorption pump 6, and these are used to desorb CO2 from the CO2 adsorbent in the CO2 recovery unit. However, the CO2 recovery device 1 is not limited to this and does not need to include a CO2 storage unit 5 and a CO2 desorption pump 6. In this case, for example, the vehicle on which the CO2 recovery device 1 is mounted may be connected to equipment for desorbing CO2 provided outside the vehicle, thereby desorbing CO2 from the CO2 adsorbent in the CO2 recovery unit. Alternatively, for example, the CO2 recovery unit on which CO2 has been adsorbed on the CO2 adsorbent may be removed from the CO2 recovery device 1, and CO2 may be desorbed from the CO2 adsorbent in the removed CO2 recovery unit using equipment for desorbing CO2 provided outside the vehicle.

[0085] (3) In the first and second embodiments, the first to sixth valves V1 to V6 are configured as three-way valves, for example, to switch the gas passage. However, the function of switching the gas passage in the first to sixth valves V1 to V6 may also be realized using a plurality of two-way valves.

[0086] For example, the first valve V1 is connected to the end of the first flow path P01 and to the beginnings of the second and third flow paths P02 and P03. In the first cycle, the first valve V1 connects the end of the first flow path P01 to the beginning of the second flow path P02 and closes the beginning of the third flow path P03. In the second cycle, the first valve V1 connects the end of the first flow path P01 to the beginning of the third flow path P03 and closes the beginning of the second flow path P02.

[0087] However, the CO2 recovery device 1 may, for example, include first and second two-way valves for opening and closing the gas passage instead of the first valve V1. The first and second two-way valves may be located in the second and third passages P02 and P03, respectively, closer to the starting end than the first and second H2O recovery sections 2A and 2B. In the first cycle, the first two-way valve may be open and the second two-way valve may be closed. In the second cycle, the first two-way valve may be closed and the second two-way valve may be open.

[0088] (4) Multiple functions of one component in the above embodiment may be realized by multiple components, or one function of one component may be realized by multiple components. Also, multiple functions of multiple components may be realized by one component, or one function realized by multiple components may be realized by one component. Furthermore, some of the configurations of the above embodiment may be omitted. Also, at least some of the configurations of the above embodiment may be added to or replaced with the configurations of other above embodiments. [Explanation of symbols]

[0089] 1...CO2 recovery device, 2A, 2B...1st and 2nd H2O recovery units, 3A, 3B...1st and 2nd CO2 recovery units, 4...Water desorption pump, 7...Control unit, P11~P13...1st to 3rd desorption channels, P21, P22...1st and 2nd atmospheric inlet channels.

Claims

1. A CO2 recovery device configured to recover CO2 from the exhaust gas of an internal combustion engine, An H2O recovery unit is configured to recover H2O from the exhaust gas by adsorbing H2O contained in the exhaust gas with an H2O adsorbent, A CO2 recovery unit is configured to recover CO2 contained in the exhaust gas from which H2O has been recovered in the H2O recovery unit, A discharge channel is provided corresponding to the H2O recovery section and is a channel that connects the H2O recovery section to the outside, An air intake passage is provided in correspondence with the H2O recovery section and is a flow path for introducing air into the H2O recovery section, A pump provided in the aforementioned discharge channel is configured to reduce the pressure in the H2O recovery section, thereby detaching the H2O adsorbed on the H2O adsorbent, and to discharge the H2O detached from the H2O adsorbent to the outside. A CO2 recovery device equipped with the following features.

2. A CO2 recovery device according to claim 1, A control unit that performs processing for opening and closing the air intake passage, A determination unit that determines whether the pressure in the H2O recovery unit is below a predetermined opening threshold, Furthermore, The control unit blocks the air intake passage corresponding to the H2O recovery unit from the time the pressure in the H2O recovery unit starts to decrease due to the pump until the determination unit determines that the pressure in the H2O recovery unit is below the opening threshold. When the determination unit determines that the pressure in the H2O recovery unit has reached below the opening threshold, it opens the air intake passage corresponding to the H2O recovery unit to allow air to flow into the H2O recovery unit while maintaining the reduced pressure in the H2O recovery unit. CO2 recovery device.

3. A CO2 recovery device according to claim 1, The air intake passage is configured such that, when the pump reduces the pressure in the H2O recovery section corresponding to the air intake passage, air is allowed to flow into the H2O recovery section while maintaining the reduced pressure in the H2O recovery section. CO2 recovery device.

4. A CO2 recovery device according to any one of claims 1 to 3, Multiple H2O recovery units, The system further comprises a plurality of discharge channels and a plurality of air intake channels, each of which is provided in accordance with the respective H2O recovery section. The multiple discharge channels include a common discharge section which is a section where the multiple discharge channels merge into one. The pump is provided in the common discharge section, CO2 recovery device.

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