JP2023105445A - Co2 separation and recovery system for internal combustion engine - Google Patents

Abstract

To provide a CO2 separation and recovery system for an internal combustion engine capable of controlling a CO2 adsorber to an appropriate temperature state and successfully and promptly adsorbing/desorbing CO2 by using the CO2 adsorber.SOLUTION: A CO2 separation and recovery system for an internal combustion engine includes: at least four CO2 separators each having a CO2 adsorber capable of adsorbing/desorbing CO2 in accordance with a temperature and a heat exchanger capable of exchanging heat with the CO2 adsorber; an exhaust passage device configured so that exhaust gas flows in the four CO2 separators sequentially to pass through one of the CO2 adsorber and the heat exchanger of each CO2 separator; and a control device switching a flowing order of exhaust gas through the four CO2 separators. In the CO2 separator on the most upstream side, CO2 is desorbed from the CO2 adsorber by causing exhaust gas to flow in the heat exchanger, and in the CO2 separator on the most downstream side, CO2 in the exhaust gas is adsorbed to the CO2 adsorber by causing the exhaust gas to flow in the CO2 adsorber.SELECTED DRAWING: Figure 5

Description

The present invention relates to a CO2 separation device for an internal combustion engine, which is provided in an exhaust system of the internal combustion engine and separates CO2 from exhaust gas.

In order to reduce adverse effects on the global environment, exhaust gas regulations for automobiles are becoming more advanced. In particular, CO2 (carbon dioxide) contained in exhaust gas from internal combustion engines is said to be one of the causes of global warming. It has been demanded.

2. Description of the Related Art Conventionally, as a CO2 separation device for separating CO2 from exhaust gas, for example, one described in Patent Document 1 is known. In this CO2 separation device, a CO2 capturing material that captures CO2 is installed in the exhaust passage of the internal combustion engine, captures CO2 in the exhaust gas of the internal combustion engine with the CO2 capturing material, and desorbs the captured CO2 from the CO2 capturing material. It is designed to let Zeolite or the like is used as the CO2 capturing material.

Specifically, the exhaust passage has two branch passages that allow the exhaust gas to flow only in one direction by means of a switching valve, and both branch passages are provided with CO2 capture materials. By letting the exhaust gas flow through one of the branch passages, the CO2 capture material in the branch passage captures CO2 in the exhaust gas (capture step), and the CO2 capture material in the other branch passage is heated using the heat of the exhaust gas. By doing so, the CO2 captured by the CO2 capture material is desorbed (desorption step). Then, in each CO2 capturing material, CO2 is separated from the exhaust gas by alternately repeating the capturing process and the desorbing process.

WO2016/076041

Some materials used as CO2 adsorbents, such as the above-mentioned zeolite, change their CO2 adsorption performance according to their temperature, and the lower the adsorbent temperature, the higher the CO2 adsorption performance, and the higher the adsorbent temperature. Some exhibit a temperature characteristic that decreases as the temperature increases. Therefore, in a CO2 separation and recovery system that switches CO2 adsorption/desorption by changing the temperature of the CO2 adsorbent and thereby separates and recovers CO2 in the exhaust gas, the CO2 adsorption performance of the CO2 adsorbent can be maximized. In order to utilize it, it is necessary to appropriately control the temperature state of the CO2 adsorbent so that it becomes a low temperature suitable for adsorption during CO2 adsorption and a high temperature suitable for desorption during CO2 desorption.

As in the CO2 separation device described in Patent Document 1, when the heat of the exhaust gas is used to change the temperature of the two CO2 adsorbents, thereby continuously performing CO2 adsorption and desorption, two CO2 adsorption Ideally, the temperature of the vessel should be controlled so as to instantaneously switch between a low temperature state (e.g., 50°C) suitable for CO2 adsorption and a high temperature state (e.g., 200°C) suitable for CO2 desorption. However, in practice, it takes a certain amount of time for the temperature of each CO2 adsorbent to reach the target temperature. This delay in temperature change of the CO2 adsorbent has been one of the factors that reduce the efficiency of CO2 adsorption/desorption.

To address these issues, a method has been proposed in which a heater or cooler is used to heat/cool the CO2 adsorber in a short period of time. A problem arises that the energy efficiency as a whole deteriorates.

The present invention has been made to solve such problems. By efficiently utilizing the heat of the exhaust gas, the CO2 adsorber is controlled to an appropriate temperature state, and the CO2 adsorption/ It is an object of the present invention to provide a CO2 separation and recovery system for an internal combustion engine capable of performing desorption well and quickly.

In order to achieve this object, the CO2 separation and capture system for an internal combustion engine according to claim 1 of the present invention removes CO2 from exhaust gas discharged from an internal combustion engine 3 (an engine in the embodiment (hereinafter the same in this section)). A CO2 separation and recovery system 1 for an internal combustion engine that separates and recovers CO2, which is configured to allow the flow of exhaust gas and has a CO2 adsorber (CO2 adsorber A, CO2 adsorber A, CO2 adsorber B, CO2 adsorber C, CO2 adsorber D), and heat exchangers (heat exchanger A, heat exchanger B , heat exchanger C, heat exchanger D), and a plurality of exhaust passages ( a first exhaust passage 11, a second exhaust passage 12, a third exhaust passage 13, a fourth exhaust passage 14, a fifth exhaust passage 15), and a plurality of open/close valves (open/close valves IN1, IN2) provided in the plurality of exhaust passages. , IN3, IN4, O1, O2, O3, O4, C1, C2, C3, C4, A1, A2, A3, A4, S1, S2, S3, S4, B1, E1, E2, E3, E4, R1, R2 , R3, R4), wherein exhaust gas is configured to flow exhaust gas through at least four CO2 separation units in sequence and through one of a CO2 adsorber and a heat exchanger of each CO2 separation unit; a control device (ECU 2) for switching the flow order of the exhaust gas to at least four CO2 separation devices by controlling a plurality of open/close valves, wherein the exhaust gas flows first among the at least four CO2 separation devices. CO2 is desorbed from the CO2 adsorber by causing the exhaust gas to flow through the heat exchanger in the most upstream CO2 separation unit, and the most downstream of the at least four CO2 separation units through which the exhaust gas flows last. The CO2 separation apparatus is characterized in that the CO2 in the exhaust gas is adsorbed by the CO2 adsorber by causing the exhaust gas to flow through the CO2 adsorber (Fig. 4).

In this internal combustion engine CO2 separation and recovery system, each of the at least four CO2 separation devices has a CO2 adsorber and a heat exchanger, and the exhaust gas passes through the at least four CO2 separation devices in turn and each CO2 by an exhaust passage device. It flows through one of the CO2 adsorber and heat exchanger of the separation unit. The control device controls a plurality of open/close valves provided on the plurality of exhaust passages, thereby switching the flow order of the exhaust gas to each CO2 separation device.

High-temperature exhaust gas emitted from the internal combustion engine exchanges heat with the CO2 adsorber when passing through the heat exchanger of the CO2 separation device on the most upstream side. From the heated CO2 adsorber, the CO2 that has been adsorbed up to that point is efficiently desorbed. On the other hand, the exhaust gas, which has lost heat when passing through the most upstream CO2 separation device, loses further heat in the process of passing through the other CO2 separation devices in order, and finally passes through the CO2 separation device on the most downstream side. When passing through the adsorber, CO2 in the exhaust gas is efficiently adsorbed by the CO2 adsorber. In this way, without using a heater or a cooler, the heat of the exhaust gas is efficiently used to control the temperature of the CO2 adsorber to an appropriate temperature state, and the adsorption/desorption of CO2 by the CO2 adsorbent can be performed satisfactorily and quickly. can be done.

The invention according to claim 2 of the present invention is the CO2 separation and recovery system for an internal combustion engine according to claim 1, wherein the plurality of exhaust passages are connected between the internal combustion engine and at least four CO2 separation devices, and the internal combustion engine a first exhaust passage for introducing the exhaust gas discharged from the CO2 separation unit to the heat exchanger of the most upstream CO2 separation unit; A third exhaust passage connected to the CO2 adsorber of the device and for discharging exhaust gas that has passed through the CO2 adsorber of the most downstream CO2 separation device into the atmosphere, and connected to the CO2 adsorbers of at least four CO2 separation devices and a fourth exhaust passage for recovering CO2 desorbed from the CO2 adsorber of the CO2 separation device on the most upstream side.

According to this configuration, the exhaust gas discharged from the internal combustion engine can be introduced into the heat exchanger of the CO2 separation device on the most upstream side by the first exhaust passage, and the CO2 separation on the most upstream side by the second exhaust passage. The exhaust gas that has passed through the device can in turn be passed through another CO2 separation device. In addition, the third exhaust passage allows the exhaust gas, in which CO2 is adsorbed when flowing through the CO2 separation device on the most downstream side, to be discharged into the atmosphere, and the fourth exhaust passage allows the CO2 separation device on the most upstream side to be discharged into the atmosphere. CO2 desorbed from the CO2 adsorber can be efficiently recovered. With such an exhaust passage configuration, it is possible to efficiently utilize the heat of the exhaust gas, thereby controlling the temperature of the CO2 adsorber to an appropriate temperature state, so that the CO2 adsorption/desorption by the CO2 adsorbent can be performed satisfactorily and quickly. can be done.

The invention according to claim 3 of the present invention is the CO2 separation and recovery system for an internal combustion engine according to claim 2, wherein the at least four CO2 separation devices are arranged in the order from upstream to downstream where the exhaust gas flows, first, second, The third and fourth CO2 separation devices are arranged in this order. In the first CO2 separation device, the exhaust gas discharged from the internal combustion engine flows into the heat exchanger of the first CO2 separation device, and the CO2 adsorber of the first CO2 separation device A desorption process for desorbing CO2 is performed, and in the second CO2 separation device, the exhaust gas that has passed through the first CO2 separation device flows into the heat exchanger of the second CO2 separation device, thereby heating the CO2 adsorber of the second CO2 separation device. In the third CO2 separation device, the exhaust gas that has passed through the second CO2 separation device flows into the heat exchanger of the third CO2 separation device, thereby cooling the CO2 adsorber of the third CO2 separation device. Then, in the fourth CO2 separation device, the exhaust gas that has passed through the third CO2 separation device flows into the CO2 adsorber of the fourth CO2 separation device, whereby the CO2 in the exhaust gas is adsorbed by the CO2 adsorption device of the fourth CO2 separation device. (Fig. 4).

According to this configuration, in the first CO2 separation device through which high-temperature exhaust gas discharged from the internal combustion engine flows, desorption processing is performed to desorb CO2 from the CO2 adsorber, and then in the second CO2 separation device, further A heat treatment is performed to heat the CO2 adsorber by taking heat from the exhaust gas. After that, the exhaust gas that has lost heat by passing through the first and second CO2 separation devices is passed through the heat exchanger of the third CO2 separation device to cool the CO2 adsorber, Furthermore, the exhaust gas from which the heat has been taken is allowed to flow through the CO2 adsorber of the fourth CO2 separation device, thereby performing an adsorption process in which CO2 in the exhaust gas is adsorbed by the CO2 adsorber.

As described above, in the process of sequentially passing the exhaust gas through the first to fourth CO2 separation devices, the heat of the exhaust gas is efficiently used to perform the desorption treatment, heating treatment, cooling treatment, and adsorption treatment, respectively. By doing so, each CO2 adsorber can be controlled to an appropriate temperature state, and adsorption/desorption of CO2 by the CO2 adsorbent can be performed satisfactorily and quickly.

The invention according to claim 4 of the present invention is the CO2 separation and recovery system for an internal combustion engine according to claim 3, wherein the plurality of exhaust passages are connected to the first, second, third and fourth CO2 separation devices. 5 exhaust passage, and is further provided with a radiator 6 arranged in the fifth exhaust passage for cooling the exhaust gas that has passed through the heat exchanger of the second CO2 separation device.

According to this configuration, the exhaust gas that has passed through the heat exchanger of the second CO2 separation device is further cooled by the radiator arranged in the fifth exhaust passage connected to each of the first to fourth CO2 separation devices. Since the cooled exhaust gas flows through the third CO2 separation device and the fourth CO2 separation device arranged downstream of the radiator, the cooling treatment and the adsorption treatment can be performed more efficiently. can. Therefore, the CO2 adsorber can be controlled to a more appropriate temperature state, and the adsorption/desorption of CO2 by the CO2 adsorbent can be performed more favorably and quickly.

The invention according to claim 5 of the present invention is the CO2 separation and recovery system for an internal combustion engine according to claim 3 or 4, wherein each of the at least four CO2 separation devices is controlled by the control of the plurality of opening and closing valves by the control device. 1, 2nd, 3rd and 4th CO2 separators are set, and desorption treatment, cooling treatment, adsorption treatment and heating treatment are repeated in order (Fig. 4).

According to this configuration, each of the at least four CO2 separation devices is switched to the first, second, third, and fourth CO2 separation devices by sequentially switching the flow order of the exhaust gas by controlling the plurality of open/close valves. Either one is set, and each CO2 separation device repeats desorption processing, cooling processing, adsorption processing, and heating processing in order. That is, the high-temperature CO2 separation device that has performed the desorption process by receiving the heat of the exhaust gas as the first CO2 separation device is next set as the third CO2 separation device, and performs the cooling process in preparation for the subsequent adsorption process. cooled by The cooled CO2 separator is then set to the fourth CO2 separator to perform the adsorption process. Furthermore, the CO2 separation device after execution of the adsorption treatment is set to the second CO2 separation device, heated by performing heat treatment in preparation for the second desorption treatment, and then set to the first CO2 separation device again, Desorption processing is performed again.

Each CO2 separation device repeats the desorption process, cooling process, adsorption process, and heating process in order, so that when the adsorption process is performed, the CO2 adsorber is cooled because the cooling process is performed in advance. Therefore, CO2 can be efficiently adsorbed from the start of the adsorption treatment. In addition, when the desorption process is performed, the CO2 adsorber is heated by the heat treatment performed in advance, so CO2 can be efficiently desorbed from the start of the desorption process. can. In this way, the heat of the exhaust gas can be efficiently used, so that the CO2 adsorber can be controlled to a more appropriate temperature state, and the adsorption/desorption of CO2 by the CO2 adsorbent can be performed better and more quickly. can be done.

1 is a block diagram for explaining the basic concept of the CO2 separation and recovery system of the present invention; FIG. FIG. 3 is a diagram showing temperature characteristics of CO2 adsorption performance of a CO2 adsorbent. FIG. 4 is an explanatory diagram for explaining switching of operation modes in the CO2 separation and recovery system of the present invention; It is a figure which shows the flow of exhaust gas in each operation mode. 1 is a diagram schematically showing a CO2 separation and capture system according to one embodiment of the present invention together with an internal combustion engine; FIG. FIG. 3 is a block diagram showing a controller of the CO2 separation and recovery system; 4 is a flowchart showing operation mode switching control processing; It is a map for setting opening and closing of the valve in each operation mode. FIG. 4 is a diagram showing the operation of the CO2 separation and recovery system in mode 1; FIG. 4 is a diagram showing the operation of the CO2 separation and recovery system in mode 2; FIG. 4 is a diagram showing the operation of the CO2 separation and recovery system in mode 3; FIG. 4 is a diagram showing the operation of the CO2 separation and recovery system in mode 4; 1 is a diagram showing a conventional example of a CO2 separation and recovery system using two CO2 separation devices; FIG.

Preferred embodiments of the present invention will now be described in detail with reference to the drawings. First, the basic concept and operation of the CO2 separation and recovery system of the present invention will be described.

FIG. 13 schematically shows a conventional example of a CO2 separation and recovery system using two CO2 separation devices. This conventional CO2 separation and recovery system 91 includes two CO2 separation devices 95A and 95B provided in an exhaust passage 94. The CO2 separation devices 95A and 95B are heat exchangers arranged adjacent to each other. A and CO2 adsorber A, and heat exchanger B and CO2 adsorber B respectively. The CO2 adsorber adsorbs and desorbs CO2 in the exhaust gas, and contains a CO2 adsorbent (not shown) for that purpose. The CO2 adsorbents are provided so as to be exposed to exhaust gas flowing through each CO2 adsorber.

The CO2 adsorbent is made of, for example, zeolite, and has CO2 adsorption performance depending on temperature as shown in FIG. Specifically, as shown in FIG. 2, the amount of CO2 that can be adsorbed by the CO2 adsorbent changes according to the temperature of the CO2 adsorbent. decreases as it rises. In this conventional CO2 separation and recovery system 91, the temperature characteristics of the CO2 adsorbent are used to lower the temperature of the CO2 adsorber to a low temperature (for example, 50°C) suitable for CO2 adsorption, thereby In addition to adsorbing CO2, the temperature of the CO2 adsorber is raised to a high temperature (for example, 200°C) suitable for desorption of CO2, thereby desorbing the adsorbed CO2, thereby performing adsorption and desorption of CO2. Execute.

In this conventional CO2 separation and recovery system 91, the exhaust gas emitted from the internal combustion engine 93 passes through branch passages 94a and 94b selectively opened by an upstream switching valve 96 provided upstream of the CO2 separation devices 95A and 95B. (branch passage 94a in FIG. 13) and either heat exchanger A or B (heat exchanger A in FIG. 13). The flue gas, which has been cooled and cooled by heat exchange with the heat exchanger, then passes through either CO2 adsorber A or B (CO2 adsorber B in FIG. 13), where CO2 is adsorbed, and then desorbed. Emitted to the atmosphere as CO2 exhaust gas (including N2, water, etc.). On the other hand, the heat absorbed by the heat exchanger from the high-temperature exhaust gas is transferred to the CO2 adsorber adjacent to the heat exchanger to which the exhaust gas is not introduced (CO2 adsorber A in FIG. 13). The previously adsorbed CO2 is thereby desorbed from the warmed CO2 adsorber. The desorbed CO2 flows through one of the branch passages 94c and 94d (the branch passage 94c in FIG. 13) selectively opened by the downstream side switching valve 97, flows toward the confluence passage 94e, and is sucked out with negative pressure. It is desorbed and stored in a storage tank 99 in a compressed state by the effective compressor 98 .

In the conventional CO2 separation and recovery system 91, as described above, when the CO2 adsorber to which the flue gas is introduced adsorbs CO2, the CO2 adsorber to which the flue gas is not introduced has already adsorbed CO2. It operates to desorb CO2. Furthermore, under predetermined conditions, the upstream side switching valve 96 is controlled to switch the branch passages 94a and 94b for introducing the exhaust gas, and the downstream side switching valve 97 is used to switch the branch passages 94c and 94d open to the confluence passage 94e side. By performing switching control, the heat exchanger and CO2 adsorber through which exhaust gas passes are switched, and the CO2 adsorber opened to the compressor 98 and storage tank 99 side is switched. As a result, the CO2 adsorber that has been adsorbing CO2 starts to desorb the adsorbed CO2, and the CO2 adsorber that has been desorbing CO2 adsorbs CO2 from the newly introduced exhaust gas. to start.

Switching of the exhaust passage by the upstream switching valve 96 and the downstream switching valve 97 is performed by, for example, using a CO2 concentration sensor (not shown) provided downstream of the CO2 adsorber to detect the CO2 concentration in the exhaust gas that has passed through the CO2 adsorber. is detected to have exceeded a predetermined value, and it is determined that the CO2 adsorber that is adsorbing CO2 has reached a saturated state.

As in the conventional CO2 separation and recovery system 91, one of the two CO2 separation devices desorbs CO2 while the other adsorbs CO2. In a desorption system, it takes time to change the temperature of the CO2 adsorber, which is a factor that deteriorates the efficiency of CO2 adsorption/desorption.

That is, when it is determined that the CO2 adsorber that has been performing CO2 adsorption processing has reached a saturated state, the exhaust gas passage is changed to change the flow path of the exhaust gas, and CO2 adsorption has been performed until then. Even if the heating of the CO2 adsorber is started, it takes a certain amount of time for the CO2 adsorber to reach a temperature suitable for desorption of CO2, so the efficiency of CO2 desorption during that time is degraded. Become. Similarly, even if the cooling of the CO2 adsorber that has been desorbing CO2 is started, it takes a certain amount of time for the temperature of the CO2 adsorber to drop to a temperature suitable for CO2 adsorption. The efficiency of CO2 adsorption will deteriorate.

In order to shorten the time required for the temperature change of the CO2 adsorber, it is possible to use a heater or cooler to accelerate the temperature rise or cooling of the CO2 adsorber. increases, resulting in a worsening of the energy efficiency of the overall system.

In view of the problems of the conventional example, the CO2 separation and recovery system according to the present invention uses at least four CO2 separation devices, and configures an exhaust passage so that the exhaust gas flows through the at least four CO2 separation devices in order. FIG. 1 shows the basic concept of a CO2 separation and recovery system according to the present invention. The CO2 separation and recovery system illustrated in FIG. 1 uses four CO2 separation units A, B, C, D each having a heat exchanger and a CO2 adsorber arranged adjacent to each other.

The high-temperature exhaust gas emitted from the internal combustion engine loses heat when flowing through the heat exchanger A of the CO2 separation device A located most upstream. From the CO2 adsorber A, which is heated to a predetermined high temperature range suitable for desorption of CO2 by the heat taken from the exhaust gas, the CO2 that had been adsorbed up to that point is desorbed, and the desorbed CO2 is desorbed by the compressor. It is stored in a storage tank in a compressed state.

On the other hand, the exhaust gas that has passed through the heat exchanger A loses more heat when it continues to flow through the heat exchanger B of the CO2 separator B. The heat taken from the exhaust gas by the heat exchanger B is transferred to the adjacent CO2 adsorber B, whereby the CO2 adsorber B is heated.

Exhaust gas whose temperature has been lowered by losing heat by passing through heat exchangers A and B continues heat exchange with the adjacent CO2 adsorber C when flowing through the heat exchanger C of the CO2 separator C. to cool the CO2 adsorber C.

The low-temperature exhaust gas that has passed through the heat exchanger C continues to flow through the CO2 adsorber D of the CO2 separation device D at the most downstream side to cool the CO2 adsorber D. The CO2 adsorber D cooled to a predetermined low temperature range suitable for CO2 adsorption adsorbs CO2 in the exhaust gas. The flue gas from which CO2 has been removed or reduced (de-CO2 flue gas) is then released to the atmosphere.

As described above, in the CO2 separation and recovery system according to the present invention, the most upstream CO2 separation device performs desorption processing for desorbing CO2, and the second CO2 separation device performs heat processing for heating the CO2 adsorber. The third CO2 separation device performs cooling processing for cooling the CO2 adsorber, and the most downstream CO2 separation device performs adsorption processing for adsorbing CO2.

A CO2 concentration sensor is arranged in the exhaust passage on the downstream side of the most downstream CO2 separation device to detect the CO2 concentration in the de-CO2 exhaust gas. When the CO2 concentration in the de-CO2 exhaust gas exceeds a predetermined value, it is determined that the CO2 adsorption amount of the most downstream CO2 adsorber has reached the upper limit of the adsorption allowable amount, and the opening/closing valve (not shown) provided in the exhaust passage ), the flow order of the exhaust gas to the four CO2 separation devices is changed, and the processes performed by the respective CO2 separation devices are switched.

FIG. 3 shows the sequence of desorption, heating, cooling, and adsorption processes performed by each of the CO2 separators A, B, C, and D. FIG. In mode 1 (first processing cycle), CO2 separation device A performs desorption processing, CO2 separation device B performs heating processing, CO2 separation device C performs cooling processing, and CO2 separation device D performs Execute adsorption processing. In mode 2 (second processing cycle), CO2 separation device A performs cooling processing, CO2 separation device B performs desorption processing, CO2 separation device C performs adsorption processing, and CO2 separation device D performs Carry out heat treatment. In mode 3 (third processing cycle), CO2 separation device A performs adsorption processing, CO2 separation device B performs cooling processing, CO2 separation device C performs heating processing, and CO2 separation device D performs desorption. Execute remote processing. In mode 4 (fourth processing cycle), CO2 separation device A performs heat treatment, CO2 separation device B performs adsorption processing, CO2 separation device C performs desorption processing, and CO2 separation device D performs Carry out the cooling process.

By repeatedly executing such operation modes 1 to 4, each CO2 separation device repeatedly executes the desorption process, the cooling process, the adsorption process, and the heating process in this order. That is, the CO2 adsorber that has desorbed the previously adsorbed CO2 by executing the desorption process is cooled by executing the cooling process as a pre-stage of the second CO2 adsorption, and the CO2 adsorption can be performed efficiently. be prepared as The CO2 adsorber cooled by the cooling process then performs the adsorption process. The CO2 adsorber that has adsorbed CO2 through the execution of the adsorption process is heated by performing heat treatment as a pre-stage of the second CO2 desorption, and is prepared so that the next desorption process can be efficiently performed.

In each of the CO2 separation devices A, B, C, and D, the cooling process is always performed before the adsorption process, so that each CO2 adsorber is already at a predetermined low temperature suitable for CO2 adsorption when the adsorption process is started. , or is cooled to a temperature close to this, CO2 can be adsorbed satisfactorily immediately after the start of the adsorption treatment. In addition, since the heat treatment is always performed before the desorption process, each CO2 adsorber is already heated to a predetermined high temperature suitable for CO2 desorption or a temperature close thereto when the desorption process is started. Therefore, it is possible to desorb CO2 satisfactorily immediately after the desorption treatment is started. Therefore, in the CO2 separation and recovery system according to the present invention, it is possible to prevent the energy efficiency of CO2 adsorption/desorption from deteriorating due to the delay in the temperature change of the CO2 adsorber.

In addition, by repeatedly executing four operation modes in which the four CO2 separation devices perform different processes while switching between them, the system as a whole can continuously perform the adsorption and desorption of CO2 without a break. Good and fast CO2 adsorption/desorption can be achieved.

Next, referring to FIG. 4, the flow of the exhaust gas in the operation modes 1 to 4 described above will be described. In addition, in the figure, exhaust gas that has passed through a CO2 separation device that performs heat treatment is introduced into a CO2 separation device that performs cooling processing after flowing through a radiator. As a result, the cooling treatment and subsequent adsorption treatment can be performed more efficiently.

First, in mode 1, the exhaust gas emitted from the internal combustion engine first flows through the heat exchanger A of the CO2 separation device A to be desorbed, and then flows through the heat exchanger B of the CO2 separation device B. Heating treatment is performed, then after passing through a radiator, it flows through the heat exchanger C of the CO2 separation device C for cooling treatment, and finally flows through the CO2 adsorber D of the CO2 separation device D for adsorption treatment. is executed.

Next, in mode 2, the exhaust gas emitted from the internal combustion engine first flows through the CO2 separation device B that has been heat-treated in the previous mode (mode 1) to be desorbed, and then in the previous mode. Heat treatment is performed by passing through the CO2 separation device D that performed the adsorption process, and then, after passing through the radiator, it is passed through the CO2 separation device A that performed the desorption process in the previous mode, and the cooling process is performed. Finally, it flows through the CO2 separator C that has performed the cooling treatment in the previous mode, and the adsorption treatment is performed.

Subsequently, in mode 3, the exhaust gas emitted from the internal combustion engine first flows through the CO2 separation device D in which the heat treatment was performed in the previous mode (mode 2), and desorption treatment is performed. Heat treatment is performed by passing through the CO2 separation device C that performed the adsorption process, and then after passing through the radiator, it is passed through the CO2 separation device B that performed the desorption process in the previous mode, and the cooling process is performed. Finally, it flows through the CO2 separator A, which performed the cooling treatment in the previous mode, and the adsorption treatment is performed.

Finally, in mode 4, the exhaust gas leaving the internal combustion engine first flows through the CO2 separation device C that has been heat-treated in the previous mode (mode 3) to be desorbed, and then in the previous mode. Heat treatment is performed by passing through the CO2 separation device A that performed the adsorption process, and then after passing through the radiator, it is passed through the CO2 separation device D that performed the desorption process in the previous mode, and the cooling process is performed. Finally, it flows through the CO2 separator B, which performed the cooling treatment in the previous mode, and the adsorption treatment is performed.

As described above, in the CO2 separation and recovery system according to the present embodiment, by switching the flow order of the exhaust gas to the four CO2 separation devices A to D for each mode, the processing performed by each CO2 separation device can be switched. . A preferred embodiment of the present invention that realizes the above-described switching of the flow order of the exhaust gas will be described below.

FIG. 5 is a diagram schematically showing the CO2 separation and recovery system 1 according to one embodiment of the present invention together with the internal combustion engine 3. As shown in FIG. The internal combustion engine 3 (hereinafter referred to as "engine") is mounted on a vehicle (not shown), for example, as a power source, and is, for example, a gasoline engine having four cylinders (not shown). An intake passage (not shown) and an exhaust passage 4 are connected to each cylinder of the engine 3 via a manifold (not shown). In the engine 3, in each cylinder, a mixture of fuel injected from a fuel injection valve (not shown) and air taken in from an intake passage is ignited by a spark plug (not shown) and combusted. High-temperature combustion gas generated thereby is discharged to the exhaust passage 4 as exhaust gas.

As shown in FIG. 5, the CO2 separation and recovery system 1 separates and recovers CO2 (carbon dioxide) from the exhaust gas flowing through the exhaust passage 4, and includes four CO2 separation devices A, B, C, and D. , a compressor 8 and a storage tank 9 .

Each of the four CO2 separation units A, B, C, D has a heat exchanger and a CO2 adsorber adjacent in contact with each other. Note that "adjacent" is not limited to direct contact, and may be a structure in which, for example, a substance with high thermal conductivity is interposed therebetween. In the following description, when distinguishing the heat exchanger and CO2 adsorber of each CO2 separation device, the heat exchanger and CO2 adsorber of CO2 separation device A will be referred to as heat exchanger A and CO2 adsorber A, respectively. , those of CO2 separation device B are referred to as heat exchanger B and CO2 adsorber B, respectively, those of CO2 separation device C are referred to as heat exchanger C and CO2 adsorber C, and those of CO2 separation device D are referred to as , as heat exchanger D and CO2 adsorber D, respectively.

Each heat exchanger is configured so that exhaust gas can flow through its interior, and heat exchange with high-temperature exhaust gas heats the adjacent CO2 adsorber. It is configured to perform the cooling function of cooling the CO2 adsorber. Any known structure can be adopted as the heat exchanger as long as it can exchange heat between the exhaust gas and the adjacent CO2 adsorber.

Each CO2 adsorber is configured so that exhaust gas can flow through it, and incorporates a CO2 adsorbent (not shown) for adsorbing and desorbing CO2 in the exhaust gas. The CO2 adsorbents are provided so as to be exposed to exhaust gas flowing through each CO2 adsorber. The CO2 adsorbent is made of, for example, zeolite, and has CO2 adsorption performance depending on temperature as shown in FIG. 2, as in the conventional example described above. That is, the amount of CO2 that can be adsorbed by the CO2 adsorbent increases as the temperature of the CO2 adsorbent decreases, and decreases as the temperature increases. In the CO2 separation and recovery system 1 of the present embodiment, the temperature characteristics of the CO2 adsorbent are used to lower the temperature of the CO2 adsorber to a low temperature (for example, 50°C) suitable for CO2 adsorption. In addition to adsorbing CO2, the temperature of the CO2 adsorber is raised to a high temperature (for example, 200°C) suitable for desorption of CO2, thereby desorbing the adsorbed CO2, thereby performing adsorption and desorption of CO2. Execute.

The compressor 8 is composed of, for example, an electric pump, and it is possible to keep the upstream side of the compressor 8 in a negative pressure state and the downstream side thereof in a pressurized state. By applying a negative pressure to the upstream side, the CO2 desorbed from each CO2 adsorber and stored in the storage tank 9 in a compressed state. Driving/stopping of the compressor 8 is controlled by an ECU 2, which will be described later.

The exhaust passage 4 is connected to a first exhaust passage 11 on the upstream side of the four CO2 separation devices A, B, C, D, and the first exhaust passage 11 connects to the four CO2 separation devices A, B, C, It has branch passages 11a, 11b, 11c, and 11d respectively connected to D. The branch passages 11a, 11b, 11c, and 11d are provided with valves IN1, IN2, IN3, and IN4 for switching opening and closing of the branch passages 11a, 11b, 11c, and 11d, respectively.

Heat exchangers A, B, C, D and CO2 adsorbers A, B, C, D are connected to each other by a second exhaust passage 12 . The second exhaust passage 12 has branch passages 12a, 12b, 12c and 12d that connect with the heat exchangers A, B, C and D, respectively. The branch passages 12a, 12b, 12c and 12d are provided with valves O1, O2, O3 and O4 for switching opening and closing of the branch passages 12a, 12b, 12c and 12d.

In addition, the second exhaust passage 12 further has branch passages 12e, 12f, 12g and 12h connected to the CO2 adsorbers A, B, C and D, respectively. The branch passages 12e, 12f, 12g and 12h are provided with valves A1, A2, A3 and A4 for switching opening and closing of the branch passages 12e, 12f, 12g and 12h.

The second exhaust passage 12 further has branch passages 12i, 12j, 12k, and 12l. The branch passage 12i connects the branch passages 12a, 12b, 12e to each other. The branch passage 12j connects the branch passages 12b, 12c, 12i with each other. The branch passage 12k connects the branch passages 12c, 12d, 12h and 12j with each other. The branch passage 12l connects the branch passages 12d, 12g, 12h and 12k to each other. The branch passages 12i, 12j, 12k and 12l are provided with valves S1, S2, S3 and S4 for switching opening and closing of the branch passages 12i, 12j, 12k and 12l.

The second exhaust passage 12 further has branch passages 12m and 12n. The branch passage 12m connects the branch passages 12a, 12f and 12i to each other. A branch passage n connects the branch passages 12f, 12g, 12l, and 12m to each other. The branch passage 12m is provided with a valve B1 for switching opening and closing of the branch passage 12m.

The CO2 adsorbers A, B, C, and D are connected to a third exhaust passage 13 that is open to the atmosphere via a one-way valve 5 . The third exhaust passage 13 has branch passages 13a, 13b, 13c and 13d connected to the CO2 adsorbers A, B, C and D, respectively. The branch passages 13a, 13b, 13c and 13d are provided with valves E1, E2, E3 and E4 for switching opening and closing of the branch passages 13a, 13b, 13c and 13d. A CO2 concentration sensor 7 is provided on the downstream side of the branch passages 13a, 13b, 13c, and 13d of the third exhaust passage 13, and the CO2 concentration sensor 7 detects the CO2 concentration of the exhaust gas at its installation position. , and outputs the detected value Cco2 to the ECU 2, which will be described later.

Also, the CO2 adsorbers A, B, C, and D are connected to the compressor 8 and the storage tank 9 by the fourth exhaust passage 14 . The fourth exhaust passage 14 has branch passages 14a, 14b, 14c and 14d connected to the CO2 adsorbers A, B, C and D, respectively. The branch passages 14a, 14b, 14c and 14d are provided with valves R1, R2, R3 and R4 for switching opening and closing of the branch passages 14a, 14b, 14c and 14d.

Furthermore, the fifth exhaust passage 15 connects the branch passages 11a, 11b, 11c, and 11d of the first exhaust passage 11 to each other downstream of the valves IN1, IN2, IN3, and IN4. The fifth exhaust passage 15 has branch passages 15a, 15b, 15c and 15d respectively connected to the branch passages 11a, 11b, 11c and 11d. The branch passages 15a, 15b, 15c and 15d are provided with valves C1, C2, C3 and C4 for switching opening and closing of the branch passages 15a, 15b, 15c and 15d. A radiator 6 is provided in the fifth exhaust passage 15 . The radiator 6 is configured so that the exhaust gas can flow through the inside thereof, and the heat of the exhaust gas is released to the outside to cool the exhaust gas. The radiator 6 only needs to release the heat of the exhaust gas to the outside through heat exchange, and any known structure such as an air-cooled system or a water-cooled system can be adopted.

FIG. 6 shows the control device of the CO2 separation and recovery system 1. As shown in FIG. The ECU 2 shown in the figure is composed of a microcomputer including a CPU, a RAM, a ROM and an I/O interface (none of which are shown). The ECU 2 operates the 29 valves IN1, IN2, IN3, IN4, O1, O2, O3, O4, A1, A2, A3, A4, S1, S2 according to the detection signal of the CO2 concentration sensor 7 and the like. , S3, S4, B1, E1, E2, E3, E4, R1, R2, R3, R4, C1, C2, C3, C4 by controlling the opening and closing of each of the CO2 separation devices A, B, C, D. The operation mode switching control for switching the operation mode of is executed. The operation mode switching control will be described below with reference to FIGS. 7 and 8. FIG.

FIG. 7 is a flowchart showing control processing of operation mode switching control. This process is executed at predetermined time intervals while the engine 3 is in a normal operating state. In this process, first, in step 101 (illustrated as "S101"; the same shall apply hereinafter), it is determined whether or not the CO2 separation/recovery by the CO2 separation/recovery system 1 is being executed. If the determination result of step 101 is YES, the process proceeds to step 102 . On the other hand, if the determination result of step 101 is NO and the CO2 separation/recovery system 1 is not executing the CO2 separation/recovery, this process ends.

In step 102, the current detection value Cco2 of the CO2 concentration of the de-CO2 exhaust gas is obtained from the CO2 concentration sensor 7 provided in the third exhaust passage 13. FIG. Next, at step 103, it is determined whether or not the detected value Cco2 exceeds a predetermined threshold concentration Cco2REF. When the detected value Cco2 of the CO2 concentration sensor 7 exceeds the threshold concentration Cco2REF, the CO2 adsorption amount in the CO2 adsorber of the CO2 separation device currently executing the CO2 adsorption process is within the adsorption allowance. It is set to a value at which it can be judged that the CO2 that exceeds the capacity and is not adsorbed by the CO2 adsorber is overflowing to the downstream side.

If the determination result of step 103 is YES, that is, if the detected value Cco2 is higher than the threshold concentration Cco2REF, the process proceeds to step 104 . On the other hand, if the determination result of step 103 is NO, that is, if the detected value Cco2 is equal to or less than the threshold concentration Cco2REF, this process ends.

In step 104, based on the determination that the CO2 adsorber of the CO2 separation device currently performing the CO2 adsorption process has reached a saturated state, the next operation to be performed by the CO2 separation devices A, B, C, and D Detect mode. The switching order of the operation modes is as shown in FIG.

Next, in step 105, a map such as that shown in FIG. 8 is used to search for valves to be opened. In the map of FIG. 8, the open/closed states of the valves in each of modes 1 to 4 are set. In FIG. 8, open valves are indicated by "o", and valves not indicated by "o" are closed. Subsequently, in step 106, by controlling the opening and closing of the valves based on the search results, the switching of the operation modes of the CO2 separation devices A, B, C, and D is completed, and each CO2 separation device starts executing a new process. be started.

Next, operations of the CO2 separation and recovery system 1 in each mode will be described with reference to FIGS. 9 to 12. FIG. FIG. 9 shows when mode 1 is executed, that is, CO2 separation device A performs desorption processing, CO2 separation device B performs heating processing, CO2 separation device C performs cooling processing, and CO2 separation device C performs cooling processing. The separation device D shows a state in which adsorption processing is being performed. In mode 1, the valves IN1, O1, O2, O3, C2, C3, A4, S1, S3, E4 and R1 are open and the other valves are closed according to the map of FIG.

First, high-temperature exhaust gas discharged from the engine 3 flows from the exhaust passage 4 into the heat exchanger A of the CO2 separator A through the branch passage 11a. Since the CO2 separator A had been heat-treated in the previous mode (mode 4), the temperature of the CO2 adsorber A has already risen to some extent. The high-temperature exhaust gas loses heat by passing through the heat exchanger A, and the temperature drops. At this time, desorption processing is performed in the CO2 separator A. That is, the CO2 adsorber A is further heated by the heat taken from the exhaust gas by the heat exchanger A, thereby increasing the temperature of the CO2 adsorber A and desorbing the adsorbed CO2. The desorbed CO 2 flows through the opened valve R 1 , the branch passage 14 a and the fourth exhaust passage 14 , is compressed by the compressor 8 , and is stored in the storage tank 9 .

The exhaust gas whose temperature has been lowered by passing through the heat exchanger A flows into the heat exchanger B of the CO2 separator B through the branch passages 12a, 12i and 12b. Since the CO2 separator B was performing adsorption treatment in the previous mode (mode 4), the CO2 adsorber B is in a low temperature state. As the exhaust gas passes through the heat exchanger B, heat is further taken away, and the temperature is further lowered. At this time, heat treatment is performed in the CO2 separator B. FIG. That is, the heat exchanger B heats the CO2 adsorber B with the heat taken from the exhaust gas, and the temperature of the CO2 adsorber B rises.

The exhaust gas whose temperature has been further lowered by passing through the heat exchanger B passes through the branch passages 11b and 15b, flows into the radiator 6, and is further deprived of heat by the radiator 6 to be cooled. The exhaust gas that has passed through the radiator 6 and has been cooled flows into the heat exchanger C of the CO2 separator C through the branch passages 15c and 11c. Since the CO2 separator C was performing desorption processing in the previous mode (mode 4), the CO2 adsorber C is in a high temperature state. The cooled exhaust gas takes heat from the CO2 adsorber C by passing through the heat exchanger C. Thereby, the cooling process in the CO2 separation device C is performed. That is, the cooled exhaust gas passing through the heat exchanger C cools the CO2 adsorber C, thereby lowering the temperature of the CO2 adsorber C.

After passing through the heat exchanger C, the exhaust gas flows into the CO2 adsorber D of the CO2 separator D through the branch passages 12c, 12k, and 12h. Since the CO2 separator D was performing a cooling process in the previous mode (mode 4), the CO2 adsorber D is already cooled to some extent. The low-temperature flue gas further takes heat from the CO2 adsorber D by passing through the CO2 adsorber D. Thereby, the adsorption treatment is performed in the CO2 separation device D. FIG. That is, the CO2 adsorber D adsorbs CO2 in the exhaust gas. The CO2-removed exhaust gas from which CO2 has been removed or reduced flows out from the CO2 adsorber D and is discharged to the atmosphere via the branch passage 13d, the third exhaust passage 13 and the one-way valve 5.

Next, the operation of the CO2 separation and recovery system 1 in mode 2 will be described. FIG. 10 shows when mode 2 is executed, that is, CO2 separation device B performs desorption processing, CO2 separation device D performs heating processing, CO2 separation device A performs cooling processing, and CO2 separation device A performs cooling processing. A state in which the separation device C is performing the adsorption process is shown. In mode 2, the valves IN2, O1, O2, O4, C1, C4, A3, S2, S3, B1, E3 and R2 are open and the other valves are closed according to the map in FIG.

First, high-temperature exhaust gas discharged from the engine 3 passes through the branch passage 11b from the exhaust passage 4 and flows into the heat exchanger B of the CO2 separator B. As shown in FIG. Since the CO2 separation device B was performing the heat treatment in the previous mode (mode 1), the temperature of the CO2 adsorber B has already risen to some extent. The high-temperature exhaust gas loses heat by passing through the heat exchanger B, and the temperature drops. At this time, desorption processing is performed in the CO2 separator B. FIG. That is, the CO2 adsorber B is further heated by the heat taken from the exhaust gas by the heat exchanger B, thereby increasing the temperature of the CO2 adsorber B and desorbing the adsorbed CO2. The desorbed CO2 flows through the opened valve R2, the branch passage 14b and the fourth exhaust passage 14, is compressed by the compressor 8, and is stored in the storage tank 9.

The exhaust gas whose temperature has been lowered by passing through the heat exchanger B flows into the heat exchanger D of the CO2 separation device D through the branch passages 12b, 12j, 12k, and 12d. Since the CO2 separator D was performing adsorption treatment in the previous mode (mode 1), the CO2 adsorber D is in a low temperature state. As the exhaust gas passes through the heat exchanger D, heat is further taken away, and the temperature is further lowered. At this time, heat treatment is performed in the CO2 separation device D. FIG. That is, the heat exchanger D heats the CO2 adsorber D with the heat taken from the exhaust gas, and the temperature of the CO2 adsorber D rises.

The exhaust gas whose temperature has been further lowered by passing through the heat exchanger D passes through the branch passages 11d and 15d, flows into the radiator 6, and is further deprived of heat by the radiator 6 to be cooled. After passing through the radiator 6 and cooled, the exhaust gas flows into the heat exchanger A of the CO2 separator A through the branch passages 15a and 11a. Since the CO2 separator A was performing the desorption process in the previous mode (mode 1), the CO2 adsorber A is in a high temperature state. The cooled exhaust gas takes heat from the CO2 adsorber A by passing through the heat exchanger A. Thereby, the cooling process is performed in the CO2 separation device A. FIG. That is, the cooled exhaust gas passing through the heat exchanger A cools the CO2 adsorber A, thereby lowering the temperature of the CO2 adsorber A.

The exhaust gas that has passed through the heat exchanger A flows into the CO2 adsorber C of the CO2 separator C through the branch passages 12a, 12m, 12n, and 12g. Since the CO2 separator C was performing a cooling process in the previous mode (mode 1), the CO2 adsorber C is already cooled to some extent. The low-temperature flue gas further takes heat from the CO2 adsorber C by passing through the CO2 adsorber C. Thereby, the adsorption process is performed in the CO2 separation device C. FIG. That is, the CO2 adsorber C adsorbs CO2 in the exhaust gas. The CO2-removed exhaust gas from which CO2 has been removed or reduced flows out of the CO2 adsorber C and is discharged to the atmosphere via the branch passage 13c, the third exhaust passage 13 and the one-way valve 5.

Next, the operation of the CO2 separation and recovery system 1 in mode 3 will be described. FIG. 11 shows when mode 3 is executed, that is, CO2 separation device D performs desorption processing, CO2 separation device C performs heating processing, CO2 separation device B performs cooling processing, and CO2 separation device B performs cooling processing. It shows a state where the separation device A is performing adsorption processing. In mode 3, the valves IN4, O2, O3, O4, C2, C3, A1, S1, S3, E1 and R4 are open and the other valves are closed according to the map in FIG.

First, high-temperature exhaust gas discharged from the engine 3 flows from the exhaust passage 4 into the heat exchanger D of the CO2 separator D through the branch passage 11d. Since the CO2 separator D had been heat-treated in the previous mode (mode 2), the temperature of the CO2 adsorber D has already risen to some extent. The high-temperature exhaust gas loses heat by passing through the heat exchanger D, and the temperature drops. At this time, a desorption process is performed in the CO2 separation device D. That is, the heat exchanger D further heats the CO2 adsorber D with the heat taken from the exhaust gas, thereby increasing the temperature of the CO2 adsorber D and desorbing the adsorbed CO2. The desorbed CO 2 flows through the opened valve R 4 , the branch passage 14 d and the fourth exhaust passage 14 , is compressed by the compressor 8 , and is stored in the storage tank 9 .

The exhaust gas whose temperature has been lowered by passing through the heat exchanger D flows into the heat exchanger C of the CO2 separator C through the branch passages 12d, 12k, and 12c. Since the CO2 separator C was performing adsorption treatment in the previous mode (mode 2), the CO2 adsorber C is in a low temperature state. As the exhaust gas passes through the heat exchanger C, heat is further taken away, and the temperature is further lowered. At this time, heat treatment is performed in the CO2 separation device C. FIG. That is, the heat exchanger C heats the CO2 adsorber C with the heat taken from the exhaust gas, and the temperature of the CO2 adsorber C rises.

The exhaust gas whose temperature has been further lowered by passing through the heat exchanger C passes through the branch passages 11c and 15c, flows into the radiator 6, and is further deprived of heat by the radiator 6 to be cooled. The exhaust gas that has passed through the radiator 6 and is cooled flows into the heat exchanger B of the CO2 separator B through the branch passages 15b and 11b. Since the CO2 separator B was performing the desorption process in the previous mode (mode 2), the CO2 adsorber B is in a high temperature state. The cooled exhaust gas takes heat from the CO2 adsorber B by passing through the heat exchanger B. Thereby, the cooling process is performed in the CO2 separation device B. FIG. That is, the cooled exhaust gas passing through the heat exchanger B cools the CO2 adsorber B, thereby lowering the temperature of the CO2 adsorber B.

After passing through the heat exchanger B, the exhaust gas flows into the CO2 adsorber A of the CO2 separator A through branch passages 12b, 12i, and 12e. Since CO2 separator A was performing a cooling process in the previous mode (mode 2), CO2 adsorber A has already cooled to some extent. The low-temperature flue gas further takes heat from the CO2 adsorber A by passing through the CO2 adsorber A. Thereby, the adsorption process is performed in the CO2 separation device A. That is, the CO2 adsorber A adsorbs CO2 in the exhaust gas. The CO2-removed exhaust gas from which CO2 has been removed or reduced flows out of the CO2 adsorber A, passes through the branch passage 13a, the third exhaust passage 13 and the one-way valve 5 and is discharged to the atmosphere.

Finally, the operation of the CO2 separation and recovery system 1 in Mode 4 will be explained. FIG. 12 shows when mode 4 is executed, that is, the CO2 separation device C performs desorption processing, the CO2 separation device A performs heating processing, the CO2 separation device D performs cooling processing, and the CO2 separation device D performs cooling processing. A state in which the separation device B is performing the adsorption process is shown. In mode 4, the valves IN3, O1, O3, O4, C1, C4, A2, S1, S2, S4, E2 and R3 are open and the other valves are closed according to the map of FIG.

First, high-temperature exhaust gas discharged from the engine 3 passes through the branch passage 11c from the exhaust passage 4 and flows into the heat exchanger C of the CO2 separator C. As shown in FIG. Since the CO2 separator C had been heat-treated in the previous mode (mode 3), the temperature of the CO2 adsorber C has already risen to some extent. The high-temperature exhaust gas loses heat as it passes through the heat exchanger C, and the temperature drops. At this time, a desorption process is performed in the CO2 separator C. That is, the CO2 adsorber C is further heated by the heat taken from the exhaust gas by the heat exchanger C, so that the temperature of the CO2 adsorber C rises and the adsorbed CO2 is desorbed. The desorbed CO 2 flows through the opened valve R 3 , the branch passage 14 c and the fourth exhaust passage 14 , is compressed by the compressor 8 , and is stored in the storage tank 9 .

The exhaust gas whose temperature has been lowered by passing through the heat exchanger C flows into the heat exchanger A of the CO2 separator A through the branch passages 12c, 12j, 12i and 12a. Since the CO2 separator A was performing adsorption treatment in the previous mode (mode 3), the CO2 adsorber A is in a low temperature state. As the exhaust gas passes through the heat exchanger A, it loses more heat and its temperature further drops. At this time, heat treatment is performed in the CO2 separation device A. That is, the heat exchanger A heats the CO2 adsorber A with the heat taken from the exhaust gas, and the temperature of the CO2 adsorber A rises.

The exhaust gas whose temperature has been further lowered by passing through the heat exchanger A passes through the branch passages 11a and 15a, flows into the radiator 6, and is further deprived of heat by the radiator 6 to be cooled. The exhaust gas that has passed through the radiator 6 and has been cooled flows into the heat exchanger D of the CO2 separator D through the branch passages 15d and 11d. Since the CO2 separator D was performing desorption processing in the previous mode (mode 3), the CO2 adsorber D is in a high temperature state. The cooled exhaust gas takes heat from the CO2 adsorber D by passing through the heat exchanger D. Thereby, the cooling process is performed in the CO2 separation device D. FIG. That is, the cooled exhaust gas passing through the heat exchanger D cools the CO2 adsorber D, thereby lowering the temperature of the CO2 adsorber D.

After passing through the heat exchanger D, the exhaust gas flows into the CO2 adsorber B of the CO2 separator B through the branch passages 12d, 12l, 12n, and 12f. Since CO2 separator B was performing a cooling process in the previous mode (mode 3), CO2 adsorber B is already cooled to some extent. The low-temperature flue gas further takes heat from the CO2 adsorber B by passing through the CO2 adsorber B. Thereby, the adsorption process is performed in the CO2 separation device B. FIG. That is, the CO2 adsorber B adsorbs CO2 in the exhaust gas. The CO2-removed exhaust gas from which CO2 has been removed or reduced flows out of the CO2 adsorber B and is discharged to the atmosphere via the branch passage 13b, the third exhaust passage 13 and the one-way valve 5.

As described above, the CO2 separation and recovery system 1 mounted on the vehicle performs adsorption treatment of CO2 in the exhaust gas between the four CO2 separation devices A, B, C, and D, and cooling as a pre-stage of the adsorption treatment. Four different treatments are alternately performed: treatment, desorption of CO2 from the adsorber, and heat treatment as a pre-desorption treatment. As a result, it is possible to greatly reduce the emission of CO2 in the exhaust gas emitted from the engine 3 into the atmosphere while the vehicle is running.

In particular, according to the CO2 separation and recovery system 1 of the present embodiment, a plurality of first to fifth exhaust passages are provided, and by controlling a plurality of open/close valves provided on the plurality of exhaust passages, Since the exhaust gas flows through the four CO2 separation devices in order and the order of the flow can be switched, the heat of the exhaust gas can be efficiently used. In addition, as shown in FIGS. 9 to 12, in the CO2 separation and recovery system 1 of the present embodiment, the configuration of the exhaust passages is made efficient, and the number and installation distance of the exhaust passages are minimized. . Therefore, even if the exhaust passage is the same, one of the features is that the passage direction of the exhaust gas is reversed depending on the operation mode. With such a configuration, in the CO2 separation and recovery system 1 of the present embodiment, while avoiding an increase in the required energy due to the use of heaters, coolers, etc., the heat of the exhaust gas is efficiently used to operate each CO2 adsorber. Adsorption/desorption of CO2 can be performed satisfactorily and rapidly by controlling the temperature in an appropriate state.

It should be noted that the present invention is not limited to the above described embodiments and can be implemented in various ways. For example, in the embodiment, four CO2 separators A to D are used, but a configuration using five or more CO2 separators is also possible. In this case, any one or all of the desorption treatment, heat treatment, cooling treatment, and adsorption treatment can be performed by a plurality of CO2 separation devices, and the heat of the exhaust gas can be used more efficiently. However, the adsorption/desorption of CO2 can be performed more efficiently.

In addition, in the embodiment, when the concentration of CO2 in the deCO2 exhaust gas exceeds a predetermined value, it is determined that the adsorption capacity of the CO2 adsorber that performs the adsorption process has been reached, and the operation mode is switched. The flow rate and CO2 concentration of the CO2 gas collected in the storage tank may be detected, and when the detected values are below a predetermined value, it may be determined that the desorption is completed, and the operation mode may be switched.

In addition, in the embodiment, the configuration of the exhaust passages and the opening/closing valves (the first to fifth exhaust passages and 29 opening/closing valves) capable of switching the operation mode was exemplified, but equivalent functions can be realized. If so, it is also possible to employ different configurations of exhaust passages and on-off valves.

In addition, in the embodiments, zeolite was exemplified as an adsorbent for CO2, but various adsorbents (such as silica gel, lithium composite oxide, or amine) can be used as long as they can adsorb and desorb CO2 depending on the temperature. can be adopted.

Further, the embodiments are examples in which the present invention is applied to a gasoline engine mounted on a vehicle, but the present invention is not limited to this, and may be applied to other types of engines such as diesel engines. , and can also be applied to engines other than those for vehicles. In addition, it is possible to change the detailed configuration as appropriate within the scope of the present invention.

1 CO2 separation and recovery system 2 ECU (electronic control unit) (control device)
3 Engine (internal combustion engine)
4 exhaust passage 6 radiator 11 first exhaust passage 12 second exhaust passage 13 third exhaust passage 14 fourth exhaust passage 15 fifth exhaust passage A CO2 separation device A (CO2 separation device)
B CO2 separation device B (CO2 separation device)
C CO2 separation device C (CO2 separation device)
D CO2 separation device D (CO2 separation device)
IN1, IN2, IN3, IN4 Open/close valve (multiple open/close valves)
O1, O2, O3, O4 On-off valve (multiple on-off valves)
C1, C2, C3, C4 on-off valves (multiple on-off valves)
A1, A2, A3, A4 Open/close valve (multiple open/close valves)
S1, S2, S3, S4 Open/close valves (multiple open/close valves)
B1 open/close valve (multiple open/close valves)
E1, E2, E3, E4 on-off valve (multiple on-off valves)
R1, R2, R3, R4 on-off valve (multiple on-off valves)

Claims (5)

A CO2 separation and recovery system for an internal combustion engine that separates and recovers CO2 from exhaust gas emitted from the internal combustion engine,
A CO2 adsorber configured to allow the exhaust gas to flow and capable of adsorbing and desorbing CO2 according to temperature; and a CO2 adsorber configured to allow the exhaust gas to flow and between the exhaust gas and the CO2 adsorber. at least four CO2 separation units, each having a heat exchanger capable of exchanging heat;
a plurality of exhaust passages, and a plurality of on-off valves provided in the plurality of exhaust passages, wherein the exhaust gas passes through the at least four CO2 separation devices in sequence, and the CO2 adsorber and the heat of each CO2 separation device. an exhaust passageway device configured to flow through one of the exchangers;
a control device that switches the flow order of the exhaust gas to the at least four CO2 separation devices by controlling the plurality of open/close valves;
with
desorbing CO2 from the CO2 adsorber by causing the exhaust gas to flow through the heat exchanger in the most upstream CO2 separation device through which the exhaust gas flows first among the at least four CO2 separation devices;
Of the at least four CO2 separation devices, in the most downstream CO2 separation device through which the exhaust gas flows last, the exhaust gas is allowed to flow through the CO2 adsorber so that the CO2 in the exhaust gas is transferred to the CO2 adsorber. A CO2 separation and recovery system for an internal combustion engine, characterized by adsorption. The plurality of exhaust passages are
a first exhaust passage connected between the internal combustion engine and the at least four CO2 separation devices for introducing exhaust gas discharged from the internal combustion engine to the heat exchanger of the most upstream CO2 separation device; ,
a second exhaust passage interconnecting the at least four CO2 separation devices;
a third exhaust passage connected to the CO2 adsorbers of the at least four CO2 separation devices and for discharging into the atmosphere exhaust gas that has passed through the CO2 adsorbers of the most downstream CO2 separation device;
a fourth exhaust passage connected to the CO2 adsorbers of the at least four CO2 separation devices for recovering CO2 desorbed from the CO2 adsorbers of the most upstream CO2 separation device;
The CO2 separation and recovery system for an internal combustion engine according to claim 1, characterized by comprising: The at least four CO2 separation devices are arranged in the order of first, second, third and fourth CO2 separation devices from upstream to downstream through which the exhaust gas flows,
In the first CO2 separation device, the exhaust gas discharged from the internal combustion engine flows through the heat exchanger of the first CO2 separation device to desorb CO2 from the CO2 adsorber of the first CO2 separation device. is executed and
In the second CO2 separation device, the exhaust gas that has passed through the first CO2 separation device flows into the heat exchanger of the second CO2 separation device, whereby heat treatment is performed to heat the CO2 adsorber of the second CO2 separation device. ,
In the third CO2 separation device, the exhaust gas that has passed through the second CO2 separation device flows into the heat exchanger of the third CO2 separation device, thereby performing a cooling process of cooling the CO2 adsorber of the third CO2 separation device. ,
In the fourth CO2 separation device, the exhaust gas that has passed through the third CO2 separation device flows into the CO2 adsorber of the fourth CO2 separation device, thereby adsorbing CO2 in the exhaust gas onto the CO2 adsorber of the fourth CO2 separation device. 3. The CO2 separation and recovery system for an internal combustion engine according to claim 2, wherein an adsorption process that causes the CO2 separation and recovery is performed. said plurality of exhaust passages further comprising a fifth exhaust passage connected to said first, second, third and fourth CO2 separation devices;
4. The internal combustion engine according to claim 3, further comprising a radiator disposed in the fifth exhaust passage for cooling the exhaust gas that has passed through the heat exchanger of the second CO2 separation device. CO2 separation and recovery system. each of the at least four CO2 separation devices is set to one of the first, second, third and fourth CO2 separation devices by the control of the plurality of on-off valves by the control device; 5. The CO2 separation and recovery system for an internal combustion engine according to claim 3, wherein said cooling process, said adsorption process and said heat treatment are repeatedly executed in order.

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