CO2 capture system for work equipment

Abstract

This invention provides a CO2 recovery system for work machines that can effectively utilize the heat generated from internal combustion engines. [Solution] The CO2 recovery system 10 mounted on a work machine 100 having a vehicle body 102 and an engine 103 comprises: a main exhaust gas passage 41 connected to the engine 103 and through which exhaust gas EG discharged from the engine 103 passes; a dryer 30 provided in the middle of the main exhaust gas passage 41 and having a moisture adsorbent 35 that adsorbs moisture in the exhaust gas EG; a recovery device 20 connected to the main exhaust gas passage 41 and recovering CO2 from the exhaust gas EG that has passed through the dryer 30; and a regeneration gas passage 43 connected to the dryer 30 and returning the exhaust gas EG that has passed through the recovery device 20 back to the dryer 30.

Description

Technical Field

[0001] The present invention relates to a CO2 recovery system for a work machine.

Background Art

[0002] Patent Document 1 discloses a vehicle equipped with a recovery system for carbon dioxide (hereinafter referred to as CO2) contained in exhaust gas discharged from an internal combustion engine. The CO2 recovery system disclosed in Patent Document 1 recovers CO2 by the temperature swing adsorption method (hereinafter referred to as the TSA method) among physical adsorption methods. The CO2 recovery system of the TSA method physically adsorbs and recovers CO2 on an adsorbent such as zeolite, and CO2 is desorbed from the adsorbent by heating the adsorbent on which CO2 is adsorbed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] A CO2 recovery system adopting the TSA method changes the temperature of the adsorbent during the recovery and desorption of CO2. Therefore, when a CO2 recovery system adopting the TSA method is mounted on a vehicle, it is preferable to effectively utilize the heat generated from the internal combustion engine. In recent years, it has been considered to mount a CO2 recovery system on a work machine among vehicles having an internal combustion engine.

[0005] Therefore, an object of the present disclosure is to provide a CO2 recovery system for a work machine capable of effectively utilizing the heat generated from an internal combustion engine.

Means for Solving the Problems

[0006] The CO2 recovery system for a work machine according to the present disclosure is a CO2 recovery system mounted on a work machine having a vehicle body and an engine, comprising: a main exhaust gas passage connected to the engine and through which exhaust gas discharged from the engine passes; a dryer provided in the middle of the main exhaust gas passage and having a moisture adsorbent for adsorbing moisture in the exhaust gas; a recovery device connected to the main exhaust gas passage and for recovering CO2 in the exhaust gas that has passed through the dryer; and a regeneration gas passage connected to the dryer and for returning the exhaust gas that has passed through the recovery device to the dryer. [Effects of the Invention]

[0007] The CO2 recovery system for the work machine described herein can effectively utilize the heat generated from the internal combustion engine. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a schematic side view showing an example of a work machine equipped with a CO2 capture system. [Figure 2] Figure 2 is a block diagram of the CO2 capture system. [Figure 3] Figure 3 is a schematic diagram illustrating the recovery device. [Figure 4] Figure 4 is a schematic diagram illustrating a hair dryer. [Figure 5] Figure 5 is a control block diagram of the CO2 capture system. [Figure 6A] Figure 6A is a schematic diagram showing the state of the recovery device during CO2 adsorption. [Figure 6B] Figure 6B is a schematic diagram showing the state of the CO2 recovery device during CO2 release. [Figure 7A] Figure 7A is a schematic diagram showing the state of the dryer when moisture is adsorbed. [Figure 7B] Figure 7B is a schematic diagram showing the state of the dryer during regeneration. [Figure 8] Figure 8 is a block diagram showing a modified example of a CO2 capture system. [Modes for carrying out the invention]

[0009] <Summary of the embodiments of this disclosure> The embodiments of the invention disclosed herein are outlined below.

[0010] (1) The CO2 recovery system for a work machine according to the present disclosure is a CO2 recovery system mounted on a work machine having a vehicle body and an engine, comprising: a main exhaust gas passage connected to the engine and through which exhaust gas discharged from the engine passes; a dryer provided in the middle of the main exhaust gas passage and having a moisture adsorbent for adsorbing moisture in the exhaust gas; a recovery device connected to the main exhaust gas passage and for recovering CO2 in the exhaust gas that has passed through the dryer; and a regeneration gas passage connected to the dryer and for returning the exhaust gas that has passed through the recovery device to the dryer.

[0011] According to the CO2 recovery system for work machines of this disclosure, the heat contained in the exhaust gas can be used to heat and regenerate the moisture adsorbent in the dryer. In this case, there is no need to separately provide a heat source for heating the moisture adsorbent, and the heat generated by the combustion of fuel can be effectively utilized. With such a configuration, the heat generated from the engine can be effectively utilized when recovering CO2 in a CO2 recovery system mounted on a work machine.

[0012] (2) In the CO2 recovery system for the work machine of the present disclosure, the exhaust gas includes pre-recovery exhaust gas before CO2 is recovered by the recovery device and post-recovery exhaust gas after CO2 is recovered by the recovery device, and the exhaust gas returned to the dryer by the regeneration gas passage is the post-recovery exhaust gas.

[0013] According to the CO2 recovery system of the working machine of the present disclosure, the heat possessed by the exhaust gas after recovery can be used to heat and regenerate the moisture adsorbent of the dryer. In this case, there is no need to separately provide a heating source for heating the moisture adsorbent, and when recovering CO2, the heat generated from the engine can be effectively utilized.

[0014] (3) The CO2 recovery system of the working machine of the present disclosure further includes a heat exchanger for heating provided in the main exhaust gas passage between the engine and the dryer and recovering the heat of the exhaust gas.

[0015] According to the CO2 recovery system of the working machine of the present disclosure, the heat exchanger for heating can adjust the temperature of the exhaust gas supplied to the recovery device to a temperature suitable for removing moisture from the moisture adsorbent. Further, according to the CO2 recovery system of the present disclosure, the heat recovered by the heat exchanger for heating can be used to heat the medium used for regenerating the recovery device.

[0016] (4) The CO2 recovery system of the working machine of the present disclosure further includes a heat exchanger for cooling provided in the main exhaust gas passage between the heat exchanger for heating and the dryer and cooling the exhaust gas.

[0017] According to the CO2 recovery system of the working machine of the present disclosure, the heat exchanger for cooling can adjust the temperature of the exhaust gas supplied to the recovery device to a more suitable temperature for removing moisture from the moisture adsorbent.

[0018] (5) The CO2 recovery system of the working machine of the present disclosure further includes a reheating heat exchanger provided in the regeneration gas passage and reheating the exhaust gas.

[0019] According to the CO2 recovery system of the working machine of the present disclosure, the reheating heat exchanger can adjust the temperature of the exhaust gas supplied to the dryer to a temperature suitable for regenerating the moisture adsorbent.

[0020] (6) In the CO2 recovery system for the work machine of the present disclosure, the dryer includes a first dryer and a second dryer, wherein the first dryer is through which the pre-recovery exhaust gas passes, and the second dryer is through which the post-recovery exhaust gas passes.

[0021] According to the CO2 recovery system for work machines of this disclosure, while moisture is being removed from the pre-recovery exhaust gas by the first dryer, the moisture adsorbent in the second dryer can be heated and regenerated by the post-recovery exhaust gas. This allows for stable operation of the CO2 recovery system mounted on the work machine.

[0022] <Details of the embodiments of this disclosure> The embodiments of this disclosure will be described in detail below with reference to the drawings. At least some of the embodiments described below may be combined in any way.

[0023] (Regarding the work equipment) Figure 1 is a schematic side view showing an example of a work implement equipped with a CO2 capture system. Figure 1 shows work implement 100, which is an example of a work implement equipped with the CO2 capture system of this disclosure. The work implement 100 shown in Figure 1 is a tractor 101, which is a work vehicle for agricultural work. The tractor 101 comprises a vehicle body 102, an engine 103, a running gear 104, a steering gear 105, and a work implement 106. The tractor 101 travels in a work area such as a field, and the work implement 106 works in that work area. The running gear 104 has front wheels 104a and rear wheels 104b.

[0024] The vehicle body 102 comprises a chassis 121 which forms the frame, a body 122 which forms the exterior, a cabin 123, a driver's seat 124, and a coupling mechanism 125. The coupling mechanism 125 is mounted at the rear of the chassis 121 and connects the work device 106 to the chassis 121 (vehicle body 102).

[0025] As shown in Figure 1, the tractor 101 is a work implement that operates using the engine 103 as a power source. The tractor 101 further includes a CO2 recovery system 10. The CO2 recovery system 10 of this disclosure recovers CO2 contained in the exhaust gas (exhaust gas EG, which will be described later) generated when the engine 103 is operating. Unlike conventional CO2 recovery systems that are fixedly installed on the ground or elsewhere, the CO2 recovery system 10 of this disclosure is configured to be small enough to be mounted on the vehicle body 102. In the tractor 101, the CO2 recovery system 10 is mounted on the vehicle body 102. The CO2 recovery system 10 is supported by the chassis 121 and mounted inside the body 122. In this embodiment, the work implement 100 (tractor 101) is shown as an example of a CO2 recovery system 10 mounted on the chassis 121, but the mounting position of the CO2 recovery system 10 is not limited to this, and may be on the upper, lower, or rear of the cabin 123, etc. The implement 100 to which the CO2 capture system 10 of this disclosure is applied is not limited to a tractor 101, but may be other implements (for example, a combine harvester, etc.).

[0026] (CO2 capture system) Figure 2 is a block diagram showing a CO2 recovery system. The CO2 recovery system 10 of this disclosure recovers CO2 by a "physical adsorption method." The "physical adsorption method" involves adsorbing the target gas (CO2) onto a solid adsorbent (such as activated carbon or zeolite), and then recovering the target gas by desorbing it from the adsorbent by reducing the pressure or heating it.

[0027] The CO2 recovery system 10 of this disclosure recovers CO2 from exhaust gas by a "thermal swing adsorption method (hereinafter referred to as the TSA method)" which is a type of "physical adsorption method". The TSA method is a recovery method that performs adsorption and desorption operations by utilizing the difference in the adsorption capacity of the adsorbent with respect to temperature. It performs adsorption of the target gas onto the adsorbent and desorption of the target gas from the adsorbent by changing (swinging) the temperature conditions around the adsorbent.

[0028] As shown in Figure 2, the CO2 recovery system 10 of this disclosure comprises a recovery device 20, a dryer 30, an exhaust gas passage 40, a heat exchanger 50, and a circulation device 60. The CO2 recovery system 10 recovers CO2 from exhaust gas discharged from the engine 103 through the exhaust gas passage 40.

[0029] (Regarding exhaust fumes) In this explanation, the exhaust gas emitted from engine 103 is referred to as exhaust gas EG. In this explanation, exhaust gas EG may be further distinguished by changing its name. In the following explanation, exhaust gas EG before CO2 is recovered by the recovery device 20 is also referred to as pre-recovery exhaust gas EG1, and exhaust gas EG after CO2 is recovered by the recovery device 20 is also referred to as post-recovery exhaust gas EG2. Furthermore, in the following explanation, exhaust gas EG that is subject to CO2 recovery by the recovery device 20 is also referred to as recovery target gas EGA, and exhaust gas EG that is not subject to CO2 recovery by the recovery device 20 is also referred to as non-recovery target gas EGB.

[0030] (Exhaust gas passage) The exhaust gas passage 40 is a pipe member through which the exhaust gas EG passes and connects various parts of the CO2 recovery system 10. The exhaust gas passage 40 includes the main exhaust gas passage 41 and the sub-exhaust gas passage 42.

[0031] The main exhaust gas passage 41 is an exhaust gas passage 40 that connects the engine 103 and the recovery device 20. In other words, the recovery device 20 is connected to the engine 103 by the main exhaust gas passage 41. The exhaust gas EG discharged from the engine 103 is sent to the recovery device 20 and the dryer 30 through the main exhaust gas passage 41. The dryer 30 is located in the main exhaust gas passage 41 between the engine 103 and the recovery device 20. The dryer 30 is connected to the engine 103 by the main exhaust gas passage 41.

[0032] The sub-exhaust gas passage 42 is an exhaust gas passage 40 branched from the main exhaust gas passage 41. The sub-exhaust gas passage 42 branches off from the part of the main exhaust gas passage 41 that connects the engine 103 and the dryer 30. The sub-exhaust gas passage 42 connects the main exhaust gas passage 41 and the dryer 30. The sub-exhaust gas passage 42 is connected to the engine 103 via the main exhaust gas passage 41 and supplies exhaust gas EG discharged from the engine 103 to the dryer 30. In the following description, the exhaust gas EG supplied to the dryer 30 by the sub-exhaust gas passage 42 will also be referred to as regenerative gas EG3. In the CO2 recovery system 10 of this disclosure, the regenerative gas EG3 is used as a heat source to heat (regenerate) the moisture adsorbent 35 of the dryer 30.

[0033] In the CO2 recovery system 10 of this disclosure, the exhaust gas passage 40 further includes a regeneration gas passage 43. The regeneration gas passage 43 is the exhaust gas passage 40 connecting the recovery device 20 and the dryer 30. The regeneration gas passage 43 connects the downstream side of the recovery device 20 in the flow direction of the exhaust gas EG (the second opening 23b, which will be described later) to the downstream side of the dryer 30 in the flow direction of the exhaust gas EG (the second opening 33b, which will be described later). The regeneration gas passage 43 supplies the exhaust gas EG used for regenerating the dryer 30 to the dryer 30. The exhaust gas EG supplied to the dryer 30 by the regeneration gas passage 43 is the recovered exhaust gas EG2. In the CO2 recovery system 10 of this disclosure, the recovered exhaust gas EG2 is used as a heat source to heat (regenerate) the moisture adsorbent 35 of the dryer 30.

[0034] In the CO2 recovery system 10 of this disclosure, the exhaust gas passage 40 further includes a waste heat utilization gas passage 44. The waste heat utilization gas passage 44 is an exhaust gas passage 40 that sends exhaust gas EG to a power generation device 80. The waste heat utilization gas passage 44 connects the sub-exhaust gas passage 42 and the dryer 30 to the power generation device 80. The waste heat utilization gas passage 44 includes a portion that connects the middle section of the sub-exhaust gas passage 42 to the power generation device 80, and a portion that connects the dryer 30 to the power generation device 80. The power generation device 80 generates electricity using the waste heat of exhaust gas EG discharged from the engine 103.

[0035] In the CO2 recovery system 10 of this disclosure, the exhaust gas passage 40 further includes an exhaust gas discharge passage 45. The exhaust gas discharge passage 45 is an exhaust gas passage 40 that discharges exhaust gas EG into the atmosphere. The exhaust gas discharge passage 45 is connected to the upstream side of the dryer 30 (the first opening 33a, which will be described later) in the flow direction of the exhaust gas EG. The exhaust gas discharge passage 45 discharges the exhaust gas EG used for regeneration of the dryer 30 into the atmosphere. Furthermore, the exhaust gas discharge passage 45 discharges the exhaust gas EG used for power generation in the power generation device 80 into the atmosphere.

[0036] In the CO2 recovery system 10 of this disclosure, the exhaust gas passage 40 further includes a CO2 discharge passage 46. The CO2 discharge passage 46 is an exhaust gas passage 40 that discharges the CO2 recovered by the recovery device 20 to the outside of the recovery device 20. The CO2 discharge passage 46 connects the upstream side of the recovery device 20 (the first opening 23a, which will be described later) in the flow direction of the exhaust gas EG to the tank 90. ​​The CO2 released from the CO2 adsorbent 25 in the recovery device 20 is discharged to the outside of the recovery device 20 via the CO2 discharge passage 46 and stored in the tank 90.

[0037] (circulation device) The circulation device 60 is a device that circulates a medium for heating and cooling each part of the CO2 recovery system 10. The circulation device 60 comprises a low-pressure pump 61, a high-pressure pump 62, and piping 63. The piping 63 includes low-pressure piping 63a and high-pressure piping 63b. In the CO2 recovery system 10 of this embodiment, water is used as the medium. However, the medium is not limited to water and may be other liquid substances (e.g., propylene glycol), a mixture of multiple liquid substances, etc.

[0038] The low-pressure pump 61 supplies low-pressure water LW to each part of the CO2 recovery system 10 via the low-pressure piping 63a. The low-pressure water LW is a medium used to cool the exhaust gas EG and the CO2 adsorbent 25 and moisture adsorbent 35, which will be described later, and is colder and lower in pressure than the high-pressure water HW, which will be described later. The circulation device 60 has a closed circuit including the cooling heat exchanger 52, the low-pressure pump 61 and the low-pressure piping 63a, which will be described later. The low-pressure water LW is circulated by the low-pressure pump 61 and the low-pressure piping 63a in the circuit that passes through the cooling heat exchanger 52.

[0039] The high-pressure pump 62 supplies high-pressure water HW to each part of the CO2 recovery system 10 via high-pressure piping 63b. The high-pressure water HW is the medium used to heat the exhaust gas EG and the CO2 adsorbent 25 and moisture adsorbent 35, which will be described later, and is hotter and higher in pressure than the low-pressure water LW. The circulation device 60 has a closed circuit including a heating heat exchanger 51, a reheating heat exchanger 53, a sub-heating heat exchanger 54, the high-pressure pump 62, and the high-pressure piping 63b, which will be described later. The high-pressure water HW is circulated by the high-pressure pump 62 and the high-pressure piping 63b in a circuit that passes through the heating heat exchanger 51, the reheating heat exchanger 53, and the sub-heating heat exchanger 54.

[0040] (heat exchanger) The heat exchanger 50 has the function of recovering heat from the exhaust gas EG passing through the exhaust gas passage 40, and / or adjusting the temperature of the exhaust gas EG passing through the exhaust gas passage 40. In the CO2 recovery system 10, the heat exchanger 50 includes a heating heat exchanger 51 and a cooling heat exchanger 52.

[0041] The heating heat exchanger 51 is installed in the main exhaust gas passage 41 between the engine 103 and the dryer 30. The heating heat exchanger 51 exchanges heat between the exhaust gas EG passing through the main exhaust gas passage 41 and the high-pressure water HW passing through the high-pressure piping 63b, thereby raising the temperature of the high-pressure water HW. In other words, the CO2 recovery system 10 recovers heat from the exhaust gas EG using the heating heat exchanger 51 and heats the high-pressure water HW. At the same time, the heating heat exchanger 51 also lowers the temperature of the exhaust gas EG.

[0042] The cooling heat exchanger 52 is located in the main exhaust gas passage 41 between the engine 103 and the dryer 30. The cooling heat exchanger 52 is located in the main exhaust gas passage 41 between the heating heat exchanger 51 and the dryer 30. The cooling heat exchanger 52 exchanges heat between the exhaust gas EG passing through the main exhaust gas passage 41 and the low-pressure water LW passing through the low-pressure pipe 63a, thereby lowering the temperature of the exhaust gas EG. At this time, the exhaust gas EG is adjusted to a temperature suitable for supply to the dryer 30.

[0043] In the CO2 recovery system 10, the heat exchanger 50 further includes a reheating heat exchanger 53 and a subheating heat exchanger 54.

[0044] The reheating heat exchanger 53 is installed in the regeneration gas passage 43. The reheating heat exchanger 53 exchanges heat between the exhaust gas EG (recovered exhaust gas EG2) passing through the regeneration gas passage 43 and the high-pressure water HW passing through the high-pressure piping 63b, thereby raising the temperature of the recovered exhaust gas EG2. At this time, the recovered exhaust gas EG2 is heated to a temperature suitable for the regeneration of the dryer 30.

[0045] The sub-heating heat exchanger 54 is installed in the sub-exhaust gas passage 42. The sub-heating heat exchanger 54 exchanges heat between the exhaust gas EG (regeneration gas EG3) passing through the sub-exhaust gas passage 42 and the high-pressure water HW passing through the high-pressure piping 63b, thereby raising the temperature of the high-pressure water HW. In other words, the CO2 recovery system 10 recovers heat from the exhaust gas EG using the sub-heating heat exchanger 54 and further heats the high-pressure water HW. At this time, the high-pressure water HW is heated to a temperature suitable for the regeneration of the recovery device 20 (the release of CO2 from the CO2 adsorbent 25, which will be explained later).

[0046] In the CO2 recovery system 10, the heat exchanger 50 further includes a recooling heat exchanger 55. The recooling heat exchanger 55 is located on the suction side of the low-pressure pump 61 and the high-pressure pump 62, on a pipe 63 through which low-pressure water LW and high-pressure water HW merge and flow. The recooling heat exchanger 55 exchanges heat between the medium flowing through the pipe 63 (water mixed with low-pressure water LW and high-pressure water HW) and the air. The recooling heat exchanger 55 cools the medium flowing through the pipe 63 to a temperature at which it can be used as low-pressure water LW.

[0047] As described above, the CO2 recovery system 10 of this embodiment is provided in the main exhaust gas passage 41 between the engine 103 and the dryer 30, and further includes a heating heat exchanger 51 that recovers heat from the exhaust gas EG. With the CO2 recovery system 10 configured in this way, the heating heat exchanger 51 can adjust the temperature of the exhaust gas EG supplied to the recovery device 20 to a temperature suitable for CO2 adsorption by the CO2 adsorbent 25. Furthermore, with the CO2 recovery system 10, the heat recovered by the heating heat exchanger 51 can heat the high-pressure water HW used for regeneration of the recovery device 20.

[0048] Furthermore, the CO2 recovery system 10 of this embodiment is provided in the main exhaust gas passage 41 between the heating heat exchanger 51 and the dryer 30, and further includes a cooling heat exchanger 52 for cooling the exhaust gas EG. With a CO2 recovery system 10 configured in this way, the cooling heat exchanger 52 can adjust the temperature of the exhaust gas EG supplied to the recovery device 20 to a temperature suitable for CO2 adsorption by the CO2 adsorbent 25.

[0049] Furthermore, the CO2 recovery system 10 of this embodiment further includes a reheating heat exchanger 53 provided in the regeneration gas passage 43 for reheating the recovered exhaust gas EG2. With the CO2 recovery system 10 configured in this way, the reheating heat exchanger 53 can adjust the temperature of the recovered exhaust gas EG2 supplied to the dryer 30 to a temperature suitable for the regeneration of the moisture adsorbent 35.

[0050] (Recovery device) Figure 3 is a schematic diagram illustrating the recovery device. The recovery device 20 recovers CO2 from the exhaust gas EG generated by the engine 103. As shown in Figures 2 and 3, the recovery device 20 is connected to the engine 103 via the main exhaust gas passage 41. The recovery device 20 includes a first recovery device 21, which is the first recovery device 20, and a second recovery device 22, which is the second recovery device 20. The first recovery device 21 and the second recovery device 22 are the same recovery device 20. In this embodiment, a configuration including two recovery devices 20 (first recovery device 21 and second recovery device 22) is illustrated, but the CO2 recovery system 10 of this disclosure may include three or more recovery devices 20.

[0051] The CO2 recovery system 10 uses one of two recovery devices 20 to adsorb CO2 from the exhaust gas EG. While one recovery device 20 is adsorbing CO2, the other recovery device 20 releases the CO2. In this explanation, the recovery device 20 that recovers CO2 is referred to as the first recovery device 21, and the recovery device 20 that releases CO2 is referred to as the second recovery device 22. In Figure 2, for the sake of explanation, the recovery device 20 on the left is labeled as the first recovery device 21, and the recovery device 20 on the right is labeled as the second recovery device 22. However, the recovery device 20 on the left also functions as the second recovery device 22, and the recovery device 20 on the right also functions as the first recovery device 21.

[0052] As shown in Figure 3, the recovery device 20 has a double-walled structure comprising an inner cylinder 23 and an outer cylinder 24. The recovery device 20 may consist only of the inner cylinder 23, and may not have a double-walled structure. The recovery device 20 further includes a CO2 adsorbent 25 filled inside the inner cylinder 23. The CO2 adsorbent 25 is a solid medium capable of adsorbing and releasing CO2. In the recovery device 20 of this embodiment, the CO2 adsorbent 25 is "zeolite". While this embodiment exemplifies the use of zeolite as the CO2 adsorbent 25, the CO2 adsorbent used in the CO2 recovery system 10 of this disclosure is not limited to this, and a CO2 adsorbent 25 composed of other materials may be used.

[0053] The inner cylinder 23 is a housing for containing the CO2 adsorbent 25 and has a first opening 23a and a second opening 23b. The first opening 23a is connected to the main exhaust gas passage 41 and the CO2 discharge passage 46. The first opening 23a serves as the inlet for the pre-recovery exhaust gas EG1 and also as the outlet for the post-recovery exhaust gas EG2. The second opening 23b is connected to the regeneration gas passage 43. The second opening 23b serves as the outlet for the post-recovery exhaust gas EG2.

[0054] The recovery device 20 has an exhaust gas switching valve 27. The exhaust gas switching valve 27 includes a first switching valve 27a provided in the main exhaust gas passage 41 on the side of the first opening 23a, and a second switching valve 27b (see Figure 4) provided in the regeneration gas passage 43 on the side of the second opening 23b. When the first switching valve 27a is "open", exhaust gas EG (exhaust gas EG1 before recovery) flows into the inner cylinder 23 from the first opening 23a. When the first switching valve 27a is "closed", exhaust gas EG does not flow into the inner cylinder 23 from the first opening 23a. The first switching valve 27a is "open" when the recovery device 20 adsorbs CO2, and is "closed" when the recovery device 20 releases CO2.

[0055] The recovery device 20 further includes a CO2 discharge valve 29. The first opening 23a also communicates with an exhaust gas discharge passage 45 that branches off from the main exhaust gas passage 41. The CO2 discharge valve 29 is provided in the exhaust gas discharge passage 45 that communicates with the first opening 23a. When the CO2 discharge valve 29 is "open", CO2 released from the CO2 adsorbent 25 is discharged from the first opening 23a to the outside of the inner cylinder 23. The CO2 discharged from the exhaust gas discharge passage 45 is stored in the tank 90 (see Figure 2). The CO2 discharge valve 29 is "open" when the recovery device 20 releases (recovers) CO2 and is "closed" when the recovery device 20 adsorbs CO2. In this way, the CO2 recovery system 10 can recover CO2 contained in the exhaust gas EG into the tank 90. In this embodiment, an example is shown in which exhaust gas EG flows from the upper side to the lower side of the recovery device 20. However, in the CO2 recovery system 10 of this disclosure, the flow direction of exhaust gas EG is not limited to this, and an example is also shown in which exhaust gas EG flows from the lower side to the upper side of the recovery device 20.

[0056] The outer cylinder 24 has an inlet 26a and an outlet 26b on its outer surface that are connected to the coil tube 26. The space between the inner cylinder 23 and the outer cylinder 24 may be filled with insulating material or the like.

[0057] The recovery device 20 further includes a coiled pipe 26. The coiled pipe 26 is a coiled piping member arranged inside the inner cylinder 23 and has an inlet 26a and an outlet 26b. The inlet 26a and outlet 26b are located outside the outer cylinder 24. The inlet 26a is an opening into which a medium for cooling the inside of the inner cylinder 23 (low-pressure water LW) or a medium for heating the inside of the inner cylinder 23 (high-pressure water HW) flows into the coiled pipe 26. The outlet 26b is an opening into which the respective mediums flow out of the coiled pipe 26. The inlet 26a and outlet 26b are each connected to the low-pressure piping 63a. In the recovery device 20, the coiled pipe 26 may be arranged along the outer circumferential surface of the inner cylinder 23.

[0058] The recovery device 20 further comprises a water switching valve 28. The water switching valve 28 includes a first low-pressure water switching valve 28a, a second low-pressure water switching valve 28b, a first high-pressure water switching valve 28c, and a second high-pressure water switching valve 28d. The first low-pressure water switching valve 28a is provided on the low-pressure piping 63a connected to the inlet 26a. The second low-pressure water switching valve 28b is provided on the low-pressure piping 63a connected to the outlet 26b. The first high-pressure water switching valve 28c is provided on the high-pressure piping 63b connected to the inlet 26a. The second high-pressure water switching valve 28d is provided on the high-pressure piping 63b connected to the outlet 26b. Note that the arrangement of the water switching valves 28 in this embodiment is illustrative, and the arrangement of the water switching valves 28 may be changed as appropriate, as long as it ensures the function of turning the flow of low-pressure water LW and high-pressure water HW supplied to the recovery device 20 ON and OFF.

[0059] When the low-pressure water switching valves 28a and 28b are set to "open," low-pressure water LW flows into the coil pipe 26 from the inlet 26a. The low-pressure water LW that flows into the coil pipe 26 indirectly cools the CO2 adsorbent 25 in the inner cylinder 23, and then flows out to the outside of the coil pipe 26 from the outlet 26b. This removes the heat generated from the CO2 adsorbent 25 during CO2 adsorption, and maintains the temperature of the CO2 adsorbent 25 at a temperature suitable for CO2 adsorption. When the low-pressure water switching valves 28a and 28b are set to "closed," low-pressure water LW does not flow into the coil pipe 26 from the inlet 26a. The low-pressure water switching valves 28a and 28b are set to "open" when CO2 is adsorbed onto the CO2 adsorbent 25 and to "close" when CO2 is released from the CO2 adsorbent 25.

[0060] When each of the high-pressure water switching valves 28c and 28d is set to "open," high-pressure water HW flows into the coil pipe 26 from the inlet 26a. The high-pressure water HW that flows into the coil pipe 26 indirectly heats the CO2 adsorbent 25 in the inner cylinder 23, and then flows out to the outside of the coil pipe 26 from the outlet 26b. This allows the CO2 adsorbent 25 to be heated when CO2 is released, raising the temperature of the CO2 adsorbent 25 to a temperature at which CO2 can be released. When each of the high-pressure water switching valves 28c and 28d is set to "closed," high-pressure water HW does not flow into the coil pipe 26 from the inlet 26a. Each of the high-pressure water switching valves 28c and 28d is set to "open" when CO2 is released from the CO2 adsorbent 25 and to "close" when CO2 is adsorbed onto the CO2 adsorbent 25.

[0061] (Hair dryer) Figure 4 is a schematic diagram illustrating the dryer. The dryer 30 removes moisture from the exhaust gas EG discharged from the engine 103 into the exhaust gas passage 40. As shown in Figures 2 and 4, the dryer 30 is connected to the engine 103 via the main exhaust gas passage 41. The dryer 30 includes a first dryer 31, which is the first dryer 30, and a second dryer 32, which is the second dryer 30. The first dryer 31 and the second dryer 32 are the same dryer 30.

[0062] The CO2 recovery system 10 uses one of the two dryers 30 to adsorb moisture from the exhaust gas EG. While one dryer 30 is adsorbing moisture, the other dryer 30 releases the moisture. In this explanation, the dryer 30 that adsorbs moisture is referred to as the first dryer 31, and the dryer 30 that releases moisture is referred to as the second dryer 32. In Figure 2, for the sake of explanation, the dryer 30 on the left is labeled as the first dryer 31, and the dryer 30 on the right is labeled as the second dryer 32. However, the dryer 30 on the left also functions as the second dryer 32, and the dryer 30 on the right also functions as the first dryer 31.

[0063] As shown in Figure 4, the dryer 30 has a double-walled structure comprising an inner cylinder 33 and an outer cylinder 34. The dryer 30 further includes a moisture adsorbent 35 filled inside the inner cylinder 33. The moisture adsorbent 35 is a solid medium capable of adsorbing and releasing moisture. In the dryer 30 of this embodiment, the moisture adsorbent 35 includes silica gel 35a and zeolite 35b. In this embodiment, the use of silica gel and zeolite as the moisture adsorbent 35 is illustrated as an example, but the moisture adsorbent used in the CO2 recovery system 10 of this disclosure is not limited to these, and a moisture adsorbent 35 composed of other substances may be used.

[0064] The inner cylinder 33 is a housing for containing the moisture adsorbent 35 and has a first opening 33a and a second opening 33b. The inner cylinder 33 is partitioned by a mesh partition member 33c into three layers: an upper layer 33X, a middle layer 33Y, and a lower layer 33Z. Silica gel 35a is contained in the upper layer 33X and the middle layer 33Y, and zeolite 35b is contained in the lower layer 33Z. The number of compartments inside the inner cylinder 33 is not limited to this; it may consist of one compartment without the partition member 33c, or it may consist of two or more compartments. The first opening 33a is connected to the main exhaust gas passage 41 and the exhaust gas discharge passage 45. The first opening 33a is the inlet for the pre-recovery exhaust gas EG1 and the outlet for the post-recovery exhaust gas EG2. The second opening 33b is connected to the main exhaust gas passage 41 and the regeneration gas passage 43. The second opening 33b serves as the outlet for the pre-recovery exhaust gas EG1 and also as the inlet for the post-recovery exhaust gas EG2.

[0065] The outer cylinder 34 has an inlet 34a and an outlet 34b. The inlet 34a is an opening into which a medium (regeneration gas EG3) for heating the inner cylinder 33 flows into the inside of the outer cylinder 34. The outlet 34b is an opening into which the medium flows out from the inside of the outer cylinder 34. The inlet 34a is connected to the regeneration gas passage 43. The outlet 34b is connected to the waste heat utilization gas passage 44 or the regeneration gas return passage 47, which will be described later.

[0066] The dryer 30 further includes a coiled tube 36. The coiled tube 36 is a coiled piping member located inside the inner cylinder 33 and has an inlet 36a and an outlet 36b. The inlet 36a and outlet 36b are located outside the outer cylinder 34. The inlet 36a is an opening into which a medium for heating the inner cylinder 33 (high-pressure water HW) or a medium for cooling it (low-pressure water LW) flows into the coiled tube 36. The outlet 36b is an opening into which the medium flows out of the coiled tube 36. The inlet 36a and outlet 36b are connected to a low-pressure pipe 63a and a high-pressure pipe 63b, respectively.

[0067] The dryer 30 has a gas switching valve 37. The gas switching valve 37 includes an exhaust gas switching valve 37a and a regeneration gas switching valve 37b. The exhaust gas switching valve 37a is located on the main exhaust gas passage 41 connected to the first opening 33a. The regeneration gas switching valve 37b is located on the regeneration gas passage 43 connected to the inlet 34a. When the exhaust gas switching valve 37a is "open", exhaust gas EG (exhaust gas EG1 before recovery) flows into the inner cylinder 33 from the first opening 33a. When the exhaust gas switching valve 37a is "closed", exhaust gas EG does not flow into the inner cylinder 33 from the first opening 33a. The exhaust gas switching valve 37a is "open" when the dryer 30 adsorbs moisture from the exhaust gas EG, and is "closed" when the moisture is released from the dryer 30.

[0068] When the regeneration gas switching valve 37b is "open", exhaust gas EG (regeneration gas EG3) flows into the outer cylinder 34 from the inlet 34a. When the regeneration gas switching valve 37b is "closed", exhaust gas EG does not flow into the outer cylinder 34 from the inlet 34a. The regeneration gas switching valve 37b is "open" when it releases moisture adsorbed by the dryer 30 to the outside, and is "closed" when the dryer 30 adsorbs moisture.

[0069] The dryer 30 further includes an exhaust gas discharge valve 39. The first opening 33a is also in communication with an exhaust gas discharge passage 45 that branches off from the main exhaust gas passage 41. The exhaust gas discharge valve 39 is located on the exhaust gas discharge passage 45 that is in communication with the first opening 33a. When the exhaust gas discharge valve 39 is "open", moisture released from the moisture adsorbent 35 is discharged from the first opening 33a together with the exhaust gas EG. The exhaust gas discharge valve 39 is "open" when moisture is discharged from the dryer 30 and "closed" when moisture is adsorbed by the dryer 30.

[0070] The dryer 30 further includes a water switching valve 38. The water switching valve 38 includes a low-pressure water switching valve 38a and a high-pressure water switching valve 38b. The low-pressure water switching valve 38a is provided on the low-pressure piping 63a connected to the inlet 36a. The high-pressure water switching valve 38b is provided on the high-pressure piping 63b connected to the inlet 36a. Note that the arrangement of the water switching valve 38 in this embodiment is illustrative, and the arrangement of the water switching valve 38 may be changed as appropriate, as long as it ensures the function of turning the flow of low-pressure water LW and high-pressure water HW supplied to the dryer 30 ON and OFF.

[0071] When the low-pressure water switching valve 38a is set to "open" and the high-pressure water switching valve 38b is set to "closed", low-pressure water LW flows into the coil pipe 36 from the inlet 36a. The low-pressure water LW that flows into the coil pipe 36 indirectly cools the moisture adsorbent 35 in the inner cylinder 33, and then flows out to the outside of the coil pipe 36 from the outlet 36b. This removes the heat generated from the moisture adsorbent 35 during moisture adsorption, and maintains the temperature of the moisture adsorbent 35 at a temperature suitable for moisture adsorption.

[0072] When the high-pressure water switching valve 38b is "open" and the low-pressure water switching valve 38a is "closed", high-pressure water HW flows into the coil pipe 36 from the inlet 36a. The high-pressure water HW that flows into the coil pipe 36 indirectly heats the moisture adsorbent 35 in the inner cylinder 33, and then flows out to the outside of the coil pipe 36 from the outlet 36b. This allows the moisture adsorbent 35 to be heated when moisture is released, raising its temperature to a temperature at which moisture can be released.

[0073] The low-pressure water switching valve 38a opens when moisture is adsorbed onto the moisture adsorbent 35 and closes when moisture is released from the moisture adsorbent 35. The high-pressure water switching valve 38b opens when moisture is released from the moisture adsorbent 35 and closes when moisture is adsorbed onto the moisture adsorbent 35.

[0074] (Control device) Figure 5 is a control block diagram of a CO2 capture system. The CO2 capture system 10 of this disclosure further includes a control device 70, as shown in Figure 5. The control device 70 controls the operation of the CO2 capture system 10. The control device 70 has a microcomputer and performs various controls according to a control program. The control device 70 has a non-volatile memory that stores programs corresponding to the functional units that perform various controls, and a CPU that executes those programs. The functions (controls) of each functional unit are realized when the program is executed by the CPU.

[0075] The control device 70 is connected to the exhaust gas switching valve 27 (first switching valve 27a and second switching valve 27b), water switching valve 28 (first low-pressure water switching valve 28a, second low-pressure water switching valve 28b, first high-pressure water switching valve 28c and second high-pressure water switching valve 28d), CO2 discharge valve 29, gas switching valve 37 (exhaust gas switching valve 37a and regeneration gas switching valve 37b), water switching valve 38 (low-pressure water switching valve 38a and high-pressure water switching valve 38b), and exhaust gas discharge valve 39. The control device 70 switches each of these valves to "open" or "closed" at predetermined timings according to a control program that performs CO2 recovery using the TSA method.

[0076] (Regarding the operation of the recovery device) This section describes the operation of the recovery device 20. The recovery device 20 performs a process for recovering CO2 (hereinafter referred to as the CO2 recovery process X). The CO2 recovery process X includes the "CO2 adsorption process X1" and the "CO2 release process X2".

[0077] (CO2 adsorption process) Figure 6A is a schematic diagram showing the state of the recovery apparatus during CO2 adsorption. Figure 6A shows the first recovery apparatus 21 in the process of performing the CO2 adsorption process X1. While the first recovery apparatus 21 is performing the CO2 adsorption process X1, the second recovery apparatus 22 (see Figure 6B) is performing the CO2 release process X2, which will be explained later.

[0078] As shown in Figure 6A, during the execution of the CO2 adsorption process X1, the first recovery device 21 receives the pre-recovery exhaust gas EG1 from the first opening 23a of the inner cylinder 23. The pre-recovery exhaust gas EG1 that has entered the inner cylinder 23 has its CO2 adsorbed by the CO2 adsorbent 25 inside the inner cylinder 23, becoming the post-recovery exhaust gas EG2, which then flows out from the second opening 23b of the inner cylinder 23.

[0079] During the execution of the CO2 adsorption process X1, the CO2 adsorbent 25 generates heat when adsorbing CO2. As the temperature of the CO2 adsorbent 25 rises, the CO2 adsorption efficiency decreases. For this reason, the first recovery device 21 introduces low-pressure water LW into the coil tube 26 from the inlet 26a, indirectly cooling the CO2 adsorbent 25 in the inner cylinder 23 with the low-pressure water LW. After cooling the CO2 adsorbent 25, the low-pressure water LW flows out from the outlet 26b.

[0080] The first recovery device 21 maintains the temperature of the CO2 adsorbent 25 in the CO2 adsorption process X1 within a temperature range that is efficient for CO2 adsorption by supplying low-pressure water LW to the coil tube 26 to cool the CO2 adsorbent 25.

[0081] (CO2 detachment process) Figure 6B is a schematic diagram showing the state of the recovery device during CO2 detachment. Figure 6B shows the second recovery device 22 in the process of performing the CO2 detachment process X2. While the second recovery device 22 is performing the CO2 detachment process X2, the first recovery device 21 (see Figure 6A) is performing the CO2 adsorption process X1. The CO2 detachment process X2 is a process of detaching CO2 from the CO2 adsorbent 25 and regenerating the CO2 adsorbent 25, and also a process of recovering the CO2 detached from the CO2 adsorbent 25. The CO2 adsorbent 25 regenerated in the CO2 detachment process X2 becomes capable of adsorbing CO2 again.

[0082] When the CO2 adsorbent 25 is heated and its temperature rises, the CO2 adsorbent 25 is released from the CO2 adsorbent 25.

[0083] As shown in Figure 6B, during the execution of the CO2 detachment process X2, the second recovery device 22 receives high-pressure water HW from the inlet 26a of the coil tube 26. The high-pressure water HW that flows into the coil tube 26 indirectly heats the CO2 adsorbent 25 in the inner cylinder 23. The high-pressure water HW then flows out from the outlet 26b of the coil tube 26. At this time, the CO2 that was adsorbed on the CO2 adsorbent 25 is detached from the CO2 adsorbent 25 and released to the outside of the inner cylinder 23 through the first opening 23a. The CO2 recovery system 10 recovers the CO2 discharged to the outside of the inner cylinder 23 into the tank 90 (see Figure 2) via the CO2 discharge passage 46.

[0084] The second recovery device 22 heats the CO2 adsorbent 25 by flowing high-pressure water HW through the coil tube 26, maintaining the temperature of the CO2 adsorbent 25 in the CO2 release process X2 within a temperature range suitable for CO2 release.

[0085] Thus, the CO2 recovery system 10 of this disclosure achieves CO2 recovery by the "TSA method" of "physical adsorption" by changing the temperature of the CO2 adsorbent 25 (raising or lowering the temperature) between the CO2 adsorption process X1 and the CO2 release process X2.

[0086] (moisture removal process) This section describes the operation of the dryer 30. The dryer 30 performs a process to remove moisture contained in the exhaust gas EG (hereinafter referred to as the moisture removal process Y). The moisture removal process Y includes the "moisture adsorption process Y1" and the "moisture release process Y2".

[0087] (moisture adsorption process) Figure 7A is a schematic diagram showing the state of the dryer during moisture adsorption. Figure 7A shows the first dryer 31 performing the moisture adsorption process Y1. While the first dryer 31 is performing the moisture adsorption process Y1, the second dryer 32 (see Figure 7B) is performing the moisture removal process Y2, which will be explained later.

[0088] As shown in Figure 7A, during the execution of the moisture adsorption process Y1, the first dryer 31 receives the pre-recovery exhaust gas EG1 from the first opening 33a of the inner cylinder 33. The pre-recovery exhaust gas EG1 that has entered the inner cylinder 33 has its moisture adsorbed by the moisture adsorbent 35 inside the inner cylinder 33, and then flows out from the second opening 33b of the inner cylinder 33.

[0089] During the execution of the moisture adsorption process Y1, the moisture adsorbent 35 generates heat when adsorbing moisture. As the temperature of the moisture adsorbent 35 rises, the moisture adsorption efficiency decreases. For this reason, the first dryer 31 introduces low-pressure water LW into the coil tube 36 from the inlet 36a, indirectly cooling the moisture adsorbent 35 in the inner cylinder 33 with the low-pressure water LW. After cooling the moisture adsorbent 35, the low-pressure water LW flows out from the outlet 36b.

[0090] The first dryer 31 supplies low-pressure water LW to the coil tube 36 to cool the moisture adsorbent 35, thereby maintaining the temperature of the moisture adsorbent 35 in the moisture adsorption process Y1 within a temperature range that is efficient for moisture adsorption.

[0091] (Moisture removal process) Figure 7B is a schematic diagram showing the state of the dryer during regeneration. Figure 7B shows the second dryer 32 in the process of moisture removal process Y2. Moisture removal process Y2 is a process of removing moisture from the moisture adsorbent 35 and regenerating the moisture adsorbent 35. The moisture adsorbent 35 regenerated in moisture removal process Y2 becomes capable of adsorbing moisture again. While the second dryer 32 is in the process of moisture removal process Y2, the first dryer 31 (see Figure 7A) is performing moisture adsorption process Y1.

[0092] When the moisture adsorbent 35 is heated and its temperature rises, the moisture adsorbent 35 is released from the moisture adsorbent 35. As a result, the moisture adsorbent 35 is regenerated to a state where it can adsorb moisture again.

[0093] As shown in Figure 7B, during the execution of the moisture removal process Y2, the second dryer 32 allows the recovered exhaust gas EG2 to flow in from the second opening 33b of the inner cylinder 33. The recovered exhaust gas EG2 that flows into the inner cylinder 33 comes into direct contact with the moisture adsorbent 35 inside the inner cylinder 33, heating the moisture adsorbent 35. The moisture adsorbent 35 heated by the recovered exhaust gas EG2 releases the adsorbed moisture. The recovered exhaust gas EG2, along with the moisture released from the moisture adsorbent 35, is discharged from the first opening 33a of the inner cylinder 33. The recovered exhaust gas EG2 discharged to the outside of the inner cylinder 33 through the first opening 33a is released into the atmosphere through the exhaust gas discharge passage 45.

[0094] Furthermore, as shown in Figure 7B, during the execution of the moisture removal process Y2, the second dryer 32 introduces regeneration gas EG3 from the inlet 34a of the outer cylinder 34. The regeneration gas EG3 introduced into the outer cylinder 34 indirectly heats the moisture adsorbent 35 in the inner cylinder 33. The regeneration gas EG3 then flows out from the outlet 34b of the outer cylinder 34. By flowing the regeneration gas EG3 into the outer cylinder 34, the second dryer 32 heats the moisture adsorbent 35, bringing the temperature of the moisture adsorbent 35 in the moisture removal process Y2 to a temperature range suitable for moisture removal.

[0095] In the second dryer 32, the moisture adsorbent 35 is heated by the recovered exhaust gas EG2 passing through the inner cylinder 33 and the regeneration gas EG3 passing through the outer cylinder 34, thereby reliably raising its temperature to a range in which moisture can be released.

[0096] Thus, the CO2 recovery system 10 of this disclosure, by having a dryer 30 (first dryer 31 and second dryer 32) configured in this way, can stably supply exhaust gas EG (exhaust gas EG1 before recovery) with moisture removed to the recovery device 20. This makes it possible to stably recover CO2 by the "physical adsorption method".

[0097] As described above, in the CO2 recovery system 10 of this embodiment, the dryer 30 includes a first dryer 31 and a second dryer 32. The first dryer 31 is through which the pre-recovery exhaust gas EG1 passes, and the second dryer 32 is through which the post-recovery exhaust gas EG2 passes. With a CO2 recovery system 10 configured in this way, while the first dryer 31 removes moisture from the pre-recovery exhaust gas EG1, the post-recovery exhaust gas EG2 heats and regenerates the moisture adsorbent 35 in the second dryer 32. This allows the CO2 recovery system 10 mounted on the work machine 100 to be operated stably.

[0098] Furthermore, as described above, in the CO2 recovery system 10 of this embodiment, the exhaust gas EG includes pre-recovery exhaust gas EG1 before CO2 is recovered by the recovery device 20, and post-recovery exhaust gas EG2 after CO2 is recovered by the recovery device 20. The exhaust gas EG returned to the dryer 30 by the regeneration gas passage 43 is the post-recovery exhaust gas EG2. With the CO2 recovery system 10 configured in this way, the heat contained in the post-recovery exhaust gas EG2 can be used to heat and regenerate the moisture adsorbent 35 in the dryer 30. In this case, there is no need to provide a separate heat source for heating the moisture adsorbent 35, and the heat generated from the engine 103 can be effectively utilized when recovering CO2.

[0099] (Regarding variations of the exhaust gas passage) Figure 8 is a block diagram showing a modified example of the CO2 capture system. As shown in Figure 8, in the CO2 capture system 10 of this disclosure, the exhaust gas passage 40 may further include a regeneration gas recirculation passage 47. The regeneration gas recirculation passage 47 is an exhaust gas passage 40 that connects the end of the sub-exhaust gas passage 42 to the main exhaust gas passage 41. The regeneration gas recirculation passage 47 constitutes a path that returns the regeneration gas EG3 to the main exhaust gas passage 41.

[0100] In the configuration shown in Figure 2, the regenerative gas EG3 flowing through the sub-exhaust gas passage 42 is the non-recoverable gas EGB. The non-recoverable gas EGB is exhaust gas EG from which CO2 is not recovered by the recovery device 20, and it contains CO2. Therefore, in the CO2 recovery system 10 with the configuration shown in Figure 2, when the regenerative gas EG3 flowing through the sub-exhaust gas passage 42 is released to the outside, the CO2 contained in the regenerative gas EG3 is also released to the outside. In the CO2 recovery system 10 with the configuration shown in Figure 2, this results in a lower ratio of the amount of CO2 recovered to the total amount of CO2 emitted from the engine 103.

[0101] The CO2 recovery system 10 shown in Figure 8 connects the end (downstream) of the sub-exhaust gas passage 42 to the main exhaust gas passage 41 via a regeneration gas recirculation passage 47. Therefore, in the CO2 recovery system 10 configured as shown in Figure 8, the regeneration gas EG3 flowing through the sub-exhaust gas passage 42 is returned to the main exhaust gas passage 41 via the regeneration gas recirculation passage 47. Thus, in the CO2 recovery system 10 configured as shown in Figure 8, the regeneration gas EG3 passing through the sub-exhaust gas passage 42 becomes the gas to be recovered, EGA. Therefore, with the CO2 recovery system 10 configured as shown in Figure 8, the ratio of the amount of recovered CO2 to the total amount of CO2 emitted from the engine 103 can be increased compared to the CO2 recovery system 10 shown in Figure 2.

[0102] As described above, the CO2 recovery system 10 of the implement 100 (tractor 101) of this embodiment is mounted on a tractor 101 having a vehicle body 102 and an engine 103. The CO2 recovery system 10 includes a main exhaust gas passage 41 connected to the engine 103 and through which exhaust gas EG discharged from the engine 103 passes; a dryer 30 provided in the middle of the main exhaust gas passage 41 and having a moisture adsorbent 35 that adsorbs moisture in the exhaust gas EG; a recovery device 20 connected to the main exhaust gas passage 41 and recovering CO2 from the exhaust gas EG (exhaust gas EG1 before recovery) that has passed through the dryer 30; and a regeneration gas passage 43 connected to the dryer 30 and returning the exhaust gas EG (exhaust gas EG2 after recovery) that has passed through the recovery device 20 to the dryer 30.

[0103] With a CO2 recovery system 10 configured in this way, the heat contained in the exhaust gas EG (recovered exhaust gas EG2) can be used to heat and regenerate the moisture adsorbent 35 in the dryer 30. In this case, there is no need to provide a separate heat source for heating the moisture adsorbent 35, and the heat generated by the combustion of fuel can be effectively utilized. With this configuration, the CO2 recovery system 10 mounted on the work machine 100 can effectively utilize the heat generated from the engine 103 when recovering CO2.

[0104] The embodiments described above are illustrative and not restrictive in all respects. The scope of the present invention is indicated by the claims rather than by the embodiments, and includes all modifications within the scope equivalent to the configurations described in the claims. [Explanation of symbols]

[0105] 10 CO2 Capture Systems 20 Recovery device 25 CO2 adsorbent 30 Hair Dryer 31. First Dryer 32. Second Dryer 35. Moisture absorbent 40 Exhaust gas passage 41 Main exhaust gas passage 42 Sub-exhaust gas passage 43 Regeneration gas passage 51 Heating heat exchanger 52 Cooling heat exchanger 53 Heat exchanger for reheating 100 work machines 101 Tractor (implementation equipment) 102 Vehicle body 103 Engine EG exhaust gas EG1 Exhaust gas before recovery EG2 Exhaust gas after recovery EG3 Regenerative Gas

Claims

1. CO2 is installed on the vehicle body and the work machine having an engine. ２ It is a collection system, A main exhaust gas passage connected to the engine and through which exhaust gas discharged from the engine passes, A dryer provided in the middle of the main exhaust gas passage and having a moisture adsorbent that adsorbs moisture in the exhaust gas, CO in the exhaust gas that is connected to the main exhaust gas passage and has passed through the dryer ２ A recovery device for recovering and A regenerative gas passage connected to the dryer and which returns the exhaust gas that has passed through the recovery device back to the dryer, CO of the work machine ２ Collection system.

2. The exhaust gas is recovered by the CO2 recovery device. ２ The exhaust gas before recovery and the CO2 recovered by the recovery device ２ Includes the post-recovery exhaust gas after recovery, The CO2 from the work machine according to claim 1, wherein the exhaust gas returned to the dryer by the regeneration gas passage is the recovered exhaust gas. ２ Collection system.

3. CO2 emissions from the work machine according to claim 1 or 2, further comprising a heating heat exchanger provided in the main exhaust gas passage between the engine and the dryer, for recovering heat from the exhaust gas. ２ Collection system.

4. CO2, the CO2 of the work machine according to claim 3, further comprising a cooling heat exchanger provided in the main exhaust gas passage between the heating heat exchanger and the dryer, and for cooling the exhaust gas. ２ Collection system.

5. The CO recovery system of the work machine according to claim 1 or claim 2, further comprising a reheating heat exchanger provided in the regeneration gas passage and reheating the exhaust gas. ２ recovery system.

6. The dryer includes a first dryer and a second dryer, The first dryer through which the exhaust gas before recovery passes, The second dryer is through which the recovered exhaust gas passes, and the CO2 from the work machine described in claim 2. ２ Collection system.

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