Exhaust gas purification system and tractor

Abstract

Provided is an exhaust gas purification system with which the vertical dimension of an absorption part can be reduced.　This exhaust gas purification system includes an absorption part 510A that causes carbon dioxide and nitrogen oxide contained in exhaust gas to be absorbed in an absorption liquid, and a regeneration part 503 that recovers carbon dioxide from the absorption liquid supplied from the absorption part 510A and supplies the absorption liquid back to the absorption part. The absorption part 510A includes a cylindrical casing 511 formed such that the diameter D is 1 / 2 or more of the total height H, and a nozzle 512 for spraying the absorption liquid inside the casing 511.

Description

Exhaust gas purification system and tractor

[0001] The present invention relates to an exhaust gas purification system and a tractor equipped with the same.

[0002] Conventionally, technology for an exhaust gas purification system for purifying exhaust gas has been publicly known, as described in, for example, Japanese Patent Application Laid-Open No. 2003-222999.

[0003] Patent Document 1 describes an exhaust gas purification system including an absorption unit that causes an absorption liquid to absorb carbon dioxide contained in exhaust gas, and an absorption liquid regeneration unit that separates carbon dioxide from the absorption liquid that has absorbed the carbon dioxide and returns it to the absorption unit. By using such an exhaust gas purification system, it is possible to absorb carbon dioxide contained in exhaust gas emitted from, for example, an engine, and purify the exhaust gas.

[0004] By installing such an exhaust gas purification system in a tractor, it is expected that the exhaust gas emitted from the tractor's engine will be purified.

[0005] Generally, the absorption section of the exhaust gas purification system as described above is formed in a vertically long shape to ensure contact between the exhaust gas and the absorption liquid.

[0006] However, when an exhaust gas purification system is installed on a tractor, the vertical dimensions of the absorption section must be reduced because the installation space for the exhaust gas purification system is limited.

[0007] Japanese Patent Application Laid-Open No. 2019-217492

[0008] One aspect of the present disclosure has been made in consideration of the above-described circumstances, and the problem it aims to solve is to provide an exhaust gas purification system that enables the vertical dimensions of the absorption section to be reduced, and a tractor equipped with the same.

[0009] The problem to be solved by the present invention is as described above, and the means for solving this problem will now be described.

[0010] An exhaust gas purification system according to one aspect of the present disclosure includes an absorption unit that absorbs carbon dioxide and nitrogen oxides contained in exhaust gas into an absorption liquid, and a regeneration unit that recovers carbon dioxide from the absorption liquid supplied from the absorption unit and supplies the absorption liquid back to the absorption unit, wherein the absorption unit includes a cylindrical housing whose diameter is at least half of the overall height, and a spray unit that sprays the absorption liquid inside the housing. According to this aspect of the present disclosure, the vertical dimensions of the absorption unit can be reduced.

[0011] In addition, the housing is formed so that the diameter is three times or more the total height. According to one aspect of the present disclosure, it is possible to reduce the vertical dimension of the absorbing section.

[0012] According to another aspect of the present disclosure, a tractor includes the exhaust gas purification system. According to this aspect of the present disclosure, the vertical dimension of the absorption section can be reduced, and therefore the size of the tractor can be reduced.

[0013] According to one aspect of the present disclosure, the vertical dimensions of the absorbing section can be reduced.

[0014] Schematic diagram showing the configuration of a physical adsorption type exhaust gas purification system. Schematic diagram showing the configuration of a chemical absorption type exhaust gas purification system. Schematic side cross-sectional diagram showing the configuration of an absorption unit. (a) Schematic side cross-sectional diagram showing the configuration of an absorption unit according to a first modified example. (b) Schematic plan cross-sectional diagram showing the casing of an absorption unit according to the first modified example. Schematic side cross-sectional diagram showing the configuration of an absorption unit according to a second modified example. Schematic side cross-sectional diagram showing the configuration of an absorption unit according to a third modified example. (a) Schematic diagram showing a tractor according to the first modified example. (b) Schematic diagram showing a tractor according to the second modified example. Schematic side view showing a tractor according to the third modified example. (a) Schematic diagram showing a tractor according to the fourth modified example. (b) Schematic diagram showing a tractor according to the fifth modified example.

[0015] An example of an exhaust gas purification system mounted on a tractor 600 (see FIG. 7 etc.) will be described below. Specifically, as examples of the exhaust gas purification system, a physical adsorption type exhaust gas purification system 4 and a chemical absorption type exhaust gas purification system 5 will be described in this order.

[0016] First, with reference to FIG. 1, an embodiment of a physical adsorption type exhaust gas purification system 4 will be described.

[0017] The exhaust gas purification system 4 is configured to purify carbon dioxide (CO ２ In this embodiment, an exhaust gas purification system 4 that purifies exhaust gas emitted from an engine E will be described as an example. The exhaust gas purification system 4 mainly includes an adsorption / desorption section 310, a cooling section 320, an auxiliary cooling section 330, a storage section 340, a heating device 350, a control section 360, and the like.

[0018] The adsorption / desorption unit 310 adsorbs carbon dioxide (CO ２ The adsorption / desorption section 310 is provided with a zeolite-based adsorbent such as Cu-ZSM-5. Zeolite-based adsorbents are porous materials, and the size of the pores affects their ability to absorb carbon dioxide, as described below. In addition, the metal supported by the zeolite-based adsorbent affects its ability as an SCR catalyst, as described below.

[0019] Note that Figure 1 illustrates the adsorption / desorption section 310 (adsorption / desorption section 310A on the upper and left side in the figure) in a state where it is heated by the waste heat of the exhaust gas supplied by the first cooling section 321, the adsorption / desorption section 310 (adsorption / desorption section 310B on the lower and right side in the figure) in a state where it is cooled by the refrigerant of the second cooling section 322, the adsorption / desorption section 310A (adsorption / desorption section 310C on the upper and right side in the figure), and the adsorption / desorption section 310 (adsorption / desorption section 310D) in a state where it is cooled (pre-cooled) by the refrigerant of the second cooling section 322, the exhaust gas that has passed through the adsorption / desorption section 310B, and the outside air supplied by the fifth cooling section 325 described later.

[0020] As described above, the exhaust gas purification system 4 according to this embodiment includes multiple (four) adsorption / desorption units 310. For example, while one adsorption / desorption unit 310A is being heated, another adsorption / desorption unit 310C is being preheated, and while another adsorption / desorption unit 310B is adsorbing carbon dioxide or the like, another adsorption / desorption unit 310D is being precooled. Thus, the processes performed by each adsorption / desorption unit 310 can be performed in parallel. Furthermore, by appropriately switching the flow paths of the exhaust gas, refrigerant, and the like, the state of each adsorption / desorption unit 310 (adsorption / desorption units 310A-310D) can be arbitrarily switched. For example, each adsorption / desorption unit 310 can be switched sequentially between a state in which carbon dioxide or the like is adsorbed (adsorption / desorption unit 310B), a preheated state (adsorption / desorption unit 310C), a heated state in which carbon dioxide is desorbed (adsorption / desorption unit 310A), and a precooled state (adsorption / desorption unit 310D). By sequentially switching the state of each adsorption / desorption section 310 in this manner, it is possible to sequentially perform adsorption and desorption of carbon dioxide and the like, reduction of nitrogen oxides, and the like in each adsorption / desorption section 310.

[0021] In addition to the above four states, when reducing nitrogen oxides adsorbed in the adsorption / desorption unit 310, the adsorption / desorption unit 310 can be temporarily heated to a temperature higher than that in the state where carbon dioxide is desorbed (adsorption / desorption unit 310A). By supplying a reducing agent together with exhaust gas to the adsorption / desorption unit 310 in this state (adsorption / desorption unit 310B in this embodiment), the nitrogen oxides adsorbed in the adsorption / desorption unit 310 can be reduced.

[0022] Specifically, exhaust gas from the engine E is guided to the adsorption / desorption unit 310 (adsorption / desorption unit 310B) via a path L11 formed by piping or the like. A reducing agent can be injected from an injector 311 into the exhaust gas supplied to the adsorption / desorption unit 310B via the path L11. Urea or hydrocarbons can be used as the reducing agent. For example, when urea is used as the reducing agent, urea water stored in a tank can be injected by the injector 311. The injected urea water is thermally decomposed by waste heat from the exhaust gas, generating ammonia. This ammonia acts as the reducing agent. When hydrocarbons are used as the reducing agent, hydrocarbons generated by decomposition of diesel fuel can be used. The exhaust gas, whose temperature has been reduced after passing through the adsorption / desorption unit 310B, is supplied to the adsorption / desorption unit 310D via a path L12, thereby cooling the adsorption / desorption unit 310D. The exhaust gas that has cooled the adsorption / desorption unit 310D is then discharged to the outside via a path L13.

[0023] The cooling section 320 uses a refrigerant to cool the exhaust gas and each section of the exhaust gas purification system 4. The cooling section 320 mainly includes a first cooling section 321, a second cooling section 322, a third cooling section 323, a fourth cooling section 324, and a fifth cooling section 325. Note that the first cooling section 321 and the third cooling section 323, and the second cooling section 322 and the fourth cooling section 324 share some of the same refrigerant flow paths. This will be explained in detail below.

[0024] The first cooling unit 321 uses a refrigerant to cool the exhaust gas discharged from the engine E, and also uses waste heat from the exhaust gas to heat the adsorption / desorption unit 310. As the refrigerant, for example, a liquid-phase fluid with a relatively large heat capacity (e.g., cooling water or oil) can be used. The first cooling unit 321 mainly includes a circulation path L21, a heat exchanger 321a, a radiator 321b, a pump 321c, and a heat exchanger 321d.

[0025] The circulation path L21 is configured by piping or the like, and allows a refrigerant to flow through it. The circulation path L21 is formed to sequentially connect the heat exchanger 321a, the adsorption / desorption unit 310A, the adsorption / desorption unit 310C, the heat exchanger 321d, the radiator 321b, and the pump 321c.

[0026] The heat exchanger 321a is provided midway along the path L11. The heat exchanger 321a exchanges heat between the exhaust gas discharged from the engine E and the refrigerant, thereby lowering the temperature of the exhaust gas. The refrigerant that has received the heat of the exhaust gas in the heat exchanger 321a is supplied to the adsorption / desorption unit 310 (adsorption / desorption unit 310A). This allows the adsorption / desorption unit 310A to be heated. By heating the adsorption / desorption unit 310A, the carbon dioxide adsorbed in the adsorption / desorption unit 310A can be desorbed.

[0027] The refrigerant that has passed through adsorption / desorption unit 310A is further supplied to adsorption / desorption unit 310C. This allows adsorption / desorption unit 310C to be preheated. The preheated adsorption / desorption unit 310C is later switched to adsorption / desorption unit 310A by switching the flow path of the refrigerant, etc. The refrigerant that has passed through adsorption / desorption unit 310C is cooled in heat exchanger 321d.

[0028] Water from a reservoir 321e capable of storing water is supplied to the heat exchanger 321d as needed by a pump (not shown). In the heat exchanger 321d, heat is exchanged between the water supplied from the reservoir 321e and the refrigerant that has passed through the adsorption / desorption unit 310C, thereby cooling the refrigerant. The water stored in the reservoir 321e is condensed water generated in the heat exchanger 321a that exchanges heat with the exhaust gas and in the heat exchanger 323a of the third cooling unit 323, which will be described later.

[0029] The refrigerant that has passed through the heat exchanger 321d is further dissipated in the radiator 321b and then supplied to the pump 321c, which supplies the refrigerant to the heat exchanger 321a again.

[0030] In this way, the first cooling section 321 can cool the exhaust gas by circulating the refrigerant, and can also heat the adsorption / desorption section 310 by utilizing the waste heat of the exhaust gas.

[0031] The second cooling section 322 uses a refrigerant to cool the adsorption / desorption section 310B and the adsorption / desorption section 310D. The second cooling section 322 mainly includes a circulation path L22, a radiator 322a, a pump 322b, and the like.

[0032] The circulation path L22 is composed of piping or the like and allows a refrigerant to flow through it. The circulation path L22 is formed to sequentially connect the adsorption / desorption unit 310B, the adsorption / desorption unit 310D, the radiator 322a, the auxiliary cooling unit 330, and the pump 322b. The circulation path L22 is formed independently of the circulation path L21 of the first cooling unit 321. That is, the refrigerant used in the circulation path L21 (first cooling unit 321) and the refrigerant used in the circulation path L22 (second cooling unit 322) are independent of each other and are not mixed. The circulation path L22 branches at a branch point P3 provided upstream of the adsorption / desorption unit 310B and the adsorption / desorption unit 310D, and is connected to the adsorption / desorption unit 310B and the adsorption / desorption unit 310D, respectively. The circulation path L21 branched off at the branch point P3 merges again at a branch point P4 provided downstream of the adsorption / desorption section 310B and the adsorption / desorption section 310D.

[0033] In the second cooling section 322, the refrigerant pumped from the pump 322b is supplied to the adsorption / desorption section 310B and the adsorption / desorption section 310D via branch sections P6 and P3. This allows the adsorption / desorption section 310B and the adsorption / desorption section 310D to be cooled. The refrigerant that has passed through the adsorption / desorption section 310B and the adsorption / desorption section 310D is supplied to the radiator 322a via branch section P4. The refrigerant, whose temperature has increased due to the heat from the adsorption / desorption section 310B and the adsorption / desorption section 310D, dissipates heat in the radiator 322a and is then supplied to the pump 322b via the auxiliary cooling section 330. The refrigerant supplied to the pump 322b is again supplied to the adsorption / desorption section 310B and the adsorption / desorption section 310D by the pump 322b.

[0034] In this way, the second cooling section 322 can cool the adsorption / desorption section 310B and the adsorption / desorption section 310D by circulating the refrigerant.

[0035] The third cooling section 323 uses a refrigerant to cool carbon dioxide to be supplied to the storage section 340, which will be described later. The third cooling section 323 mainly includes a circulation path L23, a heat exchanger 323a, a radiator 321b, a pump 321c, and a heat exchanger 321d. The third cooling section 323 uses the same refrigerant as the first cooling section 321. The third cooling section 323 also uses the radiator 321b, pump 321c, and heat exchanger 321d that are also used in the first cooling section 321.

[0036] The circulation path L23 is configured with piping or the like, and allows a refrigerant to flow through it. The circulation path L23 is formed to sequentially connect the heat exchanger 323a, the heat exchanger 321d, the radiator 321b, and the pump 321c. The circulation path L23 is formed to branch off from a branch point P1 formed on the circulation path L21 downstream of the pump 321c, and from a branch point P2 formed on the circulation path L21 between the adsorption / desorption unit 310C and the heat exchanger 321d. In this way, a portion of the circulation path L21 of the first cooling section 321 (the portion from the branch point P2 to the branch point P1) forms a portion of the circulation path L23 of the third cooling section 323.

[0037] The heat exchanger 323a is provided midway along the circulation path L22 (downstream of the branch point P1). The heat exchanger 323a exchanges heat between the carbon dioxide supplied to the storage section 340 (described later) and the refrigerant circulating through the circulation path L23, thereby lowering the temperature of the carbon dioxide. The refrigerant that has received heat from the carbon dioxide in the heat exchanger 323a is cooled in the heat exchanger 321d, dissipates heat in the radiator 321b, and is then supplied to the pump 321c. The refrigerant supplied to the pump 321c is then supplied again to the heat exchanger 323a by the pump 321c.

[0038] In this way, the third cooling section 323 can cool the carbon dioxide supplied to the storage section 340 by circulating the same refrigerant as the first cooling section 321 .

[0039] The fourth cooling section 324 uses a refrigerant to further cool the exhaust gas cooled by the first cooling section 321. The fourth cooling section 324 mainly includes a circulation path L24, a heat exchanger 324a, a radiator 322a, and a pump 322b. The fourth cooling section 324 uses the same refrigerant as the second cooling section 322. The fourth cooling section 324 also uses the same radiator 322a and pump 322b as the second cooling section 322.

[0040] The circulation path L24 is configured with piping or the like and allows a refrigerant to flow through it. The circulation path L24 is formed to sequentially connect the radiator 322a, the auxiliary cooling unit 330, the pump 322b, and the heat exchanger 324a. The circulation path L24 is formed to branch off from a branch point P6 formed downstream of the pump 322b in the circulation path L22 and a branch point P5 formed between the adsorption / desorption unit 310B and the branch point P4 in the circulation path L22. In this way, a portion of the circulation path L22 of the second cooling unit 322 (the portion from the branch point P5 through the branch point P4, the radiator 322a, and the pump 322b to the branch point P6) forms a portion of the circulation path L24 of the fourth cooling unit 324.

[0041] The heat exchanger 324a is provided midway along the circulation path L24 (downstream of the branch point P6). The heat exchanger 324a exchanges heat between the refrigerant and the exhaust gas that has been cooled by the heat exchanger 321a of the first cooling unit 321 and is flowing through the path L11, thereby further lowering the temperature of the exhaust gas. The refrigerant that has received the heat of the exhaust gas in the heat exchanger 324a is dissipated in the radiator 322a and then supplied to the pump 322b via the auxiliary cooling unit 330. The refrigerant supplied to the pump 322b is then supplied again to the heat exchanger 324a by the pump 322b.

[0042] In this way, the fourth cooling section 324 can further cool the exhaust gas by circulating the refrigerant.

[0043] The fifth cooling unit 325 is for cooling the adsorption / desorption unit 310D using gas (air in this embodiment), and is mainly equipped with a path L25, a pump 325a, and the like.

[0044] The path L25 is configured by a pipe or the like and allows gas to flow through it. The path L25 is formed to sequentially connect the pump 325a and the adsorption / desorption unit 310D. The upstream end of the path L25 is open to the outside space, allowing external air (fresh air) to be introduced.

[0045] Air introduced from the outside by the pump 325a flows through the adsorption / desorption section 310D and is released to the outside. At this time, the air passing through the adsorption / desorption section 310D can cool the adsorption / desorption section 310D.

[0046] The auxiliary cooling unit 330 is used to auxiliary cool the refrigerant used in the cooling unit 320 (particularly the second cooling unit 322 and the fourth cooling unit 324). The auxiliary cooling unit 330 is a refrigeration cycle that performs cooling by changing the phase of an appropriate refrigerant (such as carbon dioxide). The auxiliary cooling unit 330 mainly includes a heat exchanger 331, a compressor 332, a condenser 333, an expansion valve 334, etc.

[0047] The heat exchanger 331 is disposed on the refrigerant circulation path (circulation path L22, circulation path L24) between the radiator 322a and the pump 322b. The heat exchanger 331 exchanges heat with the refrigerant circulating through the path, and can further lower the temperature of the refrigerant cooled by the radiator 322a. The refrigerant, such as carbon dioxide, used for heat exchange in the heat exchanger 331 is compressed by the compressor 332 and then dissipates heat in the condenser 333. The refrigerant that has dissipated heat in the condenser 333 can be supplied again to the heat exchanger 331 via the expansion valve 334.

[0048] For example, if the cooling capacity of the second cooling section 322 and the fourth cooling section 324 is insufficient with the radiator 322a alone (such as when it is necessary to cool the exhaust gas from the engine E to a temperature lower than the outside air temperature), the auxiliary cooling section 330 configured as described above can be operated to further cool the refrigerant in the second cooling section 322 and the fourth cooling section 324, thereby improving the cooling capacity.

[0049] The storage section 340 stores the carbon dioxide desorbed from the adsorption / desorption section 310A. The storage section 340 is connected to the adsorption / desorption section 310A via a path L14 formed of piping or the like. A compressor 341 and a heat exchanger 323a are provided midway along the path L14. The carbon dioxide desorbed from the adsorption / desorption section 310A is compressed by the compressor 341, has heat dissipated in the heat exchanger 323a, and is stored in the storage section 340.

[0050] The heating device 350 is a device for heating the adsorption / desorption unit 310. The heating device 350 can be configured using, for example, an electric heating wire. The temperature of the adsorption / desorption unit 310 can be detected by a temperature sensor 351. By controlling the operation of the heating device 350 and the like while detecting the temperature of the adsorption / desorption unit 310 with the temperature sensor 351, the temperature of the adsorption / desorption unit 310 can be adjusted to any desired temperature.

[0051] The control unit 360 controls the operation of the exhaust gas purification system 4. The control unit 360 is configured with an arithmetic processing unit such as a CPU, and storage devices such as a RAM, a ROM, and an HDD. The control unit 360 can receive the detection results of the temperature sensor 351. The control unit 360 can also control the heating device 350. However, the control unit 360 is not limited to this and can also control the operation of each part of the exhaust gas purification system 4.

[0052] Although detailed explanation is omitted, the flow path of the fluid in the exhaust gas purification system 4 (for example, carbon dioxide adsorbed and desorbed in the adsorption / desorption section 310) can be switched arbitrarily using a switching device (piping, switching valve, etc.) not shown.

[0053] The exhaust gas purification system 4 configured in this manner can purify carbon dioxide and nitrogen oxides contained in the exhaust gas emitted from the engine E. A specific description will be given below.

[0054] First, the purification of carbon dioxide and nitrogen oxides contained in exhaust gas will be described.

[0055] In this case, the exhaust gas emitted from the engine E is cooled to a predetermined first temperature T1 (for example, approximately the outside air temperature (25°C)) by the first cooling section 321 and the fourth cooling section 324 while flowing through the path L11. The cooled exhaust gas is supplied to the adsorption / desorption section 310B, where the carbon dioxide and nitrogen oxides in the exhaust gas are adsorbed by the adsorbent. In this way, by cooling the exhaust gas supplied to the adsorption / desorption section 310B by the first cooling section 321 and the fourth cooling section 324, the carbon dioxide and nitrogen oxides in the exhaust gas can be efficiently adsorbed.

[0056] If further cooling of the exhaust gas is required (if the exhaust gas temperature needs to be lowered below the outside air temperature), the auxiliary cooling unit 330 is activated. When the auxiliary cooling unit 330 is activated, the refrigeration cycle of the auxiliary cooling unit 330 lowers the temperature of the refrigerant in the fourth cooling unit 324, making it possible to cool the exhaust gas to an even lower temperature. For example, by cooling the exhaust gas to around 0 degrees, it is also possible to effectively remove moisture from the exhaust gas.

[0057] The exhaust gas from which carbon dioxide and nitrogen oxides have been adsorbed in the adsorption / desorption unit 310B is supplied to the adsorption / desorption unit 310D via path L12. This allows the adsorption / desorption unit 310D to be cooled using the exhaust gas that has been cooled while flowing through the adsorption / desorption unit 310B. In this way, in this embodiment, the adsorption / desorption unit 310D can be cooled (pre-cooled) using the exhaust gas that has flowed through the adsorption / desorption unit 310B, in addition to the second cooling unit 322 and the fifth cooling unit 325. This allows the power consumption of the second cooling unit 322 and the fifth cooling unit 325 to be reduced. The exhaust gas that has passed through the adsorption / desorption unit 310D is discharged to the outside via path L13.

[0058] Next, the case where carbon dioxide adsorbed in the adsorption / desorption unit 310 is desorbed will be described.

[0059] In this case, waste heat from the exhaust gas recovered by the heat exchanger 321a of the first cooling unit 321 is supplied to the adsorption / desorption unit 310A via the refrigerant, and the adsorption / desorption unit 310A is heated to a temperature higher than the first temperature T1. The adsorption / desorption unit 310A is heated to a predetermined second temperature T2 (for example, approximately 150 degrees) at which carbon dioxide can be desorbed. At this time, the adsorption / desorption unit 310 can also be heated using a heating device 350. This causes carbon dioxide to be desorbed from the adsorption / desorption unit 310A. The carbon dioxide released from the adsorption / desorption unit 310A is stored in the storage unit 340 via path L14.

[0060] Next, the reduction of nitrogen oxides adsorbed in the adsorption / desorption section 310 will be described.

[0061] In this case, the adsorption / desorption unit 310B is heated to a temperature even higher than the second temperature T2 when desorbing carbon dioxide. The adsorption / desorption unit 310 is heated to a predetermined third temperature T3 (for example, approximately 400°C) at which the adsorption / desorption unit 310 can function as an SCR catalyst. For this heating, waste heat from the exhaust gas recovered by the heat exchanger 321a of the first cooling unit 321 is first used. This waste heat can be used to heat the adsorption / desorption unit 310A and the adsorption / desorption unit 310C. If this waste heat is not sufficient, the heating device 350 is activated to heat the adsorption / desorption unit 310 to the target temperature. The heated adsorption / desorption unit 310A and the adsorption / desorption unit 310C are switched to the adsorption / desorption unit 310B.

[0062] A reducing agent is sprayed onto the exhaust gas supplied to the adsorption / desorption unit 310B via path L11. As the exhaust gas passes through the adsorption / desorption unit 310B, the nitrogen oxides adsorbed in the adsorption / desorption unit 310B are reduced. The exhaust gas that has passed through the adsorption / desorption unit 310B is discharged to the outside via paths L12 and L13.

[0063] The temperature of the adsorption / desorption unit 310 and the fluid flow paths of each unit as described above can be switched by the control unit 360. By switching the temperature of the adsorption / desorption unit 310 to any one of the first temperature T1, second temperature T2, and third temperature T3 by the control unit 360 and appropriately injecting a reducing agent from the injection device 311, it is possible to adsorb carbon dioxide and nitrogen oxides, desorb carbon dioxide, and reduce nitrogen oxides using the common adsorption / desorption unit 310. This eliminates the need to provide separate purification devices for purifying carbon dioxide and for purifying nitrogen oxides, thereby simplifying the configuration of the exhaust gas purification system 4.

[0064] In addition, in this embodiment, the exhaust gas, the adsorption / desorption unit 310, etc. are cooled by a plurality of cooling units (the first cooling unit 321 and the third cooling unit 323, and the second cooling unit 322 and the fourth cooling unit 324) having mutually independent paths. This prevents, for example, refrigerant that has become hot in one cooling unit from mixing with the path of the other cooling unit and reducing the cooling capacity of that cooling unit, thereby reducing the power consumption for cooling.

[0065] In this embodiment, the exhaust gas and the adsorption / desorption unit 310 are cooled by the cooling unit 320, which mainly uses a liquid-phase refrigerant. This makes it possible to reduce the use of equipment that consumes a lot of power (such as a compressor). In this embodiment, the fifth cooling unit 325 is configured to cool the adsorption / desorption unit 310 using outside air. This makes it possible to further reduce power consumption. Furthermore, if the cooling capacity is insufficient, the auxiliary cooling unit 330 can be used to temporarily improve the cooling capacity.

[0066] Although the physical adsorption type exhaust gas purification system 4 has been described above, the present invention is not limited to the above configuration and various modifications are possible.

[0067] For example, as described above, it is possible to provide a plurality of adsorption / desorption sections 310, and configure the system so that some of the adsorption / desorption sections 310 adsorb carbon dioxide and the like, and simultaneously desorb carbon dioxide in other adsorption / desorption sections 310. With this configuration, exhaust gas can be purified efficiently.

[0068] Furthermore, in the above embodiment, an example has been shown in which four adsorption / desorption units 310 are used, but the present invention is not limited to this, and it is possible to arbitrarily change the number of adsorption / desorption units 310. For example, it is also possible to configure the exhaust gas purification system 4 using a single adsorption / desorption unit 310.

[0069] Furthermore, the first temperature T1, the second temperature T2, and the third temperature T3 described in the above embodiment are not particularly limited, and can be changed appropriately depending on the processing content.

[0070] In addition, in the above embodiment, an example has been shown in which the cooling section 320 includes the first cooling section 321, the second cooling section 322, the third cooling section 323, the fourth cooling section 324, and the fifth cooling section 325. However, the present invention is not limited to this, and it is possible to arbitrarily change the configuration of the cooling section 320. For example, if the exhaust gas can be sufficiently cooled by the first cooling section 321, it is also possible to adopt a configuration in which the fourth cooling section 324 that cools the exhaust gas downstream of the first cooling section 321 is not provided.

[0071] In the above embodiment, the path of the third cooling section 323 that cools the desorbed carbon dioxide is partially shared with the first cooling section 321, thereby using a common refrigerant for the first cooling section 321 and the third cooling section 323. However, the present invention is not limited to this. For example, the path of the third cooling section 323 may be partially shared with the path of the second cooling section 322 rather than the first cooling section 321, or may be configured independently from the other cooling sections (such as the first cooling section 321 and the second cooling section 322). Similarly, the path of the fourth cooling section 324 does not necessarily have to be partially shared with the second cooling section 322.

[0072] In addition, in the above embodiment, an example has been shown in which the exhaust gas that has passed through the adsorption / desorption section 310B is used to cool (pre-cool) the adsorption / desorption section 310D, but the present invention is not limited to this, and it is sufficient that the exhaust gas that has passed through one adsorption / desorption section 310 is used to adjust the temperature of the other adsorption / desorption section 310. For example, it is also possible to use the exhaust gas to heat the other adsorption / desorption section 310 instead of cooling it.

[0073] In the above embodiment, the two adsorption / desorption units 310 (the adsorption / desorption unit 310A and the adsorption / desorption unit 310C) to be heated are connected in series by the circulation path L21, but the present invention is not limited to this. That is, the adsorption / desorption unit 310A and the adsorption / desorption unit 310C can also be connected in parallel using a branched path.

[0074] In the above embodiment, the two adsorption / desorption units 310 (adsorption / desorption unit 310B and adsorption / desorption unit 310D) to be cooled are connected in parallel by a branched circulation path L21, but the present invention is not limited to this. That is, the adsorption / desorption unit 310B and the adsorption / desorption unit 310D can also be connected in series using a path that does not branch.

[0075] In this way, the multiple adsorption / desorption units 310 can be connected in series or in parallel. Alternatively, a configuration may be adopted in which the series and parallel connections can be arbitrarily switched using a switching mechanism (such as a switching valve) that can switch the refrigerant flow path. The series and parallel connections can be switched, for example, depending on the required cooling capacity. Furthermore, for example, when multiple adsorption / desorption units 310 are connected in series, the pump capacity required to send the same volume of refrigerant to the adsorption / desorption units 310 can be reduced compared to when multiple adsorption / desorption units 310 are connected in parallel, thereby reducing power consumption. This also allows for the miniaturization and simplification of pumps and paths (piping, etc.), thereby saving space.

[0076] Next, an embodiment of the chemical absorption type exhaust gas purification system 5 will be described with reference to FIG.

[0077] The exhaust gas purification system 5 is configured to purify carbon dioxide (CO ２In this embodiment, an exhaust gas purification system 5 that purifies exhaust gas emitted from an engine E will be described as an example. The exhaust gas purification system 5 mainly includes an absorption section 510, a regeneration section 503, a storage section 504, an oxidation catalyst 505, an absorption liquid sensor 506, a carbon dioxide sensor 507, a nitrogen oxide sensor 508, a control section 509, etc.

[0078] The absorption unit 510 is for absorbing carbon dioxide and nitrogen oxides. A guide path L501 (piping, etc.) that guides exhaust gas from the engine E is connected to the absorption unit 510. A hollow housing (absorption chamber) is provided in the absorption unit 510, and an absorption liquid that is circulated between the absorption unit 510 and the regeneration unit 503, which will be described later, is sprayed inside the housing. By bringing the exhaust gas supplied to the absorption unit 510 into contact with the sprayed absorption liquid, the carbon dioxide and nitrogen oxides contained in the exhaust gas can be absorbed by the absorption liquid. The exhaust gas from which the carbon dioxide and nitrogen oxides have been absorbed (purified) in the absorption unit 510 is discharged to the outside via an appropriate discharge path L502 (piping, etc.).

[0079] The absorbing liquid may be, for example, an organic aqueous solution of amine or the like, or an inorganic aqueous solution (alkaline aqueous solution) of potassium bicarbonate or sodium bicarbonate. By using such an absorbing liquid, carbon dioxide in the exhaust gas is selectively absorbed by the absorbing liquid. Nitrogen oxides in the exhaust gas are also absorbed by the absorbing liquid as they are converted into nitric acid compounds by a reduction reaction.

[0080] An appropriate circulation path L503 (piping or the like) is formed between the absorption section 510 and the regeneration section 503 described below, and the absorbing liquid can be circulated between the absorption section 510 and the regeneration section 503.

[0081] The regeneration unit 503 regenerates the absorbing solution that has absorbed carbon dioxide. The regeneration unit 503 is provided with a hollow housing (regeneration chamber), and the absorbing solution supplied from the absorption unit 510 is sprayed into the housing. The regeneration unit 503 heats the sprayed absorbing solution, thereby separating carbon dioxide from the absorbing solution. The absorbing solution from which the carbon dioxide has been separated is supplied again to the absorption unit 510.

[0082] The storage section 504 stores the carbon dioxide separated in the regeneration section 503. The storage section 504 is connected to the regeneration section 503, and can store the carbon dioxide discharged from the regeneration section 503.

[0083] The oxidation catalyst 505 is for oxidizing hydrocarbons and carbon monoxide contained in the exhaust gas that is led to the absorption section 510. The oxidation catalyst 505 is provided midway along a guide path L501 that guides the exhaust gas from the engine E to the absorption section 510.

[0084] The absorbing liquid sensor 506 detects the state of the absorbing liquid. The absorbing liquid sensor 506 is provided midway along a circulation path L503 of the absorbing liquid circulating between the absorption section 510 and the regeneration section 503. The absorbing liquid sensor 506 can detect the state of the absorbing liquid circulating at the installation location. The state of the absorbing liquid detected by the absorbing liquid sensor 506 includes at least one of the viscosity, temperature, density, pH, etc. of the absorbing liquid.

[0085] The carbon dioxide sensor 507 detects the amount of carbon dioxide contained in the exhaust gas discharged from the absorption section 510. The carbon dioxide sensor 507 is provided midway along the discharge path L502 for the exhaust gas discharged from the absorption section 510.

[0086] The nitrogen oxide sensor 508 detects the amount of nitrogen oxide contained in the exhaust gas discharged from the absorption section 510. The nitrogen oxide sensor 508 is provided midway along the discharge path L502 for the exhaust gas discharged from the absorption section 510.

[0087] The control unit 509 performs appropriate calculations based on the detection results from the absorbing liquid sensor 506, the carbon dioxide sensor 507, the nitrogen oxide sensor 508, etc. The control unit 509 is composed of an arithmetic processing unit such as a CPU, and storage devices such as a RAM, a ROM, and an HDD. The control unit 509 can receive the detection results from the absorbing liquid sensor 506, the carbon dioxide sensor 507, and the nitrogen oxide sensor 508.

[0088] In the exhaust gas purification system 5 configured as described above, exhaust gas emitted from the engine E is guided to the oxidation catalyst 505, where hydrocarbons and the like contained in the exhaust gas are oxidized. The exhaust gas is then guided to the absorption section 510, where carbon dioxide and nitrogen oxides contained in the exhaust gas are absorbed by the absorption liquid. The exhaust gas purified in this way by the absorption section 510 is discharged to the outside.

[0089] The absorption liquid that has absorbed carbon dioxide and nitrogen oxides in the absorption section 510 is supplied to the regeneration section 503, where the carbon dioxide is separated. The absorption liquid from which the carbon dioxide has been separated is supplied again to the absorption section 510, and is used to purify the exhaust gas. The carbon dioxide separated in the regeneration section 503 is stored in the storage section 504.

[0090] In this way, in the exhaust gas purification system 5 according to this embodiment, not only carbon dioxide but also nitrogen oxides in the exhaust gas can be absorbed in the absorption section 510. This eliminates the need to provide a separate exhaust gas purification device for purifying nitrogen oxides in the exhaust gas, thereby simplifying the configuration of the exhaust gas purification system 5.

[0091] It should be noted that, once the absorption liquid absorbs nitrogen oxides, the absorption capacity of the absorption liquid for carbon dioxide and nitrogen oxides decreases. Therefore, the absorption liquid that has absorbed a certain amount of nitrogen oxides needs to be replaced with new absorption liquid. Therefore, in the exhaust gas purification system 5 according to this embodiment, processing can be performed to determine the appropriate time to replace the absorption liquid using the detection results from the absorption liquid sensor 506, the carbon dioxide sensor 507, and the nitrogen oxide sensor 508. This will be explained in detail below.

[0092] First, a method for determining the replacement timing of the absorbing liquid will be described using the absorbing liquid sensor 506. In this embodiment, the state of the absorbing liquid (viscosity, temperature, density, pH, etc.) is detected using the absorbing liquid sensor 506. The control unit 509 according to this embodiment can calculate the amount of nitrogen oxides absorbed by the absorbing liquid or the replacement timing of the absorbing liquid using the detection result by the absorbing liquid sensor 506.

[0093] It is known that there is a certain correlation between the state of the absorbing solution (viscosity, temperature, density, pH, etc.) and the amount of nitrogen oxides absorbed by the absorbing solution or the appropriate replacement time of the absorbing solution. Therefore, the control unit 509 pre-stores the relationship between the state of the absorbing solution (viscosity, temperature, density, pH, etc.) and the amount of nitrogen oxides absorbed by the absorbing solution or the appropriate replacement time of the absorbing solution. This relationship can be determined by a pre-performed experiment, numerical calculation (simulation), or the like. As an example, the relationship between the pH of the absorbing solution and the amount of nitrogen oxides absorbed by the absorbing solution or the appropriate replacement time can be pre-stored in the control unit 509. As another example, the relationship between the viscosity of the absorbing solution at a certain temperature and the amount of nitrogen oxides absorbed by the absorbing solution or the appropriate replacement time can be pre-stored in the control unit 509.

[0094] The control unit 509 calculates (estimates) the amount of nitrogen oxides absorbed in the absorbing liquid or the replacement time of the absorbing liquid, based on the above relationship and the state of the absorbing liquid actually detected by the absorbing liquid sensor 506, at any timing (for example, at regular intervals) while the exhaust gas purification system 5 is in operation. When the control unit 509 calculates the amount of nitrogen oxides absorbed in the absorbing liquid or the replacement time of the absorbing liquid, it can notify the manager of the exhaust gas purification system 5 of the calculation result by an appropriate notification device (for example, an LCD monitor, a speaker, etc.).

[0095] For example, upon receiving notification from the control unit 509 of the amount of nitrogen oxides absorbed in the absorbing solution, the manager can determine the appropriate time to replace the absorbing solution based on the amount of nitrogen oxides absorbed in the absorbing solution. For example, the amount of nitrogen oxides can be compared with a predetermined threshold, and the replacement time of the absorbing solution can be determined based on the magnitude relationship. It is also possible for the control unit 509 to determine the replacement time itself and notify the manager of the result. By replacing the absorbing solution at the determined replacement time, the manager can maintain the absorption capacity of the absorbing solution appropriately.

[0096] Furthermore, the manager who receives notification from the control unit 509 that it is time to replace the absorbent liquid can maintain the absorption capacity of the absorbent liquid at an appropriate time by replacing the absorbent liquid at the notified replacement time.

[0097] Next, a method for determining the replacement time of the absorbing solution will be described using the carbon dioxide sensor 507 and the nitrogen oxide sensor 508. In this embodiment, the amounts of carbon dioxide and nitrogen oxide contained in the exhaust gas discharged from the absorption unit 510 are detected using the carbon dioxide sensor 507 and the nitrogen oxide sensor 508. The control unit 509 according to this embodiment can calculate the amount of nitrogen oxide absorbed in the absorbing solution or the replacement time of the absorbing solution using the detection results from the carbon dioxide sensor 507 and the nitrogen oxide sensor 508.

[0098] It has been found that there is a certain correlation between the amounts of carbon dioxide and nitrogen oxides contained in the exhaust gas discharged from the absorption unit 510 and the amount of nitrogen oxides absorbed in the absorption liquid, or the appropriate time to replace the absorption liquid. For example, the more nitrogen oxides are absorbed in the absorption liquid, the lower the absorption capacity of the absorption liquid becomes, and the amounts of carbon dioxide and nitrogen oxides contained in the exhaust gas discharged from the absorption unit 510 increase. Therefore, the control unit 509 pre-stores the relationship between the amounts of carbon dioxide and nitrogen oxides contained in the exhaust gas discharged from the absorption unit 510 and the amount of nitrogen oxides absorbed in the absorption liquid, or the appropriate time to replace the absorption liquid. This relationship can be determined by experiments or numerical calculations (simulations) conducted in advance.

[0099] At any timing during operation of the exhaust gas purification system 5, the control unit 509 calculates (estimates) the amount of nitrogen oxides absorbed in the absorption liquid or the replacement time of the absorption liquid based on the above relationship and the amounts of carbon dioxide and nitrogen oxides actually detected by the carbon dioxide sensor 507 and the nitrogen oxide sensor 508. When the control unit 509 has calculated the amount of nitrogen oxides absorbed in the absorption liquid or the replacement time of the absorption liquid, it can notify the manager of the exhaust gas purification system 5 of the calculation result by an appropriate notification device.

[0100] The manager who receives the notification can determine the appropriate time to replace the absorbent liquid, and by replacing the absorbent liquid at the determined replacement time, the absorption capacity of the absorbent liquid can be maintained appropriately.

[0101] The control unit 509 can calculate the amount of nitrogen oxides absorbed in the absorbing solution or the appropriate time to replace the absorbing solution based on the detection results of at least one of the carbon dioxide sensor 507 and the nitrogen oxide sensor 508. That is, the control unit 509 can perform this calculation based only on the detection results of the carbon dioxide sensor 507, or can perform this calculation based only on the detection results of the nitrogen oxide sensor 508.

[0102] Next, the configuration of the absorption section 510 of the chemical absorption type exhaust gas purification system 5 and modified examples of the absorption section 510 will be described.

[0103] 3 shows a schematic configuration of the absorbing unit 510. As shown in FIG. 3, the absorbing unit 510 mainly includes a housing 511 and a nozzle 512.

[0104] The housing 511 is a hollow member (absorption chamber) for bringing the exhaust gas into contact with the absorption liquid. The housing 511 is formed, for example, in a circular (cylindrical) shape in a plan cross section. The shape of the housing 511 is not limited to a cylindrical shape and can be changed to any shape. The housing 511 is formed with an inlet 511a, an outlet 511b, and a recovery port 511c.

[0105] The inlet 511a is a portion that introduces exhaust gas from the engine E into the housing 511. The inlet 511a is formed in the lower part of the housing 511 so as to connect the outside and the inside of the housing 511.

[0106] The exhaust port 511b is a portion that discharges the exhaust gas that has passed through the housing 511 and been purified to the outside of the housing 511. The exhaust port 511b is formed in the upper part of the housing 511 so as to connect the inside and outside of the housing 511.

[0107] The recovery port 511c is a portion for guiding and recovering the absorption liquid sprayed inside the housing 511 to the outside of the housing 511. The recovery port 511c is formed in the lower part (near the bottom surface) of the housing 511 so as to communicate the outside and inside of the housing 511.

[0108] Nozzles 512 are used to spray the absorbing liquid inside housing 511. Nozzles 512 are arranged at an upper part inside housing 511, and can spray the absorbing liquid supplied via supply pipe 512a downward. Any number of nozzles 512 can be provided at any position inside housing 511. The number and arrangement of nozzles 512 are desirably determined taking into consideration the shape of housing 511, etc., so that the absorbing liquid sprayed from nozzles 512 can efficiently come into contact with the exhaust gas.

[0109] The exhaust gas can be purified in the thus configured absorption section 510. Specifically, as shown in Figures 2 and 3, the exhaust gas guided to the inlet 511a via the guide path L501 flows upward within the housing 511 and is discharged from the outlet 511b to the discharge path L502.

[0110] Furthermore, the absorption liquid guided from the regeneration unit 503 to the supply pipe 512a via the circulation path L503 is sprayed from the nozzle 512 into the housing 511. The absorption liquid sprayed downward from the nozzle 512 comes into contact with the exhaust gas flowing inside the housing 511 and absorbs the carbon dioxide and nitrogen oxides contained in the exhaust gas, thereby purifying the exhaust gas. The absorption liquid that has absorbed the carbon dioxide and nitrogen oxides is recovered from the recovery port 511c and supplied to the regeneration unit 503 via the circulation path L503.

[0111] Here, from the viewpoint of ensuring contact between the exhaust gas and the absorption liquid, it is desirable to increase the vertical dimension of the housing 511 in order to ensure the distance until the absorption liquid sprayed from the nozzle 512 reaches the bottom surface of the housing 511. On the other hand, from the viewpoint of mounting the exhaust gas purification system 5 on the tractor 600, it is desirable to reduce the vertical dimension of the absorption section 510 (housing 511) because the mounting space for the exhaust gas purification system 5 is limited. Therefore, below, an example (variant) of a configuration for reducing the vertical dimension of the absorption section 510 will be described.

[0112] In the following description, components having roughly the same configurations are denoted by the same reference numerals, and descriptions thereof will be omitted as appropriate.

[0113] FIG. 4 shows an absorption unit 510A according to a first modification. In the absorption unit 510A according to the first modification, the diameter D of the housing 511 is large and the overall height H of the housing 511 is small. Specifically, the diameter D of the housing 511 is set to be at least half the overall height H, and preferably at least three times the overall height H. By setting the diameter D large relative to the overall height H of the housing 511 in this way, it is possible to keep the vertical dimension (total height H) of the housing 511 small while ensuring contact between the absorption liquid sprayed from the nozzle 512 and the exhaust gas. This allows the exhaust gas purification system 5 (absorption unit 510) to be miniaturized, improving mountability on the tractor 600.

[0114] Furthermore, in the absorption unit 510A according to the first modification, the flow direction of the exhaust gas within the casing 511 is set so as to increase the opportunity for contact between the absorption liquid and the exhaust gas. Specifically, the inlet 511a of the casing 511 is formed so as to face in a direction along the inner surface of the casing 511 (the tangential direction of the inner surface in a plan view). With this configuration, the exhaust gas introduced from the inlet 511a flows circumferentially in a plan view along the inner surface of the casing 511, and heads toward the outlet 511b formed above. In other words, the exhaust gas flows in a spiral within the casing 511. This makes it possible to ensure a long flow distance of the exhaust gas, thereby increasing the opportunity for contact between the exhaust gas and the absorption liquid.

[0115] In the example of Figure 4, an example is shown in which the exhaust gas is caused to flow in a spiral pattern by arranging the inlet 511a in the housing 511, but it is also possible to cause the exhaust gas to flow in a spiral pattern by using, for example, a component (such as a straightening plate) for controlling the flow direction of the exhaust gas.

[0116] FIG. 5 shows an absorption unit 510B according to a second modification. In the absorption unit 510B according to the second modification, the nozzle 512 is disposed at the bottom of the housing 511 and is disposed so as to spray the absorption liquid upward. With this configuration, the absorption liquid sprayed from the nozzle 512 rises inside the housing 511 and then falls naturally due to gravity to the bottom of the housing 511. By moving the absorption liquid back and forth up and down in this manner, the travel distance of the absorption liquid can be increased, thereby increasing the opportunity for the absorption liquid to come into contact with the exhaust gas. As a result, the vertical dimension of the housing 511 can be kept small.

[0117] The nozzle 512 does not necessarily have to spray the absorbing liquid vertically upward, but may spray the absorbing liquid diagonally upward, for example. This makes it possible to more efficiently increase the distance traveled by the absorbing liquid. The nozzle 512 does not necessarily have to be disposed at the bottom of the housing 511, but may also be disposed, for example, midway up or down the housing 511.

[0118] 6 shows an absorbing section 510C according to a third modified example. In the absorbing section 510C according to the third modified example, the housing 511 is divided into a plurality of sections, and the vertical dimension of each housing 511 is kept small. This will be described in detail below.

[0119] 6 shows an example in which the housing 511 is divided into two (a first housing 511A and a second housing 511B). The first housing 511A and the second housing 511B are arranged in parallel (at roughly the same height). Exhaust gas is introduced into the first housing 511A and the second housing 511B from an inlet 511a and discharged from an outlet 511b.

[0120] In addition, the absorption liquid sprayed in the first housing 511A is recovered from the recovery port 511c of the first housing 511A, and then supplied to the second housing 511B by the pump 513, and sprayed again from the nozzle 512 of the second housing 511B.

[0121] With this configuration, the absorbing liquid that still has room to absorb carbon dioxide and nitrogen oxides after being sprayed into the first housing 511A and purifying the exhaust gas can be reused in the second housing 511B. Therefore, since it is not necessary to have the absorbing liquid completely absorb carbon dioxide and the like in a single spray, the vertical dimensions of the housing 511 (first housing 511A and second housing 511B) can be kept small. Furthermore, the absorbing liquid that still has room to absorb carbon dioxide and nitrogen oxides can be used efficiently.

[0122] In this way, by dividing the housing 511 into a plurality of parts and arranging them in parallel, the vertical dimension of the arrangement space for the housing 511 can be kept small.

[0123] 6 shows an example in which the housing 511 is divided into two parts, but the number of parts into which the housing 511 is divided is not limited to this, and the housing 511 can be divided into, for example, three or more parts. Also, for example, exhaust gas that has flowed through the first housing 511A and been discharged from the outlet 511b can be supplied to the inlet 511a of the second housing 511B. This allows exhaust gas that cannot be completely purified in the first housing 511A to be purified again in the second housing 511B, thereby making it possible to keep the vertical dimension of the housing 511 small.

[0124] Next, an example of the arrangement of the physical adsorption type exhaust gas purification system 4 or the chemical absorption type exhaust gas purification system 5 mounted on a tractor 600 will be described. By mounting the exhaust gas purification systems 4 and 5 on the tractor 600 and supplying exhaust gas from the engine E of the tractor 600 to the exhaust gas purification systems 4 and 5, the exhaust gas from the engine E can be purified.

[0125] 7 shows an example in which exhaust gas purification systems 4 and 5 are mounted on an unmanned, automatically driven tractor 600. For ease of explanation, the physical adsorption type exhaust gas purification system 4 and the chemical absorption type exhaust gas purification system 5 are both shown in the figure, but it is assumed that the tractor 600 is equipped with either one of the exhaust gas purification systems 4 and 5.

[0126] A tractor 600A according to the first embodiment shown in FIG. 7(a) mainly comprises a vehicle body 601, wheels 602, a sensor device 603, an engine E, exhaust gas purification systems 4 and 5, and the like.

[0127] The vehicle body 601 is supported by a plurality of wheels 602. The vehicle body 601 is formed by an appropriate frame or housing. Since the tractor 600A is unmanned and automatically driven without a driver on board, no living space for the driver is formed in the vehicle body 601. Therefore, the configuration of the housing, frame, power transmission mechanism, etc. of the vehicle body 601 can be changed as desired.

[0128] 7(a) shows an example in which the engine E and the exhaust gas purification systems 4 and 5 are arranged inside a common housing. Note that in order to prevent the heat generated by the engine E from adversely affecting the exhaust gas purification systems 4 and 5 (such as reducing the cooling capacity), the engine E and the exhaust gas purification systems 4 and 5 can be separated by a partition member.

[0129] 7(a), the engine E is disposed in the front of the vehicle body 601, and the exhaust gas purification systems 4 and 5 are disposed in the rear of the vehicle body 601 (rear of the engine E). The wheels 602 are rotated by the power of the engine E, allowing the tractor 600 to travel. The exhaust gas from the engine E can be purified by the exhaust gas purification systems 4 and 5.

[0130] A sensor device 603 is provided at an appropriate position on the tractor 600. The sensor device 603 includes sensors necessary for the automatic operation of the tractor 600. The sensors include, for example, a non-contact sensor capable of detecting obstacles around the tractor 600, an imaging unit capable of acquiring images of the periphery of the tractor 600, and the like. The tractor 600 can be automatically operated by controlling the running, stopping, steering, etc. of the tractor 600 according to the detection results of these sensors.

[0131] 7(a) shows an example in which the exhaust gas purification systems 4 and 5 are arranged behind the engine E, but it is also possible to arrange the exhaust gas purification systems 4 and 5 in the front of the vehicle body, and arrange the engine E behind the exhaust gas purification systems 4 and 5. Also, while FIG. 7(a) shows an example of a tractor 600 equipped with wheels 602, it is also possible to provide crawler devices in addition to or instead of the wheels 602.

[0132] The tractor 600B according to the second embodiment shown in FIG. 7(b) mainly comprises a hood 611, a housing 612, a power transmission mechanism 613, wheels 602, a sensor device 603, an engine E, and exhaust gas purification systems 4 and 5.

[0133] The hood 611 houses the engine E. The hood 611 is provided at the front of the tractor 600B. Behind the engine E, a power transmission mechanism 613 is arranged to appropriately change the speed of the power from the engine E and transmit it to the wheels 602.

[0134] The housing 612 houses the exhaust gas purification systems 4 and 5. The housing 612 is disposed behind the hood 611 and above the power transmission mechanism 613. The upper end of the housing 612 is formed to be higher than the upper end of the hood 611. The sensor device 603 is disposed, for example, at the top of the housing 612.

[0135] The tractor 600B according to the second embodiment can be constructed by replacing the cabin portion of a typical tractor, in which a driver can sit and drive, with the housing 612 (exhaust gas purification systems 4 and 5). This allows most of the body structure of an existing tractor to be reused, making it possible to manufacture the tractor 600B at low cost.

[0136] Furthermore, by placing the sensor device 603 in the housing 612 (a structure higher than the hood 611) which corresponds to the position of the cabin, the tractor 600B itself (for example, the hood 611, etc.) is less likely to interfere with detection by the sensor device 603, and surrounding obstacles, etc. can be detected more effectively.

[0137] 8 and 9 show an example in which the exhaust gas purification systems 4 and 5 are mounted on a tractor 600 that can be driven by a driver.

[0138] A tractor 600C according to the third embodiment shown in FIG. 8 mainly includes a bonnet 621, a cabin 622, wheels 602, a housing 624, an engine E, exhaust gas purification systems 4 and 5, and the like.

[0139] The hood 621 houses the engine E. The hood 621 is provided at the front of the tractor 600C. The cabin 622 is a room where a driver sits and drives the tractor 600C. The cabin 622 is located behind the hood 621.

[0140] The housing 624 houses the exhaust gas purification systems 4 and 5. The housing 624 is provided on the upper part of the cabin 622. The housing 624 can be provided on the upper side of the roof that forms the ceiling of the cabin 622. The housing 624 may be fixed to the cabin 622 (the frame that forms the cabin 622), or it can also be fixed to a separately provided support member (support frame). Note that the location of the exhaust gas purification systems 4 and 5 is not limited to this, and they can also be housed inside the roof of the cabin 622, for example. By providing the exhaust gas purification systems 4 and 5 on the upper part of the cabin 622, space can be secured below the cabin 622, and the transmission mechanism and the like of the tractor 600C can be easily disposed in this space.

[0141] In the example shown in FIG. 8 , the storage units 340 and 504 for storing carbon dioxide recovered by the exhaust gas purification systems 4 and 5 are disposed at the rear of the cabin 622 (e.g., on the back of the cabin 622). Alternatively, the storage units 340 and 504 may be disposed diagonally rearward of the cabin 622. This ensures rearward visibility for the driver in the cabin 622. The storage units 340 and 504 are configured to be detachable from the tractor 600C (cabin 622). By making the storage units 340 and 504 detachable in this way, the storage units 340 and 504 can be easily replaced. For example, by replacing the storage units 340 and 504 when the amount of stored carbon dioxide exceeds a predetermined value, it is possible to prevent the storage units 340 and 504 from becoming too large.

[0142] 8 shows an example in which a secondary storage unit 701 capable of storing carbon dioxide is mounted on a truck 700 for transporting cargo. The storage units 340 and 504 are configured to be connectable to the secondary storage unit 701 of the truck 700, and carbon dioxide stored in the storage units 340 and 504 can be supplied to the secondary storage unit 701. In this way, by extracting and recovering the carbon dioxide stored in the storage units 340 and 504 of the tractor 600C outside the tractor 600C (truck 700 (secondary storage unit 701)), it is possible to prevent the storage units 340 and 504 from becoming large.

[0143] The tractor 600D according to the fourth embodiment shown in Figure 9(a) is mainly equipped with a hood 621, a cabin 622, wheels 602, an engine E, and exhaust gas purification systems 4 and 5, similar to the tractor 600C according to the third embodiment (see Figure 8).

[0144] In the tractor 600D according to the fourth embodiment, the exhaust gas purification systems 4 and 5 are disposed below the cabin 622 (for example, below the floor (step) of the cabin 622). By configuring in this manner, it is possible to prevent the overall height of the tractor 600D from increasing.

[0145] A tractor 600E according to a fifth embodiment shown in Fig. 9(b) is mainly equipped with a hood 621, a cabin 622, wheels 602, an engine E, and exhaust gas purification systems 4 and 5, similar to the tractor 600C according to the third embodiment (see Fig. 8). Furthermore, the tractor 600E is equipped with a towing dolly 625 for towing the exhaust gas purification systems 4 and 5, in addition to the vehicle body on which the engine E is mounted.

[0146] The towing carriage 625 is disposed behind the cabin 622 and is connected to the vehicle body of the tractor 600E. The exhaust gas purification systems 4 and 5 are disposed on the towing carriage 625. By towing the exhaust gas purification systems 4 and 5 with the tractor 600E in this way, there is no need to significantly modify the structure of the tractor 600E itself in order to install the exhaust gas purification systems 4 and 5, and therefore the exhaust gas purification systems 4 and 5 can be used with the tractor 600E at relatively low cost.

[0147] As described above, the tractor 600A (see FIG. 7(a)) according to one aspect of the present disclosure includes the engine E, and the exhaust gas purification systems 4 and 5, which are disposed in front of or behind the engine E and are capable of removing carbon dioxide and nitrogen oxides contained in the exhaust gas of the engine E. By configuring the tractor in this manner, the exhaust gas purification systems 4 and 5 can be appropriately positioned.

[0148] As described above, the tractor 600B (see FIG. 7(b)) according to one embodiment of the present disclosure includes the engine E disposed inside the hood 611, and the exhaust gas purification systems 4 and 5 disposed behind the hood 611 and capable of removing carbon dioxide and nitrogen oxides contained in the exhaust gas of the engine E. This configuration allows the exhaust gas purification systems 4 and 5 to be appropriately positioned. Furthermore, by replacing the hood 611 and the cabin portion of an existing tractor having a cabin with the exhaust gas purification systems 4 and 5, the tractor 600B equipped with the exhaust gas purification systems 4 and 5 can be constructed relatively easily.

[0149] Furthermore, the exhaust gas purification systems 4 and 5 are disposed above a power transmission mechanism 613 that transmits power from the engine E to the wheels 602. This configuration allows the exhaust gas purification systems 4 and 5 to be appropriately disposed. That is, the space above the power transmission mechanism 613 can be utilized to dispose the exhaust gas purification systems 4 and 5.

[0150] The tractor 600B further includes a housing 612 that houses the exhaust gas purification systems 4 and 5, and the upper end of the housing 612 is located at a higher position than the upper end of the hood 611. This configuration allows the exhaust gas purification systems 4 and 5 to be appropriately positioned. That is, even exhaust gas purification systems 4 and 5 that are relatively large in vertical dimension can be easily mounted on the tractor 600B. Furthermore, since the sensor device 603 can be attached at a relatively high position (at the upper end of the housing 612), detection by the sensor device 603 can be performed appropriately.

[0151] As described above, the tractor 600C (see FIG. 8 ) according to one aspect of the present disclosure includes a cabin 622 in which a driver can ride, and exhaust gas purification systems 4 and 5 that are disposed above the cabin 622 and are capable of removing carbon dioxide and nitrogen oxides contained in the exhaust gas of the engine E. This configuration allows the exhaust gas purification systems 4 and 5 to be appropriately disposed. In other words, space can be secured below the cabin 622, and the transmission mechanism and the like of the tractor 600C can be easily disposed in this space.

[0152] As described above, the tractor 600D (see FIG. 9(a)) according to one aspect of the present disclosure includes a cabin 622 in which a driver can ride, and exhaust gas purification systems 4 and 5 that are disposed below the cabin 622 and are capable of removing carbon dioxide and nitrogen oxides contained in the exhaust gas of the engine E. This configuration allows the exhaust gas purification systems 4 and 5 to be appropriately disposed. In other words, the exhaust gas purification systems 4 and 5 can be mounted on the tractor 600D while preventing the overall height of the tractor 600D from increasing.

[0153] As described above, the tractor 600E (see FIG. 9(b)) according to one aspect of the present disclosure includes: a vehicle body having an engine E; a towing dolly 625 (towed vehicle) towed by the vehicle body; and exhaust gas purification systems 4 and 5 that are disposed on the towed vehicle and are capable of removing carbon dioxide and nitrogen oxides contained in the exhaust gas of the engine E. This configuration allows the exhaust gas purification systems 4 and 5 to be appropriately disposed. In other words, since there is no need to significantly modify the structure of the tractor 600E itself in order to install the exhaust gas purification systems 4 and 5, the exhaust gas purification systems 4 and 5 can be used in the tractor 600E at a relatively low cost.

[0154] Furthermore, the exhaust gas purification systems 4 and 5 are provided with storage units 340 and 504 (storage units) capable of storing the removed carbon dioxide, and the storage units 340 and 504 are detachably provided on the tractor 600 (see FIGS. 8 and 9). This configuration allows the storage units 340 and 504 to be easily replaced, which prevents the storage units 340 and 504 from becoming too large.

[0155] The exhaust gas purification systems 4 and 5 are also provided with storage units 340 and 504 (storage units) capable of storing the removed carbon dioxide, and the storage units 340 and 504 are provided at the rear of the cabin 622 (see FIGS. 8 and 9). This configuration allows the storage units 340 and 504 to be appropriately positioned.

[0156] Furthermore, the exhaust gas purification systems 4 and 5 are provided with storage units 340 and 504 (storage units) capable of storing the removed carbon dioxide, and the storage units 340 and 504 are configured to be connectable to a secondary storage unit 701 (secondary storage unit) that is provided outside the tractor 600 and capable of storing carbon dioxide. By configuring them in this way, it is possible to prevent the storage units 340 and 504 from becoming large.

[0157] The exhaust gas purification system 5 also includes an absorption section 510 that absorbs carbon dioxide and nitrogen oxides contained in the exhaust gas into an absorption liquid, and a regeneration section 503 that recovers carbon dioxide from the absorption liquid supplied from the absorption section 510 and supplies the absorption liquid back to the absorption section 510. This configuration makes it possible to remove carbon dioxide and nitrogen oxides contained in the exhaust gas with a simple configuration. In other words, because the absorption section 510 can absorb nitrogen oxides in addition to carbon dioxide, there is no need to provide a separate exhaust gas purification device for purifying nitrogen oxides, and the configuration of the exhaust gas purification system 5 can be simplified.

[0158] The exhaust gas purification system 4 also includes an adsorption / desorption unit 310 (adsorption unit) capable of adsorbing carbon dioxide and nitrogen oxides contained in exhaust gas, a first cooling unit (first cooling unit 321 and third cooling unit 323) that uses a refrigerant to cool at least one of the exhaust gas guided to the adsorption / desorption unit 310, the adsorption / desorption unit 310, or the carbon dioxide desorbed from the adsorption / desorption unit 310, and a second cooling unit (second cooling unit 322 and fourth cooling unit 324) that uses a refrigerant that flows through a path independent of the first cooling unit to cool at least one of the exhaust gas guided to the adsorption / desorption unit 310, the adsorption / desorption unit 310, or the carbon dioxide desorbed from the adsorption / desorption unit 310. This configuration makes it possible to remove carbon dioxide and nitrogen oxides contained in exhaust gas with a simple configuration and to reduce power consumption. In other words, by separating the refrigerant flow paths of the first cooling section and the second cooling section, for example, refrigerant that has become hot in one cooling section will not reduce the cooling capacity of the other cooling section, thereby reducing the power consumption for cooling.

[0159] As described above, the exhaust gas purification system 5 (see FIGS. 2 and 4 ) according to one embodiment of the present disclosure includes: an absorption unit 510A that absorbs carbon dioxide and nitrogen oxides contained in exhaust gas into an absorption liquid; and a regeneration unit 503 that recovers carbon dioxide from the absorption liquid supplied from the absorption unit 510A and supplies the absorption liquid back to the absorption unit. The absorption unit 510A includes: a cylindrical housing 511 formed so that the diameter D is at least half the total height H; and a nozzle 512 (spray unit) that sprays the absorption liquid inside the housing 511. This configuration allows the vertical dimension of the absorption unit 510A to be reduced. In other words, by increasing the ratio of the diameter D to the total height H of the housing 511, the vertical dimension of the absorption unit 510A can be reduced while maintaining the absorption performance of the absorption unit 510A.

[0160] The housing 511 is formed so that the diameter D is three times or more the total height H. By configuring it in this way, the vertical dimensions of the absorbing section 510A can be reduced.

[0161] As described above, the exhaust gas purification system 5 (see FIGS. 2 and 5 ) according to one embodiment of the present disclosure includes: an absorption unit 510B that absorbs carbon dioxide and nitrogen oxides contained in exhaust gas into an absorption liquid; and a regeneration unit 503 that recovers carbon dioxide from the absorption liquid supplied from the absorption unit 510B and supplies the absorption liquid back to the absorption unit 510B. The absorption unit 510B includes: a housing 511; and a nozzle 512 (spray unit) that sprays the absorption liquid upward inside the housing 511. This configuration makes it possible to reduce the vertical dimension of the absorption unit 510B. In other words, the travel distance of the absorption liquid can be increased to increase the opportunity for contact between the absorption liquid and the exhaust gas, thereby making it possible to keep the vertical dimension of the housing 511 small.

[0162] As described above, the exhaust gas purification system 5 (see FIGS. 2 and 6 ) according to one embodiment of the present disclosure includes: an absorption unit 510C that absorbs carbon dioxide and nitrogen oxides contained in exhaust gas into an absorption liquid; and a regeneration unit 503 that recovers carbon dioxide from the absorption liquid supplied from the absorption unit 510C and supplies the absorption liquid back to the absorption unit 510C. The absorption unit 510C includes: a plurality of housings 511; and nozzles 512 (spraying units) that spray the absorption liquid inside the plurality of housings 511. This configuration allows the vertical dimension of the absorption unit 510C to be reduced. In other words, because carbon dioxide and the like can be absorbed in the plurality of housings 511, the vertical dimension of each housing 511 can be reduced, and therefore the vertical dimension of the entire absorption unit 510C can be reduced.

[0163] Moreover, the nozzle 512 (spraying unit) recovers the absorbing liquid sprayed in one of the plurality of housings 511, and sprays it again in the other housings 511. By configuring in this way, the absorbing liquid can be used efficiently.

[0164] Furthermore, a tractor 600 according to one aspect of the present disclosure (see FIGS. 7 to 9) is equipped with an exhaust gas purification system 5. By configuring it in this manner, it is possible to reduce the vertical dimensions of the absorbing section 510C, and therefore it is possible to reduce the size of the tractor 600.

[0165] The towing dolly 625 is an embodiment of a towed vehicle. The storage units 340 and 504 are an embodiment of a storage unit. The secondary storage unit 701 is an embodiment of a secondary storage unit. The adsorption / desorption unit 310 is an embodiment of an adsorption unit. The nozzle 512 is an embodiment of a spray unit.

[0166] Although the embodiment of the present invention has been described above, the present invention is not limited to the above configuration, and various modifications are possible within the scope of the invention described in the claims.

[0167] For example, the configurations of the above-described embodiments and modifications can be combined as appropriate.

[0168] Furthermore, the exhaust gas purification systems 4 and 5 according to the above embodiments can be mounted on work vehicles other than tractors, agricultural vehicles, industrial vehicles, transport equipment, and the like.

[0169] Furthermore, although the exhaust gas purification systems 4, 5, etc. according to the above embodiments have been described as purifying the exhaust gas emitted from the engine E, they can be used for any other purpose. For example, they can also purify exhaust gas emitted from boilers and gas turbines in thermal power plants, etc., and exhaust gas generated in steel mills, etc.

[0170] The present invention can be applied to an exhaust gas purification system and a tractor equipped with the same.

[0171] 4 Exhaust gas purification system 5 Exhaust gas purification system 310 Adsorption / desorption section 340 Storage section 503 Regeneration section 504 Storage section 510 Absorption section 511 Housing 512 Nozzle 600 Tractor 602 Wheels 611 Bonnet 612 Housing 613 Power transmission mechanism 622 Cabin 625 Towing dolly 701 Secondary storage section

Claims

1. An exhaust gas purification system comprising: an absorption unit that absorbs carbon dioxide and nitrogen oxides contained in exhaust gas into an absorption liquid; and a regeneration unit that recovers carbon dioxide from the absorption liquid supplied from the absorption unit and supplies the absorption liquid again to the absorption unit, wherein the absorption unit comprises: a cylindrical casing formed so that the diameter is at least half of the total height; and a spraying unit that sprays the absorption liquid inside the casing.

2. The exhaust gas purification system according to claim 1, wherein the housing is formed so that the diameter is three times or more the overall height.

3. A tractor comprising the exhaust gas purification system according to claim 1 or 2.

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