Ammonia Engine System

Abstract

To provide an ammonia engine system capable of properly processing ammonia discharged from an ammonia supply portion.SOLUTION: An ammonia engine system 1 has an ammonia engine 2 to which ammonia is supplied via an injector 6, and an ammonia tank 12 for storing ammonia. The ammonia engine system 1 has: an ammonia supply portion 13 having a connection passage 11 for connecting the injector 6 and the ammonia tank 12; an exhaust passage 4 connected to the ammonia engine 2 so that an exhaust gas from the ammonia engine 2 flows therein; and an exhaust catalyst 5 provided on the exhaust passage 4, and adsorbing and oxidizing ammonia. The ammonia engine system 1 has an auxiliary passage 20 provided so that an ammonia gas discharged from the ammonia supply portion 13 flows therein and the ammonia gas flowing therein is supplied to the exhaust catalyst 5.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an ammonia engine system. [Background technology]

[0002] Known conventional ammonia engine systems include, for example, the technology described in Patent Document 1. The internal combustion engine described in Patent Document 1 includes an engine body, an exhaust purification device, a decomposer, a tank, an evaporator, and an oxygen supply device.

[0003] The exhaust purification device purifies exhaust gas emitted from the engine body. The tank is connected to the evaporator by a liquid ammonia supply pipe. The inside of the tank is pressurized. Liquid ammonia is stored inside the tank. The evaporator heats the liquid ammonia supplied from the tank via the liquid ammonia supply pipe. The liquid ammonia heated by the evaporator is vaporized.

[0004] The evaporator is connected to the decomposer by an ammonia supply pipe. The ammonia vaporized in the evaporator is supplied to the decomposer via the ammonia supply pipe. The oxygen supply device supplies air to the decomposer.

[0005] The cracker receives ammonia vaporized in the evaporator and air from the oxygen supply device. The cracker generates hydrogen by oxidizing and decomposing the ammonia. The hydrogen and ammonia generated in the cracker are supplied to the combustion chamber of the engine body, and air is drawn in for combustion. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2012 / 090739 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the internal combustion engine of Patent Document 1, when ammonia is vaporized by heating the ammonia in the evaporator, the internal pressure of the evaporator and the ammonia supply pipe increases. In order to prevent the internal pressure from increasing excessively, for example, a pressure relief valve may be provided to discharge the vaporized ammonia in the ammonia supply pipe to the outside of the ammonia supply pipe in order to reduce the internal pressure of the ammonia supply pipe. In such a case, it is necessary to appropriately treat the ammonia discharged from the ammonia supply pipe via the pressure relief valve.

[0008] Furthermore, for example, the liquid ammonia supply pipe may be removed from the tank in order to replace the tank. When the liquid ammonia supply pipe is removed from the tank, it is necessary to appropriately treat the ammonia discharged from the liquid ammonia supply pipe. [Means for solving the problem]

[0009] An ammonia engine system for solving the above problems comprises: an ammonia engine to which ammonia is supplied via an ammonia amount adjustment unit capable of adjusting the amount of ammonia discharged; an ammonia tank for storing ammonia; an ammonia supply unit having a connection path connecting the ammonia amount adjustment unit and the ammonia tank; an exhaust path connected to the ammonia engine and into which exhaust gas from the ammonia engine flows; an exhaust catalyst provided in the exhaust path and which adsorbs and oxidizes ammonia; and an auxiliary path provided so that the ammonia discharged from the ammonia supply unit flows into and the inflowing ammonia is supplied to the exhaust catalyst.

[0010] In this configuration, the ammonia discharged from the ammonia supply unit is supplied to the exhaust catalyst via the auxiliary path, so that the discharged ammonia can be adsorbed and oxidized by the exhaust catalyst, thereby enabling the ammonia discharged from the ammonia supply unit to be appropriately treated.

[0011] In the above-described ammonia engine system, the ammonia supply unit may include a vaporizer that vaporizes the ammonia flowing in from the ammonia tank, and a pressure release valve that opens when the internal pressure of the vaporizer reaches or exceeds a predetermined value, the connection path may include a first connection path that connects the ammonia tank and the vaporizer, and a second connection path that connects the vaporizer and the ammonia amount adjustment unit, and the auxiliary path may be connected to the ammonia supply unit so that the ammonia discharged from the pressure release valve that is open flows into the auxiliary path.

[0012] In this configuration, the ammonia discharged from the ammonia supply unit through the pressure release valve is supplied to the exhaust catalyst through the auxiliary path, so that the discharged ammonia can be adsorbed and oxidized by the exhaust catalyst, thereby enabling the ammonia discharged from the ammonia supply unit to be appropriately treated.

[0013] In the above-described ammonia engine system, the ammonia supply unit may include an open valve that is provided so as to connect the connection path and the auxiliary path when opened.

[0014] In this configuration, when the open valve is opened, ammonia is discharged from the connecting passage to the auxiliary passage. The ammonia discharged from the connecting passage via the open valve is supplied to the exhaust catalyst via the auxiliary passage, so that the ammonia discharged from the connecting passage can be adsorbed and oxidized by the exhaust catalyst. Therefore, the ammonia discharged from the ammonia supply unit can be appropriately treated.

[0015] The above-described ammonia engine system may further include a suction device that is connected to the auxiliary path and that, when the connection path is detached from the ammonia tank, sucks in ammonia discharged from the connection path and discharges the sucked ammonia into the auxiliary path.

[0016] In this configuration, for example, when the connecting path is disconnected from the ammonia tank for maintenance of the ammonia engine system, the ammonia discharged from the connecting path is discharged into the auxiliary path by suction using the suction device, and is supplied to the exhaust catalyst via the auxiliary path. Therefore, the ammonia discharged from the connecting path can be adsorbed and oxidized by the exhaust catalyst. Therefore, the ammonia discharged from the ammonia supply unit can be appropriately treated. [Effects of the Invention]

[0017] According to the present invention, the ammonia discharged from the ammonia supply section can be appropriately treated. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a schematic diagram showing an ammonia engine system according to a first embodiment. [Figure 2] FIG. 2 is a schematic diagram showing a pressure release valve of the first embodiment. [Figure 3] FIG. 1 is a schematic diagram showing an ammonia engine system according to a second embodiment. [Figure 4] FIG. 4 is a schematic diagram showing a suction device according to a second embodiment. [Figure 5] FIG. 10 is a schematic diagram showing an ammonia engine system according to a third embodiment. [Figure 6] FIG. 10 is a schematic diagram showing an open valve of a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0019] (First embodiment) <Ammonia engine system> 1, an ammonia engine system 1 mounted on a vehicle includes an ammonia engine 2 having a combustion chamber 8, an intake path 3, an exhaust path 4, an exhaust catalyst 5, an injector 6 serving as an ammonia amount adjuster, a main throttle valve 7, and an air cleaner 9. The ammonia engine system 1 also includes a vaporizer 10, a connection path 11 having a first connection path 11a and a second connection path 11b, an ammonia tank 12, an ammonia supplier 13, a reformer 14, a reforming path 15, a reforming throttle valve 16, an ammonia gas path 17, a reforming injector 18, and a pressure release valve 19. The ammonia engine system 1 also includes an auxiliary path 20.

[0020] The ammonia engine 2 is an engine that uses ammonia (NH3) as fuel. The ammonia engine 2 is, for example, a four-cylinder engine. The ammonia engine 2 has a plurality of combustion chambers 8. Hydrogen (H2) is supplied to the combustion chambers 8 together with ammonia.

[0021] The intake path 3 connects the combustion chamber 8 and the air cleaner 9. The intake path 3 is a path through which air drawn in through the air cleaner 9 flows. The air flowing through the intake path 3 is supplied to the combustion chamber 8. The air cleaner 9 removes foreign matter such as dust and dirt contained in the air before it is drawn into the intake path 3.

[0022] The exhaust path 4 connects the combustion chamber 8 and the exhaust catalyst 5. The exhaust path 4 is a path into which exhaust gas generated in the combustion chamber 8 flows. Therefore, the exhaust path 4 is connected to the ammonia engine 2, and exhaust gas from the ammonia engine 2 flows into the exhaust path 4. The exhaust gas generated in the combustion chamber 8 is supplied to the exhaust catalyst 5 via the exhaust path 4.

[0023] The exhaust catalyst 5 removes nitrogen oxides (NO xThe exhaust catalyst 5 removes harmful substances such as benzene, toluene, and ammonia. The exhaust catalyst 5 adsorbs and oxidizes ammonia. Examples of types of exhaust catalyst 5 that can be used include a three-way catalyst and an SCR (Selective Catalytic Reduction) catalyst. Therefore, the exhaust catalyst 5 is provided in the exhaust path 4 and adsorbs and oxidizes ammonia.

[0024] The injector 6 serving as the ammonia amount adjustment unit is an electromagnetic fuel injection valve that injects ammonia toward the combustion chamber 8. The injector 6 adjusts the amount of ammonia to be injected toward the combustion chamber 8 by opening and closing a valve (not shown). Therefore, the injector 6 can adjust the amount of ammonia discharged from the injector 6 into the combustion chamber 8. Ammonia is supplied to the ammonia engine 2 via the injector 6. The injector 6 is connected to a carburetor 10 (described later) via a connection path 11. The injector 6 is attached to the ammonia engine 2.

[0025] The main throttle valve 7 is disposed in the intake path 3 between the air cleaner 9 and the ammonia engine 2. The main throttle valve 7 controls the amount of air supplied to the ammonia engine 2. An electromagnetic flow control valve is used as the main throttle valve 7.

[0026] The ammonia tank 12 stores ammonia in a liquid state. Hereinafter, ammonia in a liquid state will be referred to as liquid ammonia. Ammonia in a gaseous state will be referred to as ammonia gas.

[0027] The reformer 14 is a device that reforms ammonia gas to produce a reformed gas containing hydrogen. The reformer 14 has a carrier 14a having, for example, a honeycomb structure. A reforming catalyst (not shown) that decomposes ammonia gas into hydrogen is applied to the carrier 14a. The reforming catalyst has the function of decomposing ammonia gas into hydrogen as well as the function of burning the ammonia gas. The reforming catalyst is, for example, an ATR (Autothermal Reformer) type ammonia reforming catalyst. The reformer 14 also has a heater 14c that adjusts the temperature of the reforming catalyst to an optimum temperature for decomposing ammonia gas into hydrogen. The heater 14c is, for example, an electric heater. A low-temperature reaction catalyst may be used as the reforming catalyst.

[0028] The reforming path 15 has a first reforming path 15a that connects the intake path 3 and the reformer 14, and a second reforming path 15b that connects the reformer 14 and the intake path 3. The first reforming path 15a connects the reformer 14 to a portion of the intake path 3 between the air cleaner 9 and the main throttle valve 7. The first reforming path 15a is a path through which air drawn in through the air cleaner 9 flows. The air drawn in through the air cleaner 9 is supplied to the reformer 14 via the first reforming path 15a.

[0029] The reforming throttle valve 16 is disposed in the first reforming path 15a. The reforming throttle valve 16 controls the amount of air supplied to the reformer 14. As the reforming throttle valve 16, for example, an electromagnetic flow control valve is used.

[0030] The second reforming path 15b connects the reformer 14 to a portion of the intake path 3 between the main throttle valve 7 and the ammonia engine 2. The second reforming path 15b is a path through which the reformed gas produced in the reformer 14 flows. The reformed gas produced in the reformer 14 is supplied to the intake path 3 via the second reforming path 15b. Therefore, air and reformed gas flow in the portion of the intake path 3 between the portion connected to the second reforming path 15b and the ammonia engine 2, and the air and reformed gas are supplied to the ammonia engine 2.

[0031] The ammonia gas path 17 connects the portion of the reforming path 15 between the reforming throttle valve 16 and the reformer 14 to the connection path 11, which will be described later. The reforming injector 18 is disposed in the ammonia gas path 17. The ammonia gas path 17 is a path through which the ammonia vaporized in the vaporizer 10 flows. The ammonia vaporized in the vaporizer 10 is in a gaseous state, and is therefore the ammonia gas described above. The reforming injector 18 is an electromagnetic fuel injection valve that injects ammonia gas toward the portion of the first reforming path 15a between the reforming throttle valve 16 and the reformer 14. The reforming injector 18 adjusts the amount of ammonia gas supplied to the reformer 14. Therefore, air and ammonia gas flow in the portion of the first reforming path 15a between the reforming throttle valve 16 and the reformer 14, and the air and ammonia gas are supplied to the reformer 14.

[0032] The ammonia supply unit 13 includes a vaporizer 10 , a pressure release valve 19 , and a connecting path 11 . The vaporizer 10 vaporizes liquid ammonia supplied from the ammonia tank 12 to generate ammonia gas.

[0033] The connection path 11 has a first connection path 11a that connects the ammonia tank 12 and the vaporizer 10, and a second connection path 11b that connects the vaporizer 10 and the injector 6. Therefore, the connection path 11 connects the injector 6 and the ammonia tank 12.

[0034] First connection path 11a is a path through which liquid ammonia flows, supplied from ammonia tank 12 to vaporizer 10. The liquid ammonia flowing through first connection path 11a is supplied to vaporizer 10. Second connection path 11b is a path through which ammonia gas flowing in from vaporizer 10 flows. The ammonia gas flowing through second connection path 11b is supplied to combustion chamber 8 by injector 6.

[0035] The pressure release valve 19 is disposed in the second connection path 11b. As shown in FIG. 2, the pressure release valve 19 is a spring-type release valve. The pressure release valve 19 has a body 19a, a valve 19b, and a biasing spring 19c. A valve chamber 19d is formed in the body 19a. An auxiliary path 20, which will be described later, is connected to the body 19a. The valve 19b is disposed in the valve chamber 19d. The biasing spring 19c is disposed in the valve chamber 19d and applies a biasing force to the valve 19b in a direction toward the second connection path 11b.

[0036] The valve 19b can be positioned between a first position indicated by a two-dot chain line in FIG. 2 and a second position indicated by a solid line in FIG. 2. When the valve 19b is in the first position, the second connection path 11b and the auxiliary path 20 are blocked. When the valve 19b is in the second position, the second connection path 11b and the auxiliary path 20 are connected via a valve chamber 19d. When the internal pressure of the second connection path 11b is less than a predetermined value, the valve 19b is positioned in the first position by the biasing force of the biasing spring 19c. The biasing force of the biasing spring 19c is large enough to resist the predetermined value of the internal pressure of the second connection path 11b. When the valve 19b is positioned in the first position, the pressure release valve 19 is closed.

[0037] When the internal pressure of second connection path 11b reaches a predetermined value or higher, valve 19b receives the internal pressure and compresses biasing spring 19c, causing valve 19b to move to its second position. When valve 19b is in its second position, pressure release valve 19 opens. The internal pressure of second connection path 11b is approximately the same as the internal pressure of vaporizer 10. Therefore, when the internal pressure of vaporizer 10 reaches a predetermined value or higher, pressure release valve 19 opens. The predetermined value of the internal pressure is set to a value slightly smaller than the maximum value of the highest internal pressure among the expected internal pressures of vaporizer 10. The internal pressure of vaporizer 10 is higher than atmospheric pressure.

[0038] When the ammonia engine 2 is operating, if the internal pressure of vaporizer 10 is less than a predetermined value, valve 19b is located at the first position and pressure release valve 19 is closed. Therefore, when the internal pressure of vaporizer 10 is less than the predetermined value, ammonia gas flows through second connection path 11b. On the other hand, when the ammonia engine 2 is operating, if the internal pressure of vaporizer 10 becomes equal to or greater than the predetermined value, valve 19b is located at the second position and pressure release valve 19 is opened. Therefore, when the internal pressure of vaporizer 10 becomes equal to or greater than the predetermined value, ammonia gas flows through auxiliary path 20.

[0039] <Auxiliary Route> 1, the auxiliary passage 20 connects the pressure release valve 19 and the exhaust catalyst 5. One end of the auxiliary passage 20 is connected to the body 19a of the pressure release valve 19. The auxiliary passage 20 communicates with the valve chamber 19d. The other end of the auxiliary passage 20 is connected to the exhaust catalyst 5.

[0040] Because the exhaust catalyst 5 is open to the atmosphere, when the valve 19b of the pressure release valve 19 is in the first position, the internal pressure of the auxiliary passage 20 and the exhaust catalyst 5 is atmospheric pressure. Also, as described above, the internal pressure of the vaporizer 10 is higher than atmospheric pressure. The internal pressure of the auxiliary passage 20 and the exhaust catalyst 5 is lower than the internal pressure of the vaporizer 10. Therefore, when the internal pressure of the vaporizer 10 reaches a predetermined value or higher and the valve 19b of the pressure release valve 19 is positioned at the second position and opens, the ammonia gas in the vaporizer 10 and the second connection passage 11b is supplied to the exhaust catalyst 5 via the pressure release valve 19 and the auxiliary passage 20 due to the pressure difference between the vaporizer 10 and the auxiliary passage 20. Therefore, the auxiliary passage 20 is configured so that ammonia gas discharged from the opened pressure release valve 19 flows into it and is supplied to the exhaust catalyst 5. That is, the auxiliary path 20 is provided so that the ammonia gas discharged from the ammonia supply unit 13 flows into the auxiliary path 20 and the ammonia gas that has flowed in is supplied to the exhaust catalyst 5.

[0041] <Ammonia engine system operation> When the ammonia engine system 1 configured as described above starts, the liquid ammonia stored in the ammonia tank 12 is supplied to the vaporizer 10 via the first connection path 11a. The liquid ammonia is vaporized in the vaporizer 10 to become ammonia gas. A portion of the ammonia gas is supplied to the injector 6 via the second connection path 11b. Note that because the valve 19b of the pressure release valve 19 is in the first position, the second connection path 11b and the auxiliary path 20 are blocked.

[0042] Furthermore, a portion of the ammonia gas is supplied to the reforming injector 18 via an ammonia gas path 17. The reforming injector 18 injects the ammonia gas toward the first reforming path 15a. When the reforming throttle valve 16 opens, air drawn in via the air cleaner 9 is supplied to the reformer 14 via the first reforming path 15a. In the reformer 14, the ammonia gas is reformed by a reforming catalyst, and a reformed gas containing hydrogen is produced. The reformed gas is supplied to the combustion chamber 8 of the ammonia engine 2 via the second reforming path 15b and the intake path 3.

[0043] Furthermore, when the ammonia engine 2 starts, the main throttle valve 7 and the injector 6 open. Air drawn in through an air cleaner 9 is supplied to a combustion chamber 8 of the ammonia engine 2 via an intake path 3, and ammonia gas is injected from the injector 6. In the combustion chamber 8, the ammonia gas is combusted together with oxygen and hydrogen in the reformed gas. As a result, the ammonia gas is combusted in the combustion chamber 8.

[0044] The operation of this embodiment will be described below. When the internal pressure of the vaporizer 10 exceeds a predetermined value due to an overheating or the like while the ammonia engine 2 is operating, the pressure release valve 19 opens. Then, the second connection path 11b and the auxiliary path 20 communicate with each other via the valve chamber 19d of the pressure release valve 19. The ammonia gas is discharged from the second connection path 11b to the auxiliary path 20. The ammonia gas discharged to the auxiliary path 20 is supplied to the exhaust catalyst 5. The ammonia gas supplied to the exhaust catalyst 5 via the auxiliary path 20 is adsorbed and oxidized by the exhaust catalyst 5.

[0045] The ammonia engine system 1 according to the first embodiment has the following advantages. (1-1) A pressure release valve 19 is disposed in the second connection path 11b, and an auxiliary path 20 is connected to the pressure release valve 19. When the internal pressure of the vaporizer 10 reaches a predetermined value or more and the pressure release valve 19 opens, ammonia gas is discharged from the second connection path 11b to the auxiliary path 20. The ammonia gas discharged from the second connection path 11b via the pressure release valve 19 is supplied to the exhaust catalyst 5 via the auxiliary path 20, and the ammonia gas can be adsorbed and oxidized by the exhaust catalyst 5. Therefore, the ammonia gas discharged from the ammonia supply unit 13 can be appropriately treated.

[0046] (1-2) The ammonia gas discharged from the second connection path 11b via the pressure release valve 19 is adsorbed and oxidized by the exhaust catalyst 5. That is, the ammonia gas discharged from the second connection path 11b via the pressure release valve 19 can be treated using the exhaust catalyst 5 provided in the ammonia engine system 1. Therefore, the ammonia engine system 1 can treat the ammonia gas without adding an absorbent for treating ammonia or an ammonia detoxification device. As a result, the mountability of the ammonia engine system 1 on a vehicle is improved compared to, for example, a case where an absorbent for treating ammonia or an ammonia detoxification device is required.

[0047] (Second embodiment) Next, an ammonia engine system 1 according to a second embodiment will be described. This embodiment differs from the first embodiment in that a suction device is provided in the auxiliary path 20 and that the pressure release valve 19 is not provided. In this embodiment, the same configuration as in the first embodiment will be referred to and the same reference numerals will be used.

[0048] 3 and 4, the second connection path 11b is not provided with a pressure release valve 19. An auxiliary path 20 has an intake device 21 at one end thereof, and the other end thereof is connected to the exhaust catalyst 5. The auxiliary path 20 is a flexible pipe that allows the position of the intake device 21 to be changed. The ammonia tank 12 has a tank-side connection end 12a that is connected to the first connection path 11a, and the first connection path 11a has a path-side connection end 11c that is connected to the ammonia tank 12. The ammonia tank 12 and the first connection path 11a are connected by connecting the tank-side connection end 12a and the path-side connection end 11c.

[0049] <Suction device> The ammonia engine system 1 includes a suction device 21 connected to the auxiliary path 20 .

[0050] The suction device 21 includes a suction section 21a and a pump 21b. The suction section 21a is disposed at one end of the auxiliary path 20. The pump 21b is disposed in the auxiliary path 20. When the pump 21b is driven, it can suck in ambient air through the suction section 21a. The air sucked in by the pump 21b is discharged into the auxiliary path 20 and is also supplied to the exhaust catalyst 5 via the auxiliary path 20.

[0051] The operation of this embodiment will be described below. For maintenance of the ammonia engine system 1, the connection between the tank-side connection end 12a and the path-side connection end 11c may be disconnected. At this time, the liquid ammonia present in the ammonia tank 12 and the first connection path 11a is released to the atmosphere, vaporizes, and floats around. At this time, the suction unit 21a is disposed near the tank-side connection end 12a and the path-side connection end 11c, and the pump 21b of the suction device 21 is driven. Alternatively, the pump 21b is driven before the connection between the tank-side connection end 12a and the path-side connection end 11c is released. The ammonia gas floating around is then discharged to the auxiliary path 20 via the suction unit 21a. The ammonia gas discharged to the auxiliary path 20 is supplied to the exhaust catalyst 5. Therefore, when the connection path 11 is disconnected from the ammonia tank 12, the suction device 21 sucks in the ammonia discharged from the connection path 11 and discharges the sucked ammonia into the auxiliary path 20.

[0052] The ammonia engine system 1 according to the second embodiment has the following advantages in addition to the advantages described in (1-2) of the first embodiment. (2-1) The suction device 21 is provided in the auxiliary path 20. The ammonia gas discharged when the first connection path 11a is disconnected from the ammonia tank 12 is discharged into the auxiliary path 20 by the suction device 21. The ammonia gas discharged into the auxiliary path 20 is then supplied to the exhaust catalyst 5 via the auxiliary path 20, and can be adsorbed and oxidized by the exhaust catalyst 5. Therefore, the ammonia gas discharged from the ammonia supply unit 13 can be appropriately treated.

[0053] (Third embodiment) Next, an ammonia engine system 1 according to a third embodiment will be described. This embodiment differs from the first embodiment in that it includes a release valve 22 instead of the pressure release valve 19. In this embodiment, the same configuration as in the first embodiment will be referred to and the same reference numerals will be used.

[0054] As shown in FIG. 5, the ammonia engine system 1 of this embodiment includes an open valve 22. As shown in FIG. 6, the open valve 22 is, for example, a needle valve. The open valve 22 has a body 22a and a needle 22b. A valve chamber 22c is formed in the body 22a. The auxiliary path 20 is connected to the body 22a. The needle 22b is in a first position indicated by a two-dot chain line in FIG. 6 and a second position indicated by a solid line in FIG. 6. When the needle 22b is in the first position, the second connection path 11b and the auxiliary path 20 are blocked. When the needle 22b is in the second position, the second connection path 11b and the auxiliary path 20 are communicated with each other via the valve chamber 22c. When the ammonia engine 2 is operating, the needle 22b is positioned in the first position, and therefore the open valve 22 is closed. Therefore, when the ammonia engine 2 is operating, ammonia gas does not flow into the auxiliary path 20.

[0055] When the ammonia engine 2 is stopped, if an operator places the needle 22b in the second position for maintenance or the like, the open valve 22 opens. Then, the ammonia gas in the second connection path 11b flows into the auxiliary path 20.

[0056] The auxiliary passage 20 connects the open valve 22 and the exhaust catalyst 5. One end of the auxiliary passage 20 is connected to a body 22a of the open valve 22, and the auxiliary passage 20 is in communication with a valve chamber 22c. The other end of the auxiliary passage 20 is connected to the exhaust catalyst 5. Ammonia gas discharged from the open open valve 22 flows into the auxiliary passage 20. The auxiliary passage 20 is provided so that the inflowing ammonia gas is supplied to the exhaust catalyst 5.

[0057] The operation of this embodiment will be described below. 6, when the operator moves the needle 22b from the first position to the second position, the open valve 22 opens. Then, the second connection path 11b and the auxiliary path 20 communicate with each other via the valve chamber 22c of the open valve 22, and ammonia gas is discharged from the second connection path 11b to the auxiliary path 20. The ammonia gas discharged to the auxiliary path 20 is supplied to the exhaust catalyst 5. The ammonia gas supplied to the exhaust catalyst 5 via the auxiliary path 20 is adsorbed and oxidized by the exhaust catalyst 5.

[0058] The ammonia engine system 1 according to the third embodiment has the following advantages in addition to the advantages described in (1-2) of the first embodiment. (3-1) An open valve 22 is disposed in the connection path 11, and an auxiliary path 20 is connected to the open valve 22. When the open valve 22 opens, ammonia gas is discharged from the second connection path 11b to the auxiliary path 20. The ammonia gas discharged from the connection path 11 via the open valve 22 is supplied to the exhaust catalyst 5 via the auxiliary path 20, so that the ammonia gas discharged from the second connection path 11b can be adsorbed and oxidized by the exhaust catalyst 5. Therefore, the ammonia gas discharged from the ammonia supplier 13 can be appropriately treated.

[0059] This embodiment can be modified as follows: This embodiment and the following modifications can be combined and implemented within the scope of technical compatibility. In the above embodiments, the ammonia amount adjustment unit is the injector 6, but this is not limited to this. The ammonia amount adjustment unit may be any unit that can adjust the amount of ammonia to be discharged, such as a carburetor.

[0060] In the above embodiments, the other end of the auxiliary passage 20 is connected to the exhaust catalyst 5. However, this is not limited to this. The other end of the auxiliary passage 20 may be connected to a stage upstream of the exhaust catalyst 5 in the exhaust passage 4. In this configuration, the ammonia gas discharged from the ammonia supply unit 13 is supplied to the exhaust catalyst 5 via the auxiliary passage 20 and the exhaust passage 4.

[0061] In the second embodiment, the connection between the tank-side connection end 12a and the path-side connection end 11c is disconnected for maintenance of the ammonia engine system 1. However, this is not limited to this. The location that is disconnected for maintenance may be the connection between the first connection path 11a and the vaporizer 10, the connection between the vaporizer 10 and the second connection path 11b, or the like.

[0062] In the third embodiment, the release valve 22 is a needle valve, but this is not limitative. The release valve 22 may be a globe valve or a ball valve. In the above embodiments, the first embodiment, the second embodiment, and the third embodiment are described independently, but this is not limited to this. For example, the first embodiment and the second embodiment may be combined so that the ammonia engine system 1 includes both the pressure release valve 19 and the suction device 21. In this case, the ammonia engine system 1 includes two auxiliary paths 20. One auxiliary path 20 connects the pressure release valve 19 and the exhaust catalyst 5. The other auxiliary path 20 includes the suction device 21.

[0063] In the above embodiments, the ammonia supply unit 13 includes the vaporizer 10, but this is not limited to this. For example, in the first embodiment, the ammonia supply unit 13 does not need to include the vaporizer 10. In this case, the ammonia engine 2 does not include the pressure release valve 19 either. Liquid ammonia is supplied to the ammonia engine 2 from the ammonia tank 12 via the connection path 11.

[0064] In the first embodiment, pressure release valve 19 is arranged in second connection path 11b, but this is not limited to this. Pressure release valve 19 may be arranged in vaporizer 10 so as to form part of a section that defines the space in vaporizer 10 to which ammonia gas is supplied. In this case, when valve 19b is in the first position, vaporizer 10 and auxiliary path 20 are disconnected. When valve 19b is in the second position, vaporizer 10 and auxiliary path 20 are connected.

[0065] The technical ideas that can be understood from the above-described embodiment and modified examples will be described. (i) The suction device includes a suction unit and a pump. [Explanation of symbols]

[0066] 1...ammonia engine system, 2...ammonia engine, 4...exhaust path, 5...exhaust catalyst, 6...injector as ammonia amount adjustment unit, 10...carburizer, 11...connection path, 11a...first connection path, 11b...second connection path, 12...ammonia tank, 13...ammonia supply unit, 19...pressure release valve, 20...auxiliary path, 21...suction device, 22...release valve.

Claims

1. an ammonia engine to which ammonia is supplied via an ammonia amount adjusting unit capable of adjusting the amount of ammonia discharged; an ammonia tank for storing ammonia; an ammonia supply unit having a connection path connecting the ammonia amount adjuster and the ammonia tank; an exhaust path connected to the ammonia engine and into which exhaust gas from the ammonia engine flows; an exhaust catalyst provided in the exhaust path and configured to adsorb and oxidize ammonia; an auxiliary passage into which ammonia discharged from the ammonia supply unit flows and which is provided so that the ammonia that has flowed in is supplied to the exhaust catalyst; and the ammonia supply unit includes a vaporizer that vaporizes the ammonia that has flowed in from the ammonia tank, and a pressure release valve that opens when an internal pressure of the vaporizer reaches or exceeds a predetermined value, the connection path includes a first connection path that connects the ammonia tank and the vaporizer, and a second connection path that connects the vaporizer and the ammonia amount adjustment unit, the auxiliary path is connected to the ammonia supply unit so that the ammonia discharged through the pressure release valve that is open flows into the auxiliary path.

2. an ammonia engine to which ammonia is supplied via an ammonia amount adjusting unit capable of adjusting the amount of ammonia discharged; an ammonia tank for storing ammonia; an ammonia supply unit having a connection path connecting the ammonia amount adjuster and the ammonia tank; an exhaust path connected to the ammonia engine and into which exhaust gas from the ammonia engine flows; an exhaust catalyst provided in the exhaust path and configured to adsorb and oxidize ammonia; an auxiliary passage into which ammonia discharged from the ammonia supply unit flows and which is provided so that the ammonia that has flowed in is supplied to the exhaust catalyst; and The ammonia engine system includes an open valve, the open valve being provided so that the connection path and the auxiliary path communicate with each other when the open valve is opened.

3. an ammonia engine to which ammonia is supplied via an ammonia amount adjusting unit capable of adjusting the amount of ammonia discharged; an ammonia tank for storing ammonia; an ammonia supply unit having a connection path connecting the ammonia amount adjuster and the ammonia tank; an exhaust path connected to the ammonia engine and into which exhaust gas from the ammonia engine flows; an exhaust catalyst provided in the exhaust path and configured to adsorb and oxidize ammonia; an auxiliary passage into which ammonia discharged from the ammonia supply unit flows and which is provided so that the ammonia that has flowed in is supplied to the exhaust catalyst; and an ammonia engine system comprising: a suction device connected to the auxiliary path, which, when the connection path is detached from the ammonia tank, sucks in ammonia discharged from the connection path and discharges the sucked ammonia into the auxiliary path.

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