Engine device

Abstract

To provide an engine device capable of successfully maintaining exhaust gas properties without increasing a size of a device for purifying exhaust gas discharged from an ammonia mixed combustion engine.SOLUTION: An engine device 1 is an ammonia mixed combustion engine driven by burning main fuel containing ammonia and hydrocarbon-based auxiliary fuel. A control device 9 controls at least one of an excess air ratio of an air-fuel mixture of main fuel and air and injection timing of the auxiliary fuel so that a discharge rate of unburned ammonia and nitrogen oxide included in exhaust gas becomes a predetermined rate.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an engine device equipped with an ammonia-mixed combustion engine that operates by burning a main fuel containing at least ammonia and a hydrocarbon-based secondary fuel. [Background technology]

[0002] Conventionally, there is an engine device equipped with an ammonia co-fuel engine that operates by burning a main fuel containing at least ammonia and a hydrocarbon-based secondary fuel such as diesel oil. In the engine device, it is required to improve the properties of exhaust gas emitted from the ammonia co-fuel engine.

[0003] For example, in Patent Document 1, an exhaust purification device that purifies exhaust gas from an internal combustion engine that uses ammonia as fuel includes a catalyst that has the function of reducing nitrogen oxides and the function of oxidizing ammonia, an adsorbent arranged downstream of the catalyst and that adsorbs ammonia in the exhaust gas, an activation state detection unit that detects the activation state of the catalyst, a concentration acquisition unit that acquires the concentration of exhaust gas downstream of the adsorbent, and a control unit that controls the amount of ammonia supplied by a fuel supply unit that supplies ammonia to the internal combustion engine. When the catalyst is in an activated state, the control unit uses the exhaust gas concentration acquired by the concentration acquisition unit to control the amount of ammonia supplied so as to maintain a constant concentration of exhaust gas downstream of the adsorbent.

[0004] Furthermore, in Patent Document 2, the ammonia engine system is an ammonia engine system that includes an ammonia engine that uses ammonia as fuel, and an ammonia cracker device that includes an ammonia cracker catalyst that decomposes ammonia and generates hydrogen by decomposing the ammonia, and an ammonia oxidizer is provided between the ammonia engine and the ammonia cracker device. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2020-90894 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-121509 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in conventional ammonia co-fuel engines such as those described in Patent Document 1, a catalyst is used to reduce nitrogen oxides in the exhaust gas and oxidize ammonia, thereby purifying the exhaust gas. However, this does not control the amounts or ratios of nitrogen oxides and ammonia in the exhaust gas. Therefore, it is necessary to configure a device for purifying the exhaust gas based on the maximum values ​​of nitrogen oxides and unburned ammonia expected in the exhaust gas, which may result in an increase in the device's capacity and size. Furthermore, if the amount of ammonia supplied to such an ammonia co-fuel engine is reduced, other fuels must be added to achieve the same output, which may increase greenhouse gas (GHG) emissions and reduce product appeal.

[0007] Furthermore, in a conventional ammonia co-fuel engine such as that disclosed in Patent Document 2, ammonia is mixed with hydrogen and burned in order to improve the flame retardancy of ammonia, but no consideration is given to improving the deterioration of exhaust gas properties caused by the combustion or to purifying the exhaust gas.

[0008] An object of the present invention is to provide an engine device that can maintain good exhaust gas properties without increasing the size of a device for purifying exhaust gas emitted from an ammonia-mixed combustion engine. [Means for solving the problem]

[0009] In order to solve the above problems, the engine device of the present invention is an ammonia co-firing engine device that operates by burning a main fuel containing ammonia and a hydrocarbon-based secondary fuel, and is characterized in that at least one of the excess air ratio of the mixture of the main fuel and air and the injection timing of the secondary fuel is controlled so that the emission ratio of unburned ammonia and nitrogen oxides contained in the exhaust gas becomes a predetermined ratio. [Effects of the Invention]

[0010] According to the present invention, an engine device is provided that can maintain good exhaust gas properties without increasing the size of a device for purifying exhaust gas emitted from an ammonia co-fuel engine. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic diagram showing an engine device according to an embodiment of the present invention. [Figure 2] 1 is a schematic diagram showing an ammonia-mixed combustion engine in an engine device according to an embodiment of the present invention. FIG. [Figure 3] 1 is a graph showing, in a map, the amount of unburned ammonia in exhaust gas relative to the relationship between the injection timing of secondary fuel and the excess air ratio of main fuel in an ammonia co-fuel combustion engine. [Figure 4] 1 is a graph showing, in a map form, the amount of nitrogen oxides in exhaust gas relative to the relationship between the injection timing of secondary fuel and the excess air ratio of main fuel in an ammonia co-fuel combustion engine. [Figure 5] 1 is a graph showing, in a map, the emission ratio of unburned ammonia and nitrogen oxides in exhaust gas with respect to the relationship between the injection timing of secondary fuel and the excess air ratio of main fuel in an ammonia co-fuel combustion engine. [Figure 6] 1 is a graph showing, in a map, the amount of unburned ammonia in exhaust gas relative to the relationship between the hydrogen mixing ratio of the main fuel and the excess air ratio in an ammonia co-fuel engine. [Figure 7] 1 is a graph showing, in a map form, the amount of nitrogen oxides in exhaust gas relative to the relationship between the hydrogen mixing ratio of the main fuel and the excess air ratio in an ammonia co-fuel engine. [Figure 8] FIG. 10 is a schematic diagram showing an engine device according to another example of the present invention. [Figure 9] 1 is a graph showing a map of NO+NO2 in relation to the combustion temperature and fuel-air equivalence ratio in an ammonia co-fuel combustion engine. [Figure 10] 1 is a graph showing a map of unburned ammonia in relation to the combustion temperature and fuel-air equivalence ratio in an ammonia co-fuel combustion engine. DETAILED DESCRIPTION OF THE INVENTION

[0012] An engine device 1 according to an embodiment of the present invention will be described with reference to the drawings. As shown in Fig. 1, the engine device 1 includes an ammonia co-fuel engine 2, an intake passage 3, an exhaust passage 4, a main fuel supply device 5, and a secondary fuel supply device 6. The engine device 1 also includes a selective reduction catalyst 7, an ammonia adsorption catalyst 8, and a control device 9.

[0013] Particularly in this embodiment, the engine device 1 is an ammonia-mixed combustion engine device, and the ammonia-mixed combustion engine 2 is configured to operate by burning at least one fuel selected from a main fuel containing at least ammonia and a hydrocarbon-based secondary fuel such as diesel. A mixture of the main fuel and air is supplied to the combustion chamber 21a of each cylinder 21 of the ammonia-mixed combustion engine 2, and the mixture of the main fuel and the secondary fuel is combusted in the combustion chamber 21a. The engine device 1 controls the supply of the main fuel and the secondary fuel by a control device 9.

[0014] The main fuel supply device 5 includes an ammonia tank 11 , an ammonia supply unit 12 , an ammonia decomposition device 13 , a hydrogen tank 14 , and a hydrogen supply unit 15 .

[0015] The ammonia tank 11 is filled with ammonia, which is the main fuel, from the outside and stores it in a liquid state. The ammonia supply unit 12 is configured to have a pump and the like connected to the ammonia tank 11, and is controlled by the control device 9 to introduce ammonia from the ammonia tank 11 and supply ammonia fuel in a liquid state or a gaseous state to the ammonia injection unit 35 of the ammonia mixed-fuel engine 2.

[0016] The ammonia decomposition device 13 introduces ammonia from the ammonia tank 11, decomposes it, and reforms it to generate hydrogen fuel, and stores the gaseous hydrogen in the hydrogen tank 14. The hydrogen supply unit 15 is configured to have a pump connected to the hydrogen tank 14 and is controlled by the control device 9, and introduces hydrogen from the hydrogen tank 14 and supplies the gaseous hydrogen fuel to the hydrogen injection unit 36 ​​of the ammonia mixed combustion engine 2.

[0017] The secondary fuel supply device 6 includes a secondary fuel tank 16 and a secondary fuel supply unit 17. The secondary fuel tank 16 stores hydrocarbon-based secondary fuel such as diesel in a liquid state, and the secondary fuel supply unit 17 includes a pump and the like connected to the secondary fuel tank 16, and is controlled by the control device 9 to introduce secondary fuel from the secondary fuel tank 16 and supply the liquid secondary fuel to the secondary fuel injection unit 26 of the ammonia co-fuel engine 2.

[0018] The ammonia co-fuel engine 2 is, for example, a four-stroke engine, and is configured by including a plurality of cylinders 21 in a cylinder block 20 and a crankcase 22 (see FIG. 2). Although four cylinders 21 are shown in FIG. 1, the number of cylinders 21 is not limited to four. As shown in FIG. 2, each cylinder 21 is configured by a cylinder 23, a piston 24, and a cylinder head 25.

[0019] The cylinder 23 is formed, for example, in a cylindrical shape within the cylinder block 20, and the piston 24 is slidably housed within the cylinder 23. The cylinder head 25 is attached to the upper side of the cylinder 23, and a combustion chamber 21a is formed inside the cylinder 23 and the cylinder head 25. The cylinder head 25 is provided with a secondary fuel injection unit 26 that injects secondary fuel into the combustion chamber 21a.

[0020] For example, the secondary fuel injection unit 26 is configured with a device such as a micro-pilot type injector that injects a small amount of secondary fuel. The secondary fuel injection unit 26 has the injection amount, injection pressure, injection timing, etc. controlled by the control device 9. The secondary fuel injection unit 26 compresses and ignites the mixture of main fuel and air in the combustion chamber 21a with the hydrocarbon liquid secondary fuel, causing it to burn.

[0021] Each cylinder 23 of the multiple cylinders 21 is connected to a crankcase 22, and a crankshaft 27 is rotatably supported by the crankcase 22. A piston 24 of each cylinder 21 is connected to the crankshaft 27 via a connecting rod 28, and the reciprocating motion of the piston 24 is converted into the rotational motion of the crankshaft 27 via the connecting rod 28.

[0022] The cylinder head 25 has an intake port 29 and an exhaust port 30 that communicate with the combustion chamber 21a of the cylinder 23, and is equipped with an intake valve 31 and an exhaust valve 32 that open and close the intake port 29 and the exhaust port 30, respectively, to the combustion chamber 21a.

[0023] The intake port 29 is connected to the intake passage 3 and introduces air supplied from the intake passage 3 into the combustion chamber 21a, while the exhaust port 30 is connected to the exhaust passage 4 and discharges exhaust gas generated in the combustion chamber 21a into the exhaust passage 4. By opening the intake valve 31, a mixture of main fuel and air can be taken into the combustion chamber 21a via the intake port 29, while by opening the exhaust valve 32, exhaust gas generated in the combustion chamber 21a can be exhausted via the exhaust port 30.

[0024] The intake passage 3 is connected to the plurality of cylinders 21 of the ammonia-mixed combustion engine 2, and supplies compressed and cooled air to each cylinder 21. A mixture of air supplied from the intake passage 3 and main fuel supplied from the main fuel supply device 5 is supplied from the intake passage 3 to the combustion chamber 21a of each cylinder 21. For example, the intake passage 3 is connected to the ammonia-mixed combustion engine 2 via an intake manifold 33. The intake manifold 33 has branch passages 33a branching to the plurality of cylinders 21, and each branch passage 33a is connected to each intake port 29.

[0025] In addition, an ammonia injection unit 35 for supplying ammonia fuel as the main fuel from the main fuel supply device 5 toward each combustion chamber 21a, and a hydrogen injection unit 36 ​​for supplying hydrogen fuel are provided in the intake passage 3, the branch flow path 33a, the intake port 29, or the cylinder head 25.

[0026] The ammonia injector 35 and the hydrogen injector 36 are controlled by the control device 9 with respect to the injection amount and injection timing of ammonia fuel and hydrogen fuel. The excess air ratio in the mixture supplied to the combustion chamber 21a is controlled by controlling the air supplied from the intake passage 3 and the injection amount of ammonia fuel and hydrogen fuel by the control device 9. The ammonia injector 35 and the hydrogen injector 36 may be configured by an admission valve, an injector, or the like provided corresponding to each combustion chamber 21a and configured to inject ammonia fuel and hydrogen fuel.

[0027] 2 illustrates an example in which the ammonia injector 35 and the hydrogen injector 36 are provided in the intake manifold 33 to inject ammonia fuel or hydrogen fuel into the branch flow path 33a and supply the ammonia fuel or hydrogen fuel to the combustion chamber 21a via the intake port 29, but the present invention is not limited to this example. Alternatively, the ammonia injector 35 and the hydrogen injector 36 may be provided in the intake passage 3 to inject ammonia fuel or hydrogen fuel into the intake passage 3 and supply the ammonia fuel or hydrogen fuel to the combustion chamber 21a via the intake passage 3 or the intake port 29, or may be provided in the cylinder 23 or the cylinder head 25 to directly inject and supply the ammonia fuel or hydrogen fuel to the combustion chamber 21a.

[0028] The exhaust passage 4 is connected to the plurality of cylinders 21 of the ammonia-mixed combustion engine 2, and circulates and discharges exhaust gas generated in each cylinder 21. For example, the exhaust passage 4 is connected to the ammonia-mixed combustion engine 2 via an exhaust manifold 34. The exhaust manifold 34 has branch passages 34a that branch off to the plurality of cylinders 21, and each branch passage 34a is connected to each exhaust port 30.

[0029] The exhaust passage 4 is connected, on the downstream side in the exhaust direction, to a selective reduction catalyst 7 and an ammonia adsorption catalyst 8 for treating exhaust gas flowing through the exhaust passage 4. The selective reduction catalyst 7 and the ammonia adsorption catalyst 8 are arranged in series through the exhaust passage 4.

[0030] The selective reduction catalyst 7 is provided in the exhaust passage 4, and purifies the exhaust gas of ammonia and nitrogen oxides by selectively reducing nitrogen oxides contained in the exhaust gas flowing through the exhaust passage 4 with a reducing agent such as urea water. A reducing agent supply unit 7a that supplies reducing agent toward the selective reduction catalyst 7 is provided in the exhaust passage 4 upstream of the selective reduction catalyst 7 in the exhaust direction. The reducing agent supply unit 7a has the supply amount of reducing agent controlled by a control device 9.

[0031] For example, the selective reduction catalyst 7 reduces ammonia and nitrogen oxides by reacting them with each other at a ratio (proportion) of concentration or molar number of one to one, and the reducing agent supply unit 7a supplies the reducing agent under the control of the control device 9 so that the concentration or molar number of ammonia and nitrogen oxides introduced into the selective reduction catalyst 7 together with the exhaust gas becomes one to one.

[0032] The ammonia adsorption catalyst 8 is provided in the exhaust passage 4 upstream of the selective reduction catalyst 7 in the exhaust direction, and purifies the ammonia in the exhaust gas by adsorbing the ammonia contained in the exhaust gas flowing through the exhaust passage 4. In other words, the ammonia adsorption catalyst 8 adsorbs ammonia, thereby reducing the concentration and / or the number of moles of ammonia introduced into the selective reduction catalyst 7 by the exhaust gas.

[0033] For example, the ammonia adsorption catalyst 8 may be made of a material that adsorbs ammonia, such as activated carbon, zeolite, Prussian blue, MOF (a porous metal complex, or also called PCP (porous coordination polymer)), etc. Alternatively, the ammonia adsorption catalyst 8 may be made of a material that reacts with nitrogen oxides in addition to the function of adsorbing ammonia, such as Fe ion-exchanged zeolite or Cu ion-exchanged zeolite.

[0034] In addition, when ammonia is adsorbed on the ammonia adsorption catalyst 8, the ammonia adsorption catalyst 8 is configured so that, when exhaust gas is passed through the ammonia adsorption catalyst 8, the ammonia is desorbed from the ammonia adsorption catalyst 8 by wind force of the exhaust gas or reaction with nitrogen oxides. In this case, the ammonia adsorption catalyst 8 may be configured to be capable of desorbing ammonia at a predetermined desorption temperature or higher.

[0035] The control device 9 is a computer such as an ECU (Engine Control Unit) that controls the operation of the ammonia-mixed combustion engine 2, and is equipped with a CPU, ROM, RAM, etc., and is configured to control each part of the ammonia-mixed combustion engine 2. The control device 9 may store various programs for controlling the ammonia-mixed combustion engine 2, and control the ammonia-mixed combustion engine 2 by reading and executing the programs.

[0036] Next, supply control of the main fuel such as ammonia and hydrogen fuel and the secondary fuel such as diesel fuel in the engine device 1 will be described.

[0037] 3 to 5, the horizontal axis shows the secondary fuel injection timing supplied to combustion chamber 21a, and the vertical axis shows the excess air ratio relative to the ammonia in the mixture supplied to combustion chamber 21a. Fig. 3 shows a stable region 40 in which the ammonia co-fuel combustion engine 2 can be operated stably, relative to the secondary fuel injection timing and the excess air ratio, and also shows a map of the amount of unburned ammonia contained in the exhaust gas within stable region 40, with unburned ammonia increasing in the direction indicated by outline arrow 41. Fig. 4 shows a stable region 40 in which the ammonia co-fuel combustion engine 2 can be operated stably, relative to the secondary fuel injection timing and the excess air ratio, and also shows a map of the amount of nitrogen oxides contained in the exhaust gas within stable region 40, with nitrogen oxides increasing in the direction indicated by outline arrow 42. FIG. 5 shows a stable region 40 in which the ammonia co-fuel combustion engine 2 can be stably operated with respect to the relationship between the secondary fuel injection timing and the excess air ratio, and also shows a map of the emission ratio of unburned ammonia and nitrogen oxides contained in the exhaust gas within the stable region 40, with the ratio of ammonia to nitrogen oxides decreasing in the direction indicated by the white arrow 43 on the map.

[0038] Therefore, the control device 9 controls at least one of the excess air ratio of the main fuel mixture and the injection timing of the secondary fuel based on the relationship between the secondary fuel injection timing and the excess air ratio of the main fuel so that the emission ratio of unburned ammonia and nitrogen oxides contained in exhaust gas generated by combustion of the main fuel and the secondary fuel reaches a predetermined target ratio (a predetermined ratio that is a target value or a target range). The control device 9 controls the excess air ratio of the main fuel by controlling the supply of ammonia by the ammonia supply unit 12 and the ammonia injection unit 35 and the intake of air in the intake passage 3. The control device 9 controls the injection timing of the secondary fuel by controlling the supply of secondary fuel by the secondary fuel injection unit 26.

[0039] For example, when the rate of unburned ammonia emission is low, the control device 9 controls the excess air ratio of the main fuel to increase or decrease, or the injection timing of the secondary fuel to retard, in order to increase the unburned ammonia. When the rate of nitrogen oxide emission is low, the control device 9 controls the excess air ratio of the main fuel to increase or decrease, or the injection timing of the secondary fuel to advance, in order to increase the nitrogen oxide.

[0040] It is preferable that the engine device 1 obtains various data on the emission rates of unburned ammonia and nitrogen oxides in the exhaust gas relative to various data on the injection timing of the secondary fuel and the excess air ratio of the main fuel when the ammonia co-fuel engine 2 is operated on a trial basis in advance, thereby creating and pre-storing a map showing the emission rates of unburned ammonia and nitrogen oxides in the exhaust gas relative to the relationship between the injection timing of the secondary fuel and the excess air ratio of the main fuel within the stable region 40. Alternatively, the engine device 1 may obtain and accumulate various data on the emission rates of unburned ammonia and nitrogen oxides in the exhaust gas relative to various data on the injection timing of the secondary fuel and the excess air ratio of the main fuel when the ammonia co-fuel engine 2 is actually operated, thereby creating and pre-storing a map showing the emission rates of unburned ammonia and nitrogen oxides in the exhaust gas relative to the relationship between the injection timing of the secondary fuel and the excess air ratio of the main fuel.

[0041] The control device 9 then acquires current data on the injection timing of the secondary fuel and the excess air ratio of the main fuel, and by referring to a stored map showing the emission ratios of unburned ammonia and nitrogen oxides, calculates the amount of change in the injection timing of the secondary fuel and the excess air ratio of the main fuel required to achieve a predetermined target ratio, and controls the injection timing of the secondary fuel and the excess air ratio of the main fuel based on the amount of change.

[0042] 6 and 7, the horizontal axis represents the hydrogen mixing ratio (hydrogen mixing proportion) of the main fuel consisting of ammonia and hydrogen supplied to combustion chamber 21a, and the vertical axis represents the excess air ratio of the mixture to the main fuel supplied to combustion chamber 21a. Fig. 6 shows a stable region 40 in which the ammonia co-fuel engine 2 can be stably operated relative to the hydrogen mixing ratio and excess air ratio, and also shows a map of the amount of unburned ammonia contained in the exhaust gas within stable region 40, with the amount of unburned ammonia increasing in the direction indicated by outline arrow 44. Fig. 7 shows a stable region 40 in which the ammonia co-fuel engine 2 can be stably operated relative to the hydrogen mixing ratio and excess air ratio, and also shows a map of the amount of nitrogen oxides contained in the exhaust gas within stable region 40, with the amount of nitrogen oxides increasing in the direction indicated by outline arrow 45. Although not shown, the emission ratios of unburned ammonia and nitrogen oxides contained in the exhaust gas within the stable region in which the ammonia co-fuel engine 2 can be stably operated can also be shown in a map with respect to the relationship between the hydrogen mixing ratio and the excess air ratio, and the emission ratios that enable more stable combustion can be achieved in a predetermined direction on the map.

[0043] Therefore, the control device 9 controls the mixture ratio of ammonia and hydrogen in the main fuel (ammonia mixture ratio or hydrogen mixture ratio) based on the relationship between the hydrogen mixture ratio of the main fuel and the excess air ratio, instead of controlling the excess air ratio of the main fuel mixture or the injection timing of the secondary fuel, so that the emission ratio of unburned ammonia and nitrogen oxides contained in exhaust gas generated by combustion of the main fuel and secondary fuel reaches a predetermined target ratio (a predetermined ratio that is a target value or a target range). The control device 9 controls the mixture ratio of the main fuel by controlling the supply of ammonia by the ammonia injection unit 35 and the supply of hydrogen by the hydrogen injection unit 36.

[0044] For example, when the emission rate of unburned ammonia is low, the control device 9 controls the main fuel to increase the ammonia mixing rate (ammonia mixing rate) or decrease the hydrogen mixing rate (hydrogen mixing rate) in order to increase the unburned ammonia.When the emission rate of nitrogen oxides is low, the control device 9 controls the main fuel to increase the hydrogen mixing rate (hydrogen mixing rate) or decrease the ammonia mixing rate (ammonia mixing rate) in order to increase the nitrogen oxides.

[0045] It is preferable that the engine device 1 obtains various data on the emission rates of unburned ammonia and nitrogen oxides in the exhaust gas relative to various data on the hydrogen mixing ratio of the main fuel and the excess air ratio of the main fuel when the ammonia co-fuel engine 2 is operated on a trial basis in advance, thereby creating and pre-storing a map showing the emission rates of unburned ammonia and nitrogen oxides in the exhaust gas relative to the relationship between the hydrogen mixing ratio of the main fuel and the excess air ratio of the main fuel within the stable region 40. Alternatively, the engine device 1 may obtain and store various data on the emission rates of unburned ammonia and nitrogen oxides in the exhaust gas relative to various data on the hydrogen mixing ratio of the main fuel and the excess air ratio of the main fuel when the ammonia co-fuel engine 2 is actually operated, thereby creating and pre-storing a map showing the emission rates of unburned ammonia and nitrogen oxides in the exhaust gas relative to the relationship between the hydrogen mixing ratio of the main fuel and the excess air ratio of the main fuel.

[0046] The control device 9 then acquires current data on the hydrogen mixing ratio of the main fuel and the excess air ratio of the main fuel, and by referring to a stored map showing the emission ratios of unburned ammonia and nitrogen oxides, calculates the amount of change in the hydrogen mixing ratio of the main fuel and the excess air ratio of the main fuel required to achieve the predetermined target ratio, and controls the hydrogen mixing ratio of the main fuel and the excess air ratio of the main fuel based on the amount of change.

[0047] Alternatively, the control device 9 may control at least one of the excess air ratio of the main fuel mixture, the injection timing of the secondary fuel, and the hydrogen mixing ratio of the main fuel based on the relationship between the secondary fuel injection timing and the excess air ratio in addition to the relationship between the secondary fuel injection timing and the excess air ratio so that the emission ratio of unburned ammonia and nitrogen oxides contained in the exhaust gas generated by the combustion of the main fuel and the secondary fuel reaches a predetermined target ratio.

[0048] As described above, according to the present invention, the engine system 1, which is an ammonia co-fuel engine system that operates by burning a main fuel containing ammonia and a hydrocarbon-based secondary fuel, controls at least one of the excess air ratio of the mixture of the main fuel and air and the injection timing of the secondary fuel by the control device 9 so that the emission ratio of unburned ammonia and nitrogen oxides contained in the exhaust gas becomes a predetermined target ratio (predetermined ratio).

[0049] As a result, according to the engine device 1 of the present invention, it is possible to adjust the emission rates of unburned ammonia and nitrogen oxides in the exhaust gas without changing the operating load of the ammonia co-fuel engine 2 or the ammonia input rate (supply rate) of the main fuel, thereby reducing greenhouse gas (GHG) emissions.

[0050] Alternatively, the engine device 1 generates a main fuel by mixing ammonia with hydrogen, and the control device 9 controls the mixing ratio of ammonia and hydrogen in the main fuel so that the emission ratio of unburned ammonia and nitrogen oxides contained in the exhaust gas becomes a predetermined target ratio (predetermined ratio).

[0051] As a result, according to the engine device 1 of the present invention, there is a trade-off between unburned ammonia and nitrogen oxides in the exhaust gas in terms of purification, and by adjusting the mixture ratio of ammonia and hydrogen in the main fuel, it is possible to adjust the emission ratio of unburned ammonia and nitrogen oxides in the exhaust gas.

[0052] Alternatively, the engine device 1 generates a main fuel by mixing ammonia with hydrogen, and the control device 9 controls at least one of the excess air ratio of the mixture of the main fuel and air, the injection timing of the secondary fuel, and the mixing ratio of ammonia and hydrogen in the main fuel so that the emission ratio of unburned ammonia and nitrogen oxides contained in the exhaust gas becomes a predetermined target ratio (predetermined ratio).

[0053] As a result, according to the engine device 1 of the present invention, the excess air ratio of the mixture of the main fuel and air, the injection timing of the secondary fuel, and the mixture ratio of ammonia and hydrogen in the main fuel can be appropriately combined and adjusted to more appropriately adjust the emission ratio of unburned ammonia and nitrogen oxides in the exhaust gas.

[0054] Furthermore, the engine device 1 of the present invention increases the emission rate of unburned ammonia in the emission rates of unburned ammonia and nitrogen oxides in the exhaust gas by using the control device 9 to increase or decrease the excess air ratio of the main fuel, retard the injection timing of the secondary fuel, or increase the mixing rate of ammonia in the main fuel, thereby controlling the emission rate of unburned ammonia to a predetermined target rate.

[0055] As a result, when the engine device 1 purifies exhaust gas using the selective reduction catalyst 7 or the like, if it is predicted that nitrogen oxides will be generated in the exhaust gas in an amount greater than the appropriate amount for purification, for example, greater than the capacity of the selective reduction catalyst 7, it is possible to reduce the amount of nitrogen oxide emissions and increase the amount of unburned ammonia emissions by increasing the ammonia co-firing ratio. Therefore, it is possible to generate an appropriate amount of nitrogen oxides for purification in the exhaust gas, and it is possible to properly purify the exhaust gas.

[0056] Furthermore, the engine device 1 of the present invention increases the nitrogen oxide emission rate in the emission rates of unburned ammonia and nitrogen oxide in the exhaust gas by using the control device 9 to perform at least one of increasing or decreasing the excess air ratio of the main fuel, advancing the injection timing of the secondary fuel, and increasing the hydrogen mixing rate (hydrogen mixing rate) of the main fuel, thereby controlling the nitrogen oxide emission rate to a predetermined target rate.

[0057] As a result, when the engine device 1 purifies exhaust gas using the ammonia adsorption catalyst 8 or the like, if it is predicted that more unburned ammonia than is appropriate for purification, for example, more than the capacity of the ammonia adsorption catalyst 8, will be generated in the exhaust gas, the ammonia co-firing ratio can be reduced to reduce the amount of unburned ammonia emitted and increase the amount of nitrogen oxides emitted. Therefore, it is possible to generate an appropriate amount of unburned ammonia for purification in the exhaust gas, and it is possible to properly purify the exhaust gas.

[0058] The engine device 1 of the present invention also includes a selective reduction catalyst 7 that reduces nitrogen oxides contained in the exhaust gas with a reducing agent, and an ammonia adsorption catalyst 8 that adsorbs unburned ammonia contained in the exhaust gas.

[0059] This allows the engine device 1 to adjust the emission ratio of unburned ammonia and nitrogen oxides contained in the exhaust gas in accordance with the purification of the exhaust gas by the selective reduction catalyst 7 and the ammonia adsorption catalyst 8.

[0060] Furthermore, the engine device 1 of the present invention uses the ammonia decomposition device 13 or the like to reform ammonia to produce hydrogen fuel.

[0061] This eliminates the need for the engine device 1 to store a large amount of hydrogen as fuel, and allows the engine device 1 to use hydrogen generated by reforming ammonia as the main fuel.

[0062] In the above embodiment, an example has been described in which ammonia is introduced from the ammonia tank 11 by the ammonia decomposition device 13, decomposed, and reformed to generate hydrogen fuel, and the gaseous hydrogen is stored in the hydrogen tank 14. However, the present invention is not limited to this example, and gaseous hydrogen may be filled from the outside and stored in the hydrogen tank 14.

[0063] In the above embodiment, an example has been described in which the engine device 1 generates the main fuel by mixing ammonia with hydrogen, and the control device 9 controls at least one of the excess air ratio of the mixture of the main fuel and air, the injection timing of the secondary fuel, and the mixing ratio of ammonia and hydrogen in the main fuel so that the emission ratio of unburned ammonia and nitrogen oxides contained in the exhaust gas becomes a predetermined target ratio, but the present invention is not limited to this example.

[0064] 8, the engine device 1 includes an intake throttle 50, a supercharger 51, an intercooler 52, and a recirculation device 53 (EGR device) in addition to the configuration of the above embodiment. The engine device 1 also includes an intake bypass passage 54 and a wastegate 55.

[0065] The engine device 1 is configured to increase the nitrogen oxide emission rate in the emission rates of unburned ammonia and nitrogen oxide in the exhaust gas and control the nitrogen oxide emission rate to a predetermined target rate (predetermined rate) by performing at least one of the following in addition to, or instead of, the excess air rate of the mixture, the injection timing of the secondary fuel, and the mixing ratio of the main fuel: decreasing the EGR rate of the recirculation device 53; increasing the injection pressure of the secondary fuel by the secondary fuel injection unit 26; increasing the amount of air bypassed from the intake passage 3 to the exhaust passage 4 by the intake bypass passage 54 (i.e., the intake bypass amount); increasing the opening of the wastegate 55 of the turbocharger 51; and increasing the opening of the variable nozzle 51c of the turbocharger 51.

[0066] Specifically, the engine device 1 is provided with a supercharger 51, an intercooler 52, and an intake throttle 50 in this order from the upstream side of the intake passage 3 in the intake direction.

[0067] The turbocharger 51 has a turbine 51a arranged in the exhaust passage 4 and a compressor 51b arranged in the exhaust passage 4, and the turbine 51a is provided with a variable nozzle 51c that adjusts the passage area of ​​the exhaust gas flowing through the turbine 51a. The turbocharger 51 rotates the turbine 51a with the exhaust gas flowing through the exhaust passage 4, and drives the compressor 51b with the rotational force of the turbine 51a, thereby compressing the air flowing through the intake passage 3.

[0068] The recirculation device 53 includes a recirculation passage 53a, a recirculation cooler 53b, and a recirculation valve 53c. The recirculation passage 53a is connected to the exhaust passage 4 upstream of the turbocharger 51 (turbine 51a) in the exhaust direction, and is connected to the intake passage 3 downstream of the intercooler 52 in the intake direction. The recirculation device 53 cools and recirculates exhaust gas flowing into the exhaust passage 4 upstream of the turbocharger 51 in the exhaust direction using the recirculation cooler 53b, and supplies the cooled exhaust gas to the intake passage 3 downstream of the intercooler 52 in the intake direction. The recirculation device 53 adjusts the opening of the recirculation valve 53c using the control device 9 to adjust the flow rate of the recirculated exhaust gas flowing into the intake passage 3, thereby adjusting the amount of oxygen in the air flowing into the intake passage 3.

[0069] The engine device 1 is also provided with an intake bypass passage 54 so as to bypass the downstream side of the turbocharger 51 in the intake direction of the intake passage 3 and the upstream side of the turbocharger 51 in the exhaust direction of the exhaust passage 4, and the intake bypass passage 54 is provided with an intake bypass valve 54a that adjusts the intake bypass amount. The engine device 1 is provided with a wastegate 55 so as to bypass the upstream side and downstream side of the turbocharger 51 in the exhaust direction of the exhaust passage 4, and the wastegate 55 is provided with a wastegate valve 55a that adjusts the exhaust bypass amount.

[0070] Then, the engine system 1 controls the recirculation valve 53c of the recirculation device 53 by the control device 9 to reduce the EGR rate, which is the proportion of exhaust gas recirculated from the exhaust passage 4 to the intake passage 3 by the recirculation device 53. This reduces the exhaust gas recirculated to the intake air, thereby raising the combustion temperature in the combustion chamber 21a and increasing the emission proportion of nitrogen oxides in the exhaust gas, thereby controlling the emission proportion of nitrogen oxides to a predetermined target proportion (predetermined proportion).

[0071] Alternatively, the engine system 1 controls the secondary fuel injection unit 26 by the control device 9 to increase the injection pressure of the secondary fuel injected into the combustion chamber 21a. This increases the combustion temperature in the combustion chamber 21a by burning the secondary fuel with increased injection pressure, and increases the emission rate of nitrogen oxides in the exhaust gas, controlling the emission rate of nitrogen oxides to a predetermined target rate.

[0072] Alternatively, the engine system 1 controls the intake bypass valve 54a by the control device 9 to increase the amount of intake bypass to the exhaust passage 4. This reduces the proportion of air in the intake air and increases the proportion of fuel, raising the combustion temperature in the combustion chamber 21a and increasing the emission proportion of nitrogen oxides in the exhaust gas, thereby controlling the emission proportion of nitrogen oxides to a predetermined target proportion.

[0073] Alternatively, the engine system 1 controls the wastegate valve 55a by the control device 9 to increase the opening of the wastegate 55. This increases the amount of residual gas and reduces the amount of air compressed by the turbocharger 51, thereby decreasing the proportion of air in the intake air and increasing the proportion of fuel, raising the combustion temperature in the combustion chamber 21a and increasing the emission proportion of nitrogen oxides in the exhaust gas, thereby controlling the emission proportion of nitrogen oxides to a predetermined target proportion.

[0074] Alternatively, the engine system 1 controls the variable nozzle 51c by the control device 9 to increase the opening of the variable nozzle 51c and increase the passage area of ​​the turbine 51a of the turbocharger 51. This increases the amount of residual gas and reduces the amount of air compressed by the turbocharger 51, thereby decreasing the proportion of air in the intake air and increasing the proportion of fuel, raising the combustion temperature in the combustion chamber 21a and increasing the emission proportion of nitrogen oxides in the exhaust gas, thereby controlling the emission proportion of nitrogen oxides to a predetermined target proportion.

[0075] In Fig. 9, the horizontal axis represents the combustion temperature in the combustion chamber 21a, and the vertical axis represents the fuel-air equivalence ratio of the fuel to the air in the air-fuel mixture supplied to the combustion chamber 21a. Fig. 9 shows a map of NO+NO2 contained in the exhaust gas of the engine device 1 against the relationship between the combustion temperature and the fuel-air equivalence ratio, with NO+NO2 increasing in the direction indicated by the white arrow 60. According to Fig. 9, the higher the combustion temperature, the more NO+NO2 there is.

[0076] In this way, according to another example, by performing at least one of decreasing the EGR rate, increasing the injection pressure of the secondary fuel, increasing the intake bypass amount, increasing the wastegate opening of the turbocharger 51, and increasing the variable nozzle opening of the turbocharger 51, the emission rate of nitrogen oxides in the exhaust gas can be increased and controlled to be a predetermined rate.

[0077] On the other hand, in yet another example, the engine device 1 is configured to increase the emission rate of unburned ammonia in the emission rates of unburned ammonia and nitrogen oxides in the exhaust gas and control the emission rate of unburned ammonia to a predetermined target rate (predetermined rate) by performing at least one of increasing the EGR rate of the recirculation device 53, increasing the injection pressure of the secondary fuel by the secondary fuel injection unit 26, reducing the amount of air bypassed from the intake passage 3 to the exhaust passage 4 by the intake bypass passage 54 (i.e., the intake bypass amount), reducing the opening of the wastegate 55 of the turbocharger 51, and reducing the opening of the variable nozzle 51c of the turbocharger 51, in addition to or instead of the above-mentioned excess air rate of the mixture, injection timing of the secondary fuel, and mixing ratio of the main fuel.

[0078] Specifically, the engine system 1 controls the recirculation valve 53c of the recirculation device 53 by the control device 9 to increase the EGR rate, which is the proportion of exhaust gas recirculated from the exhaust passage 4 to the intake passage 3 by the recirculation device 53. This increases the exhaust gas recirculated to the intake air, thereby lowering the combustion temperature in the combustion chamber 21a and increasing the emission proportion of unburned ammonia in the exhaust gas, thereby controlling the emission proportion of unburned ammonia to a predetermined target proportion (predetermined proportion).

[0079] Alternatively, the engine device 1 controls the secondary fuel injection unit 26 by the control device 9 to reduce the injection pressure of the secondary fuel injected into the combustion chamber 21a. As a result, the combustion temperature in the combustion chamber 21a is lowered by combustion of the secondary fuel with the reduced injection pressure, and the emission rate of unburned ammonia in the exhaust gas is increased, and the emission rate of unburned ammonia is controlled to become a predetermined target rate.

[0080] Alternatively, the engine system 1 controls the intake bypass valve 54a by the control device 9 to reduce the amount of intake bypass to the exhaust passage 4. This increases the proportion of air in the intake air and decreases the proportion of fuel, lowers the combustion temperature in the combustion chamber 21a, and increases the emission proportion of unburned ammonia in the exhaust gas, thereby controlling the emission proportion of unburned ammonia to a predetermined target proportion.

[0081] Alternatively, the engine system 1 controls the wastegate valve 55a by the control device 9 to reduce the opening of the wastegate 55. This reduces the amount of residual gas and increases the amount of air compressed by the turbocharger 51, thereby increasing the proportion of air in the intake air and decreasing the proportion of fuel, lowering the combustion temperature in the combustion chamber 21a and increasing the emission proportion of unburned ammonia in the exhaust gas, thereby controlling the emission proportion of unburned ammonia to a predetermined target proportion.

[0082] Alternatively, the engine system 1 controls the variable nozzle 51c by the control device 9 to reduce the opening of the variable nozzle 51c and reduce the passage area of ​​the turbine 51a of the turbocharger 51. This reduces the amount of residual gas and increases the amount of air compressed by the turbocharger 51, thereby increasing the proportion of air in the intake air and decreasing the proportion of fuel, lowering the combustion temperature in the combustion chamber 21a, and increasing the emission proportion of unburned ammonia in the exhaust gas, thereby controlling the emission proportion of unburned ammonia to become a predetermined target proportion.

[0083] In Fig. 10, the horizontal axis represents the combustion temperature in the combustion chamber 21a, and the vertical axis represents the fuel-air equivalence ratio of the fuel to the air in the air-fuel mixture supplied to the combustion chamber 21a. Fig. 10 shows a map of unburned ammonia contained in the exhaust gas of the engine device 1 relative to the relationship between the combustion temperature and the fuel-air equivalence ratio, with the amount of unburned ammonia increasing in the direction indicated by the white arrow 61. According to Fig. 10, the lower the combustion temperature, the more unburned ammonia there is.

[0084] In this way, according to another example, by performing at least one of increasing the EGR rate, reducing the injection pressure of the secondary fuel, reducing the intake bypass amount, reducing the wastegate opening of the turbocharger 51, and reducing the variable nozzle opening of the turbocharger 51, the emission rate of unburned ammonia in the exhaust gas can be increased and controlled to be a predetermined rate.

[0085] Furthermore, the present invention can be modified as appropriate within the scope that does not contradict the gist or idea of ​​the invention that can be read from the claims and the entire specification, and engine devices that involve such modifications are also included in the technical idea of ​​the present invention.

[0086] [Appendix to the invention] The following is a summary of the invention extracted from the above-described embodiment. Note that the configurations and processing functions described in the following supplementary notes can be selected and combined as desired.

[0087] <Appendix 1> In an ammonia co-fuel engine device that operates by burning a main fuel containing ammonia and a hydrocarbon-based secondary fuel, an engine device that controls at least one of the excess air ratio of the mixture of the main fuel and air and the injection timing of the secondary fuel so that the emission ratio of unburned ammonia and nitrogen oxides contained in the resulting exhaust gas becomes a predetermined ratio.

[0088] <Appendix 2> In an ammonia co-fuel engine device that operates by burning ammonia as a main fuel and a hydrocarbon-based auxiliary fuel, mixing the ammonia with hydrogen to produce the main fuel; An engine device characterized by controlling a mixing ratio of the ammonia and the hydrogen in the main fuel so that the emission ratios of unburned ammonia and nitrogen oxides contained in exhaust gas become predetermined ratios.

[0089] <Appendix 3> In an ammonia co-fuel engine device that operates by burning ammonia as a main fuel and a hydrocarbon-based auxiliary fuel, mixing the ammonia with hydrogen to produce the main fuel; An engine device characterized by controlling at least one of an excess air ratio of a mixture of the main fuel and air, an injection timing of the secondary fuel, and a mixture ratio of the ammonia and the hydrogen in the main fuel so that an emission ratio of unburned ammonia and nitrogen oxides contained in exhaust gas becomes a predetermined ratio.

[0090] <Appendix 4> the engine device according to appendix 3, characterized in that the emission rate of unburned ammonia in the emission rates of unburned ammonia and nitrogen oxides in the exhaust gas is increased by performing at least one of increasing or decreasing the excess air ratio, retarding the injection timing, and increasing the mixing rate of ammonia, thereby controlling the emission rate of unburned ammonia to become the predetermined rate.

[0091] <Appendix 5> 5. The engine device according to claim 3, wherein the emission ratio of nitrogen oxides in the emission ratios of unburned ammonia and nitrogen oxides in the exhaust gas is increased by performing at least one of increasing or decreasing the excess air ratio, advancing the injection timing, and increasing the mixing ratio of hydrogen, thereby controlling the emission ratio of nitrogen oxides to be the predetermined ratio.

[0092] <Appendix 6> a selective reduction catalyst that reduces the nitrogen oxides contained in the exhaust gas with a reducing agent; an ammonia adsorption catalyst that adsorbs the unburned ammonia contained in the exhaust gas; 6. The engine device according to any one of claims 1 to 5, comprising:

[0093] <Appendix 7> 6. The engine device according to any one of claims 2 to 5, wherein the hydrogen is produced by reforming the ammonia.

[0094] <Appendix 8> 4. The engine device according to claim 3, wherein the emission rate of nitrogen oxides in the emission rates of the unburned ammonia and the nitrogen oxides in the exhaust gas is increased by performing at least one of decreasing an EGR rate, increasing an injection pressure of the secondary fuel, increasing an intake bypass amount, increasing a wastegate opening of a turbocharger, and increasing an opening of a variable nozzle of the turbocharger, thereby controlling the emission rate of nitrogen oxides to be the predetermined rate.

[0095] <Appendix 9> 4. The engine device according to claim 3, wherein the emission rate of unburned ammonia in the emission rates of unburned ammonia and nitrogen oxides in the exhaust gas is increased by performing at least one of increasing an EGR rate, reducing the injection pressure of the secondary fuel, reducing an intake bypass amount, reducing a wastegate opening of a turbocharger, and reducing an opening of a variable nozzle of a turbocharger, thereby controlling the emission rate of unburned ammonia to be the predetermined rate. [Explanation of symbols]

[0096] 1 Engine equipment 2. Ammonia co-fuel engine 3 Intake passage 4 Exhaust passage 5 Main fuel supply system 6 Auxiliary fuel supply device 7. Selective reduction catalyst 7a Reducing agent supply section 8. Ammonia adsorption catalyst 9 Control Device 11 Ammonia Tank 12 Ammonia supply section 13 Ammonia decomposition unit 14 Hydrogen Tank 15 Hydrogen supply unit 16. Secondary fuel tank 17 Auxiliary fuel supply section 21 cylinders 21a Combustion chamber 26 Auxiliary fuel injection section 35 Ammonia injection section 36 Hydrogen injection section 50 intake throttle 51 Supercharger 51a Turbine 51b Compressor 51c Variable Nozzle 52 Intercooler 53 Recirculation device 53a Recirculation passage 53b Recirculation Cooler 53c Recirculation Valve 54 Intake bypass passage 54a Intake bypass valve 55 Westgate 55a Wastegate valve

Claims

1. In an ammonia co-fuel engine device that operates by burning a main fuel containing ammonia and a hydrocarbon-based secondary fuel, An engine device characterized by controlling at least one of the excess air ratio of the mixture of the main fuel and air and the injection timing of the secondary fuel so that the emission ratio of unburned ammonia and nitrogen oxides contained in the exhaust gas becomes a predetermined ratio.

2. In an ammonia co-fuel engine device that operates by burning a main fuel containing ammonia and a hydrocarbon-based secondary fuel, mixing the ammonia with hydrogen to produce the main fuel; An engine device characterized by controlling a mixing ratio of the ammonia and the hydrogen in the main fuel so that the emission ratios of unburned ammonia and nitrogen oxides contained in exhaust gas become predetermined ratios.

3. In an ammonia co-fuel engine device that operates by burning a main fuel containing ammonia and a hydrocarbon-based secondary fuel, mixing the ammonia with hydrogen to produce the main fuel; An engine device characterized by controlling at least one of an excess air ratio of a mixture of the main fuel and air, an injection timing of the secondary fuel, and a mixture ratio of the ammonia and the hydrogen in the main fuel so that an emission ratio of unburned ammonia and nitrogen oxides contained in exhaust gas becomes a predetermined ratio.

4. 4. The engine device according to claim 3, wherein the emission rate of unburned ammonia in the emission rates of unburned ammonia and nitrogen oxides in the exhaust gas is increased by performing at least one of increasing or decreasing the excess air ratio, retarding the injection timing, and increasing the mixing rate of the ammonia, thereby controlling the emission rate of unburned ammonia to become the predetermined rate.

5. 4. The engine device according to claim 3, wherein the emission ratio of nitrogen oxides in the emission ratios of unburned ammonia and nitrogen oxides in the exhaust gas is increased by performing at least one of increasing or decreasing the excess air ratio, advancing the injection timing, and increasing the mixing ratio of hydrogen, thereby controlling the emission ratio of nitrogen oxides to be the predetermined ratio.

6. a selective reduction catalyst that reduces the nitrogen oxides contained in the exhaust gas with a reducing agent; an ammonia adsorption catalyst that adsorbs the unburned ammonia contained in the exhaust gas; The engine device according to any one of claims 1 to 3, further comprising:

7. 4. The engine device according to claim 2, wherein the hydrogen is produced by reforming the ammonia.

8. 4. The engine device according to claim 3, wherein the emission rate of nitrogen oxides in the emission rates of unburned ammonia and nitrogen oxides in the exhaust gas is increased by performing at least one of decreasing the EGR rate, increasing the injection pressure of the secondary fuel, increasing the intake bypass amount, increasing the wastegate opening of the turbocharger, and increasing the variable nozzle opening of the turbocharger, thereby controlling the emission rate of nitrogen oxides to become the predetermined rate.

9. 4. The engine device according to claim 3, wherein the emission rate of unburned ammonia in the emission rates of unburned ammonia and nitrogen oxides in the exhaust gas is increased by performing at least one of increasing an EGR rate, reducing an injection pressure of the secondary fuel, reducing an intake bypass amount, reducing a wastegate opening of a turbocharger, and reducing an opening of a variable nozzle of the turbocharger, thereby controlling the emission rate of unburned ammonia to become the predetermined rate.

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