Ammonia combustion method, ammonia combustion engine, and ship equipped with the same

Abstract

To efficiently combust ammonia in an ammonia combustion engine.SOLUTION: An ammonia combustion method comprises: adjusting ammonia decomposition gas obtained by decomposing ammonia using an ammonia decomposition catalyst 14a so that an equivalent ratio of hydrogen contained in the ammonia decomposition gas is equal to or higher than a predetermined lower limit value, then supplying it to an auxiliary combustion chamber 24 communicating with a main combustion chamber 22 through an ejection hole, and igniting and combusting it under an excessive fuel condition; ejecting excessive-concentrated combustion gas mixed with unburned hydrogen from the ejection hole into the main combustion chamber 22 as a jet torch flame; and igniting and combusting premixed gas of ammonia and air supplied to the main combustion chamber 22 by the combustion of the unburned hydrogen with the jet torch flame.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an ammonia combustion method, an ammonia combustion engine, and a ship equipped with the same.

Background Art

[0002] In the marine industry, the use of ammonia, a carbon-free fuel, as a fuel for engines that can achieve the "Greenhouse Gas (GHG) Reduction Strategy" of the International Maritime Organization (IMO) has attracted attention. However, since ammonia has properties such as a slow combustion rate and difficulty in ignition, which make combustion difficult, a powerful combustion method needs to be adopted when used as an engine fuel.

[0003] In an engine that burns ammonia, a configuration is disclosed in which hydrogen gas obtained by decomposing ammonia by heating is supplied to a sub-combustion chamber, and the ammonia gas supplied to the main combustion chamber is effectively burned using the hydrogen gas with good ignitability supplied to the sub-combustion chamber (Patent Document 1).

[0004] Also, a configuration is disclosed in which a catalyst member for decomposing ammonia gas is disposed in the combustion chamber of a cylinder, the ammonia gas supplied as fuel is decomposed to obtain hydrogen gas, and the ammonia gas is burned (Patent Document 2).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] By the way, since the technology described in Patent Document 1 is configured to guide hydrogen gas and nitrogen gas obtained by heating ammonia gas into the secondary combustion chamber and ignite them, even though the ignitability of hydrogen gas is good, air is not sufficiently supplied to the secondary combustion chamber, resulting in a delay in ignition and there is a possibility that ammonia gas cannot be sufficiently burned.

[0007] Further, since the technology described in Patent Document 2 decomposes a mixed gas of ammonia gas and air with a catalytic member fixedly provided in the combustion chamber to obtain hydrogen gas and nitrogen gas, air suitable for the combustion of hydrogen gas cannot be obtained, and there is a possibility that it cannot adapt to the transient situation of the engine.

[0008] Since ammonia is flame-retardant, there is a need for a technology to more efficiently burn ammonia in the main combustion chamber even in a configuration where ammonia is efficiently decomposed and the obtained hydrogen is burned in the secondary combustion chamber.

Means for Solving the Problem

[0016] Claim 1 The ammonia combustion engine that burns ammonia corresponding to the claim includes a main combustion chamber, a secondary combustion chamber communicating with the main combustion chamber through an ejection hole, an ammonia decomposition gas supply means for supplying an ammonia decomposition gas obtained by decomposing ammonia to the secondary combustion chamber using an ammonia decomposition catalyst, an equivalence ratio adjustment means for adjusting the lower limit value of the equivalence ratio of hydrogen contained in the ammonia decomposition gas to air to a value higher than 1.4, an ignition means for igniting the hydrogen contained in the ammonia decomposition gas supplied to the secondary combustion chamber by adjusting the equivalence ratio in the equivalence ratio adjustment means, and a premixed gas supply means for supplying a premixed gas of ammonia and air to the main combustion chamber, and injecting the rich combustion gas mixed with unburned hydrogen burned in the secondary combustion chamber as a jet torch flame from the ejection hole into the main combustion chamber, and burning the premixed gas of ammonia and air supplied to the main combustion chamber by the combustion of the unburned hydrogen by the jet torch flame.

[0017] Here , front It is preferable that the equivalence ratio adjustment means adjusts the upper limit value of the equivalence ratio to 7.2 or less.

[0018] Also, it is preferable that the equivalence ratio adjustment means changes the equivalence ratio according to the Ammonia combustion load of the engine.

[0019] Also, it is preferable that the ignition means changes the timing of igniting the ammonia decomposition gas according to the Ammonia combustion load of the engine.

[0020] Also, it is preferable to provide an ammonia supply source and supply ammonia for obtaining a premixed gas of ammonia and air for generating the ammonia decomposition gas from the same ammonia supply source.

[0021] Also, it is preferable to provide heating means for heating ammonia and / or the ammonia decomposition catalyst when generating the ammonia decomposition gas.

[0022] Also, it is preferable that the heating means has a heating control unit and performs the heating from before starting the engine according to the setting. Ammonia combustion

[0023] Also, it is preferable to provide a ship equipped with the ammonia combustion engine characterized by being equipped with the above ammonia combustion engine.

Advantages of the Invention

[0032] According to the ammonia combustion engine that burns ammonia corresponding to the claim 1 , a main combustion chamber, a sub-combustion chamber communicating with the main combustion chamber through a jet hole, an ammonia decomposition gas supply means for supplying an ammonia decomposition gas obtained by decomposing ammonia using an ammonia decomposition catalyst to the sub-combustion chamber, and the equivalence ratio of hydrogen contained in the ammonia decomposition gas to air The lower limit value of which is higher than 1.4 ​An equivalence ratio adjustment means for adjusting to, an ignition means for igniting hydrogen contained in the ammonia decomposition gas supplied to the secondary combustion chamber by adjusting the equivalence ratio in the equivalence ratio adjustment means, and a premixed gas supply means for supplying a premixed gas of ammonia and air to the main combustion chamber. The rich combustion gas mixed with unburned hydrogen burned in the secondary combustion chamber is ejected from the ejection hole into the main combustion chamber as a jet torch flame, and the premixed gas of ammonia and air supplied to the main combustion chamber is burned by the combustion of the unburned hydrogen by the jet torch flame, so that ammonia can be efficiently burned in an engine that burns ammonia. That is, since the equivalence ratio of hydrogen to air is adjusted by the equivalence ratio adjustment means, the amount of air required for the combustion of hydrogen can be surely secured. Further, since the equivalence ratio is adjusted to a predetermined lower limit value or more, it is possible to eject the rich combustion gas mixed with unburned hydrogen into the main combustion chamber as a jet torch flame without completely burning hydrogen in the secondary combustion chamber.

[0033] Here, by adjusting the equivalence ratio by the equivalence ratio adjustment means to a value higher than the predetermined lower limit value of 1.4, the hydrogen remaining in the combustion in the secondary combustion chamber can be ejected into the main combustion chamber, and the ignition and combustion propagation of ammonia in the main combustion chamber can be assisted.

[0034] Further, by adjusting the equivalence ratio by the equivalence ratio adjustment means to 7.2 or less, the upper limit value of the equivalence ratio, hydrogen can be surely burned in the secondary combustion chamber below the flammable limit of hydrogen.

[0035] Further, by changing the equivalence ratio according to the load of the engine by the equivalence ratio adjustment means, the combustion of hydrogen in the secondary combustion chamber can be performed under appropriate conditions according to the load of the engine.

[0036] Further, by changing the timing of igniting the ammonia decomposition gas according to the load of the engine by the ignition means, the combustion of hydrogen contained in the ammonia decomposition gas in the secondary combustion chamber can be performed at an appropriate timing according to the load of the engine.

[0037] Further, by providing an ammonia supply source and supplying ammonia for obtaining a premixed gas of ammonia and air for generating the ammonia decomposition gas from the same ammonia supply source, the arrangement space of the ammonia supply source can be reduced.

[0038] Further, in generating the ammonia decomposition gas, by providing heating means for heating ammonia and / or the ammonia decomposition catalyst, ammonia can be effectively decomposed into an ammonia decomposition gas containing hydrogen.

[0039] Further, since the heating means has a heating control unit and performs the heating from before the start of the engine according to a setting, the ammonia decomposition gas can be quickly generated and the engine can be started stably.

[0040] Further, by providing a ship equipped with the ammonia combustion engine characterized by mounting the above ammonia combustion engine, operation using ammonia in the ship becomes possible.

Brief Description of the Drawings

[0041]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0042] As shown in FIG. 1, the ammonia combustion engine 100 in an embodiment of the present invention includes an ammonia supply source 10, a premixed gas supply means 12, an ammonia decomposition gas supply means 14, an equivalence ratio adjustment means 16, a piston 18, a cylinder 20, a main combustion chamber 22, a sub-combustion chamber 24, an ignition means 26, an ignition control means 28, and an engine load detection means 30.

[0043] Note that the ammonia combustion engine 100 can also be configured without including the ammonia supply source 10, having a main combustion chamber 22, an auxiliary combustion chamber 24, an ammonia decomposition gas supply means 14, an equivalence ratio adjustment means 16, an ignition means 26, and a premixed gas supply means 12. Further, it can also be configured to include an engine control means for integrally controlling the ammonia supply source 10, the premixed gas supply means 12, the ammonia decomposition gas supply means 14, the equivalence ratio adjustment means 16, the ignition control means 28, etc.

[0044] The application range of the ammonia combustion engine 100 is not particularly limited. For example, it can be an engine as a main engine mounted on a ship, an engine that supplies power to a generator as an auxiliary machine, etc.

[0045] The ammonia combustion engine 100 is an engine that gives power to the piston 18 by burning ammonia supplied from the ammonia supply source 10 to the main combustion chamber 22 and ammonia decomposition gas supplied to the auxiliary combustion chamber 24.

[0046] The ammonia supply source 10 is configured to include a tank for storing ammonia (NH3) as fuel, a pump for supplying the premixed gas supply means 12 and the ammonia decomposition gas supply means 14, etc. In the ammonia combustion engine 100, ammonia is supplied to the premixed gas supply means 12 and the ammonia decomposition gas supply means 14 from the same ammonia supply source 10. Thereby, the arrangement space of the ammonia supply source 10 can be reduced.

[0047] As the supply form of ammonia, various forms can be adopted, such as a form of directly supplying ammonia gas, a form of vaporizing liquid ammonia and supplying it as ammonia gas, a form of injecting liquid ammonia into the main combustion chamber 22 at high pressure for supply, etc. Also, the ammonia supplied to the main combustion chamber 22 and the auxiliary combustion chamber 24 can be configured in separate systems.

[0048] The premixed gas supply means 12 mixes the ammonia supplied from the ammonia supply source 10 with air as an oxidizing agent and supplies it to the main combustion chamber 22. Instead of air, other oxidizing agents such as oxygen-enriched air or pure oxygen may be used. Further, other auxiliary fuels such as hydrogen (H2), natural gas, LPG, etc. may be added.

[0049] The premixed gas supply means 12 is provided with a mechanism capable of adjusting the mixing ratio of ammonia and air. For example, ammonia is injected by a fuel injector into the air flow during the intake of the cylinder 20 as the piston 18 descends to form a premixed gas. Further, an ammonia injector and an air injector are respectively provided for the premixed chamber, and the relationship between the pressure in the premixed chamber and the mixing ratio in the premixed chamber with respect to the pressure and injection time of each injector is investigated in advance and made into a map, and the ammonia and air are injected at the pressure and injection time of the injector so as to obtain the target mixing ratio according to the current pressure in the premixed chamber. Further, a flow meter for ammonia and a flow meter for air may be provided for the premixed chamber, and the ratio of the flow rate of ammonia and the flow rate of air may be adjusted so as to obtain the target mixing ratio. The target value of the mixing ratio is set according to, for example, the output torque and rotational speed of the ammonia combustion engine 100 detected by the engine load detection means 30 described later.

[0050] The ammonia decomposition gas supply means 14 decomposes the ammonia supplied from the ammonia supply source 10 to generate an ammonia decomposition gas containing hydrogen (H2) and nitrogen (N2). The ammonia decomposition gas supply means 14 supplies the ammonia decomposition gas containing hydrogen (H2) and nitrogen (N2) generated by the decomposition to the equivalence ratio adjusting means 16. Note that the ammonia remaining without being decomposed may be included in the equivalence ratio adjusting means 16.

[0051] As a method for decomposing ammonia, a method using an ammonia decomposition catalyst 14a can be applied. As the ammonia decomposition catalyst 14a, a ruthenium (Ru)-based catalyst, for example, a ruthenium oxide supported on aluminum oxide catalyst (RuO2 / γ-Al2O3 catalyst) can be used. However, the ammonia decomposition catalyst 14a is not limited to this, and other catalysts may be applied.

[0052] In order to obtain a high decomposition rate of ammonia by the ammonia decomposition catalyst 14a, heating at about 400°C to 500°C is required. Therefore, it is preferable to provide a heating means 14b for heating the ammonia decomposition catalyst 14a in the ammonia decomposition gas supply means 14. The heating means 14b heats the ammonia decomposition catalyst 14a at a temperature adjusted by a heating control unit 14c equipped with a temperature control element or the like. Examples of the heating method of the ammonia decomposition catalyst 14a include a method of utilizing the heat of the exhaust gas from the ammonia combustion engine 100 and a method of utilizing electric heating. Further, an auto-thermal-cracker (ATC) that reacts with a catalyst while heating by supplying air to ammonia and causing partial combustion may be used. Note that the heating means 14b may be configured by combining these methods. When supplying ammonia gas from the ammonia supply source 10, the ammonia supply source 10 also serves as the ammonia decomposition gas supply means 14, and the heating means 14b can be omitted.

[0053] Note that the method for decomposing ammonia is not limited to the method using the ammonia decomposition catalyst 14a, and other methods such as simple thermal decomposition may be applied.

[0054] Further, a filter for removing nitrogen (N2) unnecessary for combustion may be provided in the path between the equivalence ratio adjusting means 16 and the secondary combustion chamber 24. By removing nitrogen (N2) contained in the ammonia decomposition gas, the concentration of hydrogen (H2) can be increased. As a result, the combustion of the ammonia decomposition gas in the secondary combustion chamber 24 may be more activated.

[0055] The equivalence ratio adjustment means 16 mixes air serving as an oxidizer with the ammonia decomposition gas containing hydrogen (H2) and nitrogen (N2) supplied from the ammonia decomposition gas supply means 14 and supplies the mixture to the secondary combustion chamber 24. Other oxidizers such as oxygen-enriched air or pure oxygen may be used instead of air. Further, other auxiliary fuels such as natural gas and LPG may be added.

[0056] The equivalence ratio adjustment means 16 is provided with a mechanism capable of adjusting the equivalence ratio of hydrogen (H2) contained in the ammonia decomposition gas to air. The equivalence ratio adjustment means 16 may include, for example, an injector that injects the ammonia decomposition gas into the secondary combustion chamber 24 and an injector that injects air. The relationship between the pressure in the secondary combustion chamber 24 and the equivalence ratio in the secondary combustion chamber 24 with respect to the pressure and injection time of each injector is investigated in advance and mapped, and the ammonia decomposition gas and air are injected at the pressure and injection time of the injector so as to obtain a target mixing ratio according to the current pressure in the secondary combustion chamber 24.

[0057] Since the equivalence ratio adjustment means 16 is provided to adjust the equivalence ratio of hydrogen (H2) to air, the amount of air required for the combustion of hydrogen can be surely ensured. Note that the equivalence ratio of hydrogen (H2) to air is strictly the equivalence ratio determined from hydrogen (H2) contained in the ammonia decomposition gas and air.

[0058] Further, a flow meter for the ammonia decomposition gas and a flow meter for air may be provided for the secondary combustion chamber 24, and the ratio of the flow rate of the ammonia decomposition gas to the flow rate of air may be adjusted so as to obtain a target mixing ratio.

[0059] Figure 2 shows the ignition temperature, minimum ignition energy, combustion speed, and flammable limit equivalence ratio on the fuel-rich side for various fuels. Hydrogen (H2) contained in the ammonia decomposition gas has an ignition temperature of 500 °C, which is lower than that of natural gas at 537 °C and ammonia at 651 °C, and can be ignited at a lower temperature. Also, hydrogen (H2) has a minimum ignition energy of 0.015 mJ and can be ignited with a lower input energy compared to 0.29 mJ for natural gas and 8.0 mJ for ammonia. Additionally, hydrogen (H2) has a (laminar) combustion speed of 291 cm / sec, which is faster than that of natural gas at 37 cm / sec and ammonia at 7 cm / sec, making it suitable for igniting other fuels.

[0060] Furthermore, hydrogen (H2) has an equivalence ratio of 7.2 as the upper limit of the flammable limit when the fuel is in excess, which is higher than 2.51 for natural gas and 1.4 for ammonia. That is, hydrogen (H2) can be combusted in a state of a higher equivalence ratio, i.e., a higher fuel-rich state, compared to natural gas and ammonia.

[0061] Here, it is preferable to set the lower limit value of the equivalence ratio of hydrogen (H2) supplied to the secondary combustion chamber 24 higher than the upper limit value of the equivalence ratio of natural gas (2.51) and the upper limit value of the equivalence ratio of ammonia (1.4). When such a hydrogen (H2) mixture with a high equivalence ratio is combusted in the secondary combustion chamber 24, it becomes possible to increase the amount of hydrogen (H2) remaining in the combustion gas ejected from the secondary combustion chamber 24 to the main combustion chamber 22 compared to when natural gas or ammonia is used for combustion in the secondary combustion chamber 24. By adjusting the equivalence ratio to be equal to or higher than a predetermined lower limit value, it becomes possible to eject the secondary combustion chamber 24 as a jet torch flame of a rich combustion gas mixed with unburned hydrogen (H2) without completely combusting hydrogen (H2) in the secondary combustion chamber 24 into the main combustion chamber 22. This remaining hydrogen (H2) assists in the combustion of ammonia in the main combustion chamber 22, enabling the combustion of ammonia in the main combustion chamber 22 to occur more stably and actively.

[0062] Note that by adjusting the equivalent ratio of hydrogen (H2) to a value higher than the flammable limit equivalent ratio of ammonia, particularly a value higher than 1.49, hydrogen (H2) can be preferentially combusted in the secondary combustion chamber 24. Further, the hydrogen remaining after combustion in the secondary combustion chamber 24 can be ejected into the main combustion chamber 22, assisting the ignition and combustion propagation of ammonia in the main combustion chamber 22.

[0063] Also, it is preferable to adjust the upper limit value of the equivalent ratio to 7.2 or less. Thereby, hydrogen (H2) can be surely combusted in the secondary combustion chamber 24 below the flammable limit of hydrogen (H2).

[0064] The target value of the mixture ratio may be determined in advance, for example, as the mixture ratio required according to the output torque and rotational speed of the ammonia combustion engine 100 detected by the engine load detection means 30 described later, and set according to the target output torque and target rotational speed of the ammonia combustion engine 100 with reference to the map. Further, the timing and amount of supply of the ammonia decomposition gas and air to the secondary combustion chamber 24 may be set, for example, by estimating the mixture state at the time of ignition based on the measurement results of the air-fuel mixture state (pressure, quantity, temperature, concentration) and in-cylinder pressure of the main combustion chamber 22.

[0065] By changing the equivalent ratio according to the load of the ammonia combustion engine 100, the combustion of hydrogen (H2) in the secondary combustion chamber 24 can be carried out under appropriate conditions according to the load of the ammonia combustion engine 100.

[0066] Note that instead of injecting the ammonia decomposition gas and air into the secondary combustion chamber 24 after premixing them, a configuration may be adopted in which an injector for injecting the ammonia decomposition gas and an injector for injecting air are separately provided for the secondary combustion chamber 24.

[0067] Also, an ammonia decomposition gas supply means 14 may be arranged in the secondary combustion chamber 24, and configured to decompose ammonia by the ammonia decomposition gas supply means 14 after supplying ammonia and air into the secondary combustion chamber 24.

[0068] The main combustion chamber 22 is a combustion chamber for burning ammonia, which is the main fuel in the ammonia combustion engine 100, to generate power. The main combustion chamber 22 is a space formed between the piston 18 and the cylinder 20. Power is applied to the piston 18 by burning a mixture of ammonia and air in the main combustion chamber 22. The mixture of ammonia and air supplied to the main combustion chamber 22 is ignited by the combustion of unburned hydrogen (H2) by the high-temperature and highly active jet torch flame F ejected from the auxiliary combustion chamber 24, as shown in FIG. 3.

[0069] The auxiliary combustion chamber 24 is a combustion chamber communicated with the main combustion chamber 22 through an ejection hole. The shape, size of the auxiliary combustion chamber 24, and the aperture diameter, number, direction, etc. of the ejection hole may be set as appropriate. The auxiliary combustion chamber 24 is provided with ignition means 26 such as an ignition plug. The ignition timing by the ignition means 26 is controlled by the ignition control means 28. A mixture of ammonia decomposition gas and air is supplied to the auxiliary combustion chamber 24 from the equivalence ratio adjusting means 16, and combustion is performed by ignition by the ignition means 26. The pressure in the auxiliary combustion chamber 24 rapidly rises due to the combustion of the mixture of ammonia decomposition gas and air, and a high-temperature and highly active jet is ejected from the auxiliary combustion chamber 24 toward the main combustion chamber 22 through the ejection hole communicating the auxiliary combustion chamber 24 and the main combustion chamber 22.

[0070] The ignition means 26 is not particularly limited, and spark ignition, plasma ignition, corona ignition, laser ignition, etc. can be applied.

[0071] It is preferable to adjust the ignition timing by the ignition means 26 according to the load of the ammonia combustion engine 100. For example, the output torque and rotational speed of the ammonia combustion engine 100 are measured by the engine load detection means 30, and the ignition timing optimal for the output torque and rotational speed is set in advance as a map. Then, the ignition timing may be adjusted according to the output torque and rotational speed measured by the engine load detection means 30 with reference to the map.

[0072] By changing the timing at which the ignition means 26 ignites the ammonia decomposition gas according to the load of the ammonia combustion engine 100, the combustion of hydrogen (H2) contained in the ammonia decomposition gas in the secondary combustion chamber 24 can be carried out at an appropriate timing according to the load of the ammonia combustion engine 100.

[0073] Also, the ignition timing may be adjusted according to the measurement result of the in-cylinder pressure of the main combustion chamber 22. In this case, for example, the combustion characteristics with respect to the in-cylinder pressure may be obtained in advance, and the ignition timing may be adjusted according to the combustion characteristics from the actually measured in-cylinder pressure.

[0074] By changing the timing at which the ignition means 26 ignites the ammonia decomposition gas according to the in-cylinder pressure of the ammonia combustion engine 100, the combustion of hydrogen (H2) contained in the ammonia decomposition gas in the secondary combustion chamber 24 can be carried out at an appropriate timing according to the in-cylinder pressure of the ammonia combustion engine 100.

[0075] Also, when the ammonia combustion engine 100 is connected to a generator, the output power of the generator may be measured, and the ignition timing may be adjusted according to the measured value.

[0076] By changing the timing at which the ignition means 26 ignites the ammonia decomposition gas according to the output power of the generator connected to the ammonia combustion engine 100, the combustion of hydrogen (H2) contained in the ammonia decomposition gas in the secondary combustion chamber 24 can be carried out at an appropriate timing according to the output power of the generator.

[0077] As described above, according to the ammonia combustion engine 100, the ammonia decomposition gas obtained by previously decomposing ammonia is pre-combusted in the sub-combustion chamber 24, and the combustion gas mixed with unburned hydrogen (H2) is injected from the sub-combustion chamber 24 into the main combustion chamber 22, thereby igniting and burning the ammonia supplied to the main combustion chamber 22. By doing so, it is possible to overcome the slow combustion speed and difficulty in ignition of ammonia, improve the thermal efficiency in the ammonia combustion engine 100, and stabilize the operation. In addition, the amount of ammonia discharged from the ammonia combustion engine 100 in an unburned state can be reduced.

[0078] Further, due to the poor ignitability of ammonia, it is difficult to stably start the ammonia combustion engine 100 using only ammonia. However, by burning the ammonia decomposition gas using the sub-combustion chamber 24, the ammonia combustion engine 100 can be stably started. In this case, it is preferable to heat the heating means 14b of the ammonia decomposition gas supply means 14 from before starting the ammonia combustion engine 100 to generate the ammonia decomposition gas. Thereby, the ammonia decomposition gas can be quickly generated and the start of the ammonia combustion engine 100 can be stably performed.

Industrial Applicability

[0079] The present invention can be widely applied not only to devices that require power such as main engines and auxiliary engines of ships and generators, but also to ammonia combustion engines in the entire land and marine industry.

Explanation of Reference Numerals

[0080] 10 Ammonia supply source, 12 Premixed gas supply means, 14 Ammonia decomposition gas supply means, 14a Ammonia decomposition catalyst, 14b Heating means, 14c Heating control unit, 16 Equivalence ratio adjustment means, 18 Piston, 20 Cylinder, 22 Main combustion chamber, 24 Sub-combustion chamber, 26 Ignition means, 28 Ignition control means, 30 Engine load detection means, 100 Ammonia combustion engine.

Claims

1. An ammonia combustion engine that burns ammonia, comprising: a main combustion chamber; a sub-combustion chamber communicating with the main combustion chamber through an ejection hole; ammonia decomposition gas supply means for supplying ammonia decomposition gas obtained by decomposing ammonia using an ammonia decomposition catalyst to the sub-combustion chamber; equivalence ratio adjustment means for adjusting the lower limit value of the equivalence ratio of hydrogen in the ammonia decomposition gas to air to a value higher than 1.4; ignition means for igniting the hydrogen contained in the ammonia decomposition gas supplied to the sub-combustion chamber by adjusting the equivalence ratio in the equivalence ratio adjustment means; premixed gas supply means for supplying a premixed gas of ammonia and air to the main combustion chamber, characterized in that the rich combustion gas mixed with unburned hydrogen burned in the sub-combustion chamber is ejected from the ejection hole as a jet torch flame into the main combustion chamber, and the premixed gas of ammonia and air supplied to the main combustion chamber is burned by the combustion of the unburned hydrogen by the jet torch flame.

2. The ammonia combustion engine according to claim 1, characterized in that the equivalence ratio adjustment means adjusts the upper limit value of the equivalence ratio to 7.2 or less.

3. The ammonia combustion engine according to claim 1 or 2, characterized in that the equivalence ratio adjustment means changes the equivalence ratio according to the load of the ammonia combustion engine.

4. The ammonia combustion engine according to any one of claims 1 to 3, characterized in that the ignition means changes the timing of igniting the ammonia decomposition gas according to the load of the ammonia combustion engine.

5. Comprising an ammonia supply source, The ammonia combustion engine according to any one of claims 1 to 4, characterized in that ammonia for generating the ammonia decomposition gas and ammonia for obtaining a premixed gas of ammonia and air are supplied from the same ammonia supply source.

6. The ammonia combustion engine according to any one of claims 1 to 5, characterized in that heating means for heating ammonia and / or the ammonia decomposition catalyst is provided when generating the ammonia decomposition gas.

7. The ammonia combustion engine according to claim 6, characterized in that the heating means has a heating control unit and performs the heating from before starting the ammonia combustion engine according to a setting.

8. A ship equipped with an ammonia combustion engine, characterized in that it is equipped with the ammonia combustion engine according to any one of claims 1 to 7.

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