Denitration system and denitration method for tail gas of ammonia fuel engine

Abstract

The invention relates to the technical field of ship engine tail gas treatment, and discloses a denitration system and a denitration method for ammonia fuel engine tail gas. The denitration system comprises an ammonia fuel engine and a denitration device, the liquid ammonia fuel supply device is connected with the ammonia fuel engine through a supply pipeline and is used for supplying ammonia fuel to the ammonia fuel engine; a gas inlet of the ammonia gas buffer tank is connected with the supply pipeline, and the ammonia gas buffer tank is used for collecting unburned ammonia gas generated in the supply pipeline; the ammonia water preparation device is connected with a gas outlet of the ammonia gas buffer tank; and the tail gas denitration device is connected with an outlet of the ammonia water preparation device and an exhaust port of the ammonia fuel engine. The ammonia water is prepared from the unburned ammonia gas, and the prepared ammonia water is used for subsequent reduction of nitrogen oxides in tail gas of an ammonia fuel engine, so that the treatment problem of the unburned ammonia gas can be solved, and meanwhile, the consumption of a reducing agent is reduced. In addition, the ammonia water can replace part of the reducing agent, so that the storage amount of the reducing agent can be reduced, and the ship space occupied by the reducing agent is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of ship engine exhaust gas treatment, and particularly relates to a denitration system and a denitration method for the exhaust gas of an ammonia fuel engine. Background Art

[0002] Since ammonia fuel ship engines can reduce carbon dioxide emissions, the application technology of ship ammonia fuel is currently the key development direction of ship power.

[0003] Since the emission products of ammonia fuel ship engines contain more nitrogen oxides, exhaust gas denitration devices are usually equipped on ships at present. In the exhaust gas denitration device, nitrogen oxides are reduced to nitrogen and water by using a reducing agent (for example, urea) and a catalyst, thereby greatly reducing the emission amount of nitrogen oxides. However, since ammonia fuel ship engines need to operate continuously for a long time, it is necessary to reserve a sufficient amount of reducing agent on the ship in advance. However, reserving a large amount of reducing agent in advance will not only occupy the limited space on the ship, but also increase the upfront procurement cost. Summary of the Invention

[0004] In view of this, the present invention provides a denitration system and a denitration method for the exhaust gas of an ammonia fuel engine to solve the problems mentioned in the background art.

[0005] In a first aspect, the present invention provides an ammonia fuel engine exhaust gas denitration system, including:

[0006] An ammonia fuel engine;

[0007] A liquid ammonia fuel supply device, connected to the ammonia fuel engine through a supply pipeline, for supplying ammonia fuel to the ammonia fuel engine;

[0008] An ammonia gas buffer tank, with an intake port connected to the supply pipeline, for collecting unburned ammonia gas generated in the supply pipeline;

[0009] An ammonia water preparation device, connected to the outlet of the ammonia gas buffer tank;

[0010] An exhaust gas denitration device, connected to the outlet of the ammonia water preparation device and the exhaust port of the ammonia fuel engine.

[0011] Beneficial effects: The present invention utilizes an ammonia buffer tank to collect unburned ammonia generated in the supply pipeline, which not only avoids the direct emission of ammonia and reduces pollution to the environment, but also realizes the recycling and reuse of resources, improves the utilization rate of ammonia fuel, and reduces operating costs. Secondly, the collected ammonia is transported to an ammonia water preparation device, so that the ammonia that may have been wasted or difficult to handle is converted into ammonia water that is easier to store, transport and use. The state of the ammonia water is relatively stable, which reduces the safety risks of subsequent operations. Finally, the prepared ammonia water is transported to the exhaust gas denitrification device to treat the exhaust gas of the ammonia fuel engine, which can not only effectively remove harmful components such as nitrogen oxides in the exhaust gas, but also solve the problem of handling unburned ammonia, reduce the consumption of the original reducing agent, and improve economic efficiency. In addition, since ammonia water can replace part of the consumption of the reducing agent, the reserve amount of the reducing agent can also be reduced, thereby reducing the space occupied by the reducing agent on the ship.

[0012] In an optional embodiment, the ammonia water preparation device includes a washing cabinet and a fresh water supply device connected to the washing cabinet, the washing cabinet is connected to the gas outlet of the ammonia buffer tank, and the outlet of the washing cabinet is connected to the exhaust gas denitrification device.

[0013] Beneficial Effects: The present invention delivers both ammonia gas and fresh water into the washing cabinet, allowing the ammonia gas and fresh water to react and mix to produce ammonia water. Compared to ammonia gas, when ammonia gas is converted into ammonia water, its state is relatively more stable, making it easier to transport and store.

[0014] In an optional embodiment, the washing cabinet is provided with an ammonia concentration detection device, and the ammonia concentration detection device is used to detect the ammonia concentration in the washing cabinet.

[0015] Beneficial effect: By arranging an ammonia concentration detection device on the washing cabinet, the present invention enables the operator to accurately regulate the fresh water injection amount of the fresh water supply device or the ammonia flow input into the ammonia buffer tank according to the real-time concentration data of the ammonia water in the washing cabinet, so as to ensure that the output ammonia concentration is always maintained within the optimal working concentration range required by the exhaust gas denitrification device.

[0016] In an optional embodiment, a reflux port is provided on the bottom and / or side wall of the washing cabinet, and a spray port is provided on the top of the washing cabinet. The reflux port is connected to the spray port through a reflux pipeline and a reflux pump provided on the reflux pipeline.

[0017] Beneficial Effects: By providing reflux ports on the bottom and / or sidewalls of the washing cabinet and spray ports on the top, and connecting them with a reflux pipe and reflux pump, the present invention circulates the liquid within the washing cabinet. This circulation process allows ammonia gas and fresh water to more fully contact and react, increasing the concentration of the prepared ammonia water.

[0018] In an alternative embodiment, the fresh water supply device includes a fresh water storage device and a fresh water pump connected to the fresh water storage device. The fresh water pump is connected to the washing cabinet through a fresh water delivery pipeline; one end of the fresh water delivery pipeline is provided with a first spray head, and the first spray head extends into the interior of the washing cabinet.

[0019] Advantageous effects: By providing a fresh water pump, the operator can flexibly adjust the amount of fresh water delivered into the washing cabinet. Specifically, when it is necessary to increase the ammonia water concentration, the fresh water delivery volume is reduced; if it is necessary to dilute the ammonia water, the delivery volume is increased to ensure that the ammonia water concentration is always maintained within a suitable range. The first spray head at one end of the fresh water delivery pipeline extends into the interior of the washing cabinet, and can evenly disperse the fresh water in the form of spraying in the washing cabinet, increasing the contact area between the fresh water and ammonia gas, promoting the reaction speed between the two, and improving the production efficiency and quality of ammonia water.

[0020] In an alternative embodiment, a first regulating valve and a first flow meter are further provided on the fresh water delivery pipeline.

[0021] Advantageous effects: By providing a first regulating valve and a first flow meter on the fresh water delivery pipeline, precise quantitative control and dynamic adjustment of fresh water can be achieved, which helps to maintain the stability of the ammonia water concentration in the washing cabinet and ensure that the quality of ammonia water meets the working requirements of the tail gas denitration device.

[0022] In an alternative embodiment, an ammonia water storage tank is further included. The inlet of the ammonia water storage tank is connected to the outlet of the tail gas denitration device through a first ammonia water delivery pipeline, and the outlet of the ammonia water storage tank is connected to the tail gas denitration device through a second ammonia water delivery pipeline.

[0023] Advantageous effects: By providing an ammonia water storage tank between the ammonia water preparation device and the tail gas denitration device, the ammonia water produced by the ammonia water preparation device can be temporarily stored in the storage tank to buffer the rate difference between ammonia water preparation and denitration use. Specifically, when the ammonia water production rate of the preparation device is relatively fast and the consumption rate of the denitration device is relatively slow, the excess ammonia water can be stored; conversely, when the denitration demand surges, the ammonia water stored in the storage tank can be quickly replenished.

[0024] In an alternative embodiment, an ammonia water pump, a second regulating valve and a second flow meter are provided on the second ammonia water delivery pipeline; one end of the second ammonia water delivery pipeline is provided with a second spray head, and the second spray head extends into the interior of the tail gas denitration device.

[0025] Beneficial effects: The ammonia pump can ensure the continuous and smooth delivery of ammonia water to the tail gas denitration device, guaranteeing the uninterrupted progress of the denitration work. The second flowmeter can monitor the flow data of ammonia water in real time. In cooperation with the second regulating valve, operators can accurately adjust the delivery volume of ammonia water according to the actual content of nitrogen oxides in the tail gas and the specific requirements of the denitration reaction. When the concentration of nitrogen oxides in the tail gas is high, the second regulating valve is opened wider to increase the delivery volume of ammonia water; when the concentration is low, it is correspondingly reduced, achieving precise control, avoiding waste or insufficient supply of ammonia water, reducing the operating cost while improving the denitration efficiency. In addition, extending the second spray head into the interior of the tail gas denitration device can evenly disperse the ammonia water in the form of spray in the tail gas, improving the efficiency of ammonia water pyrolysis into ammonia gas, and at the same time increasing the contact area between ammonia gas and nitrogen oxides, enabling the two to fully mix and quickly react, enhancing the efficiency and effect of the denitration reaction.

[0026] In a second aspect, the present invention also provides a method for denitrifying the tail gas of an ammonia fuel engine, including:

[0027] Collecting the unburned ammonia gas generated in the supply pipeline between the ammonia fuel engine and the liquid ammonia fuel supply device by using an ammonia gas buffer tank;

[0028] Transporting the ammonia gas in the ammonia gas buffer tank to an ammonia water preparation device for preparing ammonia water;

[0029] Transporting the ammonia water in the ammonia water preparation device to a tail gas denitration device for treating the tail gas of the ammonia fuel engine.

[0030] Beneficial effects: The present invention uses an ammonia gas buffer tank to collect the unburned ammonia gas generated in the supply pipeline, which not only avoids the direct emission of ammonia gas, reduces environmental pollution, but also realizes the recycling of resources, improves the utilization rate of ammonia fuel, and reduces the operating cost. Secondly, transporting the collected ammonia gas to the ammonia water preparation device converts the ammonia gas that might otherwise be wasted or difficult to handle into ammonia water that is easier to store, transport, and use. The ammonia water is relatively stable in state, reducing the safety risk of subsequent operations. Finally, transporting the prepared ammonia water to the tail gas denitration device to treat the tail gas of the ammonia fuel engine can not only effectively remove harmful components such as nitrogen oxides in the tail gas, but also reduce the consumption of the original reducing agent, improving the economy. In addition, since ammonia water can replace part of the consumption of the reducing agent, the reserve of the reducing agent can also be reduced, thereby reducing the occupation of the ship's space by the reducing agent.

[0031] In an optional embodiment, the ammonia water preparation device includes a washing cabinet and a fresh water supply device connected to the washing cabinet, and the washing cabinet is connected to the air outlet of the ammonia gas buffer tank; the step of transporting the unburned ammonia gas in the ammonia gas buffer tank to the ammonia water preparation device for preparing ammonia water further includes:

[0032] Transfer the unburned ammonia gas in the ammonia gas buffer tank to the scrubbing cabinet;

[0033] Use the fresh water supply device to transfer fresh water into the scrubbing cabinet to mix the fresh water with the unburned ammonia gas in the scrubbing cabinet.

[0034] Advantageous effects: In the present invention, fresh water and unburned ammonia gas are jointly transferred into the scrubbing cabinet, enabling the unburned ammonia gas to come into full contact with the fresh water, improving the absorption efficiency of the unburned ammonia gas, and thus contributing to the efficient and stable preparation of ammonia water. Description of the Drawings

[0035] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0036] Figure 1 It is a connection schematic diagram of a denitration system for the exhaust gas of an ammonia fuel engine according to an embodiment of the present invention.

[0037] Description of the Reference Numerals in the Drawings

[0038] 1. Ammonia fuel engine; 2. Liquid ammonia fuel supply device; 3. Supply pipeline; 4. Ammonia gas buffer tank; 5. Ammonia water preparation device; 501. Scrubbing cabinet; 5011. Return port; 5012. Spray port; 5013. Return pipeline; 502. Fresh water supply device; 5021. Fresh water transfer pipeline; 6. Denitration device for exhaust gas; 7. Ammonia water storage tank; 8. First ammonia water transfer pipeline; 9. Second ammonia water transfer pipeline; 10. Ammonia water pump; 11. Ammonia water concentration detection device. Specific Embodiments

[0039] In order to make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0040] The following will be combined with Figure 1 , to describe the embodiments of the present invention.

[0041] According to the embodiments of the present invention, on the one hand, as Figure 1As shown, an ammonia fuel engine tail gas denitration system is provided, including: an ammonia fuel engine 1, a liquid ammonia fuel supply device 2, an ammonia gas buffer tank 4, an ammonia water preparation device 5, and a tail gas denitration device 6.

[0042] Specifically, the liquid ammonia fuel supply device 2 is connected to the ammonia fuel engine 1 through a supply pipeline 3 for supplying ammonia fuel to the ammonia fuel engine 1.

[0043] The inlet of the ammonia gas buffer tank 4 is connected to the supply pipeline 3 for collecting the unburned ammonia gas generated in the supply pipeline 3; the ammonia water preparation device 5 is connected to the outlet of the ammonia gas buffer tank 4; the tail gas denitration device 6 is connected to the outlet of the ammonia water preparation device 5 and the exhaust port of the ammonia fuel engine 1.

[0044] In the embodiment of the present invention, the ammonia gas buffer tank 4 is used to collect the unburned ammonia gas generated in the supply pipeline 3, which not only avoids the direct emission of ammonia gas, reduces environmental pollution, but also realizes the recycling of resources, improves the utilization rate of ammonia fuel, and reduces the operation cost. Secondly, the collected ammonia gas is transported to the ammonia water preparation device 5, so that the ammonia gas that might otherwise be wasted or difficult to handle is converted into ammonia water that is easier to store, transport and use. The ammonia water state is relatively stable, reducing the safety risk of subsequent operations. Finally, the prepared ammonia water is transported to the tail gas denitration device 6 to treat the tail gas of the ammonia fuel engine 1, which can not only effectively remove harmful components such as nitrogen oxides in the tail gas, but also solve the problem of treating unburned ammonia gas, reduce the consumption of the original reducing agent, and improve the economy. In addition, since ammonia water can replace part of the consumption of the reducing agent, the reserve of the reducing agent can also be reduced, thereby reducing the occupation of the ship space by the reducing agent.

[0045] It should be noted that the unburned ammonia gas referred to in this embodiment actually refers to the ammonia gas formed by the evaporation of part of the liquid ammonia under the influence of the pressure difference during the process of the liquid ammonia fuel supply device 2 transporting liquid ammonia to the ammonia fuel engine 1 through the supply pipeline 3. In addition, the reason why the ammonia water preparation device 5 is not directly connected to the supply pipeline 3 is that the pressure of the liquid ammonia in the liquid ammonia fuel supply device 2 is relatively high. Therefore, by setting the ammonia gas buffer tank 4 between the supply pipeline 3 and the ammonia water preparation device 5, the ammonia gas pressure input into the ammonia water preparation device 5 can be reduced, avoiding damage to the ammonia water preparation device 5.

[0046] According to an embodiment of the present invention, as Figure 1As shown in the figure, the ammonia water preparation device 5 includes a washing cabinet 501 and a fresh water supply device 502 connected to the washing cabinet 501. The washing cabinet 501 is connected to the air outlet of the ammonia buffer tank 4, and the outlet of the washing cabinet 501 is connected to the tail gas denitrification device 6. In the embodiment of the present invention, the unburned ammonia gas and fresh water are both transported into the washing cabinet 501, enabling the unburned ammonia gas to react with the fresh water to obtain ammonia water. Compared with ammonia gas, when ammonia gas is converted into ammonia water, its state is relatively more stable, so it can be more conveniently transported and stored.

[0047] According to an embodiment of the present invention, as Figure 1 shown in the figure, an ammonia water concentration detection device 11 is provided on the washing cabinet 501, and the ammonia water concentration detection device 11 is used to detect the ammonia water concentration in the washing cabinet 501. By providing the ammonia water concentration detection device 11 on the washing cabinet 501 in the embodiment of the present invention, operators can accurately adjust the fresh water injection volume of the fresh water supply device 502 or the ammonia gas flow rate input by the ammonia buffer tank 4 according to the real-time concentration data of the ammonia water in the washing cabinet 501, so as to ensure that the concentration of the produced ammonia water is always maintained within the optimal working concentration range required by the tail gas denitrification device 6.

[0048] According to an embodiment of the present invention, as Figure 1 shown in the figure, a reflux port 5011 is provided on the bottom and / or side wall of the washing cabinet 501, and a spray port 5012 is provided on the top of the washing cabinet 501. The reflux port 5011 is connected to the spray port 5012 through a reflux pipeline 5013 and a reflux pump provided on the reflux pipeline 5013. By providing the reflux port 5011 on the bottom and / or side wall of the washing cabinet 501, the spray port 5012 on the top, and connecting the two with the reflux pipeline 5013 and the reflux pump in the embodiment of the present invention, the liquid in the washing cabinet 501 can form a cycle. This cycle process can enable the unburned ammonia gas to contact and react with the fresh water more fully, improving the concentration of the prepared ammonia water.

[0049] According to an embodiment of the present invention, as Figure 1As shown, the fresh water supply device 502 includes a fresh water storage device and a fresh water pump connected to the fresh water storage device. The fresh water pump is connected to the washing cabinet 501 through a fresh water delivery pipeline 5021; one end of the fresh water delivery pipeline 5021 is provided with a first spray head, and the first spray head extends into the interior of the washing cabinet 501. In the embodiment of the present invention, by setting the fresh water pump, the operator can flexibly adjust the amount of fresh water delivered into the washing cabinet 501. Specifically, when it is necessary to increase the ammonia water concentration, the fresh water delivery volume is reduced; if it is necessary to dilute the ammonia water, the delivery volume is increased to ensure that the ammonia water concentration is always maintained within a suitable range. The first spray head at one end of the fresh water delivery pipeline 5021 extends into the interior of the washing cabinet 501, and can evenly disperse the fresh water in the form of spraying in the washing cabinet 501, increasing the contact area between the fresh water and the unburned ammonia gas, promoting the reaction speed between the two, and improving the production efficiency and quality of the ammonia water.

[0050] According to an embodiment of the present invention, a first regulating valve and a first flow meter are further provided on the fresh water delivery pipeline 5021. By setting the first regulating valve and the first flow meter on the fresh water delivery pipeline 5021 in the embodiment of the present invention, precise quantitative control and dynamic regulation of fresh water can be achieved, which helps to maintain the stability of the ammonia water concentration in the washing cabinet 501 and ensure that the ammonia water quality meets the working requirements of the tail gas denitration device 6.

[0051] According to an embodiment of the present invention, as Figure 1 shown, it further includes an ammonia water storage tank 7. The inlet of the ammonia water storage tank 7 is connected to the outlet of the ammonia water preparation device 5 through a first ammonia water delivery pipeline 8, and the outlet of the ammonia water storage tank 7 is connected to the tail gas denitration device 6 through a second ammonia water delivery pipeline 9. By setting the ammonia water storage tank 7 between the ammonia water preparation device 5 and the tail gas denitration device 6 in the embodiment of the present invention, the ammonia water produced by the ammonia water preparation device 5 can be temporarily stored in the storage tank to buffer the rate difference between ammonia water preparation and denitration use. Specifically, when the ammonia water production rate of the preparation device is fast and the consumption rate of the denitration device is slow, the excess ammonia water can be stored; on the contrary, when the denitration demand surges, the ammonia water stored in the storage tank can be quickly replenished.

[0052] According to an embodiment of the present invention, on the second ammonia water conveying pipeline 9, an ammonia water pump 10, a second regulating valve, and a second flowmeter are provided; one end of the second ammonia water conveying pipeline 9 is provided with a second spray head, and the second spray head extends into the interior of the tail gas denitration device 6. It can be understood that the ammonia water pump 10 can ensure that the ammonia water can be continuously and smoothly conveyed to the tail gas denitration device 6 to ensure the uninterrupted progress of the denitration work. The second flowmeter can real-time monitor the flow data of the ammonia water. In cooperation with the second regulating valve, the operator can accurately adjust the conveying amount of the ammonia water according to the actual content of nitrogen oxides in the tail gas and the specific requirements of the denitration reaction. When the concentration of nitrogen oxides in the tail gas is relatively high, the second regulating valve is opened wider to increase the conveying amount of the ammonia water; when the concentration is relatively low, it is correspondingly reduced, realizing precise control, avoiding waste or insufficient supply of the ammonia water, reducing the operation cost while improving the denitration efficiency. In addition, by extending the second spray head into the interior of the tail gas denitration device 6, the ammonia water can be evenly dispersed in the tail gas in the form of spraying, improving the efficiency of the thermal decomposition of the ammonia water into ammonia gas, and at the same time increasing the contact area between the ammonia gas and the nitrogen oxides, enabling the two to fully mix and quickly react, improving the efficiency and effect of the denitration reaction.

[0053] According to an embodiment of the present invention, on the other hand, an ammonia fuel engine tail gas denitration method is also provided, including:

[0054] Using the ammonia gas buffer tank 4 to collect the unburned ammonia gas generated in the supply pipeline 3 between the ammonia fuel engine 1 and the liquid ammonia fuel supply device 2;

[0055] Conveying the unburned ammonia gas in the ammonia gas buffer tank 4 to the ammonia water preparation device 5 for preparing ammonia water;

[0056] Conveying the ammonia water in the ammonia water preparation device 5 to the tail gas denitration device 6 for treating the tail gas of the ammonia fuel engine 1.

[0057] The embodiment of the present invention uses the ammonia gas buffer tank 4 to collect the unburned ammonia gas generated in the supply pipeline 3, which not only avoids the direct emission of ammonia gas, reduces environmental pollution, but also realizes the recycling of resources, improves the utilization rate of ammonia fuel, and reduces the operation cost. Secondly, conveying the collected unburned ammonia gas to the ammonia water preparation device 5 makes the ammonia gas that was originally likely to be wasted or difficult to handle into ammonia water that is easier to store, transport, and use. The ammonia water state is relatively stable, reducing the safety risk of subsequent operations. Finally, conveying the prepared ammonia water to the tail gas denitration device 6 to treat the tail gas of the ammonia fuel engine 1 can not only effectively remove harmful components such as nitrogen oxides in the tail gas, but also reduce the consumption of the original reducing agent, improving the economy. In addition, since the ammonia water can replace part of the consumption of the reducing agent, the reserve amount of the reducing agent can also be reduced, thereby reducing the occupation of the ship space by the reducing agent.

[0058] According to one embodiment of the present invention, the ammonia water preparation device 5 includes a washing cabinet 501 and a fresh water supply device 502 connected to the washing cabinet 501, and the washing cabinet 501 is connected to the gas outlet of the ammonia buffer tank 4. The step of transporting the unburned ammonia in the ammonia buffer tank 4 to the ammonia water preparation device 5 for preparing ammonia water also includes:

[0059] The unburned ammonia in the ammonia buffer tank 4 is transported to the washing cabinet 501;

[0060] Fresh water is delivered to the washing tank 501 by using the fresh water supply device 502 , and is mixed with the unburned ammonia gas in the washing tank 501 .

[0061] In the embodiment of the present invention, fresh water and unburned ammonia are delivered to the washing cabinet 501 together, so that the unburned ammonia and fresh water can be fully contacted, thereby improving the absorption efficiency of the unburned ammonia, thereby facilitating efficient and stable preparation of ammonia water.

[0062] Although the embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention. Such modifications and variations are all within the scope defined by the appended claims.

Claims

1. An ammonia fuel engine exhaust gas denitration system, characterized in that, Comprising: An ammonia fuel engine (1); A liquid ammonia fuel supply device (2), connected to the ammonia fuel engine (1) through a supply pipeline (3), for supplying ammonia fuel to the ammonia fuel engine (1); An ammonia gas buffer tank (4), with an inlet connected to the supply pipeline (3), for collecting unburned ammonia gas generated in the supply pipeline (3); An ammonia water preparation device (5), connected to the outlet of the ammonia gas buffer tank (4); An exhaust gas denitration device (6), connected to the outlet of the ammonia water preparation device (5) and the exhaust port of the ammonia fuel engine (1).

2. The ammonia fuel engine tail gas denitration system according to claim 1, characterized in that The ammonia water preparation device (5) includes a washing cabinet (501) and a fresh water supply device (502) connected to the washing cabinet (501). The washing cabinet (501) is connected to the outlet of the ammonia gas buffer tank (4), and the outlet of the washing cabinet (501) is connected to the exhaust gas denitration device (6).

3. The ammonia fuel engine tail gas denitration system according to claim 2, characterized in that, An ammonia water concentration detection device (11) is provided on the washing cabinet (501), and the ammonia water concentration detection device (11) is used to detect the ammonia water concentration in the washing cabinet (501).

4. The ammonia fuel engine tail gas denitration system according to claim 2, characterized in that, A reflux port (********) is provided on the bottom and / or side wall of the washing cabinet (501), a spray port (********) is provided on the top of the washing cabinet (501), and the reflux port (********) is connected to the spray port (********) through a reflux pipeline (********) and a reflux pump provided on the reflux pipeline (********).

5. The ammonia fuel engine tail gas denitration system according to claim 2, wherein [[ID=********]]The fresh water supply device (502) includes a fresh water storage device and a fresh water pump connected to the fresh water storage device. The fresh water pump is connected to the washing cabinet (501) through a fresh water delivery pipeline (********); one end of the fresh water delivery pipeline (********) is provided with a first spray head, and the first spray head extends into the interior of the washing cabinet (501).

6. The ammonia fuel engine tail gas denitration system according to claim 5, characterized in that, [[ID=********]]A first regulating valve and a first flow meter are also provided on the fresh water delivery pipeline (********).

7. The ammonia fuel engine exhaust gas denitration system according to any one of claims 1 to 6, characterized in that, An ammonia water storage tank (7) is further included. The inlet of the ammonia water storage tank (7) is connected to the outlet of the ammonia water preparation device (5) through a first ammonia water delivery pipeline (8), and the outlet of the ammonia water storage tank (7) is connected to the exhaust gas denitration device (6) through a second ammonia water delivery pipeline (9).

8. The ammonia fuel engine tail gas denitration system according to claim 7, characterized in that, An ammonia water pump (10), a second regulating valve, and a second flow meter are provided on the second ammonia water delivery pipeline (9); one end of the second ammonia water delivery pipeline (9) is provided with a second spray head, and the second spray head extends into the interior of the exhaust gas denitration device (6).

9. A method for denitrifying the exhaust gas of an ammonia fuel engine, characterized in that, Comprising: Collecting unburned ammonia gas generated in the supply pipeline (3) between the ammonia fuel engine (1) and the liquid ammonia fuel supply device (2) by using the ammonia gas buffer tank (4); Transporting the unburned ammonia gas in the ammonia gas buffer tank (4) to the ammonia water preparation device (5) for preparing ammonia water; Transporting the ammonia water in the ammonia water preparation device (5) to the exhaust gas denitration device (6) for treating the exhaust gas of the ammonia fuel engine (1).

10. The ammonia fuel engine tail gas denitration method according to claim 9, characterized in that, The ammonia water preparation device (5) includes a washing cabinet (501) and a fresh water supply device (502) connected to the washing cabinet (501), and the washing cabinet (501) is connected to the air outlet of the ammonia buffer tank (4); the step of transporting the unburned ammonia gas in the ammonia buffer tank (4) to the ammonia water preparation device (5) for preparing ammonia water further includes: Transporting the unburned ammonia gas in the ammonia buffer tank (4) into the washing cabinet (501); Using the fresh water supply device (502) to transport fresh water into the washing cabinet (501) to mix the fresh water with the unburned ammonia gas in the washing cabinet (501).

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