Marine ammonia fuel engine waste gas treatment system

Abstract

The utility model discloses a waste gas treatment system for a marine ammonia fuel engine. The system comprises an SCR (Selective Catalytic Reduction) reactor arranged in a pipeline of a main flow path and a catalytic oxidation reaction device arranged in a pipeline of a bypass flow path, waste gas exhausted by the marine ammonia fuel engine is divided into two paths, one path flows to a gas inlet of the SCR reactor through the main flow path, and the other path flows to the gas inlet of the SCR reactor after being subjected to a catalytic oxidation reaction through the catalytic oxidation reaction device and is exhausted from a gas outlet of the main flow path after being subjected to a reduction reaction through the SCR reactor. According to the scheme, the catalytic oxidation reaction device is arranged in the main flow path of the SCR reactor in a bypass mode, catalytic oxidation reaction is carried out on part of NH3 and N2O in flowing-in waste gas, NH3 entering the SCR reactor is reduced, part of N2O is removed, and the whole system has good simultaneous deamination and denitration performance; effective treatment of the marine ammonia fuel engine waste gas entering from the gas inlet of the main flow path is achieved.

Description

Technical Field

[0001] The utility model belongs to the technical field of marine environmental protection, and in particular relates to an exhaust gas treatment system for a marine ammonia fuel engine. Background Art

[0002] Using ammonia as a ship fuel is one of the important ways to promote the green and low-carbon development of the global shipping industry. The working principle and combustion chamber structure of ammonia fuel engines are similar to those of traditional diesel and gasoline engines. Some large two-stroke marine ammonia fuel engines use compression ignition, introducing a trace amount of diesel as a pilot oil into the cylinder to ensure the normal ignition and combustion of the ammonia fuel injected into the combustion chamber; due to the relatively poor combustion performance of ammonia and the presence of dead zones in the combustion chamber, a small amount of ammonia fuel injected into the engine combustion chamber will escape without being fully burned, resulting in the presence of escaped ammonia in the exhaust gas of ammonia fuel engines.

[0003] In addition, ammonia combustion will produce N2 (nitrogen), H2O (water), NO (nitrogen monoxide), NO2 (nitrogen dioxide) and N2O (nitrous oxide) and other substances (such as Figure 2 A large number of studies have shown that under normal operating conditions, the ammonia concentration in the exhaust gas of ammonia fueled engines is as high as about 10,000 ppm (part per million, the volume of pollutants accounts for one millionth of the volume of air), which is higher than NO and N2O. x The concentration of (nitrogen oxides) is about 10 times higher. NH3 (trihydrogen nitrate), NO, and NO2 are all gaseous pollutants that are highly harmful to the human body and need to be removed by technical means. N2O is a typical greenhouse gas. If it is emitted in large quantities, it may significantly aggravate the greenhouse effect, so it also needs to be treated. It can be seen that the simultaneous removal of the above pollutants is the key to the treatment of exhaust gas from marine ammonia fuel engines.

[0004] In related schemes, a selective catalytic reduction (SCR) system is used to remove nitrogen oxides in the exhaust gas of marine ammonia fuel engines. However, the use of the SCR system to treat the exhaust gas of marine ammonia fuel engines has the problem of residual NH3 and difficult to treat N2O.

[0005] The above contents are only used to assist in understanding the technical solution of the present utility model and do not constitute an admission that the above contents are prior art. Utility Model Content

[0006] The utility model aims to provide a marine ammonia fuel engine exhaust gas treatment system to solve the problem that there is residual NH3 and N2O that is difficult to treat when using an SCR system to treat the marine ammonia fuel engine exhaust gas, and to achieve the goal of catalytic oxidation reaction by arranging a set of catalytic oxidation reaction devices in the main flow of the SCR reactor to perform catalytic oxidation reaction on part of NH3 and N2O in the inflowing exhaust gas, thereby reducing NH3 entering the SCR reactor and removing part of N2O, so that the whole system has good simultaneous deamination and denitrification performance, and achieves the effect of effectively treating the marine ammonia fuel engine exhaust gas entering from the air inlet of the main flow.

[0007] The utility model provides an exhaust gas treatment system for a marine ammonia fuel engine, comprising: a first gas flow path and a second gas flow path; the first gas flow path is a main flow path, and an SCR reactor is arranged in a pipeline between an air inlet and an exhaust port of the main flow path; the second gas flow path is a bypass flow path, the air inlet of the bypass flow path is connected to the main flow path and is arranged behind the air inlet of the main flow path, and the exhaust port of the bypass flow path is connected to the main flow path and is arranged in front of the air inlet of the SCR reactor; A catalytic oxidation reaction device is arranged in the pipeline between the air inlet and the exhaust port of the bypass flow path; wherein the marine ammonia fuel engine exhaust gas entering from the air inlet of the main flow path is divided into two paths: one path flows to the air inlet of the SCR reactor through the main flow path, and the other path flows to the air inlet of the SCR reactor after catalytic oxidation reaction through the catalytic oxidation reaction device in the bypass flow path, the two paths of gas merge at the air inlet of the SCR reactor, and are discharged from the exhaust port of the main flow path after reduction reaction in the SCR reactor.

[0008] In some embodiments, the catalytic oxidation reaction device includes: a catalytic oxidation reactor; the catalytic oxidation reactor includes: a venturi reaction tube and a rotating magnetic field generator; wherein the front section of the venturi reaction tube serves as the air inlet of the catalytic oxidation reactor, and the rear section of the venturi reaction tube serves as the exhaust port of the catalytic oxidation reactor; the catalyst inlet is arranged above the front section of the venturi reaction tube; the rotating magnetic field generator is located at the rear section of the catalyst inlet and is arranged on the periphery of the middle part of the venturi reaction tube.

[0009] In some embodiments, the rotating magnetic field generator includes: a rotating magnetic field generating coil; the rotating magnetic field generating coil is sleeved on the periphery of the middle part of the venturi reaction tube.

[0010] In some embodiments, the catalytic oxidation reaction device also includes: an electrostatic precipitator; the catalytic oxidation reactor and the electrostatic precipitator are arranged in sequence along the gas flow direction in the bypass flow path; the air inlet of the catalytic oxidation reactor is connected to the air inlet of the bypass flow path, and the exhaust port of the catalytic oxidation reactor is connected to the air inlet of the electrostatic precipitator; the exhaust port of the electrostatic precipitator is connected to the exhaust port of the bypass flow path; a catalyst inlet is provided at the top of the catalytic oxidation reactor for adding catalyst; a catalyst outlet is provided at the bottom of the electrostatic precipitator for discharging the catalyst after the reaction.

[0011] In some embodiments, a vortex generator is disposed at a portion between an air inlet and an exhaust port of the SCR reactor.

[0012] In some embodiments, the vortex generator comprises: a vortex generating coil; wherein, when the shell and structural parts of the SCR reactor are made of non-metallic materials, the vortex generating coil is sleeved on the periphery of the portion between the air inlet and the exhaust port of the SCR reactor and is coaxially arranged with the SCR reactor; a catalyst module is arranged inside the SCR reactor; when the shell and / or structural parts of the SCR reactor are made of metal materials, the vortex generating coil is sleeved on the periphery of the catalyst module in the portion between the air inlet and the exhaust port of the SCR reactor and is coaxially arranged with the catalyst module.

[0013] In some embodiments, it also includes: a first gas concentration sensor is arranged at the air inlet of the main flow path, which is used to detect and display the gas concentration of the exhaust gas of the marine ammonia fuel engine entering from the air inlet of the main flow path; and a second gas concentration sensor is arranged at the exhaust port of the main flow path, which is used to detect and display the gas concentration of the exhaust gas discharged from the exhaust port of the main flow path.

[0014] In some embodiments, a first gas flow regulating valve is provided in the pipeline in front of the air inlet of the SCR reactor in the main flow path, for regulating the gas flow of the exhaust gas of the marine ammonia fuel engine flowing from the main flow path to the air inlet of the SCR reactor; and a second gas flow regulating valve is provided in the pipeline in front of the air inlet of the catalytic oxidation reaction device in the bypass flow path, for regulating the gas flow of the exhaust gas of the marine ammonia fuel engine flowing from the air inlet of the bypass flow path to the air inlet of the catalytic oxidation reaction device.

[0015] In some embodiments, in the pipeline of the bypass flow path, a portion where the air inlet of the bypass flow path is located and a portion where the exhaust port of the bypass flow path is located are arranged in a bent pipe.

[0016] In some embodiments, the system further comprises: an NH3 injection port; the NH3 injection port is disposed in front of the air inlet of the SCR reactor in the main flow path.

[0017] Therefore, the scheme of the utility model is to set a bypass flow path upstream of the main flow path where the SCR reactor 4 is located, and set a catalytic oxidation reaction device 10 in the bypass flow path, so that the exhaust gas entering the upstream inlet of the main flow path is divided into two paths: one path flows directly to the inlet of the SCR reactor 4, and the other path is catalytically oxidized by the catalytic oxidation reaction device 10 in the bypass flow path and then merges into the inlet of the SCR reactor 4. The two gases merge at the inlet of the SCR reactor 4 and then flow into the SCR reactor 4. After the reaction in the SCR reactor 4, they are discharged to the outlet of the main flow path; thus, by setting a set of catalytic oxidation reaction devices in the bypass main flow path of the SCR reactor, catalytic oxidation reaction is performed on part of NH3 and N2O in the inflowing exhaust gas, which can reduce NH3 entering the SCR reactor and remove part of N2O, so that the whole system has good simultaneous deamination and denitrification performance, and realizes effective treatment of the exhaust gas of the marine ammonia fuel engine entering from the air inlet of the main flow path.

[0018] Other features and advantages of the present invention will be set forth in the following description, and in part will become apparent from the description, or may be understood by practicing the present invention.

[0019] The technical solution of the utility model is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural schematic diagram of an embodiment of an exhaust gas treatment system for a marine ammonia fuel engine of the utility model;

[0021] Figure 2 Schematic diagram of the combustion reaction pathway of ammonia;

[0022] Figure 3 It is a structural schematic diagram of an embodiment of a marine SCR system;

[0023] Figure 4 The present invention is a schematic structural diagram of an embodiment of an exhaust gas treatment system for a marine ammonia fuel engine;

[0024] Figure 5 Schematic diagram of the test curve of gas concentration changing with reaction temperature when the branch flow regulating valve is in a completely closed state (i.e., the flue gas only passes through the SCR reactor);

[0025] Figure 6 It is a test curve diagram of the change of gas concentration with reaction temperature when the branch flow regulating valve is opened and the flue gas bypass volume is 20%;

[0026] Figure 7 It is a test curve diagram of the change of gas concentration with reaction temperature when the branch flow regulating valve is opened and the flue gas bypass volume is 40%;

[0027] Figure 8 It is a test curve diagram of the change of gas concentration with reaction temperature when the branch flow regulating valve is opened and the flue gas bypass volume is 60%.

[0028] In conjunction with the accompanying drawings, the reference numerals in the embodiments of the present invention are as follows:

[0029] 1, 5-gas concentration sensor; 2, 6-gas flow control valve; 3-NH3 injection port; 4-SCR reactor; 7-Venturi reaction tube, 8-rotating magnetic field generating coil, 9-electrostatic precipitator, 10-catalytic oxidation reaction device, 11-eddy current generating coil; 12-catalyst powder inlet; 13-catalyst powder outlet. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the utility model clearer, the technical solution of the utility model will be clearly and completely described below in combination with the specific embodiments of the utility model and the corresponding drawings. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0031] Consider that some ocean-going merchant ships (diesel-powered) are already equipped with SCR systems for removing nitrogen oxides from the exhaust gas of marine ammonia-fueled engines. Figure 2 Schematic diagram of the combustion reaction pathway of ammonia. Figure 3 FIG. 1 is a schematic diagram of a structure of an embodiment of a marine SCR system. The basic principle of the marine SCR system is as follows: Figure 2 and Figure 3 As shown. Figure 2 and Figure 3 As shown, the technology of removing nitrogen oxides in the exhaust gas of ammonia fueled marine engines by using a marine SCR system mainly introduces the reducing agent NH3 into the high-temperature exhaust gas, so that the reducing agent NH3 reacts with NO and NO2 in the SCR reactor to generate N2 and H2O. The relevant reactions are shown in equations (1), (2) and (3).

[0032] 2NO+4NH3+2NO2→4N2+6H2O (1);

[0033] 4NO+4NH3+O2→4N2+6H2O (2);

[0034] 6NO2+8NH3→7N2+12H2O (3).

[0035] In response to the urgent need to deal with pollutants in the exhaust gas of ammonia fuel engines, the mainstream exhaust gas technology route proposed by major marine ammonia fuel engine manufacturers around the world is still the SCR method. The main reason is that there is a large amount of NH3 in the exhaust gas of ammonia fuel engines, which can be directly used as a reducing agent in the SCR reaction, and can achieve the effect of reducing NH3, NO and NO2 emissions at the same time.

[0036] However, this technique has some disadvantages, such as:

[0037] 1. As shown in equations (1), (2) and (3), in the SCR reaction, NH3 and NO, NO2 can usually only react in a molar ratio of 1:1. However, the NH3 in the exhaust gas of an ammonia fuel engine is generally much higher than that of NO. x Therefore, there will be a large amount of residual NH3 in the exhaust gas after being treated by the SCR system.

[0038] 2. It is difficult for N2O to participate in the SCR reaction, so the SCR method has a poor effect on N2O removal.

[0039] Therefore, in view of the problem that the excess NH3 and N2O in the exhaust gas of a marine ammonia fuel engine are difficult to treat when the SCR system is used to treat the exhaust gas, the solution of the utility model proposes a marine ammonia fuel engine exhaust gas treatment system, that is, a system for treating the exhaust gas discharged by the marine ammonia fuel engine, a bypass flow path is arranged in the upstream exhaust channel of the SCR reactor (that is, the main flow path of the SCR reactor), and a set of catalytic oxidation reaction devices are arranged in the bypass flow path, which can oxidize a part of the NH3 and N2O in the exhaust gas flowing into the marine ammonia fuel engine exhaust gas treatment system into NO and NO2, which can improve or eliminate the problem of excessive NH3 in the SCR reactor, and can also remove part of N2O by catalytic oxidation, thereby solving the problem that the excess NH3 and N2O in the exhaust gas of a marine ammonia fuel engine are difficult to treat when the SCR system is used to treat the exhaust gas of a marine ammonia fuel engine, so that the whole system has good simultaneous deamination and denitrification performance, and realizes effective treatment of the exhaust gas of the marine ammonia fuel engine entering from the air inlet of the main flow path.

[0040] According to an embodiment of the utility model, a marine ammonia fuel engine exhaust gas treatment system is provided. Figure 1A schematic structural diagram of an embodiment of the device of the utility model is shown. The marine ammonia fuel engine exhaust gas treatment system is applied to the treatment of the marine ammonia fuel engine exhaust gas, and the marine ammonia fuel engine exhaust gas treatment system comprises: a first gas flow path and a second gas flow path. The first gas flow path is a mainstream flow path, and the mainstream flow path has an air inlet and an exhaust port, and an SCR reactor 4 is arranged in the pipeline between the air inlet and the exhaust port of the mainstream flow path; the SCR reactor 4 has an air inlet and an exhaust port, and the air inlet of the SCR reactor 4 is connected to the air inlet of the mainstream flow path, and the exhaust port of the SCR reactor 4 is connected to the exhaust port of the mainstream flow path.

[0041] The second gas flow path is a bypass flow path, and the bypass flow path has an air inlet and an exhaust port. The air inlet of the bypass flow path is connected to the main flow path and is arranged behind the air inlet of the main flow path, and the exhaust port of the bypass flow path is connected to the main flow path and is arranged in front of the air inlet of the SCR reactor 4. A catalytic oxidation reaction device 10 is arranged in the pipeline between the air inlet and the exhaust port of the bypass flow path; the catalytic oxidation reaction device 10 has an air inlet and an exhaust port, the air inlet of the catalytic oxidation reaction device 10 is connected to the air inlet of the bypass flow path, and the exhaust port of the catalytic oxidation reaction device 10 is connected to the exhaust port of the bypass flow path.

[0042] Among them, the marine ammonia fuel engine exhaust gas entering from the air inlet of the main flow path is divided into two paths: one path flows through the main flow path to the air inlet of the SCR reactor 4, and the other path flows to the air inlet of the SCR reactor 4 after catalytic oxidation reaction through the catalytic oxidation reaction device 10 in the bypass flow path. The two paths of gas merge at the air inlet of the SCR reactor 4 and then flow into the SCR reactor 4. The two paths of gas merge at the air inlet of the SCR reactor 4, and after reduction reaction in the SCR reactor 4, they are discharged from the exhaust port of the main flow path, thereby realizing the treatment of the marine ammonia fuel engine exhaust gas entering from the air inlet of the main flow path.

[0043] The solution of the utility model selects to set a bypass flow path in the upstream exhaust channel of the SCR reactor 4 (i.e., the main flow path of the SCR reactor 4), and sets a set of catalytic oxidation reaction devices 10 in the bypass flow path. The working principle of the marine ammonia fuel engine exhaust gas treatment system is: the exhaust gas (the exhaust gas contains NH3, NO, NO2, N2O) flowing into the marine ammonia fuel engine exhaust gas treatment system is divided into two paths: one of the exhaust gases directly enters the main flow path of the SCR reactor 4, and the other exhaust gas is first processed by the catalytic oxidation reaction device 10 in the bypass flow path, catalytically oxidizing NH3 and N2O in the bypass flow path into NO and NO2, and then re-merging into the main flow path of the SCR reactor 4, mixing with the gas in the main flow path of the SCR reactor 4 and entering the SCR reactor 4.

[0044] In the solution of the utility model, by setting a bypass flow path in the main flow path of the SCR reactor 4 and setting a catalytic oxidation reaction device 10 in the bypass flow path, a part of NH3 and N2O in the exhaust gas can be oxidized into NO and NO2, which can not only improve or eliminate the problem of excessive NH3 in the SCR reactor 4, but also remove part of N2O by catalytic oxidation. Bypass is used to guide part of the flue gas into the catalytic oxidation reaction device 10 to adjust the NH3 and NO in the exhaust gas. x ratio, thereby effectively removing NH3 and N2O in the exhaust gas of the ammonia fuel engine, so that the entire system has good simultaneous deamination and denitrification performance, and realizes effective treatment of the exhaust gas of the marine ammonia fuel engine entering from the air inlet of the main flow path.

[0045] In some embodiments, the catalytic oxidation reaction device 10 includes: a catalytic oxidation reactor; the catalytic oxidation reactor includes: a venturi reaction tube 7 and a rotating magnetic field generator; wherein the front section of the venturi reaction tube 7 serves as the air inlet of the catalytic oxidation reactor, and the rear section of the venturi reaction tube 7 serves as the exhaust port of the catalytic oxidation reactor; the catalyst inlet is arranged above the front section of the venturi reaction tube 7; the rotating magnetic field generator is located at the rear section of the catalyst inlet and is arranged at the periphery of the middle section of the venturi reaction tube 7. The middle section of the venturi reaction tube 7 is located between the front section of the venturi reaction tube 7 and the rear section of the venturi reaction tube 7.

[0046] The solution of the utility model is to set a Venturi reaction tube 7 and a rotating magnetic field generator in the catalytic oxidation reactor, and adopt a Venturi tube design to reduce the exhaust gas pressure and automatically inhale the catalyst powder. The advantage of this design is that the amount of catalyst powder added can be adaptively adjusted according to the exhaust gas flow rate; a rotating magnetic field generator is set in the middle of the Venturi tube, which is mainly used to generate a rotating magnetic field to drive the magnetic catalyst powder flow to rotate and collide, thereby improving the mixing uniformity of the gas and the catalyst powder.

[0047] In some embodiments, the rotating magnetic field generator includes: a rotating magnetic field generating coil 8 ; the rotating magnetic field generating coil 8 is sleeved on the periphery of the middle part of the venturi reaction tube 7 .

[0048] In the scheme of the utility model, the catalyst in the catalytic oxidation reaction device 10 in the marine ammonia fuel engine exhaust gas treatment system is made by loading a trace amount of precious metal components with magnetic iron oxide (Fe3O4) powder, and the inlet section of the catalytic oxidation reaction device 10 adopts a venturi tube design (such as a venturi reaction tube 7 is set at the inlet section of the catalytic oxidation reaction device 10 in the bypass flow path) to reduce the exhaust gas pressure and automatically inhale the catalyst powder. The advantage of this design is that the amount of catalyst powder added can be adaptively adjusted according to the exhaust gas flow rate. A rotating magnetic field generator (such as a rotating magnetic field generating coil 8) is set in the middle of the venturi tube, which is mainly used to generate a rotating magnetic field to drive the magnetic catalyst powder flow to rotate and collide, thereby improving the mixing uniformity of the gas and the catalyst powder. An electrostatic precipitator 9 is set behind the venturi tube for adsorbing and collecting catalyst powder, and the collected catalyst powder can be re-added to the catalyst powder inlet for recycling. A catalyst powder inlet 12 is set at the top of the front section of the venturi reaction tube 7, and a catalyst powder outlet 13 is set at the bottom of the electrostatic precipitator 9.

[0049] The rotating magnetic field generator is similar to the excitation coil structure of the AC motor. The rotating magnetic field generator is roughly in the shape of a hollow cylinder and is installed by directly sleeved on the outer side of the Venturi reaction tube 7.

[0050] Since the catalyst is a powdered magnetic iron oxide (Fe3O4), it is directly added to the high-speed airflow without the effect of a rotating magnetic field. It is mainly affected by the impact force of the airflow parallel to the incoming flow direction, which makes the catalyst powder roughly linearly distributed, which is not conducive to full contact with the gas. After the introduction of the rotating magnetic field, the catalyst entering the reactor is not only affected by the impact force of the airflow, but also by the constantly changing magnetic field force, thereby disrupting the flow direction of the powder and making its contact with the airflow more complete. The new catalytic oxidation reaction device 10 that combines a venturi tube, a rotating magnetic field generator and an electrostatic dust removal device uses a magnetic powder catalyst and has the characteristics of high catalyst utilization efficiency and adaptive reaction.

[0051] In some embodiments, the catalytic oxidation reaction device 10 further includes: an electrostatic precipitator 9; the catalytic oxidation reactor and the electrostatic precipitator 9 are sequentially arranged along the gas flow direction in the bypass flow path; the air inlet of the catalytic oxidation reactor is connected to the air inlet of the bypass flow path, and the exhaust port of the catalytic oxidation reactor is connected to the air inlet of the electrostatic precipitator 9; the exhaust port of the electrostatic precipitator 9 is connected to the exhaust port of the bypass flow path. A catalyst inlet (such as a catalyst powder inlet 12) is provided at the top of the catalytic oxidation reactor for adding catalyst; a catalyst outlet (such as a catalyst powder outlet 13) is provided at the bottom of the electrostatic precipitator 9 for discharging the catalyst after the reaction.

[0052] The solution of the utility model is to sequentially arrange a catalytic oxidation reactor and an electrostatic precipitator 9 in the catalytic oxidation reaction device 10 along the gas flow direction in the bypass flow path, and use the catalytic oxidation reactor to perform an oxidation reaction under the action of a catalyst to oxidize a part of NH3 and N2O in the exhaust gas into NO and NO2, which can not only improve or eliminate the problem of excessive NH3 in the SCR reactor 4, but also remove part of N2O through catalytic oxidation; and use the electrostatic precipitator 9 to remove dust to remove the remaining catalyst in the gas after the catalytic oxidation reaction, reduce impurities in the gas entering the SCR reactor 4, and protect the SCR reactor 4. The main function of using the electrostatic precipitator 9 to remove dust is to remove catalyst powder in the gas flow, which is beneficial to the recycling of the catalyst on the one hand, and prevents the catalyst powder from entering the SCR reactor 4 in large quantities on the other hand, thereby covering the catalyst surface in the SCR reactor 4 and weakening the catalytic effect of the catalyst in the SCR reactor 4.

[0053] In some embodiments, a vortex generator (such as a vortex generating coil 11) is provided at the portion between the air inlet and the exhaust port of the SCR reactor 4, such as a vortex generator (such as a vortex generating coil 11) is provided at the periphery of the portion between the air inlet and the exhaust port of the SCR reactor 4. Heating by the vortex generating coil 11 is more uniform than the heating effect of electric heating at the front section of the SCR reactor 4, which is conducive to sufficient heating of the catalyst.

[0054] In the scheme of the utility model, since the exhaust gas temperature of the NH3 engine may be lower than the temperature window of the SCR reactor under a lower load, the reaction effect is weakened, so the SCR reactor must have a self-heating function. Because the flue gas temperature is low under low load conditions, it may not meet the requirements of the SCR reactor 4. The eddy current heating coil is used to generate an induced current (eddy current) inside the catalyst module made of a metal matrix, so that the catalyst temperature rises to meet the reaction requirements. The eddy current heating coil is a eddy current generator. When used, an alternating current is passed through the eddy current heating coil to generate an alternating magnetic field inside the eddy current heating coil. The eddy current generator is mainly composed of a single-stage or multi-stage Helmholtz coil connected in series or in parallel; wherein, if a multi-stage Helmholtz coil is used, its arrangement is parallel and coaxial. The use of a multi-stage Helmholtz coil can increase the magnetic field strength and enhance the eddy current heating effect. In actual use, if a single stage is sufficient, use a single stage, and if a single stage is not enough, use a multi-stage. Multi-stage Helmholtz coils are arranged coaxially in parallel. On the one hand, the structure of the coils arranged coaxially in parallel is more compact, which is conducive to reducing the size of the device; on the other hand, the magnetic field directions of the coils arranged coaxially in parallel are basically consistent, which can effectively avoid the magnetic field offset loss in different directions and improve the utilization rate of the magnetic field.

[0055] In some embodiments, the eddy current generator includes: an eddy current generating coil 11. Wherein, when the shell and structural parts of the SCR reactor 4 are made of non-metallic materials, the eddy current generating coil 11 is sleeved on the periphery of the portion between the air inlet and the exhaust port of the SCR reactor 4 and is coaxially arranged with the SCR reactor 4 to prevent the magnetic field from heating the mounting parts made of metal materials, causing changes in the tightness and stress state of the parts, and affecting the structural stability; wherein, the structural parts of the SCR reactor 4 include the mounting parts on the SCR reactor 4.

[0056] A catalyst module is arranged inside the SCR reactor 4; when the shell and / or structural parts of the SCR reactor 4 are made of metal materials, the eddy current generating coil 11 is arranged on the periphery of the catalyst module in the part between the air inlet and the exhaust port of the SCR reactor 4, and is coaxially arranged with the catalyst module.

[0057] In the scheme of the utility model, the catalyst module inside the SCR reactor adopts a metal matrix, and an eddy current heating coil (such as an eddy current generating coil 11) is arranged outside the SCR reactor, and the eddy current heating coil can generate an alternating magnetic field of a certain frequency. The alternating magnetic field can act on the metal matrix catalyst, so that eddy currents are generated inside it, thereby generating heat. Compared with the electric heating wire heating in the related scheme, the method of using the eddy current heating coil to generate an alternating magnetic field of a certain frequency to generate eddy currents and generate heat has the characteristic of more uniform heating effect, which helps to make all parts of the catalyst module exert the best catalytic effect at the same time.

[0058] There are two ways to install the eddy current heating coil: one is to be sleeved on the outside of the cylindrical SCR reactor 4 and arranged coaxially with the SCR reactor 4. This installation method requires that the shell and structural parts of the SCR reactor 4 are made of non-metallic materials to avoid heating the shell and structural parts of the SCR reactor 4; the other is to be located in the shell of the SCR reactor 4, sleeved on the outside of the cylindrical catalyst module, and arranged coaxially with the catalyst module so that the alternating magnetic field mainly acts on the catalyst module rather than the shell. Among them, the coaxial arrangement allows the alternating magnetic field to act directly on the catalyst, and basically does not heat the structural parts, and there is no restriction on the material of the structural parts.

[0059] In some embodiments, the marine ammonia fuel engine exhaust gas treatment system described in the scheme of the present invention further includes: a first gas concentration sensor (such as gas concentration sensor 1) is arranged at the air inlet of the main flow path, which is used to detect and display the gas concentration of the marine ammonia fuel engine exhaust gas entering from the air inlet of the main flow path; a second gas concentration sensor (such as gas concentration sensor 5) is arranged at the exhaust port of the main flow path, which is used to detect and display the gas concentration of the exhaust gas discharged from the exhaust port of the main flow path, so as to determine the treatment effect of the marine ammonia fuel engine exhaust gas entering from the air inlet of the main flow path according to the gas concentration of the exhaust gas discharged from the exhaust port of the main flow path.

[0060] In the scheme of the utility model, in order to ensure that the marine ammonia fuel engine exhaust gas treatment system is in the best working condition, it is necessary to set NH3 and NO at the inlet and outlet of the marine ammonia fuel engine exhaust gas treatment system. x Concentration sensors (such as gas concentration sensors 1 and 5) are used to set the appropriate opening of the gas flow control valve according to the actual pollutant concentration.

[0061] In some embodiments, the marine ammonia fuel engine exhaust gas treatment system described in the scheme of the present invention further includes: a first gas flow regulating valve (such as a gas flow regulating valve 2) is provided in the pipeline in front of the air inlet of the SCR reactor 4 in the main flow path, which is used to adjust the gas flow of the marine ammonia fuel engine exhaust gas flowing from the main flow path to the air inlet of the SCR reactor 4 according to the gas concentration of the marine ammonia fuel engine exhaust gas entering from the air inlet of the main flow path; wherein, the gas flow of the marine ammonia fuel engine exhaust gas flowing from the main flow path to the air inlet of the SCR reactor 4 is adjusted by the first gas flow regulating valve, and the gas flow of the marine ammonia fuel engine exhaust gas flowing from the main flow path to the air inlet of the SCR reactor 4 can be manually adjusted according to the gas concentration of the marine ammonia fuel engine exhaust gas entering from the air inlet of the main flow path.

[0062] In the pipeline in front of the air inlet of the catalytic oxidation reaction device 10 in the bypass flow path, a second gas flow regulating valve (such as gas flow regulating valve 6) is provided, which is used to adjust the gas flow rate of the marine ammonia fuel engine exhaust gas flowing from the air inlet of the bypass flow path to the air inlet of the catalytic oxidation reaction device 10 according to the gas concentration of the marine ammonia fuel engine exhaust gas entering from the air inlet of the main flow path; wherein, the gas flow rate of the marine ammonia fuel engine exhaust gas flowing from the air inlet of the bypass flow path to the air inlet of the catalytic oxidation reaction device 10 is regulated by the second gas flow rate, and the gas flow rate of the marine ammonia fuel engine exhaust gas flowing from the air inlet of the bypass flow path to the air inlet of the catalytic oxidation reaction device 10 can be manually adjusted according to the gas concentration of the marine ammonia fuel engine exhaust gas entering from the air inlet of the main flow path.

[0063] The solution of the utility model is to provide a bypass flow path in the main flow path of the SCR reactor 4 and to provide a catalytic oxidation reaction device 10 in the bypass flow path, so that a part of NH3 and N2O in the exhaust gas flowing into the marine ammonia fuel engine exhaust gas treatment system can be oxidized into NO and NO2, which can not only improve or eliminate the problem of excessive NH3 in the SCR reactor 4, but also remove part of N2O through catalytic oxidation; in order to adjust the gas flow through the catalytic oxidation reaction device 10, a flow regulating valve is provided at the inlet of the catalytic oxidation reaction device 10 and in the main flow path of the SCR reactor 4, so as to adjust the gas flow entering the catalytic oxidation reaction device 10, so that the NH3 and NO2 in the SCR reactor 4 can be reduced. x The ratio is maintained close to 1:1, which overcomes the problem that a single SCR system cannot effectively treat a large amount of NH3 and a small amount of N2O in the exhaust gas, and is beneficial for the entire system to have good simultaneous deamination and denitrification performance, thereby achieving effective treatment of the exhaust gas of the marine ammonia fuel engine entering from the air inlet of the main flow path.

[0064] In the scheme of the utility model, the pollutants emitted by the ammonia fuel engine under different working conditions may change. The marine ammonia fuel engine exhaust gas treatment system can adjust the gas flow entering the catalytic oxidation reaction device 10 according to the concentration change of the exhaust gas pollutants (NH3, NO, NO and N2), so that the NH3 and NO inside the SCR reactor 4 can be reduced. x The ratio is kept close to 1: 1. A gas concentration sensor (such as gas concentration sensor 1, 5) is used in conjunction with a gas flow control valve (such as gas flow control valve 2, 6) to adjust the bypass flow control method according to the change in gas pollutant concentration, which can be applied to precise control under various working conditions.

[0065] In some embodiments, in the pipeline of the bypass flow path, the portion where the air inlet of the bypass flow path is located and the portion where the air outlet of the bypass flow path is located are arranged with bent pipes to facilitate smooth inflow of gas at the air inlet of the bypass flow path and smooth outflow of gas at the air outlet of the bypass flow path.

[0066] In some embodiments, the marine ammonia fuel engine exhaust gas treatment system described in the solution of the present invention further includes: an NH3 injection port 3; the NH3 injection port 3 is arranged in front of the air inlet of the SCR reactor 4 in the main flow path, so as to facilitate the injection of NH3 when it is necessary to supplement NH3 into the SCR reactor 4, so that the marine ammonia fuel engine exhaust gas treatment system is suitable for more engine operating conditions. Under some special operating conditions, such as when the engine load is too high, the NH3 fuel is relatively sufficient, the NH3 content in the exhaust gas discharged by the engine may be low, and the NOx content is high. Simply closing the bypass flow path completely still cannot solve the problem of NH3 deficiency, and additional NH3 needs to be supplemented to ensure the reaction effect of the SCR reactor 4.

[0067] Figure 4 FIG. 1 is a schematic diagram of an embodiment of an exhaust gas treatment system for a marine ammonia fuel engine. Figure 4As shown, the designed marine ammonia fuel engine exhaust gas treatment system mainly includes a main flow path and a bypass flow path, a set of SCR reactors 4 are arranged in the main flow path, and a set of catalytic oxidation reaction devices 10 are arranged in the bypass flow path. A flow regulating valve is installed in each of the main flow path and the bypass flow path, specifically, a flow regulating valve 2 is installed in the main flow path, and a flow regulating valve 6 is installed in the bypass flow path. A gas concentration sensor 1 is arranged at the entrance of the main flow path, a gas flow regulating valve 2 is arranged in the middle part of the pipeline of the front section of the SCR reactor 4 in the main flow path, an NH3 injection port 3 is arranged at the entrance of the SCR reactor 4 in the main flow path, a vortex generating coil 11 is arranged on the periphery of the SCR reactor 4 in the main flow path, and a gas concentration sensor 5 is arranged at the outlet of the SCR reactor 4 in the main flow path. A gas flow regulating valve 6 is provided at the inlet of the chemical oxidation reactor 10 in the bypass flow path; the catalytic oxidation reaction device 10 in the bypass flow path comprises: a venturi reaction tube 7 and an electrostatic precipitator 9 arranged in sequence along the flow direction of the pipeline, a catalyst powder inlet 12 and a rotating magnetic field generating coil 8 arranged in sequence in the main part of the venturi reaction tube 7 along the flow direction of the pipeline, and a catalyst powder outlet 13 arranged at the bottom of the electrostatic precipitator 9. After the exhaust gas containing NH3, NO, NO2, and N2O flows into the marine ammonia fuel engine exhaust gas treatment system, it will be divided into two paths: one path of the exhaust gas directly enters the SCR reactor 4; the other path of gas is treated by the catalytic oxidation reaction device 10, and the NH3 and N2O therein are catalytically oxidized into NO and NO2. The gas catalytically oxidized by the catalytic oxidation reaction device 10 re-enters the main flow path, mixes with the gas in the main flow path and enters the SCR reactor 4.

[0068] Among them, the air outlet of the venturi reaction tube 7 and the air inlet of the electrostatic precipitator 9 are directly connected to ensure timely treatment of the gas-solid mixture after the reaction and avoid accumulation and clogging of the catalyst powder at the outlet of the venturi tube. A hole is drilled at the upper position near the gas inlet upstream of the venturi reaction tube 7, and a catalyst powder feeding device (such as a catalyst powder inlet 12) is installed above this hole by welding, threaded connection, etc., for feeding catalyst powder. The rotating magnetic field generating coil 8 is directly sleeved on the neck of the venturi reaction tube 7 and is arranged behind the catalyst inlet to ensure that the catalyst can be affected by the rotating magnetic field as soon as it enters the reactor. The bottom of the electrostatic precipitator 9 adopts a funnel-shaped design, and an opening is set at the bottom as a catalyst powder outlet 13.

[0069] The applicant has built Figure 4The marine ammonia fuel engine exhaust gas treatment system shown in the figure has been subjected to effectiveness verification experiments. Experimental conditions: the total flow rate of simulated flue gas is 200ml / min (ml per minute), the simulated flue gas is prepared by mixing high-purity N2 and standard gases of NH3, NO, NO2, and N2O, and the simulated flue gas is prepared by normal temperature gas. Optionally, the bypass flue gas volume of the marine ammonia fuel engine exhaust gas treatment system is 0%, 20%, 40%, and 60%, the initial concentration of NH3 is 1000ppm, the initial concentrations of NO, NO2, and N2O are all 1000ppm, and the reaction temperature of the SCR reactor 4 is in the range of 150℃ to 450℃. The experimental results are shown in Figure 5 , Figure 6 , Figure 7 and Figure 8 shown.

[0070] Figure 5 When the branch flow regulating valve is in a completely closed state (i.e., the flue gas only passes through the SCR reactor 4), the test curve diagram of the gas concentration changing with the reaction temperature is shown in FIG. Figure 5 It can be seen that when the exhaust gas bypass amount is 0%, which is equivalent to using only the SCR reactor 4 to treat the exhaust gas, a small amount of NO and NO2 in the exhaust gas can be completely removed, but a large amount of NH3 and a small amount of N2O will remain in the exhaust gas.

[0071] Figure 5 When the branch flow regulating valve is in a completely closed state, the flue gas only passes through the SCR reactor 4. Figure 5 It can be seen that under this condition, the marine ammonia fuel engine exhaust gas treatment system has completely removed NO and NO2, and the amount of NH3 removed is about 2000ppm. x The concentration drop is 1:1, which is a typical NH3-SCR reaction. It should be noted that NH3 and NO in the SCR reaction equation X It is 1:1. If it is not this ratio, it is not SCR reaction. In addition, SCR reaction obviously cannot occur at room temperature, so the above experimental results show that the use effect of SCR reactor 4 and eddy current heater is better.

[0072] Figure 6 It is a test curve diagram of the change of gas concentration with reaction temperature when the branch flow regulating valve is opened and the flue gas bypass volume is 20%. Figure 6 As shown, when the exhaust gas bypass rate is 20%, the concentrations of NH3 and N2O in the exhaust gas treated by the SCR reactor 4 are significantly reduced, which indicates that the catalytic oxidation reaction device 10 has catalytically oxidized a portion of NH3 and N2O into NO and NO2, and then converted into N2 through the SCR reaction.

[0073] Figure 7It is a test curve diagram of the change of gas concentration with reaction temperature when the branch flow regulating valve is opened and the flue gas bypass volume is 40%. Figure 7 It can be seen that when the exhaust gas bypass amount (i.e., flue gas bypass amount) is 40%, NH3 and N2O in the exhaust gas are completely removed, indicating that the exhaust gas bypass amount at this time is relatively appropriate, which can basically ensure that NH3 and NO pass through the SCR reactor 4. x The ratio is 1:1.

[0074] Figure 8 It is a test curve diagram of the change of gas concentration with reaction temperature when the branch flow regulating valve is opened and the flue gas bypass volume is 60%. Figure 8 As shown, when the exhaust gas bypass rate is 40%, NH3 and N2O in the exhaust gas are completely removed, but the concentrations of NO and NO2 are significantly increased, which indicates that excess NH3 passes through the catalytic oxidation reaction device 10 and is oxidized to NO and NO2 and then discharged with the exhaust gas. The experimental results obtained by the above embodiment show that the exhaust gas treatment system for ammonia fueled marine engines can achieve the expected function.

[0075] Figure 6 , Figure 7 and Figure 8 The test results are shown below when the bypass flow control valve is open and the flue gas bypass volume is 20%, 40%, and 60%. When the flue gas bypass volume is 20%, the marine ammonia fuel engine exhaust gas treatment system has a significant effect in removing NH3, NO, and NO2. NO and NO2 are completely removed, and NH3 is mostly removed. x The reduction ratio is significantly higher than 1:1, indicating that in addition to the SCR reactor 4, the Venturi reactor in the branch is also working, and the excess NH3 is removed by catalytic oxidation of the powder catalyst in the Venturi reactor.

[0076] As the bypass rate increases from 20% to 40%, NH3 and N2O are completely removed, which shows that the Venturi reactor and SCR reactor 4 in the branch have excellent performance and can completely catalytically convert and remove NH3 and NO in the exhaust gas. x This also shows that under this bypass rate, the Venturi reactor and SCR reactor 4 have good synergistic performance. Note that in this system, the Venturi mainly catalyzes the oxidation of NH3 and N2O, converting them into N2 and NO. x The SCR reactor 4 mainly catalyzes the remaining NH3 and NO x The reaction produces N2.

[0077] When the bypass volume increases from 40% to 60%, NH3 and N2O in the flue gas are still completely removed, but a large amount of NO and NO2 appear. This is mainly because too much NH3 enters the Venturi reactor, causing NH3 to be oxidized into NO and NO2 in large quantities in the branch. This will cause the rear-end SCR reactor 4 to lack the reducing agent NH3, making it impossible to effectively remove NO and NO2.

[0078] The above results show that the amount of NH3 entering the Venturi reactor needs to be reasonably controlled in order for the marine ammonia fuel engine exhaust gas treatment system to achieve a better comprehensive treatment effect. Neither too high nor too low bypass volume will work. In actual use, the opening and catalyst reaction amount can be adjusted according to the engine operating conditions. The marine ammonia fuel engine exhaust gas treatment system has adaptive adjustment capabilities.

[0079] like Figure 5 , Figure 6 , Figure 7 and Figure 8 As shown in the figure, under the above experimental conditions, the exhaust gas bypass volume corresponding to the optimal working condition of the marine ammonia fuel engine exhaust gas treatment system is approximately 40%. However, the working conditions of the ammonia fuel engine in actual work may change continuously, resulting in changes in the exhaust gas flow rate and the concentration of pollutants in the exhaust gas. The marine ammonia fuel engine exhaust gas treatment system can use the gas concentration sensors set at the inlet and outlet to detect the concentrations of NH3, NO, NO2, N2O and other components in the gas, and adjust the exhaust gas bypass volume so that the amount of catalyst powder entering the venturi tube changes in a positive correlation with the airflow, and finally the NH3 and NO entering the SCR reactor 4 are x The ratio is always close to the optimal ratio (such as 1:1) to ensure the pollutant removal effect.

[0080] According to the technical solution of the utility model, a bypass flow path is provided upstream of the main flow path where the SCR reactor 4 is located, and a catalytic oxidation reaction device 10 is provided in the bypass flow path, so that the exhaust gas entering the upstream entrance of the main flow path is divided into two paths: one path flows directly to the entrance of the SCR reactor 4, and the other path is merged into the entrance of the SCR reactor 4 after catalytic oxidation reaction in the catalytic oxidation reaction device 10 in the bypass flow path. The two gases merge at the entrance of the SCR reactor 4 and then flow into the SCR reactor 4, and are discharged from the outlet of the main flow path after reaction in the SCR reactor 4; thus, by providing a set of catalytic oxidation reaction devices in the main flow path of the SCR reactor, a catalytic oxidation reaction is performed on part of NH3 and N2O in the inflowing exhaust gas, so that NH3 entering the SCR reactor can be reduced and part of N2O can be removed, so that the whole system has good simultaneous deamination and denitrification performance, and the exhaust gas of the marine ammonia fuel engine entering from the air inlet of the main flow path is effectively treated.

[0081] In summary, it is easy for those skilled in the art to understand that, under the premise of no conflict, the above-mentioned advantageous methods can be freely combined and superimposed.

[0082] The above description is only an embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the scope of the claims of the present invention.

Claims

1. A marine ammonia fuel engine exhaust gas treatment system, characterized in that: include: a first gas flow path and a second gas flow path; the first gas flow path is a main flow path, and an SCR reactor (4) is arranged in a pipeline between an air inlet and an exhaust port of the main flow path; The second gas flow path is a bypass flow path, the air inlet of the bypass flow path is connected to the main flow path and is arranged behind the air inlet of the main flow path, and the air outlet of the bypass flow path is connected to the main flow path and is arranged in front of the air inlet of the SCR reactor (4); a catalytic oxidation reaction device (10) is arranged in the pipeline between the air inlet and the air outlet of the bypass flow path; The marine ammonia fuel engine exhaust gas entering from the air inlet of the main flow path is divided into two paths: one path flows through the main flow path to the air inlet of the SCR reactor (4), and the other path flows through the catalytic oxidation reaction device (10) in the bypass flow path to the air inlet of the SCR reactor (4) after undergoing a catalytic oxidation reaction. The two paths of gas merge at the air inlet of the SCR reactor (4), undergo a reduction reaction in the SCR reactor (4), and are discharged from the exhaust port of the main flow path.

2. The marine ammonia fuel engine exhaust gas treatment system according to claim 1, characterized in that: The catalytic oxidation reaction device (10) comprises: a catalytic oxidation reactor and a catalyst inlet; the catalytic oxidation reactor comprises: a venturi reaction tube (7) and a rotating magnetic field generator; wherein: The front section of the Venturi reaction tube (7) serves as the air inlet of the catalytic oxidation reactor, and the rear section of the Venturi reaction tube (7) serves as the exhaust port of the catalytic oxidation reactor; The catalyst inlet is arranged above the front section of the Venturi reaction tube (7); the rotating magnetic field generator is located at the rear section of the catalyst inlet and is arranged on the periphery of the middle part of the Venturi reaction tube (7).

3. The marine ammonia fuel engine exhaust gas treatment system according to claim 2, characterized in that: The rotating magnetic field generator comprises: a rotating magnetic field generating coil (8); the rotating magnetic field generating coil (8) is sleeved on the periphery of the middle part of the Venturi reaction tube (7).

4. The marine ammonia fuel engine exhaust gas treatment system according to claim 2, characterized in that: The catalytic oxidation reaction device (10) further comprises: an electrostatic precipitator (9); the catalytic oxidation reactor and the electrostatic precipitator (9) are arranged in sequence along the gas flow direction in the bypass flow path; the air inlet of the catalytic oxidation reactor is connected to the air inlet of the bypass flow path, the exhaust port of the catalytic oxidation reactor is connected to the air inlet of the electrostatic precipitator (9); the exhaust port of the electrostatic precipitator (9) is connected to the exhaust port of the bypass flow path; A catalyst inlet is arranged at the top of the catalytic oxidation reactor for adding catalyst; and a catalyst outlet is arranged at the bottom of the electrostatic precipitator (9) for discharging the catalyst after the reaction.

5. The marine ammonia fuel engine exhaust gas treatment system according to any one of claims 1 to 4, characterized in that: A vortex generator is provided at a portion between an air inlet and an exhaust port of the SCR reactor (4).

6. The marine ammonia fuel engine exhaust gas treatment system according to claim 5, characterized in that: The eddy current generator comprises: an eddy current generating coil (11); wherein: When the shell and structural parts of the SCR reactor (4) are made of non-metallic materials, the eddy current generating coil (11) is sleeved around the periphery of the portion between the air inlet and the exhaust port of the SCR reactor (4) and is coaxially arranged with the SCR reactor (4); A catalyst module is provided inside the SCR reactor (4); when the shell and / or structural parts of the SCR reactor (4) are made of metal materials, the eddy current generating coil (11) is sleeved on the periphery of the catalyst module in the portion between the air inlet and the exhaust port of the SCR reactor (4) and is coaxially arranged with the catalyst module.

7. The marine ammonia fuel engine exhaust gas treatment system according to any one of claims 1 to 4, characterized in that: Also includes: A first gas concentration sensor is provided at the air inlet of the main flow path, for detecting and displaying the gas concentration of the exhaust gas of the marine ammonia fuel engine entering from the air inlet of the main flow path; a second gas concentration sensor is provided at the exhaust port of the main flow path, for detecting and displaying the gas concentration of the exhaust gas discharged from the exhaust port of the main flow path.

8. The marine ammonia fuel engine exhaust gas treatment system according to claim 7, characterized in that: Also includes: A first gas flow regulating valve is provided in the pipeline in front of the air inlet of the SCR reactor (4) in the main flow path, for regulating the gas flow of the marine ammonia fuel engine exhaust gas flowing from the main flow path to the air inlet of the SCR reactor (4); A second gas flow regulating valve is provided in the pipeline in front of the air inlet of the catalytic oxidation reaction device (10) in the bypass flow path, for regulating the gas flow of the marine ammonia fuel engine exhaust gas flowing from the air inlet of the bypass flow path to the air inlet of the catalytic oxidation reaction device (10).

9. The marine ammonia fuel engine exhaust gas treatment system according to any one of claims 1 to 4, characterized in that: In the pipeline of the bypass flow path, the portion where the air inlet of the bypass flow path is located and the portion where the air outlet of the bypass flow path is located are arranged as bent pipes.

10. The marine ammonia fuel engine exhaust gas treatment system according to any one of claims 1 to 4, characterized in that: Also includes: NH3 injection port (3); the NH3 injection port (3) is arranged in front of the air inlet of the SCR reactor (4) in the main flow path.

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