Nitrogen recovery and supply system of ammonia fuel engine of ship

Abstract

The invention discloses a nitrogen recovery and supply system of a ship ammonia fuel engine in the technical field of engines, which comprises a base, a plurality of catalytic modules are arranged on the base, and the catalytic modules are filled with different types of catalyst materials so as to reduce tail gas by adopting various catalysts; the catalysis module comprises a plurality of catalysis cylinders which are distributed at equal intervals, connecting pipes are arranged between inlets and outlets of the adjacent catalysis cylinders, and first control valves are arranged on the connecting pipes; a collecting pipe is arranged between every two adjacent catalytic modules, air inlet pipes are arranged between the collecting pipes and the top end outlets of the multiple catalytic cylinders, second control valves are arranged on the air inlet pipes, and air outlet pipes used for being connected with the next catalytic module are arranged at the tail ends of the collecting pipes. The system adopts multiple catalytic modules, tail gas is reduced through multiple catalysts, the catalytic efficiency and the catalytic effect are greatly improved, and the number of catalytic cylinders connected into the system in each catalytic module can be dynamically adjusted so as to adapt to multiple tail gas working conditions.

Description

Technical Field

[0001] The present invention relates to the technical field of engines, and in particular to a nitrogen recovery and supply system for a marine ammonia fuel engine. Background Art

[0002] Ammonia fuel, a zero-carbon alternative energy source, is increasingly being adopted in marine propulsion systems. While ammonia fuel effectively reduces carbon dioxide emissions during combustion, its exhaust still contains high concentrations of nitrogen oxides (NOx), potentially posing a threat to the atmospheric environment. Nitrogen recovery and supply systems for ammonia-fueled marine engines are primarily designed to recycle nitrogen while simultaneously addressing the risk of ammonia leakage and nitrogen oxide (NOx) emissions.

[0003] Currently, marine engine exhaust treatment primarily relies on catalytic reduction technologies, such as selective catalytic reduction (SCR). However, existing systems typically utilize a single type of catalyst, which struggles to cope with variations in exhaust composition under varying operating conditions, leading to significant fluctuations in catalytic efficiency. Furthermore, most systems utilize fixed catalytic modules, which are unable to dynamically adjust catalytic intensity based on exhaust concentration, making over- or under-treatment a common problem. Some systems employ continuous chemical feed or high-pressure pump injection, resulting in high energy consumption and significant chemical waste.

[0004] To this end, a nitrogen recovery and supply system for a marine ammonia fuel engine is provided to solve the above-mentioned problems. Summary of the Invention

[0005] The purpose of the present invention is to provide a nitrogen recovery and supply system for a marine ammonia fuel engine, which solves the problem that the existing system has large fluctuations in catalytic efficiency and cannot dynamically adjust the catalytic intensity according to the exhaust gas concentration.

[0006] The present invention achieves the above-mentioned purpose through the following technical solutions: A nitrogen recovery and supply system for a marine ammonia fuel engine comprises a base, on which are provided a plurality of catalytic modules, each of which is filled with a different type of catalyst material so as to reduce exhaust gas using a variety of catalysts; the catalytic modules comprise a plurality of catalytic cartridges distributed at equal intervals, a connecting pipe being provided between the inlets and outlets of adjacent catalytic cartridges, and a first control valve being provided on the connecting pipe; a manifold being provided between adjacent catalytic modules, an inlet pipe being provided between the manifold and the top outlets of the plurality of catalytic cartridges, and a second control valve being provided on the inlet pipe, and an outlet pipe being provided at the end of the manifold for connecting to the next group of catalytic modules; a sensor group for detecting exhaust gas components is also provided at the end of the manifold, and the system dynamically adjusts the number of catalytic cartridges connected to the system in each group of catalytic modules according to the exhaust gas data of the sensor group.

[0007] As a further optimization solution of the present invention, the intake pipe of the manifold is connected to the exhaust pipes of multiple cylinders in the engine main case on the side close to the engine main case to receive exhaust gas from each cylinder.

[0008] As a further optimization solution of the present invention, the system further includes a nitrogen storage tank, which is used to store nitrogen and supply nitrogen to the top space of the ammonia fuel storage tank to form an inert protective layer.

[0009] As a further optimization solution of the present invention, a driving mechanism for regulating the on-off state of the first control valve and the second control valve is provided above each group of the catalytic modules.

[0010] As a further optimization scheme of the present invention, the driving mechanism includes a mounting frame and a translation unit arranged on the side panel of the base, the translation unit is used to drive the mounting frame to move back and forth in the horizontal direction, and the mounting frame is provided with a first conductive slide groove and a second conductive slide groove; a first support rod is fixedly provided on the first control valve, and the end of the first support rod is provided with a first conductive slider matching the first conductive slide groove, and the first conductive slider contacts the first conductive slide groove to connect the first control valve; a second support rod is fixedly provided on the second control valve, and the end of the second support rod is provided with a second conductive slider matching the second conductive slide groove, and the second conductive slider contacts the second conductive slide groove to connect the second control valve.

[0011] As a further optimization scheme of the present invention, the length of the first conductive slide groove is equivalent to the length of the mounting frame to control multiple first control valves to be connected at the same time; the length of the second conductive slide groove is smaller than the first conductive slide groove, and only corresponds to one second conductive slider to control only one second control valve to be connected.

[0012] As a further optimization scheme of the present invention, a catalyst module and a dosing assembly located below the catalyst module are provided in the catalytic cylinder; the dosing assembly includes a drug storage cylinder and a plurality of air bags evenly distributed circumferentially around the drug storage cylinder, a liquid inlet pipe is provided between the air bag and the drug storage cylinder, a first one-way valve is provided on the liquid inlet pipe, a liquid outlet pipe is provided at the outlet of the air bag, and a second one-way valve is provided on the liquid outlet pipe.

[0013] As a further optimization scheme of the present invention, a lifting frame for squeezing the airbag to achieve intermittent dosing is also provided in the catalytic cylinder; the lifting frame includes a main frame body, the bottom end of the main frame body is provided with a third pressure plate fixedly connected to the airbag, and the top end of the main frame body is provided with a second pressure plate; the driving mechanism also includes a rotating shaft rotatably arranged in the mounting frame, one end of the rotating shaft is provided with a motor for driving it to rotate, and a plurality of cams are fixedly sleeved on the rotating shaft, and the cams squeeze the second pressure plate to drive the lifting frame to move back and forth.

[0014] As a further optimization scheme of the present invention, ring plates are fixed on the inner walls of the catalytic cylinder at the upper and lower ends of the catalyst module, and multiple springs are evenly distributed circumferentially between the ring plates and the catalyst module; a first pressure plate is fixed in the middle of the main frame, and the first pressure plate is used to squeeze the ring plate to drive the catalyst module to vibrate reciprocatingly.

[0015] The beneficial effects of the present invention are: 1. The present invention adopts multiple groups of catalytic modules, and the exhaust gas is reduced by multiple catalysts, which greatly improves the catalytic efficiency and catalytic effect. The number of catalytic tubes in each group of catalytic modules connected to the system can be dynamically adjusted to adapt to various exhaust gas working conditions. The entire system can achieve closed-loop automatic adjustment, with a high level of automation and intelligence.

[0016] 2. The present invention utilizes the cam and lifting frame of the driving mechanism to realize drug addition control, which has a simple structure and high reliability. Multiple air bags are arranged around the drug storage cylinder, and drug liquid can be added to different positions at the same time, thereby improving the catalytic uniformity.

[0017] 3. The catalyst module of the present invention is not easily blocked by particulate matter or reaction products in the exhaust gas under the action of vibration, maintains good permeability, promotes sufficient contact between the exhaust gas and the catalyst, and improves the reaction rate and conversion rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a three-dimensional schematic diagram of the overall structure of the present invention; Figure 2 It is a plan view of the overall structure of the present invention; Figure 3 Schematic diagram of the catalytic module structure of the present invention; Figure 4 Schematic diagram of the driving mechanism structure of the present invention; Figure 5 Schematic diagram of the connection structure between the driving mechanism and the first control valve and the second control valve of the present invention; Figure 6 This is a schematic diagram of the internal structure of the catalytic cartridge of the present invention; Figure 7 This is a schematic structural diagram of the dosing assembly of the present invention; Figure 8 It is a schematic diagram of the lifting frame structure of the present invention.

[0019] In the picture: 1. Base; 2. Catalytic module; 201. Catalytic cartridge; 202. Connecting pipe; 203. First control valve; 203a. First support rod; 203b. First conductive slider; 204. Catalyst module; 204a. Ring plate; 204b. Spring; 205. Dosing assembly; 205a. Drug storage cartridge; 205b. Air bag; 205c. Liquid inlet pipe; 205d. First one-way valve; 205e. Liquid outlet pipe; 205f. Second one-way valve; 206. Lifting frame; 206a. Main frame ; 206b, first pressure plate; 206c, second pressure plate; 206d, third pressure plate; 3, manifold; 301, air inlet pipe; 302, second control valve; 302a, second support rod; 302b, second conductive slider; 303, air outlet pipe; 4, sensor group; 5, drive mechanism; 501, mounting bracket; 502, first conductive slide groove; 503, second conductive slide groove; 504, translation unit; 505, rotating shaft; 506, cam; 507, motor; 6, engine main box. DETAILED DESCRIPTION

[0020] The present application is described in further detail below in conjunction with the accompanying drawings. It is necessary to point out that the following specific implementation methods are only used to further illustrate the present application and cannot be understood as limiting the scope of protection of the present application. Technicians in this field can make some non-essential improvements and adjustments to the present application based on the above application content.

[0021] Example 1 In order to solve the problem that the existing system generally uses a single type of catalyst, resulting in large fluctuations in catalytic efficiency, and most of them use fixed catalytic modules, which cannot dynamically adjust the catalytic intensity according to the exhaust gas concentration, please refer to Figure 1-Figure 3 The present invention provides a nitrogen recovery and supply system for a ship ammonia fuel engine, comprising a base 1, on which are provided a plurality of catalytic modules 2, each catalytic module 2 being filled with different types of catalyst materials so as to reduce exhaust gas using a plurality of catalysts; the catalytic module 2 comprises a plurality of catalytic cartridges 201 distributed at equal intervals, a connecting pipe 202 being provided between the inlet and outlet of adjacent catalytic cartridges 201, and a first control valve 203 being provided on the connecting pipe 202; a manifold 3 being provided between adjacent catalytic modules 2, an air inlet pipe 301 being provided between the manifold 3 and the top outlets of the plurality of catalytic cartridges 201, a second control valve 302 being provided on the air inlet pipe 301, and an air outlet pipe 303 being provided at the end of the manifold 3 for connecting to the next group of catalytic modules 2; a sensor group 4 for detecting exhaust gas components is also provided at the end of the manifold 3, and the system dynamically adjusts the number of catalytic cartridges 201 connected to the system in each group of catalytic modules 2 according to the exhaust gas data of the sensor group 4.

[0022] On one side close to the engine main case 6 , the air inlet pipe 301 of the manifold 3 is respectively connected to the exhaust pipes of multiple cylinders in the engine main case 6 to receive the exhaust gas from each cylinder.

[0023] The system also includes a nitrogen storage tank, which stores nitrogen and supplies it to the headspace of the ammonia fuel tank, forming an inert protective layer. This layer effectively isolates oxygen from the air, preventing the ammonia fuel from mixing with oxygen to form explosive gases, significantly improving fuel storage safety. Furthermore, nitrogen recovered from engine exhaust treatment is reused, improving the system's energy efficiency and environmental performance. The nitrogen storage tank can also supply nitrogen for pipeline purging, combustion chamber auxiliary combustion, and cargo hold inerting.

[0024] like Figure 1 、 Figure 4-Figure 5 As shown, a driving mechanism 5 for regulating the on / off states of the first control valve 203 and the second control valve 302 is provided above each catalytic module 2 .

[0025] The driving mechanism 5 includes a mounting frame 501 and a translation unit 504 provided on the side plate of the base 1. The translation unit 504 is used to drive the mounting frame 501 to reciprocate horizontally. The translation unit 504 can adopt a high-precision screw transmission device. Through the rotation of the screw, the mounting frame 501 is driven to reciprocate horizontally along the linear guide rail. The mounting frame 501 is provided with a first conductive slide 502 and a second conductive slide 503; a first support rod 203a is fixedly provided on the first control valve 203, and a first conductive slider 203b matching the first conductive slide 502 is provided at the end of the first support rod 203a. The first conductive slider 203b contacts the first conductive slide 502 to connect the first control valve 203; a second support rod 302a is fixedly provided on the second control valve 302, and a second conductive slider 302b matching the second conductive slide 503 is provided at the end of the second support rod 302a. The second conductive slider 302b contacts the second conductive slide 503 to connect the second control valve 302.

[0026] The length of the first conductive slide 502 is comparable to the length of the mounting bracket 501 to control multiple first control valves 203 to be connected at the same time; the length of the second conductive slide 503 is smaller than the first conductive slide 502, and only corresponds to one second conductive slider 302b to control only one second control valve 302 to be connected.

[0027] The exhaust gases from multiple cylinders of the engine main case 6 are collected into the manifold 3 near the engine side through the intake pipe 301, and then enter the first catalytic module 2 through the outlet pipe 303. The first catalytic module 2 may use an ammonia decomposition catalyst, such as a ruthenium-based or nickel-based catalyst, to decompose excess NH3 to prevent it from escaping into the atmosphere and causing secondary pollution. At the same time, a small amount of hydrocarbons (HC) and incomplete combustion products in the tail gas may be preliminarily oxidized. After being processed by the first catalytic module 2, the tail gas is collected into the corresponding manifold 3 through the intake pipe 301, and then enters the second catalytic module 2 through the outlet pipe 303. The second catalytic module 2 may use a selective catalytic reduction catalyst, such as a vanadium-based catalyst or a copper-based molecular sieve, to perform a preliminary reduction reaction on high-concentration NOx, converting NOx into N2 and H2O. After being processed by the second catalytic module 2, the gas is then collected into the corresponding manifold 3 through the inlet pipe 301, and then enters the third catalytic module 2 through the outlet pipe 303. The third catalytic module 2 can use activated carbon-loaded precious metal catalysts, manganese-based oxides or porous ceramic materials to deeply adsorb and catalytically oxidize the trace NOx, NH3 and other trace pollutants (such as sulfides and particulate matter) remaining after the first two stages of catalytic treatment; during each stage of catalytic treatment, the sensor group 4 monitors the exhaust gas components (such as NOx, NH3, O2, etc.) in real time. The system determines whether it is necessary to increase or decrease the number of catalytic cylinders 201 participating in the reaction based on the sensor data, controls the action of the driving mechanism 5, drives the conductive slider to contact or separate with the slide groove, and thereby selectively connects or closes the corresponding first control valve 203 and second control valve 302.

[0028] This system adopts multiple groups of catalytic modules 2, and the exhaust gas is reduced by multiple catalysts, which greatly improves the catalytic efficiency and catalytic effect and is suitable for various exhaust gas working conditions; and when the system is running at low load, only part of the catalytic tubes 201 are activated to meet the purification requirements. When the load is high or the exhaust gas concentration increases, more catalytic tubes 201 are automatically connected to improve the processing capacity, and not all catalytic tubes 201 are blindly activated to avoid energy waste; through the linkage of sensors, control valves and drive mechanisms 5, closed-loop automatic adjustment is achieved without the need for human intervention.

[0029] Example 2 On the basis of Example 1, in order to improve the catalytic efficiency and enhance the automation and intelligence level of the system, Figure 6-Figure 8As shown, a catalyst module 204 and a dosing assembly 205 located below the catalyst module 204 are provided in the catalytic cylinder 201; the dosing assembly 205 includes a drug storage cylinder 205a and a plurality of air bags 205b uniformly distributed around the drug storage cylinder 205a along the circumferential direction, a liquid inlet pipe 205c is provided between the air bags 205b and the drug storage cylinder 205a, a first one-way valve 205d is provided on the liquid inlet pipe 205c to prevent liquid backflow, a liquid outlet pipe 205e is provided at the outlet of the air bag 205b, and a second one-way valve 205f is provided on the liquid outlet pipe 205e.

[0030] A lifting frame 206 for squeezing the airbag 205b to achieve intermittent dosing is also provided in the catalytic cylinder 201; the lifting frame 206 includes a main frame body 206a, the bottom end of the main frame body 206a is provided with a third pressure plate 206d fixedly connected to the airbag 205b, and the top end of the main frame body 206a is provided with a second pressure plate 206c; the driving mechanism 5 also includes a rotating shaft 505 rotatably arranged in the mounting frame 501, one end of the rotating shaft 505 is provided with a motor 507 for driving it to rotate, and a plurality of cams 506 are fixedly sleeved on the rotating shaft 505, and the cams 506 squeeze the second pressure plate 206c to drive the lifting frame 206 to move back and forth.

[0031] The drug storage cartridge 205a contains an additive to be released (such as a reducing agent, urea, or a catalyst activator). The drive motor 507 is started, driving the rotating shaft 505 to rotate. The cam 506 rotates with the shaft, periodically striking the second pressure plate 206c. The lifting frame 206 is forced to move downward, and the third pressure plate 206d presses the airbag 205b. The volume of the airbag 205b decreases under pressure, and the second one-way valve 205f opens. The drug liquid is ejected from the liquid outlet pipe 205e and mixes with the exhaust gas to improve the catalytic efficiency. The cam 506 leaves the contact surface of the second pressure plate 206c, and the lifting frame 206 returns to its original position under the action of the elastic force. During the recovery process of the airbag 205b, the drug liquid is sucked into the airbag 205b through the liquid inlet pipe 205c, preparing for the next drug dosing cycle.

[0032] The drug dosing control is achieved by utilizing the cam 506 of the driving mechanism 5 and the lifting frame 206. By adjusting the speed of the motor 507, the drug dosing frequency and dosage can be flexibly adjusted to adapt to different working conditions. It does not rely on a high-pressure pump or a complex control system. It has a simple structure and high reliability. Multiple airbags 205b are arranged around the drug storage barrel 205a, and drug liquid can be added to different positions at the same time to improve the catalytic uniformity.

[0033] Example 3 On the basis of Example 1 and Example 2, in order to prevent the catalyst from being blocked and further improve the catalytic efficiency, Figure 6 、 Figure 8As shown, ring plates 204a are fixed to the inner walls of the catalytic cylinder 201 at both the upper and lower ends of the catalyst module 204. Multiple springs 204b are evenly distributed circumferentially between the ring plates 204a and the catalyst module 204. A first pressure plate 206b is fixed to the middle of the main frame 206a, which is used to compress the ring plates 204a to drive the catalyst module 204 to vibrate back and forth. Under vibration, the catalyst module 204 is not easily clogged by particulate matter or reaction products in the exhaust gas, maintaining good permeability. Vibration also promotes sufficient contact between the exhaust gas and the catalyst, improving the reaction rate and conversion rate, reducing catalyst deactivation caused by carbon deposits or deposition, and extending the catalyst's service life. The vibration function is simultaneously achieved by utilizing the existing lifting frame 206 for driving the dosing, resulting in a compact structure and low energy consumption.

[0034] The catalyst module 204 is supported by multiple upper and lower springs 204b and is in an elastic suspension state. The driving mechanism 5 drives the cam 506 to rotate, pushing the second pressure plate 206c downward, and the lifting frame 206 moves downward as a whole. The third pressure plate 206d compresses the airbag 205b to add medicine. At the same time, the first pressure plate 206b moves downward with the main frame 206a and contacts the ring plate 204a. The first pressure plate 206b continues to press the ring plate 204a, forcing the catalyst module 204 to move downward, compressing the lower spring 204b, and the cam 506 rotates. The pressure is released, and the compressed spring 204b releases energy, pushing the catalyst module 204 to rebound upward, forming vibration. As the lifting frame 206 continues to move up and down, the catalyst module 204 continues to vibrate back and forth under the action of the spring 204b, effectively preventing catalyst particles from accumulating, clogging or agglomerating.

[0035] The above-described embodiments merely illustrate several implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, and all such variations and improvements fall within the scope of protection of the present invention.

Claims

1. A nitrogen recovery and supply system for a marine ammonia fuel engine, comprising a base (1), characterized in that: The base (1) is provided with a plurality of catalytic modules (2), each of which is filled with different types of catalyst materials, so as to reduce the exhaust gas using multiple catalysts; The catalytic module (2) comprises a plurality of catalytic cylinders (201) distributed at equal intervals, a connecting pipe (202) is provided between the inlet and outlet of adjacent catalytic cylinders (201), and a first control valve (203) is provided on the connecting pipe (202); A manifold (3) is provided between adjacent catalytic modules (2), an air inlet pipe (301) is provided between the manifold (3) and the top outlets of the plurality of catalytic cylinders (201), a second control valve (302) is provided on the air inlet pipe (301), and an air outlet pipe (303) for connecting to the next group of catalytic modules (2) is provided at the end of the manifold (3); A sensor group (4) for detecting exhaust gas components is also provided at the end of the manifold (3), and the system dynamically adjusts the number of catalytic cylinders (201) connected to the system in each catalytic module (2) according to exhaust gas data from the sensor group (4).

2. The nitrogen recovery and supply system for a marine ammonia fuel engine according to claim 1, characterized in that: On a side close to the engine main case (6), the air inlet pipe (301) of the manifold (3) is respectively connected to the exhaust pipes of a plurality of cylinders in the engine main case (6) to receive exhaust gas from each cylinder.

3. The nitrogen recovery and supply system for a marine ammonia fuel engine according to claim 1, characterized in that: The system further comprises a nitrogen storage tank, which is used to store nitrogen and supply nitrogen to the head space of the ammonia fuel storage tank to form an inert protective layer.

4. The nitrogen recovery and supply system for a marine ammonia fuel engine according to claim 1, characterized in that: A driving mechanism (5) for regulating the on / off states of the first control valve (203) and the second control valve (302) is provided above each group of the catalytic modules (2).

5. The nitrogen recovery and supply system for a marine ammonia fuel engine according to claim 4, characterized in that: The driving mechanism (5) comprises a mounting frame (501) and a translation unit (504) provided on a side plate of the base (1), wherein the translation unit (504) is used to drive the mounting frame (501) to reciprocate in a horizontal direction, and the mounting frame (501) is provided with a first conductive slide groove (502) and a second conductive slide groove (503); A first support rod (203a) is fixedly provided on the first control valve (203); a first conductive sliding block (203b) matching the first conductive sliding groove (502) is provided at the end of the first support rod (203a); the first conductive sliding block (203b) contacts the first conductive sliding groove (502) to connect the first control valve (203); A second support rod (302a) is fixedly provided on the second control valve (302), and a second conductive sliding block (302b) matching the second conductive sliding groove (503) is provided at the end of the second support rod (302a), and the second conductive sliding block (302b) contacts the second conductive sliding groove (503) to connect the second control valve (302).

6. The nitrogen recovery and supply system for a marine ammonia fuel engine according to claim 5, characterized in that: The length of the first conductive chute (502) is comparable to the length of the mounting frame (501), so as to control the simultaneous connection of multiple first control valves (203); The second conductive slide groove (503) is shorter than the first conductive slide groove (502) and only cooperates with one second conductive sliding block (302b) to control only one second control valve (302) to be connected.

7. The nitrogen recovery and supply system for a marine ammonia fuel engine according to claim 5, characterized in that: The catalytic cylinder (201) is provided with a catalyst module (204) and a dosing assembly (205) located below the catalyst module (204); The dosing assembly (205) comprises a drug storage barrel (205a) and a plurality of air bags (205b) uniformly distributed around the drug storage barrel (205a) along the circumferential direction; a liquid inlet pipe (205c) is provided between the air bags (205b) and the drug storage barrel (205a); a first one-way valve (205d) is provided on the liquid inlet pipe (205c); a liquid outlet pipe (205e) is provided at the outlet of the air bag (205b); and a second one-way valve (205f) is provided on the liquid outlet pipe (205e).

8. The nitrogen recovery and supply system for a marine ammonia fuel engine according to claim 7, characterized in that: The catalytic cylinder (201) is further provided with a lifting frame (206) for squeezing the air bag (205b) to achieve intermittent dosing. The lifting frame (206) comprises a main frame (206a), the bottom end of the main frame (206a) is provided with a third pressing plate (206d) fixedly connected to the airbag (205b), and the top end of the main frame (206a) is provided with a second pressing plate (206c); The driving mechanism (5) further comprises a rotating shaft (505) rotatably arranged in the mounting frame (501), one end of the rotating shaft (505) being provided with a motor (507) for driving the rotating shaft (505) to rotate, a plurality of cams (506) being fixedly sleeved on the rotating shaft (505), the cams (506) pressing the second pressing plate (206c) to drive the lifting frame (206) to move up and down reciprocatingly.

9. The nitrogen recovery and supply system for a marine ammonia fuel engine according to claim 8, characterized in that: Ring plates (204a) are fixedly provided on the inner walls of the catalytic cylinder (201) at the upper and lower ends of the catalyst module (204), and a plurality of springs (204b) are evenly distributed along the circumferential direction between the ring plate (204a) and the catalyst module (204); A first pressing plate (206b) is fixedly provided in the middle of the main frame (206a), and the first pressing plate (206b) is used to press the ring plate (204a) to drive the catalyst module (204) to vibrate back and forth.

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