Dual-engine ammonia fuel supply system of engine and working method

Abstract

The invention discloses a dual-engine ammonia fuel supply system and a working method, which improve the production test run efficiency of an ammonia fuel engine, and meanwhile, when one or zero engine is tested, a non-test run ammonia fuel supply system can be completely free of ammonia, so that the safety of operators is ensured. According to the technical scheme, the system comprises a material storage device, a supply system and a control system; the material storage device is connected with the supply system, and a gasification device and a pressure reducing valve are arranged on the material storage device; the supply system is divided into a first supply system and a second supply system, the first supply system and the second supply system are both connected with the control system, and the control system is used for controlling fuel supply of the first supply system and the second supply system and removing tasks of redundant fuel according to different working conditions; the first engine and the second engine are installed in the workshop, and the material storage device, the supply system and the control system are arranged outside the workshop.

Description

Technical Field

[0001] The present invention belongs to the technical field of engine fuel supply systems, and in particular relates to an engine dual-engine ammonia fuel supply system and a working method. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] At present, engines using multiple fuels have been widely used. In recent years, ammonia fuel engines have been introduced. Using ammonia as the main fuel can reduce the carbon emissions of internal combustion engines. For example, patent number CN117662292A discloses an ammonia dual-fuel engine, which mainly realizes two-stage combustion to make ammonia burn completely to solve the technical problem of high nitrogen oxide emissions. However, for manufacturers of ammonia fuel engines, multiple ammonia fuel engines need to be tested at the same time. Therefore, there is a problem of low test efficiency of ammonia fuel engines. At the same time, considering the toxic nature of ammonia fuel itself, there is also a problem that the ammonia fuel supply pipeline is prone to cause poisoning of personnel. Summary of the invention

[0004] In view of the above problems, the present invention provides an engine dual-engine ammonia fuel supply system and working method. Through multiple supply systems, the ammonia fuel supply requirements of dual-engine operation can be met, thereby improving the efficiency of ammonia fuel engine production test runs. At the same time, when one or zero engines are tested, the non-test ammonia fuel supply system can be completely free of ammonia, ensuring the safety of operators.

[0005] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0006] In a first aspect, the present invention provides an engine dual-engine ammonia fuel supply system, comprising a first engine, a second engine, a material storage device, a supply system and a control system;

[0007] The material storage device is connected to the supply system, and is provided with a gasification device and a pressure reducing valve for storing and releasing liquefied materials required for combustion;

[0008] The supply system is divided into a first supply system and a second supply system, which are used to provide fuel to the first engine and the second engine and can remove the remaining materials in the supply system; the first supply system and the second supply system are both connected to the control system, and the control system is used to control the fuel supply and excess fuel removal tasks of the first supply system and the second supply system according to different working conditions;

[0009] The first engine and the second engine are installed inside the workshop, and the material storage device, the supply system and the control system are arranged outside the workshop.

[0010] Furthermore, the material storage device is provided with a nitrogen tank, a compressed air tank and a liquid ammonia tank.

[0011] Further, the first supply system includes a first exhaust gas discharge pipe, a first nitrogen supply pipe, a first liquid ammonia supply pipe and a first compressed air supply pipe;

[0012] One end of the first compressed air supply pipe is connected to the compressed air tank, and the other end is connected to the first engine intake pipe, so as to provide oxygen for the fuel combustion of the first engine; one end of the first liquid ammonia supply pipe is connected to the liquid ammonia tank, and the other end is connected to the first engine intake pipe; one end of the first nitrogen supply pipe is connected to the nitrogen tank, and the other end is connected to the first liquid ammonia supply pipe; one end of the first exhaust gas discharge pipe is connected to the exhaust gas pipeline, and the other end is connected to the first liquid ammonia supply pipe.

[0013] Furthermore, a first switch valve and a second switch valve are provided on the first liquid ammonia supply pipe, the first switch valve is arranged close to the liquid ammonia tank, the second switch valve is arranged close to the first engine intake pipe, and a first pressure sensor and a first gas detector are provided between the first switch valve and the second switch valve.

[0014] Furthermore, the connection point between the first exhaust gas discharge pipe and the first liquid ammonia supply pipe is located between the first switch valve and the second switch valve, and the first nitrogen supply pipe is provided with a first purge valve; the connection point between the first exhaust gas discharge pipe and the first liquid ammonia supply pipe is also located between the first switch valve and the second switch valve, and the first exhaust gas discharge pipe is provided with a first release valve.

[0015] Furthermore, the second supply system includes a second exhaust gas discharge pipe, a second nitrogen supply pipe, a second liquid ammonia supply pipe and a second compressed air supply pipe; one end of the second compressed air supply pipe is connected to the compressed air tank, and the other end is connected to the second engine intake pipe, for providing oxygen for the second engine fuel combustion; one end of the second liquid ammonia supply pipe is connected to the liquid ammonia tank, and the other end is connected to the second engine intake pipe; one end of the second nitrogen supply pipe is connected to the nitrogen tank, and the other end is connected to the second liquid ammonia supply pipe; one end of the second exhaust gas discharge pipe is connected to the exhaust gas pipeline, and the other end is connected to the second liquid ammonia supply pipe.

[0016] Furthermore, a third switch valve and a fourth switch valve are provided on the second liquid ammonia supply pipe, the third switch valve is arranged close to the liquid ammonia tank, and the fourth switch valve is arranged close to the second engine intake pipe. A second pressure sensor and a second gas detector are provided between the third switch valve and the fourth switch valve for detecting the pressure and concentration of the fuel in the second liquid ammonia supply pipe.

[0017] Furthermore, the connection point between the second nitrogen supply pipe and the second liquid ammonia supply pipe is located between the third switch valve and the fourth switch valve, and a second purge valve is provided on the second nitrogen supply pipe; the connection point between the second exhaust gas discharge pipe and the second liquid ammonia supply pipe is also located between the third switch valve and the fourth switch valve, and a second release valve is provided on the second exhaust gas discharge pipe.

[0018] Further, the control system is respectively connected to the first switch valve, the second switch valve, the third switch valve, the fourth switch valve, the first purge valve, the second purge valve, the first release valve, the second release valve, the first pressure sensor, the first gas detector, the second pressure sensor and the second gas detector.

[0019] In a second aspect, the present invention further provides a method for operating a dual-engine ammonia fuel supply system for an engine, comprising the following steps:

[0020] S1. When the first engine and the second engine are tested at the same time, the control system controls the first switch valve, the second switch valve, the third switch valve and the fourth switch valve to be in an open state, and the control system controls the first purge valve, the second purge valve, the first release valve and the second release valve to be in a closed state, and the first liquid ammonia supply pipe and the first compressed air supply pipe deliver the liquid ammonia fuel and the compression control to the intake pipe of the first engine; the second liquid ammonia supply pipe and the second compressed air supply pipe deliver the liquid ammonia fuel and the compression control to the intake pipe of the second engine;

[0021] S2, when the first engine is tested and the second engine is stopped: the third switch valve and the fourth switch valve are closed, and the second purge valve and the second release valve are not operated, and the second pressure sensor and the second gas detector enter the monitoring state. When the second pressure sensor and the second gas detector reach the preset alarm value of the control system, the second purge valve and the second release valve are opened, and nitrogen is blown into the second liquid ammonia supply pipe along the second nitrogen supply pipe, and the toxic gas ammonia is diluted and discharged through the second exhaust gas discharge pipe;

[0022] S3. When the first engine and the second engine are stopped at the same time, the first switch valve and the second switch valve are closed, and the first purge valve and the first release valve are not operated. The first pressure sensor and the first gas detector enter the monitoring state. When the first pressure sensor and the first gas detector reach the preset alarm values ​​of the control system, the first purge valve and the first release valve are opened, and nitrogen is blown into the first liquid ammonia supply pipe along the first nitrogen supply pipe, and the toxic gas ammonia therein is diluted and discharged through the first exhaust gas discharge pipe. When the second engine is stopped, the control method of the control system described in S2 is used.

[0023] Compared with the prior art, the present invention has the following advantages and positive effects:

[0024] The present invention arranges a material storage device, a supply system and a control system outside a workshop, and a first engine and a second engine are installed inside the workshop, thereby reducing the contact between operators and ammonia fuel-related devices and reducing risks; through the designed first supply system and second supply system, fuel is independently supplied to the two engines respectively, meeting the ammonia fuel supply requirements for dual-engine operation, improving the efficiency of the ammonia fuel engine production test, ensuring that the two engines can obtain fuel normally while ensuring that the contact between operators and ammonia fuel is reduced.

[0025] In the present invention, no matter one engine is tested or zero engines are tested, a switch valve, a pressure sensor and a gas detector are arranged on the liquid ammonia supply pipe, which can accurately detect the pressure and concentration of the fuel, and feed the information back to the control system, so as to realize precise control of the supply system according to different working conditions (double-machine test, single-machine test, double-machine shutdown). Through the coordinated control of the valve, pressure sensor and gas detector by the control system, a nitrogen supply pipe and an exhaust gas discharge pipe and corresponding purge valves and release valves are arranged, which can effectively remove the residual materials in the supply system, and make the ammonia fuel supply pipeline device completely free of ammonia, prevent the potential risks caused by material residues, avoid the harm of toxic gas ammonia to operators, eliminate the risks of gas leakage and explosion, and ensure the safety of personnel operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0027] Figure 1 This is a schematic diagram of the dual-engine ammonia fuel supply system for the engine of the present invention.

[0028] In the figure: 1. first switch valve; 2. first pressure sensor; 3. first gas detector; 4. second switch valve; 5. first release valve; 6. first purge valve; 7. third switch valve; 8. second pressure sensor; 9. second gas detector; 10. second purge valve; 11. second release valve; 12. fourth switch valve; 13. first engine; 14. second engine; 15. first exhaust gas discharge pipe; 16. first nitrogen supply pipe; 17. first liquid ammonia supply pipe; 18. first compressed air supply pipe; 19. second exhaust gas discharge pipe; 20. second nitrogen supply pipe; 21. second liquid ammonia supply pipe; 22. second compressed air supply pipe. DETAILED DESCRIPTION

[0029] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0030] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless otherwise explicitly stated in the present invention, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "include" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof;

[0031] This embodiment discloses a dual-engine ammonia fuel supply system for an engine, such as Figure 1 As shown, it includes a first engine 13, a second engine 14, a material storage device, a supply system and a control system; the material storage device is connected to the supply system, and a gasification device and a pressure reducing valve are provided on the material storage device for storing and releasing liquefied materials required for combustion; the supply system is divided into a first supply system and a second supply system, which are used to provide fuel to the first engine 13 and the second engine 14, and can remove the remaining materials in the supply system; the first supply system and the second supply system are both connected to the control system, and the control system is used to control the fuel supply and excess fuel removal tasks of the first supply system and the second supply system according to different working conditions; the first engine 13 and the second engine 14 are installed inside the workshop, and the material storage device, the supply system and the control system are arranged outside the workshop; the ammonia fuel supply requirements for dual-engine operation are met, and at the same time, when one or zero engines are tested, the ammonia fuel supply pipeline device is completely free of ammonia to ensure the safety of operators.

[0032] The material storage device is provided with a nitrogen tank, a compressed air tank and a liquid ammonia tank; the first supply system includes a first exhaust gas discharge pipe 15, a first nitrogen supply pipe 16, a first liquid ammonia supply pipe 17 and a first compressed air supply pipe 18; one end of the first compressed air supply pipe 18 is connected to the compressed air tank, and the other end is connected to the intake pipe of the first engine 13, so as to provide oxygen for the fuel combustion of the first engine 13; one end of the first liquid ammonia supply pipe 17 is connected to the liquid ammonia tank, and the other end is connected to the intake pipe of the first engine 13, and the first liquid ammonia supply pipe 17 is provided with a first switch valve 1 and a second switch valve 4, the first switch valve 1 is arranged close to the liquid ammonia tank, and the second switch valve 4 is arranged close to the first engine 13 intake pipe arrangement, a first pressure sensor 2 and a first gas detector 3 are arranged between the first switch valve 1 and the second switch valve 4, for detecting the pressure and concentration of the fuel in the first liquid ammonia supply pipe 17; one end of the first nitrogen supply pipe 16 is connected to the nitrogen tank, and the other end is connected to the first liquid ammonia supply pipe 17, and the connection position is located between the first switch valve 1 and the second switch valve 4, and a first purge valve 6 is arranged on the first nitrogen supply pipe 16; one end of the first exhaust gas discharge pipe 15 is connected to the exhaust gas pipeline, and the other end is connected to the first liquid ammonia supply pipe 17, and the connection position is also located between the first switch valve 1 and the second switch valve 4, and a first release valve 5 is arranged on the first exhaust gas discharge pipe 15.

[0033] The second supply system includes a second exhaust gas discharge pipe 19, a second nitrogen supply pipe 20, a second liquid ammonia supply pipe 21 and a second compressed air supply pipe 22; one end of the second compressed air supply pipe 22 is connected to the compressed air tank, and the other end is connected to the intake pipe of the second engine 14, which is used to provide oxygen for the fuel combustion of the second engine 14; one end of the second liquid ammonia supply pipe 21 is connected to the liquid ammonia tank, and the other end is connected to the intake pipe of the second engine 14, and the second liquid ammonia supply pipe 21 is provided with a third switch valve 7 and a fourth switch valve 12, the third switch valve 7 is arranged close to the liquid ammonia tank, and the fourth switch valve 12 is arranged close to the intake pipe of the second engine 14. A second pressure sensor 8 and a second gas detector 9 are arranged between the valve 7 and the fourth switch valve 12, which are used to detect the pressure and concentration of the fuel in the second liquid ammonia supply pipe 21; one end of the second nitrogen supply pipe 20 is connected to the nitrogen tank, and the other end is connected to the second liquid ammonia supply pipe 21, and the connection position is located between the third switch valve 7 and the fourth switch valve 12, and a second purge valve 10 is arranged on the second nitrogen supply pipe 20; one end of the second exhaust gas discharge pipe 19 is connected to the exhaust gas pipeline, and the other end is connected to the second liquid ammonia supply pipe 21, and the connection position is also located between the third switch valve 7 and the fourth switch valve 12, and a second release valve 11 is arranged on the second exhaust gas discharge pipe 19.

[0034] The control system is connected to the first switch valve 1, the second switch valve 4, the third switch valve 7, the fourth switch valve 12, the first purge valve 6, the second purge valve 10, the first release valve 5, the second release valve 11, the first pressure sensor 2, the first gas detector 3, the second pressure sensor 8 and the second gas detector 9 respectively. The control system controls the opening and closing of different valves according to the three working conditions of the ammonia fuel supply requirement of the dual-engine operation, two engine test run, one engine test run or zero engine test run; if the two engines are tested at the same time, the first switch valve 1, the second switch valve 4, the third switch valve 7 and the fourth switch valve 12 are all in the open state under the control of the control system, and the first purge valve 6, the second purge valve 3, the second pressure sensor 8 and the second gas detector 9 are all in the open state. 10. The first release valve 5 and the second release valve 11 are both in the closed state; if the first engine 13 is tested, it is necessary to ensure the pipeline safety of the second liquid ammonia supply pipe 21, and the third switch valve 7 and the fourth switch valve 12 need to be closed. At the same time, the second purge valve 10 and the second release valve 11 do not operate, and the second pressure sensor 8 and the second gas detector 9 enter the monitoring state. When the second pressure sensor 8 and the second gas detector 9 reach the preset alarm value of the control system, the second purge valve 10 and the second release valve 11 are opened to release the toxic gas ammonia therein, so as to ensure that the corresponding supply pipeline is safe when the corresponding engine is not running, and to ensure that there is no corresponding risk in personnel operation and no risk of gas leakage and explosion.

[0035] Working method:

[0036] S1. When the first engine 13 and the second engine 14 are tested at the same time, the control system controls the first switch valve 1, the second switch valve 4, the third switch valve 7 and the fourth switch valve 12 to be in the open state, and the control system controls the first purge valve 6, the second purge valve 10, the first release valve 5 and the second release valve 11 to be in the closed state. The first liquid ammonia supply pipe 17 and the first compressed air supply pipe 18 transport the liquid ammonia fuel and compression control to the intake pipe of the first engine 13 for combustion of the first engine 13; the second liquid ammonia supply pipe 21 and the second compressed air supply pipe 22 transport the liquid ammonia fuel and compression control to the intake pipe of the second engine 14 for combustion of the second engine 14.

[0037] S2. When the first engine 13 is tested and the second engine 14 is stopped: it is necessary to ensure the pipeline safety of the second liquid ammonia supply pipe 21, and the third switch valve 7 and the fourth switch valve 12 need to be closed. At the same time, the second purge valve 10 and the second release valve 11 do not operate, and the second pressure sensor 8 and the second gas detector 9 enter the monitoring state. When the second pressure sensor 8 and the second gas detector 9 reach the preset alarm value of the control system, the second purge valve 10 and the second release valve 11 are opened, and nitrogen is blown into the second liquid ammonia supply pipe 21 along the second nitrogen supply pipe 20, and the toxic gas ammonia therein is diluted and discharged through the second exhaust gas discharge pipe 19.

[0038] S3. When the first engine 13 and the second engine 14 stop at the same time, the first switch valve 1 and the second switch valve 4 are closed, and the first purge valve 6 and the first release valve 5 do not operate, and the first pressure sensor 2 and the first gas detector 3 enter the monitoring state. When the first pressure sensor 2 and the first gas detector 3 reach the preset alarm value of the control system, the first purge valve 6 and the first release valve 5 are opened, and nitrogen is blown into the first liquid ammonia supply pipe 17 along the first nitrogen supply pipe 16, and the toxic gas in the liquid ammonia is discharged through the first exhaust pipe 15. The third switch valve 7 and the fourth switch valve 12 are closed, and the second purge valve 10 and the second release valve 11 are not operated, and the second pressure sensor 8 and the second gas detector 9 enter the monitoring state. When the second pressure sensor 8 and the second gas detector 9 reach the preset alarm value of the control system, the second purge valve 10 and the second release valve 11 are opened, and the nitrogen is blown into the second liquid ammonia supply pipe 21 along the second nitrogen supply pipe 20, and the toxic gas ammonia therein is diluted and discharged through the second exhaust gas discharge pipe 19.

[0039] Although the above describes the specific implementation mode of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without creative work are still within the scope of protection of the present invention.

Claims

1. An engine dual-engine ammonia fuel supply system, characterized in that: It includes a first engine, a second engine, a material storage device, a supply system and a control system; The material storage device is connected to the supply system, and is provided with a gasification device and a pressure reducing valve for storing and releasing liquefied materials required for combustion; The supply system is divided into a first supply system and a second supply system, which are used to provide fuel to the first engine and the second engine and can remove the remaining materials in the supply system; the first supply system and the second supply system are both connected to the control system, and the control system is used to control the fuel supply and excess fuel removal tasks of the first supply system and the second supply system according to different working conditions; The first engine and the second engine are installed inside the workshop, and the material storage device, the supply system and the control system are arranged outside the workshop.

2. The engine dual-engine ammonia fuel supply system according to claim 1, characterized in that: The material storage device is provided with a nitrogen tank, a compressed air tank and a liquid ammonia tank.

3. The engine dual-engine ammonia fuel supply system as claimed in claim 2, characterized in that: The first supply system includes a first exhaust gas discharge pipe, a first nitrogen supply pipe, a first liquid ammonia supply pipe and a first compressed air supply pipe; One end of the first compressed air supply pipe is connected to the compressed air tank, and the other end is connected to the first engine intake pipe, so as to provide oxygen for the fuel combustion of the first engine; one end of the first liquid ammonia supply pipe is connected to the liquid ammonia tank, and the other end is connected to the first engine intake pipe; one end of the first nitrogen supply pipe is connected to the nitrogen tank, and the other end is connected to the first liquid ammonia supply pipe; one end of the first exhaust gas discharge pipe is connected to the exhaust gas pipeline, and the other end is connected to the first liquid ammonia supply pipe.

4. The engine dual-engine ammonia fuel supply system as claimed in claim 3, characterized in that: The first liquid ammonia supply pipe is provided with a first switch valve and a second switch valve. The first switch valve is arranged close to the liquid ammonia tank, and the second switch valve is arranged close to the first engine intake pipe. A first pressure sensor and a first gas detector are arranged between the first switch valve and the second switch valve.

5. The engine dual-engine ammonia fuel supply system as claimed in claim 4, characterized in that: The connection point between the first exhaust gas discharge pipe and the first liquid ammonia supply pipe is located between the first switch valve and the second switch valve, and the first nitrogen supply pipe is provided with a first purge valve; the connection point between the first exhaust gas discharge pipe and the first liquid ammonia supply pipe is also located between the first switch valve and the second switch valve, and the first exhaust gas discharge pipe is provided with a first release valve.

6. The engine dual-engine ammonia fuel supply system as claimed in claim 1, characterized in that: The second supply system includes a second exhaust gas discharge pipe, a second nitrogen supply pipe, a second liquid ammonia supply pipe and a second compressed air supply pipe; one end of the second compressed air supply pipe is connected to the compressed air tank, and the other end is connected to the second engine intake pipe, for providing oxygen for the second engine fuel combustion; one end of the second liquid ammonia supply pipe is connected to the liquid ammonia tank, and the other end is connected to the second engine intake pipe; one end of the second nitrogen supply pipe is connected to the nitrogen tank, and the other end is connected to the second liquid ammonia supply pipe; one end of the second exhaust gas discharge pipe is connected to the exhaust gas pipeline, and the other end is connected to the second liquid ammonia supply pipe.

7. The engine dual-engine ammonia fuel supply system as claimed in claim 6, characterized in that: A third switch valve and a fourth switch valve are arranged on the second liquid ammonia supply pipe. The third switch valve is arranged close to the liquid ammonia tank, and the fourth switch valve is arranged close to the second engine intake pipe. A second pressure sensor and a second gas detector are arranged between the third switch valve and the fourth switch valve for detecting the pressure and concentration of the fuel in the second liquid ammonia supply pipe.

8. The engine dual-engine ammonia fuel supply system as claimed in claim 7, characterized in that: The connection point between the second nitrogen supply pipe and the second liquid ammonia supply pipe is located between the third switch valve and the fourth switch valve, and a second purge valve is provided on the second nitrogen supply pipe; the connection point between the second exhaust gas discharge pipe and the second liquid ammonia supply pipe is also located between the third switch valve and the fourth switch valve, and a second release valve is provided on the second exhaust gas discharge pipe.

9. The engine dual-engine ammonia fuel supply system as claimed in claim 1, characterized in that: The control system is respectively connected to the first switch valve, the second switch valve, the third switch valve, the fourth switch valve, the first purge valve, the second purge valve, the first release valve, the second release valve, the first pressure sensor, the first gas detector, the second pressure sensor and the second gas detector.

10. A method for operating a dual-engine ammonia fuel supply system according to any one of claims 2 to 9, characterized in that: The following steps are involved: S1. When the first engine and the second engine are tested at the same time, the control system controls the first switch valve, the second switch valve, the third switch valve and the fourth switch valve to be in an open state, and the control system controls the first purge valve, the second purge valve, the first release valve and the second release valve to be in a closed state, and the first liquid ammonia supply pipe and the first compressed air supply pipe deliver the liquid ammonia fuel and the compression control to the intake pipe of the first engine; the second liquid ammonia supply pipe and the second compressed air supply pipe deliver the liquid ammonia fuel and the compression control to the intake pipe of the second engine; S2, when the first engine is tested and the second engine is stopped: the third switch valve and the fourth switch valve are closed, and the second purge valve and the second release valve are not operated, and the second pressure sensor and the second gas detector enter the monitoring state. When the second pressure sensor and the second gas detector reach the preset alarm value of the control system, the second purge valve and the second release valve are opened, and nitrogen is blown into the second liquid ammonia supply pipe along the second nitrogen supply pipe, and the toxic gas ammonia is diluted and discharged through the second exhaust gas discharge pipe; S3. When the first engine and the second engine are stopped at the same time, the first switch valve and the second switch valve are closed, and the first purge valve and the first release valve are not operated. The first pressure sensor and the first gas detector enter the monitoring state. When the first pressure sensor and the first gas detector reach the preset alarm values ​​of the control system, the first purge valve and the first release valve are opened, and nitrogen is blown into the first liquid ammonia supply pipe along the first nitrogen supply pipe, and the toxic gas ammonia therein is diluted and discharged through the first exhaust gas discharge pipe. When the second engine is stopped, the control method of the control system described in S2 is used.

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