Security system and control method for ammonia fuel low-speed engine test bed

Abstract

The application discloses an ammonia fuel low-speed engine test bench security system and a control method. a ) The control method comprises the following steps: a) sealing performance test before starting the ammonia fuel engine; b) normal starting and no-leakage operation of the ammonia fuel engine; c) starting and operation of the ammonia fuel low-speed engine with slight leakage of not more than 200 ppm; and d) starting and operation of the ammonia fuel low-speed engine with serious leakage of more than 200 ppm. The application recycles the leaked ammonia fuel into the ammonia evaporation tank outdoors under different working conditions of slight leakage or serious leakage of the ammonia fuel, ensures the safety of on-site personnel, and provides reliable guarantee for safe and reliable test running of the ammonia fuel low-speed engine.

Description

TECHNICAL FIELD

[0001] The application relates to a new energy engine test bench, in particular to an ammonia fuel low-speed (n <= 300 rpm) engine bench test security system and a control method, and belongs to the technical field of new energy engines. BACKGROUND

[0002] With the gradual implementation of the double-carbon strategy of "carbon peak and carbon neutralization", ammonia fuel as a zero-carbon fuel is attracting more and more attention, and preliminary progress has been made in the research and development of marine low-speed engines. At present, all major global marine low-speed engine manufacturers are actively promoting the development of ammonia fuel low-speed engines, but ammonia is gaseous at normal temperature and pressure, and high-concentration ammonia is toxic to the human body, and ammonia has a certain corrosiveness to carbon steel. Therefore, when conducting ammonia fuel low-speed engine bench tests, effective ammonia leakage protection measures must be taken to avoid ammonia leakage causing harm to on-site test personnel, so as to ensure safe and reliable debugging and testing of ammonia fuel low-speed engines and promote the zero-carbon development of marine engines. SUMMARY

[0003] The purpose of the application is to provide a marine ammonia fuel low-speed engine test bench security system and a control method to meet the safety requirements of ammonia fuel low-speed engine testing, and effectively and reliably handle ammonia leakage to ensure the safety of on-site test personnel.

[0004] The application is implemented by the following technical solutions:

[0005] The application relates to an ammonia fuel low-speed engine test bed security system, which comprises a plurality of two-way electromagnetic valves, a plurality of one-way valves, a plurality of pressure sensors, a blowing fan, an exhaust fan, a manual two-way valve, a buffer tank, an ammonia detector, a three-way electromagnetic valve and a flowmeter located in a room where the ammonia fuel low-speed engine is located, and an ammonia vapor tank located outdoors; a low-pressure nitrogen pipe is connected with a first two-way electromagnetic valve, a high-pressure nitrogen pipe is connected with a second two-way electromagnetic valve, and then the two pipes are combined into a connecting pipe; the connecting pipe is connected with a fifth two-way electromagnetic valve and a fifth one-way valve in sequence, and then the connecting pipe is divided into two pipes; one pipe is connected with a D3 port of a nitrogen fuel leakage pipe at the bottom of the ammonia fuel engine, and the other pipe is connected with one end of the ammonia vapor tank through a wall; the connecting pipe at the joint of the low-pressure nitrogen pipe and the high-pressure nitrogen pipe is divided into two branches; one branch is connected with an outer pipe of a D2 output double-wall pipe of the ammonia fuel low-speed engine through a third two-way electromagnetic valve and a first one-way valve in sequence; the connecting pipe of the outer pipe of the D2 output double-wall pipe is connected with an ammonia vapor tank through a wall through an eighth two-way electromagnetic valve, an ammonia detector, an exhaust fan, a bypass end of a three-way electromagnetic valve, a straight-through E2 end of the three-way electromagnetic valve and then the other end of the ammonia vapor tank; the other branch is connected with a D1 input double-wall pipe of the ammonia fuel low-speed engine through a fourth two-way electromagnetic valve and a second one-way valve in sequence, and then the branch is divided into two branches; one branch is connected with a B2 atmospheric input pipe port at normal temperature and pressure; the other branch is connected with a B1 port of a 0.7-1.0 MPa pressure dry compressed air input pipe through a hand-operated two-way valve and a seventh two-way electromagnetic valve; signal lines of a PLC controller are connected with control ends of the two-way electromagnetic valves, the pressure sensors, the blowing fan, the exhaust fan and the flowmeter.

[0006] The application can also be achieved by the following technical measures.

[0007] Further, a first pressure sensor is connected to the connecting pipe at the joint of the first two-way electromagnetic valve and the second two-way electromagnetic valve; a second pressure sensor is connected to the connecting pipe of the first one-way valve and the outer pipe of the D2 output double-wall pipe of the ammonia fuel low-speed engine; and a third pressure sensor is connected to the connecting pipe of the flowmeter and the buffer tank.

[0008] Further, the pressure of the low-pressure nitrogen pipe is 0.3 MPa, and the pressure of the high-pressure nitrogen pipe is 3.0 MPa.

[0009] Further, the pressure detection range of the first pressure sensor, the second pressure sensor and the third pressure sensor is 0-15 MPa, and the output current signal is 4-20 mA.

[0010] Further, the measurement range of the ammonia detector is 0-1000 ppm, the measurement accuracy is less than or equal to 1 ppm, and the output current signal is 4-20 mA.

[0011] Further, the air volume of the air supply fan is 60m 3 / h, and the air volume of the air exhaust fan is 40m 3 / h.

[0012] Further, the capacity of the buffer tank is 0.8-1.2m 3 .

[0013] A control method of an ammonia fuel low-speed engine test bed security system, comprising the following corresponding steps of different working conditions:

[0014] a) sealing performance test before starting the ammonia fuel engine

[0015] a1) the PLC controller sends a signal to open the second two-way electromagnetic valve, and close the third two-way electromagnetic valve, the fourth two-way electromagnetic valve, the sixth two-way electromagnetic valve and the eighth two-way electromagnetic valve, so that the 3Mpa high-pressure nitrogen gas input from the A2 port of the high-pressure nitrogen gas pipe is closed in the connecting pipeline after passing through the second two-way electromagnetic valve;

[0016] a2) when the first pressure sensor detects a pressure of 3.0Mpa, the PLC controller sends a signal to close the second two-way electromagnetic valve, and pressurizes the system for 10 minutes, if the nitrogen pressure decreases by no more than 10kpa within 10 minutes, the system meets the sealing requirement;

[0017] b) normal start and no leakage operation of the ammonia fuel engine

[0018] b1) in a dry environment where the air temperature is more than 20℃ and the air humidity is less than 30%, when the ammonia fuel engine is normally running, ordinary air is used to ventilate the outer wall pipe of the double-wall pipe; the PLC controller sends a signal to start the air supply fan, and respectively opens the sixth two-way electromagnetic valve, the eighth two-way electromagnetic valve, the air exhaust fan, and the bypass end and the straight-through E1 end of the three-way electromagnetic valve; the atmospheric air at normal temperature and pressure enters from the B2 atmospheric air input port of the input pipeline, passes through the air supply fan, the fourth one-way valve, the buffer tank, the flow meter, the third one-way valve and the sixth two-way electromagnetic valve in turn, enters the outer pipe of the D1 input double-wall pipe of the ammonia fuel low-speed engine, and then is output from the outer pipe of the D2 output double-wall pipe of the ammonia fuel low-speed engine, passes through the eighth two-way electromagnetic valve, the ammonia detector, the air exhaust fan, the bypass end and the straight-through E1 end of the three-way electromagnetic valve in turn, and is discharged from the C port of the exhaust pipeline that penetrates through the wall;

[0019] b2) When the atmospheric environment does not reach the condition that the air temperature exceeds 20℃ and the air humidity is less than 30%, the manual two-way valve is opened, and the PLC controller sends a signal to open the sixth two-way electromagnetic valve, the seventh two-way electromagnetic valve and the eighth two-way electromagnetic valve respectively, and the bypass end of the three-way electromagnetic valve and the straight-through E1 end of the three-way electromagnetic valve are turned on, 0.7Mpa dry compressed air is input from the B1 input port of the air inlet pipe, sequentially passes through the seventh two-way electromagnetic valve, the manual two-way valve, the buffer tank, the flow meter, the third one-way valve and the sixth two-way electromagnetic valve, enters the outer pipe of the double-wall pipe from the D1 input of the ammonia fuel low-speed engine, and then is output from the outer pipe of the double-wall pipe from the D2 output of the ammonia fuel low-speed engine, sequentially passes through the eighth electromagnetic valve, the ammonia detector and the exhaust fan, and then is discharged from the C port of the exhaust pipe leading to the outdoor through the bypass end of the three-way electromagnetic valve and the straight-through E1 end of the three-way electromagnetic valve which are turned on;

[0020] c) Start-up operation when the ammonia fuel low-speed engine has a slight leakage of not more than 200ppm

[0021] When the ammonia detector detects that the ammonia fuel has a slight leakage of not more than 200ppm, the PLC controller sends a signal to open the first two-way electromagnetic valve and the fourth two-way electromagnetic valve respectively, and closes the third two-way electromagnetic valve, at this time, 0.3Mpa nitrogen gas is input from the A1 port of the low-pressure nitrogen pipe, sequentially passes through the first two-way electromagnetic valve, the fourth two-way electromagnetic valve and the second one-way valve, enters the outer pipe of the double-wall pipe from the D1 input of the ammonia fuel, and then is output from the outer pipe of the double-wall pipe from the D2 output of the ammonia fuel, sequentially passes through the eighth electromagnetic valve, the ammonia detector and the exhaust fan, and then is output from the bypass end of the three-way electromagnetic valve and the straight-through E2 end of the three-way electromagnetic valve which are turned on, and then enters the ammonia vapor tank outside through the connecting pipe to collect the leaked ammonia fuel; at the same time, the PLC controller sends a signal to open the fifth two-way electromagnetic valve for 20 seconds every 10 minutes, and the 0.3Mpa nitrogen gas input from the A1 port of the low-pressure nitrogen pipe passes through the fifth one-way valve, and then combines with the ammonia fuel leaked from the D3 leakage port at the bottom of the ammonia fuel engine to blow back to the ammonia vapor tank for collecting the ammonia fuel;

[0022] d) Start-up operation when the ammonia fuel low-speed engine has a serious leakage of more than 200ppm

[0023] When the ammonia detector detects that the ammonia fuel has a serious leakage of more than 200 ppm, the PLC controller sends a signal to open the first two-way electromagnetic valve, the second two-way electromagnetic valve, the fourth two-way electromagnetic valve and the eighth two-way electromagnetic valve, and to close the third two-way electromagnetic valve; the 3Mpa pressure high-pressure nitrogen gas input from the A! port of the high-pressure nitrogen gas pipe passes through the first two-way electromagnetic valve, the fourth two-way electromagnetic valve and the second one-way valve in sequence, is input into the outer pipe of the ammonia fuel D1 input double-wall pipe, then passes through the outer pipe outlet of the ammonia fuel D2 output double-wall pipe, and then passes through the eighth two-way electromagnetic valve, the ammonia detector, the exhaust fan, and then the bypass end of the three-way electromagnetic valve and the straight-through E2 end of the three-way electromagnetic valve, and then enters the outdoor ammonia vapor tank through the connecting pipeline with the leaked ammonia fuel; at the same time, the PLC controller sends a signal to open the fifth two-way electromagnetic valve, and the high-pressure nitrogen gas passes through the fifth two-way electromagnetic valve and the fifth one-way valve in sequence, and the ammonia fuel leaked from the bottom D3 port of the ammonia fuel engine is blown back to the ammonia vapor tank for collecting the ammonia fuel.

[0024] The application adopts the structure that a plurality of two-way electromagnetic valves, a plurality of one-way valves, a three-way electromagnetic valve, a supply fan, an exhaust fan and an ammonia detector are connected through connecting pipelines, provides a safe and reliable ammonia fuel low-speed engine bench test security system and control method through different combination methods of electromagnetic valve opening and closing, and different input types of high-pressure nitrogen gas, low-pressure nitrogen gas, compressed air and environmental air, realizes the sealing performance test before starting of the ammonia fuel engine, and realizes that the leaked ammonia fuel is collected into the outdoor ammonia evaporation tank under different working conditions of no leakage, slight leakage and serious leakage of the ammonia fuel engine during normal starting of the ammonia fuel engine. The risk of harm to human body when ammonia leakage occurs in the ammonia fuel low-speed engine bench test is effectively reduced, the safety of the on-site personnel is ensured, and reliable protection is provided for safe and reliable test running of the ammonia fuel low-speed engine.

[0025] The advantages and characteristics of the application will be illustrated and explained by the following non-limiting description of preferred embodiments, which are given by way of example only, with reference to the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a schematic diagram of an ammonia fuel low-speed engine test running bench security system. DETAILED DESCRIPTION

[0027] The application will be further described below with reference to the accompanying drawings and embodiments.

[0028] As Figure 1As shown, the ammonia fuel low-speed engine test stand security system of the present application comprises eight two-way electromagnetic valves, five one-way valves, three pressure sensors, a supply fan 41, an exhaust fan 42, a manual two-way valve 5, a buffer tank 6, an ammonia detector 7, a three-way electromagnetic valve 8 and a flow meter 9 located in the room where the ammonia fuel low-speed engine 100 is located, and an ammonia vapor tank 20 located outdoors. The low-pressure nitrogen pipe 101 passes through the first two-way electromagnetic valve 11, and the high-pressure nitrogen pipe 102 passes through the second two-way electromagnetic valve 12 to merge into a connecting pipe 103. The connecting pipe 103 is connected to the fifth two-way electromagnetic valve 15 and the fifth one-way valve 25 in sequence and then divided into two paths. One path of the connecting pipe 103 is connected to the D3 port of the nitrogen fuel leakage pipe 104 at the bottom of the ammonia fuel engine 100, and the other path of the connecting pipe 103 passes through the wall 200 and is connected to one end of the ammonia vapor tank 10. The connecting pipe 103 at the merging point of the low-pressure nitrogen pipe 101 and the high-pressure nitrogen pipe 102 is divided into two branches. One branch is connected to the outer pipe of the D2 output double-wall pipe 105 of the ammonia fuel low-speed engine 100 in sequence through the third two-way electromagnetic valve 13 and the first one-way valve 21. The connecting pipe 103 of the outer pipe of the D2 output double-wall pipe 105 further passes through the eighth two-way electromagnetic valve 18, the ammonia detector 7, the exhaust fan 42, the bypass end 81 of the three-way electromagnetic valve, the straight-through E2 end 82 of the three-way electromagnetic valve, and then passes through the wall 200 and is connected to the other end of the ammonia vapor tank 20. The other branch is divided into two paths in sequence through the fourth two-way electromagnetic valve 14 and the second one-way valve 22. One path is connected to the outer pipe of the D1 input double-wall pipe 106 of the ammonia fuel low-speed engine 100, and the other path is connected to the B2 atmospheric air input pipe 108 port in sequence through the sixth two-way electromagnetic valve 16, the third one-way valve 23, the flow meter 9, the buffer tank 6, the fourth one-way valve 24 and the supply fan 41. One end of the buffer tank 6 is connected to the B1 port of the 0.7-1.0 MPa dry compressed air input pipe 108 in sequence through the manual two-way valve 5 and the seventh two-way electromagnetic valve 17. The signal line 301 of the PLC controller 30 is connected to the control end of each two-way electromagnetic valve, each pressure sensor, the supply fan 41, the exhaust fan 42 and the flow meter 9.

[0029] The first pressure sensor 31 is connected to the connecting pipe 103 at the merging point of the first two-way electromagnetic valve 11 and the second two-way electromagnetic valve 12, the second pressure sensor 32 is connected to the connecting pipe 103 between the first one-way valve 21 and the outer pipe of the D2 output double-wall pipe 106 of the ammonia fuel low-speed engine, and the third pressure sensor 33 is connected to the connecting pipe 103 between the flow meter 9 and the buffer tank 6. The pressure of the low-pressure nitrogen pipe 101 is 0.3 MPa, and the pressure of the high-pressure nitrogen pipe 102 is 3.0 MPa.

[0030] The pressure detection range of the first pressure sensor 31, the second pressure sensor 32 and the third pressure sensor 33 is 0-15 Mpa, and the output current signal is 4-20 mA.

[0031] The measurement range of the ammonia detector 7 is 0-1000 ppm, the measurement accuracy is ≤1 ppm, and the output current signal is 4-20 mA. The air volume of the air supply fan 41 is 60 m 3 / h, and the air volume of the air exhaust fan 42 is 40 m 3 / h. Under the control of the PLC controller 30, the air supply fan 41 and the air exhaust fan 42 ensure that the air exchange volume is 30-40 times per hour, and the single air exchange volume is the total capacity of all double-wall outer pipes. The capacity of the buffer tank 6 is 0.8-1.2 m 3 , mainly used to ensure the relative stability of the supply gas pressure. The main function of the ammonia vapor tank 20 is to separate and recover ammonia in the mixed gas to prevent it from being directly discharged into the atmosphere.

[0032] A control method of an ammonia fuel low-speed engine test bed security system, comprising the following corresponding steps of different working conditions:

[0033] a) Sealing performance test before starting the ammonia fuel engine 100

[0034] a1) The PLC controller 30 sends a signal to open the second two-way electromagnetic valve 12, close the third two-way electromagnetic valve 13, the fourth two-way electromagnetic valve 14, the sixth two-way electromagnetic valve 16 and the eighth two-way electromagnetic valve 18, and the 3.0 Mpa high-pressure nitrogen gas input from the A2 port of the high-pressure nitrogen gas pipe 102 is sealed in the connecting pipe 103 after passing through the second two-way electromagnetic valve 12.

[0035] a2) When the first pressure sensor 31 detects a pressure of 3.0 Mpa, the PLC controller 30 sends a signal to close the second two-way electromagnetic valve 12, and the system is pressure-protected for 10 minutes. If the nitrogen pressure decreases by no more than 10 kpa within 10 minutes of pressure protection, the system meets the sealing requirements.

[0036] b) Normal start and no leakage of the ammonia fuel engine

[0037] b1) In the dry environment where the air temperature is more than 20℃ and the air humidity is less than 30%, the outer wall of the double-wall pipe is ventilated with normal air when the ammonia fuel engine 100 is running normally. The PLC controller 30 sends a signal to start the air supply fan 41, and opens the sixth two-way electromagnetic valve 16, the eighth two-way electromagnetic valve 18, the air exhaust fan 42, and the three-way electromagnetic valve bypass end 83 and the three-way electromagnetic valve straight-through E1 end 81. The atmospheric air at normal temperature and pressure enters the B2 atmospheric air inlet port of the input pipeline 108, passes through the air supply fan 41, the fourth one-way valve 24, the buffer tank 6, the flow meter 9, the third one-way valve 23, and the sixth two-way electromagnetic valve 16 in turn, enters the outer pipe of the D1 input double-wall pipe 105 of the ammonia fuel low-speed engine 100, and then is output from the outer pipe of the D2 output double-wall pipe 106 of the ammonia fuel low-speed engine 100, passes through the eighth two-way electromagnetic valve 18, the ammonia detector 7, the air exhaust fan 42, the three-way electromagnetic valve bypass end 83 and the three-way electromagnetic valve straight-through E1 end 81 in turn, and is discharged from the C port of the exhaust pipeline 109 that penetrates the wall 200;

[0038] b2) In the atmospheric environment where the air temperature is not more than 20℃ and the air humidity is less than 30%, open the manual two-way valve 5, and the PLC controller 30 sends a signal to open the sixth two-way electromagnetic valve 16, the seventh two-way electromagnetic valve 17, and the eighth two-way electromagnetic valve 18, and to conduct the three-way electromagnetic valve bypass end 83 and the three-way electromagnetic valve straight-through E1 end 81. 0.7Mpa dry compressed air is input from the B1 input port of the air inlet pipe 107, passes through the seventh two-way electromagnetic valve 17, the manual two-way valve 5, the buffer tank 6, the flow meter 9, the third one-way valve 23, and the sixth two-way electromagnetic valve 16 in turn, enters the outer pipe of the D1 input double-wall pipe 105 of the ammonia fuel low-speed engine 100, is output from the outer pipe of the D2 output double-wall pipe 106 of the ammonia fuel low-speed engine 100, passes through the eighth electromagnetic valve 18, the ammonia detector 7, and the air exhaust fan 42 in turn, and is discharged from the C port of the exhaust pipeline 109 that penetrates the wall 200.

[0039] c) Start-up operation when the ammonia fuel low-speed engine has a slight leakage of not more than 200ppm

[0040] When the ammonia detector 7 detects that the ammonia fuel has a slight leakage of no more than 200 ppm, the PLC controller 30 sends a signal to open the first two-way electromagnetic valve 11 and the fourth two-way electromagnetic valve 14, and to close the third two-way electromagnetic valve 13, at this time, the nitrogen gas with a pressure of 0.3 MPa from the A1 port of the low-pressure nitrogen gas pipe 101 enters in turn through the first two-way electromagnetic valve 11, the fourth two-way electromagnetic valve 14 and the second one-way valve 22, enters the outer pipe of the ammonia fuel D1 input double-wall pipe 105, and then is output from the outer pipe of the ammonia fuel D2 output double-wall pipe 106, in turn passes through the eighth electromagnetic valve 18, the ammonia detector 7 and the exhaust fan 42, and then is output from the bypass end 83 of the three-way electromagnetic valve and the straight-through E2 end 82 of the three-way electromagnetic valve, and then enters the ammonia vapor tank 20 outside through the connecting pipe 103 to collect the leaked ammonia fuel. At the same time, the PLC controller 30 sends a signal to open the fifth two-way electromagnetic valve 15 every 10 minutes and lasts for 20 seconds, the nitrogen gas with a pressure of 0.3 MPa from the A1 port of the low-pressure nitrogen gas pipe 101 enters, passes through the fifth one-way valve 25, and is combined with the ammonia fuel leaked from the ammonia fuel low-speed engine bottom D3 leakage port 104, and is blown back to the ammonia vapor tank 20 for collecting the ammonia fuel.

[0041] d) Start-up operation of the ammonia fuel low-speed engine 100 in the case of serious leakage of more than 200 ppm

[0042] When the ammonia detector 7 detects that the ammonia fuel has a serious leakage of more than 200 ppm, the PLC controller 30 sends a signal to open the first two-way electromagnetic valve 11, the second two-way electromagnetic valve 12, the fourth two-way electromagnetic valve 14 and the eighth two-way electromagnetic valve 18, and to close the third two-way electromagnetic valve 13. The high-pressure nitrogen gas with a pressure of 3.0 MPa from the A1 port of the high-pressure nitrogen gas pipe 101 enters in turn through the first two-way electromagnetic valve 11, the fourth two-way electromagnetic valve 14 and the second one-way valve 22, enters the outer pipe of the ammonia fuel D1 input double-wall pipe 105, and then passes through the outer pipe outlet of the ammonia fuel D2 output double-wall pipe 106, and then in turn passes through the eighth two-way electromagnetic valve 18, the ammonia detector 7, the exhaust fan 42, and then from the bypass end 83 of the three-way electromagnetic valve and the straight-through E2 end 82 of the three-way electromagnetic valve, and then through the connecting pipe 103 into the ammonia vapor tank 20 outside with the leaked ammonia fuel. At the same time, the PLC controller 30 sends a signal to open the fifth two-way electromagnetic valve 15, and the high-pressure nitrogen gas passes through the fifth two-way electromagnetic valve 15 and the fifth one-way valve 25 in turn, and blows the ammonia fuel leaked from the D3 port 104 at the bottom of the ammonia fuel engine 100 back to the ammonia vapor tank 20 for collecting the ammonia fuel.

[0043] In addition to the above-mentioned embodiments, the present application can also have other implementation manners, and any technical solutions formed by equivalent replacement or equivalent transformation shall fall within the protection scope of the present application.

Claims

1. An ammonia fuel low-speed engine test stand security system, comprising a plurality of two-way electromagnetic valves, a plurality of one-way valves, a plurality of pressure sensors, a supply air fan, an exhaust air fan, a manual two-way valve, a buffer tank, an ammonia detector, a three-way electromagnetic valve, and a flow meter located in a room where an ammonia fuel low-speed engine is located, and an ammonia vapor tank located outdoors; characterized in that, The low-pressure nitrogen pipe passes through the first two-way electromagnetic valve, and the high-pressure nitrogen pipe passes through the second two-way electromagnetic valve to merge into a connecting pipe. The connecting pipe is connected with the fifth two-way electromagnetic valve and the fifth one-way valve in sequence and then is divided into two pipes. One pipe is connected with the nitrogen fuel leakage pipe D3 at the bottom of the ammonia fuel engine, and the other pipe passes through the wall and is connected with one end of the ammonia vapor tank. The connecting pipe at the merging point of the low-pressure nitrogen pipe and the high-pressure nitrogen pipe is divided into two branches. One branch is connected with the outer pipe of the D2 output double-wall pipe of the ammonia fuel low-speed engine in sequence through the third two-way electromagnetic valve and the first one-way valve. The connecting pipe of the outer pipe of the D2 output double-wall pipe also passes through the eighth two-way electromagnetic valve, the ammonia detector, the exhaust fan, the bypass end of the three-way electromagnetic valve, the straight-through E2 end of the three-way electromagnetic valve, and then passes through the wall and is connected with the other end of the ammonia vapor tank. The other branch is divided into two branches in sequence through the fourth two-way electromagnetic valve and the second one-way valve. One branch is connected with the outer pipe of the D1 input double-wall pipe of the ammonia fuel low-speed engine. The other branch is connected with the atmospheric input pipe B2 port at normal temperature and pressure in sequence through the sixth two-way electromagnetic valve, the third one-way valve, the flow meter, the buffer tank, the fourth one-way valve, and the air supply fan. One end of the buffer tank is connected with the B1 port of the 0.7-1.0 Mpa dry compressed air input pipe in sequence through the manual two-way valve and the seventh two-way electromagnetic valve. The signal lines of the PLC controller are connected with the control ends of the two-way electromagnetic valves, the pressure sensors, the air supply fan, the exhaust fan, and the flow meter.

2. The ammonia-fueled low-speed engine test stand security system of claim 1, wherein: The first pressure sensor is connected to the connecting pipe at the merging point of the first two-way electromagnetic valve and the second two-way electromagnetic valve. The second pressure sensor is connected to the connecting pipe between the first one-way valve and the outer pipe of the D2 output double-wall pipe of the ammonia fuel low-speed engine. The third pressure sensor is connected to the connecting pipe between the flow meter and the buffer tank.

3. The ammonia-fueled low-speed engine test stand security system of claim 1, wherein: The pressure of the low-pressure nitrogen pipe is 0.3 Mpa, and the pressure of the high-pressure nitrogen pipe is 3.0 Mpa.

4. The ammonia-fueled low-speed engine test stand security system of claim 1, wherein: The pressure detection range of the first pressure sensor, the second pressure sensor, and the third pressure sensor is 0-15 Mpa, and the output current signal is 4-20 mA.

5. The ammonia-fueled low-speed engine test stand security system of claim 1, wherein: The measurement range of the ammonia detector is 0-1000 ppm, and the measurement accuracy is ≤1 ppm. The output current signal is 4-20 mA.

6. The ammonia-fueled low-speed engine test stand security system of claim 1, wherein: The air volume of the air supply fan is 60 m 3 The air volume of the air supply fan is 60 m 3 / h.

7. The ammonia-fueled low-speed engine test stand security system of claim 1, wherein: The buffer tank has a capacity of 0.8-1.2 m 3 .

8. A control method of the ammonia fuel low-speed engine test stand security system according to any one of claims 1 to 7, characterized by: The corresponding steps of the following different working conditions are included: a) Sealing performance test before starting the ammonia fuel engine a1) The PLC controller sends a signal to open the second two-way electromagnetic valve and close the third two-way electromagnetic valve, the fourth two-way electromagnetic valve, the sixth two-way electromagnetic valve, and the eighth two-way electromagnetic valve. The 3 Mpa high-pressure nitrogen gas input from the high-pressure nitrogen pipe A2 port is sealed in the connecting pipe after passing through the second two-way electromagnetic valve; a2) When the first pressure sensor detects a pressure of 3.0 Mpa, the PLC controller sends a signal to close the second two-way electromagnetic valve and pressurizes the system for 10 minutes. If the nitrogen pressure decreases by no more than 10 kpa within 10 minutes of pressure maintenance, the system meets the sealing requirements; b) Normal start and no leakage operation of the ammonia fuel engine b1) When the ammonia fuel engine is running normally in a dry environment with air temperature over 20℃ and air humidity less than 30%, the outer wall of the double-wall pipe is ventilated with ordinary air at this time; the PLC controller sends a signal to start the air supply fan, and opens the sixth two-way electromagnetic valve, the eighth two-way electromagnetic valve, the air exhaust fan, and the bypass end of the three-way electromagnetic valve and the straight-through E1 end of the three-way electromagnetic valve; atmospheric air at normal temperature and pressure enters the B2 atmospheric air inlet port of the input pipeline, passes through the air supply fan, the fourth one-way valve, the buffer tank, the flow meter, the third one-way valve, and the sixth two-way electromagnetic valve in turn, enters the outer pipe of the D1 input double-wall pipe of the ammonia fuel low-speed engine, and then is output from the outer pipe of the D2 output double-wall pipe of the ammonia fuel low-speed engine, passes through the eighth two-way electromagnetic valve, the ammonia detector, the air exhaust fan, the bypass end of the three-way electromagnetic valve and the straight-through E1 end of the three-way electromagnetic valve in turn, and is discharged from the C port of the exhaust pipeline that penetrates the wall; b2) When the atmospheric environment does not reach the environment with air temperature over 20℃ and air humidity less than 30%, open the manual two-way valve, and the PLC controller sends a signal to open the sixth two-way electromagnetic valve, the seventh two-way electromagnetic valve and the eighth two-way electromagnetic valve, and the bypass end of the three-way electromagnetic valve and the straight-through E1 end of the three-way electromagnetic valve are turned on, 0.7Mpa dry compressed air is input from the B1 input port of the air inlet pipeline, passes through the seventh two-way electromagnetic valve, the manual two-way valve, the buffer tank, the flow meter, the third one-way valve and the sixth two-way electromagnetic valve in turn, enters the outer pipe of the D1 input double-wall pipe of the ammonia fuel low-speed engine, and then is output from the outer pipe of the D2 output double-wall pipe of the ammonia fuel low-speed engine, passes through the eighth electromagnetic valve, the ammonia detector and the air exhaust fan in turn, and then passes through the bypass end of the three-way electromagnetic valve and the straight-through E1 end of the three-way electromagnetic valve that are turned on, and is discharged from the C port of the exhaust pipeline that leads to the outdoor; c) Start-up operation when the ammonia fuel low-speed engine has a slight leakage of not more than 200ppm When the ammonia detector detects that the ammonia fuel has a slight leakage of not more than 200ppm, the PLC controller sends a signal to open the first two-way electromagnetic valve and the fourth two-way electromagnetic valve, and closes the third two-way electromagnetic valve, nitrogen gas at a pressure of 0.3Mpa enters from the A1 port of the low-pressure nitrogen gas pipeline, passes through the first two-way electromagnetic valve, the fourth two-way electromagnetic valve and the second one-way valve in turn, enters the outer pipe of the ammonia fuel input double-wall pipe D1, and then is output from the outer pipe of the ammonia fuel output double-wall pipe D2, passes through the eighth electromagnetic valve, the ammonia detector and the air exhaust fan in turn, and then is output from the bypass end of the three-way electromagnetic valve and the straight-through E2 end of the three-way electromagnetic valve that are turned on, and then enters the outdoor ammonia vapor tank through the connecting pipeline to collect the leaked ammonia fuel; at the same time, the PLC controller sends a signal to open the fifth two-way electromagnetic valve for 20 seconds every 10 minutes, and the nitrogen gas at a pressure of 0.3Mpa input from the A1 port of the low-pressure nitrogen gas pipeline passes through the fifth one-way valve, and combines with the ammonia fuel leaked from the ammonia fuel D3 leakage port at the bottom of the ammonia fuel engine, and blows back to the ammonia vapor tank for collecting ammonia fuel; d) Start-up operation when the ammonia fuel low-speed engine has a serious leakage of more than 200ppm When the ammonia detector detects that the ammonia fuel has a serious leakage of more than 200 ppm, the PLC controller sends a signal to open the first two-way electromagnetic valve, the second two-way electromagnetic valve, the fourth two-way electromagnetic valve and the eighth two-way electromagnetic valve, and to close the third two-way electromagnetic valve; the high-pressure nitrogen gas with a pressure of 3.0 Mpa input from the A! port of the high-pressure nitrogen gas pipe passes through the first two-way electromagnetic valve, the fourth two-way electromagnetic valve and the second one-way valve in sequence, is input into the outer pipe of the ammonia fuel D1 input double-wall pipe, then passes through the outer pipe outlet of the ammonia fuel D2 output double-wall pipe, and then passes through the eighth two-way electromagnetic valve, the ammonia detector, the air suction fan, and then the bypass end of the three-way electromagnetic valve and the straight-through E2 end of the three-way electromagnetic valve, and then enters the outdoor ammonia vapor tank with the leaked ammonia fuel through the connecting pipeline; at the same time, the PLC controller sends a signal to open the fifth two-way electromagnetic valve, and the high-pressure nitrogen gas passes through the fifth two-way electromagnetic valve and the fifth one-way valve in sequence, and blows the ammonia fuel leaked from the bottom D3 port of the ammonia fuel engine back to the ammonia vapor tank for collecting the ammonia fuel.

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