Ammonia fuel low-speed engine test bed security system and control method

Abstract

The invention discloses an ammonia fuel low-speed engine test bed security system and a control method. The system comprises a plurality of two-way electromagnetic valves, a plurality of one-way valves, a plurality of pressure sensors, an air supply fan, an air draft fan, a manual two-way valve, a buffer tank, an ammonia detector, a three-way electromagnetic valve, a flow meter and an outdoor ammonia steam tank. The control method comprises the following steps: a) testing the sealing performance of the ammonia fuel engine before starting, b) normally starting the ammonia fuel engine without leakage, c) starting the ammonia fuel low-speed engine when the ammonia fuel low-speed engine has slight leakage of not more than 200ppm, and d) starting the ammonia fuel low-speed engine when the ammonia fuel low-speed engine has serious leakage of more than 200ppm. Under different working conditions of slight leakage or serious leakage of the ammonia fuel, the leaked ammonia fuel is recovered into the outdoor ammonia evaporation tank, so that the safety of field personnel is ensured, and a reliable guarantee is provided for safe and reliable test run of the ammonia fuel low-speed engine.

Description

Technical Field

[0001] The present invention relates to a new energy engine test bench, in particular to a safety system and a control method for a low-speed (n≤300rpm) engine bench test using an ammonia fuel, belonging to the technical field of new energy engines. Background Art

[0002] With the gradual implementation of the dual carbon strategy of "carbon peak and carbon neutrality", ammonia fuel as a zero-carbon fuel has received more and more attention, and initial progress has been made in the research and development of marine low-speed engines. At present, major marine low-speed engine manufacturers around the world are actively promoting the development of ammonia fuel low-speed engines, but ammonia is gaseous at room temperature and pressure, and high concentrations of ammonia are toxic to the human body. At the same time, ammonia is corrosive to carbon steel. Therefore, when conducting bench tests on ammonia fuel low-speed engines, effective ammonia leakage protection measures must be taken to avoid ammonia leakage causing harm to on-site test personnel, thereby ensuring safe and reliable commissioning and testing of ammonia fuel low-speed engines and promoting the zero-carbon development of marine engines. Summary of the invention

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

[0004] The present invention is achieved through the following technical solutions:

[0005] A security system for an ammonia fuel low-speed engine test bench, comprising a plurality of two-way solenoid valves, a plurality of one-way valves, a plurality of pressure sensors, an air supply fan, an exhaust fan, a manual two-way valve, a buffer tank, an ammonia detector, a three-way solenoid valve and a flow meter located in a room where the ammonia fuel low-speed engine is located, and an ammonia steam tank located outdoors; a low-pressure nitrogen pipe passes through a first two-way solenoid valve, and a high-pressure nitrogen pipe passes through a second two-way solenoid valve and then merges into a connecting pipeline, and the connecting pipeline is connected to a fifth two-way solenoid valve and a fifth one-way valve connected in sequence and then split into two routes, one connecting pipeline is connected to a D3 port of a nitrogen fuel leakage pipe at the bottom of the ammonia fuel engine, and the other connecting pipeline passes through a wall and is connected to one end of the ammonia steam tank; the connecting pipeline at the junction of the low-pressure nitrogen pipe and the high-pressure nitrogen pipe is further divided into two branches, and one branch is connected to the outer pipe of a D2 output double-wall pipe of the ammonia fuel low-speed engine after passing through a third two-way solenoid valve and a first one-way valve in sequence. The connecting pipeline of the outer pipe of the D2 output double-wall pipe also passes through the eighth two-way solenoid valve, the ammonia detector, the exhaust fan, the bypass end of the three-way solenoid valve, and the direct E2 end of the three-way solenoid valve in sequence, and then passes through the wall to communicate with the other end of the ammonia steam tank; the other branch passes through the fourth two-way solenoid valve and the second one-way valve in sequence and then splits into two forks. The connecting pipeline of one fork is connected to the outer pipe of the D1 input double-wall pipe of the ammonia fuel low-speed engine; the other fork passes through the sixth two-way solenoid valve, the third one-way valve, the flow meter, the buffer tank, the fourth one-way valve and the air supply fan in sequence, and is connected to the atmospheric input pipe port at normal temperature and pressure of B2; one end of the buffer tank is connected to the B1 port of the dry compressed air input pipe with a pressure of 0.7 to 1.0 MPa through the manual two-way valve and the seventh solenoid valve in sequence; the signal line of the PLC controller is respectively connected to the control end of each two-way solenoid valve, each pressure sensor, the air supply fan, the exhaust fan and the flow meter.

[0006] The purpose of the present invention can also be achieved in one step through the following technical measures.

[0007] Furthermore, the first pressure sensor is connected in parallel to the connecting pipeline where the first two-way solenoid valve and the second two-way solenoid valve meet; the second pressure sensor is connected in parallel to the connecting pipeline 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 in parallel to the connecting pipeline between the flow meter and the buffer tank.

[0008] Furthermore, 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] Furthermore, the pressure detection ranges of the first pressure sensor, the second pressure sensor and the third pressure sensor are all 0-15 MPa, and the output current signals are 4-20 mA.

[0010] Furthermore, the measurement range of the ammonia detector is 0 to 1000 ppm, the measurement accuracy is ≤ 1 ppm, and the output current signal is 4 to 20 mA.

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

[0012] Furthermore, the capacity of the buffer tank is 0.8 to 1.2 m 3 .

[0013] A control method for a safety system of an ammonia fuel low-speed engine test bench includes the following corresponding steps under different working conditions:

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

[0015] a1) The PLC controller sends a signal to open the second two-way solenoid valve, close the third two-way solenoid valve, the fourth two-way solenoid valve, the sixth two-way solenoid valve and the eighth two-way solenoid valve, and the 3Mpa high-pressure nitrogen input from the high-pressure nitrogen pipe input port A2 passes through the second two-way solenoid valve and is sealed in the connecting pipeline;

[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 solenoid valve and maintain the system pressure for 10 minutes. If the nitrogen pressure does not drop by more than 10kpa within 10 minutes, the system meets the sealing requirements;

[0017] b) Ammonia fuel engine starts normally and runs without leakage

[0018] b1) In a dry environment with a temperature exceeding 20°C and an air humidity less than 30%, when the ammonia fuel engine is operating normally, ordinary air is used to ventilate the outer wall of the double-walled tube; the PLC controller sends a signal to start the air supply fan, and respectively opens the sixth two-way solenoid valve, the eighth two-way solenoid valve, the exhaust fan, and the bypass end of the three-way solenoid valve and the direct E1 end of the three-way solenoid valve; the normal temperature and pressure atmosphere enters from the B2 atmospheric 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 solenoid valve in sequence, enters the outer tube of the D1 input double-walled tube of the ammonia fuel low-speed engine, and then is output from the outer tube of the D2 output double-walled tube of the ammonia fuel low-speed engine, passes through the eighth two-way solenoid valve, the ammonia detector, the exhaust fan, the bypass end of the three-way solenoid valve that is turned on, and the direct E1 end of the three-way solenoid valve, and is discharged from the C port of the exhaust pipeline that passes through the wall;

[0019] b2) When the atmospheric temperature does not exceed 20°C and the air humidity is less than 30%, open the manual two-way valve, and at the same time, the PLC controller sends a signal to open the sixth two-way solenoid valve, the seventh two-way solenoid valve and the eighth two-way solenoid valve, respectively, and connect the bypass end of the three-way solenoid valve and the direct E1 end of the three-way solenoid valve. Input 0.7Mpa dry compressed air from the B1 input port of the intake pipe, pass through the seventh two-way solenoid valve, the manual two-way valve, the buffer tank, the flow meter, the third one-way valve and the sixth two-way solenoid valve in sequence, enter from the outer tube of the D1 input double-walled tube of the ammonia fuel low-speed engine, and then output from the outer tube of the D2 output double-walled tube of the ammonia fuel low-speed engine, pass through the eighth solenoid valve, the ammonia detector and the exhaust fan in sequence, and then pass through the bypass end of the three-way solenoid valve and the direct E1 end of the three-way solenoid valve, and be discharged from the C port of the exhaust pipe leading to the outdoors;

[0020] c) Starting and running of ammonia fuel low-speed engine with a slight leak not exceeding 200 ppm

[0021] When the ammonia detector detects a slight leakage of no more than 200ppm of ammonia fuel, the PLC controller sends a signal to open the first two-way solenoid valve and the fourth two-way solenoid valve respectively, and close the third two-way solenoid valve. At this time, nitrogen with a pressure of 0.3Mpa enters from the A1 port of the low-pressure nitrogen pipe, passes through the first two-way solenoid valve, the fourth two-way solenoid valve and the second one-way valve in sequence, enters from the outer tube of the double-walled tube of the ammonia fuel D1 input, and then exits from the outer tube of the double-walled tube of the ammonia fuel D2 output, passes through the eighth solenoid valve, the ammonia detector in sequence, and the nitrogen gas flows into the nitrogen gas pipeline. and exhaust fan, and then output from the bypass end of the three-way solenoid valve and the direct E2 end of the three-way solenoid valve, and then enter the outdoor ammonia steam 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 solenoid valve for 20 seconds every 10 minutes, and the nitrogen with a pressure of 0.3Mpa input from the A1 port of the low-pressure nitrogen pipe passes through the fifth one-way valve and merges with the ammonia fuel leaked from the nitrogen fuel D3 leakage port at the bottom of the ammonia fuel engine, and is blown back to the ammonia steam tank for collecting ammonia fuel;

[0022] d) Starting and operating ammonia fueled low speed engine with a severe leak exceeding 200 ppm

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

[0024] The present invention adopts a structure in which multiple two-way solenoid valves, multiple one-way valves, three-way solenoid valves, air supply fans, exhaust fans and ammonia detectors are connected by connecting pipes. Through different combination methods of opening and closing the solenoid valves, and through different input forms of high-pressure nitrogen, low-pressure nitrogen, compressed air and ambient air, a safe and reliable ammonia fuel low-speed engine bench test security system and control method are provided, and the sealing performance test before the start of the ammonia fuel engine is realized. Under different working conditions of normal start-up of the ammonia fuel engine without leakage, slight leakage of ammonia fuel and serious leakage of ammonia fuel, the leaked ammonia fuel is recovered into the outdoor ammonia evaporation tank. The risk of harm to the human body when ammonia leakage occurs in the bench test of the ammonia fuel low-speed engine is effectively reduced, the safety of on-site personnel is ensured, and reliable guarantee is provided for the safe and reliable test of the ammonia fuel low-speed engine.

[0025] Advantages and features of the present invention will be illustrated and explained by the following non-limiting description of preferred embodiments thereof, which are given by way of example only with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is the schematic diagram of the safety system of the ammonia fuel low-speed engine test bench. DETAILED DESCRIPTION

[0027] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0028] like Figure 1As shown, the security system of the ammonia fuel low-speed engine test bench of the present invention includes 8 two-way solenoid valves, 5 one-way valves, 3 pressure sensors, an air supply fan 41, an exhaust fan 42, a manual two-way valve 5, a buffer tank 6, an ammonia detector 7, a three-way solenoid valve 8 and a flow meter 9 located in the room where the ammonia fuel low-speed engine 100 is located, and an ammonia steam tank 20 located outdoors. The low-pressure nitrogen pipe 101 passes through the first two-way solenoid valve 11, and the high-pressure nitrogen pipe 102 passes through the second two-way solenoid valve 12 and then merges into a connecting pipeline 103. The connecting pipeline 103 is connected to the fifth two-way solenoid valve 15 and the fifth one-way valve 25 connected in sequence and then divided into two routes. One connecting pipeline 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 connecting pipeline 103 passes through the wall 200 and is connected to one end of the ammonia steam tank 10. The connecting pipeline 103 at the junction of the low-pressure nitrogen pipe 101 and the high-pressure nitrogen pipe 102 is further divided into two branches, one of which passes through the third two-way solenoid valve 13 and the first one-way valve 21 in sequence and is connected to the outer pipe of the D2 output double-wall pipe 105 of the ammonia fuel low-speed engine 100. The connecting pipeline 103 of the outer pipe of the D2 output double-wall pipe 105 also passes through the eighth two-way solenoid valve 18, the ammonia detector 7, the exhaust fan 42, the three-way solenoid valve bypass end 81, the three-way solenoid valve direct E2 end 82, and then passes through the wall 200 to communicate with the other end of the ammonia steam tank 20. The other branch is divided into two forks after passing through the fourth two-way solenoid valve 14 and the second one-way valve 22 in sequence. The connecting pipeline 103 of one fork is connected to the outer tube of the D1 input double-walled pipe 106 of the ammonia fuel low-speed engine 100; the other branch is connected to the port of the atmospheric input pipe 108 at normal temperature and pressure at B2 through the sixth two-way solenoid valve 16, the third one-way valve 23, the flow meter 9, the buffer tank 6, the fourth one-way valve 24 and the air supply fan 41 in sequence. One end of the buffer tank 6 is connected to the B1 port of the dry compressed air input pipe 108 with a pressure of 0.7 to 1.0 MPa through the manual two-way valve 5 and the seventh solenoid valve 17 in sequence. The signal line 301 of the PLC controller 30 is respectively connected to the control end of each two-way solenoid valve, each pressure sensor, the air supply fan 41, the exhaust fan 42 and the flow meter 9.

[0029] The first pressure sensor 31 is connected to the connecting pipeline 103 where the first two-way solenoid valve 11 and the second two-way solenoid valve 12 meet, the second pressure sensor 32 is connected to the connecting pipeline 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 pipeline 103 between the flow meter 9 and the buffer tank 6. The pressure of the low-pressure nitrogen pipe 101 is 0.3Mpa, and the pressure of the high-pressure nitrogen pipe 102 is 3.0Mpa.

[0030] The pressure detection ranges of the first pressure sensor 31 , the second pressure sensor 32 and the third pressure sensor 33 are all 0 to 15 MPa, and the output current signals are 4 to 20 mA.

[0031] The measuring range of the ammonia detector 7 is 0 to 1000 ppm, and the measuring accuracy is ≤ 1 ppm; the output current signal is 4 to 20 mA. The air volume of the air supply fan 41 is 60 m 3 / h, the air volume of the exhaust fan 42 is 40m 3 / h. Through the control of the PLC controller 30, the air supply fan 41 and the exhaust fan 42 ensure that the air volume is changed 30 to 40 times per hour, and the single air volume is the total capacity of all double-walled outer tubes. The capacity of the buffer tank 6 is 0.8 to 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 for a safety system of an ammonia fuel low-speed engine test bench includes the following corresponding steps under 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 solenoid valve 12, and close the third two-way solenoid valve 13, the fourth two-way solenoid valve 14, the sixth two-way solenoid valve 16 and the eighth two-way solenoid valve 18. The 3.0 MPa high-pressure nitrogen input from the A2 port of the high-pressure nitrogen pipe 102 passes through the second two-way solenoid valve 12 and is sealed in the connecting pipeline 103.

[0035] a2) When the first pressure sensor 31 detects that the pressure is 3.0 MPa, the PLC controller 30 sends a signal to close the second two-way solenoid valve 12 and maintain the system pressure for 10 minutes. If the nitrogen pressure does not drop by more than 10 kPa within 10 minutes, the system meets the sealing requirements.

[0036] b) Ammonia fuel engine starts normally and runs without leakage

[0037] b1) In a dry environment with a temperature of more than 20°C and air humidity less than 30%, when the ammonia fuel engine 100 is operating normally, ordinary air is used to ventilate the outer wall of the double-walled tube. The PLC controller 30 sends a signal to start the air supply fan 41, and respectively opens the sixth two-way solenoid valve 16, the eighth two-way solenoid valve 18, the exhaust fan 42, and the bypass end 83 of the three-way solenoid valve and the direct E1 end 81 of the three-way solenoid valve. Normal temperature and pressure atmosphere enters from the B2 atmospheric 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 solenoid valve 16 in sequence, enters the outer tube of the D1 input double-walled pipe 105 of the ammonia fuel low-speed engine 100, and then is output from the outer tube of the D2 output double-walled pipe 106 of the ammonia fuel low-speed engine 100, passes through the eighth two-way solenoid valve 18, the ammonia detector 7, the exhaust fan 42, the bypass end 83 of the conductive three-way solenoid valve and the direct E1 end 81 of the three-way solenoid valve in sequence, and is discharged from the C port of the exhaust pipeline 109 passing through the wall 200;

[0038] b2) When the air temperature does not exceed 20°C and the air humidity is less than 30%, the manual two-way valve 5 is opened, and at the same time, the PLC controller 30 sends a signal to open the sixth two-way solenoid valve 16, the seventh two-way solenoid valve 17 and the eighth two-way solenoid valve 18 respectively, and the three-way solenoid valve bypass end 83 and the three-way solenoid valve direct E1 end 81 are connected, and 0.7Mpa dry compressed air is input from the B1 input port of the intake pipe 107, and passes through the seventh two-way solenoid valve 17, the manual two-way valve 18 in sequence. 5, the buffer tank 6, the flow meter 9, the third one-way valve 23 and the sixth two-way solenoid valve 16, enter from the outer tube of the double-walled tube 105 input from D1 of the ammonia fuel low-speed engine 100, and then output from the outer tube of the double-walled tube 106 output from D2 of the ammonia fuel low-speed engine 100, pass through the eighth solenoid valve 18, the ammonia detector 7 and the exhaust fan 42 in sequence, and then pass through the conductive three-way solenoid valve bypass end 83 and the three-way solenoid valve direct E1 end 81, and be discharged from the C port of the exhaust pipe 109 leading to the outdoors.

[0039] c) Starting and running of ammonia fuel low-speed engine with a slight leak not exceeding 200 ppm

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

[0041] d) Starting and operating an ammonia fuel low speed engine 100 with a severe leak exceeding 200 ppm

[0042] When the ammonia detector 7 detects a serious leakage of ammonia fuel exceeding 200ppm, the PLC controller 30 sends a signal to open the first two-way solenoid valve 11, the second two-way solenoid valve 12, the fourth two-way solenoid valve 14 and the eighth two-way solenoid valve 18, and close the third two-way solenoid valve 13. The high-pressure nitrogen with a pressure of 3.0Mpa input from the A! port of the high-pressure nitrogen pipe 101 passes through the first two-way solenoid valve 11, the fourth two-way solenoid valve 14 and the second one-way valve 22 in sequence, enters the outer tube of the ammonia fuel D1 input double-walled pipe 105, and then passes through the outer tube outlet of the ammonia fuel D2 output double-walled pipe 106, and then passes through the eighth two-way solenoid valve 18, the ammonia detector 7, the exhaust fan 42 in sequence, and then from the bypass end 83 of the three-way solenoid valve and the direct E2 end 82 of the three-way solenoid valve, and then enters the outdoor ammonia vapor tank 20 through the connecting pipeline 103 with the leaked ammonia fuel. At the same time, the PLC controller 30 sends a signal to open the fifth two-way solenoid valve 15, and the high-pressure nitrogen passes through the fifth two-way solenoid valve 15 and the fifth one-way valve 25 in sequence, blowing the ammonia fuel leaked from the D3 port 104 at the bottom of the ammonia fuel engine 100 back to the ammonia steam tank 20 for collecting the ammonia fuel.

[0043] In addition to the above embodiments, the present invention may also have other implementation modes. Any technical solutions formed by equivalent replacement or equivalent transformation shall fall within the protection scope required by the present invention.

Claims

1. An ammonia fuel low-speed engine test bench security system, comprising a plurality of two-way solenoid valves, a plurality of one-way valves, a plurality of pressure sensors, a supply fan, an exhaust fan, a manual two-way valve, a buffer tank, an ammonia detector, a three-way solenoid valve and a flow meter located in a room where the ammonia fuel low-speed engine is located, and an ammonia steam tank located outdoors; characterized in that, The low-pressure nitrogen pipe passes through the first two-way solenoid valve, and the high-pressure nitrogen pipe passes through the second two-way solenoid valve and then merges into a connecting pipeline. The connecting pipeline is connected to the fifth two-way solenoid valve and the fifth one-way valve connected in sequence and then divided into two routes. One connecting pipeline is connected to the nitrogen fuel leakage pipe D3 port at the bottom of the ammonia fuel engine, and the other connecting pipeline passes through the wall and is connected to one end of the ammonia steam tank; the connecting pipeline at the junction of the low-pressure nitrogen pipe and the high-pressure nitrogen pipe is further divided into two branches, and one branch is connected to the outer pipe of the D2 output double-wall pipe of the ammonia fuel low-speed engine after passing through the third two-way solenoid valve and the first one-way valve in sequence; the connecting pipeline of the outer pipe of the D2 output double-wall pipe also passes through the eighth two-way solenoid valve, the ammonia detector, the exhaust fan, the bypass end of the three-way solenoid valve, the three-way solenoid valve, the The valve goes straight to the E2 end, then passes through the wall to communicate with the other end of the ammonia steam tank; the other branch passes through the fourth two-way solenoid valve and the second one-way valve in sequence and then splits into two forks. The connecting pipeline of one fork is connected to the outer pipe of the D1 input double-wall pipe of the ammonia fuel low-speed engine; the other fork passes through the sixth two-way solenoid valve, the third one-way valve, the flow meter, the buffer tank, the fourth one-way valve and the air supply fan in sequence, and is connected to the B2 port of the atmospheric input pipe at normal temperature and pressure; one end of the buffer tank is connected to the B1 port of the dry compressed air input pipe with a pressure of 0.7~1.0Mpa through the manual two-way valve and the seventh solenoid valve in sequence; the signal line of the PLC controller is respectively connected to the control end of each two-way solenoid valve, each pressure sensor, the air supply fan, the exhaust fan and the flow meter.

2. The ammonia fuel low-speed engine test bench safety system according to claim 1, characterized in that: The first pressure sensor is connected in parallel to the connecting pipeline where the first two-way solenoid valve and the second two-way solenoid valve meet; the second pressure sensor is connected in parallel to the connecting pipeline 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 in parallel to the connecting pipeline between the flow meter and the buffer tank.

3. The ammonia fuel low-speed engine test bench safety system according to claim 1, characterized in that: The pressure of the low-pressure nitrogen pipe is 0.3Mpa, and the pressure of the high-pressure nitrogen pipe is 3.0Mpa.

4. The ammonia fuel low-speed engine test bench safety system according to claim 1, characterized in that: The pressure detection ranges of the first pressure sensor, the second pressure sensor and the third pressure sensor are all 0-15 MPa, and the output current signal is 4-20 mA.

5. The ammonia fuel low-speed engine test bench safety system according to claim 1, characterized in that: The measuring range of the ammonia detector is 0~1000ppm, and the measuring accuracy is ≤1ppm; the output current signal is 4~20mA.

6. The ammonia fuel low-speed engine test bench safety system according to claim 1, characterized in that: The air volume of the air supply fan is 60m 3 / h, the air volume of the exhaust fan is 40m 3 / h.

7. The ammonia fuel low-speed engine test bench safety system according to claim 1, characterized in that: The capacity of the buffer tank is 0.8~1.2m 3 .

8. A control method for the safety system of an ammonia fuel low-speed engine test bench according to any one of claims 1 to 7, characterized in that: The following steps are included for different working conditions: a) Sealing performance test before starting ammonia fuel engine a1) The PLC controller sends a signal to open the second two-way solenoid valve, close the third two-way solenoid valve, the fourth two-way solenoid valve, the sixth two-way solenoid valve and the eighth two-way solenoid valve, and the 3Mpa high-pressure nitrogen input from the high-pressure nitrogen pipe A2 port passes through the second two-way solenoid valve and is sealed in the connecting pipeline; a2) When the first pressure sensor detects a pressure of 3.0Mpa, the PLC controller sends a signal to close the second two-way solenoid valve and maintain the system pressure for 10 minutes. If the nitrogen pressure does not drop by more than 10kpa within 10 minutes, the system meets the sealing requirements; b) Ammonia fuel engine starts normally and runs without leakage b1) In a dry environment with a temperature exceeding 20°C and an air humidity less than 30%, when the ammonia fuel engine is operating normally, ordinary air is used to ventilate the outer wall of the double-walled tube; the PLC controller sends a signal to start the air supply fan, and respectively opens the sixth two-way solenoid valve, the eighth two-way solenoid valve, the exhaust fan, and the bypass end of the three-way solenoid valve and the direct E1 end of the three-way solenoid valve; the normal temperature and pressure atmosphere enters from the B2 atmospheric 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 solenoid valve in sequence, enters the outer tube of the D1 input double-walled tube of the ammonia fuel low-speed engine, and then is output from the outer tube of the D2 output double-walled tube of the ammonia fuel low-speed engine, passes through the eighth two-way solenoid valve, the ammonia detector, the exhaust fan, the bypass end of the three-way solenoid valve that is turned on, and the direct E1 end of the three-way solenoid valve, and is discharged from the C port of the exhaust pipeline that passes through the wall; b2) When the atmospheric temperature does not exceed 20°C and the air humidity is less than 30%, open the manual two-way valve, and at the same time, the PLC controller sends a signal to open the sixth two-way solenoid valve, the seventh two-way solenoid valve and the eighth two-way solenoid valve, respectively, and connect the bypass end of the three-way solenoid valve and the direct E1 end of the three-way solenoid valve. Input 0.7Mpa dry compressed air from the B1 input port of the intake pipe, pass through the seventh two-way solenoid valve, the manual two-way valve, the buffer tank, the flow meter, the third one-way valve and the sixth two-way solenoid valve in sequence, enter from the outer tube of the D1 input double-walled tube of the ammonia fuel low-speed engine, and then output from the outer tube of the D2 output double-walled tube of the ammonia fuel low-speed engine, pass through the eighth solenoid valve, the ammonia detector and the exhaust fan in sequence, and then pass through the bypass end of the three-way solenoid valve and the direct E1 end of the three-way solenoid valve, and be discharged from the C port of the exhaust pipe leading to the outdoors; c) Starting and running of ammonia fuel low-speed engine with a slight leak not exceeding 200 ppm When the ammonia detector detects a slight leakage of no more than 200ppm of ammonia fuel, the PLC controller sends a signal to open the first two-way solenoid valve and the fourth two-way solenoid valve respectively, and close the third two-way solenoid valve. At this time, nitrogen with a pressure of 0.3Mpa enters from the A1 port of the low-pressure nitrogen pipe, passes through the first two-way solenoid valve, the fourth two-way solenoid valve and the second one-way valve in sequence, enters from the outer tube of the ammonia fuel input double-wall pipe D1, and then exits from the outer tube of the ammonia fuel output double-wall pipe D2, passes through the eighth solenoid valve, the ammonia detector in sequence, and the nitrogen gas flows out of the ammonia fuel output pipe. and exhaust fan, and then output from the bypass end of the three-way solenoid valve and the direct E2 end of the three-way solenoid valve, and then enter the outdoor ammonia steam 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 solenoid valve for 20 seconds every 10 minutes, and the nitrogen with a pressure of 0.3Mpa input from the A1 port of the low-pressure nitrogen pipe passes through the fifth one-way valve and merges with the ammonia fuel leaked from the nitrogen fuel D3 leakage port at the bottom of the ammonia fuel engine, and is blown back to the ammonia steam tank for collecting ammonia fuel; d) Starting and operating ammonia fueled low speed engine with a severe leak exceeding 200 ppm When the ammonia detector detects a serious leakage of more than 200ppm of ammonia fuel, the PLC controller sends a signal to open the first two-way solenoid valve, the second two-way solenoid valve, the fourth two-way solenoid valve and the eighth two-way solenoid valve, and close the third two-way solenoid valve; the high-pressure nitrogen with a pressure of 3.0Mpa input from the A! port of the high-pressure nitrogen pipe passes through the first two-way solenoid valve, the fourth two-way solenoid valve and the second one-way valve in turn, enters the outer tube of the double-walled tube of the ammonia fuel D1, and then passes through the outer tube outlet of the double-walled tube of the ammonia fuel D2, and then passes through the eighth two-way solenoid valve, the ammonia detector, the exhaust fan, and then from the bypass end of the three-way solenoid valve and the direct E2 end of the three-way solenoid valve, and then through the connecting pipeline to carry the leaked ammonia fuel into the outdoor ammonia steam tank; at the same time, the PLC controller sends a signal to open the fifth two-way solenoid valve, and the high-pressure nitrogen passes through the fifth two-way solenoid valve and the fifth one-way valve in turn, and blows the ammonia fuel leaking from the D3 port at the bottom of the ammonia fuel engine back to the ammonia steam tank for collecting ammonia fuel.

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