Fuel recovery control method for ammonia fuel engine and ammonia fuel engine

Abstract

The present invention relates to the field of engine technology, and specifically discloses a fuel recovery control method for an ammonia fuel engine and an ammonia fuel engine. The fuel recovery control method for the ammonia fuel engine collects the pressure in a supply pipeline in real time and compares it with a first set pressure after the ammonia fuel engine is shut down. When the pressure in the supply pipeline does not exceed the first set pressure, the recovery pipeline is disconnected from the supply pipeline, so that most of the ammonia fuel in the supply pipeline can be recovered to a storage tank by natural pressure relief. Compared with the prior art, there is no need to directly purge with nitrogen, which can reduce the pressure requirements of the supply pipeline and components on the supply pipeline. Moreover, the recovered ammonia fuel is not mixed with nitrogen, and there is no need to perform separation operations. The process is simple, and the very small amount of ammonia fuel remaining in other components of the recovered supply pipeline is discharged by purging, thereby ensuring the safe use of the ammonia fuel engine.

Description

Technical Field

[0001] The present invention relates to the technical field of engines, and in particular to a fuel recovery control method of an ammonia fuel engine and an ammonia fuel engine. Background Art

[0002] Internal combustion engines usually use gasoline or diesel as their main fuel, and the carbon dioxide produced during operation can easily lead to climate change. Ammonia (NH3) is an excellent carbon-free hydrogen carrier and an attractive alternative to fossil fuels. The combustion of ammonia eliminates carbon and sulfur emissions, so ammonia-fueled engines have come into being. However, ammonia should be handled with special care when used in internal combustion engines, because leakage can cause serious health damage, such as burns to human skin, eyes, and mucous membranes of respiratory organs, and excessive inhalation can even cause lung swelling.

[0003] In order to ensure the safe use of ammonia fuel engines, in the prior art, when the ammonia engine stops working, the pipeline that supplies ammonia to the engine is usually purged with nitrogen until all the ammonia in the pipeline is discharged to ensure safe use. For example, the previous patent with application number CN202211345250.X discloses a marine ammonia fuel supply system and its fuel recovery device and method. When the engine stops running, the pipeline that supplies ammonia to the engine is purged with nitrogen, and liquid ammonia, ammonia gas, and nitrogen used for purging will all be collected in the liquid ammonia collection tank. By adding nitrogen to the liquid ammonia collection tank again to pressurize it, the ammonia gas in the tank is liquefied, and the liquid ammonia can be recycled again, while also ensuring the safe use of the ammonia engine. However, when the liquid ammonia in the liquid ammonia collection tank is recovered again, the nitrogen and liquid ammonia need to be separated to prevent the nitrogen from entering the supply system. However, the separation process is cumbersome and it is difficult to separate all the liquid ammonia, resulting in energy waste. At the same time, the residual ammonia fuel in the pipeline is purged with nitrogen, and the pressure of the nitrogen needs to be higher than the pressure of the ammonia fuel, which puts higher requirements on the pressure-bearing capacity of the pipeline. Summary of the invention

[0004] The purpose of the present invention is to provide a fuel recovery control method for an ammonia fuel engine and an ammonia fuel engine, so as to solve the problem that in the prior art, the pipeline for supplying ammonia is directly purged with nitrogen, and when recovering liquid ammonia, the nitrogen and liquid ammonia need to be separated, the process is cumbersome, and it is difficult to separate all the ammonia fuel, and the problem that nitrogen purging puts higher requirements on the pressure bearing capacity of the pipeline.

[0005] On the one hand, the present invention provides a fuel recovery control method for an ammonia fuel engine, the ammonia fuel engine comprising a liquid ammonia tank for storing liquid ammonia, an injector for injecting liquid ammonia, a supply pipeline connected between the liquid ammonia tank and the injector, a supply device arranged in the supply pipeline, a recovery pipeline selectively connected to the supply pipeline, a storage tank connected to the recovery pipeline, and a purge system for purging the supply pipeline, the supply device can drive the liquid ammonia in the liquid ammonia tank to enter the injector through the supply pipeline, the fuel recovery control method for the ammonia fuel engine comprises:

[0006] Get shutdown instructions;

[0007] Ammonia fuel engine shutdown;

[0008] Connecting the recovery pipeline to the supply pipeline;

[0009] Collect the pressure in the supply pipeline in real time and compare it with the first set pressure;

[0010] When the pressure in the supply pipeline does not exceed the first set pressure, disconnecting the recovery pipeline from the supply pipeline;

[0011] The ammonia fuel remaining in the supply pipeline is purged by a purging system.

[0012] As a preferred technical solution of the fuel recovery control method of the ammonia fuel engine, the fuel recovery control method of the ammonia fuel engine further includes between the step of disconnecting the recovery pipeline from the supply pipeline and the step of purging the ammonia fuel remaining in the supply pipeline by a purge system:

[0013] pressurizing the ammonia fuel in the storage tank and liquefying the ammonia fuel;

[0014] The liquefied ammonia fuel in the storage tank is transported to the liquid ammonia tank.

[0015] As a preferred technical solution of the fuel recovery control method of the ammonia fuel engine, a piston is slidably provided in the storage tank, and the piston separates the storage tank into a first chamber and a second chamber, the first chamber is connected to the recovery pipeline, and the second chamber is connected to the high-pressure gas source;

[0016] Pressurizing the ammonia fuel in the storage tank and liquefying the ammonia fuel comprises:

[0017] The high-pressure gas source is continuously used to fill the second cavity with high-pressure gas, and when the pressure in the first cavity reaches a second set pressure, the high-pressure gas source is stopped from filling the second cavity with high-pressure gas; the pressure of the high-pressure gas is not less than 10 bar, and the second set pressure is greater than the first set pressure.

[0018] As a preferred technical solution of the fuel recovery control method of the ammonia fuel engine, the storage tank is further provided with a vent valve connected to the second chamber, and the fuel recovery control method of the ammonia fuel engine further includes after the step of transporting the liquefied ammonia fuel to the liquid ammonia tank:

[0019] The air release valve is opened to discharge the high-pressure gas in the second chamber to the outside atmosphere, and when the gas pressure in the second chamber is equal to the first set pressure, the air release valve is closed.

[0020] As a preferred technical solution of the fuel recovery control method of the ammonia fuel engine, the purge system includes a nitrogen tank, an input pipeline, an exhaust pipeline and a burner, the nitrogen tank is used to store nitrogen, the nitrogen tank is connected to the input pipeline, the input pipeline is selectively connected to one end of the supply pipeline close to the liquid ammonia tank, the exhaust pipeline is selectively connected to one end of the supply pipeline close to the liquid ammonia tank, and the exhaust pipeline is connected to the burner;

[0021] Purging the ammonia fuel remaining in the supply pipeline by the purge system includes:

[0022] Connect the input pipeline to one end of the supply pipeline close to the liquid ammonia tank, and connect the discharge pipeline to one end of the supply pipeline away from the liquid ammonia tank;

[0023] The nitrogen tank is made to output nitrogen at a third set pressure for a set time, and the discharge pipeline delivers a mixture of nitrogen and ammonia fuel to the burner, and the ammonia fuel in the mixture undergoes a combustion reaction in the burner, and the third set pressure is greater than the first set pressure;

[0024] The input pipeline is disconnected from one end of the supply pipeline close to the liquid ammonia tank, and the discharge pipeline is disconnected from one end of the supply pipeline away from the liquid ammonia tank.

[0025] On the other hand, the present invention further provides an ammonia fuel engine for implementing the fuel recovery control method of the ammonia fuel engine described in any of the above schemes, the ammonia fuel engine comprising:

[0026] Liquid ammonia tank, used to store liquid ammonia;

[0027] An injector for injecting liquid ammonia;

[0028] A supply pipeline connected between the liquid ammonia tank and the injector;

[0029] A supply device, comprising a first solenoid valve, a liquid ammonia pump, a second solenoid valve, a common rail pipe and a third solenoid valve, which are sequentially arranged on the supply pipeline along the conveying direction of the ammonia fuel;

[0030] a recovery pipeline connected to the second solenoid valve, the second solenoid valve being used to connect or disconnect the recovery pipeline with the supply pipeline;

[0031] a storage tank, connected to the recovery pipeline;

[0032] A purge system is used to purge the portion of the supply pipeline between the first solenoid valve and the third solenoid valve, and the first solenoid valve and the third solenoid valve are used to connect the supply pipeline between the liquid ammonia tank and the injector, or to be connected in series to the purge system.

[0033] As a preferred technical solution for the ammonia fuel engine, a piston is slidably disposed in the storage tank, and the piston separates the storage tank into a first chamber and a second chamber, the first chamber is connected to the recovery pipeline, and the second chamber is connected to a high-pressure gas source.

[0034] As a preferred technical solution for the ammonia fuel engine, the storage tank is also provided with a vent valve connected to the second chamber; and / or the recovery pipeline is provided with a first one-way valve, which is configured to only allow the ammonia fuel to flow from the recovery pipeline to the first chamber.

[0035] As a preferred technical solution of the ammonia fuel engine, a tension spring is further provided in the second chamber, and two ends of the tension spring are respectively connected to the piston and the inner wall of the storage tank; and / or,

[0036] The first chamber is connected to the liquid ammonia tank via a connecting pipeline, and a fourth solenoid valve, a filter and a second one-way valve are sequentially provided on the connecting pipeline along the conveying direction of the ammonia fuel. The fourth solenoid valve is used to connect or disconnect the connecting pipeline, and the second one-way valve is configured to only allow the ammonia fuel to flow from the filter to the liquid ammonia tank.

[0037] As an optimal technical solution for an ammonia fuel engine, the purge system includes a nitrogen tank, a first pressure reducing valve, an input pipeline, an exhaust pipeline and a burner. The nitrogen tank is used to store nitrogen, and the nitrogen tank is connected to the input pipeline. The first pressure reducing valve is arranged on the input pipeline, and the input pipeline is connected to the first solenoid valve, and the exhaust pipeline is connected to the third solenoid valve. The first solenoid valve is used to connect the liquid ammonia pump to either the input pipeline or the liquid ammonia tank, and the third solenoid valve is used to connect the common rail pipe to either the injector or the exhaust pipeline.

[0038] The beneficial effects of the present invention are as follows:

[0039] The present invention provides a fuel recovery control method for an ammonia fuel engine and an ammonia fuel engine. The fuel recovery control method for the ammonia fuel engine collects the pressure in a supply pipeline in real time and compares it with a first set pressure after the ammonia fuel engine is shut down. When the pressure in the supply pipeline does not exceed the first set pressure, the recovery pipeline is disconnected from the supply pipeline. In this way, most of the ammonia fuel in the supply pipeline can be recovered to a storage tank by natural pressure relief. Compared with the prior art, there is no need for direct nitrogen purging, which can reduce the pressure requirements of the supply pipeline and components on the supply pipeline. Moreover, the recovered ammonia fuel is not mixed with nitrogen, and there is no need for separation operation. The process is simple. After recovery, the very small amount of ammonia fuel remaining in the supply pipeline and other components thereon is discharged by purging, thereby ensuring the safety of the ammonia fuel engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 The structure of the ammonia fuel engine in the embodiment of the present invention is shown in FIG. Figure 1 ;

[0041] Figure 2 The process of the fuel recovery control method of the ammonia fuel engine in the embodiment of the present invention is as follows: Figure 1 ;

[0042] Figure 3 The process of the fuel recovery control method of the ammonia fuel engine in the embodiment of the present invention is as follows: Figure 2 .

[0043] In the figure:

[0044] 1. Liquid ammonia tank; 2. Injector; 3. Supply pipeline; 4. First solenoid valve; 5. Liquid ammonia pump; 6. Second solenoid valve; 7. Common rail pipe; 8. Third solenoid valve; 9. Recovery pipeline; 10. Storage tank; 101. Piston; 102. First chamber; 103. Second chamber; 104. Tension spring; 11. Nitrogen tank; 12. First pressure reducing valve; 13. Input pipeline; 14. Discharge pipeline; 15. Burner; 16. Pressurization pipeline; 17. Second pressure reducing valve; 18. Check valve; 19. Release valve; 20. First one-way valve; 21. Connecting pipeline; 22. Fourth solenoid valve; 23. Filter; 24. Second one-way valve; 25. Overflow pipeline; 26. Overflow valve. DETAILED DESCRIPTION

[0045] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0046] In the description of the present invention, it should be noted that the orientations or positional relationships indicated by the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. Among them, the terms "first position" and "second position" are two different positions, and the first feature "above", "above" and "above" the second feature include the first feature being directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. The first feature "below", "below" and "below" the second feature include the first feature being directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0047] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0048] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0049] like Figure 1 As shown, this embodiment provides an ammonia fuel engine. The ammonia fuel engine includes a liquid ammonia tank 1, an injector 2, a supply pipeline 3, a supply device, a recovery pipeline 9, a storage tank 10 and a purge system.

[0050] The liquid ammonia tank 1 is used to store liquid ammonia. In this embodiment, the pressure of the liquid ammonia stored in the liquid ammonia tank 1 is specifically 20 bar.

[0051] The supply pipeline 3 is connected between the liquid ammonia tank 1 and the injector 2. The supply device includes a first solenoid valve 4, a liquid ammonia pump 5, a second solenoid valve 6, a common rail pipe 7 and a third solenoid valve 8 which are sequentially arranged on the supply pipeline 3 along the conveying direction of the ammonia fuel. The injector 2 is arranged in the combustion chamber of the engine, and the injector 2 is used to inject liquid ammonia. Driven by the liquid ammonia pump 5, the liquid ammonia in the liquid ammonia tank 1 can be conveyed to the common rail pipe 7, stabilized by the common rail pipe 7, and further conveyed to the injector 2 for spraying.

[0052] The recovery line 9 is connected to the second solenoid valve 6, and the storage tank 10 is connected to the recovery line 9. The second solenoid valve 6 is used to connect or disconnect the recovery line 9 with the supply line 3. When the second solenoid valve 6 disconnects the recovery line 9 from the supply line 3, the supply line 3 is used to supply liquid ammonia to the injector 2. After the engine is shut down, the recovery line 9 is connected to the supply line 3 through the second solenoid valve 6. Under the pressure difference between the pressure in the supply line 3 and the pressure in the storage tank 10, the liquid ammonia remaining in the supply line 3 and other components on the supply line 3 can gradually enter the storage tank 10 for storage through the recovery line 9. Among them, when the pressure in the supply line 3 is equal to the pressure in the storage tank 10, the pressure in the supply line 3 drops to 3 bar or less, and when the ammonia fuel engine is just shut down, the pressure in the supply line 3 can be as high as 600 bar.

[0053] The purge system is used to purge the portion of the supply pipeline 3 between the first solenoid valve 4 and the third solenoid valve 8, and the first solenoid valve 4 and the third solenoid valve 8 are used to connect the supply pipeline 3 between the liquid ammonia tank 1 and the injector 2, or to be connected in series with the purge system. When the first solenoid valve 4 and the third solenoid valve 8 are used to connect the supply pipeline 3 between the liquid ammonia tank 1 and the injector 2, the supply pipeline 3 is used to supply liquid ammonia to the injector 2; when the engine is shut down, and the liquid ammonia remaining in the supply pipeline 3 and other components on the supply pipeline 3 is recovered to the storage tank 10 by gradually releasing the pressure, the first solenoid valve 4 and the third solenoid valve 8 connect the supply pipeline 3 in series with the purge system, and at this time, the ammonia fuel remaining in the supply pipeline 3 and other components on the supply pipeline 3 can be discharged from the supply pipeline 3 through the purge system to ensure the safety of the ammonia fuel engine.

[0054] Optionally, the purge system includes a nitrogen tank 11, a first pressure reducing valve 12, an input pipeline 13, an exhaust pipeline 14 and a burner 15. The nitrogen tank 11 is used to store nitrogen, and the nitrogen pressure is 50 bar. The nitrogen tank 11 is connected to the input pipeline 13, the first pressure reducing valve 12 is arranged on the input pipeline 13, the input pipeline 13 is connected to the first solenoid valve 4, the exhaust pipeline 14 is connected to the third solenoid valve 8, the first solenoid valve 4 is used to connect the liquid ammonia pump 5 to either the input pipeline 13 or the liquid ammonia tank 1, and the third solenoid valve 8 is used to connect the common rail pipe 7 to either the injector 2 or the exhaust pipeline 14. Specifically, when the engine is operating normally, the first solenoid valve 4 connects the liquid ammonia pump 5 with the liquid ammonia tank 1, and the third solenoid valve 8 connects the common rail pipe 7 with the injector 2; when purging, the first solenoid valve 4 connects the liquid ammonia pump 5 with the input pipeline 13, and the third solenoid valve 8 connects the common rail pipe 7 with the exhaust pipeline 14. The nitrogen in the nitrogen tank 11 is depressurized by the first pressure reducing valve 12 and then input into the supply pipeline 3, and then the supply pipeline 3 and other components on the supply pipeline 3 are purged. Among them, the pressure of the nitrogen after the first pressure reducing valve 12 is higher than the pressure of the ammonia fuel in the supply pipeline 3, which can be 6 bar for example. The mixed gas of the purged nitrogen and the ammonia fuel is transported to the burner 15, and the ammonia fuel undergoes a combustion reaction in the burner 15 to harmlessly treat the remaining ammonia fuel.

[0055] In other embodiments, the mixed gas of nitrogen and ammonia fuel may also be separated by a separation device, for example, by absorbing ammonia by water spraying to separate nitrogen, and then extracting ammonia by distillation.

[0056] Optionally, a piston 101 is slidably provided in the storage tank 10, and the piston 101 divides the storage tank 10 into a first chamber 102 and a second chamber 103. The first chamber 102 is connected to the recovery line 9, and the second chamber 103 is connected to the high-pressure gas source. When the engine is shut down and the residual ammonia fuel in the supply line 3 is recovered to the storage tank 10, high-pressure gas is introduced into the second chamber 103 through the high-pressure gas source, so that the ammonia fuel in the first chamber 102 can be pressurized and liquefied without external power. Among them, ammonia can be liquefied when the pressure exceeds 10 bar at a constant temperature of 25°C. Specifically, in this embodiment, the high-pressure gas delivered to the second chamber 103 is specifically 25 bar, which can ensure that the ammonia fuel in the first chamber 102 is completely liquefied.

[0057] Preferably, the high-pressure gas can be an inert gas, nitrogen, etc. Specifically, in the present embodiment, the high-pressure gas is nitrogen, and is provided by the nitrogen tank 11. Specifically, the nitrogen tank 11 is also connected to a pressurized pipeline 16, and the pressurized pipeline 16 is connected to the second chamber 103. A second pressure reducing valve 17 is provided on the pressurized pipeline 16, and the pressure of the nitrogen output from the nitrogen tank 11 is reduced to 25 bar by the second pressure reducing valve 17, and then transported to the second chamber 103. Further preferably, a check valve 18 is also provided on the pressurized pipeline 16, and the check valve 18 is close to the storage tank 10 relative to the second pressure reducing valve 17, and the check valve 18 only allows nitrogen to flow from the pressurized pipeline 16 to the second chamber 103, and prevents the nitrogen in the second chamber 103 from flowing back.

[0058] Optionally, the storage tank 10 is also provided with a vent valve 19 connected to the second chamber 103; after the ammonia in the first chamber 102 is liquefied by adding high-pressure gas to the second chamber 103, the vent valve 19 is opened to discharge the nitrogen in the second chamber 103 to the outside atmosphere, which does not affect the next recovery of ammonia fuel by the storage tank 10.

[0059] Optionally, the recovery line 9 is provided with a first one-way valve 20, which is configured to only allow ammonia fuel to flow from the recovery line 9 to the first chamber 102. The first one-way valve 20 is provided to prevent ammonia in the first chamber 102 from flowing back into the supply line 3 again when the first chamber 102 is pressurized.

[0060] Optionally, the first chamber 102 is connected to the liquid ammonia tank 1 through a connecting pipe 21, and a fourth solenoid valve 22, a filter 23 and a second one-way valve 24 are sequentially provided on the connecting pipe 21 along the conveying direction of the ammonia fuel. The fourth solenoid valve 22 is used to connect or disconnect the connecting pipe 21, and the second one-way valve 24 is configured to only allow the ammonia fuel to flow from the filter 23 to the liquid ammonia tank 1. When the ammonia fuel recovered in the first chamber 102 is liquefied, the connecting pipe 21 can be opened by the fourth solenoid valve 22, and the liquid ammonia in the first chamber 102 is filtered by the filter 23 and then transported to the liquid ammonia tank 1 for storage, thereby realizing the recovery of the ammonia fuel. Among them, the second one-way valve 24 can prevent the liquid ammonia in the liquid ammonia tank 1 from flowing back into the first chamber 102.

[0061] Optionally, a tension spring 104 is further provided in the second chamber 103, and the two ends of the tension spring 104 are respectively connected to the piston 101 and the inner wall of the storage tank 10. By providing the tension spring 104, when the liquid ammonia recovered in the first chamber 102 is recovered into the liquid ammonia tank 1, the vent valve 19 can be opened to discharge the nitrogen in the second chamber 103. At this time, under the action of the tension spring 104, the piston 101 compresses the volume of the second chamber 103 and expands the volume of the first chamber 102, so as to facilitate the recovery of ammonia fuel next time.

[0062] Optionally, the ammonia fuel engine further includes an overflow pipeline 25 connecting the common rail pipe 7 and the first chamber 102, and an overflow valve 26 arranged on the overflow pipeline 25. By setting the overflow pipeline 25 and the overflow valve 26, when the engine works normally, under the action of the liquid ammonia pump 5, when the pressure of the liquid ammonia in the common rail pipe 7 exceeds the set overflow pressure of the overflow valve 26, the liquid ammonia will overflow into the first chamber 102 through the overflow pipeline 25 to ensure that the pressure of the liquid ammonia in the common rail pipe 7 does not exceed the set overflow pressure, and at the same time, the liquid ammonia can be recycled.

[0063] In the prior art, when the ammonia fuel engine stops running, the pipeline that supplies ammonia to the engine is purged with nitrogen, and the liquid ammonia, ammonia gas, and nitrogen used for purging are all collected in the liquid ammonia collection tank. By adding nitrogen to the liquid ammonia collection tank again to pressurize it, the ammonia gas in the tank is liquefied, and the liquid ammonia can be recycled again, while ensuring the safety of the ammonia engine. However, when the liquid ammonia in the liquid ammonia collection tank is recycled again, the nitrogen and liquid ammonia need to be separated to prevent nitrogen from entering the supply system, but the separation process is cumbersome and it is difficult to separate all the liquid ammonia, resulting in energy waste; at the same time, the residual ammonia fuel in the pipeline is purged with nitrogen, and the pressure of the nitrogen needs to be higher than the pressure of the ammonia fuel, which places higher requirements on the pressure-bearing capacity of the pipeline.

[0064] In view of this, the present embodiment provides a fuel recovery control method for an ammonia fuel engine to solve the above-mentioned problem. The fuel recovery control method for an ammonia fuel engine is implemented by the above-mentioned ammonia fuel engine.

[0065] For details, please refer to Figure 2 The fuel recovery control method of the ammonia fuel engine comprises the following steps:

[0066] S100: Obtain a shutdown instruction.

[0067] The parking command can be obtained by interacting with the vehicle controller; or by detecting the position of the ignition switch, when the ignition switch is switched from the ignition position to the ignition off position, the shutdown command is determined.

[0068] S110: The ammonia fuel engine is shut down.

[0069] After the ammonia fuel engine is shut down, the liquid ammonia pump 5 will stop supplying liquid ammonia fuel.

[0070] S120: Connect the recovery pipeline 9 and the supply pipeline 3.

[0071] Specifically, the recovery line 9 and the supply line 3 are connected by controlling the second solenoid valve 6 .

[0072] When the recovery pipeline 9 is connected to the supply pipeline 3, under the action of the pressure difference between the supply pipeline 3 and the storage tank 10, the liquid nitrogen remaining in the supply pipeline 3 will be recovered to the storage tank 10, and the pressure in the supply pipeline 3 will gradually decrease.

[0073] S130: Collect the pressure in the supply pipeline 3 in real time and compare it with the first set pressure.

[0074] When the pressure in the supply pipeline 3 does not exceed the first set pressure, S140 is executed; when the pressure in the supply pipeline 3 exceeds the first set pressure, the process returns to step S120.

[0075] Specifically, the pressure in the supply pipeline 3 can be detected by a pressure sensor. In this embodiment, the first set pressure is specifically 3 bar. In other embodiments, the first set pressure can also be set according to actual needs.

[0076] S140: Disconnect the recovery pipeline 9 from the supply pipeline 3.

[0077] When the pressure in the supply pipeline 3 does not exceed the first set pressure, it indicates that the pressures between the supply pipeline 3 and the storage tank 10 are equal or approaching to be equal, so the recovery pipeline 9 and the supply pipeline 3 can be disconnected by controlling the second solenoid valve 6. At this time, most of the liquid nitrogen in the supply pipeline 3 and the common rail pipe 7 on the supply pipeline 3 has been recovered to the storage tank 10. However, there is still some ammonia fuel in the supply pipeline 3 and the common rail pipe 7 on the supply pipeline 3. Since the pressure in the supply pipeline 3 is relatively low at this time, the amount of this part of ammonia fuel is small and in gaseous form.

[0078] S150: The ammonia fuel remaining in the supply pipeline 3 is purged through the purging system.

[0079] The ammonia fuel in the supply pipeline 3 and other components on the supply pipeline 3 after recovery is removed by purging to ensure that no ammonia fuel remains, thereby ensuring the safety of the ammonia fuel engine.

[0080] The fuel recovery control method for an ammonia fuel engine provided in the present embodiment, when the ammonia fuel engine is shut down, collects the pressure in the supply pipeline 3 in real time and compares it with the first set pressure. When the pressure in the supply pipeline 3 does not exceed the first set pressure, the recovery pipeline 9 is disconnected from the supply pipeline 3, so that most of the ammonia fuel in the supply pipeline 3 can be recovered to the storage tank 10 by natural pressure relief. Compared with the prior art, there is no need for direct nitrogen purging, which can reduce the pressure requirements of the supply pipeline 3 and the components on the supply pipeline 3. Moreover, the recovered ammonia fuel is not mixed with nitrogen, and there is no need for separation operation. The process is simple. After recovery, the very small amount of ammonia fuel remaining in the supply pipeline 3 and other components thereon is discharged by purging, thereby ensuring the safety of the ammonia fuel engine.

[0081] Please refer to Figure 3 Optionally, the fuel recovery control method of the ammonia fuel engine further includes the following steps between S140 and S150:

[0082] S141: Pressurize the ammonia fuel in the storage tank 10 and liquefy the ammonia fuel.

[0083] In this embodiment, step S141 includes the following steps:

[0084] The high-pressure gas source is continuously used to fill the second chamber 103 with high-pressure gas; and when the pressure in the first chamber 102 reaches the second set pressure, the high-pressure gas source is stopped from filling the second chamber 103 with high-pressure gas.

[0085] The pressure of the high-pressure gas is not less than 10 bar, and the second set pressure is greater than the first set pressure. Specifically, the high-pressure nitrogen is output through the nitrogen tank 11, and after the pressure is adjusted by the second pressure reducing valve 17, the 25 bar nitrogen is input into the second chamber 103 of the storage tank 10, and the high pressure of the nitrogen drives the piston 101 to compress the ammonia in the first chamber 102, so that the ammonia is liquefied, and the pressure of the liquefied ammonia is 25 bar, that is, the second set pressure is 25 bar, which is greater than the pressure of the liquid ammonia in the liquid ammonia tank 1, so that the liquefied ammonia is transported to the liquid ammonia tank 1 under the action of the pressure difference between the second chamber 103 and the liquid ammonia tank 1.

[0086] S142: The liquefied ammonia fuel in the storage tank 10 is transported to the liquid ammonia tank 1.

[0087] Specifically, by opening the fourth solenoid valve 22, the liquefied ammonia fuel in the storage tank 10 will be transported to the liquid ammonia tank 1. It should be noted that during this process, the pressure in the second chamber 103 is kept constant so that all the liquid ammonia in the second chamber 103 can be transported to the liquid ammonia tank 1.

[0088] S143: Open the vent valve 19 to discharge the high-pressure gas in the second chamber 103 to the outside atmosphere, and when the gas pressure in the second chamber 103 is equal to the first set pressure, close the vent valve 19.

[0089] Through step S143, the piston 101 can be moved to the top of the storage tank 10 under the drive of the tension spring 104, so as to recover the liquid ammonia in the supply pipeline 3 when the machine is shut down next time.

[0090] Optionally, step S150 includes the following steps:

[0091] S1501: connect the input pipeline 13 to the end of the supply pipeline 3 close to the liquid ammonia tank 1, and connect the discharge pipeline 14 to the end of the supply pipeline 3 away from the liquid ammonia tank 1.

[0092] Specifically, the first solenoid valve 4 is controlled so that the input pipeline 13 is connected to the end of the supply pipeline 3 close to the liquid ammonia tank 1; the third solenoid valve 8 is controlled so that the discharge pipeline 14 is connected to the end of the supply pipeline 3 away from the liquid ammonia tank 1. At this time, the supply pipeline 3 is connected in series between the input pipeline 13 and the discharge pipeline 14.

[0093] S1502 : The nitrogen tank 11 is made to output nitrogen at a third set pressure for a set time, and the discharge pipeline 14 delivers a mixture of nitrogen and ammonia fuel to the burner 15 , where the ammonia fuel in the mixture undergoes a combustion reaction.

[0094] In this embodiment, the third set pressure is exemplarily given as 6 bar.

[0095] Specifically, in this embodiment, 50 bar high-pressure nitrogen is output through the nitrogen tank 11 and the pressure of the high-pressure nitrogen is adjusted to 6 bar through the first pressure reducing valve 12. 6 bar nitrogen can also be directly stored through the nitrogen tank 11 and 6 bar nitrogen can be directly output.

[0096] Through step S1502, the very small amount of ammonia fuel remaining in the supply pipeline 3 is purged to the burner 15 through nitrogen and participates in the combustion reaction in the burner 15. After the set time, it can be ensured that there is no ammonia fuel remaining in the supply pipeline 3 and other components on the supply pipeline 3, thereby ensuring safety. In this embodiment, the set time is specifically 1 minute, and in other embodiments, it can also be set as needed.

[0097] S1503: disconnect the input pipeline 13 from the end of the supply pipeline 3 close to the liquid ammonia tank 1 , and disconnect the discharge pipeline 14 from the end of the supply pipeline 3 away from the liquid ammonia tank 1 .

[0098] Specifically, the first solenoid valve 4 is controlled to disconnect the input pipeline 13 from the end of the supply pipeline 3 close to the liquid ammonia tank 1; the third solenoid valve 8 is controlled to disconnect the discharge pipeline 14 from the end of the supply pipeline 3 away from the liquid ammonia tank 1. At this time, the supply pipeline 3 is connected in series between the liquid ammonia tank 1 and the injector 2 to facilitate the next start-up.

[0099] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A fuel recovery control method for an ammonia fuel engine, characterized in that: An ammonia fuel engine comprises a liquid ammonia tank (1) for storing liquid ammonia, an injector (2) for injecting liquid ammonia, a supply pipeline (3) connected between the liquid ammonia tank (1) and the injector (2), a supply device arranged on the supply pipeline (3), a recovery pipeline (9) selectively connected to the supply pipeline (3), a storage tank (10) connected to the recovery pipeline (9), and a purge system for purging the supply pipeline (3), wherein the supply device is capable of driving the liquid ammonia in the liquid ammonia tank (1) to enter the injector (2) through the supply pipeline (3). The fuel recovery control method of the ammonia fuel engine comprises: Get shutdown instructions; Ammonia fuel engine shutdown; Connecting the recovery pipeline (9) to the supply pipeline (3); collecting the pressure in the supply pipeline (3) in real time and comparing it with a first set pressure; When the pressure in the supply pipeline (3) does not exceed the first set pressure, disconnecting the recovery pipeline (9) from the supply pipeline (3); The ammonia fuel remaining in the supply pipeline (3) is purged by a purging system.

2. The fuel recovery control method for an ammonia fuel engine according to claim 1, characterized in that: The fuel recovery control method for an ammonia fuel engine further includes, between the step of disconnecting the recovery pipeline (9) from the supply pipeline (3) and the step of purging the ammonia fuel remaining in the supply pipeline (3) by a purging system: Pressurizing the ammonia fuel in the storage tank (10) and liquefying the ammonia fuel; The liquefied ammonia fuel in the storage tank (10) is transported to the liquid ammonia tank (1).

3. The fuel recovery control method for an ammonia fuel engine according to claim 2, characterized in that: A piston (101) is slidably disposed in the storage tank (10), and the piston (101) divides the storage tank (10) into a first chamber (102) and a second chamber (103), the first chamber (102) being in communication with the recovery pipeline (9), and the second chamber (103) being connected to a high-pressure gas source; Pressurizing the ammonia fuel in the storage tank (10) and liquefying the ammonia fuel comprises: The high-pressure gas source is continuously used to fill the second chamber (103) with high-pressure gas, and when the pressure in the first chamber (102) reaches a second set pressure, the high-pressure gas source is stopped from filling the second chamber (103) with high-pressure gas; the pressure of the high-pressure gas is not less than 10 bar, and the second set pressure is greater than the first set pressure.

4. The fuel recovery control method for an ammonia fuel engine according to claim 3, characterized in that: The storage tank (10) is further provided with a purge valve (19) in communication with the second chamber (103). The fuel recovery control method for the ammonia fuel engine further comprises, after the step of transporting the liquefied ammonia fuel to the liquid ammonia tank (1): The air release valve (19) is opened to discharge the high-pressure gas in the second chamber (103) to the outside atmosphere, and when the gas pressure in the second chamber (103) is equal to the first set pressure, the air release valve (19) is closed.

5. The fuel recovery control method for an ammonia fuel engine according to any one of claims 1 to 4, characterized in that: The purge system comprises a nitrogen tank (11), an input pipeline (13), a discharge pipeline (14) and a burner (15); the nitrogen tank (11) is used to store nitrogen; the nitrogen tank (11) is connected to the input pipeline (13); the input pipeline (13) is selectively connected to an end of the supply pipeline (3) close to the liquid ammonia tank (1); the discharge pipeline (14) is selectively connected to an end of the supply pipeline (3) away from the liquid ammonia tank (1); and the discharge pipeline (14) is connected to the burner (15); Purging the ammonia fuel remaining in the supply pipeline (3) by means of a purge system comprises: The input pipeline (13) is connected to an end of the supply pipeline (3) close to the liquid ammonia tank (1), and the discharge pipeline (14) is connected to an end of the supply pipeline (3) away from the liquid ammonia tank (1), and the supply pipeline (3) is connected in series between the input pipeline (13) and the discharge pipeline (14); The nitrogen tank (11) outputs nitrogen at a third set pressure for a set time, and the discharge pipeline (14) delivers a mixture of nitrogen and ammonia fuel to the burner (15), and the ammonia fuel in the mixture undergoes a combustion reaction in the burner (15), and the third set pressure is greater than the first set pressure; The input pipeline (13) is disconnected from the end of the supply pipeline (3) close to the liquid ammonia tank (1), and the discharge pipeline (14) is disconnected from the end of the supply pipeline (3) away from the liquid ammonia tank (1).

6. An ammonia fuel engine, characterized in that: A fuel recovery control method for an ammonia fuel engine according to claim 1 or 2, wherein the ammonia fuel engine comprises: A liquid ammonia tank (1), used for storing liquid ammonia; An injector (2) for injecting liquid ammonia; A supply pipeline (3) connected between the liquid ammonia tank (1) and the injector (2); The supply device comprises a first solenoid valve (4), a liquid ammonia pump (5), a second solenoid valve (6), a common rail pipe (7) and a third solenoid valve (8) which are sequentially arranged on the supply pipeline (3) along the conveying direction of the ammonia fuel; A recovery pipeline (9) connected to the second solenoid valve (6), the second solenoid valve (6) being used to connect or disconnect the recovery pipeline (9) with the supply pipeline (3); A storage tank (10) connected to the recovery pipeline (9); A purge system is used for purging a portion of the supply pipeline (3) between the first solenoid valve (4) and the third solenoid valve (8), and the first solenoid valve (4) and the third solenoid valve (8) are used to connect the supply pipeline (3) between the liquid ammonia tank (1) and the injector (2), or to be connected in series with the purge system.

7. The ammonia fuel engine according to claim 6, characterized in that: A piston (101) is slidably disposed in the storage tank (10), and the piston (101) divides the storage tank (10) into a first chamber (102) and a second chamber (103), the first chamber (102) being in communication with the recovery pipeline (9), and the second chamber (103) being connected to a high-pressure gas source.

8. The ammonia fuel engine according to claim 7, characterized in that: The storage tank (10) is further provided with a purge valve (19) in communication with the second chamber (103); and / or the recovery pipeline (9) is provided with a first one-way valve (20), wherein the first one-way valve (20) is configured to only allow the ammonia fuel to flow from the recovery pipeline (9) to the first chamber (102).

9. The ammonia fuel engine according to claim 7, characterized in that: A tension spring (104) is further provided in the second chamber (103), and two ends of the tension spring (104) are respectively connected to the piston (101) and the inner wall of the storage tank (10); and / or, The first chamber (102) is connected to the liquid ammonia tank (1) via a connecting pipeline (21); a fourth solenoid valve (22), a filter (23) and a second one-way valve (24) are sequentially arranged on the connecting pipeline (21) along the conveying direction of the ammonia fuel; the fourth solenoid valve (22) is used to connect or disconnect the connecting pipeline (21); the second one-way valve (24) is configured to only allow the ammonia fuel to flow from the filter (23) to the liquid ammonia tank (1).

10. The ammonia fuel engine according to claim 6, characterized in that: The purge system comprises a nitrogen tank (11), a first pressure reducing valve (12), an input pipeline (13), a discharge pipeline (14) and a burner (15); the nitrogen tank (11) is used to store nitrogen; the nitrogen tank (11) is connected to the input pipeline (13); the first pressure reducing valve (12) is arranged on the input pipeline (13); the input pipeline (13) is connected to the first solenoid valve (4); the discharge pipeline (14) is connected to the third solenoid valve (8); the first solenoid valve (4) is used to connect the liquid ammonia pump (5) to either the input pipeline (13) or the liquid ammonia tank (1); the third solenoid valve (8) is used to connect the common rail pipe (7) to either the injector (2) or the discharge pipeline (14).

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