Marine liquid ammonia fuel supply system with ammonia ejector cooling function

Abstract

A marine liquid ammonia fuel supply system with an ammonia injector cooling function is provided with a dual-fuel main engine capable of using liquid ammonia or diesel oil as fuel, the ammonia injector is mounted at the top of a cylinder in the dual-fuel main engine, a heat exchange coil is wound outside the ammonia injector, a low-pressure fuel pump and a high-pressure fuel pump supply the liquid ammonia to the dual-fuel main engine, and the high-pressure fuel pump supplies the high-pressure fuel pump to the dual-fuel main engine. The liquid ammonia fuel enters the main machine, and after the ammonia fuel mode operation is finished, the liquid ammonia fuel is purged and refluxed, so that the liquid ammonia fuel can be recycled, the ammonia gas can be absorbed, and the residual nitrogen is discharged into the atmosphere. By slightly improving the existing liquid ammonia supply system, the function of cooling the ammonia injector in the main engine ammonia fuel mode can be realized, and the cost and the space are greatly saved. The liquid ammonia fuel replaces fresh water to cool the ammonia ejector, and due to the fact that the temperature of liquid ammonia is lower and the specific heat capacity is larger than that of water, the cooling effect is better.

Description

Technical Field

[0001] The invention belongs to the technical field of liquid ammonia fuel supply systems, and in particular relates to a marine liquid ammonia fuel supply system with an ammonia injector cooling function. Background Art

[0002] The shipping industry has a growing demand for green and environmentally friendly ships. It is urgent to carry out the research and development of innovative technologies and the introduction of alternative fuels and other emission reduction measures in the shipping industry. Using low-carbon or even zero-carbon fuels to replace traditional marine fuels is an important measure for the shipping industry to reduce emissions. Among many new fuels, ammonia, as one of the potential zero-carbon fuels, can be stored on board at a temperature of minus 33°C, has an acceptable energy density, does not produce carbides and sulfides when burned, is easy to store and transport, has sufficient production capacity and low prices, and has become the focus of industry research.

[0003] At present, the diesel / liquid ammonia dual-fuel main engine that can be used in large ships and uses ammonia fuel is still in the development process. During the prototype test, it was found that when this type of main engine is running in ammonia fuel mode, the ammonia injector that injects ammonia fuel into the cylinder will continue to rise in temperature due to contact with high-temperature and high-pressure servo oil and liquid ammonia fuel, and is close to the combustion chamber. The temperature will eventually exceed the material's bearing capacity, so corresponding cooling measures need to be taken for the ammonia injector. According to the traditional method, a separate fresh water cooling system is configured for it, which can solve the problem of cooling the ammonia injector. However, since the cooling power required by the ammonia injector is not large, a separate cooling system including a pressure water tank, a delivery pump, pipelines, corresponding valves, instruments, control systems, etc. is configured, which not only increases more costs and occupies a larger space, but also increases the complexity and failure rate of the system configuration. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a marine liquid ammonia fuel supply system with an ammonia injector cooling function, aiming to achieve the purpose of cooling the ammonia injector when the main engine is running in the ammonia fuel mode without the need for a separate fresh water cooling system. The technical solution adopted is: The invention discloses a marine liquid ammonia fuel supply system with an ammonia injector cooling function. An ammonia injector is installed on the top of a cylinder inside a dual-fuel main engine, and a heat exchange coil is wound around the outside of the ammonia injector.

[0005] When the dual-fuel main engine operates in ammonia fuel mode, a low-pressure fuel pump is used to transport liquid ammonia to the buffer tank, and the liquid ammonia is heated and pressurized by the heater and high-pressure fuel pump. The heated and pressurized liquid ammonia passes through a duplex filter to filter out large particles of impurities, and is then supplied to the dual-fuel main engine through the fuel valve group unit and the double-walled supply pipe.

[0006] The supply double-wall pipe is connected to the ammonia injector. A second remote control valve is arranged on the passage from the supply double-wall pipe to the ammonia injector. A cooling branch pipe is extended from the passage from the supply double-wall pipe to the ammonia injector. A third remote control valve is arranged on the cooling branch pipe. Most of the liquid ammonia is sprayed into the cylinder through the ammonia injector to burn and do work, and a small part of the liquid ammonia enters the cooling branch pipe of the ammonia injector. When passing through the heat exchange coil, the liquid ammonia exchanges heat with the ammonia injector. After cooling the ammonia injector, the heated liquid ammonia returns to the buffer tank through the reflux double-wall pipe.

[0007] After the ammonia fuel mode is completed, nitrogen is used to purge the fuel supply pipeline and the inside of the dual-fuel main engine. The gas-liquid mixture is purged through the reflux double-walled pipe to the ammonia processing unit for gas-liquid separation. The separated liquid ammonia returns to the buffer tank through the first remote control valve, and the separated gas is introduced into the ammonia absorption device.

[0008] The above-mentioned marine liquid ammonia fuel supply system with ammonia injector cooling function, further, the liquid ammonia fuel tank is provided with a low-pressure fuel pump, the low-pressure fuel pump is connected to the buffer tank, the heater, the high-pressure fuel pump, the duplex filter, and the fuel valve group unit in sequence through pipelines, the fuel valve group unit is connected to the ammonia injector through the supply double-walled pipe, the ammonia injector is installed on the top of the cylinder, and is used to spray liquid ammonia fuel into the cylinder.

[0009] The dual-fuel main engine is connected with the fuel valve group unit, the ammonia treatment unit, the ammonia absorption device and the air mast in sequence through the reflux double-wall pipe.

[0010] The nitrogen supply unit is connected to the fuel valve group unit to provide nitrogen for purge for the liquid ammonia fuel supply system and the dual-fuel main engine.

[0011] The fuel valve group unit is connected to the ammonia processing unit and the buffer tank through pipelines respectively. A fourth remote control valve is provided on the passage from the fuel valve group unit to the ammonia processing unit, and a fifth remote control valve is provided on the passage from the fuel valve group unit to the buffer tank.

[0012] When the main engine is running in the ammonia fuel mode, a part of the liquid ammonia fuel is used as the cooling medium of the ammonia injector, thereby achieving the purpose of utilizing the existing liquid ammonia fuel supply system as an ammonia injector cooling system after improvement.

[0013] The above-mentioned marine liquid ammonia fuel supply system with ammonia injector cooling function further comprises a heater and a high-pressure fuel pump that heat the liquid ammonia to 40° C. and pressurizes it to 85 bar.

[0014] The above-mentioned marine liquid ammonia fuel supply system with an ammonia injector cooling function further absorbs ammonia by dissolving in water in the ammonia absorption device.

[0015] The above-mentioned marine liquid ammonia fuel supply system with ammonia injector cooling function, further, has a bypass pipeline extending from the outlet of the high-pressure fuel pump to be connected to the buffer tank, and a regulating valve is provided on the pipeline, and excess fuel can flow back to the buffer tank to adjust the amount of fuel supplied to the dual-fuel main engine.

[0016] The above-mentioned marine liquid ammonia fuel supply system with ammonia injector cooling function further adopts water glycol as an intermediate medium and steam as a heat source in the liquid ammonia heater.

[0017] The above-mentioned marine liquid ammonia fuel supply system with ammonia injector cooling function further has an absolute mesh accuracy of 10 μm for the duplex filter.

[0018] The above-mentioned marine liquid ammonia fuel supply system with ammonia injector cooling function further has a cooling branch pipeline arranged on the liquid ammonia supply pipeline inside the dual-fuel main engine, and a small portion of liquid ammonia passes through the heat exchange coil of the pipeline to realize the cooling function of the ammonia injector.

[0019] The beneficial effects of the present invention are: 1. The present invention utilizes the existing liquid ammonia supply system with a slight improvement to realize the cooling function of the ammonia injector in the main engine ammonia fuel mode, which greatly saves cost and space.

[0020] 2. The present invention uses liquid ammonia fuel instead of fresh water to cool the ammonia injector. Since liquid ammonia has a lower temperature and a larger specific heat capacity than water, the cooling effect is better.

[0021] 3. The present invention returns the liquid ammonia with increased temperature after cooling the ammonia injector to the liquid ammonia supply system, which is equivalent to preheating the liquid ammonia fuel by using the excess heat of the ammonia injector, greatly saving energy and improving the energy efficiency of the ship.

[0022] 4. The present invention has simple and effective configuration, reliable operation and low failure rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the system of the present invention; Among them: 1-liquid ammonia fuel tank, 2-low-pressure fuel pump, 3-buffer tank, 4-heater, 5-high-pressure fuel pump, 6-regulating valve, 7-dual filter, 8-fuel valve group unit, 9-supply double-wall pipe, 10-dual-fuel main engine, 11-ammonia injector, 12-cylinder, 13-nitrogen supply unit, 14-reflux double-wall pipe, 15-ammonia treatment unit, 16-first remote control valve, 17-ammonia absorption device, 18-ventilation mast, 19-second remote control valve, 20-third remote control valve, 21-heat exchange coil, 22-fourth remote control valve, 23-fifth remote control valve. DETAILED DESCRIPTION

[0024] The present invention will be further described in conjunction with the accompanying drawings.

[0025] like Figure 1 The shown is a marine liquid ammonia fuel supply system with cooling function of ammonia injector 11. Liquid ammonia fuel tank 1 is used to store low-temperature liquid ammonia fuel of about -33°C. When dual-fuel main engine 10 operates in ammonia fuel mode, low-pressure fuel pump 2 is used to first deliver liquid ammonia to buffer tank 3, and then through heater 4, high-pressure fuel pump 5 heats and pressurizes liquid ammonia to reach the temperature and pressure required by the main engine for liquid ammonia fuel. Heater 4 uses water glycol as an intermediate heat exchange medium to heat liquid ammonia, and steam is used as a heat source. Since the load of the main engine is changing, the required fuel consumption is also constantly changing, so a regulating valve 6 and its pipeline are set. When the load of the main engine is small, a part of the liquid ammonia fuel can be automatically refluxed to buffer tank 3 through regulating valve 6. The heated and pressurized liquid ammonia passes through duplex filter 7 to filter out larger particle impurities and protect the stable operation of the main engine. After that, the fuel passes through fuel valve group unit 8, and comes out of fuel valve group unit 8 and is supplied to dual-fuel main engine 10 through supply double-wall pipe 9. The double-walled supply pipe 9 is connected to the ammonia injector 11, and a heat exchange coil 21 is wound around the outside of the ammonia injector 11. A second remote control valve 19 is provided on the passage from the double-walled supply pipe 9 to the ammonia injector 11. A cooling branch pipe is extended from the passage from the double-walled supply pipe 9 to the ammonia injector 11, and a third remote control valve 20 is provided on the cooling branch pipe. Most of the liquid ammonia is sprayed into the cylinder 12 through the ammonia injector 11 to burn and do work, and a small part of about 20% of the liquid ammonia enters the cooling branch pipe of the ammonia injector 11. When passing through the heat exchange coil 21, the liquid ammonia exchanges heat with the ammonia injector 11. After cooling the ammonia injector 11, the heated liquid ammonia returns to the buffer tank 3 through the reflux double-walled pipe 14, and will be reused as fuel. It is equivalent to preheating in advance using the excess heat of the ammonia injector 11, thereby improving energy utilization. When the main engine is running in the ammonia fuel mode, a part of the liquid ammonia fuel is used as the cooling medium of the ammonia injector 11, thereby realizing the use of the existing liquid ammonia fuel supply system as a cooling system for the ammonia injector 11 after improvement.

[0026] Liquid ammonia is injected into the cylinder 12 through the ammonia injector 11 to burn and do work. The annular space of the supply double-walled pipe 9 and the return double-walled pipe 14 is provided with a ventilation and leakage monitoring system to ensure that even if ammonia leakage occurs, it will not endanger the safe area such as the cabin.

[0027] After the main engine ammonia fuel mode operation is completed, the nitrogen supply unit 13 connected to the fuel valve group unit 8 provides nitrogen for purging, and the fuel supply pipeline and the inside of the main engine are purged. The liquid ammonia is purged to the ammonia treatment unit 15 through the reflux double-walled pipe 14, in which the purged gas-liquid mixture is separated into gas and liquid, and the liquid ammonia will return to the buffer tank 3 through the first remote control valve 16 to be reused, and the gas will be introduced into the ammonia absorption device 17, in which the ammonia is absorbed by water dissolution, and the remaining gas that contains almost no ammonia is discharged into the atmosphere through the ventilation mast 18.

[0028] After the operation of the ammonia fuel mode is completed, the liquid ammonia fuel can be purged and refluxed to achieve the recycling of the liquid ammonia fuel, and the absorption of ammonia can also be achieved, and the remaining nitrogen can be discharged into the atmosphere. The fuel valve group unit 8 is connected to the ammonia treatment unit 15 and the buffer tank 3 through pipelines, and a fourth remote control valve 22 is provided on the passage from the fuel valve group unit 8 to the ammonia treatment unit 15, and a fifth remote control valve 23 is provided on the passage from the fuel valve group unit 8 to the buffer tank 3. At this time, the first remote control valve 16 and the fifth remote control valve 23 are closed, and the second remote control valve 19, the third remote control valve 20, and the fourth remote control valve 22 are opened to perform nitrogen purging, liquid ammonia recovery, and gas discharge.

[0029] The present invention utilizes the cold energy of the liquid ammonia supply system and the low-temperature liquid ammonia fuel that must be matched with the dual-fuel main engine 10. After a slight improvement, the main engine can realize the cooling function of the ammonia injector 11 in the ammonia fuel mode. Compared with the traditional technical solution of separately configuring a set of fresh water cooling system, it has the advantages of low cost, small additional space occupation, simple system configuration, good cooling effect, energy saving, reliable operation, etc.

Claims

1. A marine liquid ammonia fuel supply system with an ammonia injector cooling function, characterized in that: An ammonia injector (11) is installed on the top of a cylinder (12) inside a dual-fuel main engine (10), and a heat exchange coil (21) is wound around the outside of the ammonia injector (11); When the dual-fuel main engine (10) operates in an ammonia fuel mode, a low-pressure fuel pump (2) is used to transport liquid ammonia to a buffer tank (3), and the liquid ammonia is heated and pressurized via a heater (4) and a high-pressure fuel pump (5). The heated and pressurized liquid ammonia passes through a double filter (7) to filter out large particles of impurities, and then is supplied to the dual-fuel main engine (10) via a fuel valve group unit (8) and a supply double-wall pipe (9) in sequence; The supply double-walled pipe (9) is connected to the ammonia injector (11), and a second remote control valve (19) is provided on the passage from the supply double-walled pipe (9) to the ammonia injector (11). A cooling branch pipe is extended from the passage from the supply double-walled pipe (9) to the ammonia injector (11), and a third remote control valve (20) is provided on the cooling branch pipe. Most of the liquid ammonia is sprayed into the cylinder (12) through the ammonia injector (11) to burn and do work, and a small part of the liquid ammonia enters the cooling branch pipe of the ammonia injector (11). When passing through the heat exchange coil (21), the liquid ammonia exchanges heat with the ammonia injector (11). After cooling the ammonia injector (11), the heated liquid ammonia returns to the buffer tank (3) through the reflux double-walled pipe (14); After the ammonia fuel mode is completed, nitrogen is used to purge the fuel supply pipeline and the interior of the dual-fuel main engine (10), and the gas-liquid mixture is purged through the reflux double-walled pipe (14) to the ammonia processing unit (15) for gas-liquid separation. The separated liquid ammonia returns to the buffer tank (3) through the first remote control valve (16), and the separated gas is introduced into the ammonia absorption device (17).

2. A marine liquid ammonia fuel supply system with ammonia injector cooling function according to claim 1, characterized in that: The liquid ammonia fuel tank (1) is provided with a low-pressure fuel pump (2). The low-pressure fuel pump (2) is connected to a buffer tank (3), a heater (4), a high-pressure fuel pump (5), a duplex filter (7), and a fuel valve group unit (8) in sequence through pipelines. The fuel valve group unit (8) is connected to an ammonia injector (11) through a supply double-walled pipe (9). The ammonia injector (11) is installed on the top of a cylinder (12) and is used to inject liquid ammonia fuel into the cylinder (12). The dual-fuel main engine (10) is connected to the fuel valve group unit (8), the ammonia processing unit (15), the ammonia absorption device (17), and the air mast (18) in sequence through a reflux double-walled pipe (14); The nitrogen supply unit (13) is connected to the fuel valve group unit (8) to provide nitrogen for purge to the liquid ammonia fuel supply system and the dual-fuel main engine (10); The fuel valve group unit (8) is connected to the ammonia processing unit (15) and the buffer tank (3) through pipelines, respectively; a fourth remote control valve (22) is provided on the passage from the fuel valve group unit (8) to the ammonia processing unit (15); and a fifth remote control valve (23) is provided on the passage from the fuel valve group unit (8) to the buffer tank (3).

3. A marine liquid ammonia fuel supply system with ammonia injector cooling function according to claim 1, characterized in that: The heater (4) and the high-pressure fuel pump (5) heat the liquid ammonia to 40°C and pressurize it to 85 bar.

4. A marine liquid ammonia fuel supply system with ammonia injector cooling function according to claim 1, characterized in that: Ammonia is absorbed by dissolving in water in the ammonia absorption device (17).

5. The marine liquid ammonia fuel supply system with ammonia injector cooling function according to claim 2, characterized in that: A bypass pipeline extends from the outlet of the high-pressure fuel pump (5) and is connected to the buffer tank (3). A regulating valve (6) is provided on the pipeline so that excess fuel can flow back to the buffer tank (3) to adjust the amount of fuel supplied to the dual-fuel main engine (10).

6. The marine liquid ammonia fuel supply system with ammonia injector cooling function according to claim 1, characterized in that: The liquid ammonia heater (4) uses water glycol as the intermediate medium and steam as the heat source.

7. The marine liquid ammonia fuel supply system with ammonia injector cooling function according to claim 1, characterized in that: The absolute mesh accuracy of the duplex filter is 10μm.

8. The marine liquid ammonia fuel supply system with ammonia injector cooling function according to claim 1, characterized in that: A cooling branch pipeline is arranged on the liquid ammonia supply pipeline inside the dual-fuel main engine (10), and a small portion of the liquid ammonia passes through the heat exchange coil (21) of the pipeline to achieve a cooling function for the ammonia injector (11).

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