Marine liquid ammonia fuel supply system with diesel nozzle cooling function

Abstract

A marine liquid ammonia fuel supply system with a diesel nozzle cooling function utilizes a liquid ammonia supply system matched with a dual-fuel main engine and cold energy of low-temperature liquid ammonia fuel, a cylinder in the dual-fuel main engine is provided with an ammonia fuel nozzle and a diesel nozzle, a heat exchange coil pipe is wound outside the diesel nozzle, and the heat exchange coil pipe is wound outside the diesel nozzle. Liquid ammonia is injected into a cylinder through an ammonia fuel nozzle to combust and do work, after an ammonia fuel mode of the dual-fuel main engine is finished, nitrogen is utilized to purge a fuel supply pipeline and the interior of the dual-fuel main engine, a gas-liquid mixture is purged to an ammonia gas treatment unit through a backflow double-wall pipe to be subjected to gas-liquid separation, separated liquid ammonia returns to a buffer tank, and the ammonia fuel mode of the dual-fuel main engine is finished. And the separated gas is guided into the ammonia gas absorption device through the receiving tank. The cooling function of the main engine on the nozzle in the diesel oil mode can be achieved, and compared with a traditional technical scheme that a fresh water cooling system is independently arranged, the cooling system has the advantages of being low in cost, small in extra occupied space, simple in system configuration, good in cooling effect, capable of saving energy, reliable in operation and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of ship liquid ammonia fuel supply systems, and in particular relates to a ship liquid ammonia fuel supply system with a diesel nozzle 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 diesel mode, the temperature of its diesel nozzle will continue to rise, exceeding the bearing capacity of the material, so corresponding cooling measures need to be taken for the nozzle. According to the traditional method, a separate fresh water cooling system is configured for it, which can solve the problem of nozzle cooling. However, since the cooling power required for the nozzle 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 costs and occupies a large space, but also increases the complexity and failure rate of 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 diesel nozzle cooling function, aiming to achieve the purpose of nozzle cooling of the main engine in diesel mode. The technical solution adopted is: A marine liquid ammonia fuel supply system with a diesel nozzle cooling function. The cylinder inside the dual-fuel main engine is provided with an ammonia fuel nozzle and a diesel nozzle, and a heat exchange coil is wound around the diesel nozzle.

[0005] The ammonia fuel system is connected to the inlet of the heat exchange coil through the supply double-walled pipe, and the outlet of the heat exchange coil is connected to the reflux double-walled pipe. A second remote control valve is provided on the passage from the supply double-walled pipe to the ammonia fuel nozzle, and a third remote control valve is provided on the passage to the heat exchange coil. Liquid ammonia exchanges heat with the diesel nozzle through the heat exchange coil and returns to the fuel valve group unit in the ammonia fuel system after heat exchange.

[0006] The ammonia fuel system includes a liquid ammonia fuel tank, in which a low-pressure fuel pump is installed. The low-pressure fuel pump is connected to the buffer tank, heater, high-pressure fuel pump, duplex filter, and fuel valve group unit in sequence through pipelines. The fuel valve group unit is connected to the ammonia fuel nozzle and diesel nozzle through the supply double-wall pipe, and the ammonia fuel nozzle and diesel nozzle are connected to the cylinder to spray the fuel into the cylinder.

[0007] The dual-fuel main engine is connected with the fuel valve group unit, the liquid ammonia cooler, the receiving tank, the ammonia treatment unit, the ammonia absorption device and the air mast in sequence through the reflux double-wall pipe.

[0008] The nitrogen supply unit is connected to the fuel valve group unit to provide nitrogen for purge to the liquid ammonia fuel supply system and the main engine.

[0009] When the dual-fuel main engine is running 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 through the heater and high-pressure fuel pump. The heated and pressurized liquid ammonia passes through the double filter to filter out large particles of impurities, and then is supplied to the dual-fuel main engine through the fuel valve group unit and the supply double-wall pipe in sequence. A double filter is provided before the liquid ammonia fuel enters the main engine to ensure that the fuel entering the engine does not contain large particles of impurities, and when one filter is blocked, it will not affect the operation of the entire supply system.

[0010] A variable frequency low-pressure fuel pump and high-pressure fuel pump are configured to supply liquid ammonia to the dual-fuel main engine. The frequency varies with the main engine load. In diesel mode, liquid ammonia for diesel nozzle cooling is delivered at a low frequency.

[0011] The double-walled supply pipe is connected to the ammonia fuel nozzle and the diesel nozzle respectively. A second remote control valve is provided on the passage from the double-walled supply pipe to the ammonia fuel nozzle, and a third remote control valve is provided on the passage to the diesel nozzle. Liquid ammonia is sprayed into the cylinder through the ammonia fuel nozzle to burn and do work.

[0012] After the ammonia fuel mode of the dual-fuel main engine is completed, nitrogen is used to purge the fuel supply pipeline and the interior of the dual-fuel main engine. The gas-liquid mixture is purged to the ammonia processing unit through the reflux double-walled pipe 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 through the receiving tank. The nitrogen supply system is connected to the fuel valve group unit to use nitrogen to achieve the purge operation of the supply pipeline and the main engine. After the ammonia fuel mode is completed, the liquid ammonia fuel can be recycled by purging and refluxing it.

[0013] When the main engine is running in diesel mode, low-temperature liquid ammonia fuel is used as the cooling medium of the nozzle, and the liquid ammonia fuel supply system is improved as the cooling liquid ammonia cooling system of the diesel nozzle. By setting a liquid ammonia receiving tank or liquid ammonia cooler that is heated after cooling, the diesel nozzle can be cooled for a certain period of time or for a long time.

[0014] The above-mentioned marine liquid ammonia fuel supply system with diesel nozzle cooling function further comprises a heater and a high-pressure fuel pump which heat the liquid ammonia to 40° C. and pressurizes it to 85 bar.

[0015] The above-mentioned marine liquid ammonia fuel supply system with diesel nozzle cooling function further absorbs ammonia by dissolving in water in the ammonia absorption device.

[0016] The above-mentioned marine liquid ammonia fuel supply system with diesel nozzle 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 main engine.

[0017] The above-mentioned marine liquid ammonia fuel supply system with diesel nozzle cooling function further has the diesel nozzle connected to the diesel supply system.

[0018] The above-mentioned marine liquid ammonia fuel supply system with diesel nozzle cooling function further adopts water glycol as an intermediate medium and seawater as a cold source in the liquid ammonia cooler.

[0019] The above-mentioned marine liquid ammonia fuel supply system with diesel nozzle cooling function further adopts water glycol as an intermediate medium and steam as a heat source in the liquid ammonia heater.

[0020] The above-mentioned marine liquid ammonia fuel supply system with diesel nozzle cooling function further has an absolute mesh accuracy of 10 μm for the double filter.

[0021] The beneficial effects of the present invention are: 1. By slightly improving the existing liquid ammonia supply system, the cooling function of the diesel nozzle in the main engine diesel mode can be realized, which greatly saves cost and space.

[0022] 2. Use low-temperature liquid ammonia fuel instead of low-temperature fresh water to cool the nozzle. Since the temperature of liquid ammonia is lower, the cooling effect is better.

[0023] 3. Temporarily storing the liquid ammonia whose temperature rises after cooling the nozzle is equivalent to using the excess heat of the nozzle to preheat the liquid ammonia in advance for use in the future ammonia fuel mode, which greatly saves energy and improves the energy efficiency of the ship.

[0024] 4. Simple and effective configuration, low failure rate, good cooling effect, energy saving and reliable operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] 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 fuel nozzle, 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-diesel supply system, 20-diesel nozzle, 21-second remote control valve, 22-third remote control valve, 23-heat exchange coil, 24-receiving tank, 25-liquid ammonia cooler. DETAILED DESCRIPTION

[0026] The present invention will be further described in conjunction with the accompanying drawings.

[0027] like Figure 1 The shown is a marine liquid ammonia fuel supply system with diesel nozzle cooling function. The liquid ammonia fuel tank 1 is used to store low-temperature liquid ammonia fuel of about -33°C. When the dual-fuel main engine is running in ammonia fuel mode, the low-pressure fuel pump 2 is used to first transport the liquid ammonia to the buffer tank 3, and then the high-pressure fuel pump 5 heats and pressurizes the liquid ammonia through the heater 4 to reach the temperature and pressure required by the main engine for the liquid ammonia fuel. The heater 4 uses water ethylene glycol as an intermediate heat exchange medium to heat the liquid ammonia, and steam is used as a heat source. Since the main engine load is changing, the required fuel consumption is also constantly changing, so a regulating valve 6 and its pipeline are set. When the main engine load is small, the liquid ammonia fuel can automatically flow back to the buffer tank 3 through the regulating valve 6. The heated and pressurized liquid ammonia passes through the double filter 7 to filter out larger particle impurities and protect the stable operation of the main engine. After that, the fuel passes through the fuel valve group unit 8, and comes out of the fuel valve group unit and is supplied to the dual-fuel main engine 10 through the supply double-walled pipe 9. The supply double-wall pipe is connected to the diesel nozzle and the ammonia fuel nozzle respectively. A heat exchange coil is wound around the outside of the diesel nozzle. A second remote control valve 21 is provided on the passage from the supply double-wall pipe to the ammonia fuel nozzle, and a third remote control valve 22 is provided on the passage to the diesel nozzle. Liquid ammonia is sprayed into the cylinder 12 through the ammonia fuel nozzle 11 to burn and do work. The annular space of the supply double-wall pipe and the return double-wall pipe is provided with ventilation and leakage monitoring systems to ensure that even if ammonia leaks, it will not endanger safe areas such as the cabin.

[0028] After the main engine ammonia fuel mode operation is completed, the nitrogen supply unit 13 connected from the fuel valve group unit provides nitrogen for purging, and the fuel supply pipeline and the main engine are purged. Liquid ammonia is purged to the ammonia processing 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 is returned to the buffer tank 3 through the first remote control valve 16 for reuse, and the gas is 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 air mast 18. In addition, when the dual-fuel main engine operates in diesel mode, the diesel is transported to the diesel nozzle 20 through the diesel supply system 19 and sprayed into the cylinder for combustion and work.

[0029] When the dual-fuel main engine is running in the diesel mode, that is, the diesel is delivered to the diesel nozzle 20 through the diesel supply system 19 and sprayed into the cylinder for combustion to drive the main engine to do work. At this time, the temperature of the fuel nozzle will continue to rise. At this time, the liquid ammonia fuel supply system is operated at the same time. Unlike the ammonia fuel mode, the low-pressure fuel pump 2 and the high-pressure fuel pump 5 are frequency-converted to a low-flow load at this time, and the heater 4 does not work at this time. The liquid ammonia only flows through the heater 4 and is not heated. The second remote control valve 21 is closed and the third remote control valve 22 is opened. That is, at this time, the liquid ammonia with a smaller flow rate (sufficient to meet the cooling demand of the diesel nozzle) will not enter the cylinder through the ammonia fuel nozzle, but pass through the heat exchange coil 23. While passing through the coil, the diesel nozzle is cooled. After cooling, the liquid ammonia with a higher temperature will eventually flow back to the receiving tank 24 through the reflux pipeline for temporary storage. After the load of the main engine increases and meets the conditions for operation in the ammonia fuel mode, the main engine is switched to the ammonia fuel mode. At this time, the diesel supply system 19 changes to supply a small amount of pilot oil, and the second remote control valve 21 is opened and the third remote control valve 22 is closed. At this time, the ammonia fuel can be sprayed into the cylinder 12 through the ammonia fuel nozzle 11 to burn and do work. During the operation of the ammonia fuel mode, the first remote control valve 16 is opened, and the liquid ammonia fuel previously stored in the receiving tank 24 and heated after cooling the diesel nozzle is introduced into the buffer tank 3, and then supplied to the main engine for combustion and utilization.

[0030] The volume of the receiving tank 24 is the amount of liquid ammonia that can be contained after cooling the diesel nozzle and is heated, which determines the time that the diesel nozzle can be cooled continuously. However, if you want the main engine to be able to operate in the diesel mode all the time, that is, you need to use liquid ammonia to cool the diesel nozzle all the time, then the volume of the receiving tank is too large. At this time, you can set a smaller receiving tank or cancel it, and add a liquid ammonia cooler 25 to the liquid ammonia return line to cool the liquid ammonia that is heated by the nozzle and refluxed. The liquid ammonia cooler 25 uses water glycol as an intermediate medium to cool the refluxed liquid ammonia, and seawater is used as a cold source. In this way, the liquid ammonia can be continuously circulated during the heating of the diesel nozzle and the reflux cooling, and can be used to cool the diesel nozzle all the time, so that the main engine can be operated in the diesel mode all the time without time limit.

Claims

1. A marine liquid ammonia fuel supply system with diesel nozzle cooling function, characterized in that: The cylinder (12) inside the dual-fuel main engine (10) is provided with an ammonia fuel nozzle (11) and a diesel nozzle (20), and a heat exchange coil (23) is wound around the outside of the diesel nozzle; The ammonia fuel system is connected to the inlet of the heat exchange coil through a supply double-walled pipe (9), and the outlet of the heat exchange coil (23) is connected to the return double-walled pipe (14). A second remote control valve (21) is provided on the passage from the supply double-walled pipe (9) to the ammonia fuel nozzle, and a third remote control valve (22) is provided on the passage to the heat exchange coil (23). Liquid ammonia is heat-exchanged with the diesel nozzle via the heat exchange coil (23) and returns to the fuel valve group unit (8) in the ammonia fuel system after the heat exchange.

2. A marine liquid ammonia fuel supply system with diesel nozzle cooling function according to claim 1, characterized in that: The ammonia fuel system comprises a liquid ammonia fuel tank (1), in which a low-pressure fuel pump (2) is arranged. The low-pressure fuel pump 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 fuel nozzle (11) and a heat exchange coil (23) through a double-walled supply pipe, and the ammonia fuel nozzle (11) and a diesel nozzle (20) are connected to a cylinder (12) to spray fuel into the cylinder (12); The dual-fuel main engine is connected in sequence to the fuel valve group unit (8), the liquid ammonia cooler (25), the receiving tank (24), the ammonia processing unit (15), the ammonia absorption device (17), and the air mast (18) through a reflux double-walled pipe; The nitrogen supply unit (13) is connected to the fuel valve group unit to provide nitrogen for purging to the liquid ammonia fuel supply system and the main engine.

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

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

5. A marine liquid ammonia fuel supply system with diesel nozzle cooling function according to claim 2, characterized in that: A bypass pipeline extends out of the outlet of the high-pressure fuel pump (5) and is connected to the buffer tank. A regulating valve (6) is arranged on the pipeline so that excess fuel can flow back to the buffer tank, thereby regulating the amount of fuel supplied to the main engine.

6. A marine liquid ammonia fuel supply system with diesel nozzle cooling function according to claim 1, characterized in that: The diesel injection nozzle is connected to the diesel supply system (19).

7. A marine liquid ammonia fuel supply system with diesel nozzle cooling function according to claim 1, characterized in that: The liquid ammonia cooler uses water glycol as the intermediate medium and seawater as the cooling source.

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

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

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