Marine liquid ammonia fuel supply system capable of cooling diesel nozzle

Abstract

A marine liquid ammonia fuel supply system capable of cooling a diesel nozzle 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 the diesel nozzle, and a heat exchange coil 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 application belongs to the technical field of ship liquid ammonia fuel supply system, and particularly relates to a ship liquid ammonia fuel supply system capable of cooling diesel nozzle. BACKGROUND

[0002] The demand for green and environmentally friendly ships in the shipping industry is growing, and it is urgent to develop and introduce innovative technologies and alternative fuels for 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 types of fuels, ammonia is one of the potential zero-carbon fuels, which can be stored on ships at a temperature of minus 33 DEG C, has an acceptable energy density, does not produce carbon and sulfur compounds when burned, is easy to store and transport, has abundant energy and low price, and has become the focus of industry research.

[0003] At present, diesel / liquid ammonia dual-fuel main engines that can be applied to large ships and use ammonia fuel are still in the research and development process. When a prototype test is performed, it is found that the temperature of the diesel nozzle of the main engine will continuously increase when the main engine is operated in diesel mode, and the temperature exceeds the bearing capacity of the material. Therefore, a corresponding cooling measure needs to be taken for the nozzle. According to the traditional method, a separate fresh water cooling system is configured for the nozzle. Although this method can solve the problem of nozzle cooling, since the cooling power required by the nozzle is not large, the separate configuration of a complete cooling system including a pressure water tank, a delivery pump, a pipeline, corresponding valves, instruments, a control system and the like not only increases a large cost, occupies a large space and increases the complexity and failure rate of system configuration. SUMMARY

[0004] To solve the above problems, the application provides a ship liquid ammonia fuel supply system capable of cooling diesel nozzle, which aims to cool the nozzle when the main engine is operated in diesel mode. The technical scheme adopted by the application is as follows.

[0005] The ship liquid ammonia fuel supply system capable of cooling diesel nozzle is characterized in that the cylinder in the dual-fuel main engine is connected with an ammonia fuel nozzle and a diesel nozzle, and the diesel nozzle is externally wound with a heat exchange coil.

[0006] The ammonia fuel system comprises a liquid ammonia fuel cabin, a low-pressure fuel pump is arranged in the liquid ammonia fuel cabin, the low-pressure fuel pump is sequentially connected with a buffer tank, a heater, a high-pressure fuel pump, a double filter and a fuel valve group unit through pipelines. The fuel valve group unit is connected with the ammonia fuel nozzle and the inlet of the heat exchange coil through a supply double-wall pipe, the outlet of the heat exchange coil is connected with a return double-wall pipe, and the return double-wall pipe is sequentially connected with the fuel valve group unit, a liquid ammonia cooler, a receiving tank, an ammonia gas treatment unit, an ammonia gas absorption device and a gas permeable mast.

[0007] The supply double-wall pipe is connected with the ammonia fuel nozzle and the diesel nozzle respectively, a second remote control valve is arranged on the passage of the supply double-wall pipe leading to the ammonia fuel nozzle, a third remote control valve is arranged on the passage leading to the diesel nozzle, and liquid ammonia is sprayed into the cylinder through the ammonia fuel nozzle for combustion and work.

[0008] After the ammonia fuel mode of the dual-fuel main engine ends, nitrogen is used to purge the fuel supply pipeline and the inside of the dual-fuel main engine, the gas-liquid mixture is purged to the ammonia gas treatment unit through the reflux double-wall pipe, the ammonia gas treatment unit separates the gas-liquid mixture, the separated liquid ammonia returns to the buffer tank through the first remote control valve, the separated gas is introduced into the ammonia gas absorption device through the receiving tank, and the annular space of the supply double-wall pipe and the reflux double-wall pipe is provided with a ventilation and leakage monitoring system.

[0009] When the main engine operates in the 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 cold liquid ammonia cooling system of the diesel nozzle. By arranging the liquid ammonia receiving tank after cooling and heating, the diesel nozzle is cooled for a certain period of time or a long period of time.

[0010] The above-mentioned ship liquid ammonia fuel supply system capable of cooling the diesel nozzle is further provided with a nitrogen supply unit connected with the fuel valve group unit, which provides nitrogen for purging the liquid ammonia fuel supply system and the main engine.

[0011] The above-mentioned ship liquid ammonia fuel supply system capable of cooling the diesel nozzle is further provided with a heater and a high-pressure fuel pump, which heat the liquid ammonia to 40℃ and pressurize it to 85bar.

[0012] The above-mentioned ship liquid ammonia fuel supply system capable of cooling the diesel nozzle is further provided with an ammonia gas absorption device for absorbing ammonia gas by water.

[0013] The above-mentioned ship liquid ammonia fuel supply system capable of cooling the diesel nozzle is further provided with a bypass pipeline connected with the buffer tank at the outlet of the high-pressure fuel pump, and an adjusting valve is arranged on the pipeline, so that the excess fuel can return to the buffer tank to adjust the amount of fuel supplied to the main engine.

[0014] The above-mentioned ship liquid ammonia fuel supply system capable of cooling the diesel nozzle is further provided with a diesel nozzle connected with a diesel fuel supply system.

[0015] The above-mentioned ship liquid ammonia fuel supply system capable of cooling the diesel nozzle is further provided with a liquid ammonia heater using water glycol as an intermediate medium and steam as a heat source.

[0016] The above-mentioned ship liquid ammonia fuel supply system capable of cooling the diesel nozzle is further provided with a double filter with an absolute mesh accuracy of 10μm.

[0017] The beneficial effects of the present application are:

[0018] 1. The cooling function of the diesel nozzle in the diesel mode of the main engine can be realized by slightly modifying the existing liquid ammonia supply system, which greatly saves cost and space.

[0019] 2. Low-temperature liquid ammonia fuel is used instead of low-temperature fresh water to cool the nozzle, and since the temperature of liquid ammonia is lower, the cooling effect is better.

[0020] 3. The liquid ammonia with increased temperature after cooling the nozzle is temporarily stored, which is equivalent to using the excess heat of the nozzle to preheat the liquid ammonia in advance for future use in ammonia fuel mode, greatly saving energy and improving the energy efficiency of the ship.

[0021] 4. The configuration is simple and effective, the failure rate is low, the cooling effect is good, energy is saved, and the operation is reliable. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a schematic diagram of the system of the present application;

[0023] 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-double 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-return double-wall pipe, 15-ammonia gas treatment unit, 16-first remote control valve, 17-ammonia gas absorption device, 18-permeable mast, 19-diesel fuel supply system, 20-diesel nozzle, 21-second remote control valve, 22-third remote control valve, 23-heat exchange coil, 24-receiving tank. DETAILED DESCRIPTION

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

[0025] As Figure 1The marine liquid ammonia fuel supply system shown can cool diesel nozzle, liquid ammonia fuel tank 1 for storing about -33 ℃ low temperature liquid ammonia fuel, when the dual fuel main engine runs in ammonia fuel mode, using low pressure fuel pump 2 first to deliver liquid ammonia to buffer tank 3, then through heater 4, high pressure fuel pump 5 to warm up, pressurize liquid ammonia to achieve the temperature and pressure of the main engine demand for liquid ammonia fuel. The heater 4 is heated by water glycol as intermediate heat transfer medium, steam as heat source. Because the main engine load is variable, the required fuel consumption is also changing, so the regulating valve 6 and its pipe are set, when the main engine load is small, liquid ammonia fuel can be automatically returned to a part of the buffer tank 3 through the regulating valve 6. The warmed and pressurized liquid ammonia is filtered through the double filter 7 to remove larger particles and protect the stable operation of the main engine. After that, the fuel passes through the fuel valve group unit 8, and then through the supply double wall pipe 9 to the dual fuel main engine 10. The supply double wall pipe is connected with the diesel nozzle and the ammonia fuel nozzle, and the diesel nozzle is wrapped with a heat exchange coil. The second remote control valve 21 is arranged on the passage of the supply double wall pipe leading to the ammonia fuel nozzle, and the third remote control valve 22 is arranged on the passage leading to the diesel nozzle. The liquid ammonia is injected into the cylinder 12 through the ammonia fuel nozzle 11 for combustion and work. The annular space of the supply double wall pipe and the return double wall pipe is provided with a ventilation and leakage monitoring system to ensure that even if ammonia leaks, it will not endanger the safety area such as engine room.

[0026] After the main engine ammonia fuel mode operation is completed, the nitrogen gas supply unit 13 connected from the fuel valve group unit provides nitrogen gas for purging, and the fuel supply pipeline and the main engine are purged. The liquid ammonia is blown to the ammonia gas treatment unit 15 through the return double wall pipe 14, and the gas-liquid mixture is separated in the ammonia gas treatment unit 15. The liquid ammonia will be reused by returning to the buffer tank 3 through the first remote control valve 16, and the gas will be introduced into the ammonia gas absorption device 17. After the ammonia gas is absorbed by water, the remaining gas containing almost no ammonia is discharged into the atmosphere through the air permeable mast 18. In addition, when the dual fuel main engine runs in diesel mode, diesel is delivered to the diesel nozzle 20 through the diesel supply system 19 to be injected into the cylinder for combustion and work.

[0027] When the dual-fuel main engine is running in diesel mode, i.e. diesel is delivered to the diesel nozzles 20 through the diesel fuel supply system 19 to be combusted in the cylinder to drive the main engine to work, the temperature of the fuel nozzles will continue to rise. At this time, the liquid ammonia fuel supply system is also running, but different from the ammonia fuel mode, the low-pressure fuel pump 2 and the high-pressure fuel pump 5 are frequency-converted to low-flow load at this time, the heater 4 does not work at this time, the liquid ammonia only flows through the heater 4 and will not be heated, and the second remote control valve 21 is closed and the third remote control valve 22 is opened, i.e. the small flow of liquid ammonia (which meets the cooling requirement of the diesel nozzle) will not enter the cylinder through the ammonia fuel nozzle, but will pass through the heat exchange coil 23, and at the same time through the coil, the cooling of the diesel nozzle is completed. The cooled and temperature-increased liquid ammonia will finally flow back to the receiving tank 24 for temporary storage through the backflow pipeline. When the load of the main engine is increased and meets the conditions for running in the ammonia fuel mode, the main engine is switched to the ammonia fuel mode, at this time the diesel fuel supply system 19 becomes a small amount of pilot fuel supply, 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 injected into the cylinder 12 through the ammonia fuel nozzle 11 to be combusted to work. During the ammonia fuel mode operation, the first remote control valve 16 is opened, the liquid ammonia fuel cooled to cool the diesel nozzle and heated before being stored in the receiving tank 24 is introduced into the buffer tank 3 and then supplied to the main engine to be combusted.

Claims

1. A marine liquid ammonia fuel supply system capable of cooling diesel nozzles, characterized in that, The cylinder (12) inside the dual-fuel main unit (10) is connected to an ammonia fuel nozzle (11) and a diesel nozzle (20), and the diesel nozzle is wrapped with a heat exchange coil (23). The ammonia fuel system includes a liquid ammonia fuel tank (1), a low-pressure fuel pump (2) is installed in the ammonia fuel tank, and the low-pressure fuel pump is connected in sequence to a buffer tank (3), a heater (4), a high-pressure fuel pump (5), a dual filter (7), and a fuel valve assembly unit (8) through pipelines; the fuel valve assembly unit (8) is connected to the ammonia fuel nozzle (11) and the inlet of the heat exchange coil (23) through a supply double-wall pipe, and the outlet of the heat exchange coil (23) is connected to the return double-wall pipe (14), and is connected in sequence to the fuel valve assembly unit (8), the liquid ammonia cooler (25), the receiving tank (24), the ammonia processing unit (15), the ammonia absorption device (17), and the ventilation mast (18) through the return double-wall pipe.

2. A marine liquid ammonia fuel supply system capable of cooling diesel nozzles according to claim 1, characterized in that, The nitrogen supply unit (13) is connected to the fuel valve group unit (8) to provide purging nitrogen for the liquid ammonia fuel supply system and the main unit.

3. A marine liquid ammonia fuel supply system capable of cooling diesel nozzles according to claim 1, characterized in that, Heaters and high-pressure fuel pumps heat the liquid ammonia to 40°C and pressurize it to 85 bar.

4. A marine liquid ammonia fuel supply system capable of cooling diesel nozzles according to claim 1, characterized in that, Ammonia is absorbed by dissolving it in water within the ammonia absorption device.

5. A marine liquid ammonia fuel supply system capable of cooling diesel nozzles according to claim 2, characterized in that, The outlet of the high-pressure fuel pump extends through a bypass pipeline connected to the buffer tank, and a regulating valve (6) is installed on the pipeline. Excess fuel can flow back to the buffer tank to regulate the amount of fuel supplied to the main unit.

6. A marine liquid ammonia fuel supply system capable of cooling diesel nozzles according to claim 1, characterized in that, The diesel nozzle is connected to the diesel supply system (19).

7. A marine liquid ammonia fuel supply system capable of cooling diesel nozzles according to claim 1, characterized in that, The absolute mesh precision of the dual filter is 10μm.

8. A marine liquid ammonia fuel supply system capable of cooling diesel nozzles according to claim 1, characterized in that, The liquid ammonia heater uses water-glycol as an intermediate medium and steam as a heat source.

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