Fuel supply device of ship engine

Abstract

The invention discloses a fuel supply device of a ship engine, which comprises an LNG (Liquefied Natural Gas) storage tank, a low-pressure compressor, a gas-liquid separator, a fuel container, a high-pressure compressor, a low-pressure engine and a high-pressure engine, and is characterized in that evaporated natural gas in the LNG storage tank is discharged along an evaporated natural gas pipeline and is compressed at low pressure in the low-pressure compressor; compressed low-pressure evaporated natural gas passes through a gas-liquid separator, re-liquefied evaporated natural gas and non-re-liquefied evaporated natural gas are separated, the non-re-liquefied evaporated natural gas is supplied to a fuel container, the fuel container can be discharged in two ways, one way is connected with a low-pressure engine through a first fuel pipeline to supply fuel to the low-pressure engine, and the other way is connected with a second fuel pipeline to supply fuel to the low-pressure engine. And the other path of natural gas passes through a high-pressure compressor, compresses the natural gas to fuel gas pressure required by the high-pressure engine, and is connected with the high-pressure engine through a third fuel pipeline to supply fuel to the high-pressure engine. The evaporation natural gas of the LNG storage tank is recycled, so that unnecessary waste is reduced.

Description

Technical Field

[0001] The present invention relates to an engine for a ship, and in particular to a fuel supply device for a ship engine. Background Art

[0002] On LNG (liquefied natural gas) powered ships, there are LNG storage tanks for storing LNG. The LNG storage tanks are generally heat-insulated because LNG exists in a liquefied form at about -163°C. However, the heat-insulating ability of such LNG storage tanks is limited, which results in the continuous natural evaporation of the LNG stored in the LNG storage tank during transportation, thereby generating a large amount of evaporated natural gas. As time goes by, the internal pressure of the LNG storage tank will gradually increase. If its internal pressure exceeds the predetermined safety pressure, it may cause the LNG storage tank to rupture. Therefore, a safety valve is needed to discharge the excess evaporated natural gas. However, this fails to reasonably utilize the evaporated natural gas, resulting in a certain amount of resource waste. Summary of the Invention

[0003] In order to overcome the deficiencies of the prior art, the present invention provides a fuel supply device for a ship engine.

[0004] The first technical solution adopted by the present invention to solve its technical problems is: A fuel supply device for a ship engine includes an LNG storage tank installed on a ship. The exhaust port of the LNG storage tank is connected to an evaporated natural gas pipeline. A low-pressure compressor is provided on the evaporated natural gas pipeline. The output end of the evaporated natural gas pipeline is connected to the intake port of a gas-liquid separator. The exhaust port of the gas-liquid separator is connected to a fuel container. The exhaust port of the fuel container is divided into two paths. One path is connected to a low-pressure engine, and the other path is connected to a high-pressure engine through a high-pressure compressor.

[0005] As a further improvement of the present invention, the exhaust port of the gas-liquid separator is connected to the fuel container through a gas phase pipeline. The liquid discharge port of the gas-liquid separator is connected to the LNG storage tank through a first recovery pipeline. A first flow meter is provided on the gas phase pipeline, and a first control valve is provided on the first recovery pipeline.

[0006] As a further improvement of the present invention, a safety valve is provided on the evaporated natural gas pipeline, and the safety valve is located between the gas-liquid separator and the low-pressure compressor.

[0007] As a further improvement of the present invention, the liquid discharge port of the fuel container is connected to the LNG storage tank through a second recovery pipeline, and a second control valve is provided on the second recovery pipeline.

[0008] As a further improvement of the present invention, one path of the exhaust port of the fuel container is connected to the low-pressure engine through a first fuel pipeline, and the other path is connected to the high-pressure compressor through a second fuel pipeline. The high-pressure compressor is connected to the high-pressure engine through a third fuel pipeline.

[0009] As a further improvement of the present invention, a third control valve is provided on the first fuel pipeline, a second flowmeter and a fourth control valve are provided on the second fuel pipeline, and a fifth control valve is provided on the third fuel pipeline.

[0010] As an important technical path to meet the ship's nitrogen oxide emission regulations, the EGR (Exhaust Gas Recirculation) system has attracted much attention. Nitrogen oxides (NOx) are mainly generated during the high-temperature and high-pressure combustion process in the engine combustion chamber. Nitrogen and oxygen in the air react chemically in an environment above 1500 °C to generate nitrogen oxides such as NO and NO2. The EGR system suppresses the generation of NOx by optimizing the intake strategy. Its core principle is to precisely control the oxygen content entering the combustion chamber and only supply the oxygen required for the complete combustion of the fuel to the engine combustion chamber, thereby reducing the generation probability of NOx in the high-temperature and oxygen-rich environment. The specific working process is as follows: The exhaust gas generated by the engine combustion, after being cooled and purified, the part rich in carbon dioxide is re-introduced into the intake system and mixed with fresh combustion-supporting air. This process increases the carbon dioxide concentration in the combustion-supporting gas and relatively reduces the oxygen proportion, causing the peak combustion temperature to drop, reducing the generation of nitrogen oxides from the source, and ultimately achieving compliance with ship emissions.

[0011] As described above, although the EGR system can effectively reduce nitrogen oxide emissions by re-introducing part of the exhaust gas into the engine combustion air, it has a relatively high initial investment cost in practical applications because the engine has many additional devices, and the engine output is reduced due to the exhaust gas. On the other hand, when using natural gas as the engine fuel, a large amount of nitrogen oxides will be generated, and additional equipment must be installed to meet the emission regulations. Therefore, a method for reducing nitrogen oxide emissions in ships using LNG as the engine fuel is needed.

[0012] The second technical solution adopted by the present invention to solve the reduction of nitrogen oxide emissions is: A fuel supply device for a marine engine, comprising an LNG storage tank, a hydrogen storage tank and a heat exchanger. The exhaust port of the LNG storage tank is connected to an evaporated natural gas pipeline, and a low-pressure compressor is provided on the evaporated natural gas pipeline. The exhaust port of the hydrogen storage tank is connected to the input end of the heat exchanger through an evaporated hydrogen pipeline, and the evaporated natural gas pipeline of the LNG storage tank is connected to the input end of the heat exchanger; the output end of the heat exchanger is connected to the intake port of a gas-liquid separator, the exhaust port of the gas-liquid separator is connected to a fuel container, the fuel container is connected to a high-pressure compressor through a second fuel pipeline, and the high-pressure compressor is connected to a high-pressure engine through a third fuel pipeline.

[0013] In this solution, the fuel gas obtained by mixing natural gas and hydrogen in a certain proportion can reduce the amount of carbon dioxide in the exhaust gas. In addition, by controlling the mixing ratio of natural gas and hydrogen to make the mixture of natural gas and hydrogen uniform, the combustion safety of the engine can be improved. In addition, since the evaporated natural gas can be recycled by re-liquefaction, it can be used without wasting the evaporated natural gas, which is both economical and environmentally friendly. In addition, since the cooling heat of the evaporated hydrogen is used to re-liquefy the evaporated natural gas, the energy required to liquefy the evaporated natural gas can be minimized. In addition, when a large amount of evaporated hydrogen is generated, by storing the excess evaporated hydrogen, all the evaporated hydrogen can be used without waste and can be reused as engine fuel when necessary, which is economical and environmentally friendly.

[0014] As a further improvement of the present invention, the hydrogen storage tank is connected to the input end of the heat exchanger through an evaporated hydrogen pipeline. After the evaporated hydrogen pipeline of the hydrogen storage tank passes through the heat exchanger, hydrogen is transmitted to the fuel container.

[0015] As a further improvement of the present invention, a hydrogen compressor, a sixth control valve and a third flowmeter are provided on the evaporated hydrogen pipeline. The hydrogen compressor is located at the rear end of the sixth control valve, the sixth control valve is located at the front end of the heat exchanger, and the third flowmeter is located at the rear end of the heat exchanger and the front end of the fuel container.

[0016] The beneficial effects of the present invention are as follows: The evaporated natural gas in the LNG storage tank of the present invention is discharged along the evaporated natural gas pipeline and compressed at low pressure in a low-pressure compressor. The compressed low-pressure evaporated natural gas passes through a gas-liquid separator to separate the re-liquefied evaporated natural gas from the non-re-liquefied evaporated natural gas. The non-re-liquefied evaporated natural gas is supplied to a fuel container, which can be discharged in two ways. One way is connected to a low-pressure engine through a first fuel pipeline to supply fuel to the low-pressure engine, and the other way passes through a high-pressure compressor to compress the natural gas to the fuel gas pressure required by the high-pressure engine and is connected to the high-pressure engine through a third fuel pipeline to supply fuel to the high-pressure engine. The present invention recovers and utilizes the evaporated natural gas in the LNG storage tank 1, thereby reducing unnecessary waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention will be further described below in conjunction with the drawings and embodiments.

[0018] Figure 1 It is a schematic diagram of the first embodiment of the present invention.

[0019] Figure 2 It is a schematic diagram of the second embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the specific embodiments and with reference to the drawings. It should be noted that, without conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

[0021] It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention.

[0022] Some embodiments of the present invention provided will be described below in conjunction with the drawings.

[0023] Embodiment 1: Refer to Figure 1 , Figure 1This is a schematic structural diagram of an LNG fuel supply provided by the present invention. A fuel supply device for a marine engine includes an LNG storage tank 1 installed on a ship. The LNG storage tank 1 is used to store LNG. The LNG storage tank 1 can be a container for transporting LNG on the ship or a container for supplying fuel to the engine. The exhaust port of the LNG storage tank 1 is connected to an evaporated natural gas pipeline 11. A low-pressure compressor 12 is provided on the evaporated natural gas pipeline 11. The output end of the evaporated natural gas pipeline 11 is connected to the intake port of a gas-liquid separator 2. The exhaust port of the gas-liquid separator 2 is connected to a fuel container 3. The exhaust port of the fuel container 3 is divided into two paths. One path is connected to a low-pressure engine 4, and the other path is connected to a high-pressure engine 6 through a high-pressure compressor 5. In this embodiment, the natural gas evaporated in the LNG storage tank 1 is discharged along the exhaust port, then passes through the low-pressure compressor 12 and the gas-liquid separator 2 and enters the fuel container 3. The fuel container 3 supplies fuel to the low-pressure engine 4 or the high-pressure engine 6, so that the evaporated natural gas in the LNG storage tank 1 can be utilized, reducing unnecessary waste.

[0024] In this embodiment, the low-pressure engine 4 can be a DFDE engine (Dual Fuel Diesel Electric Engine). The DFDE engine consists of four strokes and is a low-pressure gas injection engine using the Otto cycle. During the working process, low-pressure natural gas of about 6.5 bar (bar) is injected into the combustion air inlet, and then the piston rises to compress it. This low-pressure engine 4 can be used as an engine for ship power generation. The low-pressure compressor 12 compresses the pressure of the natural gas. On the one hand, it makes the natural gas more stable during pipeline transportation. On the other hand, it provides the required fuel gas pressure for the low-pressure engine 4.

[0025] The high-pressure engine 6 can be an ME-GI engine (MAN Electronic Gas Injection Engine) or a diesel / LNG dual-fuel engine. The ME-GI engine consists of two strokes and is a high-pressure gas injection engine using the diesel cycle. During the working process, high-pressure natural gas of about 300 bar is directly injected into the cylinder for combustion. This high-pressure engine 6 can be used as an engine for ship propulsion. The natural gas pressure in the fuel container 3 is relatively low, so a high-pressure compressor 5 is provided. The high-pressure compressor 5 compresses the natural gas to the fuel gas pressure required by the high-pressure engine 6.

[0026] As a further improvement of the present invention, the exhaust port of the gas-liquid separator 2 is connected to the fuel container 3 through a gas-phase pipeline 21, and the liquid discharge port of the gas-liquid separator 2 is connected to the LNG storage tank 1 through a first recovery pipeline 22. A first flowmeter 24 is provided on the gas-phase pipeline 21, and a first control valve 23 is provided on the first recovery pipeline 22. The gas-liquid separator 2 can separate the re-liquefied evaporated natural gas from the un-reliquefied evaporated natural gas. The separated gaseous natural gas is transmitted to the fuel container 3 through the gas-phase pipeline 21, and the separated liquid natural gas is recovered into the LNG storage tank 1 through the first recovery pipeline 22. In this embodiment, when the water level in the gas-liquid separator 2 reaches above the set value, the valve of the first control valve 23 can be opened to recover the re-liquefied evaporated natural gas into the LNG storage tank 1. Additionally, when the amount of evaporated natural gas is greater than the amount required by the low-pressure engine 4 or the high-pressure engine 6, the valve of the first control valve 23 can be opened to allow more evaporated natural gas to be re-liquefied from the gas-liquid separator 2 into the LNG storage tank 1 for convenient adjustment.

[0027] As a further improvement of the present invention, a safety valve 13 is provided on the evaporated natural gas pipeline 11. The safety valve 13 is located between the gas-liquid separator 2 and the low-pressure compressor 12. When the internal pressure of the LNG storage tank 1 exceeds the set pressure, the safety valve 13 can be opened to discharge the evaporated natural gas in the LNG storage tank 1, thereby reducing the internal pressure. The evaporated natural gas discharged from the LNG storage tank 1 flows along the evaporated natural gas pipeline 11. After passing through the gas-liquid separator 2, the separated gas can be supplied as fuel for the engine, and the separated liquid is recovered into the LNG storage tank 1, thereby reducing the waste of unnecessary evaporated natural gas. Additionally, the first flowmeter 24 is used to measure the flow rate of the evaporated natural gas supplied to the fuel container 3, and the opening and closing of the safety valve 13 are adjusted according to the measured flow rate value, so that the flow rate supplied to the fuel container 3 can be controlled for convenient control and adjustment.

[0028] As a further improvement of the present invention, the liquid discharge port of the fuel container 3 is connected to the LNG storage tank 1 through a second recovery pipeline 31. A second control valve 32 is provided on the second recovery pipeline 31. The fuel container 3 discharges evaporated natural gas, and these evaporated natural gases are recovered into the LNG storage tank 1. When the amount in the fuel container 3 is greater than the amount required by the engine, evaporated natural gas is continuously generated in the fuel container 3. In the temperature equilibrium state, the pressure inside the container will keep rising, and the natural gas will be recompressed back into the liquid state. Therefore, the opening and closing of the second control valve 32 can be controlled according to the liquid level in the fuel container 3. That is to say, when the water level in the fuel container 3 is higher than the set value, the valve of the second control valve 32 can be opened to discharge the evaporated natural gas from the fuel container 3 to prevent the pressure inside the fuel container 3 from being too high.

[0029] The exhaust port of the fuel container 3 is connected to the low-pressure engine 4 through the first fuel pipeline 41, and to the high-pressure compressor 5 through the second fuel pipeline 51. The high-pressure compressor 5 is connected to the high-pressure engine 6 through the third fuel pipeline 61. A third control valve 42 is provided on the first fuel pipeline 41, a second flow meter 52 and a fourth control valve 53 are provided on the second fuel pipeline 51, and a fifth control valve 62 is provided on the third fuel pipeline 61. The third control valve 42 can adjust the flow rate of the gas in the first fuel pipeline 41 according to the amount of fuel gas required by the low-pressure engine 4. The fifth control valve 62 can adjust the flow rate of the gas in the third fuel pipeline 61 according to the amount of fuel gas required by the high-pressure engine 6. The second flow meter 52 is used to measure the flow rate of the evaporated natural gas supplied to the high-pressure compressor 5, and adjusts the opening and closing of the fourth control valve 53 according to the measured flow rate value, so as to provide the amount of fuel gas required by the high-pressure engine 6, which is convenient for control and adjustment.

[0030] Working principle: The evaporated natural gas in the LNG storage tank 1 is discharged along the evaporated natural gas pipeline 11 and compressed at low pressure in the low-pressure compressor 12. The compressed low-pressure evaporated natural gas passes through the gas-liquid separator 2 to separate the re-liquefied evaporated natural gas from the un-reliquefied evaporated natural gas. The un-reliquefied evaporated natural gas is supplied to the fuel container 3. The fuel container 3 can be discharged in two ways. One way is connected to the low-pressure engine 4 through the first fuel pipeline 41 to supply fuel to the low-pressure engine 4. The other way passes through the high-pressure compressor 5 to compress the natural gas to the fuel gas pressure required by the high-pressure engine 6 and is connected to the high-pressure engine 6 through the third fuel pipeline 61 to supply fuel to the high-pressure engine 6. When the two engines work simultaneously, there may be a shortage of natural gas supply. Therefore, the low-pressure engine 4 and the high-pressure engine 6 are supplied separately. The present invention recovers and utilizes the evaporated natural gas in the LNG storage tank 1, thereby reducing unnecessary waste.

[0031] Embodiment 2: Refer to Figure 2 , Figure 2 is a schematic structural diagram of the present invention for supplying a mixture of LNG fuel and hydrogen. The second embodiment of the present invention is a variant of the first embodiment. The difference lies in adding hydrogen as a supply fuel. In the following, the differences between the second embodiment and the first embodiment of the present invention will be mainly described. Even if the description is omitted, the same reference numerals can be given in the same way as the first embodiment, and of course, changes can also be made within the scope of design changes.

[0032] In this embodiment, the fuel gas and nitrogen oxides obtained by mixing natural gas and hydrogen in a certain ratio can reduce the amount of carbon dioxide in the exhaust gas. Additionally, by controlling the mixing ratio of natural gas and hydrogen to ensure uniform mixing, the combustion safety of the engine can be improved. Moreover, since the evaporated natural gas can be recovered by reliquefaction, it can be used without waste, which is both economical and environmentally friendly. Furthermore, by using the cooling heat of the evaporated hydrogen to reliquefy the evaporated natural gas, the energy required for liquefying the evaporated natural gas can be minimized. Additionally, when a large amount of evaporated hydrogen is generated, by storing the excess evaporated hydrogen, all the evaporated hydrogen can be used without waste and can be reused as engine fuel when necessary, which is economical and environmentally friendly.

[0033] Specifically, the fuel supply structure further includes a hydrogen storage tank 7 and a heat exchanger 8. The exhaust port of the hydrogen storage tank 7 is connected to the input end of the heat exchanger 8 through an evaporated hydrogen pipeline 71. The evaporated natural gas pipeline 11 of the LNG storage tank 1 is connected to the input end of the heat exchanger 8. The evaporated natural gas of the LNG storage tank 1 is transmitted to the gas-liquid separator 2 after passing through the heat exchanger 8, and then transmitted to the fuel container 3. The evaporated hydrogen of the hydrogen storage tank 7 is transmitted to the fuel container 3 after passing through the heat exchanger 8. In the fuel container 3, the evaporated natural gas and the evaporated hydrogen are uniformly mixed, and then the gas is compressed to the fuel gas pressure required by the high-pressure engine 6 through a high-pressure compressor 5. This embodiment makes reasonable use of the evaporated natural gas of the LNG storage tank 1 and the evaporated hydrogen of the hydrogen storage tank 7, effectively reducing unnecessary waste.

[0034] In this embodiment, the hydrogen stored in the hydrogen storage tank 7 will also continuously evaporate naturally during transportation, resulting in the generation of evaporated hydrogen. Therefore, the evaporated hydrogen is recovered and utilized. Additionally, if it is used to provide power for ship propulsion, the high-pressure engine 6 requires more fuel. In the first embodiment, if only the evaporated natural gas of the LNG storage tank is used as fuel, there may be a phenomenon of insufficient fuel supply. The combustion speed of hydrogen is fast, and the flame propagation speed is faster than that of methane, which enables the mixed fuel to achieve a faster combustion process in the engine combustion chamber. Relatively speaking, methane has a higher energy density and can provide a more stable energy output during combustion. After the two are mixed, the stability and combustion efficiency of the combustion process can be improved. This mixed fuel can be applied to ship propulsion. In particular, the high-pressure engine 6 can be a ME-GI engine (MAN electronic gas injection engine), which can burn natural gas and hydrogen simultaneously.

[0035] A hydrogen compressor 72, a sixth control valve 73 and a third flowmeter 74 are provided on the evaporation hydrogen pipeline 71. The hydrogen compressor 72 is located at the rear end of the sixth control valve 73. The sixth control valve 73 is located at the front end of the heat exchanger 8. The third flowmeter 74 is located at the rear end of the heat exchanger 8 and the front end of the fuel container 3. In this embodiment, the hydrogen compressor 72 is used to compress the evaporation hydrogen at low pressure; the third flowmeter 74 is used to measure the flow rate of the evaporation hydrogen supplied to the fuel container 3, and adjust the opening and closing of the sixth control valve 73 according to the measured flow rate value, so that the flow rate supplied to the fuel container 3 can be controlled, which is convenient for control and adjustment.

[0036] Specifically, in the heat exchanger 8, the low-pressure evaporation natural gas will be cooled by the heat exchange 8, so that part of the evaporation natural gas can be re-liquefied, avoiding excessive use of natural gas and reducing unnecessary waste. In addition, the temperature of the low-pressure evaporation hydrogen will increase, making the hydrogen active, which is convenient for the mixing of the evaporation hydrogen and the evaporation natural gas. Among them, if the mixing ratio of hydrogen in the fuel container 3 is too high, after being supplied to the high-pressure engine 6, incomplete combustion may occur, and environmental pollutants such as carbon monoxide may be emitted instead. Therefore, the opening and closing of the sixth control valve 73 and the safety valve 13 can be controlled according to the flow rates measured by the first flowmeter 24 and the third flowmeter 74, so that the mixing ratio of the fuel gas mixed in the fuel container 3 is stable. The mixing ratio can be a preset value or can be changed according to the load of the high-pressure engine 6.

[0037] Working principle: The evaporation natural gas in the LNG storage tank 1 is discharged along the evaporation natural gas pipeline 11 and compressed at low pressure in the low-pressure compressor 12; the evaporation hydrogen in the hydrogen storage tank 7 is discharged along the evaporation hydrogen pipeline 71 and compressed at low pressure in the hydrogen compressor 72; the low-pressure evaporation natural gas will be cooled by the heat exchange 8, and then pass through the gas-liquid separator 2 to separate the re-liquefied evaporation natural gas from the un-reliquefied evaporation natural gas. The un-reliquefied evaporation natural gas is supplied to the fuel container 3; the low-pressure evaporation hydrogen is transmitted to the fuel container 3 through the heat exchange 8 and mixed with the evaporation natural gas. The fuel container 3 transmits the mixed fuel gas to the high-pressure compressor 5 through the second fuel pipeline 51. The high-pressure compressor 5 compresses the fuel gas to the fuel gas pressure required by the high-pressure engine 6 and is connected to the high-pressure engine 6 through the third fuel pipeline 61 to supply fuel to the high-pressure engine 6. The present invention recovers and utilizes the evaporation natural gas in the LNG storage tank 1 and the evaporation hydrogen in the hydrogen storage tank 7, thereby reducing unnecessary waste.

[0038] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the claims and their equivalents.

Claims

1. A fuel supply device for a marine engine, characterized in that, It includes an LNG storage tank (1) installed on a ship. The exhaust port of the LNG storage tank (1) is connected to an evaporated natural gas pipeline (11). A low-pressure compressor (12) is provided on the evaporated natural gas pipeline (11). The output end of the evaporated natural gas pipeline (11) is connected to the intake port of a gas-liquid separator (2). The exhaust port of the gas-liquid separator (2) is connected to a fuel container (3). The exhaust port of the fuel container (3) is divided into two paths. One path is connected to a low-pressure engine (4), and the other path is connected to a high-pressure engine (6) through a high-pressure compressor (5).

2. The fuel supply device for a marine engine according to claim 1, characterized in that The exhaust port of the gas-liquid separator (2) is connected to the fuel container (3) through a gas-phase pipeline (21). The liquid discharge port of the gas-liquid separator (2) is connected to the LNG storage tank (1) through a first recovery pipeline (22). A first flowmeter (24) is provided on the gas-phase pipeline (21), and a first control valve (23) is provided on the first recovery pipeline (22).

3. The fuel supply device for a marine engine according to claim 1, characterized in that A safety valve (13) is provided on the evaporated natural gas pipeline (11), and the safety valve (13) is located between the gas-liquid separator (2) and the low-pressure compressor (12).

4. The fuel supply device of the marine engine according to claim 1, characterized in that The liquid discharge port of the fuel container (3) is connected to the LNG storage tank (1) through a second recovery pipeline (31), and a second control valve (32) is provided on the second recovery pipeline (31).

5. The fuel supply device for a marine engine according to claim 1, characterized in that One path of the exhaust port of the fuel container (3) is connected to the low-pressure engine (4) through a first fuel pipeline (41), and the other path is connected to the high-pressure compressor (5) through a second fuel pipeline (51). The high-pressure compressor (5) is connected to the high-pressure engine (6) through a third fuel pipeline (61).

6. The fuel supply device for a marine engine according to claim 1, characterized in that A third control valve (42) is provided on the first fuel pipeline (41), a second flowmeter (52) and a fourth control valve (53) are provided on the second fuel pipeline (51), and a fifth control valve (62) is provided on the third fuel pipeline (61).

7. A fuel supply device for a marine engine, characterized in that, It includes an LNG storage tank (1), a hydrogen storage tank (7) and a heat exchanger (8). The exhaust port of the LNG storage tank (1) is connected to an evaporated natural gas pipeline (11). A low-pressure compressor (12) is provided on the evaporated natural gas pipeline (11). The exhaust port of the hydrogen storage tank (7) is connected to the input end of the heat exchanger (8) through an evaporated hydrogen pipeline (71). The evaporated natural gas pipeline (11) of the LNG storage tank (1) is connected to the input end of the heat exchanger (8). The output end of the heat exchanger (8) is connected to the intake port of a gas-liquid separator (2). The exhaust port of the gas-liquid separator (2) is connected to a fuel container (3). The fuel container (3) is connected to the high-pressure compressor (5) through a second fuel pipeline (51). The high-pressure compressor (5) is connected to the high-pressure engine (6) through a third fuel pipeline (61).

8. The fuel supply device for a marine engine according to claim 7, characterized in that The hydrogen storage tank (7) is connected to the input end of the heat exchanger (8) through an evaporated hydrogen pipeline (71). After the evaporated hydrogen pipeline (71) of the hydrogen storage tank (7) passes through the heat exchanger (8), hydrogen is transmitted into the fuel container (3).

9. The fuel supply device for a marine engine according to claim 7, characterized in that A hydrogen compressor (72), a sixth control valve (73) and a third flowmeter (74) are provided on the evaporation hydrogen pipeline (71). The hydrogen compressor (72) is located at the rear end of the sixth control valve (73). The sixth control valve (73) is located at the front end of the heat exchanger (8). The third flowmeter (74) is located at the rear end of the heat exchanger (8) and the front end of the fuel container (3).

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