LNG (Liquefied Natural Gas) fuel supply system of high-pressure main engine

Abstract

The invention discloses a high-pressure main engine LNG fuel supply system, and relates to the technical field of LNG fuel high-pressure main engines, the high-pressure main engine LNG fuel supply system comprises a pressurization unit, an evaporation unit and a conveying unit, a fuel inlet of a high-pressure evaporator of the evaporation unit is connected with a high-pressure liquid supply pipe, and a fuel gas outlet of the high-pressure evaporator is connected with a high-pressure gas outlet pipe; a heating medium inlet of the high-pressure evaporator is connected with a steam pipeline, a heating medium outlet of the high-pressure evaporator is connected with a condensate water pipeline, and the condensate water pipeline is emptied. The steam pipeline is connected with the heating medium inlet of the high-pressure evaporator, and the heating medium outlet of the high-pressure evaporator is connected with the condensate water pipeline, so that steam is directly introduced into the high-pressure evaporator, a steam direct heating mode is adopted, a middle heating medium circulating pipeline is omitted, and the system efficiency is improved; and the condensate water is discharged in an open mode, the safety of the system can be guaranteed essentially, leaked gas cannot be brought back to a safety area, and therefore the reliability of the ship is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of LNG fuel high-pressure main engine, and in particular to a high-pressure main engine LNG fuel supply system. Background Art

[0002] As global emission regulations become increasingly stringent, liquefied natural gas (LNG) as a low-emission fuel is increasingly favored by shipowners and shipyards. Currently, more and more ships are choosing LNG as their fuel.

[0003] When using LNG as a ship fuel, the ship's high-pressure gas engines are dual-fuel diesel engines, capable of operating on either conventional diesel or compressed liquefied natural gas (CNG). When using LNG as fuel, the LNG must first be pressurized to the required pressure for the diesel engine and then vaporized into CNG. The storage, pressurization, and vaporization of LNG are collectively referred to as the high-pressure gas supply system.

[0004] The existing supply system uses a transfer pump to pump liquefied natural gas (LNG) stored in a storage tank to a high-pressure pump in a supply channel. The pressurized liquefied natural gas (LNG) is then re-gasified in an evaporator and fed to a high-pressure gas engine as fuel. The existing evaporator uses waste heat from the ship's internal combustion engine to generate steam, which heats the heat medium—glycol water—in the heat medium circulation pipeline. The glycol water is then pumped to the evaporator by a heat medium pump for heat exchange with the LNG, continuously evaporating the LNG through the circulation of the glycol water. However, the existing evaporator's heat medium circulation pipeline and steam pipeline are two sets of pipelines, which are bulky and complex to install. Summary of the Invention

[0005] The present invention provides a high-pressure main engine LNG fuel supply system to solve the above technical problems.

[0006] In order to achieve the above object, the technical solution of the present invention is:

[0007] A high-pressure main engine LNG fuel supply system includes: a pressurizing unit, an evaporation unit and a delivery unit, wherein the fuel inlet of the high-pressure evaporator of the evaporation unit is connected to a high-pressure liquid supply pipe, the gas outlet of the high-pressure evaporator is connected to a high-pressure gas outlet pipe, the heat medium inlet of the high-pressure evaporator is connected to a steam pipeline, the heat medium outlet of the high-pressure evaporator is connected to a condensate pipeline, and the condensate pipeline is emptied.

[0008] Preferably, the condensate pipeline is connected to a condensate collecting tank, and the condensate in the condensate collecting tank is discharged outside the ship through a condensate discharge pipeline.

[0009] Preferably, the condensate pipeline is connected to a condensate collection cabinet, and the condensate in the condensate collection cabinet is connected to a degassing device for removing fuel in the condensate and a safety detection device for detecting the fuel content in the condensate through a condensate discharge pipeline.

[0010] Preferably, a temperature control valve for controlling the steam flow is provided on the steam pipeline.

[0011] Preferably, a first temperature sensor for detecting the gas outlet temperature of the high-pressure evaporator is provided on the high-pressure gas outlet pipe, and a signal of the first temperature sensor is fed back to the temperature control valve.

[0012] Preferably, the delivery unit includes a GVT unit, and the gasified fuel in the high-pressure outlet pipe is delivered to the high-pressure main engine via the GVT unit.

[0013] Preferably, it further includes an automatic control system, the GVT unit is electrically connected to the automatic control system, and the automatic control system is electrically connected to the high-pressure pump of the pressurizing unit and the first reflux pipe regulating valve.

[0014] Preferably, the GVT unit collects flow, pressure and temperature signals and transmits them to the automatic control system. The automatic control system processes the flow, pressure and temperature signals to obtain the control signal of the high-pressure pump and the control signal of the first return pipe regulating valve. The automatic control system transmits the control signal of the high-pressure pump to the high-pressure pump to control the displacement of the high-pressure pump, and the automatic control system transmits the control signal of the first return pipe regulating valve to the first return pipe regulating valve to control the flow of the first return pipe regulating valve.

[0015] Preferably, the pressurizing unit includes: a fuel tank, a fuel supply pump, a low-pressure liquid supply pipe, a high-pressure pump and a first return line. The liquefied natural gas in the fuel tank is pumped to the low-pressure liquid supply pipe by the fuel supply pump. The low-pressure liquid supply pipe inputs the liquefied natural gas into the high-pressure pump for pressurization. After pressurization, the liquefied natural gas is transported to the high-pressure liquid supply pipe. The first return line allows the liquefied natural gas in the high-pressure liquid supply pipe to flow back to the fuel tank.

[0016] Preferably, the fuel supply pump and the high-pressure pump are both redundantly arranged.

[0017] Beneficial effects:

[0018] The high-pressure main engine LNG fuel supply system disclosed in this application connects a steam pipeline to the heat medium inlet of a high-pressure evaporator and connects the heat medium outlet of the high-pressure evaporator to a condensate pipeline, enabling direct steam flow into the high-pressure evaporator. This utilizes direct steam heating, eliminating the intermediate heat medium circulation pipeline and improving system efficiency. Furthermore, the condensate discharge is open, inherently ensuring system safety and preventing leaked gas from being carried back to a safe area, thereby improving ship reliability. Furthermore, the high-pressure main engine LNG fuel supply system uniformly uses a common main engine signal, reducing system and fault deviations, increasing system stability, and saving system investment and maintenance costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0020] Figure 1 This is a structural schematic diagram of a high-pressure main engine LNG fuel supply system disclosed in the present invention;

[0021] Figure 2 for Figure 1 A partial enlarged view of middle A;

[0022] Figure 3 for Figure 1 A partial enlarged view of B in the middle;

[0023] Figure 4 for Figure 1 A partial enlarged view of C in the middle.

[0024] 11. Fuel tank; 12. Fuel supply pump; 13. Low-pressure liquid supply pipe; 131. First pressure sensor; 132. Low-pressure liquid supply pipe control valve; 133. Low-pressure liquid supply pipe filter; 134. Low-pressure liquid supply pipe high-pressure pump front control valve; 135. Low-pressure liquid supply pipe high-pressure pump front manual valve a; 136. Low-pressure liquid supply pipe high-pressure pump front manual valve b; 14. High-pressure pump; 141. High-pressure pump control unit; 15. First return line; 151. First return line check valve; 152. Return main control valve; 16. First return line regulating valve; 17. Second return line; 171. Second return line regulating valve; 172. Second return line check valve; 18. Third return line; 181. Third return line check valve;

[0025] 2. High-pressure evaporator; 21. High-pressure liquid supply pipe; 211. High-pressure liquid supply pipe manual valve a; 212. High-pressure liquid supply pipe manual valve b; 22. High-pressure gas outlet pipe; 23. Steam pipeline; 24. Condensate pipeline; 25. Condensate collection cabinet; 26. Condensate discharge pipeline; 27. Temperature control valve; 28. First temperature sensor; 29. ​​Gas buffer tank;

[0026] 31. GVT unit; 311. GVT control valve; 312. GVT manual valve; 32. MASTER valve; 33. Purge valve; 34. Ventilation valve; 35. Nitrogen purge pipeline; 351. Nitrogen purge control valve; 352. Nitrogen purge check valve; 36. First vent pipeline; 37. Flow sensor; 371. Mass flow meter; 38. Second pressure sensor; 39. Second temperature sensor;

[0027] 4. High-pressure main engine; 5. Automatic control system; 10. High-pressure gas pipe; 101. Second ventilation pipeline; 102. Ventilation valve; 103. Gas supply system control valve; 20. High-pressure supply pipe. DETAILED DESCRIPTION

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0029] A high-pressure main engine LNG fuel supply system, combined with Figure 1 、 Figure 2 、 Figure 3 and Figure 4As shown, it includes: a pressurizing unit, an evaporation unit, and a delivery unit. The fuel inlet of the high-pressure evaporator 2 of the evaporation unit is connected to a high-pressure liquid supply pipe 21, the gas outlet of the high-pressure evaporator 2 is connected to a high-pressure gas outlet pipe 22, the heat medium inlet of the high-pressure evaporator 2 is connected to a steam pipeline 23, and the heat medium outlet of the high-pressure evaporator 2 is connected to a condensate pipeline 24. The condensate pipeline 24 is emptied. The present application connects the steam pipeline 23 to the heat medium inlet of the high-pressure evaporator 2 and connects the heat medium outlet of the high-pressure evaporator 2 to the condensate pipeline 24. This allows steam to be directly introduced into the high-pressure evaporator 2. By using direct steam heating, liquefied natural gas (LNG) is evaporated into natural gas (NG) and the NG temperature is adjusted to meet the requirements of the high-pressure main engine 4. This eliminates the intermediate heat medium circulation pipeline, improves system efficiency, saves costs, and increases cabin utilization. In addition, the condensate discharge is open, which can essentially ensure the safety of the system and prevent leaked gas from being brought back to a safe area, thereby improving the reliability of the ship. The present application has the advantages of low initial investment cost, low power consumption during operation, and high economic efficiency.

[0030] Preferably, condensate line 24 is connected to a condensate collection tank 25, and condensate in condensate collection tank 25 is discharged overboard via a condensate discharge line 26. The provision of condensate collection tank 25 and condensate discharge line 26 allows condensate line 24 to be drained, unlike conventional heat medium circulation through heat medium circulation lines. This inherently ensures system safety, and even if a leak occurs, it will not be carried into a safe area due to the circulation.

[0031] Preferably, condensate pipe 24 is connected to a condensate collection tank 25. Condensate in condensate collection tank 25 is connected to a degassing device for removing fuel from the condensate and a safety detection device for detecting the fuel content in the condensate via a condensate discharge pipe 26. The degassing and safety detection devices are conventional technology. By removing and detecting hazardous gases, they prevent gas leaks from the condensate, allowing the condensate to be recycled and reused, conserving fresh water resources on board and reducing the volume of fresh water tanks on LNG-powered ships and LNG carriers.

[0032] Preferably, a temperature control valve 27 for controlling the steam flow is provided on the steam pipeline 23 , and the temperature control valve 27 controls the flow of steam in the steam pipeline 23 to further adjust the NG temperature at the gas outlet of the high-pressure evaporator 2 .

[0033] Preferably, a first temperature sensor 28 for detecting the gas outlet temperature of the high-pressure evaporator 2 is provided on the high-pressure gas outlet pipe 22. The signal of the first temperature sensor 28 is fed back to the temperature control valve 27 for the temperature control valve 27 to adjust according to the temperature.

[0034] Specifically, the high-pressure gas outlet pipe 22 is connected to the gas buffer tank 29 to stabilize the gas supply pressure before supplying it to the high-pressure main engine 4.

[0035] Preferably, the delivery unit includes a GVT unit 31, through which the gasified fuel in the high-pressure outlet pipe 22 is delivered to the high-pressure main engine 4. The GVT unit 31 controls the start and stop of the high-pressure main engine 4 and adjusts various parameters during operation to ensure that the high-pressure main engine 4 can operate with optimal performance under different operating conditions, thereby achieving efficient energy utilization.

[0036] Specifically, the NG in the high-pressure gas outlet pipe 22 first enters the gas buffer tank 29. The NG discharged from the gas buffer tank 29 is then transported to the GVT unit 31 via the high-pressure gas pipe 10. The GVT unit 31 is connected to the high-pressure main engine 4 via the high-pressure supply pipe 20. The NG output by the GVT unit 31 is supplied to the high-pressure main engine 4 via the high-pressure supply pipe 20. The section of the high-pressure supply pipe 20 from the engine room safety zone to the high-pressure main engine 4 is a double-walled pipe design with redundant ventilation and hazardous gas detection functions to enhance safety.

[0037] Preferably, an automatic control system 5 is further included, the GVT unit 31 is electrically connected to the automatic control system 5 , and the automatic control system 5 is electrically connected to the high-pressure pump 14 and the first reflux pipe regulating valve 16 of the pressurizing unit.

[0038] Specifically, the GVT unit 31 is provided by the OEM and includes a master valve 32, a purge valve 33, a vent valve 34, a nitrogen purge line 35, a first vent line 36, a flow sensor 37, a second pressure sensor 38, and a second temperature sensor 39. The master valve 32, purge valve 33, vent valve 34, nitrogen purge line 35, and first vent line 36 are used for safety operations during an emergency shutdown (ESD), enabling functions such as emergency shutdown, nitrogen purge, monitoring, and control. The flow sensor 37, second pressure sensor 38, and second temperature sensor 39 collect flow, pressure, and temperature signals and feed them back to the automated control system 5.

[0039] Specifically, a second air vent pipeline 101 is provided on the high-pressure gas pipe 10 , the second air vent pipeline 101 is connected to the air vent mast, and an air vent valve 102 is provided on the second air vent pipeline 101 for remote control and for emergency discharge operation.

[0040] Specifically, a gas supply system control valve 103 is provided on the high-pressure gas pipe 10 . The gas supply system control valve 103 is located between the second gas pipeline 101 and the GVT unit 31 and is used to control the high-pressure NG to enter the GVT unit 31 .

[0041] Specifically, the GVT unit 31 also includes a mass flow meter 371, a GVT manual valve 312, and a GVT control valve 311. After entering the GVT unit 31, high-pressure NG passes through the mass flow meter 371, the GVT manual valve 312, and the GVT control valve 311 before flowing to the master valve 32 and the purge valve 33. A nitrogen purge control valve 351 and a nitrogen purge check valve 352 are provided on the nitrogen purge line 35.

[0042] Preferably, the GVT unit 31 collects flow, pressure and temperature signals and transmits them to the automatic control system 5, which processes the flow, pressure and temperature signals to generate control signals for the high-pressure pump 14 and the first return pipe regulating valve 16, specifically according to the formula: Q supply =(P2-P1)×A / (R×T)+Q flow Processing, Q supply Indicates the displacement of the high-pressure pump, Q flow represents the displacement value collected by flow sensor 37, P1 represents the reference supply pressure collected by second pressure sensor 38, P2 represents the initial supply pressure collected by second pressure sensor 38, A represents the cross-sectional area of ​​the supply pipe, R represents the gas constant, and T represents the supply temperature collected by second temperature sensor 39. The automated control system 5 transmits a control signal from the high-pressure pump 14 to the high-pressure pump 14 to control the displacement of the high-pressure pump 14. The automated control system 5 also transmits a control signal from the first return pipe regulating valve 16 to the first return pipe regulating valve 16 to control the flow rate of the first return pipe regulating valve 16.

[0043] The automated control system 5 first controls the displacement of the high-pressure pump 14, and the high-pressure pump 14 uses frequency conversion to adjust the flow supply according to the control signal. Under normal working conditions, the variable frequency high-pressure pump can better control the supply flow so that the gas supply pressure is within the normal design range. When the main engine is working at too low a load or the load is rapidly reduced, in order to ensure the stability of the system and the rapidity of control, the automated control system 5 can make a judgment based on the design upper limit of the gas supply pressure, and the first return pipe regulating valve 16 adjusts the return flow according to the control signal to further control the supply pressure to a reasonable value. As a secondary control method, the first return pipe regulating valve 16 can correct the flow of the high-pressure liquid supply pipe 21 to avoid excessive flow, and at the same time serve as a second guarantee to ensure the safe operation of the system. Since the operation of the first return pipe regulating valve 16 will cause waste of system energy, the setting value is usually close to the upper limit of the main engine supply pressure, which is an important guarantee for the reliable operation of the system.

[0044] The unified use of signals from the GVT unit 31 facilitates signal consistency across all shipboard systems. Signals are provided to both the high-voltage main engine 4 and the fuel supply system simultaneously, avoiding system deviations and fault errors associated with using two sets of equipment and two signal sources, thereby increasing system stability. This also reduces the cost of having two signal acquisition systems, saving both system investment and maintenance costs.

[0045] When a system failure causes the high-pressure main engine 4 to shut down, a unified control signal is issued by the automated control system 5 (AMS). The high-pressure main engine 4, GVT unit 31, and fuel supply system each perform a series of pre-set operations according to the control logic, without causing any interference. The high-pressure main engine 4 and GVT unit 31 will sequentially close, purge, and test the relevant control valves. The fuel supply system will then emergency close / open the ESD valve to ensure system safety.

[0046] Preferably, the pressurizing unit includes: a fuel tank 11, a fuel supply pump 12, a low-pressure liquid supply pipe 13, a high-pressure pump 14 and a first return line 15. The liquefied natural gas in the fuel tank 11 is pumped to the low-pressure liquid supply pipe 13 by the fuel supply pump 12. The low-pressure liquid supply pipe 13 inputs the liquefied natural gas into the high-pressure pump 14 for pressurization. After pressurization, the liquefied natural gas is transported to the high-pressure liquid supply pipe 21. The first return line 15 allows the liquefied natural gas in the high-pressure liquid supply pipe 21 to flow back to the fuel tank 11.

[0047] Specifically, the fuel tank 11 is a Type C tank capable of withstanding relatively high pressures. Typically, based on filling calculations, it can maintain pressure buildup over a period of time. Low-temperature LNG is stored within the fuel tank 11, which features excellent thermal insulation to reduce heat transmission and natural evaporation rates. Furthermore, the Type C tank employed in this application can accumulate boil-off gas over a prolonged period, providing a beneficial measure for managing boil-off gas during ship operations.

[0048] Specifically, the fuel supply pump 12 can utilize a variable frequency controlled submersible pump or a variable frequency controlled deep well pump. Using a variable frequency pump allows the speed and flow rate of the fuel supply pump 12 to be adjusted according to the control of the automated control system 5. In this embodiment, a variable frequency controlled deep well pump is preferably used. The variable frequency motor is located outside the fuel tank 11 to prevent heat from escaping into the tank and reduce evaporation. One or more fuel supply pumps 12 can be provided as needed. In this embodiment, two fuel supply pumps 12 are provided for redundancy.

[0049] The fuel supply pump 12 delivers the LNG in the fuel tank 11 to the high-pressure pump 14 to increase the pressure to 300-400 BarG.

[0050] Specifically, the high-pressure pump 14 can adopt a variable frequency controlled electric motor pump and a variable frequency controlled hydraulic motor pump. The high-pressure pump 14 is controlled by a high-pressure pump control unit 141, and can automatically control the flow. The high-pressure pump 14 usually adopts a 2x100% or 3x50% redundant configuration. In this embodiment, the high-pressure pump 14 adopts a variable frequency controlled electric motor pump.

[0051] Preferably, the high-pressure pumps 14 are provided in two groups for redundancy. As a secondary option, the fuel supply pumps 12 and the high-pressure pumps 14 can be provided in three groups respectively.

[0052] Specifically, the pressurizing unit also includes a second return line 17 and a third return line 18. One end of the second return line 17 is connected to the low-pressure liquid supply pipe 13, and the other end is connected to the first return line 15. One end of the third return line 18 is connected to the high-pressure pump 14, and the other end is connected to the first return line 15. The second return line 17 is provided with a second return line regulating valve 171 and a second return line check valve 172, and the third return line 18 is provided with a third return line check valve 181. The first return line 15, the second return line 17 and the third return line 18 all return to the fuel tank 11.

[0053] Specifically, a first return line check valve 151 and a return main control valve 152 are provided on the first return line 15. The first return line check valve 151 is located between the point where the second return line 17 and the third return line 18 merge into the first return line 15 and the first return line regulating valve 16. The return main control valve 152 is located on one side along the return direction of the point where the second return line 17 and the third return line 18 merge into the first return line 15, and is used for overall control of the reflux.

[0054] Specifically, a first pressure sensor 131 is provided on the low-pressure liquid supply pipe 13. The first pressure sensor 131 is used to monitor the gas supply pressure. The signal of the first pressure sensor 131 can be fed back to the fuel supply pump 12 and the second return pipe regulating valve 171. The pressure is adjusted by adjusting the flow rate of the fuel supply pump 12 and the opening of the second return pipe regulating valve 171.

[0055] Specifically, the low-pressure liquid supply pipe 13 is equipped with a low-pressure liquid supply pipe control valve 132, located in front of the first pressure sensor 131, and used to control the on / off flow of the front portion of the low-pressure liquid supply pipe 13. The low-pressure liquid supply pipe 13 is also equipped with a low-pressure liquid supply pipe filter 133, located after the second return line 17, to meet the fuel accuracy requirements of the high-pressure pump 14, the high-pressure outlet pipe 22, and the high-pressure main engine 4. The low-pressure liquid supply pipe 13 is also equipped with a low-pressure liquid supply pipe high-pressure pump front control valve 134, located after the low-pressure liquid supply pipe filter 133 and before the high-pressure pump 14. This valve is used to control the on / off flow of the rear portion of the low-pressure liquid supply pipe 13, thereby controlling the inflow of LNG and stopping the inflow of LNG to the high-pressure pump 14. The low-pressure liquid supply pipe 13 is provided with a low-pressure liquid supply pipe high-pressure pump front manual valve a135 and a low-pressure liquid supply pipe high-pressure pump front manual valve b136. The low-pressure liquid supply pipe high-pressure pump front manual valve a135 and the low-pressure liquid supply pipe high-pressure pump front manual valve b136 respectively control the low-pressure liquid supply pipe 13 to connect to the two groups of high-pressure pumps 14.

[0056] Specifically, a high-pressure liquid supply pipe manual valve a211 and a high-pressure liquid supply pipe manual valve b212 are provided on the high-pressure liquid supply pipe 21. The high-pressure liquid supply pipe manual valve a211 and the high-pressure liquid supply pipe manual valve b212 are located at the front part of the high-pressure liquid supply pipe 21. The high-pressure liquid supply pipe manual valve a211 and the high-pressure liquid supply pipe manual valve b212 are used to respectively control the connection of the two groups of high-pressure pumps 14 to the high-pressure liquid supply pipe 21.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-pressure main engine LNG fuel supply system, comprising: The pressurizing unit, evaporating unit and conveying unit are characterized in that the fuel inlet of the high-pressure evaporator (2) of the evaporating unit is connected to the high-pressure liquid supply pipe (21), the gas outlet of the high-pressure evaporator (2) is connected to the high-pressure gas outlet pipe (22), the heat medium inlet of the high-pressure evaporator (2) is connected to the steam pipeline (23), the heat medium outlet of the high-pressure evaporator (2) is connected to the condensate pipeline (24), and the condensate pipeline (24) is emptied.

2. A high-pressure main engine LNG fuel supply system according to claim 1, characterized in that: The condensate pipeline (24) is connected to a condensate collecting tank (25), and the condensate in the condensate collecting tank (25) is discharged outside the ship through a condensate discharge pipeline (26).

3. A high-pressure main engine LNG fuel supply system according to claim 1, characterized in that: The condensate pipeline (24) is connected to a condensate collection cabinet (25), and the condensate in the condensate collection cabinet (25) is connected to a degassing device for removing fuel in the condensate and a safety detection device for detecting the fuel content in the condensate through a condensate discharge pipeline (26).

4. A high-pressure main engine LNG fuel supply system according to claim 2 or 3, characterized in that: The steam pipeline (23) is provided with a temperature control valve (27) for controlling the steam flow rate.

5. A high-pressure main engine LNG fuel supply system according to claim 4, characterized in that: The high-pressure gas outlet pipe (22) is provided with a first temperature sensor (28) for detecting the gas outlet temperature of the high-pressure evaporator (2), and a signal of the first temperature sensor (28) is fed back to the temperature control valve (27).

6. The high-pressure main engine LNG fuel supply system according to claim 1, characterized in that: The delivery unit comprises a GVT unit (31), and the gasified fuel in the high-pressure outlet pipe (22) is delivered to the high-pressure main engine (4) via the GVT unit (31).

7. A high-pressure main engine LNG fuel supply system according to claim 6, characterized in that: The system further comprises an automatic control system (5), wherein the GVT unit (31) is electrically connected to the automatic control system (5), and the automatic control system (5) is electrically connected to the high-pressure pump (14) of the pressurizing unit and the first return pipe regulating valve (16).

8. A high-pressure main engine LNG fuel supply system according to claim 7, characterized in that: The GVT unit (31) collects flow, pressure and temperature signals and transmits them to the automatic control system (5). The automatic control system (5) processes the flow, pressure and temperature signals to obtain a control signal of the high-pressure pump (14) and a control signal of the first return pipe regulating valve (16). The automatic control system (5) transmits the control signal of the high-pressure pump (14) to the high-pressure pump (14) to control the displacement of the high-pressure pump (14). The automatic control system (5) transmits the control signal of the first return pipe regulating valve (16) to the first return pipe regulating valve (16) to control the flow of the first return pipe regulating valve (16).

9. The high-pressure main engine LNG fuel supply system according to claim 1, characterized in that: The pressurizing unit comprises: a fuel tank (11), a fuel supply pump (12), a low-pressure liquid supply pipe (13), a high-pressure pump (14) and a first return line (15). The liquefied natural gas in the fuel tank (11) is pumped to the low-pressure liquid supply pipe (13) by the fuel supply pump (12). The low-pressure liquid supply pipe (13) inputs the liquefied natural gas into the high-pressure pump (14) for pressurization. After the pressurization, the liquefied natural gas is transported to the high-pressure liquid supply pipe (21). The first return line (15) allows the liquefied natural gas in the high-pressure liquid supply pipe (21) to flow back to the fuel tank (11).

10. The high-pressure main engine LNG fuel supply system according to claim 1, characterized in that: The fuel supply pump (12) and the high-pressure pump (14) are both redundantly arranged.

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