Dual-phase redundant high-pressure main engine LNG ship fuel gas supply system

Abstract

The invention discloses a biphase redundant high-pressure main engine LNG ship fuel gas supply system, which belongs to the technical field of liquefied natural gas transport ship fuel gas supply, and comprises a high-pressure gas supply subsystem and a low-pressure gas supply subsystem which share a high-pressure compressor and are in redundant design. The high-pressure gas supply subsystem forcibly pressurizes and evaporates cargo hold liquid-phase natural gas through a redundant high-pressure gas supply pipeline assembly by means of a high-pressure pump and an evaporation unit, or compresses cargo hold evaporation gas through a high-pressure compressor to be supplied to a high-pressure host. The low-pressure gas supply subsystem comprises a low-pressure evaporation and heating unit and a low-pressure gas supply pipeline assembly, through redundancy of the low-pressure gas supply pipeline assembly, the low-pressure evaporation and heating unit is used for forcibly evaporating and heating liquid-phase natural gas of the cargo hold, or natural evaporation gas of the cargo hold is compressed by a high-pressure compressor and a low-pressure branch of the high-pressure compressor and then is heated; and supplying to an LNG ship generator and a gas combustion device. The system forms an efficient architecture with high-pressure and low-pressure subsystem redundancy coordination, ensures stable and safe air supply, maintains pressure balance of the cargo hold, and reduces the cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of liquefied natural gas carrier gas supply, in particular to a dual-redundant high-pressure main engine LNG carrier gas supply system. BACKGROUND

[0002] LNG (Liquefied Natural Gas Carrier) is a special ship specially used for transporting low-temperature liquefied natural gas (LNG) at -162℃.

[0003] The high-pressure main engine propelling LNG carrier adopts ME-GI dual-fuel main engine and dual-fuel generator. The ME-GI main engine is a high-pressure main engine provided by MAN Energy Solutions, and the gas supply pressure is 300-400 barg. The ME-GI main engine has high thermal efficiency and good fuel economy, and has excellent methane escape control in terms of environmental protection, which meets the future carbon emission tax and environmental protection policy trend. Such LNG carrier needs to configure high and low pressure systems, the high pressure system is used to supply the high pressure main engine, and the low pressure system is used to supply the generator and the gas combustion device.

[0004] According to the specification requirements, a single mechanical failure cannot affect the normal propulsion of the ship, so the high pressure system and the low pressure system need to additionally increase a set of equipment as a replacement scheme to ensure the normal operation of the LNG carrier. The traditional design of the high pressure system is a design scheme of two high pressure compressors for gas supply, which are used as mutual backup. When one high pressure compressor fails, the other high pressure compressor can be used instead. However, due to the high cost of high pressure compressors, the double set configuration will cause the initial investment cost to be too high. The traditional design of the low pressure system is to use two sets of low pressure compressors or two low pressure pumps matched with evaporators. The system has more equipment and sufficient reliability, but the initial investment cost is high. SUMMARY

[0005] The present application provides a dual-redundant high-pressure main engine LNG carrier gas supply system to overcome the above problems.

[0006] In order to achieve the above purpose, the technical scheme of the present application is: A dual-redundant high-pressure main engine LNG carrier gas supply system, comprising a high-pressure gas supply subsystem and a low-pressure gas supply subsystem which share a high-pressure compressor and are both redundantly designed; The high-pressure gas supply subsystem comprises a high-pressure pump and evaporation unit, a high-pressure compressor and a high-pressure gas cooler; the high-pressure gas supply subsystem can use the high-pressure pump and evaporation unit to force the liquid-phase natural gas output from the cargo hold to be pressurized and evaporated into gaseous fuel to supply the LNG ship high-pressure power main engine through a redundant high-pressure gas supply pipeline assembly, or use the high-pressure compressor to compress and pressurize the evaporated gas output from the cargo hold and provide the LNG ship high-pressure power main engine after cooling by the high-pressure gas cooler; The low-pressure gas supply subsystem comprises a low-pressure evaporation and heating unit and a low-pressure gas supply pipeline assembly; The low-pressure gas supply subsystem can use the low-pressure evaporation and heating unit to force the liquid-phase natural gas in the cargo hold to be evaporated into gaseous fuel and heated to supply the LNG ship generator and gas combustion device through a redundant low-pressure gas supply pipeline assembly, or use the high-pressure compressor and the low-pressure branch of the high-pressure compressor to compress the natural evaporated gas derived from the cargo hold and heat the compressed evaporated gas to supply the LNG ship generator and gas combustion device through the heating function of the low-pressure evaporation and heating unit.

[0007] Further, the high-pressure pump and evaporation unit comprises a high-pressure pump unit and a high-pressure evaporator; The high-pressure pump unit can pressurize the liquid-phase natural gas output from the cargo hold and deliver it to the high-pressure evaporator; The high-pressure evaporator can force the liquid-phase natural gas to be evaporated into gaseous fuel to supply the LNG ship high-pressure power main engine.

[0008] Further, the low-pressure evaporation and heating unit comprises a low-pressure evaporator and a low-pressure gas heater; The low-pressure evaporator is used to force the liquid-phase natural gas output from the cargo hold to be evaporated into gaseous fuel and deliver it to the low-pressure gas heater; The low-pressure gas heater is used to heat the gaseous fuel forced to evaporate by the low-pressure evaporator and deliver it to the LNG ship generator and the gas combustion device.

[0009] Further, the high-pressure gas supply subsystem further comprises a buffer tank used to buffer the liquid-phase natural gas output from the cargo hold before it enters the high-pressure pump unit.

[0010] Further, the redundant high-pressure gas supply pipeline assembly comprises a liquid-phase natural gas high-pressure gas supply pipeline assembly and a gaseous natural gas high-pressure gas supply pipeline assembly; the liquid-phase natural gas high-pressure gas supply pipeline assembly can deliver the high-pressure gaseous fuel converted from the liquid-phase natural gas in the cargo hold to the LNG ship high-pressure power main engine; the gaseous natural gas high-pressure gas supply pipeline assembly can deliver the high-pressure gaseous fuel converted from the evaporated gas in the cargo hold to the LNG ship high-pressure power main engine; The liquid-phase natural gas high-pressure supply pipeline set comprises a first liquid-phase natural gas pipeline, a liquid-phase buffer natural gas pipeline, a high-pressure liquid-phase natural gas pipeline, and a first high-pressure natural gas pipeline; two ends of the first liquid-phase natural gas pipeline are respectively connected with an outlet end of a low-pressure LNG fuel pipeline of the cargo tank and an inlet end of the buffer tank; two ends of the liquid-phase buffer natural gas pipeline are respectively connected with an outlet end of the buffer tank and an inlet end of the high-pressure pump unit; two ends of the high-pressure liquid-phase natural gas pipeline are respectively connected with an outlet end of the high-pressure pump unit and an inlet end of the high-pressure evaporator; and two ends of the first high-pressure natural gas pipeline are respectively connected with an outlet end of the high-pressure evaporator and the LNG ship high-pressure power main engine. The cargo tank is provided with a liquid-phase natural gas fuel supply pump for delivering liquid-phase natural gas inside the cargo tank to the low-pressure LNG fuel pipeline. The gas-phase natural gas high-pressure supply pipeline set comprises an evaporated gas pipeline, a second high-pressure natural gas pipeline, and a third high-pressure natural gas pipeline; two ends of the evaporated gas pipeline are respectively connected with an evaporated gas output header pipeline of the cargo tank and an inlet end of the high-pressure compressor; two ends of the second high-pressure natural gas pipeline are respectively connected with a high-pressure outlet end of the high-pressure compressor and an inlet end of the high-pressure gas cooler; and two ends of the third high-pressure natural gas pipeline are respectively connected with an outlet end of the high-pressure gas cooler and the first high-pressure natural gas pipeline.

[0011] Further, the redundant low-pressure supply pipeline assembly comprises a liquid-phase natural gas low-pressure supply pipeline set and a gas-phase natural gas low-pressure supply pipeline; the liquid-phase natural gas low-pressure supply pipeline set can deliver low-pressure gas fuel converted from liquid-phase natural gas in the cargo tank to the LNG ship generator and the gas combustion device; and the gas-phase natural gas low-pressure supply pipeline can deliver low-pressure gas fuel converted from evaporated gas in the cargo tank to the LNG ship generator and the gas combustion device. The liquid-phase natural gas low-pressure supply pipeline set comprises a second liquid-phase natural gas pipeline, a first low-pressure NG gas pipeline, and a second low-pressure NG gas pipeline. Two ends of the second liquid-phase natural gas pipeline are respectively connected with an outlet end of the low-pressure LNG fuel pipeline and an inlet end of the low-pressure evaporator; two ends of the first low-pressure NG gas pipeline are respectively connected with an outlet end of the low-pressure evaporator and an inlet end of the low-pressure gas heater; and two ends of the second low-pressure NG gas pipeline are respectively connected with an outlet end of the low-pressure gas heater and the LNG ship generator and the gas combustion device. The gas-phase natural gas low-pressure supply pipeline is a low-pressure branch of the high-pressure compressor, and two ends of the low-pressure branch are respectively connected with a low-pressure outlet of the high-pressure compressor and the first low-pressure NG gas pipeline.

[0012] Further, the low-pressure LNG fuel pipe is provided with a first control valve; the liquid-phase buffer natural gas pipe is provided with a second control valve; the first high-pressure natural gas pipe is provided with a third control valve at one end close to the high-pressure power main engine of the LNG ship; the boil-off gas pipe is provided with a fourth control valve; the second high-pressure natural gas pipe is provided with a fifth control valve; and the third high-pressure natural gas pipe is provided with a sixth control valve.

[0013] Further, the second liquid-phase natural gas pipe is provided with a seventh control valve; the first low-pressure NG fuel pipe is provided with an eighth control valve, which is arranged at a side of the first low-pressure NG fuel pipe away from the low-pressure fuel gas heater at a connection position of the low-pressure branch; and the second low-pressure NG fuel pipe is provided with a ninth control valve at one end close to the LNG ship generator and the gas combustion device.

[0014] Further, a first gas valve group unit is arranged between the outlet end of the first high-pressure natural gas pipe and the high-pressure power main engine of the LNG ship; and a second gas valve group unit is arranged between the outlet end of the second low-pressure NG fuel pipe and the LNG ship generator and between the outlet end of the second low-pressure NG fuel pipe and the gas combustion device.

[0015] Further, the pressure range of the gas fuel delivered to the high-pressure power main engine of the LNG ship is 300-400 barg; and the pressure range of the gas fuel delivered to the LNG ship generator and the gas combustion device is 6-16 barg.

[0016] The present application has the following advantages: The dual-phase redundant high-pressure main engine LNG ship gas supply system disclosed in the present application uses the redundancy design of forced evaporation and natural evaporation of liquid-phase natural gas in the high-pressure gas supply subsystem to ensure that the high-pressure main engine obtains stable and safe high-pressure gas supply, realizes the dual backup guarantee of equipment and pipeline, maintains the cargo hold pressure balance by consuming natural evaporation gas, and avoids the high cost of double high-pressure compressors; the redundancy design of forced evaporation of liquid-phase natural gas and supply of natural evaporation gas through the low-pressure branch of the high-pressure compressor in the low-pressure gas supply subsystem ensures that the generator and the gas combustion device obtain reliable low-pressure gas, realizes the dual-phase redundancy of low-pressure gas supply at low cost without additional configuration of compressors, significantly improves the safety, stability and economy of the overall operation of the system, and forms an efficient gas supply architecture with redundancy cooperation of the high-pressure and low-pressure gas supply subsystems. BRIEF DESCRIPTION OF DRAWINGS In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, below the drawings needed to be used in the embodiments or prior art description will be simply introduced. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative labor.

[0017] Figure 1 Structure diagram of a dual-phase redundant high-pressure main engine LNG ship gas supply system disclosed in an embodiment of the present application Figure 1 ; Figure 2 Structure diagram of a dual-phase redundant high-pressure main engine LNG ship gas supply system disclosed in an embodiment of the present application Figure 2 .

[0018] In the drawings: 1, high-pressure gas supply subsystem; 101, high-pressure compressor; 102, high-pressure gas cooler; 103, high-pressure pump unit; 104, high-pressure evaporator; 105, buffer tank; 106, first liquid-phase natural gas pipe; 107, liquid-phase buffer natural gas pipe; 108, high-pressure liquid-phase natural gas pipe; 109, first high-pressure natural gas pipe; 110, evaporated gas pipe; 111, second high-pressure natural gas pipe; 112, third high-pressure natural gas pipe; 113, second control valve; 114, third control valve; 115, fourth control valve; 116, fifth control valve; 117, sixth control valve; 118, first gas valve group unit; 119, first high-pressure gas double-wall pipe; 2, low-pressure gas supply subsystem; 201, low-pressure branch; 202, low-pressure evaporator; 203, low-pressure gas heater; 204, second liquid-phase natural gas pipe; 205, first low-pressure NG gas pipe; 206, second low-pressure NG gas pipe; 207, seventh control valve; 208, eighth control valve; 209, ninth control valve; 210, second gas valve group unit; 211, second high-pressure gas double-wall pipe; 3, cargo hold; 301, low-pressure LNG fuel pipe; 302, evaporated gas output branch pipe; 303, evaporated gas output main pipe; 304, first control valve; 4, high-pressure power main engine of LNG ship; 5, LNG ship generator; 6, gas combustion device; 7, liquid-phase natural gas fuel supply pump; 8, emergency pipe; 801, emergency pipe valve. DETAILED DESCRIPTION

[0019] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0020] Embodiment As Figures 1-2 shown is a dual-phase redundant high-pressure main engine LNG ship gas supply system provided by the embodiment, comprising a high-pressure gas supply subsystem 1 and a low-pressure gas supply subsystem 2 which share a high-pressure compressor 101 and are both redundantly designed; The high-pressure gas supply subsystem 1 comprises a high-pressure pump and evaporation unit, the high-pressure compressor 101 and a high-pressure gas cooler 102. The high-pressure gas supply subsystem can use the high-pressure pump and evaporation unit to force the liquid-phase natural gas output from a cargo hold 3 to be pressurized and evaporated into gaseous fuel, and supply the gaseous fuel to a high-pressure power main engine 4 of an LNG ship through a redundant high-pressure gas supply pipeline assembly, or use the high-pressure compressor 101 to compress and pressurize the evaporated gas output from the cargo hold 3, and supply the evaporated gas cooled to a temperature of 45±10℃ by the high-pressure gas cooler 102 to the high-pressure power main engine 4 of the LNG ship; The low-pressure gas supply subsystem 2 comprises a low-pressure evaporation and heating unit and a low-pressure gas supply pipeline assembly. The low-pressure gas supply subsystem 2 can use the low-pressure evaporation and heating unit to force the liquid-phase natural gas in the cargo hold 3 to be evaporated into gaseous fuel and heated, and supply the gaseous fuel to a generator 5 and a gas combustion unit 6 (GCU) of an LNG ship through a redundant low-pressure gas supply pipeline assembly, or use the high-pressure compressor 101 and a low-pressure branch 201 of the high-pressure compressor 101 to compress the naturally evaporated gas led out from the cargo hold 3, and supply the compressed evaporated gas heated by a heating function of the low-pressure evaporation and heating unit to the generator 5 and the gas combustion unit 6 of the LNG ship.

[0021] During LNG (Liquefied Natural Gas) carrier transport, it is crucial to minimize LNG evaporation. This is because LNG, a cryogenic liquid (-162°C), readily absorbs heat and transforms into boil-off gas (BOG). One volume of LNG evaporates to approximately 600 volumes of BOG. ​​Excessive evaporation can cause several problems: firstly, it leads to a rapid increase in tank pressure, potentially causing tank rupture if it exceeds design limits. Leaking LNG or released BOG can create flammable and explosive environments, directly threatening the safety of the ship and personnel. Secondly, unrecovered BOG can only be released through depressurization, resulting in direct loss of LNG cargo, causing economic losses for the cargo owner and wasting energy. Furthermore, methane, with its lower boiling point, evaporates preferentially, increasing the proportion of heavy hydrocarbons in the remaining liquid. This can lead to issues such as gasification at the receiving terminal, coking in combustion equipment, or incomplete combustion, compromising cargo quality. Therefore, preventing LNG evaporation is a core requirement for mitigating safety risks, reducing economic losses, ensuring cargo compliance, and achieving safe and efficient LNG carrier transport.

[0022] This invention discloses a dual-phase redundant high-pressure main engine LNG ship gas supply system. Through the redundant design of the high-pressure gas supply subsystem using forced evaporation of liquid natural gas and natural evaporation, it ensures a stable and safe high-pressure gas supply to the high-pressure main engine. This provides dual backup for equipment and pipelines, and maintains cargo hold pressure balance by consuming natural evaporation gas, while avoiding the high cost of dual high-pressure compressors. The low-pressure gas supply subsystem utilizes the redundant design of forced evaporation of liquid natural gas and natural evaporation gas supplied via the low-pressure branch of the high-pressure compressor, ensuring a reliable low-pressure gas supply to the generator and gas combustion device. Without requiring additional compressors, it achieves dual-phase redundancy in low-pressure gas supply at low cost, significantly improving the overall system's safety, stability, and economy, forming a highly efficient gas supply architecture with redundant coordination between the high-pressure and low-pressure gas supply subsystems.

[0023] In most cases, the evaporated gas in the cargo hold is used first to power the high-pressure main engine, generator and gas combustion device of the LNG ship. When the evaporated gas is insufficient to power the high-pressure main engine, generator and gas combustion device (such as boiler) of the LNG ship, liquid natural gas and evaporated gas are used together to power the above equipment.

[0024] In a specific embodiment, the high-pressure pump and evaporation unit includes a high-pressure pump unit 103 and a high-pressure evaporator 104; The high-pressure pump unit 103 can pressurize the liquid natural gas output from the cargo hold 3 by the liquid natural gas fuel pump and deliver it to the high-pressure evaporator 104 through the high-pressure gas supply pipeline; the high-pressure evaporator 104 can force the liquid natural gas to evaporate into gaseous fuel to supply the LNG ship high-pressure power main engine 4. The high-pressure pump unit 103 is a high-pressure pump group. In this embodiment, it is configured with two high-pressure pumps connected in parallel. The liquid natural gas input by the fuel supply pump 7 is pressurized to a high-pressure state by the high-pressure pump unit 103. The high-pressure evaporator 104 forces the pressurized liquid natural gas to evaporate into gaseous fuel, and delivers it to the LNG ship high-pressure power main engine 4 through the first high-pressure natural gas pipe 109 and the first high-pressure gas double-wall pipe 119. The high-pressure pump unit 103 can ensure that the gas pressure output from the liquid path matches the gas supply pressure of the high-pressure compressor 101 gas path, meeting the high-pressure main engine's requirement for gas pressure (300-400 barg). The high-pressure evaporator 104 provides an independent and reliable liquid gas supply path for the high-pressure main engine, forming a dual-phase redundancy with the gas path. The parallel high-pressure pump design in this embodiment can achieve seamless switching in case of single pump failure. The high-pressure evaporator 104 ensures that the liquid natural gas is completely vaporized, avoiding damage caused by liquid medium entering the main engine, and jointly improving the stability and safety of the high-pressure gas supply subsystem 1.

[0025] In a specific embodiment, the low-pressure evaporation and heating unit includes a low-pressure evaporator 202 and a low-pressure gas heater 203; The low-pressure evaporator 202 is used to force the liquid natural gas output from the cargo hold 3 to evaporate into gaseous fuel, and then transport it to the low-pressure gas heater 203 through pipeline. The low-pressure gas heater 203 is used to heat the gaseous fuel formed by forced evaporation of the low-pressure evaporator 202, and delivers it to the LNG ship generator 5 and the gas combustion device 6 through pipelines.

[0026] Cargo hold 3 is equipped with a fuel supply pump 7. The low-pressure evaporator 202 can efficiently convert the liquid natural gas supplied by the fuel supply pump 7 into gaseous fuel, avoiding problems such as freezing and cracking or abnormal combustion caused by the liquid medium entering the subsequent low-pressure pipelines or equipment, and realizing stable gas production in the liquid phase path of the low-pressure gas supply subsystem 2. At the same time, it works in conjunction with the gas phase gas supply scheme of the low-pressure branch 201 of the high-pressure compressor 101 to form a dual-phase redundancy basis for low-pressure gas supply, ensuring that a continuous gas supply can still be provided to the generator and gas combustion device 6 when a single gas source or equipment fails.

[0027] Before the gaseous fuel output from the low-pressure evaporator 202 and the compressed evaporative gas delivered by the low-pressure branch 201 of the high-pressure compressor 101 are delivered to the LNG ship generator 5 and the gas combustion device 6, the low-pressure gas heater 203 heats the two types of gaseous fuel to a temperature of 0-60°C. This ensures that the gas temperature is raised to a range suitable for the fuel combustion requirements of the low-pressure equipment / user (generator, gas combustion device), avoiding low-temperature damage to equipment components or a decrease in combustion efficiency caused by low-temperature gas. It also ensures the consistency of temperature parameters of low-pressure gas from different sources, ensuring that the second gas valve group unit 210 (Gas Valve Unit, GVU unit) of the LNG ship generator 5 and the second gas valve group unit 210 (GVU unit) of the gas combustion device 6 meet the operating conditions required for stable equipment operation, thereby improving the operational reliability of the low-pressure gas supply subsystem 2.

[0028] In a specific embodiment, the high-pressure gas supply subsystem 1 further includes a buffer tank 105, which is used to buffer the liquid natural gas output from the cargo hold 3 before it enters the high-pressure pump unit 103. The buffered liquid natural gas enters the high-pressure pump unit 103 to balance the pressure fluctuations that may occur during the output of liquid natural gas from the cargo hold 3 (such as changes in the flow rate of the fuel supply pump 7 and instantaneous fluctuations in pipeline pressure), avoiding sudden increases or decreases in the inlet pressure of the high-pressure pump unit 103 due to pressure instability, thereby preventing cavitation, abnormal flow, and other malfunctions of the high-pressure pump and ensuring the stable operation of the high-pressure pump unit 103. At the same time, the buffer tank 105 can temporarily store a certain amount of liquid natural gas. When there is a brief pipeline failure from the cargo hold 3 to the buffer tank 105 or when the fuel supply pump 7 is switched, it can continuously provide liquid medium to the high-pressure pump unit 103, avoiding the high-pressure pump from stopping due to fuel shortage, ensuring the continuous gas supply capacity of the liquid path of the high-pressure gas supply subsystem 1, further supporting the stability of the fuel supply to the high-pressure main engine, and adapting to the reliability requirements of the system's dual-phase redundancy design.

[0029] In a specific embodiment, the redundant high-pressure gas supply pipeline assembly includes a liquid-phase natural gas high-pressure gas supply pipeline group and a gas-phase natural gas high-pressure gas supply pipeline group; the liquid-phase natural gas high-pressure gas supply pipeline group can transport the high-pressure gaseous fuel converted from the liquid-phase natural gas in the cargo hold 3 to the LNG ship high-pressure power main engine 4; the gas-phase natural gas high-pressure gas supply pipeline group can transport the high-pressure gaseous fuel converted from the evaporated gas in the cargo hold 3 to the LNG ship high-pressure power main engine 4; The high-pressure liquid-phase natural gas supply pipeline assembly includes a first liquid-phase natural gas pipeline 106, a liquid-phase buffer natural gas pipeline 107, a high-pressure liquid-phase natural gas pipeline 108, and a first high-pressure natural gas pipeline 109. The two ends of the first liquid-phase natural gas pipeline 106 are respectively connected to the outlet end of the low-pressure LNG fuel pipeline 301 in the cargo hold 3 and the inlet end of the buffer tank 105. The two ends of the liquid-phase buffer natural gas pipeline 107 are respectively connected to the outlet end of the buffer tank 105 and the inlet end of the high-pressure pump unit 103. The two ends of the high-pressure liquid-phase natural gas pipeline 108 are respectively connected to the outlet end of the high-pressure pump unit 103 and the inlet end of the high-pressure evaporator 104. The two ends of the first high-pressure natural gas pipeline 109 are respectively connected to the outlet end of the high-pressure evaporator 104 and the high-pressure power main engine 4 (gas fuel input end) of the LNG ship. Cargo hold 3 is equipped with a liquid natural gas fuel supply pump 7 for supplying its internal liquid natural gas to the low-pressure LNG fuel pipe 301. The inlet of the low-pressure LNG fuel pipe 301 is connected to the liquid natural gas fuel supply pump 7. The liquid natural gas fuel in cargo hold 3 is pumped out by the liquid natural gas fuel supply pump 7, enters the first liquid natural gas pipe 106 through the low-pressure LNG fuel pipe 301, and is then transported by the first liquid natural gas pipe 106 to the buffer tank 105 for pressure buffering. The buffered liquid natural gas is then transported to the inlet of the high-pressure pump unit 103 through the liquid-phase buffer natural gas pipe 107. The high-pressure pump unit 103 forces the pressurization to the pressure required by the high-pressure main engine, and then transports it to the high-pressure evaporator 104 through the high-pressure liquid natural gas pipe 108. The high-pressure liquid natural gas entering the high-pressure evaporator 104 is forced to evaporate into gaseous fuel. The high-pressure gaseous fuel then enters the first high-pressure natural gas pipe 109 and is transported along the first high-pressure natural gas pipe 109 to the LNG ship's high-pressure main engine 4. Finally, it is regulated by the main engine's first gas valve group unit 118 and used for combustion in the main engine.

[0030] Among them, the low-pressure LNG fuel pipe 301 serves as the initial pipeline for transporting liquid natural gas, and can stably receive the liquid medium output by the liquid natural gas fuel supply pump 7, avoiding medium leakage or flow fluctuation caused by insufficient pipeline adaptability during the initial transportation stage; the high-pressure liquid natural gas pipe 108 has high pressure resistance characteristics, and can safely transport the high-pressure liquid natural gas after being pressurized by the high-pressure pump unit 103, preventing the high-pressure medium from breaking down the pipeline and causing safety risks. The gas phase natural gas high-pressure supply pipeline assembly includes an evaporation gas pipeline 110, a second high-pressure natural gas pipeline 111, and a third high-pressure natural gas pipeline 112. The two ends of the evaporation gas pipeline 110 are respectively connected to the evaporation gas output main pipeline 303 of the cargo compartment 3 and the inlet end of the high-pressure compressor 101. The two ends of the second high-pressure natural gas pipeline 111 are respectively connected to the high-pressure outlet end of the high-pressure compressor 101 and the inlet end of the high-pressure gas cooler 102. The two ends of the third high-pressure natural gas pipeline 112 are respectively connected to the outlet end of the high-pressure gas cooler 102 and the first high-pressure natural gas pipeline 109.

[0031] Cargo hold 3 is connected to an evaporation gas output branch pipeline 302. All evaporation gas output branch pipelines 302 in each cargo hold 3 converge to the evaporation gas output main pipeline 303. Then, the evaporation gas (gas phase natural gas fuel) enters the evaporation gas pipeline 110 from the evaporation gas output main pipeline 303. After being compressed by the high-pressure compressor 101, it is converted into high-temperature and high-pressure gaseous natural gas with pressure matching the requirements of the high-pressure main engine. Then, it is transported / transmitted by the second high-pressure natural gas pipeline 111 to the high-pressure gas cooler 102 for cooling. After cooling, it enters the third high-pressure natural gas pipeline 112 to ensure that the gaseous fuel parameters entering the subsequent pipelines and the LNG ship high-pressure power main engine 4 meet the requirements for safe operation and efficient combustion. The cooled high-pressure gaseous natural gas is transmitted through the third high-pressure natural gas pipeline 112 to the first high-pressure natural gas pipeline 109, and finally delivered to the LNG ship high-pressure power main engine 4, realizing a stable gas supply to the high-pressure main engine through the gas phase path. The high-pressure gas supply pipelines for liquid-phase natural gas and gas-phase natural gas form a path redundancy. When any pipeline experiences blockage, leakage, or other faults, or when the high-pressure pump, evaporation unit, or high-pressure compressor 101 fails, the other pipeline can continue to ensure the gas supply to the high-pressure main unit, further improving the operational reliability of the high-pressure gas supply subsystem 1.

[0032] In a specific embodiment, the redundant low-pressure gas supply pipeline assembly includes a liquid-phase natural gas low-pressure gas supply pipeline group and a gas-phase natural gas low-pressure gas supply pipeline; the liquid-phase natural gas low-pressure gas supply pipeline group can transport the low-pressure gaseous fuel converted from the liquid-phase natural gas in the cargo hold 3 to the LNG ship generator 5 and the gas combustion device 6; the gas-phase natural gas low-pressure gas supply pipeline can transport the low-pressure gaseous fuel converted from the evaporated gas in the cargo hold 3 to the LNG ship generator 5 and the gas combustion device 6; The liquid phase natural gas low-pressure gas supply pipeline group includes a second liquid phase natural gas pipeline 204, a first low-pressure NG gas pipeline 205, and a second low-pressure NG gas pipeline 206. The two ends of the second liquid natural gas pipe 204 are respectively connected to the outlet end of the low-pressure LNG fuel pipe 301 and the inlet end of the low-pressure evaporator 202; the two ends of the first low-pressure NG gas pipe 205 are respectively connected to the outlet end of the low-pressure evaporator 202 and the inlet end of the low-pressure gas heater 203; the two ends of the second low-pressure NG gas pipe 206 are respectively connected to the outlet end of the low-pressure gas heater 203, the gas fuel input end of the LNG ship generator 5, and the gas fuel input end of the gas combustion device 6. The liquid natural gas fuel in cargo hold 3 is output by liquid natural gas fuel supply pump 7, enters the second liquid natural gas pipeline 204 through the low-pressure LNG fuel pipeline 301, and is then transported to the low-pressure evaporator 202 through the second liquid natural gas pipeline 204. The liquid natural gas is forcibly evaporated into low-pressure gaseous fuel (gaseous fuel is natural gas, abbreviated as NG) in the low-pressure evaporator 202, and is transported to the low-pressure gas heater 203 through the first low-pressure NG gas pipeline 205. After being heated, the gaseous fuel is transported to the GVU unit 210 of the LNG ship generator 5 and the GVU unit 210 of the gas combustion device 6 through the second low-pressure NG gas pipeline 206, and is finally supplied to the LNG ship generator 5 and the gas combustion device 6.

[0033] The low-pressure gas phase natural gas supply pipeline is the low-pressure branch 201 of the high-pressure compressor 101. The inlet end of the low-pressure branch 201 is connected to the low-pressure outlet of the high-pressure compressor 101, and the outlet end of the low-pressure branch 201 is connected to the first low-pressure NG gas pipeline 205. The evaporated gas in each cargo hold 3 is transported to the evaporated gas pipeline 110 via the evaporated gas output main pipeline 303, and then fed into the high-pressure compressor 101. After being processed by the high-pressure compressor 101 at low pressure, it forms low-pressure gas phase fuel, which is then transported to the first low-pressure NG gas pipeline 205 via the low-pressure branch 201 of the high-pressure compressor 101. After being heated by the low-pressure gas heater 203, it is then supplied to the LNG ship generator 5 and the gas combustion device 6 via the second low-pressure NG gas pipeline 206.

[0034] The low-pressure gas supply pipeline for gaseous natural gas and the low-pressure gas supply pipeline for liquid natural gas share most of the pipelines, including the first low-pressure NG gas pipe 205, the low-pressure gas heater 203, and the second low-pressure NG gas pipe 206. This significantly saves pipeline layout space and equipment investment costs, and avoids resource waste caused by the repeated construction of independent pipeline systems. At the same time, the shared pipelines achieve redundant coordination between the two types of low-pressure gas sources in the transportation path, ensuring that the low-pressure gas transported from either the liquid or gas phase path undergoes a unified heating and control process, guaranteeing the consistency of gas parameters entering the generator and gas combustion device 6, and further improving the operational stability and economy of the low-pressure gas supply subsystem 2.

[0035] In this embodiment, an emergency pipeline 8 is also provided. The inlet end of the emergency pipeline 8 is connected to the evaporation gas pipeline 110, and the outlet end of the emergency pipeline 8 is connected to the first low-pressure NG gas pipeline 205. An emergency pipeline valve 801 is provided on the emergency pipeline 8. When the ship experiences an emergency situation such as the accumulation of evaporation gas (BOG) in cargo hold 3 causing an abnormal increase in tank pressure, or a failure of the high-pressure / low-pressure gas supply subsystem, and it is impossible to maintain tank pressure by normally draining the evaporation gas through conventional pipelines, i.e., in an emergency situation, the emergency pipeline valve 8 is opened. 01 and the fourth control valve 115 allow the natural evaporation gas in the cabin to flow freely, sequentially through the evaporation gas output branch pipe 302 and the evaporation gas output main pipe 303 into the evaporation gas pipeline 110, then through the evaporation gas pipeline 110 into the emergency pipeline 8, then through the emergency pipeline 8 into the first low-pressure NG gas pipeline 205, and finally through the first low-pressure NG gas pipeline 205 to the low-pressure gas heater 203. After being heated, it is supplied to the gas combustion unit (GCU) through the second low-pressure NG gas pipeline 206. In a specific embodiment, a first control valve 304 is provided on the low-pressure LNG fuel pipe 301 to control the on / off state and flow rate regulation of the liquid natural gas output from the cargo compartment 3 to the low-pressure LNG fuel pipe, thereby realizing the total source control of the high-pressure and low-pressure liquid phase gas supply paths. The liquid phase buffer natural gas pipe 107 is equipped with a second control valve 113 to regulate the flow rate and pressure of the liquid phase natural gas delivered from the buffer tank to the high pressure pump unit 103, thereby ensuring stable inlet conditions of the high pressure pump unit 103. A third control valve 114 is provided on the first high-pressure natural gas pipe 109 and at one end near the high-pressure power host 4 of the LNG ship to control the supply of high-pressure gaseous fuel from the liquid phase path to the high-pressure host, so as to facilitate independent maintenance or fault isolation of this path. The evaporation gas pipeline 110 is equipped with a fourth control valve 115 to control the on / off state and flow rate of the evaporation gas from the cargo compartment 3 into the high-pressure compressor 101, thereby achieving source control of the gas phase supply path. The second high-pressure natural gas pipeline 111 is equipped with a fifth control valve 116 to control the supply of high-temperature and high-pressure gaseous fuel output from the high-pressure compressor 101 to the high-pressure gas cooler 102, thereby ensuring the safe control of the cooling process. The third high-pressure natural gas pipeline 112 is equipped with a sixth control valve 117 to control the supply of cooled high-pressure gaseous fuel to the first high-pressure natural gas pipeline 109, thereby realizing independent regulation of the gas phase path gas supplied to the LNG ship's high-pressure power main engine 4. When this path needs maintenance or malfunctions, the gas phase gas supply can be cut off by closing this valve to avoid affecting the normal gas supply of the liquid phase path. At the same time, in conjunction with the third control valve, the two gas supply paths of the high-pressure main engine can be controlled and isolated separately to ensure the flexible switching and safe operation of the redundant system.

[0036] In a specific embodiment, a seventh control valve 207 is provided on the second liquid phase natural gas pipe 204 to control the on / off of the liquid phase natural gas supplied from the low-pressure LNG fuel pipe 301 to the low-pressure evaporator 202, thereby realizing independent switching control of the low-pressure liquid phase gas supply path, which facilitates the maintenance of this path or isolation when switching from the gas phase low-pressure path. The first low-pressure NG gas pipe 205 is provided with an eighth control valve 208, and the eighth control valve 208 is located on the side away from the low-pressure gas heater 203 at the connection between the low-pressure branch 201 and the first low-pressure NG gas pipe 205, so as to regulate the supply of gaseous fuel output from the low-pressure evaporator 202 to the low-pressure gas heater 203, ensuring the stable flow of gas entering the heating process, and at the same time, the gas source can be cut off when the heating unit is under maintenance. A ninth control valve 209 is provided on the second low-pressure NG gas pipe 206 and at one end near the LNG ship generator 5 and the gas combustion device 6 to control the supply of heated low-pressure gaseous fuel to the generator and the gas combustion device 6, thereby controlling the output of the low-pressure gas supply subsystem 2 and ensuring the safety of gas use for low-pressure equipment and the isolation requirements during system maintenance.

[0037] In a specific embodiment, a first gas valve assembly unit 118 is provided between the outlet end of the first high-pressure natural gas pipe 109 and the high-pressure power main engine 4 of the LNG ship. This assembly unit can regulate the pressure, control the flow, perform emergency shut-off, and detect leaks of the high-pressure gaseous fuel entering the high-pressure main engine, ensuring that the fuel parameters are adapted to the combustion requirements of the main engine. The first gas valve assembly unit 118 is connected to the high-pressure power main engine 4 of the LNG ship through a first high-pressure gas double-wall pipe 119, thereby ensuring the sealing and safety of the high-pressure gas during transportation. The double-wall pipe structure can detect leakage risks in a timely manner through interlayer monitoring, achieving dual safety protection for the transportation of high-pressure gas. A second gas valve assembly unit 210 is provided between the outlet end of the second low-pressure NG gas pipe 206 and the LNG ship generator 5, and between the outlet end of the second low-pressure NG gas pipe 206 and the gas combustion device 6. This unit can perform pressure adaptation, flow distribution, and safety cut-off of the gaseous fuel entering the low-pressure equipment, meeting the different operating conditions of the generator and the gas combustion device 6. The second gas valve assembly unit 210 is connected to the LNG ship generator 5 and the gas combustion device 6 through a second high-pressure gas double-wall pipe 211, thereby ensuring safe isolation during the low-pressure gas transmission process, preventing leaked gas from contacting the outside environment and causing risks, and achieving the safety protection of the low-pressure gas supply path and the explosion-proof requirements of the overall system.

[0038] In a specific embodiment, the pressure range of the gaseous fuel supplied to the high-pressure power host 4 of the LNG ship is 300-400 barg, that is, the pressure of the gaseous fuel in the first high-pressure natural gas pipe 109 and the third high-pressure natural gas pipe 112 is 300-400 barg. The pressure range of the gaseous fuel supplied to the LNG ship generator 5 and the gas combustion device 6 is 6-16 barg, that is, the pressure of the gaseous fuel in the first low-pressure NG gas pipe 205 is 6-16 barg. This pressure setting is adapted to the direct injection combustion requirements of the LNG ship's high-pressure main engine 4 cylinder and the low-pressure combustion system design of the LNG ship generator 5 and the gas combustion device 6, ensuring that the high-pressure main engine outputs sufficient propulsion power and the low-pressure equipment operates efficiently and stably. At the same time, the two pressure ranges are matched with the pressurization equipment (high-pressure pump unit 103, high-pressure compressor 101) and pipeline pressure-bearing capacity of the corresponding subsystems, avoiding equipment overpressure damage or combustion efficiency reduction due to pressure mismatch, and ensuring that the system operates safely and efficiently under the design parameters.

[0039] In addition, the system is equipped with conventional devices such as pressure sensors, temperature sensors, and flow sensors to monitor the temperature and pressure of each device, as well as the temperature, flow rate, and pressure of the fluid / substance in the pipeline. The control valves / valve installed in the supply system are all electrically controlled valves. The supply system can be equipped with a control system for automated control and monitoring. Since the above-mentioned devices, valves, and control systems are all conventional installations in the field and are not the inventive point of this solution, their specific principles will not be elaborated here.

[0040] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions 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 dual-phase redundant high-pressure main engine LNG ship gas supply system, characterized in that, The system includes a high-pressure gas supply subsystem (1) and a low-pressure gas supply subsystem (2) that share a high-pressure compressor (101) and are both designed with redundancy. The high-pressure gas supply subsystem (1) includes a high-pressure pump and evaporation unit, a high-pressure compressor (101) and a high-pressure gas cooler (102); the high-pressure gas supply subsystem can use the high-pressure pump and evaporation unit to pressurize and evaporate the liquid natural gas output from the cargo hold (3) into gaseous fuel to supply the high-pressure power main engine (4) of the LNG ship through redundant high-pressure gas supply pipeline components, or use the high-pressure compressor (101) to compress and pressurize the evaporated gas output from the cargo hold (3) and cool it through the high-pressure gas cooler (102) before supplying it to the high-pressure power main engine (4) of the LNG ship. The low-pressure gas supply subsystem (2) includes a low-pressure evaporation and heating unit and a low-pressure gas supply pipeline assembly; The low-pressure gas supply subsystem (2) can use the low-pressure evaporation and heating unit to force the liquid natural gas in the cargo hold (3) to evaporate into gaseous fuel and heat it before supplying it to the LNG ship generator (5) and gas combustion device (6) through the redundant low-pressure gas supply pipeline assembly, or use the high-pressure compressor (101) and the low-pressure branch (201) of the high-pressure compressor (101) to compress the natural evaporation gas exported from the cargo hold (3), and then heat the compressed evaporation gas through the heating function of the low-pressure evaporation and heating unit before supplying it to the LNG ship generator (5) and gas combustion device (6).

2. The dual-phase redundant high-pressure main engine LNG ship gas supply system according to claim 1, characterized in that, The high-pressure pump and evaporation unit include a high-pressure pump unit (103) and a high-pressure evaporator (104). The high-pressure pump unit (103) can pressurize the liquid natural gas output from the cargo compartment (3) and deliver it to the high-pressure evaporator (104). The high-pressure evaporator (104) can force liquid natural gas to evaporate into gaseous fuel to supply the high-pressure power engine (4) of the LNG ship.

3. The dual-phase redundant high-pressure main engine LNG ship gas supply system according to claim 2, characterized in that, The low-pressure evaporation and heating unit includes a low-pressure evaporator (202) and a low-pressure gas heater (203). The low-pressure evaporator (202) is used to force the liquid natural gas output from the cargo compartment (3) to evaporate into gaseous fuel and deliver it to the low-pressure gas heater (203). The low-pressure gas heater (203) is used to heat the gaseous fuel formed by the forced evaporation of the low-pressure evaporator (202) and deliver it to the LNG ship generator (5) and the gas combustion device (6).

4. The dual-phase redundant high-pressure main engine LNG ship gas supply system according to claim 3, characterized in that, The high-pressure gas supply subsystem (1) also includes a buffer tank (105) for buffering the liquid natural gas output from the cargo compartment (3) before it enters the high-pressure pump unit (103).

5. The dual-phase redundant high-pressure main engine LNG ship gas supply system according to claim 4, characterized in that, The redundant high-pressure gas supply pipeline assembly includes a liquid-phase natural gas high-pressure gas supply pipeline group and a gas-phase natural gas high-pressure gas supply pipeline group; the liquid-phase natural gas high-pressure gas supply pipeline group can transport the high-pressure gaseous fuel converted from the liquid-phase natural gas in the cargo tank (3) to the high-pressure power main engine (4) of the LNG ship; the gas-phase natural gas high-pressure gas supply pipeline group can transport the high-pressure gaseous fuel converted from the evaporated gas in the cargo tank (3) to the high-pressure power main engine (4) of the LNG ship. The high-pressure liquid phase natural gas supply pipeline assembly includes a first liquid phase natural gas pipeline (106), a liquid phase buffer natural gas pipeline (107), a high-pressure liquid phase natural gas pipeline (108), and a first high-pressure natural gas pipeline (109). The two ends of the first liquid phase natural gas pipeline (106) are respectively connected to the outlet end of the low-pressure LNG fuel pipeline (301) of the cargo hold (3) and the inlet end of the buffer tank (105); the two ends of the liquid phase buffer natural gas pipeline (107) are respectively connected to the outlet end of the buffer tank (105) and the inlet end of the high-pressure pump unit (103); the two ends of the high-pressure liquid phase natural gas pipeline (108) are respectively connected to the outlet end of the high-pressure pump unit (103) and the inlet end of the high-pressure evaporator (104); the two ends of the first high-pressure natural gas pipeline (109) are respectively connected to the outlet end of the high-pressure evaporator (104) and the high-pressure power main engine (4) of the LNG ship. The cargo hold (3) is equipped with a liquid natural gas fuel supply pump (7) for supplying its internal liquid natural gas to the low-pressure LNG fuel line (301). The gas phase natural gas high-pressure supply pipeline group includes an evaporation gas pipeline (110), a second high-pressure natural gas pipeline (111), and a third high-pressure natural gas pipeline (112); the two ends of the evaporation gas pipeline (110) are respectively connected to the evaporation gas output main pipeline (303) of the cargo compartment (3) and the inlet end of the high-pressure compressor (101); the two ends of the second high-pressure natural gas pipeline (111) are respectively connected to the high-pressure outlet end of the high-pressure compressor (101) and the inlet end of the high-pressure gas cooler (102); the two ends of the third high-pressure natural gas pipeline (112) are respectively connected to the outlet end of the high-pressure gas cooler (102) and the first high-pressure natural gas pipeline (109).

6. The dual-phase redundant high-pressure main engine LNG ship gas supply system according to claim 5, characterized in that, The redundant low-pressure gas supply pipeline assembly includes a liquid-phase natural gas low-pressure gas supply pipeline group and a gas-phase natural gas low-pressure gas supply pipeline; the liquid-phase natural gas low-pressure gas supply pipeline group can transport the low-pressure gaseous fuel converted from the liquid-phase natural gas in the cargo hold (3) to the LNG ship generator (5) and the gas combustion device (6); the gas-phase natural gas low-pressure gas supply pipeline can transport the low-pressure gaseous fuel converted from the evaporated gas in the cargo hold (3) to the LNG ship generator (5) and the gas combustion device (6). The liquid-phase natural gas low-pressure gas supply pipeline assembly includes a second liquid-phase natural gas pipeline (204), a first low-pressure NG gas pipeline (205), and a second low-pressure NG gas pipeline (206); the two ends of the second liquid-phase natural gas pipeline (204) are respectively connected to the outlet end of the low-pressure LNG fuel pipeline (301) and the inlet end of the low-pressure evaporator (202); the two ends of the first low-pressure NG gas pipeline (205) are respectively connected to the outlet end of the low-pressure evaporator (202) and the inlet end of the low-pressure gas heater (203); the two ends of the second low-pressure NG gas pipeline (206) are respectively connected to the outlet end of the low-pressure gas heater (203), the LNG ship generator (5), and the gas combustion device (6); The gas phase natural gas low-pressure supply pipeline is the low-pressure branch (201) of the high-pressure compressor (101), and the two ends of the low-pressure branch (201) are respectively connected to the low-pressure outlet of the high-pressure compressor (101) and the first low-pressure NG gas pipe (205).

7. The dual-phase redundant high-pressure main engine LNG ship gas supply system according to claim 5, characterized in that, The low-pressure LNG fuel pipe (301) is provided with a first control valve (304); the liquid phase buffer natural gas pipe (107) is provided with a second control valve (113); the first high-pressure natural gas pipe (109) is provided with a third control valve (114) at one end near the high-pressure power main engine (4) of the LNG ship; the evaporation gas pipe (110) is provided with a fourth control valve (115); the second high-pressure natural gas pipe (111) is provided with a fifth control valve (116); and the third high-pressure natural gas pipe (112) is provided with a sixth control valve (117).

8. The dual-phase redundant high-pressure main engine LNG ship gas supply system according to claim 6, characterized in that, The second liquid natural gas pipe (204) is provided with a seventh control valve (207); the first low-pressure NG gas pipe (205) is provided with an eighth control valve (208), and the eighth control valve (208) is located on the side away from the low-pressure gas heater (203) at the connection between the low-pressure branch (201) and the first low-pressure NG gas pipe (205); the second low-pressure NG gas pipe (206) is provided with a ninth control valve (209) at one end near the LNG ship generator (5) and the gas combustion device (6).

9. The dual-phase redundant high-pressure main engine LNG ship gas supply system according to claim 6, characterized in that, A first gas valve assembly unit (118) is provided between the outlet end of the first high-pressure natural gas pipe (109) and the high-pressure power host (4) of the LNG ship; a second gas valve assembly unit (210) is provided between the outlet end of the second low-pressure NG gas pipe (206) and the LNG ship generator (5) and between the outlet end of the second low-pressure NG gas pipe (206) and the gas combustion device (6).

10. The dual-phase redundant high-pressure main engine LNG ship gas supply system according to claim 1, characterized in that, The pressure range of the gaseous fuel supplied to the high-pressure power main engine (4) of the LNG ship is 300-400 barg; the pressure range of the gaseous fuel supplied to the generator (5) and gas combustion device (6) of the LNG ship is 6-16 barg.

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