CN219318208U - Marine LNG single fuel gas supply system - Google Patents

Abstract

The utility model discloses a marine LNG single-fuel gas supply system, which comprises a fuel cabin (1) arranged on a reinforced main deck, wherein the fuel cabin (1) is of a double-layer vacuum insulation structure, the left side of the fuel cabin (1) is a port fuel cabin joint (2) and the right side of the fuel cabin is a starboard fuel cabin joint (3), and the arrangement of all devices in the fuel cabin joint and the starboard fuel cabin joint are identical in connection mode. A liquid phase supplementing part, a gas phase conveying part and a ventilation part are arranged around the fuel cabin (1). The marine LNG single-fuel gas supply system is strictly designed and built according to relevant standard rules, has the functions of system initial starting, filling and discharging, fuel gas supply, dry dock maintenance, emergency treatment and the like, meets the supply of gasified fuel required by a large-tonnage multipurpose cargo ship, has a perfect emergency treatment mechanism, and ensures the marine transportation quality and the safety of staff.

Description

Marine LNG single fuel gas supply system

Technical Field

The utility model relates to the technical field of large-tonnage cargo ship single fuel host and generator fuel supply equipment, in particular to a marine LNG single fuel gas supply system.

Background

The natural gas single fuel host and the generator of the large-tonnage multipurpose cargo ship need to meet the temperature and pressure requirements and gas is used as fuel, and a set of LNG single fuel gas supply system special for the large-tonnage multipurpose cargo ship needs to be designed at present, so that low-temperature LNG is converted into fuel meeting the temperature and pressure requirements and is transmitted to the single fuel host and the generator for use. The design and the construction are in accordance with natural gas fuel power ship standards, steel ship construction standards and legal inspection guidelines of ships. The LNG single fuel gas supply system should realize the functions of operation before the system is started for the first time, filling and discharging operation, gas supply operation, operation before the dry dock maintenance, emergency operation and the like.

Disclosure of Invention

The utility model aims to solve the problem that a large-tonnage cargo ship lacks a set of reliable single fuel gas supply system which accords with related specifications.

In order to achieve the above purpose, the utility model provides a marine LNG single fuel supply system, which is characterized by comprising a fuel tank arranged on a reinforced main deck, wherein the fuel tank is of a double-layer vacuum insulation structure, the left side of the fuel tank is a sealed port fuel tank joint, and the right side of the fuel tank is a sealed starboard fuel tank joint; a liquid phase supplementing part, a gas phase conveying part and a ventilation part are arranged around the fuel cabin.

The liquid phase supplementing part comprises: and the liquid filling port in the filling station is used for respectively conveying LNG to a spray pipe arranged at the upper part of the fuel cabin and a liquid inlet pipe in a liquid inlet and outlet main pipe at the lower part of the fuel cabin through a liquid phase pipeline. The liquid phase pipeline is provided with a first valve at a part close to the filling station, a second valve at a part which is led into the spray pipe, a third valve at a part which is connected with the liquid inlet and outlet main pipe, and a fourth valve at the liquid inlet and outlet main pipe.

The gas phase conveying section includes: the top of the fuel cabin is connected with a return air port in the filling station through a gas phase pipeline; and a fifth valve, a sixth valve and a seventh valve are sequentially arranged in the direction of the gas phase pipeline leading to the gas return port. The filling station is also provided with a first nitrogen purging pipeline which is respectively connected into a liquid phase pipeline from the liquid filling port to the fuel cabin and a pipeline from the air return port to the top of the fuel cabin; a first check valve is arranged on the way from the first nitrogen purging pipeline to the liquid phase pipeline of the fuel tank, and a second check valve is arranged on the way from the first nitrogen purging pipeline to the return air port to the pipeline at the top of the fuel tank.

Two liquid outlet pipes in a liquid inlet and outlet main pipe at the lower part of the fuel tank are respectively connected with two independent pipe passes of a gasification heater positioned in a joint of the starboard fuel tank, wherein materials in one independent pipe pass are gasified and then are connected to a gas return pipe at the top of the right side of the fuel tank, so that the pressure of the fuel tank is balanced, and the gasified materials in the other independent pipe pass are introduced into a buffer tank, and at least one gas supply pipe is arranged on the buffer tank to supply gas for the starboard fuel tank; an eighth valve and a ninth valve are respectively arranged on the two liquid outlet pipes; the independent tube pass is connected to a position between the fifth valve and the sixth valve of the muffler through a pipeline provided with a tenth valve.

The inlet and the outlet of the shell side of the gasification heater are respectively connected with a water inlet pipeline and a water outlet pipeline in an LNG heating water system of the starboard cabin; the gas supply pipe is connected with a second nitrogen purging pipeline for purging the gas supply pipe before and after gas supply. And hand valves are respectively arranged on the water inlet and outlet pipelines of the LNG heating water system of the starboard cabin and the pipeline of the second nitrogen purging pipeline after the second valve, before the first check valve and before the second check valve.

The breathable portion includes: the upper part of the buffer tank is connected with an exhaust main pipe discharged to an onshore receiving device through an exhaust pipeline and is used for pressure relief of the buffer tank; the top of the fuel cabin and the air return pipe of the gasification heater are connected to the exhaust manifold through an exhaust pipeline for pressure relief of the fuel cabin and the gasification heater; the liquid phase pipeline of the liquid adding port is connected to the exhaust manifold in front of the valve of the first valve and is used for purging and deflating; safety valves are respectively arranged on the exhaust pipes of the ventilation part. The upper part and the side of the inner wall of the starboard fuel tank joint on the right side are respectively provided with a ventilation inlet and a ventilation outlet for ventilation before workers enter the tank. The arrangement of all the devices in the port fuel tank joint and the connection mode among the devices are identical to the arrangement of all the devices in the starboard fuel tank joint on the right side and the connection mode among the devices.

Preferably, a conical filter screen is arranged in a liquid phase pipeline from a liquid filling port in the filling station to the fuel tank, drip trays are arranged at the lower parts of the liquid filling port and the air return port, and the bottoms and high liquid level parts of the drip trays are connected with outboard discharge pipelines; and a water curtain connected with fire water is also arranged at the upper part of the filling station.

Preferably, the fuel tank is provided with a first temperature sensor, a liquid level sensor and a first pressure sensor.

Preferably, a second temperature sensor and a second pressure sensor are arranged on an outlet pipeline of an independent tube side of the gasification heater which is led into the buffer tank, and a third temperature sensor is arranged on an outlet pipeline of a shell side of the gasification heater.

Preferably, the top of the inner wall of the starboard fuel tank joint and the top of the inner wall of the port fuel tank joint are respectively provided with a combustible gas probe and a fire probe.

Preferably, the meteorological pipeline of the fuel cabin is further provided with a branch pipeline, the branch pipeline is connected to a pipe section of the liquid outlet pipe with the eighth valve before entering the gasification heater, and the branch pipeline is provided with an eleventh valve.

The marine LNG single-fuel gas supply system is strictly designed and built according to relevant standard rules, has the functions of system initial starting, filling and discharging, fuel gas supply, dry dock maintenance, emergency treatment and the like, meets the supply of gasified fuel required by a large-tonnage multipurpose cargo ship, has a perfect emergency treatment mechanism, and ensures the marine transportation quality and the safety of staff.

Drawings

Fig. 1 is a general flow chart of a marine LNG single fuel supply system according to the present utility model.

Fig. 2 is a schematic diagram of a front view structure of the marine LNG single fuel supply system according to the present utility model.

Fig. 3 is a perspective view of a port and starboard fuel tank joint in the marine LNG single fuel supply system according to the present utility model.

Fig. 4 is a schematic top view of the marine LNG single fuel supply system according to the present utility model, after being seen through the port and starboard fuel tank joints.

Fig. 5 is a schematic left-view structural diagram of a ship LNG single fuel supply system according to the present utility model, after a perspective view of a port and starboard fuel tank joint.

Fig. 6 is a schematic diagram of a right-hand view structure of a ship LNG single fuel supply system according to the present utility model, after a perspective view of a port and starboard fuel tank joint.

Fig. 7 is a flow chart of a ventilation part in the marine LNG single fuel supply system according to the present utility model.

Fig. 8 is a flow chart of the first nitrogen purge line supply in the marine LNG single fuel supply system according to the present utility model.

Fig. 9 is a flow chart of the liquid level and pressure control of the fuel tanks in the marine LNG single fuel supply system according to the present utility model.

Fig. 10 is a flow chart of materials in a fuel tank to a host and a generator in the marine LNG single fuel supply system according to the present utility model.

Wherein: 1. the fuel tank, 2, port fuel tank joint, 3, starboard fuel tank joint, 4, liquid adding port, 5, spray pipe, 6, liquid inlet and outlet header, 7, gasification heater, 8, independent tube side, 9, return pipe, 10, buffer tank, 11, gas supply pipe, 12, gas outlet header, 13, filling station, 14, return port, 15, drip tray, 16, water curtain, 17, first nitrogen purge line, 18, combustible gas probe, 19, fire probe, 20, first valve, 21, second valve, 22, third valve, 23, fourth valve, 24, fifth valve, 25, sixth valve, 26, seventh valve, 27, first check valve, 28, second check valve, 29, eighth valve, 30, ninth valve, 31, tenth valve, 32, second nitrogen purge line, 33, eleventh valve, 34, twelfth valve, 35, thirteenth valve, 36, fourteenth valve.

Detailed Description

The marine LNG single fuel gas supply system is specially designed and manufactured for the large-tonnage multi-purpose cargo ship, strictly obeys the liquefied natural gas fuel cabin and is a fuel supply system capable of meeting gasification fuel required by the large-tonnage multi-purpose cargo ship according to related standard rules, the filling and the discharging of gas and liquid fuel and the stable supply of fuel gas are facilitated, and the marine LNG single fuel gas supply system also has a dry dock maintenance and an emergency treatment mechanism when leakage occurs, so that the stable and safe operation of the ship is ensured.

Examples:

as shown in fig. 2 to 6, the marine LNG single fuel supply system comprises a fuel tank 1 installed on a reinforced main deck, wherein the fuel tank 1 has a double-layer vacuum insulation structure, the left side of the fuel tank 1 is a closed port fuel tank joint 2, and the right side of the fuel tank 1 is a closed starboard fuel tank joint 3; the fuel tank 1 is a C-type independent fuel tank. The fuel tank 1 is mounted on a reinforced main deck, and the top of the inner wall of the starboard fuel tank joint 3 and the top of the inner wall of the port fuel tank joint 2 are respectively provided with a combustible gas probe 18 and a fire probe 19. Around the fuel tank 1, a liquid phase replenishing portion, a gas phase transporting portion, and a gas permeable portion are provided.

The liquid phase supplementing part comprises:

as shown in fig. 1 and 7, the liquid filling port 4 in the filling station 13 is configured to convey LNG through a liquid phase pipeline to a liquid inlet pipe in the liquid inlet/outlet manifold 6 at the lower part of the fuel tank 1, in the shower pipe 5 provided at the upper part of the fuel tank 1. The liquid phase pipeline is provided with a first valve 20, namely VP101S, at a part close to the filling station 13, a second valve 21, namely VP206S, at a part which is communicated with the spray pipe 5, a third valve 22, namely VP207S, at a part which is communicated with the liquid inlet and outlet main pipe 6, and a fourth valve 23, namely VM201S, at the liquid inlet and outlet main pipe 6. A conical filter FI101S is arranged in the liquid phase pipeline from the filling opening 4 in the filling station 13 to the fuel tank 1, and is used for filtering impurities. The lower parts of the liquid adding port 4 and the air return port 14 are provided with a drip tray 15 for receiving liquid leakage. The bottom and the high liquid level of the drip tray 15 are both connected with an outboard relief line, and a hand valve VM107S is arranged on the relief line; a water curtain 16 for fire protection water is also provided in the upper part of the filling station 13 for fire protection.

The gas phase conveying section includes: the top of the fuel tank 1 is connected with a return air port 14 in the filling station 13 through a gas phase pipeline; a fifth valve 24, namely VM202S, a sixth valve 25, namely VP208S, and a seventh valve 26, namely VP102S, are sequentially arranged in the direction of the gas-phase pipeline leading to the return port 14; as shown in fig. 8, a first nitrogen purging pipeline 17 is further provided in the filling station 13, and is respectively connected to the liquid phase pipeline from the filling port 4 to the fuel tank 1 and the pipeline from the return port 14 to the top of the fuel tank 1; a hand valve VM101S and a first check valve 27 (VC 101S and VC 102S) are provided on the way from the first nitrogen purge line 17 to the liquid phase line of the fuel tank 1, and a hand valve VM104S and a second check valve 28 (VC 103S and VC 104S) are provided on the way from the first nitrogen purge line 17 to the return air port 14 to the line at the top of the fuel tank 1.

As shown in fig. 1 and 10, two liquid outlet pipes in the liquid inlet and outlet header pipe 6 at the lower part of the fuel tank 1 are respectively connected with two independent pipe passes 8 of the gasification heater 7 (E202S) located in the starboard fuel tank joint 3, wherein the material in one independent pipe pass 8 is gasified and then is connected to the air return pipe 9 at the top of the right side of the fuel tank 1, so as to balance the pressure of the fuel tank 1, the gasified material in the other independent pipe pass 8 is introduced into the buffer tank 10, at least one air supply pipe 11 is arranged on the buffer tank 10 to supply air for the starboard fuel tank, and a twelfth valve 34 is arranged on the air supply pipe 11. As shown in fig. 1, two of the air supply pipes 11 are provided on the surge tank 10 in the starboard fuel tank joint 3, one of which is supplied to the main engine as fuel through the hand valve VM205S and the VP205S in the twelfth valve 34, and the other of which is supplied to the auxiliary engine as fuel through the hand valve VM213S and the VP213S in the twelfth valve 34.

The eighth valve 29 and the ninth valve 30 are respectively arranged on the two liquid outlet pipes; the independent tube side 8 is linked to a position between the fifth valve 24 and the sixth valve 25 of the muffler 9 through a pipe provided with a tenth valve 31. The inlet and the outlet of the shell side of the gasification heater 7 are respectively connected with a water inlet pipeline and a water outlet pipeline in an LNG heating water system of the starboard cabin; and the system is used for heating LNG in the two independent tube passes 8 of the gasification heater 7, and finally NG is formed and supplied to a natural gas single fuel host machine and a generator to be used as fuel. The meteorological pipeline of the fuel cabin 1 is further provided with a branch pipeline which is connected to a pipe section of the liquid outlet pipe with the eighth valve 29 before entering the gasification heater 7, and the branch pipeline is provided with an eleventh valve 33; when the pressure in the fuel tank 1 is too high, the vaporized gas in the tank can flow into the gasification heater 7 for heating and then directly burn through the action of the pressure in the tank, so that the overpressure of the fuel tank is prevented, and the BOG emission is avoided under the normal operation. The gas supply pipe 11 is connected with a second nitrogen purging pipeline 32 for purging the gas supply pipe 11 before and after gas supply; the second valve 21, namely, the valve back of VP206S, the first check valve 27, namely, the valve front of VC101S and VC102S, the second check valve 28, namely, the valve front of VC103S and VC104S, and the hand valves on the water inlet and outlet pipelines of the LNG heating water system of the starboard cabin and the pipeline of the second nitrogen purging pipeline 32 are respectively provided, and the corresponding labels of each hand valve are VM206S, VM101S, VM104S, VM291S, VM292S, VM203S and VM204S; wherein, the pipeline of the second nitrogen purging pipeline 32 has two paths, the VM203S and the VM204S are respectively arranged on one path, the path with the VM203S is also provided with check valves VC203S and VC204S after the valve, and the path with the VM204S is also provided with check valves VC201S and VC204S after the valve.

As shown in fig. 7, the ventilation part includes: the upper part of the buffer tank 10 is connected with an exhaust manifold 12 discharged to an onshore receiving device through an exhaust pipeline for pressure relief of the buffer tank 10; the exhaust line is provided with a fourteenth valve 36, i.e. VP210S. A normally open hand valve VM210S and a normally closed thirteenth valve 35, namely VP209S, which is opened in an emergency state are arranged on an exhaust pipe at the top of the fuel tank 1; the return air pipes 9 of the gasification heater 7 are also connected to the exhaust manifold 12 via exhaust lines for pressure relief of the fuel tank 1 and the gasification heater 7. The liquid phase pipeline of the liquid filling port 4 is connected to the exhaust manifold 12 before the valve of the first valve 20, namely the valve of the VP101S, and is used for purging and deflating. Safety valves are respectively arranged on the exhaust pipes of the ventilation part, pressure relief is carried out under the emergency condition that the pressure of each exhaust pipe exceeds the limit, the safety valves are basically arranged, and the reference numerals are specifically shown in fig. 1 and 2. The outlet pipeline of the independent tube side 8 of the gasification heater 7 which is led into the buffer tank 10 is provided with a second temperature sensor 7.1, namely TT203S, and a second pressure sensor 7.2, namely PT203S and PT202S, and the outlet pipeline of the gasification heater 7, namely E202S shell side is provided with a third temperature sensor 7.3, namely TT601S.

The right side is the inner wall of starboard fuel tank joint 3, and upper portion and side still have set up respectively and have ventilated import, export that ventilates for before the staff gets into the cabin ventilation. The arrangement of all the devices and the connection mode among the devices in the port fuel tank joint 2 are identical to the arrangement of all the devices and the connection mode among the devices in the starboard fuel tank joint 3 on the right side.

As shown in fig. 9, the fuel tank 1 is provided with a first temperature sensor 1.1, i.e., TT205, a liquid level sensor 1.2 (i.e., a high liquid level sensor DPLT201 and a low liquid level sensor DPLT 202), and a first pressure sensor 1.3 (i.e., PT201P and PT 204P). The first temperature sensor 1.1 is a tank LNG overflow alarm temperature sensor, and is disposed between the fuel tank 1 and a fifth valve 24 on the muffler 9, and is used for overflow alarm of the fuel tank 1.

The equipment names and models represented by the part numbers of the parts in fig. 1 are set forth in tables 1 to 6 below (where the parts representing the starboard fuel tank joint are denoted by the suffix S and the parts representing the port fuel tank joint are denoted by the suffix P):

because some parts in tables 1 to 6 are in the prior art, and with reference to the installation positions of each part shown in fig. 1 to 9, a person skilled in the art can clearly know the positions and connection modes of each part, so the parts are listed in a list form in this embodiment, and will not be described in detail.

The operation method of the utility model comprises the following steps:

1. operation of system before initial start-up

1.1 drying & inertization

The purpose of this operation is to remove the wet air and oxygen from the fuel tanks, process equipment and piping using dry nitrogen, the wet air being purged to prevent icing and oxygen purging within the system, and to prevent an explosive environment from forming within the system.

The nitrogen used in the process is supplied by the tank car and is supplied to the system in the form of liquid nitrogen vaporized by the vaporized gas (low dew point, low oxygen content). When the oxygen content value and dew point in the system are monitored to meet the requirements, the operation is ended.

1.2 precooling

After the fuel tank is dried and inerted, the fuel tank is pre-cooled before the first filling, so that the stress generated by low temperature is reduced to the greatest extent. The precooling operation is carried out by providing liquid nitrogen by the tank truck, and the liquid nitrogen enters the fuel tank through the bottom filling pipeline and the top spraying pipeline, and a temperature sensor arranged in the fuel tank can provide temperature data of the fuel tank in real time, and the precooling speed is controlled within 10 ℃/h. When the average temperature of the storage tank is lower than-150 ℃, the precooling operation is ended.

1.3 dispelling Qi

After the inerting precooling, the fuel tank and the pipeline are filled with nitrogen, and the nitrogen needs to be replaced by low-temperature natural gas before the first filling. Cryogenic natural gas may be provided by a tank car and is produced from liquefied natural gas by vaporization through an air temperature vaporizer. And in the process of purging, the gas in the cabin is sampled through the sampling port so as to confirm whether the purging operation can be finished.

1.4 filling and line bleed

(1) Liquefied natural gas filling

The fuel tanks may receive liquefied natural gas from tankers, shore-based tankers and tank cars. Liquefied natural gas can enter the fuel tank from the bottom and top filling lines simultaneously to inhibit stratification and tumbling of the liquid and to regulate the pressure of the fuel tank during filling. If a filling ship or shore-based filling facility is used, the return line should be connected to the filling facility.

(2) Bleed operation

After filling, the liquid in the filling line may be vented into the fuel tank or purged to the filling side with nitrogen.

2 gas supply

The gas supply line, valves, meters can be set in an automatic mode and a manual mode.

2.1 forced vaporization gas supply

Liquefied natural gas in the fuel tank flows to the vaporization heater under the action of pressure in the tank, and is supplied to downstream gas equipment for combustion after vaporization heating.

2.2 vapor treatment

When the pressure in the fuel tank is too high, the evaporation gas in the tank can flow into the evaporation heater to be heated through the action of the pressure in the tank, so that the fuel tank is directly burnt, the overpressure is prevented, and the BOG emission is avoided under the normal operation.

3 dry dock pre-repair operations

3.1 Fuel tank emptying

The fuel tanks need to be emptied of liquid prior to the docking maintenance of the vessel. The fuel tank may be pressurized by a vaporization heater and the liquid in the tank may be discharged to an onshore receiving means by a differential pressure method.

3.2 warm cabin & inerting

Nitrogen at normal temperature enters the bottom of the fuel cabin through a liquid phase filling pipeline, residual LNG in the cabin can be evaporated in the process, and mixed gas is discharged to an onshore receiving device through a cabin top gas item pipeline. The temperature sensor arranged in the cabin displays the temperature in the cabin in real time, and samples are taken at the sampling port to determine the components of the gas in the cabin.

3.3 ventilation

Ventilation is required before the fuel tanks are opened to ensure that the environment within the tanks allows personnel access.

4 Emergency operation

4.1 Emergency cut-off

The emergency cut-off system has the following functions:

the associated valve is closed and the associated equipment within the system is shut off. In order to ensure the safe operation of the air supply system, the emergency cut-off system can be automatically cut off through a system instrument or can be manually cut off remotely.

5 fuel tank evacuation

If the fuel tank structure is damaged, the liquid in the tank can be discharged to an onshore receiving device by a differential pressure method until all the liquid is discharged.

The foregoing is only a preferred embodiment of the present utility model, but the scope of the present utility model is not limited thereto, and any person skilled in the art, who is within the scope of the present utility model, should be covered by the protection scope of the present utility model by making equivalents and modifications to the technical solution and the inventive concept thereof.

Claims (6)

1. The marine LNG single-fuel gas supply system is characterized by comprising a fuel cabin (1) arranged on a reinforced main deck, wherein the fuel cabin (1) is of a double-layer vacuum insulation structure, the left side of the fuel cabin (1) is a sealed port fuel cabin joint (2) and the right side of the fuel cabin is a sealed starboard fuel cabin joint (3); a liquid phase supplementing part, a gas phase conveying part and a ventilation part are arranged around the fuel cabin (1);

the liquid phase supplementing part comprises: a liquid adding port (4) in a filling station (13) respectively conveys LNG to a spray pipe (5) arranged at the upper part of the fuel cabin (1) and a liquid inlet pipe in a liquid inlet and outlet main pipe (6) at the lower part of the fuel cabin (1) through a liquid phase pipeline;

the liquid phase pipeline is provided with a first valve (20) at a part close to the filling station (13), a second valve (21) at a part which is communicated with the spray pipe (5), a third valve (22) at a part which is connected with the liquid inlet and outlet main pipe (6), and a fourth valve (23) at the liquid inlet and outlet main pipe (6);

the gas phase conveying section includes: the top of the fuel cabin (1) is connected with a return air port (14) in the filling station (13) through a gas phase pipeline; a fifth valve (24), a sixth valve (25) and a seventh valve (26) are sequentially arranged in the direction of the gas phase pipeline leading to the gas return port (14); a first nitrogen purging pipeline (17) is further arranged in the filling station (13), and is respectively connected into a liquid phase pipeline from the liquid filling port (4) to the fuel tank (1) and a pipeline from the air return port (14) to the top of the fuel tank (1); a first check valve (27) is arranged on the way from the first nitrogen purging pipeline (17) to the liquid phase pipeline of the fuel cabin (1), and a second check valve (28) is arranged on the way from the first nitrogen purging pipeline (17) to the air return port (14) to the pipeline at the top of the fuel cabin (1);

two liquid outlet pipes in a liquid inlet and outlet main pipe (6) at the lower part of the fuel tank (1) are respectively connected with two independent pipe passes (8) of a gasification heater (7) positioned in a starboard fuel tank joint (3), materials in one independent pipe pass (8) are gasified and then are connected to an air return pipe (9) at the top of the right side of the fuel tank (1), the materials are used for balancing the pressure of the fuel tank (1), and the gasified materials in the other independent pipe pass (8) are introduced into a buffer tank (10) and are supplied to the starboard fuel tank through at least one air supply pipe (11) arranged on the buffer tank (10); an eighth valve (29) and a ninth valve (30) are respectively arranged on the two liquid outlet pipes; the independent tube side (8) is connected to a position between the fifth valve (24) and the sixth valve (25) of the air return tube (9) through a pipeline provided with a tenth valve (31);

the inlet and the outlet of the shell side of the gasification heater (7) are respectively connected with a water inlet pipeline and a water outlet pipeline in an LNG heating water system of the starboard cabin;

the gas supply pipe (11) is connected with a second nitrogen purging pipeline (32) for purging the gas supply pipe (11) before and after gas supply;

hand valves are respectively arranged behind the second valve (21), in front of the first check valve (27), in front of the second check valve (28), on the water inlet and outlet pipelines of the LNG heating water system of the starboard cabin and on the pipeline of the second nitrogen purging pipeline (32);

the breathable portion includes: the upper part of the buffer tank (10) is connected with an exhaust manifold (12) discharged to an onshore receiving device through an exhaust pipeline and is used for pressure relief of the buffer tank (10); the top of the fuel cabin (1) and the air return pipe (9) of the gasification heater (7) are connected to the exhaust manifold (12) through an exhaust pipeline for pressure relief of the fuel cabin (1) and the gasification heater (7); the liquid phase pipeline of the liquid adding port (4) is connected to the exhaust manifold (12) in front of the valve of the first valve (20) for purging and deflating; safety valves are respectively arranged on the exhaust pipelines of the ventilation part;

the upper part and the side of the inner wall of the starboard fuel tank joint (3) on the right side are respectively provided with a ventilation inlet and a ventilation outlet for ventilation before workers enter the tank;

the arrangement of all the devices and the connection mode among the devices in the port fuel tank joint (2) are identical to the arrangement of all the devices and the connection mode among the devices in the starboard fuel tank joint (3) on the right side.

2. Marine LNG single fuel supply system according to claim 1, characterized in that a conical filter screen is arranged in the liquid phase pipeline from the filling port (4) in the filling station (13) to the fuel tank (1), a drip tray (15) is arranged at the lower parts of the filling port (4) and the return air port (14), and the bottom and the high liquid level of the drip tray (15) are both connected with an outboard drain pipeline; a water curtain (16) for connecting fire water is also arranged at the upper part of the filling station (13).

3. Marine LNG single fuel supply system according to claim 1, characterized in that the fuel tank (1) is provided with a first temperature sensor (1.1), a liquid level sensor (1.2) and a first pressure sensor (1.3).

4. Marine LNG single fuel supply system according to claim 1, characterized in that a second temperature sensor (7.1) and a second pressure sensor (7.2) are provided on the outlet line of the separate tube side (8) of the vaporizing heater (7) leading into the buffer tank (10), and that a third temperature sensor (7.3) is provided on the outlet line of the shell side of the vaporizing heater (7).

5. Marine LNG single fuel supply system according to claim 1, characterized in that the top of the inner wall of the starboard fuel tank joint (3) and the top of the inner wall of the port fuel tank joint (2) are provided with a combustible gas probe (18) and a fire probe (19), respectively.

6. Marine LNG single fuel supply system according to claim 1, characterized in that the meteorological line of the fuel tank (1) is further provided with a branch line, which branch line is connected to the pipe section before the outflow pipe with the eighth valve (29) enters the vaporizing heater (7), and that the branch line is provided with an eleventh valve (33).

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