Operation device for recycling and quickly discharging liquid by utilizing BOG (Boil Off Gas)

Abstract

The utility model provides an operation device for recycling and quickly discharging liquid by utilizing BOG (boil-off gas), which comprises a plurality of liquid discharging pries arranged in parallel, and the plurality of liquid discharging pries are connected through flat pressing pipelines; each liquid unloading pry comprises a gasifier used for gasifying LNG, a pressurizing liquid outlet pipeline connected with a liquid inlet of the gasifier, a first gas phase pipeline connected with a gas outlet of the gasifier and a second gas phase pipeline used for conveying BOG, and the second gas phase pipeline passes through a first manual valve and then is divided into a first branch pipe to be connected with the flat pressing pipeline. According to the operation device for rapidly discharging the liquid through BOG recovery, the gasification pressurization time is shortened, the liquid discharging efficiency of an LNG storage and distribution station is improved, and the risk of explosion caused when residual BOG natural gas in a storage tank vehicle is emptied on site is reduced.

Description

Technical Field

[0001] The utility model belongs to the field of liquefied natural gas, and in particular relates to an operating device for rapidly unloading liquid by utilizing BOG recovery. Background Art

[0002] Liquefied natural gas (LNG) is a cryogenic liquid primarily composed of methane, characterized by cleanliness, efficiency, and safety. LNG is produced by liquefying purified natural gas at extremely low temperatures (approximately -162°C). Maritime transport is a method of international LNG trade, particularly suitable for transoceanic or long-distance international transport. Maritime transport offers the advantages of large capacity and low costs. LNG is typically transported from receiving terminals to storage stations via LNG tankers. LNG tankers are used for ground transportation and are a crucial tool for connecting gas sources and users, storing LNG in tanker tanks for transfer. In existing technologies, after unloading LNG tankers, the pressurized BOG (gasified natural gas) remaining in the tankers is vented on-site, preventing efficient utilization and resulting in resource waste. Furthermore, existing unloading skid-type gasification devices operate independently and are disorganized, resulting in long gasification and pressurization times and slow unloading speeds, making them unable to meet gas supply requirements during peak gas demand seasons. Utility Model Content

[0003] In view of the above existing problems, the utility model provides an operating device for rapid liquid unloading by recovering BOG, which shortens the gasification and pressurization time, can recycle the BOG natural gas remaining in the tank truck storage tank, and at the same time reduces the risk of explosion when the BOG natural gas remaining in the tank truck is vented on site.

[0004] The technical solutions adopted in this utility model are as follows:

[0005] A device for rapid liquid unloading utilizing BOG recovery comprises a plurality of liquid unloading skids arranged in parallel, connected to each other via a surge pipe. Each liquid unloading skid comprises a vaporizer for vaporizing LNG, a pressurized liquid outlet pipe connected to the liquid inlet of the vaporizer, a first gas phase pipe connected to the gas outlet of the vaporizer, and a second gas phase pipe for conveying BOG gas. The second gas phase pipe branches off into a first branch pipe after passing through a first manual valve and is connected to the surge pipe. The liquid unloading skid is arranged on a base.

[0006] Furthermore, the liquid unloading skid also includes a liquid unloading pipeline for transporting LNG. The liquid unloading pipeline is provided with an LNG inlet and an LNG outlet. The LNG inlet is connected to the liquid unloading port of the tank truck via a first hose, and the LNG outlet is connected to the LNG storage system pipeline of the station.

[0007] Furthermore, a second manual valve and a third manual valve are sequentially provided on the unloading pipeline along the LNG transportation direction. Preferably, the second manual valve is provided on the unloading pipeline near the LNG inlet, and the third manual valve is provided on the unloading pipeline near the LNG outlet. A second branch pipe is branched off from the unloading pipeline between the second manual valve and the third manual valve. A first vent valve is provided on the second branch pipe. The first vent valve protects the unloading pipeline from overpressure. The first vent valve is opened when the pressure in the unloading pipeline exceeds a safe value during unloading or when residual liquid or BOG gas in the unloading pipeline or unloading skid needs to be discharged after unloading is completed.

[0008] Furthermore, a pressurized liquid phase inlet is provided at one end of the pressurized liquid outlet pipe away from the gasifier, and the pressurized liquid phase inlet is connected to the pressurized liquid phase outlet of the tank truck via a second hose.

[0009] Furthermore, a fourth manual valve is provided on the pressurized liquid outlet pipeline. A third branch is branched off from the pressurized liquid outlet pipeline between the fourth valve and the vaporizer. A second vent valve is provided on the third branch. The second vent valve is used to protect the pressurized liquid outlet pipeline from overpressure. The second vent valve is opened in the following two situations: ① When the pressure of the pressurized liquid outlet pipeline exceeds the safety value during the liquid unloading process; ② When the residual liquid or BOG gas in the pressurized liquid outlet pipeline or the liquid unloading skid needs to be discharged after the liquid unloading is completed. The pressurized liquid outlet pipeline is used to transport LNG to the vaporizer for gasification in the initial state.

[0010] Furthermore, a pressure-equalizing valve is provided on the first branch pipe.

[0011] Furthermore, the second gas-phase pipeline has a BOG inlet at one end and a BOG outlet at the other. The BOG inlet is connected to the tank truck's BOG port via a third hose, while the BOG outlet is connected to the station's BOG system pipeline. A fourth branch is branched from the second gas-phase pipeline between the first manual valve and the first branch, and a third vent valve is installed on the fourth branch. The third vent valve protects the second gas-phase pipeline from overpressure and is opened in the following two situations: ① When the pressure in the second gas-phase pipeline exceeds a safe level during liquid unloading; ② After liquid unloading is completed, residual liquid or BOG gas needs to be discharged from the second gas-phase pipeline or the liquid unloading skid.

[0012] Furthermore, the first gas phase pipeline merges with the downstream pipeline at the location where the second gas phase pipeline branches off the first branch, and then is connected to the station BOG system pipeline. A fifth manual valve is provided on the second gas phase pipeline downstream of the first gas phase pipeline.

[0013] Furthermore, a fifth branch is branched from the first gas phase pipeline, which is equipped with a fourth vent valve. This fourth vent valve protects the first gas phase pipeline from overpressure and is opened in the following two situations: 1) when the pressure in the first gas phase pipeline exceeds a safe value during liquid unloading; 2) when residual liquid or BOG gas needs to be discharged from the first gas phase pipeline or the liquid unloading skid after liquid unloading is completed.

[0014] Furthermore, all the liquid unloading skids are connected to the flat-pressure pipeline through the first branch pipe.

[0015] Furthermore, the second branch pipe, the third branch pipe, the fourth branch pipe, and the fifth branch pipe are all connected to the station BOG system.

[0016] The working principle of the utility model's BOG recovery and rapid liquid unloading device is as follows:

[0017] Taking two parallel liquid unloading skids as an example, the two liquid unloading skids are respectively the first liquid unloading skid and the second liquid unloading skid. Before use, all valves of the operating device for rapid liquid unloading using BOG recovery described in the utility model are in a closed state.

[0018] After unloading, the transport tank truck becomes a light truck. The tank tank of the light truck contains BOG (pressure, for example, about 0.7 MPa). The tank truck that has not unloaded liquid is a heavy truck. The tank tank of the heavy truck contains LNG and a small amount of BOG at about 0.1 MPa. The BOG inlet of the first unloading skid is connected to the BOG port of the light truck, the BOG inlet of the second unloading skid is connected to the BOG port of the heavy truck, the pressurized liquid phase inlet of the second unloading skid is connected to the pressurized liquid phase outlet of the heavy truck, and the LNG inlet of the second unloading skid is connected to the unloading port of the heavy truck. Simultaneously, the first manual valves and pressure relief valves of the first and second unloading skids are opened to connect the light and heavy trucks and disconnect them from the terminal BOG system. The higher-pressure BOG in the light truck continuously flows to the heavy truck through the branch pipe, squeezing the LNG in the heavy truck out of the tank truck tank, speeding up the tank truck unloading. When the BOG pressures in the heavy and light trucks are roughly the same, the first manual valve and pressure relief valve of the second unloading skid are closed, and the first manual valve of the first unloading skid is closed. The equalizing pressure valve enters the heavy vehicle unloading process. The heavy vehicle unloading process includes: opening the fourth manual valve of the second unloading skid to transfer the LNG in the heavy vehicle to the vaporizer of the second unloading skid for vaporization. After the vaporization reaches a certain pressure, the first manual valve of the second unloading skid is opened to continuously vaporize and pressurize the heavy vehicle LNG storage tank. After the liquid delivery pressure requirement is reached, the second and third manual valves of the second unloading skid are opened. During the unloading process, it is necessary to observe and dynamically adjust the BOG pressure to maintain pressure stability and ensure rapid unloading. If the liquid delivery pressure decreases during unloading, the opening of the first manual valve of the second unloading skid is increased. If the liquid delivery pressure increases, the opening of the first manual valve of the second unloading skid is reduced. If the liquid delivery pressure increases beyond the safe value, the second, third, and fourth vent valves are opened as needed to discharge the BOG in the unloading skid pipeline until the pressure drops back to a safe range. The pressure increased by vaporization in the heavy vehicle storage tank is used to transfer the heavy vehicle LNG to the storage area for storage.

[0019] After the heavy vehicle unloading is completed, the third and second manual valves are closed in sequence to cut off the unloading pipeline. At the same time, the first vent valve is opened to discharge the residual LNG and BOG in the unloading pipeline to the station BOG system. The fourth and first manual valves are closed in sequence to cut off the connection between the light vehicle and the second unloading skid. At the same time, the fifth manual valve is opened to equalize the pressure of the second unloading skid and the station BOG system. The high-pressure BOG gas in the vaporizer enters the station BOG system, fully utilizing the BOG gas and reducing external discharge. The fifth manual valve is then closed and the second, third, and fourth vent valves are opened to discharge the residual BOG in the pipeline of the second unloading skid to the station BOG system.

[0020] When the BOG in a light vehicle flows to two or more heavy vehicles at the same time, the operation process is the same as that of a light vehicle flowing to a heavy vehicle, and the unloading process of each heavy vehicle is the same as the above unloading process.

[0021] After the heavy truck unloading is completed, the fifth manual valve is opened to equalize the pressure of the unloading skid and the station BOG system. After unloading, the BOG is mainly divided into three parts: ① Part remains in the light truck tank and can be used for the next unloading through this operating device; ② Part enters the station BOG system through the fifth manual valve; ③ Part is emptied through the vent valves on the unloading skid.

[0022] Beneficial effects of the utility model:

[0023] The utility model discloses an operation device for rapid liquid unloading by utilizing BOG recovery. By arranging a pressure-equalizing pipe and a branch pipe, a plurality of parallel liquid unloading skids are connected. The BOG remaining in a light vehicle is supplied to a heavy vehicle to be unloaded subsequently. The higher-pressure BOG in the light vehicle continuously flows to the heavy vehicle, squeezing the LNG in the heavy vehicle out of the tanker storage tank, thereby accelerating the liquid unloading speed of the tanker. As the BOG in the light vehicle continuously enters the heavy vehicle, the heavy vehicle is rapidly pressurized, shortening the time and flow rate of LNG gasification in the vaporizer, quickly and conveniently improving the liquid unloading efficiency of the LNG storage and distribution station, and recycling the BOG natural gas remaining in the storage tank. At the same time, the risk of explosion caused by the on-site venting of the BOG natural gas remaining in the tanker is reduced. This device overcomes the disadvantages of slow liquid unloading during peak gas consumption seasons, the lack of liquid unloading skids, and the inability to meet gas supply conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a flow chart of an operating device for rapid liquid unloading using BOG recovery in the utility model;

[0025] Figure 2 This is a plan view of an operating device for rapid liquid unloading using BOG recovery according to the present invention;

[0026] Figure 3 This is an elevational view of an operating device for rapid liquid unloading using BOG recovery according to the present invention.

[0027] Reference numerals:

[0028] 1-base, 2-vaporizer, 3-second vent valve, 4-fourth vent valve, 5-third vent valve, 6-first vent valve, 7-fourth manual valve, 8-first manual valve, 9-fifth manual valve, 10-second manual valve, 11-third manual valve, 12-pressurized liquid outlet pipeline, 131-first gas phase pipeline, 132-second gas phase pipeline, 14-liquid unloading pipeline, 15-equalizing valve, 16-equalizing pipeline, 17-first branch pipe, N1-pressurized liquid inlet, N2-BOG inlet, N3-LNG inlet, N4-BOG outlet, N5-LNG outlet, A-first liquid unloading skid, B-second liquid unloading skid. DETAILED DESCRIPTION

[0029] The present invention will be further described below with reference to the accompanying drawings.

[0030] like Figure 1 As shown, a device for rapid liquid unloading using BOG recovery is shown, comprising a plurality of parallelly arranged liquid unloading skids connected to each other via a surge pipe 16. Each liquid unloading skid comprises a vaporizer 2 for vaporizing LNG, a pressurized liquid outlet pipe 12 connected to the liquid inlet of the vaporizer 2, a first gas phase pipe 131 connected to the gas outlet of the vaporizer 2, and a second gas phase pipe 132 for conveying BOG gas. The second gas phase pipe 132 branches off into a first branch pipe 17 after passing through a first manual valve 8 and is connected to the surge pipe 16. The liquid unloading skid is disposed on a base 1.

[0031] The unloading skid also includes an unloading pipeline 14 for transporting LNG. The unloading pipeline 14 is provided with an LNG inlet N3 and an LNG outlet N5. The LNG inlet N3 is connected to the unloading port of the tank truck via a first hose, and the LNG outlet N5 is connected to the pipeline of the station LNG storage system.

[0032] A second manual valve 10 and a third manual valve 11 are sequentially provided on the unloading pipeline 14 along the LNG transport direction. Preferably, the second manual valve 10 is provided on the unloading pipeline near the LNG inlet N3, and the third manual valve 11 is provided on the unloading pipeline near the LNG outlet N5. A second branch pipe branches from the unloading pipeline between the second and third manual valves 10, 11, and a first vent valve 6 is provided on the second branch pipe. The first vent valve 6 protects the unloading pipeline from overpressure and is opened when the pressure in the unloading pipeline 6 exceeds a safe value during unloading, or when residual liquid or BOG gas needs to be discharged from the unloading pipeline or unloading skid after unloading is completed.

[0033] A pressurized liquid phase inlet N1 is provided at one end of the pressurized liquid outlet pipe 12 away from the gasifier. The pressurized liquid phase inlet N1 is connected to the pressurized liquid phase outlet of the tank truck via a second hose.

[0034] A fourth manual valve 7 is installed on the pressurized liquid outlet pipeline 12. A third branch of the pressurized liquid outlet pipeline between the fourth valve 7 and the vaporizer 2 is branched off. This third branch is equipped with a second vent valve 3. In its initial state, the pressurized liquid outlet pipeline 12 is used to transport LNG to the vaporizer 2 for vaporization. Second vent valve 3 protects the pressurized liquid outlet pipeline 12 from overpressure. It opens in the following two situations: ① when the pressure in the pressurized liquid outlet pipeline 12 exceeds a safe value during liquid unloading; ② when residual liquid or BOG gas needs to be drained from the pressurized liquid outlet pipeline 12 or the liquid unloading skid after liquid unloading is complete.

[0035] The first branch pipe 17 is provided with a pressure equalizing valve 15 .

[0036] The second gas-phase pipeline 132 has a BOG inlet N2 at one end and a BOG outlet N4 at the other. The BOG inlet N2 is connected to the BOG port of the tank truck via a third hose, while the BOG outlet N4 is connected to the station's BOG system pipeline. A fourth branch pipe branches out from the second gas-phase pipeline 132 between the first manual valve 8 and the first branch pipe 17. A third vent valve 5 is installed on the fourth branch pipe. The third vent valve 5 protects the second gas-phase pipeline 132 from overpressure and is opened in the following two situations: ① when the pressure in the second gas-phase pipeline 132 exceeds a safe level during liquid unloading; ② when residual liquid or BOG gas needs to be discharged from the second gas-phase pipeline 132 or the liquid unloading skid after liquid unloading is completed.

[0037] The first gas phase pipeline 131 and the second gas phase pipeline 132 merge into a downstream pipeline at the location where the first branch pipe 17 is separated, and then connected to the station BOG system pipeline. A fifth manual valve 9 is provided on the second gas phase pipeline downstream of the connection with the first gas phase pipeline 131.

[0038] A fifth branch pipe branches out from the first gas-phase pipeline 131, which is equipped with a fourth vent valve 4. This valve protects the first gas-phase pipeline 131 from overpressure and is opened in the following two situations: ① when the pressure in the first gas-phase pipeline 131 exceeds a safe value during liquid unloading; ② when residual liquid or BOG gas needs to be discharged from the first gas-phase pipeline 131 or the liquid unloading skid after liquid unloading is completed.

[0039] All liquid unloading skids are connected to the leveling pipe 16 via the first branch pipe 17 .

[0040] The second branch pipe, the third branch pipe, the fourth branch pipe and the fifth branch pipe are all connected to the station BOG system.

[0041] The working principle of the BOG recovery and rapid liquid unloading device of the utility model is as follows:

[0042] like Figure 1-3As shown, two parallel liquid unloading skids are used as an example for explanation. The two liquid unloading skids are respectively a first liquid unloading skid A and a second liquid unloading skid B. Before use, all valves of the operating device for rapid liquid unloading using BOG recovery described in the utility model are in a closed state.

[0043] After unloading the liquid, the transport tank truck becomes a light truck. The tank of the light truck contains BOG (pressure is about 0.7MPa, for example). The tank truck that has not unloaded the liquid is a heavy truck. The tank of the heavy truck contains LNG and a small amount of BOG at about 0.1MPa. The BOG inlet N2 of the first unloading skid A is connected to the BOG port of the light truck. The BOG inlet of the second unloading skid B is connected to the BOG port of the heavy truck. The pressurized liquid phase inlet of the second unloading skid B is connected to the pressurized liquid phase outlet of the heavy truck. The LNG inlet of the second unloading skid is connected to the unloading port of the tank truck of the heavy truck. Simultaneously, open the first manual valve 8 and the equalizing valve 15 of the first liquid unloading skid A and the second liquid unloading skid B, connect the light truck and the heavy truck gas phase, and disconnect them from the terminal BOG system. The higher-pressure BOG in the light truck continuously flows to the heavy truck through the branch pipe, squeezing the LNG in the heavy truck out of the tank truck storage tank, thereby accelerating the tank truck unloading process. When the BOG pressures in the heavy truck and the light truck are basically the same, close the first manual valve 8 and the equalizing valve 15 of the second liquid unloading skid B, and close the first manual valve 8 and the equalizing valve 15 of the first liquid unloading skid A, and then enter the heavy truck unloading process.

[0044] The heavy truck unloading process includes: opening the fourth manual valve 7 of the second unloading skid B to transfer the LNG in the heavy truck to the vaporizer 2 of the second unloading skid B for vaporization. After the vaporization reaches a certain pressure, the first manual valve 8 of the second unloading skid B is opened to continuously vaporize and pressurize the heavy truck LNG storage tank. After the liquid delivery pressure requirement is reached, the second manual valve 10 and the third manual valve 11 of the second unloading skid B are opened. During the unloading process, it is necessary to observe and dynamically adjust the BOG pressure to maintain pressure stability and ensure rapid unloading. If the liquid delivery pressure decreases during unloading, the opening of the first manual valve 8 of the second unloading skid B is increased. If the liquid delivery pressure increases, the opening of the first manual valve 8 of the second unloading skid B is reduced. If the liquid delivery pressure increases beyond a safe value, the second vent valve 3, the third vent valve 5, and the fourth vent valve 4 are opened as needed to discharge the BOG in the unloading skid pipeline until the pressure returns to a safe range. The pressure increased by vaporization in the heavy truck storage tank is then used to transfer the heavy truck LNG to the storage area for storage.

[0045] After the heavy vehicle unloading is completed, the third manual valve 11 and the second manual valve 10 are closed in sequence to cut off the unloading pipeline 14. At the same time, the first vent valve 6 is opened to discharge the residual LNG and BOG in the unloading pipeline 14 to the terminal BOG system. The fourth manual valve 7 and the first manual valve 8 are closed in sequence to cut off the connection between the light vehicle and the second unloading skid B. At the same time, the fifth manual valve 9 is opened to equalize the pressure of the second unloading skid and the terminal BOG system. The high-pressure BOG gas in the vaporizer 2 enters the terminal BOG system, fully utilizing the BOG gas and reducing external discharge. The fifth manual valve 9 is then closed and the second vent valve 3, the third vent valve 5, and the fourth vent valve 4 are opened to discharge the residual BOG in the pipeline of the second unloading skid B to the terminal BOG system.

[0046] When the BOG in a light vehicle flows to two or more heavy vehicles at the same time, the operation process is the same as that of a light vehicle flowing to a heavy vehicle, and the unloading process of each heavy vehicle is the same as the above unloading process.

[0047] After the heavy vehicle unloading is completed, the fifth manual valve 9 is opened to equalize the pressure between the unloading skid and the terminal BOG system. After unloading, the BOG is mainly divided into three parts: ① Part remains in the light vehicle tank and can be used for the next unloading through this operating device; ② Part enters the terminal BOG system through the fifth manual valve 9; and ③ Part is emptied through the vent valves on the unloading skid.

[0048] The above describes preferred embodiments of the present invention. However, the above description is not intended to be limiting. Those skilled in the art may make numerous changes or modifications to the present invention without departing from the spirit and scope of the present invention. Such changes or modifications are intended to fall within the scope of the appended claims.

Claims

1. A device for rapid liquid unloading using BOG recovery, characterized in that: The invention comprises a plurality of liquid unloading skids arranged in parallel, wherein the plurality of liquid unloading skids are connected to each other via a pressure-scaling pipeline (16), each liquid unloading skid comprises a vaporizer (2) for gasifying LNG, a pressurized liquid outlet pipeline (12) connected to the liquid inlet of the vaporizer (2), a first gas phase pipeline (131) connected to the gas outlet of the vaporizer (2), and a second gas phase pipeline (132) for conveying BOG gas, wherein the second gas phase pipeline (132) branches off into a first branch pipe (17) after passing through a first manual valve (8) and is connected to the pressure-scaling pipeline (16), and the liquid unloading skid is arranged on a base (1).

2. The device for rapid liquid unloading by BOG recovery according to claim 1, characterized in that: The liquid unloading skid further comprises a liquid unloading pipeline (14) for transporting LNG. The liquid unloading pipeline (14) is provided with an LNG inlet (N3) and an LNG outlet (N5). The LNG inlet (N3) is connected to the liquid unloading port of the tank truck via a first hose, and the LNG outlet (N5) is connected to the pipeline of the LNG storage system of the station.

3. The device for rapid liquid unloading by BOG recovery according to claim 2, characterized in that: A second manual valve (10) and a third manual valve (11) are sequentially provided on the liquid unloading pipeline (14) along the LNG transportation direction. A second branch pipe is branched from the liquid unloading pipeline (14) between the second manual valve (10) and the third manual valve (11). A first vent valve (6) is provided on the second branch pipe.

4. The device for rapid liquid unloading by BOG recovery according to claim 3, characterized in that: A pressurized liquid phase inlet (N1) is provided at one end of the pressurized liquid outlet pipe (12) away from the gasifier, and the pressurized liquid phase inlet (N1) is connected to the pressurized liquid phase outlet of the tank truck via a second hose.

5. The device for rapid liquid unloading by BOG recovery according to claim 4, characterized in that: A fourth manual valve (7) is provided on the pressurized liquid outlet pipeline (12), a third branch pipe is branched from the pressurized liquid outlet pipeline between the fourth manual valve (7) and the vaporizer (2), and a second vent valve (3) is provided on the third branch pipe.

6. The device for rapid liquid unloading by BOG recovery according to claim 5, characterized in that: The first branch pipe (17) is provided with a pressure-equalizing valve (15).

7. The device for rapid liquid unloading utilizing BOG recovery according to any one of claims 1 to 6, characterized in that: A BOG inlet (N2) is provided at one end of the second gas phase pipeline (132), and a BOG outlet (N4) is provided at the other end. The BOG inlet (N2) is connected to the BOG port of the tank truck via a third hose, and the BOG outlet (N4) is connected to the BOG system pipeline of the station. A fourth branch pipe is branched from the second gas phase pipeline (132) between the first manual valve (8) and the first branch pipe (17), and a third vent valve (5) is provided on the fourth branch pipe.

8. The device for rapid liquid unloading by BOG recovery according to claim 7, characterized in that: The first gas phase pipeline (131) and the second gas phase pipeline (132) merge into a downstream pipeline at the location where the first branch pipe (17) is branched off, and then connected to the station BOG system pipeline. A fifth manual valve (9) is provided on the second gas phase pipeline downstream of the connection with the first gas phase pipeline (131).

9. The device for rapid liquid unloading by BOG recovery according to claim 8, characterized in that: A fourth vent valve (4) is provided on the first gas phase pipeline (131).

10. The device for rapid liquid unloading by BOG recovery according to claim 9, characterized in that: All the liquid unloading skids are connected to the leveling pipe (16) through the first branch pipe (17).

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