BOG (Boil Off Gas) treatment equipment of marine LNG (Liquefied Natural Gas) fuel supply system

Abstract

The invention discloses BOG (Boil Off Gas) treatment equipment of a marine LNG (Liquefied Natural Gas) fuel supply system, and belongs to the technical field of fuel supply. The BOG treatment equipment of the marine LNG fuel supply system comprises a mounting plate and a storage tank mounted on the outer wall of the top end of the mounting plate, a material injection assembly used for injecting materials into a boiler is arranged on the outer wall of the storage tank, a cabin is formed between a storage tank shell and a storage tank body in a hollow mode, and a liquefaction assembly is arranged in the cabin. The internal pressure of the storage tank can be automatically detected, a BOG management mode or an LNG pump supply mode can be switched in a manual or automatic mode, BOG in the storage tank can be compressed and cooled when a ship is berthed so as to be re-liquefied, meanwhile, the two heat exchangers heat or cool fuel in turn, additional equipment is not needed, energy consumption is low, and cost is low. And the BOG can be fully utilized, the utilization rate of the LNG is increased, and the heat exchanger is simple in structure, free of additional maintenance, low in price, small in occupied area, high in reliability, and one heat exchanger is used and the other heat exchanger is standby.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel supply, and in particular to a BOG processing device of a marine LNG fuel supply system. Background Art

[0002] Boil-off gas (BOG) is a derivative of liquefied natural gas (LNG). Its existence and emission will not only cause great economic losses to ships, but also pose hidden dangers to ship safety. After liquid LNG enters the LNG storage tank, it will inevitably exchange heat with the outside world, causing the temperature of the LNG in the tank to rise. Therefore, part of the liquid evaporates to produce BOG flash gas. After BOG is formed, it will increase the pressure in the LNG storage tank. When the pressure reaches a certain pressure, it will open the safety valve and discharge the excess natural gas into the atmosphere through the vent pipe to relieve the pressure inside the tank and avoid explosion.

[0003] Chinese patent CN112648530B published on April 26, 2022 discloses a BOG treatment system for LNG tankers, which can recycle excess BOG generated when the LNG tanker is anchored and convert it into relatively stable natural gas hydrates to avoid direct discharge into the atmosphere, causing energy waste and environmental pollution. At the same time, it effectively utilizes the large amount of cold energy released by LNG and BOG before combustion to prepare low-temperature water, thereby reducing the energy consumption in the synthesis of natural gas hydrates and improving energy utilization. However, the BOG treatment system for LNG tankers is suitable for situations where the amount of BOG generated in LNG storage tanks is large, and its BOG reliquefaction device has large investment and complex operation. Summary of the invention

[0004] The object of the present invention is to provide a BOG treatment device for a marine LNG fuel supply system to solve the problems raised in the above background technology.

[0005] To achieve the above-mentioned object, the present invention provides the following technical solutions: a BOG processing device of a marine LNG fuel supply system, comprising a mounting plate, and a storage tank mounted on the outer wall at the top end of the mounting plate, the storage tank comprising a storage tank shell fixedly connected to the outer wall at the top end of the mounting plate, a storage tank body fixedly connected inside the storage tank shell, an injection assembly for injecting material into a boiler is arranged on the outer wall at one end of the storage tank, the injection assembly comprises a separation mechanism for gas-liquid separation of the fuel inside the storage tank, and a control box mounted on the outer wall at the top end of the mounting plate, a control system is mounted on the outer wall of the control box, a heat exchanger is mounted on the inner wall of the control box, the separation mechanism is controlled by the control system to select BOG or LNG to be injected into the heat exchanger for heating, a chamber is formed hollow between the storage tank shell and the storage tank body, and a liquefaction assembly is arranged inside the chamber, the liquefaction assembly comprises a vent pipe for sucking the BOG inside the storage tank body into the interior of the chamber, and a reflux pipe for re-injecting the liquefied BOG into the interior of the storage tank body.

[0006] Furthermore, the separation mechanism includes a liquid inlet pipe arranged on a side of the storage tank shell close to the control box, the liquid inlet pipe is installed in a direction close to the control box, an injection pipe is installed at one end of the second inlet valve, a water-gas dual-purpose pump adapted to the injection pipe is provided on one outer wall of the control box, a first connecting pipe running through the interior of the control box is installed at one end of the water-gas dual-purpose pump, a first connecting pipe extending into the interior of the control box is installed at one end of the water-gas dual-purpose pump, a first check valve is installed at one end of the first connecting pipe extending into the interior of the control box, a feeding pipe is installed on an outer wall of one side of the first check valve, one end of the feeding pipe is connected to the heat exchanger, a discharge pipe is fixedly connected to an outer wall of one side of the heat exchanger, an electric three-way valve is installed on the outer wall of the discharge pipe, a second connecting pipe running through the outer wall of the control box is installed on one outer wall of the electric three-way valve, a second check valve is installed at one end of the second connecting pipe extending out of the control box, and one end of the second check valve is connected to the return pipe, and an injection pipe for conveying fuel to the boiler is installed at the other end of the second check valve.

[0007] Furthermore, the heat exchanger is provided with two groups inside the control box, two groups of feeding pipes respectively connected to the two groups of control boxes are installed on the outer wall of the first check valve, and both ends of the discharge pipe on the outer wall of the electric three-way valve are respectively connected to the two groups of control boxes.

[0008] Furthermore, the separation mechanism also includes a pressure gauge arranged on an outer wall of one side of the storage tank shell, a pressure sensor is installed on the outer wall of one side of the storage tank shell, an air intake pipe is installed on the side of the storage tank shell close to the control box, a first inlet valve is installed on the air intake pipe close to the control box, an air injection pipe adapted for a water-gas dual-purpose pump is provided at one end of the first inlet valve, and the end of the air injection pipe close to the first inlet valve is connected to one end of the ventilation pipe.

[0009] Furthermore, the liquefaction component includes an air inlet opened on the inner wall of the storage tank body, and a plurality of first guide plates and second guide plates arranged in a circumferential direction on the outer peripheral surface of the storage tank body to form a channel, a gap exists between the first guide plate and the storage tank shell in the direction close to the ventilation pipe, a gap exists between the second guide plate and the storage tank shell in the direction close to the air inlet, the distance between the first guide plate and the second guide plate decreases successively from point A to point B, and the first guide plate and the second guide plate are adjacent to each other and the channel formed is connected to the ventilation pipe.

[0010] Furthermore, the liquefaction component also includes a limit plate and a limit rod arranged inside the channel, the limit plate having a through hole on its surface facing the channel, a limit rod being provided at one end of the first guide plate close to the gap and at one end of the second guide plate closed with the storage tank shell, a return spring being fixedly connected to a side of the storage tank shell in the direction of the return spring being fixedly connected to a push plate in the direction of the limit rod, a connecting rod being slidably connected to an inner wall of the push plate, a piston plate being fixedly connected to the connecting rod in the direction of the limit plate, a connecting spring adapted for the push plate being provided in the direction of the connecting rod away from the piston plate, a first vent being provided on the surface of the push plate, first connecting grooves adapted for the limit rod being provided at both ends of the push plate, a second vent being provided on the surface of the piston plate, second connecting grooves adapted for the limit rod being provided at both ends of the piston plate, and a rubber pad being fitted on the inner wall of the second connecting groove.

[0011] The difference from the prior art is that the beneficial effects of this application are:

[0012] The BOG processing equipment of the ship's LNG fuel supply system can automatically detect the internal pressure of the storage tank and switch the BOG management mode or the LNG pump supply mode manually or automatically. When the ship is moored, it can compress and cool the BOG inside the storage tank to liquefy it. At the same time, the two heat exchangers heat or cool the fuel in turn. No additional equipment is required, the energy consumption is low, and the BOG can be fully utilized to improve the utilization rate of LNG. The heat exchanger has a simple structure, does not require additional maintenance, is cheap, occupies a small area, has one for use and one for backup, and has high reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the three-dimensional structure of an embodiment of the present invention;

[0014] Figure 2 This is a schematic diagram of the structure of the storage tank shell and the storage tank body cooperating with each other in the present invention;

[0015] Figure 3 This is a schematic diagram of the internal structure of the control box of the present invention;

[0016] Figure 4 This is a schematic diagram of the structure of the air inlet and the guide plate cooperating with each other in the present invention;

[0017] Figure 5 This is a schematic diagram of the structure of the guide plate and the storage tank body cooperating with each other in the present invention;

[0018] Figure 6 This is a schematic diagram of the structure of the return spring and the push plate cooperating with each other in the present invention;

[0019] Figure 7 It is a schematic diagram of the structure of the second connecting groove and the rubber pad cooperating with each other in the present invention.

[0020] In the figure: 1, mounting plate; 2, storage tank; 21, storage tank shell; 22, storage tank body; 3, injection assembly; 301, pressure gauge; 302, pressure sensor; 303, control box; 304, control system; 305, air inlet pipe; 306, first inlet valve; 307, air injection pipe; 308, water-gas dual-purpose pump; 309, liquid inlet pipe; 310, second inlet valve; 311, liquid injection pipe; 312, first connecting pipe; 313, first check valve; 314, feeding pipe; 315, heat exchanger; 316, discharge pipe; 317, electric three-way valve; 318. Second connecting pipe; 319. Second check valve; 320. Filling pipe; 4. Liquefaction assembly; 401. Air inlet; 402. First guide plate; 403. Ventilation pipe; 404. Return pipe; 405. Limit plate; 406. Through hole; 407. Limit rod; 408. Return spring; 409. Push plate; 410. Connecting rod; 411. Piston plate; 412. Connecting spring; 413. First vent hole; 414. First connecting groove; 415. Second vent hole; 416. Second connecting groove; 417. Rubber pad; 418. Second guide plate. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0023] Embodiment 1

[0024] See also Figure 1-Figure 7The present invention provides a technical solution: a BOG processing device of a marine LNG fuel supply system, comprising a mounting plate 1, and a storage tank 2 mounted on the top outer wall of the mounting plate 1, the storage tank 2 comprising a storage tank shell 21 fixedly connected to the top outer wall of the mounting plate 1, a storage tank body 22 fixedly connected to the storage tank shell 21, an injection assembly 3 for injecting material into a boiler is arranged on the outer wall of one end of the storage tank 2, the injection assembly 3 comprises a separation mechanism for gas-liquid separation of the fuel inside the storage tank 2, and a control mechanism mounted on the top outer wall of the mounting plate 1. The control box 303 is provided with a control system 304 on its outer wall, and a heat exchanger 315 on its inner wall. The control system 304 controls the separation mechanism to select BOG or LNG to be injected into the heat exchanger 315 for heating. A hollow chamber is formed between the storage tank shell 21 and the storage tank body 22, and a liquefaction component 4 is arranged inside the chamber. The liquefaction component 4 includes a vent pipe 403 for sucking the BOG inside the storage tank body 22 into the chamber, and a reflux pipe 404 for re-injecting the liquefied BOG into the storage tank body 22.

[0025] When in use, when the internal pressure of the storage tank 2 is greater than 3Bar, the control system 304 can be manually operated to enter the BOG management mode and can be manually exited. When it is lower than 2Bar, the control system 304 will automatically close the BOG management mode and switch to the LNG pump supply mode. When the internal pressure of the storage tank 2 is greater than 7Bar, the control system 304 automatically switches to the BOG management mode. If no confirmation is made within 30s, the system will automatically enter the boiler BOG mode. Manually clicking the boiler "LNG supply" within 30s will continue the LNG supply. The BOG or LNG inside the storage tank body 22 is injected into the heat exchanger 315 inside the control box 303 through the separation mechanism for heating, and then transported to the boiler. When the ship is moored, the boiler consumes less fuel, and the pressure inside the storage tank 2 will increase. At this time, the BOG inside the storage tank body 22 will enter the compartment between the storage tank shell 21 and the storage tank body 22 for squeezing, and then injected into the interior of the heat exchanger 315 through the vent pipe 403 for cooling and condensation into liquid, and finally flows back to the interior of the storage tank body 22 through the reflux pipe 404.

[0026] See also Figure 1 and Figure 3As shown in the figure, the separation mechanism includes a liquid inlet pipe 309 arranged on the side of the storage tank shell 21 close to the control box 303, a second inlet valve 310 is installed on the liquid inlet pipe 309 close to the side of the control box 303, a liquid injection pipe 311 is installed at one end of the second inlet valve 310, a water-gas dual-purpose pump 308 adapted to the liquid injection pipe 311 is arranged on the outer wall of one side of the control box 303, a first connecting pipe 312 penetrating the interior of the control box 303 is installed at one end of the water-gas dual-purpose pump 308, a first check valve 313 is installed at one end of the first connecting pipe 312 extending into the interior of the control box 303, and the first check valve 313 is installed at one end of the first connecting pipe 312 extending into the interior of the control box 303. A feeding pipe 314 is installed on the outer wall of one side, one end of the feeding pipe 314 is connected to the heat exchanger 315, a discharge pipe 316 is fixedly connected to the outer wall of one side of the heat exchanger 315, an electric three-way valve 317 is installed on the outer wall of the discharge pipe 316, a second connecting pipe 318 penetrating the outer wall of the control box 303 is installed on the outer wall of one side of the electric three-way valve 317, a second check valve 319 is installed on the end of the second connecting pipe 318 extending out of the control box 303, one end of the second check valve 319 is connected to the return pipe 404, and the other end of the second check valve 319 is installed with an injection pipe 320 for conveying fuel to the boiler.

[0027] During use, when the internal pressure of the storage tank 2 is lower than 2 Bar, the control system 304 will control the second inlet valve 310 and the first check valve 313 to open, and at the same time start the water-gas dual-purpose pump 308 to pump the LNG inside the storage tank body 22 into the inside of the injection pipe 311 through the liquid inlet pipe 309, and then enter the inside of the heat exchanger 315 through the first connecting pipe 312 and the feeding pipe 314, so as to heat the LNG and prevent the LNG from being directly supplied to the boiler, resulting in reduced combustion efficiency and causing engine failure. The heated LNG will enter the injection pipe 320 through the discharge pipe 316 and the second connecting pipe 318 and be transported into the boiler. The first check valve 313 on the surface of the feeding pipe 314 and the second check valve 319 on the surface of the second connecting pipe 318 can prevent the LNG from flowing back when the pressure of the boiler is too high.

[0028] See also Figure 3 As shown in the figure, two groups of heat exchangers 315 are arranged inside the control box 303, two groups of feeding pipes 314 respectively connected to the two groups of control boxes 303 are installed on the outer wall of the first check valve 313, and the two ends of the discharge pipe 316 on the outer wall of the electric three-way valve 317 are respectively connected to the two groups of control boxes 303.

[0029] When in use, the first check valve 313 is controlled to inject the fuel inside the storage tank body 22 into one of the heat exchangers 315 through the feeding pipe 314 and heat it up, and then supply it to the boiler through the discharge pipe 316. At the same time, the electric three-way valve 317 on the surface of the discharge pipe 316 can prevent the fuel from flowing back into the other heat exchanger 315. No additional equipment is required, the energy consumption is low, and BOG can be fully utilized to improve the utilization rate of LNG. The BOG heat exchanger has a simple structure, does not require additional maintenance, is cheap, occupies a small area, has one for use and one for backup, and has high reliability.

[0030] See also Figure 1 As shown in the figure, the separation mechanism also includes a pressure gauge 301 arranged on the outer wall of one side of the storage tank shell 21, a pressure sensor 302 is installed on the outer wall of one side of the storage tank shell 21, an air intake pipe 305 is installed on the side of the storage tank shell 21 close to the control box 303, and a first inlet valve 306 is installed on the side of the air intake pipe 305 close to the control box 303. An air injection pipe 307 adapted to a water-gas dual-purpose pump 308 is provided at one end of the first inlet valve 306, and an end of the air injection pipe 307 close to the first inlet valve 306 is connected to one end of the ventilation pipe 403.

[0031] When in use, the pressure gauge 301 will monitor the internal pressure of the storage tank body 22 in real time, and transmit the data to the control system 304 through the pressure sensor 302. When the control system 304 determines that the internal pressure of the storage tank body 22 is too high, it will enter the BOG management mode, at which time the second inlet valve 310 is closed and the first inlet valve 306 is opened. Through the pressure inside the storage tank body 22, the BOG is automatically injected into the interior of the injection pipe 307 through the air inlet pipe 305, and then enters the interior of the heat exchanger 315 through the first connecting pipe 312 and the feeding pipe 314 to heat the BOG, and finally enters the injection pipe 320 through the discharge pipe 316 and the second connecting pipe 318 and is transported into the boiler.

[0032] In order to ensure that the pressure inside the storage tank 2 is kept within a safe range when the ship is at anchor, please refer to Figure 1 , Figure 4 and Figure 5 As shown in the figure, the liquefaction component 4 includes an air inlet 401 opened on the inner wall of the storage tank body 22, and a plurality of first guide plates 402 and second guide plates 418 arranged in a circumferential direction along the outer surface of the storage tank body 22 to form a channel, a gap exists between the first guide plate 402 and the storage tank shell 21 in the direction close to the ventilation pipe 403, a gap exists between the second guide plate 418 and the storage tank shell 21 in the direction close to the air inlet 401, the distance between the first guide plate 402 and the second guide plate 418 decreases successively from point A to point B, and the first guide plate 402 and the second guide plate 418 are adjacent to each other and the channel formed is connected to the ventilation pipe 403.

[0033] During use, when the pressure inside the storage tank 2 is too high during the mooring process of the ship, the water-gas dual-purpose pump 308 is started to pump the gas inside the cabin between the storage tank shell 21 and the storage tank body 22 into the interior of the gas injection pipe 307 through the ventilation pipe 403, thereby reducing the air pressure inside the cabin. At this time, the BOG inside the storage tank body 22 will enter the interior of the cabin through the air inlet 401. The BOG entering the cabin can be guided by multiple sets of first guide plates 402 and second guide plates 418, so that the BOG inside the cabin can only move along the channel formed by the first guide plates 402 and the second guide plates 418, so that the BOG entering the cabin can flow through the storage tank body 22 Each corner of the outer wall can be insulated by the low temperature characteristic of BOG itself, thereby reducing the gasification efficiency of LNG inside the storage tank body 22, and the widths of the multiple groups of through grooves inside the compartment are successively reduced, so that each time BOG flows into a through groove, the BOG will be squeezed. When BOG enters the through groove with the narrowest width, it will be sucked into the inside of the gas injection pipe 307 through the vent pipe 403, and then enter the inside of the heat exchanger 315 through the first connecting pipe 312 and the feeding pipe 314 for cooling treatment, so that the BOG is converted back into LNG, and finally enters the reflux pipe 404 through the discharge pipe 316 and the second connecting pipe 318, and finally flows back to the inside of the storage tank body 22.

[0034] See also Figure 6-Figure 7 As shown in the figure, the liquefaction component 4 also includes a limit plate 405 and a limit rod 407 arranged inside the channel. The limit plate 405 has a through hole 406 on its surface facing the channel. The first guide plate 402 has an end close to the gap and the second guide plate 418 has an end closed to the storage tank shell 21. A return spring 408 is fixedly connected to the side of the channel close to the storage tank shell 21. A push plate 409 is fixedly connected to the return spring 408 on the side close to the limit rod 407. A connecting rod 410 is slidably connected to the inner wall of the push plate 409. The connecting rod 410 is fixedly connected to a piston plate 411 on the side close to the limit plate 405, and a connecting spring 412 adapted to the push plate 409 is arranged on the side of the connecting rod 410 away from the piston plate 411. A first air vent 413 is provided on the surface of the push plate 409, and first connecting grooves 414 adapted to the limit rod 407 are provided at both ends of the push plate 409. A second air vent 415 is provided on the surface of the piston plate 411, and second connecting grooves 416 adapted to the limit rod 407 are provided at both ends of the piston plate 411, and a rubber pad 417 is attached to the inner wall of the second connecting groove 416.

[0035] When in use, after BOG enters the channel through the gap between the first guide plate 402, the second guide plate 418 and the storage tank shell 21, it will exert a thrust on the surface of the push plate 409, so that the push plate 409 and the piston plate 411 slide toward the limit plate 405 on the surface of the limit rod 407 through the first connecting groove 414 and the second connecting groove 416 and pull the return spring 408. At this time, the piston plate 411 will squeeze the BOG between the piston plate 411 and the limit plate 405, so that the BOG between the piston plate 411 and the limit plate 405 is The BOG is compressed by the first air hole 413 and passes through the stop plate 405 through the through hole 406 to enter the other end of the channel. When the BOG enters the through hole 406, it is compressed again. When the BOG passes through the through hole 406, the flow speed is accelerated, thereby promoting the liquefaction efficiency of the BOG. ​​After the push plate 409 slides on the surface of the stop rod 407 for a distance, it stops sliding due to the pulling force of the return spring 408. At this time, the BOG enters the first air hole 413 and pushes the piston plate 411 to continue sliding on the surface of the stop rod 407. The push plate 409 is pushed back and the piston plate 411 is pressed against the piston plate 412, thereby pulling the connecting rod 410 to slide inside the push plate 409 and compressing the connecting spring 412, so that the push plate 409 and the piston plate 411 are separated and the limit of the first vent hole 413 and the second vent hole 415 is released. At this time, the reset spring 408 is forced to pull the push plate 409 to reset. Since the rubber pad 417 is attached to the inner wall of the second connecting groove 416, the friction between the piston plate 411 and the limit rod 407 is greater than the friction between the push plate 409 and the limit rod 407, so that the push plate 409 and the piston plate 411 are separated and the limit of the first vent hole 413 and the second vent hole 415 is released. Plate 409 must slide backwards before piston plate 411. During this process, push plate 409 will pull piston plate 411 to slide synchronously through connecting rod 410, and BOG will pass through the first vent hole 413 and the second vent hole 415 to re-enter between piston plate 411 and limit plate 405. When push plate 409 is reset, the force applied to connecting rod 410 by connecting spring 412 will pull piston plate 411 and push plate 409 to close, and limit the first vent hole 413 and the second vent hole 415 again.

[0036] In the description of the present invention, it is necessary to understand that the orientation or positional relationship indicated by terms such as "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0037] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0038] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A BOG processing device for a marine LNG fuel supply system, comprising a mounting plate (1), and a storage tank (2) mounted on the top outer wall of the mounting plate (1), the storage tank (2) comprising a storage tank shell (21) fixedly connected to the top outer wall of the mounting plate (1), a storage tank body (22) fixedly connected to the interior of the storage tank shell (21), an injection assembly (3) for injecting material into a boiler is arranged on the outer wall of one end of the storage tank (2), characterized in that: The injection assembly (3) comprises a separation mechanism for separating gas and liquid from the fuel inside the storage tank (2), and a control box (303) mounted on the outer wall of the top end of the mounting plate (1), a control system (304) mounted on the outer wall of the control box (303), a heat exchanger (315) mounted on the inner wall of the control box (303), and the control system (304) controls the separation mechanism to select BOG or LNG to be injected into the heat exchanger (315) for heating. A hollow chamber is formed between the storage tank shell (21) and the storage tank body (22), and a liquefaction assembly (4) is arranged inside the chamber. The liquefaction assembly (4) comprises a vent pipe (403) for sucking BOG inside the storage tank body (22) into the chamber, and a reflux pipe (404) for re-injecting liquefied BOG into the storage tank body (22).

2. The BOG treatment equipment of a marine LNG fuel supply system according to claim 1, characterized in that: The separation mechanism comprises a liquid inlet pipe (309) arranged on a side of the storage tank shell (21) close to the control box (303); a second inlet valve (310) is installed on the liquid inlet pipe (309) close to the control box (303); a liquid injection pipe (311) is installed at one end of the second inlet valve (310); a water-gas dual-purpose pump (308) adapted to the liquid injection pipe (311) is arranged on an outer wall of one side of the control box (303); a first connecting pipe (312) penetrating the interior of the control box (303) is installed at one end of the water-gas dual-purpose pump (308); a first check valve (313) is installed at one end of the first connecting pipe (312) extending into the interior of the control box (303); the first check valve (313) is installed at one end of the first connecting pipe (312) extending into the interior of the control box (303); A feeding pipe (314) is installed on one side of the outer wall, one end of the feeding pipe (314) is connected to the heat exchanger (315), a discharge pipe (316) is fixedly connected to one side of the outer wall of the heat exchanger (315), an electric three-way valve (317) is installed on the outer wall of the discharge pipe (316), a second connecting pipe (318) penetrating the outer wall of the control box (303) is installed on one side of the outer wall of the electric three-way valve (317), a second check valve (319) is installed on one end of the second connecting pipe (318) extending out of the control box (303), and one end of the second check valve (319) is connected to the return pipe (404), and the other end of the second check valve (319) is installed with an injection pipe (320) for conveying fuel to the boiler.

3. The BOG treatment equipment of the marine LNG fuel supply system according to claim 2, characterized in that: Two groups of the heat exchanger (315) are arranged inside the control box (303); two groups of feeding pipes (314) are installed on the outer wall of the first check valve (313) and are respectively connected to the two groups of control boxes (303); and both ends of the discharge pipe (316) on the outer wall of the electric three-way valve (317) are respectively connected to the two groups of control boxes (303).

4. The BOG treatment equipment of the marine LNG fuel supply system according to claim 2, characterized in that: The separation mechanism further comprises a pressure gauge (301) arranged on an outer wall of one side of the storage tank shell (21); a pressure sensor (302) is installed on an outer wall of one side of the storage tank shell (21); an air intake pipe (305) is installed on a side of the storage tank shell (21) close to the control box (303); a first inlet valve (306) is installed on a side of the air intake pipe (305) close to the control box (303); an air injection pipe (307) adapted to a water-gas dual-purpose pump (308) is arranged at one end of the first inlet valve (306); and an end of the air injection pipe (307) close to the first inlet valve (306) is connected to one end of the ventilation pipe (403).

5. The BOG treatment equipment of a marine LNG fuel supply system according to claim 1, characterized in that: The liquefaction component (4) comprises an air inlet (401) opened on the inner wall of the storage tank body (22), and a plurality of first guide plates (402) and second guide plates (418) arranged in a circumferential direction on the outer surface of the storage tank body (22) to form a channel, wherein a gap exists between the first guide plate (402) and the storage tank shell (21) in a direction close to the ventilation pipe (403), and a gap exists between the second guide plate (418) and the storage tank shell (21) in a direction close to the air inlet (401), and the distance between the first guide plate (402) and the second guide plate (418) decreases in sequence from point A to point B, and the first guide plate (402) and the second guide plate (418) are adjacent to each other and the channel formed is connected to the ventilation pipe (403).

6. The BOG treatment equipment of the marine LNG fuel supply system according to claim 5, characterized in that: The liquefaction component (4) further comprises a limit plate (405) and a limit rod (407) arranged inside the channel, a through hole (406) is provided on the surface of the limit plate (405) facing the channel, a limit rod (407) is provided on the end of the first guide plate (402) close to the gap and the end of the second guide plate (418) closed to the storage tank shell (21), a return spring (408) is fixedly connected to the inside of the channel in a direction close to the storage tank shell (21), a push plate (409) is fixedly connected to the return spring (408) in a direction close to the limit rod (407), a connecting rod (410) is slidably connected to the inner wall of the push plate (409), and the connecting rod (410) is slidably connected to the inner wall of the push plate (409). 10) A piston plate (411) is fixedly connected in a direction close to one side of the limit plate (405), and a connecting spring (412) adapted to the push plate (409) is arranged on the connecting rod (410) in a direction away from the side of the piston plate (411), and a first vent hole (413) is provided on the surface of the push plate (409), and first connecting grooves (414) adapted to the limit rod (407) are arranged at both ends of the push plate (409), and a second vent hole (415) is provided on the surface of the piston plate (411), and second connecting grooves (416) adapted to the limit rod (407) are arranged at both ends of the piston plate (411), and a rubber pad (417) is attached to the inner wall of the second connecting groove (416).

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