Micro-interface vacuum type BOG recondenser and recondensation method

Abstract

According to the micro-interface vacuum type BOG recondenser and the recondensation method, LNG enters an LNG flow guide pipe from an LNG inlet, then enters an LNG liquid flow channel shrinkage pipe and is sprayed out at a high speed through an LNG nozzle pipe; bOG enters the BOG buffer chamber through the BOG inlet, is uniformly distributed through the micro-interface BOG annular plate arranged in the BOG buffer chamber and then is mixed with LNG gas and liquid in the mixing chamber, and the BOG is subjected to phase change condensation in filler of the filler section and enters the LNG buffer tank after passing through the flow channel expansion pipe. The BOG after-condenser is simple in structure, convenient to disassemble and assemble, easy to control, sufficient in gas-liquid contact, high in BOG condensation efficiency and low in operation energy consumption.

Description

Technical Field

[0001] The present invention relates to the technical field of liquefied natural gas boil-off gas recovery and treatment, and in particular to a micro-interface vacuum BOG recondenser and a recondensation method. Background Art

[0002] During long-distance transportation, receiving, and storage of LNG, a significant amount of LNG volatilizes due to heat leakage from storage tanks, heat introduced by pump operation, LNG loading and unloading, and environmental fluctuations, forming a large amount of boil-off gas (BOG). This BOG gas must be recovered and treated using appropriate processes; otherwise, the pressure within the storage tank will continue to rise, potentially leading to safety issues. Currently, BOG recovery methods both domestically and internationally fall into two main categories: direct compression and external recovery, and recondensation and liquefaction.

[0003] The direct compression and export method uses a compressor to directly pressurize the BOG to the export pipeline pressure. However, due to its high energy consumption and operating costs, its widespread application is limited. Therefore, the recondensation and liquefaction recovery method is currently the most commonly used method. The key equipment in this BOG recondensation and liquefaction recovery method is the BOG recondenser. Currently, typical recondensers in China and abroad include packed tower recondensers, static mixer and gas-liquid separator combined recondensing devices, microporous tube and static mixer combined recondensing towers, compression cooling recondensers, and dual condensation and heat exchange recondensers. The packed tower recondenser is the most widely used.

[0004] The packed tower recondenser consists of an upper packing section and a lower buffer section. BOG enters from the top above the packing section, while LNG enters from the side, leading to a co-current flow of gas and liquid from top to bottom within the recondenser. However, because LNG and BOG are not evenly distributed within the recondenser's packing layer, gas-liquid contact is insufficient, and BOG condensation is incomplete. This results in a complex internal structure design for the recondenser, high gas-liquid flow resistance, bulky equipment, and high investment.

[0005] A recondensing unit combines a static mixer and a gas-liquid separator. LNG enters from one end of the static mixer, while BOG enters from the middle and then enters the gas-liquid separator. Although this recondenser has a simple structure, the uneven distribution of BOG in the static mixer means some BOG remains uncondensed by the LNG, and its mixed condensing efficiency needs to be further improved.

[0006] In a recondenser combining microporous tubes and a static mixer, BOG entering the recondenser is dispersed in the LNG as microbubbles. Theoretically, this results in sufficient gas-liquid contact. However, this results in uneven distribution of BOG within the tube bundle, and uneven distribution of LNG outside the bundle. Furthermore, after entering the tube bundle from the bottom of the tower, BOG must pass through the micropores to reach the outer surface of the bundle, where it flows upwards into the static mixer unit along with the LNG outside the bundle. This creates significant flow resistance, high power consumption, and bulky equipment, requiring dedicated storage tanks for the hot LNG.

[0007] The compression-cooling recondenser converts BOG into liquid through two steps: compression and cooling, so the energy consumption is relatively high.

[0008] The dual heat exchanger-condensing recondenser consists of a first heat exchanger, a first condenser, a second heat exchanger, a second condenser, a refrigerant storage tank, and an LNG buffer tank. The first heat exchanger and first condenser are coupled in one device, while the second heat exchanger and second condenser are coupled in another device. These two devices rely on the refrigerant to condense BOG in series, resulting in limited condensation efficiency and high energy consumption.

[0009] At present, the common problems of BOG recondensers in operation at home and abroad are: (1) uneven distribution of LNG and BOG, insufficient gas-liquid contact, and the BOG recondensation effect needs to be improved. (2) The BOG recondensation process consumes a lot of power and energy. (3) The recondenser equipment has high investment, large size, large floor space, and is difficult to use and maintain. Summary of the Invention

[0010] 1. Technical problems to be solved: In response to the above technical problems, the present invention provides a micro-interface vacuum BOG recondenser and recondensation method, which can effectively solve the problems of uneven distribution of LNG and BOG in the recondenser, insufficient gas-liquid contact, poor condensation effect, high energy consumption and large equipment size.

[0011] 2. Technical solution: A micro-interface vacuum BOG recondenser features an LNG channel for passing LNG, a BOG buffer chamber for passing BOG, a gas-liquid mixing chamber for mixing LNG and BOG, a recondensing section for recondensing the mixed gas and liquid, and an LNG buffer tank. The BOG buffer chamber is equipped with a micro-interface BOG plate structure. Gas entering the BOG buffer chamber forms a microinterface through the microporous channels provided by the micro-interface BOG plate structure before entering the gas-liquid mixing chamber for mixing. The mixed fluid then passes into the recondensing section for phase change condensation. The recondensed fluid then enters the LNG buffer tank. Furthermore, the LNG channel is funnel-shaped, with the inlet of the funnel being the LNG inlet. The upper end of the funnel is a cylindrical LNG guide tube, below which is a truncated cone-shaped LNG flow channel contraction section with a preset contraction angle, and the outlet of the funnel is the LNG nozzle. The LNG channel and the BOG buffer chamber are an inner and outer tube sleeve structure with a common central axis. The shell of the BOG buffer chamber is adapted to the shape of the LNG channel, and a BOG inlet is provided on the side wall corresponding to the position of the LNG guide tube. The micro-interface BOG plate structure is a micro-interface BOG annular plate located in the cavity between the LNG guide tube and the shell of the BOG buffer chamber. The shell of the gas-liquid mixing chamber wraps around the periphery of the nozzle and is integrally connected to the bottom end of the shell of the BOG buffer chamber.

[0012] The recondensing section is cylindrical and filled with fillers for recondensation; the fillers include one or more of step ring distribution, saddle ring distribution, yoke ring distribution, wire mesh corrugated distribution, and orifice plate corrugated distribution; the input end of the recondensing section is connected to the BOG buffer chamber, and the output end is connected to the trumpet-shaped LNG flow channel expansion section, and the liquid output through the LNG flow channel expansion section is output to the LNG buffer tank; the recondensing section and the LNG flow channel expansion section are both located in the inner cavity of the LNG buffer tank.

[0013] Furthermore, the preset contraction angle of the contraction section of the LNG flow channel, i.e., the apex angle of the cone where the frustum is located, ranges from 15° to 30°; there are two BOG inlets, which are evenly and symmetrically distributed; and the expansion angle of the expansion section of the LNG flow channel is 4° to 8°.

[0014] Furthermore, the preset contraction angle of the LNG channel is in the range of 20° to 25°; and the expansion angle of the expansion section of the LNG flow channel is in the range of 4° to 6°.

[0015] Furthermore, a plurality of micropores processed by laser or electron beam are provided on the surface of the micro-interface BOG plate structure; the micropores have an aperture of 400-800 nm; and the micropores are arranged in a regular hexagonal pattern.

[0016] Furthermore, the LNG inlet is connected to the flange by welding; the LNG guide pipe is connected to the LNG flow channel contraction section by welding; the LNG nozzle is connected to the truncated cone by threads to achieve adjustable nozzle length.

[0017] Furthermore, the ratio of the diameter of the LNG nozzle to the diameter of the LNG draft tube is in the range of 0.25 to 0.75; and the ratio of the diameter of the recondensing section to the diameter of the LNG nozzle is in the range of 1.2 to 1.5.

[0018] Furthermore, it also includes a support ring for fixing the micro-interface BOG annular plate; the lower end surface of the micro-interface BOG annular plate is fixed on the support ring through a tongue and groove structure.

[0019] Furthermore, the LNG channel and the BOG buffer chamber are both installed vertically or horizontally.

[0020] A micro-interface vacuum BOG recondensation method is disclosed. LNG enters the LNG draft tube through the LNG inlet and then into the LNG flow channel contraction section. In the LNG flow channel contraction section, as the flow channel cross-section continues to shrink, the fluid velocity gradually increases while the pressure decreases. Finally, the BOG flows out of the nozzle into a gas-liquid mixing chamber, generating a high degree of vacuum. After entering the BOG buffer chamber from the BOG inlet, the BOG passes through the micro-interface BOG plate structure under the vacuum suction of the gas-liquid mixing chamber, dispersing into microbubbles of 400-600 nm. The BOG enters the gas-liquid mixing chamber and mixes evenly with the high-speed LNG flowing from the nozzle. The BOG then enters a condensation section filled with fillers, undergoing phase change condensation. The resulting fluid leaves the condensation section and enters the LNG flow channel expansion section. As the flow channel cross-section continues to expand, the fluid velocity gradually decreases while the pressure increases. The fluid has a low pressure at the inlet of the LNG flow channel expansion section and a high pressure at the outlet. Under the action of reverse pressure, a large number of vortices appear in the LNG flow channel expansion section, enhancing gas-liquid mixing contact. Phase change condensation of the BOG occurs again in the LNG flow channel expansion section.

[0021] 3.Beneficial effects: (1) This method discloses a micro-interface vacuum BOG recondenser and recondensation method, which uses a micro-interface distribution plate in the BOG buffer chamber to achieve uniform gas distribution. BOG evaporated gas enters the buffer chamber through two symmetrical BOG inlets, ensuring that the BOG is relatively evenly distributed in the gas buffer chamber. On this basis, a gas distribution plate with 400-600 nm micropores is set between the gas buffer chamber and the gas-liquid mixing chamber, ensuring the uniformity of the gas in the gas-liquid mixing chamber and providing a guarantee for uniform and sufficient contact between the gas and the liquid.

[0022] (2) The present method discloses a micro-interface vacuum BOG recondenser and recondensation method, which designs a special LNG flow channel contraction structure to reduce the energy consumption of the condensation process. When LNG enters the flow channel contraction section through the guide tube, as the flow channel cross-section continues to decrease, the liquid flow rate continues to increase and the pressure continues to decrease. When the liquid flows out through the nozzle through the LNG, the cross-section here is the smallest, the liquid flow rate reaches the maximum, and the pressure is at the lowest and less than one atmosphere, generating a higher vacuum degree for sucking BOG gas from the micro-interface distribution plate, thereby greatly reducing the pressure delivery requirements for BOG gas and reducing the BOG compression energy consumption. In addition, in the recondenser of the present invention, both gas and liquid flow downward, the flow resistance is small, and the energy consumption is also reduced.

[0023] (3) This method uses a packing condensation section and a special LNG flow channel expansion structure to ensure sufficient gas-liquid contact and high recondensation efficiency. The packing condensation section belongs to the BOG first phase change condensation. Various types of packing are filled in the condensation section, providing a large number of complex curved channels for LNG and BOG, and at the same time providing a huge specific surface area for the contact between LNG and BOG, so that the gas-liquid contact is sufficient and the BOG recondensation efficiency is high. The flow channel expansion section belongs to the BOG second phase change condensation. When LNG enters the inlet of the flow channel expansion section, the flow channel cross-sectional area is small, the fluid flow rate is large and the pressure is low. As the flow channel cross-sectional area gradually expands, the fluid flow rate continues to decrease, while the fluid pressure continues to increase. At the outlet of the flow channel expansion section, the cross-sectional area is the largest, the flow rate is the smallest, and the pressure is the largest. Therefore, there is a reverse pressure difference at the inlet and outlet of the flow channel expansion section that is opposite to the fluid flow direction, resulting in a large number of vortices in the fluid expansion section, which greatly enhances the gas-liquid contact opportunity and significantly improves the BOG phase change condensation effect.

[0024] In summary, the micro-interface vacuum BOG recondenser of the present invention has a main fluid channel composed of a guide tube, a flow channel contraction section, a nozzle, a condensation section, a flow channel expansion section, etc., which are all on the same center line. It has an ingenious and simple structure, a small size, and a small footprint. It can be used in LNG carriers, LNG receiving stations, LNG storage tanks, and other occasions. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is an overall cross-sectional view of a micro-interface vacuum BOG recondenser in a specific embodiment; Figure 2 Schematic diagram of micropore distribution on the surface of a micro-interface BOG plate structure in a specific embodiment; Figure 3 Schematic diagram of the LNG flow channel contraction section in a specific embodiment; Figure 4 is a schematic diagram of the recondensation section and the packing in a specific embodiment; Figure 5 It is a schematic diagram of the LNG flow channel expansion section in a specific embodiment.

[0026] Figure numerals: 1. LNG inlet; 2. LNG draft tube; 3. BOG inlet; 4. BOG buffer chamber; 5. Micro-interface BOG annular plate; 6. LNG nozzle; 7. LNG flow channel contraction section; 8. Gas-liquid mixing chamber; 9. Condensation section; 10. Packing; 11. LNG flow channel expansion section; 12. LNG buffer tank; 13. Micropore. DETAILED DESCRIPTION

[0027] The present invention will be described in detail below with reference to the accompanying drawings.

[0028] As attached Figure 1A micro-interface vacuum BOG recondenser is shown. It features an LNG channel for passing LNG, a BOG buffer chamber for passing BOG, a gas-liquid mixing chamber for mixing LNG and BOG, a recondensing section for recondensing the mixed gas and liquid, and an LNG buffer tank. The BOG buffer chamber is equipped with a micro-interface BOG plate structure. Gas entering the BOG buffer chamber forms a microinterface through the microporous channels provided by the micro-interface BOG plate structure before entering the gas-liquid mixing chamber for mixing. The mixed fluid then flows into the recondensing section for phase change condensation. The recondensed fluid then enters the LNG buffer tank. Furthermore, the LNG channel is funnel-shaped, with the inlet of the funnel being the LNG inlet 1. The upper end of the funnel is a cylindrical LNG guide tube 2, below which is a truncated cone-shaped LNG flow channel contraction section 7 with a preset contraction angle, and the outlet of the funnel is the LNG nozzle 6. The LNG channel and the BOG buffer chamber 4 are a concentric inner and outer tube sleeve structure. The shell of the BOG buffer chamber is adapted to the shape of the LNG channel, and a BOG inlet 3 is provided on the side wall corresponding to the position of the LNG guide tube. The micro-interface BOG plate structure is a micro-interface BOG annular plate 5, which is located in the cavity between the LNG guide tube and the shell of the BOG buffer chamber. The shell of the gas-liquid mixing chamber 8 wraps around the nozzle and is integrally connected to the bottom end of the shell of the BOG buffer chamber. As attached Figure 4 As shown, the recondensing section 9 is cylindrical and filled with a filler 10 for recondensation; the filler includes one or more of a stepped ring distribution, a saddle-shaped distribution, a yoke-ring distribution, a wire mesh corrugated distribution, and a orifice plate corrugated distribution; the input end of the recondensing section is connected to the BOG buffer chamber, and the output end is connected to the trumpet-shaped LNG flow channel expansion section 11, and the liquid output through the LNG flow channel expansion section is output to the LNG buffer tank 12; the recondensing section and the LNG flow channel expansion section are both located in the inner cavity of the LNG buffer tank.

[0029] As attached Figure 3 、 5 As shown, the preset contraction angle of the contraction section of the LNG flow channel, i.e., the apex angle of the cone where the frustum is located, ranges from 15° to 30°; there are two BOG inlets, which are evenly and symmetrically distributed; and the expansion angle of the expansion section of the LNG flow channel is 4° to 8°.

[0030] Furthermore, the preset contraction angle of the LNG channel is in the range of 20° to 25°; and the expansion angle of the expansion section of the LNG flow channel is in the range of 4° to 6°.

[0031] Furthermore, the surface of the micro-interface BOG plate structure is provided with a plurality of micro-pores processed by laser or electron beam; the micro-pore diameter is 400-800 nm; the micro-pores are arranged in a regular hexagonal pattern, as shown in the attached figure. Figure 2 shown.

[0032] Furthermore, the LNG inlet is connected to the flange by welding; the LNG guide pipe is connected to the LNG flow channel contraction section by welding; the LNG nozzle is connected to the truncated cone by threads to achieve adjustable nozzle length.

[0033] Furthermore, the ratio of the diameter of the LNG nozzle to the diameter of the LNG draft tube is in the range of 0.25 to 0.75; and the ratio of the diameter of the recondensing section to the diameter of the LNG nozzle is in the range of 1.2 to 1.5.

[0034] Furthermore, it also includes a support ring for fixing the micro-interface BOG annular plate; the lower end surface of the micro-interface BOG annular plate is fixed on the support ring through a tongue and groove structure.

[0035] Furthermore, the LNG channel and the BOG buffer chamber are both installed vertically or horizontally.

[0036] A micro-interface vacuum BOG recondensation method is disclosed. LNG enters the LNG draft tube through the LNG inlet and then into the LNG flow channel contraction section. In the LNG flow channel contraction section, as the flow channel cross-section continues to shrink, the fluid velocity gradually increases while the pressure decreases. Finally, the BOG flows out of the nozzle into a gas-liquid mixing chamber, generating a high degree of vacuum. After entering the BOG buffer chamber from the BOG inlet, the BOG passes through the micro-interface BOG plate structure under the vacuum suction of the gas-liquid mixing chamber, dispersing into microbubbles of 400-600 nm. The BOG enters the gas-liquid mixing chamber and mixes evenly with the high-speed LNG flowing from the nozzle. The BOG then enters a condensation section filled with fillers, undergoing phase change condensation. The resulting fluid leaves the condensation section and enters the LNG flow channel expansion section. As the flow channel cross-section continues to expand, the fluid velocity gradually decreases while the pressure increases. The fluid has a low pressure at the inlet of the LNG flow channel expansion section and a high pressure at the outlet. Under the action of reverse pressure, a large number of vortices appear in the LNG flow channel expansion section, enhancing gas-liquid mixing contact. Phase change condensation of the BOG occurs again in the LNG flow channel expansion section. Specific embodiment: This embodiment is shown in the attached Figures 1 to 5 As shown, in this embodiment, the LNG channel and BOG buffer chamber are both installed vertically. As shown in the figure, the recondenser comprises: an LNG inlet connected to a flow guide pipe, which is connected to the LNG flow channel's contraction section, with an LNG nozzle connected at the smallest cross-section of the contraction section. A BOG inlet connected to the BOG buffer chamber, within which a micro-interface BOG distribution plate with microporous channels is installed. A condensing section, filled with various fillers, is connected to the flow channel expansion pipe. The condensing section and flow channel expansion section are located within the buffer tank, while the remaining components are located outside the buffer tank.

[0038] In the micro-interface vacuum recondenser of this embodiment, LNG enters the draft tube through the inlet and then the converging section of the flow channel. As the flow channel cross-section continues to shrink, the fluid velocity gradually increases while the pressure decreases, ultimately flowing out of the nozzle into the gas-liquid mixing chamber, generating a high degree of vacuum. After BOG enters the gas buffer chamber from two inlets, it passes through the micro-interface distribution plate under the vacuum suction of the mixing chamber, disperses into microbubbles of 400-600 nm, and enters the gas-liquid mixing chamber. After evenly mixing with the high-speed LNG flowing from the nozzle, the BOG enters the packing-filled condensing section, undergoing phase change condensation. The fluid leaves the condensing section and enters the expanding section of the flow channel. As the flow channel cross-section continues to expand, the fluid velocity gradually decreases while the pressure increases. Therefore, the fluid pressure is low at the inlet of the expanding section and high at the outlet. Under the action of reverse pressure, numerous vortices appear within the expanding section, greatly enhancing the gas-liquid mixing contact, and the BOG undergoes phase change condensation again in the expanding section. Therefore, the micro-interface vacuum recondenser of the present invention has sufficient gas-liquid contact, sufficient BOG phase change condensation and high efficiency, which effectively solves the problems of low efficiency and high energy consumption of existing recondensers.

[0039] Although the present invention has been disclosed above in terms of preferred embodiments, they are not intended to limit the present invention. Anyone skilled in the art can make various changes or modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection defined by the claims of this application.

Claims

1. A micro-interface vacuum BOG recondenser, characterized in that: It includes an LNG channel for passing LNG, a BOG buffer chamber for passing BOG, a gas-liquid mixing chamber for mixing LNG and BOG, a recondensing section for recondensing the mixed gas and liquid, and an LNG buffer tank; wherein the BOG buffer chamber is provided with a micro-interface BOG plate structure, the gas entering the BOG buffer chamber is micro-interfaced through the microporous channel provided with the micro-interface BOG plate structure, and then enters the gas-liquid mixing chamber for mixing, the mixed fluid is passed into the recondensing section to realize phase change condensation of the fluid, and the recondensed fluid enters the LNG buffer tank.

2. The micro-interface vacuum BOG recondenser according to claim 1, characterized in that: The LNG channel is funnel-shaped, the inlet of the funnel is the LNG inlet, the upper end of the funnel is a cylindrical LNG guide pipe, the lower end is a truncated cone-shaped LNG flow channel contraction section with a preset contraction angle, and the outlet of the funnel is the LNG nozzle; the LNG channel and the BOG buffer chamber are in an inner and outer tube sleeve structure with a common central axis; the shell of the BOG buffer chamber is adapted to the shape of the LNG channel, and a BOG inlet is arranged on the side wall corresponding to the position of the LNG guide pipe; the micro-interface BOG plate structure is a micro-interface BOG annular plate, which is located in the cavity between the LNG guide pipe and the shell of the BOG buffer chamber; the shell of the gas-liquid mixing chamber is wrapped around the nozzle and is integrally connected to the bottom end of the shell of the BOG buffer chamber; The recondensing section is cylindrical and filled with fillers for recondensation; the fillers include one or more of step ring distribution, saddle ring distribution, yoke ring distribution, wire mesh corrugation distribution, and orifice plate corrugation distribution; the input end of the recondensing section is connected to the BOG buffer chamber, and the output end is connected to the trumpet-shaped LNG flow channel expansion section, and the liquid output through the LNG flow channel expansion section is output to the LNG buffer tank; the recondensing section and the LNG flow channel expansion section are both located in the inner cavity of the LNG buffer tank.

3. The micro-interface vacuum BOG recondenser according to claim 2, characterized in that: The preset contraction angle of the contraction section of the LNG flow channel, i.e., the vertex angle of the cone where the frustum is located, ranges from 15° to 30°; there are two BOG inlets, which are evenly and symmetrically distributed; and the expansion angle of the expansion section of the LNG flow channel is 4° to 8°.

4. The micro-interface vacuum BOG recondenser according to claim 3, characterized in that: The preset contraction angle of the LNG channel is in the range of 20° to 25°; the expansion angle of the expansion section of the LNG flow channel is in the range of 4° to 6°.

5. The micro-interface vacuum BOG recondenser according to claim 1, characterized in that: The surface of the micro-interface BOG plate structure is provided with a plurality of micro-pores processed by laser or electron beam; the aperture of the micro-pores is 400-800nm; and the distribution of the micro-pores is arranged in a regular hexagon.

6. The micro-interface vacuum BOG recondenser according to claim 2, characterized in that: The LNG inlet is connected to the flange by welding; the LNG guide pipe is connected to the LNG flow channel contraction section by welding; the LNG nozzle is connected to the truncated table by threads to achieve adjustable nozzle length.

7. The micro-interface vacuum BOG recondenser according to claim 2, characterized in that: The ratio of the diameter of the LNG nozzle to the diameter of the LNG guide pipe is in the range of 0.25 to 0.75; the ratio of the diameter of the recondensing section to the diameter of the LNG nozzle is in the range of 1.2 to 1.

5.

8. The micro-interface vacuum BOG recondenser according to claim 2, characterized in that: It also includes a support ring for fixing the micro-interface BOG annular plate; the lower end surface of the micro-interface BOG annular plate is fixed on the support ring through a tongue and groove structure.

9. The micro-interface vacuum BOG recondenser according to claim 2, characterized in that: The LNG channel and the BOG buffer chamber are both installed vertically or horizontally.

10. A micro-interface vacuum BOG recondensation method, using the recondenser according to any one of claims 1 to 9 to achieve recondensation, characterized in that: LNG first enters the LNG guide pipe through the LNG inlet, and then enters the LNG flow channel contraction section; in the LNG flow channel contraction section, as the flow channel cross section continues to shrink, the fluid velocity gradually increases and the pressure continues to decrease, and finally flows out from the nozzle into the gas-liquid mixing chamber, while generating a high vacuum degree; after BOG enters the BOG buffer chamber from the BOG inlet, under the vacuum suction of the gas-liquid mixing chamber, BOG passes through the micro-interface BOG plate structure, disperses into micro bubbles of 400-600nm and enters the gas-liquid mixing chamber, and after being uniformly mixed with the high-speed LNG flowing out of the nozzle, enters the condensation section equipped with fillers to undergo phase change condensation; the generated fluid leaves the condensation section and enters the LNG flow channel expansion section. As the flow channel cross section continues to increase, the fluid velocity gradually decreases and the pressure continues to increase; the fluid has a low pressure at the inlet of the LNG flow channel expansion section and a high pressure at the outlet. Under the action of the reverse pressure, a large number of vortices appear in the LNG flow channel expansion section, which strengthens the gas-liquid mixing contact, and BOG undergoes phase change condensation again in the LNG flow channel expansion section.

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