A jet flow type LNG evaporation gas recovery apparatus and method

Abstract

The application discloses a kind of spray drainage type LNG evaporation gas recovery equipment and method, belong to evaporation gas recovery technical field, improve the adaptability of recovery equipment in different gas flow range, solve the problem of many process equipment, can also be used normally under the process of no BOG compressor, realize the effect of wide gas flow range, equipment table piece is less, heat exchange efficiency is high, technical scheme includes outer pipe, the inner pipe, mixing chamber and expansion chamber are sequentially arranged in the outer pipe;The inner tube is provided with a tapered section inward, and a small straight pipe section is provided at the outlet;Gas flow channel is formed between the inner tube and the outer tube, and spiral blades and porous discs are arranged in the gas flow channel.

Description

Technical Field

[0001] This invention belongs to the field of evaporation gas recovery technology, specifically relating to a jet-induced LNG evaporation gas recovery device and method. Background Technology

[0002] The statements herein provide only background information in relation to this invention and do not necessarily constitute prior art.

[0003] During storage, unloading, and transportation, liquefied natural gas (LNG) may be partially or completely vaporized into natural gas. The gas produced in this vaporization process is called liquefied gas (BOG). The processing technology for liquefied gas mainly includes direct compression and re-condensation liquefaction. The main equipment in the re-condensation process is the BOG re-condenser, which uses the cooling capacity of pressurized LNG to condense the liquefied gas into a liquid state.

[0004] Before entering the recondenser, LNG is pressurized by a low-pressure pump to become subcooled LNG, while BOG (Boiling Gas) is pressurized by a compressor to become superheated gas. LNG from the low-pressure output pipeline is split into two streams: one stream enters the recondenser to provide cooling for the superheated BOG, and the other stream bypasses the pipeline to regulate flow and ensure downstream pressure meets process requirements. The BOG condensed in the recondenser mixes with the bypass LNG and then enters the high-pressure pump. Sufficient LNG is needed for complete condensation of the evaporator gas. If the LNG load is low, the packing surface cannot be effectively wetted, reducing mass transfer efficiency and preventing complete condensation of the evaporator gas. Therefore, its application range is narrow, and the recondensation process involves numerous equipment and is complex. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a jet-driven LNG evaporation gas recovery device and method, which improves the adaptability of the recovery device to different gas flow ranges, solves the problem of numerous process equipment, and can be used normally even in processes without BOG compressors. It achieves the effects of a wide applicable gas flow range, fewer equipment components, and high heat exchange efficiency.

[0006] To achieve the above objectives, the present invention provides the following technical solution: Firstly, the present invention provides a jet-driven LNG evaporation gas recovery device, comprising an outer pipe, which is divided into a straight section and a tapering section; an inner pipe is disposed inside the outer pipe, which is also divided into a straight section and a tapering section; a perforated disc is disposed at one end of the tapering section of the outer pipe, and one end of the tapering section of the inner pipe is connected to the perforated disc; a mixing chamber is connected to one end of the outer ring of the perforated disc, and the other end of the mixing chamber is connected to an expansion chamber.

[0007] An evaporation gas inlet is provided on one side of the outer pipe, and the evaporation gas inlet is located in the straight section of the outer pipe; an LNG inlet is provided at one end of the straight section of the inner pipe, and an LNG outlet is provided at one end of the tapering section of the inner pipe.

[0008] As a further technical solution, the porous disk is composed of an inner ring and an outer ring, one end of the tapered section of the outer tube is connected to one side of the outer ring of the porous disk, and one end of the tapered section of the inner tube is connected to the inner ring of the porous disk.

[0009] As a further technical solution, the diameter of the outer tube is larger than the diameter of the inner tube, and a gas flow channel is formed between the inner tube and the outer tube; the cross-sectional area of ​​the gas flow channel gradually decreases.

[0010] As a further technical solution, the LNG outlet is equipped with a straight pipe section.

[0011] As a further technical solution, a spiral blade is provided inside the gas flow channel.

[0012] As a further technical solution, the spiral blades are divided into multiple segments, and the spiral blades are distributed alternately along the gas flow channel, with the twist angle of the spiral blades gradually increasing; the number of each segment of the spiral blades is the same, and the stagger angle of each segment is the same.

[0013] As a further technical solution, the porous disk is provided with multiple sets of air holes.

[0014] As a further technical solution, the cross-sectional area of ​​the expansion chamber is larger than that of the mixing chamber, and the expansion chamber is horn-shaped.

[0015] As a further technical solution, the evaporation gas inlet, LNG inlet, and mixed fluid outlet are equipped with connecting flanges.

[0016] Secondly, the present invention also provides a method for operating a jet-driven LNG evaporation gas recovery device, comprising the following steps:

[0017] S1. LNG enters the mixing chamber through the LNG inlet at the outer end of the inner pipe. It expands and accelerates at the LNG outlet, enters the mixing chamber at high speed and forms a low-pressure zone. Due to the pressure difference, the vapor gas is entrained and enters the gas flow channel through the vapor gas inlet, and obtains a certain speed through the spiral blades.

[0018] S2. The fluids are dispersed through a porous disk and enter the mixing chamber at a certain angle. The two fluids are mixed in the mixing chamber, and momentum and energy are exchanged. Some of the evaporated gas releases heat and liquefies into LNG.

[0019] S3. The gas-liquid mixed phase fluid flowing out of the mixing chamber enters the diffuser chamber, where some of the kinetic energy is converted into pressure energy. The fluid velocity decreases and the pressure increases, further promoting the mixing and heat exchange of the gas and liquid phases. The mixture then flows out of the equipment together from the outlet.

[0020] The beneficial effects of the present invention are as follows:

[0021] The jet-driven LNG vapor gas recovery equipment of this invention optimizes the mixing and entry methods of the gas and liquid two-phase fluids compared to traditional LNG vapor gas recovery equipment. An inner tube is installed inside the equipment, allowing the liquid phase to undergo depressurization and acceleration as it passes through, thus entraining the gas in the tank. Both phases then enter the mixing chamber for mixing and heat exchange. The inner tube outlet uses a straight section, ensuring that the liquid phase reaches a pressure sufficient to entrain the gas phase without depressurizing to the point of vaporization. This improves the adaptability of the LNG vapor gas recovery equipment within different gas flow ranges and offers advantages such as fewer equipment components, smaller footprint, easier maintenance, and higher heat exchange efficiency.

[0022] The jet-guided LNG vapor gas recovery equipment of this invention, compared with traditional LNG vapor gas recovery equipment, adopts a gas-liquid dual-channel structure. This allows the gas and liquid to pass through independent channels before entering the mixing chamber, where they are then mixed, ensuring uniform gas entry. Furthermore, the gas channel is equipped with helical blades and porous discs, which draw out the vapor gas generated in the storage tank, creating a helical flow before entering the mixing chamber. This increases the turbulence intensity of the vapor gas and promotes its uniform distribution. Passing through the porous discs before entering the mixing chamber, the vapor gas is buffered while still being able to enter the mixing chamber cavity uniformly through multiple pores. This gas-liquid mixing method reduces collisions caused by sudden contact between the gas and liquid, enhances turbulence intensity and the effective gas-liquid mixing area, and allows for more uniform gas distribution in the liquid phase, thus improving the equipment's mixing efficiency and heat exchange capacity. Attached Figure Description

[0023] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0024] Figure 1 This is a schematic diagram of the jet-driven LNG evaporation gas recovery device of the present invention;

[0025] Figure 2 This is a schematic diagram of the structure of the spiral blade inside the gas flow channel of the present invention;

[0026] Figure 3 This is a schematic diagram of the porous disk structure inside the gas flow channel of the present invention.

[0027] In the diagram: 1. Outer pipe; 2. Spiral blade; 3. Porous disk; 4. Mixing chamber; 5. Expansion chamber; 6. Mixed fluid outlet; 7. LNG outlet; 8. LNG inlet; 9. Inner pipe; 10. Evaporated gas inlet; 11. Pore; 12. Outer ring; 13. Inner ring; 14. Gas flow channel. Detailed Implementation

[0028] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0029] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, unless otherwise expressly indicated by the invention, the singular form is also intended to include the plural form. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0030] For ease of description, the words "up," "down," "left," and "right" appearing in this invention only indicate that they are consistent with the up, down, left, and right directions of the accompanying drawings themselves, and do not limit the structure. They are merely for the purpose of facilitating the description of this invention and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0031] Terminology Explanation: In this invention, terms such as “installation,” “connection,” “linking,” and “fixing” should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components or the interaction relationship between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0032] As described in the background section, traditional LNG vapor gas recovery equipment recovers LNG vapor gas through direct compression and re-condensation. However, this process suffers from high energy consumption, large footprint, and narrow application range. To address these technical issues, this application proposes a jet-driven LNG vapor gas recovery equipment, which has good adaptability, low heat load, and its vapor gas recovery efficiency is less affected by the amount of vapor gas processed.

[0033] In a typical embodiment of the present invention, such as Figure 1As shown, a jet-driven LNG evaporation gas recovery device is provided, including an outer pipe 1. An evaporation gas inlet 10 is provided on one side of the outer pipe 1. The outer pipe 1 is divided into a straight section and a tapering section, with the evaporation gas inlet 10 located in the straight section. An inner pipe 9 is provided inside the outer pipe 1. The inner pipe 9 is divided into a straight section and a tapering section. An LNG inlet 8 is provided at one end of the straight section of the inner pipe 9, and an LNG outlet 7 is provided at one end of the tapering section. A perforated disc 3 is provided at one end of the tapering section of the outer pipe 1. The perforated disc 3 consists of an inner ring 13 and an outer ring 12. One end of the tapering section of the outer pipe 1 is connected to one side of the outer ring 12 of the perforated disc 3, and one end of the tapering section of the inner pipe 9 is connected to the inner ring 13 of the perforated disc 3. One end of a mixing chamber 4 is connected to the other side of the outer ring 12 of the perforated disc 3, and the other end of the mixing chamber 4 is connected to an expansion chamber 5. The jet-driven LNG evaporation gas recovery equipment of the present invention improves the adaptability of LNG evaporation gas recovery equipment in different gas phase flow ranges, and has the advantages of fewer equipment components, smaller footprint, easy inspection and maintenance, and high heat exchange efficiency.

[0034] The outer tube 1 is placed horizontally and is divided into a straight section and a tapering section. One end of the tapering section of the outer tube 1 is connected to one side of the outer ring 12 of the porous disk 3. The inner tube 9 is located inside the outer tube 1. An LNG inlet 8 is located at the outer end of the inner tube 9, and an LNG outlet 7 is located at the other end. The diameter of the outer tube 1 is larger than the diameter of the inner tube 9, and a gas flow channel 14 is formed between the inner tube 9 and the outer tube 1. An evaporation gas inlet 10 is located above the gas flow channel 14 on the outer tube 1. The inner tube 9 is located inside the outer tube. When the liquid phase passes through the inner tube 9, it can be depressurized and accelerated, thereby entraining the gas in the tank. The two phases flow together enter the mixing chamber 4 for mixing and heat exchange. The outlet of the inner tube 9 is designed with a straight section, which can ensure that the liquid phase reaches a pressure that can entrain the gas phase when it passes through, but will not depressurize to a pressure that causes vaporization.

[0035] The outer pipe 1 is connected to a mixing chamber 4 and an expansion chamber 5 at its rear. The mixing chamber 4 and expansion chamber 5 are arranged adjacent to each other, with the mixing chamber 4 located near the converging section. One end of the expansion chamber 5 is connected to the mixing chamber 4, and the other end of the expansion chamber 5 is provided with a mixed fluid outlet 6. This gas-liquid mixing method reduces collisions caused by sudden contact between gas and liquid, enhances turbulence intensity, and allows the gas to be distributed more evenly in the liquid phase, thereby enhancing the mixing efficiency and heat exchange capacity of the equipment.

[0036] The inner pipe 9 is divided into a straight section and a converging section. LNG enters the inner pipe 9 through the LNG inlet 8, and after passing through the converging section, it is accelerated and depressurized before entering the mixing chamber 4 through the LNG outlet 7. A short straight pipe section is provided at the LNG outlet 7 to ensure that the LNG maintains a certain linear velocity when it is injected into the mixing chamber 4 from the inner pipe 9. LNG enters the mixing chamber 4 through the inner pipe, and the evaporated gas enters the mixing chamber 4 and mixes with the LNG due to the pressure difference generated by the LNG passing through the inner pipe 9. The expansion chamber 5 adopts a funnel shape to further mix and exchange heat between the gas and liquid mixture, and the pressure causes all the evaporated gas to liquefy.

[0037] The cross-section of the gas flow channel 14 gradually decreases. A spiral blade 2 is installed inside the gas flow channel 14, and a porous disk 3 is installed at the end of the gas flow channel 14. Figure 2 and Figure 3 As shown. The evaporated gas enters the gas flow channel 14 through the evaporated gas inlet 10, passes through the spiral blade 2 and the porous disk 3, and enters the mixing chamber 4. The arrangement of the gas flow channel 14 ensures that the gas and liquid pass through independent channels before entering the mixing chamber 4, and then mix within the mixing chamber 4, ensuring uniform gas entry.

[0038] The helical blades 2 are arranged in a staggered pattern, with the same number of segments and consistent stagger angles. Each segment of the blade has the same twist angle, which gradually increases as the segment tapers inward. In this example, the twist angle of the helical blades 2 ranges from 30° to 60°.

[0039] The porous disk 3 has a certain arrangement, size and number of pores 11, which are arranged in a concentric circular array. The size and number of pores 11 are determined by a combination of factors such as the amount of evaporative gas processed and the mixing ratio of evaporative gas and LNG.

[0040] The spiral blades 2 create a spiral flow of the evaporated gas before it enters the mixing chamber 4, increasing its kinetic energy and promoting its uniform distribution. The porous disk 3 buffers the evaporated gas while allowing it to enter the mixing chamber 4 uniformly through multiple vents 11. The evaporated gas and LNG pass through independent channels before entering the mixing chamber 4, and then mix within the mixing chamber 4, ensuring uniform entry of the evaporated gas. Furthermore, the spiral blades 2 and porous disk 3 within the gas flow channel 14 create a spiral flow of the gas before it enters the mixing chamber 4, increasing its kinetic energy and promoting its uniform distribution. Before entering the mixing chamber 4, the gas passes through the porous disk 3, which buffers it while allowing it to enter the mixing chamber 4 uniformly through multiple vents.

[0041] The working principle of the jet-induced LNG vapor gas recovery equipment is as follows: LNG enters the inner pipe 9 through the LNG inlet 8, forming a jet at the LNG outlet 7. The pressure decreases and the velocity increases, entraining vapor gas with even lower pressure. The vapor gas enters the gas flow channel 14 from the vapor gas inlet 10, gains a certain velocity through the spiral blades 2, and then passes through the porous disc 3, where it is dispersed into bubbles or jets and enters the mixing chamber 4 at a certain angle, where it mixes and exchanges heat with the LNG. The mixed fluid enters the expansion chamber 5, where the expansion structure promotes further heat exchange and increases the liquefaction rate. Furthermore, the expansion structure increases the fluid pressure and reduces the flow velocity to meet subsequent transportation requirements.

[0042] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A jet-driven LNG evaporation gas recovery device, characterized in that, The device includes an outer tube, which is divided into a straight section and a tapering section; an inner tube is disposed inside the outer tube, which is also divided into a straight section and a tapering section; a porous disc is disposed at one end of the tapering section of the outer tube, and the porous disc is provided with multiple sets of air holes; one end of the tapering section of the inner tube is connected to the porous disc; one end of a mixing chamber is connected to the other side of the outer ring of the porous disc, and the other end of the mixing chamber is connected to an expansion chamber. An evaporation gas inlet is provided on one side of the outer pipe, and the evaporation gas inlet is located in the straight section of the outer pipe; an LNG inlet is provided at one end of the straight section of the inner pipe, and an LNG outlet is provided at one end of the tapering section of the inner pipe.

2. The jet-driven LNG evaporation gas recovery device as described in claim 1, characterized in that, The porous disk consists of an inner ring and an outer ring. One end of the tapered section of the outer tube is connected to one side of the outer ring of the porous disk, and one end of the tapered section of the inner tube is connected to the inner ring of the porous disk.

3. The jet-driven LNG evaporation gas recovery device as described in claim 1, characterized in that, The diameter of the outer tube is larger than that of the inner tube, and a gas flow channel is formed between the inner tube and the outer tube; the cross-sectional area of ​​the gas flow channel gradually decreases.

4. The jet-driven LNG evaporation gas recovery device as described in claim 1, characterized in that, A straight pipe section is provided at the LNG outlet.

5. The jet-driven LNG evaporation gas recovery device as described in claim 3, characterized in that, The gas flow channel is equipped with spiral blades.

6. The jet-driven LNG evaporation gas recovery device as described in claim 5, characterized in that, The spiral blades are divided into multiple segments, which are staggered along the gas flow channel, and the twist angle of the spiral blades gradually increases; each segment of the spiral blades has the same number of segments, and each segment is staggered by the same angle.

7. The jet-driven LNG evaporation gas recovery device as described in claim 1, characterized in that, The cross-sectional area of ​​the expansion chamber is larger than that of the mixing chamber, and the expansion chamber is funnel-shaped.

8. The jet-driven LNG evaporation gas recovery device as described in claim 1, characterized in that, The evaporator gas inlet, LNG inlet, and mixed fluid outlet are all equipped with connecting flanges.

9. The operating method of a jet-driven LNG evaporation gas recovery device as described in any one of claims 1-8, characterized in that, Includes the following steps: S1. LNG enters the mixing chamber through the LNG inlet at the outer end of the inner pipe. It expands and accelerates at the LNG outlet, enters the mixing chamber at high speed and forms a low-pressure zone. Due to the pressure difference, the vapor gas is entrained and enters the gas flow channel through the vapor gas inlet, and obtains a certain speed through the spiral blades. S2. The fluids are dispersed through a porous disk and enter the mixing chamber at a certain angle. The two fluids are mixed in the mixing chamber, and momentum and energy are exchanged. Some of the evaporated gas releases heat and liquefies into LNG. S3. The gas-liquid mixed phase fluid flowing out of the mixing chamber enters the diffuser chamber, where some of the kinetic energy is converted into pressure energy. The fluid velocity decreases and the pressure increases, further promoting the mixing and heat exchange of the gas and liquid phases. The mixture then flows out of the equipment together from the outlet.

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