阅读说明：本技术 一种天然气液化方法 (Natural gas liquefaction method ) 是由 狄风君 徐浩 *** 于 2019-09-18 设计创作，主要内容包括：本发明涉及天然气液化技术领域,具体的说是一种天然气液化方法,该液化方法采用的液化装置包括绝热结构、冷媒介质输送结构、天然气输送结构和液气分离结构,冷媒介质输送结构的内壁固定安装有天然气输送结构,天然气输送结构和冷媒介质输送结构之间固定安装有液气分离结构,绝热结构包括护壳、壳盖和底板,护壳的上侧螺丝固定有壳盖,壳盖的中部设有检修口,本发明所述的一种天然气液化方法,通过冷媒介质输送结构和天然气输送结构的设置,高压天然气从气体进管进入气液两相空间,并从环形通道沿三号折流板螺旋上升,该过程和内外流体腔内的低温介质充分进行热交换,从而能有效降低高压天然气的温度。(The invention relates to the technical field of natural gas liquefaction, in particular to a natural gas liquefaction method, wherein a liquefaction device adopted by the liquefaction method comprises a heat insulation structure, a cold medium conveying structure, a natural gas conveying structure and a liquid-gas separation structure, wherein the natural gas conveying structure is fixedly arranged on the inner wall of the cold medium conveying structure, the liquid-gas separation structure is fixedly arranged between the natural gas conveying structure and the cold medium conveying structure, the heat insulation structure comprises a protective shell, a shell cover and a bottom plate, the shell cover is fixed on the upper side of the protective shell through screws, and an overhaul port is formed in the middle of the shell cover. Thereby effectively reducing the temperature of the high-pressure natural gas.)

1. a natural gas liquefaction process, characterized by: the liquefaction method comprises the following steps:

S1, preparation of raw material gas: introducing coke oven gas and coal gas into a gas holder, mixing to obtain mixed gas, and performing sulfur-resistant water vapor conversion or CO conversion on 5-50% of the mixed gas₂After reforming, mixing the raw material gas with the rest mixed gas to obtain raw material gas, so as to obtain the material gas meeting the methanation requirement;

S2: compressing the raw material gas in S1, purifying to remove H₂S and CO₂Desulphurizing and recovering the removed hydrogen sulphide, removing CO₂Discharging gas, methanation of purified raw gas, PSA (pressure swing adsorption) separation of the methanated purge gas, and separation of CO and CO₂Returning to purification, carrying out heavy oil hydrogenation on the separated hydrogen to prepare hydrogenated gasoline blend oil or hydrogenated diesel blend oil, carrying out methanation to obtain methane gas, and dehydrating and compressing the methane gas to prepare a qualified natural gas product;

s3: carrying out low-pressure treatment on the natural gas product in the S2 to form low-pressure natural gas, and then introducing the low-pressure natural gas into a liquefying device for liquefying;

the liquefaction device adopted in the step S3 comprises a heat insulation structure (1), a refrigerant medium conveying structure (2), a natural gas conveying structure (3) and a liquid-gas separation structure (4), wherein the refrigerant medium conveying structure (2) is fixedly installed inside the heat insulation structure (1), the natural gas conveying structure (3) is fixedly installed on the inner wall of the refrigerant medium conveying structure (2), and the liquid-gas separation structure (4) is fixedly installed between the natural gas conveying structure (3) and the refrigerant medium conveying structure (2); adiabatic structure (1) is including protecting shell (11), cap (12) and bottom plate (19), the upside screw fixation of protecting shell (11) has cap (12), the middle part of cap (12) is equipped with access hole (13), screw fixation has sealed lid (14) on the ring flange of access hole (13), the downside screw fixation of protecting shell (11) has bottom plate (19), it is equipped with gas-supply pipe (16) and evacuation pipe (15) to inlay on the lower part outer wall of protecting shell (11), install check valve (18) on evacuation pipe (15), install governing valve (17) on gas-supply pipe (16), the welding of protecting shell (11) inner wall has a plurality of connecting plates (110).

2. A natural gas liquefaction process according to claim 1, characterised in that: the refrigerant medium conveying structure (2) comprises an outer sleeve (21), an inner sleeve (22), a first baffle plate (23), a second baffle plate (24), a filling rod (25), an upper cylinder cover (26), a lower cylinder cover (27), a medium inlet pipe (210), a guide pipe (211) and a medium outlet pipe (212), the outer sleeve (21) is located in a protective shell (11), the outer wall of the outer sleeve (21) is welded with a connecting plate (110), the upper side and the lower side of the outer sleeve (21) are fixedly connected with the upper cylinder cover (26) and the lower cylinder cover (27) respectively, the inner sleeve (22) is fixedly connected between the upper cylinder cover (26) and the lower cylinder cover (27) and located in the outer sleeve (21), the first baffle plate (23) is fixedly connected to the inner wall of the outer sleeve (21), the second baffle plate (24) is fixedly connected to the inner wall of the inner sleeve (22), and the filling rod (25) is sleeved in the second baffle plate (, fill the both ends of pole (25) respectively with last cover (26) and lower cover (27) fixed connection, the upper portion outer wall of outer sleeve (21) inlays and is equipped with medium and advances pipe (210), the inside of going up cover (26) and the upside that is located inner sleeve (22) inlays and is equipped with medium exit tube (212), be equipped with interior fluid chamber (29) between inner sleeve (22) and filling pole (25), be equipped with outer fluid chamber (28) in outer sleeve (21), the intercommunication has honeycomb duct (211) between interior fluid chamber (29) and outer fluid chamber (28).

3. A natural gas liquefaction process according to claim 1, characterised in that: the natural gas conveying structure (3) comprises a middle sleeve (31), a third baffle plate (32), a return pipe (33), a liquid outlet pipe (34), a gas inlet pipe (35), a three-way valve (36), a flash vapor pipe (37), an outer support (38), an inner support (39) and an arc-shaped pipe (310), wherein the middle sleeve (31) is positioned between the outer sleeve (21) and the inner sleeve (22), the upper end and the lower end of the middle sleeve (31) are respectively and fixedly connected with an upper sleeve cover (26) and a lower sleeve cover (27), the third baffle plate (32) is fixedly connected between the middle sleeve (31) and the inner sleeve (22), the liquid outlet pipe (34) and the gas inlet pipe (35) are embedded between the middle sleeve (31) and the inner sleeve (22) in the lower sleeve cover (27), the return pipe (33) is embedded between the middle sleeve (31) and the inner sleeve (22) in the upper sleeve cover (26), the utility model discloses a flash steam generator, including lower cover (27), middle sleeve (31) and inner skleeve (22), the upside of lower cover (27) just is located between fixed screw has inner support (39), arc pipe (310) are installed to the upside of inner support (39), a plurality of orifice (311) have been seted up on arc pipe (310), arc pipe (310) intercommunication has flash steam pipe (37), flash steam pipe's (37) one end is passed lower cover (27) and is connected with three-way valve (36), three-way valve (36) are installed on medium exit tube (212), flash steam pipe (37) are through outer support (38) and protective case (11) inner wall fixed connection.

4. A natural gas liquefaction process according to claim 1, characterised in that: liquid-gas separation structure (4) include top separation board (41), bottom separation board (42), pack (43), angle steel (44) and angle steel (45) down, top separation board (41) and bottom separation board (42) all overlap the outside of establishing at inner skleeve (22), and top separation board (41) and bottom separation board (42) outer fringe all with middle sleeve (31) welding, fill filler (43) between top separation board (41) and bottom separation board (42), the upside welding of top separation board (41) has angle steel (45) on, the downside welding of bottom separation board (42) has angle steel (44) down, angle steel (45) and angle steel (44) all with middle sleeve (31) inner wall welding, a plurality of gas pockets (46) have all been seted up in top separation board (41) and the bottom separation board (42).

5. A natural gas liquefaction process according to claim 2, characterised in that: the outer fluid cavity (28) is located between the outer sleeve (21) and the middle sleeve (31), and the first baffle plate (23), the second baffle plate (24) and the third baffle plate (32) are all in spiral structures.

6. a natural gas liquefaction process according to claim 3, characterised in that: the height of the port of the gas inlet pipe (35) is higher than that of the port of the liquid outlet pipe (34), and the central angle of the arc-shaped pipe (310) is an obtuse angle.

7. a natural gas liquefaction process according to claim 4, characterised in that: the upper separation plate (41) and the lower separation plate (42) are both in circular ring structures, and the liquid-gas separation structure (4) is positioned above the third baffle plate (32).

Technical Field

the invention relates to the technical field of natural gas liquefaction, in particular to a natural gas liquefaction method.

Background

natural gas is a combustible gas in the formation, mainly a mixture of low molecular alkanes, and can be divided into dry natural gas and wet natural gas, wherein the dry gas mainly contains methane, and the wet natural gas contains a large amount of ethane, propane, butane and the like besides methane. The liquefied natural gas is liquid after being compressed and cooled to the boiling point (-161.5 ℃), and is usually stored in a low-temperature storage tank at-161.5 ℃ and about 0.1 MPa. The main component of the methane is methane, and the methane is transported by a special ship or an oil tank truck and is gasified again when in use.

when liquefying natural gas in a hot environment, the liquefaction of natural gas is carried out in the condenser, need will be constantly with the low pressure gas and the high-pressure gas heat transfer of expansion cooling, through manifold cycles back, natural gas in the condenser reaches the liquefaction and requires just can liquefy, when liquefying a large amount of natural gas, this process need go on in thermal-insulated environment, and current condenser heat exchange efficiency is not high, can not satisfy the requirement of a large amount of liquefaction of natural gas, consequently, propose a natural gas liquefaction method to above-mentioned problem.

Disclosure of Invention

The invention provides a natural gas liquefaction method aiming at the problems in the prior art.

The technical scheme adopted by the invention for solving the technical problems is as follows: a natural gas liquefaction process, the liquefaction process comprising the steps of:

s1, preparation of raw material gas: introducing coke oven gas and coal gas into a gas holder, mixing to obtain mixed gas, and performing sulfur-resistant water vapor conversion or CO conversion on 5-50% of the mixed gas₂After reforming, mixing the raw material gas with the rest mixed gas to obtain raw material gas, so as to obtain the material gas meeting the methanation requirement;

S2: compressing the raw material gas in S1, purifying to remove H₂S and CO₂Desulphurizing and recovering the removed hydrogen sulphide, removing CO₂Discharging gas, methanation of purified raw gas, PSA (pressure swing adsorption) separation of the methanated purge gas, and separation of CO and CO₂Returning to purification, carrying out heavy oil hydrogenation on the separated hydrogen to prepare hydrogenated gasoline blend oil or hydrogenated diesel blend oil, carrying out methanation to obtain methane gas, and dehydrating and compressing the methane gas to prepare a qualified natural gas product;

S3: carrying out low-pressure treatment on the natural gas product in the S2 to form low-pressure natural gas, and then introducing the low-pressure natural gas into a liquefying device for liquefying;

the liquefaction device adopted in the step S3 includes a heat insulation structure, a refrigerant medium conveying structure, a natural gas conveying structure, and a liquid-gas separation structure, the refrigerant medium conveying structure is fixedly installed inside the heat insulation structure, the natural gas conveying structure is fixedly installed on an inner wall of the refrigerant medium conveying structure, and the liquid-gas separation structure is fixedly installed between the natural gas conveying structure and the refrigerant medium conveying structure.

Specifically, adiabatic structure includes protecting casing, cap and bottom plate, the upside screw fixation of protecting casing has the cap, the middle part of cap is equipped with the access hole, the screw fixation has sealed lid on the ring flange of access hole, the downside screw fixation of protecting casing has the bottom plate, inlay on the lower part outer wall of protecting casing and be equipped with gas-supply pipe and evacuation pipe, install the check valve on the evacuation pipe, install the governing valve on the gas-supply pipe, the welding of protecting casing inner wall has a plurality of connecting plates.

Specifically, the cold medium conveying structure comprises an outer sleeve, an inner sleeve, a first baffle plate, a second baffle plate, a filling rod, an upper sleeve cover, a lower sleeve cover, a medium inlet pipe, a flow guide pipe and a medium outlet pipe, wherein the outer sleeve is positioned in a protective shell, the outer wall of the outer sleeve is welded with a connecting plate, the upper side and the lower side of the outer sleeve are respectively and fixedly connected with the upper sleeve cover and the lower sleeve cover, the inner sleeve is fixedly connected between the upper sleeve cover and the lower sleeve cover and positioned in the outer sleeve, the inner wall of the outer sleeve is fixedly connected with the first baffle plate, the inner wall of the inner sleeve is fixedly connected with the second baffle plate, the filling rod is sleeved in the second baffle plate, two ends of the filling rod are respectively and fixedly connected with the upper sleeve cover and the lower sleeve cover, the medium inlet pipe is embedded in the outer wall of the upper part of the outer sleeve cover, the medium outlet pipe is embedded in, an outer fluid cavity is arranged in the outer sleeve, and a flow guide pipe is communicated between the inner fluid cavity and the outer fluid cavity.

Specifically, the natural gas conveying structure comprises a middle sleeve, a third baffle plate, a return pipe, a liquid outlet pipe, a gas inlet pipe, a three-way valve, a flash steam pipe, an outer support, an inner support and an arc-shaped pipe, wherein the middle sleeve is positioned between an outer sleeve and an inner sleeve, the upper end and the lower end of the middle sleeve are respectively fixedly connected with an upper sleeve cover and a lower sleeve cover, the third baffle plate is fixedly connected between the middle sleeve cover and the inner sleeve, the liquid outlet pipe and the gas inlet pipe are embedded between the middle sleeve cover and the inner sleeve in the lower sleeve cover, the return pipe is embedded between the middle sleeve cover and the inner sleeve in the upper sleeve cover, the inner support is fixed on the upper side of the lower sleeve cover and between the middle sleeve and the inner sleeve through screws, the arc-shaped pipe is installed on the upper side of the inner support, a plurality of spray holes are formed in the, one end of the flash steam pipe penetrates through the lower barrel cover to be connected with a three-way valve, the three-way valve is installed on the medium outlet pipe, and the flash steam pipe is fixedly connected with the inner wall of the protective shell through an outer support.

the liquid-gas separation structure comprises an upper separation plate, a lower separation plate, filler, lower angle steel and upper angle steel, wherein the upper separation plate and the lower separation plate are all sleeved outside an inner sleeve, the outer edges of the upper separation plate and the lower separation plate are all welded with an intermediate sleeve, the filler is filled between the upper separation plate and the lower separation plate, the upper angle steel is welded on the upper side of the upper separation plate, the lower angle steel is welded on the lower side of the lower separation plate, the upper angle steel and the lower angle steel are all welded with the inner wall of the intermediate sleeve, and a plurality of air holes are formed in the upper separation plate and the lower separation plate.

Specifically, the outer fluid cavity is located between the outer sleeve and the middle sleeve, and the first baffle plate, the second baffle plate and the third baffle plate are all in spiral structures.

Specifically, the port height of the gas inlet pipe is higher than that of the liquid outlet pipe, and the central angle of the arc-shaped pipe is an obtuse angle.

Specifically, the upper separation plate and the lower separation plate are both in circular ring structures, and the liquid-gas separation structure is located above the third baffle plate.

The invention has the beneficial effects that:

(1) According to the natural gas liquefaction method, the cold medium mass conveying structure and the natural gas conveying structure are linked, so that high-pressure natural gas enters a gas-liquid two-phase space from the gas inlet pipe and spirally rises along the third baffle plate from the annular channel, heat exchange is fully performed with low-temperature media in the inner fluid cavity and the outer fluid cavity in the process, the temperature of the high-pressure natural gas can be effectively reduced, and the natural gas liquefaction method can be conveniently used in a hot environment.

(2) According to the natural gas liquefaction method, the heat insulation structure and the liquid-gas separation structure are linked, the vacuum environment is used for cold insulation, the filler is used for gas-liquid separation, the natural gas liquefaction device is compact in structure and high in heat exchange efficiency, and secondary condensation liquid preparation can be realized when BOG is introduced.

Drawings

The invention is further illustrated with reference to the following figures and examples.

FIG. 1 is a flow chart of a method of the present invention;

FIG. 2 is a sectional view showing the structure of a liquefying apparatus used in the present invention;

FIG. 3 is a top sectional view of a casing of a liquefaction plant in which the present invention is used;

FIG. 4 is a schematic view of the internal assembly of the inner sleeve of the liquefaction plant employed in the present invention;

FIG. 5 is a schematic view of the structure of the upper partition plate of the liquefaction plant employed in the present invention;

Fig. 6 is an enlarged view of fig. 2 at a.

In the figure: 1. an insulating structure; 11. protecting the shell; 12. a shell cover; 13. an access hole; 14. a sealing cover; 15. vacuumizing a tube; 16. a gas delivery pipe; 17. adjusting a valve; 18. a check valve; 19. a base plate; 110. a connecting plate; 2. a refrigerant medium conveying structure; 21. an outer sleeve; 22. an inner sleeve; 23. a first baffle plate; 24. a second baffle plate; 25. filling the rods; 26. an upper barrel cover; 27. a lower cylinder cover; 28. an outer fluid chamber; 29. an inner fluid chamber; 210. a medium inlet pipe; 211. a flow guide pipe; 212. a medium outlet pipe; 3. a natural gas delivery structure; 31. an intermediate sleeve; 32. a third baffle plate; 33. a return pipe; 34. a liquid outlet pipe; 35. a gas inlet pipe; 36. a three-way valve; 37. a flash vapor tube; 38. an outer support; 39. an inner support; 310. an arc tube; 311. spraying a hole; 4. a liquid-gas separation structure; 41. an upper partition plate; 42. a bottom divider plate; 43. a filler; 44. lower angle steel; 45. upper angle steel; 46. and (4) air holes.

Detailed Description

In order to make the technical means, the creation characteristics, the achievement purposes and the effects of the invention easy to understand, the invention is further described with the specific embodiments.

As shown in fig. 1 to 6, the liquefaction method of natural gas according to the present invention includes the following steps:

S1, preparation of raw material gas: introducing coke oven gas and coal gas into a gas holder, mixing to obtain mixed gas, and performing sulfur-resistant water vapor conversion or CO conversion on 5-50% of the mixed gas₂after reforming, mixing the raw material gas with the rest mixed gas to obtain raw material gas, so as to obtain the material gas meeting the methanation requirement;

S2: compressing the raw material gas in S1, purifying to remove H₂s and CO₂Desulphurizing and recovering the removed hydrogen sulphide, removing CO₂Discharging gas, methanation of purified raw gas, PSA (pressure swing adsorption) separation of the methanated purge gas, and separation of CO and CO₂Returning to purification, carrying out heavy oil hydrogenation on the separated hydrogen to prepare hydrogenated gasoline blend oil or hydrogenated diesel blend oil, carrying out methanation to obtain methane gas, and dehydrating and compressing the methane gas to prepare a qualified natural gas product;

S3: carrying out low-pressure treatment on the natural gas product in the S2 to form low-pressure natural gas, and then introducing the low-pressure natural gas into a liquefying device for liquefying;

the liquefaction device adopted in the S3 includes a heat insulation structure 1, a refrigerant medium conveying structure 2, a natural gas conveying structure 3, and a liquid-gas separation structure 4, the refrigerant medium conveying structure 2 is fixedly installed inside the heat insulation structure 1, the natural gas conveying structure 3 is fixedly installed on the inner wall of the refrigerant medium conveying structure 2, and the liquid-gas separation structure 4 is fixedly installed between the natural gas conveying structure 3 and the refrigerant medium conveying structure 2.

Specifically, adiabatic structure 1 includes protecting casing 11, cap 12 and bottom plate 19, the upside screw fixation of protecting casing 11 has cap 12, the middle part of cap 12 is equipped with access hole 13, screw fixation has sealed lid 14 on the ring flange of access hole 13, the downside screw fixation of protecting casing 11 has bottom plate 19, inlay on the lower part outer wall of protecting casing 11 and be equipped with gas-supply pipe 16 and evacuation pipe 15, install check valve 18 on the evacuation pipe 15, install governing valve 17 on the gas-supply pipe 16, the welding of protecting casing 11 inner wall has a plurality of connecting plates 110, and after the evacuation, form vacuum environment in protecting casing 11, have adiabatic effect.

Specifically, the refrigerant medium conveying structure 2 comprises an outer sleeve 21, an inner sleeve 22, a first baffle plate 23, a second baffle plate 24, a filling rod 25, an upper cylinder cover 26, a lower cylinder cover 27, a medium inlet pipe 210, a guide pipe 211 and a medium outlet pipe 212, wherein the outer sleeve 21 is positioned in the protective shell 11, the outer wall of the outer sleeve 21 is welded with the connecting plate 110, the upper side and the lower side of the outer sleeve 21 are respectively and fixedly connected with the upper cylinder cover 26 and the lower cylinder cover 27, the inner sleeve 22 is fixedly connected between the upper cylinder cover 26 and the lower cylinder cover 27 and positioned in the outer sleeve 21, the inner wall of the outer sleeve 21 is fixedly connected with the first baffle plate 23, the inner wall of the outer sleeve 22 is fixedly connected with the second baffle plate 24, the filling rod 25 is sleeved in the second baffle plate 24, two ends of the filling rod 25 are respectively and fixedly connected with the upper cylinder cover 26 and the lower cylinder cover 27, the medium inlet pipe 210, a medium outlet pipe 212 is embedded in the upper cylinder cover 26 and located on the upper side of the inner cylinder 22, an inner fluid cavity 29 is arranged between the inner cylinder 22 and the filling rod 25, an outer fluid cavity 28 is arranged in the outer cylinder 21, a guide pipe 211 is communicated between the inner fluid cavity 29 and the outer fluid cavity 28, a low-temperature medium enters the outer fluid cavity 28 from a medium inlet pipe 210, the low-temperature medium spirally descends along a first baffle plate 23 in the outer fluid cavity 28 and is changed to the rear direction through the guide pipe 211, the low-temperature medium spirally ascends along a second baffle plate 24 in the inner fluid cavity 29, and high-pressure natural gas in a gas-liquid two-phase space is subjected to inside-outside slow-speed heat exchange.

Specifically, the natural gas conveying structure 3 includes an intermediate sleeve 31, a third baffle plate 32, a return pipe 33, a liquid outlet pipe 34, a gas inlet pipe 35, a three-way valve 36, a flash vapor pipe 37, an outer support 38, an inner support 39 and an arc pipe 310, the intermediate sleeve 31 is located between the outer sleeve 21 and the inner sleeve 22, the upper end and the lower end of the intermediate sleeve 31 are respectively and fixedly connected with the upper sleeve cover 26 and the lower sleeve cover 27, the third baffle plate 32 is fixedly connected between the intermediate sleeve 31 and the inner sleeve 22, the liquid outlet pipe 34 and the gas inlet pipe 35 are embedded in the lower sleeve cover 27 and located between the intermediate sleeve 31 and the inner sleeve 22, the return pipe 33 is embedded in the upper sleeve cover 26 and located between the intermediate sleeve 31 and the inner sleeve 22, the inner support 39 is fixed by screws on the upper side of the lower sleeve cover 27 and located between the intermediate sleeve 31 and the inner sleeve 22, the arc pipe 310 is installed on the upper side of, the arc-shaped pipe 310 is provided with a plurality of spray holes 311, the arc-shaped pipe 310 is communicated with a flash steam pipe 37, one end of the flash steam pipe 37 penetrates through the lower cylinder cover 27 and is connected with a three-way valve 36, the three-way valve 36 is installed on the medium outlet pipe 212, the flash steam pipe 37 is fixedly connected with the inner wall of the protective shell 11 through an outer support 38, a liquefaction space is formed between the inner sleeve 22 and the middle sleeve 31, the upper side of the filler 43 is a gas phase space, the lower side of the filler 43 is a gas-liquid two-phase space, the bottom of the gas-liquid two-phase space is a liquid phase space, high-pressure natural gas enters the gas-liquid two-phase space from the gas inlet pipe 35 and spirally rises along the third baffle plate 32 from an annular channel, and the process and low-temperature.

Specifically, the liquid-gas separation structure 4 includes an upper separation plate 41, a lower separation plate 42, a filler 43, a lower angle steel 44 and an upper angle steel 45, the upper separation plate 41 and the lower separation plate 42 are all sleeved outside the inner sleeve 22, the outer edges of the upper separation plate 41 and the lower separation plate 42 are all welded to the intermediate sleeve 31, the filler 43 is filled between the upper separation plate 41 and the lower separation plate 42, an upper angle steel 45 is welded to the upper side of the upper separation plate 41, a lower angle steel 44 is welded to the lower side of the lower separation plate 42, the upper angle steel 45 and the lower angle steel 44 are both welded to the inner wall of the intermediate sleeve 31, a plurality of air holes 46 are respectively formed in the upper separation plate 41 and the lower separation plate 42, liquid flows from top to bottom along the surface of the filler 43, and gas and.

Specifically, the outer fluid cavity 28 is located between the outer sleeve 21 and the middle sleeve 31, and the first baffle plate 23, the second baffle plate 24 and the third baffle plate 32 are all in a spiral structure and have the functions of slowing and prolonging a heat exchange path.

Specifically, the height of the port of the gas inlet pipe 35 is higher than that of the port of the liquid outlet pipe 34, and the central angle of the arc-shaped pipe 310 is an obtuse angle, so that liquid drainage is facilitated.

Specifically, the upper separation plate 41 and the lower separation plate 42 are both annular structures, the liquid-gas separation structure 4 is located above the third baffle plate 32, after the BOG is introduced into the outer fluid cavity 28, the three-way valve 36 can be reversed, the condensed residual BOG enters a gas-liquid two-phase space through the flash evaporation gas pipe 37, the BOG in the gas-liquid two-phase space is mixed with natural gas and then is uniformly mixed and injected into the filler 43 for secondary condensation and recovery, and secondary condensation liquid preparation can be realized.

When the high-pressure natural gas liquefaction device is used, a low-temperature medium enters the outer fluid cavity 28 from the medium inlet pipe 210, the low-temperature medium is low-pressure natural gas after expansion and cooling, the low-temperature medium descends in the outer fluid cavity 28 in a spiral mode along the first baffle plate 23 and changes direction through the guide pipe 211, the low-temperature medium ascends in the inner fluid cavity 29 in a spiral mode along the second baffle plate 24, a liquefaction space is formed between the inner sleeve 22 and the middle sleeve 31, the upper side of the filler 43 is a gas-phase space, the lower side of the filler 43 is a gas-liquid two-phase space, the bottom of the gas-liquid two-phase space is a liquid-phase space, the high-pressure natural gas enters the gas-liquid two-phase space from the gas inlet pipe 35 and ascends in a spiral mode along the third baffle plate 32 through the annular channel, heat exchange is fully carried out on the low-temperature medium in the inner fluid, when the condensed BOG passes through the filler 43, the natural gas continuously moves upwards, the gasified liquid is gathered, the liquid drops spirally descend to the bottom along the third baffle plate 32, the liquid drops are pumped into the storage tank along the liquid outlet pipe 34 by the high-pressure pump, the unliquefied natural gas is discharged from the return pipe 33, the natural gas liquefaction process is realized, further, after the BOG is introduced into the outer fluid cavity 28, the three-way valve 36 can be reversed, the condensed residual BOG enters a gas-liquid two-phase space through the flash evaporation gas pipe 37, the BOG in the gas-liquid two-phase space and the natural gas are uniformly mixed and sprayed into the filler 43 for secondary condensation and recovery, and secondary condensation liquid.

the foregoing illustrates and describes the principles, general features, and advantages of the present invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, and the embodiments and descriptions given above are only illustrative of the principles of the present invention, and various changes and modifications may be made without departing from the spirit and scope of the invention, which fall within the scope of the claims. The scope of the invention is defined by the appended claims and equivalents thereof.