Optimized structure of LNG around-tube heat exchanger

Abstract

The application relates to the technical field of pipe-coil heat exchangers, in particular to an optimized structure of an LNG pipe-coil heat exchanger, which comprises an upper shell, a lower shell and a middle shell fixed between the upper shell and the lower shell, a first medium inlet and a second medium inlet are arranged on the upper shell, a first medium outlet and a second medium outlet are arranged on the lower shell, a cavity formed by the upper shell, the lower shell and the middle shell is in communication with the second medium inlet and the second medium outlet, a winding pipe group is further arranged in the cavity, and the two ends of the winding pipe group are in communication with the first medium inlet and the first medium outlet through connecting parts. By arranging two conical spiral structures with opposite spiral directions on the winding pipe, the thermal stress deformation of the spiral winding pipe can be automatically compensated, and the temperature difference that can be borne by the LNG pipe-coil heat exchanger is improved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of a LNG (liquefied natural gas) spiral wound heat exchanger, in particular to an optimized structure of a LNG spiral wound heat exchanger. BACKGROUND

[0002] The LNG spiral wound heat exchanger is one of the key equipment in the LNG industry chain, and is mainly used for efficiently realizing heat exchange of gas-liquid two phases in a low-temperature environment. The core structure adopts a multi-layer spiral wound thin tube bundle, and a high-density heat exchange surface is formed through a compact laminated design, so that the LNG spiral wound heat exchanger has the high-pressure resistance of a tube-shell heat exchanger and the heat exchange efficiency advantage of a plate heat exchanger. The traditional tube-shell heat exchanger has problems such as easy brittle fracture and large temperature difference stress below-160 DEG C, while the spiral wound design offsets the thermal stress through spiral winding, and simultaneously strengthens heat exchange through counterflow arrangement. Modern technology further integrates high-strength aluminum alloy material, vacuum brazing process and computer-aided flow channel optimization, so that the equipment performs outstandingly in compactness (the unit volume heat exchange area reaches 150 m2 / m3) and temperature difference adaptability (-200 DEG C to 50 DEG C), is widely applied to LNG receiving stations, floating liquefaction devices and regasification links, and becomes the preferred heat exchange scheme for large-scale and modular LNG projects. In order to further improve the heat exchange efficiency of the LNG heat exchanger and increase the bearing range of the temperature difference stress, the structure of the heat exchanger needs to be continuously improved. SUMMARY

[0003] In view of the defects of the prior art, the application provides an optimized structure of a LNG spiral wound heat exchanger, two tapered spiral structures with opposite spiral directions are arranged on the spiral wound pipe, so that the thermal stress deformation generated by the spiral wound pipe can be automatically compensated, and the temperature difference that can be borne by the LNG spiral wound heat exchanger is improved.

[0004] To achieve the above object, the application provides the following technical scheme.

[0005] An optimized structure of a LNG spiral wound heat exchanger comprises an upper shell, a lower shell and a middle shell fixed between the upper shell and the lower shell, the upper shell is provided with a first medium inlet and a second medium inlet, the lower shell is provided with a first medium outlet and a second medium outlet, a cavity formed by the upper shell, the lower shell and the middle shell is in communication with the second medium inlet and the second medium outlet, a spiral wound pipe group is further arranged in the cavity, and the two ends of the spiral wound pipe group are in communication with the first medium inlet and the first medium outlet through connecting portions, the spiral wound pipe group comprises an outer spiral wound pipe and an inner spiral wound pipe arranged in the outer spiral wound pipe, the two ends of the outer spiral wound pipe and the inner spiral wound pipe are provided with tapered structures, and the tapered structures at the two ends are connected through a communication portion, a fixing ring is arranged on the communication portion at the middle part of the outer spiral wound pipe and the inner spiral wound pipe, and an elastic structure is arranged between the fixing ring and the middle shell.

[0006] Further, the conical structure of the outer winding pipe comprises a first outer conical surface and a second outer conical surface; the small spiral diameter end of the first outer conical surface is connected with the connecting part, and the large spiral diameter end of the first outer conical surface is connected with the first communicating part; the small spiral diameter end of the second outer conical surface is connected with the connecting part, and the large spiral diameter end of the second outer conical surface is connected with the first communicating part.

[0007] Further, the conical structure of the inner winding pipe comprises a first inner conical surface and a second inner conical surface; the small spiral diameter end of the first inner conical surface is connected with the connecting part, and the large spiral diameter end of the first inner conical surface is connected with the second communicating part; the small spiral diameter end of the second inner conical surface is connected with the connecting part, and the large spiral diameter end of the second inner conical surface is connected with the second communicating part.

[0008] Further, the first outer conical surface and the second outer conical surface are composed of a plurality of outer spiral pipes which are equidistantly arranged along the circumference of the connecting part; the first inner conical surface and the second inner conical surface are composed of a plurality of inner spiral pipes which are equidistantly arranged along the circumference of the connecting part; the outer spiral pipes and the inner spiral pipes on the connecting part are alternately arranged to avoid spatial interference.

[0009] Further, the structure of the outer spiral pipe and the inner spiral pipe each comprises a first communicating pipe, a conical spiral pipe and a second communicating pipe; the small spiral diameter end of the conical spiral pipe is connected with the connecting part through the second communicating pipe; the large spiral diameter end of the conical spiral pipe is connected with the first communicating pipe of the spiral pipe on the other side through the first communicating pipe.

[0010] Further, the spiral direction of the conical spiral pipe of the first outer conical surface is opposite to the spiral direction of the conical spiral pipe of the second outer conical surface; the spiral direction of the conical spiral pipe of the first inner conical surface is opposite to the spiral direction of the conical spiral pipe of the second inner conical surface.

[0011] Further, a plurality of first clamping grooves and second clamping grooves are equidistantly arranged on the inner side of the body of the fixing ring; the first clamping grooves and the second clamping grooves are alternately arranged; the first communicating part of the outer winding pipe is arranged in the first clamping groove; the second communicating part of the inner winding pipe is arranged in the second clamping groove; the first clamping groove and the second clamping groove are slot-shaped structures with an open end facing the inner side of the fixing ring.

[0012] Further, one end of each of the upper shell and the lower shell is provided with a mounting part; the two ends of the middle shell are fixed with the mounting parts of the upper shell and the lower shell; the inner wall of the shell body of the middle shell is provided with a limiting part; the outer circular side of the body of the fixing ring is provided with a flange, and the flange of the fixing ring is rotatably arranged in the limiting part of the middle shell.

[0013] Further, a plurality of limiting grooves are arranged on the body of the fixing ring; a plurality of bosses are arranged on the sidewall of the shell of the middle shell and extend into the limiting grooves; and an elastic body is arranged between the bosses and the limiting grooves; the elastic body blocks rotation of the fixing ring in the limiting part of the middle shell.

[0014] Further, the length of the second communication pipe in the outer winding pipe is less than the length of the second communication pipe in the inner winding pipe; the length of the first communication pipe in the outer winding pipe is greater than the length of the first communication pipe in the inner winding pipe; and the depth of the first clamping groove in the fixing ring is greater than the depth of the second clamping groove.

[0015] Compared with the prior art, the LNG winding pipe heat exchanger provided by the application has the following beneficial effects: the winding pipe group has two opposite conical spiral structures, the small-diameter end of the two conical spiral structures is a fixed end, and the large-diameter end of the two conical spiral structures is connected to each other, the setting mode of gradually increasing the spiral diameter is used to compensate for the deformation caused by thermal stress, and the spiral directions of the two conical spiral structures are opposite, so that the middle part of the two spiral structures connected to each other has a same-direction moving trend when the middle part is subjected to thermal stress, the fixing ring fixed by clamping and the elastic structure arranged on the fixing ring can be used to limit and fix the spiral winding pipe while eliminating the deformation caused by thermal stress, so that the pressure in the winding pipe group is very high, but the component acting on the pipe wall is not high, and therefore the LNG heat exchanger can withstand a larger temperature difference. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 FIG. 1 is a structural schematic diagram of the LNG winding pipe heat exchanger of the application;

[0017] Figure 2 FIG. 2 is a structural schematic diagram of the internal structure of the winding pipe heat exchanger of the application;

[0018] Figure 3 FIG. 3 is a structural schematic diagram of the middle shell and the fixing ring of the application;

[0019] Figure 4 FIG. 4 is a structural schematic diagram of the winding pipe group of the application;

[0020] Figure 5 FIG. 5 is an exploded structural schematic diagram of the inner and outer winding pipes of the application;

[0021] Figure 6 FIG. 6 is a structural schematic diagram of the inner and outer spiral pipes of the application;

[0022] Figure 7 FIG. 7 is a structural schematic diagram of the outer spiral pipe of the application;

[0023] Figure 8 FIG. 8 is a sectional view of the fixing ring of the application;

[0024] Figure 9 A schematic view of the cooperation mode of the middle shell and the fixing ring of the present application;

[0025] Figure 10 A schematic view of the structure of the fixing ring of the present application;

[0026] In the figure:

[0027] Upper shell 1, lower shell 10, first medium inlet 11, first medium outlet 12, second medium inlet 13, second medium outlet 14, mounting portion 15;

[0028] Middle shell 2, shell body 21, limiting portion 22, boss 23, elastic body 24;

[0029] Winding pipe group 3, outer winding pipe 6, first outer taper surface 61, second outer taper surface 62, inner winding pipe 7, first inner taper surface 71, second inner taper surface 72, first communication portion 60, second communication portion 70, outer spiral pipe 610, first communication pipe 611, tapered spiral pipe 612, second communication pipe 613, inner spiral pipe 710;

[0030] Connecting portion 4;

[0031] Fixing ring 5, body 51, limiting groove 52, first clamping groove 53, second clamping groove 54, flange 55; DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0033] The present invention is described in detail below with reference to the accompanying drawings. The optimized structure of the LNG coiled heat exchanger of the present invention includes an upper shell 1, a lower shell 10, and a middle shell 2 fixed between the upper shell 1 and the lower shell 10. The upper shell 1 is provided with a first medium inlet 11 and a second medium inlet 13; the lower shell 10 is provided with a first medium outlet 12 and a second medium outlet 14. The cavity formed by the upper shell 1, the lower shell 10, and the middle shell 2 is connected to the second medium inlet 13 and the second medium outlet 14. A coiled tube group 3 is also provided in the cavity, and the ends of the coiled tube group 3 are connected to the first medium inlet 11 and the first medium outlet 12 respectively through a connecting portion 4. The coiled tube group 3 includes an outer coiled tube 6 and an inner coiled tube 7 disposed inside the outer coiled tube 6. The outer coiled tube 6 and the inner coiled tube 7 have tapered structures at both ends, and the tapered structures at both ends are connected by a connecting portion. A fixing ring 5 is sleeved on the connecting portion in the middle of the outer coiled tube 6 and the inner coiled tube 7, and an elastic structure is provided between the fixing ring 5 and the middle shell 2.

[0034] The structural design of the spiral tube bundle of the winding tube group 3 of the present invention can automatically compensate for thermal stress, which is conducive to adapting to the large temperature difference changes of the LNG heat exchanger. The two ends of the winding tube group 3 are fixed on the connecting part 4. When subjected to thermal stress, the distance between the spirals or the diameter of the spirals can be automatically changed to compensate for the thermal stress. In order to further compensate for the deformation of the winding tube group 3 caused by thermal stress, both ends of the outer winding tube 6 and the inner winding tube 7 of the winding tube group 3 have a tapered structure, that is, the diameter of the spiral gradually increases from the two ends fixed on the connecting part 4 to the middle part. When the winding tube group 3 is subjected to a large temperature difference, the deformation of the non-fixed end of the winding tube group 3 caused by thermal stress is further reduced, so that the pressure inside the tube of the winding tube group 3 is very high, but the component acting on the tube wall is not high, so that the LNG heat exchanger can withstand higher pressure.

[0035] The conical structure of the outer winding tube 6 includes a first outer conical surface 61 and a second outer conical surface 62; the small spiral diameter end of the first outer conical surface 61 is connected to the connecting part 4, and the large spiral diameter end of the first outer conical surface 61 is connected to the first connecting part 60; the small spiral diameter end of the second outer conical surface 62 is connected to the connecting part 4, and the large spiral diameter end of the second outer conical surface 62 is connected to the first connecting part 60.

[0036] The conical structure of the inner winding tube 7 includes a first inner conical surface 71 and a second inner conical surface 72; the small spiral diameter end of the first inner conical surface 71 is connected to the connecting part 4, and the large spiral diameter end of the first inner conical surface 71 is connected to the second connecting part 70; the small spiral diameter end of the second inner conical surface 72 is connected to the connecting part 4, and the large spiral diameter end of the second inner conical surface 72 is connected to the second connecting part 70.

[0037] Specifically, the outer winding pipe 6 is sleeved with the inner winding pipe 7, the space of the LNG winding pipe heat exchanger can be utilized to set the winding pipe group 3 with a longer path in the same volume to improve the heat exchange efficiency, and the conical surface structure formed by the inner and outer winding pipes forms an angle with the flow direction of the second medium flowing from the second medium inlet 13 to the second medium outlet 14, thereby improving the flowability of the second medium around the winding pipe group 3 and further improving the heat exchange efficiency between the winding pipe group 3 and the second medium.

[0038] The first outer conical surface 61 and the second outer conical surface 62 are composed of a plurality of outer spiral pipes 610 which are equidistantly arranged in the circumferential direction of the connecting portion 4; the first inner conical surface 71 and the second inner conical surface 72 are composed of a plurality of inner spiral pipes 710 which are equidistantly arranged in the circumferential direction of the connecting portion 4; the outer spiral pipes 610 and the inner spiral pipes 710 on the connecting portion 4 are alternately arranged to avoid spatial interference.

[0039] Specifically, the number of the outer spiral pipes 610 and the inner spiral pipes 710 arranged on the connecting portion 4 is the same, and the number of the outer spiral pipes 610 and the inner spiral pipes 710 corresponds to the pitch of the spiral segments thereof, and more number requires a larger pitch, in an embodiment of the present application, preferably, the number of the outer spiral pipes 610 and the inner spiral pipes 710 is four and equidistantly arranged in the circumferential direction of the connecting portion 4, and the spiral segments of the plurality of outer spiral pipes 610 and inner spiral pipes 710 form the first outer conical surface 61, the second outer conical surface 62, the first inner conical surface 71 and the second inner conical surface 72.

[0040] The structure of the outer spiral pipe 610 and the inner spiral pipe 710 both includes a first communication pipe 611, a conical spiral pipe 612 and a second communication pipe 613; the small spiral diameter end of the conical spiral pipe 612 is connected with the connecting portion 4 through the second communication pipe 613; the large spiral diameter end of the conical spiral pipe 612 is connected with the first communication pipe 611 of the spiral pipe on the other side through the first communication pipe 611.

[0041] Specifically, the outer spiral pipe 610 and the inner spiral pipe 710 are fixed to the connecting portion 4 and extend outward, and the spiral diameter thereof gradually increases, see Figures 5-7 When subjected to thermal stress, the expansion and contraction amount of the spiral pipe is weakened due to the increase of the spiral diameter, so that the torsional deformation of the outer spiral pipe 610 and the inner spiral pipe 710 away from the fixed end (the end fixedly connected with the connecting portion 4) due to thermal stress is kept within a controllable range.

[0042] The spiral direction of the conical spiral pipe 612 of the first outer conical surface 61 is opposite to the spiral direction of the conical spiral pipe 612 of the second outer conical surface 62; the spiral direction of the conical spiral pipe 612 of the first inner conical surface 71 is opposite to the spiral direction of the conical spiral pipe 612 of the second inner conical surface 72.

[0043] Referring to Figure 4 and 5 , the first outer taper surface 61 and the second outer taper surface 62 are opposite in the spiral direction of the spiral pipe, specifically, as viewed from the top in Figure 5 , the spiral direction of the first outer taper surface 61 is clockwise, and the spiral direction of the second outer taper surface 62 is counterclockwise, and similarly, the first inner taper surface 71 and the second inner taper surface 72 maintain the same arrangement, the above arrangement makes the lower end of the first outer taper surface 61 in Figure 5 and the upper end of the second outer taper surface 62 in Figure 5 produce displacement in the same torsion direction when subjected to thermal stress, that is, the first outer taper surface 61 and the second outer taper surface 62 jointly push the first communication part 60 to rotate in the same direction after being subjected to thermal stress, eliminating the influence of thermal stress on the fixed end of the spiral pipe at the connecting part 4, and improving the temperature difference that the LNG spiral pipe heat exchanger can withstand.

[0044] The inner side of the body 51 of the fixed ring 5 is circumferentially spaced apart and provided with a plurality of first clamping grooves 53 and second clamping grooves 54; the first clamping grooves 53 and the second clamping grooves 54 are arranged alternately; the first clamping grooves 53 are provided with the first communication part 60 of the outer winding pipe 6; the second clamping grooves 54 are provided with the second communication part 70 of the inner winding pipe 7; the first clamping grooves 53 and the second clamping grooves 54 are slot-shaped structures with one end open towards the inner side of the fixed ring 5.

[0045] Specifically, the arrangement of one end of the first clamping groove 53 and the second clamping groove 54 being open facilitates the installation of the communication part of the inner and outer winding pipes, and the extension of the first clamping groove 53 and the second clamping groove 54 in the radial direction can provide a moving space for the communication part of the inner and outer winding pipes when the inner and outer winding pipes change the spiral diameter due to thermal stress, while achieving the limiting and fixing of the communication part of the inner and outer winding pipes. When the first outer taper surface 61 and the second outer taper surface 62 jointly push the first communication part 60 to rotate in the same direction after being subjected to thermal stress, the first and second communication parts push the fixed ring 5 to generate a movement trend through the clamping grooves.

[0046] The proximal end of the upper shell 1 and the lower shell 10 is respectively provided with a mounting part 15; the two ends of the middle shell 2 are fixed with the mounting parts 15 of the upper shell 1 and the lower shell 10; the inner wall of the shell body 21 of the middle shell 2 is provided with a limiting part 22; the outer circular side of the body 51 of the fixed ring 5 is provided with a flange 55, and the flange 55 of the fixed ring 5 is rotatably arranged in the limiting part 22 of the middle shell 2.

[0047] A plurality of limiting grooves 52 are arranged on the body 51 of the fixed ring 5; a plurality of bosses 23 protruding into the limiting grooves 52 are arranged on the side wall of the shell body 21 of the middle shell 2; an elastic body 24 is arranged between the boss 23 and the limiting groove 52; the elastic body 24 blocks the rotation of the fixed ring 5 in the limiting part 22 of the middle shell 2.

[0048] Specifically, as shown in Figure 8 , the side surface of the two sides of the boss 23 is provided with an elastic body 24, which abuts against the two opposite inner walls of the limiting groove 52. When the fixing ring 5 has a movement tendency due to the deformation of the heat stress of the winding pipe, the movement tendency is elastically supported by the elastic body 24, and the deformation of the inner and outer winding pipes due to the heat stress is eliminated while the inner and outer winding pipes are limited and fixed by the fixing ring 5.

[0049] The length of the second communication pipe 613 in the outer winding pipe 6 is less than the length of the second communication pipe in the inner winding pipe 7; the length of the first communication pipe 611 in the outer winding pipe 6 is greater than the length of the first communication pipe in the inner winding pipe 7; the depth of the first clamping groove 53 in the fixing ring 5 is greater than the depth of the second clamping groove 54.

[0050] Although the embodiments of the present application have been shown and described, it is to be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. An optimized structure of an LNG coiled-tube heat exchanger, comprising an upper shell (1), a lower shell (10), and a middle shell (2) fixed between the upper shell (1) and the lower shell (10), characterized in that: The upper shell (1) is provided with a first medium inlet (11) and a second medium inlet (13); The lower shell (10) is provided with a first medium outlet (12) and a second medium outlet (14); The cavity formed by the upper shell (1), the lower shell (10) and the middle shell (2) is in communication with the second medium inlet (13) and the second medium outlet (14); A winding tube group (3) is also provided in the cavity, and two ends of the winding tube group (3) are respectively connected to the first medium inlet (11) and the first medium outlet (12) through the connecting portion (4); The winding tube group (3) comprises an outer winding tube (6) and an inner winding tube (7) arranged inside the outer winding tube (6); Both ends of the outer winding tube (6) and the inner winding tube (7) have a tapered structure, and the tapered structures at both ends are connected by a connecting portion; A fixing ring (5) is sleeved on the communication portion in the middle of the outer winding tube (6) and the inner winding tube (7), and an elastic structure is provided between the fixing ring (5) and the middle shell (2); The conical structure of the outer winding tube (6) comprises a first outer conical surface (61) and a second outer conical surface (62); The conical structure of the inner winding tube (7) comprises a first inner conical surface (71) and a second inner conical surface (72); The spiral direction of the conical spiral tube (612) of the first outer conical surface (61) is opposite to the spiral direction of the conical spiral tube (612) of the second outer conical surface (62); The spiral direction of the conical spiral tube (612) of the first inner conical surface (71) is opposite to the spiral direction of the conical spiral tube (612) of the second inner conical surface (72).

2. The optimized structure of the LNG coiled heat exchanger according to claim 1 is characterized in that: The small spiral diameter end of the first outer conical surface (61) is connected to the connecting portion (4), and the large spiral diameter end of the first outer conical surface (61) is connected to the first connecting portion (60); The small spiral diameter end of the second outer conical surface (62) is connected to the connecting portion (4), and the large spiral diameter end of the second outer conical surface (62) is connected to the first connecting portion (60).

3. The optimized structure of the LNG coiled heat exchanger according to claim 2 is characterized in that: The small spiral diameter end of the first inner conical surface (71) is connected to the connecting portion (4), and the large spiral diameter end of the first inner conical surface (71) is connected to the second connecting portion (70); The small spiral diameter end of the second inner conical surface (72) is connected to the connecting portion (4), and the large spiral diameter end of the second inner conical surface (72) is connected to the second communicating portion (70).

4. The optimized structure of the LNG coiled heat exchanger according to claim 3 is characterized in that: The first outer conical surface (61) and the second outer conical surface (62) are composed of a plurality of outer spiral tubes (610) equidistantly arranged along the circumference of the connecting portion (4); The first inner conical surface (71) and the second inner conical surface (72) are composed of a plurality of inner spiral tubes (710) equidistantly arranged along the circumference of the connecting portion (4); The outer spiral tubes (610) and the inner spiral tubes (710) on the connecting portion (4) are arranged alternately to avoid spatial interference.

5. The optimized structure of the LNG coiled heat exchanger according to claim 4 is characterized in that: The structures of the outer spiral tube (610) and the inner spiral tube (710) both include a first connecting tube (611), a conical spiral tube (612) and a second connecting tube (613); The small spiral diameter end of the conical spiral tube (612) is connected to the connecting portion (4) via a second connecting tube (613); The large spiral diameter end of the conical spiral tube (612) is connected to the first connecting tube (611) of the spiral tube on the other side through the first connecting tube (611).

6. The optimized structure of the LNG coiled heat exchanger according to claim 5 is characterized in that: A plurality of first clamping grooves (53) and second clamping grooves (54) are provided at intervals in the circumferential direction on the inner side of the body (51) of the fixing ring (5); The first card slots (53) and the second card slots (54) are alternately arranged; A first connecting portion (60) of the outer winding tube (6) is provided in the first clamping groove (53); A second connecting portion (70) of the inner winding tube (7) is provided in the second clamping groove (54); The first clamping groove (53) and the second clamping groove (54) are groove-shaped structures with one end facing the inner side of the fixing ring (5) being an open end.

7. The optimized structure of the LNG coiled heat exchanger according to claim 6 is characterized in that: The upper shell (1) and the lower shell (10) are respectively provided with a mounting portion (15) at one end thereof that is close to each other; The two ends of the middle shell (2) are fixed to the mounting portions (15) of the upper shell (1) and the lower shell (10); The inner wall of the shell (21) of the middle shell (2) is provided with a limiting portion (22); A flange (55) is provided on the outer circumferential side of the body (51) of the fixing ring (5), and the flange (55) of the fixing ring (5) is rotatably arranged in the limiting portion (22) of the middle shell (2).

8. The optimized structure of the LNG coiled heat exchanger according to claim 7 is characterized in that: A plurality of limiting grooves (52) are provided on the body (51) of the fixing ring (5); The side wall of the shell (21) of the middle shell (2) is provided with a plurality of bosses (23) extending into the limiting grooves (52); An elastic body (24) is provided between the boss (23) and the limiting groove (52); The elastic body (24) blocks the rotation of the fixing ring (5) in the limiting portion (22) of the middle shell (2).

9. The optimized structure of the LNG coiled heat exchanger according to claim 8 is characterized in that: The length of the second connecting tube (613) in the outer winding tube (6) is smaller than the length of the second connecting tube in the inner winding tube (7); The length of the first connecting tube (611) in the outer winding tube (6) is greater than the length of the first connecting tube in the inner winding tube (7); The depth of the first clamping groove (53) in the fixing ring (5) is greater than the depth of the second clamping groove (54).

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