Optimized structure of liquefied natural gas (LNG) coiled tube type heat exchanger

Abstract

The invention relates to the technical field of coiled tube heat exchangers, in particular to an LNG coiled tube heat exchanger optimized structure which comprises an upper shell, a lower shell and a middle shell fixed between the upper shell and the lower shell, and the upper shell is provided with a first medium inlet and a second medium inlet; a first medium outlet and a second medium outlet are formed in the lower shell; a cavity formed by the upper shell, the lower shell and the middle shell is communicated with a second medium inlet and a second medium outlet; a winding pipe set is further arranged in the cavity, the two ends of the winding pipe set communicate with the first medium inlet and the first medium outlet through connecting parts correspondingly, and the two conical spiral structures with the opposite spiral directions are arranged on the winding pipe, so that thermal stress deformation generated by the spiral winding pipe can be automatically compensated; and the temperature difference capable of being borne by the LNG coiled tube type heat exchanger is increased.

Description

Technical Field

[0001] The present invention relates to the technical field of spiral wound heat exchangers, and particularly to an optimized structure of an LNG spiral wound heat exchanger. Background Art

[0002] The LNG spiral wound heat exchanger is one of the key equipment in the liquefied natural gas (LNG) industrial chain, mainly used for efficiently realizing the heat exchange between gas and liquid phases in a low-temperature environment. Its core structure adopts multiple layers of finely wound tubes in a spiral shape, forming a high-density heat transfer surface through a compact laminated design, combining the high-pressure tolerance of shell-and-tube heat exchangers and the heat transfer efficiency advantages of plate heat exchangers. Traditional shell-and-tube heat exchangers have problems such as easy brittle fracture and large temperature difference stress below -160°C, while the spiral wound tube design offsets thermal stress through spiral winding and enhances heat transfer by using countercurrent arrangement. Modern technology further integrates high-strength aluminum alloy materials, vacuum brazing processes, and computer-aided flow channel optimization, making the equipment outstanding in terms of compactness (the heat transfer area per unit volume reaches 150 m² / m³) and temperature difference adaptability (-200°C to 50°C), and is widely used in LNG receiving terminals, floating liquefaction plants, and regasification links, becoming the preferred heat exchange solution for large-scale and modular LNG projects. In order to further improve the heat transfer efficiency of LNG heat exchangers and increase the range of temperature difference stress that can be tolerated, it is necessary to continuously improve the structure of the heat exchanger. Summary of the Invention

[0003] Aiming at the deficiencies of the prior art, the present invention provides an optimized structure of an LNG spiral wound heat exchanger. By providing two conical spiral structures with opposite spiral directions on the spiral wound tube, the thermal stress deformation generated by the spiral wound tube can be automatically compensated, and the temperature difference that the LNG spiral wound heat exchanger can withstand can be increased.

[0004] To achieve the above object, the present invention provides the following technical solutions: An optimized structure of an LNG spiral wound heat exchanger, including 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 provided on the upper shell; a first medium outlet and a second medium outlet are provided on the lower shell; the cavity formed by the upper shell, the lower shell, and the middle shell is communicated with the second medium inlet and the second medium outlet; a spiral wound tube group is further provided in the cavity, and both ends of the spiral wound tube group are communicated with the first medium inlet and the first medium outlet through connecting parts respectively; the spiral wound tube group includes an outer spiral wound tube and an inner spiral wound tube arranged inside the outer spiral wound tube; both ends of the outer spiral wound tube and the inner spiral wound tube have conical structures, and the conical structures at both ends are connected through a communicating part; a fixing ring is sleeved on the communicating part in the middle of the outer spiral wound tube and the inner spiral wound tube, and an elastic structure is provided between the fixing ring and the middle shell.

[0005] Further, the conical structure of the outer winding tube includes a first outer conical surface and a second outer conical surface; the small helical diameter end of the first outer conical surface is connected to the connecting portion, and the large helical diameter end of the first outer conical surface is connected to the first communication portion; the small helical diameter end of the second outer conical surface is connected to the connecting portion, and the large helical diameter end of the second outer conical surface is connected to the first communication portion.

[0006] Further, the conical structure of the inner winding tube includes a first inner conical surface and a second inner conical surface; the small helical diameter end of the first inner conical surface is connected to the connecting portion, and the large helical diameter end of the first inner conical surface is connected to the second communication portion; the small helical diameter end of the second inner conical surface is connected to the connecting portion, and the large helical diameter end of the second inner conical surface is connected to the second communication portion.

[0007] Further, the first outer conical surface and the second outer conical surface are composed of a plurality of outer spiral tubes arranged equidistantly in the circumferential direction of the connecting portion; the first inner conical surface and the second inner conical surface are composed of a plurality of inner spiral tubes arranged equidistantly in the circumferential direction of the connecting portion; the outer spiral tubes and the inner spiral tubes on the connecting portion are arranged alternately to avoid spatial interference.

[0008] Further, the structures of the outer spiral tube and the inner spiral tube both include a first communication tube, a conical spiral tube, and a second communication tube; the small helical diameter end of the conical spiral tube is connected to the connecting portion through the second communication tube; the large helical diameter end of the conical spiral tube is connected to the first communication tube of the spiral tube on the other side through the first communication tube.

[0009] Further, the spiral direction of the conical spiral tube of the first outer conical surface is opposite to the spiral direction of the conical spiral tube of the second outer conical surface; the spiral direction of the conical spiral tube of the first inner conical surface is opposite to the spiral direction of the conical spiral tube of the second inner conical surface.

[0010] Further, a plurality of first card slots and second card slots are circumferentially spaced at intervals on the inner side of the body of the fixing ring; the first card slots and the second card slots are arranged alternately; the first communication portion of the outer winding tube is arranged in the first card slot; the second communication portion of the inner winding tube is arranged in the second card slot; the first card slots and the second card slots are groove-shaped structures with open ends facing the inner side of the fixing ring.

[0011] Further, mounting portions are respectively arranged at one end of the upper shell and the lower shell close to each other; both ends of the middle shell are fixed to the mounting portions of the upper shell and the lower shell; a limiting portion is arranged on the inner wall of the shell of the middle shell; a flange is arranged on the outer circumferential side of the body of the fixing ring, and the flange of the fixing ring is rotatably arranged in the limiting portion of the middle shell.

[0012] Further, a plurality of limiting grooves are provided on the body of the fixing ring; a plurality of bosses extending into the limiting grooves are provided on the side wall of the housing of the middle shell; an elastic body is provided between the boss and the limiting groove; the elastic body blocks the rotation of the fixing ring in the limiting part of the middle shell.

[0013] 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; the depth of the first card slot in the fixing ring is greater than the depth of the second card slot.

[0014] Compared with the prior art, the present invention provides an optimized structure of an LNG spiral wound heat exchanger, having the following beneficial effects: the winding tube group of the present invention has two conical spiral structures with opposite winding directions, the small spiral diameter ends of the two conical spiral structures are fixed ends, and the large spiral diameter ends are connected to each other. The arrangement with gradually increasing spiral diameter is used to compensate for the deformation caused by thermal stress. Moreover, the spiral directions of the two conical spiral structures are opposite, so that the middle parts where the two spiral structures are connected to each other have the same moving tendency when subjected to thermal stress. Cooperating with the fixing ring fixedly connected thereto and the elastic structure provided on the fixing ring, it can limit and fix the spiral wound tube while eliminating the deformation caused by thermal stress, so that the pressure inside the winding tube group is very high, but the component acting on the tube wall is not high, thereby enabling the LNG heat exchanger to withstand a greater temperature difference. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a schematic structural diagram of the LNG spiral wound heat exchanger of the present invention; Figure 2 is a schematic internal structural diagram of the spiral wound heat exchanger of the present invention; Figure 3 is a schematic structural diagram of the middle shell and the fixing ring of the present invention; Figure 4 is a schematic structural diagram of the winding tube group of the present invention; Figure 5 is an exploded structural diagram of the inner and outer winding tubes of the present invention; Figure 6 is a schematic structural diagram of the inner and outer spiral tubes of the present invention; Figure 7 is a schematic structural diagram of the outer spiral tube of the present invention; Figure 8 is a cross-sectional view of the fixing ring of the present invention; Figure 9 is a schematic diagram of the cooperation mode of the middle shell and the fixing ring of the present invention; Figure 10 is a schematic structural diagram of the fixing ring of the present invention; In the figure: Upper shell 1, lower shell 10, first medium inlet 11, first medium outlet 12, second medium inlet 13, second medium outlet 14, installation part 15; Middle shell 2, housing 21, limiting part 22, boss 23, elastic body 24; Winding tube group 3, outer winding tube 6, first outer conical surface 61, second outer conical surface 62, inner winding tube 7, first inner conical surface 71, second inner conical surface 72, first communication part 60, second communication part 70, outer spiral tube 610, first communication pipe 611, conical spiral tube 612, second communication pipe 613, inner spiral tube 710; Connection part 4; Fixed ring 5, body 51, limiting groove 52, first clamping groove 53, second clamping groove 54, flange 55; Specific implementation manner

[0016] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0017] The optimized structure of the LNG spiral wound heat exchanger of the present invention will be described in detail below with reference to the accompanying drawings. The optimized structure of the LNG spiral wound 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. A first medium inlet 11 and a second medium inlet 13 are provided on the upper shell 1; a first medium outlet 12 and a second medium outlet 14 are provided on the lower shell 10; the cavity formed by the upper shell 1, the lower shell 10, and the middle shell 2 communicates with the second medium inlet 13 and the second medium outlet 14; a winding tube group 3 is further provided in the cavity, and both ends of the winding tube group 3 are respectively communicated with the first medium inlet 11 and the first medium outlet 12 through a connection part 4; the winding tube group 3 includes an outer winding tube 6 and an inner winding tube 7 provided inside the outer winding tube 6; both ends of the outer winding tube 6 and the inner winding tube 7 have a conical structure, and the conical structures at both ends are connected through a communication part; a fixed ring 5 is sleeved on the communication part in the middle of the outer winding tube 6 and the inner winding tube 7, and an elastic structure is provided between the fixed ring 5 and the middle shell 2.

[0018] 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 beneficial to adapting to the large temperature difference change 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 spiral 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. When the winding tube group 3 is subjected to a large temperature difference, the deformation amount of the non-fixed end of the winding tube group 3 caused by thermal stress is further reduced, so that the pressure inside 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.

[0019] The tapered 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.

[0020] The tapered 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.

[0021] Specifically, the inner winding tube 7 is sleeved inside the outer winding tube 6, which can utilize the space of the LNG shell-and-tube heat exchanger to set a winding tube group 3 with a longer path in the same volume to improve the heat exchange efficiency. The conical structure formed by the inner and outer winding tubes makes the flow direction of the second medium flowing from the second medium inlet 13 to the second medium outlet 14 form an angle with the conical structure, improving the fluidity of the second medium around the winding tube group 3 and further improving the heat exchange efficiency between the winding tube group 3 and the second medium.

[0022] The first outer conical surface 61 and the second outer conical surface 62 are composed of a plurality of outer spiral tubes 610 arranged equidistantly in the circumferential direction of the connecting part 4; the first inner conical surface 71 and the second inner conical surface 72 are composed of a plurality of inner spiral tubes 710 arranged equidistantly in the circumferential direction of the connecting part 4; the outer spiral tubes 610 and the inner spiral tubes 710 on the connecting part 4 are arranged alternately to avoid space interference.

[0023] Specifically, the number of the outer spiral tubes 610 and the inner spiral tubes 710 provided on the connecting portion 4 is the same. The number of the outer spiral tubes 610 and the inner spiral tubes 710 corresponds to the pitch of their spiral segments. A larger number requires a larger pitch. In an embodiment of the present invention, preferably, the number of the outer spiral tubes 610 and the inner spiral tubes 710 is four and they are equidistantly arranged in the circumferential direction of the connecting portion 4. The spiral segments of multiple outer spiral tubes 610 and inner spiral tubes 710 form a first outer conical surface 61, a second outer conical surface 62, a first inner conical surface 71, and a second inner conical surface 72.

[0024] The structures of the outer spiral tube 610 and the inner spiral tube 710 both include a first connecting pipe 611, a conical spiral pipe 612, and a second connecting pipe 613. The small spiral diameter end of the conical spiral pipe 612 is connected to the connecting portion 4 through the second connecting pipe 613. The large spiral diameter end of the conical spiral pipe 612 is connected to the first connecting pipe 611 of the spiral tube on the other side through the first connecting pipe 611.

[0025] Specifically, the outer spiral tube 610 and the inner spiral tube 710 are fixed to the connecting portion 4 and extend outward, and their spiral diameters gradually increase. Refer to Figures 5-7 , when subjected to thermal stress, the expansion and contraction amount of the spiral tube is weakened due to the increase in its spiral diameter, so that the torsional deformation generated by the outer spiral tube 610 and the inner spiral tube 710 in the part far from the fixed end (the end fixedly connected to the connecting portion 4) due to thermal stress is kept within a controllable range.

[0026] 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.

[0027] Refer to Figure 4 and 5 , the spiral directions of the spiral tubes in the first outer conical surface 61 and the second outer conical surface 62 are opposite. Specifically, in the top view of Figure 5 , the spiral direction of the first outer conical surface 61 is clockwise, and the spiral direction of the second outer conical surface 62 is counterclockwise. Similarly, the first inner conical surface 71 and the second inner conical surface 72 are arranged in the same way. The above arrangement makes the Figure 5 lower end in Figure 5 of the first outer conical surface 61 and the Figure 5 upper end in Figure 5 of the second outer conical surface 62 generate displacements in the same torsional direction when subjected to thermal stress, that is, the first outer conical surface 61 and the second outer conical surface 62 jointly push the first connecting portion 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 tube at the connecting portion 4 and improving the temperature difference that the LNG spiral wound heat exchanger can withstand.

[0028] On the inner circumference of the body 51 of the fixed ring 5, a plurality of first clamping grooves 53 and second clamping grooves 54 are circumferentially spaced; the first clamping grooves 53 and the second clamping grooves 54 are arranged alternately; the first communication part 60 of the outer winding pipe 6 is arranged in the first clamping groove 53; the second communication part 70 of the inner winding pipe 7 is arranged in the second clamping groove 54; the first clamping grooves 53 and the second clamping grooves 54 are groove-shaped structures with open ends facing the inner side of the fixed ring 5.

[0029] Specifically, the arrangement of the open ends at one end of the first clamping grooves 53 and the second clamping grooves 54 facilitates the installation and entry of the communication parts of the inner and outer winding pipes. At the same time, the radial extension of the first clamping grooves 53 and the second clamping grooves 54 can reserve a moving space for the communication parts of the inner and outer winding pipes when the inner and outer winding pipes are subjected to thermal stress and change the spiral diameter, and at the same time, limit and fix the communication parts of the inner and outer winding pipes. When the first outer conical surface 61 and the second outer conical 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 tendency through the clamping grooves.

[0030] At the adjacent ends of the upper shell 1 and the lower shell 10, mounting parts 15 are respectively arranged; both ends of the middle shell 2 are fixed to the mounting parts 15 of the upper shell 1 and the lower shell 10; a limiting part 22 is arranged on the inner wall of the shell body 21 of the middle shell 2; a flange 55 is arranged on the outer circular side of the body 51 of the fixed ring 5, and the flange 55 of the fixed ring 5 is rotatably arranged in the limiting part 22 of the middle shell 2.

[0031] A plurality of limiting grooves 52 are arranged on the body 51 of the fixed ring 5; a plurality of bosses 23 extending 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 bosses 23 and the limiting grooves 52; the elastic body 24 blocks the rotation of the fixed ring 5 in the limiting part 22 of the middle shell 2.

[0032] Specifically, as Figure 8 , elastic bodies 24 are arranged on the side surfaces on both sides of the boss 23, and the elastic bodies 24 are abutted against the two opposite inner walls of the limiting groove 52. When the fixed ring 5 has a movement tendency due to the thermal stress deformation of the winding pipe, the movement tendency is elastically supported through the elastic bodies 24. While the inner and outer winding pipes are limited and fixed through the fixed ring 5, the deformation caused by the thermal stress of the inner and outer winding pipes is eliminated.

[0033] 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 fixed ring 5 is greater than the depth of the second clamping groove 54.

[0034] Although embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An optimized structure of an LNG spiral wound 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: A first medium inlet (11) and a second medium inlet (13) are provided on the upper shell (1); A first medium outlet (12) and a second medium outlet (14) are provided on the lower shell (10); The cavity formed by the upper shell (1), the lower shell (10), and the middle shell (2) is communicated with the second medium inlet (13) and the second medium outlet (14); A spiral wound tube group (3) is further provided in the cavity, and both ends of the spiral wound tube group (3) are respectively communicated with the first medium inlet (11) and the first medium outlet (12) through a connecting part (4); The spiral wound tube group (3) includes an outer spiral wound tube (6) and an inner spiral wound tube (7) arranged inside the outer spiral wound tube (6); Both ends of the outer spiral wound tube (6) and the inner spiral wound tube (7) have a conical structure, and the conical structures at both ends are connected through a communicating part; A fixing ring (5) is sleeved on the communicating part in the middle of the outer spiral wound tube (6) and the inner spiral wound tube (7), and an elastic structure is provided between the fixing ring (5) and the middle shell (2).

2. The optimized structure of the LNG spiral wound heat exchanger according to claim 1, characterized in that: The conical structure of the outer spiral wound 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 a first communicating 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 communicating part (60).

3. The optimized structure of the LNG spiral wound heat exchanger according to claim 2, characterized in that: The conical structure of the inner spiral wound 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 a second communicating 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 communicating part (70).

4. The optimized structure of the LNG spiral wound heat exchanger according to claim 3, 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) arranged equidistantly in the circumferential direction of the connecting part (4); The first inner conical surface (71) and the second inner conical surface (72) are composed of a plurality of inner spiral tubes (710) arranged equidistantly in the circumferential direction of the connecting part (4); The outer spiral tubes (610) and the inner spiral tubes (710) on the connecting part (4) are arranged alternately to avoid spatial interference.

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

6. The optimized structure of the LNG wound tube heat exchanger according to claim 5, characterized in that: 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).

7. The optimized structure of the LNG wound tube heat exchanger according to claim 6, characterized in that: A plurality of first clamping grooves (53) and second clamping grooves (54) are circumferentially spaced on the inner side of the body (51) of the fixing ring (5); The first clamping grooves (53) and the second clamping grooves (54) are arranged alternately; The first connecting part (60) of the outer winding tube (6) is arranged in the first clamping groove (53); The second connecting part (70) of the inner winding tube (7) is arranged in the second clamping groove (54); The first clamping grooves (53) and the second clamping grooves (54) are of a groove-shaped structure with an open end at one end facing the inner side of the fixing ring (5).

8. The optimized structure of the LNG wound tube heat exchanger according to claim 7, characterized in that: Mounting parts (15) are respectively arranged at one end of the upper shell (1) and the lower shell (10) close to each other; Both ends of the middle shell (2) are fixed to the mounting parts (15) of the upper shell (1) and the lower shell (10); A limiting part (22) is arranged on the inner wall of the shell body (21) of the middle shell (2); A flange (55) is arranged on the outer circular 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 part (22) of the middle shell (2).

9. The optimized structure of the LNG wound tube heat exchanger according to claim 8, characterized in that: A plurality of limiting grooves (52) are arranged on the body (51) of the fixing ring (5); A plurality of bosses (23) extending 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 fixing ring (5) in the limiting part (22) of the middle shell (2).

10. The optimized structure of the LNG wound tube heat exchanger according to claim 9, characterized in that: The length of the second connecting pipe (613) in the outer winding tube (6) is less than the length of the second connecting pipe in the inner winding tube (7); The length of the first connecting pipe (611) in the outer winding tube (6) is greater than the length of the first connecting pipe in the inner winding tube (7); The depth of the first card slot (53) in the fixed ring (5) is greater than the depth of the second card slot (54).

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