High-vacuum multi-layer heat insulation double-wall vacuum pipeline sealing structure suitable for LNG (Liquefied Natural Gas) ship

Abstract

The invention discloses a high-vacuum multi-layer heat insulation double-wall vacuum pipeline sealing structure suitable for an LNG (Liquefied Natural Gas) ship. The structure comprises a prefabricated pipe section and an assembly pipe section, the prefabricated pipe section is provided with an interlayer, and the interlayer is provided with a sealing assembly and a first vacuumizing assembly; the assembling pipe section comprises a pre-tightening spring assembly, an interlayer conduction operation assembly and an outer pipe assembly, the pre-tightening spring assembly is arranged on the inner side of the outer pipe assembly and connected with the sealing assembly, and the interlayer conduction operation assembly penetrates through the outer pipe assembly and is connected with the pre-tightening spring assembly; the interlayer conduction operation assembly can drive the sealing assembly to move through the pre-tightening spring assembly. According to the structure, a mature land vacuum pipe production process, namely a high-vacuum multi-layer heat insulation production process, can be applied to the marine vacuum pipeline, so that the vacuum service life of the high-vacuum double-wall pipeline for the LNG ship is remarkably prolonged, a large amount of evacuation time is saved, and the vacuum heat insulation performance of the pipeline can be guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of LNG powered ships, and further to a double-wall vacuum pipeline sealing structure suitable for high vacuum multi-layer insulation of LNG ships. Background Art

[0002] LNG powered ships use LNG fuel as the main energy source or use dual-fuel engines. Compared with traditional diesel powered ships, LNG fuel has the characteristics of strong economy and emission reduction. It can save operators 20% of fuel costs and reduce ship carbon dioxide emissions by about 20%. It is widely used in the field of powered ships. Since LNG is a low-temperature medium, it is easy to vaporize when heated and is flammable and explosive. Therefore, LNG powered ships need to be equipped with vacuum insulated vacuum pipelines as the best way to transmit and transfer LNG. It can effectively reduce heat leakage during the transmission process to maintain the liquefied state of LNG and avoid accidents. At present, domestic LNG ship vacuum pipelines generally have a short vacuum life due to process limitations. Often, the pipeline insulation performance is poor due to vacuum failure in about 3 months. However, land-based vacuum pipelines have widely adopted mature high-vacuum multi-layer insulation production processes, which can easily achieve a vacuum life of more than 3 years, which is a significant gap.

[0003] The reason for the difference between the two is: first, the special requirements of the marine LNG vacuum double-wall pipe for the pipe sandwich structure. Since the LNG marine vacuum pipeline is laid through a relatively small and closed area of ​​the ship, in order to ensure the safety of the vacuum double-wall pipe in the event of a rupture and leakage of the inner pipe and meet the safety requirements of the ship construction specifications, the leaked medium is discharged uniformly and centrally through the sandwich space between the inner and outer pipes, that is, the vacuum sandwich between the inner and outer pipes of this long pipeline is required to be connected. In order to ensure the vacuum degree, vacuum life, and ease of production, the land-based vacuum pipeline divides the long pipeline into short sections, evacuates them separately, and connects them on site through welding or vacuum flange-type structures; the inner and outer pipes are composed of relatively independent vacuum sandwich spaces, and vacuum treatment has obvious advantages.

[0004] Secondly, the manufacturing and construction processes are different. At present, the ship LNG vacuum pipeline is generally insulated by vacuum insulation. This process cannot effectively carry out material degassing. In addition, the vacuum interlayer between the inner and outer pipes of the ship LNG vacuum pipeline is small, and it is not covered with multi-layer insulation materials to reduce radiation heat leakage. The vacuum degree is maintained for a short time and the insulation effect is poor. Land vacuum pipelines are mostly insulated by high vacuum multi-layer insulation. High vacuum multi-layer insulation is also called "super insulation". At the same time, adsorbents are added during the production process, which can effectively absorb the gas released by the interlayer under vacuum to maintain the vacuum life. Therefore, its insulation performance and vacuum life are significantly better than the former. The production method and production environment are also different. The segment length of land vacuum pipelines is generally not more than 6m; it is made in a clean and dust-free environment to avoid water vapor, grease, dust and other pollution that seriously reduce the vacuum performance; due to the small size of the structure, it is convenient to heat, replace, degas and evacuate in the oven, and it is easy to achieve high vacuum.

[0005] At present, the marine vacuum double-wall pipeline needs to be spliced ​​into a long pipeline on site, and then evacuated as a whole. During the construction process, the interlayer is exposed to the air, especially in the open air, and is greatly affected by the environment such as water vapor, oil pollution, paint and even operational accidents. In particular, water in the interlayer will greatly extend the evacuation time. Even if multi-layer insulation is used to maintain the vacuum life, the water absorption characteristics of the insulation material and the adsorbent are not conducive to evacuation. In addition, it is difficult to heat the long pipeline, and the long pipeline has a large flow resistance. It takes a long period to achieve a high vacuum degree, the effect is poor, and the cost is high.

[0006] Therefore, it is necessary to design a double-wall vacuum pipe sealing structure suitable for LNG ship high vacuum multi-layer insulation to ensure the implementation of the high vacuum multi-layer insulation process. Summary of the invention

[0007] In view of the above technical problems, the purpose of the present invention is to provide a double-wall vacuum pipe sealing structure suitable for LNG ship high vacuum multi-layer insulation. Through this structure, the mature land-based vacuum pipe production process, namely the high vacuum multi-layer insulation production process, can be applied to ship vacuum pipes, significantly extending the vacuum life of LNG ship high vacuum double-wall pipes, saving a lot of evacuation time and ensuring the vacuum insulation performance of the pipeline.

[0008] In order to achieve the above-mentioned object, the present invention provides a double-wall vacuum pipeline sealing structure suitable for LNG ship high vacuum multi-layer insulation, including a prefabricated pipe section and an assembled pipe section;

[0009] The prefabricated pipe section has an interlayer, and the interlayer is provided with a sealing component for sealing the interlayer, and a first vacuuming component for vacuuming the interlayer;

[0010] The assembly pipe section includes a pre-tensioning spring component, a sandwich conduction operating component and an outer tube component. The outer tube component is sleeved on the end of the inner tube. The pre-tensioning spring component is arranged on the inner side of the outer tube component and is connected to the sealing component. The sandwich conduction operating component passes through the outer tube component and is connected to the pre-tensioning spring component. The sandwich conduction operating component can drive the sealing component to move through the pre-tensioning spring component to control the conduction and sealing between the outer tube and the inner tube. The outer tube component is provided with a second vacuuming component for vacuuming the assembled prefabricated pipe section and the assembly pipe section.

[0011] In some embodiments, the prefabricated pipe segment includes an inner tube, an outer tube and at least one sealing assembly, the inner tube is inserted into the outer tube, and both ends extend out of the outer tube by a preset length, the interlayer is formed between the outer tube and the inner tube, and the outer tube is sealed and connected to the inner tube through the sealing assembly.

[0012] In some embodiments, the sealing assembly includes an outer tube sealing ring, a sandwich sealing ring, a rubber sealing ring, a tension ring, a fixing ring, a compression bolt, a sealing compensation bellows, a spacer block group and a spacer ring;

[0013] The outer tube sealing ring is fixed to the inner wall of the outer tube, the rubber sealing ring is fixed to the outer wall of the sealing compensation bellows, the sandwich sealing ring is fixed to the rubber sealing ring, the sandwich sealing ring, the rubber sealing ring and the sealing compensation bellows form a sandwich sealing body, one end of the sandwich sealing body is fixed to the outer wall of the inner tube, and the other end of the sandwich sealing body realizes the sealing of the inner and outer tube sandwich space through the radial direction and end surface of the rubber sealing ring and the outer tube sealing ring;

[0014] The fixing ring is fixed on the inner tube, and the clamping bolt passes through the fixing ring and is threadedly connected with the outer tube sealing ring, so that the clamping bolt can clamp the sealing surface between the outer tube sealing ring and the sandwich sealing ring;

[0015] The spacer block group is installed on the inner wall of the sealing compensation bellows through the spacer ring, and the tension ring is arranged on the sandwich sealing ring. The sandwich sealing ring can be moved by pulling the tension ring outward to conduct the sandwich spaces on both sides.

[0016] In some embodiments, the spacer group includes a plurality of polytetrafluoroethylene spacers arranged at intervals, and the polytetrafluoroethylene spacers are used to reduce the heat leakage of the sandwich seal to the outer tube and reduce the operating friction resistance when the sandwich is turned on;

[0017] The rubber sealing ring is coated with a first thermal insulation blanket, and the first thermal insulation blanket is used to reduce radiation heat leakage between the inner tube and the outer tube;

[0018] The first vacuum pumping assembly comprises a vacuum port and a vacuum plug, wherein the vacuum port is arranged at the connection between the outer tube and the inner tube and communicates with the interlayer between the outer tube and the inner tube, and the vacuum plug is detachably connected to the vacuum port;

[0019] A reducing pipe joint is fixed to the end of the outer pipe, the outer diameter of the reducing pipe joint is greater than the outer diameter of the outer pipe, and the reducing pipe joint is used to increase the gap between the inner pipe and the outer pipe.

[0020] In some embodiments, the preload spring assembly includes a main spring component, an anti-loosening component, a spring seat, a spring limiting disk and a limiting nut;

[0021] The spring seat is fixed on the inner tube, the main spring component, the anti-loosening component, the spring limiting disk and the limiting nut are arranged on the spring seat, one end of the main spring component is connected to the tension ring of the prefabricated pipe section, the other end of the main spring component limits the restoring force of the spring preload through the spring limiting disk and the limiting nut, one end of the anti-loosening component presses the sandwich sealing ring of the sealing assembly, and the other end of the anti-loosening component presses the spring limiting disk;

[0022] The spring limiting disk is provided with a first through hole and a second through hole. When the spring limiting disk is rotated by a preset angle, one end of the main spring component away from the sealing assembly can extend from the first through hole, and one end of the anti-loosening component away from the sealing assembly can extend from the second through hole, thereby driving the interlayer sealing ring of the sealing assembly to detach from the sealing surface and connect the interlayers on both sides.

[0023] In some embodiments, the main spring component includes a main limit nut, a tension bolt, a spring rod, a spring washer, a main coil spring, a main butterfly spring and an adjusting nut, the main butterfly spring is sleeved on the spring rod, the main coil spring is sleeved on the main butterfly spring, one end of the spring rod passes through one end of the spring seat and is connected to the tension bolt, one end of the tension bolt away from the spring seat passes through the tension ring of the prefabricated pipe section and is connected to the main limit nut, and the other end of the spring rod passes through the spring washer, the main coil spring, the main butterfly spring and the adjusting nut in sequence;

[0024] The anti-loosening component comprises a first anti-loosening screw, an anti-loosening nut, a small butterfly spring, a small butterfly spring seat and a second anti-loosening screw, wherein the small butterfly spring is inserted in the small butterfly spring seat, the first anti-loosening screw passes through one end of the spring seat, the anti-loosening nut, the small butterfly spring, the small butterfly spring seat and is connected with the second anti-loosening screw in sequence, and an end of the second anti-loosening screw away from the first anti-loosening screw is pressed against the other end of the spring seat;

[0025] When the spring limiting disk rotates to a preset angle, the spring rod can extend from the first through hole, and the second anti-loosening screw can extend from the second through hole, thereby driving the interlayer sealing ring of the sealing assembly to separate from the sealing surface and connect the interlayers on both sides.

[0026] In some embodiments, the main spring component is provided in plurality, and the plurality of main spring components are arranged at intervals along the circumference of the spring seat;

[0027] The anti-loosening components are provided in plurality, and the plurality of anti-loosening components are arranged at intervals along the circumference of the spring seat and are arranged in a staggered manner with the main spring components;

[0028] A plurality of the first through holes and the second through holes are provided, and when the spring limiting plate rotates by a preset angle, each of the spring rods can extend from the corresponding first through hole, and each of the second anti-loosening screws can extend from the corresponding second through hole;

[0029] The outer side of the preload spring assembly is covered with a second thermal insulation blanket, and the second thermal insulation blanket is used to reduce radiation heat leakage between the inner tube and the outer tube.

[0030] In some embodiments, the sandwich conduction operation assembly includes an assembly tube evacuation plug, an evacuation plug sealing ring, a sliding rod, a positioning pin shaft, a connecting rod, a rotating rod, a locking rod, a supporting spring and a locking device, and the second vacuuming assembly includes an assembly tube evacuation port;

[0031] The evacuation plug sealing ring is installed on the evacuation plug of the assembly tube, and the evacuation plug of the assembly tube is installed on the evacuation port of the assembly tube; the sliding rod is arranged on the lower side of the evacuation plug of the assembly tube, the sliding rod is connected with the connecting rod through the positioning pin shaft, the connecting rod is rotatably connected with the rotating rod, and the rotating rod is connected with the spring limiting disk, the sliding rod, the positioning pin shaft, the connecting rod, the rotating rod and the spring limiting disk form a set of crank slider components, when the evacuation plug of the assembly tube is pressed down, the crank slider component is driven to drive the spring limiting disk to rotate, and when the evacuation plug of the assembly tube is lifted up, the evacuation plug of the assembly tube moves up and disengages from the sliding rod;

[0032] The locking rod is fixed on the sliding rod, and the supporting spring is sleeved on the locking rod, so as to enable the assembly tube evacuation plug to contact the locking rod in the initial installation state. The locking device is fixed on the outer wall of the inner tube. When the assembly tube evacuation plug moves downward and the locking rod moves downward to the lower limit, the locking device locks the locking rod to keep the sliding rod stationary.

[0033] In some embodiments, the outer tube assembly includes a split outer tube, a heat-conducting rod, a welding protection cap and a pressing tool, the two ends of the split outer tube are respectively connected to the inner tubes on both sides, the assembly tube evacuation port is arranged on one side of the split outer tube, the welding protection cap is welded and sealed to the assembly tube evacuation port, the heat-conducting rod is arranged on the welding protection cap, and the pressing tool is threadedly connected to the outer side of the assembly tube evacuation port.

[0034] In some embodiments, at least two prefabricated pipe segments are provided, and every two prefabricated pipe segments are connected by the assembly pipe segment;

[0035] The assembled pipe section includes two pre-tensioning spring assemblies, one pre-tensioning spring assembly is connected to the sealing assembly of one prefabricated pipe section, and the other pre-tensioning spring assembly is connected to the sealing assembly of another prefabricated pipe section. The two pre-tensioning spring assemblies are respectively connected to the interlayer conduction operating assemblies, so that the interlayer conduction operating assembly can drive the two sealing assemblies to move synchronously through the two pre-tensioning spring assemblies.

[0036] Compared with the prior art, the double-wall vacuum pipeline sealing structure suitable for LNG ship high vacuum multi-layer insulation provided by the present invention has at least one of the following beneficial effects:

[0037] 1. The present invention has a reliable long vacuum life and excellent thermal insulation performance. Since the production of long pipelines is divided into workshop prefabricated vacuum pipe sections and on-site assembled pipe sections, the length of the workshop prefabricated vacuum pipe sections accounts for about 90%. The vacuum production process of high vacuum multi-layer insulation can ensure a long vacuum life and excellent thermal insulation performance, which can significantly improve the vacuum life and thermal insulation performance of the existing production process; by adopting a specially designed sealing structure to ensure the sealing of the on-site construction process, the insulation blanket, low-temperature adsorbent, etc. can be isolated from contact with the environment, avoiding the influence of environmental moisture, oil pollution, and impurity gases, extending the vacuum life and ensuring thermal insulation performance; the special structural design of the vacuum port execution unit avoids the occurrence of conduction heat leakage, and the sealing structure is coated with multi-layer insulation materials to effectively reduce radiation heat leakage.

[0038] 2. In the present invention, the on-site evacuation effect is excellent and the work efficiency can be significantly improved. Since most of the entire long vacuum pipeline is prefabricated in the workshop, the workload on site can be greatly reduced. In terms of structural design and operation, the independent interlayer formed after the butt joint of the pipe section can be evacuated separately by a small pump (i.e., a small vacuum is drawn on the prefabricated pipe section), and then the vacuum interlayer of the butt joint section and the independent interlayer are connected and merged into the vacuum interlayer of the long pipeline to be evacuated by a large pump (i.e., a large vacuum is drawn on the assembled pipe section); since the sealing structure before the pipe section is butt jointed can ensure the sealing, the evacuation work is not affected during the butt joint construction, and a step-by-step evacuation working mode is realized (i.e., the large pump starts to evacuate from 2 butt joint sections, and gradually increases to 3, 4... the last section); since most of the pipe sections have achieved high vacuum in the workshop and the construction time is fully utilized to evacuate the pipeline interlayer at the same time, the evacuation effect of the pipeline is significantly better than the existing process and the work efficiency is significantly improved.

[0039] 3. In the present invention, the sealing structure is reliable, and the prefabricated vacuum tube adopts radial and planar two-layer sealing ring sealing structure, and the corresponding sealed main structure is connected by welding to ensure reliable sealing; flexible supplementation is achieved by bellows to ensure effective compensation when the inner and outer tubes are produced on site, without affecting the sealing effect; the bolt compression method can ensure that the sealing of the prefabricated section is not affected during transportation and construction to maintain the vacuum degree of the prefabricated pipe section; after the pipe sections are butt-jointed, the independent interlayer of the assembled pipe sections is evacuated, and after evacuation, the evacuation port is welded by a protective cap to ensure the reliability of the seal; the special sealing ring destruction treatment process after the protective cap is welded can eliminate the possibility of aging and failure of the sealing plug to destroy the vacuum.

[0040] 4. In the present invention, the vacuuming efficiency is high and the reliability is good. Most of the pipe sections of the long pipeline are vacuum treated in the workshop, which significantly reduces a large amount of on-site vacuuming work. The independent space before the vacuum pipe section is sealed is opened when the pipe section is assembled, which is convenient for heating, replacement and vacuuming. The vacuuming and assembly of the pipe section can be carried out in parallel with high efficiency. The assembly and operation process are carried out in a sealed environment without being affected by the environment and has high reliability.

[0041] 5. In the present invention, the sealing structure is universal and has good expansibility. The vacuum interlayer of the inner and outer tubes of various specifications of marine vacuum pipelines is about 25 mm, and the sealing structure can be applied to pipes with different diameters. When the inner and outer diameters change, the annular surfaces corresponding to the inner and outer tubes become larger, and the number of pre-tightening spring assemblies, clamping bolts, and loosening bolts that can be arranged can be adjusted accordingly, and the expansibility is good. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The preferred implementation modes will be described below in a clear and understandable manner with reference to the accompanying drawings to further illustrate the above-mentioned characteristics, technical features, advantages and implementation methods of the present invention.

[0043] Figure 1It is a structural schematic diagram of a double-wall vacuum pipeline sealing structure suitable for high vacuum multi-layer insulation for LNG ships in a preferred embodiment of the present invention;

[0044] Figure 2 is a schematic structural diagram of a prefabricated pipe section in a preferred embodiment of the present invention;

[0045] Figure 3 is a front view of an assembled pipe section of a preferred embodiment of the present invention;

[0046] Figure 4 is a side view of an assembled pipe section of a preferred embodiment of the present invention;

[0047] Figure 5 It is a structural schematic diagram of a closed state of a preload spring assembly in a preferred embodiment of the present invention;

[0048] Figure 6 It is a structural schematic diagram of a preload spring assembly in an open state in a preferred embodiment of the present invention;

[0049] Figure 7 It is a structural schematic diagram of the conductive state of two adjacent prefabricated pipe sections in a preferred embodiment of the present invention;

[0050] Figure 8 It is a side view of the conductive state of two adjacent prefabricated pipe sections in a preferred embodiment of the present invention;

[0051] Fig. 9 is a schematic structural diagram of a spacer block group in a preferred embodiment of the present invention;

[0052] Fig.10 It is a structural schematic diagram of an evacuation port of an assembly pipe according to a preferred embodiment of the present invention;

[0053] Fig.11 It is a structural schematic diagram of a prefabricated pipe section in another preferred embodiment of the present invention.

[0054] Description of Figure Numbers:

[0055] Prefabricated pipe section 1, sealing assembly 11, outer pipe sealing ring 111, sandwich sealing ring 112, rubber sealing ring 113, tension ring 114, fixing ring 115, tightening bolt 116, sealing compensation bellows 117, first insulation quilt 118, spacer block group 119, spacer 1110, evacuation port 1111, evacuation plug 1112, inner pipe 12, outer pipe 13, reducing pipe joint 131, assembled pipe section 2, preload spring assembly 21, main limit nut 211, tension bolt 212, spring rod 213, spring seat 214, spring washer 215, main coil spring 216, main butterfly spring 217, adjusting nut 218, spring limit plate 219, first through hole 2191, second through hole 2192, limit screw Mother 2110, first anti-loosening screw 2111, anti-loosening nut 2112, small butterfly spring 2113, small butterfly spring seat 2114, second anti-loosening screw 2115, second thermal insulation quilt 2116, interlayer conduction operation assembly 22, assembly tube evacuation plug 221, evacuation plug sealing ring 222, sliding rod 223, positioning pin shaft 224, connecting rod 225, rotating rod 226, locking rod 227, supporting spring 228, locking device 229, outer tube assembly 23, split outer tube 231, assembly tube evacuation port 232, first welding water cooling part 2321, second welding water cooling part 2322, heating part 2323, thin-walled structure 2324, heat conducting rod 233, welding protection cap 234, pressing tool 235. DETAILED DESCRIPTION

[0056] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the specific implementation methods of the present invention will be described below with reference to the accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings and other implementation methods can be obtained based on these drawings without creative work.

[0057] In order to simplify the drawings, only the parts related to the invention are schematically shown in each figure, and they do not represent the actual structure of the product. In addition, in order to simplify the drawings and facilitate understanding, in some figures, only one of the parts with the same structure or function is schematically drawn or marked. In this article, "one" not only means "only one", but also means "more than one".

[0058] It should be further understood that the term “and / or” used in the specification and appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0059] In this document, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0060] In addition, in the description of the present application, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0061] In one embodiment, the reference specification Figures 1 to 4 The present invention provides a double-wall vacuum pipe sealing structure suitable for high vacuum multi-layer insulation of LNG ships, comprising a prefabricated pipe section 1 and an assembled pipe section 2. The prefabricated pipe section 1 has an interlayer, and the interlayer is provided with a sealing component 11 for sealing the interlayer, and a first vacuum pumping component for vacuuming the interlayer; the assembled pipe section 2 includes a preload spring component 21, an interlayer conduction operating component 22 and an outer tube component 23, the outer tube component 23 is sleeved on the end of the inner tube 12, the preload spring component 21 is provided on the inner side of the outer tube component 23, and is connected to the sealing component 11, the interlayer conduction operating component 22 passes through the outer tube component 23 and is connected to the preload spring component 21, the interlayer conduction operating component 22 can drive the sealing component 11 to move through the preload spring component 21 to control the conduction and sealing between the outer tube 13 and the inner tube 12, and the outer tube component 23 is provided with a second vacuum pumping component for vacuuming the assembled double-wall vacuum pipe sealing structure.

[0062] In this embodiment, the double-wall vacuum pipeline sealing structure suitable for LNG ship high vacuum multi-layer insulation is composed of a prefabricated pipe section 1 produced in a workshop and an assembly pipe section 2 assembled on site. In the entire pipeline, the prefabricated pipe section 1 accounts for an absolute majority (about 90%), which is produced in the workshop using a high vacuum multi-layer insulation process and then evacuated, and assembled on board with the assembly pipe section 2 assembled on site to form a long pipeline. The prefabricated pipe section 1 and the assembly pipe section 2 have independent vacuum interlayers during the assembly process. After the prefabricated pipe section 1 is evacuated by a small vacuum pump group, the vacuum interlayer between the prefabricated pipe section 1 and the assembly pipe section 2 is conducted by using a preload spring assembly 21 and an interlayer conduction operation assembly 22, and then the whole is evacuated by a large vacuum pump group.

[0063] The prefabricated pipe section 1 produced in the workshop is produced in a clean, dust-free and dry environment according to the manufacturing process of land-based vacuum pipes, and has significantly excellent thermal insulation performance and long vacuum life. The assembly pipe section 2 assembled on site is cleaned and degreased in the workshop, spliced ​​and welded on site, and then the assembly pipe section 2 is evacuated, and the adjacent pipe sections are connected after evacuation. The connection operation of the adjacent pipe section interlayer is carried out in a sealed environment to prevent environmental pollution. Therefore, the overall pipeline can achieve a higher vacuum degree and maintain a longer vacuum life, ensuring the thermal insulation performance of the entire pipeline.

[0064] In one embodiment, the reference specification Figure 2 The prefabricated pipe section 1 includes an inner pipe 12, an outer pipe 13 and two sealing assemblies 11. The inner pipe 12 is inserted into the outer pipe 13, and both ends extend out of the outer pipe 13 by a preset length. There is a sandwich between the outer pipe 13 and the inner pipe 12, and both ends of the outer pipe 13 are sealed and connected to the inner pipe 12 through the sealing assemblies 11. The sealing assembly 11 includes an outer pipe sealing ring 111, a sandwich sealing ring 112, a rubber sealing ring 113, a tension ring 114, a fixing ring 115, a clamping bolt 116, a sealing compensation bellows 117, a spacer block group 119 and a spacer 1110. The outer pipe sealing ring 111 is welded and fixed to the inner wall of the outer pipe 13, or the outer pipe sealing ring 111 and the outer pipe 13 are integrally processed and formed. The sandwich sealing ring 112, the rubber sealing ring 113, and the sealing compensation bellows 117 are connected together to form a sandwich sealing body. One end of the sandwich sealing body is welded to the outer wall of the inner tube 12 to seal and fix the sealing body; the other end of the sandwich sealing body is sealed through the radial direction and end surface of the rubber sealing ring 113 and the outer tube sealing ring 111 to achieve the sealing of the inner and outer tube sandwich space. The fixing ring 115 is fixed on the inner tube 12, and the sealing surfaces of the outer tube sealing ring 111 and the sandwich sealing ring 112 are compressed by the compression bolts 116 to ensure reliable sealing and prevent leakage during subsequent operations.

[0065] Reference Manual Attached Fig. 9 The spacer block group 119 is installed on the inner wall of the sealing compensation bellows 117 through the spacer ring 1110. The spacer block group 119 includes a plurality of spaced polytetrafluoroethylene spacers. The advantages of polytetrafluoroethylene's low thermal conductivity and low friction coefficient are used to reduce the heat leakage of the sandwich sealing body to the outer tube 13 and reduce the operating friction resistance when the sandwich is connected. The spacer block group 119 adopts a split structure to ensure the penetration of the evacuation channel when the vacuum pipeline is evacuated.

[0066] Reference Manual Attached Figure 2The tension ring 114 is arranged on the sandwich sealing ring 112. The outer tension ring 114 can move the sandwich sealing ring 112 to connect the sandwich spaces on both sides. The outer side of the sealing component 11 is coated with a first insulation blanket 118. The first insulation blanket 118 is used to reduce the radiation heat leakage between the inner tube 12 and the outer tube 13. The first vacuum assembly includes an evacuation port 1111 and an evacuation plug 1112. The evacuation port 1111 is arranged at the connection between the outer tube 13 and the inner tube 12, and is connected to the sandwich between the outer tube 13 and the inner tube 12. The evacuation plug 1112 is detachably connected to the evacuation port 1111, and is used for evacuating the prefabricated pipe section 1 in the workshop.

[0067] Reference Manual Attached Fig.11 The two ends of the outer tube 13 are fixed with reducing pipe joints 131, the outer diameter of the reducing pipe joint 131 is larger than the outer diameter of the outer tube 13, and the reducing pipe joint 131 is used to increase the gap between the inner tube 12 and the outer tube 13 to avoid contact between the inner and outer tubes and cause heat conduction.

[0068] In this embodiment, the sealing compensation bellows 117 mainly realizes the axial displacement required for the conduction of the interlayers on both sides under the sealed state. The spacer group 119 and the sealing compensation bellows 117 are matched with a large gap. Together with the compensation effect of the sealing compensation bellows 117, the installation and manufacturing errors between the inner and outer pipes can be compensated, and it is also convenient for adjusting the docking position between different pipe sections on site, and ensuring that the interlayer seal is not affected during the adjustment process; the sealing compensation bellows 117 has a thin wall thickness, a long unfolded length, and a large relative thermal resistance. A relatively long "thermal bridge" structure is formed by the inner pipe 12 through the sealing compensation bellows 117 and the interlayer sealing ring 112, which can effectively reduce heat leakage.

[0069] It should be noted that the structures of the sealing components 11 on both sides are basically the same, except that a first vacuum assembly is provided at the sealing component 11 on one side. The prefabricated pipe section 1 needs to be insulated and coated, adsorbent installed, and heated and replaced for evacuation in a clean and dust-free workshop; through the application of the sealing components on both sides, the production requirements of land-based vacuum tubes are fully met. The specific structure of the sealing component 11 is explained in accordance with the drawings in the specification. In actual use, it can also be changed according to actual needs. As long as the structure or device can achieve the above-mentioned functions, it is acceptable. This is only for better explanation of the present invention and should not constitute a limitation to the present invention.

[0070] In one embodiment, the reference specification Figures 3 to 7The preload spring assembly 21 includes a main spring component, an anti-loosening component, a spring seat 214, a spring limiting disk 219 and a limiting nut 2110; the spring seat 214 is fixed to the inner tube 12 by welding, and the main spring component, the anti-loosening component, the spring limiting disk 219 and the limiting nut 2110 are arranged on the spring seat 214, one end of the main spring component is connected to the tension ring 114 of the prefabricated pipe section 1, and the other end of the main spring component limits the restoring force of the spring preload by the spring limiting disk 219 and the limiting nut 2110, one end of the anti-loosening component presses the sandwich sealing ring 112 of the sealing assembly 11, and the other end of the anti-loosening component presses the spring limiting disk 219. The spring limiting disk 219 is provided with a first through hole 2191 and a second through hole 2192. When the spring limiting disk 219 is rotated by a preset angle, one end of the main spring component away from the sealing component 11 can extend from the first through hole 2191, and one end of the anti-loosening component away from the sealing component 11 can extend from the second through hole 2192, thereby driving the interlayer sealing ring 112 of the sealing component 11 to detach from the sealing surface and connect the interlayers on both sides.

[0071] Specifically, the main spring component includes a main limit nut 211, a tension bolt 212, a spring rod 213, a spring washer 215, a main coil spring 216, a main butterfly spring 217 and an adjusting nut 218. The main butterfly spring 217 is sleeved on the spring rod 213, and the main coil spring 216 is sleeved on the main butterfly spring 217. One end of the spring rod 213 passes through one end of the spring seat 214 and is connected with the tension bolt 212. The end of the tension bolt 212 away from the spring seat 214 passes through the tension ring 114 of the prefabricated pipe section 1 and is connected with the main limit nut 211. The other end of the spring rod 213 passes through the spring washer 215, the main coil spring 216, the main butterfly spring 217 and the adjusting nut 218 in sequence. The adjusting nut 218 is used to adjust the spring preload; the main butterfly spring 217 has small deformation and large preload, and is used to overcome the friction resistance of the sealing surface; the main coil spring 216 has a small preload and a large stroke, and is used to have a sufficient conduction distance after the sealing surface is separated.

[0072] The anti-loosening component includes a first anti-loosening screw 2111, an anti-loosening nut 2112, a small butterfly spring 2113, a small butterfly spring seat 2114 and a second anti-loosening screw 2115. The small butterfly spring 2113 is inserted in the small butterfly spring seat 2114. The first anti-loosening screw 2111 passes through one end of the spring seat 214, the anti-loosening nut 2112, the small butterfly spring 2113, the small butterfly spring seat 2114 and is connected with the second anti-loosening screw 2115 in sequence. The end of the second anti-loosening screw 2115 away from the first anti-loosening screw 2111 is pressed against the other end of the spring seat 214; the small butterfly spring 2113 is used to make one end of the anti-loosening component press the sandwich sealing ring 111, and the other end presses the spring limit plate 219. When assembling the pipe section 2, the clamping bolt 116 needs to be removed in advance, and the small butterfly spring seat 2114 is adjusted to be pre-tightened to prevent the sealing structure from loosening and affecting the sealing of the vacuum pipe section.

[0073] When the spring limiting disk 219 rotates to a preset angle, the spring rod 213 can extend from the first through hole 2191, and the second anti-loosening screw 2115 can extend from the second through hole 2192, thereby driving the sandwich sealing ring 112 of the sealing assembly 11 to separate from the sealing surface and connect the sandwich layers on both sides.

[0074] Further, a plurality of main spring components are provided, and the plurality of main spring components are arranged at intervals along the circumference of the spring seat 214; a plurality of anti-loosening components are provided, and the plurality of anti-loosening components are arranged at intervals along the circumference of the spring seat 214, and are arranged in an interlaced manner with the main spring components; a plurality of first through holes 2191 and a plurality of second through holes 2192 are provided, and when the spring limiting plate 219 rotates a preset angle, each spring rod 213 can extend from the corresponding first through hole 2191, and each second anti-loosening screw 2115 can extend from the corresponding second through hole 2192. The outer side of the preload spring assembly 21 is coated with a second insulation blanket 2116, and the second insulation blanket 2116 is used to reduce the radiation heat leakage between the inner tube 12 and the outer tube 13. Considering that the eccentricity of the inner and outer tubes generates additional resistance, the spring preload force is adjusted by adjusting the nut 218; a plurality of main spring components are evenly distributed in the circumferential direction, so that the spring force is multiplied to ensure that the vacuum interlayer conduction has sufficient pulling force.

[0075] It should be noted that the specific structure of the preload spring assembly 21 is described in accordance with the drawings in the specification. In actual use, it can also be changed accordingly according to actual needs. As long as the structure or device can achieve the above-mentioned function, it is only for better illustrating the present invention and should not constitute a limitation to the present invention.

[0076] In one embodiment, the reference specification Figures 3 to 8The interlayer conduction operation component 22 includes an assembly tube evacuation plug 221, an evacuation plug sealing ring 222, a sliding rod 223, a positioning pin shaft 224, a connecting rod 225, a rotating rod 226, a locking rod 227, a supporting spring 228 and a locking device 229, and the second vacuum pumping component includes an assembly tube evacuation port 232.

[0077] The evacuation plug sealing ring 222 is installed on the assembly tube evacuation plug 221, and the assembly tube evacuation plug 221 is installed on the assembly tube evacuation port 232, and is used to seal the assembly tube evacuation port 232. The sliding rod 223 is arranged on the lower side of the assembly tube evacuation plug 221, and the sliding rod 223 is connected to the connecting rod 225 through the positioning pin shaft 224, and the connecting rod 225 is rotatably connected to the rotating rod 226, and the rotating rod 226 is connected to the spring limiting disk 219. The sliding rod 223, the positioning pin shaft 224, the connecting rod 225, the rotating rod 226 and the spring limiting disk 219 form a set of crank slider components. When the assembly tube evacuation plug 221 is pressed down, the crank slider component drives the spring limiting disk 219 to rotate, and when the assembly tube evacuation plug 221 is lifted up, the assembly tube evacuation plug 221 moves up and disengages from the sliding rod 223.

[0078] The locking rod 227 is fixed on the sliding rod 223, and the supporting spring 228 is sleeved on the locking rod 227, which is used for the assembly tube evacuation plug 221 to contact the locking rod 227 in the initial installation state. The locking device 229 is fixed on the outer wall of the inner tube 12, and the locking device 229 can be a quick-insertion standard part of a steel ball locking or a snap ring locking type. When the assembly tube evacuation plug 221 moves down and the locking rod 227 moves down to the lower limit, the locking device 229 locks the locking rod 227, so that the sliding rod 223 remains stationary, and the assembly tube evacuation plug 221 moves up and is out of contact with it, which can effectively prevent conduction heat leakage between the sliding rod 223 and the sealing plug.

[0079] Reference Manual Attached Figures 3 to 8 The outer tube assembly 23 includes a split outer tube 231, a heat conducting rod 233, a welding protective cap 234 and a pressing tool 235. The two ends of the split outer tube 231 are respectively connected to the inner tubes 12 on both sides. The assembly tube evacuation port 232 is arranged on one side of the split outer tube 231. The welding protective cap 234 is welded and sealed with the assembly tube evacuation port 232. The heat conducting rod 233 is arranged on the welding protective cap 234. The pressing tool 235 is threadedly connected with the outer side of the assembly tube evacuation port 232. The assembly tube evacuation port 232 is used for replacement, evacuation, and interlayer conduction operations of the on-site assembly pipe section 2.

[0080] Reference Manual Attached Fig.10The top of the assembly pipe evacuation port 232 extends upward to form a first welding water cooling part 2321, and the second welding water cooling part 2322 is arranged on both sides of the assembly pipe evacuation port 232. The thin-walled structure 2324 is arranged on both sides of the inner part of the assembly pipe evacuation port 232, and the heating part 2323 is arranged near the heat conducting rod 233 at the top of the assembly pipe evacuation port 232. On the one hand, this structure can extend the heat conduction path, and on the other hand, water cooling protection can be provided at the second welding water cooling part 2322 on both sides of the welding part during welding to prevent the evacuation plug sealing ring 222 from being damaged during welding to affect the sealing. The heat conducting rod 233 is made of copper for heat conduction, and the welding protective cap 234 is welded and sealed with the assembly pipe evacuation port 232. After the assembly pipe evacuation port 232 is sealed, the top area of ​​the protective cap is heated to damage the evacuation plug sealing ring 222, and the residual gas between the welding protective cap 234 and the assembly pipe evacuation port 232 is passed into the pipeline interlayer in advance to be evacuated, so as to ensure the reliability of the final long pipeline sealing. Considering the large pressing force of the preload spring assembly 21 , the pressing fixture 235 and the assembly tube evacuation port 232 overcome the rotational resistance generated by the preload spring assembly 21 through threaded force transmission to achieve the rotation of the spring limit plate 219 .

[0081] It should be noted that the specific structure of the interlayer conduction operation component 22 and the outer tube component 23 is described in accordance with the drawings in the specification. In actual use, they can also be changed accordingly according to actual needs. As long as the structure or device can achieve the above-mentioned functions, it is only for better illustrating the present invention and should not constitute a limitation to the present invention.

[0082] In one embodiment, the reference specification Figure 1 At least two prefabricated pipe sections 1 are provided, and every two prefabricated pipe sections 1 are connected by an assembly pipe section 2. The assembly pipe section 2 includes two preload spring assemblies 21, one preload spring assembly 21 is connected to the sealing assembly 11 of one prefabricated pipe section 1, and the other preload spring assembly 21 is connected to the sealing assembly 11 of another prefabricated pipe section 1. The two preload spring assemblies 21 are respectively connected to the interlayer conduction operation assembly 22, so that the interlayer conduction operation assembly 22 can drive the two sealing assemblies 11 to move synchronously through the two preload spring assemblies 21.

[0083] In this embodiment, the mature land-based vacuum pipe manufacturing process can be fully referenced to assemble multiple prefabricated pipe sections 1 into a long pipeline, which can prevent environmental pollution during the construction process and effectively extend the life of the ship-borne LNG vacuum pipeline, saving a lot of evacuation time and ensuring the thermal insulation performance of the pipeline.

[0084] In actual use, refer to the instructions attached Figures 1 to 11 The specific production process of the double-wall vacuum pipeline sealing structure suitable for LNG ship high vacuum multi-layer insulation is as follows:

[0085] 1. Prefabricate pipe sections in the production workshop, refer to the instructions attached Figure 2 , fix the sealing component 11 on the left side to the inner tube 12, and install the insulation blanket, adsorbent, and insulation support on the inner tube 12 according to the production process; weld the outer tube sealing ring 111 on the left side of the outer tube 13, fit the inner tube 12 and the outer tube 13, and install the clamping bolt 116 to ensure the sealing of the sealing surface; weld the outer tube sealing ring 111 on the right side of the outer tube 13, install the sealing component 11 on the right side to ensure that the sealing compensation bellows 117 is in a reasonable telescopic position and fix the sealing component 11 on the right side; perform vacuum treatment such as heating, replacement, and evacuation through the evacuation port 1111.

[0086] 2. Assemble the pipe sections on site, set the preload spring assembly 21 on the corresponding butt joint sides of the two prefabricated pipe sections 1, butt weld the inner pipe 12 and perform the corresponding inspection and treatment; fix the tension ring 114 and the spring rod 213 with the main limit nut 211 and the tension bolt 212, install the sandwich conduction operation assembly 22, and assemble the split outer pipe 231 and the assembly pipe evacuation port 232 of the outer pipe assembly 23 according to the position of the evacuation plug 221 of the assembly pipe; install the standard evacuation valve, and The pipe evacuation port 232 opens the assembly pipe evacuation plug 221 to heat, replace and evacuate the interlayer of the assembly pipe section 2. After the evacuation is completed, the assembly pipe evacuation plug 221 is closed again; the pressing tool 235 is installed, and the assembly pipe evacuation plug 221 is pressed down to drive the crank slider unit to rotate the spring limit plate 219, and the second anti-loosening screw 2115 and the spring rod 213 are ejected in sequence into the pre-opened hole of the spring limit plate 219, and at the same time drive the interlayer sealing ring 112 and the elongated sealing compensation bellows 117 , the interlayer seals on both sides are connected, and the locking device 229 is pressed down to the lower limit to lock the locking rod 227; the assembly pipe evacuation plug 221 is lifted up to make the sliding rod 223 disengage from the assembly pipe evacuation plug 221; the heat conducting rod 233 is installed on the assembly pipe evacuation plug 221, and the welding protection cap 234 is installed on the assembly pipe evacuation port 232. The welding protection cap 234 is installed on the assembly pipe evacuation port 232 for cooling protection, and the assembly pipe evacuation port 232 and the welding protection cap 234 are welded; butt welding The top of the protective cap 234 is heated to destroy the evacuation plug sealing ring 222 through high temperature, and the interlayer between the welding protective cap 234 and the evacuation port 232 of the assembly pipe is connected with the interlayer between the inner and outer pipes; to prevent the interlayer gas from leaking into the interlayer of the inner and outer pipes and destroying the vacuum when the evacuation plug sealing ring 222 fails; to start the large vacuum pump group to evacuate the entire interlayer and continue to evacuate the penetrated interlayer; the subsequent on-site assembly of the prefabricated pipe section 1 is carried out according to the above steps, and the previously connected pipeline is connected to continue evacuation.

[0087] Since most of the pipe sections in the pipeline have been evacuated, the assembled pipe sections 2 at each site are short and can be evacuated independently before being connected to the inner and outer pipe interlayers for evacuation. During the construction process of pipe section docking, evacuation can be carried out in parallel. After the basic pipe section docking construction is completed, a short evacuation can achieve excellent vacuum performance, which can significantly improve work efficiency.

[0088] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0089] It should be noted that the above embodiments can be freely combined as needed. The above are only preferred embodiments of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A double-wall vacuum pipeline sealing structure suitable for high vacuum multi-layer insulation of LNG ships, characterized in that: Including prefabricated pipe sections and assembled pipe sections; The prefabricated pipe section has an interlayer, and the interlayer is provided with a sealing component for sealing the interlayer, and a first vacuuming component for vacuuming the interlayer; The assembly pipe section includes a pre-tensioning spring component, a sandwich conduction operating component and an outer tube component. The outer tube component is sleeved on the end of the inner tube. The pre-tensioning spring component is arranged on the inner side of the outer tube component and is connected to the sealing component. The sandwich conduction operating component passes through the outer tube component and is connected to the pre-tensioning spring component. The sandwich conduction operating component can drive the sealing component to move through the pre-tensioning spring component to control the conduction and sealing between the outer tube and the inner tube. The outer tube component is provided with a second vacuuming component for vacuuming the assembled prefabricated pipe section and the assembly pipe section.

2. The double-wall vacuum pipeline sealing structure suitable for LNG ship high vacuum multi-layer insulation according to claim 1 is characterized in that: The prefabricated pipe section includes an inner pipe, an outer pipe and at least one sealing assembly. The inner pipe is inserted into the outer pipe, and both ends extend out of the outer pipe by a preset length. The interlayer is formed between the outer pipe and the inner pipe. The outer pipe is sealed and connected to the inner pipe through the sealing assembly.

3. The double-wall vacuum pipeline sealing structure suitable for LNG ship high vacuum multi-layer insulation according to claim 2 is characterized in that: The sealing assembly comprises an outer tube sealing ring, a sandwich sealing ring, a rubber sealing ring, a tension ring, a fixing ring, a clamping bolt, a sealing compensation bellows, a spacer block group and a spacer ring; The outer tube sealing ring is fixed to the inner wall of the outer tube, the rubber sealing ring is fixed to the outer wall of the sealing compensation bellows, the sandwich sealing ring is fixed to the rubber sealing ring, the sandwich sealing ring, the rubber sealing ring and the sealing compensation bellows form a sandwich sealing body, one end of the sandwich sealing body is fixed to the outer wall of the inner tube, and the other end of the sandwich sealing body realizes the sealing of the inner and outer tube sandwich space through the radial direction and end surface of the rubber sealing ring and the outer tube sealing ring; The fixing ring is fixed on the inner tube, and the clamping bolt passes through the fixing ring and is threadedly connected with the outer tube sealing ring, so that the clamping bolt can clamp the sealing surface between the outer tube sealing ring and the sandwich sealing ring; The spacer block group is installed on the inner wall of the sealing compensation bellows through the spacer ring, and the tension ring is arranged on the sandwich sealing ring. The sandwich sealing ring can be moved by pulling the tension ring outward to conduct the sandwich spaces on both sides.

4. The double-wall vacuum pipeline sealing structure suitable for LNG ship high vacuum multi-layer insulation according to claim 3 is characterized in that: The spacer block group includes a plurality of polytetrafluoroethylene spacers arranged at intervals, and the polytetrafluoroethylene spacers are used to reduce the heat leakage of the sandwich seal to the outer tube and reduce the operating friction resistance when the sandwich is turned on; The rubber sealing ring is coated with a first thermal insulation blanket, and the first thermal insulation blanket is used to reduce radiation heat leakage between the inner tube and the outer tube; The first vacuum pumping assembly comprises a vacuum port and a vacuum plug, wherein the vacuum port is arranged at the connection between the outer tube and the inner tube and communicates with the interlayer between the outer tube and the inner tube, and the vacuum plug is detachably connected to the vacuum port; A reducing pipe joint is fixed to the end of the outer pipe, the outer diameter of the reducing pipe joint is greater than the outer diameter of the outer pipe, and the reducing pipe joint is used to increase the gap between the inner pipe and the outer pipe.

5. The double-wall vacuum pipeline sealing structure suitable for high vacuum multi-layer insulation of LNG ships according to any one of claims 1 to 4, characterized in that: The preload spring assembly comprises a main spring component, an anti-loosening component, a spring seat, a spring limiting disk and a limiting nut; The spring seat is fixed on the inner tube, the main spring component, the anti-loosening component, the spring limiting disk and the limiting nut are arranged on the spring seat, one end of the main spring component is connected to the tension ring of the prefabricated pipe section, the other end of the main spring component limits the restoring force of the spring preload through the spring limiting disk and the limiting nut, one end of the anti-loosening component presses the sandwich sealing ring of the sealing assembly, and the other end of the anti-loosening component presses the spring limiting disk; The spring limiting disk is provided with a first through hole and a second through hole. When the spring limiting disk is rotated by a preset angle, one end of the main spring component away from the sealing assembly can extend from the first through hole, and one end of the anti-loosening component away from the sealing assembly can extend from the second through hole, thereby driving the interlayer sealing ring of the sealing assembly to detach from the sealing surface and connect the interlayers on both sides.

6. The double-wall vacuum pipeline sealing structure suitable for LNG ship high vacuum multi-layer insulation according to claim 5 is characterized in that: The main spring component comprises a main limit nut, a tension bolt, a spring rod, a spring washer, a main coil spring, a main butterfly spring and an adjusting nut. The main butterfly spring is sleeved on the spring rod, and the main coil spring is sleeved on the main butterfly spring. One end of the spring rod passes through one end of the spring seat and is connected with the tension bolt. One end of the tension bolt away from the spring seat passes through the tension ring of the prefabricated pipe section and is connected with the main limit nut. The other end of the spring rod passes through the spring washer, the main coil spring, the main butterfly spring and the adjusting nut in sequence. The anti-loosening component comprises a first anti-loosening screw, an anti-loosening nut, a small butterfly spring, a small butterfly spring seat and a second anti-loosening screw, wherein the small butterfly spring is inserted in the small butterfly spring seat, the first anti-loosening screw passes through one end of the spring seat, the anti-loosening nut, the small butterfly spring, the small butterfly spring seat and is connected with the second anti-loosening screw in sequence, and an end of the second anti-loosening screw away from the first anti-loosening screw is pressed against the other end of the spring seat; When the spring limiting disk rotates to a preset angle, the spring rod can extend from the first through hole, and the second anti-loosening screw can extend from the second through hole, thereby driving the interlayer sealing ring of the sealing assembly to separate from the sealing surface and connect the interlayers on both sides.

7. The double-wall vacuum pipeline sealing structure suitable for high vacuum multi-layer insulation of LNG ships according to claim 6 is characterized in that: The main spring components are provided in plurality, and the plurality of main spring components are arranged at intervals along the circumference of the spring seat; The anti-loosening components are provided in plurality, and the plurality of anti-loosening components are arranged at intervals along the circumference of the spring seat and are arranged in a staggered manner with the main spring components; A plurality of the first through holes and the second through holes are provided, and when the spring limiting plate rotates by a preset angle, each of the spring rods can extend from the corresponding first through hole, and each of the second anti-loosening screws can extend from the corresponding second through hole; The outer side of the preload spring assembly is covered with a second thermal insulation blanket, and the second thermal insulation blanket is used to reduce radiation heat leakage between the inner tube and the outer tube.

8. The double-wall vacuum pipeline sealing structure suitable for high vacuum multi-layer insulation of LNG ships according to claim 5 is characterized in that: The interlayer conduction operation assembly includes an assembly pipe evacuation plug, an evacuation plug sealing ring, a sliding rod, a positioning pin shaft, a connecting rod, a rotating rod, a locking rod, a supporting spring and a locking device, and the second vacuuming assembly includes an assembly pipe evacuation port; The evacuation plug sealing ring is installed on the evacuation plug of the assembly tube, and the evacuation plug of the assembly tube is installed on the evacuation port of the assembly tube; the sliding rod is arranged on the lower side of the evacuation plug of the assembly tube, the sliding rod is connected with the connecting rod through the positioning pin shaft, the connecting rod is rotatably connected with the rotating rod, and the rotating rod is connected with the spring limiting disk, the sliding rod, the positioning pin shaft, the connecting rod, the rotating rod and the spring limiting disk form a set of crank slider components, when the evacuation plug of the assembly tube is pressed down, the crank slider component is driven to drive the spring limiting disk to rotate, and when the evacuation plug of the assembly tube is lifted up, the evacuation plug of the assembly tube moves up and disengages from the sliding rod; The locking rod is fixed on the sliding rod, and the supporting spring is sleeved on the locking rod, so as to enable the assembly tube evacuation plug to contact the locking rod in the initial installation state. The locking device is fixed on the outer wall of the inner tube. When the assembly tube evacuation plug moves downward and the locking rod moves downward to the lower limit, the locking device locks the locking rod to keep the sliding rod stationary.

9. The double-wall vacuum pipeline sealing structure suitable for high vacuum multi-layer insulation of LNG ships according to claim 8 is characterized in that: The outer tube assembly includes a split outer tube, a heat-conducting rod, a welding protection cap and a pressing tool. The two ends of the split outer tube are respectively connected to the inner tubes on both sides. The evacuation port of the assembly tube is arranged on one side of the split outer tube. The welding protection cap is welded and sealed to the evacuation port of the assembly tube. The heat-conducting rod is arranged on the welding protection cap. The pressing tool is threadedly connected to the outer side of the evacuation port of the assembly tube.

10. The double-wall vacuum pipeline sealing structure suitable for LNG ship high vacuum multi-layer insulation according to claim 1 is characterized in that: At least two prefabricated pipe sections are provided, and every two prefabricated pipe sections are connected by the assembly pipe section; The assembled pipe section includes two pre-tensioning spring assemblies, one of which is connected to the sealing assembly of one prefabricated pipe section, and the other pre-tensioning spring assembly is connected to the sealing assembly of another prefabricated pipe section. The two pre-tensioning spring assemblies are respectively connected to the interlayer conduction operating assemblies, so that the interlayer conduction operating assembly can drive the two sealing assemblies to move synchronously through the two pre-tensioning spring assemblies.

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