Marine LNG vacuum insulated pipeline and construction process

Abstract

The application belongs to the field of vacuum heat insulation pipelines, and discloses a marine LNG vacuum heat insulation pipeline and a construction process. The marine LNG vacuum heat insulation pipeline comprises a workshop prefabricated pipe section, a field fabricated pipe section and a driving assembly. The workshop prefabricated pipe section comprises a pipeline main body and two sealing assemblies. The sealing assembly comprises a sealing element, and the sealing element is fixedly connected with a prefabricated inner pipe. The field fabricated pipe section comprises a field fabricated outer pipe, a field fabricated inner pipe and the driving assembly. The driving assembly drives the sealing element to extend or retract along the axial direction of the prefabricated inner pipe. When the workshop prefabricated pipe section and the field fabricated pipe section are not spliced, the sealing element is in sealing connection with the inner wall of the prefabricated outer pipe, and a vacuum interlayer is formed by evacuating the space between the prefabricated outer pipe and the prefabricated inner pipe. After the workshop prefabricated pipe section and the field fabricated pipe section are spliced, the driving assembly drives the sealing element to release the sealing with the prefabricated outer pipe, and the independent interlayer is in communication with the vacuum interlayer. The application can be applied to the construction of the long pipeline shared interlayer evacuation of the marine LNG vacuum heat insulation pipeline, effectively improves the vacuum service life of the pipeline, and solves the problem of short vacuum service life of the existing process.

Description

Technical Field

[0001] This invention relates to the field of vacuum insulated pipeline technology, and more particularly to a marine LNG vacuum insulated pipeline and its construction process. Background Technology

[0002] Energy conservation, low carbon emissions, and environmental protection have become the future direction of the global shipping industry. Liquefied natural gas (LNG), as an emerging marine fuel, is increasingly attracting attention and favor from the shipping industry. Currently, LNG-powered ships have achieved success in more and more regions of China, and the pace of promotion is accelerating. Because LNG is a cryogenic medium (the temperature of LNG in China is between 140℃ and 162℃), it is easily vaporized when heated and is flammable and explosive. Therefore, LNG-powered ships need to be equipped with vacuum-insulated pipelines for the transmission and transfer of LNG. This can effectively reduce heat leakage during transmission to maintain the liquefied state of LNG and avoid vaporization causing overpressure and subsequent serious accidents. However, currently, domestic LNG marine vacuum pipelines generally have a short vacuum life, often failing after about 3 months due to vacuum failure, resulting in poor pipeline insulation performance. This is significantly different from the more than 3 years of vacuum life of land-based vacuum pipelines. The reason for this lies in the special requirements of marine LNG vacuum pipelines and the significant differences in construction processes between marine and land-based LNG vacuum pipelines, leading to a gap in insulation performance.

[0003] (1) Insulation method

[0004] Currently, marine LNG vacuum pipelines use high-vacuum insulation for heat preservation, while land-based vacuum pipelines mostly use high-vacuum multi-layer insulation. Compared to the former, high-vacuum multi-layer insulation is also known as "super insulation" due to its superior insulation performance and long service life. High-vacuum insulation requires the pipeline interlayer to maintain a high degree of vacuum to reduce residual gas heat conduction. It also demands high smoothness and low emissivity from the materials and walls to reduce radiative heat leakage. Furthermore, it requires treatment to prevent material venting under high vacuum, placing very high demands on manufacturing processes.

[0005] (2) Production method and production environment

[0006] Land-based vacuum pipelines typically consist of independent vacuum tubes no longer than 6 meters, spliced ​​together to form long pipelines. The short pipe sections allow for fabrication in a clean, dust-free environment, effectively preventing contamination from moisture, grease, dust, and other pollutants that could affect vacuum levels. The use of independent vacuum tube sections in land-based pipelines allows for a highly efficient evacuation process, facilitating operation. Pipeline cleaning, degreasing, material venting, and insulation material covering in a clean environment are all highly beneficial for achieving high vacuum and maintaining a long vacuum lifespan, fully meeting the fabrication requirements for vacuum pipelines. In contrast, existing marine vacuum pipelines are spliced ​​on-site to form long pipelines. During accidents, these pipelines are susceptible to environmental factors such as grinding, painting, oil stains, high humidity, and operational errors at the ship's construction site. Furthermore, current processes cannot completely isolate the construction process from the environment, making it difficult to achieve the necessary environment for high vacuum levels due to moisture and oil contamination.

[0007] (3) Vacuuming method and evacuation cycle

[0008] Land-based vacuum pipelines are short and can be heated and evacuated in a furnace. Due to their small pipe sections and low interlayer volume, the short length results in low flow resistance, allowing high vacuum to be achieved quickly (generally around one week), ensuring a vacuum life of over two years. However, due to the special safety requirements of marine LNG vacuum pipelines, very long vacuum interlayer spaces (generally tens or even hundreds of meters) must be constructed on-site. Evacuation is performed on-site using pumps, but the limited pump capacity and significantly increased flow resistance of long pipelines necessitate the use of large vacuum pump sets. This significantly increases the evacuation cycle, which, even with large pump sets, typically exceeds 30 days. Furthermore, environmental constraints and pollution during manufacturing, coupled with insufficient material degassing during evacuation, mean that the actual vacuum life cannot be maintained long-term within the limited construction period, resulting in time-consuming and inefficient operations. Summary of the Invention

[0009] The purpose of this invention is to provide a marine LNG vacuum insulated pipeline and its construction process, which can improve the vacuum life of the pipeline.

[0010] The technical solution provided by this invention is as follows:

[0011] On the one hand, a marine LNG vacuum insulated pipeline is provided, comprising:

[0012] The prefabricated pipe section in the workshop includes a pipe body and two sealing components. Each of the two ends of the pipe body is provided with a sealing component. The pipe body includes a prefabricated outer pipe and a prefabricated inner pipe disposed inside the prefabricated outer pipe. The sealing component includes a sealing element. One end of the sealing element is fixedly connected to the outer wall of the prefabricated inner pipe. The sealing element is axially expandable along the prefabricated inner pipe.

[0013] The on-site fabricated pipe section includes an on-site fabricated outer pipe that connects to the prefabricated outer pipe, an on-site fabricated inner pipe that connects to the prefabricated inner pipe, and a drive assembly. An independent interlayer is formed between the on-site fabricated inner pipe and the on-site fabricated outer pipe. The drive assembly is disposed in the independent interlayer and one end is connected to the sealing element, and is used to drive the sealing element to extend and retract along the axial direction of the prefabricated inner pipe.

[0014] When the prefabricated pipe section in the workshop and the pipe section made on site are not spliced, the other end of the sealing element is sealed to the inner wall of the prefabricated outer pipe, and a vacuum interlayer is formed between the prefabricated outer pipe and the prefabricated inner pipe.

[0015] After the prefabricated pipe section in the workshop is spliced ​​with the pipe section made on site, the driving component drives the sealing element to retract, and the sealing element releases the seal with the prefabricated outer pipe, so that the independent interlayer is connected with the vacuum interlayer.

[0016] In some embodiments, the inner wall of the prefabricated outer tube is provided with a radial protrusion, and a sealing ring is provided on the side of the protrusion near the sealing element;

[0017] The sealing element includes a telescopic bellows and a sealing sleeve. One end of the telescopic bellows is fixedly connected to the outer wall of the prefabricated inner tube, and the other end is sealed to one end of the sealing sleeve. The other end of the sealing sleeve is sealed to the protrusion.

[0018] In some embodiments, the sealing assembly further includes a retaining ring, a locking rod, and a steel ball locking sleeve. The retaining ring is fixedly connected to the outer wall of the prefabricated inner tube and is disposed on the side of the sealing sleeve away from the protrusion. The outer wall of the sealing sleeve is provided with a connecting portion. One end of the locking rod is fixedly connected to the connecting portion, and the other end is movably disposed on the retaining ring along the axial direction of the prefabricated inner tube. The steel ball locking sleeve is fixedly disposed on the end of the retaining ring away from the sealing sleeve. When the locking rod moves into the steel ball locking sleeve, the steel ball locking sleeve fixes the locking rod.

[0019] In some embodiments, the sealing assembly further includes a locking bolt, one end of which is connected to the connecting portion and the other end of which is threaded to the retaining ring.

[0020] In some embodiments, the sealing assembly further includes an elastic element that is fitted onto the locking rod and has one end abutting against the retaining ring and the other end abutting against the connecting portion.

[0021] In some embodiments, the sealing assembly further includes a plurality of sliders, which are circumferentially spaced along the inner side of the connection between the telescopic bellows and the sealing sleeve.

[0022] In some embodiments, the slider is made of polytetrafluoroethylene.

[0023] In some embodiments, a first sealing plug is also included;

[0024] The sealing sleeve is provided with a first evacuation port, and the first sealing plug is disposed at the first evacuation port.

[0025] In some embodiments, the drive assembly includes a sealing seat, a second sealing plug, a rack, a gear, a pivot seat, a winch, and a wire rope. The side wall of the field-fabricated outer tube has a through hole. The sealing seat is hollow inside and is sealed within the through hole, with its interior communicating with the through hole to form a second evacuation port. The second sealing plug is movably disposed radially within the second evacuation port. One end of the rack is connected to the second sealing plug, and the other end meshes with the gear. The pivot seat is disposed on the outer wall of the field-fabricated inner tube. The gear is rotatably disposed on the pivot seat. The winch is fixedly connected to the gear. The first end of the wire rope is connected to the winch, and the last end is connected to the sealing element.

[0026] When the second sealing plug moves toward the center of the on-site fabricated inner tube, the rack drives the gear and the winch to rotate. The rotation of the winch causes the wire rope to wind around the winch, and the wire rope winds around the winch, driving the sealing element to retract.

[0027] In some embodiments, the drive assembly further includes an adjusting nut, the end of the wire rope is provided with a threaded section, the adjusting nut is disposed on the threaded section, the wire rope passes through the fixing ring on the outer wall of the precast inner tube and the connecting portion on the outer wall of the seal, and the adjusting nut abuts against the connecting portion.

[0028] In some embodiments, the field-made pipe section further includes a sealing adjustment cap, the outer wall of the sealing seat is threaded, the sealing adjustment cap is fitted over the sealing seat and threadedly connected to the sealing seat, and the second sealing plug abuts against the top of the sealing adjustment cap.

[0029] In some embodiments, the drive assembly includes a sealing seat, a second sealing plug, a rack, a gear, a first connecting rod, and a second connecting rod. A through hole is provided on the side wall of the field-made outer tube. The sealing seat is hollow inside and is sealed within the through hole, with its interior communicating with the through hole to form a second evacuation port. The second sealing plug is movably disposed radially within the second evacuation port along the field-made outer tube. One end of the rack is connected to the second sealing plug, and the other end meshes with the gear. One end of the first connecting rod is fixedly connected to the gear, and the other end is pivotally connected to one end of the second connecting rod. The other end of the second connecting rod is pivotally connected to the sealing element.

[0030] In some embodiments, the pipeline body further includes an insulating support, a low-temperature adsorption layer, a multi-layer insulating layer, and a room-temperature adsorption layer disposed between the prefabricated outer pipe and the prefabricated inner pipe. One end of the insulating support is connected to the outer wall of the prefabricated inner pipe, and the other end is connected to the inner wall of the prefabricated outer pipe. The low-temperature adsorption layer, the multi-layer insulating layer, and the room-temperature adsorption layer are arranged sequentially from the inside to the outside along the radial direction of the prefabricated outer pipe.

[0031] On the other hand, a construction process for a marine LNG vacuum insulated pipeline as described in any of the above embodiments is also provided, including:

[0032] Prefabricate pipe sections in the prefabrication workshop and maintain the seal of the vacuum interlayer;

[0033] The on-site fabricated pipe section has a split outer pipe structure.

[0034] The on-site fabricated pipe section is installed between the two prefabricated pipe sections in the workshop, and the inner pipe of the prefabricated pipe section in the workshop is butt-welded to the inner pipe of the on-site fabricated pipe section.

[0035] Connect the drive assembly to the seal;

[0036] The outer pipe of the prefabricated pipe section in the workshop is welded to the outer pipe of the on-site manufactured pipe section, forming three isolated sealed spaces: two vacuum interlayers and one independent interlayer between the two prefabricated pipe sections in the workshop and one on-site manufactured pipe section.

[0037] After evacuating the independent interlayer, the independent interlayer is then sealed.

[0038] The seal is retracted by the drive assembly, so that the independent interlayer is connected to the two vacuum interlayers;

[0039] The connected independent interlayer and the two vacuum interlayers are evacuated using a vacuum pump.

[0040] The technical advantages of this invention are as follows: In the prefabricated inner and outer pipe sections of the workshop-prefabricated pipe segment, a sealed space is formed between the prefabricated inner pipe and the prefabricated outer pipe by a sealing component. This sealed space forms a vacuum interlayer after being evacuated in the workshop. In the on-site fabricated pipe segment, an independent interlayer is formed between the on-site fabricated outer pipe and the on-site fabricated inner pipe. After the workshop-prefabricated and on-site fabricated pipe sections are spliced, the independent interlayer can be evacuated first, then sealed, and then the sealing element is driven to retract by a drive component, making the independent interlayer and the vacuum interlayer conductive. The drive component is located within the independent interlayer, and the conductive operation between the independent interlayer and the vacuum interlayer is performed in a sealed environment, preventing environmental pollution and enabling the overall pipeline to achieve a higher vacuum degree and maintain a longer vacuum life, ensuring the insulation performance of the marine LNG vacuum insulation pipeline. Attached Figure Description

[0041] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0042] Figure 1 This is a schematic diagram of the prefabricated pipe section of a marine LNG vacuum insulated pipeline provided in a specific embodiment of this application;

[0043] Figure 2 yes Figure 1 Enlarged view of point A in the middle;

[0044] Figure 3 This is a schematic diagram of the structure provided in a specific embodiment of this application when the vacuum interlayer and the independent interlayer are not connected;

[0045] Figure 4 yes Figure 3 Enlarged view of point B in the middle;

[0046] Figure 5 This is a schematic diagram of the longitudinal section of a field-fabricated section of a marine LNG vacuum insulated pipeline provided in a specific embodiment of this application;

[0047] Figure 6 This is a cross-sectional schematic diagram of a field-fabricated section of a marine LNG vacuum insulated pipeline provided in a specific embodiment of this application;

[0048] Figure 7 This is a diagram of the pipeline structure after on-site assembly of the marine LNG vacuum insulated pipeline provided in a specific embodiment of this application.

[0049] Explanation of icon numbers:

[0050] 10. Prefabricated pipe section in workshop; 11. Prefabricated outer pipe; 111. Protrusion; 12. Prefabricated inner pipe; 131. Sealing element; 1311. Telescopic corrugated pipe; 1312. Sealing sleeve; 1313. Connecting part; 1314. First evacuation port; 132. Fixing ring; 133. Locking rod; 134. Steel ball locking sleeve; 135. Locking bolt; 136. Elastic element; 137. Sliding block; 14. Vacuum interlayer; 15. Thermal insulation support; 16. 17. Low-temperature adsorption layer; 18. Multi-layer insulation layer; 29. ​​Room temperature adsorption layer; 20. On-site fabricated pipe section; 21. On-site fabricated outer pipe; 22. On-site fabricated inner pipe; 23. Drive assembly; 231. Sealing seat; 232. Second sealing plug; 233. Rack; 234. Gear; 235. Pivot seat; 236. Winch; 237. Wire rope; 2371. Threaded section; 238. Adjusting nut; 239. Sealing adjustment cap; 24. Independent interlayer. Detailed Implementation

[0051] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0052] To keep the drawings concise, only the parts relevant to the invention are shown schematically in each figure, and they do not represent the actual structure of the product. Furthermore, for ease of understanding, in some figures, only one of components with the same structure or function is shown schematically, or only one is labeled. In this document, "one" can mean not only "only one" but also "more than one".

[0053] It should also be further understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0054] In this document, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0055] Furthermore, in the description of this application, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0056] In one embodiment of this application, such as Figures 1 to 4 As shown, a marine LNG vacuum insulated pipeline includes a prefabricated pipe section 10 in a workshop and a pipe section 20 fabricated on-site. The prefabricated pipe section 10 includes a pipeline body and two sealing components. Each end of the pipeline body is provided with a sealing component. The pipeline body includes a prefabricated outer pipe 11 and a prefabricated inner pipe 12 disposed inside the prefabricated outer pipe 11. The sealing component includes a sealing element 131. One end of the sealing element 131 is fixedly connected to the outer wall of the prefabricated inner pipe 12. The sealing element 131 is axially expandable and contractible along the prefabricated inner pipe 12.

[0057] The on-site fabricated pipe section 20 includes an on-site fabricated outer pipe 21 that connects to the prefabricated outer pipe 11, an on-site fabricated inner pipe 22 that connects to the prefabricated inner pipe 12, and a drive assembly 23. An independent interlayer 24 is formed between the on-site fabricated outer pipe 21 and the on-site fabricated inner pipe 22. The drive assembly 23 is disposed in the independent interlayer 24 and one end is connected to the seal 131 for driving the seal 131 to extend and retract along the axial direction of the prefabricated inner pipe 12.

[0058] When the prefabricated pipe section 10 in the workshop and the pipe section 20 on site are not spliced, the other end of the sealing element 131 is sealed to the inner wall of the prefabricated outer pipe 11, and a vacuum interlayer 14 is formed between the prefabricated outer pipe 11 and the prefabricated inner pipe 12. After the prefabricated pipe section 10 in the workshop and the pipe section 20 on site are spliced, the drive component 23 drives the sealing element 131 to retract, and the sealing element 131 releases the seal with the prefabricated outer pipe 11, so that the independent interlayer 24 is connected to the vacuum interlayer 14.

[0059] Specifically, prefabricated pipe section 10 is prefabricated in the workshop, while on-site fabricated pipe section 20 is fabricated on-site. The prefabricated pipe section 10 and the on-site fabricated pipe section 20 are then spliced ​​together on-site to form a long pipeline, which is then evacuated. The prefabricated pipe section 10 is manufactured in a clean, dust-free, and dry environment according to the manufacturing process for land-based vacuum pipelines, ensuring its long vacuum life. The on-site fabricated pipe section 20 undergoes material preparation, cleaning, and degreasing in the workshop, followed by on-site welding. When splicing the prefabricated pipe section 10 and the on-site fabricated pipe section 20, the prefabricated pipe section 10 at the beginning and end, or the on-site fabricated pipe section 20, uses pipe caps to directly seal the inner and outer pipes. Figure 7 As shown, the left end of the prefabricated pipe section 10 at the beginning is sealed with a pipe cap instead of a sealing component, and the right end of the prefabricated pipe section 10 at the end is sealed with a pipe cap instead of a sealing component. Similarly, when the on-site fabricated pipe section 20 is at the beginning, the left end of the on-site fabricated pipe section 20 is sealed with a pipe cap, and when the on-site fabricated pipe section 20 is at the end, the right end of the on-site fabricated pipe section 20 is sealed with a pipe cap.

[0060] A sealed space is formed between the prefabricated inner pipe 12 and the prefabricated outer pipe 11 of the prefabricated pipe section 10 in the workshop by a sealing assembly. This sealed space forms a vacuum interlayer 14 after being evacuated in the workshop. An independent interlayer 24 is formed between the on-site fabricated outer pipe 21 and the on-site fabricated inner pipe 22 of the on-site fabricated pipe section 20. After the prefabricated pipe section 10 in the workshop and the on-site fabricated pipe section 20 are spliced, the independent interlayer 24 can be evacuated first, then sealed, and then the sealing element 131 can be retracted by the drive assembly 23 to make the independent interlayer 24 and the vacuum interlayer 14 conductive. The drive assembly 23 is set in the independent interlayer 24. The conductive operation between the independent interlayer 24 and the vacuum interlayer 14 is carried out in a sealed environment to prevent environmental pollution, so that the overall pipeline can achieve a higher vacuum degree and maintain a longer vacuum life, ensuring the thermal insulation performance of the marine LNG vacuum insulation pipeline.

[0061] The main body of the pipeline also includes an insulating support 15, a low-temperature adsorption layer 16, a multi-layer insulation layer 17, and a room-temperature adsorption layer 18, all disposed between the prefabricated outer pipe 11 and the prefabricated inner pipe 12. One end of the insulating support 15 is connected to the outer wall of the prefabricated inner pipe 12, and the other end is connected to the inner wall of the prefabricated outer pipe 11. The low-temperature adsorption layer 16, the multi-layer insulation layer 17, and the room-temperature adsorption layer 18 are arranged sequentially from the inside to the outside along the radial direction of the prefabricated outer pipe 11. By setting the low-temperature adsorption layer 16, the multi-layer insulation layer 17, and the room-temperature adsorption layer 18, the adsorption capacity of the material for gas release can be significantly improved, and radiative heat leakage can be reduced. Under the condition of ensuring that both ends are sealed, a vacuum life and thermal insulation performance of more than 2 years can be easily maintained.

[0062] Furthermore, the inner wall of the prefabricated outer tube 11 is provided with a protrusion 111 in the radial direction, and a sealing ring is provided on the side of the protrusion 111 near the sealing element 131; the sealing element 131 includes a telescopic bellows 1311 and a sealing sleeve 1312, one end of the telescopic bellows 1311 is fixedly connected to the outer wall of the prefabricated inner tube 12, and the other end is sealed to one end of the sealing sleeve 1312, and the other end of the sealing sleeve 1312 is sealed to the protrusion 111.

[0063] Sealing components are installed at both ends of the prefabricated pipe section 10 in the workshop. By sealing both ends of the prefabricated pipe section 10 with the sealing components, a vacuum interlayer 14 can be formed after the prefabricated outer pipe 11 and the prefabricated inner pipe 12 of the prefabricated pipe section 10 are evacuated. The sealing element 131 includes a telescopic bellows 1311 and a sealing sleeve 1312. The telescopic bellows 1311 is telescopic to realize the expansion and contraction of the sealing element 131. When the telescopic bellows 1311 is kept in an extended state under atmospheric pressure and / or external force, the sealing sleeve 1312 can maintain a sealed connection with the protrusion 111 of the prefabricated outer pipe 11. When the telescopic bellows 1311 is retracted under the action of the driving component 23, it drives the sealing sleeve 1312 away from the protrusion 111 of the prefabricated outer pipe 11, releasing the sealed connection between the sealing sleeve 1312 and the protrusion 111. As a variation, the sealing element 131 can also be composed entirely of the telescopic bellows 1311.

[0064] Furthermore, such as Figure 2 As shown, the sealing assembly also includes a retaining ring 132, a locking rod 133, and a steel ball locking sleeve 134. The retaining ring 132 is fixedly connected to the outer wall of the prefabricated inner tube 12 and is disposed on the side of the sealing sleeve 1312 away from the protrusion 111. The outer wall of the sealing sleeve 1312 is provided with a connecting part 1313. One end of the locking rod 133 is fixedly connected to the connecting part 1313, and the other end is movably disposed on the retaining ring 132 along the axial direction of the prefabricated inner tube 12. The steel ball locking sleeve 134 is fixedly disposed on the end of the retaining ring 132 away from the sealing sleeve 1312. When the locking rod 133 moves into the steel ball locking sleeve 134, the steel ball locking sleeve 134 fixes the locking rod 133.

[0065] The fixing ring 132 is welded to the prefabricated inner tube 12 for fixation, and the steel ball locking sleeve 134 is welded to the fixing ring 132. The fixing ring 132, the telescopic bellows 1311, and the sealing sleeve 1312 are sequentially welded to form a sealing unit, and a seal is formed through the sealing unit, the prefabricated outer tube 11, and the prefabricated inner tube 12. The locking rod 133 is fixed to the sealing sleeve 1312 and is used in conjunction with the steel ball locking sleeve 134. When the locking rod 133 moves outward into position, the steel ball locking sleeve 134 locks with the locking rod 133. The locking rod 133 and the steel ball locking sleeve 134 are existing locking mechanisms that can maintain the gap between the sealing unit and the protrusion 111 on the prefabricated outer tube 11, and maintain the communication between the inner and outer spaces.

[0066] When the sealing sleeve 1312 retracts under the action of the drive assembly 23, it drives the connecting part 1313 to move toward the fixing ring 132. When the connecting part 1313 moves toward the fixing ring 132, it drives the locking rod 133 to move toward the steel ball locking sleeve 134, so that the locking rod 133 is fixed in the steel ball locking sleeve 134 to fix the position of the sealing element 131 and keep the vacuum interlayer 14 and the independent interlayer 24 in communication.

[0067] Furthermore, such as Figure 1 As shown, the sealing assembly also includes a locking bolt 135, one end of which is fixedly connected to the connecting part 1313, and the other end is threadedly connected to the retaining ring 132. The sealing clamping force of the sealing member 131 and the protrusion 111 can be adjusted by the locking bolt 135, which can ensure the sealing connection between the sealing member 131 and the protrusion 111. Preferably, the sealing assembly also includes an elastic member 136, which is sleeved on the locking rod 133 and abuts against the retaining ring 132 at one end and against the connecting part 1313 at the other end. After the prefabricated inner pipe 12 of the prefabricated pipe section 10 and the on-site fabricated inner pipe 22 of the on-site fabricated pipe section 20 are butt-welded, the locking bolt 135 needs to be loosened. After the locking bolt 135 is loosened, the elastic member 136 can continue to press the sealing member 131 to ensure the sealing connection between the sealing member 131 and the protrusion 111.

[0068] Preferred, such as Figure 2 As shown, the sealing assembly also includes multiple sliders 137, which are spaced circumferentially along the inner side of the connection between the telescopic bellows 1311 and the sealing sleeve 1312. The multiple sliders 137 spaced circumferentially along the connection between the telescopic bellows 1311 and the sealing sleeve 1312 can support the connection between the telescopic bellows 1311 and the sealing sleeve 1312, thereby connecting the internal space of the telescopic bellows 1311 with the internal space of the sealing sleeve 1312. This prevents the internal space of the telescopic bellows 1311 from being disconnected from the internal space of the sealing sleeve 1312, which would affect the evacuation effect. Furthermore, the sliders 137 supporting the sealing sleeve 1312 can prevent the sealing sleeve 1312 from becoming eccentric, which would lead to a deterioration in the sealing effect between the sealing sleeve 1312 and the protrusion 111. Preferably, the slider 137 is made of polytetrafluoroethylene (PTFE) to utilize its low-temperature resistance, low thermal conductivity, and friction-reducing properties to achieve center positioning of the sealing unit, reduce friction, and reduce heat leakage from the prefabricated inner tube 12.

[0069] Optionally, the sealing sleeve 1312 is provided with a first evacuation port 1314. An evacuation device can be set at the first evacuation port 1314 to evacuate the area between the prefabricated outer tube 11 and the prefabricated inner tube 12 to form a vacuum interlayer 14. After evacuation, a first sealing plug can be set at the first evacuation port 1314 for sealing. When sealing components are set at both ends of the prefabricated pipe section 10 in the workshop, the first evacuation port 1314 can be set only on the sealing component at one end, and the first evacuation port 1314 can be omitted at the other end; or the first evacuation port 1314 can be set on the sealing components at both ends to improve evacuation efficiency.

[0070] In some embodiments, such as Figure 5 and 6As shown, the drive assembly 23 includes a sealing seat 231, a second sealing plug 232, a rack 233, a gear 234, a pivot seat 235, a winch 236, and a wire rope 237. A through hole is provided on the side wall of the field-fabricated outer tube 21. The sealing seat 231 is hollow inside and is sealed within the through hole, with its interior communicating with the through hole to form a second evacuation port. The second sealing plug 232 is movably disposed radially along the field-fabricated outer tube 21 within the second evacuation port. One end of the rack 233 is connected to the second sealing plug 232, and the other end meshes with the gear 234. A pivot seat 235 is disposed on the outer wall of the on-site fabricated inner tube 22. A gear 234 is rotatably disposed on the pivot seat 235. A winch 236 is fixedly connected to the gear 234. The first end of the wire rope 237 is connected to the winch 236, and the end of the wire rope 237 is connected to the seal 131. When the second sealing plug 232 moves toward the center of the on-site fabricated inner tube 22, the rack 233 drives the gear 234 and the winch 236 to rotate. The rotation of the winch 236 causes the wire rope 237 to wind around the winch 236. When the wire rope 237 is wound around the winch 236, it drives the seal 131 to retract.

[0071] The sealing seat 231 is welded and fixed to the outer tube 21 fabricated on site. A second sealing plug 232 is installed inside the sealing seat 231 and can move up and down. A sealing ring is installed on the outer wall of the second sealing plug 232 to prevent leakage during its up-and-down movement. A rack 233 is fixed to the lower end of the second sealing plug 232. Gears 234 and winches 236 are rotatably mounted on a pivot seat 235 via a pivot. The pivot is connected to the pivot seat 235 via a PTFE bushing and a retaining ring. Gears 234 and rack 233... The meshing mechanism rotates the steel wire rope 237. One end of the steel wire rope 237 is connected to the winch 236, and the other end is connected to the sealing sleeve 1312. When the second sealing plug 232 drives the rack 233 to move downward, it drives the gear 234 and the winch 236 to rotate. The rotation of the winch 236 winds the steel wire rope 237 onto the winch 236, making the steel wire rope 237 shorter. The steel wire rope 237 can drive the sealing sleeve 1312 to retract, so that the independent interlayer 24 of the field-made pipe section 20 is connected to the vacuum interlayer 14 of the prefabricated pipe section 10 in the workshop. When it is necessary to open the sealing components at both ends of the field-made pipe section 20, two steel wire ropes 237 can be set on the winch 236. One steel wire rope 237 opens the sealing component at the left end of the field-made pipe section 20, and the other steel wire rope 237 opens the sealing component at the right end of the field-made pipe section 20. In addition, the interface dimensions of the sealing seat 231 and the second sealing plug 232 are compatible with the interface of common vacuum valves on the market, allowing for separate vacuuming.

[0072] When connecting the on-site fabricated pipe section 20, the on-site fabricated outer pipe 21 is first assembled and welded to isolate it from the environment. Then, the second sealing plug 232 is pressed downwards. The rotation of the rotating unit is achieved through the transmission of the rack 233 and gear 234, which causes the winch 236 to tighten the wire rope 237 to transmit force. Since the second sealing plug 232 remains sealed throughout the pressing process, no leakage can be guaranteed during operation.

[0073] Optionally, the drive assembly 23 also includes an adjusting nut 238. The end of the wire rope 237 has a threaded section 2371, and the adjusting nut 238 is disposed on the threaded section 2371. The wire rope 237 passes through the fixing ring 132 on the outer wall of the prefabricated inner tube 12 and the connecting part 1313 on the outer wall of the sealing sleeve 1312. The adjusting nut 238 abuts against the connecting part 1313. The wire rope 237 is fixed to the sealing assembly by the adjusting nut 238, which can also adjust the tension of the wire rope 237.

[0074] Optionally, the on-site fabricated pipe section 20 also includes a sealing adjustment cap 239. The outer wall of the sealing seat 231 is threaded. The sealing adjustment cap 239 is fitted over the sealing seat 231 and threadedly connected to it. The second sealing plug 232 abuts against the top of the sealing adjustment cap 239. When the sealing adjustment cap 239 is rotated, its downward movement causes the second sealing plug 232 to move downward. By using the sealing adjustment cap 239, the difficulty of moving the second sealing plug 232 downward is reduced, saving manpower.

[0075] In other embodiments, the drive assembly includes a sealing seat 231, a second sealing plug 232, a rack 233, a gear 234, a first connecting rod, and a second connecting rod. The side wall of the field-made outer tube 21 has a through hole. The interior of the sealing seat 231 is hollow. The sealing seat 231 is sealed in the through hole and the interior of the sealing seat 231 communicates with the through hole to form a second evacuation port. The second sealing plug 232 is movably disposed in the second evacuation port along the radial direction of the field-made outer tube 21. One end of the rack 233 is connected to the second sealing plug 232, and the other end is engaged with the gear 234. One end of the first connecting rod is fixedly connected to the gear 234, and the other end is pivotally connected to one end of the second connecting rod. The other end of the second connecting rod is pivotally connected to the seal 131.

[0076] When the second sealing plug 232 moves downward, it drives the gear 234 to move downward. The downward movement of the gear 234 causes the gear 234 to rotate. The rotation of the gear 234 causes the first connecting rod to rotate. The rotation of the first connecting rod causes the second connecting rod to rotate. When the second connecting rod rotates, it causes the sealing element 131 to move axially along the prefabricated inner tube 12. A limiting part needs to be provided on the outer wall of the prefabricated inner tube 12 along its axial direction. The sealing element 131 is provided with a mating part that cooperates with the limiting part, so that when the second connecting rod rotates, the sealing element 131 can only move axially along the prefabricated inner tube 12 to achieve expansion and contraction.

[0077] This invention also provides an embodiment of a construction process for a marine LNG vacuum insulated pipeline, comprising:

[0078] Prefabricate pipe sections in the prefabrication workshop and maintain the seal of the vacuum interlayer;

[0079] The on-site fabricated pipe section has a split outer pipe structure.

[0080] The on-site fabricated pipe section is installed between the two prefabricated pipe sections in the workshop, and the inner pipe of the prefabricated pipe section in the workshop is butt-welded to the inner pipe of the on-site fabricated pipe section.

[0081] Connect the drive assembly to the seal;

[0082] The outer pipe of the prefabricated pipe section in the workshop is welded to the outer pipe of the on-site manufactured pipe section, forming three isolated sealed spaces: two vacuum interlayers and one independent interlayer between the two prefabricated pipe sections in the workshop and one on-site manufactured pipe section.

[0083] After evacuating the independent interlayer, the independent interlayer is then sealed.

[0084] The seal is retracted by the drive assembly, so that the independent interlayer is connected to the two vacuum interlayers;

[0085] The connected independent interlayer and the two vacuum interlayers are evacuated using a vacuum pump.

[0086] Specifically, the long pipelines required for on-site installation are installed and welded sequentially from left to right, following the order of prefabricated pipe sections in the workshop and on-site fabricated pipe sections. In particular, the sealing component is removed from the left end of the first pipe section, and the inner and outer pipes are directly sealed by welding with a pipe cap. The sealing component is removed from the right end of the last pipe section, and the inner and outer pipes are directly sealed by welding with a pipe cap.

[0087] (1) First, the prefabrication of pipe sections is carried out in the workshop. The vacuum interlayer of the prefabricated pipe section is locked with locking bolts to maintain the vacuum state of the vacuum interlayer.

[0088] (2) Then, the on-site fabrication of pipe sections is carried out. The outer pipe of the on-site fabrication pipe section is processed into a split structure to facilitate on-site installation, welding and special requirements of ship inspection. The pivot seat is installed on the outside of the on-site fabrication inner pipe.

[0089] (3) Perform butt welding of the inner pipe of the prefabricated pipe section in the adjacent workshop with the inner pipe of the pipe section made on site, and conduct the corresponding inspections required by the ship.

[0090] (4) After inspection and approval, clean and install the winch, gear, rack and wire rope, so that the gear and rack are accurately meshed, the wire rope is in a slack state, and fix the two wire ropes to the sealing components on the adjacent sides respectively. Adjust the length of the wire rope by adjusting the wire rope nut to make the wire rope in a horizontal state.

[0091] (5) Remove the locking bolts. The sealing assembly will remain sealed under the action of the elastic element and atmospheric pressure. Take precautions during the operation to keep the interlayer between the inner and outer tubes clean.

[0092] (6) Welding the outer pipe to separate the inner and outer pipes of the on-site pipe section, so that the prefabricated pipe section in the workshop and the on-site pipe section form three mutually isolated sealed spaces: vacuum interlayer 1, independent interlayer and vacuum interlayer 2.

[0093] (7) Use a universal vacuum valve to open the second sealing plug and use a portable vacuum pump to replace and evacuate the independent interlayer of the pipe section fabricated on site.

[0094] (8) After evacuation, close the second sealing plug and remove the evacuation valve. Press down the second sealing plug through the sealing adjustment cap. The corresponding rack and gear drive tightens the wire rope, causing the sealing components on the left and right sides to disengage from the corresponding sealing surfaces. The adjacent interlayer spaces are connected, that is, vacuum interlayer 1, independent interlayer and vacuum interlayer 2 are connected. After the second sealing plug is pressed down into place, the locking rod of the sealing component is locked and fixed on the prefabricated inner tube by the steel ball locking sleeve, and the left and right sealing components remain reliably open.

[0095] (9) After the second sealing plug is moved into place, weld a reliable seal to the independent interlayer of the pipe section fabricated on site at the marked location on the outside of the second sealing plug. At this time, the large vacuum pump group will evacuate the conductive interlayer space. Except for the large vacuum pump maintaining the evacuation state, the rest will be connected to the right pipe section in sequence according to the above steps until the last pipe section to complete the installation and connection of the entire long pipeline. The spliced ​​marine LNG vacuum insulated pipeline is as follows: Figure 7 As shown.

[0096] (10) Vacuuming of the pipe interlayer is carried out from the pipeline evacuation port through a large evacuation pump set until the target is met.

[0097] Because the pipe sections are short and the evacuation effect is good, and the pipe sections are installed sequentially from left to right, the space of each prefabricated pipe section on site can be evacuated individually in turn. After the evacuation is completed, the corresponding left and right sealing components are opened and connected to the pipe interlayer of the previous stage. A large evacuation pump set is used to evacuate the pipes, which can significantly improve work efficiency.

[0098] The marine LNG vacuum insulated pipeline of this application has the following advantages:

[0099] (1) Long vacuum life and excellent thermal insulation performance

[0100] Because the fabrication of long pipelines is divided into prefabricated vacuum tube sections in the workshop and prefabricated sections on-site, the workshop-prefabricated vacuum tube sections account for approximately 90% of the total length. These sections are manufactured using mature land-based vacuum tube production processes, ensuring a long vacuum life and excellent insulation performance. Compared to existing production processes, both vacuum life and insulation performance are significantly improved.

[0101] (2) Fully utilize the thermal insulation properties of vacuum maintenance and insulation materials

[0102] By employing a specially designed sealing structure, the sealing performance of the on-site construction process is ensured, which can isolate the insulation blanket, low-temperature adsorbent, etc. from contact with the environment, avoid the influence of environmental moisture, oil, impurities and gases, extend the vacuum life and ensure the insulation performance.

[0103] Compared to existing production processes, the construction process cannot isolate the insulation blanket and low-temperature adsorbent from the environment, causing them to absorb water and air, resulting in difficulties in evacuation, poor vacuum achievement, long evacuation time, short vacuum life, and poor insulation effect. Therefore, existing construction processes often do not place insulation blankets and adsorbents in the pipe interlayer.

[0104] (3) Reducing on-site production workload can significantly improve work efficiency.

[0105] Since most of the entire long vacuum pipeline is prefabricated in the workshop, the amount of work on site can be greatly reduced. In terms of structural design and operation, vacuuming can be carried out step by step. The operation is convenient and can be carried out in parallel with the construction of subsequent pipeline sections, which can reduce the on-site vacuuming time and significantly improve work efficiency.

[0106] (4) Reliable structure, convenient operation, and more reasonable process

[0107] The main sealed structure is connected by welding. During construction, the seal is opened via threaded tightening and a reliable gear / rack transmission mechanism. The seal design allows for operation according to... Figure 7 As shown, vacuuming is performed step by step from left to right. This method is convenient and can be carried out in parallel with the subsequent pipe section assembly and welding construction. There is no need to wait for all pipe sections to be assembled and welded before vacuuming, making the construction process more reasonable.

[0108] (5) Vacuum life is less affected by the environment.

[0109] Marine pipeline construction environments are often characterized by high humidity, dust, paint, oil stains, and unpredictable pollution, all of which negatively impact the pipeline's vacuum performance. This invention prefabricates most of the vacuum tube sections in the workshop, ensuring that the internal vacuum performance of these sections is unaffected by the environment. The proportion of tube sections requiring on-site construction is small, and a specially designed sealing structure minimizes environmental impact during on-site construction.

[0110] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A marine LNG vacuum insulated pipeline, characterized in that, include: The prefabricated pipe section in the workshop includes a pipe body and two sealing components. Each of the two ends of the pipe body is provided with a sealing component. The pipe body includes a prefabricated outer pipe and a prefabricated inner pipe disposed inside the prefabricated outer pipe. The sealing component includes a sealing element. One end of the sealing element is fixedly connected to the outer wall of the prefabricated inner pipe. The sealing element is axially expandable along the prefabricated inner pipe. The on-site fabricated pipe section includes an on-site fabricated outer pipe that connects to the prefabricated outer pipe, an on-site fabricated inner pipe that connects to the prefabricated inner pipe, and a drive assembly. An independent interlayer is formed between the on-site fabricated inner pipe and the on-site fabricated outer pipe. The drive assembly is disposed in the independent interlayer and one end is connected to the sealing element, and is used to drive the sealing element to extend and retract along the axial direction of the prefabricated inner pipe. When the prefabricated pipe section in the workshop and the pipe section made on site are not spliced, the other end of the sealing element is sealed to the inner wall of the prefabricated outer pipe, and a vacuum interlayer is formed between the prefabricated outer pipe and the prefabricated inner pipe. After the prefabricated pipe section in the workshop is spliced ​​with the pipe section made on site, the drive component drives the sealing element to retract, and the sealing element releases the seal with the prefabricated outer pipe, so that the independent interlayer is connected with the vacuum interlayer. The inner wall of the prefabricated outer tube has a protrusion along the radial direction, and a sealing ring is provided on the side of the protrusion near the sealing element; The sealing element includes a telescopic bellows and a sealing sleeve. One end of the telescopic bellows is fixedly connected to the outer wall of the prefabricated inner tube, and the other end is sealed to one end of the sealing sleeve. The other end of the sealing sleeve is sealed to the protrusion.

2. The marine LNG vacuum insulated pipeline according to claim 1, characterized in that, The sealing assembly further includes a retaining ring, a locking rod, and a steel ball locking sleeve. The retaining ring is fixedly connected to the outer wall of the prefabricated inner tube and is located on the side of the sealing sleeve away from the protrusion. The outer wall of the sealing sleeve is provided with a connecting part. One end of the locking rod is fixedly connected to the connecting part, and the other end is movably disposed on the retaining ring along the axial direction of the prefabricated inner tube. The steel ball locking sleeve is fixedly disposed on the end of the retaining ring away from the sealing sleeve. When the locking rod moves into the steel ball locking sleeve, the steel ball locking sleeve fixes the locking rod.

3. A marine LNG vacuum insulated pipeline according to claim 2, characterized in that, The sealing assembly also includes a locking bolt, one end of which is connected to the connecting part, and the other end is threadedly connected to the retaining ring.

4. A marine LNG vacuum insulated pipeline according to claim 2, characterized in that, The sealing assembly also includes an elastic element, which is sleeved on the locking rod and has one end abutting against the fixing ring and the other end abutting against the connecting part.

5. A marine LNG vacuum insulated pipeline according to claim 2, characterized in that, The sealing assembly also includes a plurality of sliders, which are spaced circumferentially along the inner side of the connection between the telescopic bellows and the sealing sleeve.

6. A marine LNG vacuum insulated pipeline according to claim 5, characterized in that, The slider is made of polytetrafluoroethylene.

7. A marine LNG vacuum insulated pipeline according to claim 2, characterized in that, It also includes the first sealing plug; The sealing sleeve is provided with a first evacuation port, and the first sealing plug is disposed at the first evacuation port.

8. A marine LNG vacuum insulated pipeline according to any one of claims 1-7, characterized in that, The drive assembly includes a sealing seat, a second sealing plug, a rack, a gear, a pivot seat, a winch, and a wire rope. The side wall of the field-fabricated outer tube has a through hole. The sealing seat is hollow inside and is sealed within the through hole, with its interior communicating with the through hole to form a second evacuation port. The second sealing plug is movably disposed in the second evacuation port along the radial direction of the field-fabricated outer tube. One end of the rack is connected to the second sealing plug, and the other end meshes with the gear. The pivot seat is disposed on the outer wall of the field-fabricated inner tube. The gear is rotatably disposed on the pivot seat. The winch is fixedly connected to the gear. The first end of the wire rope is connected to the winch, and the last end is connected to the sealing element. When the second sealing plug moves toward the center of the on-site fabricated inner tube, the rack drives the gear and the winch to rotate. The rotation of the winch causes the wire rope to wind around the winch, and the wire rope winds around the winch, driving the sealing element to retract.

9. A marine LNG vacuum insulated pipeline according to claim 8, characterized in that, The drive assembly also includes an adjusting nut, the end of the wire rope is provided with a threaded section, the adjusting nut is disposed on the threaded section, the wire rope passes through the fixing ring on the outer wall of the precast inner tube and the connecting part on the outer wall of the seal, and the adjusting nut abuts against the connecting part.

10. A marine LNG vacuum insulated pipeline according to claim 8, characterized in that, The on-site fabricated pipe section also includes a sealing adjustment cap. The outer wall of the sealing seat is threaded. The sealing adjustment cap is fitted over the sealing seat and threadedly connected to the sealing seat. The second sealing plug abuts against the top of the sealing adjustment cap.

11. A marine LNG vacuum insulated pipeline according to any one of claims 1-7, characterized in that, The drive assembly includes a sealing seat, a second sealing plug, a rack, a gear, a first connecting rod, and a second connecting rod. A through hole is provided on the side wall of the field-made outer tube. The sealing seat is hollow inside and is sealed within the through hole, with its interior communicating with the through hole to form a second evacuation port. The second sealing plug is movably disposed in the second evacuation port along the radial direction of the field-made outer tube. One end of the rack is connected to the second sealing plug, and the other end meshes with the gear. One end of the first connecting rod is fixedly connected to the gear, and the other end is pivotally connected to one end of the second connecting rod. The other end of the second connecting rod is pivotally connected to the sealing element.

12. A marine LNG vacuum insulated pipeline according to any one of claims 1-7, characterized in that, The main body of the pipeline also includes an insulation support, a low-temperature adsorption layer, a multi-layer insulation layer and a normal-temperature adsorption layer disposed between the prefabricated outer pipe and the prefabricated inner pipe. One end of the insulation support is connected to the outer wall of the prefabricated inner pipe and the other end is connected to the inner wall of the prefabricated outer pipe. The low-temperature adsorption layer, the multi-layer insulation layer and the normal-temperature adsorption layer are arranged sequentially from the inside to the outside along the radial direction of the prefabricated outer pipe.

13. A construction process for a marine LNG vacuum insulated pipeline according to any one of claims 1-12, characterized in that, include: Prefabricate pipe sections in the prefabrication workshop and maintain the seal of the vacuum interlayer; The on-site fabricated pipe section has a split outer pipe structure. The on-site fabricated pipe section is installed between the two prefabricated pipe sections in the workshop, and the inner pipe of the prefabricated pipe section in the workshop is butt-welded to the inner pipe of the on-site fabricated pipe section. Connect the drive assembly to the seal; The outer pipe of the prefabricated pipe section in the workshop is welded to the outer pipe of the on-site manufactured pipe section, forming three isolated sealed spaces: two vacuum interlayers and one independent interlayer between the two prefabricated pipe sections in the workshop and one on-site manufactured pipe section. After evacuating the independent interlayer, the independent interlayer is then sealed. The seal is retracted by the drive assembly, so that the independent interlayer is connected to the two vacuum interlayers; The connected independent interlayer and the two vacuum interlayers are evacuated using a vacuum pump.

Images