Sleeve type LNG (Liquefied Natural Gas) conveying pipeline

The casing LNG conveying pipeline provides insulation performance through the BOG flow of the inner and outer pipe cavity, processes BOG gas, and uses thermal compensation and stress compensation mechanisms to improve thermal insulation performance and sealing, solving the problem of rapid gasification of LNG and high vacuum insulation costs, achieving efficient and low-energy LNG conveying.

CN119687291APending Publication Date: 2025-03-25YANGTZE UNIVERSITY +1
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Patent Information

Application Number
CN202510148576.0
Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Filing Date
2025-02-11
Publication Date
2025-03-25

AI Technical Summary

Technical Problem

During the bare pipe transportation process, the existing LNG conveying pipelines have rapid gasification of LNG due to differences in high and low temperature characteristics, resulting in gas resistance, affecting the conveying efficiency, and the vacuum insulation solution is costly and poor sealing.

Method used

A casing type LNG conveying pipeline is adopted, including the cavity between the outer pipe and the inner pipe, a low-temperature exhaust valve is installed to treat BOG gas, and a thermal compensation and stress compensation mechanism is used to improve the thermal insulation performance and sealing of the pipeline.

Benefits of technology

The BOG flow through the inner and outer pipe cavity provides insulation performance, reduces LNG gasification losses, improves conveying efficiency, reduces energy losses, and improves the thermal insulation performance and sealing of the pipeline through compensation mechanisms.

✦ Generated by Eureka AI based on patent content.

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Abstract

The invention provides a sleeve type LNG (Liquefied Natural Gas) conveying pipeline. The sleeve type LNG conveying pipeline comprises a conveying pipe, a thermal compensation mechanism and a stress compensation mechanism, the conveying pipe is composed of an outer pipe body and an inner pipe body, a cavity is formed between the outer pipe body and the inner pipe body, flange plates are installed at the two ends of the conveying pipe body respectively, a first filler cavity and a second filler cavity are formed in the two sides of the conveying pipe body respectively, supporting rings are distributed on the outer side of the inner pipe body in a sleeving mode at equal intervals, and a low-temperature exhaust valve is installed on the outer surface of the inner pipe body. A damp-proof layer and a heat preservation layer are arranged in the outer pipe. The thermal compensation mechanism is arranged on the outer side of the conveying pipe in a sleeving manner; the inner pipe is arranged for LNG transportation, the low-temperature exhaust valve is arranged on the inner pipe, gasified BOG can flow into the cavity of the outer pipe and the inner pipe, LNG single-phase transportation is ensured, loss of the LNG in the transportation process is reduced, the BOG introduced into the cavity can provide heat preservation performance for the LNG, meanwhile, the cold energy provided by the LNG precools the subsequent reliquefied BOG, and energy loss is reduced.
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Description

Technical Field

[0001] The invention relates to a delivery pipeline, in particular to a casing type LNG delivery pipeline, belonging to the technical field of delivery pipelines. Background Art

[0002] Liquefied natural gas (LNG) is regarded as one of the cleanest fossil energy sources on earth due to its high energy density, convenient transportation and low environmental pollution. Its main component is methane, which has a density 600 times that of natural gas, but a mass of only about 45% of the same volume of water. It is known as the "energy flow carrier". However, the high and low temperature characteristics of LNG and the huge difference in ambient temperature cause it to gasify quickly during bare pipe transportation, resulting in gas blockage, which seriously affects the transportation efficiency.

[0003] At present, LNG pipeline transportation mainly adopts two methods: stacking insulation and vacuum insulation. Although the stacking insulation scheme has relatively low cost, it occupies a large space and the insulation effect is not as good as vacuum insulation. The vacuum insulation scheme has excellent insulation performance, but it is expensive. In addition, during the pipeline transportation process, the temperature difference between the inside and the outside causes LNG to gasify and produce BOG gas, thereby forming a two-phase flow. If not handled in time, more LNG will be gasified. At the same time, the airtightness of the pipeline connection leads to poor cold preservation, which will also affect the normal transportation of LNG.

[0004] In order to solve the above technical problems, a casing type LNG transmission pipeline is proposed. Summary of the invention

[0005] In view of this, the present invention provides a casing-type LNG transmission pipeline to solve or alleviate the technical problems existing in the prior art and at least provide a beneficial option.

[0006] The technical solution of the present invention is implemented as follows: a casing-type LNG delivery pipeline comprises a delivery pipe, a heat compensation mechanism and a stress compensation mechanism;

[0007] The delivery pipe is composed of an outer pipe and an inner pipe, a cavity is provided between the outer pipe and the inner pipe, flanges are installed at both ends of the delivery pipe, a first packing cavity and a second packing cavity are respectively provided on both sides of the delivery pipe, support rings are equidistantly arranged on the outer side of the inner pipe, and a low-temperature exhaust valve is installed on the outer surface of the inner pipe;

[0008] The interior of the outer tube is respectively provided with a moisture-proof layer and a heat-insulating layer;

[0009] The thermal compensation mechanism is sleeved on the outside of the conveying pipe, and the stress compensation mechanism is installed on the bottom of the thermal compensation mechanism.

[0010] Further preferably, the flange is provided with a threaded opening, and the two adjacent sections of the delivery pipe are fixed and locked by bolts.

[0011] Further preferably, the first filling cavity and the second filling cavity are filled with insulation powder.

[0012] Further preferably, the support ring is made of polytetrafluoroethylene, and the thickness of the support ring is mm.

[0013] Further preferably, the low-temperature exhaust valve is composed of a valve housing, a valve stem installed in the valve housing, and a valve ball installed at one end of the valve stem.

[0014] Further preferably, the thermal compensation mechanism consists of a bellows compensator and a fixing rod, the bellows compensator is sleeved on the outside of the outer tube, and four fixing rods are equidistantly distributed and arranged around the outside of the bellows compensator, both ends of the fixing rod pass through the flange end of the bellows compensator, and the fixing rod passes through one side of the bellows compensator and is threadedly connected to a limiting nut.

[0015] Further preferably, a fixing ring is sleeved on one side of the bellows compensator, the fixing rod passes through the fixing ring, and a lifting connector is sleeved on one side of the fixing ring.

[0016] Further preferably, the stress compensation mechanism consists of a bottom bracket and a shock absorber, four shock absorbers are formed into a group of two and are symmetrically hinged to the top of the bottom bracket, one end of the shock absorber is sleeved on one side of the fixed rod, and the shock absorber is rotatably connected to the fixed rod.

[0017] Further preferably, an arc-shaped support portion is integrally formed on one side of the bottom bracket, and weight-reducing grooves are evenly distributed inside the arc-shaped support portion.

[0018] The embodiment of the present invention has the following advantages due to the adoption of the above technical solution:

[0019] 1. The present invention arranges an inner tube for LNG transportation, and arranges a low-temperature exhaust valve on the inner tube, so that the gasified BOG can flow into the cavity between the outer tube and the inner tube, ensuring the single-phase transportation of LNG and reducing the loss of LNG during the transportation process. The BOG entering the cavity can provide thermal insulation performance for LNG, and the cold amount provided by LNG can be used for pre-cooling of the subsequent reliquefied BOG, thereby reducing energy loss;

[0020] Second, the connection between multiple pipes of the present invention is made through bolt connection, which is convenient, and the filling cavity at the connection ensures the heat preservation performance and sealing performance of the connection;

[0021] 3. In the present invention, the outer tube and the inner tube are separated by a support ring made of polyurethane material, which has a low thermal conductivity and can greatly reduce the amount of cold leakage from the outer tube of the inner tube.

[0022] The above summary is for illustrative purposes only and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments and features described above, further aspects, embodiments and features of the present invention will be readily apparent by reference to the accompanying drawings and the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 It is a structural diagram of the present invention;

[0025] Figure 2 It is a connection structure diagram of the present invention;

[0026] Figure 3 It is a structural diagram of the bottom bracket of the present invention;

[0027] Figure 4 It is a cross-sectional structural diagram of the outer tube and the inner tube in the present invention;

[0028] Figure 5 It is a structural diagram of the bellows compensator in the present invention;

[0029] Figure 6 It is a structural diagram of the low-temperature exhaust valve in the present invention;

[0030] Figure 7 It is a structural diagram of the support ring in the present invention;

[0031] Figure 8 It is a structural diagram of the fixing ring in the present invention.

[0032] Figure numerals: 11, outer tube; 12, inner tube; 13, flange; 14, bottom bracket; 15, shock absorber; 16, fixing rod; 17, bellows compensator; 18, fixing ring; 19, lifting connector; 21, arc-shaped support portion; 22, weight-reducing groove; 33, insulation layer; 34, moisture-proof layer; 35, first packing chamber; 36, second packing chamber; 37, support ring; 38, low-temperature exhaust valve; 41, valve housing; 42, valve stem; 43, valve ball. DETAILED DESCRIPTION

[0033] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.

[0034] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0035] Embodiment 1

[0036] like Figure 1-8 As shown, an embodiment of the present invention provides a casing-type LNG delivery pipeline, which is composed of a delivery pipe, a thermal compensation mechanism and a stress compensation mechanism.

[0037] The delivery pipe is composed of an outer pipe 11 and an inner pipe 12, a cavity is provided between the outer pipe 11 and the inner pipe 12, flanges 13 are installed at both ends of the delivery pipe, a first stuffing cavity 35 and a second stuffing cavity 36 are respectively provided on both sides of the delivery pipe, and support rings 37 are equidistantly distributed on the outer side of the inner pipe 12, the support rings 37 are made of polytetrafluoroethylene, and the thickness of the support ring 37 is 30 mm, a low-temperature exhaust valve 38 is installed on the outer surface of the inner pipe 12, and a moisture-proof layer 34 and a thermal insulation layer 33 are respectively provided inside the outer pipe 11.

[0038] In one embodiment, in order to facilitate the connection between the delivery pipes, the flange 13 is provided with a threaded opening, and two adjacent delivery pipes are fixed and locked by bolts.

[0039] In one embodiment, in order to ensure the thermal insulation performance and sealing performance of the connection of the conveying pipe, the first filling cavity 35 and the second filling cavity 36 are filled with insulation powder.

[0040] In one embodiment, the low-temperature exhaust valve 38 is composed of a valve housing 41 , a valve stem 42 installed in the valve housing 41 , and a valve ball 43 installed at one end of the valve stem 42 .

[0041] The thermal compensation mechanism consists of a bellows compensator 17 and a fixing rod 16. The bellows compensator 17 is sleeved on the outside of the outer tube 11. Four fixing rods 16 are equidistantly distributed and arranged around the outside of the bellows compensator 17. Both ends of the fixing rod 16 penetrate the flange end of the bellows compensator 17. The fixing rod 16 penetrates one side of the bellows compensator 17 and is threadedly connected to a limiting nut.

[0042] In one embodiment, in order to facilitate the lifting of the conveying pipe, a fixing ring 18 is sleeved on one side of the bellows compensator 17 , the fixing rod 16 passes through the fixing ring 18 , and a lifting connector 19 is sleeved on one side of the fixing ring 18 .

[0043] The stress compensation mechanism is composed of a bottom bracket 14 and a shock absorber 15. Four shock absorbers 15 are symmetrically hinged to the top of the bottom bracket 14 in a group of two. One end of the shock absorber 15 is sleeved on one side of a fixed rod 16. The shock absorber 15 is rotatably connected to the fixed rod 16. An arc-shaped support portion 21 is integrally formed on one side of the bottom bracket 14, and weight-reducing grooves 22 are evenly distributed inside the arc-shaped support portion 21.

[0044] Embodiment 2

[0045] like Figure 1-8 A casing-type LNG transmission pipeline is shown, comprising an inner tube 12, an outer tube 11 and a cryogenic exhaust valve 38. The inner tube 12 is located at the innermost part of the entire transmission system. A support ring 37 is arranged between the inner tube 12 and the outer tube 11 to provide space for BOG flow. At the same time, the cryogenic exhaust valve 38 is connected to the upper wall of the inner tube 12. The inner tube 12 flows LNG. The vaporized BOG enters the valve body through a pipeline connected to the inner tube 12 at the bottom of the cryogenic exhaust valve 38, and is discharged into the interlayer space of the inner and outer tubes 11 through the valve hole at the top of the cryogenic exhaust valve 38. The valve ball 43 inside the cryogenic exhaust valve 38 has a lower density than LNG. Under normal conditions, the top of the valve body filled with part of LNG is a BOG space to ensure that BOG does not enter the inner tube 12.

[0046] The outer tube 11 ensures cold preservation while preventing water vapor from entering. An austenitic stainless pipe is arranged at the bottom of the outer tube 11. A prefabricated insulation material is arranged outside the steel pipe as an insulation layer 33. The surface of the insulation layer 33 is covered with a moisture-proof layer 34 to prevent water vapor from entering. Finally, the outermost aluminum steel pipe of the outer tube 11 is arranged.

[0047] At the pipe connection, a first stuffing cavity 35 and a second stuffing cavity 36 are provided. The two pipes are connected by bolts. Flanges 13 are symmetrically arranged on both sides of the pipes. At the same time, to enhance air tightness, rubber gaskets can be provided between the flanges 13. Behind the two flanges 13 is a stuffing cavity. Pearlescent sand is filled after the pipes are connected to enhance the thermal insulation of the connection and prevent cold loss.

[0048] In one embodiment, the inner tube 12 is made of austenitic stainless steel. In order to separate the inner and outer tubes 11 and form a cavity, in addition to the BOG gas generated by the gasification of LNG during transportation, BOG is introduced into the cavity in advance to make it a cold insulation layer to reduce the gasification rate of LNG. Polytetrafluoroethylene is used as the material of the support ring 37, and a support ring 37 is arranged every 1m to ensure the continuity between the cavities and avoid direct contact between the inner and outer walls.

[0049] In order to isolate the influence of the external environment, the outer pipe 11 is composed of a three-layer structure. The first layer is directly in contact with the low-temperature fluid and is made of austenitic stainless steel. The second layer is arranged with a PIR foam insulation layer 33. The outer wall of the insulation layer 33 is paved with glass cloth coated with horseshoe grease on both sides as a moisture-proof layer 34, and the outer wall is paved with aluminum-plated steel plate.

[0050] In one embodiment, due to the large temperature changes during LNG transportation, the pipeline will cause thermal expansion and contraction. A bellows compensator 17 is installed outside the outer tube 11. Considering the stress of the pipeline during installation and operation, a fixing ring 18 is installed on the fixing rod 16 of the bellows compensator 17, and a lifting connector 19 is provided on the fixing ring 18 to lift the delivery pipe. A bottom bracket 14 is provided at the bottom to cooperate with the shock absorber 15 for support, etc., to compensate for the pipeline stress.

[0051] When the present invention is working, BOG is introduced into the cavity between the outer tube 11 and the inner tube 12 in advance to form a cold insulation layer, thereby reducing the gasification rate of LNG. The delivery pipes are connected by bolts and flanges 13, and pearl sand is filled in the first filling cavity 35 and the second filling cavity 36 at the connection to enhance the thermal insulation of the connection. After the connection, BOG is introduced into the cavity in advance, and the air tightness is tested. There is no leakage at the pipeline connection. After the inner tube 12 is precooled, LNG is transported. During the transportation process, the gasified BOG enters the cavity through the low-temperature exhaust valve 38, thereby ensuring the single-phase transportation of LNG and reducing the loss of LNG during the transportation process. The BOG introduced into the cavity can provide thermal insulation performance for LNG, and the cold amount provided by LNG is used for precooling the subsequent reliquefied BOG, thereby reducing energy loss.

[0052] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of various changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A casing type LNG transmission pipeline, characterized in that: It includes a conveying pipe, a heat compensation mechanism and a stress compensation mechanism; The delivery pipe is composed of an outer pipe (11) and an inner pipe (12); a cavity is provided between the outer pipe (11) and the inner pipe (12); flanges (13) are installed at both ends of the delivery pipe; a first packing cavity (35) and a second packing cavity (36) are respectively provided on both sides of the delivery pipe; support rings (37) are equidistantly arranged on the outer side of the inner pipe (12); and a low-temperature exhaust valve (38) is installed on the outer surface of the inner pipe (12); The outer tube (11) is provided with a moisture-proof layer (34) and a heat-insulating layer (33) inside. The thermal compensation mechanism is sleeved on the outside of the conveying pipe, and the stress compensation mechanism is installed on the bottom of the thermal compensation mechanism.

2. The casing-type LNG transportation pipeline according to claim 1, characterized in that: The flange (13) is provided with a threaded opening, and two adjacent sections of the delivery pipe are fixed and locked by bolts.

3. The casing-type LNG transportation pipeline according to claim 1, characterized in that: The first filling cavity (35) and the second filling cavity (36) are filled with powder for heat insulation.

4. The casing-type LNG transportation pipeline according to claim 1, characterized in that: The support ring (37) is made of polytetrafluoroethylene, and the thickness of the support ring (37) is 30 mm.

5. The casing-type LNG transportation pipeline according to claim 1, characterized in that: The low-temperature exhaust valve (38) is composed of a valve housing (41), a valve stem (42) installed in the valve housing (41), and a valve ball (43) installed at one end of the valve stem (42).

6. The casing-type LNG transportation pipeline according to claim 1, characterized in that: The thermal compensation mechanism is composed of a bellows compensator (17) and a fixing rod (16). The bellows compensator (17) is sleeved on the outside of the outer tube (11). Four fixing rods (16) are equidistantly distributed and arranged around the outside of the bellows compensator (17). Both ends of the fixing rod (16) penetrate the flange end of the bellows compensator (17). The fixing rod (16) penetrates one side of the bellows compensator (17) and is threadedly connected to a limiting nut.

7. The casing-type LNG transportation pipeline according to claim 6, characterized in that: A fixing ring (18) is sleeved on one side of the bellows compensator (17), the fixing rod (16) passes through the fixing ring (18), and a lifting connector (19) is sleeved on one side of the fixing ring (18).

8. The casing-type LNG transportation pipeline according to claim 6, characterized in that: The stress compensation mechanism is composed of a bottom bracket (14) and a shock absorber (15). Four shock absorbers (15) are symmetrically hinged to the top of the bottom bracket (14) in a group of two. One end of the shock absorber (15) is sleeved on one side of a fixed rod (16). The shock absorber (15) is rotatably connected to the fixed rod (16).

9. The casing-type LNG transportation pipeline according to claim 8, characterized in that: An arc-shaped support portion (21) is integrally formed on one side of the bottom bracket (14), and weight-reducing grooves (22) are evenly spaced inside the arc-shaped support portion (21).