LNG (Liquefied Natural Gas) pipeline leakage protection system and split flange elbow device

Abstract

The invention relates to an LNG pipeline leakage protection system and a split flange elbow device, and belongs to the technical field of ship manufacturing. A low-pressure pump in an LNG fuel cabin is used for pumping fuel, the fuel is conveyed to a fuel gas preparation room through an inner pipe, the inner pipe is wrapped with a heat preservation layer, the heat preservation layer is sleeved with an outer pipe, the turning position of the outer pipe is connected through a split flange elbow, and an annular space is formed between the outer pipe and the heat preservation layer; a temperature sensor and a pressure sensor are arranged in the annular space, and a ventilation valve is arranged on the outer pipe and connected to a ventilation mast pipeline; the split flange elbow is composed of an elbow pipe, an upper flange seat and a lower flange seat, a bolt is connected with the outer pipe through the connecting hole, and a sealing ring is arranged on the connecting end face; the flanged elbow is cut into two symmetrical halves in the diameter direction, and a sealing gasket is arranged between the sectioning planes. The system can bear LNG leakage, can carry out leakage monitoring on the pipeline and discharge leaked gas, avoids damage to the pipeline caused by too large pressure of the pipeline, is convenient to disassemble and overhaul, and can realize stable sealing.

Description

Technical Field

[0001] This invention relates to an LNG pipeline leakage protection system and a split flange elbow device, which belongs to the field of shipbuilding technology. Background Technology

[0002] With increasingly stringent global emission regulations, many ships are equipped with LNG (Liquefied Natural Gas) fuel systems. LNG fuel leaks onto open decks can cause low-temperature corrosion. Existing leak protection methods often employ vacuum double-walled pipes, such as the anti-pollution process for continuous vacuum-insulated double-walled pipes disclosed in document CN 109667996 B. This method uses double-walled vacuum insulation, effectively avoiding the shortcomings of conventional insulation materials, such as easy leakage and difficulty in detection. Strict anti-pollution measures are implemented for both the inner and outer pipes of the double-walled pipe, achieving long-term stable vacuum, reliable, and efficient LNG transportation. However, vacuum pipes are expensive, and repairs after leaks are difficult. Summary of the Invention

[0003] To address the problems of difficult leak detection, repair, and high equipment costs in existing technologies, as well as the low-temperature corrosion of decks caused by leaks, this invention provides an LNG pipeline leak protection system and a split flange elbow device. This system can monitor leaks in real time, facilitate disassembly and maintenance, provide stable sealing, and can absorb LNG leaks, thus preventing low-temperature corrosion of the deck.

[0004] An LNG pipeline leakage protection system and a split flange elbow device are disclosed. The system uses a low-pressure pump in the LNG fuel tank to extract fuel, which is then transported to the gas preparation room through an inner pipe. The inner pipe is wrapped with an insulation layer, and an outer pipe is fitted over the insulation layer. Split flange elbows are used to connect the outer pipe at bends, and an annular space is formed between the outer pipe and the insulation layer. Temperature and pressure sensors are installed on the outer tube, with their detection ends inserted into the annular space. A vent valve is installed on the outer tube and connected to the vent mast pipeline. The split flange elbow includes two symmetrical bends, an upper flange seat and a lower flange seat located at both ends of the bend, and an outer bend connecting lug and an inner bend connecting lug located on both sides of the bend. The two half-bends are fastened together so that the inner bend connecting ears on the two half-bends correspond to each other and the outer bend connecting ears correspond to each other. Sealing gaskets are set at the contact surfaces and bolts are used to lock the two half-bends together into one piece. The flange seat is provided with a boss, and bolts are used to connect it to the outer pipe through the connecting hole. A sealing ring is provided on the connecting end face. The sealing gasket has the same shape as the connecting lug, but its length is greater than that of the connecting lug. When in use, the sealing gasket is folded, and the sealing ring is used to press the folded sealing gasket at the connecting end face to achieve a seal at the junction of the flange seat and the connecting lug.

[0005] Furthermore, the outer tube is a split flange outer tube, which is formed by two symmetrical semi-circular tubes with ribs fastened together, and the ribs are locked with bolts; a rib sealing gasket is set between the contact surfaces of the two ribs. The gasket has the same shape as the ribs and is longer than the ribs. When in use, the rib sealing gasket is folded and pressed with a sealing ring to achieve a seal at the junction of the outer tube flange and the ribs.

[0006] Furthermore, the temperature sensor, pressure sensor, and vent valve are connected to the controller.

[0007] Furthermore, several supports are installed between the outer tube and the insulation layer.

[0008] Furthermore, several pipe supports are installed on the deck near the outer pipe.

[0009] Furthermore, the flange, connecting lug, and rib are provided with positioning holes.

[0010] Compared with the prior art, the present invention has the following advantages: The LNG pipeline leakage protection system and split flange elbow device can withstand LNG leakage, monitor pipeline leakage, and discharge leaked gas when necessary to avoid pipeline damage caused by excessive pressure. It is also easy to disassemble and maintain to achieve stable sealing. Attached Figure Description

[0011] 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 some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 This is a schematic diagram of the LNG pipeline leakage protection system and the split flange elbow device.

[0013] Figure 2 This is a cross-sectional view of the pipe (AA section).

[0014] Figure 3 It is an LNG pipeline leakage protection system that uses a split outer pipe.

[0015] Figure 4 This is a cross-sectional view of pipe A'-A'.

[0016] Figure 5 This is a top view of the outer tube.

[0017] Figure 6 This is a schematic diagram of the sealing strip on the outer rib plate of the split flange.

[0018] Figure 7This is a schematic diagram of the split flange elbow split in the middle.

[0019] Figure 8 This is a diagram of the split flange elbow along direction B.

[0020] Figure 9 This is a C-direction diagram of a split flange elbow.

[0021] Figure 10 This is a schematic diagram of the split flange elbow sealing structure.

[0022] In the diagram: 1. LNG fuel tank; 2. Low-pressure pump; 3. Inner pipe; 4. Insulation layer; 5. Outer pipe; 51. Outer pipe flange; 511. Outer pipe flange boss; 513. Outer pipe flange sealing ring; 53. Rib; 533. Rib sealing gasket; 6. Split flange elbow; 61. Upper flange seat; 611. Upper flange seat boss; 612. Upper flange seat connection hole; 613. Upper flange seat sealing ring; 62. Lower flange seat; 621. Lower flange seat boss; 622. Lower flange seat connection hole; 623. Lower flange seat sealing ring; 63. Inner bend connecting lug; 631 632. Inner bend connecting ear positioning hole; 633. Inner bend connecting ear connecting hole; 634. Inner bend sealing gasket; 645. Inner bend sealing gasket folding part; 646. Outer bend connecting ear; 647. Outer bend connecting ear positioning hole; 648. Outer bend connecting ear connecting hole; 649. Outer bend sealing gasket; 640. Outer bend sealing gasket folding part; 65. Bend; 7. Gas preparation room; 86. Controller; 87. Annular space; 88. Temperature sensor; 89. Pressure sensor; 80. Vent valve; 81. Bracket; 9. Vent mast pipeline; 10. Deck; 11. Pipe support. Detailed Implementation

[0023] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0026] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0027] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention. The directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0028] For ease of description, spatial relative terms such as "above," "over," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation besides the orientation of the device as described in the figures. For example, if the device in the figures is inverted, a device described as "above" or "above" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0029] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0030] This invention discloses an LNG pipeline leakage protection system and a split flange elbow device (such as...). Figure 1 Using a low-pressure pump 2 installed in the LNG fuel tank 1, fuel is drawn and transported to the gas preparation room 7 through an inner pipe 3. The inner pipe 3 is wrapped with an insulation layer 4, and an outer pipe 5 is fitted over the insulation layer 4. An annular space 80 is formed between the outer side of the insulation layer 4 and the outer pipe 5.

[0031] The LNG stored in LNG fuel tank 1 is in a cryogenic liquid state (approximately -162 degrees Celsius) with low pressure, while the dual-fuel engine requires gaseous natural gas and must meet specific pressure, temperature and flow requirements.

[0032] In use, the gas preparation room 7 (also known as the gas processing room / gas module room) uses integrated equipment to vaporize LNG, heat it to room temperature, and then gradually depressurize it to the engine's matching pressure. The liquefied natural gas (LNG) stored on the ship undergoes a series of processes such as depressurization, heating, filtration, and metering to bring it to a state where it can be directly used by the engine.

[0033] The core function of the LNG transmission pipeline insulation layer 4 is to efficiently retain cold and reduce cold loss, while preventing condensation and ice formation on the outer wall of the pipeline, protecting the pipeline structure and ensuring personnel safety. It also blocks the transfer of external heat through its extremely low thermal conductivity, thereby reducing the evaporation rate of LNG inside the pipeline.

[0034] Several supports 84 are installed between the outer pipe 5 and the insulation layer 4 to maintain the annular space 80 formed between the outer pipe 5 and the insulation layer 4, preventing the insulation layer 4 from being squeezed and damaged. The insulation layer 4 must be firmly fixed to resist the ship's swaying. This annular space 80 can serve as a leakage protection space to absorb LNG leaks, and as an emergency storage and vaporization facility to temporarily store or safely vaporize LNG, preventing leaks to the open deck and causing low-temperature corrosion.

[0035] On the other hand, a temperature sensor 81 and a pressure sensor 82 are installed inside the annular space 80, and a vent valve 83 is installed on the vent mast pipe 9 connected to the outer pipe 5. The temperature sensor 81, pressure sensor 82, and vent valve 83 are connected to the controller 8. When a leak occurs, the annular space 80 will experience low temperature and high pressure. The controller 8 will issue a leak alarm and control the vent valve 83 to open, allowing the leaked gas to be discharged through the vent mast pipe 9, thus preventing excessive pressure inside the annular space 80 from damaging the pipe.

[0036] Specifically, when the temperature sensor 81 detects that the set temperature has reached -50 degrees Celsius, or when the pressure sensor 82 detects that the set pressure has reached 3 bar, the controller 8 issues a leak alarm and opens the vent valve 83 at the same time, releasing the gas through the vent valve to prevent overpressure in the pipeline.

[0037] Due to the flammable and explosive nature of LNG, open flames should be avoided around the pipeline. Split flange elbows (6) are used for connection at bends in the outer pipe (5). This special design allows for the installation, maintenance, and replacement of the flange without disassembling the pipeline system, facilitating installation and disassembly, enabling hot work without open flames, and simplifying maintenance.

[0038] Flange elbow (such as) Figure 7 , 8 9) It consists of a bend 65 and upper flange seats 61 and lower flange seats 62 at both ends. The flange seats are provided with bosses. In use, it is connected to the outer pipe 5 by means of a sheet-like sealing ring (for radial sealing), upper flange seat 61, lower flange seat connecting hole 622, and bolts.

[0039] Split flanges (also known as butt flanges or split flanges) are flange elbows that have been cut into two symmetrical halves along the diametrical direction (e.g., Figure 7 The cut flange has an inner and outer curved connecting lug. The connecting lug has positioning holes and mounting holes, and is connected using positioning pins and bolts. The cut flange seats are then fitted together to form a complete flange seat. (e.g., strip gasket) Figure 10 Placed between the cut surfaces, it completes the axial seal and ensures a tight seal.

[0040] The shape of the sealing gasket is set according to the connecting lug, and its length is longer than the connecting lug. The part of the length exceeding the connecting lug is folded over to the flange end face and pressed under the flange seat sealing ring during installation (e.g., Figure 10The sealing ring presses against the sealing gasket to seal the junction between the flange seat and the connecting lug, thus completing the axial and radial sealing of the split flange elbow. In use, the two split flange elbows are placed on either side of the pipeline, and the two flange halves are fastened together with bolts to form a complete sealed connection. Disassembly is simple: just loosen the bolts to separate the flanges without damaging the piping system.

[0041] Specifically, the upper flange seat 61 is provided with an upper flange seat boss 611, which works with the upper flange seat sealing ring 613 and is connected to other flanges using the upper flange seat connection hole 612; the lower flange seat 62 is provided with a lower flange seat boss 621, which works with the lower flange seat sealing gasket 623 and is connected using the lower flange seat connection hole 622.

[0042] The inner curved connecting ear 63 is used in conjunction with the inner curved sealing gasket 633. During use, it is first positioned through the inner curved connecting ear positioning hole 631, and then connected through the inner curved connecting ear connecting hole 632. The outer curved connecting ear 64 is used in conjunction with the outer curved sealing gasket 643. During use, it is first positioned through the outer curved connecting ear positioning hole 641, and then connected through the outer curved connecting ear connecting hole 642.

[0043] The portion of the inner curved sealing gasket 633 that extends beyond the inner curved connecting lug 63 is the inner curved sealing gasket folded portion 633a. In use, the inner curved sealing gasket folded portion 633a folds over the end faces of the upper flange seat 61 and the lower flange seat 62. During installation, it is pressed under the upper flange seat sealing ring 613 and the lower flange seat sealing ring 623 (e.g., ...). Figure 10 The portion of the outer curved sealing gasket 643 that extends beyond the outer curved connecting lug 64 is the outer curved sealing gasket folded portion 643a. In use, the outer curved sealing gasket folded portion 643a folds over the end faces of the upper flange seat 61 and the lower flange seat 62. During installation, it is pressed under the upper flange seat sealing ring 613 and the lower flange seat sealing ring 623 (e.g., ...). Figure 10 When the required outer tube 5 is relatively short, a solid round tube can be used directly as the outer tube 5 (e.g., Figure 1 , 2 It is installed outside the insulation layer 4, and a bracket 84 can be installed in the middle for support as needed. The two ends are connected to other structures using flanges.

[0044] When the required outer pipe 5 is relatively long, it is difficult to directly fit the outer pipe 5 onto the insulation layer 4, and it is also difficult to install the support bracket 84 within the annular space. A split flange outer pipe can be used as the outer pipe 5 (e.g., Figure 3 The outer pipe is a split flange, with flanges at both ends. The outer pipe is cut into two symmetrical halves along the diameter, and ribs 53 are provided at the cut. Figure 5 To prevent deformation of the outer tube 5, the rib plate 53 is provided with bolt holes for connecting the two split flange outer tubes.

[0045] Rib sealing gaskets 533 are provided between the cut surfaces (e.g.) Figure 6 The sealing gasket 533 has the same shape as the rib plate but is longer than the rib plate 53. The portion exceeding the connecting lug is folded up to the flange end face and tightened with a sealing ring to achieve a seal at the junction of the outer pipe flange 51 and the rib plate 53. All the aforementioned sealing rings and various sealing gaskets are made of polytetrafluoroethylene (PTFE), which can still ensure a seal at -162 degrees Celsius even if LNG leaks, avoiding the use of ordinary sealing materials, which harden and lose their sealing ability at low temperatures. This completes the containment of leaked LNG and prevents LNG from directly leaking onto the deck and causing low-temperature corrosion.

[0046] Locating holes are provided on the flanges, connecting lugs, and ribs 53 (when using split flange outer pipes) to quickly locate the bolt hole positions between flanges, connecting lugs, and ribs 53. During installation, insert 1-2 locating pins into the corresponding locating holes to keep the bolt holes aligned, avoid bolt hole misalignment, and significantly improve installation efficiency; avoid forcibly screwing in bolts due to bolt hole misalignment during installation, prevent bolt thread damage and flange hole deformation, and reduce subsequent maintenance risks.

[0047] Several pipe supports 11 are installed on the deck near the outer pipe 5 to fix the outer pipe 5 and support its weight.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An LNG pipeline leakage protection system and a split flange elbow device, wherein fuel is drawn from a low-pressure pump (2) in an LNG fuel tank (1) and transported to a gas preparation room (7) via an inner pipe (3), the inner pipe (3) is wrapped with an insulation layer (4), and an outer pipe (5) is fitted over the insulation layer (4), characterized in that: The outer pipe (5) is connected by a split flange elbow (6) at the bend, and an annular space (80) is formed between the outer pipe (5) and the insulation layer (4). Temperature sensor (81) and pressure sensor (82) are installed on the outer tube (5), and their detection ends are inserted into the annular space (80). A vent valve (83) is installed on the outer tube (5) and connected to the vent mast pipe (9). The split flange elbow (6) includes two symmetrical bends (65), an upper flange seat (61) and a lower flange seat (62) at both ends of the bend, and an outer bend connecting lug (64) and an inner bend connecting lug (63) on both sides of the bend. The two half-bends (65) are fastened together so that the inner bend connecting ears (63) on the two half-bends correspond to each other and the outer bend connecting ears (64) correspond to each other. Sealing gaskets are provided at the contact surfaces and bolts are used to lock the two half-bends (65) together. A boss is provided on the flange seat, and bolts are used to connect it to the outer pipe (5) through the connecting hole. A sealing ring is provided on the connecting end face. The shape of the sealing gasket is the same as that of the connecting ear, but the length is greater than that of the connecting ear. When in use, the sealing gaskets that exceed the connecting ear are folded onto the flange end face at both ends. The sealing gaskets are pressed tightly with the sealing ring at the connecting end face to achieve the sealing at the junction of the flange seat and the connecting ear.

2. The LNG pipeline leakage protection system and split flange elbow device according to claim 1, characterized in that: The outer tube (5) is a split flange outer tube, which is made of two symmetrical semi-circular tubes with ribs (53) fastened together, and the ribs (53) are locked with bolts; a rib sealing gasket (533) is set between the contact surfaces of the two ribs (53). The gasket (533) has the same shape as the rib and is longer than the rib (53). When in use, the rib sealing gasket (533) is folded and the sealing ring is used to press it to achieve a seal at the junction of the outer tube flange (51) and the rib (53).

3. An LNG pipeline leakage protection system and a split flange elbow device according to claim 1 or 2, characterized in that: The temperature sensor (81), pressure sensor (82), and vent valve (83) are connected to the controller (8).

4. An LNG pipeline leakage protection system and a split flange elbow device according to claim 1 or 2, characterized in that: Several supports (84) are provided between the outer pipe and the insulation layer.

5. An LNG pipeline leakage protection system and a split flange elbow device according to claim 1 or 2, characterized in that: Several pipe supports (11) are installed on the deck (10) near the outer pipe.

6. An LNG pipeline leakage protection system and a split flange elbow device according to claim 2, characterized in that: The flange, connecting lug, and rib are provided with positioning holes.

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