Liquid nitrogen conveying pipeline externally connected with vacuum maintaining jumper connection pipe

Abstract

The utility model provides a liquid nitrogen conveying pipeline externally connected with a vacuum maintaining jumper pipe, inner cavities of two double-layer hollow pipelines are communicated, a sealing end cover is connected between the inner wall and the outer wall of one end, close to a flange, of each double-layer hollow pipeline, and outer cavities of the double-layer hollow pipelines at the two ends of the flange are isolated by the sealing end covers. The inner wall of the first double-layer hollow pipeline is sunken inwards in the axial direction, and the inner wall of the second double-layer hollow pipeline extends outwards in the axial direction, penetrates through the flange and extends into the first double-layer hollow pipeline; the outer walls of the two double-layer hollow pipelines are respectively provided with a first interface and a second interface which are connected with respective outer cavities, a vacuum maintaining jumper pipe is connected between the first interface and the second interface, and three interfaces of the vacuum maintaining jumper pipe are connected with the first interface, the second interface and a vacuum maintaining system. According to the liquid nitrogen conveying pipeline system, the liquid nitrogen conveying efficiency and safety are improved, and good economical efficiency and practicability are achieved.

Description

Technical Field

[0001] The utility model relates to a transportation pipeline system for cryogenic liquids, and particularly to a liquid nitrogen transportation pipeline externally connected with a vacuum maintenance jump pipe. Background Art

[0002] At present, most vacuum pipeline systems adopt a double-layer pipeline structure. The cryogenic liquid flows inside, and the outer layer is a vacuum insulation layer. Before leaving the factory, each section of the pipeline (normally 7-8 meters, convenient for transportation and installation) is individually evacuated and sealed, and then installed at the place of use. Currently, the vacuum degree of the vacuum insulation layer of the vacuum pipeline is mainly ensured by two methods: passive vacuum maintenance and dynamic vacuum maintenance. In the former method, additional heat-insulating materials are filled in the vacuum part of the double-layer pipeline to enhance the heat-insulating performance. In the latter method, a vacuum pump is used to maintain the vacuum degree of a certain length of the pipeline section.

[0003] After long-term use of the existing double-layer vacuum liquid nitrogen transportation pipeline system, the vacuum degree of the vacuum insulation layer will decrease, resulting in a significant decline in the heat-insulating effect. At the same time, the problem of condensation on the outer surface will also occur. In addition, the decrease in the heat-insulating effect easily causes the liquid nitrogen transported in the pipeline to vaporize, and the occurrence of gas blockage in the pipeline greatly reduces the transportation efficiency of the liquid nitrogen, exacerbating the liquid nitrogen loss and energy consumption. Moreover, the number of conventional dynamic vacuum maintenance systems used is relatively large. Each section of the vacuum pipeline requires a dynamic vacuum maintenance system, and the use cost is relatively high when the pipeline length is not long, resulting in waste. Summary of the Utility Model

[0004] The utility model provides a liquid nitrogen transportation pipeline externally connected with a vacuum maintenance jump pipe. The liquid nitrogen transportation pipeline includes two double-layer hollow pipelines connected by a flange. Each double-layer hollow pipeline is provided with an inner wall and an outer wall. The inner cavity of the inner wall is used for transporting liquid nitrogen, and the outer cavity between the inner and outer walls is a vacuum insulation cavity. The inner cavities of the two double-layer hollow pipelines are connected and communicated. And a sealing end cover is connected between the inner and outer walls of the double-layer hollow pipeline near one end of the flange, and the outer cavities of the double-layer hollow pipelines at both ends of the flange are isolated by the sealing end cover.

[0005] The inner wall of the first double-layer hollow pipeline is recessed inward in the axial direction, and the inner wall of the second double-layer hollow pipeline extends outward in the axial direction and passes through the flange and extends into the interior of the first double-layer hollow pipeline. The sealing end cover is L-shaped.

[0006] The outer walls of the two double-layer hollow pipelines are respectively provided with a first interface and a second interface connected to their respective outer cavities. A vacuum maintenance jump pipe is connected between the first interface and the second interface. The vacuum maintenance jump pipe is a three-way pipe, and the three interfaces of the three-way pipe are connected to the first interface, the second interface, and a vacuum maintenance system respectively. Manual valves are respectively arranged at the first interface and the second interface.

[0007] Furthermore, the contact end faces of the two double-layer hollow pipes are provided with mutually fitting steps.

[0008] Furthermore, the vacuum maintenance jump pipe includes a metal bellows body, and two of the interfaces of the metal bellows body are respectively connected to the first interface and the second interface through straight pipe joints.

[0009] Furthermore, the sealing end cap of the second double-layer hollow pipe extending into the first double-layer hollow pipe is provided with a sealing ring groove, and a sealing ring is installed in the sealing ring groove.

[0010] The advantages of the present utility model are as follows:

[0011] 1. The vacuum jump pipe is connected to both ends of the sealed vacuum pipe section, connecting the vacuum insulation layers of each conveying pipe on site, and can be additionally connected to a vacuum pump. By the vacuum pump, the vacuum of the vacuum insulation layer is maintained. With a vacuum probe and a control system, the vacuum degree can be stably maintained within a range for a long time.

[0012] 2. The vacuum insulation cavities are connected in series and communicate with each other. By maintaining the vacuum degree with a vacuum pump, the reliability and stability of the entire system are significantly improved, effectively avoiding the problem of the vacuum degree of the vacuum insulation layer decreasing after long-term use.

[0013] 3. The vacuum maintenance jump pipe is convenient for maintaining and overhauling the pipeline system, improving the reliability and service life of the system.

[0014] 4. The design of the sealing end cap and the steps not only improves the sealing performance but also ensures the connection stability, reducing the problem of sealing failure.

[0015] 5. The number of vacuum systems used is greatly reduced, and the use cost is significantly reduced.

[0016] 6. When a fault occurs, the problem pipeline can be quickly isolated without affecting the operation of other normal pipelines, thereby improving the maintenance efficiency of the system and reducing the maintenance cost.

[0017] 7. The structural design of the present utility model is simple, easy to manufacture and maintain, and has good market application prospects.

[0018] The present utility model provides a liquid nitrogen conveying pipeline system with reasonable structure and excellent performance, which not only improves the efficiency and safety of liquid nitrogen conveying but also has good economy and practicability. Through the implementation of the present utility model, the energy consumption during liquid nitrogen conveying can be effectively reduced, the stability and reliability of the system can be improved, providing an efficient and energy-saving liquid nitrogen conveying solution for related industries. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0020] Figure 1 Schematic diagram of a three-way vacuum maintenance jump connection pipe connected between two butt-jointed double-layer hollow pipes of the present invention;

[0021] Figure 2 Schematic diagram of the cooperation of two adjacent double-layer hollow pipes. Detailed implementation manners

[0022] In the following description, a large number of specific details are given to provide a more thorough understanding of the present invention. However, it is obvious to those skilled in the art that the present invention can be implemented without one or more of these details. In other examples, to avoid confusion with the present invention, some well-known technical features in the art are not described.

[0023] To thoroughly understand the present invention, detailed steps and detailed structures will be proposed in the following description to explain the technical solutions of the present invention. The preferred embodiments of the present invention are described in detail as follows. However, in addition to these detailed descriptions, the present invention can also have other implementation manners.

[0024] Referring to Figure 1 As shown, the present invention provides a liquid nitrogen delivery pipe externally connected with a vacuum maintenance jump connection pipe 6. The liquid nitrogen delivery pipe includes two double-layer hollow pipes connected by a flange 4. Let these two double-layer hollow pipes be the first double-layer hollow pipe 11 and the second double-layer hollow pipe 12 respectively.

[0025] Both the first double-layer hollow pipe 11 and the second double-layer hollow pipe 12 are provided with an inner wall 13 and an outer wall 14. The inner cavity 2 of the inner wall 13 is used to transport liquid nitrogen, and the outer cavity 1 between the inner and outer walls 14 is a vacuum insulation cavity. The inner cavities 2 of the two double-layer hollow pipes are connected and communicated. A sealing end cover 15 is connected between the inner and outer walls 14 of the first double-layer hollow pipe 11 near the flange end, and the outer cavity 1 of the first double-layer hollow pipe 11 and the outer cavity 1 of the second double-layer hollow pipe 12 are isolated by the sealing end cover 15. A sealing end cover 15 is also provided at one end of the second double-layer hollow pipe 12 near the flange.

[0026] As Figure 2As shown, the inner wall 13 of the first double-layer hollow pipe 11 on the right side is recessed inward in the axial direction to form a plug hole, and the inner wall 13 of the second double-layer hollow pipe 12 on the left side extends outward in the axial direction, so that the inner wall 13 of the second double-layer hollow pipe 12 can pass through the flange and extend into the internal plug hole of the first double-layer hollow pipe. By extending the inner wall 13 of the second double-layer hollow pipe 12 into the interior of the first double-layer hollow pipe 11, the distance between the inner wall joint and the outer wall joint of the two double-layer hollow pipes is increased, which is conducive to strengthening the seal and avoiding the low-temperature liquid nitrogen leaking from the inner wall joint from affecting the flange as much as possible. In order to adapt to the design of the inner wall center tube protruding forward at one end, the sealing end cover 15 is adaptively changed to an L-type.

[0027] The contact end faces of the two double-layer hollow pipes are provided with mutually fitting steps 16 (i.e., the radial contact end faces of the sealing end covers 15 of the two double-layer hollow pipes). The design of the step 16 can increase the contact area and at the same time form a bite between the sealing end covers 15 of the first double-layer hollow pipe 11 and the second double-layer hollow pipe 12, which, on the one hand, improves the sealing effect and reduces the possibility of vacuum leakage, and on the other hand, ensures the stability of the connection and reduces the impact of vibration or thermal expansion and contraction on the sealing of the pipe. The size of the step 16 is precisely calculated to ensure that the pipe connection still maintains good sealing performance when subjected to different pressures and temperature changes. In addition, the surface of the step 16 is specially treated to improve its wear resistance and corrosion resistance, thereby extending the service life of the entire pipe system.

[0028] In practical applications, the connection between the first double-layer hollow pipe 11 and the second double-layer hollow pipe 12 needs to consider not only the sealing but also the convenience of installation. Therefore, in the design, the shape and size of the step 16 are optimized so that the pipes can be quickly aligned and easily inserted during connection, greatly improving the installation efficiency.

[0029] Furthermore, the second double-layer hollow pipe sealing end cover 15 extending into the first double-layer hollow pipe is provided with a sealing ring groove 17, and a sealing ring 18 is installed in the sealing ring groove to further improve the sealing effect.

[0030] The outer walls 14 of the first double-layer hollow pipe 11 and the second double-layer hollow pipe 12 are respectively provided with a first interface 7 and a second interface 8 connected to their respective outer cavities 1, and a vacuum maintaining jumper pipe 6 is connected between the first interface 7 and the second interface 8. The vacuum maintaining jumper pipe 6 is a three-way pipe, and the three interfaces of the three-way pipe are respectively connected to the first interface 7, the second interface 8 and the vacuum maintaining system (i.e., the vacuum maintaining system shown in the figure), and the first interface 7 and the second interface 8 are respectively provided with a manual valve 5.

[0031] In an alternative embodiment, the vacuum maintenance jumper tube 6 includes a metal bellows body, and two interfaces of the metal bellows body are respectively connected to the first interface 7 and the second interface 8 through straight pipe joints 9.

[0032] Before transporting liquid nitrogen, two manual valves 5 need to be opened to ensure that the outer cavities 1 of the first double-layer hollow pipe 11 and the second double-layer hollow pipe 12 are interconnected. Then, a vacuum maintenance system is used to maintain a vacuum in all the interconnected outer cavities 1. Subsequently, the liquid nitrogen delivery pipe starts to transport cryogenic liquid, and the pipeline system enters the normal working state. After the pipeline system stops being used, the liquid nitrogen inside the pipe needs to be completely emptied first, then all the manual valves 5 of the vacuum maintenance jumper tube are closed, and finally the vacuum maintenance system is shut down.

[0033] When a section of the double-layer hollow pipe fails, the manual valves 5 connecting the two ends of the pipe to the vacuum maintenance jumper tube 6 can be closed to isolate the outer cavity 1 of the problematic pipe from the outer cavities 1 of other pipes, which is convenient for inspection and maintenance and ensures the vacuum degree of the outer cavities 1 of other normal pipelines during the inspection process. After the inspection is completed, the valves at both ends of the pipe are opened again to make its outer cavity 1 communicate with the vacuum maintenance system again.

[0034] The vacuum jumper tube is connected to both ends of the sealed vacuum pipe section, connecting the vacuum insulation layers of each conveying pipeline on-site, and can be additionally connected to a vacuum pump. The vacuum pump is used to evacuate the vacuum insulation layer, and with a vacuum probe and a control system, the vacuum degree can be stably maintained within a certain range for a long time.

[0035] The preferred embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the above specific embodiments, and the equipment and structures not described in detail should be understood to be implemented in a common manner in the art; any person skilled in the art can make many possible changes and modifications to the technical solution of the present invention, or modify it into an equivalent embodiment with equivalent changes, without departing from the scope of the technical solution of the present invention, which does not affect the essence of the present invention. Therefore, any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A liquid nitrogen delivery pipeline externally connected with a vacuum maintenance jump pipe. The liquid nitrogen delivery pipeline includes two double-layer hollow pipelines connected by a flange. Each double-layer hollow pipeline is provided with an inner wall and an outer wall. The inner cavity of the inner wall is used for delivering liquid nitrogen, and the outer cavity between the inner and outer walls is a vacuum insulation cavity. The inner cavities of the two double-layer hollow pipelines are communicated with each other, and a sealing end cover is connected between the inner and outer walls of the double-layer hollow pipelines near one end of the flange, and the outer cavities of the double-layer hollow pipelines at both ends of the flange are isolated by the sealing end cover. It is characterized in that, the inner wall of the first double-layer hollow pipeline is recessed inward in the axial direction, and the inner wall of the second double-layer hollow pipeline extends outward in the axial direction and passes through the flange and extends into the interior of the first double-layer hollow pipeline. The sealing end cover is L-shaped; first interfaces and second interfaces respectively connected to their outer cavities are opened on the outer walls of the two double-layer hollow pipelines. A vacuum maintenance jump pipe is connected between the first interface and the second interface. The vacuum maintenance jump pipe is a three-way pipe, and the three interfaces of the three-way pipe are connected to the first interface, the second interface and a vacuum maintenance system respectively. Manual valves are respectively arranged on the first interface and the second interface.

2. The liquid nitrogen delivery pipeline with a vacuum-maintaining jump connection pipe externally connected as described in claim 1, characterized in that, The contact end faces of the two double-layer hollow pipelines are provided with mutually fitting steps.

3. The liquid nitrogen delivery pipeline with a vacuum-maintaining jump connection pipe externally connected as described in claim 1, wherein The vacuum maintenance jump pipe includes a metal bellows body, and two of the interfaces of the metal bellows body are respectively connected to the first interface and the second interface through straight pipe joints.

4. The liquid nitrogen delivery pipeline externally connected with a vacuum maintenance jump pipe as claimed in claim 1, characterized in that, A sealing ring groove is provided on the sealing end cover of the second double-layer hollow pipeline extending into the interior of the first double-layer hollow pipeline, and a sealing ring is installed in the sealing ring groove.

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