A pipe connection structure for double-layer spherical tank and double-layer spherical tank

Abstract

The present invention discloses a pipe connection structure for a double-layer spherical tank and a double-layer spherical tank, and relates to the technical field of low-temperature storage equipment. The pipe connection structure includes an inner tank body, an outer tank body, a liquid inlet and outlet pipe, and a flexible connector. One end of the liquid inlet and outlet pipe is connected to the inner tank body, and the other end extends out of the avoidance hole on the outer tank body. The flexible connector is arranged between the liquid inlet and outlet pipe and the avoidance hole, and its inner and outer wall surfaces are respectively fixedly connected to the outer tube wall of the liquid inlet and outlet pipe and the inner hole wall of the avoidance hole. The flexible connector includes a plurality of sleeves that are sleeved outside the liquid inlet and outlet pipe and are sequentially spaced from the inside to the outside. The plurality of sleeves are connected to form a connection structure with a square wave-shaped cross-section along the axial direction of the liquid inlet and outlet pipe, and at least one sleeve is also provided with a displacement compensation section. Through this structure, the heat conduction at the connection between the liquid inlet and outlet pipe and the outer tank body can be effectively reduced, and the displacement change at this location can be compensated, and the structure is simple and reliable.

Description

Technical Field

[0001] The invention relates to the technical field of low-temperature storage equipment, and in particular to a pipe connection structure for a double-layer spherical tank and the double-layer spherical tank. Background Art

[0002] Cryogenic medium refers to liquefied gas with a boiling point below -20°C, such as liquefied ethylene, liquefied natural gas, liquid oxygen, liquid argon, liquid nitrogen, liquid hydrogen, etc. Cryogenic medium is generally liquefied from normal temperature gas for easy storage and transportation. In view of the characteristics of cryogenic medium, its storage equipment must have good insulation performance. Double-layer spherical tanks, as a cryogenic storage equipment, are widely used in the storage of cryogenic liquefied gas media. Since double-layer spherical tanks can be stored under pressure, there is no need to set up cryogenic pumps, which is conducive to reducing investment costs and operating costs.

[0003] The liquid inlet and outlet pipes of a double-layer spherical tank need to pass through the tank wall of the outer tank body when leading out from the inner tank body and be connected to the external pipeline. When the liquid inlet and outlet pipes are connected to the outer tank body, the structure of the connection part must at least meet the following requirements: first, reduce the heat conduction of the connection part, and second, compensate for the displacement change caused by the temperature difference. At present, in order to achieve this goal, a vacuum tube connection structure is often used. However, this connection structure has very high requirements for vacuum extraction. Once a failure occurs, its functions will fail and the reliability is low. In addition, since the connection structure is relatively complex, all related structures including the liquid inlet and outlet pipes need to be replaced as a whole when it fails, which will undoubtedly greatly increase the economic cost and time cost.

[0004] Based on this, there is an urgent need for a pipe connection structure for a double-layer spherical tank and a double-layer spherical tank to solve the above problems. Summary of the invention

[0005] The purpose of the present invention is to provide a pipe connection structure for a double-layer spherical tank and a double-layer spherical tank, which can effectively reduce the heat conduction between the liquid inlet and outlet pipes and the outer tank body, and compensate for the displacement changes of the connection parts of the liquid inlet and outlet pipes and the outer tank body. The structure is simple and reliable.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] A pipe connection structure for a double-layer spherical tank comprises an inner tank body and an outer tank body, and further comprises:

[0008] A liquid inlet and outlet pipe, one end of which is connected to the inner tank body, and the other end of which extends out of the avoidance hole on the outer tank body;

[0009] A flexible connector is arranged between the liquid inlet and outlet pipe and the avoidance hole, the inner wall surface and the outer wall surface of the flexible connector are fixedly connected to the outer tube wall of the liquid inlet and outlet pipe and the inner hole wall of the avoidance hole respectively, the flexible connector includes a plurality of sleeves sleeved outside the liquid inlet and outlet pipe, the plurality of sleeves are arranged in sequence from the inside to the outside of the liquid inlet and outlet pipe and are connected to each other to form a connection structure with a square wave-shaped cross-section along the axial direction of the liquid inlet and outlet pipe, and at least one of the sleeves is also provided with a displacement compensation section.

[0010] Optionally, the flexible connector is configured as a thin-walled structure.

[0011] Optionally, the displacement compensation section is arranged between the inner tank body and the outer tank body.

[0012] Optionally, the displacement compensation section is a bellows.

[0013] Optionally, the plurality of sleeves, the flexible connector and the liquid inlet and outlet pipe, and the flexible connector and the outer tank body are all connected by welding.

[0014] Optionally, a first thermal insulation layer is provided outside the flexible connector.

[0015] Optionally, the flexible connector includes a first ring plate, a first sleeve, a second ring plate, a second sleeve, a third ring plate and a third sleeve which are arranged in sequence from the inside to the outside of the liquid inlet and outlet pipe and are connected to each other.

[0016] The present invention also provides a double-layer spherical tank, comprising the above-mentioned pipe connection structure for the double-layer spherical tank.

[0017] Optionally, the outer surface of the inner tank body and the inner surface of the outer tank body are respectively coated with a second thermal insulation layer and a third thermal insulation layer.

[0018] Optionally, the second insulation layer comprises a vacuum insulation layer and a first PIR insulation layer arranged sequentially from the inside to the outside on the outer surface of the inner tank body; and / or

[0019] The third thermal insulation layer includes a second PIR insulation layer.

[0020] Beneficial effects of the present invention:

[0021] The present invention provides a pipe connection structure for a double-layer spherical tank and a double-layer spherical tank. In the pipe connection structure for a double-layer spherical tank, a flexible connector for connecting a liquid inlet and outlet pipe and an outer tank body is provided, and a plurality of sleeves are provided in the flexible connector, so that the plurality of sleeves are connected in sequence to form a connection structure with a square wave-shaped cross-section along the axial direction of the liquid inlet and outlet pipe, which can greatly extend the heat transfer length between the liquid inlet and outlet pipe and the outer tank body, and effectively reduce the heat conduction between the liquid inlet and outlet pipe and the outer tank body. At the same time, since a displacement compensation section is provided in at least one sleeve, the displacement change of the connection part between the liquid inlet and outlet pipe and the outer tank body can be compensated. This connection structure is simple to set up, does not rely on vacuum means, and has high reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural schematic diagram of a pipe connection structure for a double-layer spherical tank provided by an embodiment of the present invention;

[0023] Figure 2 It is a schematic diagram of the overall structure of a double-layer spherical tank provided by an embodiment of the present invention.

[0024] In the figure:

[0025] 1. Inner tank body; 2. Outer tank body; 3. Liquid inlet and outlet pipes; 4. Flexible connector; 41. First ring plate; 42. First sleeve; 43. Second ring plate; 44. Second sleeve; 45. Displacement compensation section; 46. Third ring plate; 47. Third sleeve; 5. Reinforcement ring; 6. First insulation layer; 7. Second insulation layer; 71. Vacuum insulation layer; 72. First PIR insulation layer; 8. Third insulation layer; 9. Pillar; 91. Upper pillar; 92. Middle pillar; 93. Lower pillar; 10. Pull rod. DETAILED DESCRIPTION

[0026] In order to make the technical problem solved by the present invention, the technical solution adopted and the technical effect achieved more clearly, the technical solution of the present invention is further explained below with reference to the accompanying drawings and through specific implementation methods.

[0027] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0029] In the description of this embodiment, the terms "upper", "lower", "left", "right" and other directions or positional relationships are based on the directions or positional relationships shown in the drawings, and are only for the convenience of description and simplification of operation, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operate in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used to distinguish in the description and have no special meaning.

[0030] This embodiment provides a pipe connection structure for a double-layer spherical tank. Figure 1 As shown, the pipe connection structure for the double-layer spherical tank includes an inner tank body 1, an outer tank body 2, a liquid inlet and outlet pipe 3 and a flexible connector 4. Specifically, one end of the liquid inlet and outlet pipe 3 is connected to the inner tank body 1, and the other end extends out of the avoidance hole set on the outer tank body 2. The flexible connector 4 is arranged between the liquid inlet and outlet pipe 3 and the avoidance hole, and the inner wall surface and the outer wall surface of the flexible connector 4 are respectively fixedly connected to the outer tube wall of the liquid inlet and outlet pipe 3 and the inner hole wall of the avoidance hole. The flexible connector 4 includes a plurality of sleeves sleeved outside the liquid inlet and outlet pipe 3, and the plurality of sleeves are sequentially arranged from the inside to the outside of the liquid inlet and outlet pipe 3 and connected to each other to form a connection structure with a square wave cross section along the axial direction of the liquid inlet and outlet pipe 3, thereby greatly extending the heat transfer length between the liquid inlet and outlet pipe 3 and the outer tank body 2, and effectively reducing the heat conduction between the liquid inlet and outlet pipe 3 and the outer tank body 2. At the same time, since at least one sleeve is also provided with a displacement compensation section 45, the displacement change of the connection part between the liquid inlet and outlet pipe 3 and the outer tank body 2 can be compensated. It can be seen that the overall arrangement of the double-layer spherical tank pipe connection structure is simple, does not rely on vacuum means, and has high reliability. In this embodiment, the liquid inlet and outlet pipe 3 extends out of the avoidance hole on the outer tank body 2 and is connected to the external process pipeline.

[0031] Specifically, from the heat conductivity formula of solid materials Q = λ·A·ΔT / L, it can be known that the heat conductivity Q is proportional to the average thermal conductivity λ of the material, the heat transfer area A, and the temperature difference ΔT at both ends of the component, and is inversely proportional to the heat transfer length L of the component. In this embodiment, Figure 1As shown, on a plane parallel to the axial direction of the liquid inlet and outlet pipe 3, the length of the flexible connector 4 along the heat transfer path between the outer tank body 2 and the liquid inlet and outlet pipe 3 represents the heat transfer length L between the liquid inlet and outlet pipe 3 and the outer tank body 2. Therefore, when other parameters remain unchanged, the heat conduction between the liquid inlet and outlet pipe 3 and the outer tank body 2 can be effectively reduced by increasing the length of the flexible connector 4 along the heat transfer path.

[0032] Furthermore, the flexible connector 4 can be configured as a thin-walled structure. According to this configuration, the wall thickness of the flexible connector 4 can be much smaller than its length, so as to reduce the cross-sectional area (i.e., the heat transfer area A) of the flexible connector 4, thereby further effectively reducing the heat transfer between the liquid inlet and outlet pipe 3 and the outer tank body 2.

[0033] Alternatively, if Figure 1 As shown, the displacement compensation section 45 is arranged between the inner tank body 1 and the outer tank body 2, so that the outer tank body 2 can be used to shield the displacement compensation section 45, thereby preventing the displacement compensation section 45 from being exposed to the open air environment and being accidentally damaged, thereby further improving the reliability of the overall structure.

[0034] like Figure 1 As shown, in this embodiment, in terms of specific structure, the flexible connector 4 includes a first sleeve 42, a second sleeve 44 and a third sleeve 47 which are arranged in sequence from the inside to the outside of the liquid inlet and outlet pipe 3. The displacement compensation section 45 is arranged in the middle of the second sleeve 44. In this embodiment, the displacement compensation section 45 is a bellows. The bellows is made of stainless steel sheet, and its two ends are respectively fixedly connected to two straight pipe sections to form the second sleeve 44. The axial displacement and radial displacement caused by the temperature difference at the connection part between the liquid inlet and outlet pipe 3 and the outer tank body 2 can be compensated by the section of the bellows in the second sleeve 44. When in use, the axial displacement and radial displacement to be compensated can be calculated according to the actual application of the double-layer spherical tank, and then the bellows can be designed according to the displacement to be compensated to meet the displacement compensation requirements.

[0035] Furthermore, since the sleeves constituting the flexible connector 4 are all straight tubes, a plurality of ring plates are also provided in the flexible connector 4 to achieve a sealed connection between two adjacent sleeves and between the sleeves and the liquid inlet and outlet pipes 3. Specifically, Figure 1 As shown, a first ring plate 41 is provided in the flexible connector 4 to connect the outer wall of the liquid inlet and outlet pipe 3 and the first sleeve 42, a second ring plate 43 is provided to connect the first sleeve 42 and the second sleeve 44, and a third ring plate 46 is provided to connect the second sleeve 44 and the third sleeve 47. It can be understood that in order to reduce the heat transfer area of ​​the flexible connector 4, the sleeve, ring plate and bellows in this embodiment are all made of thin plates.

[0036] Optionally, multiple sleeves, the flexible connector 4 and the liquid inlet and outlet pipe 3, and the flexible connector 4 and the outer tank body 2 are all welded to ensure the strength of the structure. More specifically, the ring plate and the liquid inlet and outlet pipe 3, the sleeve and the ring plate, the straight pipe section in the sleeve 44 and the displacement compensation section 44, and the sleeve and the outer tank body 2 are all parts that need to be welded. During the manufacturing process, non-destructive testing and leakage testing are also required for the weld parts to ensure the airtightness of the structure. In addition, if Figure 1 As shown, a reinforcing ring 5 is further provided at the connection portion between the third sleeve 47 and the outer tank body 2 to further enhance the structural strength of the avoidance hole portion.

[0037] Of course, it should be noted that any parts and connecting parts in the pipe connection structure for the double-layer spherical tank should be accurately designed according to the design pressure, geometric dimensions and pipeline specifications of the double-layer spherical tank before welding to ensure that the strength and sealing of the overall structure meet the theoretical requirements.

[0038] Optionally, a first insulation layer 6 is provided outside the flexible connector 4. The first insulation layer 6 is made of an insulating material and can effectively reduce the heat leakage at the flexible connector 4. Since the temperature difference is greater at the part closer to the liquid inlet and outlet pipes 3, Figure 1 As shown, in this embodiment, the heat insulating material is coated on the outside of the liquid inlet and outlet pipe 3, the first ring plate 41 and the first sleeve 42. Of course, in other embodiments, the heat insulating material can also be coated on other parts of the flexible connector 4 to achieve complete coating of the flexible connector 4 and minimize the heat leakage at the flexible connector 4.

[0039] In summary, in the pipe connection structure for the double-layer spherical tank provided in this embodiment, a flexible connector 4 is provided to connect the liquid inlet and outlet pipe 3 and the outer tank body 2, and a plurality of sleeves are provided in the flexible connector 4, so that the plurality of sleeves are connected in sequence to form a connection structure with a square wave cross section along the axial direction of the liquid inlet and outlet pipe 3, which can greatly extend the heat transfer length and effectively reduce the heat conduction between the liquid inlet and outlet pipe 3 and the outer tank body 2. At the same time, since a displacement compensation section 45 is provided in at least one sleeve, the displacement change of the connection part between the liquid inlet and outlet pipe 3 and the outer tank body 2 can be compensated. The flexible connector 4 can also be set as a thin-walled structure to reduce the heat transfer area and further reduce the heat conduction between the liquid inlet and outlet pipe 3 and the outer tank body 2.

[0040] like Figure 2 As shown, this embodiment also provides a double-layer spherical tank, including the pipe connection structure for the double-layer spherical tank as described above.

[0041] Optionally, the inner tank body 1 is a steel spherical tank body, adopting an orange segment type or a mixed type spherical shell structure. A plurality of pillars 9 are evenly distributed along the equator of the inner tank body 1 to support the inner tank body 1. The material of the inner tank body 1 is low temperature resistant steel (including but not limited to austenitic stainless steel and nickel steel) that can withstand low temperatures.

[0042] Like the inner tank 1, the outer tank 2 is also a steel spherical tank, adopting an orange segment or mixed spherical shell structure, and the sphere center of the outer tank 2 coincides with that of the inner tank 1. At the same time, the outer tank 2 is fixedly connected to the support 9. It should be noted that when designing the size and structure of the outer tank 2, the load effects of wind load, snow load, earthquake load, auxiliary ladder platform and other structures on the outer tank 2 need to be considered.

[0043] Optionally, taking into account processing capabilities, transportation conditions, etc., a large-sized petal structure should be used as much as possible during tank manufacturing to reduce the overall weld length and reduce on-site installation work.

[0044] Furthermore, considering that the upper end of the support 9 is fixedly connected to the inner tank body 1, and the lower end is arranged through the outer tank body 2, part of its structure is located between the inner tank body 1 and the outer tank body 2, so Figure 2 As shown, in this embodiment, the support 9 is set to a segmented structure so that the support 9 can not only play a supporting role, but also meet the insulation requirements of the spherical tank. Specifically, the support 9 is divided into three parts from top to bottom: an upper support 91, a middle support 92 and a lower support 93. Among them, the upper support 91 and the middle support 92 are both arranged between the inner tank body 1 and the outer tank body 2. The upper end of the upper support 91 is fixedly connected to the inner tank body 1, and an insulating layer is arranged on the outer surface of the upper support 91 to reduce heat leakage. The middle support 92 is set as a horizontal plane centripetal sliding structure for displacement compensation to avoid shrinkage caused by the temperature difference between the inner tank body 1 and the outer tank body 2 and cause the support 9 to be damaged. Optionally, the middle support 92 is made of pressure-bearing insulation material (including but not limited to glass fiber reinforced plastic). The lower support 93 is fixedly connected to the outer tank body 2 and is arranged through the outer tank body 2, and the lower end of the lower support 93 is fixed on the foundation. The lower support 93 can be made of a material having properties close to those of the outer tank 2 for ease of manufacture. In this embodiment, the support 9 is made of a finished steel pipe or a rolled steel plate pipe.

[0045] Furthermore, if Figure 2As shown, a tie rod 10 is also provided between two adjacent pillars 9 to increase the stability of the overall structure. In this embodiment, each tie rod 10 is configured as an adjustable structure. During use, the tightness of the tie rod 10 can be adjusted according to actual conditions to improve the stress condition of the tie rod 10 and ensure the safety and stability of the double-layer spherical tank during operation. Specifically, the tie rod 10 is divided into two sections, long and short. Among them, the upper part of the tie rod 10 is the long section, and the lower part of the tie rod 10 is the short section. The long section and the short section are connected by an adjustable nut (the position of the adjustable nut should be set to facilitate operation), so that the tightness of the tie rod 10 can be adjusted by the adjustable nut.

[0046] In this embodiment, in order to ensure the thermal insulation performance of the double-layer spherical tank, a certain arrangement is also made for the sandwich structure between the inner tank body 1 and the outer tank body 2.

[0047] Alternatively, if Figure 2 As shown, the outer surface of the inner tank body 1 and the inner surface of the outer tank body 2 are respectively coated with a second insulation layer 7 and a third insulation layer 8 to improve the thermal insulation performance of the double-layer spherical tank. There is a vacuum layer between the second insulation layer 7 and the third insulation layer 8, that is, the second insulation layer 7 and the third insulation layer 8 are vacuumized to further improve the thermal insulation performance. Of course, the provision of the vacuum layer is also conducive to reducing the total weight of the double-layer spherical tank.

[0048] In this embodiment, the total width of the interlayer between the inner tank body 1 and the outer tank body 2 is 0.6m-1.2m. Of course, in other embodiments, spherical tank interlayers of other structures or sizes may also be provided. However, it should be noted that the interlayer structure of the double-layer spherical tank should always be reasonably designed according to the characteristics such as the boiling point of the storage medium in the tank and the requirements of thermal insulation performance, and avoid the situation of waste of resources caused by excessive design.

[0049] Optionally, the second insulation layer 7 includes a vacuum insulation layer 71 and a first PIR insulation layer 72 which are sequentially arranged from the inside to the outside on the outer surface of the inner tank body 1. The vacuum insulation layer 71 is made of a vacuum insulation panel (Vacuum Insulation Panel, VIP), and the vacuum insulation panel and PIR (Polyisocyanurate Foam) are prefabricated into spherical shell-shaped small pieces for easy installation. Further, the outer surface of the inner tank body 1 and the inner surface of the vacuum insulation layer 71 and the outer surface of the vacuum insulation layer 71 and the inner surface of the first PIR insulation layer 72 are bonded by a low-temperature resistant adhesive. At the same time, a fixed structure made of a low-temperature resistant elastic material is also tied on the outer surface of the first PIR insulation layer 72 to prevent the second insulation layer 7 from falling off, further enhancing the reliability of the structure. The composite insulation structure can effectively eliminate the heat transfer caused by gas convection and heat conduction, greatly improve the insulation effect of the double-layer spherical tank, reduce the loss of low-temperature medium, and reduce the investment and maintenance costs of equipment.

[0050] In addition, it should be noted that since the thermal conductivity of the vacuum insulation panel is only about one tenth of the thermal conductivity of expanded perlite, when ensuring the same insulation effect, the provision of the vacuum insulation layer 71 can greatly reduce the amount of insulation material used, thereby effectively reducing the total weight of the equipment and being more conducive to the safe operation of the equipment.

[0051] Optionally, the third insulation layer 8 coated on the inner surface of the outer tank body 2 includes a second PIR insulation layer. However, unlike the first PIR insulation layer 72, the third insulation layer 8 is constructed by on-site spraying or patching, that is, the PIR is evenly covered on the inner surface of the outer tank body 2 by spraying or patching. The third insulation layer 8 can ensure that the equipment has the ability to cope with complex environmental conditions, effectively reduce the impact of the external environment (such as solar radiation, fire, etc.) on the insulation of the double-layer spherical tank, and make the double-layer spherical tank have a lower evaporation.

[0052] In short, the double-layer spherical tank provided in this embodiment has a reliable structure, good insulation performance, stable operation, and a wide range of applicable storage media. It can be used to store a variety of low-temperature media such as liquefied ethylene, liquefied natural gas, liquid oxygen, liquid argon, liquid nitrogen and liquid hydrogen, and has extremely high economy, practicality and safety.

[0053] The above contents are only preferred embodiments of the present invention. For ordinary technicians in this field, according to the concept of the present invention, there will be changes in the specific implementation methods and application scopes. The content of this specification should not be understood as limiting the present invention.

Claims

1. A pipe connection structure for a double-layer spherical tank, comprising an inner tank body (1) and an outer tank body (2), characterized in that: Also includes: a liquid inlet and outlet pipe (3), one end of the liquid inlet and outlet pipe (3) being in communication with the inner tank body (1), and the other end of the liquid inlet and outlet pipe (3) extending out of a relief hole on the outer tank body (2); A flexible connector (4) is arranged between the liquid inlet and outlet pipe (3) and the avoidance hole, the inner wall surface and the outer wall surface of the flexible connector (4) being fixedly connected to the outer tube wall of the liquid inlet and outlet pipe (3) and the inner hole wall of the avoidance hole respectively, the flexible connector (4) comprising a plurality of sleeves sleeved outside the liquid inlet and outlet pipe (3), the plurality of sleeves being arranged in sequence from the inside to the outside of the liquid inlet and outlet pipe (3) and being connected to each other to form a connection structure having a square wave-shaped cross section along the axial direction of the liquid inlet and outlet pipe (3), and at least one of the sleeves is further provided with a displacement compensation section (45); The flexible connection member (4) comprises a first ring plate (41), a first sleeve (42), a second ring plate (43), a second sleeve (44), a third ring plate (46) and a third sleeve (47) which are arranged in sequence from the inside to the outside of the liquid inlet and outlet pipe (3) and are connected to each other; The displacement compensation section (45) is arranged between the inner tank body (1) and the outer tank body (2).

2. The pipe connection structure for a double-layer spherical tank according to claim 1 is characterized in that: The flexible connecting piece (4) is configured as a thin-wall structure.

3. The pipe connection structure for a double-layer spherical tank according to claim 1 is characterized in that: The displacement compensation section (45) is a bellows.

4. The pipe connection structure for a double-layer spherical tank according to claim 1 is characterized in that: The plurality of sleeves, the flexible connector (4) and the liquid inlet and outlet pipe (3), and the flexible connector (4) and the outer tank body (2) are all connected by welding.

5. The pipe connection structure for a double-layer spherical tank according to claim 1 is characterized in that: A first thermal insulation layer (6) is arranged outside the flexible connecting piece (4).

6. A double-layer spherical tank, characterized in that: It comprises a pipe connection structure for a double-layer spherical tank as described in any one of claims 1 to 5.

7. The double-layer spherical tank according to claim 6, characterized in that: The outer surface of the inner tank body (1) and the inner surface of the outer tank body (2) are respectively coated with a second thermal insulation layer (7) and a third thermal insulation layer (8).

8. The double-layer spherical tank according to claim 7, characterized in that: The second thermal insulation layer (7) comprises a vacuum thermal insulation layer (71) and a first PIR thermal insulation layer (72) which are arranged in sequence from the inside to the outside of the outer surface of the inner tank body (1); and / or The third thermal insulation layer (8) comprises a second PIR insulation layer.

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