Neck tube for ultra-low temperature storage tank

Abstract

The present invention relates to a neck tube for ultra-low temperature storage tanks, and belongs to the technical field of thermal insulation design of cryogenic containers. The neck tube includes an outer joint with a closed cover that is sealed and fixedly connected to the outer shell of the storage tank, and an inner cylinder that is sealed and fixedly connected to the inner liner of the storage tank; the inner end of the inner cylinder is closed, and is sealed and fixedly connected to the inner end circumference of the inner tube located in the inner cylinder, the inner tube extends out of the outer section of the inner cylinder, inserts the inner support tube whose axis intersects with it, and is sealed and fixedly connected, one end of the inner support tube is sealed and fixedly connected to the outer end of the outer support tube that is empty sleeved outside it; the inner end of the outer support tube penetrates into the inner section of the inner tube adjacent to the inner tube that is empty sleeved outside the inner tube, and is sealed and fixedly connected; the outer end of the inner tube is fixedly connected to the inner end of the outer joint through a non-metallic spacer. The present invention makes the thermal insulation effect of the ultra-low temperature storage tank very ideal, and can effectively meet the needs of long-term storage of ultra-low temperature media.

Description

Technical Field

[0001] The invention relates to a neck tube for an ultra-low temperature storage tank, in particular to a neck tube structure for a small vertical liquid hydrogen storage tank, and belongs to the technical field of thermal insulation design of low temperature containers. Background Art

[0002] In heat transfer, a high vacuum environment can effectively avoid convective heat transfer, and multi-layer aluminum foil composite layers or multi-layer cold screens can effectively reduce radiation heat leakage. Therefore, high vacuum multi-layer (multi-screen) insulation is often used in low-temperature vacuum insulation structures. However, since the inner and outer containers of the low-temperature vacuum insulation tank need to be connected to each other with the help of a support similar to a neck tube structure, solid heat conduction is inevitable. In order to minimize heat conduction, the support structure should have a low thermal conductivity, strong low temperature resistance, and a sufficiently long thermal bridge.

[0003] Figure 1 It is a neck tube structure supported between the inner liner 5 and the outer shell 10 of a conventional low-temperature vacuum insulated storage tank, wherein the inner cylinder 2 welded to the inner liner 5 is fixedly connected to the closing cover 12 welded to the outer joint 11 of the outer shell 10 through the inner tube 16. In order to minimize heat conduction, the improvement Figure 2 The core innovation of the neck tube structure of the prior art is to divide the original integral inner tube 16 into two sections, inner and outer sections, and to add a non-metallic insulating tube 16' with low thermal conductivity in between.

[0004] With the need to store ultra-low temperature media such as liquid hydrogen and liquid helium with a temperature below -196°C, it is difficult to meet the requirements by applying the above existing technologies to ultra-low temperature storage. The reason is that the length of the thermal bridge is limited to the distance between the inner tank and the outer shell, which is very limited; the second is that the connection structure of the neck tube produces tensile and compressive stresses, which cannot bear the shear stress of the weld under excessive cold shrinkage, and has poor fatigue resistance and a short service life. This is especially true for small ultra-low temperature vacuum insulated storage tanks. Summary of the invention

[0005] The purpose of the present invention is to address the problems existing in the above-mentioned prior art and, through structural improvement, propose a neck tube for an ultra-low temperature storage tank that properly solves the problem of thermal bridge limitation and eliminates the shear stress problem, thereby further significantly improving the insulation effect and enabling the vacuum storage tank to effectively meet the needs of long-term storage of ultra-low temperature media.

[0006] In order to achieve the above-mentioned purpose, the basic technical scheme of the neck tube for ultra-low temperature storage tanks of the present invention is: comprising an outer joint with a closed cover which is sealed and fixedly connected to the outer shell of the storage tank, and an inner cylinder which is sealed and fixedly connected to the inner liner of the storage tank;

[0007] The inner end of the inner cylinder is closed and is sealed and fixedly connected to the inner end circumference of the inner tube located in the inner cylinder. The inner tube extends out of the outer section of the inner cylinder and penetrates the inner support cylinder whose axis intersects with it and is sealed and fixedly connected. One end of the inner support cylinder is sealed and fixedly connected to the outer end of the outer support cylinder that is hollowly sleeved outside it.

[0008] The inner end of the outer support tube is inserted into the inner tube sleeved outside the inner tube and is sealed and fixedly connected to the inner section of the inner tube;

[0009] The outer end of the inner pipe is fixedly connected to the inner end of the outer joint through a non-metallic spacer.

[0010] After adopting the present invention, not only the neck tube thermal bridge supported between the storage tank shell and the inner liner has a non-metallic isolation link, but also the thermal bridge passes through the inner cylinder body - inner tube - inner support tube - outer support tube - inner tube - spacer - outer joint, and the length is much longer than the vacuum interlayer spacing between the storage tank shell and the inner liner, and the inner cylinder body and the inner tube as well as the inner support tube and the outer support tube respectively form a maze structure in two directions; in addition, the inner support tube structure in which the axis intersects with the inner tube breaks through the original connection structure of the neck tube in the direction of only tensile and compressive stress, and can effectively eliminate the shear stress through the strain generated by the inner and outer support tubes, so that the thermal insulation effect of the ultra-low temperature storage tank using the present invention is very ideal, which can effectively meet the needs of long-term storage of ultra-low temperature media.

[0011] A further improvement of the present invention is that at least one fin is radially extended from the portion of the inner tube between the inner cylinder and the outer support cylinder, thereby forming a cold shield structure.

[0012] A further improvement of the present invention is that the inner end of the inner cylinder is sealed and fixedly connected to the inner head through the inner end of the connecting ring by sealing welding.

[0013] A further improvement of the present invention is that the inner end of the inner cylinder is sealed and fixedly connected to the inner end circumference of the inner tube in the inner cylinder through the outer end of the connecting ring. In this way, the connecting ring plays a three-piece connection role, the process is convenient, and the structure is reliable.

[0014] A further improvement of the present invention is that one end of the inner support tube is sealed and fixedly connected to the outer end of the outer support tube which is hollowly sleeved outside of the inner support tube through a U-shaped ring. Thus, by means of the horizontal inner and outer support tubes forming a labyrinth tube, the neck tube thermal bridge can be extended as much as possible in a limited space to reduce heat leakage.

[0015] A further improvement of the present invention is that the outer end of the inner pipe is connected to the inner end of the outer joint by means of a glass fiber reinforced plastic insulation pad and a fastener of the outer glass fiber reinforced plastic insulation sleeve. This structure can not only reduce heat leakage, but also the glass fiber reinforced plastic insulation sleeve and the glass fiber reinforced plastic insulation pad are subjected to compressive stress, and the weight of the inner tank is borne by fasteners such as stainless steel bolts, which can also reduce the difficulty of processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural diagram of a traditional cryogenic storage tank.

[0017] Figure 2 It is a structural schematic diagram of a cryogenic storage tank in the prior art.

[0018] Figure 3 It is a structural diagram of embodiment 1 of the present invention.

[0019] Figure 4 yes Figure 3 Schematic diagram of the three-dimensional exploded structure of an embodiment.

[0020] Figure 5 It is a structural diagram of embodiment 2 of the present invention.

[0021] Figure 6 It is a structural diagram of embodiment 3 of the present invention. DETAILED DESCRIPTION

[0022] Embodiment 1

[0023] The small vertical liquid hydrogen storage tank of this embodiment uses a neck tube such as Figure 3 and Figure 4 As shown, it includes an outer joint 11 with a closing cover 12 which is sealed and welded to the outer shell 10 of the liquid hydrogen storage tank, and an inner cylinder 2 which is sealed and welded to the inner liner 5 of the liquid hydrogen storage tank.

[0024] The inner end of the inner cylinder 2 is sealed and fixedly connected to the elliptical inner head 1 through the inner end of the connecting ring 3 by sealing welding, and the outer end of the connecting ring 3 is sealed and fixedly connected to the inner end circumference of the inner tube 4 located in the inner cylinder 2 by sealing welding.

[0025] The inner tube 4 extends out of the outer section of the inner cylinder 2 and penetrates the inner support cylinder 9 whose axis intersects perpendicularly therewith and is sealed and welded fixedly connected. One end of the inner support cylinder 9 is sealed and welded fixedly connected to the outer end of the outer support cylinder 8 which is hollowly sleeved outside it by U-shaped ring 7. Three fins 6 are radially extended from the portion of the inner tube 4 between the inner cylinder 2 and the outer support cylinder 8.

[0026] The inner end of the outer support tube 8 is inserted into the inner tube 16 which is hollowly sleeved outside the inner tube 4 and is sealed and welded to the inner section of the inner tube 4. The outer end ring of the inner tube 16 is fixed to the inner end of the outer joint 11 through the glass fiber reinforced plastic isolation pad 15 as a non-metallic spacer and with the help of the fastener 13 of the outer glass fiber reinforced plastic insulation sleeve pad 14.

[0027] The connection between the neck tube and the inner liner of this embodiment forms an air-cooled tube structure of the head, which can use the coldness of the low-temperature medium to form an air-cooled cavity to cool the root of the neck tube during operation. The fins form a cold shield structure connected to the neck tube, so that the insulation layer forms a multi-layer cold shield. The labyrinth tube formed by the horizontal inner and outer support tubes can lengthen the neck tube thermal bridge as much as possible in a limited space to reduce heat leakage. The connection between the neck tube and the outer shell can reliably form a vacuum interlayer.

[0028] Experiments show that this embodiment has the following advantages:

[0029] 1) Effectively improve the thermal insulation performance and neck strength of small vertical ultra-low temperature vacuum insulated storage tanks, and properly solve the problems of easy frost, condensation or local low temperature.

[0030] 2) By rationally adding transverse labyrinth tube structures, the pure tensile stress of the tank body on the neck tube is converted into the bending stress of the horizontal cantilever beam, maximizing the use of the interlayer space, lengthening the neck tube thermal bridge, and reducing heat leakage.

[0031] 3) With the help of fiberglass isolation pads and thermal insulation sleeves, not only the thermal conduction "broken bridge" between metal components is achieved, but also the thermal insulation pads and thermal insulation sleeves basically do not bear tensile stress and shear stress, and the stress state is good.

[0032] Embodiment 2

[0033] The storage tank neck tube of this embodiment is as follows Figure 5 As shown, its basic structure is the same as that of the first embodiment, except that: the inner tube extends out of the outer section of the inner cylinder 2, penetrates the inner support cylinder 9 whose axis obliquely intersects with it, and is sealed and welded to be fixed.

[0034] Embodiment 3

[0035] The storage tank neck tube of this embodiment is as follows Figure 6 As shown, its basic structure is the same as that of the first embodiment, except that the inner support tube 9 and the outer support tube 8 are both conical tubes with a larger outer side and a smaller inner side.

[0036] In addition to the above embodiments, the present invention may also have other implementations. For example, the inner head may also be an elliptical head or a flat cover installed in reverse; for another example, when the inner tank is heavy, considering that the horizontal heat transfer of the thermal bridge will cause a large bending moment in the neck tube, the labyrinth tube formed by the inner and outer support tubes may be arranged symmetrically on the left and right or at multiple points in the circumference to offset the bending moment; and so on. Any technical solution formed by equivalent replacement or equivalent transformation falls within the protection scope of the invention.

Claims

1. A neck tube for a cryogenic storage tank, comprising an outer joint (11) with a closure cover (12) which is sealed and fixedly connected to a storage tank shell (10), and an inner cylinder (2) which is sealed and fixedly connected to a storage tank liner (5); the characteristics are: The inner end of the inner cylinder (2) is sealed and fixedly connected to the inner end circumference of the inner tube (4) located in the inner cylinder; the inner tube (4) extends out of the outer section of the inner cylinder (2) and penetrates the inner support cylinder (9) whose axis intersects with the inner cylinder (2) and is fixedly connected to the inner support cylinder (9); one end of the inner support cylinder (9) is fixedly connected to the outer end of the outer support cylinder (8) which is hollowly sleeved outside the inner support cylinder (9); The inner end of the outer support tube (8) passes through an inner tube (16) which is hollowly sleeved outside the inner tube (4) and is adjacent to the inner section of the inner tube (4), and is sealed and fixedly connected to the inner section; The outer end of the inner pipe (16) is fixedly connected to the inner end of the outer joint (11) via a non-metallic spacer (15).

2. The neck tube for ultra-low temperature storage tank according to claim 1, characterized in that: At least one fin radially extends from a portion of the inner tube between the inner cylinder and the outer support cylinder.

3. The neck tube for ultra-low temperature storage tank according to claim 2, characterized in that: The inner end of the inner cylinder is sealed and fixedly connected to the inner head by sealing and welding through the inner end of the connecting ring.

4. The neck tube for ultra-low temperature storage tank according to claim 3, characterized in that: The inner end of the inner cylinder is sealed and fixedly connected to the inner end circumference of the inner tube located in the inner cylinder through the outer end of the connecting ring.

5. The neck tube for ultra-low temperature storage tank according to claim 4, characterized in that: One end of the inner support tube is fixedly connected to the outer end of the outer support tube which is hollowly sleeved outside of the inner support tube through a U-shaped ring seal.

6. The neck tube for ultra-low temperature storage tank according to claim 5, characterized in that: The outer end of the inner pipe passes through a glass fiber reinforced plastic isolation pad and is fixedly connected to the inner end of the outer joint by means of a fastener of the outer glass fiber reinforced plastic insulation sleeve pad.

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