Valve unit for vacuum double-walled piping and its connection method

Abstract

This invention provides a vacuum double-walled piping valve unit that ensures airtightness within the housing covering the valve body while maintaining the ease of maintenance of the valve body, using an inexpensive configuration. [Solution] A valve unit 1 used in a vacuum double-walled piping system in which a vacuum layer is formed between an inner tube and an outer tube, comprising a valve body 10, a housing 20 covering the valve body 10, and connecting pipes 2 and 3 connected to the downstream and upstream sides of the valve body 10, wherein the connecting pipes 2 and 3 have first flange portions 2a and 3a on their outer circumference, and the inner tube can be welded to the ends protruding to the outside through first openings 23a and 24a of the housing 20, and the housing 20 can be sealed by welding the first flange portions 2a and 3a to the peripheral edges of the first openings 23a and 24a, thereby maintaining a vacuum state inside.

Description

Technical Field

[0005] ، , , , <00000s03> The present invention relates to a valve unit for a vacuum double pipe and a connection method thereof.

Background Art

[0002] In order to transport cryogenic fluids such as liquefied hydrogen, a vacuum double pipe is known in which an inner pipe through which the cryogenic fluid passes is covered with an outer pipe, and a vacuum layer is formed between the inner pipe and the outer pipe. Valve units used in vacuum double pipes are mainly known as welded types and flange types due to differences in connection structures. However, in applications such as for ships, the need for welded types has recently been increasing.

[0003] As a conventional welded valve unit, Patent Document 1 discloses a configuration in which a valve box having an openable maintenance hole is covered with a housing (jacket member). In this welded valve unit, the inner pipe is connected to the valve box by welding, and the outer pipe is connected to the housing by welding.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the above conventional welded valve unit, while each connection part of the valve box, the inner pipe, and the outer pipe has high dimensional accuracy, for the connection part of the housing, it is difficult to achieve sufficient dimensional accuracy mainly due to manufacturing cost issues, and there is a risk that welding of the outer pipe becomes difficult. Therefore, from the viewpoint of maintaining the vacuum state inside the housing with a simple configuration, there is still room for further improvement.

[0006] Therefore, the present invention aims to provide a valve unit for vacuum double piping and a connection method thereof that can ensure airtightness within the housing covering the valve body with an inexpensive configuration while maintaining the ease of maintenance of the valve body. [Means for solving the problem]

[0007] The object of the present invention is achieved by a valve unit for use in a vacuum double-walled piping system in which a vacuum layer is formed between an inner tube through which a low-temperature fluid flows and an outer tube covering the inner tube, the valve unit comprising a valve body, a housing covering the valve body, and a connecting pipe connected to the downstream and upstream sides of the valve body, wherein the valve body comprises a valve casing through which a low-temperature fluid passes, a valve element provided in the valve casing for opening and closing the flow path of the low-temperature fluid by driving a valve shaft, and a maintenance cover that can open and close a maintenance hole formed on the upper part of the valve casing, the housing having a first opening through which the connecting pipe is inserted and a second opening for opening and closing the maintenance cover from the outside, the second opening being covered by an operating cover that can open and close, the connecting pipe having a first flange portion on its outer circumference and the inner tube being weldable to the end protruding to the outside through the first opening, and the housing being sealed by welding the first flange portion to the periphery of the first opening, thereby maintaining a vacuum state inside.

[0008] In this vacuum double-walled piping valve unit, it is preferable that the first flange portion is welded to the inner surface of the housing.

[0009] If the portion of the valve stem protruding from the valve body is covered by a protective cylinder, the protective cylinder may have a second flange portion on its outer circumference and protrude to the outside through a third opening formed in the housing. The housing is sealed by welding the second flange portion to the periphery of the third opening.

[0010] Furthermore, the object of the present invention is achieved by a method for connecting the above-mentioned valve unit for vacuum double piping to a vacuum double piping system in which a vacuum layer is formed between an inner tube through which a low-temperature fluid flows and an outer tube covering the inner tube, comprising a connection step of connecting the connecting pipe to the inner tube by welding, and a covering step of covering the portion of the connecting pipe and the inner tube that is exposed to the outside after connection with a cylindrical connecting cover having both ends open, wherein the covering step comprises moving the connecting cover toward the valve unit for vacuum double piping from a state in which the outer tube is inserted inside, and sealing the inside of the connecting cover by connecting both ends of the connecting cover to the respective joints of the housing and the outer tube. [Effects of the Invention]

[0011] According to the present invention, a valve unit for vacuum double piping and its connection method can ensure airtightness within the housing covering the valve body with an inexpensive configuration, while maintaining the ease of maintenance of the valve body. [Brief explanation of the drawing]

[0012] [Figure 1] This is a schematic cross-sectional view of a valve unit for vacuum double piping according to one embodiment of the present invention. [Figure 2] Figure 1 is a side view of a valve unit for vacuum double piping. [Figure 3] Figure 1 is an exploded view of a valve unit for vacuum double piping. [Figure 4] Figure 1 is a process diagram illustrating the connection method for the valve unit for vacuum double piping. [Figure 5] This is a side view of a valve unit for vacuum double piping according to another embodiment of the present invention. [Figure 6] This is a side view of a valve unit for vacuum double piping according to yet another embodiment of the present invention. [Modes for carrying out the invention]

[0013] Hereinafter, one embodiment of the present invention will be described with reference to the attached drawings. Figure 1 is a schematic cross-sectional view of a vacuum double-walled piping valve unit according to one embodiment of the present invention, and Figure 2 is a side view of the vacuum double-walled piping valve unit shown in Figure 1, viewed in the direction of arrow A. The vacuum double-walled piping valve unit (hereinafter simply referred to as "valve unit") 1 shown in Figures 1 and 2 is a welded butterfly valve used in vacuum double-walled piping described later, and comprises a valve body 10, a housing 20 covering the valve body 10, and connecting pipes 2 and 3 connected to the downstream and upstream sides of the valve body 10. The use of the valve unit 1 is not particularly limited, but it can be suitably used, for example, in ships, to open and close the flow path of low-temperature fluids such as liquefied hydrogen, liquefied ammonia, liquefied helium, liquefied nitrogen, and liquefied oxygen.

[0014] The valve body 10 comprises a cylindrical valve casing 11 through which a low-temperature fluid passes, a valve element 13 provided within the valve casing 11 and driven by a valve stem 12 to open and close the flow path of the low-temperature fluid, and a maintenance cover 14 that can open and close a rectangular maintenance hole 11a formed on the upper part of the valve casing 11. The valve stem 12 is rotatably inserted into a cylindrical protective cylinder 15 that protrudes upward from the valve casing 11, which is arranged so that the flow path is horizontal. The maintenance cover 14 is a rectangular flat plate-shaped member and is fastened to the periphery of the maintenance hole 11a by a plurality of fasteners 18 such as bolts arranged along its periphery, thereby covering the maintenance hole 11a in an openable and closable manner.

[0015] The connecting pipes 2 and 3 are provided so as to extend horizontally from both the left and right sides of the valve body 11 shown in Figure 1. The base ends of the connecting pipes 2 and 3 are welded to the valve body 11 so as to communicate with the inside of the valve body 11. Near the center of the outer surface of the connecting pipes 2 and 3, ring-shaped first flange portions 2a and 3a are fixed by being welded all around at welds W1 and W2, respectively. The connecting pipes 2 and 3 do not necessarily have to be separate components from the valve body 11; the valve body 11 and the connecting pipes 2 and 3 may be integrally formed by machining or other means.

[0016] The housing 20 is formed in a rectangular parallelepiped shape, and four side plates 23, 24, 25, 26 are arranged and welded between the top plate 21 and the bottom plate 22. A vacuum drawing line 27 and a vacuum release line 28 each provided with an on-off valve are connected to the housing 20. The inside of the housing 20 can be evacuated to a vacuum state using the vacuum drawing line 27, and the vacuum state of the housing 20 can be released using the vacuum release line 28.

[0017] On the side plates 23, 24 facing each other on the downstream side and the upstream side of the valve box 11, first openings 23a, 24a through which the communication pipes 2, 3 are inserted with a gap are formed. The first flange portions 2a, 3a provided on the communication pipes 2, 3 are each in contact with the inner surfaces of the side plates 23, 24, and are welded along the opening edges of the first openings 23a, 24a at the welding portions W4, W5, so that the gaps between the communication pipes 2, 3 and the first openings 23a, 24 are sealed by the first flange portions 2a, 3a.

[0018] On the outer surfaces of the side plates 23, 24, ring-shaped coupling portions 23b, 24b used when connecting a cover for connecting a vacuum double pipe described later are provided. A plurality of mounting screw holes 23c, 24c are formed in the coupling portions 23b, 24b.

[0019]

[0020] On the top plate 21, a second opening 21a for opening and closing the maintenance cover 14 of the valve body 10 from the outside of the housing 20 and a third opening 21b through which the protective cylinder 15 of the valve body 10 is inserted with a gap are formed. The second opening 21a is covered in an openable and closable manner by an operation cover 21d via a packing 21c. The operation coverThe valve unit 1 having the above-described configuration can be manufactured easily and at low cost by assembling and covering the valve body 10 to which the communication pipes 2 and 3 are attached with the housing 20. The procedure for assembling the housing 20 is not particularly limited, but it can be performed, for example, by the following method.

[0021] That is, as shown in FIG. 3, first, the first flange portions 2a and 3a are welded to the communication pipes 2 and 3 connected to the valve box 11, and the second flange portion 15a is welded to the protective cylinder 15. The welding of the second flange portion 15a is performed in a state where the protective cylinder 15 is inserted in advance through the third opening 21b of the top plate 21.

[0022] Next, with the valve body 10 disposed above the bottom plate 22, the top plate 21 is moved in the direction of the arrow until it abuts against the second flange portion 15a, and the second flange portion 15a is welded to the top plate 21.

[0023] Then, the side plates 23 and 24 are moved in the direction of the arrow until they abut against the first flange portions 2a and 3a, respectively, the communication pipes 2 and 3 are inserted through the first openings and 24a, and then the side plates 23 and 24 are welded to the first flange portions 2a and 3a as well as to the top plate 21 and the bottom plate 22.

[0024] Finally, the remaining two side plates 25 and 26 (see FIG. 2) are welded to the top plate 21, the bottom plate 22, and the side plates 23 and 24, thereby obtaining a sealed housing 20.

[0025] Next, referring to FIG. 4, a method of connecting the valve unit 1 of the present embodiment to a vacuum double pipe will be described. As shown in FIG. 4, the vacuum double pipe 30 has an inner pipe 31 through which a low-temperature fluid flows and an outer pipe 32 that covers the inner pipe 31, which are concentrically arranged, and a vacuum layer 33 is formed between the inner pipe 31 and the outer pipe 32. The tip of the inner pipe 31 protrudes from the tip of the closed outer pipe 32 and is exposed to the outside. A ring-shaped coupling portion 32a for connecting a connection cover 40, which will be described later, is provided on the outer peripheral surface of the outer pipe 32. The vacuum layer 33 is evacuated by a vacuum pump (not shown) to thermally insulate the inner pipe 31.

[0026] The tip of the vacuum double-walled pipe 30 can be covered with a rectangular tubular connecting cover 40 that has openings at both ends. The peripheral edges of the openings at both ends of the connecting cover 40 are provided with ring-shaped flange portions 40a and 40b. One flange portion 40a is connected to the coupling portions 23b and 24b of the valve unit 1 by fasteners such as bolts (not shown), and the other flange portion 40b is connected to the coupling portion 32a of the outer pipe 32. This allows the inside of the connecting cover 40 to be sealed, and the inside can be made into a vacuum state by performing vacuum evacuation with a vacuum pump (not shown).

[0027] To connect the valve unit 1 to the vacuum double piping 30, first, as shown in Figure 4(a), the tip of the outer pipe 32 is inserted into the connecting cover 40, and the inner pipe 31 of the valve unit 1 is brought close to one of the connecting pipes 3 as indicated by the arrow, and the ends of the connecting pipe 3 and the inner pipe 31 are welded together. In this way, the connection process of connecting the connecting pipe 3 to the inner pipe 31 is performed.

[0028] Next, as shown in Figure 4(b), the connecting cover 40 is moved toward the valve unit 1 as indicated by the arrow. If the connecting cover 40 is large, it may be moved on a trolley (not shown). After this, the flange portions 40a and 40b at both ends of the connecting cover 40 are connected to the respective joint portions 24b and 32a of the housing 20 and outer pipe 32, thereby sealing the inside of the connecting cover 40 as shown in Figure 4(c). In this way, a covering process is performed in which the parts of the connecting pipe 3 and inner pipe 31 that are exposed to the outside after connection are covered with the connecting cover 40.

[0029] The vacuum double piping 30 can also be connected to the other connecting pipe 4 of the valve unit 1 using the same procedure as described above. After connecting the vacuum double piping 30 to the valve unit 1, as shown in Figure 4(d), the housing 20 and the connecting cover 40, and the connecting cover 40 and the vacuum layer 33 are connected by connection lines 34 and 35, respectively, thereby maintaining a vacuum state inside the housing 20 and the connecting cover 40 together with the vacuum layer 33.

[0030] Although one embodiment of the present invention has been described in detail above, the specific aspects of the present invention are not limited to the above embodiment. For example, in this embodiment, the first flange portions 2a and 3a of the connecting pipes 2 and 3 are welded to the inner surface of the housing 20 to facilitate the assembly of the housing 20, but it is also possible to weld the first flange portions 2a and 3a to the outer surface of the housing 20.

[0031] Furthermore, in this embodiment, the second flange portion 15a of the protective cylinder 15 is welded to the outer surface of the housing 20, but it may also be welded to the inner surface of the housing 20, or even better, the protective cylinder 15 may be welded directly to the opening edge of the third opening 21b without providing the second flange portion 15a.

[0032] Furthermore, although the housing 20 is formed in the shape of a rectangular parallelepiped in this embodiment, the shape of the housing 20 is not particularly limited. For example, as shown in the side view in Figure 5, a housing 20 can be constructed with a lower part that is arc-shaped in side view by welding curved side plates 25 and 26 together at the welding joint W10 without providing a bottom plate. The shape of the joint 24b may be formed to match the opening shape of the connecting cover 40 (see Figure 4), and may be formed in the shape of a rectangular frame, for example, as shown in Figure 6. Note that in Figures 5 and 6, the same reference numerals are used for components that are the same as those in Figure 2, etc. [Explanation of symbols]

[0033] 1. Valve unit for vacuum double-walled piping 2,3 Communication pipe 2a,3a First flange portion 10 Valve body 11 Valve box 11a Maintenance Hole 12 Valve stem 13 Valve body 14. Maintenance cover 15 Protective tube 15a Second flange portion 20 cabinets 21a Second opening 21b Third opening 21d Operating Cover 23a, 24a First opening 23b,24b joint part 30 Vacuum double piping 31 Inner tube 32 Outer tube 32a Joint part 40 Connection cover 40a, 40b Flange section

Claims

1. A valve unit used in a vacuum double-walled piping system in which a vacuum layer is formed between an inner tube through which a low-temperature fluid flows and an outer tube covering the inner tube, The device comprises a valve body, a housing covering the valve body, and connecting pipes connected to the downstream and upstream sides of the valve body. The valve body comprises a valve casing through which a low-temperature fluid passes, a valve element provided within the valve casing that opens and closes the flow path of the low-temperature fluid by the drive of a valve stem, and a maintenance cover that can open and close to cover a maintenance hole formed in the upper part of the valve casing. The housing has a first opening through which the connecting pipe is inserted and a second opening for opening and closing the maintenance cover from the outside, and the second opening is covered by an operating cover so as to be openable and closable. The connecting pipe has a first flange portion on its outer circumference, and the inner pipe can be welded to the end portion that protrudes to the outside through the first opening. The housing is sealed by welding the first flange portion to the periphery of the first opening, thereby maintaining a vacuum state inside, making it a valve unit for vacuum double piping.

2. The valve unit for vacuum double piping according to claim 1, wherein the first flange portion is welded to the inner surface of the housing.

3. The valve stem is covered by a protective tube in the portion that protrudes from the valve body. The protective cylinder has a second flange portion on its outer circumference and protrudes to the outside through a third opening formed in the housing. The valve unit for vacuum double piping according to claim 1, wherein the housing is sealed by welding the second flange portion to the periphery of the third opening.

4. A method for connecting the valve unit for vacuum double piping described in claim 1 to a vacuum double piping in which a vacuum layer is formed between an inner tube through which a low-temperature fluid flows and an outer tube covering the inner tube, A connection step of connecting the aforementioned connecting pipe to the aforementioned inner pipe by welding, The process includes a covering step in which the portion of the connecting pipe and the inner pipe that is exposed to the outside after connection is covered with a cylindrical connecting cover that has openings at both ends, A method for connecting a vacuum double-pipe valve unit, comprising the covering step of moving the connecting cover toward the vacuum double-pipe valve unit from a state in which the outer pipe is inserted inside, and sealing the inside of the connecting cover by connecting both ends of the connecting cover to the respective joints of the housing and the outer pipe.

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