Valve device for vacuum double piping and its maintenance method

Abstract

To provide a valve device for a vacuum double pipe having an improved workability in maintenance while reducing size.SOLUTION: A valve device 10 used for a vacuum double pipe 8 in which a vacuum layer 6 is formed between an inner pipe 2 in which a low-temperature fluid flows and an outer pipe 4 covering the inner pipe 2, includes a valve box 12, a valve body 16, a maintenance hole 18, a maintenance cover 20, and a jacket member 22. An inner space of the jacket member 22 is formed around the valve box 12 and partitioned to form an operation chamber 24 and a non-operation chamber 26. The operation chamber 24 stores the maintenance cover 20 therein, and is closed in an opened / closed manner by an operation cover 28 such that an opening and closing operation of the maintenance cover 20 is available from the outside. A vacuum communication flow path 32 having an open / close valve 30 communicates the operation chamber 24 and the non-operation chamber 26.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a valve device for a vacuum double pipe and a maintenance 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. As a conventional valve device used for a vacuum double pipe, Patent Document 1 discloses a configuration including a valve box 51 connected to an inner pipe 61 of a vacuum double pipe 60, a maintenance hole 52 formed on the downstream side in the flow direction F of the valve box 51, and a maintenance cover 53 for opening and closing the maintenance hole 52, as shown in FIG. 4.

[0003] In the vacuum layer 62 of the vacuum double pipe 60, an isolation part 65 is formed between partition members 64a and 64b provided on the upstream side and the downstream side of the valve box 51, respectively, and the isolation part 65 can communicate with other parts of the vacuum layer 62 through bypass flow paths 67a and 67b provided with on-off valves 66a and 66b.

[0004] The directly upper part 68 of the maintenance hole 52 in the outer pipe 63 of the vacuum double pipe 60 is configured to be removable. During maintenance, after closing the on-off valves 66a and 66b of the bypass flow paths 67a and 67b to block the isolation part 65 from other parts of the vacuum layer 62, the directly upper part 68 of the maintenance hole 52 can be removed, enabling the maintenance cover 53 to be opened and closed.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in the configuration disclosed in Patent Document 1, the entire valve body 51 is covered by a cylindrical outer tube 63, which means that the diameter of the outer tube 63 becomes too large relative to the size of the valve body 51, potentially leading to an overall large configuration.

[0007] Furthermore, as the diameter of the outer tube 63 increases, the volume of the isolation section 65 also increases. This means that a wide area is vacuum-broken during maintenance, making it difficult to restore the entire isolation section 65 to a vacuum state after maintenance is complete. Therefore, there was room for improvement in terms of maintenance efficiency.

[0008] Therefore, the present invention aims to provide a valve device for vacuum double piping and a maintenance method thereof that improves the workability of maintenance while achieving miniaturization. [Means for solving the problem]

[0009] The object of the present invention is achieved by a valve device for use in a vacuum double-walled piping system in which a vacuum layer is formed between an inner pipe through which a low-temperature fluid flows and an outer pipe covering the inner pipe, comprising: a valve body connected to the inner pipe through which a low-temperature fluid passes; a valve element provided inside the valve body for opening and closing the flow path of the inner pipe by driving a valve shaft; a maintenance hole formed in the valve body for performing maintenance inside the valve body; a maintenance cover that can open and close the maintenance hole; and a jacket member connected to the outer pipe that covers the valve body, wherein the jacket member has an internal space formed around the valve body that is partitioned to form an operating chamber and a non-operating chamber, the operating chamber houses the maintenance cover and can be closed and opened and closed by an operating cover so that the maintenance cover can be opened and closed from the outside, and the operating chamber and the non-operating chamber are connected by a vacuum connecting flow path equipped with an on / off valve.

[0010] In this vacuum double-pipe valve device, the jacket member preferably comprises a cylindrical portion connected to the outer pipe and a rectangular tubular portion rising from the outer circumferential surface of the cylindrical portion, the operating chamber preferably formed inside the rectangular tubular portion and the non-operating chamber preferably formed inside the cylindrical portion.

[0011] Furthermore, it is preferable to further include an external communication passage that connects the control room to the outside, and a vacuum release valve that can open and close the external communication passage.

[0012] The valve stem can be inserted through a cylindrical insertion portion protruding from the valve body, and the operating chamber can accommodate a portion of the insertion portion.

[0013] Furthermore, the above-mentioned objective of the present invention is achieved by a maintenance method for a vacuum double-pipe valve device, which includes the steps of closing the on-off valve and then opening the operating cover to perform the opening and closing operation of the maintenance cover, from a state in which the operating chamber and the non-operating chamber are maintained under vacuum by evacuating the inside of the vacuum layer with the on-off valve open. [Effects of the Invention]

[0014] According to the present invention, a valve device for vacuum double piping and its maintenance method can be miniaturized while improving the workability of maintenance. [Brief explanation of the drawing]

[0015] [Figure 1] This is a cross-sectional view of a valve device for vacuum double piping according to one embodiment of the present invention. [Figure 2] This is a cross-sectional view AA in Figure 1. [Figure 3] This is a cross-sectional view of a vacuum double piping valve device according to another embodiment of the present invention. [Figure 4] This is a cross-sectional view of a conventional valve device for vacuum double piping. [Modes for carrying out the invention]

[0016] Hereinafter, one embodiment of the present invention will be described with reference to the attached drawings. Figure 1 is a cross-sectional view of a vacuum double-walled piping valve device according to one embodiment of the present invention, and Figure 2 is a cross-sectional view of AA in Figure 1. The vacuum double-walled piping valve device (hereinafter simply referred to as "valve device") 10 shown in Figures 1 and 2 is a welded butterfly valve, and vacuum double-walled pipes 8, 8 are connected by welding to the upstream and downstream sides of the low-temperature fluid flow direction F, respectively. The connection between the vacuum double-walled pipes 8 and the valve device 10 is not limited to a welded type, but may also be a flange connection or the like. The application of the valve device 10 is not particularly limited, but it can be used, for example, for marine applications.

[0017] The vacuum double-walled piping 8 comprises an inner tube 2 and an outer tube 4 made of a metal material such as stainless steel. In this embodiment, a cryogenic fluid such as liquefied hydrogen, liquefied ammonia, liquefied helium, liquefied nitrogen, or liquefied oxygen passes through the inside of the inner tube 2 in the direction indicated by arrow F. The flow direction of the cryogenic fluid may be in the opposite direction to the direction indicated by arrow F.

[0018] The outer tube 4 is positioned concentrically with the inner tube 2 so as to cover it, and a vacuum layer 6 is formed between the inner tube 2 and the outer tube 4. The vacuum layer 6 is evacuated by a vacuum pump (not shown) to vacuum-insulate the inner tube 2.

[0019] The valve device 10 comprises a cylindrical valve body 12 connected to the inner pipe 2 through which a low-temperature fluid passes; a valve element 16 provided inside the valve body 12 that opens and closes the flow path of the inner pipe 2 when driven by a valve stem 14; a maintenance hole 18 formed downstream of the valve element 16 in the valve body 12; a maintenance cover 20 that can open and close the maintenance hole 18; and a jacket member 22 connected to the outer pipe 4 that covers the entire valve body 12. The valve stem 14 is rotatably inserted into a cylindrical insertion portion 13 that protrudes upward from the valve body 12, which is arranged so that the flow path is horizontal.

[0020] The maintenance hole 18 is a rectangular opening formed at the tip of a square tube-shaped portion protruding upward from the upper part of the valve box 12, and is closable by a maintenance cover 20. The maintenance cover 20 is a rectangular flat plate-shaped member, and is detachably fastened to the peripheral edge of the maintenance hole 18 by fasteners 19 such as bolts and nuts arranged along the peripheral edge.

[0021] The jacket member 22 includes a cylindrical portion 221 extending horizontally so as to be connected to the outer tube 4, a square tube-shaped portion 223 standing upright upward from the outer peripheral surface of the cylindrical portion 221 and having an open upper end, a flange portion 224 formed along the upper edge of the square tube-shaped portion 223, and a rectangular flat plate-shaped operation cover 28 detachably attached to the flange portion 224 by a plurality of fasteners 29.

[0022] A first opening 222 that opens into the square tube-shaped portion 223 is formed in the peripheral wall of the cylindrical portion 221. The peripheral edge of the maintenance hole 18 is fitted into the first opening 222, and the entire circumference is joined by welding.

[0023] With the jacket member 22 having the above-described configuration, the internal space formed around the valve box 12 inside the jacket member 22 is partitioned by a partition portion 23 that is part of the peripheral wall of the cylindrical portion 221, an operation chamber 24 is formed inside the square tube-shaped portion 223, and a non-operation chamber 26 is formed inside the cylindrical portion 221. The maintenance cover 20 that can open and close the maintenance hole 18 is housed in the operation chamber 24, and by opening the operation cover 28 that can open and close the operation chamber 24, the opening and closing operation of the maintenance cover 20 can be performed from the outside.

[0024] As shown in Figure 2, the control chamber 24 and the non-control chamber 26 are connected to each other by a vacuum connecting passage 32 equipped with an on-off valve 30. Furthermore, an external communication passage 34 is connected to the control cover 28, which connects the inside of the control chamber 24 to the outside, and a vacuum breaking valve 36 is provided in the external communication passage 34. The vacuum connecting passage 32 and the external communication passage 34 are formed, for example, by piping, but their configuration and arrangement are not particularly limited.

[0025] Upstream of the first opening 222 in the peripheral wall of the cylindrical portion 221, a second opening 225 is formed in an upwardly bulging portion. The insertion portion 13 is fitted into the second opening 225, and the entire circumference is joined by welding.

[0026] In the valve device 10 having the above configuration, the operating chamber 24 and non-operating chamber 26 of the jacket member 22 are maintained in a vacuum state by opening the on-off valve 30 and closing the vacuum-breaking valve 36, thereby evacuating the inside of the vacuum layer 6 of the vacuum double piping 8. This allows the entire area around the valve body 12 through which the low-temperature fluid flows to be vacuum-insulated.

[0027] The maintenance method for the valve device 10 may include a step in which the operator opens and closes the on / off valve 30 and opens the vacuum breaking valve 36 to break the vacuum only in the operating chamber 24, and then opens the operating cover 28 to allow the operator to open and close the maintenance cover 20. Since the non-operating chamber 26 is kept under vacuum, it is preferable to improve the thermal insulation between the operating chamber 24 and the non-operating chamber 26 by installing thermal insulation material in the partition 23, etc.

[0028] After the maintenance work is completed, the maintenance cover 20 and the operation cover 28 are closed, and then the vacuum release valve 36 is closed and the on / off valve 30 is opened, thereby evacuating the control chamber 24 through the non-operation chamber 26, allowing for normal operation.

[0029] Thus, with the valve device 10 of this embodiment, maintenance work can be performed by opening and closing the maintenance cover 20 by only creating a vacuum break in the minimum space consisting of the operating chamber 24. Therefore, there is no risk of the vacuum break being extensive as in the conventional method, and the efficiency of maintenance can be improved.

[0030] Furthermore, by forming the control chamber 24 to match the position and shape of the maintenance cover 20, the jacket member 22 does not need to cover the entire valve body 12 in a cylindrical shape, thus enabling miniaturization of the jacket member 22.

[0031] 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 maintenance cover 20 is housed in the operating chamber 24, while a part of the insertion portion 13 through which the valve stem 12 is inserted is housed in the non-operating chamber 26. However, as shown in the valve device 10' in Figure 3, a part of the insertion portion 13 may be housed in the operating chamber 24. The upper part of the operating chamber 24 is covered by an upper wall 226, and an opening that is opened and closed by the operating cover 28 and an opening through which the insertion portion 13 is inserted can be formed in this upper wall 226. Note that in Figure 3, the same reference numerals are used for components that are the same as those in Figure 1.

[0032] According to the valve device 10' shown in Figure 3, the internal space of the control chamber 24 is slightly increased, while a portion of the insertion section 13 is integrally housed in the control chamber 24 together with the maintenance cover 20. This makes it easier to manufacture the jacket member 22 and reduces costs. [Explanation of symbols]

[0033] 2 Inner tube 4 Outer tube 6 vacuum layer 8 Vacuum double piping 10. Valve device for vacuum double piping 12 valve boxes 13 Insertion part 14 Valve stem 16 Valve body 18 Maintenance Hole 20 Maintenance cover 22 Jacket components 221 Cylindrical part 223 Square tubular part 23 Partition 24 Control room 26 Non-control room 28. Operating cover 30 Shut-off valves 32 Vacuum connection pipe 34 External communication path 36 Vacuum Breaking Valve

Claims

1. A valve device 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, A valve body connected to the inner pipe through which a low-temperature fluid passes, A valve body provided within the valve casing opens and closes the flow path of the inner tube by the drive of the valve stem, A maintenance hole formed in the valve body for performing maintenance inside the valve body, A maintenance cover that can open and close the aforementioned maintenance hole, The valve comprises a jacket member connected to the outer pipe and covering the valve body, The jacket member has an internal space formed around the valve body that is partitioned to form an operating chamber and a non-operating chamber. The control room houses the maintenance cover and is closed by an operating cover so that the maintenance cover can be opened and closed from the outside. A valve device for vacuum double piping, in which the operating chamber and the non-operating chamber are connected by a vacuum connecting passage equipped with an on / off valve.

2. The jacket member comprises a cylindrical portion connected to the outer tube and a rectangular tubular portion rising from the outer circumferential surface of the cylindrical portion. The valve device for vacuum double piping according to claim 1, wherein the operating chamber is formed inside the rectangular tubular portion, and the non-operating chamber is formed inside the cylindrical portion.

3. The valve device for vacuum double piping according to claim 1, further comprising an external communication passage that connects the control chamber to the outside, and a vacuum breaking valve that can open and close the external communication passage.

4. The valve stem is inserted through a cylindrical insertion portion that protrudes from the valve body. The valve device for vacuum double piping according to claim 1, wherein the operating chamber accommodates a part of the insertion portion.

5. A maintenance method for a vacuum double piping valve device according to any one of claims 1 to 4, A maintenance method for a valve device for vacuum double piping, comprising the steps of closing the on-off valve, opening the operating cover, and then performing the opening and closing operation of the maintenance cover, from a state in which the operating chamber and the non-operating chamber are maintained under vacuum by evacuating the inside of the vacuum layer with the on-off valve open.

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