Double tube connection structure

Abstract

To provide a double pipe connection structure which has a simple structure and is capable of easily exposing a connection part of an inner pipe and easily removing the inner pipe used for connection.SOLUTION: A double pipe connection structure includes: a cylindrical first outer pipe for connection disposed at a prescribed interval in an axial direction between an outer pipe on a fuel gas supply source side and an outer pipe on a combustion equipment side; at least one first inner pipe for connection disposed inside; a first connection member connecting the first outer pipe for connection and an outer pipe of a double pipe on the combustion equipment side or a second outer pipe for connection; and a second connection member connecting the first outer pipe for connection and the outer pipe of the double pipe on the fuel gas supply source side or the second outer pipe for connection. The second outer pipe for connection is a member which extends at least either the outer pipe of the double pipe on the fuel gas supply source side or the outer pipe of the double pipe on the combustion equipment side and is connectable to the first outer pipe for connection.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a double pipe connection structure for connecting double pipes. [Background technology]

[0002] Conventionally, when supplying fuel gas to a boiler located in a ship's engine room, the ClassNK's steel ship rules require that all fuel gas piping in the engine room be housed in a duct or double pipe. These ducts or double pipes are also required to be strong enough to withstand the internal fuel gas pressure. Therefore, when using double pipes, the fuel gas piping that supplies fuel gas to the boiler must be the inner pipe, and the inner pipe (fuel gas piping) must be a pressure-resistant double pipe with an outer pipe that completely encloses it. The double pipe on the ship side, where the fuel gas supply source is located, and the double pipe on the boiler side (combustion equipment side) are connected by a fitting or the like. Furthermore, such double pipes are also used, for example, in boilers that use ammonia as fuel gas, for the purpose of suppressing the effects of ammonia leakage on boiler operation (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-77011 Summary of the Invention [Problem to be solved by the invention]

[0004] In a boiler to which fuel gas is supplied through a double pipe, it may be necessary to remove the bolts at the flange connection part of the inner pipe for maintenance, etc. To avoid this, one possible method is to make the outer pipe at the connection part into, for example, a half-cylindrical shape so that the connection part of the inner pipe can be easily exposed. However, such a half-cylindrical outer pipe requires an axial seal in addition to a circumferential seal at the end where it connects to the ship or the double pipe of the combustion equipment, which makes the structure complex in order to meet the requirements for airtightness, pressure resistance, etc. In particular, in order for the half-cylindrical outer pipe to meet the strength requirement of being able to withstand pressures greater than the maximum operating pressure of the fuel gas flowing through the inner pipe, it requires high airtight sealing and a large number of bolts, etc.

[0005] Furthermore, when it comes to the connection part of a double pipe, for example, when removing a combustion equipment (burner), it is necessary to remove the inner pipe at the connection part, but if the positions of the connection part of the inner pipe and the connection part of the outer pipe in the axial direction of the double pipe are significantly different, there is a problem that the inner pipe may get caught on the outer pipe and cannot be easily removed. For the above reasons, there is a demand for a connection structure for connecting the double pipe on the ship side (fuel supply source side) with the double pipe on the boiler side (combustion equipment side), which has a simple configuration, allows the connection portion of the inner pipe connecting the two to be easily exposed, and allows the inner pipe connecting the two to be easily removed.

[0006] An object of the present invention is to provide a double pipe connection structure that has a simple configuration, allows the connection portion of the inner pipe to be easily exposed, and allows the inner pipe used for connection to be removed. [Means for solving the problem]

[0007] The present invention solves the above problems by the following means.

[0008] The double pipe connection structure of the present invention is a double pipe connection structure for connecting a fuel gas supply source and a combustion appliance, comprising an outer pipe and an inner pipe arranged inside the outer pipe and forming a ventilation flow path between the outer pipe and the inner pipe, and for connecting an end of the double pipe on the fuel gas supply source side to an end of the double pipe on the combustion appliance side, the double pipe connection structure comprising a cylindrical first connecting outer pipe arranged at a predetermined distance in the axial direction between the outer pipe of the double pipe on the fuel gas supply source side and the outer pipe of the double pipe on the combustion appliance side, at least one first connecting inner pipe arranged inside the first connecting outer pipe and connecting the inner pipe of the double pipe on the fuel gas supply source side to the inner pipe of the double pipe on the combustion appliance side, and a second connecting outer pipe arranged between the first connecting outer pipe and the outer pipe of the double pipe on the combustion appliance side or the first connecting outer pipe on the combustion appliance side. and a second connecting member connecting the first connecting outer pipe to the outer pipe of the double pipe on the fuel gas supply source side or a second connecting outer pipe arranged on the fuel gas supply source side of the first connecting outer pipe, wherein the second connecting outer pipe is a member that extends at least one of the outer pipe of the double pipe on the fuel gas supply source side and the outer pipe of the double pipe on the combustion equipment side toward the first connecting outer pipe to make it an outer pipe connectable to the first connecting outer pipe, and the first connecting member and the second connecting member comprise a cylindrical housing into which the first connecting outer pipe can be inserted, a tightening means for tightening the housing so as to reduce the inner diameter of the housing, and an elastic body arranged inside the housing and in close contact with the first connecting outer pipe.

[0009] The second connecting outer pipe has a cylindrical end on the first connecting outer pipe side and a flange portion on the end opposite the first connecting outer pipe, and it is preferable that the flange portion be flange-connected to the flange when at least one of the outer pipe at the second outer pipe end on the fuel gas supply source side and the outer pipe at the double pipe end on the combustion equipment side has a flange.

[0010] Preferably, the double pipe connection structure further comprises a second connecting inner pipe disposed inside the second connecting outer pipe.

[0011] The length of the first connecting outer pipe is preferably shorter than the total length of the first connecting inner pipe.

[0012] It is preferable that the length of the first connecting outer pipe is shorter than the total length of the first connecting inner pipe by at least a length equivalent to the bolt length of the bolt used when flange-connecting the first connecting inner pipe to the inner pipe on the combustion appliance side or the inner pipe on the fuel gas supply source side.

[0013] It is preferable that the second connecting inner pipe has a flange portion at least on the side of the first connecting inner pipe, and when the double pipe on the fuel gas supply source side and the double pipe on the combustion equipment side are connected by the double pipe connection structure, the end face of the second connecting outer pipe on the side of the first connecting outer pipe and the end face of the flange portion of the second connecting inner pipe that is flange-connected to the first connecting inner pipe are arranged on the same plane. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a double pipe connection structure that has a simple configuration, allows the connection portion of the inner pipe to be easily exposed, and allows the inner pipe used for connection to be removed. [Brief explanation of the drawings]

[0015] [Figure 1] 1A and 1B are diagrams illustrating a double pipe connection structure 1 according to a first embodiment. [Figure 2] 2 is a diagram illustrating a first connecting member 50 and a second connecting member 60. FIG. [Figure 3] 3A to 3C are diagrams illustrating a method for attaching the double pipe connection structure 1 of the first embodiment. [Figure 4] 3A to 3C are diagrams illustrating a method for attaching the double pipe connection structure 1 of the first embodiment. [Figure 5] 10A and 10B are diagrams illustrating a double pipe connection structure 2 according to a second embodiment. [Figure 6] 10A and 10B are diagrams illustrating a modified double pipe connection structure 3. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, embodiments of the present invention will be described with reference to the drawings, etc. Note that the drawings shown below, including Fig. 1, are schematic diagrams, and the size and shape of each part are appropriately exaggerated to facilitate understanding. In the following embodiments, the double pipe connection structure of the present invention will be described by taking an example in which it is used to supply fuel gas or the like from a fuel gas supply source to a combustion device (burner) provided in a boiler. Both the fuel gas supply source and the boiler are arranged on a ship, and the boiler is a steam boiler that burns fuel gas supplied from the fuel gas supply source as fuel using a burner to generate steam.

[0017] (First embodiment) FIG. 1 is a diagram illustrating a double pipe connection structure 1 according to a first embodiment. The double pipe connection structure 1 of the first embodiment is a connection structure for connecting a double pipe 80 on the fuel gas supply source side (hereinafter referred to as the double pipe 80 on the fuel gas supply source side) extending from a fuel gas supply source (not shown) to a double pipe 90 on the combustion appliance side (hereinafter referred to as the double pipe 90 on the combustion appliance side) extending from a combustion appliance (not shown). The double pipe comprises an outer pipe and an inner pipe placed inside the outer pipe. In this embodiment, the inner pipe forms a fuel gas flow path, and the outer pipe surrounds the inner pipe and forms a ventilation flow path between the inner pipe and the outer pipe. The ventilation flow path allows ventilation air to flow in the unlikely event that fuel gas flowing through the inner pipe leaks due to damage to the inner pipe, etc. In addition, in this embodiment, as an example, the double pipe connection structure 1 is used when, at the downstream end of the double pipe 80 on the fuel gas supply source side, the outer pipe 81 has a flange portion 811 at its downstream end, and the upstream end of the outer pipe 91 of the double pipe 90 on the combustion equipment side is cylindrical.

[0018] The double pipe 80 on the fuel gas supply source side comprises an outer pipe 81 and an inner pipe 82. The outer pipe 81 and the inner pipe 82 are cylindrical. The outer pipe 81 has a flange portion 811 at its downstream end (combustion appliance side), and the inner pipe 82 has a flange portion 821 at its downstream end. Furthermore, the end face of the flange portion 821 of the inner pipe 82 is located downstream (closer to the burner) than the end face of the flange portion 811 of the outer pipe 81 in the axial direction of the double pipe.

[0019] The double pipe 90 on the burner side comprises an outer pipe 91 and an inner pipe 92. The outer pipe 91 and the inner pipe 92 are cylindrical. The inner pipe 92 has a flange portion 921 at its upstream end (on the fuel gas supply source side), but the outer pipe 91 does not have a flange portion. Furthermore, the end face of the outer pipe 91 and the end face of the flange portion 921 of the inner pipe 92 are at the same position in the axial direction, and are arranged so that these end faces are located on the same plane. This allows the inner pipe (first connecting inner pipe 30, described later) of the double pipe connection structure 1 to be easily attached and detached by sliding it in any direction without getting caught on the outer pipe 91, when attaching or detaching a combustion appliance (not shown). Between the downstream end of the double pipe 80 and the upstream end of the double pipe 90, a gap is formed in the axial direction, in which the double pipe connection structure 1 can be disposed.

[0020] The fuel gas supplied from a fuel gas supply source (not shown) may be, for example, LNG, LPG, hydrogen gas, ammonia gas, ammonia decomposition gas, etc. In the present embodiment, the fuel gas supply source will be described by taking an example in which ammonia is supplied as the fuel gas.

[0021] The double pipe connection structure 1 of this embodiment comprises a first connecting outer pipe 10, a second connecting outer pipe 20, a first connecting inner pipe 30, a second connecting inner pipe 40, a first connecting member 50, a second connecting member 60, etc. The first connecting outer pipe 10 in this embodiment is a cylindrical member that is arranged at a predetermined distance in the axial direction between the second connecting outer pipe 20 connected to the end of the double pipe 80 on the fuel gas supply source side and the end of the double pipe 90 on the combustion equipment side. The first connecting outer pipe 10 is located upstream (toward the fuel gas supply source) of the double pipe 90 on the burner side, and is connected to the outer pipe 91 by a first connecting member 50. The outer diameter of the first connecting outer pipe 10 is the same as the outer diameter of the second connecting outer pipe 20 and the outer diameter of the outer pipe 91 of the double pipe 90 on the burner side.

[0022] The second connecting outer pipe 20 is a component that extends at least one of the outer pipe 81 on the fuel gas supply source side and the outer pipe 91 on the combustion equipment side toward the first connecting outer pipe 10 side to make it an outer pipe that can be connected to the first connecting outer pipe 10. The second connecting outer pipe 20 of this embodiment is a substantially cylindrical member having a flange portion 221 at its upstream end (fuel gas supply source side) and a cylindrical downstream end (burner side). The outer diameter of the downstream side (burner side) end of the second connecting outer pipe 20 is the same as that of the first connecting outer pipe 10. The outer pipe 81 and the second connecting outer pipe 20 are connected by fastening the flange portion 221 of the second connecting outer pipe 20 to the flange portion 811 of the double pipe 80 on the fuel gas supply source side with bolts or the like (not shown). Furthermore, the second connecting outer pipe 20 is connected to the first connecting outer pipe 10 by a second connecting member 60.

[0023] The first connecting outer pipe 10 and the second connecting outer pipe 20 are made of steel, but are not limited to this and may be made of stainless steel or synthetic resin such as polyvinyl chloride pipe, polyethylene pipe, etc. The material and thickness of the first connecting outer pipe 10 can be selected within a range that provides sufficient pressure resistance and airtightness as an outer pipe.

[0024] The first connecting inner pipe 30 is disposed inside the first connecting outer pipe 10, and is an inner pipe provided in at least one form to connect the end of the inner pipe 82 of the double pipe 80 on the fuel gas supply source side to the end of the inner pipe 92 of the double pipe 90 on the combustion appliance side. In this embodiment, an example in which one first connecting inner pipe 30 is provided will be described.

[0025] The first connecting inner pipe 30 has a substantially cylindrical shape and has flanges 311, 321 at both axial ends. The flange 311 provided at the downstream end (burner side) can be flange-connected to a flange 921 of the inner pipe 92 on the burner side, and the flange 321 provided at the upstream end (fuel gas supply source side) can be flange-connected to a flange 411 of the second connecting inner pipe 40, which will be described later. The first connecting inner pipe 30 and the inner pipe 92 are connected by flange connection between the flange portion 311 and a flange portion 921 of the inner pipe 92. Furthermore, the first connecting inner pipe 30 and the second connecting inner pipe 40 are connected by flange connection between the flange portion 321 and a flange portion 411 of the second connecting inner pipe 40 described below.

[0026] In addition, in the axial direction, the axial length of the first connecting outer pipe 10 is shorter than the length of this first connecting inner pipe 30, and is shorter by at least a length equivalent to the bolt length of the bolt (not shown) used when flange-connecting the first connecting inner pipe 30 to the inner pipe 92 on the combustion appliance side.

[0027] The second connecting inner pipe 40 has flanges 411, 421 at both axial ends. The flange 411 at the downstream end (combustion appliance side) can be flange-connected to the flange 321 of the first connecting inner pipe 30, and the flange 421 at the upstream end (fuel gas supply source side) can be flange-connected to the flange 821 of the inner pipe 82 on the fuel gas supply source side. The second connecting inner pipe 40 and the first connecting inner pipe 30 are connected by flange connection between the flange portion 411 and the flange portion 321 of the first connecting inner pipe 30. Furthermore, the second connecting inner pipe 40 and the inner pipe 82 are connected by flange connection between the flange portion 421 and the flange portion 821 of the inner pipe 82 on the fuel gas supply source side.

[0028] In this embodiment, the first connecting inner pipe 30 and the second connecting inner pipe 40 are made of steel, but the first connecting inner pipe 30 and the second connecting inner pipe 40 may be made of stainless steel, or may be made of synthetic resin such as polyvinyl chloride pipe or polyethylene pipe. The material, thickness, etc. of the first connecting inner pipe 30 and the second connecting inner pipe 40 can be selected within a range that provides sufficient pressure resistance and airtightness as inner pipes.

[0029] Fig. 2 is a diagram illustrating the first connecting member 50 and the second connecting member 60. Since the first connecting member 50 and the second connecting member 60 have the same shape, Fig. 2 shows the reference numerals of the respective parts of the first connecting member 50 and the second connecting member 60. In the following explanation, the first connecting member 50 will be taken as an example. The first connecting member 50 is a member, or so-called joint, that connects the end of the outer pipe 91 to the downstream (combustor side) end of the first connecting outer pipe 10 at the end of the double pipe 90 on the burner side. The first connecting member 50 preferably has a pressure resistance of up to about 1 MPa. The first connecting member 50 has a substantially cylindrical shape and an inner diameter larger than the outer diameter of the first connecting outer tube 10 and the outer diameter of the outer tube 91, allowing the first connecting outer tube 10 and the outer tube 91 to be inserted therein. The first connecting member 50 also has a housing 51, an elastic body 52 provided inside the housing 51, a fastening means 53 for fastening the housing 51, etc.

[0030] The housing 51 is a substantially cylindrical member that is partially discontinuous in the circumferential direction, and is a member into which the first connecting outer pipe 10 and the combustion appliance side outer pipe 91 can be inserted. The housing 51 is made of stainless steel, carbon steel, or the like. The elastic body 52 is a member that is disposed inside the housing and that comes into close contact with the outer peripheral surfaces of the first connecting outer tube 10 and the outer tube 91 that are inserted inside the first connecting member 50. The elastic body 52 is made of rubber such as EPDM or NBR.

[0031] The fastening means 53 fastens the housing 51 so as to reduce the inner diameter of the housing 51, and in this embodiment, the fastening means 53 includes two bolts 531, a rod-shaped nut 532, a rod-shaped washer 533, and support members 534, 535 for positioning these at predetermined positions on the outer peripheral surface of the housing 51. The rod-shaped nut 532 has screw holes formed at two positions along its axial direction to be threadedly engaged with the bolt 531. Note that the rod-shaped nut 532 is not limited to the rod-shaped nut 532, and a general-purpose nut may also be used. The rod-shaped washer 533 has holes formed at two locations along its axial direction, into which the bolt 531 can be inserted. Note that the rod-shaped washer 533 is not the only option, and a general-purpose washer may also be used.

[0032] The support members 534, 535 are provided to face the outer peripheral surface of both ends of the housing 51, which are discontinuous in the circumferential direction, and have openings formed at positions corresponding to the holes of the rod nut 532 and the rod washer 533. The support member 534 positions the rod washer 533 at a predetermined position on the outer peripheral surface of the housing 51 so that its axial direction is parallel to the axial direction of the housing 51. The support member 535 positions the rod nut 532 at a predetermined position on the outer peripheral surface of the housing 51 so that its axial direction is parallel to the axial direction of the housing 51.

[0033] The bolt 531 is inserted into a threaded hole of a rod-shaped nut 532 and a hole of a rod-shaped washer 533, which are supported by support members 534 and 535. The two bolts 531 are arranged in parallel with each other in the axial direction of the housing 51 with a predetermined gap therebetween.

[0034] The first connecting member 50 reduces the inner diameter of the housing 51 by tightening the two bolts 531 of the tightening means 53 so that the gap between the support members 534, 535 is parallel, thereby tightening the outer surfaces of the first connecting outer pipe 10 and the outer pipe 91 and tightly adhering to them, thereby connecting the first connecting outer pipe 10 and the outer pipe 91 with high airtightness.

[0035] The second connecting member 60 is a member that connects the downstream side (combustion appliance side) end of the second connecting outer pipe 20 and the upstream side (fuel gas supply source side) end of the first connecting outer pipe 10. The second connecting member 60 is a joint having the same shape as the first connecting member 50, and includes a housing 61, an elastic body 62, a fastening means 63, etc. The fastening means 63 includes two bolts 631, a rod-shaped nut 632, a rod-shaped washer 633, support members 634 and 635, etc. The second connecting member 60 has an inner diameter larger than the outer diameter of the second connecting outer pipe 20 and the outer diameter of the first connecting outer pipe 10, and the downstream end of the second connecting outer pipe 20 and the first connecting outer pipe 10 can be inserted inside it.

[0036] The second connecting member 60 reduces the inner diameter of the housing 61 by tightening the two bolts 631 of the tightening means 63, thereby tightening the outer surfaces of the second connecting outer pipe 20 and the first connecting outer pipe 10 and tightly adhering them, thereby connecting the second connecting outer pipe 20 and the first connecting outer pipe 10 with high airtightness. The shapes of the parts of the fastening means 53, 63 may be changed as appropriate.

[0037] 3 and 4 are diagrams illustrating a method for attaching the double pipe connection structure 1 of the first embodiment. For ease of understanding, the shapes of the various parts are appropriately simplified. 3(a), first, an operator places a gasket (not shown) between the flange portion 821 of the inner pipe 82 on the fuel gas supply source side and the flange portion 421 of the second connecting inner pipe 40, and then fastens the flange portions 421 and 821 with bolts and nuts (not shown). This completes a flange connection between the inner pipe 82 on the fuel gas supply source side and the second connecting inner pipe 40.

[0038] 3(b), the worker places a gasket (not shown) between the flange portion 221 of the second connecting outer pipe 20 and the flange portion 811 of the fuel gas supply source side outer pipe 81, and fastens the flange portion 221 to the flange portion 811 with bolts and nuts (not shown). This completes a flange connection between the second connecting outer pipe 20 and the fuel gas supply source side outer pipe 81. 3(b), the second connecting inner pipe 40 is positioned inside the second connecting outer pipe 20. The downstream end face of the second connecting outer pipe 20 and the end face of the flange portion 411 of the second connecting inner pipe 40 are at the same position in the axial direction, and these end faces are on the same plane. This allows the first connecting inner pipe 30 and the first connecting outer pipe 10 to be attached and detached by sliding them in any direction without getting caught on the second connecting outer pipe 20, when attaching or detaching a combustion appliance (not shown), and the first connecting inner pipe 30 can be easily attached and detached.

[0039] 3(c), the worker inserts the second connecting outer pipe 20 into the second connecting member 60 and attaches the second connecting member 60 to the second connecting outer pipe 20. At this time, the inner diameter of the second connecting member 60 is not reduced by the fastening means 63 and is larger than the outer diameter of the second connecting outer pipe 20, so the second connecting member 60 is located on the outer diameter side of the second connecting outer pipe 20 and is slidable in the axial direction. The worker moves the second connecting member 60 upstream and positions it in a position where the downstream flange portion 411 of the second connecting inner pipe 40 is sufficiently visible. Similarly, the worker attaches the first connecting member 50 to the outer pipe 91 on the combustion appliance side. At this time, the first connecting member 50 is located on the outer diameter side of the outer pipe 91 and is slidable in the axial direction. The worker moves the first connecting member 50 downstream and positions it in a position where the flange portion 921 of the inner pipe 92 can be fully seen.

[0040] Next, as shown in Figure 4(a), the worker places the first connecting inner pipe 30 and the first connecting outer pipe 10 between the second connecting inner pipe 40 and the second connecting outer pipe 20 and the double pipe 90 on the combustion appliance side. At this time, the first connecting inner pipe 30 is inserted inside the first connecting outer pipe 10 in advance.

[0041] 4(b), the worker shifts the first connecting outer pipe 10 upstream, places a gasket or the like (not shown) between the flange portion 311 of the first connecting inner pipe 30 and the flange portion 921 of the inner pipe 92 on the combustion appliance side, and fastens the flange portion 311 and the flange portion 921 with bolts and nuts (not shown). This completes the flange connection between the first connecting inner pipe 30 and the inner pipe 92. The axial length of the first connecting outer pipe 10 is shorter than the axial length of the first connecting inner pipe 30 by the length of the bolt used to flange-connect the first connecting inner pipe 30 to the inner pipe 92. Therefore, by shifting the first connecting outer pipe 10 upstream in the axial direction, the flange portion 311, which is the connection part of the first connecting inner pipe 30, can be easily exposed, ensuring sufficient working space and facilitating the insertion of the bolt into the hole in the flange portion and the tightening work.

[0042] As described above, the end face of the flange portion 921 of the inner pipe 92 and the end face of the outer pipe 91 are at the same position in the axial direction and these end faces are on the same plane, so the first connecting inner pipe 30 can be attached and detached by sliding it in any direction without getting caught on the outer pipe 91, making it easy to attach and detach the first connecting inner pipe 30 and improving the workability of the attachment and detachment work. Furthermore, when flange-connecting the first connecting inner pipe 30 and the inner pipe 92 on the combustion appliance side, it is easy to arrange a gasket and fasten with bolts.

[0043] Next, although not shown, the first connecting outer pipe 10 is shifted downstream, a gasket (not shown) is placed between the flange portion 321 at the upstream end of the first connecting inner pipe 30 and the flange portion 411 at the downstream end of the second connecting inner pipe 40, and the flange portion 321 and the flange portion 411 are fastened together with bolts and nuts (not shown). This completes a flange connection between the first connecting inner pipe 30 and the second connecting inner pipe 40. By shifting the first connecting outer pipe 10 downstream in the axial direction, the flange portion 321, which is the connection part of the first connecting inner pipe 30, can be easily exposed, ensuring sufficient working space and facilitating the insertion of bolts into holes in the flange portion and tightening work.

[0044] 4(c), the worker returns the first connecting outer pipe 10 to a position required for connection in the axial direction, and moves the first connecting member 50 upstream (towards the fuel gas supply source) along the axial direction, and places it in a position where it covers the end of the first connecting outer pipe 10 and the end of the outer pipe 91. At this time, a gap of a predetermined dimension is generated in the axial direction between the first connecting outer pipe 10 and the outer pipe 91, but this is smaller than the axial length of the first connecting member 50, and the first connecting member 50 sufficiently covers this gap. The worker then tightens the two bolts 531 of the tightening means 53 with a torque wrench or the like to reduce the inner diameter of the housing 51, and brings the elastic body 52 into close contact with the outer peripheral surface of the downstream end of the first connecting outer pipe 10 and the outer peripheral surface of the outer pipe 91. In this way, the first connecting member 50 connects the first connecting outer pipe 10 and the outer pipe 91.

[0045] The worker also moves the second connecting member 60 downstream (toward the combustion appliance) along the axial direction, and places it in a position where it covers the downstream end of the second connecting outer pipe 20 and the upstream end of the first connecting outer pipe 10. At this time, a gap of a predetermined dimension is generated in the axial direction between the second connecting outer pipe 20 and the first connecting outer pipe 10, but this gap is smaller than the axial length of the second connecting member 60, and the second connecting member 60 sufficiently covers this gap. The worker then tightens the two bolts 631 of the tightening means 63 with a torque wrench or the like to reduce the inner diameter of the housing 61, and brings the elastic body 62 into close contact with the outer peripheral surface of the downstream end of the second connecting outer pipe 20 and the outer peripheral surface of the upstream end of the first connecting outer pipe 10. In this way, the second connecting member 60 connects the second connecting outer pipe 20 and the first connecting outer pipe 10. In this way, as shown in Fig. 4(c), the end of the double pipe 80 on the fuel gas supply source side and the end of the double pipe 90 on the burner side are connected by the double pipe connection structure 1. When removing the double pipe connection structure 1, it can be easily removed by performing the above-mentioned steps in reverse order.

[0046] According to the double pipe connection structure 1 of this embodiment described above, the following effects can be achieved. (1) The double pipe connection structure 1 is a double pipe connection structure that connects an end of the double pipe 80 on the fuel gas supply source side to an end of the double pipe 90 on the combustion appliance side, and includes an outer pipe and an inner pipe that is disposed inside the outer pipe and forms a ventilation flow path between the outer pipe and the inner pipe. The double pipe connection structure connects a fuel gas supply source and a combustion appliance, and includes a cylindrical first connecting outer pipe 10 that is disposed with a predetermined distance in the axial direction between the outer pipe of the double pipe 80 on the fuel gas supply source side and the outer pipe of the double pipe 90 on the combustion appliance side, at least one first connecting inner pipe 30 that is disposed inside the first connecting outer pipe 10 and is used to connect the inner pipe of the double pipe 80 on the fuel gas supply source side to the inner pipe of the double pipe 90 on the combustion appliance side, and connects the first connecting outer pipe 10 to the outer pipe 91 of the double pipe 90 on the combustion appliance side or a second connecting outer pipe 20 that is disposed on the combustion appliance side of the first connecting outer pipe 10. and a second connecting member 60 that connects the outer pipe 81 of the double pipe 80 on the fuel gas supply source side or the second connecting outer pipe 20 that is arranged on the fuel gas supply source side of the first connecting outer pipe 10. The second connecting outer pipe 20 is a member that extends at least one of the outer pipe 81 of the double pipe 80 on the fuel gas supply source side or the outer pipe 91 of the double pipe 90 on the combustion appliance side toward the first connecting outer pipe 10 to form an outer pipe that can be connected to the first connecting outer pipe 10. The first connecting member 50 and the second connecting member 60 each comprise a cylindrical housing 51, 61 into which the first connecting outer pipe 10 can be inserted, tightening means 53, 63 that tighten the housing 51, 61 to reduce the inner diameter of the housing 51, 61, and elastic bodies 52, 62 that are arranged inside the housing 51, 61 and come into close contact with the first connecting outer pipe 10.

[0047] Therefore, the first connecting outer pipe 10 is arranged between the end of the double pipe 80 on the fuel gas supply source side and the end of the double pipe 90 on the combustion equipment side, with a predetermined axial gap between them, so that the connection portion of the inner pipe can be easily exposed by shifting the first connecting outer pipe 10 in the axial direction, facilitating the connection work. In addition, the first connecting member 50 and the second connecting member 60 have elastic bodies 52, 62 inside cylindrical housings 51, 61, and the housings 51, 61 are tightened with tightening means 53, 63 to fix the outer tube, making it possible to connect outer tubes positioned at a predetermined distance in the axial direction, facilitating installation and removal, and improving the workability of connecting double pipes. Furthermore, the first connecting member 50 and the second connecting member 60 can withstand a pressure of about 1 MPa, and can be used even when the pressure of the gas fuel is high. Furthermore, the first connecting outer pipe 10 and the second connecting outer pipe 20 are not in a half-cylindrical shape and do not have a connecting portion extending in the axial direction, so that the risk of leakage from the connecting portion in the axial direction can be reduced.

[0048] Furthermore, when the outer pipe 81 on the fuel gas supply source side has a flange portion 811 as in this embodiment, it can be extended toward the first connecting outer pipe 10 as a cylindrical outer pipe connectable to the first connecting outer pipe 10 by the second connecting outer pipe 20, and can be easily connected by appropriately adjusting the distance between the cylindrical ends of the two outer pipes using the second connecting member 60, etc. Similarly, when the outer pipe 91 on the combustion appliance side has a flange portion 921, it can be extended toward the first connecting outer pipe 10 as a cylindrical outer pipe connectable to the first connecting outer pipe 10 by the second connecting outer pipe 20, and can be easily connected using the second connecting member 60, etc.

[0049] (2) The second connecting outer pipe 20 has a cylindrical end on the first connecting outer pipe 10 side and a flange portion 221 on the end opposite the first connecting outer pipe 10, and the flange portion 221 is flange-connected to the flange of at least one of the outer pipe 81 of the double pipe 80 on the fuel gas supply source side and the outer pipe 91 of the double pipe 90 on the combustion equipment side when the outer pipe 81 has a flange. Therefore, even if the outer pipe 81 on the fuel gas supply source side or the outer pipe 91 on the combustion equipment side has a flange portion, the second connecting outer pipe 20 can be used to make the first connecting outer pipe 10 side cylindrical, and can be connected to the first connecting outer pipe 10 using the first connecting member 50 or the second connecting member 60, making it possible to easily connect the double pipe 90 on the combustion equipment side and the double pipe 80 on the combustion gas supply source side.

[0050] (3) The double pipe connection structure 1 further includes the second connecting inner pipe 40 disposed inside the second connecting outer pipe 20 . By providing the second connecting inner pipe 40, the fixing portion of the inner pipe can be extended to near the end face of the second connecting outer pipe 20 on the first connecting outer pipe 10 side, making fastening easier. Even if the downstream end of the outer pipe 81 on the fuel gas supply source side and the end face of the flange portion 821 of the inner pipe 82 are not on the same plane, by using the second connecting inner pipe 40, the end of the second connecting outer pipe 20 on the first connecting outer pipe 10 side and the end face of the flange portion 411 of the second connecting inner pipe 40 on the first connecting outer pipe 10 side can be made on the same plane, making fastening the first connecting inner pipe 30 and the first connecting outer pipe 10 easier. Furthermore, since the second connecting outer pipe 20 is removable, the flange portion 821 of the inner pipe 82 on the fuel gas supply source side and the flange portion 421 of the second connecting inner pipe 40 can be easily fastened together. In addition, by adjusting the lengths of the second connecting outer pipe 20 and the second connecting inner pipe 40, the connecting work of the first connecting outer pipe 10 and the first connecting inner pipe 30 can be performed while avoiding locations where work is difficult due to interference with other piping, for example.

[0051] (4) In the double pipe connection structure 1, the length of the first connecting outer pipe 10 is shorter than the total length of the first connecting inner pipe 30 (in this embodiment, the length of the first connecting inner pipe 30). Therefore, for example, when flange-connecting the first connecting inner pipe 30 to the inner pipe 92 on the burner side, the first connecting outer pipe 10 can be moved to the fuel gas supply source side, and when flange-connecting the first connecting inner pipe 30 to the second connecting inner pipe 40 on the fuel gas supply source side, the first connecting outer pipe 10 can be moved to the burner side, thereby ensuring space for fixing the bolts required for flange connection. This allows for appropriate bolt tightening work.

[0052] (5) In the double pipe connection structure 1, the length of the first connection outer pipe 10 is shorter than the total length of the first connection inner pipe 30 (in this embodiment, the length of the first connection inner pipe 30) by at least the length equivalent to the bolt length of the bolt used to flange-connect the first connection inner pipe 30 to the inner pipe 92 on the combustion equipment side or the inner pipe 82 on the fuel gas supply source side. Therefore, when installing the double pipe connection structure 1, a sufficient gap for the bolt length can be secured by moving the first connecting outer pipe 10 in the axial direction. This makes it easy to attach the bolt to the flange portion, and allows the flange portion of the first connecting inner pipe 30 to be tightened appropriately.

[0053] (6) In the double pipe connection structure 1, the second connecting inner pipe 40 has a flange portion 411 at least on the side of the first connecting inner pipe 30, and when the double pipe 80 on the fuel gas supply source side and the double pipe 90 on the combustion equipment side are connected by the double pipe connection structure 1, the end face of the second connecting outer pipe 20 on the side of the first connecting outer pipe 10 and the end face of the flange portion 411 of the second connecting inner pipe 40 that is flange-connected to the first connecting inner pipe 30 are arranged on the same plane. This allows the first connecting inner pipe 30 to be attached and detached by sliding it in any direction without getting caught on the second connecting outer pipe 20 when attaching or detaching a combustion appliance, making it easy to attach and detach the first connecting inner pipe 30 and improving the workability of the attachment and detachment work.

[0054] (Second embodiment) Fig. 5 is a diagram illustrating a double pipe connection structure 2 of a second embodiment. Fig. 5 shows a state in which a double pipe 80 on the fuel gas supply source side and a double pipe 90 on the burner side are connected by the double pipe connection structure 2. The double pipe connection structure 2 of the second embodiment is similar to the double pipe connection structure 1 of the first embodiment, except that it does not include the second connecting inner pipe 40 and the second connecting outer pipe 20. Therefore, parts that perform the same functions as those in the first embodiment described above are given the same reference numerals or the same reference numerals with the same suffixes, and redundant explanations will be omitted as appropriate.

[0055] In the second embodiment, the outer pipe 81 on the fuel gas supply source side does not have a flange portion. Accordingly, the double pipe connection structure 2 of the second embodiment does not include the second connecting outer pipe 20, and the second connecting member 60 connects the outer pipe 91 on the fuel gas supply source side and the first connecting outer pipe 10. Furthermore, the double pipe connection structure 2 does not include the second connecting inner pipe 40, and the inner pipe 82 on the fuel gas supply source side is connected to the first connecting inner pipe 30 by flange connection. Even with this configuration, similar to the double pipe connection structure 1 of the first embodiment, it is possible to obtain a double pipe connection structure with a simple configuration, in which the connection portion of the first connecting inner pipe 30 can be easily exposed and attached and removed.

[0056] According to the double pipe connection structure 2 of this embodiment described above, the following effects can be achieved, similarly to the double pipe connection structure 1 of the first embodiment described above. (7) The double pipe connection structure 2 is a double pipe connection structure that includes an outer pipe and an inner pipe that is disposed inside the outer pipe and forms a ventilation flow path between the outer pipe and the inner pipe, and that connects an end of the double pipe 80 on the fuel gas supply source side to an end of the double pipe 90 on the combustion appliance side in a double pipe that connects a fuel gas supply source and a combustion appliance, and includes a cylindrical first connecting outer pipe 10 that is disposed at a predetermined interval in the axial direction between the outer pipe 81 of the double pipe 80 on the fuel gas supply source side and the outer pipe 91 of the double pipe 90 on the combustion appliance side, and is disposed inside the first connecting outer pipe 10 and is used to connect the inner pipe 82 of the double pipe 80 on the fuel gas supply source side to the inner pipe 92 of the double pipe 90 on the combustion appliance side. a first connecting member 50 that connects the first connecting outer pipe 10 to the outer pipe 91 of the double pipe 90 on the combustion equipment side; and a second connecting member 60 that connects the first connecting outer pipe 10 to the outer pipe 81 of the double pipe 80 on the fuel gas supply source side. The first connecting member 50 and the second connecting member 60 each include a cylindrical housing 51, 61 into which the first connecting outer pipe 10 can be inserted, tightening means 53, 63 that tightens the housing 51, 61 so as to reduce the inner diameter of the housing 51, 61, and an elastic body 52, 62 that is arranged inside the housing 51, 61 and comes into close contact with the first connecting outer pipe 10.

[0057] Therefore, the first connecting outer pipe 10 is arranged between the end of the double pipe 80 on the fuel gas supply source side and the end of the double pipe 90 on the combustion equipment side, with a predetermined axial gap between them, so that the connection portion of the inner pipe can be easily exposed by shifting the first connecting outer pipe 10 in the axial direction, facilitating the connection work. In addition, the first connecting member 50 and the second connecting member 60 have elastic bodies 52, 62 inside cylindrical housings 51, 61, and the housings 51, 61 are tightened with tightening means 53, 63 to fix the outer tube, making it possible to connect outer tubes positioned at a predetermined distance in the axial direction, facilitating installation and removal, and improving the workability of connecting double pipes. Furthermore, the first connecting member 50 and the second connecting member 60 can withstand a pressure of about 1 MPa, and can be used even when the pressure of the gas fuel is high. Furthermore, the first connecting outer pipe 10 is not in a half-cylindrical shape and does not have a connecting portion extending in the axial direction, so that the risk of leakage from the connecting portion in the axial direction can be reduced. Furthermore, the double pipe connection structure 2 can have a simpler configuration than the double pipe connection structure 1.

[0058] (Variations) The present invention is not limited to the above-described embodiments, and various modifications and variations are possible, and these are also within the scope of the present invention. For example, if the outer pipe 81 on the fuel gas supply source side does not have a flange portion, the outer pipe 81 and the second connecting outer pipe 20 may be connected by a third connecting member having the same shape as the first connecting member 50 and the second connecting member 60. Fig. 6 is a diagram illustrating a modified double pipe connection structure 3. Fig. 6 shows a state in which a double pipe 80 on the fuel gas supply source side and a double pipe 90 on the burner side are connected by the double pipe connection structure 3. In Fig. 6, the shapes of the first connecting member 50 and the like are simplified for ease of understanding.

[0059] 6(a), in the case where the inner pipe 82 on the fuel gas supply source side protrudes further downstream than the outer pipe 81, the double pipe connection structure 3 may not include the second connecting inner pipe 40, but may be configured so that the inner pipe 82 is positioned inside the second connecting outer pipe 20, the inner pipe 82 and the first connecting inner pipe 30 are flange-connected, and the outer pipe 81 and the second connecting outer pipe 20 are connected by the third connecting member 70. This can also be said to be a configuration in which the end of the double pipe 80 on the gas supply source side is extended to the first connecting outer pipe 10 side (downstream side, burner appliance side) by the second connecting outer pipe 20, the inner pipe 82, and the third connecting member 70, and connected to the first connecting outer pipe 10 and the first connecting inner pipe 30.

[0060] 6(b), the double pipe connection structure 3 may include a second connecting inner pipe 40, and an inner pipe 82 on the fuel gas supply source side and the second connecting inner pipe 40 may be flange-connected, and an outer pipe 81 and the second connecting outer pipe 20 may be connected by a third connecting member 70. This can also be said to be a configuration in which the end of the double pipe 80 on the gas supply source side is extended to the first connecting outer pipe 10 side (downstream side, burner side) by the second connecting outer pipe 20, the second connecting inner pipe 40, and the third connecting member 70, and is connected to the first connecting outer pipe 10 and the first connecting inner pipe 30.

[0061] Furthermore, in each embodiment, an example has been shown in which there is one first connecting inner pipe 30, but this is not limited to this, and multiple first connecting inner pipes 30 may be provided inside the first connecting outer pipe 10, and they may be flange-connected. In such a configuration, it is preferable that the length of the first connecting outer pipe 10 is shorter than the total length of the multiple first connecting inner pipes 30. It is also more preferable that the length of the first connecting outer pipe 10 is shorter than the total length of the multiple first connecting inner pipes 30 by at least the length corresponding to the bolt length used when flange-connecting the first connecting inner pipe 30 to the inner pipe 92 on the combustion appliance side or the inner pipe 82 on the fuel gas supply source side.

[0062] Furthermore, when the outer pipe 91 of the double pipe 90 on the burner side has a flange portion, the double pipe connection structure may have the second connecting outer pipe 20 and the second connecting inner pipe 40 disposed downstream (on the burner side) of the first connecting outer pipe 10. In this case, the flange portion 221 of the second connecting outer pipe 20 is flange-connected to the flange portion of the outer pipe 91 on the burner side, and the other cylindrical end of the second connecting outer pipe 20 is connected to the first connecting outer pipe 10 by the first connecting member 50. Furthermore, the second connecting inner pipe 40 is provided inside the second connecting outer pipe 20, and the second connecting inner pipe 40 connects the inner pipe 92 on the burner side and the first connecting inner pipe 30.

[0063] The double-pipe connection structure of the present invention is also applicable to cases where both the fuel gas supply source side outer pipe 81 and the burner side outer pipe 91 have flanges, and in this case, the second connecting outer pipe 20 and the second connecting inner pipe 40 are arranged upstream and downstream of the first connecting outer pipe 10 and the first connecting inner pipe 30, respectively. In this case, the second connecting outer pipe 20 located upstream of the first connecting outer pipe 10 and the second connecting outer pipe 20 located downstream may have different axial lengths. Similarly, the second connecting inner pipe 40 located upstream of the first connecting inner pipe 30 and the second connecting inner pipe 40 located downstream may have different axial lengths.

[0064] Furthermore, when the outer diameter of at least one of the fuel gas supply source side outer pipe 81 and the burner side outer pipe 91 is different from the outer diameter of the first connecting outer pipe 10, the second connecting outer pipe 20 may have a structure that allows connection of different diameters, in which the outer diameter of at least one of the fuel gas supply source side outer pipe 81 and the burner side outer pipe 91 is changed to the outer diameter of the first connecting outer pipe 10. In other words, the first connecting outer pipe 10 may also have a structure that allows connection of different diameters. However, when such a configuration is used, it is preferable that the first connecting outer pipe 10 and the second connecting outer pipe 20 are configured to be movable in the axial direction with the first connecting member 50 and the second connecting member 60 inserted inside the first connecting outer pipe 10 and the second connecting outer pipe 20.

[0065] Furthermore, the two outer tubes connected by the first connecting member 50 and the second connecting member 60 preferably have a cylindrical shape and the same outer diameter. However, if the two outer tubes have different outer diameters, the inner diameters of the elastic body 52 of the first connecting member 50 and the elastic body 62 of the second connecting member 60 may be made different in the axial direction to correspond to the respective outer diameters. By using such a first connecting member 50 and second connecting member 60, it is possible to connect two outer tubes with different outer diameters.

[0066] The end face of the flange portion 921 of the inner pipe 92 of the double pipe 90 on the burner side may be positioned axially upstream (towards the fuel gas supply source) of the end of the outer pipe 91.

[0067] In each embodiment, an example in which one first connecting outer tube 10 is provided is shown, but this is not limited to this, and multiple first connecting outer tubes 10 may be arranged along the axial direction and connected by a connecting member (not shown) having the same shape as the first connecting member 50, etc.

[0068] The present invention is not limited to the above-described embodiments, but may be combined with other embodiments as desired.

[0069] Furthermore, since the present invention promotes the use of ammonia as a fuel, which does not emit carbon dioxide, it can contribute to, for example, Goal 7 of the United Nations-led Sustainable Development Goals (SDGs), which is to "ensure access to affordable, reliable, sustainable and modern energy." [Explanation of symbols]

[0070] 1,2 Double pipe connection structure 10 Outer pipe for first connection 20 Outer pipe for second connection 221 Flange 30 First connecting inner pipe 311,321 Flange 40 Second connecting inner pipe 411,421 Flange 50 first connecting member 51,61 Housing 52,62 Elastic body 53,63 Fastening means 60 second connecting member

Claims

1. A double pipe connection structure for connecting a fuel gas supply source and a combustion appliance, the double pipe comprising an outer pipe and an inner pipe disposed inside the outer pipe and forming a ventilation flow path between the outer pipe and the inner pipe, the double pipe connection structure connecting an end of the double pipe on the fuel gas supply source side to an end of the double pipe on the combustion appliance side, a cylindrical first connecting outer pipe disposed between the outer pipe of the double pipe on the fuel gas supply source side and the outer pipe of the double pipe on the combustion appliance side at a predetermined interval in the axial direction; at least one first connecting inner pipe disposed inside the first connecting outer pipe and used to connect an inner pipe of the double pipe on the fuel gas supply source side to an inner pipe of the double pipe on the combustion appliance side; a first connecting member that connects the first connecting outer pipe to an outer pipe of the double pipe on the burner side or a second connecting outer pipe that is arranged on the burner side of the first connecting outer pipe; a second connecting member that connects the first connecting outer pipe to an outer pipe of the double pipe on the fuel gas supply source side or a second connecting outer pipe that is arranged on the fuel gas supply source side of the first connecting outer pipe; Equipped with the second connecting outer pipe is a member that extends at least one of the outer pipe of the double pipe on the fuel gas supply source side and the outer pipe of the double pipe on the combustion appliance side toward the first connecting outer pipe, thereby making the second connecting outer pipe an outer pipe that can be connected to the first connecting outer pipe, The first connecting member and the second connecting member are a cylindrical housing into which the first connecting outer pipe can be inserted; a clamping means for clamping the housing so as to reduce the inner diameter of the housing; an elastic body disposed inside the housing and in close contact with the first connecting outer tube; A double pipe connection structure.

2. the second connecting outer pipe has a cylindrical end on the first connecting outer pipe side and a flange portion on the end opposite to the first connecting outer pipe, When at least one of an outer pipe of the double pipe on the fuel gas supply source side and an outer pipe of the double pipe on the combustion appliance side has a flange, the flange portion is flange-connected to the flange. The double pipe connection structure according to claim 1 .

3. Further provided is a second connecting inner pipe disposed inside the second connecting outer pipe. The double pipe connection structure according to claim 1 or 2.

4. The length of the first connecting outer pipe is shorter than the total length of the first connecting inner pipe. The double pipe connection structure according to claim 1 .

5. the length of the first connecting outer pipe is shorter than the total length of the first connecting inner pipe by at least a length corresponding to the length of a bolt used when flange-connecting the first connecting inner pipe to the inner pipe on the combustion appliance side or the inner pipe on the fuel gas supply source side; The double pipe connection structure according to claim 4.

6. the second connecting inner pipe has a flange portion at least on the first connecting inner pipe side, When the double pipe on the fuel gas supply source side and the double pipe on the combustion appliance side are connected by the double pipe connection structure, the end face of the second connecting outer pipe on the first connecting outer pipe side and the end face of the flange portion of the second connecting inner pipe that is flange-connected to the first connecting inner pipe are arranged to be on the same plane. The double pipe connection structure according to claim 3.

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