Johnston coupling with galvanic isolation

Abstract

To provide a Johnston coupling with a galvanic insulation.SOLUTION: A plug-in coupling includes a coupling plug and a coupling socket. The coupling plug includes an inner and outer pipe piece and a first attachment flange, and is connected to a first cryogenic temperature line. The coupling socket includes an inner and outer pipe piece and a second attachment flange, and is connected to a second cryogenic temperature line. On a distal end of the coupling plug, there is arranged a circular annular seal such that a sealed connection between the coupling socket and the coupling plug is formed when the coupling plug has been fully inserted into the coupling socket.. The plug-in coupling is characterized in that (a) the seal on the distal end of the coupling plug is of electrically insulating form, (b) an insulating sleeve is arranged on the outer pipe piece of the coupling plug, and (c) an insulating disc is situated between the first and the second attachment flange when the coupling plug has been inserted into the coupling socket.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a plug-in coupling for vacuum insulated flexible lines, also known by the term "Johnston coupling." In particular, the present invention relates to a Johnston coupling with galvanic isolation. [Background technology]

[0002] Supercooled media, also called cryogenic liquids, are usually transported by ships, tank cars, or tank trucks. One important example is liquefied natural gas (LNG), whose evaporation temperature is −162°C (111K). Loading is typically done using uninsulated lines and couplings, which freeze during the loading process. Without insulation, some of the supercooled media will evaporate, which involves an energy loss, since the evaporated media must be re-liquefied elsewhere using significant energy.

[0003] When loading even colder media, such as liquid nitrogen (evaporation temperature -253°C, 20K) or liquid helium (evaporation temperature -269°C, 4K), the oxygen in the air, which has a relatively high evaporation temperature (-183°C, 90K), will condense on the surfaces of uninsulated lines and couplings. This is highly undesirable, as liquid oxygen significantly increases the risk of fire.

[0004] Furthermore, vacuum insulated lines are also known for transporting such cryogenic liquids or media, and are manufactured, for example, by the company Nexans. For filling and loading into tanks, the vacuum insulated lines must be flexible and equipped at one end with a so-called Johnston coupling, which allows two cryogenic lines to be connected without compromising the insulation at the connection point. In this way, losses of cryogenic media due to freezing and evaporation at the connection point are reduced.

[0005] Simply put, in a Johnston coupling, two double vacuum-insulated pipelines are inserted one into the other. The internal diameter of such pipelines is typically 20 to 150 mm. However, smaller or larger internal diameters are also possible. The male part (inner double pipeline) is inserted into the female part (outer double pipeline). These are also called coupling plugs and coupling sockets. In this way, the outer surface is very effectively insulated with respect to the inner medium conduit. For this purpose, the two double pipelines must be inserted one into the other over a certain length. Depending on the medium and the desired insulation, typical pipe insertion lengths are in the range of 200 to 600 mm. Individual applications may deviate from this range to shorter or longer lengths.

[0006] A pipe connection that interconnects two objects at different potentials has galvanic isolation to electrically isolate the two objects with respect to each other. For example, there is always a voltage difference between a ship and the pier where the ship is moored. This voltage difference can be caused, for example, by the ship's cathodic protection system or by a galvanically generated voltage.

[0007] The voltage differences mentioned above can cause ignition sources, which is a major hazard, especially during the loading and unloading of flammable materials. Such ignition sources can be avoided, for example, by an electrical connection between the ship and the quay. However, in reality, the current flowing through the electrical connection can lead to unacceptable overheating of the electrical connection.

[0008] In order to avoid these problems, regulations have been enacted which require that ships and onshore or quayside installations be kept electrically separated. For crude oil tankers and terminals, it is prescribed that the ship and onshore structures be electrically separated from each other. For this purpose, insulating flanges are incorporated into the transport lines between the ship and shore. Such insulating flanges are known, for example, from Patent Document 1, which proposes a coupling means made of insulating material and connected on both sides by an annular flange to a pipeline which is connected on one side to the ship and on the other side to the onshore installation. The pipeline is formed as a non-insulated pipeline.

[0009] Such non-insulated pipelines work well for transporting liquids that are liquid at room temperature, but do not work well for supercooled or cryogenic liquids, thereby necessitating vacuum insulated lines and couplings for the reasons described in the introduction. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] European Patent Application Publication No. 0113948A1 Summary of the Invention [Problem to be solved by the invention]

[0011] Taking this as a starting point, the object of the present invention is to devise a plug-in coupling for cryogenic lines with galvanic isolation in order to overcome or at least mitigate one or more of the problems described in the introduction. [Means for solving the problem]

[0012] To achieve this object, the present invention proposes, according to a first aspect, a plug-in coupling for connecting a first double vacuum insulated cryogenic line to a second double vacuum insulated cryogenic line. The plug-in coupling includes a connecting plug and a connecting socket. The connecting plug has inner and outer pipe pieces and a first mounting flange and is connected to the first cryogenic line. The connecting socket has inner and outer pipe pieces and a second mounting flange and is connected to the second cryogenic line. A circular annular seal is arranged at the distal end of the connecting plug, whereby a sealed connection is formed between the connecting socket and the connecting plug when the connecting plug is fully inserted into the connecting socket. The plug-in coupling according to the present invention comprises: - the seal at the distal end of the coupling plug is of an electrically insulating type; - an insulating sleeve is arranged on the outer tube part of the coupling plug; - When the mating plug is inserted into the mating socket, an insulating disc is positioned between the first and second mounting flanges. It is characterized by:

[0013] On the one hand, the proposed plug-in coupling offers a solution for transporting a subcooled medium by means of a vacuum-insulated line, which is advantageous in terms of energy losses due to evaporation of the transported medium, and at the same time, the proposed plug-in coupling allows electrical isolation between the connected parts, which is desirable or required by law, for example, when loading onto a ship.

[0014] In one refinement of the plug-in coupling according to the invention, the first and second mounting flanges are provided with through holes for screws connecting the first mounting flange to the second mounting flange, and insulating bushings are inserted into the through holes to electrically insulate the screws with respect to the first and / or second mounting flange.

[0015] In a preferred embodiment of the plug-in coupling, the outer diameter of the first mounting flange is smaller than the outer diameter of the second mounting flange. A rotatable rotary flange having threaded through holes is positioned on the first mounting flange, and the rotary flange can be moved to a rotated position in which the through holes of the rotary flange are aligned with the through holes of the second mounting flange.

[0016] In this exemplary embodiment, there is no need to rotate the mating plug in the mating socket to align the through holes for the fixing screws of the mating plug and the mating socket, respectively, which greatly simplifies handling while the plug-in coupling is closed, because the double vacuum insulated cryogenic line is quite heavy and cannot be easily moved.

[0017] In one advantageous refinement of the plug-in coupling, seals are arranged between the insulating disk and the second mounting flange and / or between the insulating disk and the first mounting flange. This / these additional seals serve to seal the plug-in coupling in warm areas if the seal at the distal end of the connecting plug does not seal the plug-in coupling properly due to locally present low temperatures. The additional seals ensure that even in this unfavorable situation there is no possibility of leakage of the evaporative medium, which could constitute an explosion risk in some circumstances.

[0018] In one variant of the plug-in coupling, the insulating disk and the insulating sleeve are formed as a single, undivided part, thus reducing the number of parts that need to be assembled during assembly of the coupling plug.

[0019] According to a second aspect of the invention, there is proposed a loading facility for cryogenic fluids having a plug-in coupling according to the first aspect of the invention.

[0020] Said loading facility realizes the advantages already described for plug-in coupling with regard to the loading of subcooled medium between the ship and the onshore facility.

[0021] The invention will now be explained in more detail, by way of example, based on two exemplary embodiments and with reference to the accompanying drawings, all of which are purely schematic and not to scale. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 1 is an exploded schematic view of a Johnston coupling with galvanic isolation. [Figure 2] 2 shows the Johnston coupling of FIG. 1 after assembly. [Figure 3] 1 illustrates another exemplary embodiment of a Johnston coupling with galvanic isolation in an assembled state. DETAILED DESCRIPTION OF THE INVENTION

[0023] In the drawings, the same or similar elements are labeled with the same or similar reference numerals.

[0024] Exemplary Embodiments Figure 1 shows a plug-in coupling, generally designated by the reference numeral 100. The plug-in coupling 100 includes a mating plug 101 and a mating socket 102, which are shown in Figure 1 in an unassembled state with a small gap between them.

[0025] The coupling plug 101 is connected to a first cryogenic line 103, and the coupling socket 102 is connected to a second cryogenic line 104. The first cryogenic line 103 has an outer tube 106 and an inner tube 107, which are separated from each other by an intermediate space 108 and insulated from each other by an insulating vacuum within the intermediate space 108. The cryogenic lines 103, 104 are double vacuum insulated cryogenic lines.

[0026] The connecting plug 101 includes a first mounting flange 109, an outer pipe piece 111, and an inner pipe piece 112. The outer pipe 106 of the first cryogenic line 103 is welded to a major surface of the first mounting flange 109. On the opposite major surface of the mounting flange 109, the outer pipe piece 111 is welded to the first mounting flange 109. A distal end 113 of the outer pipe piece 111, remote from the first mounting flange, is connected to an inner pipe piece 112, which extends to the first mounting flange and is connected to the inner pipe 107 of the first cryogenic line 103. An annular gap 114 is formed between the outer pipe piece 111 and the inner pipe piece 112. The intermediate space 108 is connected to the annular gap 114 at a point of flow, allowing an insulating vacuum to extend into the annular gap 114, ensuring good thermal insulation of the inner pipe piece 112.

[0027] An electrically insulating sleeve 116 fits over the outer tubular part 111 of the connecting plug 101. The sleeve 116 is somewhat longer than the outer tubular part 111 and therefore protrudes at the distal end 113 of the connecting plug 101 to form a protruding lip 117 that holds a circular annular seal 118, which abuts the distal end 113 of the connecting plug 101. The seal 118 is made from an electrically insulating material, for example polytetrafluoroethylene (PTFE) or Torlon®. An annular groove 120 is cut in the first mounting flange 109, into which a seal 121 is inserted. The seal 121 may be of conductive or non-conductive type.

[0028] The connection socket 102 has a second mounting flange 122, an outer pipe piece 123, and an inner pipe piece 124. The pipe pieces 123, 124 are each welded at one end to the second mounting flange 122, in turn forming an annular gap 126 between the pipe pieces 123, 124. The other end of each of the pipe pieces 123, 124 is connected to the second cryogenic line 104. The second cryogenic line has an outer pipe 128 and an inner pipe 129. An intermediate space 130 is formed between the outer pipe 128 and the inner pipe 129, within which an insulating vacuum prevails, insulating the inner pipe 129. An outer pipe 128 of the second cryogenic line 104 is connected to the outer pipe piece 123, an inner pipe 129 is connected to the inner pipe piece 124 of the connecting socket 102, and an intermediate space 130 is connected at a point of flow to the annular gap 126, so that the insulating vacuum extends into the annular gap 126 of the connecting socket 102 and ensures good insulation of the inner pipe piece 124 of the connecting socket 102. The outer diameter of the insulating sleeve 116 is smaller than the inner diameter of the inner pipe piece of the connecting socket, so that an annular gap 131 (FIG. 2) is formed between the sleeve 116 and the inner pipe piece 124.

[0029] At the transition between the connection socket 102 and the second cryogenic line 104, an annular seat 132 for the seal 118 is formed, and the seal 118 abuts against the seat 132 when the connection plug 101 is fully inserted into the connection socket 102 (FIG. 2).

[0030] Radially outwardly, the first and second mounting flanges 109, 122 have through holes 133, 134 for fixing screws 136. The diameter of the through hole 134 is larger than the diameter of the fixing screws 136, by means of which an insulating bushing 137 can be fitted, which in the assembled state abuts the second mounting flange 122 together with a collar 138. An annular groove 139 is cut in the second mounting flange 122, into which a seal 141 is inserted. The seal 141 may be of conductive or non-conductive type.

[0031] Disposed between the first and second mounting flanges 109, 122 is an insulating disk 142 having a central opening 143 through which the insulating sleeve 116 projects.

[0032] On its side facing the second mounting flange 122, the insulating disk 142 has an annular protrusion 144 that fits precisely into an annular recess 145 in the second mounting flange 122 and serves to center the insulating disk 142. On its opposite side, the insulating disk 142 is provided with an annular recess 146 that receives a surrounding collar 147 of the insulating sleeve 116 when the plug-in coupling is assembled. The annular protrusion and recess ensure that the individual components are centered relative to one another. The insulating disk 142 also has a through-hole 148 for the fixing screw 136, which is located in the same angular position as the through-holes 133 and 134 in the first and second mounting flanges 109 and 122, respectively, so that the fixing screw can be installed when the insulating disk 142 and the first and second mounting flanges 109 and 122, respectively, are rotated to the corresponding rotational positions.

[0033] 2 shows the plug-in coupling 100 of FIG. 1 in an assembled state. The fixing screw 136 is attached using a threaded nut 149 and a washer 150, pressing the first and second mounting flanges 109, 122 against the insulating disk 142 from both sides. The thickness D of the insulating disk 142 is such that the distal end 113 of the connecting plug 101 presses the seal 118 against the seat 132 of the connecting socket 102. The seal 118 seals the transition between the connecting plug 101 and the connecting socket 102. Because the seal 118 comes into contact with the subcooled medium during operation of the plug-in coupling, 100% leak-proofness may not be guaranteed in some circumstances. The subcooled medium passes through seal 118 into annular gap 131 between insulating sleeve 116 and inner tube 124 of coupling socket 102, where it vaporizes, and seals 121, 141 located in the warm areas of first and second mounting flanges 109, 122, respectively, prevent the vaporized medium from leaking out of the plug-in coupling into the environment, which is highly undesirable in the case of flammable media such as liquefied natural gas or liquid hydrogen.

[0034] As can be seen in FIG. 2 , there is no metallic connection between the mating plug 101 and the mating socket 102. The electrically insulating seal 118, the electrically insulating sleeve 116, and the insulating disk 142 prevent contact between the metal parts of the mating plug 101 and the mating socket 102. This is true even if the mating plug 101 is inserted into the mating socket at an angle or misaligned. The electrically insulating sleeve 116 prevents contact between the metal parts of the mating plug 101 and the inner tubular part 124 of the mating socket 102. The fixing screw 136 is guided in the electrically insulating sleeve 137 and similarly prevents electrical contact between the mating plug 101 and the mating socket 102. In this way, galvanic isolation is achieved between the mating plug 101 and the mating socket 102.

[0035] During assembly of the plug-in coupling, the mating plug is first inserted into the mating socket. The insulating disk 142 is then rotated until the through holes 148 of the insulating disk 142 are aligned with the through holes 134 of the second mounting flange 122. This rotated position of the insulating disk 142 is fixed by one or more partially threaded fixing screws 136. The mating plug 101 is then rotated until the fixing screws 136 can be inserted into the through holes 133 of the first mounting flange 109 and secured by the threaded nuts 149.

[0036] Although the insulating disk 142 can be rotated relatively easily, the plug-in coupling 100 generally cannot, because the plug-in coupling is fixedly connected to the first cryogenic line 103. Therefore, other exemplary embodiments are proposed that allow the plug-in coupling 100 to be more easily closed.

[0037] 3 shows a second exemplary embodiment of a plug-in coupling 100 according to the invention, which differs from the plug-in coupling according to FIG. 2 in particular in that the first mounting flange 109′ is not pressed directly against the insulating disk 142 or the second mounting flange 122 by the fixing screws, but rather the tension of the fixing screws 136 is applied to a rotatable rotary flange 151, which bears against the first mounting flange 109′ and therefore transmits the force applied by the fixing screws 136 to the first mounting flange 109′. For this purpose, the outer diameter of the mounting flange 109′ is reduced so that the fixing screws 136 extend beyond the outer periphery of the first mounting flange 109′. The rotary flange 151 is formed as a circular annular disk and has through holes 152 for the fixing screws 136. The through holes 152 are arranged concentrically with respect to the through holes 134 of the second mounting flange 122. The rotary flange 151 is received in a seat 153 on the first mounting flange 109' with a small amount of play, which allows the rotary flange 151 to be easily rotated on the first mounting flange 109' to a rotated position where the through holes 152 are aligned with the through holes 134 in the second mounting flange 122 and the fixing screws 136 can be installed. In this exemplary embodiment, the coupling plug 101 does not need to be rotated after being inserted into the coupling socket 102. Only the rotary flange 151 needs to be rotated, which greatly simplifies the work of the person connecting the plug-in coupling.

[0038] In a variant of the second exemplary embodiment (not shown), the roles of the first and second mounting flanges are reversed, so to speak, in that the rotary flange is positioned on the second mounting flange. In this variant of the second exemplary embodiment, the second mounting flange has a smaller outer diameter, so that the fixing screws 136 extend beyond the outer periphery of the second mounting flange. In this way, again, during assembly of the plug-in coupling, only the easily rotatable rotary flange needs to be moved to a rotated position so that the through-holes in the rotary flange are aligned with the through-holes in the first mounting flange and the fixing screws can be installed. In this variant embodiment, an insulating bushing 137 is attached to the first mounting flange 109.

[0039] In another variation of the first or second exemplary embodiment, the insulating sleeve 116 and the insulating disk 142 are formed as a single, undivided part, thereby reducing the number of individual parts in the plug-in coupling 100. A single part may also be advantageous in terms of assembly of the plug-in coupling. [Explanation of symbols]

[0040] Reference Code List 100 Plug-in Coupling 101 Connecting plug 102 Connecting Socket 103 First Cryogenic Line 104 Second Cryogenic Line 106 Outer tube 107 Inner tube 108 Intermediate Space 109, 109' first mounting flange 111 Outer pipe parts 112 Inner tube parts 113 Distal end 114 Annular Gap 116 Insulating sleeve 117 Protruding edge 118 stickers 120 Annular groove 121 Stickers 122 Second mounting flange 123 Outer pipe parts 124 Inner tube part 126 Annular Gap 128 Outer tube 129 Inner tube 131 Intermediate Space 132 Circular pedestal 133 Through Hole 134 through hole 136 Fixing screw 137 Insulating bushing 138 Insulating bushing color 139 Annular groove 141 Stickers 142 Insulating disc 143 Central opening 144 Annular protrusion 145 Annular recess 146 Annular recess 147 Surrounding Color 148 through holes 149 Threaded Nut 150 washer 151 Rotary flange 152 through hole 153 Pedestal

Claims

1. A plug-in coupling for connecting a first double vacuum insulated cryogenic line (103) to a second double vacuum insulated cryogenic line (104), the plug-in coupling (100) comprising a coupling plug (101) and a coupling socket (102); - said connecting plug (101) comprises inner and outer pipe pieces (111, 112) and a first mounting flange (109, 109') and is connected to said first cryogenic line (103); - said connecting socket (102) has inner and outer pipe pieces (123, 124) and a second mounting flange (122) and is connected to said second cryogenic line (104); an annular seat (132) formed at a transition between the connection socket (102) and the second cryogenic line (104); a circular annular seal (118) is arranged at the distal end (113) of said connecting plug (101), so that when said connecting plug is fully inserted into said connecting socket, said distal end (113) of said connecting plug presses said seal (118) against said annular seat (132) of said connecting socket (102) in the insertion direction, forming a sealed connection between said connecting socket and said connecting plug; the seal (118) at the distal end (113) of the connecting plug is of an electrically insulating type; an insulating sleeve (116) is disposed on the outer pipe part (111) of the connecting plug (101), and when the connecting plug is fully inserted into the connecting socket, the insulating sleeve (116) does not abut against the connecting socket in the insertion direction; A plug-in coupling, characterized in that when the mating plug is inserted into the mating socket, an insulating disk (142) is positioned between the first and second mounting flanges (109, 109'; 122).

2. 2. A plug-in coupling according to claim 1, characterized in that in the first and second mounting flanges, through-holes (133, 134) for screws (136) for the connection of the first mounting flange (109, 109') to the second mounting flange (122) are provided, and in the through-holes (133, 134) insulating bushings are inserted which electrically insulate the screws (136) with respect to the first and / or second mounting flanges (109, 109'; 122).

3. 3. A plug-in coupling according to claim 1 or 2, characterized in that the outer diameter of the first mounting flange (109, 109') is smaller than the outer diameter of the second mounting flange (122), and a rotatable rotary flange (151) having through holes (152) for screws (136) is located on the first mounting flange (109, 109'), which rotary flange can be moved to a rotational position in which the through holes (152) of the rotary flange (151) are aligned with the through holes (134) of the second mounting flange (122).

4. 4. The plug-in coupling according to claim 1, wherein a seal (121) is arranged between the insulating disc (142) and the first mounting flange (109, 109') and / or between the insulating disc (142) and the second mounting flange (122).

5. 5. A plug-in coupling according to any one of claims 1 to 4, characterized in that the insulating disc (142) and the insulating sleeve (116) are formed as a single, undivided part.

6. Cryogenic fluid loading equipment comprising a plug-in coupling (100) according to any one of claims 1 to 5.

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