GB2639175A

GB2639175A - Cryogenic fluid transfer

Info

Publication number: GB2639175A
Application number: GB2403037.1A
Authority: GB
Inventors: Edward Alec Beaumont Jonathan; Willis Alexandra
Original assignee: Enoflex Ltd
Current assignee: Enoflex Ltd
Priority date: 2024-03-01
Filing date: 2024-03-01
Publication date: 2025-09-17
Also published as: WO2025181461A1; GB202403037D0

Abstract

A hose for fluid (e.g cryogenic fluid) transfer comprises a tubular inner hose 1 for fluid transport and an outer hose part 6. The tubular inner hose has a corrugated inner surface defining a bore of the inner hose, and the inner hose has a permeable tubular inner sleeve 7 located within its bore. An inner wall of the permeable tubular sleeve is substantially smooth. The smooth interior surface of the sleeve prevents turbulence arising and allows for effective flow. As the sleeve is permeable, liquid can pass through it to prevent a pressure differential arising between the inner and outer walls of the sleeve, which could cause it to collapse. Embodiments include: the permeable sleeve comprises a polymer composite internal layer and a permeable outer layer wrapped around the internal layer; Methods of manufacturing such a hose; Insulated superconducting cable comprising a hose for fluid transfer with a superconducting cable disposed within the inner permeable tubular sleeve such that the inner hose is adapted for conveying a low temperature fluid in the bore of the inner hose for cooling the superconducting cable.

Description

Cryogenic Fluid Transfer

FIELD OF THE INVENTION

The present invention relates to cryogenic fluid transfer. In embodiments, the present invention provides methods and apparatus for effective transfer of cryogenic fluids.

DESCRIPTION OF THE RELATED ART

Cryogenic fluid transfer techniques have been used for some time in relation to subsea pipelines. Originally, this use was driven by the desire to obtain natural gas from remote locations. A large amount of natural gas (mainly methane) is present in remote locations around the world. This gas is of significant value if it can be economically marketed. If the stored gas is reasonably close to the places where it is to be consumed and the terrain between the locations allows, then the gas is generally extracted and transported in gaseous form to those end locations. Transportation is achieved via underwater and/or onshore pipelines. However, if gas is produced where it is not economically feasible or where it is not permitted to lay a pipeline, then other techniques to transport the gas need to be employed.

A commonly used technique for transporting gas without a pipeline is to liquefy the gas at or near the production site and then to transfer the liquefied gas into a specially designed storage tank on a carrier, such as a ship. Liquefying the gas significantly reduces its volume and increases the mass of gas that can be stored and transported. In order to achieve this, the natural gas is cooled and condensed to a liquid state to produce liquefied natural gas (LNG). LNG is typically (but not always) stored and transported at substantially atmospheric pressure and at a temperature of about -162 ° C. When an LNG carrier arrives at a destination, typically the LNG is unloaded into other storage tanks. A regassification processes is then performed, as needed, to convert the LNG back into gaseous form, after which it may be transported, for example via pipelines, to end locations to be used. LNG is an increasingly popular transportation method for supplying natural gas to major energy consuming countries. -2 -

The piping used to transport liquefied gases, such as LNG or the liquefied components of air, must be capable of withstanding very low temperatures, typically below -150°C. One type of piping used for such transport is a reeled corrugated hose with a vacuum between an inner and an outer corrugated hose.

Transfer of LNG is not the only use case for cryogenic fluid transfer, however. An increasingly important use of such hoses is in connection with superconducting cabling. There are now superconducting materials available that are capable of superconducting operation (with significant current flow) at liquid nitrogen temperatures, and which can be manufactured as structurally stable tapes or wires -examples of such materials are BizSr2Ca2Cu3Olo (BSCCO) with a critical temperature of -160°C and YBa2Cu307 (YBCO) with a critical temperature of 180°C. Hoses of the type indicated above may be used to convey liquid nitrogen to support such superconducting uses. However, such hoses may also be used for superconducting cables in use.

Reeled corrugated hoses manufactured from stainless steel are an established means of transporting cryogenic fluids -stainless steel hoses can be used to carry fluids at such temperatures without becoming brittle. Figures 1 and 2 show a prior art hose of this type (such hoses are provided, for example, by Nexans). The cryogenic fluid is carried within a helically corrugated stainless steel inner tube 1. This tube is longitudinally welded to form desired hose lengths. The inner tube 1 is surrounded by a number of layers 2 of superinsulation -individual layers are separated by a polypropylene spacer fleece (not shown). A low loss spacer 3 holds the inner tube 1 in position and a vacuum layer 5 is defined between the insulated inner tube 1 and a further helically corrugated stainless steel outer tube 4, also longitudinally welded to form a desired hose length. This outer tube 4 is retained within a protective outer polyethylene jacket 6. Figure 3 shows an example of how this arrangement can be used in connection with superconducting cable 8 (comprising, for example, superconducting wire in a sheath). Using a hose of this type with a flow of liquid nitrogen in the central bore of the hose enables the superconducting cable to be kept at operating temperature even if the outer jacket of the hose is at ambient temperature. -3 -

While such hose structures are robust and can achieve well insulated cryogenic flow, another technical problem arises. Fluid flow through the inner hose can easily become turbulent, and there are significant friction effects between the transported liquid and the hose. Agitation and turbulence can also lead to 'boil off', in which the liquid changes phase to gas. Such gas must then be either consumed, re-liquified (at significant cost) or vented (which may be environmentally damaging) This can lead to use of such corrugated hoses becoming problematic in certain conditions.

It is against this background that the present invention has been devised.

SUMMARY OF THE INVENTION

According to a first aspect, the invention provides a hose for fluid transfer, the hose comprising a tubular inner hose for fluid transport and an outer hose part, wherein the tubular inner hose has a corrugated inner surface defining a bore of the inner hose, the inner hose further comprising an inner permeable tubular sleeve located within the bore of the inner hose, wherein an inner wall of the permeable tubular sleeve is substantially smooth.

Using this approach, the smooth interior surface of the sleeve prevents turbulence arising and allows for effective flow. As the sleeve is permeable, liquid can pass through it to prevent a pressure differential arising between the inner and outer walls of the sleeve, which could cause it to collapse. r

In embodiments, an outer wall of the inner sleeve forms a clearance fit with the corrugated inner surface. In a particular use case of interest, the hose is adapted for flow of cryogenic fluids. Here, the inner hose may be wrapped in one or more layers of superinsulation. Such a tubular inner hose may have both corrugated inner and outer surfaces, and the tubular inner hose may then be located within an outer hose part bore, a corrugated inner surface of the outer hose part defining the outer hose part bore. Such an outer hose part bore may be adapted to provide a vacuum space between the outer hose part and the inner hose. -4 -

In a second aspect, the invention provides a permeable tubular sleeve for use in a hose for fluid transfer, the permeable sleeve comprising: a. a polymer composite internal layer; b. a permeable outer layer wrapped around the internal layer; wherein the internal layer is formed from a longitudinal sheet of polymer composite, the longitudinal sheet of polymer composite having been wrapped around the longitudinal axis, such that the internal layer has the form of an annular cylinder permeable to fluid.

The internal layer of the sleeve may have a thickness of 0.2 to 0.6mm. The polymer composite may comprise polymer fibres embedded in a polymer matrix. The polymer fibres and the polymer matrix may comprise the same polymer or a copolymer thereof. Specifically, the polymer fibres and the polymer matrix may comprise the same polyolefin or a copolymer thereof. This polyolefin may be polyethylene or polypropylene. The polymer fibres may consist of polypropylene or a copolymer thereof and the polymer matrix may consist of polypropylene or a copolymer thereof. The polymer fibres may have a softening point which is higher than the softening point of the polymer matrix. The polymer fibres of the internal layer may be aligned either parallel to the longitudinal axis or orthogonal to the longitudinal axis. The internal layer may also comprise a plurality of perforations.

In one type of embodiment, the internal layer may have a circumference which is greater than a sheet width defined between a first longitudinal side edge and a second longitudinal side edge of the longitudinal sheet, the longitudinally extending gap comprising a longitudinally extending break defined between the first longitudinal side edge and the second longitudinal side edge. Here, the permeable outer layer may comprise two or more layers of polymer composite tape wound over the internal layer, wherein each of the two or more layers of polymer composite tape comprises a plurality of adjacent windings all applied at the same angle for that layer with respect to a longitudinal axis of the permeable sleeve, wherein adjacent windings in the layer are separated by a winding gap, and wherein the angle for one layer of the polymer composite tape differs from that of an adjacent layer of the polymer composite tape such that there is a permeable gap between each pair of -5 -adjacent layers. With this arrangement, for each layer the angle may be between +/-25 and +/-85 degrees to the axis of the permeable sleeve. If so, for at least two adjacent layers the angle of a first layer of the two adjacent layers may be equal and opposite to the angle of the second layer of the two adjacent layers. A first layer of polymer composite tape wound over the internal layer may be laid at substantially +/-80 degrees to the axis of the permeable sleeve. Such a polymer composite tape may be 10-20 mm wide. The winding gap may be 1-3mm. The polymer composite tape and the internal layer may be formed of the same material. The polymer composite tape may be 0.2-0.8mm in thickness. Adjacent polymer composite tape layers may be laser bonded to each other. An innermost polymer composite tape layer may be laser bonded to the internal layer.

In another type of embodiment, the internal layer of the sleeve may have a circumference which is lesser than a sheet width defined between a first longitudinal side edge and a second longitudinal side edge of the longitudinal sheet, the internal layer comprising a longitudinally extending break and an overlap region between a main cylinder part ending at the first longitudinal side edge and an internal flange part ending at the second longitudinal side edge. This internal flange part may abut, but not be bonded to, the main cylinder part. The permeable outer layer may comprise a dry braided permeable sleeve. This dry braided permeable sleeve may comprise one or more of the following: glass fibre, polymer fibre (for example, aram id fibre), or carbon fibre. This dry braided permeable tubular sleeve may form an interference fit with the internal layer.

In a third aspect, the invention provides a hose for fluid transfer as provided in the first aspect above, wherein the permeable tubular inner sleeve comprises the permeable sleeve as provided in the second aspect above.

In a fourth aspect, the invention provides an insulated superconducting cable comprising a hose for fluid transfer as provided in the first or the third aspect above, with a superconducting cable disposed within the inner permeable tubular sleeve such that the inner hose is adapted for a conveying a low temperature fluid in the bore of the inner hose for cooling the superconducting cable. -6 -

In a fifth aspect, the invention provides for the use of a hose for fluid transfer as provided in the first or the third aspects above for conveying a fluid having a temperature below -150°C.

In a sixth aspect, the invention provides for the use of the insulated superconducting cable of the fourth aspect above, further comprising providing a flow of a fluid having a temperature below -150°C, optionally liquid nitrogen, in the bore of the inner hose.

in a seventh aspect, the invention provides a method of manufacturing a permeable sleeve for use in a hose for fluid transfer, the permeable sleeve comprising a polymer composite internal layer and a permeable outer layer wrapped around the internal layer, the method comprising: a. providing a longitudinal sheet of polymer composite having a sheet width defined between a first longitudinal side edge and a second longitudinal side edge; b. wrapping the longitudinal sheet of polymer composite around the longitudinal axis to provide the internal layer such that the internal layer has the form of an annular cylinder permeable to fluid; c. wrapping the permeable outer layer around the internal layer.

In one approach, wrapping the longitudinal sheet of polymer composite in b. may be achieved by: i. conveying the longitudinal sheet of polymer composite in a direction of travel over rollers which bend the longitudinal sheet of polymer composite into a U-shaped preform; ii. passing the U-shaped preform through a cone-shaped funnel which is configured to wrap the U-shaped preform around a mandrel to provide the internal layer, and wherein in c. the internal layer has a longitudinally extending gap.

The internal layer may have a circumference which is greater than the sheet width, the longitudinally extending gap comprising a longitudinally extending break defined -7 -between the first longitudinal side edge and the second longitudinal side edge. The method here may further comprise winding two or more layers of polymer composite tape over the internal layer to form the permeable outer layer, wherein each of the two or more layers of polymer composite tape comprises a plurality of adjacent windings all applied at the same angle for that layer with respect to a longitudinal axis of the permeable sleeve, wherein adjacent windings in the layer are separated by a winding gap, and wherein the angle for one layer of the polymer composite tape differs from that of an adjacent layer of the polymer composite tape such that there is a permeable gap between each pair of adjacent layers. It may further comprise bonding an inner layer of polymer composite tape to an exterior surface of the internal layer by laser fusion. After the winding of a first layer of wound polymer composite tape, any second and further layer(s) of wound polymer composite tape may be bonded to the preceding layer of wound polymer composite tape by fusion. This method may be configured as a continuous process.

In another approach, the internal layer has a circumference which is lesser than the sheet width, the longitudinally extending gap comprising a longitudinally extending break and an overlap region with a radial gap between a main cylinder part ending at the first longitudinal side edge and an internal flange part ending at the second longitudinal side edge. Here, wrapping the longitudinal sheet of polymer composite in b. may be achieved by: i. conveying the longitudinal sheet of polymer composite in a direction of travel over rollers into a forming cone; ii. passing the longitudinal sheet through the forming cone which is configured to wrap the longitudinal sheet into an tubular layer comprising a longitudinally extending break and an overlap region between a main cylinder part and an internal flange part.

This approach may further comprise heating the wrapped tubular layer to substantially 150 degrees Celsius and subsequently cooling the wrapped tubular layer to ambient temperature. The permeable outer layer may comprise a dry braided permeable sleeve, with the method further comprising overbraiding or pulling the permeable sleeve on to the internal layer. The dry braided permeable -8 -sleeve may then form an interference fit with the internal layer.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be further described, by way of example only, and with reference to the accompanying drawings, in which: Figure 1 shows a view of separate layers of a corrugated hose known in the prior art; Figure 2 shows a longitudinal sectional view of the corrugated hose of Figure 1; Figure 3 shows a corrugated hose of the type shown in Figures 1 and 2 adapted for carrying a superconducting cable; Figure 4 shows a modified corrugated hose, with an internal liner, according to an embodiment of the invention; Figure 5 shows a schematic perspective view of an apparatus used for manufacture of an internal liner associated with embodiments of the invention; Figure 6 shows a schematic perspective view of part of the apparatus used for manufacture of an inner sleeve associated with embodiments of the invention; Figure 7 shows a further perspective view of part of the apparatus used for manufacture of an inner sleeve associated with embodiments of the invention; Figures 8A and 8B show respectively a cross-sectional view and a longitudinal perspective view of a first embodiment of an inner sleeve associated with embodiments of the invention; Figure 9 shows a detailed view of a liner as shown in Figures 8A and 8B wrapped in multiple tape layers; -9 -Figures 10A and 10B show respectively a cross-sectional view and a longitudinal perspective view of a second embodiment of an inner sleeve associated with embodiments of the invention; Figure 11 shows apparatus suitable for forming the second embodiment of the inner sleeve as shown in Figures 10A and 10B; Figures 12A and 12B show alternative methods of providing a braided outer layer for the inner sleeve of Figures 10A and 10B; and Figures 13A and 13B show different views on inserting an inner sleeve into a corrugated hose in accordance with an embodiment of the invention.

DETAILED DESCRIPTION

A detailed description of the invention will now be provided with reference to the above figures. A given reference number is always used to denote the same feature in each of the accompanying drawings.

Figure 4 shows the basic approach taken to address the issue of turbulent flow in the corrugated inner pipe. An inner sleeve or liner 7 is located within the corrugated inner pipe 1. This inner sleeve 7 has a substantially, or comparatively, smooth inner surface, and so does not create turbulence in the same wayas the corrugated inner pipe 1.

The inner sleeve 7 is here disposed so that the main flow of fluid takes place within the internal sleeve. However, it is not intended to form the boundary of the flow channel -it is desirable for the inner sleeve 7 to be permeable so that there is fluid disposed to either side of it. This prevents a pressure buildup which could cause the inner sleeve 7 to collapse. It is therefore appropriate for the inner sleeve 7 to be a clearance fit to the inner wall of the corrugated inner pipe 1, rather than an interference fit. This also has benefits in manufacture, as will be described further below.

-10 -Using this approach, the issue of turbulence can be addressed effectively. As the main flow of fluid is along the smooth inner bore of the inner sleeve 7, turbulence is largely prevented. Otherwise, for cryogenic fluid flow along a long pipe -in practice, pipes of this type may be several kilometres in length -turbulence may be a significant limiting factor in the flow rate achievable through the pipe.

While Figure 4 illustrates this approach in the context of the pure fluid carrying hose of Figure 1, it is equally applicable to the superconducting cable carrying hose of Figure 3 -here the superconducting cable will simply slide within the inner sleeve 7. The cable may be provided with periodic axial centralizers to keep the cable centralized within the inner pipe 1 and the inner sleeve 7. Another possible mechanism for providing superconducting cable in this arrangement is to wrap it around the inner corrugated pipe within the annulus under vacuum.

As previously noted, a suitable corrugated hose structure for use with embodiments of the invention is known, and is shown in Figure 1 -further discussion of hoses of this general type may be found in, for example, US 2020/224816 Al (Nexans) -and this will not be discussed in further detail here. Different types of internal sleeve 7 suitable for use in embodiments of the invention will now be described, together with methods for manufacturing such sleeves and for integrating them into a hose.

A first type of inner sleeve is shown in cross-section in Figure 8A. Here, the inner sleeve 70 comprises a flexible thin wall pipe with a maximum wall thickness t of (approximately) 2.5mm. The key structural element, defining the internal wall 71, is a single polymer composite (SPC) liner layer 73 -made, for example, from polypropylene. This liner layer 73 is permeable, and may for example have a longitudinally extending gap 72, here extending parallel to the longitudinal axis of the internal sleeve. Alternative approaches to permeability can be taken -for example, the liner layer 73 may be perforated with small holes. To the outside of this are a plurality of SPC tape layers 74a, 74b... 74n. These tape layers may be constructed from the same SPC material, and may be formed from a common SPC sheet. In general, however, there should be a leakage path 75 to allow material to leak to the outside of the inner sleeve.

In one exemplary approach, a polypropylene single polymer composite (SPC) sheet is prepared, comprising: - extruded and drawn polypropylene homopolymer fibres which have been plane woven into sheets (woven sheets) such that the fibres are aligned either along an axis or at 90° to the axis; - a polypropylene copolymer matrix in the form of thin film sheets (thin film sheet) having a softening point which is 20°C lower than the melting point of the polypropylene homopolymer fibres.

One or more woven sheets is encased between thin film sheets to form the SPC. If there is more than one woven sheet, then each woven sheet may be separated from the next woven sheet by a thin film sheet interposed between the woven sheets.

Such an SPC sheet may be prepared to comprise three woven sheet layers, each having a thickness of 0.15mm. Each woven sheet layer is separated from the next woven sheet layer by an intermediate layer of thin film sheet, so that there are two intermediate layers of thin film sheet in total. Each intermediate layer of thin film sheet has a thickness of 0.02mm. The combination is sandwiched between two "skin" layers of thin film sheet, each skin layer having a thickness of 0.04mm. There are thus seven layers in total, being two "skin" layers, three woven sheet layers and two intermediate layers.

The seven sandwiched layers are hot-compacted into an SPC of 0.57mm thickness. During hot compaction, the thin film layers soften or melt to form the matrix. Softening or melting of the polypropylene homopolymer fibres is avoided or minimized, by careful application of heat and because of the higher softening point of the homopolymer fibres.

As is noted above, this approach is exemplary and other embodiments may differ -for example, different numbers of layers may be used, or different thicknesses may be used for individual layers or for the SPC sheet as a whole. For example, -12 -for greater flexibility a thinner SPC sheet (say 0.4mm rather than 0.57mm) may be used.

SPCs of the present type are strong and tough at cryogenic temperatures, they are flexible and relatively low cost to produce. Their good material properties are in part due to the good adhesion between the fibres and the matrix on account of their identical or very similar chemical properties. SPCs have the environmental advantage that they may be melted to recycle them.

An exemplary 50.8mm (2 inch) internal diameter pipe may be manufactured from the above-described SPC sheet in the following manner. For completeness, pipes having other dimensions, such as 15.24cm (6 inch), 20.32cm (8 inch) or 25.4cm (10 inch) internal diameter, etc., could also be made in this way: Both a sleeve former and polymer composite tape are cut to width from a longitudinal sheet of SPC. The polymer composite tape is here cut to have a width of 18mm (and has a thickness of 0.57mm, as mentioned above). The sleeve former, cut to a width of 159.51mm, is additionally rolled to further compact it to a thickness of 0.4mm. In the embodiment shown in Figure 8B, the inner sleeve thickness -and so the sleeve former thickness -may be 0.2 to 0.6mm. The SPC tape may be from 0.2 to 0.8mm in thickness, and may be between 10 and 20mm in width.

Figures 5 to 7 show a manufacturing process for first forming the inner sleeve from the sleeve former, and for then applying SPC tape.

With reference to Figures 5 to 7, the longitudinal sheet of SPC serving as the sleeve former 11 is conveyed in a direction of travel 12 through a forming box 13. If it is desirable to do so for a subsequent forming step, the longitudinal sheet of SPC may be heated here to 50-70°C to make it more pliable. The fibres embedded in the longitudinal sheet of SPC are aligned parallel to the direction of travel 12 or are aligned at 90° to the direction of travel. The longitudinal sheet of SPC 11 is conveyed further in the direction of travel over rollers 14 which bend it -13 -into a U-shaped preform 15. The forming box and rollers 14 assembly is located in a housing as shown in Figure 5. The housing for this assembly is removed for the purposes of showing internal workings in Figures 6 and 7. The U-shaped preform is conveyed further in the direction of travel 12 through a cone-shaped funnel 16 and onto a static mandrel 18 to wrap it into a cylindrical sleeve 17 in the form of a broken annular cylinder. The cylinder here has a longitudinal break 19, as can be seen in Figures 6 and 7, and is suitable for use in the inner sleeve of Figures 8A and 8B. In this example, the longitudinal break 19 in the broken annular cylinder may be 2mm wide.

The cylindrical sleeve 17 forms the central member of the inner sleeve 70, the liner layer 73. As is apparent from the description above, the liner layer 73 is permeable at least by virtue of the longitudinal break in the manufactured cylindrical sleeve. As indicated above, if greater permeability, and possibly a different distribution of permeability around the sleeve, is required, then it would be possible to perforate the liner layer 73 to increase the permeability. It would be desirable for the dimensions of such perforations to be relatively small, so that the smooth bore of the inner surface 71 of the liner layer 73 is preserved without such perforations serving to promote turbulence.

As shown in Figures 8A and 8B, SPC tape layers 74a, 74b... 74n are wrapped around the liner layer 73 to form the inner sleeve 70. Figure 7B shows an exemplary wrapping arrangement for a layer 74a with respect to a longitudinal axis x of the inner sleeve 70. As is shown in Figure 7B, the SPC tape is laid at angles of between +/-25 and +/-85 degrees to the pipe axis x. These SPC tape layers are fused to adjacent tape layers -and for the inner SPC tape layer 74a, to the liner layer 73 -by laser welding.

There will typically be multiple tape layers -two to four layers may be suitable for most applications. Figure 8 shows greater detail of a region of the inner sleeve where a second tape layer 74b overlies a first tape layer 74a. As can be seen in Figure 8 (this detail is not shown in Figure 7B), a gap g is introduced between successive strips 76 of tape in the first SPC tape layer 74a. Here, g is chosen to -14 -be 1-3mm. The strips of the second SPC tape layer 74b are laid over the first SPC tape layer at the same angle to the sleeve axis x, but with the opposite sign, and again with a gap g between successive strips. This defines leakage holes 78 at the intersection between the first SPC tape layer 74a and the second SPC tape layer 74b to provide permeability for the inner sleeve 70. For a third SPC tape layer (not shown), there will be a similar set of leakage holes defined between the second SPC tape layer and the third SPC tape layer. This set of leakage holes typically will not overlay the first set of leakage holes 78, but the gap g between the strips of the second tape layer 74b will define a leakage path between the first set of leakage holes 78 and the further set of leakage holes. While there may be points where these sets of leakage holes align, as each succeeding layer is laid on a slightly larger diameter than the previous layer this will lead to a slightly different leakage hole spacing and consequently to a pitch effect.

Figures 5 to 7 also illustrate how an SPC tape layer is applied. While the cylindrical sleeve 17 is conveyed along the static mandrel 18 in the direction of travel 12, layers 21 of SPC tape 20, prepared as described above, are wound onto the cylindrical sleeve 17. The windings of the first layer of SPC tape 20 are applied at an angle to the longitudinal axis, as described above, and are fused to the cylindrical sleeve 17 by laser welding using a laser welding device (not shown). In one possible arrangement, the first layer may be laid at approximately 80 degrees to the pipe axis with a 1 to 3mm gap between the tape edges.

In the arrangement of Figure 8, the windings of a second layer of SPC tape are applied over the first layer of SPC tape and the windings are here applied at the same but opposite angle as the windings of the first layer. Pairs of layers may be applied in this way, but typically a first layer will be applied at a relatively large angle to the pipe axis, such as 80 degrees, as discussed above. Typically, layers beyond this may be applied in pairs, with equal but opposite angles to the pipe axis. A final layer may not be paired -for example, typical angles for a four layer structure may be, in degrees, (Layer 1 +80), (Layer 2 +25), Layer 3 (-25), (Layer 4 +25).. The windings of the one layer of SPC tape are fused to the windings of the preceding layer of SPC tape by laser welding using a laser welding device (not -15 -shown). In this way, with successive laser welding and tape laying stations or with repeated passes through these stations, the full inner sleeve according the first embodiment can be constructed.

An alternative embodiment of an inner sleeve is shown in Figures 10A and 10B. In this case, inner sleeve 90 comprises a liner layer 93 overlaid with a dry braided sleeve 94. Again, the liner layer 93 defines the inner wall 91 of the inner sleeve 90. In this case, the liner layer 93 is not a complete cylinder but it is broken in a different manner -where the liner layer of the first embodiment terminates to form the longitudinal gap, the liner layer 93 extends inwardly and then essentially parallel but radially displaced from the main part of the liner layer 93 to form an unbonded overlap region 97 with the longitudinal gap 92 extending into an overlap region99. These parts of the liner layer 93 in the overlap region 99 may touch or have a small gap -they are not bonded together. The liner layer 93 may be constructed from a former formed from an SPC sheet in a similar manner as for the first embodiment, and to similar dimensions, though the forming process will be slightly different, as discussed below. It should be noted that such a liner is well adapted to reeling -it will squash flat when reeled -which may allow for more versatile assembly of the inner sleeve 90.

The manufacturing process for the liner layer 93 differs slightly for that from that of the first embodiment -a modified process is shown in Figure 11. The sleeve former 11 again passes in direction of travel 12, but in this case it is dragged into forming cone 118, and is bent in the forming cone 118 into an annular shape 117 with an unbonded overlap 119. This annulus 117 will be heated 120 and then cooled into its final shape. After the liner layer is formed, the process is simpler than for the first embodiment, as no tape wrapping step or station is required. Dry fibre braiding is a well-known technique -such a braided sleeve can be woven to appropriate dimensions from materials such as glass fibre, carbon fibre, or a polymer fibre such as an aramid to provide high strength reinforcement material. The braided fibre is naturally permeable, so together with the longitudinal gap 92 and the radial gap 99, it will form a leakage path 95 from the inner sleeve 90 when -16 -in place. Again, the liner layer may also be perforated with small holes to increase permeability.

The braided sleeve 94 provides axial strength to the inner sleeve 90 but it does not need to be bonded to the liner layer 93, allowing for more flexibility in manufacture (possibly even allowing for the braided sleeve 94 to be fitted to the liner layer 93 remotely from the formation of the liner layer itself, for example). Two processes suitable for this fitting process are shown in Figures 12A and 12B. Figure 12A shows an overbraiding process, in which the pre-formed liner layer 93 is ovewrapped 94 by an in-line braiding machine from a braiding ring 95 alternatively, the liner layer 93 may be manufactured to length and then shipped to a supplier for over-braiding. Figure 10B shows a process suitable for extending the manufacturing line shown in Figures 4 to 6 -here, an already manufactured braided sleeve 94 is fixed at a fixing point 102 to the liner layer 93 and dragged on to the liner layer 93 during the manufacturing process. It is well known to manufacture braided sleeves at appropriate lengths (hundreds of metres) which will therefore be suitable for this purpose.

Insertion of an inner sleeve 70, 90 into the corrugated inner pipe 1 can be carried out by adapting known processes, such as pigging. Figures 13A and 13B show how pigging can be used to achieve insertion of an inner sleeve 70 into a corrugated inner pipe 1 of a corrugated hose. Pigs 111 ("pig" is a backronym for pipeline inspection gauge, or gadget) are commonly used for a variety of purposes in relation to pipelines -originally for inspection and maintenance, but other uses are known. The pig 111 is urged by pressure from one end of the pipeline to another -typically the pig 111 will be driven by compressed air or water. Here the pig 111 is used to insert the inner sleeve 70, 90 in a two stage process. It is practical to fit the inner sleeve 70, 90 this way as it has a clearance fit to the corrugated inner pipe 1, so the operation will not meet varied or excessive resistance. The pig 111 is attached to a cable 112, and then the pig 111 is driven (Figure 13A) through the corrugated inner pipe 1 by an appropriate pressure medium (for example compressed air, or water), pulling the cable 112 behind it. The cable 112 can then be used to drag the inner sleeve 70, 90 through the -17 -corrugated inner hose, and to position the ends of the inner sleeve 70, 90 correctly with respect to the ends of the corrugated inner pipe 1 for final assembly.

Using this approach, the cryogenic hose of Figure 3 (with inner sleeve 70, 90) can be used for transfer of cryogenic fluid with the risk of turbulence effectively addressed. The smooth inner bore of the inner sleeve prevents turbulent conditions from arising in the cryogenic fluid as transferred, and the leakage path prevents structural instability in the inner sleeve itself that would result from a pressure imbalance across the sleeve -at typical operating pressures, the pressure differential that would result without such a leakage path would be likely to lead to collapse of the liner layer.

Further embodiments of the hose and the inner sleeve, of methods of manufacture of both hose and inner sleeve and of cryogenic fluid transfer, will be apparent to the skilled person in accordance with the invention as here defined.

Claims

CLAIMS1. Hose for fluid transfer, the hose comprising a tubular inner hose for fluid transport and an outer hose part, wherein the tubular inner hose has a corrugated inner surface defining a bore of the inner hose, the inner hose further comprising an inner permeable tubular sleeve located within the bore of the inner hose, wherein an inner wall of the permeable tubular sleeve is substantially smooth.
2. Hose for fluid transfer as claimed in claim 1, wherein an outer wall of the inner sleeve forms a clearance fit with the corrugated inner surface.
3. Hose for fluid transfer as claimed in claim 1, wherein the hose is adapted for flow of cryogenic fluids.
4. Hose for fluid transfer as claimed in claim 3, wherein the inner hose is wrapped in one or more layers of superinsulation.
5. Hose for fluid transfer as claimed in claim 3 or claim 4, wherein the tubular inner hose has both corrugated inner and outer surfaces, and wherein the tubular inner hose is located within an outer hose part bore, a corrugated inner surface of the outer hose part defining the outer hose part bore.
6. Hose for fluid transfer as claimed in claim 5, wherein the outer hose part bore is adapted to provide a vacuum space between the outer hose part and the inner hose.
7. Permeable tubular sleeve for use in a hose for fluid transfer, the permeable sleeve comprising: a. a polymer composite internal layer; b. a permeable outer layer wrapped around the internal layer; wherein the internal layer is formed from a longitudinal sheet of polymer composite, the longitudinal sheet of polymer composite having been wrapped around the longitudinal axis, such that the internal layer has the form of an annular cylinder permeable to fluid.
8. Permeable tubular sleeve as claimed in claim 7, wherein the internal layer has a thickness of 0.2 to 0.6mm.
9. Permeable tubular sleeve as claimed in claim 7 or claim 8, wherein the polymer composite comprises polymer fibres embedded in a polymer matrix.
10. Permeable tubular sleeve as claimed in any of claims 7 to 9, wherein the polymer fibres and the polymer matrix comprise the same polymer or a copolymer thereof.
11. Permeable tubular sleeve as claimed in claim 9 or claim 10, wherein the polymer fibres and the polymer matrix comprise the same polyolefin or a copolymer thereof.
12. Permeable tubular sleeve as claimed in any of claims 9 to 11, wherein the polyolefin is polyethylene or polypropylene.
13. Permeable tubular sleeve as claimed in any of claims 9 to 12, wherein the polymer fibres consist of polypropylene or a copolymer thereof and the polymer matrix consists of polypropylene or a copolymer thereof.
14. Permeable tubular sleeve as claimed in any of claims 9 to 13, wherein the polymer fibres have a softening point which is higher than the softening point of the polymer matrix.
15. Permeable tubular sleeve as claimed in any of claims 9 to 14, wherein the polymer fibres of the internal layer are aligned either parallel to the longitudinal axis or orthogonal to the longitudinal axis.
16. Permeable tubular sleeve as claimed in any of claims 7 to 15, wherein the internal layer comprises a plurality of perforations.
17. Permeable tubular sleeve as claimed in any of claims 7 to 16, wherein the internal layer has a circumference which is greater than a sheet width defined between a first longitudinal side edge and a second longitudinal side edge of the longitudinal sheet, the longitudinally extending gap comprising a longitudinally extending break defined between the first longitudinal side edge and the second longitudinal side edge.
18. Permeable tubular sleeve as claimed in claim 17, wherein the permeable outer layer comprises two or more layers of polymer composite tape wound over the internal layer, wherein each of the two or more layers of polymer composite tape comprises a plurality of adjacent windings all applied at the same angle for that layer with respect to a longitudinal axis of the permeable sleeve, wherein adjacent windings in the layer are separated by a winding gap, and wherein the angle for one layer of the polymer composite tape differs from that of an adjacent layer of the polymer composite tape such that there is a permeable gap between each pair of adjacent layers.
19. Permeable tubular sleeve as claimed in claim 18, wherein for each layer the angle is between +/-25 and +/-85 degrees to the axis of the permeable sleeve.
20. Permeable tubular sleeve as claimed in claim 19, wherein for at least two adjacent layers the angle of a first layer of the two adjacent layers is equal and opposite to the angle of the second layer of the two adjacent layers.
21. Permeable tubular sleeve as claimed in any of claims 18 to 20, wherein a first layer of polymer composite tape wound over the internal layer is laid at substantially +/-80 degrees to the axis of the permeable sleeve.
22. Permeable tubular sleeve as claimed in any of claims 18 to 21, wherein the polymer composite tape is 10-20 mm wide.
23. Permeable tubular sleeve as claimed in claim 22, wherein the winding gap is -21 -1-3mm.
24. Permeable tubular sleeve as claimed in any of claims 18 to 23, wherein the polymer composite tape and the internal layer are formed of the same material.
25. Permeable tubular sleeve as claimed in any of claims 18 to 24, wherein the polymer composite tape is 0.2-0.8mm in thickness.
26. Permeable tubular sleeve as claimed in any of claims 18 to 25, wherein adjacent polymer composite tape layers are laser bonded to each other.
27. Permeable tubular sleeve as claimed in any of claims 18 to 26, wherein an innermost polymer composite tape layer is laser bonded to the internal layer.
28. Permeable tubular sleeve as claimed in any of claims 7 to 16, wherein the internal layer has a circumference which is lesser than a sheet width defined between a first longitudinal side edge and a second longitudinal side edge of the longitudinal sheet, the internal layer comprising a longitudinally extending break and an overlap region between a main cylinder part ending at the first longitudinal side edge and an internal flange part ending at the second longitudinal side edge.
29. Permeable tubular sleeve as claimed in claim 28, wherein the internal flange part abuts, but is not bonded to, the main cylinder part.
30. Permeable tubular sleeve as claimed in claim 28 or claim 29, wherein the permeable outer layer comprises a dry braided permeable sleeve.
31. Permeable tubular sleeve as claimed in claim 30, wherein the dry braided permeable sleeve comprises one or more of the following: glass fibre, polymer fibre (optionally aram id fibre), or carbon fibre.
32. Permeable tubular sleeve as claimed in claim 30 or claim 31, wherein the dry braided permeable tubular sleeve forms an interference fit with the internal layer.
-22 - 33. Hose for fluid transfer as claimed in any of claims 1 to 6, wherein the permeable tubular inner sleeve comprises the permeable sleeve of any of claims 7 to 32.
34. Insulated superconducting cable comprising a hose for fluid transfer as claimed in any of claims 1 to 6 or 33, with a superconducting cable disposed within the inner permeable tubular sleeve such that the inner hose is adapted for a conveying a low temperature fluid in the bore of the inner hose for cooling the superconducting cable.
35. The use of a hose for fluid transfer as claimed in any of claims 1 to 6 or 33 for conveying a fluid having a temperature below -150°C.
36. The use of the insulated superconducting cable of claim 34, further comprising providing a flow of a fluid having a temperature below -150°C, optionally liquid nitrogen, in the bore of the inner hose.
37. A method of manufacturing a permeable sleeve for use in a hose for fluid transfer, the permeable sleeve comprising a polymer composite internal layer and a permeable outer layer wrapped around the internal layer, the method comprising: d. providing a longitudinal sheet of polymer composite having a sheet width defined between a first longitudinal side edge and a second longitudinal side edge; e. wrapping the longitudinal sheet of polymer composite around the longitudinal axis to provide the internal layer such that the internal layer has the form of an annular cylinder permeable to fluid; f. wrapping the permeable outer layer around the internal layer.
38. The method of claim 37, wherein wrapping the longitudinal sheet of polymer composite in b. is achieved by: iii. conveying the longitudinal sheet of polymer composite in a direction -23 -of travel over rollers which bend the longitudinal sheet of polymer composite into a U-shaped preform; iv. passing the U-shaped preform through a cone-shaped funnel which is configured to wrap the U-shaped preform around a mandrel to provide the internal layer, and wherein in c. the internal layer has a longitudinally extending gap.
39. The method of claim 37 or claim 38, wherein the internal layer has a circumference which is greater than the sheet width, the longitudinally extending gap comprising a longitudinally extending break defined between the first longitudinal side edge and the second longitudinal side edge.
40. The method of claim 39, further comprising winding two or more layers of polymer composite tape over the internal layer to form the permeable outer layer, wherein each of the two or more layers of polymer composite tape comprises a plurality of adjacent windings all applied at the same angle for that layer with respect to a longitudinal axis of the permeable sleeve, wherein adjacent windings in the layer are separated by a winding gap, and wherein the angle for one layer of the polymer composite tape differs from that of an adjacent layer of the polymer composite tape such that there is a permeable gap between each pair of adjacent layers.
41. The method of claim 40, further comprising bonding an inner layer of polymer composite tape to an exterior surface of the internal layer by laser fusion.
42. The method of claim 40 or claim 41, wherein, after the winding of a first layer of wound polymer composite tape, any second and further layer(s) of wound polymer composite tape are bonded to the preceding layer of wound polymer composite tape by fusion.
43. The method of any of claims 40 to 42 which is configured as a continuous process.
-24 - 44 The method of claim 37, wherein the internal layer has a circumference which is lesser than the sheet width, the longitudinally extending gap comprising a longitudinally extending break and an overlap region with a radial gap between a main cylinder part ending at the first longitudinal side edge and an internal flange part ending at the second longitudinal side edge.
45. The method of claim 44, wherein wrapping the longitudinal sheet of polymer composite in b. is achieved by: iii. conveying the longitudinal sheet of polymer composite in a direction of travel over rollers into a forming cone; iv. passing the longitudinal sheet through the forming cone which is configured to wrap the longitudinal sheet into an tubular layer comprising a longitudinally extending break and an overlap region between a main cylinder part and an internal flange part.
46. The method of claim 44, further comprising heating the wrapped tubular layer to substantially 150 degrees Celsius and subsequently cooling the wrapped tubular layer to ambient temperature.
47. The method of any of claims 44 to 46, wherein the permeable outer layer comprises a dry braided permeable sleeve, and further comprising overbraiding or pulling the permeable sleeve on to the internal layer.
48. The method of claim 47, wherein the dry braided permeable sleeve forms an interference fit with the internal layer.