EP3926645A1

EP3926645A1 - An umbilical for combined transport of power and fluid

Info

Publication number: EP3926645A1
Application number: EP20305679.1A
Authority: EP
Inventors: Audun JOHANSON
Original assignee: Nexans SA
Current assignee: Nexans SA
Priority date: 2020-06-19
Filing date: 2020-06-19
Publication date: 2021-12-22

Abstract

The present invention relates to an umbilical for combined transport of electrical current and fluid, where the umbilical comprises at least one conductor arranged internally inside the umbilical, wherein the at least one conductor is in the form of a tubular member comprising a pipe-shaped conductor having an insulation system surrounding an external surface of the tubular member, the pipe-shaped conductor having a pipe wall made from an electrically conductive material, wherein an internal volume of the pipe-shaped conductor forms a transport pipe for a fluid, the fluid being in contact with an internal surface of the pipe-shaped conductor.

The present invention also relates to a system for such combined transport of electrical current and fluid.

Description

FIELD OF THE INVENTION

The present invention relates to umbilicals or cables having at least one power phase conductor, and more particularly subsea umbilicals or cables comprising at least one conductor made from high conductivity and hydrogen resistant materials for combined hydrogen transport.

BACKGROUND OF THE INVENTION

An umbilical may consist of a group of one or more types of elongated active umbilical elements, such as electrical phases, optical fiber cables, steel tubes and/or hoses, where the elongated elements are sheathed and, when applicable, armored for mechanical strength. Umbilicals are typically used for transmitting power, signals and fluids (for example for fluid injection or hydraulic power) to and from a subsea installation.
Generally, the cross-section of the umbilical is substantially circular, where the elongated elements are wound together either in a helical or in a S or Z pattern. In order to fill the voids between the various elements of the umbilical and to obtain the desired configuration, one or more filler components may be included within said voids.
Subsea umbilicals are installed at increasing water depths, commonly deeper than 1000 m. Such umbilicals have to be able to withstand severe loading conditions during their installation and their service life. Additional load bearing elements, such as armoring wires in the outer layers of the umbilical, are used to withstand the loads.
An umbilical may further comprise other optional or additional elements, for instance electrical and/or optical cable, thermoplastic hoses, polymeric external sheath(s) and polymeric filler component(s).
An umbilical comprising at least one power phase is often termed a power umbilical. Thus, a power umbilical includes one or more electrical power phases. These power phases are in the prior art formed from a conductor, where the conductor is formed from a plurality of strands.
EP 1.872.375 B1 which relates to the technical field of superconductors discloses a superconductive multi-phase, fluid-cooled cable system comprising a) a cable comprising at least three electrical conductors constituting at least two electrical phases and a zero- or neutral conductor, said electrical conductors being mutually electrically insulated from each other, and b) a thermal insulation defining a central longitudinal axis and having an inner surface and surrounding the cable, said inner surface of said thermal insulation forming the radial limitation of a cooling chamber for holding a cooling fluid for cooling said electrical conductors.
In general, it is cumbersome and expensive to manufacture such prior art umbilicals or cables due to the many elements such an umbilical may have, the space the elements take up or require and the bundling of the elements.
There is thus a need for alternatives to today's umbilicals or cables having at least one power phase conductor, or at least supplementary solutions for umbilicals or cables having at least one power phase conductor.
An object of the present invention is to provide an umbilical or cable which from a constructional point of view is simple and robust, and which may be used without the danger of collapse under various conditions.
A further object of the present invention is to seek to solve one or more of the problems or drawbacks according to prior art.
Yet another object of the present invention is to provide an umbilical for combined electrical and hydrogen transport.
These objects are achieved with an umbilical as defined in the independent claim 1. Advantageous embodiments of the present invention are indicated in the dependent claims.

SUMMARY OF THE INVENTION

The present invention relates to an umbilical for combined transport of electrical current and fluid, where the fluid may, for instance, be hydrogen, as well as a system for such combined transport, where the umbilical comprises at least one tubular member comprising a pipe-shaped conductor having an electrical insulation system surrounding an external surface of the tubular member, the pipe-shaped conductor having a pipe wall made from a conductive material, and wherein an internal volume of the pipe-shaped conductor forms a transport pipe for hydrogen, the hydrogen being in direct contact with the internal surface of the pipe-shaped conductor. The pipe-shaped conductor thus simultaneously conducts electrical current through the pipe wall, as well as transporting the fluid, for instance, hydrogen, through the internal volume of the pipe-shaped conductor.
The umbilical may further comprise at least one enclosing layer surrounding the internal elements and defining the umbilical.
The fluid, for instance hydrogen, may be in a liquid or gaseous form.
The umbilical for combined transport of electrical current and fluid according to the present invention may therefore be used for transmitting power and transporting fluid between two or more offshore installations. The liquid may, for instance, be a liquid hydrogen or a high-pressure gaseous hydrogen.
If, for instance, the umbilical for combined transport of electrical current and fluid is used for transmitting power and fluid between two offshore installations, one offshore installation may be a subsea installation and the other may be a floating installation, both offshore installations may be subsea installations or both installations may be floating installations.
However, it could also be envisaged that the umbilical for combined transport of electrical current according to the present invention could be used for transmitting power and transporting fluid between offshore and onshore installations or even between onshore installations.
The copper may be high purity copper such as an Electrolytic Tough Pitch (ETP) copper (for instance CW004A according to European standards); De-oxidized high purity copper (for instance CW008A or CW020A according to European standards), or high strength/high conductivity copper such as Copper-Nickel-Silicon alloy (for instance CW109C, CW111C, CW112C according to European standards); A beryllium containing copper alloy. The European standard, may, for instance, be EN1976.
The aluminium may be any wrought alloy with conductivity above approximately 50% IACS, including, but not limiting to AW1110, AW1350, AW1370, AW5005, AW6101, AW8030, AW8176, for instance, according to European standard EN1715 or EN573-3.
The tubular member, comprising a pipe-shaped conductor made from a conductive and in one embodiment hydrogen resistant material, may be manufactured by welding together a plurality of pipe segments, each individual pipe segment having a limited length. Alternatively, the tubular member may be manufactured continuously by an extrusion process or continuously forming a strip into a tubular shape and welding strip edges in an axial direction to form the continuous tubular member.
As used herein, the term "conductive and hydrogen resistant material" means that a material, on one hand, must have an ability to conduct an electrical current, and on the other hand, must not embrittle under mechanical loads when exposed to a hydrogen environment, either in form of gas or by electrochemical exposure. Testing if a material is resistant to hydrogen embrittlement may be determined according to methods such as slow strain rate tensile testing. According to this test methodology, hydrogen embrittlement is indicated by a significant reduction of ductility when subjected to tensile testing at slow strain rate under in a hydrogen environment- either by exposure to gas and/or under cathodic protection. This methodology is described in standards such as ASTM G142:98 (2016). Other standards for determining susceptibility to hydrogen embrittlement for specific applications- or for specific material groups are given in standards such as: ISO 11114-4:2017, ISO 7539-11:2914 or ASTM F1469:05-2017. The conductivity of the material may by measured according to IEC 60468 and is preferably above 30% IACS, more preferably above 50% IACS. The term "high conductivity" refers to above 50% IACS. In one aspect the conductive and hydrogen resistant material may be a copper or aluminium or alloys thereof.
In one aspect the insulation system may comprise an inner semiconducting layer, a solid insulation layer and an outer semiconducting layer.
In one aspect the umbilical may comprise a plurality of tubular members, for instance three, in order to manufacture a three-phase umbilical. In such an embodiment the plurality of tubular members may be wounded together in a stranded configuration.
In one aspect the umbilical may also comprise other appropriate or suitable functional elements such as fiber optical elements, additional conductors or tubular elements for transport of fluid(s).
As a person skilled in the art will know how the above-mentioned functional elements work and function and how they can be manufactured, this is not described any further herein.
For instance, in one embodiment the umbilical may comprises one tubular member, the tubular member comprising a pipe-shaped conductor and an insulation system arranged around an external surface of the tubular member and where the umbilical further comprises one fiber optical cable and a stranded conductor. A filler material may then be filled around and between the different elements of the umbilical in order to hold the different elements in a fixed position relative each other. Each pipe-shaped conductor is made from a high conductivity and hydrogen resistant materials.
In another embodiment the umbilical may comprise three tubular members, each tubular member comprising a pipe-shaped conductor and an insulation system, and in addition two fiber optical cables and a stranded conductor. Each pipe-shaped conductor is made from a high conductivity and hydrogen resistant materials. A filler material may then be filled around and between the different elements of the umbilical in order to hold the different elements in a fixed position relative each other.
However, it should be understood that the umbilical could be manufactured only or solely from the above-mentioned tubular members, thereby not comprising any of the above-mentioned functional elements, where the umbilical could comprise, for instance, three tubular members, each tubular member comprising a pipe-shaped conductor and an insulation system and without any further of the above-mentioned functional elements. A filler material may then be filled around and between the different elements of the umbilical in order to hold the different elements in a fixed position relative each other.
In one aspect the filler material may be in the form of stiff elongated plastic elements.
In one aspect a steel armoring may be arranged around an outer surface of the umbilical. The steel armoring may be arranged in several layers, in different patterns or directions or the like, such that the steel armor could take up axial and/or radial stresses in the umbilical. A person with skill in the art would know how such steel armoring is to be arranged, whereby this is not described any further herein.
In one aspect the umbilical may further comprises a filler material in the form of stiff elongate plastic elements located at least partially around and between the at least one tubular member, the number of tubular members and stiff plastic elements being gathered in a twisted bundle by means of a laying operation.
In yet another aspect, the present invention comprises a system for the combined transport of electrical current and fluid, where the fluid may, for instance, be hydrogen. According to this aspect, an umbilical is provided that comprises at least one pipe-shaped conductor as described above. The umbilical may therefore be arranged between a first location and a second location, where the umbilical may be utilized for combined transport of electrical current and fluid between the first location and the second location. An electrical source may then be connected to the pipe wall of the pipe-shaped conductor in order to conduct electrical current between the two locations. A source of fluid, for instance hydrogen, is connected to the internal volume of the pipe-shaped conductor in order to transport the fluid between the two locations simultaneously with the electrical current.
The fluid, for instance hydrogen, may be in a liquid or gaseous form.
An example of the use of such a system for combined transport of electrical current and fluid is in connection an energy or power producing installation or plant, for instance combined production of electricity and hydrogen at wind turbine installations. It is also known to produce hydrogen as a storage medium from excess electrical production. The system for combined transport of electrical current and fluid would be useful for simultaneously transporting both the electrical current and fluid for such an installation to a second installation.

BRIEF DESCRIPTION OF THE FIGURES

Other advantages and characteristic features of the present invention will be seen clearly from the following detailed description, the appended figures and the following claims, wherein:

Figure 1 is a cross-sectional view of prior art power umbilical comprising stranded conductors,
Figure 2 is a sectional view of a stranded conductor used in prior art power umbilicals,
Figure 3 is a cross-sectional view of a tubular member used in the umbilical according to the present invention,
Figure 4 is a cross-sectional view of an umbilical comprising tubular members according to the present invention, and
Figure 5 is a schematic illustration of an example application of the umbilical according to figure.

DETAILED DESCRIPTION

Figure 1 shows a power umbilical 1 according to prior art. The power umbilical 1 comprises two conductors 2 and is suitable for providing a power supply. Each conductor 2 is surrounded by various sheaths 6 for insulation and protection of said conductor 2. As can be seen, the power umbilical 1 comprises also an optical fiber cable 3, where also the optical fiber cable 3 is surrounded by various sheaths and a pipe 9 through which a liquid can be conducted through. The conductors 2, the optical fiber cable 3 and the pipe 9 are supported within the surrounding protective sheaths 5 of the power umbilical 1 by a filler material 4. The purpose of the filler material 4 is to hold the conductors 2 and the optical fiber cable 3 in a fixed position relative to each other and to provide a circular cross-section. The surrounding sheaths 5 prevent intrusion of water into the power umbilical 1. Furthermore, remaining voids in the power umbilical 1 may be filled with a liquid filler to further prevent intrusion of water.
The conductors 2, the optical fiber cable 3 and the pipe 9 may also, in different ways, be bundled together.
Figure 2 shows one power phase comprising a single conductor 2. The conductor 2 comprises a plurality of metallic strands 8 made from, for instance, copper, aluminium or different alloys, where the plurality of metallic strands 8 is bundled or wrapped together to form the conductor 2. Due to the form of the metallic stands 8, a multiple of voids 7 will be provided between the metallic strands 8 in a longitudinal direction of the power umbilical 1.
The lay-up of the metallic strands 8, as well as pressing the metallic strands 8 closer together may contribute to lessen the size of the longitudinal voids 7, but this procedure will not remove the voids 7 entirely.
Such conductors 2 are thus vulnerable towards detrimental accumulation of gasses and water in the longitudinal voids 7.
Figure 3 shows a tubular member 11 of an umbilical 10 according to the present invention, where it can be seen that the tubular member 11 comprises a pipe or tubing manufactured from a conductive and in one embodiment hydrogen resistant material, thereby providing a pipe-shaped conductor 12 in the umbilical 10.
The pipe-shaped conductor 12 may in one embodiment be manufactured from a copper or aluminium alloy.
However, it should be understood that the pipe-shaped conductor 12 also could be manufactured from other materials, where the copper may be a high purity copper such as an Electrolytic Tough Pitch (ETP) copper (for instance CW004A according to European standards); De-oxidized high purity copper (for instance CW008A or CW020A according to European standards), or high strength/high conductivity copper such as Copper-Nickel-Silicon alloy (for instance CW109C, CW111C, CW112C according to European standards) or a beryllium containing copper alloy.
An internal volume 17 of the pipe-shaped conductor 12 will then form a transport pipe for fluid such as hydrogen. The hydrogen may be a liquid hydrogen or a high-pressure gaseous hydrogen. The hydrogen will be in direct contact with an inner circumference or surface of the pipe-shaped conductor 12.
The pipe-shaped conductor 12 will have a pipe wall 12A.
An outer circumference of the pipe-shaped conductor 12 is electrically insulated through an isolation system 16, where the isolation system 16 comprises an inner semiconducting layer, a solid insulation layer and an outer semiconducting layer.
Figure 4 shows an umbilical 10 according to the present invention, where the umbilical 10 in this exemplary embodiment comprises three power phases with pipe-shaped conductors 12 and a fiber optical cable 13. As mentioned above, the pipe-shaped conductors 12 and also the fiber optical cable 13, are insulated through the insulation system 16.
Furthermore, the pipe-shaped conductors 12 and the fiber optical cable 13 are supported within the surrounding protective sheaths 15 of the umbilical 10 by a filler material 14. The purpose of the filler material 14 is to hold the pipe-shaped conductors 12 and the fiber optical cable 13 in a fixed position relative to each other. The outer layers 15 protect the inner elements and prevent intrusion of water into the umbilical 10.
However, it is to be understood that the umbilical 10 according to the present invention may comprise other appropriate or suitable functional elements, such as fiber optical elements, additional conductors or tubular elements for transport of other non-hydrogen agents.
For instance, in one embodiment the umbilical 10 may comprises one tubular member 11, the tubular member 11 comprising a pipe-shaped conductor 12 and an insulation system 16 arranged around an external surface of the tubular member 11 and where the umbilical 10 further comprises one fiber optical cable 13 and a stranded conductor. A filler material 14 may then be filled around and between the different elements of the umbilical 10 in order to hold the different elements in a fixed position relative each other. Each pipe-shaped conductor 12 is made from a high conductivity and hydrogen resistant materials.
In another embodiment the umbilical 10 may comprise three tubular members 11, each tubular member 11 comprising a pipe-shaped conductor 12 and an insulation system 16, and in addition two fiber optical cables 13 and a stranded conductor. Each pipe-shaped conductor 12 is made from a high conductivity and hydrogen resistant materials. A filler material 14 may then be filled around and between the different elements of the umbilical in order to hold the different elements in a fixed position relative each other.
However, it should be understood that the umbilical 10 could be manufactured only or solely from the above-mentioned tubular members 11, thereby not comprising any of the above-mentioned functional elements, where the umbilical 10 could comprise, for instance, three tubular members 11, each tubular member 11 comprising a pipe-shaped conductor 12 and an insulation system 16 and without any further of the above-mentioned functional elements. A filler material 14 may then be filled around and between the different elements of the umbilical 10 in order to hold the different elements in a fixed position relative each other.
In one aspect a steel armoring may be arranged around an outer surface of the umbilical 10. The steel armoring may be arranged in several layers, in different patterns or directions or the like, such that the steel armor could take up axial and/or radial stresses in the umbilical 10. A person with skill in the art would know how such steel armoring is to be arranged, whereby this is not described any further herein.
Figure 5 shows in a schematic way an embodiment of an umbilical 10 for combined transport of electrical current and fluid, as well as the system S for such combined transport, where the umbilical 10 and the system are used for simultaneously transporting both the electrical current and the fluid from a first installation to a second installation.
The umbilical 10 for combined transport of electrical current and fluid is employed between the first installation, the first installation being an energy or power producing plant 20 in form of a wind turbine installation and to the second installation, the second installation being an oil and gas exploration and production facility 30 to provide electrical current and fluid from the energy or power producing plant 20 to the oil and gas exploration and production facility 30.
The oil and gas exploration and production facility 30 comprises a derrick, a hoist system, a circulation system and power system(s), where one or more energy systems for supply of current and fluid are used to operate and run the above-mentioned systems.
An electrical source, such as a wind turbine, on the energy or power producing plant 20 will then, in appropriate ways, be connected to a pipe wall 12A of one end of the pipe-shaped conductor 12, while a source of hydrogen on the energy or power producing plant 20 will, in appropriate ways, be connected to the internal volume 17 of this end of the pipe-shaped conductor 12. Similarly, a pipe wall 12A and an internal volume 17 of an opposite end of the pipe-shaped conductor 12 will, in appropriate ways, be connected to the one or more energy systems for supply of current and fluid on the oil and gas exploration and production facility 30 in order to conduct the electrical current and fluid from the energy or power producing plant 20 to the energy systems for supply of current and fluid of the oil and gas exploration and production facility 30.
The umbilical 10 for combined transport of electrical current and fluid as well as the system S for such combined transport are also susceptible to being used in one or more of the following applications:

between a first and second installation, where each of the first and second installation is arranged onshore, or
between a first and second installation, where one of the installations is arranged offshore and the other installation is arranged offshore.

The invention has now been explained with several non-limiting exemplary embodiments. One skilled in the art will appreciate that a variety of variations and modifications can be made to the umbilical for combined transport of electrical current and fluid, as well as for the system for such combined transport as described within the scope of the invention as defined in the appended claims.

Claims

An umbilical (10) for combined transport of electrical current and fluid, where the umbilical (10) comprises at least one conductor arranged internally within the umbilical (10), characterized in that the at least one conductor is in the form of a tubular member (11) comprising a pipe-shaped conductor (12) having an insulation system (16) surrounding an external surface of the tubular member (11), the pipe-shaped conductor (12) having a pipe wall (12A) made from an electrically conductive material, and wherein an internal volume (17) of the pipe-shaped conductor (12) forms a transport pipe for a fluid, the fluid being in direct contact with an internal surface of the pipe-shaped conductor (12).
The umbilical (10) according to claim 1,
wherein the fluid is hydrogen, the hydrogen being in a liquid or gaseous form.
The umbilical (10) according to claim 1 or 2,
wherein the pipe-shaped conductor (12) is made from a hydrogen resistant material determined according to ASTM G142:98-2016 and that the umbilical (10) is arranged to simultaneously transport electrical current and hydrogen.
The umbilical (10) according to any one of the claims 1-3,
wherein the pipe-shaped conductor (12) is made from copper, aluminium or an alloy thereof.
The umbilical according to claim 4,
wherein the pipe-shaped conductor (12) is made of a material selected from the following list of materials: CW004A, CW008A, CW020A, CW109C, CW111C, CW112C, a beryllium containing copper, in accordance with European standard EN1976; or AW1110, AW1350, AW1370, AW5005, AW6101, AW8030, AW8176, in accordance with European standard EN1715 or EN573-3.
The umbilical (10) according to any one of the preceding claims,
wherein the insulation system (13) comprises an inner semiconducting layer, a solid insulation layer and an outer semiconducting layer.
The umbilical (10) according to any of the preceding claims,
wherein the umbilical (10) comprises a plurality of tubular members (11),
the plurality of tubular members (11) being wounded together in a stranded configuration.
The umbilical (10) according to any preceding claims,
wherein umbilical (10) further comprise separate functional elements such as fiber-optical elements, additional conductors or tubular elements for transport of other non-hydrogen agents.
The umbilical (10) according to any preceding claims,
wherein a filler material (14) is arranged at least partly around the at least one tubular element (11).
The umbilical (10) according to claim 9,
wherein the filler material is in form of stiff elongate plastic elements, the plurality of tubular elements (11) and stiff plastic elements being gathered in a twisted bundle by means of a laying operation.
The umbilical according to any preceding claims,
wherein a steel armoring is wounded around an outer surface of the umbilical (10) to take up axial stresses.
The umbilical according to any preceding claims
wherein a steel armoring is wounded around an outer surface of the umbilical (10) to take up radial stresses for internal hydrogen pressure.
A system for a combined transport of electrical current and a fluid from a first location (20) to a second location (30), the system comprising:
- an umbilical (10) according to any of the preceding claims 1-12,

- an electrical source connected to the pipe wall (12A) of the at least one pipe-shaped conductor (12),

- a source of fluid connected to the internal volume (17) of the pipe-shaped conductor (12),

- wherein the pipe-shaped conductor (12) is arranged to simultaneously transport electrical current and fluid between the first location (20) and second location (30).
The system according to claim 13, wherein the fluid is hydrogen, the hydrogen being in a liquid or gaseous form.
The system according to claim 13 or 14, wherein the first location (20) is an offshore wind turbine installation of the type that produces both electrical current and hydrogen as a storage and transport medium for excess electrical current production.