Mooring line for a floating platform comprising a part comprising an elastomeric material

Abstract

To provide a mooring rope capable of reducing cost while coping with severe environmental conditions such as facing shallow sea.SOLUTION: Wherein the mooring line comprises a part 24 comprising two leading ends 26, 28, wherein the strand 30 comprises an elastomeric material and extends between the two leading ends along a longitudinal direction L when the strand is subjected to tensile stress, each strand has two ends 44 and a central portion 46 along the longitudinal direction, the central portion having a cross section S with an elongated shape in a first transverse direction T1 perpendicular to the longitudinal direction and having a breadth T2 in a second transverse direction L2 perpendicular to the first transverse direction; At least one of the two leading ends comprises steel and is configured to be subjected to a tensile stress, and one of the two ends has an extension of maximum width along the second transverse direction when the strands are at rest and parallel to each other, the maximum width being greater than the width.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to mooring lines intended for tethering to floating platforms, in particular wind turbine platforms, and mooring systems for anchoring to the seabed.

[0002] The present disclosure also relates to a floating platform, a mooring system, and an assembly comprising at least such a mooring line. [Background technology]

[0003] Floating platforms need to be moored to the seabed, which is challenging for wind turbine platforms as the relatively shallow waters and potentially harsh environmental conditions subject the assembly to dynamics with large tension peaks in the mooring lines.

[0004] Generally, mooring lines are very long relative to the water depth, providing sufficient flexibility for the mooring system to maintain tension below an acceptable level. In a typical mooring system, mooring lines can be more than 10 times longer than the water depth in shallow waters and harsh environmental conditions, leading to high mooring costs.

[0005] Several known systems have been proposed to address this problem by providing elasticity in the mooring lines, however, none of them are considered satisfactory.

[0006] For example, mechanical components using stainless steel have been proposed, but there are questions about their integrity over a 20 year service life in seawater and their practical cost effectiveness.

[0007] It has been proposed to use elasticity in the mooring lines provided by elastomeric materials, however serious problems have arisen regarding the interface between such materials and the rest of the mooring lines. Summary of the Invention [Problem to be solved by the invention]

[0008] SUMMARY OF THE INVENTION It is an object of the present invention to overcome or reduce the above problems and to provide a mooring line that is less expensive while still being able to cope with the harsh environmental conditions encountered in shallow waters. [Means for solving the problem]

[0009] To this end, the invention proposes a mooring line intended to connect a floating platform, in particular a wind turbine platform, to a mooring system fixed to the seabed, the mooring line comprising the parts: The part comprises two ends and a plurality of strands including an elastomeric material, the strands extending between the two ends along a longitudinal direction when each strand is subjected to a tensile stress; Each strand has two longitudinal ends and a central portion, the central portion has a transverse cross-section perpendicular to the longitudinal direction, the transverse cross-section having an elongated shape when the strand is at rest, the elongated shape defining a length in a first transverse direction perpendicular to the longitudinal direction and a width in a second transverse direction perpendicular to the longitudinal direction and the first transverse direction; At least one of the two tip portions includes steel and is configured to apply a respective tensile stress to one of the two ends of each strand; One of the two ends of each strand has a maximum width extension along the second transverse direction when the strands are at rest and parallel to each other, and the maximum width of one of the two ends is greater than the width of the elongated shape.

[0010] In another embodiment, the mooring line may include one or more of the following features, either alone or in any technically feasible combination: - the cross section is rectangular with rounded corners, the ratio of the length of the elongated shape divided by the width of the elongated shape is between 3.0 and 20, preferably between 5.0 and 10; the ratio of said maximum width divided by the width of the elongated shape is between 1.3 and 6; one of the two tips defines a plurality of primary housings and includes a plurality of occlusion members, each primary housing configured to receive a respective one of the occlusion members to form a secondary housing configured to receive the extension portion, the extension portion configured to be retained in the secondary housing; the extension portion has a diverging shape away from the central portion with an increasing width defined along a second transverse direction, and the secondary housing has a diverging shape configured to cooperate with the diverging shape of the extension portion to retain the extension portion on the secondary housing; each primary housing is defined by two opposing walls along the second transverse direction, the extension portion defines two side surfaces along the second transverse direction, and each closure member defines two opposing surfaces configured to respectively face contact one of the two walls and one of the two side surfaces along the second transverse direction, the other of the two side surfaces being in face contact with the other of the two walls; the two opposing walls define a shape that widens away from the central portion with an increasing width defined along a second transverse direction, and the two opposing faces define a width along the second transverse direction, the width narrowing away from the central portion; one of the two ends of each strand comprises two branches made of an elastomeric material, the two branches projecting longitudinally from the extension portion and spaced apart from each other in a second transverse direction, and a wedge member fixed to the two branches and extending between the two branches in the second transverse direction; - the strands form a plurality of loops, each loop comprising one of two ends of one strand and one of two ends of another strand, and one of the two ends comprising a plurality of supports partially surrounded by one of the loops, each support being configured to apply a stress to one of the loops, the stress being the sum of two of the tensile stresses; - each support extends along a first transverse direction, and each loop at least partially surrounds one of the supports in the first transverse direction; each loop is formed by two strands, said two strands being contiguous in a second transverse direction; each support is made of a low friction material such as PTFE in contact with one of the loops; one of said two tip portions comprises a main portion, and each support comprises a shaft movable relative to the main portion between an attached position in which the shaft is attached to the main portion and a rest position in which the shaft is spaced apart from the main portion, and a marginal portion at least partially surrounding the shaft.

[0011] The present invention provides - a floating platform adapted to float on a body of water, preferably a wind turbine platform; - Mooring systems adapted to be anchored to the seabed, and - at least one mooring line connected to the platform and to the mooring system, the mooring line being as described above; An assembly member is also proposed, comprising:

[0012] The present disclosure and its advantages will be better understood from reading the following description, given purely by way of example, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a schematic side view of an assembly according to the present invention; [Figure 2] FIG. 2 is a partial schematic view of the mooring lines shown in FIG. 1. [Figure 3] 3 is a partial perspective view of the components shown in FIG. 2 according to the first embodiment, the components being shown in a vertical position. [Figure 4] FIG. 4 is a perspective view of the tip of the component shown in FIG. 3. [Figure 5]5 is a partial cross-sectional view of the tip portion shown in FIG. 4, showing how some strands of the part traverse along a plane and how the strands are connected to the tip portion. [Figure 6] FIG. 3 is a perspective view of the tip of the component shown in FIG. 2 according to a second embodiment. [Figure 7] FIG. 7 is a partial cross-sectional view of the tip shown in FIG. 6, showing how some strands of the part traverse along a plane and how the strands are connected to the tip. DETAILED DESCRIPTION OF THE INVENTION

[0014] [Detailed Description of the Invention] [Assembly parts] Referring to FIG. 1, an assembly 10 according to the present invention will now be described.

[0015] The assembly comprises a platform 12 suitable for floating on a body of water 14 , a wind turbine 16 advantageously supported on the platform, and a mooring system 18 adapted to be fixed to the seabed 20 .

[0016] The assembly 10 includes a platform 12 and mooring lines 22 connected to a mooring system 18 .

[0017] The assembly 10 may advantageously include other mooring lines (not shown), such as mooring lines similar to the mooring lines 22, and / or other mooring systems (not shown). In a particular embodiment (not shown), the platform 12 is tethered to two additional mooring lines.

[0018] The body of water 14 may be an ocean, a sea or a lake. The body of water 14 has a depth H relative to the vertical direction V, for example comprised between 50 m and 600 m, advantageously between 50 m and 200 m.

[0019] [Mooring rope] The mooring lines 22 advantageously have a length in shallow waters that is less than 6 times the water level H. "Shallow water" means for example a water depth between 50 and 150 m.

[0020] Thus, the mooring lines 22 according to the present invention are shorter than conventional mooring lines, particularly conventional all-chain configurations, which are typically longer than eight or more times the water level H. This reduction in length represents a significant cost savings.

[0021] For example, if the water level H is about 70 m high, a conventional mooring line would have a length of approximately 700 m, while the mooring line 22 has a length of less than 400 m with a comparable or lower extreme tension.

[0022] The mooring line 22 comprises a part 24 having two ends 26, 28 and a plurality of strands 30 (FIG. 3) that extend between the two ends along a longitudinal direction L when each strand 30 is subjected to a tensile stress F.

[0023] In the example shown in Figure 1, the mooring line 22 has a stationary portion 32 that rests on the seabed 14 and an uplifted portion 34 that is away from the seabed.

[0024] In a variant (not shown), the mooring line 22 does not have a stationary portion on the seabed, particularly in the case of a tote mooring.

[0025] In this example, the mooring line 22 comprises an upper part 36 that connects the platform 12 and one of the two extremities 26, 28 of the part 24, and a lower part 38 that connects the mooring system 18 and the other of the two extremities 26, 28.

[0026] In one variation (not shown), there is no upper part 36 and the tip 26 is connected to the platform 12 .

[0027] In another variation (not shown), the tip 28 does not have the lower part 38 and is connected to the mooring system 18 .

[0028] In another variation (not shown), mooring line 22 may comprise one or more parts (not shown) similar to part 24 connected to each other or to intermediate parts (not shown).

[0029] The upper part 36 and / or the lower part 38 are, for example, made of steel, in particular of steel wire or metal chain, as shown in FIG.

[0030] In one variant, the upper part 36 and / or the lower part 38 are made of synthetic rope, in particular synthetic polyester rope or nylon rope.

[0031] In another variation, the upper and / or lower components 36, 38 may be comprised of multiple sub-components (not shown), each of which may be made of a different material, such as steel or polyester.

[0032] Thus, the upper and lower parts 36, 38 have significant stiffness, particularly greater stiffness than part 24.

[0033] [Parts of the mooring rope according to the first embodiment] The first embodiment will now be described with reference to FIGS.

[0034] The part 24 is advantageously located in a raised portion 34 to avoid wear caused by the seabed 14 .

[0035] Component 24 may be positioned at any height along the vertical direction V of raised portion 32. However, component 24 is preferably positioned sufficiently deep below surface 42 of body of water 14, particularly greater than 20 meters, to avoid UV exposure and limit marine life growth.

[0036] Advantageously, the part 24 comprises between 30 and 350 strands, for example between 30 and 150 strands, preferably between 40 and 130 strands, and for example 64 strands.

[0037] The part 24 preferably has a length L0 of 10 m to 30 m when at rest.

[0038] The part 24 may provide a maximum extension of more than 100% of the part's rest length, advantageously more than 300%, and even more advantageously more than 500%.

[0039] Typically, the part 24 has a maximum elongated length of more than 10 meters.

[0040] The elasticity of the part 24 is provided by the elastomeric material, which makes it possible to limit the maximum tension that the mooring line 22 can withstand.

[0041] The part 24 has a minimum breaking strength of more than 15 MPa, preferably more than 18 MPa, advantageously more than 22 MPa.

[0042] The segment 24 has a minimum breaking load of more than 400T, advantageously more than 1200T.

[0043] The component 24 has a creep of less than 20%, advantageously less than 10%.

[0044] Creep is the permanent elongation of a polymer under a constant load from its initial length L0, where initial length means the length L0 at the beginning of the service life without load.

[0045] [Strand] Advantageously, the strands 30 are structurally similar to one another: they therefore have substantially the same mechanical properties, in particular the same maximum elongation and minimum breaking strength.

[0046] The strands 30 comprise an elastomeric material.

[0047] Preferably, the strands 30 are free of any metal.

[0048] The strands 30 are advantageously free of other materials or mechanical components in addition to the elastomeric material.

[0049] The monolithic material constituting the strands 30 is selected, for example, from natural rubber, thermoplastic elastomers, polychloroprene, nitrile butadiene rubber (NBR) and hydrogenated nitrile butadiene rubber (HNBR). The monolithic material is advantageously vulcanized.

[0050] Each strand 30 has two ends 44 and a central portion 46 along the longitudinal direction L.

[0051] For example, strands 30 are at least partially coated with a protective composition 48, eg, to prevent staining.

[0052] [Central part of strand] The central portion 46 has a cross section S perpendicular to the longitudinal direction L (FIG. 3).

[0053] The transverse cross-section S has an elongated shape when the strand 30 is at rest, and the elongated shape defines a length L1 in a first transverse direction T1 perpendicular to the longitudinal direction L, and a width L2 in a second transverse direction T2 perpendicular to the longitudinal direction L and the first transverse direction T1. In other words, the transverse cross-section S is elongated in the first transverse direction T1, and the length L1 is greater than the width L2.

[0054] The cross section S is, for example, rectangular with rounded corners 50 .

[0055] The ratio of the length L1 of the elongate shape divided by the width L2 of the elongate shape is advantageously between 3.0 and 20, preferably between 5.0 and 10.

[0056] For example, the length L1 is between 200 mm and 350 mm.

[0057] For example, the width L2 is between 30 mm and 50 mm.

[0058] Strand Ends The two ends 44 of each strand are advantageously similar to each other.

[0059] The end 44 has an extension 52 of maximum width L3 along the second transverse direction T2 when the strands 30 are at rest and parallel to one another (i.e., without any twisting relative to the longitudinal direction L). The end 44 advantageously comprises two branches 54 and a wedge member 56.

[0060] The maximum width L3 of the end portion 44 is greater than the width L2 of the elongated shape.

[0061] The extension portion 52 defines two side surfaces 58 along the second transverse direction T2.

[0062] The ratio of the maximum width L3 divided by the maximum width L2 of the elongated shape is advantageously between 1.3 and 6.

[0063] For example, the extension portion 52 has a shape that widens away from the central portion 46 with an increasing width L3 defined along the second transverse direction T2.

[0064] Two branches 54 comprise an elastomeric material and protrude from the extension portion 52 in the longitudinal direction L and are spaced apart from each other, for example, in the second transverse direction T2.

[0065] The wedge members 56 are, for example, fixed to the two branches 54 and extend between the two branches in the second transverse direction T2.

[0066] [Tip of part] Advantageously, the two tips 26, 28 are structurally similar to each other.

[0067] The two tips 26, 28 include, and are advantageously made of, steel and are configured such that each tensile stress is applied to one of the two ends 44 of each strand 30.

[0068] The two extremities 26, 28 define one or more attachment points 59 for connection to other components of the platform 12 or the mooring system 18. In an embodiment, each of the two extremities 26, 28 includes two plates 60, 62, each defining two openings 64, 66.

[0069] In the first embodiment, the two tips 26, 28 comprise a plate 67, for example defining a plurality of primary housings 68, and comprising a plurality of closure members 70.

[0070] For example, plate 67 extends perpendicular to the longitudinal direction.

[0071] Each primary housing 68 is configured to receive one of the occlusion members 70 to form a secondary housing 72 configured to receive the extension portion 52 of the end 44 and to retain the extension portion.

[0072] The primary housings 68 advantageously form a row of housings in a first transverse direction T1 and / or a second transverse direction T2.

[0073] For example, each primary housing 68 is defined by two opposing walls 74 along the second transverse direction T2.

[0074] Secondary housing 72 has an expanding shape configured to cooperate with the expanding shape of extension portion 52 to retain said extension portion on the secondary housing.

[0075] Each closure member 70 defines two opposing surfaces 76 configured to be in face contact with one of the two walls 74 and one of the two side surfaces 59 along the second transverse direction T2, and the other of the two side surfaces is in face contact with the other of the two walls 74.

[0076] The two opposing walls 74 advantageously define a shape that widens away from the central portion 46 with an increasing width L4 defined along the second transverse direction T2.

[0077] The two opposing surfaces 76 advantageously define a width L5 along the second transverse direction T2, said width L5 narrowing with increasing distance from the central portion 46.

[0078] [Mooring rope components according to the second embodiment] A second embodiment will now be described with reference to FIGS.

[0079] The second embodiment is similar to the first embodiment shown in Figures 3 to 5. Similar elements have the same reference numbers and will not be described again. Only the differences are described in detail below.

[0080] In the second embodiment, only the two ends 44 and the two tips 26, 28 of the strand 30 differ from the first embodiment.

[0081] The strands 30 advantageously form a plurality of loops 78. Each loop 78 comprises an end 44 of one strand 30 and an end of another strand. These two end portions 44 advantageously connect directly to one another to form one of the loops 78.

[0082] For example, the loop 78 is obtained by joining the slip 80 to itself. Advantageously, the joining 82 is located inside the extension portion.

[0083] For example, each loop 78 is formed from two strands 30, said two strands being continuous in the second transverse direction T2.

[0084] The two tips 26 , 28 include a main portion 84 and a plurality of supports 86 partially surrounded by the loops 78 .

[0085] Each support 86 is configured to apply a force F1 to one of the loops 78, said force F1 being the sum of two tensile forces F2, F3 applied to the strands 30.

[0086] Each support 86 advantageously comprises a low friction material, such as PTFE, in contact with one of the loops 78 .

[0087] For example, each support 86 includes a shaft 88 that is movable relative to main portion 84 between a mounted position in which the shaft is mounted to the main portion and a rest position in which the shaft is spaced apart from the main portion. For example, each support 86 includes a peripheral portion 90 that surrounds shaft 88.

[0088] For example, each support 86 extends along a first transverse direction T1, and each loop 78 partially surrounds one of the supports 86 in the first transverse direction T1.

[0089] For example, the main portion 84 comprises a plurality of plates 92 extending perpendicular to the first transverse direction T1, each plate defining an opening 94, and the shaft 88 being received in two of the openings 84, the two openings being in two different plates among the plates 92.

[0090] [advantage] Thanks to the above-described features, the mooring line 22 is inexpensive yet able to withstand harsh environmental conditions such as those encountered in shallow waters.

[0091] In particular, the component 24 can reduce the length while limiting the maximum tension supported by the mooring line 22. Indeed, the elastomeric material provides the elasticity that allows the mooring line 22 to withstand harsh environmental conditions.

[0092] The elongated shape of the central portion 46 of the strand 30 enhances the vulcanization process.

[0093] The extensions 52 at the two ends 44 provide an improved interface between the strand 30 and the two tips 26,28.

[0094] In particular, in the second embodiment, the loop 78 provides a strong interface. [Explanation of symbols]

[0095] 10 Assembly parts 12 Platform 22 Mooring line 24 parts 26, 28 Tip 30 strands 44 End 46 Central part 52 Extension 54 Two Branches 56 Wedge member 68 Primary Housing 70 Closure member 72 Secondary Housing 78 Loops 84 Main parts 86 Support 88 Shaft

Claims

1. A mooring line (22) intended to connect a floating platform (12), in particular a wind turbine platform, to a mooring system (18) fixed to the seabed (20), the mooring line comprising a part (24), The part (24) comprises two end portions (26, 28) and a plurality of strands (30) including an elastomeric material, and the strands (30) extend between the two end portions (26, 28) along a longitudinal direction (L) when each strand (30) is subjected to a tensile stress (F, F1, F2); Each strand (30) has two ends (44) and a central portion (46) along the longitudinal direction (L); the central portion (46) has a transverse cross-section (S) perpendicular to the longitudinal direction (L), the transverse cross-section (S) having an elongated shape when the strand (30) is at rest, the elongated shape defining a length (L1) in a first transverse direction (T1) perpendicular to the longitudinal direction (L) and a width (L2) in a second transverse direction (T2) perpendicular to the longitudinal direction (L) and the first transverse direction (T1); At least one of the two tip portions (26, 28) comprises steel and is configured such that a respective tensile stress (F, F2, F3) is applied to one of the two ends (44) of each strand (30); one of the two ends (44) of each strand (30) has an extension (52) of a maximum width (L3) along the second transverse direction (T2) when the strands (30) are at rest and parallel to each other, the maximum width (L3) of one of the two ends (44) being greater than the width (L2) of the elongated shape; Mooring line (22).

2. 2. A mooring line (22) according to claim 1, wherein the cross section is rectangular with rounded corners (50).

3. 2. A mooring line (22) according to claim 1, wherein the ratio of the length (L1) of the elongated shape divided by the width (L2) of the elongated shape is between 3.0 and 20.

4. 4. A mooring line (22) according to claim 3, wherein the ratio of the length (L1) of the elongated shape divided by the width (L2) of the elongated shape is between 5.0 and 10.

5. 2. A mooring line (22) according to claim 1, wherein the ratio of the maximum width (L3) divided by the width (L2) of the elongated shape is between 1.3 and 6.

6. 6. A mooring line (22) according to any one of claims 1 to 5, wherein one of the two tip portions (26, 28) defines a plurality of primary housings (68) and comprises a plurality of closure members (70), each primary housing (68) configured to receive one of the closure members (70) to form a secondary housing (72) configured to receive the extension portion (52), the extension portion (52) being configured to be retained in the secondary housing (72).

7. - said extension portion (52) has a shape that widens away from the central portion (46) with an increasing width (L3) defined along a second transverse direction (T2); and A mooring line (22) according to claim 6, wherein the secondary housing (72) has an expanding shape configured to cooperate with the expanding shape of the extension portion (52) to retain the extension portion (52) in the secondary housing (72).

8. - each primary housing (68) is defined by two opposing walls (74) along a second transverse direction (T2); - said extension (52) defines two lateral sides (58) along a second transverse direction (T2); and A mooring line (22) according to claim 6, wherein each closure element (70) defines two opposing faces (76) configured to respectively come into face-to-face contact with one of the two walls (74) and one of the two side faces (58) along the second transverse direction (T2), the other of the two side faces (58) being in face-to-face contact with the other of the two walls (74).

9. - said two opposing walls (74) define a shape that widens away from the central portion (46) with an increasing width (L4) defined along a second transverse direction (T2); and A mooring line (22) according to claim 8, wherein the two opposing faces (76) define a width (L5) along a second transverse direction (T2), said width (L5) narrowing as it moves away from the central portion (46).

10. One of the two ends (44) of each strand (30) is - two branches (54) made of elastomeric material, projecting from said extension (52) in a longitudinal direction (L) and spaced apart from each other in a second transverse direction (T2); a wedge element (56) fixed to the two branches (54) and extending between the two branches (54) in a second transverse direction (T2); The mooring line (22) of claim 6, comprising:

11. - said strands (30) form a plurality of loops (78), each loop (78) comprising one of the two ends (44) of one strand (30) and one of the two ends (44) of another strand (30); and A mooring line (22) according to any one of claims 1 to 5, wherein one of the two tip portions (26, 28) comprises a plurality of supports (86) partially surrounded by one of the loops (78), each support (86) being configured to apply a stress (F1) to one of the loops, said stress (F1) being the sum of two of said tensile stresses (F2, F3).

12. 12. A mooring line (22) according to claim 11, wherein each support (86) extends along a first transverse direction (T1), and each loop (78) at least partially surrounds one of the supports (86) in the first transverse direction (T1).

13. 12. A mooring line (22) according to claim 11, wherein each loop (78) is formed of two strands (30), said two strands (30) being continuous in the second transverse direction (T2).

14. The mooring line (22) of claim 11, wherein each support (86) includes a low friction material in contact with one of the loops (78).

15. 15. The mooring line (22) of claim 14, wherein the low friction material is PTFE.

16. One of the two tips (26, 28) comprises a main portion (84), and each support (86) comprises: a shaft (88) movable relative to the main part (84) between an attached position in which the shaft (88) is attached to the main part (84) and a rest position in which the shaft (88) is spaced apart from the main part (84); and a peripheral portion (90) at least partially surrounding the shaft (88); The mooring line (22) according to claim 11, comprising:

17. - a floating platform (12) adapted to float on a body of water (14); - a mooring system (18) adapted to be fixed to the seabed (20), and - a mooring line (22) connected to the platform (12) and to the mooring system (18), said mooring line (22) being at least one of the mooring lines (22) of claims 1 to 5; An assembly member (10) comprising:

18. 18. The assembly (10) of claim 17, wherein the floating platform (12) is a wind turbine platform.

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