Floating intervention vessel for temporarily docking on an offshore wind turbine platform and associated intervention assembly and system

Abstract

The invention relates to a vessel comprising a float (80) and a wind turbine intervention assembly carried by the float (80), the float (80) comprising a floating body (86) and a connecting platform (88) projecting from the floating body (86) along a connecting axis (A-A') to a lower surface of the offshore wind turbine platform. The floating body (86) defines a ballast-holding space, the vessel comprising a ballast controller which is configured to control the amount of ballast held in the ballast-holding space in order to move an upper contact surface (94) of the platform (88) upward to bring it into contact with a lower surface of the offshore wind turbine platform, the float (80) consisting of a single hull.

Description

Description Title of the invention: Floating intervention vessel intended to be temporarily moored on an offshore wind platform, associated intervention assembly and installation

[0001] The present invention relates to a floating offshore intervention vessel, intended to be temporarily moored on an offshore wind platform to carry out an installation and / or maintenance intervention on a wind turbine, the floating vessel comprising:

[0002] - a float, intended to be at least partially submerged in a body of water;

[0003] - an intervention assembly on the wind turbine, carried by the float, the intervention assembly comprising at least one lifting device configured to lift wind turbine equipment.

[0004] Such a vessel is intended to carry out assembly, disassembly and / or maintenance work on offshore wind turbines which are mounted on floating platforms.

[0005] Such an intervention vessel is particularly suitable for carrying out installation and / or maintenance operations in offshore wind farms located in waters with a depth greater than 60 m.

[0006] Installation and maintenance of wind turbines may be carried out using an offshore platform, such as a fixed-base platform disclosed in EP 2 275 340. Such a platform is particularly suitable for shallow waters where the wind turbines are fixed to the bottom of the body of water using a mast support permanently mounted in the bottom of the body of water.

[0007] However, the vast majority of offshore wind resources are found in waters deeper than 60 m, where conventional bottom fixation is not economically or practically feasible. To exploit this potential, floating wind platforms are used.

[0008] In such platforms, the wind turbine mast is carried by a floating base which is anchored by mooring lines to the bottom of the body of water.

[0009] An example of a floating wind platform includes a floating base comprising several floating columns connected together by pontoons and / or trusses. The mast extends, for example, from the top of one of the columns.

[0010] Floating wind platforms create more challenging Operation and Maintenance (O&M) conditions for wind turbines, requiring new O&M strategies and technologies.

[0011] This is all the more the case as floating wind turbine platforms see their installed power increase year on year, with installed powers of 8 MW, 12 MW, 15 MW and now even 20 MW. This increases the height of the masts (more than 100 m) and the length of the blades (more than 80 m).

[0012] Offshore wind turbines may require repeated heavy maintenance operations, given the long lifespans envisaged (more than 25 years).

[0013] When these wind turbines are carried by floating bases, maintenance operations may require disconnecting the platform's mooring and towing it to a port for maintenance using tall harbor cranes. These operations are time-consuming and very costly, causing a significant production shutdown.

[0014] Lifting solutions at sea, at significant depths (for example from 60 m to 120 m) exist but are not entirely satisfactory.

[0015] For example, maintenance platforms with deployable legs ("Jack-Up") can be used. However, since these leg platforms are fixed relative to the seabed, while the wind turbine is placed on a floating base, lifting operations are very complex to implement, given the relative excursion between the leg platform and the floating base due to the movements of the body of water.

[0016] Semi-submersible assembly and maintenance units also exist. These units can be moored to the floating wind platform or placed in dynamic positioning relative to it ("Dynamic Positioning"). However, these units have their own rolling, pitching, yaw, and heave motion, which also makes lifting operations difficult.

[0017] Another solution is to place a crane on the floating base of the wind turbine. The crane moves together with the floating base, which greatly simplifies lifting operations. However, given the required size of the crane, its transshipment, assembly on the floating base, and disassembly are cumbersome operations requiring specialized vessels, which are scarce and expensive.

[0018] An aim of the invention is therefore to provide an offshore intervention vessel, suitable for interventions on offshore wind turbines requiring high positioning precision, the intervention vessel being simple and inexpensive to operate.

[0019] To this end, the subject of the invention is an intervention vessel of the aforementioned type, characterized in that the float comprises a floating body and an attachment sole protruding from the floating body along an attachment axis on a lower surface of the offshore wind platform, the floating body defining a ballast receiving volume, the floating vessel comprising a ballast controller configured to control the quantity of ballast received in the ballast receiving volume. to move upwards an upper contact surface of the sole to place it in contact with a lower surface of the offshore wind platform, the float being monocoque.

[0020] The intervention vessel according to the invention may comprise one or more of the following characteristics, taken in isolation or in any technically possible combination:

[0021] - the upper contact surface of the sole is provided with an anchoring assembly, configured to suppress the relative movement between the upper contact surface of the sole and the lower surface of the offshore wind platform, the anchoring assembly comprising in particular at least one suction anchoring pad, and / or a magnetic anchoring pad and / or a friction anchoring pad;

[0022] - the float has at least one docking fender located above the sole, the docking fender optionally projecting relative to the floating body along the attachment axis;

[0023] - the float has an L-shaped section, taken in a vertical plane containing the attachment axis, or the float has a C-shaped section, taken in a vertical plane containing the attachment axis, the docking fender and the sole defining between them an intermediate space for receiving a structure of the offshore wind platform;

[0024] - the lifting device comprises at least one lifting and / or handling unit chosen from an intervention crane, a forklift, a wind turbine blade gripper, and / or a motion compensation device;

[0025] - the lifting device comprises a fixed mast formed from a lattice of beams assembled together, the mast projecting vertically above the floating body;

[0026] the mast has a height greater than the height of the float, the mast advantageously having a center of gravity located at a height less than half the height of the mast;

[0027] - the transverse dimensions and / or thicknesses of the lattice beams decrease from bottom to top along the mast;

[0028] - the lifting device comprises a telescopic mast, deployable between a retracted configuration in which its free end is arranged in the vicinity of the float, and an upwardly deployed configuration;

[0029] the axis of the telescopic mast is tiltable between a vertical configuration, a first configuration inclined at a non-zero angle relative to the vertical in a first direction and a second configuration inclined at a non-zero angle relative to the vertical in a second direction opposite to the first direction;

[0030] - the float comprises at least one propeller thruster arranged under the floating body and / or under the sole;

[0031] - each horizontal section of the floating body has a maximum axial dimension, taken along the attachment axis, less than 0.75 times the maximum transverse dimension of the horizontal section, preferably less than 0.50 times the maximum transverse dimension of the horizontal surface, the maximum transverse dimension being taken perpendicular to the attachment axis.

[0032] The invention also relates to an offshore intervention assembly, comprising a vessel having a hull defining at least one storage space for wind turbine equipment, and a floating vessel as defined above,

[0033] the floating vessel being movable relative to the ship between a position for transporting the floating vessel to the offshore wind platform, in which the sole of the float is kept fixed against a lower surface of the hull and an intervention position, in which the floating vessel is arranged away from the ship to intervene on an offshore wind platform.

[0034] The intervention assembly according to the invention may comprise the following characteristic:

[0035] the ship comprises at least one wind turbine equipment storage rack, and optionally at least one handling assembly having a handling member movable between a wind turbine equipment gripping position in the storage rack and an intervention position outside the hull.

[0036] The invention also relates to an offshore installation, comprising an offshore intervention assembly as defined above, and an offshore wind platform, the floating vessel being movable across the body of water from its transport position to an intervention position in which the sole is applied under a lower surface of the offshore wind platform, the maximum axial dimension of each horizontal section of the floating body, taken along the attachment axis, being less than 90% of the maximum dimension of the offshore wind platform, taken parallel to the same attachment axis.

[0037] The installation according to the invention may include the following characteristic:

[0038] - the offshore wind platform comprises a floating foundation having at least three floating columns and lower pontoons, connecting two by two the at least three floating columns, the lower pontoons defining at least part of the lower surface of the floating wind platform, the upper contact surface of the sole being engaged under the lower surface of a lower pontoon between two adjacent floating columns, the maximum transverse dimension of each horizontal section of the floating body being less than the distance horizontally separating the two adjacent floating columns or comprises a floating foundation formed by a barge with or without a central hole.

[0039] The invention will be better understood by reading the following description, given solely by way of example, and made with reference to the attached drawings, in which:

[0040] - [Fig.l] [Fig.l] is a front view of a floating wind platform on which an intervention is to be carried out using the intervention assembly according to the invention;

[0041] - [Fig.2] [Fig.2] is a top view of the floating wind platform and the intervention assembly positioned in the vicinity of the floating wind platform;

[0042] - [Fig.3] [Fig.3] is a side view (a) (b) from the front of a floating intervention vessel of the intervention assembly according to the invention;

[0043] - [Fig.4] [Fig.4] is a three-quarter front perspective view of a mounting base of the floating vessel of [Fig.3] on the floating wind platform, the base being provided with mounting pads;

[0044] - [Fig.5] [Fig.5] is a view of a floating vessel equipped with a fixed mast secured to the offshore wind platform, during an intervention on a wind turbine blade;

[0045] - [Fig.6] [Fig.6] is a view similar to [Fig.5], during an intervention on the nacelle of the wind turbine;

[0046] - [Fig.7] [Fig.7] is a view similar to [Fig.5], the floating vessel being equipped with a telescopic mast;

[0047] - [Fig.8][Fig.9][Fig.l0] Figures 8 to 10 are side views showing successively the approach and the mooring of the floating vessel on the offshore wind platform;

[0048] - [Fig.11] [Fig.11] is a top view similar to [Fig.2], illustrating the transfer of a blade from the floating vessel to the transport vessel.

[0049] A first floating offshore intervention assembly 10 according to the invention is notably represented in Figures 2 to 6 and 8 to 11.

[0050] The intervention assembly 10 floats on a body of water 12. It is intended to carry out an installation and / or maintenance intervention on at least one floating offshore wind platform 14 shown in [Fig.l].

[0051] For example, offshore wind platform 14 is located in an offshore wind farm on the surface of body of water 12.

[0052] The body of water 12 near the offshore wind platform 14 has a depth greater than 50 meters, and generally between 60 m and 1000 m.

[0053] The body of water 12 is for example an ocean, a sea, a lake, and / or a river.

[0054] With reference to [Fig.l], the wind platform 14 comprises a floating foundation 16 for example with columns, or barge type, with or without central hole, an anchoring assembly 17 anchoring the floating foundation 16 to the bottom 18 of the body of water 12 and a wind turbine 20 carried by the floating foundation 16.

[0055] In the example shown in the figures, the floating foundation 16 is a semi-submersible platform. In this example, it comprises at least three floating columns. 22, structural elements 24 connecting the floating columns 22, and possibly, a bridge (not shown). Alternatively, as indicated above, the floating foundation 16 is formed of a prismatic barge, with or without a central hole

[0056] In the particular example shown in the figures, the structural elements 24 here comprise lower pontoons 26A, connecting each pair of adjacent floating columns 22 to the bottom of the floating columns 22, upper pontoons 26B connecting each pair of adjacent floating columns 22 to the top of the floating columns 22. As a variant (not shown), lower and / or upper pontoons radially connect each column to a central point of the foundation 16 and / or to a central floating column.

[0057] The floating columns 22 extend vertically. They have internally a buoyancy volume at least partially filled with gas, providing buoyancy to the floating foundation 16. The buoyancy is adapted such that the floating foundation 16 is partially submerged in the body of water 12.

[0058] The anchoring assembly 17 comprises a plurality of anchoring lines 30 connecting each column 22 to the bottom 18 of the body of water 12. In the example of [Fig. 1], each floating column 22 is connected to at least one anchoring line 30, preferably between two and four anchoring lines 30.

[0059] The wind platform 14 is thus maintained in a horizontal position in the body of water 12.

[0060] The wind turbine 20 conventionally comprises a mast 32, a nacelle 34 rotatably mounted at the top of the mast 32, and a rotor 36, rotatably mounted relative to the nacelle 34 preferably around a horizontal axis.

[0061] The rotor 36 comprises a central hub 38 and blades 40 projecting radially from the central hub 38, the blades 40 being removably attached to the hub 38.

[0062] The mast 32 is fixed in this example to the top of a floating column 22, coaxially to the axis of one of the floating columns 22. Alternatively, the mast 32 is fixed non-coaxially to a floating column 22.

[0063] The floating columns 22 and advantageously the lower pontoons 26A define a lower surface 42 of the wind platform 14. The lower surface 42 has at least one flat region intended for mooring the floating vessel 50 of the intervention assembly 10, as will be seen below.

[0064] The intervention assembly 10 is configured to be moved on the surface of the body of water 12 to come close to the offshore wind platform 14 and carry out an intervention.

[0065] The intervention is for example an installation of wind turbine equipment, maintenance of wind turbine equipment and / or dismantling of the equipment wind turbine. In particular, the wind turbine equipment is a 40 blade, and the intervention is the installation of a 40 blade, maintenance on a 40 blade, or replacement of a 40 blade.

[0066] As illustrated by Figures 2 and 11, the intervention assembly 10 comprises a floating intervention vessel 50, and a transport vessel, 52, intended for transporting the floating vessel 50 and wind turbine equipment for their assembly or replacement on the wind turbine 20 of the offshore wind platform 14.

[0067] The transport vessel 52 comprises a hull 54, defining a hold 56 and a deck 58. It comprises at least one rack 60 for storing wind turbine equipment, and a handling assembly 62.

[0068] The support rack 60 is for example arranged on the deck 58 and / or in the hold 56. It carries wind turbine equipment, for example blades 40, or mechanical or electrical equipment of the nacelle 34.

[0069] The hull 54 has a side wall 64 also designated by the term “planking” and a bottom 66 also designated by the term “keel” defining a lower surface 68 on which the floating vessel 50 is intended to attach, the floating vessel 50 then resting on the side wall 64, as will be seen below.

[0070] The handling assembly 62 comprises for example a crane and / or a lifting arm. It comprises at least one handling member 63, capable of gripping equipment on the rack 60, and of moving it beyond the hull 54 to bring it onto the floating vessel 50, when the latter is detached from the hull 54, as illustrated in [Fig. 11],

[0071] Preferably, the handling assembly 62 is of standard capacity in the offshore sector. It has a lifting capacity, for example, of less than 1500 tonnes. Its achievable height is generally less than 40 metres. Thus, the vessel 52 is of standard size, and is therefore readily available.

[0072] With reference to [Eig.3], the floating vessel 50 comprises a monocoque float 80, defining an interior ballast receiving volume 81, a ballast controller 82, configured to control the volume of ballast received in the interior ballast receiving volume 81. The interior volume 81 is advantageously compartmentalized to ensure stability in the event of accidental flooding.

[0073] The floating vessel 50 further includes an intervention assembly 84, mounted on the float 80, the intervention assembly 84 projecting upwardly from an upper surface of the float 80.

[0074] A monohull float is composed of a single floating hull, with or without a keel, as opposed to a multihull, such as a catamaran, an outrigger canoe, a trimaran, or a quadrimaran. A monohull float, in particular, lacks an above-water or overhead superstructure connecting several independent hulls together.

[0075] With reference to [Fig. 4], the monohull float 80 comprises a floating body 86 and a sole 88 for non-permanent attachment to the offshore wind platform 14 and / or to the ship 52 projecting relative to the floating body 86 along a horizontal attachment axis A-A'. The float 80 advantageously comprises a docking fender 90 and at least one thruster 92.

[0076] The float 80 is preferably of small thickness. For example, each horizontal section of the floating body 86, in particular the horizontal section of the floating body 86 which has a maximum area, has a maximum axial dimension DA along the attachment axis A- A' less than 0.75 times the maximum transverse dimension DT of the floating body 86, taken perpendicular to the attachment axis A- A'. Preferably, the maximum axial dimension DA is less than 0.50 times its maximum transverse dimension DT, preferably less than 0.40 times its maximum transverse dimension DT.

[0077] The floating body 86 also advantageously has a height HF greater than its other dimensions, in particular its maximum axial dimension DA and its maximum transverse dimension DT.

[0078] Likewise, the height HF of the floating body 86 is preferably greater than 2.0 times the maximum axial dimension DA, in particular 3.0 times the maximum axial dimension DA. The height of the float 80 is also advantageously greater than 1.2 times the maximum transverse dimension DT.

[0079] Furthermore, the maximum axial dimension DA of the floating body 86 is less than 0.75 times, in particular 0.50 times and advantageously 0.20 times the maximum axial dimension DP of the floating wind platform 14 (visible in [Fig.11]), taken parallel to the attachment axis A-A'.

[0080] Also, in the case where the floating wind platform 14 comprises a plurality of columns 22, the maximum transverse dimension DT is preferably less than the distance DF horizontally separating the floating columns 22 (visible in [Fig.5]).

[0081] This makes it possible to remain at a safe distance from the anchor lines 30 of the floating platform 14.

[0082] In the example shown in [Fig. 4], the floating body 86 of the monocoque float 80 defines a central through orifice, opening parallel to the attachment axis A-A'. It thus has a continuous lower flotation region, two uprights projecting on either side of the lower flotation region and an upper region defining the upper surface of the float 80.

[0083] The sole 88 projects along the attachment axis A-A' from the floating body 86, preferably from the lower end of the floating body 86.

[0084] The maximum axial dimension DAS of the sole 88, taken along the attachment axis A-A' from the floating body 86, is preferably greater than 0.5 times the maximum axial dimension DA of the floating body 86, in particular greater than 0.8 times the maximum axial dimension DA of the floating body 86.

[0085] The sole 88 defines an upper contact surface 94 with the lower surface 42 of the offshore wind platform, and / or with the lower surface 68 of the hull 54.

[0086] The area of ​​the contact surface 94 is for example greater than at least 50% of the area of ​​the horizontal section of the floating body 86 having a maximum area.

[0087] In the example shown in the figures, the maximum axial dimension DAS of the sole 88 is greater than 50% of the width of the lower surface 42 of the pontoon 26A on which the sole 88 is applied, taken along the attachment axis A-A'.

[0088] As illustrated by [Fig.4], the contact surface 94 is preferably equipped with at least one anchoring element 95 allowing attachment to the lower surface 42, 68.

[0089] The anchoring assembly 95 comprises for example at least one anchoring pad on the lower surface 42, 68, preferably a plurality of anchoring pads. The or each anchoring pad is in particular a pad for anchoring by suction of the volume of fluid disposed between the contact surface 94 and the lower surface 42, 68. Advantageously, the suction anchoring pad then comprises a peripheral seal carried by the contact surface 94 and intended to be applied in a sealed manner to the lower surface 42, 68. The volume of fluid present inside the peripheral seal between the contact surface 94 and the lower surface 42, 68 is then intended to be sucked to activate the anchoring, which results in particular from the surrounding water pressure applying a connection force.

[0090] Alternatively or additionally, at least one anchor pad is a friction anchor pad and / or a magnetic anchor pad.

[0091] In the embodiment shown in the figures, the sole 88 is fixed relative to the floating body 86 and permanently protrudes from the floating body 86. In one variation (not shown), the sole 88 is retractable from a deployed configuration relative to the floating body 86 to a retracted position in the floating body 86.

[0092] In this example, taking into account the geometry of the floating foundation 16, the or each docking fender 90 projects from the floating body 86 along the attachment axis A-A' above and vertically away from the sole 88. It extends here from the upper end of the floating body 86. Alternatively, for other geometries of floating foundations 16, the or each docking fender 90 is flush with the floating body 86.

[0093] The docking fender 90 comprises, for example, an elastomer block suitable for coming into contact with the upper pontoon 26B.

[0094] The sole 88 and the docking fender 90 thus delimit between them an intermediate space 96 suitable for allowing the insertion of a lower pontoon 26A of the platform 14. Advantageously, other elastomer blocks are present in this intermediate space to cushion the docking of the lower pontoon 26A.

[0095] In the particular example illustrated in [Fig. 3], the float 80 advantageously has a C-shaped profile in side view.

[0096] Preferably, the float 80 is also provided with a mooring assembly (not shown) comprising at least one mooring line configured to be deployed towards the offshore wind platform 14 or towards the transport vessel 52 and to ensure a robust attachment to the offshore wind platform 14. This reinforces and secures in particular the connection out of the water, in the upper part of the platform 14.

[0097] Each thruster 92 is mounted under the floating body 86 and / or under the sole 88. It comprises, for example, at least one rotating propeller mounted in a tubular casing.

[0098] Each thruster 92 is preferably mounted to rotate around a vertical axis, for example with an angular movement of 360°.

[0099] The thruster(s) 92 are configured to horizontally move the vessel 50 in the body of water 12, in particular between a transport position stowed on the vessel 52, shown in [Fig. 2], and the intervention position, in which the floating vessel is stowed under the offshore wind platform 14, as shown in [Fig. 11].

[0100] The ballast receiving volume 81 is for example delimited in the floating body 86 and / or in the anchoring sole 88. It is advantageously supplemented by a fixed ballast volume, preferably located at the level of the keel to improve stability in autonomous navigation between the transport vessel 52 and the floating platform 14.

[0101] At rest, the ballast receiving volume 81 is at least partially filled with a gas such as air. The ballast is here formed of water coming from the body of water 12.

[0102] The ballast controller 82 includes at least one pump configured to pump ballast into the ballast receiving volume 81 and thereby decrease the buoyancy of the floating vessel 50, or to pump ballast present in the ballast receiving volume 81 outward and thereby increase the buoyancy of the floating vessel 50.

[0103] Thus, the ballast controller 82 is configured to stabilize the float 80 and control the draft of the float 80 between a lower configuration, in which the sole 88 is able to pass under the lower surface 42, 68, and an upper configuration, in which the contact surface 94 of the gripping sole 88 is able to be applied under the lower surface 42, 68, advantageously exerting an upwardly directed force on the lower surface 42, 68.

[0104] In the example shown in Figures 3 to 6, the intervention set 84 comprises a lifting device 100 for wind turbine equipment carried by the float 80 and, possibly, a storage 102 for wind turbine equipment present on the float 80.

[0105] In the example shown in this figure, the lifting device 100 comprises a fixed mast 104, and at least one lifting and / or handling unit 106 carried by the mast 104.

[0106] The mast 104 is here formed from a lattice of beams 108. Preferably, the thickness of the beams 108 forming the mast 104 decreases from bottom to top along the mast 104.

[0107] This makes it possible to lighten the structure of the mast 104 towards its top, and to lower the center of gravity of the intervention vessel 50. Preferably, the center of gravity of the mast 104 is lowered by at least half the height of the mast 104, for example to four tenths of the height of the mast 104.

[0108] The lifting and / or handling unit(s) 106 comprise, for example, a forklift 110, mounted movably along the mast 104, and / or an intervention crane 112 mounted movably along the mast 104, preferably in the forklift 110.

[0109] The forklift 110 is for example movable between a lower position located opposite the storage 102, and an upper position for intervention on the wind turbine 20 as visible in [Fig.3].

[0110] The intervention crane 112 can be operated from mast 104, for example to intervene at the level of nacelle 34.

[0111] The forklift 110 provides vertical movement. It is preferably equipped with a blade gripper 111.

[0112] Advantageously, the forklift 110 and / or the intervention crane 112 are equipped with a three-dimensional motion compensation table 113 to compensate for any excursions between the forklift 110 and the wind turbine 20, in particular in translation in a horizontal plane, and preferably along six axes. The vertical compensation can advantageously be carried out by the forklift 110.

[0113] A method of intervention on an offshore wind platform 14, using the intervention assembly 10, will now be described.

[0114] This method will be described for example for the replacement of a blade 40 of the wind turbine 20. Alternatively, the intervention concerns another piece of equipment of the wind turbine 20, for example equipment of the nacelle 34 and / or the mast 32.

[0115] Initially, the equipment intended for the wind turbine 20 is loaded into the ship 52 by being arranged, for example, in the racks 60 present in the hold 56 or on the deck 58.

[0116] The intervention vessel 50 is then attached to the hull 54 of the vessel 52. To do this, the ballast controller 82 is activated to introduce ballast into the ballast receiving volume 81 and cause the contact surface 94 to rise to a height lower than the height of the lower surface 68 of the ship 52.

[0117] The thruster 92 is then activated to move the sole 88 and make it pass under the lower surface 68 of the hull 54. Then, the ballast controller 82 is controlled to extract ballast from the ballast receiving volume 81.

[0118] Under the effect of deballasting, the contact surface 94 rises and is applied to the lower surface 68. It exerts an upwardly directed force on the lower surface 68. In addition, the anchoring assembly 95 of the contact surface 94 on the lower surface 68 is activated, for example by creating a suction between these surfaces at the anchoring pads 95, or by activating the friction pads or the magnetic pads.

[0119] The docking fender 90 is applied laterally to the side wall 64 of the hull 54. The mooring assembly is then put in place to finalize the holding in position of the floating vessel 50 on the hull 54 of the ship.

[0120] The floating vessel 50 having a float 80 having a maximum axial dimension and a transverse dimension as specified above, the float 80 has a small footprint in the body of water 12 relative to the vessel 52, so that it is easily secured to the hull 54 of the vessel 52 allowing its easy transport to the vicinity of the offshore wind platform 14, even over long distances.

[0121] As illustrated by [Eig.2], when the vessel 52 arrives in the vicinity of the offshore wind platform 14, for example at a distance of less than 500 m from the offshore wind platform 14, in particular between 40 m and 300 m, the mooring assembly is disconnected and the anchoring assembly 95 is deactivated.

[0122] The ballast controller 82 is again driven to introduce ballast into the ballast receiving volume 81.

[0123] Under the effect of the introduction of the ballast, the float 80 separates from the hull 54 of the ship 52.

[0124] The thrusters 92 are then activated to move the floating vessel 50 towards the offshore wind platform 14. The thrusters 92 are further activated to orient the sole 88 with its attachment axis A-A' perpendicular to the axis of a lower pontoon 26A, as illustrated by [Fig.8].

[0125] If necessary, the ballasting is adjusted using the ballast controller 82 so that the contact surface 94 of the sole 88 is located at a height lower than the height of the lower surface 42 of the floating wind platform 14, in particular at a height lower than that of the lower surface of the pontoon 26A.

[0126] With reference to [Fig.9], the sole 88 then passes below the lower pontoon 26A until the docking fenders 90 come into contact with the upper pontoon 26B.

[0127] The lower pontoon 26A is housed in the intermediate space 96 between the contact surface 94 of the sole 88 and the docking fender 90.

[0128] The float 80 is positioned opposite the pontoons 26A, 26B, between the columns 22.

[0129] Then, the ballast controller 82 is reactivated to extract ballast from the ballast receiving volume 81. As illustrated by [Fig. 10], this causes the contact surface 94 to rise, which is applied under the lower surface 42 and exerts, as before, an upwardly directed force on this surface 42. This force is generally greater than at least 80%, preferably greater than the weight of the wind turbine equipment intended to be lifted, in particular the weight of the wind turbine blade 40.

[0130] The anchoring assembly 95 is then activated as previously described. Once this is done, the mooring assembly is connected to the offshore wind platform 14, advantageously at the upper pontoon 26B.

[0131] The floating vessel 10 is thus secured to the floating foundation 16 of the offshore wind platform 14.

[0132] Given the dimensions of the float 80 as described above, the float 80 is integral with the movement of the floating foundation 16 and moves jointly with it, without heaving or taking off.

[0133] The lifting device 100 then projects relative to the float 80 directly opposite the mast 32 of the wind turbine 20.

[0134] In the case of changing a blade 40, the forklift 110 is then placed in an upper position visible in [Fig.5] to grip the blade 40. It is possibly moved angularly to orient itself in the axis of the blade 40 and transversely to approach the bolting plate of the blade 40 on the rotor hub.

[0135] Alternatively, the carriage 110 is placed at the center of gravity of the blade 40. The nacelle 34 is oriented in azimuth to present the blade 40 in the same alignment as the gripper of the carriage 110.

[0136] Optionally, when a three-dimensional compensation device is used, this compensates for the relative movements due in particular to the residual flexibility of the connection between the floating foundation 16 and the float 80 as well as to the flexibility between the mast 32 of the wind turbine 20 and the mast 104 of the lifting device 100.

[0137] The blade 40 is then detached from the central hub 38, to rest on the forklift 110 which is lowered back into its lower position.

[0138] With reference to [Fig. 11], the ship 52 then approaches the floating vessel 50 and the handling assembly 62 of the ship 52 is piloted to grasp the blade 40 which has been removed from the wind turbine 20 and place it in a rack 60 located in the hold 56 or on the deck 58.

[0139] A replacement blade 40 is then gripped by the handling assembly 62 and then loaded onto the forklift 110 in its lower position. The forklift 110 is then raised to the height of the central hub 38 of the wind turbine 20, to allow the replacement blade 40 to be reassembled.

[0140] Alternatively, as illustrated in [Fig.6], the intervention crane 112 is activated to be moved vertically (for example on the forklift 110 replacing the gripper 111) and to be placed opposite the nacelle 34 and to intervene on other equipment of the nacelle.

[0141] In the interventions which have just been described, the float 80 is attached to a lower pontoon 26A between two floating columns 22, and its maximum transverse dimension DT is less than the distance DF horizontally separating the floating columns 22 (see [Fig.5]). As indicated above, this limits the risk of interference with the anchor lines 30.

[0142] Thus, it is possible to have the lifting device 100 placed in the appropriate position relative to the wind turbine 20, while maintaining a very effective connection of the float 80 to the floating foundation 16 of the wind turbine 20. The appropriate position is as close as possible to the mast 32 in the case of the use of the intervention crane 112. For the replacement of a blade 40, the appropriate position is at the distance from the mast 32 adapted so that the mast 104 is aligned with the position of the center of gravity of the blade 40.

[0143] This limits unwanted excursions between the lifting and / or handling units 106 and the wind turbine 20.

[0144] Thus, thanks to the floating vessel 50 according to the invention, it is possible to carry out complex maintenance operations, in particular the replacement of blades 40 of wind turbines 20 or heavy nacelle equipment 34 on an offshore wind platform 14 carrying a high-power wind turbine, installed very high, for example more than 100 m above the surface of the body of water 12.

[0145] These interventions 20 can be carried out without returning to a port on the coast, which reduces the intervention time and production shutdown, and therefore the cost.

[0146] The lifting device 100 is directly secured to the offshore wind platform 14 using the floating vessel 50, as if it were mounted directly on the offshore wind platform 14, taking into account the small relative excursions between the offshore wind platform 14 and the floating vessel 50.

[0147] It is therefore not necessary to assemble / disassemble a large intervention crane on the offshore wind platform 14, this being present on the floating vessel 50. The use of a specific vessel and / or a large capacity crane is therefore not useful since the lifting device 100 is already present on the floating vessel 50.

[0148] The floating vessel 50 according to the invention therefore makes it possible to simply bring onto the offshore wind platform 14 a high-capacity lifting device 100, while retaining the advantage of remaining integral in movement with the offshore wind platform 14, and in particular with the wind turbine 20.

[0149] The floating vessel 50 can move autonomously from the vessel 52 which transports it in the vicinity of the platform 14 to the offshore wind platform 14 thanks to its thrusters 92.

[0150] Furthermore, once fixed on the offshore wind platform 14, the floating vessel 50, although having a float 80 of reduced dimensions, and therefore little inertia, benefits from the intrinsic stability of the floating foundation 16 of the offshore wind platform 14. The latter being sized to withstand severe storms, this guarantees the stability of the floating wind platform 14, even when the floating vessel 50 is secured to it.

[0151] Thus, the transport of the floating vessel 50 can be carried out with a simple ship 52 commonly used, with a relatively rapid transport time. Furthermore, the dimensions of the float 80 avoid having to modify the design of the mast 32 of the wind turbine 20, since the floating vessel 50 can be moored on the floating foundation 16 in a position suitable for the intervention.

[0152] The securing of the float 80 on the floating foundation 16 is also very simple, in particular when the latter comprises pontoons 26A, 26B, the C shape of the float 80 in side view making it possible to accommodate the lower pontoons 26A, once the docking fender 90 is applied to the upper pontoon 26B.

[0153] In a variant shown in Figures 7, the lifting device 100 does not include a fixed mast 104. It includes a telescopic mast 104 that can be deployed between a retracted position, in which the free end of the mast 104 is located in the vicinity of an upper end of the float 80, and a deployed position projecting upwards relative to the upper end of the float 80.

[0154] The telescopic mast 104 is equipped at its free end with the or each lifting and / or handling unit 106, for example a gripper 111 or an intervention crane 112 and advantageously, with a movement compensation device 113.

[0155] As illustrated by [Fig.7], in the case of assembly or replacement of blade 40, the telescopic mast 104 is deployed vertically so that the gripper 111 in the deployed position receives the blade 40.

[0156] The mast 104 is inclined relative to the vertical, for example by an angle of between 1° and 15°, moving away from the mast 32 of the wind turbine 20. This moves the gripper 111 away from the mast 32 so that it is naturally placed close to the center of gravity of the blade 40.

[0157] Preferably, the vertical position is not used when lifting the masses because the inclination allows the mechanical play of the telescopic mast 104 to be taken up and stabilizes the position of the summit.

[0158] Alternatively, for an intervention for example on the nacelle 34, the telescopic mast 104 is inclined relative to the vertical for example by an angle of between 1° and 15° to allow the intervention crane 112 to approach the nacelle 34.

[0159] This makes it possible to approach the top of the telescopic mast 104 of the nacelle 34, without having to bring the floating vessel 50 closer to the mast 32.

[0160] In other words, the initial adjustment of the angle of the telescopic mast 104, then the deployment of the telescopic length makes it possible alternately to move the top of the mast 104 away from the mast 32 of the wind turbine 20 in order to be at the center of gravity of the blade 40, or on the contrary, to move the top of the mast 104 closer to the mast 32 of the wind turbine 32, to be as close as possible to the nacelle 34 to carry out the lifting of its components.

[0161] The use of a telescopic mast 104 lowers the center of gravity of the floating vessel 50 when the telescopic mast 104 occupies its retracted position. This is useful particularly when transporting the floating vessel 50 on the vessel 52, and when moving it autonomously through the body of water 12 from the hull 54 of the vessel 52 to the offshore wind platform 14.

Claims

Claims

1. Floating offshore intervention vessel (50), intended to be temporarily moored on an offshore wind platform (14) to carry out an installation and / or maintenance intervention on a wind turbine (20), the floating vessel (50) comprising: - a float (80), intended to be at least partially immersed in a body of water (12); - an intervention assembly (84) on the wind turbine (20), carried by the float (80), the intervention assembly (84) comprising at least one lifting device (100) configured to lift wind turbine equipment, characterized in that the float (80) comprises a floating body (86) and a hooking sole (88) projecting relative to the floating body (86) along a hooking axis (A-A') on a lower surface (42) of the offshore wind platform (14), the floating body (86) defining a ballast receiving volume (81), the floating vessel (50) comprising a ballast controller (82) configured to control the quantity of ballast received in the ballast receiving volume (81) in order to move upwards an upper contact surface (94) of the sole (88) to place it in contact with a lower surface (42) of the offshore wind platform (14), the float (80) being monocoque.

2. A floating vessel (50) according to claim 1, wherein the upper contact surface (94) of the sole (88) is provided with an anchoring assembly (95), configured to suppress relative movement between the upper contact surface (94) of the sole (88) and the lower surface (42) of the offshore wind platform (14), the anchoring assembly (95) in particular comprising at least one suction anchoring pad, and / or a magnetic anchoring pad and / or a friction anchoring pad.

3. Floating vessel (50) according to any one of claims 1 or 2, wherein the float (80) has at least one docking fender (90) located above the sole (88), the docking fender (90) optionally projecting relative to the floating body (86) along the attachment axis (A-A').

4. A floating vessel (50) according to claim 3, wherein the float (80) has an L-shaped section, taken in a vertical plane containing the attachment axis (A-A'), or in which the float (80) has a C-shaped section, taken in a vertical plane containing the attachment axis (A-A'), the docking fender (90) and the sole (88) defining between them an intermediate space (96) for receiving a structure of the offshore wind platform (14).

5. Floating vessel (50) according to any one of the preceding claims, wherein the lifting device (100) comprises at least one lifting and / or handling unit (104) chosen from an intervention crane (112), a forklift (110), a wind turbine blade gripper (111), and / or a motion compensation device (113).

6. A floating vessel (50) according to any preceding claim, wherein the lifting device (100) comprises a fixed mast (104) formed from a lattice of beams (108) assembled together, the mast (104) projecting vertically above the floating body (86).

7. A floating vessel (50) according to claim 6, wherein the mast (104) has a height greater than the height of the float (80), the mast (104) advantageously having a center of gravity located at a height less than half the height of the mast (104).

8. A floating vessel (50) according to any one of claims 6 or 7, wherein the transverse dimensions and / or thicknesses of the beams (108) of the lattice decrease from bottom to top along the mast (104).

9. A floating vessel (50) according to any one of claims 1 to 5, wherein the lifting device (100) comprises a telescopic mast (104), deployable between a retracted configuration in which its free end is disposed in the vicinity of the float (80), and an upwardly deployed configuration.

10. A floating vessel (50) according to claim 9, wherein the axis of the telescopic mast (104) is tiltable between a vertical configuration, a first configuration inclined at a non-zero angle relative to the vertical in a first direction and a second configuration inclined at a non-zero angle relative to the vertical in a second direction opposite the first direction.

11. A floating vessel (50) according to any preceding claim, wherein the float (80) comprises at least one propeller thruster (92) disposed under the floating body (86) and / or under the sole (88).

12. A floating vessel (50) according to any one of the preceding claims. preceding in which each horizontal section of the floating body (86) has a maximum axial dimension, taken along the attachment axis (A-A'), less than 0.75 times the maximum transverse dimension of the horizontal section, preferably less than 0.50 times the maximum transverse dimension of the horizontal surface, the maximum transverse dimension being taken perpendicular to the attachment axis (A-A').

13. An offshore intervention assembly (10), comprising a vessel (52) having a hull (54) defining at least one wind turbine equipment storage space, and a floating vessel (50) according to any one of the preceding claims, the floating vessel (50) being movable relative to the vessel (52) between a transport position of the floating vessel (50) to the offshore wind platform (14), in which the sole (88) of the float (80) is held fixed against a lower surface (68) of the hull (54) and an intervention position, in which the floating vessel is arranged away from the vessel (52) to intervene on an offshore wind platform (14).

14. Offshore intervention assembly (10) according to claim 13, wherein the vessel (52) comprises at least one rack (60) for storing wind turbine equipment, and optionally at least one handling assembly (62) having a handling member (63) movable between a position for gripping wind turbine equipment in the storage rack (60) and an intervention position outside the hull (54).

15. Offshore installation, comprising an offshore intervention assembly (10) according to one of claims 13 or 14, and an offshore wind platform (14), the floating vessel (50) being movable through the body of water (12) from its transport position to an intervention position in which the sole (88) is applied under a lower surface (42) of the offshore wind platform (14), the maximum axial dimension of each horizontal section of the floating body (86), taken along the attachment axis (A-A'), being less than 90% of the maximum dimension of the offshore wind platform (14), taken parallel to the same attachment axis (A-A').

16. An offshore installation according to claim 15, wherein the offshore wind platform (14) comprises a floating foundation (16) having at least three floating columns (22) and pontoons in- lower (26A), connecting two by two the at least three floating columns (22), the lower pontoons (26A) defining at least a part of the lower surface (42) of the floating wind platform (14), the upper contact surface (94) of the sole (88) being engaged under the lower surface of a lower pontoon (26 A) between two adjacent floating columns (22), the maximum transverse dimension of each horizontal section of the floating body (86) being less than the distance horizontally separating the two adjacent floating columns (22) or comprises a floating foundation formed by a barge with or without a central hole.

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