FR3088298A1 - ARTICULATED FLOAT FOR A FLOATING PLATFORM, PARTICULARLY FOR A FLOATING WIND TURBINE. - Google Patents

Description

DESCRIPTION

TITLE: Articulated float for floating platform, in particular for floating wind turbine.

The present invention relates to the field of platforms located at sea. It particularly relates to platforms carrying wind turbines.

Such a platform generally includes at least three floats. These floats are made of thick metal sheets. Such floats are therefore heavy, which affects their buoyancy. In addition, given their dimensions, they require large and expensive equipment for their manufacture, as well as a long manufacturing time. The mass of steel used is also a significant cost factor. In addition, such a platform is sensitive to the elements, in particular swell and wind; it must therefore be extremely rigid.

The problem to be solved consists in minimizing the quantities of steel used in order to facilitate the manufacture of a platform, to increase the speed of manufacture, to reduce its cost and to increase its buoyancy, while reducing its sensitivity to the element, in particular to the swell.

To solve this problem, the invention proposes a floating platform which comprises at least three floats and a substantially rigid structure, one base of which carries anchors for said floats, each float being connected to a respective anchorage by a mooring, so that the float can tilt laterally relative to said structure.

Each float advantageously comprises at least one tube, preferably metallic. Preferably, each anchor is placed in the vicinity of a lower part of the tube and the mooring connects this anchor with an upper part of this tube. The tube can include an opening downward and the mooring extends, through this opening, from bottom to top in an interior volume of this tube.

The mooring can be a flexible element, preferably a cable or a chain.

The base is advantageously a polygon, preferably a triangle, each anchor being arranged in the vicinity of an angle of this polygon. Each anchorage can be secured to a respective base, in the form of a plate, preferably circular. The base preferably comprises a central part and an annular peripheral part having a thickness less than the thickness of the central part.

The platform advantageously comprises, for each float, means for limiting a lateral displacement of the lower part of said float.

Preferably, the structure has a polyhedral shape flaring from a vertex, arranged above the base, up to this base, the shape preferably being tetrahedral or pyramidal. The structure advantageously consists of metal tubes arranged along the edges of the tetrahedron.

Each float may comprise a central tube, preferably metallic, and several peripheral tubes, preferably plastic, arranged around said central tube.

The invention also relates to a floating wind turbine, characterized in that it comprises a platform according to the invention and a mast, preferably tubular, for carrying a nacelle of the wind turbine, said mast extending upwards from a top of the structure.

- 3 Several embodiments of the invention will be described below, by way of non-limiting examples, with reference to the accompanying drawings in which:

[Fig. 1] is a view in elevation and in perspective, from above, of a wind turbine system equipped with three floats according to a first embodiment of the invention, in the form of a bundle, the bundle comprising several tubes;

[Fig. 2] is a view in section and in elevation, of a float according to FIG. 1, equipping the platform of FIG. 1; and, [Fig. 3] is a sectional and elevation view of a float according to a second embodiment.

In the description, the terms "vertical" and "horizontal" refer to an equilibrium position of the wind turbine system, as shown in Figure 1.

FIG. 1 illustrates a wind turbine system 1. In the example illustrated, the system comprises a wind turbine 2 mounted on a floating platform 3. The platform 3 comprises three floats 4, substantially identical to each other and substantially equidistant from each other.

Figures 1 and 2 illustrate a first embodiment for a float according to the invention.

Figure 2 illustrates a float 4 in more detail. In the example illustrated, the float 4 comprises a central tube 5 and eight peripheral tubes 6. The central tube is metallic and the peripheral tubes are made of plastic. The peripheral tubes are arranged around the central tube, substantially contiguous with each other and with the central tube. The tubes 5, 6 are arranged vertically, parallel to a vertical axis X4 of the float 4. The tubes all have substantially the same height, equal to the height H7 of the bundle 7.

- Each of the tubes 5, 6 substantially forms an internal volume over its entire height 9. The internal volume 9 is closed at the upper end 5A, 6A of the tube 5, 6 and open at the lower end 5B, 6B of the tube, over its entire section, through an opening 12. In the example illustrated, the tubes are closed by one of the plugs and / or a sealing plate 11.

Compressor means, not shown, are advantageously provided for injecting pressurized air into the interior volume 9. A tap allows the injection of the compressed air into the upper part of the volume 9, here through the sealing plate . The injection of air inside the tube 5, 6 makes it possible to maintain a pressure there such that a free surface 14 of the water in the tube can maintain a level NI4 close to or identical to a lower level N5B, N6B of the tube. Possible air leaks through the opening 12 at the base 6B of the tube, or by an accidental opening, can be compensated by a supply of air supplied by the compressor.

By varying the pressure inside the tubes 5, 6, it is possible to vary the level N14 of the water in the tubes. This stabilizes the stabilization of platform 1, by ballasting, by adjusting the air pressure in each tube. We can thus control the stability and level of submersion of the platform.

One can, in particular when the air supply in each tube is individualized, intervene in a tube individually, when a repair of a leak is necessary, by maintaining a pressure slightly higher than the hydrostatic pressure at the level of this leak. . Advantageously, the plug may include means of access to the interior of the tube for a worker, for example a hatch.

It also appears that the compressible air volume 9 advantageously serves as a damper for the vertical movements of the float 4.

The platform 3 comprises a structure 20 formed of six beams 21 each forming an edge of a tetrahedron. The beams are cylindrical tubes. The base 20B of the tetrahedron is an isosceles triangle.

The structure comprises, at each angle of its base 20B, a base 22. In the example illustrated, each base comprises a circular plate. An annular part 22A of the base has a reduced, substantially constant height, compared to a substantially constant height of a central part 22B.

As particularly illustrated in FIG. 2, the base 22 comprises, on its upper face 23, an anchoring 24 for the float 4. In this embodiment, the anchoring has the form of a tube, extending vertically towards the high from the upper surface 23 of the base 22. The anchoring tube extends to the interior of the central tube 5, through its opening 12. A key 27 is disposed transversely in an upper end of the tube anchor 26. A mooring, here a chain 28, connects the anchor to a fixing ring 29 secured to the underside of the sealing plate 11.

Thus fixed, the float can swing around its anchoring 24. The anchoring tube 26 penetrating into the central tube 5 constitutes a lateral stop 25 which limits any lateral movement of the lower part 5B of the tube 5, therefore of the float 4. Preferably, the platform is calculated so that in normal operation the float 4 does not come into contact with the stop 25; damping means, not shown, are advantageously provided there to limit shock in the event of contact.

Thus moored, the float 4 can tilt at the rate of the hydrodynamic forces applied to it. Thus, by its pendulum movements, the float absorbs part of the forces applied to the platform, so that part of these forces are transmitted to the structure. This last

-6Before taking back less effort can be alleviated. The weight of the platform is therefore reduced and its buoyancy improved.

In addition, due to this arrangement, the forces resulting from Archimedes' thrust are mainly taken up by the sealing plate 11, and taken up by the mooring, so that the axial forces on the tubes 5,6 are substantially harmful.

Furthermore, the tetrahedral structure is extremely rigid, with an economy of means, therefore with a reduced weight and a reduced grip under hydrodynamic forces. The weight of the platform is further reduced by the use of peripheral plastic tubes 6, the central tube 5 of which strengthens the rigidity.

In addition, the enlarged base 22 by the annular zone 22B constitutes an anti-pounding device which limits the vertical movements of the platform.

Thus, the combination of the bases 22 and the floats according to the invention therefore make it possible to increase the stability of a platform according to the invention, relative to the platforms of the prior art.

In the example illustrated, the material of the peripheral tubes 6 is a high-density polyethylene (HDPE) having a nominal diameter of approximately 2 meters, and a length of approximately 30 meters. The use of HDPE for tubes and / or pipes is particularly advantageous. Indeed, this material is very durable in water and resists internal pressure.

We will now describe a second embodiment for the invention, with reference to Figure 3, which will be described only in that it differs from the embodiment of Figures 1 and 2.

- In this second embodiment, the float 4 consists of a single metal tube 5. The anchoring means 24 consist of a ring secured to the base 22 and arranged in the center of the latter. The lateral stop 25 is dissociated from the anchor 24; it comprises a metal cylinder portion with a vertical axis and integral with the base 22. The lower part 5B of the tube 5 penetrates into the stop cylinder 25, so that the stop cylinder 25 limits any lateral movement of the lower part 5B of the tube 5, therefore of the float 4. Preferably, the platform is calculated so that in normal operation the float 4 does not come into contact with the stop; damping means are advantageously provided to limit shock in the event of contact.

In the example illustrated, secondary chains 30 connect the anchorage to the lower part of the float 4, so that in normal operation the lower part of the tube does not come into contact with the cylinder 25.

Of course, the invention is not limited to the examples which have just been described. On the contrary, the invention is defined by the claims which follow.

It will appear to those skilled in the art that various modifications can be made to the embodiments described above, in the light of the teaching which has just been disclosed to him.

The mooring, instead of being a chain, can be a cable. It can also be a rigid element, for example a bar, articulated on the one hand with the base and on the other hand with the upper part of the float. Means of articulation with the base can be of the ball joint or universal joint type.

Other plastics can be used for the peripheral tubes. These tubes can also be made of metal, for example steel; the section and

- 8the reduced thickness of the tubes makes it possible to use standard metal tubes or to produce them at low cost.

In the lower part of the tubes, the opening may be only partial, so as to reduce the exchange of water between the outside and the inside of the tubes and air leaks. The opening can also be screened to avoid, for example, an intrusion of an object harmful to the proper functioning of the float.

Equally advantageous is the use of a pressurized air supply system in the tubes. Indeed, this avoids installing drain pumps in the bottom of the floats, as is done in those of the prior art.

The base, instead of being only a plate, can be a closed volume, preferably cylindrical; this volume can be of the ballastable type, and served as a buoyancy reserve, in particular when the platform is in port, or in an area with a low draft.

The first illustrated embodiment, in addition to the advantages already explained, makes it possible to increase the safety of a platform equipped with floats according to the first embodiment of the invention. Indeed, if one of the peripheral tubes is damaged, for example during a collision, the loss of buoyancy of the float is limited, and does not endanger the stability of the platform. Operation in degraded mode, when some of the tubes are damaged, can advantageously be provided during the design of the platform.

There can be several rows of peripheral tubes. These tubes can have different diameters from each other. For example, reduced diameters at the periphery of the bundle, in order to limit a loss of buoyancy in the event of a collision.

-9The section of the tubes is not necessarily circular; the tubes can for example be of square or rectangular section.

Claims (13)

1. Floating platform (3), characterized in that it comprises at least three floats (4) and a substantially rigid structure (20), one base (20B) of which carries anchors (24) for said floats, each float being connected to a respective anchorage by a mooring (28), so that the float can tilt laterally relative to said structure. 2. Platform according to claim 1, characterized in that each float comprises at least one tube, preferably metallic. 3. Platform according to claim 2, characterized in that each anchor is arranged in the vicinity of a lower part (5B) of the tube (5) and in that the mooring connects said anchor with an upper part (5A) of said tube . 4. Platform according to claim 3, characterized in that the tube comprises an opening (12) downwards and in that said mooring extends, through this opening, from bottom to top in an interior volume to said tube. 5. Platform according to one of claims 1 to 4, characterized in that the mooring is a flexible element, preferably a cable or a chain. 6. Platform according to one of claims 1 to 5, characterized in that the base is a polygon, preferably a triangle, each anchor being arranged in the vicinity of an angle of said polygon. 7. Platform according to one of claims 1 to 6, characterized in that each anchorage is integral with a respective base (22), in the form of a plate, preferably circular. 8. Platform according to claim 1 to 6, characterized in that each anchoring is integral with a respective base (22), preferably cylindrical, defining a closed volume, preferably ballastable. 9. Platform according to one of claims 1 to 8, characterized in that it comprises, for each float (4), means (25,30) for limiting a lateral movement of the lower part of said float. 10. Platform according to one of claims 1 to 9, characterized in that the structure has a polyhedral shape flaring from a top, arranged - 11 above the base, up to said base, said shape preferably being tetrahedral or pyramidal. 11. Platform according to claim 10, characterized in that the structure consists of metal tubes arranged along the edges of the tetrahedron. 5 12. Platform according to one of claims 1 to 11, characterized in that each float comprises a central tube (5), preferably metallic, and several peripheral tubes (6), preferably plastic, arranged around said central tube. 13. Floating wind turbine, characterized in that it comprises a platform 10 according to one of claims 1 to 12 and a mast, preferably tubular, for carrying a nacelle of the wind turbine, said mast extending upwards from the top of the structure.