System and method for placing a heavy load in water

Abstract

System (1) for placing a heavy load (E), in particular a gravity base of a wind turbine comprising a base and a central tower, in water, the system comprising: - two supporting structures (20a, 20b) extending between a zone for receiving the load on land and a zone for unloading the load onto the water; - front and rear transporting structures (10a, 10b) that are able to move together while bearing on the two supporting structures between the receiving and unloading zones, each transporting structure being transversally movable relative to the supporting structures in order to go from a lifting configuration, in which the transporting structure extends partially over the load, to a retracted configuration, in which the transporting structure frees a space to allow the load to pass through the transporting structure in order to be placed between the transporting structures in the receiving zone and released in the unloading zone, and vice versa, each transporting structure comprising members for lifting the load to allow it to be lifted in the receiving zone and lowered into the water in the unloading zone; - a rear bearing structure (30a) which allows the rear transporting structure to rest thereon and on one of the supporting structures only in the retracted configuration; and - a front bearing structure (30b) which allows the front transporting structure to rest thereon and on one of the supporting structures in the retracted configuration.

Description

[0001] The present invention relates to the launching of heavy loads and more particularly but not exclusively those of gravity bases (also called GBF for "Gravity Base Foundation") used in offshore wind power, or those of jacket structures or floating foundations. Previous technique

[0002] Wind turbine towers are becoming increasingly tall to maximize energy capture by maximizing the area swept by the blades. Offshore wind turbines can reach a rotor height of 140 meters or more. Their design includes a gravity-based foundation whose weight is proportional to the installed power (typically 6,000 to 12,000 tons). These foundations are most often prefabricated onshore to optimize construction costs. The lower (submerged) section of the tower is constructed of concrete along with the base, while the above-water section can be constructed of either concrete or steel.

[0003] The lower section of the mast, constructed of concrete, always covers at least the submerged portion. Since wind turbines are commonly installed at depths of between 20 and 40 meters, the corresponding mast height of the base is generally between 40 and 60 meters. Traditional deployment methods become more expensive as the dimensions and weight of the components to be deployed increase.

[0004] Known methods of launching can involve: A specially designed barge (float); the base then loaded using SPMT-type transporters (Self-Propelled Modular Transporter – for example, Kamag type) or a high-capacity gantry crane. The barge is then ballasted and submerged to float the base; One or more vessels equipped with high-capacity lifting equipment, the cost of which is commensurate and whose availability is limited for these exceptional loads; A platform lowered by cables with winches or hydraulic jacks. The dimensions and weight of the bases limit this solution, not to mention the need for a dry dock (launching pit) under the platform; Sliding (translation) down a ramp with a constant and limited slope, similar to the older technique used for launching ships.This places significant stresses and strains on the port structure and also on the base; a gantry or structure allows for top-down support followed by sliding (translation) before launching. This solution is commonly used for launching prefabricated elements such as port caissons. However, the height of the base mast is a limiting factor when it is assembled on land rather than while afloat.

[0005] The closest prior art is represented in document EP 2 641 825 B, which describes the preamble of claim 1. Description of the invention

[0006] There is therefore a need for a system that allows for the launching of heavy loads such as gravity-driven bases, featuring a mast of significant height, remedying the disadvantages of the previous art. Summary of the invention

[0007] The invention addresses this need by proposing a system for launching a heavy load, in particular a gravity-based wind turbine generator base comprising a plinth and a central mast, the system comprising: Two support structures extending between a load reception area on land and a load unloading area on water, front and rear transport structures capable of moving together in support of the support structures between the reception and unloading areas, each transport structure being mobile transversely relative to the support structures to move from a lifting configuration where it extends at least partially over the load to a retracted configuration where it frees up space allowing the load to pass through the transport structure in order to be positioned between the transport structures in the reception area and released in the unloading area, each transport structure having load lifting devices enabling it to be lifted in the reception area and lowered into the water in the unloading area,a rear support structure allowing the rear transport structure to rest on it and on one of the support structures in the retracted configuration, a front support structure allowing the front transport structure to rest on it and on one of the support structures in the retracted configuration.

[0008] The movement of the transport structures between the lifting and retracted configurations is carried out without carrying the load, before loading or after unloading it, this movement being carried out for the sole purpose of clearing the passage for the load in order to allow it to be positioned under the transport structures or to be released, and when the load is a gravity base, to allow its mast to extend vertically between the transport structures.

[0009] The invention offers multiple advantages.

[0010] Firstly, it allows limiting the required draft because there is no submerged load-bearing structure extending under the load, and ensures launching regardless of sea and wind conditions; secondly, it allows limiting civil engineering work to reinforce port structures.

[0011] The invention allows the support of a concrete tower or a tall metal mast, with or without its generator (wind nacelle, rotor and blades).

[0012] The invention also makes it possible to limit maintenance operations at the marine site such as dredging at the launching site, because little equipment is in motion underwater.

[0013] Furthermore, compared to the drawbacks associated with the prior art described above, the invention provides a heavy lifting system in which the transport structures can be easily engaged and retracted to insert and symmetrically support the base. The base has a taller element than the transport structures themselves. This solution allows the load to be lifted onto a platform, moved over the required distance, and then lowered to float.

[0014] The invention makes it possible to avoid the use of a large capacity barge, the need for a large draft, and a large number of SMPT type rolling modules, the use of which generally requires the reinforcement of port structures and which has a high carbon footprint.

[0015] Furthermore, the solution of opening each of the transport structures in its middle section (mid-span), the area most mechanically stressed, would be more complicated to implement and would prove less competitive (manufacturing costs, duration of lifting and moving cycles, safety).

[0016] Preferably, each transport structure includes at least one steel crossbeam, which reduces weight. Each transport structure may, in particular, include a set of steel crossbeams connected together. Each crossbeam may have a main truss section, for example with two, three, or four longitudinal elements, extended by end pieces, for example with two vertically superimposed longitudinal elements. These end pieces bear on the support structure and / or the support structure when switching from the lifting configuration to the retracted configuration or vice versa, so that at all times the transport structure rests on at least two longitudinally spaced supports, namely either on at least two support structures, or on at least one support structure and one end piece.

[0017] The system may include at least two movable supports, such as sliding supports, for example in the form of trolleys, moving along the support structures, which carry the transport structures. These transport structures may move laterally relative to the trolleys. The movable supports are, for example, moved along the support structures by cable jacks, and the transport structures are, for example, moved relative to the movable supports by cable jacks. The term "trolley" should be understood broadly, encompassing trolleys with or without wheels or rollers, and capable of moving by sliding, rolling, or other means.

[0018] Each transport structure may include a plurality of lifting devices to lift the load, for example cable jacks.

[0019] Each support structure can be supported by concrete piles. Each support structure can be located at a lower ground level than the top of the mast when the load is a gravity base. For example, the top of the mast, when the base rests on the ground, is at least twice the height of the support structures.

[0020] Each support structure may include a beam supported by at least two piers at its ends. The invention also relates, according to another aspect, to a method of launching a heavy load using a launching system according to the invention, as defined above, the method comprising the following steps: Receiving the load in the loading area with the rear transport structure in retracted configuration, switching the rear transport structure to the lifting configuration, lifting the load with the transport structures, moving the load thus lifted by the transport structures along the support structures to the unloading area, lowering the load for launching, switching the front transport structure to the retracted configuration, moving the load in flotation out of the unloading area.

[0021] Such a process is particularly suitable for a load with a mast, the latter extending between the front and rear transport structures and at a height greater than these during the movement of the load between the loading and unloading areas, and in particular for a load consisting of a gravity base. Brief description of the drawings

[0022] The invention will be better understood upon reading the detailed description that follows, a non-limiting example of its implementation, and upon examination of the attached drawing, in which: [ FIG. 1 ] there figure 1 represents in a partial and schematic way, in perspective, an example of a launching system according to the invention, [ FIG. 2 ] there figure 2 is a schematic perspective view showing the lifting equipment present on the sleepers, [ FIG. 3 ] there figure 3 is a schematic perspective view showing the means of moving the sleepers along the support structures, [ FIG. 4 ] there figure 4 is a view analogous to the figure 3 showing the means of transport from another point of view, [ FIG. 5 ] there figure 5 represents in a partial and schematic perspective the transition between the main section of the crossbeams and the prongs extending from it, [ FIG. 6 ] there figure 6 represents the beaks present at one end of the front cross members, [ FIG. 7 ] there figure 7 illustrates the connection between the base and the lifting equipment, [ FIG. 8 ] there figure 8 is a partial, perspective view showing the base during transport, [ FIG. 9 ] there figure 9 is a view analogous to the figure 8 from another point of view, and [ FIG. 10 ] THE Figures 10A to 10G are top and perspective views illustrating different stages of the launching process with the system according to the invention. Detailed description

[0023] We have represented on the figures 1 to 10 a launching system 1 according to the invention, usable for launching a load consisting of a gravity base E comprising a base B and a mast F, both made of concrete and constructed on land.

[0024] Base E is intended to receive an upper part of the mast and a wind turbine nacelle (not shown).

[0025] Mast F, for example, extends to a height of more than 20 m above base B.

[0026] The weight of the load is, for example, greater than or equal to 3000t.

[0027] The base's pedestal B may have ballast caissons to ensure its buoyancy until it reaches its final location on the seabed. The outer diameter of pedestal B is, for example, greater than or equal to 15 m.

[0028] System 1 according to the invention comprises front transport structures 10a and rear 10b that can move along two parallel support structures 20a and 20b extending from a load loading zone L on the ground to a load unloading zone U in the water.

[0029] Movement paths 40 can be provided, as illustrated, to bring the base E from a manufacturing area (not shown) to the loading area L. Each transport structure 10a or 10b comprises in the illustrated example several parallel crossbeams 17 made together by connecting elements 15, the crossbeams 17 being three in the example considered.

[0030] Preferably, as illustrated, each crossbeam 17 is made with a metal frame, and has a main section 11 extended by claws 12 and 16 at its longitudinal ends.

[0031] The main section 11, for example, presents four longitudinal elements 111 parallel to each other and arranged in section like the vertices of a rectangle, as visible on the figure 4 in particular, these longitudinal elements 111 being joined together by metal mesh elements 112.

[0032] The nozzles 12 and 16 each have two parallel longitudinal elements 113, superimposed vertically, joined by metal mesh elements 114.

[0033] The upper longitudinal element 113 is connected to the two upper longitudinal elements 111 by transition elements 115 forming a V, and the same is true of the lower longitudinal element 113.

[0034] The support structures 20a and 20b each comprise a beam 23, for example made of concrete, resting on vertical piers 21. Inclined bracing beams 22 are arranged on the outside side of the piers 21, to stabilize the support structures against lateral forces.

[0035] Rear support structures 30a and front support structures 30b extend at a distance from support structure 20b.

[0036] Each support structure includes, for example, as illustrated, a horizontal beam 31, for example made of concrete, resting at its ends on vertical piers 32. Just like the support structures 20a and 20b, the support structures 30a and 30b can be stabilized by oblique bracing beams 33, in pairs on the inner and outer sides of the piers 32.

[0037] Each support structure 30a or 30b is located at a distance from the adjacent support structure 20b which is less than the length of each transport structure 10a or 10b.

[0038] The rear support structure 30a allows the rear transport structure 10b to be able to switch from a lifting configuration, illustrated in the figure 1 in particular, where it rests on support structures 20a and 20b, in a retractable configuration, visible on the Figure 10A in particular, where it rests on the support structure 20b and the support structure 30a.

[0039] Similarly, the front support structure 30b allows the front transport structure 10a to be able to switch from a lifting configuration, illustrated in the Figure 10A in particular, where it rests on support structures 20a and 20b, in a retractable configuration, visible on the figure 10G in particular, where it rests on support structure 20b and support structure 30b.

[0040] The spacing between the support structures 20a and 20b corresponds approximately to the length of the main section 11 of the crossbeams 17; the transition portions comprising the transition elements 115 come, for example, directly above the support structures in the lifting configuration.

[0041] In its retracted configuration, each transport structure 10a or 10b can rest, by its longer prongs 12, on the support structure 20b, and by its shorter prongs 16, on its corresponding support structure. Before the prongs 16 cease to rest on the support structure, the prongs 12 come to rest on the support structure 20a.

[0042] 60 trolleys are mobile on each support structure 20a or 20b to allow the transport structures 10a and 10b to move along the support structures, between the loading and unloading areas.

[0043] These trolleys 60 move along specially designed tracks on the support structures. The movement of the trolleys 60 can be ensured by any suitable drive system 61, for example by cable jacks, as illustrated in the figure 3. In the illustrated example, we see that each drive system 61 can include a cable 65 attached to the ends of the corresponding support structure, and extending between them.

[0044] The trolley 60, traveling on the support structure 20b, on which each transport structure is always supported, can carry, as can be seen in particular at the figure 9 , at least one drive system 64 adapted to move the corresponding transport structure laterally, between the lifting and retracted configurations, for example at least one cable jack drive system 66. The latter can extend between the connecting elements 15 arranged at the level of the beaks 12 and 16.

[0045] The trolleys 60 may include supports 69 to guide the crossbeams 17 laterally during their movement between the retracted and lifted configurations. In the example considered, each transport structure 10a or 10b includes beams 13 resting on the upper longitudinal elements 111 of the main sections 11, these beams 13 supporting lifting devices 50, for example cable jacks.

[0046] The distribution of the lifting devices 50 on each crossbeam 17 is chosen according to the nature and geometry of the load to be lifted; in the example considered, the transport structures 10a and 10b have symmetrical arrangements with respect to a plane of symmetry oriented perpendicularly to the support structures 20a and 20b.

[0047] For a load such as a gravity base E, the crossbeam 17 furthest from the mast F can bear as illustrated in the figure 8four lifting members 50 grouped in pairs, the latter being separated by a distance d1 and positioned symmetrically with respect to the middle of the crossbeam 17, the middle crossbeam can carry four lifting members 50, the two most central of which are separated by a distance d2 less than d1, and the two most external are separated by a distance d3 greater than d1, the crossbeam 17 closest to the mast F having four lifting members 50 of which the two most central are positioned on the crossbeam 17 substantially like the pairs of lifting members of the most external crossbeam 17, and the two most external lifting members 50 are separated by a distance d4 greater than d3.

[0048] The lifting devices 50 have attachments 51, visible on the figure 7 in particular, which can be attached to anchors 53 of the base E.

[0049] System 1 can be used in the following way.

[0050] First, the rear transport structure 10b is brought into the retracted configuration, where it rests by the prongs 16 on the rear support structure 30a and by the prongs 12 on the support structure 20b, as illustrated in the Figure 10A The front support structure 10a is in a lifting configuration, and rests by the main section 11 on the support structures 20a and 20b.

[0051] The base E can be brought into the loading area L, as illustrated in the figure 10B The mast F can be moved up to the front cross member 10a, thanks to the sufficiently recessed positioning of the lugs 12 of the rear support structure 10b. Once the base E is in place, the rear cross member 10b is returned to its lifting configuration, as illustrated in the figure 10C , and mast F extends between support structures 10a and 10b.

[0052] The fasteners 51 are attached to the base E and the lifting devices 50 are actuated to lift it above the ground.

[0053] Next, the two transport structures 10a and 10b can be moved together to bring the base E into the unloading area U, above the water, as illustrated in the figure 10D Once the base E is in the unloading zone U, it can be lowered into the water by operating the lifting devices 50 so as to make it float, as illustrated in figures 10E And 10F The fasteners 51 can be detached from the base E.

[0054] The front transport structure 10a can then be moved laterally to be brought into a retracted configuration, as illustrated in the figure 10G, in order to free the base E and allow it to leave the unloading area U. In retracted configuration, the front transport structure 10a rests by the slats 16 on the front support structure 30b, and on the support structure 20b by the slats 12.

[0055] Once the base E has left the unloading area U, the forward transport structure 10a can be brought back into lifting configuration and then moved aft so that it can take charge of the next base E to be put into the water.

[0056] Of course, the invention is not limited to the example just described.

[0057] For example, support structures 30a and 30b can be replaced by a support structure extending continuously along support structures 20a and 20b.

[0058] The arrangement of the transport structures 10a and 10b can be modified; for example, the number of crossbeams can be increased or decreased depending on the size of the base to be deployed. The transport structures can be brought into their retracted configuration by means other than translational movement along their longitudinal axis, for example, by rotation in a horizontal or vertical plane, or by a more complex movement.

[0059] Many technical solutions other than the one illustrated can be used to move transport structures along support structures, for example Air Pad System type drive solutions (air cushion sliding system commonly used for the translation of heavy loads, allowing friction to be limited to less than 1% of the vertical force, translation system with sliding supports on air cushion as described in patent EP1854746, with pads, ...)

[0060] Similarly, many technical solutions other than the one illustrated can be used to move transport structures laterally relative to support structures, for example other launching solutions on rolling or sliding supports.

Claims

1. System (1) for the load-out of a heavy load (E), in particular a gravity base of a wind generator having a plinth and a central mast, the system having: - Two supporting structures (20a, 20b) configured to extend between an onshore zone for receiving the load and a zone for unloading the load onto the water, - front and rear transport structures (10a, 10b) that can move together, bearing on the two supporting structures between the receiving and unloading zones, each transport structure being able to move transversely relative to the supporting structures so as to pass from a lifting configuration in which it extends at least partially above the load to a stowed configuration in which it frees up a space allowing the load to pass the transport structure in order to be put in place between the transport structures in the receiving zone and released in the unloading zone, and vice versa, each transport structure having members for lifting the load allowing it to be lifted in the receiving zone and lowered into the water in the unloading zone; the system being characterized in that it further comprises: - a rear bearing structure (30a) allowing the rear transport structure to rest thereon and on one of the supporting structures only in the stowed configuration, - a front bearing structure (30b) allowing the front transport structure to rest thereon and on one of the supporting structures in the stowed configuration.

2. System according to Claim 1, each transport structure having at least one crossbeam (17) made of a metal framework.

3. System according to Claim 2, each transport structure having an assembly of crossbeams (17) made of a metal framework, which are connected together.

4. System according to either of Claims 2 and 3, each crossbeam having a main section (11) made of a latticework beam, in particular with four longitudinal elements, extended by noses (12, 16) at the ends, in particular with two vertically superposed longitudinal elements, the noses bearing on the supporting structure and / or the bearing structure during the passage from the lifting configuration to the stowed configuration or vice versa, so as to ensure that, at all times, the transport structure rests at least on two longitudinally spaced supports, namely either on at least the two supporting structures or on at least one supporting structure and one bearing structure.

5. System according to any one of the preceding claims, having two mobile supports (60), in particular carriages, moving on the supporting structures, bearing the transport structures, the latter being able to move laterally relative to the mobile supports.

6. System according to the preceding claim, having cable jacks (61; 66) for moving the mobile supports (60) along the supporting structures (20a, 20b) and / or the transport structures (10a, 10b) relative to the mobile supports (60).

7. System according to any one of the preceding claims, each transport structure having a plurality of lifting members (50) making it possible to lift the load (E).

8. System according to any one of the preceding claims, each supporting structure (20a, 20b) being borne by concrete piers.

9. System according to any one of the preceding claims, each bearing structure having a beam (31) supported by at least two piers (32) at its ends.

10. Method for the load-out of a heavy load, using a system for placing in water as defined in any one of the preceding claims, the method involving the following steps: - Reception of the load in the loading zone (L) with the rear transport structure (10b) in the stowed configuration, - passage of the rear transport structure into the lifting configuration, - lifting of the load with the transport structures, - movement of the load thus lifted by the transport structures into the unloading zone, - lowering of the load for the load-out thereof, - passage of the front transport structure (10a) into the stowed configuration, - movement of the floating load out of the unloading zone (U).

11. Method according to Claim 10, the load having a mast (F), the latter extending between the front and rear transport structures and at a height greater than these during the movement of the load between the loading and unloading zones.

12. Method according to either of Claims 10 and 11, the load being constituted by a gravity base.

Images