EP3047140A1

EP3047140A1 - Semisubmersible platform equipped with an angular amplification system

Info

Publication number: EP3047140A1
Application number: EP14784299.1A
Authority: EP
Inventors: José Antonio RUIZ DIEZ
Original assignee: Waves Ruiz
Current assignee: Waves Ruiz
Priority date: 2013-09-20
Filing date: 2014-09-16
Publication date: 2016-07-27
Also published as: CN105745437A; US20160230739A1; BR112016005972A2; CA2921545A1; WO2015040322A1; FR3011042A1; JP2017500491A

Abstract

Wave power station which comprises: • a semisubmersible platform (2) provided with at least one longitudinal casing (4) which extends from a bow (7) to a stern (8) of the platform (2), this platform (2) having, at the bow (7) thereof, a stabilizing vane (12) which extends transversally a little back from a lower edge (9) of the casing (4) and, at the stern (8) thereof, a buoyancy beam (11) secured to the casing (4); • a wave power machine (3) mounted on the platform (2), which comprises: • a portal frame (17) mounted transversally on the casing (4) of the bow end of the platform (2), • at least one float (18) designed to allow wave energy to be converted into mechanical energy, the float (18) being mounted on an arm (20) mounted so that it can rotate on an axle (21) secured to the portal frame (17), • a converter (23) for converting the mechanical energy of the float (18) into hydraulic energy.

Description

Semi-submersible platform equipped with an angular amplification system

The invention relates to the field of energy production, and more specifically to the field of producing electrical energy from wave energy.

The invention relates to a wave power plant equipped with a platform and a wave machine mounted on this platform and equipped with floats whose upward movement or descent following the swell (which also exerts on the floats a horizontal thrust) is converted into hydraulic energy, this hydraulic energy being in turn converted into electrical energy by means of a hydraulic motor associated with a generator, or a hydroelectric turbine.

A wave power plant of this type is particularly known from US 2013/067903 (Sea Power Ltd). This plant comprises two floats (called pontoons in the document) mutually articulated by arms. These floats are designed to follow the vertical movements of the swell and produce mechanical energy by mutual rotation.

This architecture is not without inconvenience. In particular, the plant is sensitive to the heel, induced by the lateral pressure exerted by the water on the stem of the floats. This pressure is not constant over the entire length of the plant. Also the heel generates in the hinge arms torsional stress likely to accelerate the aging of the structure by mechanical fatigue. In case of rough seas, the risk of breakage is not zero. One solution would be to resize the arms to increase the stiffness, but it would result in increasing their inertia, to the detriment of the energy efficiency of the plant.

A first objective is to propose a wave power plant with increased energy efficiency.

A second objective is to propose a wave power plant with increased stability, particularly in relation to the deposit.

A third objective is to propose a wave power plant with increased compactness, in particular to benefit from rigidity and manufacturing costs. A fourth objective is to propose a wave power plant with good reliability, so as to minimize maintenance operations.

For this purpose, it is proposed a wave power plant, which comprises:

a semi-submersible platform provided with at least one longitudinal box which extends from a bow to a stern of the platform, this platform having at its bow a stabilizing fin which extends transversely below a lower edge of the box, and at its stern a transverse floating beam secured to the box;

a wave machine mounted on the platform, this machine comprising:

o a gantry mounted transversely on the caisson at the bow of the platform,

at least one float arranged to allow the transformation of the wave energy into mechanical energy, the float being mounted on an arm rotatably mounted on a fixed axis of the gantry,

o a mechanical energy converter from the float to hydraulic energy.

Thanks to this architecture, the float and the floating beam can be animated oscillatory movements in opposite direction, maximizing the angular travel of the arm (and thus the output of the power plant).

Various characteristics may be provided, alone or in combination:

the beam has, in longitudinal section, a circular contour; the beam extends about halfway up the box;

the or each box has, at the stern, an enlarged end and / or raised;

the portico extends perpendicular to the fin;

each converter comprises a pair of jacks preferably operating in tension, for example in opposition, whose pistons are coupled to the arm;

- each arm is rigid;

each arm is rigidly secured to the float; each float comprises a hydrodynamic appendage in the form of a gutter fixed under a hull of the float;

the wave power plant comprises at least two longitudinal boxes delimiting a central channel in which is disposed the float, wherein the gantry is mounted transversely between the boxes, and wherein the floating beam connects transversely caissons.

Other objects and advantages of the invention will become apparent in the light of the description of an embodiment, given hereinafter with reference to the accompanying drawings, in which:

Figure 1 is a perspective view of a wave power plant;

Figure 2 is a top view of the wave power plant of Figure 1;

- Figure 3 is a schematic view showing a power converter equipping the plant;

Figure 4 is a sectional view of the central of Figure 2, along the section plane IV-IV;

Figure 5 is a sectional detail showing a box of the central unit of Figure 2, along the section plane V-V;

Figure 6 is a detailed sectional view showing a float of the central of Figure 2, along the section plane VI-VI;

Figure 7 is a view similar to Figure 6, showing a float according to an alternative embodiment wherein the float is equipped with a hydrodynamic appendage;

Figure 8 is a side detail view showing the plant according to an alternative embodiment;

Figure 9 is a view similar to Figure 8, showing the central according to another embodiment;

- Figure 10 is a view similar to Figure 1, showing the central according to yet another embodiment.

In Figure 1 is shown a central 1 wave. This plant 1, intended to be installed offshore, comprises a semi-submersible platform 2 and a wave machine 3 mounted on the platform 2. The semi-submersible platform 2 is equipped with a plurality of elongate floating caissons 4 arranged substantially parallel in a longitudinal direction which, when the central station 1 is at sea, corresponds to the main direction of propagation of the swell (represented by the arrows located on the left in Figure 2).

In the illustrated example, the boxes 4 are two in number and have a parallelepipedal shape, square section or (as illustrated) rectangular, a height preferably greater than their thickness. The caissons 4 have solid or perforated lateral walls 5 which jointly delimit a central channel 6 extending from a bow 7 (on the left in FIGS. 1, 2 and 4) to a stern 8 (on the right in FIGS. , 2 and 4) of platform 2.

Thanks to the side walls 5 of the caissons 4, the seawater is channeled in the channel 6 along the main direction of propagation of the swell, which limits the roll movements (or heel) of the platform 2.

Each box 4 has an opposite upper longitudinal edge 9 and an opposite lower longitudinal edge 10 which are respectively emerged and immersed in calm (although hearable) sea to moderately agitated.

Each box 4 is preferably hollow, and made by assembling metal plates (for example anti-corrosion treated steel), composite material or any other material sufficiently rigid and resistant to bending forces as corrosion. Each box 4 can be stiffened by means of internal ribs, in order to better withstand the bending stresses both in the longitudinal plane (especially when the box extends cantilevered at the top of a ridge, or when is carried at both ends by two successive ridges) only in the transverse plane (especially in case of local vortex).

Each box 4 may further be compartmentalized to form ballasts that can be at least partially filled with seawater or drained so as to adjust the waterline. The filling and emptying of the ballasts can be carried out by means of pumps, preferably actuated automatically. This adjustment is preferably carried out so that the waterline is substantially median on the caissons 4 - in other words so that the draft and the freeboard of the caissons 4 are substantially identical.

According to an embodiment illustrated in Figures 1, 2 and 4, each box 4 has, at the stern 8, an enlarged end (as is more particularly visible in Figure 2) and / or elevated (as is more particularly visible in Figure 4). In this way, the volume of air trapped in the caissons 4 is higher, and the buoyancy of the platform 2 is locally increased at its stern 8.

As seen in Figures 1, 2 and 4, the platform 2 comprises, at its stern 8, a flotation beam 11 secured to the caissons 4, and which extends transversely connecting them. In addition to a function of coupling and bracing the caissons 4, and stiffening the platform 2, the beam 11 performs a float function to keep the stern 8 permanently at sea level. In other words, as it is seen well in Figure 4, the stern 8 follows the swell (shown in dashed lines in this figure).

The beam 11 may have, in longitudinal section (FIG. 4), any shape, but it is preferable, in order to optimize its float function, to have a circular shape in longitudinal section. Thus, in the example shown, the beam 11 is tubular, hollow, circular section. The vertical positioning of the beam 11 is adapted to the architecture of the platform 2 and in particular to the shape of the caissons 4; in the example shown, the beam 11 extends about halfway up the caissons 4.

The platform 2 further comprises at least one stabilizing fin 12 which, at sea, is normally immersed permanently, this fin 12 extending transversely below the lower edges of the caissons 4, at the bow of the platform 2.

The bow 12 extends only a portion of the length of the platform 2 (typically between 1/5 and 1/10 of this length).

The fin 12 has a surface 13 upper or extrados substantially flat, parallel to and facing the lower longitudinal edges 10 of the caissons 4, and a lower face or intrados 14 by which the platform 2 can be anchored to the seabed by means of a catenary 15 integral with the platform 2. The anchoring of the catenary 15 on the fin 12 can automatically orientate the platform 2 facing the swell, the forces being applied in the axis thereof and ensuring a continuous voltage of the catenary 15.

As can be seen in FIG. 1, the fin 12 has a U-shaped cross-section and comprises two lateral sides 16 extending from the lower edges of the caissons 4, in the vertical extension thereof. ci, so that the extrados 13 extends away from the lower edges of the caissons 4 so that the fin 12, located below the caissons 4, is always immersed to a depth sufficient to be immune effects of the swell.

This results in a stable maintenance of the platform plate 2 thanks to the weight of the water column which overcomes the wing 12, and acts as a damper of the movements of the platform 2, including roll (or bed ). The combined effects of the damper function of the fin 12 and the anchoring of the platform 2 by means of the catenary 15 cause the bow 7 of the platform 2 is not sensitive to the swell and is maintained at a plate substantially constant.

On the other hand, the stern 8 follows the swell thanks to the floatation of the stern ends of the caissons 4 combined with that of the beam 11. Thus, the swell induces on the platform 2 a swinging movement of the stern 8, centered on a axis substantially coincident with a median transverse line at the fin 12.

The wave machine 3 is mounted on the platform 2 at its bow 7, for example at the base of the fin 8. The machine 3 comprises, in the first place, a gantry 17 mounted on the caissons 4 extending transversely between them, and which couples them on the side of their upper edges.

The wave machine 3 comprises, secondly, at least one movable float 18 mounted in the channel between the bow 7 and the stern

8 to allow the transformation of wave energy into mechanical energy. According to a preferred embodiment illustrated in the figures

1, 2 and 4, the machine 3 comprises a transverse row of floats

18 arranged side by side in channel 6.

In the illustrated example, the floats 18 are four in number, namely a pair of side floats 18 adjacent the boxes 4 on the edges of the channel 6, and a pair of central floats 18 mounted between the lateral floats 18 in the center of the channel 6. Alternatively, the number of floats 18 could be greater. Each float 18 is preferably profiled as a boat hull, and for this purpose has a bow 19 oriented towards the bow 7 of the platform 2. As can be seen in FIG. 4, each float 18 extends beyond the fin 12 in the direction of the stern 8.

Each float 18 is mounted on a rigid rigid angled arm 20, rotatably mounted on an axis 21 secured to the gantry 17. The axis 21 is preferably common to all the arms 20. Each arm extends towards the stern 8 from the axis 21.

According to an embodiment not shown, each float 18 can be articulated with respect to the arm 20. In this way, each float 18 is pitched according to the swell, regardless of the angular position of its arm 20.

According to a preferred embodiment however, the connection between the float 18 and its arm 20 is recessed. In other words, the arm 20 is rigidly secured to the float 18.

For the purpose of stiffness, the junction between each float 18 and its arm 20 can even be supported by means of brackets 22. In this configuration, where the orientation of the float 18 relative to the platform depends only on the angle of rotation of the arm 20, the energy efficiency of the machine 3 is better because there is no loss of friction at the junction between the float 18 and its arm 20.

The gantry 17 is preferably dimensioned sufficiently generously to form a technical room welcoming and housing the equipment of the plant 1, in particular for the conversion of the mechanical energy of the swell into hydraulic energy, and then the hydraulic energy into energy electric.

The machine 3 comprises for this purpose, thirdly, for each float 18, a converter 23 of mechanical energy in hydraulic energy. This converter 23 comprises at least one jack 24 provided with a cylinder 25 defining a chamber 26 filled with a hydraulic fluid and a piston 27 slidably mounted in the chamber 26 and coupled to the arm 20.

More precisely, as illustrated in FIG. 3, the piston 27 is coupled to a wheel 28 integral with the axis 21 of rotation of the arm 20, so that the rotation thereof, caused by a movement of upward movement or descent of the float 18 accompanying the swell, alternately biases the piston 27 in tension (in the direction of the large right arrow in FIG. 3) and in compression by spring effect (in the direction of the small right arrow in FIG. 3).

In order to limit the fatigue of the mechanical parts, the jack 24 is preferably simple effect, being arranged so that the fluid is compressed (and injected into an external fluid circuit connected to turbines generating electricity, possibly stored in accumulators) only when the piston 27 is stressed in tension.

In the illustrated example, each converter 23 comprises a pair of jacks 24 operating in opposition (and both in traction), whose pistons 27 are coupled to the wheel 28, so that each oscillation of the arm 20 alternately exerts traction on each of the pistons 27, the energy of the swell being thus recovered both during the movements of ascent and descent of the float 18, as well as during any movements due to the horizontal thrust of the swell.

In order to prevent the traction forces exerted simultaneously on the pistons 27 of all the floats 18 does not translate into a global torque applied to the platform 2, tending to tilt it around the axis 21 of the arms 20, the wave machine 3 may be equipped with a force balancing system, for example in the form of a torque reverser interposed between the energy converter 23 and the arm 20.

The central unit 1 is preferably arranged so that the center of gravity of the floats 18 (which preferably extends vertically above the anchoring point of the arm 20 on the float 18) is at a distance from the beam 11 equal to at about half of the average wavelength of the swell in the maritime zone where the plant 1 is installed. For example, for a swell with an average wavelength of 150 m, it will be ensured that the distance from the beam 11 to the centers of gravity of the floats 18 is about 75 m.

In this way, the caissons 18 and the beam 11 (which drives the stern 8) are animated reciprocating movements in the opposite direction, the amplitude of which corresponds to the vertical vertical-peak distance of the swell. It can be seen in FIG. 4 that, when the beam 11 is in the hollow of a wave, the floats 18 are on the crest of the next wave. Conversely, when the beam 11 is on the crest of a wave, the floats are in the hollow thereof. This phase opposition allows maximize the angular amplitude of the rotational movement of the arm 20 relative to the platform 2.

Various design tips make it possible to optimize the operation of the central unit 1.

In particular, as illustrated in FIG. 5, the lower edge of each caisson 4 can be V-shaped, so as to improve the penetration of the caisson 4 into the water and to minimize the bending forces induced by the swell on the latter. this.

Similarly, each float 18 has a hull 29 which, in cross section (Figure 6) is V-shaped rather than flat, so as to improve the penetration of the float 18 in the water.

In addition, each float 18 may be equipped with a hydrodynamic appendage 30 for increasing the amplitude of displacement of the float 18 and the value of the engine torque exerted by the arm 20 on its axis 21 of rotation.

According to an embodiment illustrated in FIG. 7, the hydrodynamic appendage 30 is in the form of a gutter fixed under the hull 29 of the float 18, either directly (in the illustrated example) or via spacer (not shown). As seen further in Figure 7, the width of the gutter 30 is greater than the width of the float 18, its side edges being spaced from the side walls of the float 18. It follows from this configuration:

on the one hand, a local restriction of the section of passage of the swell at the level of the floats 18, which raises the level of water and thus increases the amplitude of the swell (and thus the movement of the floats)

on the other hand, an increase, on the side of the bow 19, the apparent frontal surface (and therefore the drag coefficient) of the floats 18, which increases the frontal pressure exerted by the water, and therefore the engine torque exerted by each float 18 on the axis 21 of rotation of its arm 20.

In this way, each float 18 makes it possible to recover the sum of the buoyancy forces due to the swell, and the forces resulting from the frontal thrust of the waves.

It follows from the architecture of the plant 1 which has just been described several advantages. Firstly, as we have seen, the presence of the flotation beam 11 at the stern 8 of the platform 2, at a distance from the floats 18 equal to approximately half of the average wavelength of the swell, makes it possible to maximize the angular amplitude of the swinging motion of the arms. This results in amplification of wave energy recovery, and therefore increased energy efficiency.

Secondly, the caissons 4 together form an effective barrier against the taking of the platform 2 (and therefore the central 1), which effectively channels the swell in the channel 6 and thus optimize the operation of the floats 18 In addition, the floats 18 are thus protected against transverse forces that may affect their good rotation about their axis 21. This results in increased transverse stability of the central 1, and a better reliability thereof.

Third, the fact of mounting the boxes between the bow 7 and the stern 8 of the platform 2 gives the plant 1 a good compactness (and therefore a better rigidity), which allows in particular to minimize manufacturing costs.

It should be noted that it is possible to couple several power plants

1, either by aligning them on the same wave line or by shifting them longitudinally (i.e. in the direction of the swell).

Various variants can be envisaged without departing from the scope of the present invention.

Thus, FIG. 8 shows a variant of the central unit 1, in which the stabilizing fin 12 is mounted articulated with respect to the caissons 4, and more precisely with respect to the sides 16, around a central axis 31.

This articulation allows the fin 12 to remain substantially horizontal while the platform 2 pivots at the mercy of the swell, driven by the beam 11 of flotation.

This results in a better facility of pivoting of the platform

2, since the fin 12 no longer offers resistance to its own tilting.

Furthermore, as can also be seen in FIG. 8, the fin 12 may be provided with a counterweight 32 provided projecting under the lower surface 14 and which, acting as a keel, maintains the plate of the fin 12. According to another variant embodiment, which can be combined with the previous one, each float 18 has, instead of a boat-shaped form, a cylindrical shape which limits its axial extension (that is to say, parallel to the large one). axle of the platform 2) and thus makes it less sensitive (see insensitive) to the bending forces experienced by a float in the form of a boat hull due to the passage of the swell.

According to yet another variant embodiment, illustrated in FIG. 10, the platform 2 comprises a single floating caisson 4 arranged centrally, on either side of which are distributed the floats 18, the gantry 17, the stabilizer wing 12 and the flotation beam 11, which remains integral with the casing 4 at the stern 8. The shape of the casing 4 remains generally unchanged, except that it preferably has a thickness (measured transversally) greater, for the purpose of resistance and mechanical stiffness.

The number of floats 18 illustrated (in this case eight) corresponds to an exemplary embodiment, but this number could be lower (up to two distributed on either side of the central box 4), or higher.

Claims

1. Central (1) wave, which comprises:

a semi-submersible platform (2) provided with at least one longitudinal box (4) extending from a bow (7) to a stern (8) of the platform (2), this platform (2) having to its stern (8) a transverse flotation beam (11) integral with the box (4);

a wave machine (3) mounted on the platform (2), this machine (3) is characterized in that it comprises:

a gantry (17) mounted transversely on the box (4) at the bow of the platform (2),

at least one float (18) arranged to allow the transformation of the wave energy into mechanical energy, the float (18) being mounted on an arm (20) rotatably mounted on an axis (21) integral with the gantry ( 17)

a converter (23) for mechanical energy of the float (18) in hydraulic energy,

a stabilizing fin (12) extending transversely below a lower edge (9) of the box (4).

2. Power plant (1) wave according to claim 1, wherein the beam (11) has, in longitudinal section, a circular contour.

3. Power plant (1) wave according to claim 1 or claim 2, wherein the beam (11) extends to about half the height of the box (4).

4. Power plant (1) wave according to one of the preceding claims, wherein each box (4) has, at the stern (8), an enlarged end and / or raised.

5. Power plant (1) wave according to one of the preceding claims, wherein the gantry (17) extends vertically above the fin (12).

6. power plant (1) wave according to one of the preceding claims, wherein each converter (23) comprises a pair of cylinders (24) operating in opposition, whose pistons (27) are coupled to the arm (20).

7. power plant (1) wave according to one of the preceding claims, wherein each arm (20) is rigid.

8. power plant (1) wave according to one of the preceding claims, wherein each arm is rigidly secured to the float (18).

9. power plant (1) wave according to one of the preceding claims, wherein each float (18) comprises an appendix

(30) hydrodynamic in the form of a gutter fixed under a hull (29) of the float (18).

10. Power plant (1) wave according to one of the preceding claims, which comprises at least two longitudinal boxes (4) defining a channel (6) in which central is disposed the float (18), wherein the gantry (17) is mounted transversely between the caissons (4), and wherein the flotation beam (11) transversely connects the caissons (4).