GB2056574A - Toroidal modular captors of the energy of sea waves - Google Patents

Abstract

A toroidal semi-submersible vessel 1 has its centre of gravity G disposed below the centre of buoyancy C and oscillates about a horizontal axis which passes through the geometric centre of circle 6. In the lower part of the vessel are chambers 12 and 13 through which sea water is pumped by the relative movement of member 11. The sea water drives turbines 20 and electrical generators 21. Alternatively the vessel oscillates relative to an anchored cradle which engages part of the rim of the vessel and a generator mounted on the cradle is driven through gearing. Again the generator may comprise a column of mercury or a copper block which move radially or circumferentially respectively relative to an electromagnet. A plurality of vessels 1 may be assembled side-by-side to form a unit or may be constructed and assembled so that they form a unit having a helical duct. <IMAGE>

Description

SPECIFICATION Toroidal modular captors of the energy of sea waves The present invention relates to the transformation of the energy of the swell in the sea into useful energy.

In U.S.P. 4,119,052, which issued on October 10, 1978, a semi-submersible vessel is described which comprises a toroidal element in the form of a closed envelope adapted to float upright and partially immersed with the plane of the toroidal element disposed vertically with respect to the water surface, with its centre of gravity situated below the centre of buoyancy, the toroidal element having a horizontal platform mounted on its non-immersed upper part.

Various structures are presently being tested on a reduced scale for capturing the energy of waves.

Some of them utilize the relative movement of articulated parts of the support afloat in the swell, and others contain an internal system which uses the movement of a heavy body sea-borne in the interior of the floating structure. The present invention belongs to the latter category of structures. The energy converting system is of the hydropneumatic type, for example, and its effect on the pitching is the equivalent of a damping which consequently diminishes the pitch amplitude. Thus a module according to the invention has an internal damping the energy of which can be captured. This characteristic is an important industrial advantage, as compared for example with a semi-submersible driliing platform which in resonance possesses a viscous damping the energy of which is dissipated into the sea.

In a toroidal vessel the resultant forces acting on the immersed portion of the torus are converging towards the geometric centre of the torus or through a small space region around that geometric center.

This toroidal vessel presents good stability on swell when its pitching and billowing frequencies are tuned so as to be situated outside the range of the frequencies of highest energy of the swell spectrum.

The present invention relates to toroidal vessels or modules whose pitching frequency is purposely fixed in the range of the highest-energy frequencies of a given swell spectrum. In view of the fact that the toroidal form of the module has low viscous damping in pitching, the pitch amplitude is very great in the resonance, and a sea-based system uses this amplitude to transform it into electrical energy.

In the North Atlantic sea, the average energy density of the swell is 93 KW per meter of wave width at a mean period of 10 seconds. For a toroidal module according to the invention, and for a midship frame of 2 meters and an efficiency of the converting system of 70%, a production of 130 KW is possible.

An object of the present invention is to utilize the toroidal vessel of U.S.P. 4,119,052 as a floating structure the pitching on swell of which is maximized for utilizing the energy of the swell by sea-based hydropneumatic or mechanical means.

Another object of the present invention is to utilize the general toroidal form of the module so as to impart to the module an inherent billowing period higher than the tuned period of its pitch, so that the energy of the swell is chiefly transformed into kinetic energy of rotation, thereby improving the overall yield.

Still another object is to limit the pitch amplitude by stabilization surfaces fixed on the hull of the module, in case where the internal damping is insufficient to contain the pitch amplitude within imposed limits.

Still another object is to provide several systems or processes of transformation of the kinetic pitch energy into electrical energy.

A further object of the present invention is to supply a system of anchorage to stretched cables for the module-acco.rding to the invention.

Other characteristics and advantages of the invention will be better understood from the following description and the drawings of which: Figure 1 is a view in elevation of a module according to U.S.P. 4,119,052 of toroidal and circular form; Figure 2 is a view in elevation and in cross-section along line ll-ll of Figure 1 for a module of circular cross-section; Figure- 2-a is aview in elevation and in crosssection along line ll-ll of Figure 1 for a module of elliptical cross-section; Figure 2-b is aview in elevation and in crosssection, similar to the sections and elevations of Figures 2 and 2a, for a module the cross-section of which is polygonal;; Figure 3 is a view in elevation of another embodiment of a module oftoroidal form, whose emerging portion has a greater cross-section than the crosssection ofthe immersed portion; Figure 4 is a view in elevation of another embodiment of a module of toroidal form; Figure 5 is a view in elevation and in section along line ll-ll of Figure 6 for a module of toroidal cross-section; Figure 6 is a view in elevation of another embodiment of the module of toroidal form, equipped with a central hub and with radial columns of elliptical cross-section; Figure 7 is a diagram in elevation and in section of a hydropneumatic system, installed on board of a toroidal module; Figure 8 is a view in elevation of a toroidal module and illustrates one form according to which it may be anchored;; Figure 9 is a view in elevation and in section of a group of modules connected to a common hub by a group of radial columns; Figure 10 is a view in elevation of a toroidal module deformed along a uniform helix line; Figure 7 1 is a view in elevation of a group of toroidal modules identical with that of Figure 10, secured edge to edge, one behind the other, so as to constitute a macromodule; Figure 12 is a view in elevation of the macromodule of Figure 11; Figure 13 is a view in elevation of a macromodule composed of a group of toroidal modules of rectangular cross-sections; Figure 14 is a view in elevation of a module according to Figure 13; Figure 15is a view in elevation of a toroidal module and of its connecting elements;; Figure 16 is a view in elevation and in section of the assembly of two toroidal modules identical with that of Figu?e 15; Figure t7 is a diagram in elevation and in section of a sea-based hydraulic system; Figure 18 is a view in elevation of an embodiment of a module and of its mooring system according tot the invention; Figure 19 is a view in section along line IV-IV of Figure 18, ofan embodiment of a carriage and of its fixation to the module according to tiie invention; Figures 20 and 21 are each a View in elevation and in diametrical section, of another ebodiment of a module according to the invention;; Figure 22 is a view in elevation of an embodiment of a mooring system with stretched cables, permitting the module to be anchored facing the swell, and of converting the kinetic energy of rotation of the module into electrical energy; Figure 23 is a horizontal section along line VIII-VIII of Figure 22; Figure 24 is a view in elevation of a mooring system with stretched cables, permitting the tnodule to be anchored facing the swell, by means of a balanced semi-submersible carriage; Figure 25 is a view in elevation of another embodiment of a catenary mooring system of two modules according to the invention; Figure 26 is a section along line Xl-XI of Figure 25;; Figure 27 is a view in elevation and in section of still another embodiment of the invention which permits to produce electrical energy, by means of the displacements of a liquid in the interior of a toroidal circuit secured to the interior of a module; Figure 28 is a view in elevation and in section of a module illustrating a system of energy conversion using the centripetal acceleration of the module of the invention; Figure 29 is a sectional view of a magnetohydrodynamic generator of Figure 28; Figure 30 is a view in elevation and in section of another embodiment of a module and of its internal generator, using the pendulum movement of an electrical conductor placed in a magnetic field created in the air gap of a least one electromagnet;; Figure 31 is a view in vertical section of another embodiment of a model and of its internal electric generator, using the displacement of a solid electric conductor mounted on a carriage and moving in the air gap of at least one electromagnet; Figure 32 is a view in elevation and in section of a further embodiment of a module and of its internal electric generator, using the displacement of a conducting fluid vein in the toroidal air gap of a toroidal electro-magnet; Figure 33 is a sectional view along line XVIII-XVIII of Figure 32.

Figure 34 is a view in elevation and in section of a module and of its internal electric generator, using the displacement along a toroidal helix of a conducting fluid, in a magnetic field created by a toroidal solenoid; Figure 35 is a view in elevation and in section of a module according to the invention, permitting elec tric energy to be produced by means of the rotary displacement of a fluid filling a toroidal vein, and driving turbo-generators; Figure 36 is a view in section and in elevation of a module according to the invention permitting electric energy to be produced by means of the pressure variations of a gas generated by the movement of a liquid of a toroidal vein.

In Figures 1 and 2 is shown an embodiment of a module according to U.S.P. 4,119,052 which is formed by a tight, closed enclosure 1 of general tornidal form, partially immersed relative to a water surface 2, the plane of symmetry of which is disposed vertically relative to said water surface.

Thetoroidal module is obtained from a generating circle whose center moves along a circle 3 shown in broken lines in Figure 1, the generating circle having a variable cross-section which is maximum in the lower portion 4 and minimum in the upper portion 5, so that the inner and outer circles or peripheries 6 and 7 delimiting the crown of the plane of symmetry are vertically eccentric in relation to each other.

In its upper portion 5, the module is equipped with a horizontal deck8, secured by means of struts 15.

This deck can serve for example as landing area for a service helicopter, when the swell is of low amplitude. On the immersed portion of the module 4 and around the toroidal element there is optionally provided at least one stabilization plane 9, situated in cross-sectional planes of the toroidal element.

Figure 3 represents a similar toroidal module, but the cross-section of this module is maximum in the upper portion and minimum in the lower portion.

Figure 4 represents a toroidal module whose eccentricity of the inner and outer peripheries is zero, the centers of which are in the geometric center of the module.

According to the embodiment of Figure 2a, the form of the enclosure of the module is obtained from a generating ellipse whose center moves along the circle 3 represented in broken lines in Figure 1,the generatrix having a variable cross-section or pitch, according to the three forms described above. The module of toroidal form thus floats in upright position by reason of a suitable imbalance which permits the center of gravity G to be below the center of buoyancy C.

The approximation of the different geometric surfaces described hereinabove for the construction of the plating of the module may be substantially different, depending on whether one builds the module of prestressed concrete or with prefabricated elements as forexample by means of polygonal, flat and/or curved panels. The approximation of the different geometric surfaces described above, for the construction of the plating of the module, may also be greatly different with regard to the form of the generatrix. In fact, for example a plane generatrix of losange or rectangularform is possible, without detriment to the tuned pitching of the module.

However, the drag of the module and the rigidity of its hull benefit from a circular or ellipsoidoross- section. Figure 2b illustrates an embodiment of the invention by means of an eight-sided polygonalvariable cross-section.

The small draft of the module lying flat on its side permits its being built in a shallow basin of water, as well as its being towed on the high seas where it is then righted by progressive removal of ballast in order to occupy its vertical position of normal use.

For this purpose the lower portion 4 comprises a reservoir 10 which is used as float for floating the module on its side.

Figures 5 and 6 illustrate one manner of mooring a module equipped with a hub 25 whose horizontal axis passes through.the geometric centre of the circle 6. The columns 26 distributed radially between the hub 25 and the module have preferably an elliptical cross-section whose major axis is oriented perpendicularly to the horizontal.axis of the hub 25.

In this manner the drag of the columns produces a negligible damping. The mooring is realized by two rigid arms 27 and 28 secured relatively to the ends of the hub 25 with an anchor line.

Different systems may be used in a module to convert kinetic pitch energy into electrical energy.

Figure 7 illustrates a hydropneumatic system composed of a plunger 11 of a density higher than unity which under the effect of the pitching alternately compresses the two modules 12 and 13 which it separates in the pump body formed by the ballasting reservoir 10. This pump body, therefore, has the form of a toroidal sector of constant cross-section the ends of which are formed by hemispherical partitions. Each end of the reservoir is equipped with a seawater inlet valve which closes at high pressure and opens at low pressure. The seawater is thus introduced under pressure into two spherical pressr urized chambers 16 through an inlet valve 17 which lets the seawater enter only if the pressure exerted by the plunger 11 is higher than the pressure ofthe air chamber situated in the interior of each of the chambers 16.Both chambers 16 feed under pressure a hydraulic turbine 20 by means of a conduit 19 and each turbine 20 drives an electric generator 21. The water at the low pressure exit of the turbine is thrown back to sea.

According to another embodiment of the invention, a pump body in the form of a toroidal sector of square or rectangular cross-section arranged in the bottom of the module may be used. In this case the plunger is in the form of a cylinder of a density higher than unity.

According to the embodiment shown in Figure 8, the electric energy is directed toward the shore, by means of an electrical under water coduit 22 which descends to the bottom along the catenary anchoring system 23 of the module, to the anchor buoy 24.

The toroidal module according to the invention is anchored preferably by means of a catenary line 23 to the anchor buoy 24 with the mooring point situated at the prow of the module, in order to permit free rotation around the buoy, as a function of the combined action of the swell, wind and currents on the module.

In general, the module according to the invention is usable near coasts, where the action of the-swell is dominant and orients the module facing out.

Figure 9 jllustrates a mode of mooring a group of modules, each-integral with a common hub 31.

In Figure 10 is shown a. module the upper portion of which has been-sect!oned along a plane perpendi cular to its initial plane of symmetry. Circle 3 forms a left curve which intersects at a constant angle the generatrices of a cylinder of a diameter equal to that of circle 3.

In Figure 11 is shown.the assembly of several toroidal modules similar to that of Figure 10. The assembly is achieved by fixation of each of the faces of a module with one of the faces of one of the adjacent modules so that the aggregate of the initial circles 3 of the modules forms a helix of constant pitch Taken individually, each module has, despite its deformation, little damping in pitching and the same is true of the macromodule. The latter has the advantage of grouping an assembly of identical modules at short distance from each other, while eliminating any connecting.elements. Each module of the macromodule-is anchored by its prow to .a common buoy. This type of inter-module connection reduces the viscous damping resulting from the drag of.the connecting elements during the pitching movements of the module.

In Figures 13 and 14 is shown a macromodule, composed of several toroidal modules of rectangular cross-section. whose cross-section, constant in the bottom portion of each module, permits securing the modules, hull against hull, on a large plane surface.

Figures. 15 and 16 illustrate a macromodule, composed of two toroidal modules of variable circular cross-section, the inter-hull connection of which is obtained by several connecting elements 34 disposed along a circle centered at mid-distance of the centers of the circles 6 and 7 of the crown of the plane of symmetry.

This type of inter-module connection reduces the viscous damping resulting from the drag of the connecting elements during the pitching movements ofthe module.

Figure 17 illustrates the diagram of a hydraulic system operating inclosed circuit. The operation of the system is the following: When plunger 11 compresses the fluid of volume 12, the fluid passes across the check valve 36 and feeds the hydraulic turbine 20 andthen flows out into the volume 13.

Check valve 35 prevents the fluid from feeding turbine 20a. Turbine 20 drives the electric generator 21.When the plunger then compresses the volume 13, the fluid of volume 13-feeds across valve 35 the turbine 20a which drives the generator 21..Closing of valve 36 then.prevents the fluid from driving turbine 20.. The advantage of a hydraulic system in closed circuit is that one can operate with fresh water, or with oil thereby avoiding the corrosion of seawater.

.In Figure 8 one of the mooring modes of the module is a catenary line connecting a fixed point of the prow 47 to a buoy 24. This mooring hasthe disadvantage of being. quickly wo.rn by the movements which the pitching of the. module 1 imparts to it, the pitching being tuned to the mean period of the swell. In Figure 18 is shown a mooring system with sliding carriage decoupling the mooring line 16 from the rhythmical pitching of the module. Line 16 connects the sliding carriage 10 to the base-wei'ght 22. The carriage slides on a slide 17 disposed along the outer periphery 7, at the prow 47 of the nodule.

The mass of the carriage lOis such that its inertias greater than the friction on the slide and that of'the roller 12 which drives an electric generator 13 installed inside the carriage 10 by means of a suitable transmission system.

In Figure 19 is shown diagrammatically iri a section along line IV-IV of Figure 3, an embodiment of a sliding anchoring arrangement composed bf a carriage 10 sliding on a slide 17 integral with th'ë module 1, by means of rolls 11. The electric gener ator 13 is driven by the rotation of th rn1l6r 12. The catenary mooring line 16 is integral with the-caFriage 10.

The toroidal element of the present invention can be obtained from a plane generating geometric figure whose geometric centre moves along a circle 3 shown in broken lines in Figure 1; the geometric figure may or may not have a variable cross-section as described above. Thus in Figure 20 the generatrix is an ellipse whose major axis coincides with the axis of symmetry x-x1 of the vessel. Likewise in Figure 21 the generatrix is a geometric figure which keeps a large portion of the volume of the module awaylfrom the instantaneous axis y-y' of rotation, while permits ting the inner periphery 6 to have a small diameter relative to the outer periphery 7.The geometry of this module permits the installation of a hub 8 in which a horizontal axis permits the mooring of the module as indicated for example in Figures 22,23 and 25.

In Figure 22, a module 1 according to the invention is made fast by the axis of its hub 8 to two rigid arms 20 and 20a, which are pivoted on a horizontal axis integral with a toroidal semi-submerged float 21.

This float 21 is maintained on the vertical of a base-weight 22 by means of at least one flexible stretched mooring line 23.

In Figure 23 a possible embodiment of the present invention is illustrated in horizontal section along line VIII-VIII of Figure 22. The electric generator 13 is installed inside the float 21. A roller 12, integral with the float, the axis of rotation which is in the plane of the two axes of rotation of the ends of the connecting arms 20 and 20a, drives the generator 13 by a suitable transmission system. The arrangement of the axis of the roller in the above plane minimizes the influence of the billowing of the module on the rotation of the roller 12.

in Figure 24, another embodiment of the invention is shown. The pitching of a module according to the invention drives a roller 12 integral with a carriage 10 floating and sliding on a fixed slide 17along the outer periphery of the module in a manner similar to the carriage of Figure 19. An electric generator inside the carriage is driven by means of a suitable transmission by the rotation of roller 12. Carriage 10 is connected to a float-21 by an H-shaped rigid chassis 24 submerged horizontally. The fioa21 and the carriage each-pivot in the chassis about'a horizontal axis. Float 21 is maintained inthe vertical line of a submerged base-weight 22 by means of art least one stretched cable 23.On the emerging portion of the carriage a platform 44 is installed to support various equipments and in particular a helideck 9 which permits connection by helicopter even duriiig heaving pitching of module 1.

In Fig urns 25 and 26 is shown the assembly of two modules accdrding to the invention.inside an im mersed flat and horizontal H-shaped chassis 25, in which are secured the axes of rotation of the two modules, arranged one behind the other facing the swell. On the central portion of the chassis an open-work tubular-structure 4 partly immersed, is e?ected, supporting an overhead platform 5. Each of the rollers 12 and 12a, integral with the platform, drives an electric generator installed on the platform 5. The anchoririg of the groups is obtained by two catenary lines 46 and 45 which anchor the front of the chassis to a submerged base-weight 22, on the bottom of the sea.A rigid tube 38 connects the two catenary lines together at a sufficient distance from the prow of the head module in order to prevent friction of the lines against the rotating module.

In Figure 27, another embodiment of the present invention is shown. The electric generator is composed of two aerogerierators 27 and 28 installed in series, in the interior and at the summit of a toroidal, fight vein 26, partially filled with air and with a liquid of any kind as for example fresh water. The aerogenerators are constructed so as to operate in one direction of airflow only.

In Figure 27, the aerogenerator 27 operates when theair flows clockwise in the vein; and aerogenerator 28 operates at a flow in the opposite direction.

Thus a displacement of the liquid clockwise causes positive air pressure upstream of aerogenerator 27 and a vacuum downstream of aerogenerator 28.

Therefore, an air flow occurs which activates aerogenerator 27. Conversely, a displacement of the liquid in the opposite direction activates aerogenerator 28. In order to increase the efficiency of the aerogenerators it is possible to pressurize the toroidal vein thereby increasing the density of the air.

In Figures 28 and 29, another embodiment of the present invention is shown diagrammatically, based on the relative centripetal acceleration of a vein of mercury in the air gap of an electro-magnet. The mercury circulates in a conduit 18 covered internally by an electric insulator and which radially connects a reservoir 19 to a hydraulic accumulator 15. The sinusoidal variations of the centripetal acceleration produce a reciprocating motion of the mercury between the reservoir 19 and the hydraulic accumulator 15. Two electrodes are installed in the portion of the conduit situated in the air gap, so as to collect the blectromotor force generated there, according to Faraday's law. In Figure 30 another embodiment of the present invention is shown, based on the relative tangential acceleration of a block of copper circulating in the air gap of at least one electro-magnet The copper block 29'has a pendulum motion about the inner periphery 6, that is, about a horizontal axis of rotation.

In Figure 31, the displacement of the conductor in the air gap of at least one electro-magnet 30 is obtained by means of a curved carriage 31 on casters.

This variant may be used in the case of a toroidal module the diameter of the inner periphery 6 of which is large.

The electromotor force is picked up by means of two brush electrodes.

In Figures 32 and 33, another embodiment of the present invention is shown, based on the relative tangential acceleration of a toroidal vein of mercury in a magnetic field.

Figure 33 is a sectional view of a toroidal vein composed of an inductor torus 32 of solid steel which carries a winding 33 coaxial with it which is arranged so as to create a radial field B. This magnetic field B is closed by a toroidal hollow yoke 34 the cross-section of which is concentric with the cross-section of the inductor (field magnet) and of the same metal, but not comprising any coil.

In the air gap 35 the surfaces of the inductor and of the yoke are covered with an electric insulator.

Mercury completely fills the air gap and circulates perpendicularly to the magnetic field during the rhythmic pitching movements of the module.

The currents induced in the two half-crowns of Z Z' are in opposition; at Z Z' are two toroidal collector electrodes which are the terminals of the generator.

In Figure 34, another embodiment of the present invention is shown. The magnetic field is supplied by a toroidal solenoid 42 obtained by winding a conductor about a toroidal envelope 43, fixed inside the module. This toroidal envelope 43 is obtained from a generating circle the center of which moves along the circle 3 shown in broken lines. Inside the toroidal envelope 43 is helically wound a tight conduit 39, filled with a conducting fluid as for example mercury, and whose inner surface is covered with an electric insulator. Two electrodes 40 and 41, each in the form of a ribbon, pass through the conduit 39 so as to form a helix each and in this way the electrode 41 has a maximum generatrix and the other electrode 40 a minimum generatrix.Thus, in any section of the toroidal envelope, the component of speed of the conducting fluid and the component of the magnetic field B are there both perpendicular to the peripheries of the two electrodes. According to Faraday's law, an electromotor force appears at the terminals of these electrodes at a relative displacement of the vein of fluid and of the module according to the invention.

In Figure 35, another possible form of the present invention is shown. A preferably non-corrosive liquid entrains a relative alternating displacement inside the vein 26, during the pitching of the module.

This displacement is utilized to drive at least one hydraulic turbine 14 coupled to an electric generator.

The sinusoidal pitching movement of the module produces a centripetal acceleration and a tangential acceleration inside the module, These two accelerations are used to displace an electric conductor in a magnetic field and to produce, according to Faraday's law, an electromotor force. The conductor used must have a sufficient mass for the damping energy of the pitching to be substantial, but without stopping the pitching movement altogether. The conductor may be either a solid as for example a copper block, or a liquid as for example mercury, or salt water. The magnetic field may be produced either by an electro-magnet or by a solenoid.

In Figure 36 another embodiment of the present invention is shown based on the use of pressure variations inside a toroidal vein 50 whose upper portion is hermetically closed by means of a tight partition 51. The vein is partially filled with a liquid 52 and a gas 53 not soluble in the liquid so that the pressures on either side of the partition are identical when the pitching of the module is zero.

Two generators are placed on either side of the tight partition inside the toroidal vein. These generators 54 use the variations of the gas pressure to produce electricity. For example they may be generators operating on the principle of Professor E.

Salomon and S. Harding of Temple University, published in OCEAN INDUSTRY, August 1978.

Inside the generators, two compartments filled with hydrogen gas are separated by a membrane made of a conductive protonic substance. The pressure variations of the hydrogen permit the production of electricity.

Claims (6)

1. A semi-submersible vessel comprising a plurality of modules having a common hub, each module being of general toroidal form, the modules being partially submersed and being arranged with the respective plane of symmetry disposed vertically relative to the water surface, each module floating with the center of gravity below the center of buoyancy, each module being free to roll about said common hub.

2. The vessel according to claim 1 wherein each module is deformed along a helical line.

3. The vessel according to claim 2 wherein said modules are connected edge to edge and a macromodule is formed.

4. A semi-submersible vessel according to claim 1 wherein said modules are of rectangular crosssection.

5. The semi-submersible vessel according to claim 1 wherein a mooring system with stretchable cables is provided to anchor each module facing the swell.

6. A device, for extracting energy from waves in a liquid (2), comprising a semi-submersible vessel having at least one tubular module (1) extending around a horizontal axis with the centre of gravity (G) of the module disposed below the centre of buoyancy (C) of the module (1); relatively movable means (10 or 11) supported for movement relative to at leat said one module (1) on oscillatory rolling movement of the module (1) about said horizontal axis; and drive means (20, 20a, 12, 27 and 28) for harnessing this relative movement to generate energy.