Patent Application
20100158705
The invention relates to the field of recovering kinetic energy of a naturally moving fluid current, such as for example a marine or atmospheric current (wind), and the conversion of this energy into mechanical or electrical energy.
Several types of devices are known today with which kinetic energy of a fluid may be collected in order to convert it into usable energy.
Among these devices, some aim at recovering the energy of fluid movements which cannot be assimilated to <<currents>>. This is notably the case of devices aiming at recovering energy from marine swell or waves.
Such devices for recovering the energy of the swell or of the waves thus typically use means for recovering the energy capable of being carried away by the swell or the waves in a reciprocal movement such as for example bellows or weights.
Document U.S. Pat. No. 4,883,411 describes a system for recovering the energy of waves comprising two immersed pumping apparatuses, each pumping means comprising a float which is set into motion by the action of the waves and a piston pump. Each piston pump is capable of picking up sea water and of sending it to a tank positioned above sea level. The stored fluid may be used in order to operate a hydroelectric generator.
The devices according to the invention as for them fall within a different design and different general operation.
The devices according to the invention actually aim at recovering the energy of a current, the possible variations of which (in direction and/or in velocity) occur during variation periods much longer than the typical variation times of the swell. The (atmospheric or marine for example) currents actually change generally continuously and relatively slowly.
In certain cases, it is further possible to predict the force and the direction of these currents, which is quasi not the case for swell or waves.
In this respect, it is specified that a particularly advantageous application of the invention consists of recovering the energy of tidal currents, for which the period, the direction and the force are quite predictable—which is an important factor for guaranteeing efficient and economically viable recovery of energy.
Therefore, as regards devices for recovering the energy of a current, wind turbines are known which allow transformation of the kinetic energy of the wind into mechanical energy. The generated mechanical energy may directly be used or converted into energy of different nature (heat, electricity).
Also, hydroelectric machines are known (sometimes called “tidal turbines” or “underwater turbines”) capable of transforming the kinetic energy of a marine current into mechanical or electric energy.
Such known devices are schematically illustrated in
These known devices comprise first means for energy conversion, typically a propeller 10 or another rotor element, bound up with a rotating shaft 100 or to another mobile member, in order to recover the energy of the current and to convert it into a mechanical movement of said mobile member. In this text, such “first” conversion means will also be called “recovery means”.
These known devices also comprise means 11 for converting the thereby recovered mechanical energy, in order to convert this energy (typically into electric energy). In this text such means will be called “second” conversion means. The means 11 typically comprise an alternator, the rotor of which is driven by the output shaft 100 of the propeller 10.
They also comprise means 12 for conveying the electricity produced by the alternator towards a site for storing or consuming this electricity.
In the case of known devices, the second conversion means are generally directly coupled to the first conversion means. This is for example the case for a wind turbine, the propeller of which (first conversion means) is directly coupled with an alternator (second conversion means).
By “directly coupled”, is meant here that the movement of the recovery means is used (possibly via a drive train for example comprising gear or speed reduction means) without any energy conversion in order to set into motion the second conversion means which in turn produce electric energy on location.
The first and second directly coupled conversion means are then positioned close to each other in order to provide this coupling.
Now, this may be a drawback notably for the installation of the device, its exploitation and its maintenance.
In particular, in the case of a device intended to be implanted in a location which is difficult to access, the installation of second conversion means such as an electric alternator, may prove to be delicate—notably in a wet medium and a fortiori in an immersed location, in particular if power electronics prove to be necessary
The exploitation of such second conversion means and their maintenance, always on a site which is difficult to access, may also be very restricting.
Even if this drawback is not necessarily redhibitory, it would be preferable to be able to get rid of it.
Further, the transport of electricity produced in situ towards a location for consumption or storage, may also represent a constraint—here again notably in the case of production on isolated and/or wet sites or even immersed sites.
Document U.S. Pat. No. 4,317,048 describes a system comprising a plurality of <<first>> conversion devices, each conversion device being capable of collecting energy emitted by a source of natural energy (solar energy, wind energy, water currents, etc.) in order to pressurize a fluid. The pressurized fluid is then transported and its pressure is used for operating hydraulic motors coupled to electric generators.
With such a system, it is possible to transport the energy recovered in a natural medium via a closed fluidic circuit, without having to produce electricity on location and being subject to the aforementioned drawbacks thereof.
But this system requires the installation of a closed fluidic circuit comprising a supply conduit for feeding fluid to the first conversion devices on the one hand and a collecting conduit for collecting the pressurized fluid produced by each conversion device on the other hand and for transporting this fluid towards the hydraulic motors.
Such a system thus requires a complicated construction with its closed fluidic circuit. It requires the provision of an energy transfer fluid.
Further, in the case of failure of the device, the energy transfer fluid is capable of polluting the environment.
A goal of the invention consists of giving the possibility of getting rid of the drawbacks and constraints mentioned above.
Document WO 03/029645 A1 describes an electric power generation system comprising a plurality of turbine units immersed in the sea, each unit including a turbine and a pump coupled to the turbine. The device also comprises remote generator means and a conduit for transporting fluid from each turbine unit as far as the generator means. The transported fluid is sea water taken by the pump. The turbine units are attached to the bottom of the sea and are driven by the flow and ebb of the tide, so that they do not need to be oriented in the direction of motion of the water.
Document U.S. Pat. No. 4,383,182 describes an electric power generation system intended to be positioned in a marine current with a substantially constant velocity. The system comprises a plurality of power producing modules including a propeller and a centrifugal pump, as well as a power absorption module including a centrifugal pump or turbine and an electric generator. This document specifies that any number of power production modules may be used for feeding a high pressure tank in the absorption module so as to increase the amount of electricity generated by the generator. In this system, electricity is produced on location, in the immersed system, and not by remote means.
Document EP 1 489 299 A1 describes a system for recovering wind energy, comprising a wind rotor and an air compressor capable of being driven by the rotor and of producing liquid air. A conduit allows the liquid air to be conveyed from the compressor to storage tanks or to a sea water desalination station.
Document GB 2,340,892 A describes a system comprising “propellers” immersed in sea water, each propeller including a rotor and a water pump driven by the rotor. A high pressure conduit allows the pressurized water to be conveyed from the propellers to a remote receiving station. The receiving station includes a water turbine with which electricity may be generated. Each propeller is able to naturally orienting itself in the direction of the current.
Document EP 1 637 733 A1 describes a system for producing electric energy from wind. The system comprises a plurality of wind turbines, each turbine including a rotor and a pump driven by the rotor. The pump is able to receive fluid (in particular water) via a supply conduit and of injecting pressurized fluid into a collecting conduit for conveying the fluid to a pressurized tank. The pressurized fluid is used for operating an electric power generator.
This system requires the installation of a closed fluidic circuit comprising a supply conduit on the one hand and a collecting conduit on the other hand for collecting the pressurized fluid produced by each wind turbine and transporting this fluid to the tank.
Document DE 10 204 063895 A1 describes a system for recovering wind energy. The system comprises an off-shore installation including a compressor mounted on a mast. The compressor driven by the wind is capable of transmitting pressurized air towards a remote electric generator located on land.
In the known systems for recovering energy from a current, the current exerts on the recovery means a mechanical thrust which may be significant.
The recovery means are always integrated on their installation site to an assembly which comprises other means—for example second energy conversion means.
This assembly is subject to the thrust of the current.
It is therefore necessary to accordingly dimension strong anchoring and holding means of the assembly installed on site. This may prove to be restricting.
Further, it may desired to exclude from the thrust of the current, the (conversion or other) means which are coupled to the recovery means. This is for example the case of an alternator coupled to a propeller—it is then desired to isolate the alternator from the thrust applied by the current on the propeller so that the alternator may rotate independently of the thrust experienced by the propeller.
In this case, it is necessary to provide in the device, holding, bearing and abutment systems intended to isolate as much as possible the means coupled to the recovery means, according to the thrust direction of the current.
The application of such systems may become complicated. In the case when the thrust is very large (case of an underwater turbine with large dimensions for example) the design, installation and setting into place of such bearing and abutment systems may become very restricting.
Another goal of the invention thus consists of being able to do without bearing and abutment systems of large dimensions.
Another aspect which still should be taken into account, concerns the regularity of the energy supply provided by the energy recovery devices.
The recovery of natural energy is actually subject to the availability of this energy.
In certain cases (case of tidal currents notably) this availability is predictable. But even so, the provision of energy remains irregular since it varies with the intensity of the current.
In the case of tidal currents which probably correspond to the most predictable natural currents, there actually remain periods during which the current flow will not be sufficient for providing significant energy (period around the stationary level, neap tide periods).
And during other periods (stronger spring tide current for example), the current flow may also be too strong for the needs or provided capacities.
Indeed, in practice, the devices for which exploitation may be contemplated are designed in order to recover energy around rated operating conditions, centered on the most frequent current conditions. Outside these conditions, energy recovery is impossible or at the very least is a problem.
It would also be desirable to do without this irregularity constraint on the availability of the energy, at least to a certain extent.
Finally, in the case where production of electric energy is desired, it would be desirable to be able to directly produce electricity with given characteristics (for example an alternating electric current of 50 Hertz), without the intervention of power electronics.
The invention is aimed at meeting the goals stated above.
More specifically, in the different embodiments of the invention which will be discussed hereafter, some of these goals will be targeted. It is thus understood that a given embodiment does not necessarily aim at simultaneously attaining all these goals. But as this will be seen, each goal is targeted by means specific to certain embodiments of the invention.
In this respect, the invention proposes a device for collecting kinetic energy of a naturally moving fluid, comprising:
characterized in that the pumping or compression means comprise a multicellular centrifugal pump, the axis of rotation of which is parallel or substantially parallel to the direction of the current.
Because the fluid set into circulation is also the fluid from which kinetic energy is collected, this device does not require the supply of a specific transport fluid.
In the case of failure of the device, the risks of polluting the environment with the transported fluid are therefore limited.
Further, this device does not require the installation of a closed hydraulic circuit.
By means of the multicellular centrifugal pump, the pumping/compression means exert on the conversion means a force which opposes the thrust necessarily generated by the conversion means. Thus, the forces exerted by the pumping/compression means on the one hand and by the conversion means on the other hand may counterbalance each other partly or entirely. This avoids the use of mechanical retaining means for retaining the conversion means relatively to the pumping/compression means, such as bearings or abutments of large dimensions.
The device may further have the following characteristics:
The invention also relates to a method for collecting the kinetic energy of a naturally moving fluid, comprising steps of:
wherein the pumping or compression means comprise a multicellular centrifugal pump, the axis of rotation of which is parallel or substantially parallel to the direction of the current.
Other features and advantages will further emerge from the following description. This description is purely illustrative and should be read with reference to the appended drawings, among which, in addition to
Generally, the invention thus proposes a device for collecting kinetic energy from a fluid current, comprising:
The recovery means typically comprise a propeller or another rotating element. In any case, they comprise a mobile element for recovering the energy from the fluid current and for driving the pumping means.
The pumping means driven by the recovery means, pump fluid in the ambient medium and pressurize it in order to allow its transport towards remote energy conversion or storage means. This pressurized fluid thus allows transport of the energy recovered in the current.
The fact that the fluid is the natural fluid of the current makes it possible to avoid resorting to a complicated closed fluidic circuit. With this, it is also possible to avoid the other drawbacks associated with such a closed circuit (risk of pollution, difficulty in maintaining it, . . . ).
Several embodiments of the invention will be described. These embodiments are non-limiting. The different examples which will be illustrated each comprise particular aspects. These particular aspects are not exclusively attached to the embodiment which they illustrate in this text—they may be applied with any embodiment of the invention and these particular aspects may thus be combined together according to any possible combination.
Further, the elements which are discussed concerning a wind turbine system may be applicable—except for incompatibility, to underwater systems. The converse is also true.
In this figure, the illustrated device 100 comprises a first portion 110 immersed in the sea and a second portion 120 on land, installed for example on one side, at a distance from the immersed portion 110.
The first portion 110 of the device is an apparatus comprising a case 111, a propeller 112 rotatably mounted relatively to the case 111, a first transmission shaft 113 capable of being driven into rotation by the propeller 112, a multiplier mechanism 114, a second transmission shaft 115, a multicellular centrifugal pump 116 capable of being driven by the second shaft 115.
In this embodiment like in all the embodiments of the invention, the multiplier mechanism is optional.
When this multiplier mechanism is present it allows the transmission shaft engaged with the pumping means (which here are the multicellular centrifugal pump) to be driven with a high speed of rotation.
When this mechanism is absent, the design and the maintenance of the system are simplified.
The case 111 is secured to the bottom of the sea via a securing chain 117 or on a stake or a support itself moored or attached to the ground.
Moreover, the device comprises a venturi system 118 in order to accelerate the velocity of the marine current which drives the propeller 112.
The propeller 112 is located outside the case 111. For example, this is a propeller of the Kaplan type.
The multiplier mechanism 114, the second transmission shaft 115 and the multicellular centrifugal pump 116 are laid out inside the case 111.
The pump is advantageously made as a multicellular pump, each stage (cell) of which increases the fluid pressure. Details will be given which may relate to such a pump, in another section of this text.
The centrifugal pump 116 has a fluid inlet 1161 and a fluid outlet 1162.
The device comprises a fluid conduit 119 for transporting fluid from the outlet 1162 of the pump 116 towards the portion 120 at the bottom of the device.
In this embodiment, the fluid conduit 119 is provided with a rotary gasket 1191 which allows orientation of the immersed portion 110 of the device, without damaging the conduit 119.
The rotary gasket is here illustrated close to the side, which in reality is at a distance. In practice, the immersed portion 110 of the device orients itself depending on the stresses from the current, by pivoting around the rotary gasket 1191 which remains fixed.
The second portion 120 of the device comprises a hydraulic turbine 121 of the Pelton or Francis type for example, and an electricity generator 122 such as an alternator coupled to the turbine 121.
In operation, the immersed portion 110 of the device is maintained at substantially constant depth.
Because of the engagement which it provides to the current, the case 111 is capable of swinging, i.e. of orienting itself in the direction of the marine current by rotating around its anchoring point 1191 at the bottom, so that the stress on the propeller 112 by the marine current is always maximum. The assembly 110 forms a rigid whole and therefore swings with the case.
The circulating sea water in the venturi 118, drives the propeller 112 into rotation.
The movement of rotation of the propeller 112 is transmitted by means of the first driving shaft 113, the multiplier mechanism 114 and the second driving shaft 115 to the pump 116. The multiplier mechanism 114 (which is optional as this has been stated) enables conversion of the movement of rotation of the first shaft 113 into a movement of rotation of the second shaft 115 having a higher speed of rotation.
Typically, the multiplier mechanism 114 is capable of converting a speed of rotation of the first shaft 113 comprised between 100 and 600 revolutions per minute into a speed of rotation of the second shaft 115 comprised between 3,000 and 6,000 revolutions per minute.
The second driving shaft 115 drives the pump 116. The pump 116 picks up sea water through the inlet 1161 and injects the sea water into the conduit 119 through the outlet 1162. The sea water is injected by the pump 116 at a high pressure, of the order of 200 bars. The sea water is directly picked up in the surrounding medium.
The pump 116 causes the pressurized sea water to circulate in the conduit 119. The sea water is transported through the conduit 119 as far as the bottom portion 120 of the device.
The thereby transported sea water is used for feeding the turbine 121. The turbine 121 is driven into rotation by the pressurized sea water. The turbine 121 in turn drives the generator 122 which converts the movement of rotation of the turbine 121 into an electric current. With the movement of the turbine 121 at a stable regulated speed, an electric current with stable frequency may be provided.
The thereby used water may return to the sea.
The propeller 112 is actuated by the marine current, characterized by large water mass at low pressure, and the pump 116 injects a transport liquid as a small water mass with high pressure.
Smoothing the Current Irregularities
Natural (either marine or air) currents are likely to vary which may prove to be a problem for properly exploiting their energy.
Generally, the velocity of the marine current varies continually which causes a variation of the kinetic energy which may be collected by the propeller 112.
Smoothing of the Irregularities by Adjusting the Admission Flow Rate
Means for adjusting the admission flow rate for the propeller 112 or the turbine 121 may be provided, or further means for adjusting the orientation of the blades of the propeller 112, so as to regulate the speed of rotation of the propeller and/or the turbine 121 and to obtain a substantially constant speed of rotation of the shaft 115.
An electric current with a substantially constant period may thereby be obtained.
Smoothing of the Irregularities by the Use of Several “Sources” 110
Further, as this is illustrated in
In this case, the outlets of the different conduits 119 from each apparatus 110 converge at a concentrator or manifold (both of these terms being understood as being equivalent in this text).
In the case of a manifold provided with admission means allowing selective adjustment of the aperture of each conduit 119, it is thereby possible to manage the admission of pressurized fluid from the different apparatuses 110. These different fluid admissions are combined at the manifold into a single flow, which feeds the turbine located in 120.
In the case of a marine current, for which the characteristics (case of tidal currents) are known in advance, it is possible to program beforehand these apertures in order to obtain a turbine feeding flow with desired characteristics, for example within a desired operating range of the turbine.
The apparatuses 110 may be positioned in distinct geographical sites, each site having at a given instant different current characteristics. In such a configuration, the different sea water flow rates generated by the different apparatuses 110 are combined according to proportions which may be controlled at the manifold, which allows smoothing of the global flow rate of sea water feeding the turbine 121.
And in the case of the implantation of several apparatuses 110 in sites for which the currents are known beforehand (for example sites in which the currents are tidal currents) it is possible to predict beforehand the energy which will be conveyed towards the turbine 121, while maintaining this energy in desired ranges by controlled addition of the whole or part of the energies from the conduits 119.
In this embodiment like in all the others, it is moreover possible to provide a means for selectively orienting the pressurized fluid of the conduit 119 towards the turbine (energy conversion means) or towards an energy storage means (for example a tank located in height).
Finally, several hydraulic turbines 121 may be provided downstream from the manifold. This aspect will be developed with notably reference to
Energy <<Conversion or Storage>> Means
By <<energy conversion or storage means>> are designated means receiving the conveyed pressurized fluid from the pumping means.
These means may thus be energy conversion means such as a turbine activated by an intake 119 of pressurized water (example of
Such energy conversion means convert pneumatic or hydraulic energy of the pressurized fluid into an energy of a different kind, typically electric energy.
It is also possible that the <<energy conversion or storage means>> are energy storage means.
Thus these may be a tank of pressurized fluid. These may also be a fluid (notably water) tank, placed in height, wherein the energy is accumulated as a potential energy.
Moreover a means may be provided such as a three-way valve on the conduit for conveying pressurized fluid in order to selectively direct this fluid towards an energy conversion means, or an energy storage means, depending on what is desired at a given instant.
This possibility is schematically illustrated in
In this figure, a device portion 110 is seen, comprising means for recovering energy from the marine current, coupled with pumping means which send pressurized fluid into a conduit 119.
At its arrival on land, the conduit 119 is provided with a three-way valve which may be controlled in order to send the pressurized fluid towards a turbine 121, or towards a tank R in height which the fluid may attain by means of its pressure.
The tank may then be used for diverting its energy on the one hand, notably when the current of the fluid is low.
This possibility provides an additional solution for regulating the operation of the device.
For example, it is possible to select derivation towards the reservoir of pressurized water in the conduit 119 when the tidal current is the strongest, in order to then redirect this water towards the turbine 121 when the current is less strong.
Specifications on the Multicellular Centrifugal Pump
Compensation of the Thrust
In this section a few specifications will be given with reference to
The trajectories of the pressurized water are then illustrated by curved and arrowed lines.
Each stage Ei of the multicellular centrifugal pump is delimited by a vane which rotates around the axis of the pump.
Each vane comprises a central recessed portion for receiving in proximity to the axis A the water from the previous stage of the pump. The rotation of the vane ejects water through the sole outlet provided by the vane, i.e. a peripheral outlet.
The water is thus injected into the following stage, its pressure being increased by passing through the vane.
It is noted that the downstream face of the vane has facing the direction parallel to the axis A, a much larger surface than its downstream face (which is recessed in its central portion).
The resulting pressure applied on the vane is therefore directed upstream (towards the left of the figures—see
The added resulting pressures of the vanes of the multicellular centrifugal pump thereby generate counterpressure directed upstream which may be significant. This counterpressure is exerted on the rotary shaft which connects the pump to the energy recovery means located upstream from it.
By having such a multicellular centrifugal pump with its axis of rotation parallel or substantially parallel to the direction of the current, it is possible to counter the thrust exerted by the energy recovery means (propeller) on the pumping means. It is thus possible to balance the axial forces which are exerted between the members inside the apparatus.
This compensation effect, illustrated in
Self-Control
By using a multicellular centrifugal pump within the background of the invention, it is also possible to obtain an advantageous self-control effect on the speed of rotation of the energy recovery means.
These means as this has been stated, typically comprise a turbine, which should in practice rotate within a certain range of speeds of rotation.
Notably, the turbine should not rotate too fast (even if the increase provides extra power) since this might damage the device.
The power provided by the turbine is proportional to the cube of the velocity of the current.
On the other hand, the power absorbed by the pump is proportional to the cube of the speed of rotation of the axis (driven by the turbine). Therefore, the faster the axis rotates, the more powerfully the pump slows down the rotation of this axis—and therefore of the turbine, the axis of which is integral therewith.
This arrangement thereby allows self-control of the speed of rotation of the turbine, the runaway of which is prevented in the case of strong current.
Moreover, it is specified that according to a particular embodiment, it is possible to exploit this advantageous self-control effect by directly coupling the pressurized fluid outlet of the pump with the energy conversion means (a turbine driven by pressurized water), installed on site.
In this case, the energy would be converted on location, into electric energy, for example via an alternator with permanent magnets which, rotating at a constant velocity, is able to generate a current with a stable frequency.
This embodiment does not come under the main goals of the invention—it may nevertheless be considered as advantageous independently of the other aspects of the invention.
In this figure, the illustrated device 200 comprises a first portion 210 and a second portion 220, which may be localized at a distance from the first portion 210.
The first portion 210 comprises a mast 211 attached to the ground, a propeller 212 rotatably mounted relatively to the mast 211 (this propeller may also be positioned in a venturi), a first transmission shaft 213 capable of being driven into rotation by the propeller 212, a multiplier mechanism 214, a second transmission shaft 215, a compressor 216 capable of being driven by the second shaft 215.
The compressor 216 has an air inlet 2161 and an air outlet 2162.
The device further comprises a conduit 219 for transporting compressed air. The conduit 219 is connected at one of its ends to the outlet 2162 of the compressor 216 and at the other one of its ends to an inlet 2261 of a compressed air turbine 226 of the second portion 220.
The second portion 220 comprises a compressed air turbine (or motor) 226 and an electricity generator 222, such as an alternator coupled to the turbine 226. The compressed air turbine 226 comprises an air inlet 2261 connected to the conduit 219 through which compressed air is admitted and an air outlet 2262 through which air is discharged into the atmosphere.
During operation, the air circulating in the atmosphere (wind) drives the propeller 212 into rotation.
The movement of rotation of the propeller 212 is transmitted by means of the first driving shaft 213, the multiplier mechanism 214 and the second driving shaft 215 to the compressor 216. The multiplier mechanism 214 allows conversion of the movement of rotation of the first shaft 213 into a movement of rotation of the second shaft 215 having a higher speed of rotation.
The second driving shaft 215 drives the compressor 216. The compressor 216 picks up air from the atmosphere through the inlet 2161 and injects the picked-up air into the conduit 219 through the outlet 2162. The air is injected by the compressor 216 at a high pressure.
The compressor 216 causes the pressurized air to circulate in the conduit 219. The air is transported through the conduit 219 as far as to the turbine 226.
The pressurized air drives the turbine 226 into rotation.
The turbine 226 in turn drives the generator 222 which converts the movement of rotation of the turbine 226 into an electric current.
In this alternative, the device 200 comprises a conduit 219 for transporting compressed air and a conduit 229 for transporting a water+air mixture. The conduits 219 and 229 are connected to each other at a junction 239 immersed in a water expanse and forming an injector of the Giffard type.
The second portion 220 comprises a storage tank 223, a water supply conduit 224, a hydraulic turbine 221, of the Pelton or Francis type for example, and an electricity generator 222, such as an alternator, coupled to the turbine 221.
The storage tank 223 is located in height relatively to the turbine 221.
The tank 223 comprises two compartments 2231, 2232 and a recessed partition in its lower portion 2233 extending between both compartments. The first compartment 2231 is capable of being supplied with a water+air mixture through the conduit 229. This first compartment 2231 allows air to escape into the atmosphere, while the water of the first compartment 2231 may flow into the second compartment through the partition 2233.
During operation, the air circulating in the atmosphere (wind) drives the propeller 212 into rotation.
The movement of rotation of the propeller 212 is transmitted by means of the first driving shaft 213, the multiplier mechanism 214 and the second driving shaft 215 to the compressor 216. The multiplier mechanism 214 allows conversion of the movement of rotation of the first shaft 213 into a movement of rotation of the second shaft 215 having a higher speed of rotation.
The second driving shaft 215 drives the compressor 216. The compressor 216 picks up air from the atmosphere through the inlet 2161 and injects the picked-up air into the conduit 219 through the outlet 2162. The air is injected by the compressor 216 at a high pressure.
The compressor 216 causes the pressurized air to circulate in the conduit 219. The air is transported through the conduit 219 as far as the injector 239.
The injector 239 injects into the conduit 229 a mixture comprising air from the conduit 219 and water picked up in the water expanse. The water+air mixture is transported through the conduit 219 up to the storage tank 223.
The water passes from the first compartment 2231 to the second compartment 2232.
The water stored in the second compartment 2232 is used for feeding the turbine 221. The turbine 221 is driven into rotation by pressurized water from the storage tank 223. The pressure of the water which feeds the turbine is proportional to the height of the surface of the water contained in the tank relatively to the turbine 221.
The turbine 221 in turn drives the generator 222 which converts the movement of rotation of the turbine 221 into an electric current with a stable frequency.
It will be noted that the wind velocity varies continually, which necessarily causes a variation of the kinetic energy which may be collected by the propeller 212. However, the tank 223 provides regulation of the water flow rate which feeds the turbine 221 so as to regulate the speed of rotation of the turbine 221.
Moreover, as this is the case of the first embodiment, provision may be made for means for adjusting the orientation of the blades of the propeller 212 or of the turbine 221, so as to regulate the speed of rotation of the propeller 212 and/or of the turbine 221 and to obtain an electric current with a substantially constant period.
Provision may also be made for one or more propellers 212 each driving an associated compressor 216, which feed one or more compressed air motors or turbines 226 via one or more transport conduits 219, each motor or turbine 226 being coupled to one or more alternators 222.
In these figures, the apparatus 210 comprises a case 211, two propellers 212 laid out on either side of the case 211, a multiplier mechanism 214, a compressor 216 capable of being driven by the propellers 212 and a tube 218 of a generally convergent-divergent shape forming a venturi.
The case 211 and the propellers 212 extend inside the tube 218.
Illustration of Implantations in Marine Currents
In these figures, the apparatus 110 comprises a tube 118 with a convergent-divergent general shape forming a venturi.
The tube 118 is secured at the bottom of the sea via one or more securing chains 117. The tube 118 may also be bound up with a stake or to a platform, either submersible or not, itself anchored or attached on stakes.
The characteristics of a current generated by the tide are the following:
The characteristics (intensity and direction) of such a current are predictable and known.
The apparatus exposed to this current has the following characteristics:
In this case, the apparatus is attached to the bottom of the sea with a securing chain 117 or other means as defined earlier, and a rotary gasket 1191 so that the pressurized water generated by the pump may circulate without any incident in the transport conduit 119 regardless of the orientation of the apparatus.
In this case the apparatus subject to an alternating fluid flow comprises a turbine capable of being alternately driven in a first direction and then in a second direction opposite to the first direction. The apparatus comprises a reversing device capable of transmitting to the pump a movement of rotation in a constant direction in spite of the reversals of the direction of rotation of the turbine.
In an alternative of this embodiment, the apparatus comprises a turbine comprising a propeller with reversible blades and means for reversing the orientation of the blades of the propeller depending on the direction of the current, so that the turbine rotates according to a constant direction of rotation in spite of the reversals of the current direction.
The turbine may be a turbine of the Kaplan type comprising a propeller having blades with variable tilt, so that the tilt of the blades may be adapted to a velocity of the marine current, in order to obtain a substantially constant movement of rotation of the turbine.
The tube with a convergent-divergent shape generates a suction effect for sea water and allows acceleration of the velocity of the water which drives the turbine.
The turbine drives the centrifugal pump. The centrifugal pump is optionally laid out in an annexed bulb, which includes a sealing system of the first driving shaft, a retaining abutment and a speed multiplier. The speed multiplier is capable of converting a speed of rotation at the output of the turbine comprised between 100 and 600 revolutions per minute into a speed of rotation at the inlet of the pump comprised between 3,000 and 6,000 revolutions per minute. The pump may thus discharge water at a high pressure, of the order of 200 bars.
Means may be provided for compensating the torque generated by the turbine. According to a first possibility, the case of the apparatus may comprise fins or a rudder-wheel, optionally under control of the current velocity. According to a second possibility, the apparatus may comprise an even number of turbines, the turbines being associated per pair of turbines, two turbines of a same pair being driven in opposite directions of rotation under the effect of the same marine current.
Moreover, the apparatus is positioned at a sufficiently large depth in order to be safe from draughts of ships likely to be moving on the surface of the sea. Moreover, the apparatus is at a suitable distance from the bottom of the sea so that it may move without encountering natural obstacles.
The apparatus may comprise one or more anchors connected to the chain(s) for attaching the apparatus to the bottom of the sea. These are for example anchors such as those which are generally used for light ships, buoys of large size or even offshore drilling platforms.
As the apparatus is submersible, its shape is adapted so as to give it a suitable trim, at a given depth, and according to an orientation depending on the current.
Discharge of the water picked up by the centrifugal pump may be performed towards the bottom of the sea. According to a first possibility, the conduit for transporting pressurized water may be used as mooring line means, which requires the use of a rotary gasket in a fixed point in order to connect a first conduit portion from the apparatus to a second conduit portion intended for the land portion of the device, in order to allow the apparatus to swing.
According to a second possibility, a mooring chain or cable 117 provides securing of the apparatus while a conduit 119 provides the conveying of pressurized water towards the land portion of the device. In this case, a vertical outlet with a rotating point is provided on the apparatus. The conduit may be held in floatation above the apparatus by suitable means. The conduit is maintained at the floatation level over the whole trajectory followed by the apparatus during its swinging. This arrangement prevents possible interference between the mooring chain or cable and the discharge conduit.
According to an embodiment, the apparatus is immobilized by two mooring lines attached at two ends of the apparatus, which allows the apparatus to be maintained along a direction of the current. With this embodiment, it is possible to connect to a same conduit several apparatuses, each producing pressurized water.
In this alternative, the immersed apparatus 110 comprises means 130 for varying the orientation of the blades of the propeller 112. These means 130 comprise a mechanism 131 for orienting the blades, notably including a hydraulic actuator 132, servo-control means 133 for the hydraulic actuator, a tank 134 of pressurized liquid and a hydraulic circuit 135 for feeding the hydraulic actuator 132.
In such an alternative, a portion of the pressurized liquid produced by the pump 116 is picked up at the pump outlet 1162 and stored in the tank 134. The pressurized liquid stored in the tank 134 is intended to feed the mechanism for orienting the blades of the propeller 112. For this purpose, the control means 133 control the actuator 132 in order to vary the orientation of the blades of the propeller 112 according to the current. The actuator 132 is fed with pressurized liquid via the hydraulic circuit 135.
With the tank 134, a portion of the pressurized liquid may be stored in order to be able to control the orientation of the blades of the propeller 112, even when the propeller 112 is not driven into rotation. The pressurized liquid contained in the tank 134 forms a reserve of energy available for this purpose.
The apparatus 110 may further comprise a battery 136 and an electric generator 137 for the electric power supply of the servo-control.
The means 130 for varying the orientation of the blades of the propeller allow adaptation of the tilt of the blades to a velocity of the marine current, in order to obtain a substantially constant movement of rotation of the propeller 112 and to thereby smooth out the power collected by the latter.
Provision may be made for adjusting the tilt of the blades of the propeller 112 according to various parameters, such as:
With such a device it is possible to deliver an alternating current with a stable frequency.
It is thus possible to regulate this frequency, not only by a first adjustment of the needle of the supply nozzle of the remotely localized turbine 121 (when this is a Pelton turbine) or by an adjustment of the orientation of the blades of the turbine 121 (when this is Francis turbine), but also by a second adjustment of the orientation of the blades of the propeller 112 driving the pump 116. This dual adjustment provides upstream regulation of the flow rate and pressure of the fluid feeding the turbine 121 and a quasi-constant speed of the alternator 122 may be obtained by combining both regulation modes if necessary.
The first adjustment applied to the turbine 121 allows the water supply rate of the turbine 121 to be varied, which has the effect of adjusting the driving speed of the alternator 122. With the second adjustment applied to the propeller 112 it is possible to vary the speed of rotation of the pump 116 according to the velocity of the current, which has the effect of adjusting the pressure of the water injected into the conduit 119 at the pump outlet. The first and second adjustments may be controlled either independently or concomitantly.
The parameters of the regulation program may either be pre-recorded in a memory of the control means 133 or be transmitted from the land portion 120 to the control means 133, via a wire or waves for example.
Finally, the apparatus 110 comprises a conduit 138 for having the inside of the case 11 communicate with the atmosphere. The conduit 138 may for example be integral with the pressurized water circulation conduit 119 towards the portion on land 120. Alternatively, the conduit 138 may be independent of the conduit 119. In this case, the conduit 138 may comprise an end maintained at the surface of the water by a float (such a float may for example support a plurality of similar conduits from other immersed apparatuses). The conduit 138 may be used as a conduit for renewing air or gas in order to inject air or neutral gas into the inside of the apparatus 110.
Both apparatuses 110 are positioned in parallel and attached to each other. Both apparatuses 110 are identical, except that they comprise propellers 112 capable of rotating in opposite directions relatively to each other. With this characteristic, it is possible to cancel out the effects of the moments generated by each propeller 112.
Both venturis 118 are maintained in constant positions relatively to each other and delimit between them a defined and constant space.
As illustrated in
Further, communication means (airlock) between the maintenance apparatus and each of the apparatuses 110 may be provided in order to allow the operators to penetrate inside the cases 111 of the apparatuses in order to proceed with possible inspection or repair operations.
Provision may also be made for having either one of the sides of the maintenance apparatus include one or more airlocks providing access to corresponding airlocks or corresponding doors on each propeller-pump assembly.
This will allow each propeller-pump assembly to communicate directly with the maintenance apparatus.
The maintenance apparatus may also be secured to the apparatuses 110 in order to allow on-site installation or displacement on a selected site of the apparatuses 110, with view to maintenance or modification of the apparatuses 110.
Lifting or hoisting means may be integrated to the maintenance apparatuses or to the devices allowing the mooring chain or cable 117 of the apparatuses to be dissociated or to be relinked together.
Application to a Multisource Configuration—Use of Manifolds
A few details will be given here on particular means for controlling the operation of a device according to the invention, exposed to non-constant currents.
As this was already mentioned, it may be advantageous to provide several assemblies 110 each forming a source of pressurized fluid in order to couple their conduits 119 to one or more devices 120 on land including a turbine and an alternator so that the latter operate under the best selected conditions in order to directly deliver an electric current with a suitable period.
The device comprises a manifold receiving pressurized fluid from several sources of type 110 (propeller-pump pairs) TP1, TP2, TP3 and delivering according to a pre-established program pressurized fluid to one or more energy conversion means of the type 120 (turbine-alternator pairs PA1, PA2, PA3), by a suitable valve control procedure.
The manifold may allow all connection combinations between one or more of the sources TP1, TP2, TP3 on the one hand with controlled admission rates from each source, and one or more of the energy conversion means PA1, PA2, PA3 on the other hand.
Depending on the rated operating characteristics of each energy conversion means (which correspond here to the <<second>> energy conversion means according to the conventions of this text), and on the characteristics of the currents in locations where the three sources are implanted, the connections of the manifold may be programmed in order to operate one or more of the energy conversion means.
In the case of tidal currents, as the characteristics of the currents are known beforehand, this programming may also be performed beforehand. And depending on the characteristics of the currents in a given region, the energy recovery turbines as well as the second energy conversion means, may be dimensioned in order to maximize the global yield of the system while operating the different components in their rated range.
The source TP1 is associated with the current intake 171, which includes an upstream section 171a and a downstream section 171b capable of supplying current to the source.
In the same way, the source TP2 is associated with the current intake 172, which includes an upstream section 172a and a downstream section 172b capable of supplying current to the source.
Both of the current intakes placed upstream from both respective sources are moreover connected through transverse channels 1710 and 1720.
The channel 1710 may divert towards the current intake 172 the flow engaged in the upstream section of the current intake 171, if the flap 1711 is in the position for closing the channel (a position illustrated in dotted lines).
In the same way, the channel 1720 may divert towards the current intake 171 the flow engaged in the upstream section of the current intake 172, if the flap 1721 is in the position for closing the channel (a position illustrated in dotted lines).
By controlling the position of the flaps 1711 and 1721, it is possible to selectively feed one or two of the sources with the current. It is also possible to concentrate on a unique source the flows engaged in both current intakes. It is also possible to close one of the two intakes, or both (for example, for reasons of maintenance).
Thus an <<upstream>> manifold is available, positioned before the sources in order to control the intensity of the flow passing through each source.
And on this diagram, a downstream manifold similar to the one of
The two upstream and downstream manifolds of
Here again, the operation of each of the two manifolds may be programmed—for example according to characteristics known beforehand of the current.
The upstream manifold and the downstream manifold are two means—which may advantageously be combined—in order to control the operation of the energy conversion means PAi.
| Number | Date | Country | Kind |
|---|---|---|---|
| 0753820 | Mar 2007 | FR | national |
| 0754757 | Apr 2007 | FR | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP08/53130 | 3/14/2008 | WO | 00 | 1/19/2010 |
