The present invention deals with a plant for recovering energy from a fluid flow, in particular water, exploiting the positive and negative pressure values according to the difference in level of water accumulation basins arranged along the hydraulic circuit composing the plant.

Documents FR-A1-2462585 and DE-A1-1004 372 disclose plants according to the preamble of Claim 1.

Object of the present invention is solving the prior art problems, by providing a plant for recovering energy from a fluid flow which is extremely efficient, easily manufactured and with reduced cost.

The above and other objects and advantages of the invention, as will result from the following description, are obtained by a plant for recovering energy from a fluid flow, as claimed in Claim 1. Preferred embodiments and non-trivial variations of the present invention are the subject matter of the dependent claims.

It is intended that all enclosed claims are an integral part of the present description.

In a first preferred embodiment, the plant of the present invention is substantially composed of a fluid column placed under negative (static) pressure, from which liquid is taken through a pump and is transferred in the falling part with a positive pressure, using a compensating circuit composed of various elements which allow sending to the energy generator a fluid flow with a positive thrust composed of the sum of the forces generated in the various steps of the path travelled by the fluid.

In a second preferred embodiment, the plant of the present invention is substantially composed of two columns placed at the same positive pressure, which create the conditions under which the fluid flow passing by the various elements composing the plant reaches the energy generator with a positive thrust, benefiting from the sum of forces generated in the path travelled by the fluid.

The features of the plant according to the present invention will result from the following detailed description of its components and afterwards of the operating principle of the plant itself, with reference to enclosed Figures 1 and 2 which schematically show the two preferred embodiments of the plant of the present invention, as regards both constitution and operation of the plant. Every plant component can be made with the most suitable elements and materials for this purpose, the diagrams given below being provided merely as an example for a full understanding of the invention.

With reference to Figure 1, a first embodiment of the plant of the present invention is shown. Figure 1 shows the following components:

1) Big fluid reserve basin, which is on the ground surface, where volumes and surfaces are determined by the needs of the plant. This basin can be both artificial, and natural, like a lake, river, sea, torrent, etc., where levels, volumes and surfaces will be constant or scarcely variable; this part will always be the part at the lowest level with respect to the other parts composing the plant, such as for example the sea surface level meant as zero. This basin, in addition to natural, can also be artificial and built with building material, such as concrete, steel, plastics, glass, etc. The features of the material must be with low friction coefficient to facilitate handling the fluids; in any case, this basin will have to show such technical building features as to allow a resistance to stresses of the forces acting outside and inside it. This basin could be open or totally closed: this choice will be dictated by the needs of the type of plant, when working either with natural pressure or with artificial pressure.

2) Fluid level in the reserve (1) and in the exchange chamber (7).

3) Gas which is found in the reserve (1) , in the exchange chamber (7), and also in the backup gas chamber (17).

4) (4al) Inlet tube in the reserve (1) and (4a2) outlet tube from the reserve (1) . These tubes must be arranged under the fluid level in the reserve (1) and are used for different applications.

C) Tap for checking the level (2) in the reserve (1) .

D) Big tap (gate) which can be found above the cover of the reserve (1), and is used to put in natural balance the fluid mass in the plant when the plant operates under natural pressures.

E) Tap which is used for injecting pressure in the reserve (1); this pressure is then transferred to the major point of the plant such as in the exchange chamber (7) and in the backup gas chamber (17)

R) Sleeve which is used to apply the measuring instruments like the barometer.

5) Fluid rising tube - This building element is sized depending on operating needs and amount of fluid which has to be moved through it; the geometric shapes of this part can change depending on technical and operating needs. This part can be made of different types of material, suitably with low fluid friction coefficient, and extremely low fluid sliding speeds, and building features which are resistant against forces operating inside and outside this part.

6) Lower gate which is used to fill the plant. 7) Exchange chamber which can be found in the upper part of the plant; this part needs an absolute insulation from external conditions and that its geometric features make it resistance to internal and external operating forces. Surfaces and volumes of this part, as well as its geometric shapes, have to be evaluated according to the amounts of fluid or gas present therein, which determine the plant efficiency.

8) Tap for exhausting liquid or gaseous fluids inside the exchange chamber (7).

9) Sleeve with tap for connections to measuring instruments which will point out the forces therein and the possible negative or positive drops.

10) Fluid compensating reserve, which is connected under the exchange chamber (7), always placed in parallel to the rising tube (5) and at the same height; this part is used to supply the pump (12) suction, keeping the fluid level constant. The variation in the upper part thereof triggers a fluid recall and it must be kept in mind that geometric shape and surfaces can facilitate this fluid recall, benefiting in the plant efficiency; the sizes will have to take into account the flow speed and the amount of exiting fluid; the building materials of this part will hae to support internal and external forces, and the geometric shapes will have to be evaluated depending on efficiency.

11) Suction tube: this component, connected to the pumping system, is completely immersed into the previous component, the compensating reserve (10); the position of this component is parallel to the part in which it is immersed; its sizes are proportional to the exchange amounts; this part will have a greater internal flow speed. This tube can be geometrically built with sizes which make its suction easier; the materials to be adopted need low resistances to fluid flows and good insulation from external fluid.

12) Pump or fluid exchange system: this part of the plant can eb used with any type of pump or fluid exchange system, provided that suction creates values equal to negative pressure values which can be found in the exchange chamber when it is under static conditions (before starting the pump) ; setting these pressures equal facilitates the fluid exchange from suction to exhaust under positive pressure; the pump exhaust is connected insulated from influences due to the release compensator. This part, which accompanies the fluid flow, is suitably made in a conical shape, in which flow is unified in a bunch of sizes suitable for the exiting amounts and for increasing the flow speed and increase the dynamic dragging; the building materials for this exchange or pumping system are advised with low friction coefficients.

13) Tap for exhausting the section between suction tube (11) and compensating chamber (14) : it is placed to guarantee air or gas exhaust inside the exchange section.

14) Compensating chamber which is used as exchange point of pressure, volumes, density between pump outlet and release compensator, in which, when the dynamic fluid acceleration process is triggered, the gas contained in the upper part, which exceeds the fluid level is compressed or decompressed in such a way as to allow the pump to freely exhaust and that the fluid flow is free in its fall and can benefit from gravity and acceleration induced by the pump; these components need geometries, volumes and surfaces suitable to the amount of exiting fluid, and their building features must support external and internal forces.

15) Tap for exhausting gas and liquid in the compensating chamber (14).

16) Accompanying cone which is placed perpendicular above the duct (18) collector, almost down the compensating chamber (14) bottom, which is used to accompanying the fluid in a laminar way, when exiting the pump.

17) Backup gas chamber: it is a gas reserve which is used to guarantee the release of fluid under free fall, this due to the difference in density between fluid and gas itself, creating the necessary space or advancing the fluid when exiting the pump.

18) Collector of the duct which goes downwards and is under the conical accompanying tube (16) of the pump (12) exit: it is used to facilitate the fluid collection, to then go on into the duct (19) towards the turbine (26) down. This collector can be conical, but also cylindrical: the conical shape is preferred due to a better efficiency, and must be made of rigid material, possibly coated with material having a low friction coefficient.

19) Duct which is used to accompany the fluid downwards along the turbine (26) direction: it can have different shapes, such as squared, cylindrical and conical, preferably conical for a better efficiency; it must be made of a rigid material, possibly coated with materials with low friction coefficient .

20) Gate of the duct (19) which is used for regularly filling the plant and for guaranteeing that, when filling, there is no air or gas inside the section.

21) Duct which connects the reserve (1) below with the backup gas chamber (17) on the top, with their respective taps (21a) and (21b) .

22) Tap with sleeve to check and drive or measure the gas or air flow in the gas chamber (17)

23) Duct which connects the compensating chamber (14) to the backup gas chamber (17) .

24) Tap which is used to exhaust gas or fluid in the turbine chamber (25) .

25) Turbine chamber.

26) Turbine, which can be of different types, such as Kaplan, Peltron, Francis and so on.

27) Exhaust cone in the reserve (1).

A description will now be made about the operating principle of the plant, with reference to its previously listed components.

The plant is loaded with fluids regularly through its entry tap (6), suitably made for this operation. The closure of the tap (20) above the turbine chamber (25) is ensured, and, once having set the correct level for the plant fluids using the suitable taps for adjusting the fluids, such as tap (C) for the big reserve (1) level, tap (8) for the exchange chamber (7), tap (13) for exhausting the suction tube (11) and pump (12), and the exchange chamber with tap (15) when filling, complying with the levels (2) already preset and provided for its operation, one makes sure that all parts where fluid flows has no conditions which impair the correct operating cycle, and, once the plant has been regularly loaded, its operating procedure starts.

By opening the big gate (D) which is above the reserve (1), all the fluid mass in the rising tube (5) takes to a negative pressure the exchange chamber (7) and consequently all fluid in the plant, where all pressure values in the plant are conditioned from the atmospheric pressure (static condition) .

According to these values, the fluid which is in the exchange chamber (7) has the higher negative pressure value. Starting from the top and going downwards, there is a pressure situation where the values found in the exchange chamber (7) are depending on the plant height: the pressure value starting from the exchange chamber (7) upwards towards the big reserve (1) will go from a negative pressure up to a pressure equal to the big reserve (1) one, namely the atmospheric pressure.

The same pressure value can also be found in the suction tube (11), which is completely immerses into the fluid contained in the compensating reserve (10) which communicates with the same level of the big reserve (1), starting depending on the pressure of the big reserve (1) up to its maximum height which is under negative pressure (-) .

The same pressure value can also be found in the descent column starting from the pump (12), with negative pressure and then down in the compensating chamber (14) and column (19) and towards the turbine (26) which is at the pressure of the big reserve (1) . (From point 12 with minus pressure to point 26 at atmospheric pressure.)

All these positive or possibly negative pressure values are present when the pump exchanger member 12 is not operating (static condition) .

To create a situation in which advantage can be had of the dynamic movement of the fluid, the pump (12) must be actuated, which creates, from the big reserve (1) till the entry of the pump (12) through the suction tube (11) , a dynamic negative pressure condition, equal to the previously statically created static negative pressure condition in the exchange chamber (7).

At the same time, fluid exiting the pump (12) assumes a positive pressure condition, which divides the influence of the negative pressure entering the pump (12) from the positive one exiting, and consequently changes the pressure condition of the descent column from point 12 (pump) till point 26 (turbine) , including the pressure condition of the backup gas chamber (17). The amount of outgoing flow and the pressure condition created by the pump (12) must be compensated with the accompanying cone (16) which extends almost till the collecting cone (16) perpendicular with the column (19), with the compensating chamber (14) and the backup gas chamber ( 17) which are connected through the duct (28) and is above the plant level. Under these conditions, it is possible that the pressures exiting the pump (12) are recovered due to the drop of the fluid accelerating from point 12 till point 26 next to the gravitational effect also positively summed to the drop of fluid going out of the outlet cone (27), directly falling into the big reserve (1) to again repeat the plant cycle. The operation of the plant with induced pressure will now be described.

The process for filling the plant with fluid is the same as described above.

Also the operating process is the same, apart from that, in this case, there is an induced positive pressure. By inducing pressure from the tap (E) in the big reserve (1) according to the physical plant construction, there is no limit in injecting pressure.

The only difference is that, in the above described plant, there are different positive values: in the big reserve (1) and in the backup gas chamber (17) there is the maximum positive pressure, instead in the exchange chamber (7) there is a lower pressure than the one in the big reserve (1) .

The big reserve (1) and the backup gas chamber (17) have the same pressure value because they are connected through the duct (21) which is driven with respective taps (21a) and (21b) .

In this case, in order to discharge the fluid in the big reserve (1), tubes are used with diameters and surfaces computed according to the pressure induced in the plant. With reference now to Figure 2, a second preferred embodiment of the plant of the present invention is shown. Figure 2 shows the following components :

1') Turbine chamber, which can be found in the lower part of the plant: this chamber can be made with different sizes, depending on needs of the plant which has to be built, and in any geometric shape: it is enough that it guarantees the resistance to internal and external forces in play. Materials must have features with low friction coefficient.

2') Turbine, which is placed in the chamber (l ¹ ) and which can be of different construction types, such as Kaplan, Fancis, Peltron, and other types of turbines which can be found on the market or of a particular application design .

3') Tube which connects the turbine (2 ¹ ) outlet with the pump (4 ¹ ) inlet: this tube can have different types and geometric shapes suitably made for this purpose, and must be built with material possibly with low friction coefficient. ) Pump or fluid exchange system: this part of the plant can use any type of pumping or fluid exchange system, provided that the pressure generated at its outlet has values which are equal to or greater than the positive pressure values which can be found in the chamber (5').

) Chamber for discharging the pump (4'), which can be found in the lower part of the plant with respect to the ground: this chamber is sized, both as geometry, and as volumes, depending on the plant operating needs; the chamber must guarantee the resistance to internal and external forces in play. Materials must have features with low friction coefficient.

) Discharging tube for the pump (4'), which is joined to the pump (4') and extends till above the fluid level (E) , which can be found in the chamber (5'); it can have different geometric shapes, and is built with a material possibly with low friction coefficient, which guarantees the resistance to internal and external forces.

) Fluid rising tube: it is connected in the lower part with the chamber (5'), and in the upper part with the connection chamber (8'); its height determines the positive pressures inside the plant, and can be made with geometric shapes at will, which comply with the plant operating requirements. Construction materials must have a low friction coefficient and must guarantee the resistance to external and internal forces.

) Connecting chamber: it is placed in the upper part of the plant, and connects the rising fluid flow of the tube (7 ¹ ) to the descending flow of the tube (9'); this part of the plant has twp types of fluid, namely the circulating fluid between rise and descent, and the gaseous fluid which remains in the upper part of this chamber. This chamber can be built with different geometric shapes, and construction materials must guarantee the resistance to operating forces, possibly with low friction coefficient.

) Descent tube: in this part of the plant, fluid flows towards the turbine (2 ¹ ), with acceleration due to the gravitational effect; this tube can have different geometric shapes, but must be sized with right proportions depending on the amount and speed of fluids which cross it; construction materials must guarantee the resistance to internal and external operating forces. Construction materials must have a low friction coefficient. ') Tap which is used to adjust the machine functionality. ') Tap which is used to adjust the machine functionality. ') Tap which is placed above the chamber (5 ¹ ), and is used to adjust internal chamber conditions, such as volumes, pressures, levels and density of fluids inside it. ') Tap which is placed above the chamber (1'), and is used to adjust internal chamber conditions, such as volumes, pressures, levels and density of fluids inside it. ') Tap which can be found in the lower part of the chamber (1') and adjust the conditions of internal chamber fluids. ') Tap which can be found in the topmost part of the plant in the connecting chamber (8 ¹ ): it is used to adjust the conditions of gaseous fluids in this part of the plant. 16') Tap which can be found in the upper part of the connecting chamber (8'): it is used as service for plant fluids.

17 ' ) Service tap for the plant which can be found below the chamber (5')

18') Tap for loading and unloading the plant.

19') Service tap placed below the connecting chamber ( 8 ' ) .

20') Service tap placed below the connecting chamber (8').

A) Fluid level in chamber (1').

B) Fluid level in chamber (5').

C) Fluid level in chamber (8').

D) Gas contained in chamber (Ι'). E) Gas contained in chamber (5').

F) Gas contained in connecting chamber (8') .

A description of the operating principle of the plant will now be made, with reference to its previously listed components. The plant is regularly loaded with fluid through the tap (18'), suitably built for this operation. Before starting the plant filling, one makes sure that the taps (15') and (16') in the upper pat are open. Once having regularly filled- in the plant, complying with levels (A) , (B) and (C) provided for its operation, the plant is ready to operate.

By actuating the pump (4') motor, the fluid starts being transferred from the chamber (1') towards the chamber (5'): this subtraction of fluid from the chamber (1') gives room to fluid coming from the descent tube (9'), which benefits from the gravity acceleration; this kinetic condition is obtained due to gases contained in chamber (1') and in chamber (8'), which allow the necessary space, and enable fluid to give to the turbine (2') the resulting kinetic energy.

In this transfer of fluid, the pump (4') will have the gravity as single opposing force, which will oppose from the pump (4') outlet till the tube (6') outlet, in the chamber (5'), and not the whole column of the rising tube (7'), thereby benefiting of the maximum amount of fluid which the pumping system can move. The pressure created by the pump (4 ¹ ) will be summed to the pressure of the turbine (1') chamber due to the column height of the descent tube {9') , with the result of enabling the exchange of fluid taken in the chamber turbine (1') and discharged in the pump discharge chamber (5').

Gas contained in the chamber (l ¹ ) enables the pump suction and the exhaust of the turbine {2') , since pressure and volume conditions being found in the chamber (1') will balance the pressure and volume of the chamber (5 ¹ ), since the gas density increases in a very low percentage when the pressure increases.

The fluid moved by the pump (4') joins the fluid contained in the chamber (5 ¹ ) : the pressure differential induced by the pump (4 ¹ ) will be summed as acceleration factor in the fluid movement towards the turbine (2'), through the connecting chamber (8 ¹ ) and the descent tube (9')· The diameter of the rising tube (7') will be sized depending on the pressure difference produced by the pump (4 ¹ ): this to obtain that the amount of fluid moved towards the rising tube (7') balances the amount of fluid crossing the descent tube (9 ¹ ) down to the turbine (2'); since the sliding speed of fluid in the rising tube (7') depends only on the pressure difference generated by the pump (4'), while in the descent tube (9') the fluid speed depends on the acceleration due to gravity, it will therefore be necessary to size such tubes appropriately with different computations.

Having thereby described in detail the plant and its operation, it must be understood that only two preferred embodiments have been described here, but that numerous variations, modifications, additions and/or replacements of parts can be made to individual components, without thereby departing from its fundamental principles, and without also departing from its scope, as defined in the enclosed claims.