EP2016282A2

EP2016282A2 - Turbine and hydroelectric plant comprising said turbine

Info

Publication number: EP2016282A2
Application number: EP07734448A
Authority: EP
Inventors: Lino Rossi; Savino Frigiola
Original assignee: Ener Water Ltd
Current assignee: BONCIANI S.P.A.
Priority date: 2006-05-05
Filing date: 2007-04-24
Publication date: 2009-01-21
Also published as: WO2007129185A3; ITRN20060029A1; WO2007129185A2

Abstract

The turbine 2 comprises a runner (2) rotating relative to its own axis of rotation (20). The runner (2) in turn comprises at least one blade (21), said blade (21) being able to be at least partially immersed in a liquid stream (22) with free surface. The runner (2) is operatively connectable to an electric generator. The turbine (1) characteristically comprises: -a base suitable to interact directly with the outside environment to support the weight of the turbine (1); -means (3) for raising and lowering the axis of rotation (20) of the impeller (2) relative to at least one part of the base (4).

Description

Turbine and hydroelectric plant comprising said turbine

Technical Field

The present invention relates to a turbine. The present invention further relates to a hydroelectric plant comprising said turbine.

Turbines are machines that convert the energy of a fluid stream into mechanical energy. Said mechanical energy can then be transformed by an electric generator into electrical energy.

Background Art

Known hydroelectric apparatuses comprise a runner, rotating relative to its own axis of rotation and mounted on a hull floating in a body of water. Said runner comprises a plurality of blades immersed in a liquid flow with free surface and it is operatively connected to an electric generator.

The hydroelectric apparatuses indicated above have some drawbacks.

In particular, both mounting and dismounting the runner and every kind of maintenance thereon is impossible, unless the flow of the liquid stream is previously deviated for the time required for the operation. Otherwise, the runner w ould b e e onstantly m aintained i n r otation b y t he action o f t he liquid stream. It is evident that extremely complex and costly structures must be provided in order to deviate or interrupt the flow of a body of water.

Moreover, it is not possible, in use, to regulate the velocity of rotation of the runner, a parameter to which the electrical energy produced is closely linked. Said velocity therefore remains a function of the velocity of the flow of the water body wherein the hull is immersed.

Disclosure of the Invention

An object of the present invention is to overcome the drawbacks described above, making available a turbine which facilitates maintenance, mounting and dismounting operations on the turbine.

Another object of the present invention is to make available a turbine that enables to regulate the velocity of rotation of the runner.

A further o bj ect o f t he present i nvention i s t o make a vailable a h ydroelectric plant comprising said turbine.

These and other objects, which shall become readily apparent in the description that follows, are achieved, in accordance with the present invention, by a turbine having structural and functional characteristics in accordance with the appended independent claims, additional embodiments of the present invention being identified in the appended and corresponding dependent claims.

Brief Description of the Drawings

The invention is described more in detail hereafter with the aid of the drawings, which show a purely exemplifying, non limiting embodiment thereof.

- Figures 1 and 2 respectively show a perspective view and a plan view of a turbine according to the invention in a first configuration.

- Figures 3 and 4 respectively show a perspective view and a plan view of a turbine according to the invention in a second configuration.

- Figures 5 and 6 respectively show a lateral view and an interrupted plan view of a hydroelectric plant according to the invention.

- Figure 7 shows a plan view of a hydroelectric plant according to the invention.

- Figures 8, 9 show two schematic views according to the section plane A-A of Figure 7 showing two operating conditions of the hydroelectric plant shown in Figure 7.

- Figure 10 shows a partially interrupted perspective view of a detail of a part shown in Figures 7, 8, 9.

- Figure 11 shows a perspective view of a particular application of the turbine according to the invention.

Figure 12 shows a schematic plan view of a hydroelectric apparatus according to the present invention.

Detailed Description of the Preferred Embodiments of the Invention With reference to Figures 1, 2, 3, 4, the reference numeral 1 indicates a turbine according to the invention.

The turbine 1 comprises a runner 2 rotating relative to its own axis of rotation 20. hi turn, the runner 2 comprises at least one blade 21. The blade 21 can be at least partially immersed in a liquid flow 22 with free surface. The runner 2 is operatively connectable to an electric generator. The turbine 1 characteristically comprises a base 4 suitable to interact directly with the outside environment to support the weight of the turbine 1. The turbine 1 comprises means 3 for raising and lowering the axis of rotation 20 of the runner 2 relative to the base 4 or at least one part of the base 4. Advantageously the runner 2 comprises a plurality of blades 21. These blades 21 advantageously develop radially. The lifting and lowering means 3 actuate the axis of rotation 20 between a first configuration, in which said axis of rotation 20 is placed at a first predetermined height, and a second configuration in which said axis of rotation 20 is placed at a second predetermined height. The second predetermined height is greater than the first predetermined height. The term "height" means the vertical component of the distance of the axis 20 of rotation from a fixed reference positioned below the turbine 1. This first configuration is advantageously exemplified in figures 1 and 2, whilst the second configuration is advantageously exemplified in figures 3 and 4. Advantageously said first configuration corresponds to a configuration in w hich t he r unner 2 c an b e a 11 east p artially immersed for a p redetermined depth into the liquid stream 22. Similarly, said second configuration corresponds to a configuration in which the runner 2 cannot be at least partially immersed into the liquid stream.

The expression "can be at least partially immersed" means that the runner 2 as a result of a complete turn around its own axis of rotation 20 submerges at least partially in the liquid stream 22.

Advantageously the lifting means 3 position the axis of rotation 20 in at least one intermediate configuration between the first and the second configuration. In this intermediate configuration, the axis of rotation 20 will be at an intermediate height relative to that of the first and of the second configuration. In this way, the maximum immersion of the blade 21 into the liquid stream 22 can be regulated. This enables to regulate the thrust exerted by the liquid current 22 on the blades 21 and hence the velocity of rotation of the blade 2. Advantageously said turbine 1 comprises a sensor for measuring the velocity of rotation of the runner 2 and means for commanding the lifting and lowering means operatively connected to the sensor 200 for measuring the velocity of rotation of the runner 2 to maintain constant the velocity of rotation of the runner 2.

The lifting and lowering means 3 determine a translation of the axis of rotation

20. Preferably, the axis of rotation 20 of the runner 2 is horizontal. As shown in the accompanying figures, the axis of rotation 20 can be positioned outside the liquid stream 22. As shown in the accompanying figures, advantageously the axis of rotation 20 of the runner 2 is transverse, preferably orthogonal, to the flow of the liquid stream 22.

The lifting and lowering means 3 connect each of the two axial ends 23, 24 of the runner 2 with a corresponding area 230, 240 of the base 4.

In particular, the runner 2 is interposed between the two areas 230, 240 of the base 4 and the liquid stream 22 flows between said two areas 230, 240 of the base 4.

The turbine 1 advantageously comprises means 5 for supporting the axis of rotation 20 of the runner 2, said supporting means 5 comprising a first portion

51 integral with the axis of rotation 20 of the runner 2 and a second portion 52 integral with the base 4.

As shown by way of example in figure 1, in said first configuration the second portion 52 abuts against the first portion 51. Preferably, the lifting and lowering means 3 comprise a mechanism of the articulated quadrilateral type 6. An

"articulated quadrilateral", in the exemplifying configuration shown in figure 3, comprises a system of four bodies 63. Said four bodies 63 have a preponderant direction of development, they are arranged consecutively, they are hinged together in twos at the ends, in order to materialise a deformable planar quadrilateral. Said bodies 63 could, by way of example, be constituted by rods. The lifting and lowering means 3 advantageously comprise a mechanism of the articulated parallelogram 60 type. An articulated parallelogram 60 comprises an articulated quadrilateral 6 in which the direction of preponderant development of the bodies 63 arranged one opposite the other, are always parallel. Said first and said second portion 51, 52 comprise respectively connecting rod 61 and frame 62 o f the articulated p arallelogram 60. hi figure 3 , the frame 62 i s the body that remains substantially fixed in space as a result o f the action of the lifting and lowering means 3. The connecting rod 61 is the body 63 opposite the frame 62. In the exemplifying and non limiting embodiment shown in figure 3, each body 63 of the parallelogram that connects frame 62 and connecting rod 63 comprises a pair of rods, parallel and positioned at a short distance. This is simply to improve the structural resistance of the lifting and lowering means 3, but without altering the operating principle of the mechanism. As exemplified in the accompanying drawings, the lifting and lowering means 3 are operatively comiected both to the first portion 51 and to the second portion 52.

The second portion 52 comprises a protrusion 520 with vertical development; the lifting and lowering means 3 develop between a first point 511 of the first portion 51 of the supporting means 5 and a second point 512 of the protrusion 520 with vertical development. The second point 512 is positioned at a greater height than said first point 511. hi the embodiment shown in figures I₅ 2, 3, 4, the lifting and lowering means 3 comprise fastening means 30 operating in traction. Said fastening means 30 operating in traction comprise a first end connected to said first point 511 and a second end connected to a coiler 31 positioned in said second point 512. Examples of said fastening means 30 operating in traction are ropes, chains, etc. In an alternative embodiment, not shown, the lifting and lowering means 3 comprise a fluid-dynamic actuator.

Advantageously the base 4 comprises bearing means 64, suitable to be abutted by a solid support. In figure 11, with said bearing means 64 is indicated the lower portion of the frame 62, which bears directly on an external support. Depending on the specific embodiment, the bearing means 64 could, however, comprise or coincide with other parts of the base 4.

In a first embodiment, not shown, the base 4 is stably fixed in space. It unloads the w eight o f t he t urbine 1 d irectly t o t he g round. F or e xample, t he r unner 2 could be positioned internally to an outflow channel with free surface, and the base 4 that supports the runner 2 could be obtained externally to said channel or on the edge of the channel itself. In an alternative embodiment, the turbine 1 comprises flotation means 40, able to be fastened to a fixed point in space, e.g. by means of a rope, hi this case, the turbine 1 can be placed within a body of water. Advantageously, the flotation means 40 can be connected by means of the rope to a fixed point obtained in the riverbed, to a bridge or to other infrastructures. This connection enables the runner 2 to start rotating when it is impacted by the liquid stream 22 and prevents the turbine to be carried away by the liquid stream 22.

Preferably, the flotation means are shaped as hulls 41. Advantageously, the base 4 comprises the flotation means 40. Said flotation means 40 interact with a body of water to support, exploiting Archimedes' buoyancy, the entire turbine 1. If the depth of the water is not sufficient (e.g., because in a given period of the year the body of water is dry), the flotation means 40 advantageously lie on the bottom, unloading thereon the weight of the turbine 1. In this circumstance, the bearing means 64 suitable to be abutted by a solid support comprise the flotation means 40. A lternatively, t he b ase 4 m ay c omprise b earing m eans 64, d istinct from the flotation means 40 and suitable to be abutted by an external solid support. In this way, the floating means 40 do not lie on the bottom even when the depth of the water is low, because said bearing means 64 intervene first. For example, said bearing means 64 comprise the frame 62 as previously indicated. In an additional embodiment, both the flotation means 40 and said bearing means 64 are simultaneously abutted by external supports. A turbine 1 of the type described above, comprising the flotation means 40, can be employed directly in a body of water, or it can be used in combination with the infrastructures shown in figures 5 through 9 and described subsequently. As shown in figure 3 and 4, the turbine 1 advantageously comprises an appendage 42 which can be raised and upset to minimise the size of the turbine 1, in particular when packing and transporting it.

The base 4 advantageously comprises said appendage 42. The turbine 1 advantageously comprises auxiliary lifting members 32 to actuate said appendage 42. In particular, said appendage 42 during normal use is placed in the operative configuration shown in figures 1 and 2. To facilitate transport, especially but without limitation to allows its introduction in a container, the appendage 42 can instead be raised. I f said appendage 42 is connected to the flotation means 40, said means, before the appendage 42 is raised, are dismounted and transported separately. The p resent i nvention further r elates t o a h ydro electric p lant 1 0 c omprising a turbine 1 of the kind described previously.

In particular, said hydroelectric plant 10 comprises at least one turbine 1, which in turn comprises the lifting and lowering means 3. Said lifting and lowering means 3 actuate the axis of rotation 20 between a first configuration, in which said axis of rotation 20 is placed at a predetermined height, and a second configuration in which said axis of rotation 20 is placed at a second predetermined height. The second predetermined height is greater than said first predetermined height. hi the first configuration, the runner 2 can be at least partially immersed in the liquid stream 22; in the second configuration, the runner 2 is completely outside the liquid current 22. The expression "can be at least partially immersed" means that the runner 2 as a result of a complete turn around its own axis of rotation 20 submerges at least partially in the liquid stream 22.

With reference to the embodiment shown in figures 5 and 6, the hydroelectric plant 10 comprises: a body of water 7; a flow channel 9 with free surface positioned internally to the bed 70 of the body of water 7. Said flow channel 9 is also positioned on the bottom of the bed 70 of the body of water 7.

Advantageously, said flow channel has substantially the same slope as the body of water 7.

With reference to the alternative embodiment shown in figures 7, 8 and 9, the hydroelectric plant 10 advantageously comprises: a body of water 7; a transverse barrage 8 of the lower portion of the bed 70 of the body of water 7; a flow channel 9 with free surface.

Said flow channel 9 is advantageously: inclined downward along the direction

220 of flow of the liquid stream 22; positioned downstream of the barrage 8; obtained in the bed 70 of the body of water 7; said flow channel 9, moreover, develops starting from the barrage 8.

The rise of the free surface of the body of water 7, upstream of the transverse barrage 8, causes a difference in height that can be exploited to produce electrical energy.

At the upper portion of the barrage 7 is obtained a through opening 84, said through opening 84 being in fluid communication with the flow channel 9. Consequently, the height of the barrage 8, measured starting from the bottom of the b ed o f the b ody o f water 7 , i s lower at the through opening 84, than the remaining parts of the barrage 8. Said barrage 8 can be obtained by appropriately modifying banks already existing along many bodies of water 7. At least a first segment 91 of said flow channel 9 comprises a greater slope than the slope of the body of water 7 in that point. With reference to the direction 220 of flow of the liquid stream, upstream of the opening 84 of the barrage 8 is advantageously positioned a grid 85 that retains any debris transported by the fluid stream. This prevents them from damaging the runner positioned downstream.

At the areas of the barrage 8 distinct from the area associated with the flow channel 9, the barrage 8 advantageously comprises the height-adjustable auxiliary barrage means. The auxiliary barrage means advantageously comprise plates that are movable in the vertical direction, applied in the upper part of the barrage 8. Said auxiliary barrage means enable to regulate the apportionment between the flow rate of water conveyed by the flow channel 9 and the flow rate of water that seeps through the remaining parts of the barrage 8. Both in the exemplifying embodiments shown in figures 5 and 6, and in figures 7, 8, 9, the runner 2 of the turbine 1, at least in one operating condition is operatively associated with the liquid stream 22 transiting in said flow channel

9.

Said operating condition corresponds to the operating condition shown in figure

8 and better described below.

The t urbine 1 c omprises flotation m eans 40 ofthe type d escribed p reviously.

Said flotation means 40 are advantageously positioned within the bed 70 of the body of water 7, but externally to the flow channel 9.

Figures 8 and 9 illustrate the same embodiment in two different operating conditions. The operating condition shown in figure 9 corresponds to a condition of full flood, i.e. with high water flow rates, whilst the configuration shown in figure 8 shows a condition with smaller flow rates. In the operating condition shown in figure 8, the liquid stream flows through the through opening 84 obtained in the barrage 8. If the level of the body of water is sufficiently high, part of the flow rate falls over at the parts of the barrage 8 distinct from the opening 84. The flow rate of water conveyed by the flow channel 9 may be exploited for the production of electrical energy by means of the turbine 1 positioned downstream of the barrage 8 along the flow channel 9: the runner 2 of said turbine 1 is positioned within the flow channel 9. The remaining flow rate of water, which falls over along the parts of the opening 8 distinct from the opening 84, instead is not used for the production of electrical energy. hi this operating condition, the base 4 of the turbine 1 advantageously bears directly on the edge 92 of the flow channel 9 as shown, for example, in figure

11. hi the operating condition shown in figure 9, the flow rate of water that seeps from the barrage 8 is such as to raise the flotation means 40 that are positioned externally to the flow channel 9, but internally to the bed 70 of the body of water 7. In particular, in the operating condition of figure 9, the runner 2 of the turbine 1 is no longer internally to the flow channel 9 and the height difference produced by the barrage 8 can no longer be exploited. The presence of the flotation means 40 enables the turbine 1 not to be submerged by the water stream in the full flood condition and prevents the damaging of the turbine 1.

The hydroelectric plant 10 further comprises means for positioning the turbine 1 relative to the flow channel 9. Said positioning means are important to prevent the liquid stream 22 from dragging the turbine 1, misaligning it with respect to the underlying flow channel 9. The problem of the misalignment of the turbine 1 relative to the flow channel 9 is particularly felt in the operating condition of full flood, shown in figure 9. As the water level decreases, the turbine 1 must be perfectly aligned with the flow channel 9 to enable the runner 2 to be positioned within the flow channel 9.

The turbine 1 is preferably connected to two anchoring points, fixed in space, by means of two ropes that develop substantially parallel and positioned adjacent to each other. The aforementioned positioning means advantageously comprise two crossed rigid bars, joined together. The bars connect the two ropes. Each bar develops between a point positioned in proximity to one of the fixed anchoring points of the turbine 1 and a point positioned in proximity to the turbine 1. Advantageously, on the bottom the positioning means comprise "V" shaped grooves that receive and guide the complementarily shaped flotation means 40; in this way, the correct positioning of the turbine relative to the flow channel is facilitated. Advantageously, the positioning means comprise fixed guides that develop upwards starting from the flow channel 9 and that guide the turbine 1 when it moves upwards or downwards according to the flood level. Advantageously the hydroelectric plant 10 comprises multiple turbines 1. hi an exemplifying and non limiting solution, each turbine 1 is connected to an asynchronous electric generator, downstream of which is present an inverter that transforms the alternating current produced at variable frequency by the runner 2 into direct current. The direct current thus obtained, before being sent into the grid, is then re-transformed by a subsequent common inverter into alternating current. Advantageously, the inverters, which are more delicate and costly apparatuses, are positioned in a sheltered location, whilst the asynchronous generator can also be positioned on the turbine 1 and hence is more exposed to the action of any external agents.

The present invention also relates to a hydroelectric apparatus 10 comprises a flow channel 9 with free surface defining a direction of flow of a liquid stream 22. Said channel 9 comprises surfaces 102 for the containment of the liquid stream. Said containment surfaces 102 define the bed of the channel 9. The hydroelectric apparatus 10 further comprises at least two turbines positioned along the channel 9, having one or more of the technical characteristics of the turbines according to the present invention. The containment surfaces 102 comprise two lateral surfaces 1020 of the channel 9 and a bottom surface 1021 of the channel 9. The two lateral surfaces 1020 are substantially vertical. The bottom surface 1021 inferiorly connects the two vertical lateral surfaces 1020. Having defined a first horizontal direction orthogonal to the direction of flow of the liquid stream 22 in the channel 9, the size of the blades 21 along the first direction is greater than or equal to 0.7 times the distance between the two lateral surfaces 1020 of the channel 9, said distance between the two lateral surfaces 1020 of the channel 9 being measured along the first direction. In this way, the blades 21 can transit internally to the channel 9 maintaining a reduced play with the lateral surfaces 1020. Advantageously during normal operation, the play between the blade 21 and the bottom surface 1021 of the channel 9 is less than one quarter the length of the maximum rectilinear segment joining two points of the blade 21. Advantageously the bases 4 of the turbines 1 are integral to the channel 9 and are fixed in space.

In general, the axis of rotation 20 of the runner 2 is transverse, and in particular orthogonal, to the direction of flow of the liquid stream 22. Advantageously two immediately consecutive runners 2 are positioned along the channel 9 at a predetermined distance from each other defining a portion 103 of the flow channel interposed between two runners 2, a first of said two runners 2 being positioned upstream of the other relative to the direction of flow of the liquid stream 22. Advantageously said two runners 2 belong to distinct turbines 1. The aforementioned predetermined distance is advantageously such as to allow the maximum exploitation of the energy made available by the liquid stream 22 along the channel 9. Said interposed portion 103 has substantially constant slope, substantially constant passage section and substantially constant friction; let maximum limit velocity be defined as the maximum velocity reached spontaneously by the liquid current 21 in the absence of obstacles in a generic flow channel having substantially constant slope, substantially constant passage section and substantially constant friction. Said maximum limit velocity, once reached, tends to remain constant in the absence of additional perturbations. If along the channel 9, however, is positioned a runner 2, said runner intercepts with its blades 21 the liquid stream 22 braking its motion. The predetermined distance between said two immediately consecutive runners is equal to the distance necessary for the liquid stream 22, perturbed by the presence of the first runner 2 upstream, to reach said maximum limit velocity along the interposed portion 103. Preferably, the predetermined distance between said two immediately consecutive runners 2 is equal to the distance necessary and sufficient for the liquid stream 22, perturbed by the presence of the first runner 2 upstream, to reach said maximum limit velocity along the interposed portion 103. Advantageously the interposed portion 103 is substantially rectilinear.

The number of the runners 2 positioned in succession along a predetermined interval of the flow channel 9 is equal to the ratio, rounded to the nearest natural number, between the maximum hydraulic power available in said predetermined interval and the mechanical power obtained with a runner 2, hypothesising that the runner 2 is impacted by a liquid stream 22 whose velocity is equal to the maximum limit velocity. Good results are also obtained using a number of runners that differs by less than 10% from the value calculated previously. Advantageously the runners 2 are mutually e quidistant from each other along the predetermined interval.

Said maximum limit velocity in the predetermined interval of the channel 9 is a function of friction, of the geometry and of the slope of the predetermined interval of the flow channel 9. In particular, said limit velocity is estimated as the product of a coefficient of friction (see table 14 of the Manuale deU'Ingegnere [Engineer's Manual] - Nuovo Colombo - 84^th edition - Hoepli editore - page H-32) and of the square root of the product of the slope of the interval of the channel 9 and of an average radius of the passage section of the liquid stream 22 in the channel 9 (Bazin's formula). In particular, the slope is equal to the ratio between the difference in height between two end points of the predetermined i nterval o f t he flow c hannel 9 a nd t he 1 ength o f t he h orizontal projection of the trajectory between said two points; the average radius is instead defined as the ratio between the wet perimeter and the area of the passage section. The wet perimeter is defined by the length of the interface between the liquid stream 22 and the flow channel 9 measured at the passage section.

The maximum hydraulic power made available by the liquid stream 22 along the predetermined interval of the flow channel 9 is equal to the product of the following factors: mass flow rate, gravity acceleration, difference between the value assumed by Bernoulli's trinomial in the initial point and in the final point of the predetermined interval of the flow channel 9. Bernoulli's trinomial is defined as the sum of the geodetic height, of the piezometric height and of the kinetic height of the liquid stream 22.

The mechanical power obtained with a runner 2 is equal to the product of the hydraulic power available in a passage section and the efficiency of the runner 2.

The hydraulic power available in a passage section is equal to half of the product of the density of the liquid, of the surface of the passage section and of the cube of the velocity of the liquid stream 22 in that specific passage section. The presence along the interval of the channel 9 of a higher number of runners 2 than the one determined according to the preceding expressions would determine a higher number of bleeds of power of the liquid stream 22. However, the attainment of the maximum limit velocity would be prevented and consequently the maximum value of the hydraulic power available in a passage section would decrease. Using a lower number of runners 2, one would not exploit a segment of the interval of the flow channel 9 along which the velocity of the liquid stream 22 no longer increases, having reached the aforementioned maximum limit velocity.

Advantageously said predetermined interval of the channel 9 coincides with the entire length of the flow channel 9.

As shown in the particular solution of figure 12, the flow channel 9, or otherwise the predetermined interval considered, is substantially rectilinear, with constant flow section (not considering the presence of the runners 2), with constant slope and friction.

The invention achieves important advantages.

First of all, it enables to facilitate maintenance operations.

An additional, important advantage is that it enables to regulate the velocity of rotation of the runner.

The invention thus conceived can be subject to numerous modifications and variants, without thereby departing from the scope of the inventive concept that characterises it.

Moreover, all details can be replaced by other technically equivalent elements.

In practice, all materials used, as well as the dimensions, can be any, according to requirements.

Claims

1. A turbine comprising a runner (2) rotating relative to its own axis of rotation (20), said runner (2) in turn comprising at least one blade (21), said blade (21) being able to be at least partially immersed in a liquid stream with free surface (22), said runner (2) being operatively comiectable to an electric generator; said turbine (1) being characterised in that it comprises:

-a base (4) suitable to interact directly with the outside environment to support the weight of the turbine (1);

-means (3) for raising and lowering the axis of rotation (20) of the runner (2) relative to at least one part of the base.

2. Turbine as claimed in claim 1, characterised in that the lifting and lowering means (3) actuate the axis of rotation (20) between a first configuration, in which said axis of rotation (20) is placed at a first predetermined height, and a second configuration in which said axis of rotation (20) is placed at a second predetermined height, said second predetermined height being greater than said first predetermined height.

3. Turbine as claimed in claim 2, characterised in that the lifting and lowering means (3) position the axis of rotation (20) in at least one intermediate configuration between the first and the second configuration.

4. Turbine as claimed in claim 3, characterised in that it comprises:

- a sensor for measuring the velocity of rotation of the runner (2);

- means for commanding the lifting and lowering means (3) operatively connected to the sensor for measuring the velocity of rotation of the runner (2) to maintain constant the velocity of rotation of the runner (2).

5. Turbine as claimed in any of the previous claims (3), characterised in that the lifting and lowering means determine a translation of the axis of rotation (20).

6. Turbine as claimed in any of the previous claims, characterised in that the lifting and lowering means (3) connect each of the two axial ends (23, 24) of the runner (2) with a corresponding area (230, 240) of the base (4).

7. Turbine as claimed in any of the previous claims, characterised in that it comprises means (5) for supporting the axis of rotation (20) of the runner (2), said supporting means (5) comprising a first portion (51) integral with the axis of rotation (20) of the runner (2) and a second portion (52) integral with said base (4).

8. Turbine as claimed in claim 7 when it depends on claim 2, characterised in that in said first configuration the second portion (52) abuts the first portion (51).

9. Turbine as claimed in claim 7 or 8, characterised in that the lifting and lowering means (3) comprise a mechanism of the articulated quadrilateral type (6).

10. Turbine as claimed in claim 7 or 8 or 9, characterised in that the lifting and lowering means (3) comprise a mechanism of the articulated parallelogram type (60), said first and said second portion (51, 52) respectively comprise connecting rod (61) and frame (62) of the articulated parallelogram (60).

11. Turbine as claimed in any of the claims 7 through 10, characterised in that the 1 ifting a nd 1 owering m eans (3) are o peratively connected b oth t o t he first portion (51) and to the second portion (52).

12. Turbine as claimed in any of the claims 7 through 11, characterised in that the second portion (52) comprises a protrusion (520) with vertical development; the lifting and lowering means (3) developing between a first point (511) of the first portion (51) of the supporting means (5) and a second point (512) of the protrusion (520) with vertical development, said second point (512) being positioned at a greater height than said first point (511).

13. Turbine as claimed in claim 12, characterised in that said lifting and lowering means (3) comprise fastening means (30) operating in traction comprising a first end connected to said first point (511) and a second end connected to a coiler (31) positioned in said second point (512).

14. Turbine as claimed in any of the claims 1 through 12, characterised in that said lifting and lowering means comprise a pneumatic actuator.

15. Turbine as claimed in any of the previous claims, characterised in that the base (4) comprises bearing means (64) suitable to be abutted by a solid support.

16. Turbine as claimed in any of the previous claims, characterised in that said base (4) is stably fixed in space.

17. Turbine as claimed in any of the claims 1 through 15, characterised in that it comprises floating means (40), said floating means (40) being able to be fastened to a fixed point in space.

18. Turbine as claimed in claim 17, characterised in that the floating means (40) are shaped as hulls (41).

19. Turbine as claimed in any of the previous claims, characterised in that it comprises an appendage (42) which can be upset and raised to minimise the size of the turbine (1).

20. Hydroelectric plant, characterised in that it comprises at least one turbine (1) as claimed in any of the claims 1 through 19.

21. Hydroelectric plant as claimed in claim 20, characterised in that it comprises a turbine (1) as claimed in claims 1 and 2, in the first configuration the runner (2) being at least partially immersed in the liquid stream (22), in the second configuration, the runner being completely external to the liquid stream (22).

22. A hydroelectric plant as claimed in claim 20 or 21, characterised in that it comprises: a body of water (7); a flow channel with free surface positioned internally to the bed (70) of the body of water (7) and on the bottom of the bed (70) of the body of water (7), said flow channel (9) having substantially the maximum slope of the body of water (7).

23. A hydroelectric plant as claimed in claim 20 or 21, characterised in that it comprises: a body of water (7); a transverse barrage (8) of the lower portion of the bed (70) of the body of water (7); a flow channel (9) with free surface: inclined downward along the direction

(220) of flow of the liquid stream (22); positioned downstream of the barrage (8); obtained in the bed (70) of the body of water (7); developing starting from the barrage (8).

24. Hydroelectric plant as claimed in claim 23, characterised in that at the upper portion of the barrage (8) is obtained a through opening (84), said through opening (84) being in fluid communication with the flow channel (9).

25. Hydroelectric plant as claimed in claim 23 or 24, characterised in that at least a first segment (91) of said flow channel (9) comprises a greater slope than the slope of the body of water (7) in that point.

26. Hydroelectric plant as claimed in any of the claims 23 through 25, characterised in that at the areas of the barrage (8) distinct from the area associated with the flow channel (9), the barrage (8) comprises auxiliary barrage means of adjustable height.

27. Hydroelectric plant as claimed in any of the claims 22 through 26, characterised in that the runner (2) of the turbine (1), at least in one operating condition, is operatively associated with the liquid stream (22) transiting in said flow channel (9).

28. Hydroelectric plant as claimed in any of the claims 22 through 27, characterised in that it comprises a turbine (1) as claimed in claim 17 or 18, said floating means (40) being positioned internally to the bed (70) of the body of water (7), but externally to the flow channel (9).

29. Hydroelectric p lant a s c laimed i n c laims 27 o r 28, c haracterised i n t hat i t comprises means for positioning the turbine 1 relative to the flow channel 9.

30. Hydroelectric apparatus, characterised in that it comprises:

-a flow channel (9) defining a direction of flow of a liquid stream (22) said channel (9) having free surface and comprising surfaces (102) for containing the liquid current (22);

-at least two turbines positioned along the channel (9), said turbines being according to any of the claims 1 through 19.

31. Hydroelectric apparatus as claimed in claim 30, characterised in that the containment surfaces (102) comprise two lateral surfaces (1020) of the channel (9) and a bottom surface (1021) of the channel (9); having defined a first horizontal direction orthogonal to the direction of flow of the liquid stream (22) in the channel (9), the size of the blades (21) along the first direction is greater than or equal to 0.7 times the distance between the two lateral surfaces (1020) of the channel (9), said distance between the two lateral surfaces (1020) of the channel (9) being measured along the first direction.

32. Hydroelectric apparatus as claimed in claim 30 or 31 characterised in that two immediately consecutive runners (2) are positioned along the channel (9) at a predetermined distance from each other defining a portion (103) of the flow channel (9) interposed between the two runners (2), a first of said two runners (2) being positioned upstream of the other runner (2) relative to the direction of flow of the liquid stream (22); said interposed portion (103) having substantially constant slope, substantially constant passage section and substantially constant friction; let a maximum limit velocity be defined as the maximum velocity reached spontaneously by the liquid stream (21) in the absence of obstacles in a generic flow channel having substantially constant slope, substantially constant passage section and substantially c onstant friction; the predetermined distance between said two immediately consecutive runners (2) being equal to the distance necessary for the liquid stream (22), perturbed by the presence of the first upstream runner (2), to reach said maximum limit velocity along the interposed portion (103), preferably the predetermined distance between two immediately consecutive runners (2) being equal to the necessary and sufficient distance for the liquid stream (22), perturbed by the presence of the first upstream runner (2), to reach said maximum limit velocity along the interposed portion (103).

33. Hydroelectric apparatus as claimed in claim 32, characterised in that the number of the runners (2) positioned in succession along a predetermined interval of the flow channel 2 is equal to the ratio, rounded to the nearest natural number, between the maximum hydraulic power available in said predetermined interval and the mechanical power obtained with a runner (2), hypothesising that it is impacted by a liquid stream (22) whose velocity is equal to the maximum limit velocity.