Pelton hydraulic turbine and installation

A method for producing electrical energy from potential energy contained water supplied from at least one supply reservoir selected from the group consisting of supply tanks for storing water with a maximum hydraulic pressure of between 7×105 Pa and 250×105 Pa and supply basins with a maximum waterfall height of between 70 m and 500 m,

• whereby said method uses a turbine unit comprising at least one hydraulic turbine of the Pelton type (1) adapted to drive an alternator (2) with a determined net rated power of 5 to 1000 KW by at least one water jet (J) issuing from a water injector along a central axis of the water jet (Ajet), said at least one water jet (J) having a maximum size defined by a jet diameter (djet) and a variable effective hydraulic pressure (Peff) lower than a maximum effective hydraulic pressure (PMax) equivalent to a determined waterfall height (HMax) comprised between 70 and 500 m, in which the said at least one hydraulic turbine of the Pelton type (1) comprises at least:
• a body (10) of the at least one turbine of the Pelton type (1), said body (10) bearing a rotating shaft defining an axis of rotation (4);
• a wheel (3) with a periphery (30) of diameter (D) comprised between 300 mm and 2000 mm, said wheel (3) being mounted on the said rotating shaft whereby the wheel is rotating relative to the turbine body (10) about the said axis of rotation (4);
• a series of buckets (5) mounted in a regular manner along the periphery (30) of the wheel (3), each bucket (5) having the shape of two half-shells (50, 51) symmetrical with respect to a plane of symmetry (6), said half-shells (50, 51) defining a peripheral edge (5A, 5P) extending substantially in a plane (P5P), said half-shells (50, 51) being bound to each other along a central rib (52) located in the plane of symmetry (6), each bucket (5) having a free end wall (53) remote from the periphery (30) of the wheel (3), said free end wall (53) being provided with a notch (54) whose size is greater than the maximum size of the water jet (J) of the injector (11), each half-shell (50,51) having a bottom (50A, 51A), while the notch (54) of a bucket (5) defines an opening (54) to each half-shell (50, 51) of the bucket (5) in consideration;
• at least one water injector (11) adapted to direct at least the water jet (J) successively towards at least one bucket of the series of buckets (5) of the wheel (3) for driving the wheel into rotation around the said axis of rotation (4), said at least one water injector (11) defining a passage outlet (11P) characterized by an outlet diameter (ds) corresponding substantially to the jet diameter (djet) of the water jet (J) leaving the injector (11), in which the said at least one water injector is arranged with respect to the buckets of the wheel (3) so that the central axis of the water jet (J) issuing from the said at least one injector (11) towards successively at least one bucket of the series of buckets (5) is tangent to a turbine circle (CT) having a centre located on the axis of rotation (4) of the wheel (3) and having a turbine diameter (DT) greater than the diameter (D) of the periphery (30) of the wheel (3),
• in which the said at least one water injector (11) is a variable flow rate injector with a variable passage outlet (11P) defining a variable outlet diameter (ds) able to vary at least between at least a first outlet diameter (ds1) to ensure a first flow rate of water leaving the variable flow rate injector (11) adapted for a first hydraulic pressure (P1) corresponding to the maximum hydraulic pressure (PMax), and a second outlet diameter (ds2) at least 20% greater than said first outlet diameter (ds1) adapted for a second hydraulic pressure (P2) at least 30% lower than the maximum hydraulic pressure (PMax),
• in which a number of buckets (5) is from 19 to 33,
• in which the half-shells (50, 51) of each bucket (5) each define a cavity (50C, 51C) characterized by
• (a) a maximum width (Lmax) measured perpendicular to the plane of symmetry (6) comprised between 1.3 and 1.9 times said second outlet diameter (ds2) of the injector (11),
• (b) a maximum length (Imax) measured parallel to the plane of symmetry (6) comprised between 2.2 and 3 times said second outlet diameter (ds2) of the injector (11), and
• (c) at least one deepest point (C50, C51) located at a maximum depth (Pmax) from the plane (P5P) of the peripheral edge (5A, 5P) comprised between 0.8 and 1.2 times said second outlet diameter (ds2) of the injector (11), said maximum depth (Pmax) being measured along a line parallel to the plane of symmetry (6) and perpendicular to the plane (P5P) of the peripheral edge (5A, 5P),
• in which the notch (54) of each bucket (5) has two lateral edges (54A, 54B) with remote end parts separated from each other by a distance (d54) comprised between 1 and 1.2 times said second outlet diameter (ds2) of the injector (11),
• in which each bucket (5) has an outer face (5SE) opposite to the cavities (50C, 51C), said outer face (5SE) having a longitudinal channel (15) located under the central rib (52), said longitudinal channel (15) having a bottom with at least a part (15p) located between a first longitudinal plane (P1) perpendicular to the plane of symmetry (6) and extending through the deepest points (C50,C51) of the cavities (50C, 51C), and a second longitudinal plane (P2) perpendicular to the plane of symmetry (6) and intersecting the central rib (52),
• in which the said turbine unit further comprises:
• at least one supply reservoir selected from the group consisting of supply tanks for storing water with a maximum hydraulic pressure of between 7×105 Pa and 250×105 Pa and supply basin with a maximum waterfall height of between 70m and 500m,
• at least one alternator with at least one driving shaft for driving into rotation a rotatable part of the alternator,
• at least one kinematic device connecting the rotating shaft of the variable flow rate turbine to the driving shaft of the alternator, and
• at least one pipe for bringing water from the said at least one supply reservoir to the said at least one water injector, in which said method comprises at least the following steps:
• supplying water from the at least one supply reservoir to the said at least one water injector via the at least one pipe;
• directing at least the water jet (J) from the at least one water injector (11) successively towards at least one bucket of the series of buckets of the wheel (3), so as to drive the wheel into rotation around the axis of rotation (4), while driving into rotation the rotatable part of the alternator via the at least one kinematic device;
• and
• producing electrical energy by rotating the rotatable part of the alternator.

A bucket wheel assembly suitable for a turbine unit comprising a hydraulic turbine of the Pelton type (1) adapted to drive an alternator (2) with a determined net rated power of 5 to 1000 KW by at least one water jet (J) issuing from a water injector along a central axis of the water jet (Ajet), said at least one water jet (J) having a maximum size defined by a jet diameter (djet) and a variable effective hydraulic pressure (Peff) lower than a maximum effective hydraulic pressure (PMax) equivalent to a determined waterfall height (HMax) comprised between 70 and 500 m, in which the said hydraulic turbine (1) comprises at least:

• a body (10) of the turbine (1), said body (10) bearing a rotating shaft defining an axis of rotation (4);
• a wheel (3) with a periphery (30) of diameter (D) comprised between 300 mm and 2000 mm, said wheel (3) being mounted on the said rotating shaft whereby the wheel is rotating relative to the turbine body (10) about the said axis of rotation (4);
• a series of buckets (5) mounted in a regular manner along the periphery (30) of the wheel (3), each bucket (5) having the shape of two half-shells (50,51) symmetrical with respect to a plane of symmetry (6), said half-shells (50,51) defining a peripheral edge (5A, 5P) extending substantially in a plane (P5P), said half-shells (50,51) being bound to each other along a central rib (52) located in the plane of symmetry (6), each bucket (5) having a free end wall (53) remote from the periphery (30) of the wheel (3), said free end wall (53) being provided with a notch (54) whose size is greater than the maximum size of the water jet (J) of the injector (11), each half-shell (50, 51) having a bottom (50A, 51A), while the notch (54) of a bucket (5) defines an opening (54) to each half-shell (50,51) of the bucket (5) in consideration;
• at least one water injector (11) adapted to direct at least the water jet (J) successively towards at least one bucket of the series of buckets (5) of the wheel (3) for driving the wheel into rotation around the said axis of rotation (4), said at least one water injector (11) defining a passage outlet (11P) characterized by an outlet diameter (ds) corresponding substantially to the jet diameter (djet) of the water jet (J) leaving the injector (11), in which the said at least one water injector is arranged with respect to the buckets of the wheel (3) so that the central axis of the water jet (J) issuing from the said at least one injector (11) towards successively at least one bucket of the series of buckets (5) is tangent to a turbine circle (CT) having a centre located on the axis of rotation (4) of the wheel (3) and having a turbine diameter (DT) greater than the diameter (D) of the periphery (30) of the wheel (3),
• in which the said at least one water injector (11) is a variable flow rate injector with a variable passage outlet (11P) defining a variable outlet diameter (ds) able to vary at least between at least a first outlet diameter (ds1) to ensure a first flow rate of water leaving the variable flow rate injector (11) adapted for a first hydraulic pressure (P1) corresponding to the maximum hydraulic pressure (PMax), and a second outlet diameter (ds2) at least 20% greater than said first outlet diameter (ds1) adapted for a second hydraulic pressure (P2) at least 30% lower than the maximum hydraulic pressure (PMax),
• in which a number of buckets is comprised between 19 and 33,
• in which the half-shells (50, 51) of each bucket (5) each define a cavity (50C, 51C) characterized by
• (a) a maximum width (Lmax) measured perpendicular to the plane of symmetry (6) comprised between 1.3 and 1.9 times said second outlet diameter (ds2) of the variable flow rate injector (11),
• (b) a maximum length (lmax) measured parallel to the plane of symmetry (6) comprised between 2.2 and 3 times said second outlet diameter (ds2) of the variable flow rate injector (11), and
• (c) at least one deepest point (C50, C51) located at a maximum depth (Pmax) from the plane (P5P) of the peripheral edge (5A, 5P) comprised between 0.8 and 1.2 times said second outlet diameter (ds2) of the injector (11), said maximum depth (Pmax) being measured along a line parallel to the plane of symmetry (6) and perpendicular to the plane (P5P) of the peripheral edge (5A, 5P), in which the notch (54) of each bucket (5) has two lateral edges (54A, 54B) with remote end parts separated from each other by a distance (d54) comprised between 1 and 1.2 times said second outlet diameter (ds2) of the variable flow rate injector (11), and
• in which each bucket (5) has an outer face (5SE) opposite to the cavities (50C, 51C), said outer face (5SE) having a longitudinal channel (15) located under the central rib (52), said longitudinal channel (15) having a bottom with at least a part (15p) located between a first longitudinal plane (P1) perpendicular to the plane of symmetry (6) and extending through the deepest points (C50,C51) of the cavities (50C, 51C), and a second longitudinal plane (P2) perpendicular to the plane of symmetry (6) and intersecting the central rib (52),
• whereby the bucket wheel assembly comprises a wheel (3) having a periphery (30) of diameter (D) comprised between 300 mm and 2000 mm, said wheel (3) being mounted or able to be mounted on a central shaft defining the axis of rotation (4).