Pelton turbine with at least four nozzles and a supply system, and method for modernising an existing hydroelectric power plant

Abstract

The invention relates to a Pelton turbine comprising an impeller with a horizontal axis of rotation and a supply system with at least four nozzles which surround the impeller in a uniformly distributed manner in the circumferential direction, and wherein the supply system comprises a first arm (1) and a second arm (2), and wherein the first arm (1) is connected to at least two mutually adjacent nozzles, and wherein the second arm (2) is connected to the remaining nozzles, and wherein each arm (1, 2) comprises a strand which partially wraps around the impeller and from which in each case at least one first pipe branches off to a first nozzle and wherein a further nozzle forms the end of the strand, and wherein each arm (1, 2) comprises a manifold (1.1, 2.1) and a tubular connecting piece (1.2, 2.2), and wherein the axes of the tubular connecting pieces (1.2, 2.2) are oriented parallel to the axis of rotation of the impeller, and wherein each tubular connecting piece (1.2, 2.2) is connected to the associated strand via the associated manifold (1.1, 2.1).

Description

[0001] Pelton turbine with at least four nozzles and a feed system and method for modernizing an existing hydroelectric power plant

[0002] The invention relates to a Pelton turbine with at least four nozzles and with a supply system for the drive water and a method for modernizing an existing hydroelectric power plant with Pelton turbines.

[0003] Pelton turbines with four, five, or six nozzles according to the invention are particularly advantageous. Pelton turbines according to the invention with an even number of nozzles are used in the modernization process according to the invention.

[0004] The invention is described using the particularly advantageous 6-nozzle embodiment as an example. Transferring the concept according to the invention to embodiments with a different number of nozzles is easily feasible for a person skilled in the art.

[0005] Six-nozzle Pelton turbines with a feed system are known from the prior art. For example, US Patent 2,965,764 A discloses a six-nozzle Pelton turbine with a feed system that extends almost 360° around the turbine runner. Although this design requires considerable space, it is commonly used in six-nozzle Pelton turbines with a vertical axis of rotation. A six-nozzle Pelton turbine with a horizontal axis of rotation is disclosed in EP 2,035,689 B1. The cost-effective feed system consists of a central distribution pipe from which six feed lines branch off. The central distribution pipe runs axially along the turbine, and the feed lines branch off from the central distribution pipe at oblique-axial intervals, evenly spaced around the circumference.

[0006] When modernizing existing hydroelectric power plants that include Pelton turbines, a common challenge is to combine several of the existing turbines into larger or more powerful units in order to reduce maintenance. This requires pooling the flow rates by combining the individual inlets of the existing turbines.

[0007] The object of the invention is to provide a Pelton turbine with at least four nozzles, a horizontal axis of rotation, and an alternative feed system, which has a compact design. Furthermore, the turbine according to the invention is very well suited for modernizing existing hydroelectric power plants that include Pelton turbines, since the inventive feed system design enables an efficient and cost-effective merging of the existing feeds.

[0008] The problem is solved according to the invention by an embodiment according to the independent claims. Further advantageous embodiments of the present invention are found in the dependent claims.

[0009] The invention will be explained below with the aid of figures. The figures show, in detail:

[0010] Fig. 1: Pelton turbine according to the invention in side view

[0011] Fig. 2: Pelton turbine according to the invention in top view

[0012] Fig. 3: Hydroelectric power plant before modernization

[0013] Fig. 4: Hydroelectric power plant after modernization

[0014] Fig. 5: Hydroelectric power plant after modernization

[0015] Fig. 6: Hydroelectric power plant before modernization. Fig. 7: Hydroelectric power plant after modernization.

[0016] Figure 1 shows a side view of a 6-nozzle Pelton turbine according to the invention. The turbine comprises an impeller with a horizontal axis of rotation and a feed system with six nozzles that surround the impeller uniformly in the circumferential direction. The impeller comprises a plurality of buckets which are supplied with drive water through the nozzles during operation. The feed system comprises two arms, the first arm being designated 1 and the second arm 2. The first arm is connected to three adjacent nozzles, and the second arm is connected to the remaining nozzles. Each arm comprises a strand that partially encircles the impeller, from which two successive pipes branch off to nozzles, with a third nozzle forming the end of the strand.

[0017] In a 4-nozzle embodiment, each branch would comprise two nozzles. In a 5-nozzle embodiment, one branch would comprise two nozzles and the other branch would comprise three nozzles. In embodiments with an odd number of nozzles, the arms differ at least in that the number of nozzles in the two arms differs by one; that is, in each case, the nozzles are distributed as evenly as possible between the two arms.

[0018] Figure 2 shows a top view of the Pelton turbine according to the invention. The impeller is arranged in a turbine housing, which is designated 3. For clarity, the turbine housing is not shown in Figure 1. The impeller is also connected to a generator, which is designated 4. The dashed line segments running centrally at the top and bottom indicate the collinear axes of rotation of the impeller and the generator. Each arm comprises a bend, which is designated 1.1 or 2.1, and a connecting pipe section, which is designated 1.2 or 2.2. The axes of the connecting pipe sections 1.2 and 2.2 are indicated by dashed lines. The axes of the connecting pipe sections 1.2 and 2.2 are aligned parallel to the axis of rotation of the impeller. The connecting pipe sections 1.2 and 2.2 are connected to the associated strands via the bends 1.1 and 2.1. The manifolds 1.1 and 2.1 therefore cause a 90° deflection of the flow direction in the respective arm (from an axis-parallel direction to a direction tangential to the axis).

[0019] In the embodiment shown in Figures 1 and 2, the connecting pipe sections 1.2 and 2.2 are located on the same side of the impeller. This has the advantage of a compact turbine design. However, the connecting pipe sections 1.2 and 2.2 can also be distributed on both sides of the impeller; for example, connecting pipe section 1.2 in Figure 2 could also be arranged above the impeller, with its opening facing upwards. This can be advantageous when the turbine according to the invention is used to modernize a hydroelectric power plant where the feed lines to two adjacent existing turbines approach them from opposite directions. In this case, the two sides of the impeller are separated by a plane defined by the center lines of the impeller buckets.

[0020] In the embodiment shown in Figure 2, the generator 4 is arranged on the side of the impeller where the connecting pipe sections 1, 2 and 2, 2 are also located. This also results in a very compact design. The generator 4 could also be arranged on the other side. This can be advantageous if the turbine according to the invention is part of a tandem unit, i.e., if two turbines according to the invention are connected to one generator. The generator 4 is then arranged between the two turbines, and the four connecting pipe sections run outwards from the generator.

[0021] In the embodiment shown in Figures 1 and 2, the two arms 1 and 2 are identically constructed, which is advantageous for the cost-effective manufacturing of the turbine. The identical construction results in the axis of rotation being located centrally between the axes of the connecting pipe sections 1.2 and 2.2 (all these axes then also lie in the same plane). This is also advantageous when the turbine according to the invention is used for the modernization of an existing power plant. The two arms can only be identically constructed in embodiments with an even number of nozzles.

[0022] The modernization method according to the invention for an existing hydroelectric power plant is described below with reference to Figures 3 and 4. The configuration of the existing hydroelectric power plant and the Pelton turbines according to the invention used for the modernization shown in these figures was chosen because it offers a particularly large number of advantages. Based on the description for this configuration, a person skilled in the art can easily transfer the modernization method according to the invention to other configurations. Figure 3 shows a top view of an existing hydroelectric power plant before the modernization. The hydroelectric power plant comprises a total of four Pelton turbines, with each pair of Pelton turbines forming a tandem unit together with a generator. One of the two generators is designated 7. The associated Pelton turbines are designated 6.1 and 6.2.The existing Pelton turbines are two-nozzle designs with a horizontal axis of rotation. The turbines are supplied with drive water via a common penstock, shown in the lower part of the figure. An inlet pipe branches off from the penstock for each Pelton turbine. A shut-off valve is installed in each inlet pipe. One of the shut-off valves is labeled 5. The dashed horizontal line runs along the end of the inlet pipes and indicates the interface between the reused parts and those being replaced during the modernization. The parts located below the dashed line in Figure 3 are reused.

[0023] Figure 4 shows the hydroelectric power plant from Figure 3 after the modernization. Two existing Pelton turbines belonging to a tandem unit were replaced by a new Pelton turbine according to the invention. The connecting pipe sections of the new Pelton turbines according to the invention were connected to the corresponding inlet pipes. Since the inlet pipes belonging to two adjacent existing Pelton turbines run parallel to each other, the connection to the connecting pipe sections could be made without any special adaptation. The lateral distance between the connecting pipe sections of a Pelton turbine according to the invention can be varied by adjusting the pipe segments of arms 1 and 2, which are arranged between the first nozzle branch and the bends. However, there are certain limits to the small values ​​of this distance.

[0024] Since all shut-off valves are retained during the modernization, the pressure pipeline does not need to be drained. Instead, the other tandem unit can continue operating while one is being dismantled. This minimizes downtime during the modernization. In the described example, two 2-nozzle Pelton turbines are replaced by one 6-nozzle Pelton turbine. Although the given flow rate is now handled by only one impeller, the increased number of nozzles allows for a higher power density and improved part-load performance because ventilation losses are reduced. Furthermore, since machines with a higher number of nozzles operate at higher speeds, a more compact design is achieved.Another advantage is that the existing underwater channels can be connected to form a channel using the existing generator pit, through which the drainage of the new turbine according to the invention can take place.

[0025] During the modernization, Pelton turbines according to the invention with an even number of nozzles are used.

[0026] The application of the modernization method according to the invention is not limited to hydroelectric power plants with tandem units. Equally, two separate Pelton turbines, each with its own associated generator, can be replaced by one Pelton turbine with a generator according to the invention.

[0027] Further configurations for a modernization according to the invention are described below in brief as examples.

[0028] A particularly advantageous embodiment of the modernization method according to the invention can be carried out on an existing power plant, which consists of a mirror image of Figure 3 at the top of the figure. That is, the existing power plant comprises two rows of tandem units, which are supplied with drive water by two penstocks arranged on either side. During the modernization, two of the existing tandem units are replaced by a new tandem unit with two Pelton turbines according to the invention. Figure 5 shows the hydroelectric power plant after the modernization.

[0029] Figure 6 shows another hydroelectric power plant before modernization. The power plant comprises four separate Pelton turbines, each with a generator. The turbines are fed by two laterally arranged penstocks. Figure 7 shows the power plant from Figure 6 after modernization. The modernized power plant comprises two Pelton turbines according to the invention, in which the connecting pipe sections are arranged on opposite sides of the associated impellers.

[0030] In conclusion, it should be emphasized once again that the Pelton turbines according to the invention can not only be used in the modernization of existing hydroelectric power plants, but can also be advantageously implemented in new plants due to their compact design. That is, the embodiments shown in Figures 4, 5, and 7 could also be implemented as new plants. In new plants, embodiments with an odd number of nozzles can also be advantageously used.

[0031] Reference symbol list

[0032] 1 First arm

[0033] 1.1 Manifold

[0034] 1.2 Connecting pipe section

[0035] 2 Second arm

[0036] 2.1 Manifold

[0037] 2.2 Connecting pipe section

[0038] 3 turbine housings

[0039] 4 Generator

[0040] 5 Shut-off device

[0041] 6.1 Pelton Turbine

[0042] 6.2 Pelton Turbine

[0043] 7 Generator

Claims

Patent claims 1. A Pelton turbine comprising an impeller with a horizontal axis of rotation and a feed system with at least four nozzles uniformly distributed around the impeller in the circumferential direction, characterized in that the feed system comprises a first arm (1) and a second arm (2), wherein the first arm (1) is connected to at least two adjacent nozzles, and wherein the second arm (2) is connected to the remaining nozzles, and wherein each arm (1, 2) comprises a strand partially encircling the impeller, from which at least one first pipe branches off to a first nozzle, and wherein a further nozzle forms the end of the strand, and wherein each arm (1, 2) comprises a bend (1.1, 2.1) and a connecting pipe section (1.2, 2.2), and wherein the axes of the connecting pipe sections (1.2, 2.2) are aligned parallel to the axis of rotation of the impeller, and wherein each connecting pipe section (1.2, 2.2) extends via the associated bend (1.1 , 2.1) is connected to the corresponding strand.

2. Pelton turbine according to claim 1, wherein the Pelton turbine comprises six nozzles, and wherein the first arm (1) is connected to three adjacent nozzles, and wherein from each strand a first tube successively branches off to a first nozzle and a second tube to a second nozzle, and wherein a third nozzle forms the end of the strand.

3. Pelton turbine according to claim 1 or 2, wherein one connecting pipe section (1 .2) is arranged on a first side of the impeller, and wherein the other connecting pipe section (2.2) is arranged on the same side of the impeller.

4. Pelton turbine according to one of claims 1 to 3, wherein the number of nozzles is even and the two arms (1 , 2) are identically constructed.

5. Pelton turbine according to one of claims 3 or 4, wherein the side of the impeller is connectable to a generator (4) on which the connecting pipe sections (1.2, 2.2) are arranged.

6. Pelton turbine according to one of claims 3 or 4, wherein the side of the impeller is connectable to a generator (4) on which the connecting pipe sections (1.2, 2.2) are not arranged, and wherein the Pelton turbine is provided to form part of a tandem unit.

7. Pelton turbine according to claim 1 or 2, wherein one connecting pipe section (1 .2) is arranged on a first side of the impeller, and wherein the other connecting pipe section (2.2) is arranged on the other side of the impeller.

8. Method for modernizing an existing hydroelectric power plant with at least two Pelton turbines (6.1, 6.2), wherein the hydroelectric power plant comprises a first existing inlet pipe for a first existing Pelton turbine (6.1), and wherein the hydroelectric power plant comprises a second existing inlet pipe for a second existing Pelton turbine (6.2), and wherein the two existing Pelton turbines (6.1, 6.2) are replaced by a new Pelton turbine with an even number of nozzles according to one of the preceding claims, and wherein a first connecting pipe section (1, 2) of the new Pelton turbine is connected to the first existing inlet pipe, and wherein a second connecting pipe section (2, 2) of the new Pelton turbine is connected to the second existing inlet pipe.

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