JPH0417563Y2 - - Google Patents

Description

[Detailed Description of the Invention] A. Field of Industrial Application The present invention relates to a water turbine runner that prevents corrosion damage due to gaps between runner blades and support plates.

B. Summary of the invention The present invention provides a sacrificial anode to connect the runner blades and a support plate in the runner of a water turbine such as a cross-flow turbine used for small-scale hydroelectric power generation with an output of 1 MW or less. This prevents crevice corrosion, pitting corrosion, etc. in the gap with the support plate, and improves the reliability of the water turbine.

C. Prior Art A cross-flow water turbine is a prime mover used for small-scale hydroelectric power generation, and is used to extract electrical energy from river water, blast furnace cooling water, etc., with a head of about 20 to 100 m and an output of 1 MW or less.

FIG. 2 is a partially sectional perspective view showing the structure of a typical cross-flow water turbine, and FIG. 3 is an explanatory diagram conceptually showing the flow of water inside the water turbine. As shown in these drawings, a plurality of runner blades 1a rotated by the potential energy of water, and a support plate 1 that supports the runner blades 1a arranged in a cylindrical shape.
A runner 1 having a runner b is rotatably supported in a casing 2 by a rotating shaft 3 via a bearing 8. Between the casing 2 and the runner 1, a nozzle 2a is provided extending from the casing 2 to prevent water leakage and water splashing. On the upstream side of the runner 1, an inlet pipe 4 is connected to the casing 2, and on the inlet side of the casing 2 corresponding to the outlet side of the inlet pipe 4, a guide vane 5 that adjusts the amount of water entering the runner 1 can be opened and closed. It is set in. On the downstream side of the runner 1, another casing 6 is connected to the casing 2, and a water discharge pipe 7 hanging down from these casings 2, 6 is connected.
Note that this water discharge pipe 7 is guided into the water. Water flowing in from the inlet pipe 4 is adjusted by a guide vane 5 and enters the runner 1, and after rotating the runner 1, is discharged from its outer periphery and discharged into the water through the water discharge pipe 7. As a result, a generator (not shown) connected to one end of the rotating shaft 3 is activated, and electrical energy is generated.

Details of the runner 1 of the above-mentioned cross-flow turbine are shown in FIGS. 4a and 4b.

As shown in both figures, the runner 1 is formed by inserting a runner blade 1a into a groove formed around a support plate 1b and fixing it by welding 9. Such a runner 1 is fixed to the rotating shaft 3 by welding 10 via the support plate 1b, and is rotatably supported by the casing of the water turbine.

D Problems to be solved by the invention As mentioned above, the runner blade 1a and the support plate 1b
When welding the runner blades 1a, the welding torch cannot penetrate deep into the gap 11 due to the narrow spacing between the runner blades 1a.
was left behind.

When a cross-flow turbine equipped with such a runner 1 is used in contaminated river water, seawater, etc., crevice corrosion, pitting corrosion, etc. are likely to occur in the runner 1 due to the gaps 11. In particular, the runner blade 1a
When the runner 1 whose support plate 1b is made of stainless steel is used in seawater, significant crevice corrosion and pitting corrosion occur, causing early damage to the runner 1.
A problem with cross-flow water turbines was that they could no longer perform their functions.

Further, the runner blade 1a has a thin thickness of about 6 to 20 mm, and the structure of the runner 1 as a whole is complicated, so that it is difficult to cast the runner 1 as a single piece.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to provide a water turbine runner that prevents crevice corrosion and pitting corrosion in the gap between the runner blade and the support plate.

E. Means for Solving the Problems The present invention for achieving the above object is based on the following knowledge. In other words, in conventional water turbine runners, the gap between the runner blade and the support plate is as narrow as approximately 0.5 mm, making it difficult for fluids such as river water or seawater to flow in, resulting in a low concentration of dissolved oxygen inside the gap. Become. Therefore, in such a runner, a local battery is formed in which the outside of the gap is the cathode and the inside of the gap is the anode, depending on the concentration of dissolved oxygen inside and outside the gap. Corrosion occurs inside the gaps, resulting in crevice corrosion and pitting corrosion.

The configuration of the present invention based on this knowledge is such that a ring-shaped sacrificial anode made of a metal having a higher ionization tendency than the runner blades and the support plate is attached to each of the runner blades and the support plate. It is characterized in that it is attached so as to be electrically connected to the support plate.

F Effect In the water turbine runner according to the present invention, a sacrificial anode is provided which is connected to the runner blade and the support plate and is made of a material with a higher ionization tendency than these materials, so that the sacrificial anode becomes a new anode. Corrosion current now flows only from the

In this manner, the water turbine runner according to the present invention prevents crevice corrosion and pitting corrosion between the runner blade and the support plate by corroding and eluting the sacrificial anode.

G. Embodiment A preferred embodiment of the present invention will be described below with reference to the drawings. Note that the same parts as those in the prior art are given the same numbers, and redundant explanations will be omitted.

FIG. 1a is a partial side view showing the structure of the runner according to the present invention, and FIG. 1b is a sectional view taken along the line A-A'.

As shown in both figures, the sacrificial anode 20 is formed into a ring shape so as to be in close contact with both end surfaces of the runner blade 1a, and is fixed to the support plate 1b by welding 22 via a plurality of fasteners 21. . This fastener 21 is preferably made of the same material as the runner blade 1a and the support plate 1b, and is made of SS-41, SM41B,
Various SUS plates are used. sacrificial anode 20
As the material, a material having a larger ionization tendency than these materials can be used, such as magnesium or its alloy, zinc or its alloy, aluminum or its alloy.

The dimensions of the sacrificial anode 20 may be determined depending on the cross-sectional dimension of the runner blade 1a and the period during which the sacrificial anode 20 is renewed. Furthermore, when used in highly contaminated seawater, various sacrificial anode materials may be used depending on the environmental conditions, such as using zinc or its alloys, which have little self-corrosion.

In this embodiment, the sacrificial anode 20 is fixed to the support plate 1b by welding via the fastener 21, but it may of course be fixed with bolts or the like. It is also possible to directly attach it to the support plate 1b with bolts or the like without using the fasteners 21 or the like. Further, in this embodiment, the sacrificial anode 20 is formed into a ring shape, but it may be divided into several parts and attached. Further, in this embodiment, the sacrificial anode 20 is attached near the gap 11 on the rotating shaft side of the support plate 1b, but it may be attached away from the gap 11 and near the outer periphery of the support plate 1b.

As described above, various configurations of the sacrificial anode 20 can be considered, but it is sufficient that the sacrificial anode 20 is configured so that each of the runner blades 1a and the support plate 1b are electrically connected via the sacrificial anode 20.

H. Effect of the invention As specifically explained above with the examples,
According to the present invention, by providing a sacrificial anode on the runner of a water turbine, it is possible to prevent crevice corrosion and pitting corrosion in the gap between the runner blade and the support plate, and the durability of the runner can be greatly improved. can. Therefore, a water turbine using this runner can maintain reliability for a long period of time even when used in heavily polluted seawater.

[Brief explanation of the drawing]

Fig. 1a is a partial side view showing the structure of a water turbine runner according to an embodiment of the present invention, and Fig. 1b is its A.
-A' line sectional view, Figure 2 is a partial cross-sectional perspective view of a cross-flow turbine, Figure 3 is an explanatory diagram conceptually representing the water flow of a cross-flow turbine, and Figure 4a is a water turbine according to the prior art. A partial side view showing the structure of the runner,
FIG. 4b is a sectional view taken along the line A-A'. In the drawing, 1 is a runner, 1a is a runner blade,
1b is a support plate, 3 is a rotating shaft, 20 is a sacrificial anode, 2
1 is a fastener.

Claims (1)

[Scope of utility model registration request] A runner of a water turbine that has a plurality of runner blades and a support plate that supports the runner blades by arranging them in a cylindrical shape, and is supported on a water turbine casing by a rotating shaft provided on the support plate, wherein the plurality of runner blades are A metal such as magnesium or its alloy, zinc or its alloy, aluminum or its alloy, which is formed to electrically connect each end face of the blade and the support plate, and has a greater ionization tendency than the runner blade and the support plate. A water turbine runner characterized by having a ring-shaped sacrificial anode consisting of a ring-shaped sacrificial anode.