JPH0721895Y2 - Once-through turbine runner - Google Patents

Description

[Detailed Description of the Invention] A. Field of Industrial Application The present invention is intended to improve the efficiency of the water turbine for improving the runner of the once-through turbine.

B. Conventional technology A power generation system using a once-through turbine is known as a part of hydraulic energy recovery.

FIG. 8 is a partially cutaway perspective view showing a typical structure of a once-through turbine, and FIG. 9 is a sectional front view of the runner of the once-through turbine shown in FIG.

A runner 1 having a plurality of runner blades 1a rotated by the potential energy of water is rotatably supported by a rotary shaft 3 via a bearing 3a having a seal built in a casing 2. A nozzle 2 a is extended from the casing 2 between the casing 2 and the runner 1 in order to prevent water leakage and water flow scattering. An inlet pipe 4 is connected to the casing 2 on the upstream side of the runner 1, and a guide vane 5 for adjusting the amount of water entering the runner 1 can be opened and closed on the inlet side of the casing 2 corresponding to the outlet side of the inlet pipe 4. It is provided in. On the downstream side of the runner 1, another casing 6 is connected to the casing 2, and a water discharge pipe 7 that hangs down is connected to these casings 2, 6. In addition, this water discharge pipe is guided into water. The water flowing in through the inlet pipe 4 is adjusted by the guide vanes 5 into the runner 1, is discharged from the outer periphery of the runner 1 after being rotated, and is discharged into the water through the water discharge pipe 7.

During operation of the water turbine, air is mixed into the discharged water and discharged, so that the pressure inside the water turbine chamber including the casings 2 and 6 becomes negative. This negative pressure state acts as a force for forcibly sucking in water from the inlet pipe 4, and consequently improves the efficiency of the water turbine. On the other hand, when the water pressure inside the water turbine chamber becomes negative, the water discharge surface in the water discharge pipe 7 rises. However, since the water discharge surface rises as the runner 1 is submerged, it is uncomfortable. A valve device 8 is provided in the casing 6 in order to properly operate the valve. That is, when the negative pressure in the turbine interior reaches a certain value, the valve device 8
Is opened to introduce air into the turbine to prevent the negative pressure in the turbine from exceeding a certain value.

The runner 1 of this once-through turbine is composed of a large number of runner blades 1a processed into an airfoil cross section, a disc-shaped side plate 1b and a partition plate 1c for supporting the runner blades 1a, and a side plate 1b and a partition plate. A portion surrounded by the plate 1c and the runner blade 1a is a runner chamber. The rotary shaft 3 penetrates through this runner chamber. Further, the side plate 1b is attached at a right angle to the rotating shaft 3, and the cross section of the runner chamber is rectangular.
In addition, 2b in FIG. 9 is a partition for dividing the guide vanes.

C. Problems to be solved by the device The amount of water that can be swallowed by the once-through turbine is determined by the amount of water that can flow through the runner 1, and this amount is determined by the height of the water channel formed by the rotating shaft 3 and the casing 2. If the amount of water that exceeds this is applied, the water flow will contact the rotating shaft 3, the inflow and outflow angles of the runner blade 1a will be significantly different from the installation angle of the runner blade 1a, and the efficiency will be reduced. Will act as a brake on the runner blade 1a. For this reason, the design is such that the amount of water that can flow into the turbine is limited.

The present invention has been made in view of the above situation, and provides a runner capable of passing a larger amount of water in an once-through turbine having the same water channel height without any inconvenience, thereby improving the efficiency of the once-through turbine. The goal is to achieve without changing.

D. Means for Solving the Problems The structure of the present invention for achieving the above-mentioned object is to install disc-shaped side plates on both ends of the rotary shaft, and to install a plurality of runner blades on the radial outer periphery of the side plates. A runner, which is arranged in a cylindrical shape and is supported by the turbine casing by the rotating shaft, wherein the spacing between the rotating shaft support portions of the side plates in the axial direction of the rotating shaft is wider than the spacing in the radial outer peripheral portion. It is characterized by

E. Widen the rotating shaft support side of the working side plate, and increase the waterway width within the same runner for the waterway height.

F. Embodiment FIG. 1 shows a cross-sectional front view of a runner of a once-through turbine according to one embodiment of the present invention, and FIG. 2 shows its cross-sectional side surface. still,
The same members as those in FIGS. 8 and 9 are designated by the same reference numerals, and duplicate description will be omitted.

Reference numeral 21 is a side plate, and the pair of side plates 21 are provided such that a space X between the rotary shaft support portions in the axial direction of the rotary shaft 3 is larger than a space Y between the outer circumferences in the radial direction. The arrangement of the partition plate 1c on the rotary shaft 3 is as follows. That is, for the inlet l ₁ water select l ₁₀ as equivalent waterway width is trapezoidal cross-section waterways a waterway inside runner 1 is the constant ratio _{R (R = l 1 / l} 10), likewise l ₂ And l ₁₁ , l ₃ and l ₁₂ are selected so as to have a ratio of R. Therefore, the width of S in FIG. 1 has a constant ratio R within the range of ₀ to l 0/2.
The position of the partition 2b is determined as follows. That is, R is set so that the three water channels in the figure have the same ratio.

In the above-mentioned runner 22, as shown in FIG. 2, the flow passing through the guide vanes 5 flows from the outer circumference of the runner 22 to the inner circumference, and part of the flow flows into the runner blade 1a. The water flowing into the runner blade 1a again flows from the inner circumference of the runner 22 to the outer circumference and is discharged to the outside of the runner 22. The other part flows into the runner blade 1a, is reversed, and is discharged to the outer periphery of the runner 22. Let the former flow be B flow and the latter flow be A flow. In the once-through turbine, the A flow is relatively inferior in power conversion efficiency and the B flow is good. Further, this flow cannot flow over the water passage L formed by the rotating shaft 3 and the casing 2, and when a large amount of water is made to flow, the water outside the L range comes into contact with the rotating shaft 3 and comes into contact with the rotating shaft 3.
Flows to the opposite side and collides with the runner blade 1a. This flow therefore brakes the turbine, significantly reducing turbine efficiency. Therefore, it is necessary to keep the amount of water within the L range.

According to the runner 22, l ₁₀ (equivalent water channel width) is expanded relative to l ₁ to increase B flow and improve turbine efficiency.
The height W of the water channel with the same amount of water decreases. Conventional structure (8th,
In Fig. 9, the flow indicated by the dotted line in Fig. 2 is changed to the flow indicated by the two-dot chain line in the runner 22 and the water channel height W is reduced by U compared with the conventional one. Therefore, the amount of water that can be flowed by the turbine of the same size increases, and a larger output can be obtained.

On the other hand, in the runner 22, the flow of water causes a streamline in the turbine to bend in the axial direction, which may cause a slight decrease in efficiency.
As can be seen from the figure, the efficiency does not decrease because the water flows in the runner 22 along the runner 22 in a direction perpendicular to the axis, but rather the efficiency improves as a whole because the B flow increases. . Further, the runner blade 1a is usually welded to the side plate 21 (can be cast), but since the distance between the pair of side plates 21 is wide on the rotary shaft 3 side, the effect of relaxing radial welding stress (casting stress) is obtained. is there.

Fig. 3 shows the efficiency-flow rate characteristics of the conventional runner 1 and the runner 22 of the present invention. The once-through turbine using the runner 22 shows a slight improvement in efficiency, especially at high flow rates (absolute flow rates). It can be seen that the improvement is large and the amount of water is also increasing. Third
In Fig. 4, the flow rate is shown as a percentage (%), and since the absolute flow rate is increasing, the efficiency improvement at the partial load appears significantly, and the efficiency improvement at the maximum flow rate partial load flow rate can be seen.

FIG. 5 shows an embodiment of a runner 31 used in a relatively high head water turbine, which is a single-flow guide vane type once-through turbine having a shaft length shorter than its diameter. In this example, the partition plate 32 has an inner diameter larger than the shaft diameter of the rotary shaft 3, and is not connected to the rotary shaft 3. Further, the width l ₂₁ on the rotary shaft 3 side and the width l _{22 on the} radial outer side of the water channel surrounded by the side plate 33, the runner blade 1a and the rotary shaft 3 can be increased.

6 and 7 show runners 41 and 51 of still another embodiment, in which the side plate 42 of the runner 41 is formed in a curved sectional shape.
The rotation shaft support side of 41 is wider. Also, runner 51
The pair of side plates 52 has a structure in which the width of the middle portion is narrowed and the runner 51 has a wider rotary shaft support portion side. Lanna 41,5
Both have the same effects as the runner 22 shown in FIGS.

The above-described run-through turbine runner of the present invention can improve the efficiency near the partial load and the maximum flow rate, and can increase the amount of water swallowed by the turbine of the same size to obtain a high-output turbine, which reduces the manufacturing price. You can get an inexpensive turbine. In addition, the stress can be relaxed by welding (casting) the runner blade 1a, a larger stress can be tolerated, and it is particularly effective for high-head water turbines (water turbines with a small aspect ratio). Cost reduction and efficiency improvement can be achieved.

G. Effect of the Invention In the runner of the once-through turbine of the present invention, since the gap between the side plates of the rotary shaft supporting portion is widened to widen the water channel width, a larger amount of water can be generated without any inconvenience in a once-through turbine having the same water channel height. Can be threaded. As a result, it is possible to improve the efficiency of the water turbine without changing the physique of the once-through turbine.

[Brief description of drawings]

FIG. 1 is a sectional front view of a runner of a once-through turbine according to an embodiment of the present invention, FIG. 2 is a sectional side view thereof, and FIGS.
Efficiency characteristic diagram, FIGS. 5, 6 and 7 are sectional front views of runners according to other examples, and FIG. 8 is a partially cutaway perspective view of a conventional once-through turbine.
FIG. 9 is a sectional front view of the runner. In the drawing, 1a is a runner blade, 2 is a casing, 3 is a rotating shaft, 2
1,33,42,52 are side plates, and 22,31,41,51 are runners.

Claims (1)

[Scope of utility model registration request] 1. A disk-shaped side plate is attached to both ends of a rotary shaft,
A runner in which a plurality of runner blades are arranged in a cylindrical outer circumferential portion of the side plate in a cylindrical shape, and the runner is supported by the water turbine casing by the rotating shaft, the rotating shaft supporting portion of each side plate in the axial direction of the rotating shaft. A runner for a once-through turbine, characterized in that the side spacing is wider than the radial outer circumferential side spacing.