JPH10103212A - Kaplan turbine - Google Patents

Abstract

(57) [Summary] [Problem] To provide a Kaplan-turbine designed to surely prevent a floating phenomenon of a rotating body having a runner, a runner vane, and a main shaft. A Kaplan turbine according to the present invention includes a hydraulic penstock (16) connected to an inlet of a water turbine casing (15) and a runner (21) having a runner vane (20) in an intermediate passage (18) connecting an outlet of the water turbine casing (15) and a suction pipe. In the Kaplan turbine, a hydraulic pipe is provided which branches off from the penstock 16 and connects to the upstream side of the runner vane 20 in the intermediate passage 18.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Kaplan turbine, and more particularly to a Kaplan turbine designed to prevent runners from being lifted when operation is stopped or when a load is cut off.

[0002]

2. Description of the Related Art Generally, as shown in FIG. 6, in a Kaplan turbine, a runner 5 having a runner vane 4 in an intermediate flow path 3 connecting a water turbine casing 1 and a suction pipe 2 is integrated with a main shaft 6 (rotary shaft). The runner vanes 4 are rotationally driven by the energy of hydraulic fluid guided from the turbine casing 1 through the stay vanes 7 and the guide vanes 8,
The rotating drive force is used to drive a generator (not shown) as rotational torque via a main shaft 6 which is axially mounted by a thrust bearing 9.

[0003] The intermediate flow path 3 is divided into an upper flow path 10 and a lower flow path 11 with the runner vane 4 as a boundary. The upper flow path 10 has a vacuum break valve 12 and the lower flow path 11 has a suction pipe 2. And a water discharge garden 13 that communicates with the intermediary.

[0004] In the Kaplan turbine having such a configuration, the hydraulic fluid guided from the penstock (not shown) to the turbine casing 1 is rectified by the stay vanes 7, the flow rate is adjusted by the guide vanes 8, and the energy thereof is reduced. The water is supplied to the runner vane 4 and driven to rotate. After the rotation, the water is stored in the water discharge garden 13 via the suction pipe 2.

[0005] Incidentally, when the operation of the Kaplan turbine is stopped or when the operation is stopped due to load interruption due to some trouble in the system, as shown in FIG.
The guide vane 8 is closed, the rotation angle of the runner vane 4 is changed from the open state to the closed state, and the hydraulic water guided from the water turbine casing 1 to the runner vane 4 has been cut off.

However, unlike other types of water turbines, such as Pelton turbines and tubular water turbines, the Kaplan turbine has an inertia force even when water is cut off, so that the rotation speed exceeds the rated rotation speed as shown in the figure. The so-called floating phenomenon of the rotating body including the main shaft 6 and the runner 5 occurs as the rotation speed increases. In FIG. 7, the lifting of the rotating body occurs when the ratio between the reverse shaft thrust and the weight of the rotating body exceeds 1.0.

As shown in FIG. 6, when the supply of hydraulic fluid is cut off, although the pressure P _{1 of the} hydraulic fluid in the upper flow channel 10 gradually decreases, as shown in FIG. Conversely shaft thrust F shown in the illustrated arrows is considered to be due to be generated by an increase from suction pipe 2 inside the pressing force P ₂ toward the runner 5 11 (water lifting power). In addition, the rising of the rotating body also appears when the guide vane 8 has a small valve opening and the head difference Hs of the water discharge garden 13 is high.

The means for preventing the floating of the rotating body may be adjusted by lowering the head of the water discharge garden 13 communicating with the lower flow path 11.
Alternatively, it is conceivable that the pressure in the upper flow path 10 is not reduced.

However, in the former case, it is impossible to adjust the water head low during operation itself due to operating conditions, and the water head difference Hs between the water surface of the water discharge garden 13 and the runner vane 4 due to recent high speed and downsizing. Unrealistic today is growing.

In the latter case, the pressure in the upper flow path 10 is adjusted by opening the vacuum breaking valve 12 when the pressure becomes equal to or lower than the atmospheric pressure, and controlling the pressure in the upper flow path 10 and the atmospheric pressure. Although the same pressure level has been maintained, the water pressure difference Hs between the water surface of the water discharge yard 13 and the runner vane 4 is large. Today, the same pressure level is temporarily maintained, and the runner vane is discharged from the suction pipe 2 with the passage of time. The lifting of the rotating body still occurs due to the pressing force P ₂ of the moving water toward 4.

When the atmosphere is supplied into the upper flow path 10 by using the vacuum break valve 12, the air and the hydraulic fluid are separated with the passage of time, so that the runner vanes 4 are separated from the air layer and the hydraulic layer. Driving in a state of living together, intermittent lifting has occurred.

As means for preventing such lifting,
Conventionally, movable adjustment has been performed to change the rotation angle of the runner vane 4 from the closed state to the open state. However, considering that the movable adjustment often fails, the vacuum break valve 12 is not used.
Supplying the atmosphere into the upper flow path 10 by using the gas has already reached its limit, and is currently searching for it.

[0013]

As disclosed in Japanese Patent Application Laid-Open No. 56-83477, for example, the means for preventing the floating of the rotating body supplies high-pressure air to the runner chamber as in the case of performing the water surface lowering operation at startup. It is disclosed that the runner vane is operated in air to suppress the generation of the reverse shaft thrust.

However, in the prior art disclosed in Japanese Patent Application Laid-Open No. 56-83577, when the runner vane is operated in the air, the stop operation time becomes long, and the air layer and the hydraulic layer coexist halfway. However, since the runner vane is operated, there is a problem that an intermittent lifting phenomenon still occurs.

Another solution is to provide a bypass passage or a bypass chamber for communicating the upper flow path and the lower flow path with each other, and to use a pressing force (water level rising force) from the suction pipe toward the runner vane. Techniques for preventing the generation of reverse axial thrust by pressure-balancing the flow path and the lower flow path have already been disclosed in JP-A-56-64159 and JP-A-61-406.
No. 9 is published.

However, in the prior art disclosed in Japanese Patent Application Laid-Open No. 56-64159 and Japanese Utility Model Application No. 61-4069, the pressing force generated when the water level of the suction pipe rises toward the runner is utilized. It takes some time until the upper flow path and the lower flow path are pressure-balanced. During this time, there is an inconvenience that a reverse axial thrust is generated and the floating phenomenon cannot be completely prevented.

The present invention has been made in view of such circumstances, and it has been found that the floating phenomenon of the rotating body can be more quickly achieved.
It is an object of the present invention to provide a Kaplan turbine that can be prevented more reliably.

[0018]

In order to achieve the above object, a Kaplan turbine according to the present invention has a penstock connected to an inlet of a water turbine casing and an outlet of the water turbine casing. In a Kaplan turbine in which a runner having a runner vane is installed in an intermediate passage connecting the suction pipe and a suction pipe, a hydraulic pipe branched from the penstock and connected to an upstream side of the runner vane in the intermediate passage is provided.

In order to achieve the above object, in the Kaplan turbine according to the present invention, as set forth in claim 2, the hydraulic pipe is provided with a control valve for controlling the hydraulic water jetted to the upstream side of the runner vane in the intermediate passage. It is provided with.

In order to achieve the above object, in the Kaplan turbine according to the present invention, as set forth in claim 3, the water pipe comprises a manifold surrounding the runner vane in an annular shape, and a hydraulic fluid from the manifold to the runner vane. It has a spout to spout.

In order to achieve the above object, in the Kaplan turbine according to the present invention, the jet port is arranged so as to face in the direction opposite to the rotation direction of the runner vanes.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a Kaplan turbine according to the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram showing an embodiment of a Kaplan turbine according to the present invention.

The Kaplan turbine 14 is provided with a hydraulic iron pipe 16 in which a hydraulic water from a dam (not shown) is provided in a spiral water turbine casing 15 on the way of which an inlet valve 16a is interposed.

The Kaplan turbine 14 is provided with an intermediate flow path 18 connecting the water turbine casing 15 and the suction pipe 17, and a stay vane 19, a guide vane 20, and a runner 21 are provided in the intermediate flow path 18. It is configured to be installed sequentially along the flow.

The runner 21 has a runner vane 22 whose rotation angle can be freely changed, and is mounted on a thrust bearing 23 to provide a generator (not shown) with a rotation torque and a main shaft 24.

The intermediate passage 18 is provided with a runner vane 22.
Is formed into an upper flow path 25 and a lower flow path 26 that are divided when closed. The lower flow path 26 is provided with a suction pipe 17 and communicates with a water discharge garden 27. .

On the other hand, in the upper channel 25 of the intermediate channel 18,
A hydraulic pipe 29 branched from the penstock 16 and provided with a control valve 28 is provided.

As shown in FIG. 2, the hydraulic pipe 29 is provided on the manifold 3 surrounding the runner vane 22 in an annular shape.
0 and an outlet 31 for ejecting fluid from the manifold 30 toward each runner vane 22.
As shown in FIG. 3, the jet port 31 of the manifold 30 is installed so as to jet fluid in a direction (counterclockwise) opposite to the rotation direction of the runner vanes 22.

Next, the operation will be described.

As shown in FIG. 5, when the Kaplan turbine 14 is stopped or the load is stopped, the guide vane 20 is first closed, and then the rotation angle of the runner vane 22 is reduced from the open state. The movement is adjusted. In this case, when the rotation angle of the runner vane 22 is moved to the closed state as shown by the solid line in the drawing, the rotation speed of the runner vane 22 greatly overshoots the rated speed,
It may cause lifting of the rotating body. For this reason, in the present embodiment, as shown in FIG. Is braked as shown by the broken line in FIG. In addition, the timing for ejecting the hydraulic fluid from the ejection port 31 to the ventral side of the runner vane 22 is as follows.
When the guide vane 20 is closing the valve and the upper flow path 25 and the lower flow path 26 are pressure-balanced, or when the hydraulic fluid in the suction pipe 17 reaches the runner vane 22 and the pressing force is generated, the control valve The valve 28 is opened to adjust the flow rate of the hydraulic fluid.

As described above, in the present embodiment, at the time of the stop operation of the Kaplan turbine or at the time of the stop operation due to the load interruption, the high-pressure hydraulic water of the penstock 16 is used to move the hydraulic water from the jet port 31 of the hydraulic water pipe 29. Is spouted in a direction opposite to the rotation direction of the runner vane 22, and the rotation angle of the runner vane 22 is controlled in the open state direction so that the moving water can collide with the ventral side of the runner vane 22, and the rotation speed of the runner vane 22 is braked. Therefore, it is possible to prevent the rotating body from being lifted as shown in FIG. In the balance characteristic of the rotating body shown in FIG. 5, the ratio of the weight of the rotating body to the reverse axial thrust is set to 1.0, and if the ratio exceeds 1.0, the rotating body is lifted. Indicates that

[0033]

As described above, the Kaplan turbine according to the present invention is provided with a hydraulic pipe which branches off from the penstock and is connected to the upper flow path. The pressure is balanced with the pressing force of the hydraulic fluid generated from the suction pipe toward the lower flow path, preventing the reverse shaft thrust generated in the rotating body, and the lifting of the rotating body more reliably than before Can be prevented.

In the Kaplan turbine according to the present invention, the outlet of the hydraulic pipe is installed in the direction opposite to the rotation direction of the runner vane, and the rotation angle of the runner vane is set so that the hydraulic water from the outlet can collide with the ventral side of the runner vane. Is moved in the opening direction so that the increase in the rotation speed of the runner vane is braked, so that the increase in the rotation speed exceeding the rated speed of the runner vane can be suppressed lower than before.

Therefore, in the Kaplan turbine according to the present invention, since the stop operation is performed with the increase in the rotation speed relative to the rated rotation speed of the runner vane significantly lower than in the conventional case, the floating of the rotating body can be more quickly and more reliably lifted. Can be prevented.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an embodiment of a Kaplan turbine according to the present invention.

FIG. 2 is a schematic plan view seen from the direction of the arrow Z in FIG. 1;

FIG. 3 is an explanatory view developed in a plan view of FIG. 2;

FIG. 4 is a rotational speed distribution diagram of a runner vane showing that the increase in the rotational speed with respect to the rated rotational speed of the runner vane is lower than that in the related art.

FIG. 5 is an explanatory diagram showing a stop operation procedure of the Kaplan turbine according to the present invention, in which the floating state of the rotating body, the rotation speed of the runner vane, the rotation angle of the runner vane, and the guide vane opening are associated with each other.

FIG. 6 is a schematic view showing an embodiment of a conventional Kaplan turbine.

FIG. 7 is an explanatory view showing a stop operation procedure of a conventional Kaplan turbine, in which a floating state of a rotating body, a rotation speed of a runner vane, a rotation angle of a runner vane, and a guide vane opening are associated with each other.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Turbine casing 2 Suction pipe 3 Intermediate flow path 4 Runner vane 5 Runner 6 Main shaft 7 Stay vane 8 Guide vane 9 Thrust bearing 10 Upper flow path 11 Lower flow path 12 Vacuum break valve 13 Water discharge yard 14 Kaplan turbine 15 Turbine casing 16 Hydraulic iron pipe 16a Inlet Valve 17 Suction pipe 18 Intermediate flow path 19 Stay vane 20 Guide vane 21 Runner 22 Runner vane 23 Thrust bearing 24 Main shaft 25 Upper flow path 26 Lower flow path 27 Water discharge yard 28 Control valve 29 Hydraulic pipe 30 Manifold 31 Spout

Claims (4)

[Claims] 1. A Kaplan turbine having a hydraulic penstock connected to an inlet of a water turbine casing and a runner having a runner vane installed in an intermediate passage connecting an outlet of the water turbine casing and a suction pipe. A Kaplan turbine characterized by having a water pipe connected to an upstream side of a runner vane in a passage. 2. The Kaplan turbine according to claim 1, wherein the hydraulic pipe is provided with a control valve for adjusting hydraulic water jetted upstream of the runner vanes in the intermediate passage. 3. The Kaplan turbine according to claim 1, wherein the hydraulic pipe includes a manifold surrounding the runner vane in an annular shape, and an outlet for jetting hydraulic water from the manifold to the runner vane. 4. The Kaplan water turbine according to claim 3, wherein the jet port is disposed in a direction opposite to a rotation direction of the runner vane.