JPH08291786A - Leakage preventing device at the time of condenser operation - Google Patents

Abstract

PURPOSE: To dispense with deep drilling for taking the height of a draft pipe in order to prevent air from leaking to the draft pipe at the time of condenser operation of a hydraulic turbine or a pump hydraulic turbine. CONSTITUTION: An air leakage preventing device at the time of condenser operation is provided with an air sump 9 arranged downstream from the bending part of a draft pipe 5, piping 10 for connecting the air sump 9 and a racing liner 1 to each other, and a valve 11 arranged on the way of the piping.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a measure for preventing leakage of push-down air to a downstream side of a suction pipe 5 when the runner 1 idles in a phase-matching operation of a turbine or a pump turbine.

[0002]

2. Description of the Related Art FIG. 2 shows a state of a conventional turbine or pump turbine when a runner idles. In the figure, 1 is a runner, 2 is a runner cone, 3 is an upper cover, 4 is a lower cover, 5 is a suction pipe, 6 is a guide vane, 7 is a supply / exhaust pipe, and 8 is a main shaft.

When performing the phase-matching operation of the water turbine or the pump water turbine or starting the pump of the pump water turbine, as shown in FIG. 2, while the guide vane 6 is fully closed, compressed air is sent from the air supply / exhaust pipe 7 to the runner 1. The water in the portion (2) is pushed down to hold the water surface at the position A where the runner 1 does not come into contact with the water surface, the runner 1 idles, and the torque required to rotate the runner 1 is reduced.

The reason why compressed air is necessary for the pushing down is as follows.
This is because generally, in a water turbine or a pump turbine, the position of the runner 1 is installed below the water level of the lower dam in order to prevent cavitation generated in the runner 1.

When the runner 1 idles in this state, a swirling flow of air in the suction pipe 5 due to the idle rotation excites a wave having a large wavelength on the depressed water surface, and the condition of the water surface is A.
Changes from B to B. In this case, when the pushed-down water surface position is not sufficiently low and becomes a wavy water surface like B, the runner 1 comes into contact with the water surface, and large torque fluctuations and rotational vibrations of the main shaft occur.

On the other hand, if the pushed water surface position is too low, the bent portion of the suction pipe 5 becomes a water surface state like B,
A situation occurs in which compressed air leaks behind the suction pipe 5. In order to prevent this, conventionally, the length of the suction pipe 5 in the height direction is lengthened to keep the position of the water surface optimal so that the above-mentioned problems do not occur even if waves occur on the water surface. It was

[0007]

As described above, in the prior art, the method in which the suction pipe 5 is lengthened in the height direction against the contact between the water surface and the runner 1 or the leakage of air has been adopted. However, in order to increase the height of the suction pipe 5, it is necessary to excavate deeply, and the suction pipe 5 becomes long, which is uneconomical.

According to the present invention, an air reservoir 9 is provided in the ceiling portion downstream of the bent portion of the suction pipe 5, and an air pipe connecting the air reservoir and the suction pipe 5 at the lower portion of the runner is installed. The leaked air is trapped in the air reservoir 9 and the runner 1 is used again.
By returning to the lower portion, it is possible to prevent the leaked air from escaping to the rear of the suction pipe 5, and to prevent the compressed air from decreasing.

An object of the present invention is to provide a device which does not need to be deeply drilled, because the suction pipe has a height for preventing leakage of air to the suction pipe during a phase-matching operation of a water turbine or a pump turbine. .

[0010]

SUMMARY OF THE INVENTION An air leak prevention device during a phase-shifting operation according to the present invention includes a suction pipe 5 of a water turbine or a pump turbine, and an air reservoir 9 provided downstream of a bent portion of the suction pipe. An air leak preventing device at the time of a phase-shifting operation, which has an air pipe 10 connecting the air reservoir and a lower part of the runner 1 which is idling, and a valve 11 provided in the middle of the air pipe. It is characterized by becoming.

[0011]

By providing the air reservoir 9, the compressed air that tries to escape backward along the ceiling portion of the suction pipe 5 is captured, and further captured by the air pipe 10 that connects the air reservoir 9 and the lower portion of the runner 1. The air can be effectively used again.

[0012]

Embodiments of the present invention will be described below with reference to FIG. FIG. 1 is a block diagram of the entire apparatus according to the first embodiment. In FIG. 1, 1 is a runner, 2 is a runner cone,
3 is an upper cover, 4 is a lower cover, 5 is a suction pipe, 6 is a guide vane, 7 is a supply / exhaust pipe, 8 is a main shaft, 9 is an air reservoir, 1
Reference numeral 0 indicates an air pipe, and 11 indicates a valve.

FIG. 1 shows a situation in which the runner 1 is idling by pushing down the water surface. At this time, a wave is generated in the state of B on the water surface in the suction pipe 5. Although the water surface is in a position where it does not come into contact with the runner 1, the bubbles 12 entrained in the water from the bent portion below the suction pipe 5 downstream due to the fluctuation of the wave front.
But flows from the bent portion of the suction pipe 5 along the ceiling of the horizontal portion of the water flow.

However, there is an air reservoir 9 on the downstream side, and the bubbles 12 flowing in are trapped by the air reservoir 9 and pass through the air pipe 10, and further pass through the valve 11 in an open state, as shown in FIG. It is returned to the lower part of the runner again from the pipe wall of the suction pipe 5 below the runner 1. The valve 11 is closed when the turbine or pump turbine is operating normally except when the runner is idling.

[0015]

According to the present invention, in the suction pipe of the turbine or the pump turbine, an air reservoir is provided downstream of the bent portion of the suction pipe, and the air accumulated there is returned to the lower portion of the runner through the air pipe to compress the air. Air can be prevented from escaping, and stable phase-matching operation can be performed.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an entire apparatus according to an embodiment of the present invention.

FIG. 2 is a corresponding diagram of FIG. 1 of a conventional example.

[Explanation of symbols]

1 ... runner, 2 ... runner cone, 3 ... upper cover, 4 ... lower cover, 5 ... suction pipe, 6 ... guide vane, 7 ... supply / exhaust pipe, 8 ... spindle, 9 ... air reservoir, 10 ... air pipe, 11 ...
Valve, 12 ... bubble.

Claims (1)

[Claims] 1. A suction pipe (5) of a water turbine or a pump turbine, comprising an air reservoir (9) provided downstream of a bent portion of the suction pipe and a lower portion of a runner (1) idling with the air reservoir. An air leak prevention device at the time of a phasing operation, which has an air pipe (10) to connect and a valve (11) provided in the middle of the air pipe.