JP4653774B2 - How to prevent sediment wear on Pelton turbine - Google Patents

Description

  The present invention relates to a method for preventing a runner of a Pelton turbine used in a hydroelectric power plant from being worn by earth and sand.

  FIGS. 17 and 18 are a side view and a plan view, respectively, showing a schematic configuration of a Pelton turbine that has been generally used in a power plant as an example of a vertical double-split structure, and a runner directly connected to the main shaft 1. A plurality (two in the illustrated example) of nozzle pipes 4 are arranged toward a large number of buckets 3 provided around 2. The nozzle pipe 4 is connected to a hydraulic iron pipe 7 through a casing 5 and an inlet valve 6, and a needle valve 8 is inserted into each nozzle pipe 4.

  In the Pelton turbine having such a configuration, the pressure water from the hydraulic iron pipe 7 is injected from the tip of the nozzle pipe 4 toward the bucket 3 via the inlet valve 6 and the casing 5, and the runner is caused by the collision force of the water pressure. Rotational force is generated in 2 and the runner 2 and the generator 9 directly connected to the runner 2 via the main shaft 1 are rotated.

  However, when the conventional Pelton turbine described above is operated in a river with a lot of earth and sand, the sand and sand flowing from the hydraulic iron pipe 7 is mixed with jet water ejected from the tip of the nozzle pipe 4 at a high speed. Therefore, the runner 2 such as the bucket 3 is worn by the earth and sand, which is a factor for shortening the life of the runner 2. When the earth and sand are large or sharp, the bucket 3 may be partially damaged, and when the draining portion 3a including the ridge portion of the bucket 3 is heavily worn, the efficiency is significantly reduced and the axial thrust is increased. There were problems such as a decrease in turbine performance.

  The present invention has been made to solve such a problem, and prevents wear of the runner 2 due to earth and sand by preventing mixing of earth and sand into jet water ejected from the nozzle pipe 4 toward the bucket 3. And it aims at providing the abrasion prevention method of the Pelton turbine which can aim at maintenance of runner 2 and life extension.

According to a first aspect of the present invention, in the method for preventing sediment wear of a Pelton turbine by causing pressure water to be ejected from a hydraulic iron pipe toward a bucket to rotate the runner, the runner is idly started when the turbine is started, and the rotational speed is a predetermined rotation. When the speed is reached, the needle valve is opened, and jet water from the nozzle is ejected toward the bucket to shift to normal operation.

Further, the invention of claim 2 is characterized in that, in the invention of claim 1 , the runner is idlingly started by a drive unit directly connected to the turbine main shaft.

The invention of claim 3 is characterized in that, in the invention of claim 1 , the runner is idly started by a small impeller directly connected to the runner.

As apparent from the above description, the present invention, at startup, according to the method for ejecting jet water toward the bucket of the runner is rotated in advance, the collision receiving from sediment bucket is ejected mixed jet water Since the force is greatly reduced as compared with normal startup, runner wear due to earth and sand is prevented, and runner maintenance and life extension can be achieved.

  Hereinafter, each reference example and each embodiment of the present invention will be described with reference to FIGS. In the figure, the same parts as those in FIGS. 17 and 18 are denoted by the same reference numerals, and detailed description thereof is omitted.

First Reference Example FIG. 1 is a view showing a first reference example of the present invention. The hydraulic iron pipe 7 on the upstream side of the inlet valve 6 is provided in the vicinity of the bent pipe portion 7 a of the hydraulic iron pipe 7 or the inlet valve 6. A sediment separating and discharging conduit 11 having a valve 10 is branched and led out immediately before.

  Thus, high-pressure water flows through the hydraulic iron pipe 7 during the operation of the water turbine. In the curved pipe portion 7a, large sediment which has a specific gravity greater than that of water and which easily causes wear to the runner is generated in the direction of main water flow due to its inertial action. It does not flow in a certain arrow b direction, but flows in the direction of the sediment separating and discharging conduit 11 as indicated by an arrow a, and accumulates in the sediment separating and discharging conduit 11. Moreover, the earth and sand from the upstream side of the hydraulic iron pipe while the water turbine is stopped also flows into the earth and sand separation / discharge conduit 11.

  Therefore, the accumulated sediment flowing into the sediment separating and discharging conduit 11 can be discharged out of the conduit by opening the valve 10 as necessary. Therefore, it is possible to prevent the earth and sand from being mixed into the jet water ejected from the nozzle pipe 4 toward the bucket 3, and to prevent the runner from being worn by the earth and sand.

Second Reference Example By the way, in the first reference example, since the amount of sediment deposited in the sediment separating and discharging conduit 11 cannot be confirmed, it is impossible to discharge sediment deposited outside the conduit in a timely manner. Also, there is concern about forgetting to discharge.

  Therefore, FIG. 2 is a view showing a second reference example of the present invention that can surely discharge the earth and sand. The earth and sand separation detector 12 such as a differential pressure gauge is connected to the earth and sand separating and discharging conduit 11. Is provided. The detection signal detected by the sediment accumulation detector 12 is sent to the control device 13, and the valve 10 is controlled to open and close via the valve drive device 14 by the control signal from the control device 13.

  Accordingly, when a certain amount of sediment is accumulated in the sediment separation / discharge conduit 11 and this is detected by the sediment accumulation detector 12, the valve 10 is automatically opened according to the detection output. Therefore, the earth and sand deposited on the earth and sand separating and discharging conduit 11 can be reliably and labor-savingly discharged out of the conduit, and mixing of the earth and sand into the jet water can be prevented.

Third Reference Example In the two reference examples described above, as described above, only the sediment separating and discharging conduit 11 is branched and led out to the hydraulic iron pipe 7. Therefore, in the case of a Pelton turbine located in a river with a lot of earth and sand, the earth and sand are filled in a short time, so the opening operation of the valve 10 must be performed frequently. Therefore, in the third reference example shown in FIG. 3, a sediment accumulation box 15 having a valve 10 is provided on the downstream side of the sediment separation and discharge conduit 11.

  Thus, as in the first reference example, the earth and sand contained in the flowing water in the hydraulic iron pipe 7 by the inertial action of the water flow in the hydraulic iron pipe 7 enters the earth and sand accumulation box 15 through the earth and sand separating and discharging conduit 11. Inflow and deposit. And the earth and sand which flowed into the earth and sand accumulation box 15 and were accumulated are discharged | emitted out of a conduit | pipe by opening the valve 10 as needed. Therefore, in this case, it is possible to accumulate a large amount of sand and sand as compared with the case where only the sediment separating and discharging conduit 11 is provided as in the first reference example. It is possible to prevent soil and sand from being mixed in.

Fourth Reference Example FIG. 4 is a diagram showing a fourth reference example, in which a sediment accumulation detector 12 is provided in a sediment accumulation box 15 connected to the sediment separation and discharge conduit 11, and the sediment accumulation detector. The opening control of the valve 10 is performed by the detection signal from 12. Therefore, this fourth reference example also has the same effects as the second reference example.

Fifth Reference Example and Sixth Reference Example FIGS. 5 and 6 show a fifth reference example and a sixth reference example, which are modifications of the first reference example and the second reference example shown in FIGS. 1 and 2, respectively. FIG. In the fifth reference example, the sediment separating and discharging conduit 11 is branched and led out on the axial extension of the upstream straight pipe portion 7b of the curved pipe portion 7a in the vicinity of the curved pipe portion 7a of the upstream casing of the nozzle pipe 4. ing. Further, in the sixth reference example, a sediment deposition detector 12 is provided in the sediment separation / discharge conduit 11. In the case where the water wheel has a horizontal shaft structure, the downstream side of the sediment separating and discharging conduit 11 is bent downward.

  Thus, in this case, as in the first reference example, the large earth and sand which is particularly likely to wear the runner is separated from the flow of the main water flow in the direction of arrow c due to its inertial action, and substantially in the linear direction as indicated by arrow d And flows smoothly into the sediment separation and discharge conduit 11. Therefore, by opening the valve 10 as necessary, the accumulated sediment flowing into the sediment separating and discharging conduit 11 can be discharged out of the conduit, and the same effect as the first reference example can be achieved.

  Moreover, as shown in FIG. 6, by providing a sediment accumulation detector 12 in the sediment separation / discharge conduit 11, the same effects as those of the second reference example can be achieved.

Seventh Reference Example and Eighth Reference Example FIGS. 7 and 8 show a seventh reference example and an eighth reference example, which are modifications of the fifth reference example and the sixth reference example shown in FIGS. 5 and 6, respectively. In the figure, a sediment deposit box 15 is provided downstream of the sediment separation / discharge conduit 11. In these cases, the same effects as those shown in FIGS. 3 and 4 are obtained.

Ninth Reference Example FIG. 9 is an operation explanatory view showing a ninth reference example of the earth and sand wear preventing method of the present invention. When the Pelton turbine is started, the earth and sand separation is performed before the inlet valve 6 or the needle valve 8 is opened. After the valve 10 provided in the discharge conduit 11 or the sediment deposit box 15 is opened for a predetermined time T1, after the valve 10 is closed, the inlet valve 6 or the needle valve 8 is opened and started.

  Thus, the earth and sand collected on the downstream side of the hydraulic iron pipe 7 or the upstream side of the nozzle pipe 4 before the opening of the inlet valve 6 or the needle valve 8 is discharged out of the pipe line and directed toward the bucket 3 from the nozzle pipe 4. It is prevented that earth and sand are mixed into the jet water jetted out.

Tenth Reference Example FIGS. 10 to 12 are views showing a tenth reference example of the present invention. By using a deflector 16 provided at the tip of the nozzle pipe 4, earth and sand are mixed into the jet water. To prevent.

  That is, when the needle valve 8 is opened when the Pelton turbine is started, the deflector 16 is closed as shown in FIG. 11A, and the jet water ejected from the nozzle pipe 4 is blocked by the deflector 16 for a predetermined time T2. 11 (b), the deflector 16 is opened, the jet water is injected into the bucket 3 of the runner 2, and the runner 2 is rotated. FIG. 12 shows the operation diagram.

  Thus, as shown in FIG. 11 (a), when the deflector 16 is closed, the earth and sand accumulated on the downstream side of the hydraulic iron pipe 7 or the upstream side of the nozzle pipe 4 does not hit the bucket 3 and is blocked by the deflector 16 together with the jet water. It is possible to prevent the earth and sand from colliding with the bucket 3 by falling.

First Embodiment FIGS. 13 and 14 are views showing a first embodiment of the present invention, in which a generator 18 such as a pony motor is connected to a generator shaft 17 connected to a turbine main shaft 1. By the way, the collision force that the bucket 3 receives from the jet water jetted from the nozzle pipe 4 is when jet water is jetted toward the bucket 3 while the runner 2 is stationary like when a conventional Pelton turbine is started. It is the strongest and decreases as the runner 2 begins to rotate and the rotational speed increases.

For this reason, in the first embodiment , as shown in the operation diagram of FIG. 14, when the Pelton turbine is started, before the needle valve 8 is opened, the runner 2 is idly started by the driver 18. And when this rotational speed reaches predetermined rotational speeds, such as synchronous rated speed, the needle valve 8 is opened, the jet water from the nozzle pipe 4 is spouted toward the bucket 3, and it transfers to normal electric power generation operation. Therefore, in this case as well, the strong collision force that the bucket 3 receives from the earth and sand accumulated in the jet water at the time of activation is greatly reduced compared to that at the time of conventional activation.

Second Embodiment FIGS. 15 and 16 are views showing a second embodiment of the present invention in which another means for rotating the runner 2 in advance before opening the needle valve 8 is provided. A small impeller 20 provided with a large number of blades on the circumference is directly connected to the lower portion. On the other hand, a branch pipe 22 having a valve 21 is branched on the upstream side of the nozzle pipe 4, and the tip of the branch pipe 22 is opened to face the blades of the small impeller 20.

When the Pelton turbine is started, as shown in FIG. 16, the valve 21 is opened before the needle valve 8 is opened, and the pressure water is discharged toward the blades of the small impeller 20 through the branch pipe 22. When the rotation speed of the runner 2 rotated together with the wheel 20 reaches a predetermined rotation speed such as a synchronous rated speed, the valve 21 is closed and the needle valve 8 is opened so that the jet from the nozzle pipe 4 is opened. Water is ejected toward the bucket 3 to shift to normal power generation operation.
Therefore, in this case as well, the same effects as those shown in FIGS. 13 and 14 can be obtained. Moreover, since the means for rotating the runner in advance is easy to assemble and can be achieved by a simple impeller such as a two-dimensional blade and a branch pipe, it can be arranged at a lower cost than that provided with the drive unit of FIG.

The figure which shows the 1st reference example of the earth and sand abrasion prevention apparatus of the Pelton turbine of this invention. The figure which shows the 2nd reference example of this invention. The figure which shows the 3rd reference example of this invention. The figure which shows the 4th reference example of this invention. The figure which shows the 5th reference example of this invention. The figure which shows the 6th reference example of this invention. The figure which shows the 7th reference example of this invention. The figure which shows the 8th reference example of this invention. Action | operation explanatory drawing of the 9th reference example of this invention. The figure which shows the 10th reference example of this invention. The figure which shows the operation | movement of a dereflector in the 10th reference example shown in FIG. Explanatory drawing of an effect | action of the 10th reference example shown in FIG. The figure which shows 1st Embodiment of this invention. Explanatory drawing of operation | movement of 1st Embodiment shown in FIG. The figure which shows 2nd Embodiment of this invention. Action | operation explanatory drawing of 2nd Embodiment . The side view which shows schematic structure of a general Pelton turbine. The top view which shows schematic structure of a general Pelton turbine.

DESCRIPTION OF SYMBOLS 1 Main shaft 2 Runner 3 Bucket 4 Nozzle pipe 5 Casing 6 Inlet valve 7 Hydraulic iron pipe 7a Curved pipe part 7b Straight pipe part 8 Needle valve 10, 21 valve 11 Sediment separation discharge conduit 12 Sediment accumulation detector 13 Controller 15 Sediment accumulation box 16 Deflector 18 Drive 20 Small impeller 22 Branch pipe

Claims (3)

In a Pelton turbine that rotates the runner by ejecting pressure water from the nozzle to the bucket,
When the water turbine starts up, the runner starts idling, and when the rotational speed reaches a predetermined rotational speed, the needle valve is opened and jet water from the nozzle is ejected toward the bucket to shift to normal operation. A method for preventing sediment wear in Pelton turbines. Claim 1 sediment wear prevention method Pelton wheel of, wherein the idle starting the runner by a driving motor which is directly connected to the water wheel spindle. Claim 1 sediment wear prevention method Pelton wheel of, wherein the idle starting the runners by small impeller is directly connected to the runner.

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