JP3630740B2 - Drain discharge device for steam turbine - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a steam turbine, and more particularly to a drain discharge device that collects water droplets flowing on the outer surface of a nozzle and discharges them as drain.
[0002]
[Prior art]
A steam turbine according to the prior art is shown in FIGS . FIG. 8 shows a typical paragraph structure of a steam turbine. In the passenger compartment 6, there are nozzles composed of a nozzle plate 3, a nozzle inner ring 4, and a nozzle outer ring 5. The steam that has passed through the nozzle and whose flow velocity has increased hits the blade 2 behind the nozzle, and rotates the rotor 1 to which the blade 2 is attached.
[0003]
When the pressure of the steam is reduced inside the steam turbine, the wetness is increased, and the moisture in the steam adheres to the surface of the nozzle plate 3 and becomes the drain 8. This drain 8 is pushed by the surrounding steam flow and jumps out from the outlet end of the nozzle plate 3 toward the blade 2 downstream. However, since the drain 8 has a lower speed than the surrounding high-velocity steam flow, it collides with the vicinity of the tip of the blade 2 and causes erosion while operating for a long time.
[0004]
In order to prevent the erosion of the blades 2 due to the drain 8, techniques as shown in FIGS. 9 and 10 are used. 9A and 9B, the drain 8 adhered to the outer surface from the slit 10 provided in the hollow nozzle plate 9 is taken into the hollow nozzle plate 9. FIG. Of the drain 8 that has entered the hollow nozzle plate 9, the one that has occurred in the upper half is guided to the lower half by a passage 11 provided in the nozzle inner ring 4, and the nozzle passes through a part of the hollow nozzle plate 9 in the lower half. A passage 12 (see FIG. 10 ) in the outer ring 5 flows in the circumferential direction, is led to a passage 13 that penetrates the vehicle compartment 6, and is discharged to an exhaust chamber (not shown).
[0005]
[Problems to be solved by the invention]
By the way, the technology for preventing the erosion of the blades 2 described above is easy to form all the drain passages including the nozzle casing 6 when a steam turbine is newly manufactured. However, if a similar drain passage is formed in the steam turbine in use, the casing 6 is a large pressure vessel, and therefore it can be easily disassembled and transported for processing. Not.
[0006]
When the drain passage cannot be formed in the passenger compartment 6, the drain passage cannot be completed to the end, so it becomes difficult to have the drain passage in the steam turbine, and this technique cannot be used to prevent the blade 2 from being eroded.
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a steam turbine drain discharge device capable of forming a drain passage without newly modifying a vehicle compartment.
[0007]
[Means for Solving the Problems]
According to the first aspect of the present invention, in order to guide water droplets moving on the outer surface of the nozzle through the slit to the passage of the nozzle outer ring and to discharge it as drain to the outside, the nozzle outer ring is provided with a through hole communicating with the passage, and the slit In the steam turbine drain discharge device in which the extracted drain is directly guided to the exhaust chamber through the through hole, a hole is formed in the steam guide in the front facing portion of the through hole provided in the nozzle outer ring. In addition, the drain is discharged outside the steam guide.
[0008]
Further, in the invention according to claim 2, the water droplet moving on the outer surface of the nozzle is led to the nozzle outer ring passage through the slit, and is discharged to the outside as a drain and communicated with the slit in the nozzle plate constituting the nozzle. In a steam turbine drain discharge device that forms a small chamber and connects a conduit for leading drain to the exhaust chamber from the lowest part of the small chamber through the nozzle outer ring, the nozzle blade trailing edge of the nozzle outer ring near the outlet of the conduit It is characterized in that a slope is formed in a downstream portion from the portion.
[0009]
The invention according to claim 3 is characterized in that a throat portion is formed between the nozzle outer ring near the outlet of the conduit and the steam guide. Furthermore, the invention according to claim 4 is characterized in that the outlet of the conduit is provided in a low pressure portion downstream of the slit, in the nozzle plate of the nozzle plate and at the inner end of the nozzle outer ring.
[0010]
Further, the invention according to claim 5 is characterized in that the outlet of the conduit is provided in the nozzle plate of the nozzle plate and at the outlet end of the nozzle plate.
[0011]
[Action]
In the invention according to each claim, an outlet for drain discharge that communicates with the passage in the nozzle outer ring in the lower half is provided in the axially rearward direction of the nozzle outer ring, so that the drain can be produced without processing the casing. Can be discharged to the outside.
[0012]
【Example】
FIG. 1 shows a reference example according to the present invention .
A discharge port 14 communicating with the passage 12 of the nozzle outer ring 5 in the lower half is provided on the downstream side in the axial direction of the nozzle outer ring 5. The drain 8 captured by the slit 10 passes through the hollow nozzle plate 9, passes through the passage 12 of the nozzle outer ring 5, and then flows in the direction of the exhaust chamber from the discharge port 14 provided on the downstream side of the nozzle outer ring 5 in the axial direction. To be discharged. As a result, the drain 8 is reliably removed without colliding with the blade 2.
[0013]
FIG. 2 shows an embodiment of the invention according to claim 1 . An opening 15 is provided in the steam guide 7 facing the discharge port 14 of the nozzle outer ring 5 in the lower half. The drain collides with the steam guide 7 from the discharge port 14 of the nozzle outer ring 5, but erosion can be eliminated by making an opening 15 at a place where erosion is likely to occur. Incidentally, it is easy to process the opening 15 in the steam guide 7 even in an existing steam turbine.
[0014]
FIG. 3 shows another reference example of the invention according to the present invention . A small chamber 16 communicating with the slit 10 is formed inside the nozzle plate 3, and a conduit 17 for connecting the drain from the lowermost portion of the small chamber 16 to the exhaust chamber through the nozzle outer ring 5 is connected.
[0015]
Drain adhering to the nozzle plate 3 enters the small chamber 16 through the slit 10. Due to the pressure distribution on the surface of the nozzle plate 3, the pressure at the outlet of the conduit 17 in the nozzle outer ring 5 is lower than the pressure at the portion with the slit 10, so that the drain extracted into the small chamber 16 is sucked through the conduit 17 toward the exhaust chamber. Is issued. Since the conduit 17 is connected to the lowermost part of the small chamber 16, all the drain that has entered the small chamber 16 is discharged by the conduit 17.
[0016]
FIG. 4 shows an embodiment of the invention according to claim 2 . A slope 18 is formed on the nozzle outer ring 5 near the outlet of the conduit 17. When the steam flow from the nozzle outlet toward the exhaust chamber flows along the slope 18, the static pressure at the outlet of the conduit 17 at the end of the slope 18 is lowered, and the conduit 17 helps drain out of the small chamber 16. ing.
[0017]
FIG. 5 shows an embodiment of the invention according to claim 3 . A throat portion 19 is formed between the nozzle outer ring 5 and the steam guide 7 in accordance with the outlet of the drain discharge conduit 17.
[0018]
That is, when the steam flows between the nozzle outer ring 5 and the steam guide 7 toward the exhaust chamber, the flow rate increases at the throat portion 19 and the static pressure near the outlet of the conduit 17 decreases. For this reason, the drain from the small room 16 can be discharged effectively.
[0019]
FIG. 6 shows an embodiment according to the fourth aspect of the present invention. The outlet 20 of the conduit 17 is provided at the inner end of the nozzle outer ring of the nozzle plate 3 at a lower pressure position downstream of the slit 10.
[0020]
The drain that has flowed out from the outlet 20 of the conduit 17 flows toward the exhaust chamber along the nozzle outer ring 5 while being pressed to the inside of the nozzle outer ring 5 by the high-speed steam flow passing through the nozzle plate 3.
[0021]
FIG. 7 shows an embodiment of the invention according to claim 5 . The outlet 20 of the conduit 17 is provided at the outlet end of the nozzle plate 3 inside the nozzle outer ring 5 of the nozzle plate 3.
[0022]
【The invention's effect】
As described above , according to the present invention, it is possible to complete the drain passage without newly modifying the passenger compartment, and it is possible to prevent the blades from being eroded in the existing steam turbine. is there.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing a reference example according to the present invention.
FIG. 2 is a longitudinal sectional view showing an embodiment according to the present invention.
FIG. 3 is a longitudinal sectional view showing another reference example according to the present invention.
FIG. 4 is a longitudinal sectional view showing another embodiment according to the present invention.
FIG. 5 is a longitudinal sectional view showing another embodiment according to the present invention.
FIG. 6 is a longitudinal sectional view showing another embodiment according to the present invention.
FIG. 7 is a longitudinal sectional view showing another embodiment according to the present invention.
FIG. 8 is a longitudinal sectional view of a conventional steam turbine.
FIG. 9 is a longitudinal sectional view showing an example of a drain discharge device according to the prior art.
FIG. 10 is a cross-sectional view showing another example of the drain discharge device according to the prior art.
[Explanation of symbols]
4 Nozzle inner ring 5 Nozzle outer ring 7 Steam guide 9 Hollow nozzle plate 10 Slit 11, 12 Passage 14 Discharge port 16 Small chamber 17 Conduit 19 Throat part 20 Exit

Claims (5)

In order to guide water droplets moving on the outer surface of the nozzle through the slit to the passage of the outer ring of the nozzle and discharge it as drain ,
A through hole communicating with the passage is provided in the nozzle outer ring,
In the steam turbine drain discharge device, the drain extracted from the slit is directly led to the exhaust chamber through the through hole .
A steam turbine drain discharge device characterized in that a hole is formed in a steam guide in a front portion of the nozzle outer ring facing the through hole and drain is discharged to the outside of the steam guide . In order to guide the water droplets moving on the outer surface of the nozzle through the slit to the nozzle outer ring passage and discharge it as drain to the outside,
Forming a small chamber communicating with the slit in the nozzle plate constituting the nozzle;
In a steam turbine drain discharge device connected to a conduit for leading drain from the lowermost part of the small chamber to the exhaust chamber via the nozzle outer ring,
A drain discharge device for a steam turbine, wherein a slope is formed in a downstream portion of a nozzle blade rear edge portion of the nozzle outer ring near the outlet of the conduit. The drain discharge device according to claim 2,
A steam turbine drain discharge device, wherein a throat portion is formed between the nozzle outer ring and a steam guide near the outlet of the conduit. The drain discharge device according to claim 2,
A steam turbine drain discharge device characterized in that an outlet of the conduit is provided in a low-pressure portion in the nozzle plate of the nozzle plate and on the inner end of the nozzle outer ring and downstream of the slit. The drain discharge device according to claim 4,
A drain discharge device for a steam turbine, wherein an outlet of the conduit is provided in a nozzle plate of the nozzle plate and at an outlet end of the nozzle plate.

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