JPS643761Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to stator blades of steam turbines, etc., and in particular,
The present invention relates to an improvement in a grooved stationary blade that can effectively remove condensate from the blade surface.

Generally, in a turbine stage, a working fluid such as high-temperature, high-pressure steam flows in through stator vanes, and the stator vanes convert the thermal energy of the working fluid into velocity energy to create a high-speed working fluid, which is then transferred to the rotor blades. The rotor blades are rotated by an impulse action or a combination of an impulse action and a reaction action of the working fluid caused by a change in momentum.

By the way, as shown in FIGS. 1 and 2, a ring material 22 is attached to the stationary blade 1 of a conventional steam turbine, and the ring material 2 is supported at a predetermined position of a casing (not shown). ing.

The steam passes through the passage formed in the stationary blade 1 and then hits the rotor blade (not shown), giving rotation to the rotor blade.While passing through the steam passage, the steam turns into water droplets, which grow. The flow velocity decreases, and in the stator blade 1, the minute water droplets that mainly accumulate on the ventral surface become a water film flowing in the mainstream direction on the blade surface, gather at the trailing edge of the blade, and finally become coarse water droplets that flow into the steam mainstream again. Then, the liquid collides with the rotor blades rotating at high speed, causing a phenomenon called drain attack or drain erosion.

In order to reduce the above-mentioned erosion, grooves 3 are provided on the vane surface as shown in Figs. 1 and 2 for the purpose of removing condensate from the stator vane in the state of water film accumulated on the vane surface. There is. The water film collected in the groove 3 receives a driving force from the mainstream steam due to the arrangement of the groove, which is not perpendicular to the mainstream, but is slightly inclined, and is transferred to the ring material 2 provided on the outer periphery of the blade. The steam collects at the exhaust port 4, and is discharged from there to the outside of the turbine stage using the steam differential pressure.

However, the above-mentioned conventional stator vanes have the following drawbacks.

(1) Since the groove 3 requires a certain depth, it must be provided not near the trailing edge of the blade, which is a desirable location, but rather far upstream and in a location where the blade is sufficiently thick. Therefore, not enough water film can be collected, so drain attack still occurs.

(2) In order to effectively move the water film collected in the groove 3 to the outer circumference of the blade, the opening width of the groove 3 must be sufficiently large, and the opening width should be several tens of times the water film thickness. It is normal to have one. Therefore, there is a concern that the blade profile loss will increase.

(3) In view of the flow of the water film collected in the groove 3, the cross-sectional area of the groove needs to increase toward the outer periphery of the stator blade 1, and the ring material 2 is arranged at an angle. Therefore, it is difficult to make the groove 3 deeper toward the outer periphery. Furthermore, it is not easy to change the groove width due to the reason (2) above.

The present invention aims to improve the above-mentioned drawbacks, and its purpose is to provide a grooved stationary blade that can effectively remove condensate from the blade surface.

In order to achieve the above object, the present invention forms the drain discharge groove with a thin plate separate from the blade material, and sets the opening of the groove separately from the groove without forming a protrusion on the blade surface. It is characterized by being constructed so that it can be wetted.

Hereinafter, embodiments of a stator blade for a steam turbine according to the present invention will be described with reference to FIGS. 3 and 4.

In FIGS. 3 and 4, a ring material 2 is attached to the outer periphery of the stator blade 1, and a separate thin plate 11 is glued to the back of the trailing edge of the stator blade 1 material, and one end of the thin plate 11 Another thin plate 12 is attached to the front side of the trailing edge of the blade, and an adhesive part 13 is formed on the trailing edge of the stationary blade using silver solder or the like. An opening 14 is formed between the front surface of the trailing edge of the wing material and the other end of the thin plate 12 opposite to the end of the bonded portion 13. As a result, a groove 16 is formed between the thin plates 11 and 12 to serve as a passage for transporting the collected drain.
This groove 16 extends toward the ring material 2 and communicates with a discharge port 4 provided in the ring material 2.

If necessary, an intermediate support 1 may be placed between the thin plates 11 and 12.
It is also possible to provide 5.

Next, regarding the function of the grooved stator vane configured as described above, the water film flowing along the stator vane surface gathers at the opening 14. Here, between the steam at the opening 14 and the steam near the outlet 4, the steam near the outlet 4 has a lower pressure, so the water film collected at the opening 14 enters the groove 16. It flows along the drain and becomes drain and is discharged from the discharge port 4.

The configuration as described above provides the following effects.

(1) Since the groove 16 is formed by the thin plates 11 and 12, the groove opening 14 can be set sufficiently close to the rear end of the stator blade regardless of the groove depth.

(2) Since the opening 14 can be made narrower to the same extent as the water film thickness, the opening 14 is narrower than the groove 16.
area becomes sufficiently small, and therefore, the low pressure at the outlet 4, which is the source of the differential steam pressure for discharging, will be traced back to the groove 16, and the water film will flow through the opening 14 due to the differential pressure of the steam. In addition to being actively sucked, there is no need to incline the groove with respect to the mainstream, which was required in the past.

(3) The groove 16 which becomes the drain discharge passage is formed by the thin plates 11 and 1.
2, the groove 16 is selected from the thin plate 1.
You can set relatively freely by selecting 1 and 12,
Thereby, the opening 14 can be set separately and independently from the groove 16.

(4) Since the drain discharge part does not protrude from the blade surface, the drain discharge part can remove the drain without disturbing the fluid flow and reducing the performance of the stationary blade.

As described above, according to the present invention, drain can be effectively removed without deteriorating the performance of the stator blade, and maintenance is reduced because drain attack does not occur.

In addition, the present invention is not limited to the embodiment using the steam turbine described above and shown in the drawings, but can of course be implemented by appropriately modifying it to a gas turbine or a rotating machine without departing from the scope of the invention. be.

[Brief explanation of drawings]

Figure 1 is a front view of a conventional steam turbine stationary blade.
2 is a sectional view taken in the - arrow direction of FIG. 1, FIG. 3 is a front view of a stationary blade of the steam turbine of the present invention, and FIG. 4 is a sectional view taken in the - arrow direction of FIG. 3. 1... Stationary blade, 2... Ring material, 4... Discharge port,
11, 12...Thin plate, 13...Adhesive part, 14...
Opening portion, 15... intermediate support member, 16... groove.

Claims (1)

[Scope of utility model registration request] In a stationary blade with a drain discharge groove provided on the trailing edge of the blade, the groove is formed of a thin plate separate from the blade material, and the opening of the groove is set independently of the groove without forming a protrusion on the blade surface. A grooved stator blade that is characterized by the ability to