JPH0674001A - Governor stage nozzle of steam turbine - Google Patents

Abstract

PURPOSE:To stop the installation of a strut on the upper course of a nozzle piece row for obviating pressure loss and disturbance of steam flow and reducing secondary flow loss between the nozzle pieces. CONSTITUTION:The governor stage nozzles of a steam turbine is composed of a plurality of nozzle pieces 21 having small blade width and a plurality of nozzle pieces 22 having small curvature in the front half part of the upper course and large blade width. Besides, at least a nozzle piece 21 having a small blade width is disposed between the nozzle pieces 22 having the large blade width.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speed control nozzle for a steam turbine.

[0002]

2. Description of the Related Art Conventionally, there are an assembly type nozzle and a welding type nozzle as a speed control nozzle of a steam turbine.

FIG. 2 is a vertical cross-sectional view showing a conventional assembly type nozzle. A plurality of nozzle pieces 1 constituting the nozzle are fitted into an outer wall 2 and an inner wall 3, respectively, and a reinforcement is still provided on the upstream side of the nozzle piece row. A plurality of supporting columns 4 are arranged to form an outer wall 2 and an inner wall 3.
It is welded to. Then, as shown in the cross-sectional view of FIG. 3, the steam 5 expands by passing through the flow passage defined by the plurality of nozzle pieces 1, and flows into a blade row (not shown).

Next, FIG. 4 is a longitudinal sectional view showing a conventional welding type nozzle. A plurality of nozzle pieces 11 constituting the nozzle are welded to an outer wall 12 and an inner wall 13, respectively, and the nozzle piece 1 is formed.
1 has a large wing width and also serves as a pillar. Then, as shown in the cross-sectional view of FIG. 5, the steam 14 expands by passing through the flow passage defined by the plurality of nozzle pieces 11, and flows into a blade row (not shown).

[0005]

By the way, in the conventional steam turbine speed control stage nozzle described above, as shown in FIGS.
In the conventional assembly type nozzle shown in FIG. 2, since the nozzle piece 1 has a small blade cross-sectional area, it is weak in strength to support the outer wall 2 and the inner wall 3. Therefore, the column 4 is provided separately from the nozzle piece 1. However, the column 4 obstructs the steam flow 5 and causes pressure loss, and also disturbs the steam flow 5 flowing into the nozzle piece row, which causes a problem of loss.

On the other hand, in the conventional welding type nozzle shown in FIGS. 4 and 5, the blade is enlarged by increasing the blade width so that the nozzle piece 11 also has a function as a support for supporting the outer wall 12 and the inner wall 13. Since the welded nozzle piece 11 has a larger blade width than the above-described assembled nozzle piece 1 due to the increased cross-sectional area and the increased strength, there is a problem that the secondary flow loss increases. It was

The present invention has been made in order to solve the above-mentioned problems of the prior art, and stops the installation of the column on the upstream side of the nozzle piece row to eliminate pressure loss and turbulence of the steam flow, and It is an object of the present invention to provide a speed-control stage nozzle for a steam turbine in which the secondary flow loss generated between the one side is reduced.

[0008]

In order to solve the above problems, the present invention provides a speed control nozzle for a steam turbine comprising a plurality of nozzle pieces, wherein the nozzle pieces are a plurality of nozzle pieces having a small blade width. And a plurality of nozzle pieces each having a large blade width and having a small curvature in the upstream front half portion, and at least one nozzle piece having a small blade width is arranged between the nozzle pieces having a large blade width.

[0009]

According to the above means, since there is no column other than the nozzle piece, pressure loss and turbulence of the steam flow due to the column are eliminated, and the loss is reduced. Further, since the interval between the nozzle pieces having the large blade width becomes large, the secondary flow loss generated between the nozzles having the large blade width is reduced.

Further, since the upstream half of the nozzle piece having a large blade width has a small curvature, the acceleration of the steam flow on the back side and the ventral side of the upstream half of the nozzle piece having a large blade width can be suppressed to a low level. In the latter half of the nozzle piece, all the flow paths have substantially the same inflow condition, so that the nonuniformity of the vapor flow due to the mixture of the nozzle pieces having different shapes can be suppressed to a low level.

[0011]

An embodiment of the present invention will be described in detail below with reference to FIG. FIG. 1 is a cross-sectional view showing an embodiment of a steam turbine speed control stage nozzle according to the present invention.

In FIG. 1, the speed-control stage nozzle of the steam turbine has a plurality of nozzle pieces 21 having a small blade width and a plurality of blade pieces having a large blade width, for example, about twice the blade width of the nozzle piece 21. The nozzle piece 22 has a large blade width, and the upstream half of the nozzle piece 22 has a small curvature.
At least one (two in this embodiment) nozzle piece 21 having a small blade width is provided between the nozzle pieces 22 having a large blade width.
Are arranged.

Although the nozzle piece 21 having a small blade width may be of the assembly type and the nozzle piece 22 having a large blade width may be of the welding type, the invention is not limited to this.

According to the structure of the steam turbine speed control stage nozzle described above, since there is no support column different from the nozzle pieces 21 and 22, a comparison with the conventional assembly type nozzle shown in FIGS. Since there is no pressure loss or steam flow disturbance due to the columns,
Loss is reduced. Moreover, since the interval between the nozzle pieces 22 having a large blade width becomes large, the secondary flow loss generated between the nozzle pieces 22 having a large blade width is reduced.

Since the upstream front half of the nozzle piece 22 having a large blade width has a small curvature, the steam flow 23 is accelerated on the back side and ventral side of the upstream front half of the nozzle piece 22 having a large blade width. Since the flow rate is suppressed to a low level, and in the latter half of the nozzle piece, all the flow paths have substantially the same inflow condition, so that the nonuniformity of the vapor flow due to the mixture of nozzle pieces having different shapes can be suppressed to a low level.

[0016]

As described above, according to the present invention, in a speed control stage nozzle of a steam turbine comprising a plurality of nozzle pieces, the nozzle piece is composed of a plurality of nozzle pieces having a small blade width and an upstream first half. Installation of stanchions by configuring with a plurality of nozzle pieces with large blade width with a small curvature of part, and arranging at least one nozzle piece with small blade width between nozzle pieces with large blade width It is possible to stop the pressure loss and the turbulence of the steam flow, and reduce the secondary flow loss generated between the nozzle pieces having a large blade width. Further, the nonuniformity of the steam flow due to the mixing of nozzle pieces having different shapes can be suppressed to a low level by reducing the curvature of the upstream front half of the nozzle piece having a large blade width.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a steam turbine speed control stage nozzle according to the present invention.

FIG. 2 is a vertical cross-sectional view showing an example of a conventional steam turbine speed control stage nozzle.

3 is a cross-sectional view of the speed control stage nozzle of FIG.

FIG. 4 is a vertical cross-sectional view showing another example of a conventional steam turbine speed control stage nozzle.

5 is a cross-sectional view of the speed control stage nozzle of FIG.

[Explanation of symbols]

 21 Nozzle piece with small blade width 22 Nozzle piece with large blade width 23 Steam flow

Claims (1)

[Claims] 1. A steam turbine speed-control stage nozzle comprising a plurality of nozzle pieces, the nozzle pieces comprising a plurality of nozzle pieces having a small blade width, and a plurality of blade pieces having a small upstream side half and a large blade width. And a nozzle piece having a small blade width, and at least one nozzle piece having a small blade width is disposed between the nozzle pieces having a large blade width.