JPH06307203A - Turbine nozzle box - Google Patents

Abstract

PURPOSE:To correct the circumferential excessive unbalane of the distribution of the flow rate to flow in a moving blade from a ring-like steam passage through a stationary blade, and also to decrease flow loss caused by collision of the flow to directly flow in from the steam inlet pipe against the flow to be carried over from an adjacent ring-like steam passage. CONSTITUTION:In a turbine nozzle box 1 for guiding steam to flow in from a steam inlet pipe 2 to governor stationary blades 4 through a ring-like steam passage 3, a plurality of partition plates 20a, 20b, 20c whose axial lengthes are gradually larger toward the horizontal joint side from the steam inlet pipe corresponding part at the distance where they are circumferentially separated by at least two pitches or more are arranged on the upstream side of the governor stationary blade 4 in the ring-like steam passage 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turbine nozzle box installed in a steam turbine.

[0002]

2. Description of the Related Art FIGS. 3 to 5 show a conventional turbine nozzle box, and FIG. 3 is an external sectional view showing an upper half of the box.
FIG. 5 is a cross-sectional view of the ring-shaped steam passage of the turbine nozzle box of FIG. 3, and FIG. 5 is a diagram showing FIG.

In FIGS. 3 to 5, high-pressure, high-temperature steam supplied from a boiler is introduced into a ring-shaped steam passage 3 through a steam inlet pipe 2 of a turbine nozzle box 1 and is then adjusted by a blade row. It is configured to flow through a speed-control vane 4 and into a speed-control blade (not shown).

[0004]

The conventional turbine nozzle box described above has the following problems. That is, the speed control vanes 4 are generally arranged in the same profile at equal pitches in the circumferential direction. On the other hand, the steam inlet pipe 2 is installed vertically.
The ring-shaped steam passage 3 having the same cross-sectional shape in the circumferential direction except the connection portion with the steam inlet pipe 2 has a passage 5 in the circumferential direction in the upper side (or lower side) of the nozzle box.
It is roughly divided into a steam inlet pipe equivalent passage 6 and a horizontal joint side passage 7. The uppermost portion and the most horizontal joint portion are fixed walls, and no fluid flows in or out. The flow 8 of the steam inlet pipe 2 is branched into the above-mentioned three passages 5, 6 and 7 in the ring-shaped steam passage 3, and flows into the moving blades through the stationary blades 4, respectively.

In this case, in the flow 9 of the passage 6 corresponding to the steam inlet tube, the distance between the steam inlet tube 2 and the stationary blade 4 is the shortest and both are facing each other, and the flow resistance is small, so that the flow 9 passes through the stationary blade 4. Flow rate to the rotor blades is highest. On the other hand, in the flow 10 in the horizontal joint side passage 7, the flow 11 that directly flows in from the steam inlet pipe 2 has a large distance to the stationary blade 4 because it is not directly facing, and thus has a large flow resistance. The flow rate is large and the flow rate flowing out of the stationary blades 4 in this region is small. Furthermore, even in the flow of the steam inlet pipe equivalent passage 6,
There is a flow 12 that does not flow into the adjacent horizontal passage 7 on the horizontal joint side and flows out. Then, the carryover flow 12 collides with the flow 11 directly flowing from the steam inlet pipe 2 at a high speed, so that a flow loss occurs.

As described above, in the turbine nozzle box having the speed control vanes 4 having the same profile and arranged at equal pitches in the circumferential direction, the flow rate flowing out of the vanes 4 is largely unbalanced in the circumferential direction and flows. Since the loss is large, there is a problem that the performance and reliability of the turbine are adversely affected as a result of reducing the fluid performance of the speed control stage and increasing the excitation force.

The present invention has been made to solve the above-mentioned problems of the prior art, and is an excessive circumferential unbalance of the flow distribution flowing from the ring-shaped steam passage to the moving blades through the stationary blades. It is an object of the present invention to provide a turbine nozzle box in which the flow loss due to the collision between the flow that directly flows in from the steam inlet pipe and the flow that carries over from the adjacent ring-shaped steam passage is reduced.

[0008]

In order to solve the above problems, the present invention relates to a turbine nozzle box in which steam flowing from a steam inlet pipe is guided to a speed control vane through a ring-shaped steam passage. A plurality of partition plates whose axial length gradually increases from the steam inlet pipe equivalent portion toward the horizontal joint side at intervals of at least 2 pitches in the circumferential direction at the upstream side of the speed control vane in the steam steam passage. It was installed.

[0009]

According to the above-mentioned means, in the ring-shaped steam passage of the turbine nozzle box, the flow of the steam inlet pipe equivalent passage is separated from the flow directly flowing into the stationary blade by the partition plate on the horizontal joint side. It is branched into a flow that carries over to the horizontal joint side passage adjacent to the passage corresponding to the steam inlet pipe. Therefore, in the horizontal joint-side ring-shaped steam passage adjacent to the steam inlet pipe equivalent passage, the flow directly flowing from the steam inlet pipe and the carryover flow from the steam inlet pipe equivalent passage merge. Then, the combined flow flows into the moving blade through the stationary blade. Further, also in the ring-shaped steam passage closest to the horizontal joint, the flow that directly flows in from the steam inlet pipe and the flow that carries over the partition plate merge. Then, the combined flow flows into the moving blade through the stationary blade.

[0010]

Embodiments of the present invention will be described in detail below with reference to FIGS. FIG. 1 is a view showing an embodiment of a turbine nozzle box according to the present invention, FIG. 2 is a sectional view of a ring-shaped steam passage thereof, and FIG. 1 shows FIG. 2 expanded into a cylindrical surface at the same radial position. There is something. In FIGS. 1 and 2, the same parts as those shown in FIGS. 3 to 5 are designated by the same reference numerals, and the duplicated description will be omitted.

As shown in FIGS. 1 and 2, according to the present invention, at least two pitches apart in the circumferential direction are provided upstream of the speed control vanes 4 in the ring-shaped steam passage 3 of the turbine nozzle box 1. A plurality of partition plates 20 (20a, 20b, 20c) whose axial length gradually increases from the steam inlet pipe equivalent portion toward the horizontal joint side are installed.
These partition plates 20 are formed so as to be fluidly and smoothly integrated with the stationary blades 4. Further, structurally, the partition plate 20 and the stationary blade 4 may be separate bodies, or may be a structure having a blade profile shape in which the axial length is integrated and is larger than that of other general stationary blades. .

Such partition plates 20a, 20b, 20c
By installing, in the ring-shaped steam passage 3 of the turbine nozzle box 1, the flow of the steam inlet pipe equivalent passage 6 directly flows into the vane 4 and the partition plates 20a and 20b closer to the horizontal joint. It is partitioned and branched into a flow 12a that carries over to the horizontal joint side ring-shaped steam passage 7a adjacent to the steam inlet pipe equivalent passage 6. Therefore, in the horizontal joint side ring-shaped steam passage 7a adjacent to the steam inlet pipe equivalent passage 6, the flow 11a flowing directly from the steam inlet pipe 2 and the carryover flow 12a from the steam inlet pipe equivalent passage 6 are formed. Join. Then, the combined flow 10a flows into the moving blade through the stationary blade 4.
Further, also in the ring-shaped steam passage 7b closest to the horizontal joint, the flow 11b that directly flows in from the steam inlet pipe 2 and the flow 12b that carries over the partition plate 20b merge. Then, the combined flow 10b flows into the moving blade through the stationary blade 4.

In this case, since the ring-shaped steam passage 7b closest to the horizontal joint is partitioned by the partition plates 20b and 20c, the flow 11b directly flowing from the steam inlet pipe 2 can be properly captured. Further, the flow 12b that carries over the partition plate 20b from the horizontal joint side ring-shaped steam passage 7a adjacent to the steam inlet pipe equivalent passage 6 is also captured, and the merge 10
b, the flow rate that flows through the stationary blades 4 in this region into the moving blades increases. Further, since the amount of carryover is appropriately limited by the partition plate 20b, the flow loss due to the collision with the flow 11b directly flowing from the steam inlet pipe 2 into the ring-shaped steam passage 7b on the horizontal joint side is reduced.

[0014]

As described above, according to the present invention, in the turbine nozzle box in which the steam flowing from the steam inlet pipe is guided to the speed control vanes through the ring-shaped steam passage, the adjustment in the ring-shaped steam passage is performed. By installing a plurality of partition plates, the axial length of which gradually increases from the steam inlet pipe equivalent portion toward the horizontal joint side at least at intervals of 2 pitches or more in the circumferential direction, on the upstream side of the speed vane, Corrects an excessive circumferential unbalance in the flow distribution flowing from the ring-shaped steam passage through the vanes to the moving blade, and also causes carry-over from the ring-shaped steam passage adjacent to the flow directly flowing from the steam inlet pipe. It is possible to reduce the flow loss due to the collision with the incoming flow, thereby improving the performance of the speed control stage and reducing the excitation force.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a turbine nozzle box according to the present invention by developing FIG. 2 on a cylindrical surface at the same radial position.

2 is a cross-sectional view of a ring-shaped steam passage of the turbine nozzle box of FIG.

FIG. 3 is an external sectional view showing an upper half of a conventional turbine nozzle box.

4 is a cross-sectional view of a ring-shaped steam passage of the turbine nozzle box of FIG.

5 is a diagram showing FIG. 4 developed on a cylindrical surface at the same radial position. FIG.

[Explanation of symbols]

 1 Turbine Nozzle Box 2 Steam Inlet Pipe 3 Ring Steam Passage 4 Stator Blade 5 Nozzle Box Upper Side Passage 6 Steam Inlet Pipe Equivalent Passage 7a, 7b Horizontal Joint Side Passage 20, 20a, 20b, 20c Partition Plate

Claims (1)

[Claims] 1. A turbine nozzle box in which steam flowing from a steam inlet pipe is guided to a speed control vane through a ring-shaped steam passage, at least in a circumferential direction at an upstream side of the speed control vane in the ring-shaped steam passage. A turbine nozzle box, characterized in that a plurality of partition plates whose axial length gradually increases from the steam inlet pipe equivalent portion toward the horizontal joint side at intervals of two pitches or more are provided.