JPS5848703A - Row of stator blade of turbine - Google Patents

Abstract

PURPOSE:To make the deformation of the row of stator blades of a turbine due to difference of pressure uniform and reduce the leakage loss of an operating fluid by providing long nozzle blades having large rigidity in the vicinities of divided parts of partition plates of the row of the stator blade and short nozzle blades having small friction loss at other parts of the row. CONSTITUTION:An outer partition plate 2a is divided into two parts on surfaces 2c and an inner partition plate 2b on surfaces 2d. Three long nozzle blades 3b having high rigidity are provided only in the vicinity of the divided surfaces and short nozzle blades 3a having a small friction resistance are provided at other remaining parts. By this arrangement, the axial deformation due to vapor pressure in the row of stator blades is made uniform, and gaps of respective parts between the row of stator blades and the row of rotary blade can be made small. Accordingly, the leakage loss of the operating fluid can be reduced, and the function of the turbine can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a two-part turbine stationary blade row.

In axial flow turbomachines such as steam turbines and other gas turbines, as is well known, a stage is composed of a stationary blade row serving as a stationary part and a rotary blade row serving as a rotating part. That is, these are housed in a turbine casing, and the high-temperature, high-pressure working fluid from outside, such as a boiler, is guided by nozzle blades installed in a stationary blade row and sprayed at high speed onto the rotor blades of the rotary blade row. The row is rotated, and the working fluid that has passed through this rotary blade row is transmitted to the next stage, and the thermal energy of the working fluid is sequentially converted into mechanical work.

Since the stationary blade row and the rotary blade row have a relationship between the stationary body and the rotating body, they require a certain amount of clearance for their operation, but the working fluid leaking from these gaps does no work. Therefore, it is necessary to keep this gap as small as possible.

However, in reality, the stationary blade row deforms downstream due to the pressure difference before and after it, so the gap mentioned above was set with this deformation in mind, and in the past, this deformation was uneven and large. , the gap is large, and therefore leakage losses are large, leading to a decrease in turbine efficiency.

This will be explained in detail with reference to the figures. Figure 1 is an axial sectional view showing the stage structure of a steam turbine, and (a) in Figure 2
is a PP arrow view in Figure 1, and (b) is an A-A view in (a).
FIG. The stationary blade row 1 includes an outer frame partition plate 2a, an inner partition plate 2b, and an outer frame partition plate 2b.
, 2a, and is composed of a plurality of nozzle blades 3 and packing 4, which are respectively connected to the two, and the outer periphery of the stationary blade row, that is, the outer periphery 1a of the outer cutting plate 2a, is connected to the turbine cane. It is fixed to the inner wall of the housing with a structure that can accommodate thermal expansion. In addition, as shown in Figure 2 (a), the stationary blade row 1 has 20 outer rod partition plates and 2 inner partition plates for maintenance and inspection purposes.
Divided into two by the d plane, the whole is 2 c -2d -2d
It is divided into two parts by the -2d plane. On the other hand, the rotor blade row 5 includes a rotor blade 6, a shroud 7 connected thereto, and a rotor disk 8.
The rotor blades 6 receive high-temperature, high-pressure steam blown from the direction B through the nozzle blades 3 of the stationary blade row 1, and rotate around center #5a (the turbine (The casing and bearings are not shown.)

Between the stationary blade row 1 and the rotary blade row 5, the outer cutting plate 2a is provided.
The rotor blade tip gap 9a between the side surface and the side surface of the shroud 7, the rotor blade root gap 9b1 between the side surface of the internal partition plate 2b and the root in'' 6a of the rotor blade 6, and the gasket fin 4 of the gasket 4.
A packing gap 9C is formed between the rotor disk 80 and the side surface of the rotor packing groove 8a. Since these gaps are affected by the deformation of the stationary blade row 1, the stationary blade row 1 must have a highly rigid structure in order to reduce this deformation.

However, as described above, the stationary blade row 1 is composed of the outer rod partition plate 2a, the inner partition plate 2b, and the plurality of nozzle blades 3 located between them and connected to both.
The rigidity of the stationary blade row 1 has a large influence on the rigidity of the stationary blade row 1. On the other hand, the rigidity of the nozzle blade 3 is as shown in FIG. 3(b), and the blade width is as shown in FIG. 3(a)! However, on the other hand,
As the blade surface area increases, friction losses increase and reduce the efficiency of the turbine. For this reason, conventionally, as shown in Figure 2,
Short nozzle blades 3a with low friction loss and long nozzle blades 3b with high rigidity were used in alternate combination.

However, in this conventional method, although highly rigid long nozzle blades 3b are arranged evenly on the circumference and relatively frequently used, as shown by the dashed dotted line 1°2 in FIG. 5(a), The deformation, that is, the displacement δ of the end of the inner peripheral surface of the inner partition plate 2b is not uniform and large.゛In particular, the dividing plane 2 c of the stationary blade row
-2d -2d The deformation near -2C is large. That is,
In conventional stationary blade rows, the gap with the rotary blade row is set based on this maximum deformation, so this gap is large, resulting in large steam leakage losses and a decrease in turbine performance. Ta.

The purpose of the present invention is to eliminate the above-mentioned drawbacks, to uniformly reduce the deformation of the stationary blade row, to reduce the gaps between each part of the stationary blade row, and to minimize the use of long nozzle blades that cause large friction loss. An object of the present invention is to provide a turbine stationary blade row with improved turbine performance.

To achieve this objective, the turbine stationary blade cascade according to the present invention replaces the conventional arrangement of long and short nozzle blades evenly arranged on the circumference, with long and rigid nozzle blades arranged only in the vicinity of the dividing plane where the deformation is most severe. In addition to the nozzle blades, the other parts are composed of short nozzle blades with low friction loss, and the structure is such that the deformation of the turbine stationary blade row due to the pressure difference before and after is made uniform. be.

Hereinafter, one embodiment of the present invention will be described based on the drawings. In this embodiment, the configuration of the stationary blade row is basically the same as the one described above, only the arrangement of the nozzle blades is different.
The configuration will be explained using FIG. 1 mentioned above, and the arrangement of the nozzle blades will be explained based on FIG. 4 showing one embodiment of the present invention. In addition, in FIG. 1, FIG. 2, and FIG. 4, the same reference numerals indicate the same or the same equivalent parts. - As shown in FIG.
The stationary blade row 1 is composed of a plurality of nozzle blades 3 and a gasket 4 arranged between the inner and outer partition plates 2b and 2a and connected to both. The outer periphery, that is, the outer periphery 1a of the outer cutting plate 2a is fixed to the inner wall of the turbine casing (not shown) in a structure that can accommodate thermal expansion. For maintenance and inspection, the stationary blade row 1 is divided into two parts, as shown in FIG. -2d-2d Divided into two by the 2C plane.

In the arrangement of the long and short nozzle blades, as shown in FIG. 4, the highly rigid long nozzle blades 3b are not arranged evenly on the circumference, and the above-mentioned dividing plane 2C- 2d
-2d Three blades are arranged only near -2C, and short nozzle blades 3a with low frictional resistance are arranged in the remaining part. As shown in FIG. 3 or 4, the long nozzle blade 3b has a shape formed by extending the short nozzle blade 3a toward the upstream side. Therefore, the rigidity near the dividing plane, where conventionally the deformation was greatest and lacked rigidity, was strengthened, while the rigidity of the middle part, where conventionally the deformation was small, was relaxed, so the deformation of the stationary blade row l was averaged out. That is, as shown by the solid line 13 in FIG. 5(a), the displacement δ of the end of the inner circumferential surface of the internal partition plate 2b is almost uniform at every point on the circumference, and its value is greater than that of the conventional example in the same figure. This is considerably smaller than the maximum value shown by point @Gen12. Therefore, since the gaps 9a, gb, and gC between the stationary blade row and the rotary blade row shown in FIG. It is possible to improve the performance of the turbine. In addition, since only three long nozzle blades 3b, which have a large steam friction loss, are used near the dividing surface, the usage ratio 2 of the long nozzle blades becomes relatively small, reducing friction loss and improving turbine performance. can be further improved.

FIG. 6 shows the arrangement of nozzle blades in another embodiment of the present invention. This embodiment differs from the previous embodiments in that the long nozzle blades are not integrated, and the long nozzle blades 3b
', a nozzle blade 3a' having the same shape as the short nozzle blade 3a,
It is constructed from a fixing plate 14 provided separately from this nozzle blade 3 a on the upstream extension line thereof. Since this combination of the nozzle blade 3a' and the fixed plate 14 has almost the same rigidity as the long nozzle blade 3b of the integral structure, the same functions and effects as described above can be achieved in this embodiment as well. . Furthermore, in this embodiment, there is no need for two types of long and short nozzle blades with complicated shapes, and only the short nozzle blade 3a, the nozzle blade 3a/ having the same shape, and the fixing plate 14 with a simple shape are prepared. This is advantageous not only in terms of production but also in terms of maintenance management.

As explained above, in the turbine stationary blade row according to the present invention, the deformation in the axial direction due to the working fluid such as steam pressure is uniformized and small, so the gaps between each part of the stationary blade row and the rotary blade row are set small. be able to. Therefore, the leakage loss of working fluid such as steam is small, and the ratio of use of the long nozzle blades, which have a large friction loss, can be reduced, so that the performance of the turbine can be further improved.

[Brief explanation of the drawing]

Figure 1 is an axial sectional view of a steam turbine stage, Figure 2 (a
) is a PP arrow view in Figure 1, and (b) is a view A- in Figure (a).
The conventional example is shown in a cross-sectional development view along arrow A, and Fig. 3 (a
) shows the nozzle blade shape, (b) shows the relationship between the nozzle blade span, its rigidity, and friction loss, FIG. 4 shows an embodiment of the present invention, and (a) and (b) respectively Figure 2 (a). (b) A drawing corresponding to FIG. 5, (a) is a comparison diagram of the modification in the conventional example shown in FIG. 2 and the modification in the embodiment shown in FIG. Figure 6 shows the actual deformation measurement points in the arrow view, and Figure (C) shows the E-E cross-sectional view taken along each plane E-E in the radial direction of Figure (1)) and its deformation. FIG. 5 is a diagram corresponding to FIG. 4 in another embodiment of the invention; l... Turbine stationary blade row, 1a... Outer periphery, 2a...
・Outer rod cutting plate, 2b...inner partition plate, 2cm2d-2d-
2c...Divided surface, 3...Nozzle blade, 3a...Short nozzle blade, 3a/...Nozzle blade with the same shape as the short nozzle blade, 3b. Happy 1st figure - 2nd mouth (Q-) j$3 figure (Itton (t) 4th hindrance ((1) (b)

Claims (1)

[Claims] 1. Consisting of an outer partition plate, an inner partition plate, and a plurality of nozzle blades disposed between the two and connected to the two, the outer periphery of the outer partition plate is attached to the inner wall of the turbine casing. In a stationary turbine blade row that is divided into two parts, long nozzle blades are arranged near the dividing surface, and the other part is composed of short nozzle blades, so that the pressure difference between the front and rear A turbine stationary blade row characterized in that the turbine stationary blade row has a structure that uniformizes deformation of the turbine stationary blade row. 2. The turbine stationary blade row according to claim 1, wherein the long nozzle blade has a shape formed by extending the short nozzle blade toward the upstream side. 3. The long nozzle is comprised of a nozzle blade having the same shape as the short nozzle blade, and a fixing plate disposed on an upstream extension of the nozzle blade. Turbine stationary blade row.