JP4107766B2 - Steam turbine exhaust system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a structure of an exhaust passage in a casing of a high-pressure turbine or an intermediate-pressure turbine in a steam turbine , and more particularly to an exhaust device of a steam turbine provided with exhaust flow guide means.
[0002]
[Prior art]
FIG. 2 is a cross-sectional view of a main part along a turbine rotor axial center line of a high- and medium-pressure turbine in which a high-pressure turbine and an intermediate-pressure turbine are provided in a common outer casing and inner casing.
[0003]
In FIG. 2, 30 is a high-pressure turbine, 40 is an intermediate-pressure turbine, 1 is an outer casing, 2 is an inner casing, and the high-pressure turbine 30 and the intermediate-pressure turbine 40 are provided in the common outer casing 1 and inner casing 2. It has been.
11 'is a main steam inlet for introducing main steam to the high-pressure turbine 30, 6 is a high-pressure exhaust port from which high-pressure exhaust from the high-pressure turbine 30 is led, and 7 is reheated steam from a boiler (not shown). A reheat steam inlet 8 for introduction into the intermediate pressure turbine 40 and an intermediate pressure outlet 8 through which intermediate pressure exhaust from the exhaust from the intermediate pressure turbine 40 is derived.
[0004]
Reference numerals 5 and 4 denote high-pressure stationary blades and high-pressure moving blades that constitute the high-pressure turbine 30, and 11 and 12 denote intermediate-pressure stationary blades and intermediate-pressure moving blades that constitute the intermediate-pressure turbine 40. The high-pressure turbine 30 and the intermediate-pressure turbine 40 are configured by combining a plurality of moving blades.
[0005]
9a, 9b, and 9c are exhaust chambers of the high-pressure turbine 30, and are formed between the outer periphery of the inner casing 2 and the inner periphery of the outer casing 1, as shown in FIG. An exhaust chamber 9a, a lower exhaust chamber 9b connected to the high-pressure exhaust port 6, and a side exhaust chamber 9c connecting the upper exhaust chamber 9a and the lower exhaust chamber 9b. .
Reference numerals 2a and 2b denote upper and lower connecting flanges of the inner casing 2 divided into two parts, and reference numeral 15 denotes a connecting bolt inserted through the flange 2a.
[0006]
During the operation of the steam turbine, the main steam introduced into the high-pressure turbine 30 from the main steam inlet 11 ′ performs expansion work in the high-pressure blade stage including the high-pressure stationary blade 5 and the high-pressure blade 4, and then the exhaust chamber. It passes through 9a, 9c, 9b, reaches the high pressure exhaust port 6, is sent from the high pressure exhaust port 6 to a boiler (not shown), and is reheated by the boiler.
[0007]
The reheated steam enters the intermediate pressure turbine 40 from the reheat steam inlet 7, performs expansion work in the intermediate pressure blade stage including the intermediate pressure stationary blade 11 and the intermediate pressure rotor blade 12, and then passes through the exhaust chamber 12 ′. The intermediate pressure exhaust port 8 is sent to the low pressure turbine (not shown).
[0008]
During the above operation, the steam that has been expanded by the high-pressure blade 4 at the final stage of the high-pressure turbine 30, that is, high-pressure exhaust, flows from the high-pressure stage outlet 2 d to the outer peripheral side of the inner casing 2 as shown in FIGS. To the exhaust chambers 9a, 9c and 9b.
[0009]
Most of the high-pressure exhaust gas that has flowed into the lower exhaust chamber 9b flows directly into the high-pressure exhaust port 6, but the high-pressure exhaust gas that has flowed into the upper exhaust chamber 9a passes along the outer surface of the inner casing 2 on the side portion side. The high-pressure exhaust gas flows into the exhaust chamber 9c, and flows into the lower- side exhaust chamber 9b by joining the high-pressure exhaust gas flowing out from the high-pressure stage outlet 2d into the exhaust chamber 9c on the side , and flows out from the high-pressure stage outlet 2d. It merges with a part of the exhaust and flows to the high-pressure exhaust port 6.
[0010]
However, in the exhaust system of a steam turbine having the conventional exhaust chamber structure as shown in FIG. 3, the exhaust gas flows out to the upper side of the exhaust chamber 9a from the high-pressure stage outlet 2d flange 2a of the inner casing 2, 2b is since protrudes into the exhaust chamber 9c side of the side portion has a flow resistance, not flow smoothly from the upper side of the exhaust chamber 9a to the exhaust chamber 9c side portion, the vortex in the upper recess of the flange 2a 21 '.
Also, the high-pressure exhaust gas flowing from the exhaust chamber 9c side portion to the exhaust chamber 9b of the lower side, since the section recess in the lower portion of the flange 2b is formed, resulting in the vortex 20 'in the recess portion.
[0011]
Accordingly, in the steam turbine exhaust system having the conventional exhaust chamber structure, the flow is disturbed by the formation of the vortices 20 'and 21' in the recess, so that the high pressure exhaust gas is discharged from the high pressure stage outlet 2d. The flow of the exhaust gas to the port 6 is not a smooth flow, and the pressure loss increases, resulting in a decrease in turbine performance.
[0012]
[Problems to be solved by the invention]
The present invention solves the above-mentioned problems, and the object of the present invention is to make the exhaust passage through which the exhaust sent from the high-pressure turbine or the intermediate-pressure turbine flows a smooth flow without the generation of vortices. Another object of the present invention is to provide a steam turbine exhaust device that reduces pressure loss and prevents deterioration of turbine performance.
[0013]
[Means for Solving the Problems]
SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems. The gist of the present invention is that exhaust (steam) flowing out from the final stage outlet of a high-pressure turbine or an intermediate-pressure turbine is exhausted from the outer surface of the inner casing and the inner surface of the outer casing. In a steam turbine that is led to an exhaust port through an exhaust chamber formed between
The outer surface of the inner casing, the upper flow guide and a lower flow guide for guiding the exhaust, provided so as to cover the outer periphery of the inner casing, butt each end face at the attachment portion to the flange of the inner casing, In the exhaust apparatus for a steam turbine, the exhaust chamber is formed between an outer surface of the upper flow guide and the lower flow guide and an inner surface of the outer casing.
[0014]
According to the above means, the exhaust (steam) flowing out from the final stage of the high-pressure turbine or intermediate-pressure turbine flows into the exhaust chamber formed between the outer surface of the upper flow guide and the lower flow guide and the inner surface of the outer casing. Then, it is guided by the outer surfaces of the upper flow guide and the lower flow guide , flows through the exhaust chamber, and is guided to the exhaust port.
[0015]
Thus, according to the above means, by providing the upper flow guide and the lower flow guides on the outside of the inner casing, the recessed portion formed in the upper and lower, etc. flange of the inner casing is no longer possible to face the exhaust chamber The exhaust chamber formed outside the upper flow guide and the lower flow guide becomes a smooth exhaust flow path without irregularities.
As a result, the formation of the exhaust vortex due to the formation of the hollow portion as in the prior art is avoided, and a smooth exhaust flow with a low flow resistance is obtained, and the pressure loss of the exhaust can be reduced.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS.
FIG. 2 is a longitudinal sectional view of a main part of a high and medium pressure turbine to which the present invention is applied, in which 30 is a high pressure turbine, 40 is a medium pressure turbine, 1 is an outer casing, 2 is an inner casing, The high-pressure turbine 30 and the intermediate-pressure turbine 40 are provided in the common outer casing 1 and inner casing 2.
[0017]
11 'is a main steam inlet for introducing main steam to the high-pressure turbine 30, 6 is a high-pressure exhaust port from which high-pressure exhaust from the high-pressure turbine 30 is led, and 7 is reheated steam from a boiler (not shown). reheat steam inlet for introducing the intermediate-pressure turbine 40, 8 is a pressure release port in the pressure release in the exhaust gas or al from the intermediate pressure turbine 40 is derived.
[0018]
Reference numerals 5 and 4 denote high-pressure stationary blades and high-pressure moving blades that constitute the high-pressure turbine 30, and 11 and 12 denote intermediate-pressure stationary blades and intermediate-pressure moving blades that constitute the intermediate-pressure turbine 40. The high-pressure turbine 30 and the intermediate-pressure turbine 40 are configured by combining a plurality of moving blades.
[0019]
Reference numerals 9a, 9b, 9c denote exhaust chambers of the high-pressure turbine 30, which are formed between the outer periphery of the inner casing 2 and the inner periphery of the outer casing 1, as shown in FIG. A chamber 9a, a lower exhaust chamber 9b connected to the high pressure exhaust port 6, and a side exhaust chamber 9c connecting the upper exhaust chamber 9a and the lower exhaust chamber 9b. .
Reference numerals 2a and 2b denote upper and lower connecting flanges of the inner casing 2 divided into two parts, and reference numeral 15 denotes a connecting bolt inserted through the flange 2a.
[0020]
The configuration of the high and medium pressure turbine shown above is the same as that of the conventional one.
FIG. 1 is a cross-sectional view of an exhaust chamber portion of a high-pressure turbine according to an embodiment of the present invention, in which 20 is an upper flow guide made of a plate material, and 21 is a lower flow guide made of a plate material. The upper flow guide 20 is provided so as to cover the outer periphery of the upper half of the inner casing 2, and the upper surface portion is fixed to the outer peripheral upper surface of the inner casing 2 with mounting screws 22, and the side surface portion is fixed to the flange 2 a with the mounting screws 22. It is fixed to the side surface 2c. The lower flow guide 21 extends along the outer periphery of the lower half of the inner casing 2 and extends downward from the upper flow guide 20 so as to swell, and a lower surface portion of the lower flow guide 21 protrudes downward from the inner casing 2. The side surface is fixed to the side surface 2c of the flange 2b of the inner casing 2 with the mounting screw 22.
[0021]
The upper flow guide 20 and the lower flow guide 21 face each other at the attachment portions to the flanges 2a and 2b, and in the direction of the rotor center 10 of the turbine rotor 3, the exhaust chambers 9a, 9b, and 9c as a whole, at least In FIG. 2, it is provided over the range of B.
[0022]
The main steam introduced from the main steam inlet 11 ′ into the high pressure turbine 30 during operation of the steam turbine configured as described above and having the exhaust chamber structure is a high pressure blade including the high pressure stationary blade 5 and the high pressure moving blade 4. After performing the expansion work in the stage, it passes through the exhaust chambers 9a, 9c, 9b to reach the high-pressure exhaust port 6 and is sent from the high-pressure exhaust port 6 to a boiler (not shown), where it is reheated and heated. Is done.
[0023]
The reheated steam enters the intermediate pressure turbine 40 from the reheat steam inlet 7, performs expansion work in the intermediate pressure blade stage including the intermediate pressure stationary blade 11 and the intermediate pressure rotor blade 12, and then passes through the exhaust chamber 12 ′. The intermediate pressure exhaust port 8 is sent to the low pressure turbine (not shown).
[0024]
During the operation, the steam that has been expanded by the high-pressure blade 4 at the final stage of the high-pressure turbine 30, that is, high-pressure exhaust, is exhausted from the high-pressure stage outlet 2d to the outer periphery of the inner casing 2 as shown in FIG. It flows out into the chambers 9a, 9c and 9b.
[0025]
Most of the high-pressure exhaust gas that has flowed into the lower exhaust chamber 9 b flows directly into the high-pressure exhaust port 6.
On the other hand, the exhaust flowing out to the upper side of the exhaust chamber 9a flows into the exhaust chamber 9c of being guided by the outer surface of the upper flow guide 20 side portion, wherein the outflow into the exhaust chamber 9c side portion from the high pressure stage outlet 2d was joined with pressure exhaust flow into the exhaust chamber 9b of the lower side is guided to the outer surface of the lower flow guides 21, further merges with a portion of the high pressure exhaust gas flowing out into the exhaust chamber 9b of the lower side from the high pressure stage outlet 2d Flow to the high-pressure exhaust port 6.
[0026]
During the flow of the high-pressure exhaust, the upper and lower surfaces and the flanges 2a of the inner casing 2, by providing the upper flow guide 20 and the lower flow guide 21 on the outside of 2b, flange 2 a, the portion indentations in the upper and lower 2b eliminated, the exhaust passage leading to the exhaust chamber 9b of the lower side from the upper side of the exhaust chamber 9a through the exhaust chamber 9c side portion becomes a smooth flow path with no irregularities.
Thereby, formation of the vortex 20 and 21 resulting from formation of a hollow part like the conventional thing is avoided, it becomes a smooth exhaust flow with few flow path resistances, and a pressure loss is reduced.
[0027]
【The invention's effect】
The present invention is constructed as described above, according to the present invention, by the outside of the inner casing provided upper flow guide and a lower flow guide recesses are formed on the upper and lower, etc. flange of the inner casing The portion does not face the exhaust chamber, and the exhaust chamber formed outside the upper flow guide and the lower flow guide becomes a smooth exhaust passage without irregularities.
[0028]
This avoids the formation of exhaust vortices due to the formation of depressions as in the conventional type, resulting in a smooth exhaust flow with less flow resistance, reducing the pressure loss of the exhaust, and improving the turbine performance compared to the conventional type. It can Rukoto to improve.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an exhaust chamber portion of a high and medium pressure turbine according to an embodiment of the present invention.
FIG. 2 is a longitudinal sectional view of a main part of a high and medium pressure turbine to which the present invention is applied.
FIG. 3 is a diagram corresponding to FIG. 1 showing a conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Outer casing 2 Inner casing 2a, 2b Flange 2d High pressure stage exit 3 Turbine rotor 4 High pressure moving blade 5 High pressure stationary blade 6 High pressure exhaust port 7 Reheat steam inlet 8 Medium pressure exhaust port 9a, 9b, 9c Exhaust chamber 10 Rotor center 11 Medium pressure stationary blade 12 Medium pressure blade 11 'Main steam inlet 12' Exhaust chamber (Medium pressure)
20 Upper Flow Guide 21 Lower Flow Guide 22 Mounting Screw 23 Mounting Boss 30 High Pressure Turbine 40 Medium Pressure Turbine

Claims (1)

In a steam turbine in which exhaust (steam) flowing out from the final stage outlet of a high-pressure turbine or intermediate-pressure turbine is guided to an exhaust port through an exhaust chamber formed between the outer surface of the inner casing and the inner surface of the outer casing.
The outer surface of the inner casing, the upper flow guide and a lower flow guide for guiding the exhaust, provided so as to cover the outer periphery of the inner casing, butt each end face at the attachment portion to the flange of the inner casing, An exhaust system for a steam turbine, wherein the exhaust chamber is formed between an outer surface of the upper flow guide and the lower flow guide and an inner surface of the outer casing.

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