JP2013050054A - Steam turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steam turbine that can certainly cool the constituent parts to be cooled, and suppress a drop of the turbine efficiency caused by the cooling steam.SOLUTION: The steam turbine 10 includes a turbine rotor 22 penetrating an internal casing 20, rotor blade rows configured so that a plurality of rotor blades 24 are implanted in the turbine rotor 22 in the circumferential orientation, a diaphragm outer race 26 and a diaphragm inner race 27 installed at the bore of the internal casing 20, and stator blade rows configured so that a plurality of stator blades 28 are installed between these diaphragms in the circumferential arrangement. The configuration includes a cooling steam introducing pipe 34 to supply the cooling steam to the turbine rotor 22 surface situated outside the first stage stator blade row and a cooling steam recovery passage 50 formed around the diaphragm inner race 27, stator blades 28, and the diaphragm outer race 26 to constitute a turbine step at the lowermost stream stage cooled by the cooling steam and recovering at least part of the cooling steam and leading it to a bleeder port.

Description

  Embodiments of the present invention relate to a steam turbine.

  From the viewpoint of improving the efficiency of steam turbines, steam turbines using mainstream steam having a temperature of about 600 ° C. are currently in practical use. In order to further improve the efficiency of the steam turbine, the temperature of the mainstream steam is considered to be about 650 to 750 ° C., and development is being advanced.

  In such a steam turbine, since the mainstream steam is high temperature, some components need to be made of a heat-resistant alloy. However, due to the high cost of heat-resistant alloys and the difficulty in producing large parts with heat-resistant alloys, technology to cool steam turbine components with cooling steam without using heat-resistant alloys has been studied. ing.

Japanese Patent Laid-Open No. 11-200801

  In the conventional cooling technique, when cooling the turbine rotor, the cooling steam supplied around the turbine rotor finally flows out to the mainstream steam side. As a result, the temperature of the mainstream steam decreases, leading to an increase in secondary flow loss in the blade row, and turbine efficiency decreases.

  The problem to be solved by the present invention is to provide a steam turbine capable of reliably cooling components to be cooled and suppressing a decrease in turbine efficiency due to cooling steam.

  The steam turbine according to the embodiment includes a casing, a turbine rotor penetrating the casing, and a plurality of moving blades implanted in the circumferential direction of the turbine rotor, and is provided with a plurality of stages in the turbine rotor axial direction. A plurality of stationary blades in the circumferential direction between the blade cascade, the diaphragm outer ring provided on the inner periphery of the casing, the diaphragm inner ring provided on the inner side of the diaphragm outer ring, and the diaphragm outer ring and the diaphragm inner ring And the stationary blade cascade provided in a plurality of stages alternately with the moving blade cascade in the axial direction of the turbine rotor. The diaphragm further comprises a cooling steam supply mechanism for supplying cooling steam to the surface of the turbine rotor upstream of the first stage stationary blade cascade, and a most downstream stage turbine stage cooled by the cooling steam. An inner ring, the stationary blade and the diaphragm outer ring, or a cooling stage formed in the diaphragm inner ring, the stationary blade and the diaphragm outer ring, which constitutes a turbine stage which is one stage downstream of the most downstream turbine stage cooled by cooling steam. A cooling steam recovery passage for recovering at least a part of the steam and leading to an extraction port formed in an inner periphery of the casing;

It is a figure which shows the cross section (meridian cross section) containing the central axis of a turbine rotor of the steam turbine of 1st Embodiment. It is the figure which expanded a part of section (meridian section) including a central axis of a turbine rotor of a steam turbine of a 1st embodiment. In the first embodiment, a part of a section (a meridional section) including a central axis of a turbine rotor of a steam turbine when an extraction port is formed immediately downstream of a turbine stage that is one stage downstream of a cooling final turbine stage FIG. It is a figure showing an outline of steam turbine power generation equipment provided with a steam turbine of a 1st embodiment. It is the figure which expanded a part of section (meridian section) including a central axis of a turbine rotor of a steam turbine of a 2nd embodiment. In 2nd Embodiment, it is the figure which expanded a part of cross section (meridian cross section) including the central axis of a turbine rotor of the steam turbine in case a collection port has a labyrinth seal formed.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a diagram illustrating a cross section (meridian cross section) including a central axis of a turbine rotor 22 of the steam turbine 10 according to the first embodiment. In the following description, the same components are denoted by the same reference numerals, and redundant description is omitted or simplified.

  In the following, a high-pressure turbine will be described as an example of the steam turbine 10, but the configuration of the present embodiment can also be applied to an intermediate-pressure turbine and further to an ultrahigh-pressure turbine.

  As shown in FIG. 1, the steam turbine 10 includes a double-structure casing composed of an inner casing 20 and an outer casing 21 provided outside the inner casing 20. A turbine rotor 22 is provided in the inner casing 20. The turbine rotor 22 is formed with a plurality of stages of rotor disks 23 in the turbine rotor axial direction. A plurality of rotor blades 24 are implanted in each rotor disk 23 in the circumferential direction to constitute a rotor blade cascade 25.

  A diaphragm outer ring 26 is provided on the inner peripheral side of the inner casing 20 in the circumferential direction. Inside the diaphragm outer ring 26, a diaphragm inner ring 27 is provided in the circumferential direction.

  Between the diaphragm outer ring 26 and the diaphragm inner ring 27, a plurality of stationary blades 28 (nozzles) are supported in the circumferential direction to form a stationary blade cascade 29. The stationary blade cascade 29 is provided on the upstream side of each rotor blade cascade 25 and includes a plurality of stages of alternating stationary blade cascades 29 and moving blade cascades 25 in the turbine rotor axial direction. The stationary blade cascade 29 and the moving blade cascade 25 constitute one turbine stage.

  Here, an example is shown in which the bleed port 36 is provided immediately downstream of the fifth stage turbine stage, but the position where the bleed port 36 is provided is not limited to this position. The bleed port 36 is formed on the outer peripheral side of the diaphragm outer ring 26 in the circumferential direction, and communicates with a bleed pipe (not shown).

  A labyrinth seal 30 is provided on the side of the diaphragm inner ring 27 facing the turbine rotor 22. As a result, leakage of steam from between the diaphragm inner ring 27 and the turbine rotor 22 to the downstream side is suppressed.

  Further, the steam turbine 10 is provided with a steam inlet pipe 31 penetrating the outer casing 21 and the inner casing 20, and the end of the steam inlet pipe 31 is connected to the nozzle box 32 in communication therewith. A first stage vane 28 is provided at the outlet of the nozzle box 32.

  On the inner periphery of the inner casing 20 and the outer casing 21 outside the position where the nozzle box 32 is provided (outside in the direction along the turbine rotor 22 and to the left of the nozzle box 32 in FIG. 1), the axial direction of the turbine rotor A plurality of gland labyrinth seals 33 are provided to prevent the steam from leaking to the outside between the inner casing 20 and the outer casing 21 and the turbine rotor 22.

  Further, the steam turbine 10 is provided with a cooling steam introduction pipe 34 that functions as a part of the cooling steam supply mechanism, penetrating the outer casing 21 and the inner casing 20. The cooling steam introduction pipe 34 may be connected to the inner casing 20 so as to penetrate the outer casing 21 and communicate with a through hole formed in the inner casing 20.

  The cooling steam introduction pipe 34 communicates with a groove 35 formed in the inner circumferential surface of the inner casing 20 between the gland labyrinth seals 33 in the circumferential direction. In this manner, the cooling steam outlet and the groove 35 of the cooling steam introduction pipe 34 are outside the first stage stationary blades 28 and the nozzle box 32 (outside in the direction along the turbine rotor 22, and in FIG. It is located on the left side of the box 32.

  Since the cooling steam supplied from the cooling steam introduction pipe 34 spreads in the circumferential direction along the groove 35, the cooling steam is supplied uniformly in the circumferential direction. The cooling steam introduction pipes 34 may be provided at a plurality of locations in the circumferential direction.

  As the cooling steam, steam extracted from another steam turbine, steam extracted from a boiler, or the like can be used. When the steam turbine 10 is a high pressure turbine or an ultra high pressure turbine, for example, steam extracted from a boiler can be used as the cooling steam. When both a high-pressure turbine and an ultrahigh-pressure turbine are provided, for example, steam extracted from the ultrahigh-pressure turbine can be used as cooling steam in the high-pressure turbine. When the steam turbine 10 is an intermediate pressure turbine, for example, steam extracted from a high-pressure turbine can be used as the cooling steam.

  The temperature of the cooling steam is preferably set to a temperature that does not generate a large thermal stress in the components such as the turbine rotor 22 to be cooled, and can be changed depending on the specifications of the steam turbine that supplies the cooling steam.

  The supply pressure of the cooling steam flows between the grand labyrinth seal 33 and the turbine rotor 22 to the turbine stage side, and flows to the extraction port 36 through a predetermined turbine stage for cooling and a cooling steam recovery flow path 50 described later. Is set to a possible pressure. Further, since a part of the cooling steam is ejected from the turbine stage into which the cooling steam is introduced into the main steam flow path 70, the supply pressure of the cooling steam is higher than the pressure of the main steam in each turbine stage. Is set to

  Next, the cooling steam recovery path will be described.

  FIG. 2 is an enlarged view of a part of a cross section (meridian cross section) including the central axis of the turbine rotor 22 of the steam turbine 10 according to the first embodiment.

  Here, the diaphragm inner ring, the stationary blade, the diaphragm outer ring, the labyrinth seal, the rotor disk, and the rotor blade constituting the third stage turbine stage, which is the most upstream turbine stage shown in FIG. , 28a, 26a, 30a, 23a and 24a. Here, the most downstream turbine stage (hereinafter referred to as the final cooling turbine stage) cooled by the cooling steam is the fifth turbine stage, and the diaphragm inner ring, the stationary blade, the diaphragm outer ring, which constitute the turbine stage, The labyrinth seal, the rotor disk, and the rotor blade are designated as 27c, 28c, 26c, 30c, 23c, and 24c, respectively. Also in the other turbine paragraphs, reference numerals are given to the respective components based on this. In FIG. 2, the flow of the cooling steam is indicated by arrows.

  As shown in FIG. 2, a cooling steam recovery flow path that collects at least a part of the cooling steam and guides it to the bleed port 36 at the diaphragm inner ring 27 c, the stationary blade 28 c, and the diaphragm outer ring 26 c constituting the final cooling turbine stage. 50 is formed. The cooling steam recovery flow path 50 is configured by a hole communicating the diaphragm inner ring 27c, the stationary blade 28c, and the diaphragm outer ring 26c.

  A plurality of recovery ports 51 for recovering the cooling steam are formed on the downstream end face of the diaphragm inner ring 27c, for example, at equal intervals in the circumferential direction. The recovery port 51 can be formed on the downstream end face of the diaphragm inner ring 27c, for example, corresponding to the stationary blade 28c arranged in the circumferential direction.

  The cooling steam recovery flow path 50 formed in the diaphragm outer ring 26c can be configured as a flow path that is bent so as to discharge cooling air toward the opening of the extraction port 36, for example, as shown in FIG. .

  Note that the cooling steam recovery flow path 50 formed in the diaphragm outer ring 26c is not limited to this shape, and may be formed, for example, obliquely and linearly so as to discharge the cooling air toward the opening of the extraction port 36. Good.

  Further, the cooling steam recovery flow path 50 formed in the diaphragm outer ring 26 c may be formed linearly in the radial direction so as to discharge the cooling steam between the diaphragm outer ring 26 c and the inner casing 20. In this case, the cooling steam flows toward the extraction port 36 between the diaphragm outer ring 26 c and the inner casing 20. For example, a slit-like flow path is formed on the downstream end face of the diaphragm outer ring 26c that is in contact with the inner casing 20. Thus, the cooling steam can flow out to the extraction port 36 side.

  In addition, although the cooling steam recovery flow path 50 is formed also in the stationary blade 28c, for example, when the inside of the stationary blade 28c is a hollow stationary blade, the hollow portion is caused to function as the cooling steam recovery flow path 50. Can do.

  Here, as shown in FIG. 2, an example is shown in which the planted portions of the rotor blades 24a, 24b, and 24c are configured in a saddle-shaped dovetail shape that is implanted in the circumferential direction on the rotor disks 23a, 23b, and 23c. . Therefore, a cooling steam passage 60 for guiding the cooling steam to the downstream side is formed in the rotor disks 23a and 23b constituting the turbine stage upstream of the final cooling turbine stage. A cooling steam passage 60 is also formed in the rotor disk 23 that forms the turbine stage upstream of the final cooling turbine stage, not shown in FIG.

  The rotor blades 24 a, 24 b, and 24 c may be constituted by, for example, a so-called axial insertion blade root type rotor blade that is inserted in the axial direction of the turbine rotor 22. In this case, the outer peripheral end surface of the impeller and the blade roots of the rotor blades adjacent in the circumferential direction form a gap (balance groove) penetrating in the turbine rotor axial direction. It is not necessary to form the cooling steam passage 60.

  Next, the operation of the steam turbine 10 will be described.

  The steam flowing into the nozzle box 32 through the steam inlet pipe 31 performs expansion work while passing through each turbine stage, and rotates the turbine rotor 22. The steam that has performed expansion work passes through an exhaust passage (not shown) and is exhausted to the outside of the steam turbine 10.

  The cooling steam introduced through the cooling steam introduction pipe 34 is supplied to the groove 35 and spreads in the circumferential direction (see FIG. 1). A part of the cooling steam flows from between the turbine rotor 22 and the ground labyrinth seal 33 to the turbine stage side along the turbine rotor 22 while cooling the turbine rotor 22 (see FIG. 1).

  Subsequently, part of the cooling steam passes through the cooling steam passage 60 formed in the rotor disk 23 toward the downstream, and the remaining part of the cooling steam is ejected into the main steam channel 70 (see FIG. 1).

  Then, as shown in FIG. 2, while cooling the turbine rotor 22, a part of the cooling steam that has reached the fifth turbine stage, which is the final cooling turbine stage, passes between the turbine rotor 22 and the labyrinth seal 30 c. It flows downstream and is recovered from the recovery port 51.

  The cooling steam recovered from the recovery port 51 is guided to the opening of the extraction port 36 via the cooling steam recovery channel 50. The cooling steam guided to the extraction port 36 is discharged to the outside as extraction steam together with a part of the main steam.

  Here, in order to prevent main steam from flowing from the main steam flow path 70 to the turbine rotor 22 side, a minimum amount of cooling steam is jetted from the turbine rotor 22 side to the main steam flow path 70 side. The sum of the flow rates of cooling steam required for cooling is usually greater than the sum of the minimum jet flow rates.

  Therefore, in the cooling method in the conventional steam turbine that does not include the cooling steam recovery channel 50, the cooling steam having a flow rate exceeding the minimum ejection flow rate is jetted into the main steam channel 70 in the cooling final turbine stage. Such jetting of the cooling steam to the main steam flow path 70 causes a decrease in the temperature of the main steam and an increase in the secondary flow loss of the blade row, thereby lowering the turbine efficiency.

  However, according to the steam turbine 10 of the first embodiment, the cooling steam exceeding the minimum ejection flow rate can be recovered in the cooling final turbine stage. Therefore, it is possible to suppress the decrease in the temperature of the main steam and the increase in the secondary flow loss of the blade row, and to improve the turbine efficiency.

  Furthermore, since the recovered cooling steam functions as extraction steam, the flow rate of main steam extracted as extraction steam can be reduced. Thereby, the turbine efficiency can be improved.

  Here, in the above description, an example in which the extraction port 36 is formed on the downstream side of the final cooling turbine stage is shown, but the formation position of the extraction port 36 is not limited to this position.

  FIG. 3 is a cross section including the central axis of the turbine rotor 22 of the steam turbine 10 in the first embodiment when the extraction port 36 is formed immediately downstream of the turbine stage one stage downstream of the cooling final turbine stage. It is the figure which expanded a part of (meridian section).

  As shown in FIG. 3, when the bleed port 36 is formed immediately downstream of the turbine stage one stage downstream of the cooling final turbine stage, the diaphragm outer ring 26 d constituting the turbine stage one stage downstream of the cooling final turbine stage and the inside A flow path through which the cooling steam passes to the extraction port 36 side is formed between the casing 20 and the casing 20. This flow path functions as a cooling steam recovery flow path 50. Note that, for example, a slit-shaped flow path is formed on the downstream end face of the diaphragm outer ring 26d with which the inner casing 20 contacts. Thus, the cooling steam can flow out to the extraction port 36 side.

  Next, an example of the steam turbine power generation facility provided with the steam turbine 10 of the first embodiment is shown. FIG. 4 is a diagram illustrating an outline of a steam turbine power generation facility including the steam turbine 10 according to the first embodiment.

  The steam turbine power generation facility shown in FIG. 4 includes a boiler 82 including a superheater 80 and a reheater 81, a high pressure turbine that is the steam turbine 10, an intermediate pressure turbine 90, a low pressure turbine 91, a generator 92, and a condenser 100. , A condensate pump 101, a low-pressure feed water heater 102, a boiler feed water pump 103, and a high-pressure feed water heater 104.

  In this steam turbine power generation facility, the high-temperature steam generated in the superheater 80 of the boiler 82 is introduced into the steam turbine 10 via the main steam pipe 110 and performs expansion work, and then via the low-temperature reheat steam pipe 111. The reheater 81 of the boiler 82 is introduced.

  The steam heated (reheated) again to the high-temperature superheated steam by the reheater 81 is introduced into the intermediate pressure turbine 90 through the high-temperature reheat steam pipe 112. After the expansion work is performed by the intermediate pressure turbine 90, the medium is introduced into the low pressure turbine 91 through the crossover pipe 113.

  The steam introduced into the low-pressure turbine 91 is guided to the condenser 100 after performing expansion work. The generator 92 is driven by the low-pressure turbine 91 to generate power.

  The steam guided to the condenser 100 is condensed and becomes condensate. Condensate in the condenser 100 is sent to the low-pressure feed water heater 102 by the condensate pump 101, boosted by the boiler feed pump 103, and then to the superheater 80 via the feed water pipe 120 and the high-pressure feed water heater 104. Water is supplied.

  The extracted steam extracted from the steam turbine 10 and the intermediate pressure turbine 90 passes through the extraction pipes 121 and 122, is guided to the high-pressure feed water heater 104, and heats the feed water flowing in the high-pressure feed water heater 104. The extraction steam extracted from the low-pressure turbine 91 passes through the extraction pipe 123 and is led to the low-pressure feed water heater 102 to heat the feed water flowing in the low-pressure feed water heater 102. The extracted steam that has heated the high-pressure feed water heater 104 and the low-pressure feed water heater 102 is guided to the condenser 100.

  Although not shown in FIG. 4, the steam turbine power generation facility is provided with a cooling steam supply pipe that guides, for example, extracted steam from a boiler to the steam turbine 10 that is a high-pressure turbine as cooling steam. Further, for example, a cooling steam supply pipe for guiding the extracted steam of the steam turbine 10 to the intermediate pressure turbine 90 is provided as the cooling steam. These cooling steam supply pipes function as a part of the cooling steam supply mechanism.

  As described above, in the steam turbine power generation facility including the steam turbine 10 according to the first embodiment, the feed water is heated by the extracted steam extracted from the steam turbine 10, the intermediate pressure turbine 90, and the low pressure turbine 91. Efficiency can be improved.

  Note that the above-described steam turbine power generation facility may further include, for example, an ultrahigh pressure turbine. In this case, for example, steam extracted from the ultrahigh pressure turbine can be used as the cooling steam in the high pressure turbine.

(Second Embodiment)
The steam turbine 11 of the second embodiment is the same as the configuration of the steam turbine 10 of the first embodiment except for the configuration of the cooling steam recovery path. Therefore, here, the configuration of the cooling steam recovery path will be mainly described.

  FIG. 5 is an enlarged view of a part of a cross section (meridian cross section) including the central axis of the turbine rotor 22 of the steam turbine 11 according to the second embodiment.

  Here, the diaphragm inner ring, the stationary blade, the diaphragm outer ring, the labyrinth seal, the rotor disk, and the rotor blade constituting the third stage turbine stage, which is the most upstream turbine stage shown in FIG. , 28a, 26a, 30a, 23a and 24a. Also, here, the final cooling turbine stage is the fourth stage turbine stage, and the diaphragm inner ring, the stationary blade, the diaphragm outer ring, the labyrinth seal, the rotor disk, and the rotor blade constituting the turbine stage are respectively 27b, 28b, and 26b. , 30b, 23b and 24b. Also in the other turbine paragraphs, reference numerals are given to the respective components based on this. In FIG. 5, the flow of the cooling steam is indicated by arrows.

  In the steam turbine 11, a cooling steam recovery passage is formed in a turbine stage (fifth stage turbine stage) that is one stage downstream of the final cooling turbine stage. In the steam turbine 11, as shown in FIG. 5, at least a part of the cooling steam is collected in the diaphragm inner ring 27 c, the stationary blade 28 c and the diaphragm outer ring 26 c constituting the turbine stage one stage downstream from the final cooling turbine stage. Thus, a cooling steam recovery flow path 50 that leads to the extraction port 36 is formed. The cooling steam recovery flow path 50 is configured by a hole communicating the diaphragm inner ring 27c, the stationary blade 28c, and the diaphragm outer ring 26c.

  A plurality of recovery ports 52 for recovering the cooling steam are formed on the upstream end face of the diaphragm inner ring 27c, for example, at equal intervals in the circumferential direction. The recovery port 52 can be formed on the upstream end face of the diaphragm inner ring 27c, for example, corresponding to the stationary blade 28c arranged in the circumferential direction.

  The cooling steam recovery flow path 50 formed in the diaphragm outer ring 26c can be configured as a bent flow path so as to discharge the cooling air toward the opening of the extraction port 36, for example, as shown in FIG. .

  Note that the cooling steam recovery flow path 50 formed in the diaphragm outer ring 26c is not limited to this shape, and may have another shape described in the steam turbine 10 of the first embodiment. Further, the cooling steam recovery flow path 50 is also formed in the stationary blade 28c. For example, when the stationary blade 28c is a hollow stationary blade, the hollow portion functions as the cooling steam recovery flow path 50. Can do.

  Here, since the cooling steam recovery flow path is formed in the turbine stage one stage downstream of the cooling final turbine stage, the cooling for guiding the cooling steam to the downstream side also in the rotor disk 23b constituting the cooling final turbine stage. A steam passage 60 is formed.

  The cooling steam introduced through the cooling steam introduction pipe 34 is supplied to the groove 35 and spreads in the circumferential direction (see FIG. 1). A part of the cooling steam flows from between the turbine rotor 22 and the ground labyrinth seal 33 to the turbine stage side along the turbine rotor 22 while cooling the turbine rotor 22 (see FIG. 1).

  Subsequently, part of the cooling steam passes through the cooling steam passage 60 formed in the rotor disk 23 toward the downstream, and the remaining part of the cooling steam is ejected into the main steam channel 70 (see FIG. 1).

  Then, as shown in FIG. 5, while cooling the turbine rotor 22, a part of the cooling steam that has reached the fourth turbine stage, which is the final cooling turbine stage, passes between the turbine rotor 22 and the labyrinth seal 30 b. It flows downstream and passes through the cooling steam passage 60 formed in the rotor disk 23b toward the downstream.

  A part of the cooling steam reaching the fourth stage turbine stage is recovered from the recovery port 52. The cooling steam recovered from the recovery port 52 is guided to the opening of the extraction port 36 via the cooling steam recovery channel 50. The cooling steam guided to the extraction port 36 is discharged to the outside as extraction steam together with a part of the main steam.

  According to the steam turbine 11 of the second embodiment described above, the cooling steam exceeding the minimum ejection flow rate ejected to the main steam flow path 70 is recovered in the turbine stage one stage downstream from the cooling final turbine stage. be able to. Therefore, it is possible to suppress the decrease in the temperature of the main steam and the increase in the secondary flow loss of the blade row, and to improve the turbine efficiency.

  Further, the upstream and downstream surfaces of the rotor disk 23b constituting the final cooling turbine stage can be cooled. Furthermore, since the recovered cooling steam functions as extraction steam, the flow rate of main steam extracted as extraction steam can be reduced. Thereby, the turbine efficiency can be improved.

  Here, the position of the recovery port 52 in the steam turbine 11 of the second embodiment is not limited to the upstream end face of the diaphragm inner ring 27c. FIG. 6 is an enlarged view of a part of a cross section (meridian cross section) including the central axis of the turbine rotor 22 of the steam turbine 11 when the recovery port 52 is formed in the labyrinth seal 30c in the second embodiment. It is.

  As shown in FIG. 6, the cooling steam recovery flow path 50 may be extended to the labyrinth seal 30 c supported by the diaphragm inner ring 27 c, and the recovery port 52 may be formed on the surface of the labyrinth seal 30 c facing the turbine rotor 22.

  Also in this case, the same effect as the effect in the steam turbine 11 described above can be obtained.

  According to the embodiment described above, it is possible to reliably cool the components to be cooled and to suppress a decrease in turbine efficiency due to the cooling steam.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 10,11 ... Steam turbine, 20 ... Inner casing, 21 ... Outer casing, 22 ... Turbine rotor, 23, 23a, 23b, 23c ... Rotor disk, 24, 24a ... Rotor blade, 25 ... Rotor blade cascade, 26, 26a, 26b, 26c, 26d ... Diaphragm outer ring, 27, 27a, 27b, 27c ... Diaphragm inner ring, 28, 28a, 28b, 28c ... Stator blade, 29 ... Stator blade cascade, 30, 30a, 30b, 30c ... Labyrinth seal, 31 ... Steam inlet pipe, 32 ... Nozzle box, 33 ... Grand labyrinth seal, 34 ... Cooling steam introduction pipe, 35 ... Groove, 36 ... Extraction port, 50 ... Cooling steam recovery flow path, 51, 52 ... Recovery port, 60 ... Cooling steam Passage, 70 ... main steam flow path, 80 ... superheater, 81 ... reheater, 82 ... boiler, 90 ... medium pressure turbine, 91 ... low pressure turbine, 92 Generator: 100 ... Condenser, 101 ... Condensate pump, 102 ... Low pressure feed water heater, 103 ... Boiler feed pump, 104 ... High pressure feed water heater, 110 ... Main steam pipe, 111 ... Low temperature reheat steam pipe, 112 ... high temperature reheat steam pipe, 113 ... crossover pipe, 120 ... water supply pipe, 121, 122, 123 ... extraction pipe.

Claims (5)

A casing,
A turbine rotor penetrating the casing;
A plurality of rotor blades are implanted in the circumferential direction of the turbine rotor, and a plurality of rotor blade cascades provided in the turbine rotor axial direction;
A diaphragm outer ring provided on the inner periphery of the casing;
A diaphragm inner ring provided inside the diaphragm outer ring;
Between the diaphragm outer ring and the diaphragm inner ring, a plurality of stator blades are attached in the circumferential direction, and in the turbine rotor axial direction, a stator blade cascade arranged in a plurality of stages alternately with the rotor blade cascade,
A cooling steam supply mechanism for supplying cooling steam to the surface of the turbine rotor outside the first stage blade cascade of the first stage;
The most downstream turbine stage cooled by the cooling steam constitutes the most downstream turbine stage, the diaphragm inner ring, the stationary blade and the diaphragm outer ring, or the most downstream stage turbine stage cooled by the cooling steam. And a cooling steam recovery passage formed on the inner ring of the diaphragm, the stationary blade and the outer ring of the diaphragm, and recovering at least a part of the cooling steam and leading to the extraction port formed on the inner periphery of the casing. A steam turbine characterized by that. In the case where the cooling steam recovery flow path is formed in the diaphragm inner ring, the stationary blade and the diaphragm outer ring, which constitutes the most downstream turbine stage cooled by the cooling steam,
The steam turbine according to claim 1, wherein a cooling steam recovery port in the cooling steam recovery flow path is formed on an end face on the downstream side of the inner ring of the diaphragm. In the case where the cooling steam recovery flow path is formed in the diaphragm inner ring, the stationary blade, and the diaphragm outer ring that constitute a turbine stage that is one stage downstream of the most downstream turbine stage that is cooled by the cooling steam,
The steam turbine according to claim 1, wherein a cooling steam recovery port in the cooling steam recovery flow path is formed on an end face on the upstream side of the inner ring of the diaphragm. In the case where the cooling steam recovery flow path is formed in the diaphragm inner ring, the stationary blade, and the diaphragm outer ring that constitute a turbine stage that is one stage downstream of the most downstream turbine stage that is cooled by the cooling steam,
The cooling steam recovery flow path is further formed in a seal portion supported by the inner ring of the diaphragm, and a cooling steam recovery port is formed on a surface of the seal portion facing the turbine rotor. The steam turbine according to claim 1.   5. The steam turbine according to claim 1, wherein the extraction port is provided on a downstream side of a turbine stage at a most downstream stage cooled by cooling steam. 6.

Images