JP2013019284A - Steam turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steam turbine capable of precisely performing cooling by suppressing an increase in temperature of cooling steam until reaching a component to be cooled.SOLUTION: This steam turbine 10 comprises a turbine rotor constituted by joining turbine rotor components 40, 50 in an axial direction. The turbine rotor component 40 comprises: a rotor body 41; a recess 43 formed at a central part of a joining end surface 42 of the rotor body 41; a center through hole 44 formed at an axial center of the rotor body and having one end in communication with the recess 43; and a cooling steam introduction hole 45 having an opening at an outer circumferential surface of the rotor body 41 and in communication with the center through hole 44. The turbine rotor component 50 comprises: a rotor body 51 including a wheel part 54 formed in a circumferential direction of an outer circumferential surface; a recess 53 formed at a central part of a joining end surface 52 of the rotor body 51; and a cooling steam jet hole 55 having an opening at the outer circumferential surface of the rotor body 51 and in communication with the recess 53.

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 700 to 750 ° C., and development is being promoted.

  In such a steam turbine, since the mainstream steam is high temperature, some components need to be made of a heat-resistant alloy. For example, in a part where a large stress is generated such as a blade implantation part, it is necessary to provide a cooling structure in addition to being made of a heat resistant alloy in order to improve durability. Therefore, a technique for suppressing a decrease in material strength due to a high temperature by cooling component parts that become high temperature has been studied.

Japanese Patent Laid-Open No. 2006-104951

  However, in the conventional steam turbine cooling structure, the cooling steam pipe for supplying the cooling steam may be arranged so as to cross the high-temperature mainstream steam, and in such a configuration, heat from the mainstream steam is generated. Upon receipt, the cooling steam is heated. Therefore, the temperature of the cooling steam rises before reaching the component to be cooled, and the component may not be sufficiently cooled.

  In addition, in the case of using a structure that cools the components of the downstream turbine stage using the cooling steam that has cooled the components of the upstream turbine stage, the temperature of the cooling steam rises. In some cases, the components could not be cooled sufficiently.

  That is, none of the conventional steam turbines has a configuration for accurately cooling the component parts by a simple method.

  The problem to be solved by the present invention is to provide a steam turbine capable of suppressing the temperature rise of cooling steam until reaching the component to be cooled and cooling the component accurately.

  The steam turbine according to the embodiment includes a turbine rotor configured by joining at least two turbine rotor components in the turbine rotor axial direction. One turbine rotor constituent member to be joined is constituted by a cylindrical first rotor body. The first rotor body is formed at the center of the joint end face of the first rotor body and the axial center of the first rotor body, and one end is A central through hole that communicates with the first recess and the other end of which can be sealed, and has an opening in the outer peripheral surface of the first rotor body, and the introduced cooling steam is passed through the central through hole And a cooling steam introduction hole leading to

  The other turbine rotor constituent member to be joined is constituted by a cylindrical second rotor body portion including a wheel portion in which a moving blade is implanted, which is formed in the circumferential direction so as to protrude outward in the radial direction. Is done. The second rotor body has a second recess formed at the center of the joining end surface of the second rotor body, and an opening on the outer peripheral surface of the second rotor body, A cooling steam ejection hole communicating with the second depression.

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 showed the other structure of the cooling steam ejection hole in the cross section equivalent to the AA cross section in FIG. 1 in which the meridional section of the steam turbine of 1st Embodiment was shown. 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 2nd Embodiment. 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 3rd Embodiment. It is meridional sectional drawing which shows the hollow part of another shape in the steam turbine of 3rd Embodiment. It is meridional sectional drawing which shows the hollow part of another shape in the steam turbine of 3rd Embodiment.

  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 24 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, an intermediate pressure turbine will be described as an example of the steam turbine 10, but the configuration of the present embodiment is also applied to a high pressure turbine to which high-temperature and high-pressure steam is supplied, and also to an ultra-high pressure turbine. Can do.

  As shown in FIG. 1, a diaphragm outer ring 21 is provided along the circumferential direction on the inner periphery of the casing 20, and a diaphragm inner ring 22 is provided along the circumferential direction inside the diaphragm outer ring 21. A plurality of stationary blades 23 are supported in the circumferential direction between the diaphragm outer ring 21 and the diaphragm inner ring 22 to constitute a stationary blade cascade.

  A labyrinth seal 33 is provided on the inner periphery of the diaphragm inner ring 22 to suppress the leakage of steam from between the diaphragm inner ring 22 and a turbine rotor 24 described later.

  A turbine rotor 24 is provided in the casing 20. As shown in FIG. 1, the turbine rotor 24 is configured by joining two turbine rotor constituent members 40 and 50 in the turbine rotor axial direction, for example, by welding or the like. Here, although an example in which the turbine rotor 24 is configured by two turbine rotor constituent members 40 and 50 is shown, the turbine rotor 24 may be configured by three or more turbine rotor constituent members.

  As shown in FIG. 1, the turbine rotor constituting member 40 constitutes the turbine rotor 24 on the outer side (left side in FIG. 1) than the position where the first stage stationary blade 23 is provided. Therefore, the turbine rotor constituent member 40 is not exposed to high-temperature steam, and can be made of conventional steel such as CrMoV steel, for example.

  The turbine rotor constituent member 40 includes a columnar rotor body 41 that functions as a first rotor body. A recess 43 that functions as a first recess is formed at the center of the joint end surface 42 of the rotor body 41. The recess 43 is formed so that a cross-sectional shape perpendicular to the turbine rotor shaft is, for example, a circle. For example, the recess 43 can be formed so that the cross-sectional shape is substantially the same in any cross-section. That is, the hollow part 43 becomes a cylindrical cavity part with a constant cross-sectional diameter, for example.

  A central through hole 44 with one end communicating with the recess 43 is formed at the axial center of the rotor body 41. The other end of the central through hole 44 is configured to be sealable to prevent the cooling steam introduced into the central through hole 44 from flowing out. The other end of the central through hole 44 is sealed with, for example, a sealing plate fixed via a flange.

  The rotor body 41 is formed with a cooling steam introduction hole 45 having an opening on the outer peripheral surface and communicating with the central through hole 44. For example, the cooling steam introduction holes 45 are constituted by through holes that penetrate radially in the radial direction of the rotor body 41 and are formed at a plurality of locations in the circumferential direction. Cooling steam is introduced into the central through hole 44 through the cooling steam introduction hole 45.

  On the other hand, as shown in FIG. 1, the turbine rotor constituent member 50 constitutes the turbine rotor 24 on the inner side (right side in FIG. 1) than the position where the first stage stationary blade 23 is provided. Therefore, the turbine rotor constituent member 50 is exposed to high-temperature steam and becomes high temperature, and thus is configured of, for example, heat-resistant steel such as 12Cr steel or heat-resistant alloy such as Ni-based alloy.

  The turbine rotor constituent member 50 includes a columnar rotor body 51 that functions as a second rotor body. At the center of the joint end surface 52 of the rotor body 51, a recess 53 that functions as a second recess is formed. The recess 53 is formed so that a cross-sectional shape perpendicular to the turbine rotor shaft is, for example, a circle. For example, the recessed portion 53 can be formed so that this cross-sectional shape is substantially the same in any cross-section. That is, the hollow part 53 becomes a cylindrical hollow part with a constant cross-sectional diameter, for example.

  The joint end surface 52 of the rotor body 51 is configured to have a shape corresponding to the joint end surface 42 of the rotor body 41, and for example, the shape of both the joint end surfaces 42 and 52 may be the same. preferable.

  The rotor body 51 is provided with a wheel portion 54 formed in the circumferential direction so as to protrude outward in the radial direction. The wheel portion 54 is formed in a plurality of stages in the turbine rotor axial direction. At the tip of the wheel portion 54, the moving blade 25 is implanted in the circumferential direction to constitute a moving blade cascade. This moving blade cascade is provided in the axial direction of the turbine rotor 24 alternately with the above-described stationary blade cascade, and constitutes a plurality of turbine stages including the stationary blade cascade and the moving blade cascade.

  A through hole 54a penetrating from the upstream side to the downstream side is formed on the turbine rotor shaft side of the wheel portion 54 from the portion where the rotor blades 25 are implanted. A part of the cooling steam flows into the turbine stage downstream, that is, one stage downstream through the through hole 54a.

  The rotor body 51 is formed with a cooling steam ejection hole 55 having an opening on the outer peripheral surface and communicating with the recess 53. The cooling steam ejection holes 55 are constituted by, for example, through holes that penetrate radially in the radial direction of the rotor body 51. And the cooling vapor | steam ejection hole 55 is formed in multiple places over the circumferential direction. The cooling steam that has flowed into the recess 53 is ejected to the outside of the rotor body 51 through the cooling steam ejection hole 55.

  Here, as shown in FIG. 1, the cooling steam jet is made so that the opening on the outer peripheral surface of the rotor body 51 is located between the root part of the wheel part 54 and the labyrinth seal 33 located on the upstream side thereof. It is preferable to form the holes 55. Further, it is more preferable that the cooling steam ejection hole 55 is formed so that the opening on the outer peripheral surface of the rotor body 51 is located immediately upstream of the root portion of the wheel portion 54.

  By forming the cooling steam ejection holes 55 in this way, the wheel portion 54 that is at a high temperature can be accurately cooled by the cooling steam.

  In the steam turbine shown in FIG. 1, an example is shown in which cooling steam ejection holes 55 are formed in a turbine stage that is exposed to high-temperature steam in the turbine stage, for example, from the upstream to the third stage. The cooling steam ejection holes 55 are preferably formed in the turbine stage where the inlet steam temperature of the turbine stage, that is, the inlet steam temperature of the stationary blade 23 becomes 600 to 750 ° C., for example.

  Here, the cooling steam ejection holes 55 are not limited to a structure that is formed radially in the radial direction of the rotor body 51, that is, in the radial direction in the through holes that penetrate perpendicularly to the turbine rotor shaft. For example, it may be formed so as to be inclined in the axial direction of the turbine rotor, like a cooling steam injection hole 55 formed in the third stage turbine stage of FIG. The passage cross-sectional area and the number of the cooling steam ejection holes 55 formed corresponding to each wheel portion 54 may be configured to be different for each corresponding wheel portion 54.

  Since the pressure in the steam flow path 32 through which the main steam flows is lower in the third stage turbine stage than in the first stage turbine stage, the pressure of the cooling steam and the configuration of the cooling steam ejection holes 55 are the same. The flow rate of the cooling steam in the third stage turbine stage is larger than that in the first stage turbine stage. However, as described above, the pressure loss when the cooling steam flows through the cooling steam ejection holes 55 is adjusted by changing the shape and the number of the cooling steam ejection holes 55 corresponding to each turbine stage. The steam flow rate can be optimized.

  The turbine rotor constituent member 40 and the turbine rotor constituent member 50 are joined to each other by welding or the like at the joint portion 26, and the turbine rotor 24 has a hollow portion composed of a recess portion 43 and a recess portion 53 as shown in FIG. It becomes the composition to provide.

  A plurality of ground labyrinth seals 27 are provided along the turbine rotor axial direction on the inner periphery of the casing 20 on the outer side (left side in FIG. 1) from the position where the first stage blades 25 are provided. The steam is prevented from leaking to the outside between the turbine rotor 24 and the turbine rotor 24.

  On the inner peripheral surface of the casing 20 facing the opening of the cooling steam introduction hole 45 formed in the turbine rotor constituent member 40, a concave groove 28 is formed in the circumferential direction as shown in FIG. A ground labyrinth seal 27 is provided on the outer side (the left side in FIG. 1) and the inner side (the right side in FIG. 1) than the groove part 28 to prevent the cooling steam introduced into the groove part 28 from leaking to the surroundings. Yes.

  The casing 20 is formed with a communication hole 30 that communicates with a cooling steam supply pipe 29 that supplies cooling steam and guides the cooling steam to the groove 28. The communication hole 30 functions as a cooling steam introduction channel. The communication holes 30 are preferably formed at a plurality of locations in the circumferential direction in order to uniformly supply the cooling steam to the groove portions 28 over the circumferential direction.

  As the cooling steam, steam extracted from another steam turbine, steam exhausted from another steam turbine, steam extracted from a boiler, or the like can be used. 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. When the steam turbine 10 is a high-pressure turbine, for example, steam extracted from a boiler can be used as the cooling steam.

  Note that the temperature of the cooling steam is preferably set to a temperature at which a large thermal stress is not generated in the components such as the turbine rotor 24 to be cooled. The temperature of the cooling steam can be changed according to the specification of the steam turbine that supplies the cooling steam, and can be set to about 400 ° C., for example.

  The supply pressure of the cooling steam is set so that the pressure of the cooling steam ejected from the cooling steam ejection hole 55 is higher than the pressure in the steam flow path 32. That is, the supply pressure of the cooling steam is set to such an extent that the cooling steam can be surely ejected from the cooling steam ejection hole 55 to the steam flow path 32.

  Further, the steam turbine 10 is provided with a steam inlet pipe 31 so as to communicate the casing 20. Steam from the outside is introduced into the steam turbine 10 by the steam inlet pipe 31 and is introduced into the steam flow path 32 as main steam.

  Next, the operation of the steam turbine 10 having the cooling structure as described above will be described.

  As shown in FIG. 1, the steam introduced into the steam turbine 10 from the steam inlet pipe 31 is guided to the first stage stationary blade 23 and ejected toward the first stage moving blade 25. Then, the steam flows through the steam flow path 32 including the stationary blade 23 and the moving blade 25, and rotates the turbine rotor 24 while performing expansion work. The steam that has passed through the final stage moving blade 25 is exhausted to the outside of the steam turbine 10 through an exhaust passage (not shown).

  The cooling steam introduced from the cooling steam supply pipe 29 into the groove portion 28 through the communication hole 30 passes through the cooling steam introduction hole 45 and is guided to the center through hole 44. At this time, since the other end side of the central through hole 44 is sealed by a sealing member (not shown), the cooling vapor does not flow out from the other end of the central through hole 44 to the outside.

  The cooling steam guided to the central through hole 44 is introduced into a hollow portion composed of the recessed portion 43 and the recessed portion 53, and cools the turbine rotor 24 from the inside. The cooling steam introduced into the hollow portion is ejected from each cooling steam ejection hole 55 to, for example, the upstream side of the root portion of the wheel portion 54 to cool the surfaces of the turbine rotor 24 and the wheel portion 54. Most of the cooling steam flows into the steam flow path 32.

  A part of the jetted cooling steam passes through a through hole 54a formed in the wheel portion 54 and is guided to the downstream turbine stage. The wheel portion 54 is also cooled when the cooling steam passes through the through hole 54a.

  Thus, the turbine rotor 24 can be cooled from the inside and the outside by the cooling steam.

  As described above, according to the steam turbine 10 of the first embodiment, the cooling steam can be once introduced into the hollow portion inside the turbine rotor 24 and can be ejected to the outside through the cooling steam ejection hole 55. Therefore, the turbine rotor 24 can be cooled from the inside and the outside, and the temperature rise of the cooling steam until reaching the component to be cooled can be suppressed. Thereby, the component to be cooled can be accurately and efficiently cooled.

  Here, the configuration of the cooling steam ejection hole 55 described above is not limited to the configuration described above. FIG. 2 is a view showing another configuration of the cooling steam ejection hole 55 in a cross section corresponding to the AA cross section in FIG. 1 in which the meridional cross section of the steam turbine 10 of the first embodiment is shown.

  As shown in FIG. 2, the cooling steam ejection holes 55 may be formed to be inclined in the circumferential direction with respect to the radial direction of the turbine rotor. The direction of tilting may be the rotational direction of the turbine rotor 24 or the opposite direction.

  You may comprise so that the inclination angle of each cooling-vapor ejection hole 55 formed corresponding to each wheel part 54 may differ for every wheel part 54 corresponding. Also, in the cooling steam ejection holes 55 formed corresponding to the same wheel portion 54, the inclination angles of the cooling steam ejection holes 55 may be varied.

  In this way, by forming the cooling steam ejection hole 55 to be inclined in the circumferential direction, the passage length of the cooling steam ejection hole 55 can be changed, and the pressure loss in the cooling steam ejection hole 55 can be adjusted. Furthermore, by changing the shape and size of the cooling steam ejection hole 55, the pressure loss when the cooling steam flows through the cooling steam ejection hole 55 can be adjusted. In other words, the flow rate of the cooling steam ejected for each cooling steam ejection hole 55 formed corresponding to each wheel portion 54 or for each cooling steam ejection hole 55 formed corresponding to the same wheel portion 54. Can be adjusted.

  Even in the case where the cooling steam ejection hole 55 is configured as described above, it is possible to obtain the same function and effect as those of the steam turbine 10 described above.

(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 ejection holes, and here, mainly the configuration of the cooling steam ejection holes. Will be described.

  FIG. 3 is a diagram showing a cross section (meridian cross section) including the central axis of the turbine rotor 24 of the steam turbine 11 according to the second embodiment.

  The turbine rotor 24 is configured by joining two turbine rotor constituent members 40 and 50 in the turbine rotor axial direction, for example, by welding.

  The rotor body 51 constituting the turbine rotor constituent member 50 is provided with a wheel portion 54 formed in the circumferential direction so as to protrude outward in the radial direction. The wheel portion 54 is formed in a plurality of stages in the turbine rotor axial direction. At the tip of the wheel portion 54, the moving blade 25 is implanted in the circumferential direction to constitute a moving blade cascade.

  As shown in FIG. 3, the wheel portion 54 is formed with a cooling steam ejection hole 60 having an opening at the tip end surface thereof and communicating with the recess portion 53. The cooling steam ejection holes 60 are constituted by, for example, through holes that penetrate radially in the radial direction of the rotor body 51. And the cooling vapor | steam ejection hole 60 is formed in multiple places over the circumferential direction. The cooling steam that has flowed into the recessed portion 53 through the cooling steam ejection hole 60 is ejected from the front end surface of the wheel portion 54 to the outside.

  When using the moving blade 25 having an outside tabtil type blade implantation portion as shown in FIG. 3, there is a gap between the root portion of the saddle-shaped leg portion of the blade implantation portion and the tip surface of the wheel portion 54. have. Therefore, the cooling steam ejected from the opening of the cooling steam ejection hole 60 on the front end surface of the wheel portion 54 collides with the root portion of the saddle-shaped leg portion of the blade implantation portion, thereby cooling the root portion.

  Here, the cooling steam ejection holes 60 are not limited to a structure that is formed radially in the radial direction of the rotor body 51, that is, in the radial direction in the direction perpendicular to the turbine rotor shaft, as described above. Further, it may be formed with a portion inclined in the turbine rotor axial direction. The passage cross-sectional area and the number of the cooling steam ejection holes 60 formed corresponding to each wheel portion 54 may be configured to be different for each corresponding wheel portion 54. Further, as shown in FIG. 3, the cooling steam ejection holes 60 may be formed to be inclined in the circumferential direction with respect to the radial direction of the turbine rotor.

  For example, by adjusting the shape and number of the cooling steam ejection holes 60 corresponding to each turbine stage, the pressure loss when the cooling steam flows through the cooling steam ejection holes 60 is adjusted, and the flow rate of the cooling steam is optimized. Can be achieved.

  In the steam turbine 11 having such a cooling structure, the cooling steam introduced from the cooling steam supply pipe 29 into the groove portion 28 through the communication hole 30 passes through the cooling steam introduction hole 45 and is guided to the central through hole 44. At this time, since the other end side of the central through hole 44 is sealed by a sealing member (not shown), the cooling vapor does not flow out from the other end of the central through hole 44 to the outside.

  The cooling steam guided to the central through hole 44 is introduced into a hollow portion composed of the recessed portion 43 and the recessed portion 53, and cools the turbine rotor 24 from the inside. The cooling steam introduced into the hollow portion passes through each cooling steam ejection hole 60, and from the opening of the cooling steam ejection hole 60 on the front end surface of the wheel portion 54, the vertical leg of the blade implantation portion of the blade 25. It is ejected toward the root. The jetted cooling steam cools the tip of the wheel portion 54 and the moving blade 25 and flows into the steam flow path 32.

  In addition, since the cooling steam ejected from the opening of the cooling steam ejection hole 60 flows into the steam flow path 32, in the second embodiment, the through-hole formed in the wheel portion 54 in the first embodiment. It can comprise without providing 54a.

  As described above, according to the steam turbine 11 of the second embodiment, the cooling steam can be once introduced into the hollow portion inside the turbine rotor 24 and can be ejected to the outside through the cooling steam ejection hole 60. Further, the cooling steam can pass through the inside of the wheel portion 54 and be ejected from the tip portion of the wheel portion 54.

  Therefore, the turbine rotor 24 can be cooled from the inside and the outside, and the temperature rise of the cooling steam until reaching the component to be cooled can be suppressed. Thereby, the component to be cooled can be accurately and efficiently cooled.

(Third embodiment)
In the steam turbine 12 of the third embodiment, the configuration of the steam turbine 10 of the first embodiment other than the configuration of the hollow portion formed of the recess 43 and the recess 53 formed inside the turbine rotor 24 is provided. Since the configuration is the same, the configuration of the hollow portion will be mainly described here.

  FIG. 4 is a view showing a cross section (meridian cross section) including the central axis of the turbine rotor 24 of the steam turbine 12 according to the third embodiment.

  As shown in FIG. 4, the turbine rotor 24 is configured by joining two turbine rotor constituent members 40 and 50 in the turbine rotor axial direction, for example, by welding or the like.

  The turbine rotor constituent member 40 includes a cylindrical rotor body 41, and a recess 43 is formed at the center of the joint end surface 42 of the rotor body 41. The recess 43 is formed so that a cross-sectional shape perpendicular to the turbine rotor shaft is, for example, a circle. For example, the recess 43 can be formed so that the cross-sectional shape is substantially the same in any cross-section, or the cross-sectional area gradually increases toward the opening side.

  The turbine rotor component 50 includes a cylindrical rotor body 51, and a recess 53 is formed at the center of the joint end surface 52 of the rotor body 51. The recess 53 is formed so that the cross-sectional shape perpendicular to the turbine rotor shaft is, for example, a circle, and the cross-sectional area is gradually increased toward the bottom 53 a of the recess 53. That is, the hollow part 53 is comprised by the cavity part which spreads in a taper shape toward the bottom part 53a.

  The joint end surface 52 of the rotor body 51 is configured to have a shape corresponding to the joint end surface 42 of the rotor body 41, and for example, the shape of both the joint end surfaces 42 and 52 may be the same. preferable.

  The rotor body 51 is formed with a cooling steam ejection hole 55 having an opening on the outer peripheral surface and communicating with the recess 53. For example, the cooling steam ejection holes 55 can be configured by through holes that penetrate radially in the radial direction of the rotor body 51. And the cooling vapor | steam ejection hole 55 is formed in multiple places over the circumferential direction. Cooling steam that has flowed into the recess 53 through the cooling steam ejection hole 55 is ejected to the outside of the rotor body 51.

  The cooling steam ejection holes 55 are not limited to a structure that is formed radially in the radial direction of the rotor body 51, i.e., in the direction perpendicular to the turbine rotor axis, as described above. You may incline and form in a turbine rotor axial direction. Further, the passage cross-sectional area and the number of the cooling steam ejection holes 55 formed corresponding to each wheel portion 54 may be configured to be different for each corresponding wheel portion 54. Further, as shown in FIG. 3, the cooling steam ejection holes 60 may be formed to be inclined in the circumferential direction with respect to the radial direction of the turbine rotor.

  For example, by adjusting the shape and number of the cooling steam ejection holes 55 corresponding to each turbine stage, the pressure loss when the cooling steam flows through the cooling steam ejection holes 55 is adjusted to optimize the flow rate of the cooling steam. Can be achieved.

  In the steam turbine 12 having such a cooling structure, the operation of the cooling steam is the same as the operation of the cooling steam in the first embodiment described above.

  In the steam turbine 12, after the operation is stopped, the cooling steam present in the depression 43 and the depression 53 is condensed, and water droplets are accumulated on the lower side of gravity in the depression 43 and the depression 53. If this is left untreated, corrosion proceeds in the turbine rotor 24.

  Therefore, the condensate accumulated on the gravity lower side in the recess 53 is guided to the cooling steam ejection hole 55 by forming the recess 53 in a tapered shape having inclined side surfaces as described above, and the cooling steam It is discharged to the steam flow path 32 through the ejection hole 55. Here, in FIG. 4, the flow of the condensed water is indicated by arrows. The condensed water guided to the lower gravity side of the steam flow path 32 is discharged to the outside of the steam turbine 12 through a discharge pipe (not shown) that discharges the condensed mainstream steam.

  In the case of the configuration of the recessed portion 53, the condensed water is finally guided to the bottom 53 a side of the recessed portion 53. Therefore, the condensed water that has not been discharged from the other cooling steam ejection holes 55 can be discharged from the cooling steam ejection holes 55 on the bottom 53 a side, and the condensate water can be prevented from remaining in the recess 53.

  Moreover, in the hollow part 43, when the depth of the hollow part 43 was deep, for example, it accumulated by comprising in the taper shape which has an inclined side surface so that a cross-sectional area may increase gradually toward an opening side. The condensed water can be more reliably guided to the cooling steam jet hole 55.

  As described above, according to the steam turbine 12 of the third embodiment, the condensed water accumulated in the recess 43 and the recess 53 after the operation is stopped can be discharged to the outside of the steam turbine 12. Therefore, in addition to the operational effects of the steam turbine 10 of the first embodiment described above, corrosion inside the turbine rotor 24 can be prevented.

  Here, the shape of the recessed portion 53 is not limited to the shape described above, and the recessed portion 53 is formed so that the area of the cross section perpendicular to the turbine rotor shaft in the recessed portion 53 differs along the turbine rotor axial direction. It only has to be done. That is, it is only necessary that the shape of the recess 53 is set so that the condensed water is finally guided to any one of the cooling steam ejection holes 55.

  FIG. 5 and FIG. 6 are meridional cross-sectional views showing other shaped recesses 53 in the steam turbine 12 of the third embodiment.

  As shown in FIG. 5, you may form the side surface of the hollow part 53 so that it may incline toward the cooling-vapor ejection hole 55 by the side of an opening. In this case, the condensed water is finally guided to the cooling steam ejection hole 55 on the opening side. Therefore, the condensed water that has not been discharged through the other cooling steam ejection holes 55 can be discharged from the cooling steam ejection holes 55 on the opening side, and the condensate water can be prevented from remaining in the recess 53.

  Further, as shown in FIG. 6, in the configuration shown in FIG. 5, a groove portion 70 is further formed in the circumferential direction on the inner peripheral surface of the recessed portion 53 provided with the inlet of the cooling steam ejection hole 55 on the opening side. May be. By providing the groove portion 70, the condensed water guided to the cooling steam ejection hole 55 on the opening side can be stored. Therefore, for example, even when the flow rate of the condensed water collected at the cooling steam ejection hole 55 on the opening side is large, the condensed water can be discharged without flowing out to the depression 43 side.

  In the configuration shown in FIGS. 5 and 6, an example in which the side surface of the recess portion 53 is formed so as to be inclined toward the cooling steam ejection hole 55 on the opening side is shown, but the configuration is not limited thereto. For example, the side surface of the recess 53 may be formed so as to be inclined toward the central cooling steam ejection hole 55 (the cooling steam ejection hole 55 of the second stage turbine stage).

  Moreover, although the example provided with the hollow part 53 which has the above-mentioned taper-shaped side surface in the structure of the steam turbine 10 of 1st Embodiment was shown here, the steam turbine of 2nd Embodiment mentioned above is shown. The configuration of the recess 53 can be applied to the configuration of 11. Even in this case, the same effects as those described above can be obtained.

  According to the embodiment described above, the temperature rise of the cooling steam until reaching the component to be cooled is suppressed, and it is possible to perform the cooling accurately.

  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, 12 ... Steam turbine, 20 ... Casing, 21 ... Diaphragm outer ring, 22 ... Diaphragm inner ring, 23 ... Stator blade, 24 ... Turbine rotor, 25 ... Moving blade, 26 ... Joint part, 27 ... Ground labyrinth seal, 28 , 70 ... Groove part, 29 ... Cooling steam supply pipe, 30 ... Communication hole, 31 ... Steam inlet pipe, 32 ... Steam flow path, 33 ... Labyrinth seal, 40, 50 ... Turbine rotor component, 41, 51 ... Rotor body 42, 52 ... Junction end face, 43,53 ... Depression, 44 ... Center through hole, 45 ... Cooling steam introduction hole, 53a ... Bottom part, 54 ... Wheel part, 54a ... Through hole, 55 ... Cooling steam ejection hole, 60 ... Cooling steam outlet.

Claims (10)

A steam turbine comprising a turbine rotor configured by joining at least two turbine rotor components in the axial direction of the turbine rotor,
One turbine rotor constituent member to be joined is composed of a cylindrical first rotor body,
The first rotor body is
A first recess formed in the center of the joint end face of the first rotor body;
A central through hole formed at the axial center of the first rotor body, with one end communicating with the first recess and the other end sealed;
An opening on the outer peripheral surface of the first rotor body, and a cooling steam introducing hole for guiding the introduced cooling steam to the central through hole,
The other turbine rotor constituent member to be joined is constituted by a cylindrical second rotor body portion including a wheel portion in which a moving blade is implanted, which is formed in the circumferential direction so as to protrude outward in the radial direction. And
The second rotor body is
A second recess formed in the center of the joint end face of the second rotor body,
A steam turbine comprising: an opening on an outer peripheral surface of the second rotor body portion; and a cooling steam ejection hole communicating with the second recess portion. A groove formed on the inner wall of the casing facing the opening of the cooling steam introduction hole formed on the outer peripheral surface of the first rotor body, and extending in the circumferential direction;
A seal portion provided on the inner side and the outer side of the steam turbine than the groove portion of the inner wall of the casing to prevent steam leakage;
The steam turbine according to claim 1, further comprising: a cooling steam introduction flow path that is formed in the casing and guides the cooling steam introduced from the outside to the groove portion.   The steam turbine according to claim 1 or 2, wherein an opening of the cooling steam ejection hole is formed immediately upstream of a root portion of the wheel portion.   The steam turbine according to claim 1, wherein an opening of the cooling steam ejection hole is formed at a tip portion of the wheel portion.   The steam according to any one of claims 1 to 4, wherein the wheel portion is formed in a plurality of stages in the turbine rotor axial direction, and the cooling steam ejection holes are formed corresponding to the wheel portions. Turbine.   The steam turbine according to claim 5, wherein a passage cross-sectional area and / or the number of the cooling steam ejection holes formed corresponding to each of the wheel portions is different for each of the corresponding wheel portions.   The steam turbine according to claim 5, wherein the cooling steam ejection hole formed corresponding to at least one of the wheel portions is formed to be inclined in a circumferential direction with respect to a radial direction of the turbine rotor.   The steam turbine according to any one of claims 1 to 7, wherein a cross-sectional shape perpendicular to a turbine rotor shaft in the first depression and the second depression is circular.   The steam turbine according to any one of claims 1 to 8, wherein an area of a cross section perpendicular to the turbine rotor shaft in the second recess portion is different along a turbine rotor shaft direction.   The steam turbine according to claim 1, wherein the turbine rotor constituent members to be joined are made of different materials.

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