WO2018101238A1

WO2018101238A1 - Steam turbine

Info

Publication number: WO2018101238A1
Application number: PCT/JP2017/042534
Authority: WO
Inventors: 伸次深尾; 椙下　秀昭; 松本　和幸; 秀樹間所; 祥弘桑村; 英治小西; 豊治西川
Original assignee: 三菱重工業株式会社
Priority date: 2016-11-29
Filing date: 2017-11-28
Publication date: 2018-06-07
Also published as: JP2018087532A

Abstract

This steam turbine is provided with an exhaust chamber, a moving vane provided to the upstream side of the exhaust chamber, and a stationary vane provided to the upstream side of the exhaust chamber. The exhaust chamber includes a casing and a flow guide provided inside the casing. The exhaust chamber has an exhaust chamber outlet on hte lower side, and the distribution of the length of the inner surface of the flow guide in a cross-section along the axial direction of the flow guide, and/or of the distance along the axial direction between the downstream end of the flow guide and an inner wall surface of the casing that faces this downstream end, is non-axisymmetric with respect to a vertical line passing through the center axis of the flow guide.

Description

Steam turbine

The present disclosure relates to a steam turbine exhaust chamber, a flow guide for a steam turbine exhaust chamber, and a steam turbine.

Steam from the turbine casing of the steam turbine is usually discharged from the steam turbine through the exhaust chamber. The exhaust chamber may be provided with a flow guide that guides the flow of steam from the inlet to the outlet of the exhaust chamber.

For example, Patent Document 1 discloses a tip flow guide provided on the top side (outer peripheral side) of a moving blade on the outlet side of the turbine final stage in the turbine exhaust chamber, and the base side (inner peripheral side) of the moving blade. A steam turbine is described in which a turbine exhaust passage is formed by a route flow guide and a bearing cone provided in the engine.

Further, in Patent Document 2, steam is discharged downward from the exhaust chamber, and a steam flow path formed by the outer peripheral flow guide and the inner peripheral bearing cone in the exhaust chamber is formed in the upper portion. In comparison, a steam turbine is described in which the lower part is formed longer.

JP 2004-150357 A Japanese Patent Laid-Open No. 11-200144

By the way, if a deviation occurs in the flow of steam in the exhaust chamber, fluid loss may occur, and the efficiency of the entire steam turbine may be reduced. In a typical exhaust chamber, since steam is discharged downward, the flow of steam is normally biased to the lower side of the exhaust chamber. In this regard, in the steam turbine described in Patent Document 2, in order to make the steam flow in the exhaust chamber uniform in the vertical direction, the lower part of the flow guide is formed longer (that is, the lower side of the flow guide). This increases the frictional resistance on the lower side of the steam flow path.
Here, it is considered that the steam flow in the exhaust chamber may be uneven even in directions other than the vertical direction. Therefore, further measures for achieving a uniform steam flow in the exhaust chamber of the steam turbine are desired.

In view of the above-described circumstances, at least one embodiment of the present invention aims to provide an exhaust chamber of a steam turbine, a flow guide, and a steam turbine including these, which can improve the efficiency of the steam turbine.

(1) An exhaust chamber of a steam turbine according to at least one embodiment of the present invention includes:
A casing,
A flow guide provided in the casing,
The exhaust chamber has an exhaust chamber outlet on the lower side,
The length of the inner surface of the flow guide in the cross section along the axial direction of the flow guide, or the axial direction between the downstream end of the flow guide and the inner wall surface of the casing facing the downstream end. At least one distribution of distances along the line is axisymmetric with respect to a vertical line passing through the central axis of the flow guide.

Since the steam flow entering the exhaust chamber from the turbine casing has a swirl component, there may be a deviation in flow not only in the vertical direction but also in the horizontal direction (horizontal direction) in the exhaust chamber.
In this regard, according to the configuration of (1) above, the distribution of at least one of the length of the inner surface of the flow guide or the distance between the downstream end of the flow guide and the inner wall surface of the flow guide Since it is non-symmetrical with respect to the vertical line passing through the flow line, it is possible to suppress the flow deviation caused by the swirl component of the steam flow in the exhaust chamber. That is, when the distribution of the length of the inner surface of the flow guide is axisymmetric with respect to the vertical line, the frictional resistance on the inner surface of the flow guide becomes asymmetric in the exhaust chamber, and the flow bias caused by the swirl component Can be suppressed. In addition, when the distribution of the distance between the downstream end of the flow guide and the inner wall surface of the casing is axisymmetric with respect to the vertical line, the cross-sectional area of the flow path formed between the flow guide and the inner wall surface of the casing Becomes asymmetrical in the exhaust chamber, and the flow deviation due to the swirl component can be suppressed. Therefore, the steam flow in the exhaust chamber can be made uniform to reduce the pressure loss of the fluid, thereby improving the efficiency of the entire steam turbine.

(2) In some embodiments, in the configuration of (1) above,
The angular coordinate system along the swirl direction has an angular range of 90 degrees or more and 270 degrees or less in the angular coordinate system with the circumferential angle position where the tangential direction of the swirl direction of the steam flow at the exhaust chamber inlet of the exhaust chamber is vertically upward. An angular position at which the length of the inner surface of the flow guide is a maximum value, or an angular position at which the distance between the downstream end of the flow guide and the inner wall surface of the casing is a minimum value. included.

As a result of intensive studies by the present inventors, it has been clarified that the steam flow tends to be biased in a region where the steam flow has a downward swirl component in the exhaust chamber. In this regard, according to the configuration of (2) above, in the angular coordinate system, in the angle range of 90 degrees or more and 270 degrees or less (that is, the region where the steam flow has a downward swirling component), the inner surface of the flow guide Since the length is the maximum value or the distance between the downstream end of the flow guide and the inner wall surface of the casing is the minimum value, flow deviation due to the swirl component of the steam flow in the exhaust chamber is effectively suppressed. be able to.

(3) In some embodiments, in the configuration of (2) above,
In the angular coordinate system, an angular position where the length of the inner surface of the flow guide becomes a maximum value within an angular range of 180 degrees or more and 270 degrees or less, or the downstream end of the flow guide and the inner portion of the casing. An angular position where the distance to the wall surface is a minimum value is included.

In an exhaust chamber having an exhaust chamber outlet on the lower side and discharging steam downward, the flow of steam is normally biased to the lower side of the exhaust chamber. In this regard, according to the configuration of (3) above, in the angular coordinate system, in the angle range of 90 degrees or more and 270 degrees or less (that is, the lower area of the area where the steam flow has a downward swirling component). The length of the inner surface of the flow guide is the maximum value, or the distance between the downstream end of the flow guide and the inner wall surface of the casing is the minimum value. The bias can be more effectively suppressed.

(4) In some embodiments, in any one of the above configurations (1) to (3),
The angular coordinate system along the swirl direction has an angular range of 0 degrees or more and 90 degrees or less in the angular coordinate system along the swirl direction, where the circumferential angle position where the tangential direction of the swirl direction of the steam flow at the exhaust chamber inlet of the exhaust chamber is vertically upward is 0 degrees. An angular position at which the length of the inner surface of the flow guide is a minimum value, or an angular position at which the distance between the downstream end of the flow guide and the inner wall surface of the casing is a maximum value. included.

As described above, the steam flow tends to be biased to a region where the steam flow has a downward swirl component in the exhaust chamber or to the lower side of the exhaust chamber. In this regard, according to the configuration of (4) above, in the angular coordinate system, the angular range of 0 ° or more and 90 ° or less that does not belong to either the region where the steam flow has a downward swirling component or the lower side of the exhaust chamber. The length of the inner surface of the flow guide is the minimum value, or the distance between the downstream end of the flow guide and the inner wall surface of the casing is the maximum value. Therefore, it is possible to more effectively suppress the flow deviation caused by the swirl component of the steam flow in the exhaust chamber.

(5) In some embodiments, in any one of the above configurations (1) to (4),
A distribution of positions in the axial direction of the downstream end of the flow guide is non-linearly symmetric with respect to a vertical line passing through the central axis of the flow guide.

The axial position of the downstream end of the flow guide is the length of the inner surface of the flow guide along the axial direction, or the distance along the axial direction between the downstream end of the flow guide and the inner wall surface of the casing. Related. Therefore, according to the configuration of (5) above, the position distribution in the axial direction of the downstream end of the flow guide is axisymmetric with respect to the vertical line passing through the central axis of the flow guide, so that friction on the inner surface of the flow guide Resistance or the cross-sectional area of the flow path formed between the flow guide and the inner wall surface of the casing becomes asymmetrical in the exhaust chamber, and the flow deviation due to the swirling component of the steam flow in the exhaust chamber can be suppressed. .

(6) In some embodiments, in the configuration of (5) above,
The inner wall surface of the casing is provided along a plane in which at least a region facing the flow guide is orthogonal to the axial direction.

According to the configuration of (6) above, the position distribution in the axial direction of the downstream end of the flow guide is axisymmetric with respect to the vertical line passing through the central axis of the flow guide, and the inner wall surface of the casing is at least the flow guide. Is provided along a plane perpendicular to the axial direction, the distribution of the distance between the downstream end of the flow guide and the inner wall surface of the casing is axisymmetric with respect to a vertical line passing through the central axis of the flow guide. Become. Therefore, the cross-sectional area of the flow path formed between the flow guide and the inner wall surface of the casing becomes asymmetrical in the exhaust chamber, and flow deviation due to the swirling component of the steam flow in the exhaust chamber can be suppressed.
Moreover, the structure of said (6) is obtained by applying the flow guide which has the characteristic of said (5) so that an axial direction may orthogonally cross with respect to the inner wall face of a casing. Therefore, even in an existing steam turbine plant, the flow guide having the feature (5) above is applied by replacement or the like, so that the cross-sectional area of the flow path formed between the flow guide and the inner wall surface of the casing can be reduced. As a result, it is possible to suppress the flow deviation caused by the swirl component of the steam flow in the exhaust chamber.

(7) In some embodiments, in any one of the configurations (1) to (6) above,
A bearing cone provided on the inner peripheral side of the flow guide in the casing and having a downstream end connected to the inner wall surface of the casing is further provided.

According to the configuration of (7) above, a steam flow path in the exhaust chamber can be formed by the flow guide and the bearing cone provided in the casing.

(8) A steam turbine according to at least one embodiment of the present invention includes:
The exhaust chamber according to any one of (1) to (7) above;
A moving blade provided upstream of the exhaust chamber;
A stationary blade provided on the upstream side of the exhaust chamber;
Is provided.

According to the configuration of the above (8), the distribution of at least one of the length of the inner surface of the flow guide or the distance between the downstream end of the flow guide and the inner wall surface of the flow guide is perpendicular to the central axis of the flow guide. Since it is non-linearly symmetrical with respect to the line, it is possible to suppress the flow deviation caused by the swirling component of the steam flow in the exhaust chamber. That is, when the distribution of the length of the inner surface of the flow guide is axisymmetric with respect to the vertical line, the frictional resistance on the inner surface of the flow guide becomes asymmetric in the exhaust chamber, and the flow bias caused by the swirl component Can be suppressed. In addition, when the distribution of the distance between the downstream end of the flow guide and the inner wall surface of the casing is axisymmetric with respect to the vertical line, the cross-sectional area of the flow path formed between the flow guide and the inner wall surface of the casing Becomes asymmetrical in the exhaust chamber, and the flow deviation due to the swirl component can be suppressed. Therefore, the steam flow in the exhaust chamber can be made uniform to reduce the pressure loss of the fluid, thereby improving the efficiency of the entire steam turbine.

(9) The flow guide according to at least one embodiment of the present invention is:
Used in the exhaust chamber of the steam turbine according to any one of (1) to (7) above.

According to the configuration of the above (9), the distribution of at least one of the length of the inner surface of the flow guide or the distance between the downstream end of the flow guide and the inner wall surface of the flow guide is expressed as a vertical line passing through the central axis of the flow guide. Since it is non-linearly symmetrical with respect to the line, it is possible to suppress the flow deviation caused by the swirling component of the steam flow in the exhaust chamber. That is, when the distribution of the length of the inner surface of the flow guide is axisymmetric with respect to the vertical line, the frictional resistance on the inner surface of the flow guide becomes asymmetric in the exhaust chamber, and the flow bias caused by the swirl component Can be suppressed. In addition, when the distribution of the distance between the downstream end of the flow guide and the inner wall surface of the casing is axisymmetric with respect to the vertical line, the cross-sectional area of the flow path formed between the flow guide and the inner wall surface of the casing Becomes asymmetrical in the exhaust chamber, and the flow deviation due to the swirl component can be suppressed. Therefore, the steam flow in the exhaust chamber can be made uniform to reduce the pressure loss of the fluid, thereby improving the efficiency of the entire steam turbine.

(10) The flow guide according to at least one embodiment of the present invention is:
A flow guide for an exhaust chamber of a steam turbine,
The length of the inner surface of the flow guide in a cross section along the axial direction of the flow guide is axisymmetric with respect to an arbitrary straight line orthogonal to the central axis of the flow guide.

According to the configuration of (10) above, the length of the inner surface of the flow guide is axisymmetric with respect to an arbitrary straight line orthogonal to the central axis of the flow guide, so that the flow guide is properly oriented with respect to the exhaust chamber. If it installs in, the deviation of the flow resulting from the swirling component of the steam flow in the exhaust chamber can be suppressed. For example, when the flow in the exhaust chamber is biased to the left side (angle range of 90 degrees or more and 270 degrees or less in the angle coordinate system described above), a region where the inner surface of the flow guide is relatively long is located on the left side of the exhaust chamber. By orienting the flow guide so as to be positioned, the frictional resistance on the inner surface of the flow guide becomes asymmetrical in the exhaust chamber, and the flow deviation due to the swirl component can be suppressed.

(11) In some embodiments, in the configuration of (10) above,
The distribution of the position in the axial direction of the downstream end of the flow guide having a large inner diameter among both end portions in the axial direction of the flow guide is axisymmetric with respect to an arbitrary straight line orthogonal to the central axis of the flow guide. .

According to the configuration of (11), since the distribution of the position in the axial direction of the downstream end of the flow guide is asymmetric with respect to an arbitrary straight line orthogonal to the central axis of the flow guide, the flow guide is exhausted in an appropriate orientation. If it is installed indoors, it is possible to suppress the flow bias caused by the swirl component of the steam flow in the exhaust chamber. For example, when the flow in the exhaust chamber is biased to the left side (angle range of 90 degrees or more and 270 degrees or less in the aforementioned angle coordinate system), the position in the axial direction of the downstream end of the flow guide is relatively downstream in the axial direction. By orienting the flow guide so that the region on the end side is located on the left side of the exhaust chamber, the frictional resistance on the inner surface of the flow guide becomes asymmetrical in the exhaust chamber, and the flow bias due to the swirl component can be suppressed. .

According to at least one embodiment of the present invention, there are provided an exhaust chamber of a steam turbine, a flow guide, and a steam turbine including these, which can improve the efficiency of the steam turbine.

It is a schematic sectional drawing along the axial direction of the steam turbine concerning one embodiment. It is a schematic sectional drawing (longitudinal sectional view) of an exhaust chamber concerning one embodiment. It is a schematic sectional drawing (cross-sectional view) of the exhaust chamber which concerns on one Embodiment. It is a graph which shows distribution of the length of the inner surface of the flow guide in the exhaust chamber shown in FIG. It is a schematic sectional drawing (cross-sectional view) of the exhaust chamber which concerns on one Embodiment. FIG. 6 is a schematic view of the flow guide as viewed from the side in the exhaust chamber shown in FIG. 5. It is a figure which shows distribution of the distance between the downstream end of the flow guide in the exhaust chamber shown in FIG. 5, and the inner wall face of the casing of an exhaust chamber.

Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described in the embodiments or shown in the drawings are not intended to limit the scope of the present invention, but are merely illustrative examples. Absent.

First, the whole structure of the steam turbine which concerns on some embodiment is demonstrated.
FIG. 1 is a schematic cross-sectional view along the axial direction of a steam turbine according to an embodiment. As shown in FIG. 1, the steam turbine 1 includes a rotor 2 rotatably supported by a bearing portion 6, a plurality of moving blades 8 attached to the rotor 2, and an inner side that accommodates the rotor 2 and the moving blades 8. A casing 10 and a plurality of stages of stationary blades 9 attached to the inner casing 10 so as to face the moving blade 8 are provided. An outer casing 12 is provided outside the inner casing 10.
In such a steam turbine 1, when steam is introduced into the inner casing 10 from the steam inlet 3, the steam is expanded and accelerated when passing through the stationary blade 9, and works on the moving blade 8. The rotor 2 is rotated.

Further, the steam turbine 1 includes an exhaust chamber 14. The exhaust chamber 14 is located downstream of the moving blade 8 and the stationary blade 9. That is, the moving blade 8 and the stationary blade 9 are provided on the upstream side of the exhaust chamber 14. The steam (steam flow S) that has passed through the moving blade 8 and the stationary blade 9 in the inner casing 10 flows into the exhaust chamber 14 from the exhaust chamber inlet 11, passes through the inside of the exhaust chamber 14, and below the exhaust chamber 14. It is discharged from the exhaust chamber outlet 13 provided on the side to the outside of the steam turbine 1.
A condenser (not shown) may be provided below the exhaust chamber 14. The steam that has finished working on the moving blade 8 in the steam turbine 1 may flow into the condenser from the exhaust chamber 14 via the exhaust chamber outlet 13.

Next, the configuration of the exhaust chamber 14 according to some embodiments will be described more specifically with reference to FIGS.
FIG. 2 is a schematic cross-sectional view of an exhaust chamber according to an embodiment. FIG. 2 is a schematic cross-sectional view along the axial direction of a flow guide (described later) of the exhaust chamber.
3 and 5 are schematic cross-sectional views of the exhaust chamber according to the embodiment, respectively, and are cross-sectional views along the line AA in FIG.
4 is a graph showing the distribution of the length L of the inner surface 20a of the flow guide 20 with respect to the circumferential angle position θ in the exhaust chamber 14 shown in FIG. 3 (that is, the circumferential angle in the exhaust chamber 14 shown in FIG. 3). It is a graph showing the relationship between the position θ and the length L of the inner surface 20a of the flow guide 20.
FIG. 6 is a schematic view of the flow guide 20 viewed from the side in the exhaust chamber 14 shown in FIG.
FIG. 7 is a graph showing the distribution of the distance D between the downstream end 20b of the flow guide 20 and the inner wall surface 15a of the casing 15 of the exhaust chamber 14 with respect to the circumferential angular position θ in the exhaust chamber 14 shown in FIG. FIG. 6 is a graph showing the relationship between the circumferential angular position θ in the exhaust chamber 14 shown in FIG. 5 and the distance D between the downstream end 20b of the flow guide 20 and the inner wall surface 15a of the casing 15 of the exhaust chamber 14). .
Here, the circumferential angle position θ described above is a circumferential angle position where the tangential direction of the swirl direction (see FIG. 3) of the steam flow S at the exhaust chamber inlet 11 (see FIG. 2) of the exhaust chamber 14 is vertically upward. An angular coordinate system along the turning direction of 0 degrees (see FIGS. 3 and 5; that is, in FIGS. 3 and 5, the right direction is 0 degrees around the central axis O of the flow guide 20 and is counterclockwise. Is the positive position).
Further, the downstream end 20b of the flow guide 20 is an end portion disposed on the downstream side of the steam flow among both end portions in the axial direction of the flow guide 20, and means an end portion having a larger inner diameter.

As shown in FIGS. 1, 2, 4, and 5, the exhaust chamber 14 according to some embodiments includes a casing 15 and a bearing cone 16 provided so as to cover the bearing portion 6 in the casing 15. A flow guide 20 provided on the outer peripheral side of the bearing cone 16 in the casing 15. That is, the bearing cone 16 is provided on the inner peripheral side of the flow guide 20 in the casing 15. As shown in FIG. 2, the downstream end 16 a of the bearing cone 16 is connected to the inner wall surface 15 a of the casing 15.
The casing 15 of the exhaust chamber 14 may form at least a part of the outer casing 12 of the steam turbine 1 as shown in FIG.

The exhaust chamber 14 has an exhaust chamber outlet 13 on the lower side, and steam is discharged from the steam turbine 1 through the exhaust chamber outlet 13.

An annular diffuser passage 18 (steam passage) is formed in the casing 15 by the bearing cone 16 and the flow guide 20.
The diffuser passage 18 has a shape in which the cross-sectional area gradually increases. When the high-speed steam flow S that has passed through the rotor blade 8A in the final stage of the steam turbine 1 flows into the diffuser passage 18, the steam flow S is decelerated. The kinetic energy is converted into pressure (static pressure recovery).

In some embodiments, the length of the inner surface 20a of the flow guide 20 along the axial direction (the direction of the central axis O) of the flow guide 20, or the downstream end 20b of the flow guide 20 and the downstream end 20b At least one of the distances along the axial direction of the flow guide 20 between the opposing inner wall surface 15a of the casing 15 is axisymmetric with respect to a vertical line passing through the central axis O of the flow guide 20. As shown in FIGS. 1 to 3, 5, and 6, the center axis O of the flow guide 20 may exist on the same straight line as the center axis of the rotor 2, or the bearing cone 16 It may exist on the same straight line as the central axis.

For example, in the embodiment shown in FIG. 3, the distribution of the length L (see FIG. 2) of the inner surface 20 a of the flow guide 20 along the axial direction of the flow guide 20 is a vertical line passing through the central axis O of the flow guide 20. It is non-linearly symmetric with respect to Lv (that is, left-right asymmetric).

This can be explained, for example, from the following. That is, as shown in the graph of FIG. 4, in the embodiment shown in FIG. 3, in the angle coordinate system described above, the angular position θ ranges from 0 degrees to 90 degrees and from 270 degrees to 360 degrees (that is, right In the half portion, the length L of the inner surface 20a described above changes in the range of L _{min to} L ₂₇₀ , whereas the angular position θ is in the range of 90 degrees to 270 degrees (that is, the left half). Part), the length L of the inner surface 20a described above changes in the range of L _min or more and L _max or less. However, in the graph of FIG. 4, L _min is the minimum value of the length of the inner surface 20a, L _max is the maximum value of the length of the inner surface 20a, and L ₂₇₀ is when the angular position θ is 270 degrees. This is the length of the inner surface 20a (where L _min <L ₂₇₀ <L _max ).

Further, for example, in the embodiment shown in FIGS. 5 and 6, the distance along the axial direction of the flow guide 20 between the downstream end 20 b of the flow guide 20 and the inner wall surface 15 a of the casing 15 facing the downstream end 20 b. The distribution of D (see FIG. 6) is non-axisymmetric (that is, left-right asymmetric) with respect to the vertical line Lv passing through the central axis O of the flow guide 20.

This can be explained, for example, from the following. That is, as shown in the graph of FIG. 7, in the embodiment shown in FIGS. 5 and 7, in the angle coordinate system (see FIG. 5), the angular position θ is 0 degree or more and 90 degrees or less and 270 degree or more and 360 degrees. In the range of degrees or less (that is, the right half), the distance D changes in the range of D ₂₇₀ or more and D _max or less, whereas the angular position θ is in the range of 90 degrees or more and 270 degrees or less (that is, In the left half), the above-mentioned distance D changes in the range of D _{min to} D _max . However, in the graph of FIG. 7, D _min is the minimum value of the above-mentioned distance D, D _max is the maximum value of the above-mentioned distance D, and D ₂₇₀ is the above-mentioned distance when the angular position θ is 270 degrees. D (where D _min <D ₂₇₀ <D _max ).

In some embodiments, the distribution of the length L (see FIG. 2) of the inner surface 20a of the flow guide 20 along the axial direction of the flow guide 20, the downstream end 20b of the flow guide 20, and the downstream Both of the distribution of the distance D (see FIG. 6) along the axial direction of the flow guide 20 between the inner wall surface 15a of the casing 15 facing the end 20b are not related to the vertical line Lv passing through the central axis O of the flow guide 20. It may be line symmetric (that is, left / right asymmetric).

Since the steam flow S passing through the stationary blade 9 and the moving blade 8 of the steam turbine 1 and entering the exhaust chamber 14 has a swirling component, not only in the vertical direction but also in the horizontal direction (horizontal direction) in the exhaust chamber 14. In some cases, the flow may be biased.
In this regard, as in the embodiment shown in FIG. 3 or FIGS. 5 to 6, the length L of the inner surface 20a of the flow guide 20 or the distance between the downstream end 20b of the flow guide 20 and the inner wall surface 15a of the casing 15 is used. The distribution of at least one of the distances D is non-axisymmetric with respect to the vertical line Lv passing through the central axis O of the flow guide 20, thereby suppressing the flow bias due to the swirl component of the steam flow S in the exhaust chamber 14. can do.

That is, as in the embodiment shown in FIG. 3, when the distribution of the length L of the inner surface 20a of the flow guide 20 is axisymmetric with respect to the vertical line Lv, the frictional resistance on the inner surface 20a of the flow guide 20 is It becomes asymmetrical in the exhaust chamber 14, and the deviation of the flow caused by the swirl component can be suppressed.
In addition, as in the embodiment shown in FIGS. 5 to 6, the distribution of the distance D between the downstream end 20b of the flow guide 20 and the inner wall surface 15a of the casing 15 is axisymmetric with respect to the vertical line Lv. In addition, the cross-sectional area of the flow path (diffuser passage 18) formed between the flow guide 20 and the inner wall surface 15a of the casing 15 becomes asymmetric in the exhaust chamber, and the flow deviation due to the swirling component can be suppressed.
Therefore, the steam flow in the exhaust chamber 14 is made uniform to reduce the pressure loss of the fluid, thereby improving the efficiency of the steam turbine 1 as a whole.

In some embodiments, in the above-described angular coordinate system, as in the embodiment illustrated in FIG. 3, for example, the flow guide 20 is in an angle range (that is, the left half) in which the angular position θ is 90 degrees or more and 270 degrees or less. May include an angular position where the length L of the inner surface 20a is the maximum value L _max , or the angular position θ is not less than 90 degrees and not more than 270 degrees, for example, as in the embodiment shown in FIGS. May include an angular position where the distance D between the downstream end 20b of the flow guide 20 and the inner wall surface 15a of the casing 15 is the minimum value _Dmin .

In the exhaust chamber 14, the region where the steam flow S has a downward swirl component, that is, in the embodiment shown in FIG. 3 or FIG. 5, the circumferential angular position θ is 90 degrees or more and 270 degrees or less in the angular coordinate system. It became clear that the steam flow tends to be biased in the angular range (left half).
In this regard, in the angle coordinate system described above, the length L of the inner surface 20a of the flow guide 20 is the maximum value L _max or the downstream end 20b of the flow guide 20 and the casing 15 in an angle range of 90 degrees or more and 270 degrees or less. If the distance D between the inner wall surface 15a and the inner wall surface 15a takes the minimum value _Dmin , it is possible to effectively suppress the deviation of the flow due to the swirling component of the steam flow in the exhaust chamber 14.

In some embodiments, in the above-described angular coordinate system, as in the embodiment illustrated in FIG. 3, for example, the angular position θ is in an angle range of 180 degrees or more and 270 degrees or less (that is, the lower left portion). An angular position where the length L of the inner surface 20a is the maximum value L _max may be included, or the angular position θ is not less than 180 degrees and not more than 270 degrees as in the embodiment shown in FIGS. The angular range (that is, the lower left portion) may include an angular position where the distance D between the downstream end 20b of the flow guide 20 and the inner wall surface 15a of the casing 15 is the minimum value _Dmin .

In the exhaust chamber 14 having the exhaust chamber outlet 13 on the lower side and discharging the steam downward as in the embodiment shown in FIG. 3 or FIG. 5, the flow of the steam is usually below the exhaust chamber 14. Biased. In this regard, in the angle coordinate system described above, in the angle range of 90 degrees or more and 270 degrees or less (that is, the lower area of the area where the steam flow has a downward swirl component), the inner surface 20a of the flow guide 20 If the length L is the maximum value L _max or the distance D between the downstream end 20b of the flow guide 20 and the inner wall surface 15a of the casing 15 is the minimum value D _min , the steam flow in the exhaust chamber 14 will be described. The deviation of the flow due to the swirling component can be more effectively suppressed.

In the embodiment shown in FIG. 3, as shown in the graph of FIG. 4, the length L of the inner surface 20 a of the flow guide 20 is the maximum value L at θ ₁ where the angular position θ is 180 degrees or more and 270 degrees or less. _max . In the embodiment shown in FIGS. 5 and 6, as shown in the graph of FIG. 7, when the angular position θ is θ ₂ of 180 degrees or more and 270 degrees or less, the downstream end 20 b of the flow guide 20 and the casing 15 The distance D to the wall surface 15a is the minimum value _Dmin .

In some embodiments, in the above-described angular coordinate system, the length L of the inner surface 20a in the range where the angular position θ is in the range of 0 ° to 90 ° and 270 ° to 360 ° (that is, the right half). The average value is smaller than the average value of the length L of the inner surface 20a in the range where the angular position θ is 90 degrees or more and 270 degrees or less (that is, the left half), or the angular position θ is 0 degrees or more and 90 degrees. The average value of the distance D in the range of 270 degrees or more and 360 degrees or less (that is, the right half portion) is the average value of the distance D in the range where the angular position θ is 90 degrees or more and 270 degrees or less (that is, the left half portion). Greater than average value.

In some embodiments, in the above-described angular coordinate system, the average value of the length L of the inner surface 20a in the range where the angular position θ is 270 degrees or more and 360 degrees or less (that is, the lower right portion) is the angular position The angle θ is smaller than the average value of the length L of the inner surface 20a in the range of 180 degrees or more and 270 degrees or less (that is, the lower left portion), or the angle position θ is in the range of 270 degrees or more and 360 degrees or less (that is, the right The average value of the distance D in the lower part is smaller than the average value of the distance D in the range where the angular position θ is 180 degrees or more and 270 degrees or less (that is, the lower left part).

In some embodiments, for example, as in the embodiment shown in FIG. 3, the length of the inner surface 20 a of the flow guide 20 is within an angular range in which the angular position θ is not less than 0 degrees and not more than 90 degrees in the angular coordinate system described above. An angle position where L is a minimum value L _min may be included, or the flow guide is in an angle range where the angle position θ is 0 degree or more and 90 degrees or less, for example, as in the embodiment shown in FIGS. The angle position where the distance D between the downstream end 20b of the 20 and the inner wall surface 15a of the casing 15 becomes the maximum value _Dmax may be included.

As described above, the length L of the inner surface 20a of the flow guide 20 is the smallest in an angle range of 0 degrees to 90 degrees that does not belong to either the region where the steam flow has a downward swirl component or the lower side of the exhaust chamber. If the value L _min or the distance D between the downstream end 20b of the flow guide 20 and the inner wall surface 15a of the casing 15 takes the maximum value D _max , it results from the swirl component of the steam flow in the exhaust chamber 14. The uneven flow can be more effectively suppressed.

In some embodiments, the position distribution in the axial direction of the downstream end 20 b of the flow guide 20 is axisymmetric with respect to a vertical line passing through the central axis O of the flow guide 20.
For example, in the embodiment shown in FIGS. 5 to 6, when attention is paid to the axial position of the downstream end 20b in the region below the central axis O in FIG. 6, the vertical line Lv passing through the central axis O (see FIG. 5). ) On the left side (portion where the downstream end 20b is indicated by a solid line) and the right side (portion where the downstream end 20b is indicated by a broken line) from the vertical line Lv, Are not overlapping. Therefore, in this embodiment, the distribution of the position of the downstream end 20b in the axial direction is axisymmetric with respect to the vertical line Lv.

As described above, the distribution of the position in the axial direction of the downstream end 20b of the flow guide 20 is axisymmetric with respect to the vertical line Lv passing through the central axis O of the flow guide 20, so that friction on the inner surface 20a of the flow guide 20 is achieved. Resistance or the cross-sectional area of the flow path (diffuser passage 18) formed between the flow guide 20 and the inner wall surface 15a of the casing 15 becomes asymmetric in the exhaust chamber 14, and the swirl of the steam flow in the exhaust chamber 14 It is possible to suppress the uneven flow due to the components.

In the embodiment shown in FIGS. 5 to 6, the inner wall surface 15a of the casing 15 is provided along a plane in which at least a region facing the flow guide 20 is orthogonal to the axial direction of the flow guide 20 (the direction of the central axis O). It has been.
In this case, the distribution of the position of the downstream end 20b of the flow guide 20 in the axial direction is axisymmetric with respect to the vertical line Lv passing through the central axis O of the flow guide 20, and the downstream end 20b of the flow guide 20 and the casing. The distribution of the distance D between the 15 inner wall surfaces 15a is axisymmetric with respect to the vertical line Lv passing through the central axis O of the flow guide 20. Therefore, the cross-sectional area of the flow path (diffuser passage 18) formed between the flow guide 20 and the inner wall surface 15a of the casing 15 becomes asymmetric in the exhaust chamber 14, and the swirl component of the steam flow in the exhaust chamber 14 The resulting flow bias can be suppressed.

Further, the flow guide 20 having a feature that the position distribution in the axial direction of the downstream end 20b is axisymmetric with respect to a vertical line passing through the central axis O is axially oriented with respect to the inner wall surface 15a of the casing 15. By applying so as to be orthogonal to each other, the inner wall surface 15a of the casing 15 has an exhaust gas provided along a plane in which at least a region facing the flow guide 20 is orthogonal to the axial direction of the flow guide 20 (the direction of the central axis O). Chamber 14 can be obtained.
Therefore, even in an existing steam turbine plant, a flow path (diffuser passage 18) formed between the flow guide 20 and the inner wall surface 15a of the casing 15 by applying the flow guide 20 having the above-described characteristics by replacement or the like. ) In the exhaust chamber 14 can be made asymmetrical in the left-right direction, and flow deviation due to the swirling component of the steam flow in the exhaust chamber 14 can be suppressed.

In some embodiments, the flow guide 20 as a part of the exhaust chamber 14 of the steam turbine 1 has a length L of the inner surface 20a of the flow guide 20 in a cross section along the axial direction of the flow guide 20 (see FIG. 2). ) Is axisymmetric with respect to an arbitrary straight line orthogonal to the central axis O of the flow guide 20.
Thus, if the length L of the inner surface 20a of the flow guide 20 is axisymmetric with respect to an arbitrary straight line orthogonal to the central axis O of the flow guide 20, the flow guide 20 is in an appropriate orientation and the exhaust chamber 14 is aligned. By installing in, the deviation of the flow resulting from the swirling component of the steam flow in the exhaust chamber 14 can be suppressed.

Further, in some embodiments, the position distribution in the axial direction of the downstream end 20b having the larger inner diameter among the both ends in the axial direction of the flow guide 20 is not related to an arbitrary straight line orthogonal to the central axis O of the flow guide 20. It is line symmetric.

Thus, since the distribution of the position in the axial direction of the downstream end 20b of the flow guide 20 is asymmetric with respect to an arbitrary straight line orthogonal to the central axis O of the flow guide 20, the flow guide 20 is placed in the exhaust chamber 14 in an appropriate orientation. If installed inside, it is possible to suppress the deviation of the flow due to the swirl component of the steam flow in the exhaust chamber 14.

It should be noted that the strength of the swirling flow in the exhaust chamber 14 and the angular position θ at which the flow deviation increases in the exhaust chamber 14 can vary depending on the operating conditions of the steam turbine. For example, the strength of the swirl flow varies depending on the degree of vacuum, and the degree of vacuum depends on the temperature. Therefore, the strength of the swirl flow can vary depending on the temperature of the place where the steam turbine is installed. Therefore, the flow guide 20 may be designed so as to have an appropriate shape according to the operating conditions of the steam turbine (for example, the temperature at the installation location). For example, a cross section along the axial direction of the flow guide 20 The distribution of the length L of the inner surface 20a of the flow guide 20 in the inside, or the distance D along the axial direction between the downstream end 20b of the flow guide 20 and the inner wall surface 15a of the casing 15 facing the downstream end 20b. Or the like may be determined.

As mentioned above, although embodiment of this invention was described, this invention is not limited to embodiment mentioned above, The form which added the deformation | transformation to embodiment mentioned above, and the form which combined these forms suitably are included.

In this specification, an expression representing a relative or absolute arrangement such as “in a certain direction”, “along a certain direction”, “parallel”, “orthogonal”, “center”, “concentric” or “coaxial”. Represents not only such an arrangement strictly but also a state of relative displacement with tolerance or an angle or a distance to obtain the same function.
For example, an expression indicating that things such as “identical”, “equal”, and “homogeneous” are in an equal state not only represents an exactly equal state, but also has a tolerance or a difference that can provide the same function. It also represents the existing state.
In this specification, expressions representing shapes such as quadrangular shapes and cylindrical shapes not only represent shapes such as quadrangular shapes and cylindrical shapes in a strict geometric sense, but also within a range where the same effects can be obtained. In addition, a shape including an uneven portion or a chamfered portion is also expressed.
In this specification, the expression “comprising”, “including”, or “having” one constituent element is not an exclusive expression for excluding the existence of another constituent element.

DESCRIPTION OF SYMBOLS 1 Steam turbine 2 Rotor 3 Steam inlet 6 Bearing part 8 Rotor blade 8A Final stage rotor blade 9 Stator blade 10 Inner casing 11 Exhaust chamber inlet 12 Outer casing 13 Exhaust chamber outlet 14 Exhaust chamber 15 Casing 15a Casing inner wall surface 16 Bearing cone 16a Downstream end 18 of bearing cone 18 Diffuser passage 20 Flow guide 20a Inner surface 20b of flow guide Downstream end Lv of flow guide Vertical line O Center axis

Claims

A steam turbine comprising: an exhaust chamber; a moving blade provided upstream of the exhaust chamber; and a stationary blade provided upstream of the exhaust chamber,
The exhaust chamber is
A casing,
A flow guide provided in the casing,
The exhaust chamber has an exhaust chamber outlet on the lower side,
The length of the inner surface of the flow guide in the cross section along the axial direction of the flow guide, or the axial direction between the downstream end of the flow guide and the inner wall surface of the casing facing the downstream end. A steam turbine characterized in that the distribution of at least one of the distances along the axis is axisymmetric with respect to a vertical line passing through the central axis of the flow guide.
The angular coordinate system along the swirl direction has an angular range of 90 degrees or more and 270 degrees or less in the angular coordinate system with the circumferential angle position where the tangential direction of the swirl direction of the steam flow at the exhaust chamber inlet of the exhaust chamber is vertically upward. An angular position at which the length of the inner surface of the flow guide is a maximum value, or an angular position at which the distance between the downstream end of the flow guide and the inner wall surface of the casing is a minimum value. The steam turbine according to claim 1, wherein the steam turbine is included.
In the angular coordinate system, an angular position where the length of the inner surface of the flow guide becomes a maximum value within an angular range of 180 degrees or more and 270 degrees or less, or the downstream end of the flow guide and the inner portion of the casing. The steam turbine according to claim 2, wherein an angular position at which the distance to the wall surface is a minimum value is included.
The angular coordinate system along the swirl direction has an angular range of 0 degrees or more and 90 degrees or less in the angular coordinate system along the swirl direction, where the circumferential angle position where the tangential direction of the swirl direction of the steam flow at the exhaust chamber inlet of the exhaust chamber is vertically upward is 0 degrees. An angular position at which the length of the inner surface of the flow guide is a minimum value, or an angular position at which the distance between the downstream end of the flow guide and the inner wall surface of the casing is a maximum value. The steam turbine according to claim 1, wherein the steam turbine is included.
The distribution of the position in the axial direction of the downstream end of the flow guide is axisymmetric with respect to a vertical line passing through the central axis of the flow guide. The described steam turbine.
The steam turbine according to claim 5, wherein the inner wall surface of the casing has at least a region facing the flow guide along a plane orthogonal to the axial direction.
7. The bearing cone according to claim 1, further comprising a bearing cone provided on an inner peripheral side of the flow guide in the casing and having a downstream end connected to the inner wall surface of the casing. The described steam turbine.