Patent Grant
11149588
The present disclosure relates to an exhaust chamber of a steam turbine, a flow guide for a steam turbine exhaust chamber, and a steam turbine.
Steam from a turbine casing of a steam turbine is normally discharged from the steam turbine via an exhaust chamber. In the exhaust chamber, a fluid loss is caused by characteristics of a steam flow, a shape of an internal, or the like. Therefore, a configuration for reducing the fluid loss in the exhaust chamber is proposed.
For example, Patent Document 1 discloses a steam turbine. The steam turbine applies swirl to a tip flow in a diffuser flow passage of an exhaust chamber by disposing a deflection member on a flow guide forming the diffuser flow passage, and then reduces a loss when the tip flow and a steam main flow are mixed.
In addition, Patent Document 2 discloses a steam turbine which has an exhaust chamber defined by an outer turbine casing and an inner turbine casing of a turbine, and is provided with a rectifier unit on a lower side of a lower half part of the inner turbine casing. Thus, the steam turbine prevents a steam flow toward an outlet below the exhaust chamber from separating on a lower side of the inner turbine casing.
Patent Document 1: JP2011-220125A
Patent Document 2: JP2003-27905A
The steam turbines disclosed in Patent Document 1 and Patent Document 2 are expected to reduce the loss in the exhaust chamber by the deflection member and the rectifier unit disposed in the exhaust chamber.
However, a further measure to reduce the fluid loss in the exhaust chamber of the steam turbine is desired.
In view of the above, an object of at least one embodiment of the present invention is to provide an exhaust chamber of a steam turbine, a flow guide for a steam turbine exhaust chamber, and a steam turbine which can reduce the fluid loss in the exhaust chamber.
(1) An exhaust chamber of a steam turbine according to at least one embodiment of the present invention includes a casing, an inner flow guide portion disposed in the casing so as to define an outer boundary of a diffuser passage communicating with an outlet of a last stage blade in the steam turbine, and an outer flow guide portion disposed on an outer peripheral side of the inner flow guide portion in the casing. The exhaust chamber has an exhaust chamber outlet on a lower side thereof. The outer flow guide portion is disposed at least around an upper half region of the inner flow guide portion.
A steam flow passing through the diffuser passage may form separation vortices on a back side of the inner flow guide portion (an opposite side to the diffuser passage across the inner flow guide portion) forming the diffuser passage. In this regard, with the above configuration (1), since the outer flow guide portion is disposed at least around the upper half region of the inner flow guide portion, the outer flow guide portion guides a steam flow passing through the diffuser passage and tending to circulate back into the upper half region of the inner flow guide portion. Thus, it is possible to reduce the separation vortices of the steam flow. Thus, it is possible to reduce a fluid loss in the exhaust chamber and to improve efficiency in the steam turbine as a whole.
(2) In some embodiments, in the above configuration (1), at least a part of a connection portion between the outer flow guide portion and the upper half region of the inner flow guide portion has a curved shape in a cross section along an axial direction of the inner flow guide portion.
With the above configuration (2), since the steam flow tending to circulate back into the upper half region of the inner flow guide portion flows to the outer flow guide portion via the connection portion having the curved shape, it is possible to reduce the separation vortices of the steam flow even further. Thus, it is possible to reduce a fluid loss in the exhaust chamber more effectively.
(3) In some embodiments, in the above configuration (1) or (2), the outer flow guide portion is disposed on an outer peripheral side of the inner flow guide portion over an entire periphery of the inner flow guide portion.
With the above configuration (3), since the outer flow guide portion is disposed on the entire periphery of the inner flow guide portion, it is possible to suppress even a separation vortex of a steam flow directed downward along the outer flow guide portion after passing through the diffuser passage and circulating back into the upper half region of the inner flow guide portion.
(4) In some embodiments, in the above configuration (3), an angular position around a center axis of the inner flow guide portion at which a radial distance between a first intersection point of the inner flow guide portion with a line segment extending radially from the center axis and a second intersection point of the outer flow guide portion with the line segment becomes maximum is included in an angular range on a lower side of a horizontal plane including the center axis.
Since the above-described exhaust chamber has the exhaust chamber outlet on the lower side, flows directed downward as a whole are mainly formed in the exhaust chamber. In this regard, with the above configuration (4), since an interval between the inner flow guide portion and the outer flow guide portion (the distance between the first intersection point and the second intersection point) becomes maximum in a lower half region, it is possible to effectively suppress the separation vortices in correspondence with the downward flows in the exhaust chamber.
(5) In some embodiments, in the above configuration (4), the angular position at which the radial distance becomes maximum is located at a downstream side in a swirl direction of a steam flow in an exhaust chamber inlet of the exhaust chamber compared to an angular position extending vertically downward through the center axis.
A flow in the exhaust chamber is influenced by a rotation of a turbine rotor, and thus may include a swirl component. In this case, flow deflection owing to the swirl component occurs in the exhaust chamber. In this regard, with the above configuration (5), an angular position at which the interval between the inner flow guide portion and the outer flow guide portion (the distance between the first intersection point and the second intersection point) becomes maximum is displaced to the downstream side in the swirl direction, giving the outer flow guide portion a shape considering the flow deflection and making it possible to reduce a pressure loss.
(6) In some embodiments, in any one of the above configurations (3) to (5), the exhaust chamber of the steam turbine further includes an intermediate flow guide portion disposed below the inner flow guide portion so as to suspend from a lower half region of the inner flow guide portion toward a lower half region of the outer flow guide portion, and the intermediate flow guide portion connects the lower half region of the inner flow guide portion and the lower half region of the outer flow guide portion.
With the above configuration (6), the intermediate flow guide portion which connects the lower half region of the inner flow guide portion and the lower half region of the outer flow guide portion appropriately guides a downward flow flowing out of the lower half region of the inner flow guide portion. It is possible to effectively suppress the separation vortices below the inner flow guide portion.
(7) In some embodiments, in the above configuration (6), the intermediate flow guide portion is oblique with respect to a vertical direction to be directed to an upstream side of a steam flow in the diffuser passage toward downward in a cross section along an axial direction of the inner flow guide portion.
With the above configuration (7), a cross-sectional area of the steam flow passage formed by the intermediate flow guide portion is gradually expanded downward, promoting static pressure recovery in the exhaust chamber. Thus, it is possible to reduce a loss in the exhaust chamber more effectively.
(8) In some embodiments, in any one of the above configurations (3) to (7), in a cross section along an orthogonal plane of a center axis of the inner flow guide portion, a lower end part of the outer flow guide portion includes a first discontinuous point on a first surface of the outer flow guide portion facing an inner surface of a first side wall of the casing and a second discontinuous point on a second surface of the outer flow guide portion facing an inner surface of a second side wall of the casing on an opposite side to the first side wall.
With the above configuration (8), at the first discontinuous point and the second discontinuous point of the lower end part of the outer flow guide portion, flows guided by the outer flow guide portion toward downward easily separate from each other, respectively. Therefore, flow separation positions in the lower end part of the outer flow guide portion are fixed (stabilized), making it possible to reduce an unsteady loss.
(9) In some embodiments, in the above configuration (8), the first discontinuous point and the second discontinuous point have different height positions from one another.
With the above configuration (9), since the first discontinuous point and the second discontinuous point are disposed at the different height positions, the flow separation positions in the lower end part of the outer flow guide portion become asymmetric, making it possible to suppress occurrence of an unsteady vortex. Thus, it is possible to reduce the unsteady loss more effectively.
(10) In some embodiments, in any one of the above configurations (1) to (9), an upper half region of the outer flow guide portion is displaced from a center axis of the inner flow guide portion such that a distance between an inner wall surface of the casing and the upper half region of the outer flow guide portion on a downstream side in a swirl direction of a steam flow in an exhaust chamber inlet of the exhaust chamber is larger than the distance between the inner wall surface of the casing and the upper half region of the outer flow guide portion on an upstream side in the swirl direction.
In the exhaust chamber, the steam flow tends to deflect on the downstream side in the swirl direction in the upper half region. In this regard, with the above configuration (10), the upper half region of the outer flow guide portion is displaced from the center axis of the inner flow guide portion such that a flow passage cross-sectional area on the downstream side in the swirl direction of the steam flow increases in the upper half region of the exhaust chamber. Therefore, it is possible to reduce the pressure loss of the fluid in the exhaust chamber and to improve efficiency in the steam turbine as a whole more effectively.
(11) A steam turbine according to at least one embodiment of the present invention includes the exhaust chamber according to any one of the above (1) to (10), a rotor blade disposed on an upstream side of the exhaust chamber, and a stator vane disposed on the upstream side of the exhaust chamber.
With the above configuration (11), since the outer flow guide portion is disposed at least around the upper half region of the inner flow guide portion, the outer flow guide portion guides a steam flow passing through the diffuser passage and tending to circulate back into the upper half region of the inner flow guide portion. Thus, it is possible to reduce the separation vortices of the steam flow. Thus, it is possible to reduce a fluid loss in the exhaust chamber and to improve efficiency in the steam turbine as a whole.
(12) A flow guide for an exhaust chamber of a steam turbine according to at least one embodiment of the present invention includes an inner flow guide portion, and an outer flow guide portion disposed on an outer peripheral side of the inner flow guide portion.
The outer flow guide portion is disposed on the outer peripheral side of the inner flow guide portion over an entire periphery of the inner flow guide portion.
With the above configuration (12), since the outer flow guide portion is disposed over the entire periphery of the inner flow guide portion, the outer flow guide portion guides a steam flow passing through a diffuser passage and tending to circulate back into an upper half region of the inner flow guide portion when the flow guide is applied to the exhaust chamber of the steam turbine. Thus, it is possible to reduce the separation vortices of the steam flow, and to suppress even a separation vortex of a steam flow directed downward along the outer flow guide portion after passing through the diffuser passage and circulating back into the upper half region of the inner flow guide portion. Thus, it is possible to effectively reduce a fluid loss in the exhaust chamber and to improve efficiency in the steam turbine as a whole.
According to at least one embodiment of the present invention, provided are an exhaust chamber of a steam turbine, a flow guide for a steam turbine exhaust chamber, and a steam turbine which can reduce a fluid loss in the exhaust chamber.
Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It is intended, however, that unless particularly identified, dimensions, materials, shapes, relative positions and the like of components described in the embodiments shall be interpreted as illustrative only and not intended to limit the scope of the present invention.
First, an overall configuration of a steam turbine according to some embodiments will be described.
In such a steam turbine 1, if steam is introduced from a steam inlet 3 to the inner casing 10, the steam expands and increases in speed when passing through the stator vane 9, performs work on the rotor blades 8, and rotates the rotor 2.
In addition, the steam turbine 1 includes an exhaust chamber 14. The exhaust chamber 14 is positioned on a downstream side of the rotor blades 8 and stator vanes 9. That is, the rotor blades 8 and the stator vanes 9 are disposed on an upstream side of the exhaust chamber 14. Steam having passed through the rotor blades 8 and the stator vanes 9 in the inner casing 10 (steam flows S) flows into the exhaust chamber 14 from an exhaust chamber inlet 11, and is discharged to the outside of the steam turbine 1 from an exhaust chamber outlet 13 disposed on a lower side of the exhaust chamber 14 through the inside of the exhaust chamber 14.
A condenser (not shown) may be disposed below the exhaust chamber 14. The steam having finished performing work on the rotor blades 8 in the steam turbine 1 may flow into the condenser from the exhaust chamber 14 via the exhaust chamber outlet 13.
Next, with reference to
As shown in
As shown in
The exhaust chamber 14 has the exhaust chamber outlet 13 on the lower side. Steam is discharged from the steam turbine 1 via the exhaust chamber outlet 13.
Inside the casing 15, an annular diffuser passage 18 (steam flow passage) is formed by the bearing cone 16 and the flow guide 20.
The diffuser passage 18 communicates with a last stage blade outlet 17 of the steam turbine 1 and has a shape with a gradually increasing cross-sectional area. Then, if the high-speed steam flow S having passed through a last stage rotor blade 8A of the steam turbine 1 flows into the diffuser passage 18 via the last stage blade outlet 17, the steam flow S is decreased in speed, and kinetic energy thereof is converted into a pressure (static pressure recovery).
As shown in
The inner flow guide portion 22 is configured to guide the steam flows S by its inner surface 22a (a surface forming the diffuser passage 18 by facing the bearing cone 16; see
Then, the outer flow guide portion 24 is disposed at least around an upper half region 22A of the inner flow guide portion 22. That is, in the exemplary embodiments shown in
In the present specification, a region on an upper side of a center axis O of the inner flow guide portion 22 is referred to as an upper half region, and a region on a lower side of the center axis O of the inner flow guide portion 22 is referred to as a lower half region. In addition, the upper half region 22A and a lower half region 22B of the inner flow guide portion 22 are portions positioned in the upper half region and the lower half region described above of the inner flow guide portion 22, respectively. The upper half region 24A and a lower half region 24B of the outer flow guide portion 24 are portions positioned in the upper half region and the lower half region described above of the outer flow guide portion 24, respectively.
As shown in
The flow guide 20 disposed in the typical exhaust chamber 14 shown in
In an upper half region of such a typical exhaust chamber 14, for example, as shown in
In this regard, in the embodiments shown in
In some embodiments, at least a part of a connection portion 25 between the outer flow guide portion 24 and the upper half region 22A of the inner flow guide portion 22 has a curved shape in a cross section along the axial direction of the inner flow guide portion. In the embodiment shown in
In some embodiments, the inner flow guide portion 22 may be a portion of the flow guide 20, a diameter of which gradually increases in the axial direction toward a wall surface of the casing 15 from the exhaust chamber inlet 11.
As described above, since the upper half region 22A of the inner flow guide portion 22 and the outer flow guide portion 24 are connected via the connection portion 25 having the curved shape, the steam flows S tending to circulate back into the upper half region 22A of the inner flow guide portion 22 flow to the outer flow guide portion 24 via the connection portion 25 having the curved shape. Thus, it is possible to reduce the separation vortices V of the steam flows S even further and to reduce the fluid loss in the exhaust chamber 14 more effectively.
In some embodiments, as shown in
The lower half region 24B of the outer flow guide portion 24 may have such a shape that a width W of the outer flow guide portion 24 in a horizontal direction decreases downward in the cross section (each of
For example, as shown in
In addition, even if the upper half region 24A of the outer flow guide portion 24 is disposed only in the upper half region, steam flows directed downward along the outer flow guide portion 24 after passing through the diffuser passage 18 and circulating back into the upper half region 22A of the inner flow guide portion 22 may circulate back into the lower half region 20B of the inner flow guide portion 22 and form the separation vortex V.
In this regard, in the embodiments shown in
In the embodiments shown in
For example, in the embodiment shown in
Since the exhaust chamber 14 has the exhaust chamber outlet 13 on the lower side, flows directed downward as a whole are mainly formed in the exhaust chamber 14. In this regard, as the embodiments shown in
If the outer flow guide portion 24 is not disposed below, for example, as shown in
In some embodiments, the angular position at which the above-described distance becomes the maximum value Dmax is located at a downstream side in a swirl direction of the steam flows S in the exhaust chamber inlet 11 of the exhaust chamber 14 compared to an angular position extending vertically downward through the center axis O.
For example, in the embodiment shown in
A flow in the exhaust chamber 14 is influenced by a rotation of the rotor 2, and thus may include a swirl component. In this case, flow deflection owing to the swirl component occurs in the exhaust chamber 14.
In this regard, for example, as the embodiment shown in
In some embodiments, as shown in
As shown in the drawings, the intermediate flow guide portion 26 is disposed below the inner flow guide portion 22 so as to suspend from the lower half region 22B of the inner flow guide portion 22 toward the lower half region 24B of the outer flow guide portion 24.
The intermediate flow guide portion 26 which connects the lower half region 22B of the inner flow guide portion 22 and the lower half region 24B of the outer flow guide portion 24 appropriately guides downward flows flowing out of the lower half region 22B of the inner flow guide portion 22. It is possible to effectively suppress the separation vortices V below the inner flow guide portion 22.
In the exemplary embodiment shown in
The upstream side of the steam flows S in the diffuser passage 18 means an upstream side in a flow direction of the steam flows S flowing into the exhaust chamber 14 from the exhaust chamber inlet 11.
In this case, a cross-sectional area of the steam flow passage formed by the intermediate flow guide portion 26 and the inner wall surface of the casing 15 is gradually expanded downward, promoting static pressure recovery in the exhaust chamber 14. Thus, it is possible to reduce a loss in the exhaust chamber 14 more effectively.
In some embodiments, for example, as shown in
In the cross-sectional view shown in
That is, in the exemplary embodiment shown in
In the exhaust chamber 14, the steam flows S tend to deflect on the downstream side in the swirl direction in the upper half region.
In this regard, as the embodiment shown in
In the embodiments shown in
In the embodiments shown in
In some embodiments, as the embodiment shown in
As described above, by disposing the first discontinuous point PD1 and the second discontinuous point PD2 at the different height positions, the flow separation positions in the lower end part 24b of the outer flow guide portion 24 become asymmetric, making it possible to suppress occurrence of an unsteady vortex. Therefore, it is possible to reduce the unsteady loss more effectively.
Embodiments of the present invention were described in detail above, but the present invention is not limited thereto, and various amendments and modifications may be implemented.
For example, in the exemplary embodiments shown in
In other embodiments, however, in at least a partial range in a circumferential direction, the end part 27 of the outer flow guide portion 24 may be spaced apart from the inner wall surface 15b of the casing 15. In this case, the end part 27 of the outer flow guide portion 24 may be positioned on an upstream side in a flow direction of the steam flows S flowing into the exhaust chamber 14 via the exhaust chamber inlet 11 with respect to an end part 23 of the inner flow guide portion 22 (that is, the end part 27 may be formed such that the length of the outer flow guide portion 24 in the axial direction is larger than the length of the inner flow guide portion 22 in the axial direction). Thus, it is possible to increase the effect of suppressing the separation vortices V by the outer flow guide portion 24.
The inner wall surface 15b of the casing 15 is a surface of the casing 15 which is positioned on the upstream side in the flow direction of the steam flows S flowing into the exhaust chamber 14 via the exhaust chamber inlet 11 of the inner wall surface of the casing 15 substantially orthogonal to the center axis O of the inner flow guide portion 22. The inner wall surface 15b of the casing 15 may be disposed only in a partial circumferential range (for example, only in the lower half region).
Further, in the present specification, an expression of relative or absolute arrangement such as “in a direction”, “along a direction”, “parallel”, “orthogonal”, “centered”, “concentric” and “coaxial” shall not be construed as indicating only the arrangement in a strict literal sense, but also includes a state where the arrangement is relatively displaced by a tolerance, or by an angle or a distance whereby it is possible to achieve the same function.
For instance, an expression of an equal state such as “same” “equal” and “uniform” shall not be construed as indicating only the state in which the feature is strictly equal, but also includes a state in which there is a tolerance or a difference that can still achieve the same function.
Further, for instance, an expression of a shape such as a rectangular shape or a cylindrical shape shall not be construed as only the geometrically strict shape, but also includes a shape with unevenness or chamfered corners within the range in which the same effect can be achieved.
On the other hand, an expression such as “comprise”, “include” and “have” are not intended to be exclusive of other components.
| Number | Date | Country | Kind |
|---|---|---|---|
| JP2016-212491 | Oct 2016 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2017/039244 | 10/31/2017 | WO | 00 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2018/079805 | 5/3/2018 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 3631672 | Gentile | Jan 1972 | A |
| 3690786 | Silvestri, Jr. | Sep 1972 | A |
| 4315715 | Nishiguchi | Feb 1982 | A |
| 5257906 | Gray et al. | Nov 1993 | A |
| 5340276 | Norris | Aug 1994 | A |
| 20090068006 | Hardin | Mar 2009 | A1 |
| 20110158799 | Dalsania | Jun 2011 | A1 |
| 20120163969 | Ongole | Jun 2012 | A1 |
| 20150167468 | Bison et al. | Jun 2015 | A1 |
| 20190353053 | Kuwamura | Nov 2019 | A1 |
| 20200173309 | Sugishita | Jun 2020 | A1 |
| Number | Date | Country |
|---|---|---|
| 362093 | May 1962 | CH |
| 06-066157 | Mar 1994 | JP |
| 10-227202 | Aug 1998 | JP |
| 11-200814 | Jul 1999 | JP |
| 2003-027905 | Jan 2003 | JP |
| 2004-150357 | May 2004 | JP |
| 2011-220125 | Nov 2011 | JP |
| 2012-132455 | Jul 2012 | JP |
| 2015-523496 | Aug 2015 | JP |
| Entry |
|---|
| International Search Report dated Jan. 16, 2018 in International (PCT) Application No. PCT/JP2017/039244 with English translation. |
| International Preliminary Report on Patentability dated May 9, 2019 in International (PCT) Application No. PCT/JP2017/039244 with English translation. |
| Number | Date | Country | |
|---|---|---|---|
| 20210285338 A1 | Sep 2021 | US |
