JP2019143508A - Turbine exhaust hood and turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust chamber capable of suppressing deterioration of turbine performance and a turbine provided with the exhaust chamber. An exhaust chamber of a turbine includes a casing, a bearing cone provided in the casing, and a flow guide provided on the outer peripheral side of the bearing cone in the casing and forming a diffuser passage together with the bearing cone. The guides are provided in at least a part of the circumferential direction of the bearing cone and the upstream flow guide, and the guides are provided in at least a part of the circumferential direction, and a gap is provided in the axial direction of the bearing cone with respect to the upstream flow guide. The downstream end of the downstream flow guide is communicated with the outer peripheral space located on the outer peripheral side of the flow guide inside the casing and the diffuser passage through a gap including the downstream flow guide arranged vacantly. , Is located radially outside the bearing cone at the downstream end of the upstream flow guide with respect to the tangent of the upstream flow guide. [Selection diagram] Fig. 2

Description

  The present disclosure relates to a turbine exhaust chamber and a turbine.

  In the exhaust chamber of a turbine such as a steam turbine, a diffuser passage for recovering the static pressure of the fluid is usually provided. The diffuser passage has a shape in which the cross-sectional area of the flow passage expands toward the downstream side.For this reason, the flow passing through the diffuser passage is decelerated and the static pressure is recovered. The pressure ratio is increased, and the turbine efficiency is improved.

  In the diffuser portion where the flow path cross-sectional area gradually increases, the flow is decelerated, and therefore, flow separation is likely to occur depending on the operating conditions of the turbine. When such separation occurs, the flow passage cross-sectional area substantially decreases at the position where the separation occurs, so that the effect of increasing the static pressure by the diffuser passage is reduced, and therefore it is desirable to suppress separation in the diffuser portion. . Therefore, a configuration for suppressing peeling that may occur in the diffuser passage has been proposed.

  For example, Patent Document 1 discloses a turbine exhaust chamber in which a diffuser passage is formed by a shell (bearing cone) of an exhaust hood and a steam guide (flow guide) provided on the outer peripheral side of the shell. In the exhaust chamber, a structural member (splitter) is provided in the diffuser passage so as to divide the diffuser passage into a passage on the discharge hood shell side and a passage on the guide side. The fluid separation in the diffuser passage is suppressed.

JP 2010-242759 A

  By the way, especially under operating conditions with a small volume flow rate, even if a structure in which the diffuser passage is divided by a structural member (splitter) or the like described in Patent Document 1 is adopted, after passing through the final stage rotor blade of the turbine Since strong swirling remains in the fluid, it drifts to the radially outer side (tip side) in the diffuser passage, peeling occurs on the radially inner (hub side) diffuser passage wall surface, and circulates in the downstream portion of the diffuser passage Flow may occur. In this case, the effective flow cross-sectional area (effective exhaust area) in the diffuser passage is reduced by the circulation flow, and the flow is accelerated at the outlet of the diffuser passage. May lead to decline.

  In view of the above-described circumstances, at least one embodiment of the present invention aims to provide an exhaust chamber capable of suppressing a decrease in turbine performance even when the operating condition of the turbine changes, and a turbine including the exhaust chamber.

(1) An exhaust chamber of a turbine according to at least one embodiment of the present invention includes:
A casing,
A bearing cone provided in the casing;
A flow guide provided on the outer peripheral side of the bearing cone in the casing and forming a diffuser passage together with the bearing cone;
The flow guide is
An upstream flow guide provided in at least a part of the circumferential direction of the bearing cone;
A downstream flow guide that is provided in at least a part of the circumferential direction and is disposed with a gap in the axial direction of the bearing cone with respect to the upstream flow guide;
Through the gap, an outer peripheral side space located on the outer peripheral side of the flow guide inside the casing and the diffuser passage are communicated,
The downstream end of the downstream flow guide is located on the radially outer side of the bearing cone with respect to the tangent line of the upstream flow guide at the downstream end of the upstream flow guide.

In the configuration of (1), the upstream flow guide and the downstream flow guide that form at least a part of the diffuser passage are arranged with a gap in the axial direction, so that a circulation region is formed on the downstream side of the diffuser passage. Even under such low volume flow operating conditions, the flow on the tip side can flow out to the space behind the flow guide (outer space) through the gap, and the effective channel cross-sectional area Is reduced. As a result, an increase in the flow speed at the outlet of the diffuser passage can be suppressed, and exhaust loss can be reduced. Therefore, it is possible to suppress the deterioration of the exhaust chamber performance and improve the turbine efficiency.
In the configuration of (1), the axial component of the flow passing through the final stage rotor blade of the turbine and flowing into the diffuser passage is relatively large under the operating condition where the volumetric flow rate is relatively large. Separation is less likely to occur, and the flow through the gap between the upstream flow guide and the downstream flow guide is reduced. For this reason, effective reduction of the cross-sectional area of the flow passage hardly occurs in the diffuser passage, and the desired exhaust performance is easily obtained.
Therefore, according to the configuration of (1) above, even if the operating condition of the turbine changes, it is possible to suppress the deterioration of the exhaust performance of the exhaust chamber and suppress the deterioration of the turbine performance.

(2) In some embodiments, in the configuration of (1) above,
When the distance in the axial direction between the downstream end of the upstream flow guide and the upstream end of the downstream flow guide is L0, the downstream end of the upstream flow guide in the radial direction of the bearing cone The distance between the tangent to the upstream flow guide and the upstream end of the downstream flow guide is L0 or less.

  According to the configuration of (2) above, the distance between the tangent of the upstream flow guide at the downstream end of the upstream flow guide and the upstream end of the downstream flow guide is set to L0 or less. The upstream end of the guide will be located substantially on the extension line of the upstream flow guide. Therefore, for example, the fluid flow is less likely to be hindered by the flow guide, for example, the collision of the fluid flow with the downstream flow guide is suppressed under an operation condition with a relatively large volume flow rate. Therefore, exhaust loss in the exhaust chamber can be reduced, and deterioration in exhaust performance of the exhaust chamber can be effectively suppressed.

(3) In some embodiments, in the above configuration (1) or (2),
The upstream flow guide and the downstream flow guide are all in the circumferential direction,
It is at least partially provided in a circumferential range on the opposite side of the exhaust chamber outlet across the shaft center of the bearing cone.

There is a pressure distribution in the exhaust chamber. Normally, the pressure in the region far from the exhaust chamber outlet (the counter exhaust side region) connected to the condenser is the pressure in the region near the exhaust chamber outlet (exhaust side region). It tends to be higher than. Therefore, the counter exhaust side region tends to be in a lower volume flow rate state than the exhaust side region, and therefore, the circulation region described above is likely to occur in the diffuser passage.
In this regard, according to the configuration of the above (3), the upstream flow guide and the downstream flow guide that are provided with a gap in the axial direction are arranged in the circumferential range opposite to the exhaust chamber outlet (that is, the anti-exhaust side region). Therefore, at least in the region opposite to the exhaust side, it is possible to suppress the reduction of the effective channel cross-sectional area in the diffuser passage and to suppress the deterioration of the exhaust performance of the exhaust chamber. Therefore, a decrease in turbine performance can be effectively suppressed.

(4) In some embodiments, in any one of the above configurations (1) to (3),
The upstream flow guide and the downstream flow guide are provided over the entire circumferential range.

As described above, there is a pressure distribution in the exhaust chamber, and there is a circumferential range in which a circulation region is likely to occur under a low volume flow rate condition. Such a circulation region can occur in the entire circumferential range.
In this regard, according to the configuration of (4) above, the upstream flow guide and the downstream flow guide provided with a gap in the axial direction are provided over the entire range in the circumferential direction. In addition, it is possible to suppress the reduction of the effective channel cross-sectional area in the diffuser passage, and to suppress the deterioration of the exhaust performance of the exhaust chamber. Therefore, a decrease in turbine performance can be effectively suppressed.

(5) In some embodiments, in the configuration according to any one of (1) to (4) above,
The axial distance L1 between the downstream end of the upstream flow guide and the upstream end of the downstream flow guide at the first position in the circumferential direction is greater than the first position in the circumferential direction. The axial distance L2 between the downstream end of the upstream flow guide and the upstream end of the downstream flow guide at the second position near the exhaust chamber outlet is larger.

In the configuration of (5) above, the width of the gap is set so as to change in the circumferential direction in accordance with the ease of occurrence of the circulation region. In other words, in the circumferential direction, the volume flow rate tends to be relatively small, and the upstream flow guide and the downstream flow guide become closer to the circumferential position (position opposite to the exhaust chamber outlet) where the circulation region is more likely to occur. Since the distance in the axial direction (width of the gap in the axial direction) is increased, the flow rate of the fluid flowing out from the diffuser passage to the outer peripheral space through the gap at the circumferential position where circulation flow is more likely to occur is further increased. The effective channel cross-sectional area can be increased correspondingly.
Therefore, effective reduction of the cross-sectional area of the flow passage in the diffuser passage can be appropriately suppressed according to the circumferential position, and a reduction in exhaust performance of the exhaust chamber can be effectively suppressed, resulting in a reduction in turbine performance. It can be effectively suppressed.

(6) In some embodiments, in any one of the above configurations (1) to (5),
The axial position of the gap at the third position in the circumferential direction is upstream in the axial direction than the axial position of the gap at the fourth position closer to the exhaust chamber outlet than the third position in the circumferential direction. On the side.

According to the configuration of (6) above, the axial position of the gap is set to change in the circumferential direction according to the size of the circulation region that can be generated. That is, in the circumferential direction, the above-described circulation region is likely to be larger, and the gap is positioned upstream in the axial direction as it approaches a circumferential position (a position opposite to the exhaust chamber outlet) that protrudes to the upstream side. Since it did in this way, a flow-path cross-sectional area can be increased appropriately according to the axial direction position in which a circulation area | region is formed in each circumferential direction position.
Therefore, effective reduction of the cross-sectional area of the flow passage in the diffuser passage can be appropriately suppressed according to the circumferential position, and a reduction in exhaust performance of the exhaust chamber can be effectively suppressed, resulting in a reduction in turbine performance. It can be effectively suppressed.

(7) In some embodiments, in any one of the configurations (1) to (6) above,
The apparatus further includes a support portion for supporting the downstream flow guide on the upstream flow guide.

According to the configuration of (7) above, the downstream flow guide can be stably supported on the upstream flow guide fixed to the casing via the support portion.
In the configuration (7), the downstream flow guide is supported by the casing via the upstream flow guide provided with a gap in the axial direction, so the downstream flow guide is directly supported by the casing. The support structure can be simplified compared to the case where For this reason, the fluid flow is less likely to be inhibited in the exhaust chamber, and the deterioration of the exhaust chamber performance can be more effectively suppressed.

(8) In some embodiments, in the configuration of (7) above,
The support portion has a diameter so as to connect the upstream flow guide and the downstream flow guide across the gap and from the outer peripheral surface of the upstream flow guide and the outer peripheral surface of the downstream flow guide. A rib provided so as to protrude outward in the direction.

  According to the configuration of (8) above, the rib provided on the outer peripheral surface of the flow guide is used as a support portion for supporting the downstream flow guide, so that while improving the strength of the flow guide, The downstream flow guide can be appropriately supported by the upstream flow guide.

(9) In some embodiments, in any one of the above configurations (1) to (8),
The flow guide including the upstream flow guide and the downstream flow guide is an integral member, and is provided with a slit extending along the circumferential direction,
The gap is formed by the slit.

  According to the configuration of (9) above, the flow guide as an integral member has a simple configuration in which only slits extending along the circumferential direction are formed, and both sides in the axial direction with the slit (gap) interposed therebetween. The configuration of (1) including the upstream flow guide and the downstream flow guide located respectively in the above can be realized.

(10) In some embodiments, in any one of the above configurations (1) to (9),
The downstream flow guide has an airfoil-shaped cross section in the axial direction.

The flow that flows from the diffuser passage through the gap and flows into the outer peripheral space may be separated on the outer peripheral space-side surface of the downstream flow guide, thereby causing exhaust loss and exhaust chamber performance. May lead to a decline.
In this regard, according to the configuration of (10) above, since the cross section in the axial direction of the downstream flow guide is formed into an airfoil shape, the flow that has passed through the gap tends to flow along the curved shape of the airfoil. Therefore, peeling on the surface of the downstream flow guide can be suppressed, and exhaust loss can be further reduced.

(11) A turbine according to at least one embodiment of the present invention includes:
The exhaust chamber according to any one of (1) to (10) above;
A stationary blade and a moving blade provided on the upstream side of the exhaust chamber;
Is provided.

In the configuration (11), the upstream flow guide and the downstream flow guide that form at least a part of the diffuser passage are arranged with a gap in the axial direction, so that a circulation region is formed on the downstream side of the diffuser passage. Even under such low volume flow operating conditions, the flow on the tip side can flow out to the space behind the flow guide (outer space) through the gap, and the effective channel cross-sectional area Is reduced. As a result, an increase in the flow speed at the outlet of the diffuser passage can be suppressed, and exhaust loss can be reduced. Therefore, it is possible to suppress the deterioration of the exhaust chamber performance and improve the turbine efficiency.
In the configuration of (11) above, since the axial component of the flow passing through the final stage rotor blade of the turbine and flowing into the diffuser passage is relatively large under the operating condition where the volumetric flow rate is relatively large, Separation is less likely to occur, and the flow through the gap between the upstream flow guide and the downstream flow guide is reduced. For this reason, effective reduction of the cross-sectional area of the flow passage hardly occurs in the diffuser passage, and the desired exhaust performance is easily obtained.
Therefore, according to the structure of said (11), even if the driving | running condition of a turbine changes, the fall of the exhaust performance of an exhaust chamber can be suppressed and the fall of turbine performance can be suppressed.

  According to at least one embodiment of the present invention, there is provided an exhaust chamber capable of suppressing a decrease in turbine performance even when the operating condition of the turbine changes, and a turbine including the exhaust chamber.

It is a schematic sectional drawing along the axial direction of the steam turbine concerning one embodiment. It is a schematic sectional drawing of the exhaust chamber which concerns on one Embodiment. It is AA sectional drawing of the exhaust chamber shown in FIG. It is a schematic diagram which shows the cross section along the radial direction of the flow guide which concerns on one Embodiment. It is a schematic diagram which shows the cross section along the radial direction of the flow guide which concerns on one Embodiment. It is a schematic diagram which shows the cross section along the radial direction of the flow guide which concerns on one Embodiment. It is a side view of the flow guide concerning one embodiment. It is a perspective view of the flow guide shown in FIG. It is a side view of the flow guide concerning one embodiment. It is a side view of the flow guide concerning one embodiment. It is a side view of the flow guide concerning one embodiment. It is a schematic sectional drawing of a typical 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 as an example of the turbine which concerns on some embodiment is demonstrated. In addition, the turbine in this invention is not limited to a steam turbine, For example, a gas turbine may be sufficient.

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 that is rotatably supported by a bearing portion 6, multiple stages of moving blades 8 and stationary blades 9, an inner casing 10, and an outer casing 12.
The plurality of moving blades 8 and the plurality of stationary blades 9 are arranged in the circumferential direction to form a row, and the rows of the moving blades 8 and the rows of the stationary blades 9 are alternately arranged in the axial direction. .
The plurality of stages of moving blades 8 are attached to the rotor 2, and the rotor 2 and the moving blades 8 are accommodated in the inner casing 10. The stationary blade 9 is attached to the inner casing 10 so as to face the moving blade 8.
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 after passing through the final stage moving blade 8A, passes through the inside of the exhaust chamber 14, and is exhausted. An exhaust chamber outlet 13 provided on the lower side of the chamber 14 is discharged to the outside of the steam turbine 1.
A condenser (not shown) is provided below the exhaust chamber 14. The steam that has finished working on the moving blade 8 in the steam turbine 1 is discharged from the exhaust chamber 14 through the exhaust chamber outlet 13 and flows into the condenser.

  In the illustrated embodiment, the exhaust chamber outlet 13 is provided on the lower side of the exhaust chamber 14, but in other embodiments, the exhaust chamber outlet 13 may be provided on the side of the exhaust chamber 14. . In this case, the condenser may be provided on the side of the exhaust chamber 14.

  Hereinafter, exhaust chambers according to some embodiments will be described.

  2 is a schematic cross-sectional view of an exhaust chamber according to an embodiment, and FIG. 3 is a cross-sectional view of the exhaust chamber shown in FIG. 4 to 6 are schematic views showing cross sections along the radial direction of the flow guide according to the embodiment, respectively.

As shown in FIGS. 1 to 3, the exhaust chamber 14 according to some embodiments includes a casing 15, a bearing cone 16 provided to cover the bearing portion 6 in the casing 15, and a bearing in the casing 15. And a flow guide 20 provided on the outer peripheral side of the cone 16. 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. Further, the upstream end of the flow guide 20 may be connected to the inner casing 10.
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.

  An annular diffuser passage 18 (steam passage) is formed in the casing 15 by the bearing cone 16 and the flow guide 20. In the exhaust chamber 14, an outer peripheral side space 30 is formed on the opposite side of the diffuser passage 18 with the flow guide 20 interposed therebetween. The outer peripheral space 30 is located on the outer peripheral side of the flow guide 20.

  The diffuser passage 18 has a shape in which the cross-sectional area of the steam (fluid) gradually increases, and when the high-speed steam flow S that has passed through the moving blade 8A in the final stage of the steam turbine 1 flows into the diffuser passage 18. The steam flow S is decelerated and its kinetic energy is converted into pressure (static pressure recovery).

As shown in FIGS. 2 to 3, the flow guide 20 includes an upstream flow guide 22 and a downstream flow guide 24 arranged with a gap 26 in the axial direction of the bearing cone 16 with respect to the upstream flow guide 22. And including. The upstream flow guide 22 and the downstream flow guide 24 are provided in at least a part of the circumferential direction of the bearing cone 16.
The axial direction of the bearing cone 16 is the direction of the axial center O of the bearing cone 16 and is substantially the same as the axial direction of the rotor 2 of the steam turbine 1 (the direction of the rotation axis).
The circumferential direction of the bearing cone 16 is a direction around the axial center O of the bearing cone 16 and is substantially the same as the circumferential direction of the rotor 2 of the steam turbine 1.
The outer peripheral space 30 located on the outer peripheral side of the flow guide 20 and the diffuser passage 18 formed by the flow guide 20 and the bearing cone 16 are a gap 26 between the upstream flow guide 22 and the downstream flow guide 24. It is communicated through.

  As shown in FIGS. 4 to 6, the downstream end 24 </ b> B of the downstream flow guide 24 is more bearing cone than the tangent To of the inner wall surface 22 a of the upstream flow guide 22 at the downstream end 22 </ b> B of the upstream flow guide 22. 16 is located outside in the radial direction. In other words, at the axial position of the downstream end 22B of the downstream flow guide 24, the distance Rd from the center line of the bearing cone 16 to the downstream end 22B of the downstream flow guide 24 is from the center line to the tangent line To described above. It is longer than the distance Rt.

  Here, FIG. 12 is a schematic sectional view of a typical exhaust chamber 114. The exhaust chamber 114 shown in FIG. 12 has basically the same configuration as the exhaust chamber 14 shown in FIG. 2, but the flow guide 20 of the exhaust chamber 114 has a cross-section that continues continuously from the upstream end to the downstream end. It differs from the exhaust chamber 14 shown in FIG. That is, the flow guide 20 in the exhaust chamber 114 does not have an upstream flow guide and a downstream flow guide, and no axial gap is formed between the upstream flow guide and the downstream flow guide.

  In both the exhaust chamber 14 shown in FIG. 2 and the exhaust chamber 114 shown in FIG. 12, particularly under operating conditions where the volumetric flow rate is small (for example, the condition where the vacuum degree of the condenser is low or the fluid flow rate is low). Since strong swirl remains in the fluid after passing through the final stage moving blade 8A of the steam turbine 1, the diffuser passage 18 drifts radially outward (tip side) in the diffuser passage 18 and the diffuser passage 18 wall surface radially inward (hub side) In some cases, separation may occur and a circulation flow may occur in the downstream portion of the diffuser passage 18 (see the circulation region Z in FIGS. 2 and 12).

Here, in the exhaust chamber 114 shown in FIG. 12, the effective flow cross-sectional area (effective exhaust area) in the diffuser passage 18 decreases due to the circulation flow. That is, in the exhaust chamber 114, the flow path cross-sectional area of the upper half side and the lower half side immediately after the final stage moving blade 8A passage is S _U0 and S _L0, respectively. On the other hand, since the circulation region Z is formed in the diffuser passage 18 in the vicinity of the outlet of the diffuser passage 18, the effective channel cross-sectional areas on the upper half side and the lower half side in the vicinity of the outlet are SU _2. (Where S _U2 <S _U0 ) and S _L2 (where S _L2 <S _L0 ).
As described above, when the effective flow path cross-sectional area in the diffuser passage 18 is reduced, the flow is accelerated at the outlet of the diffuser passage 18, so that the exhaust loss increases, and as a result, the turbine performance may be lowered. .

On the other hand, in the exhaust chamber 14 shown in FIG. 2 (and FIGS. 3 to 6), the upstream flow guide 22 and the downstream flow guide 24 that form at least a part of the diffuser passage 18 are spaced from each other in the axial direction. Since it is arranged, the flow on the tip side passes through the gap 26 and the space on the rear side of the flow guide 20 even under a low volume flow operation condition in which the circulation region Z is formed downstream of the diffuser passage 18. It is possible to flow out into the (outer peripheral space 30), and the effective reduction of the channel cross-sectional area is suppressed.
That is, in the exhaust chamber 14, the channel cross-sectional areas of the upper half side and the lower half side immediately after passing through the final stage moving blade 8 _{</ b> A} are _{SU 0} and S _L0 , respectively. On the other hand, in the vicinity of the outlet of the diffuser passage 18, a circulation region Z is formed in the diffuser passage 18, but since the flow on the tip side can flow out to the outer space 30 through the gap 26, The effective channel cross-sectional areas on the half side and the lower half side are S _U1 (where S _{U1 ≈S U0} ) and S _L1 (where S _L1 ≈S _L0 ), respectively, and are near the inlet and the outlet of the diffuser passage 18. The effective channel cross-sectional area does not decrease so much.
Therefore, according to the exhaust chamber 14 including the upstream flow guide 22 and the downstream flow guide 24, an increase in the flow velocity at the outlet of the diffuser passage 18 can be suppressed, and exhaust loss can be reduced. Therefore, it is possible to suppress the deterioration of the exhaust chamber performance and improve the turbine efficiency.

  In the exhaust chamber 14, the axial component of the flow that flows through the final stage moving blade 8A of the steam turbine 1 and flows into the diffuser passage 18 is relatively large under an operation condition in which the volumetric flow rate is relatively large. Separation on the hub side is less likely to occur, and the flow through the gap 26 between the upstream flow guide 22 and the downstream flow guide 24 is reduced. For this reason, effective reduction of the cross-sectional area of the flow path hardly occurs in the diffuser passage 18, and the desired exhaust performance can be easily obtained.

  Therefore, according to the exhaust chamber 14 described above, even if the operating conditions of the steam turbine 1 change, it is possible to suppress a decrease in the exhaust performance of the exhaust chamber 14 and suppress a decrease in the turbine performance.

  In the exhaust chamber described in Patent Document 1, the diffuser passage is divided by providing a structural member (splitter) inside the diffuser passage, that is, inside the main flow path of the fluid that has passed through the turbine blades. By reducing the enlargement ratio of the flow path cross-sectional area, separation on the wall surface of the diffuser passage is suppressed.

  On the other hand, in the above-described embodiment, a structural member is not provided inside the diffuser passage 18 (inside the main flow path of the steam), but on the radially outer side than the tangent line To at the downstream end 22B of the upstream flow guide 22. That is, the downstream flow guide in which at least a part is arranged (that is, radially outside the original main flow path (see FIG. 12) when the upstream flow guide 22, the downstream flow guide 24, and the gap 26 are not provided). By providing 24, even if the separation and circulation region Z occurs in the diffuser passage 18, the effect of suppressing the deterioration of the exhaust chamber performance can be obtained as described above.

In some embodiments, for example, as shown in FIGS. 4-6, the axial distance between the downstream end 22B of the upstream flow guide 22 and the upstream end 24A of the downstream flow guide 24 is L ₀ . when, in the radial direction of the bearing cone 16, the tangent to the inner wall surface 22a of the upstream-side flow guide 22 at the downstream end 22B of the upstream flow guide 22, the distance _{L E} of the upstream end 24A of the downstream flow guide 24 L ₀ or less.
Here, when there is a thick downstream flow guide 24, the aforementioned "and tangential To, the distance between the upstream end 24A of the downstream flow guide 24 L _E" is the tangential To, the upstream end of the downstream flow guide 24 It may be a distance from the center position of the thickness of 24A.

In the above embodiment, the tangent To the upstream flow guide 22 at the downstream end 22B of the upstream flow guide 22, since the distance L _E of the upstream end 24A of the downstream flow guide 24 was set to be L ₀ or less The upstream end 24 </ b> A of the downstream flow guide 24 is positioned substantially on the extension line of the upstream flow guide 22. Therefore, for example, the flow of the fluid flows into the flow guide 20 (upstream flow guide 22 and downstream flow guide 24) such that the collision of the fluid flow with the downstream flow guide 24 is suppressed under an operation condition with a relatively large volume flow rate. It is hard to be disturbed by. Therefore, exhaust loss in the exhaust chamber 14 can be reduced, and deterioration of the exhaust performance of the exhaust chamber 14 can be effectively suppressed.

  In some embodiments, for example, as shown in FIG. 6, the downstream flow guide 24 has an airfoil shape 27 in the axial cross section.

The flow that flows from the diffuser passage 18 through the gap 26 into the outer peripheral space 30 is separated on the surface of the downstream flow guide 24 on the outer peripheral space 30 side (that is, the surface opposite to the diffuser passage 18). As a result, exhaust loss may occur, leading to deterioration in exhaust chamber performance.
In this regard, in the above-described embodiment, since the cross section in the axial direction of the downstream flow guide 24 has the airfoil shape 27, the flow that has passed through the gap 26 tends to flow along the curved shape of the airfoil. Therefore, exfoliation on the surface 24a of the downstream flow guide 24 can be suppressed and exhaust loss can be further reduced.

  7 and 9 to 11 are side views of the flow guide 20 according to the embodiment, respectively. FIG. 8 is a perspective view of the flow guide 20 shown in FIG.

In some embodiments, the upstream-side flow guide 22 and the downstream-side flow guide 24 have a circumferential range (on the opposite side of the exhaust chamber outlet 13 across the axial center O of the bearing cone 16) of the entire circumferential range ( At least partly in the region opposite to the exhaust).
In some embodiments, the upstream flow guide 22 and the downstream flow guide 24 are provided over the entire circumferential range.

Here, as shown in FIG. 3, in the cross section orthogonal to the axial center O of the bearing cone 16, the angular position of the central position 13a of the exhaust chamber outlet 13 is defined as 0 degree with the axial center O as the center.
Under this definition, the circumferential range on the opposite side of the exhaust chamber outlet 13 across the axial center O of the bearing cone 16 is the position opposite to the central position 13a of the exhaust chamber outlet 13 across the axial center O. A range of ± 90 degrees from (position of 180 degrees), that is, a circumferential range of 90 degrees or more and 270 degrees or less. Hereinafter, this circumferential range (a circumferential direction range of 90 degrees or more and 270 degrees or less) is also referred to as an anti-exhaust side region.
Further, a range of ± 90 degrees from the center position 13a of the exhaust chamber outlet 13, that is, a circumferential range of 0 degrees to 90 degrees and 270 degrees to 360 degrees is also referred to as an exhaust side area.

  In the exemplary embodiment shown in FIGS. 7 to 8, the upstream flow guide 22 and the downstream flow guide 24 are provided only in the counter-exhaust side region in the entire circumferential range. That is, in this embodiment, the gap 26 between the upstream flow guide 22 and the downstream flow guide 24 is also provided only in the anti-exhaust side region.

  In the exemplary embodiments shown in FIGS. 2 to 3 and FIGS. 9 to 11, the upstream flow guide 22 and the downstream flow guide 24 are provided over the entire circumferential range. That is, in these embodiments, the gap 26 between the upstream flow guide 22 and the downstream flow guide 24 is also provided over the entire circumferential range.

There is a pressure distribution in the exhaust chamber 14, and the pressure in the region farther from the exhaust chamber outlet 13 connected to the condenser (anti-exhaust side region) is usually closer to the exhaust chamber outlet (exhaust side region). ) Tends to be higher than the pressure in). Therefore, the counter-exhaust side region is likely to be in a state of a lower volume flow rate than the exhaust side region, and therefore, the circulation region Z (see FIG. 2) described above is likely to occur in the diffuser passage 18.
In this regard, in the embodiment shown in FIGS. 2 to 3 and FIGS. 7 to 11, the upstream-side flow guide 22 and the downstream-side flow guide 24 are at least partially in the circumferential range (anti-exhaust side region) opposite to the exhaust chamber outlet 13. Therefore, at least in the region opposite to the exhaust side, it is possible to suppress a reduction in effective cross-sectional area of the diffuser passage 18 and to suppress a reduction in exhaust performance of the exhaust chamber 14.

Further, as described above, there is a pressure distribution in the exhaust chamber 14 and there is a circumferential range in which the circulation region Z is likely to occur under the low volume flow rate condition. It can occur in the entire range.
In this respect, in the embodiment shown in FIGS. 2 to 3 and FIGS. 9 to 11, the upstream flow guide 22 and the downstream flow guide 24 are provided over the entire range in the circumferential direction. Over the range, it is possible to suppress the reduction of the effective channel cross-sectional area in the diffuser passage 18 and to suppress the deterioration of the exhaust performance of the exhaust chamber 14.

  In some embodiments, for example, as shown in FIG. 9, the axial direction between the downstream end 22B of the upstream flow guide 22 and the upstream end 24A of the downstream flow guide 24 at a first position C1 in the circumferential direction. The distance L1 (the width of the gap 26 at the first position C1) is the downstream end 22B and the downstream side of the upstream flow guide 22 at the second position C2 closer to the exhaust chamber outlet 13 than the first position C1 in the circumferential direction. It is larger than the axial distance L2 between the upstream end 24A of the flow guide 24 (the width of the gap 26 at the second position C2).

  In the above-described embodiment, the width of the gap 26 is set to change in the circumferential direction in accordance with the ease with which the circulation region Z (see FIG. 2) is generated. That is, in the circumferential direction, the volume flow rate tends to be relatively small, and the upstream becomes closer to the circumferential position (position opposite to the exhaust chamber outlet 13 (position of 180 degrees shown in FIG. 2)) where the circulation region Z is more likely to occur. The distance in the axial direction between the side flow guide 22 and the downstream flow guide 24 (the width of the gap 26 in the axial direction) increases. Thereby, at the circumferential position where the circulation region Z is more likely to occur, the flow rate of the fluid flowing out from the diffuser passage 18 to the outer circumferential side space 30 through the gap 26 becomes larger, and the effective flow cross-sectional area is increased accordingly. Can be increased. Therefore, effective reduction of the flow passage cross-sectional area in the diffuser passage 18 can be appropriately suppressed according to the circumferential position, and a reduction in the exhaust performance of the exhaust chamber 14 can be effectively suppressed.

In some embodiments, for example, as shown in FIG. 10, the axial position P3 of the gap 26 at the third position C3 in the circumferential direction is a fourth position closer to the exhaust chamber outlet 13 than the third position C3 in the circumferential direction. It is upstream in the axial direction with respect to the axial position P4 of the gap 26 at the position C4.
The axial position of the gap 26 may be the center position of the gap 26 in the axial direction.

In the above embodiment, the axial position of the gap 26 is set to change in the circumferential direction according to the size of the circulation region Z that can be generated. That is, in the circumferential direction, the circulation region Z described above tends to be larger, and approaches a circumferential position (a position on the opposite side of the exhaust chamber outlet 13 (position of 180 degrees shown in FIG. 2)) that protrudes to the upstream side. Accordingly, since the gap 26 is positioned on the upstream side in the axial direction, the flow path cross-sectional area can be appropriately increased at each circumferential position according to the axial position where the circulation region Z is formed.
Therefore, effective reduction of the flow passage cross-sectional area in the diffuser passage 18 can be appropriately suppressed according to the circumferential position, and a reduction in the exhaust performance of the exhaust chamber 14 can be effectively suppressed.

  In the above-described embodiment, the shapes of the upstream flow guide 22 and the downstream flow guide 24 may be symmetric with respect to the axial center O or may be asymmetric.

In some embodiments, for example, as shown in FIGS. 3 and 11, a support portion 34 for supporting the downstream flow guide 24 on the upstream flow guide 22 may be further provided.
In this case, the downstream flow guide 24 can be stably supported on the upstream flow guide 22 fixed to the casing 15 via the support portion 34.
Further, since the downstream flow guide 24 is supported by the casing 15 via the upstream flow guide 22 provided with a gap 26 in the axial direction, the downstream flow guide 24 is directly supported by the casing 15. Compared with the support structure can be simplified. For this reason, the fluid flow is less likely to be inhibited in the exhaust chamber 14, and the deterioration of the exhaust chamber performance can be more effectively suppressed.

In the exemplary embodiment shown in FIG. 3, the flow guide 20 including the upstream flow guide 22 and the downstream flow guide 24 is constituted by an integral member, and is separated by a slit extending along the circumferential direction. 26 is formed. A support portion 34 is configured by the connection portion 31 that connects the upstream flow guide 22 and the downstream flow guide 24 at a pair of circumferential positions facing each other across the axial center O of the bearing cone 16.
Thus, the support part 34 may be provided integrally with the upstream flow guide 22 and the downstream flow guide 24 as a part of the flow guide 20.

Further, in the embodiment shown in FIG. 11, the support portion 34 connects the upstream flow guide 22 and the downstream flow guide 24 across the gap 26, and the outer peripheral surface 23 of the upstream flow guide 22. And a rib 32 provided to protrude radially outward from the outer peripheral surface 25 of the downstream flow guide 24.
In this case, the ribs 32 provided on the outer peripheral surfaces 23 and 25 of the flow guide 20 (the upstream flow guide 22 and the downstream flow guide 24) are used as the support portions 34 for supporting the downstream flow guide 24. Therefore, the downstream flow guide 24 can be appropriately supported by the upstream flow guide 22 while improving the strength of the flow guide 20.

  9 and 10, the support portion 34 is not shown, but the downstream flow guide 24 separated from the upstream flow guide 22 by a gap 26 over the entire circumference in the circumferential direction. A support 34 is provided for proper support.

  In some embodiments, for example, as shown in FIGS. 3 and 7-8, the flow guide 20 including the upstream flow guide 22 and the downstream flow guide 24 is an integral member and is circumferential. A slit extending along the slit is provided, and a gap 26 is formed by the slit.

  According to the above-described embodiment, the flow guide 20 as an integral member has a simple configuration that only forms a slit extending along the circumferential direction, and both sides in the axial direction with the slit (gap 26) interposed therebetween. It is possible to realize a configuration including the upstream flow guide 22 and the downstream flow guide 24 that are respectively located in

  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 12 Outer casing 13 Exhaust chamber outlet 13a Center position 14 Exhaust chamber 15 Casing 15a Inner wall surface 16 Bearing cone 16a Downstream end 18 Diffuser passage 20 Flow guide 22 Upstream flow guide 22B Downstream end 22a Inner wall surface 23 Outer surface 24 Downstream flow guide 24A Upstream end 24B Downstream end 24a Surface 25 Outer surface 26 Gap 27 Airfoil shape 30 Outer space 31 Connection portion 32 Rib 34 Supporting part 114 Exhaust chamber Z Circulation area

Claims (11)

A casing,
A bearing cone provided in the casing;
A flow guide provided on the outer peripheral side of the bearing cone in the casing and forming a diffuser passage together with the bearing cone;
The flow guide is
An upstream flow guide provided in at least a part of the circumferential direction of the bearing cone;
A downstream flow guide that is provided in at least a part of the circumferential direction and is disposed with a gap in the axial direction of the bearing cone with respect to the upstream flow guide;
Through the gap, an outer peripheral side space located on the outer peripheral side of the flow guide inside the casing and the diffuser passage are communicated,
An exhaust chamber of a turbine, wherein a downstream end of the downstream flow guide is located on a radially outer side of the bearing cone with respect to a tangent line of the upstream flow guide at a downstream end of the upstream flow guide. When the distance in the axial direction between the downstream end of the upstream flow guide and the upstream end of the downstream flow guide is L0, the downstream end of the upstream flow guide in the radial direction of the bearing cone 2. The turbine exhaust chamber according to claim 1, wherein a distance between a tangent of the upstream flow guide and the upstream end of the downstream flow guide is equal to or less than L <b> 0. The upstream flow guide and the downstream flow guide are all in the circumferential direction,
3. The turbine exhaust chamber according to claim 1, wherein the exhaust chamber of the turbine according to claim 1 is provided at least partially in a circumferential range opposite to the exhaust chamber outlet across the shaft center of the bearing cone. 4. The turbine exhaust chamber according to claim 1, wherein the upstream flow guide and the downstream flow guide are provided over the entire circumferential range. 5. The axial distance L1 between the downstream end of the upstream flow guide and the upstream end of the downstream flow guide at the first position in the circumferential direction is greater than the first position in the circumferential direction. 2. The axial distance L2 between the downstream end of the upstream flow guide and the upstream end of the downstream flow guide at a second position near the exhaust chamber outlet is greater than the axial distance L2. The exhaust chamber of the turbine according to claim 4. The axial position of the gap at the third position in the circumferential direction is upstream in the axial direction than the axial position of the gap at the fourth position closer to the exhaust chamber outlet than the third position in the circumferential direction. The exhaust chamber of the turbine according to any one of claims 1 to 5, wherein the exhaust chamber is on the side. The turbine exhaust chamber according to any one of claims 1 to 6, further comprising a support portion for supporting the downstream flow guide on the upstream flow guide. The support portion has a diameter so as to connect the upstream flow guide and the downstream flow guide across the gap and from the outer peripheral surface of the upstream flow guide and the outer peripheral surface of the downstream flow guide. The turbine exhaust chamber according to claim 7, further comprising a rib provided so as to protrude outward in the direction. The flow guide including the upstream flow guide and the downstream flow guide is an integral member, and is provided with a slit extending along the circumferential direction,
The turbine exhaust chamber according to any one of claims 1 to 8, wherein the gap is formed by the slit. 10. The turbine exhaust chamber according to claim 1, wherein the downstream flow guide has an airfoil-shaped cross section in the axial direction. 11. An exhaust chamber according to any one of claims 1 to 10,
A stationary blade and a moving blade provided on the upstream side of the exhaust chamber;
Turbine with.

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