JP2020186709A - Exhaust chamber of steam turbine - Google Patents

Abstract

To provide an exhaust chamber of a steam turbine capable of improving exhaust efficiency and decreasing costs for manufacturing a flow guide.SOLUTION: An exhaust chamber of a steam turbine includes a casing, a bearing cone provided in the casing, and a flow guide that is provided on the outer side in a diametrical direction of the bearing cone in the casing, and has a passage forming surface forming a diffuser passage with the bearing cone. The passage forming surface includes: a first straight line portion that is disposed on the most upstream side of the flow guide and is parallel with a rotation axis or has a predetermined inclined angle with respect to the rotation axis in a side cross-sectional view including the rotation axis of the steam turbine, and extends to increase a distance from the rotation axis toward a downstream side of the flow guide; and a second straight line portion that is disposed on the downstream side of the flow guide from the first straight line portion and has an inclined angle larger than that of the first straight line portion with respect to the rotation axis, and extends so as to increase a distance from the rotation axis toward the downstream side of the flow guide.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to the exhaust chamber of a steam turbine.

Conventionally, in the exhaust chamber of a steam turbine, it is known that the shape of the flow guide forming the diffuser passage downstream of the final stage rotor blade has a great influence on the exhaust performance. Patent Document 1 discloses a configuration relating to an exhaust chamber of such a steam turbine.

JP 2015-194085

By the way, in the exhaust chamber of the steam turbine disclosed in Patent Document 1, the vicinity of the downstream end of the flow guide is formed in a curved shape in a side cross-sectional view including the rotation axis of the steam turbine. The production of a flow guide including such a curved portion has a higher processing cost than the production of a flow guide formed linearly in the above side cross-sectional view. Further, in the exhaust chamber of a steam turbine as in Patent Document 1, there is a risk that the exhaust efficiency may decrease due to interference between the main exhaust flow discharged through the diffuser passage and the circulating flow flowing in a spiral after passing through the diffuser passage. there were.

In view of the above circumstances, at least one embodiment of the present disclosure aims to provide an exhaust chamber of a steam turbine capable of achieving both improvement in exhaust efficiency and reduction in cost of manufacturing a flow guide.

(1) The exhaust chamber of the steam turbine according to at least one embodiment of the present invention is
Casing and
A bearing cone provided in the casing and
A flow guide provided in the casing on the radial outer side of the bearing cone and having a passage forming surface for forming a diffuser passage together with the bearing cone.
The passage forming surface of the flow guide is
A first straight line portion arranged on the most upstream side of the flow guide in a side sectional view including the rotation axis of the steam turbine, which is parallel to the rotation axis or predetermined with respect to the rotation axis. A first straight line portion having an inclination angle and extending linearly so that the distance from the rotation axis increases toward the downstream side of the flow guide.
A second straight line portion arranged on the downstream side of the flow guide from the first straight line portion in a side cross-sectional view including the rotation axis of the steam turbine, and the first straight line portion with respect to the rotation axis. Includes a second straight line portion having a larger inclination angle and extending linearly so that the distance from the rotation axis increases toward the downstream side of the flow guide.

When manufacturing the exhaust chamber of a steam turbine, in order to improve the performance of the exhaust chamber, a curved flow guide may be adopted in a side cross-sectional view including the rotation axis of the steam turbine. Since a complicated processing process is required for manufacturing, the number of steps and cost are increased as compared with the case of manufacturing a linear flow guide in a cross-sectional view on the same side.
In this regard, the exhaust chamber of the steam turbine shown in (1) above is configured such that the passage forming surface of the flow guide includes the first straight line portion and the second straight line portion in the side cross-sectional view. Compared with the case of forming a curved flow guide in a side cross-sectional view, the man-hours and cost required for manufacturing the flow guide can be suppressed. Further, in the first straight line portion and the second straight line portion, adjacent end portions thereof are continuous in a non-parallel manner so that the passage forming surface facing the diffuser passage expands in diameter toward the downstream side, and at least the second straight line portion. Is provided so as to be inclined so as to increase the diameter toward the downstream side with respect to the central axis of the steam turbine. Therefore, for example, the passage forming surface defining the diffuser passage is a straight portion parallel to the rotation axis and a straight portion orthogonal to the rotation axis. The exhaust flow can be guided more smoothly than when it is configured. Therefore, it is possible to provide an exhaust chamber of a steam turbine that can achieve both improvement of exhaust efficiency and cost reduction of flow guide production.

(2) In some embodiments, in the configuration of (1) above,
The passage forming surface of the flow guide is
A third straight line portion arranged on the downstream side of the flow guide from the second straight line portion in a side cross-sectional view including the rotation axis of the steam turbine, and the second straight line portion with respect to the rotation axis. It may further include a third straight line portion having a larger inclination angle and extending linearly so that the distance from the rotation axis increases toward the downstream side of the flow guide.

According to the configuration of the above (2), in addition to the effect of the above (1), by further including the third straight line portion, the interference between the circulating flow of the exhaust gas after passing through the flow guide and the main exhaust flow is suppressed. be able to. Therefore, although the configuration is simple, the exhaust chamber performance can be further improved while suppressing the man-hours for manufacturing the flow guide.

(3) In some embodiments, in the configuration of (2) above,
The third straight line portion may extend along a direction orthogonal to the rotation axis.

According to the configuration of (3) above, the third straight line portion of the flow guide extends along the direction orthogonal to the rotation axis of the steam turbine, so that the circulating flow flowing in a spiral shape after passing through the diffuser passage flows through the diffuser passage. Since it is possible to physically block the merging with the main exhaust flow discharged through the main exhaust flow, it is possible to effectively suppress the interference between the main exhaust flow and the circulating flow. Therefore, the exhaust efficiency can be improved.

(4) In some embodiments, in the configuration of (2) or (3) above,
The passage forming surface of the flow guide is
A fourth straight line portion extending linearly from the downstream end of the first straight line portion to the upstream end of the second straight line portion in a side sectional view including the rotation axis of the steam turbine. The 1st straight section, the 4th straight section shorter than the 2nd straight section, and
A fifth straight line portion extending linearly from the downstream end of the second straight line portion to the upstream end of the third straight line portion in a side sectional view including the rotation axis of the steam turbine. It may further include a two straight line portion and a fifth straight line portion shorter than the third straight line portion.

According to the configuration of (4) above, the diffuser is formed by the fourth straight line portion between the first straight line portion and the second straight line portion and the fifth straight line portion between the second straight line portion and the third straight line portion. Of the passage forming surfaces that define the passage, the connection portion between the first straight line portion and the fourth straight line portion, the connection portion between the fourth straight line portion and the second straight line portion, and the connection between the second straight line portion and the fifth straight line portion. A convex portion having a convex shape is formed fluidly at the portion and the connecting portion between the fifth straight portion and the third straight portion. Then, when the exhaust passes through these convex portions, an expansion wave is generated in each convex portion. As a result, the exhaust (fluid) can be deflected at supersonic speed to improve the followability of the fluid to the flow guide shape. Therefore, the development of the boundary layer is suppressed and the performance deterioration due to the reduction of the effective flow path area is suppressed. Can be done.
The fourth straight line portion may be, for example, a chamfered portion in which the corner on the passage forming surface side at the joint portion between the first straight line portion and the second straight line portion is chamfered linearly in the above side cross-sectional view. Similarly, the fifth straight line portion may be, for example, a chamfered portion in which the corner on the passage forming surface side at the joint portion between the second straight line portion and the third straight portion is chamfered linearly in the above side cross-sectional view.

(5) In some embodiments, in the configuration of (4) above,
The lengths of the fourth straight line portion and the fifth straight line portion in the side cross-sectional view including the rotation axis of the steam turbine may be 20 mm or more and 70 mm or less.

The expansion wave and supersonic deflection described above occur when passing through a convex portion having a predetermined angle in the direction in which the cross-sectional area of the flow path expands, regardless of the size of the steam turbine. Therefore, when forming a convex portion capable of causing such an expansion wave or supersonic deflection, if the dimensions of the fourth straight portion and the fifth straight portion are too large, the installation area of the exhaust chamber is increased or the effective flow path area is increased. On the contrary, if the dimensions of the 4th straight line portion and the 5th straight line portion are too small, a sufficient effect may not be obtained.
In this regard, according to the configuration of (4) above, the fourth straight line portion and the fifth straight line portion are formed within a range of 20 mm or more and 70 mm or less along the rotation axis direction to form the exhaust chamber. It is possible to provide an exhaust chamber of a steam turbine that can enjoy the above-mentioned benefit (4) while having a configuration that is easy to process while suppressing an increase in the installation area.

(6) In some embodiments, in any one of the above configurations (2) to (5),
The ratio of the length (S) of the third straight line portion in the radial direction of the bearing cone to the distance (H) from the base end portion of the third straight line portion in the radial direction to the inner peripheral surface of the casing (H). S / H) may be 0.2 or more and 0.5 or less.

After diligent research, the present inventors have determined the length (S) of the third straight line portion in the radial direction of the bearing cone and the length (S) in the radial direction in any one of the above-mentioned configurations (2) to (5). Exhaust efficiency is determined when the ratio (S / H) to the distance (H) from the base end of the third straight line to the inner peripheral surface of the casing is within the range of 0.2 or more and 0.5 or less. I found out that it can be improved.
That is, the exhaust efficiency of the exhaust chamber does not improve if the length of the third straight portion is too long or too short, but according to the configuration of (6) above, the exhaust efficiency of the third straight portion in the radial direction of the bearing cone The ratio (S / H) of the length (S) to the distance (H) from the base end of the third straight line portion in the radial direction to the inner peripheral surface of the casing is 0.2 or more and 0.5. By forming the third straight line portion so as to be within the following range, interference between the circulating flow and the main exhaust flow can be suppressed and the exhaust efficiency can be improved.

(7) In some embodiments, in the configuration of (6) above,
The flow guide may be formed so that the length (S) of the third straight line portion along the radial direction is non-uniform in the circumferential direction of the rotation axis.

In the circumferential direction of the steam turbine, at a position where interference between the exhaust circulation flow and the main exhaust flow is relatively likely to occur, by ensuring a long length of the third straight line portion along the radial direction of the steam turbine, the above-mentioned circulation flow can be obtained. It is possible to improve the exhaust efficiency by suppressing the interference with the main exhaust flow. On the other hand, the manufacturing cost of the flow guide can be suppressed or reduced by lowering the height of the third straight line portion at a position where interference between the circulating flow and the main exhaust flow is relatively unlikely to occur in the circumferential direction.
Therefore, according to the configuration of (7) above, for example, the length (S) of the third straight line portion of the flow guide along the radial direction is set according to the tendency of interference between the circulating exhaust flow and the main exhaust flow. By forming the exhaust chamber non-uniformly in the circumferential direction of the rotation axis, it is possible to provide an exhaust chamber of a steam turbine that can achieve both improvement of exhaust efficiency and cost reduction of flow guide production.

(8) In some embodiments, in the configuration of (7) above,
In the flow guide, the length (S) of the third straight line portion along the radial direction is 90 to 90 ° in the range of −90 to 90 °, with 0 ° vertically above in the direction of the rotation axis of the steam turbine. It may be formed longer than the range of 270 °.

In the circumferential direction of the steam turbine, for example, if an exhaust outlet is provided in the lower part of the exhaust chamber (lower exhaust) and the lower exhaust is discharged, the length of the third straight line portion located on the lower side in the circumferential direction in the flow guide. Even if it is short, the effect of exhaust interference is small. Therefore, according to the configuration (8) above, it is possible to provide an exhaust chamber of a steam turbine suitable for application to an exhaust chamber adopting a configuration in which exhaust gas is extracted from the lower part of the exhaust chamber.

(9) In some embodiments, in the configuration of (7) or (8) above,
In the flow guide, the peak of the length (S) of the third straight line portion along the radial direction is 0 ° in the circumferential direction of the rotation axis, and the moving blade is in the range of 0 to 90 °. It may be configured to exist on the downstream side in the rotation direction of the.

The interference between the circulating flow flowing in a spiral after passing through the diffuser passage and the main exhaust flow shifted from 0 ° to the downstream side in the rotation direction of the moving blade when the vertical upper direction was 0 ° in the circumferential direction of the rotation axis of the steam turbine. Prone to occur in position.
Therefore, according to the configuration of (9) above, the peak of the length (S) of the third straight line portion is 0 ° above the vertical direction in the circumferential direction of the rotation axis, and the rotor blade is in the range of 0 to 90 °. Since the flow guide is configured so as to exist on the downstream side in the rotation direction, as described in (7) above, the exhaust chamber of the steam turbine can achieve both improvement of exhaust efficiency and cost reduction of flow guide production. Can be provided.

(10) In some embodiments, in any one of the above configurations (4) to (9),
In the side sectional view including the rotation axis of the steam turbine, the inclination angle of the second straight line portion with respect to the fourth straight line portion may be 10 ° or more and 20 ° or less.

The exhaust gas passing near the inlet (upstream end side) of the exhaust chamber, that is, the exhaust gas (fluid) immediately after passing through the final stage blade, has strong momentum, and if the flow direction is suddenly changed, peeling occurs. This is not preferable because the exhaust efficiency is lowered.
In this regard, according to the configuration of (10) above, the second straight line portion is 10 ° or more and 20 ° or less with respect to the fourth straight line portion arranged on the upstream side of the second straight line portion in the flow guide. By continuing at an inclination angle, it is possible to suppress the occurrence of peeling when the flow of exhaust along the fourth straight portion passes through the joint portion between the fourth straight portion and the second straight portion, and the exhaust efficiency is lowered. Can be suppressed.

(11) In some embodiments, in any one of the above (4) to (10) configurations.
In a side sectional view including the rotation axis of the steam turbine, the inclination angle of the fifth straight line portion with respect to the second straight line portion may be 10 ° or more and 20 ° or less.

According to the configuration of (11) above, as described in (10) above, the fifth straight line portion arranged on the most downstream side of the flow guide is arranged on the upstream side of the flow guide with respect to the fifth straight line portion. By being continuously formed at an inclination angle of 10 ° or more and 20 ° or less with respect to the second straight portion to be formed, the flow of exhaust gas along the second straight portion flows between the second straight portion and the fifth straight portion. It is possible to suppress the occurrence of peeling when passing through the joint with the vehicle and suppress the decrease in exhaust efficiency.

(12) In some embodiments, in any one of the above configurations (2) to (11),
In a side sectional view including the rotation axis of the steam turbine, the inclination angle of the second straight line portion with respect to the first straight line portion may be equal to or less than the inclination angle of the third straight line portion with respect to the second straight line portion. ..

As described above, the exhaust gas passing near the inlet (upstream end side) of the exhaust chamber has a strong momentum, and if the flow direction is suddenly changed, peeling occurs and the exhaust efficiency is lowered, which is not preferable. On the other hand, the third straight portion existing on the outlet side (downstream) of the exhaust chamber is guided by the second straight portion existing on the upstream side of the third straight portion, so that the exhaust flow in the radial direction is to some extent. In addition to being formed, the flow path area is wider than immediately after passing through the final stage rotor blade, so the exhaust momentum is weaker than immediately after passing through the final stage rotor blade. Therefore, the inclination angle of the third straight line portion with respect to the second straight line portion can be made larger than the inclination angle of the second straight line portion with respect to the first straight line portion.
Therefore, according to the configuration of (12) above, it is possible to efficiently guide the exhaust gas and improve the exhaust efficiency while suppressing the occurrence of peeling.

According to at least one embodiment of the present disclosure, it is possible to provide an exhaust chamber of a steam turbine that can achieve both improvement of exhaust efficiency and cost reduction of flow guide production.

It is the schematic sectional drawing along the axial direction of the steam turbine which concerns on one Embodiment of this disclosure. It is a side sectional view which shows the structural example of the exhaust chamber of the steam turbine which concerns on one Embodiment. It is sectional drawing which follows the AA line of FIG. It is a figure which shows the structural example of the exhaust chamber of the steam turbine which concerns on one Embodiment. It is sectional drawing seen from the rotation axis direction of the steam turbine in one Embodiment. It is a side sectional view which shows the structural example of the flow guide including the 4th straight line part and the 5th straight line part in one Embodiment. It is a side sectional view which shows the structural example of the flow guide including the 4th straight line part and the 5th straight line part in one Embodiment, and shows how the 4th straight line part and the 5th straight line part are formed by chamfering the passage formation surface. It is a schematic diagram. It is the schematic which illustrates the length along the rotation center axis direction of the 4th straight line part and 5th straight line part in one Embodiment. It is the schematic which illustrates the installation angle range of the 3rd straight line part in one Embodiment. The ratio of the length (S) of the third straight line portion in one embodiment to the distance (H) from the base end portion of the third straight line portion in the radial direction (D) to the inner wall surface (inner peripheral surface) of the casing (H). It is a graph which shows the relationship of S / H). It is the schematic in the direction view of the rotation axis which shows the structural example of the 3rd straight line part in one Embodiment. It is a graph which shows the length distribution around the rotation axis of the 3rd straight line part in one Embodiment. It is a schematic diagram which shows the modification of the length distribution around the rotation center axis of the 3rd straight line part in one Embodiment. It is the schematic which illustrates the angle of the 4th straight line part and 5th straight line part in one Embodiment.

Hereinafter, some embodiments of the present invention will be described with reference to the drawings. However, the scope of the present invention is not limited to the following embodiments. The dimensions, materials, shapes, relative arrangements, and the like of the components described in the following embodiments are not intended to limit the scope of the present invention to that alone, but are merely explanatory examples.

First, the overall configuration of the steam turbine according to some embodiments will be described.
FIG. 1 is a schematic cross-sectional view of the steam turbine according to the embodiment along the axial direction. As shown in FIG. 1, the steam turbine 1 includes a rotor 2 rotatably supported by a bearing portion 6, a multi-stage rotor blade 8 attached to the rotor 2, and an inner side accommodating the rotor 2 and the rotor blade 8. It includes a casing 11 and a plurality of stages of stationary blades 9 attached to the inner casing 11 so as to face the moving blades 8. An outer casing 12 is provided on the outside of the inner casing 11.
When steam is introduced into the inner casing 11 from the steam inlet 3, such a steam turbine 1 expands and accelerates when the steam passes through the stationary blade 9, and works on the moving blade 8. The rotor 2 is designed to rotate.

Further, the steam turbine 1 includes an exhaust chamber 14. The exhaust chamber 14 is located on the downstream side 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 ST1) that has passed through the moving blade 8 and the stationary blade 9 in the inner casing 11 flows into the exhaust chamber 14 from the exhaust chamber inlet 14A, passes through the inside of the exhaust chamber 14, and is below the exhaust chamber 14. It is designed to be discharged to the outside of the steam turbine 1 from the exhaust chamber outlet 14B provided on the side.
A condenser (not shown) may be provided below the exhaust chamber 14. The steam that has finished working on the moving blades 8 in the steam turbine 1 may flow into the condenser from the exhaust chamber 14 via the exhaust chamber outlet 14B.

Next, the configuration of the exhaust chamber 14 of the steam turbine 1 according to some embodiments will be described more specifically.
FIG. 2 is a side sectional view showing a configuration example of an exhaust chamber of the steam turbine according to the embodiment. FIG. 3 is a cross-sectional view taken along the line AA of FIG.
As illustrated in FIGS. 2 and 3, the exhaust chamber 14 of the steam turbine 1 according to at least one embodiment of the present invention includes a casing 10, a bearing cone 16 provided in the casing 10, and a casing. A flow guide 20 is provided inside the bearing cone 16 on the outer side in the radial direction D, and has a passage forming surface 22 that forms a diffuser passage 18 (steam passage) together with the bearing cone 16. The exhaust chamber 14 has an exhaust chamber outlet 14B on the lower side, and steam is discharged from the steam turbine 1 through the exhaust chamber outlet 14B.

The casing 10 is composed of the inner casing 11 and the outer casing 12 of the steam turbine 1 described above.
The bearing cone 16 is provided on the inner peripheral side of the flow guide 20 so as to cover the bearing portion 6 in the casing 15. Further, as shown in FIG. 2, the downstream end 16A of the bearing cone 16 is connected to the inner wall surface 10A of the casing 15.
The diffuser passage 18 has a shape in which the cross-sectional area gradually increases, and when the high-speed steam flow ST1 passing through the final stage blade 8A of the steam turbine 1 flows into the diffuser passage 18, the steam flow ST1 is decelerated. , The kinetic energy is converted into pressure (static pressure recovery).
The diameter of the flow guide 20 is increased toward the downstream side of the steam flow ST1, and the downstream end 20A is formed to have a larger diameter than the upstream end 20B. That is, the flow guide 20 is adjacent to the steam turbine 1 so that the passage forming surface 22 defining the diffuser passage 18 expands in diameter toward the downstream side at least inside the steam turbine 1 in a side cross-sectional view including the rotation axis C. Includes a plurality of straight portions whose ends are non-parallel and continuous.
The downstream end 20A of the flow guide 20 is an end portion arranged on the downstream side of the steam flow ST1 among both ends in the axial direction of the flow guide 20, and means the end portion having a larger inner diameter. .. Further, the upstream end 20B of the flow guide 20 is an end portion arranged on the upstream side of the steam flow ST1 among both ends in the axial direction of the flow guide 20, and means the end portion having the smaller inner diameter. ..
The passage forming surface 22 of the flow guide 20 has a first straight line portion 31 arranged on the most upstream side of the flow guide 20 and the rotation of the steam turbine 1 in a side sectional view including the rotation axis C of the steam turbine 1. In the side sectional view including the axis C, the second straight line portion 32 arranged on the downstream side of the flow guide 20 with respect to the first straight line portion 31 is included.

As illustrated in FIGS. 1 and 2, the first straight line portion 31 has a predetermined inclination angle with respect to the rotation axis C, and is located downstream of the flow guide 20. It extends linearly so that the distance from the rotation axis C increases as it goes toward it. That is, the portion of the flow guide 20 on the upstream side including the first straight line portion 31 in the side cross-sectional view including the rotation axis C of the steam turbine 1 is cylindrical so that the central axis is along the rotation axis C. Alternatively, the downstream side is formed in the shape of a large-diameter cone (or truncated cone).
The second straight line portion has an inclination angle larger than that of the first straight line portion 31 with respect to the rotation axis C, and is linear so that the distance from the rotation axis C increases toward the downstream side of the flow guide 20. It is protracted (see FIGS. 1 and 2). That is, in the flow guide 20, the portion including the second straight line portion 32 in the side cross-sectional view including the rotation axis C of the steam turbine 1 has a central axis along the rotation axis C and a large-diameter cone (or cone) on the downstream side. It is formed in a truncated cone shape (see FIG. 3).

Here, when manufacturing the exhaust chamber 14 of the steam turbine 1, a curved flow guide 20 may be adopted in a side cross-sectional view including the rotation axis C of the steam turbine 1 in order to improve the performance of the exhaust chamber. However, since the production of the curved flow guide 20 requires a complicated processing process, the number of steps and the cost are increased as compared with the case of producing the linear flow guide 20 in the same side cross-sectional view.
In this respect, the exhaust chamber 14 of the steam turbine 1 having the above-described configuration is configured such that the passage forming surface 22 of the flow guide 20 includes the first straight line portion 31 and the second straight line portion 32 in the above side cross-sectional view. Therefore, for example, the man-hours and costs required for manufacturing the flow guide 20 can be suppressed as compared with the case where the curved flow guide is formed in the side cross-sectional view. Further, in the first straight line portion 31 and the second straight line portion 32, adjacent ends thereof are continuous in a non-parallel manner so that the passage forming surface 22 facing the diffuser passage 18 expands in diameter toward the downstream side, and at least. Since the second straight line portion 32 is provided so as to be inclined so as to increase the diameter toward the downstream side with respect to the rotation axis C of the steam turbine 1, for example, the passage forming surface 22 defining the diffuser passage 18 is a straight line parallel to the rotation axis C. The exhaust flow (steam flow ST1) can be guided more smoothly than in the case of being composed of a portion and a straight portion orthogonal to the portion. Therefore, it is possible to provide the exhaust chamber 14 of the steam turbine 1 that can achieve both improvement of exhaust efficiency and cost reduction of manufacturing the flow guide 20.
Further, by providing the first straight line portion 31 and the second straight line portion 32, it is possible to suppress the interference between the main exhaust flow of the steam flow ST1 and the circulating flow ST2.

Subsequently, FIG. 4 is a diagram showing a configuration example of an exhaust chamber of the steam turbine according to the embodiment. FIG. 5 is a cross-sectional view taken from the direction of the rotation axis of the steam turbine.
As illustrated non-limitingly in FIGS. 4 and 5, in some embodiments, in the configuration described above, the passage forming surface 22 of the flow guide 20 is in a side sectional view including the rotation axis C of the steam turbine 1. Therefore, the third straight line portion 33 arranged on the downstream side of the flow guide 20 with respect to the second straight line portion 32 may be further included.

The third straight line portion 33 has an inclination angle larger than that of the second straight line portion 32 with respect to the rotation axis C, and is linear so that the distance from the rotation axis C increases toward the downstream side of the flow guide 20. It may be extended to. That is, in the flow guide 20, the portion including the third straight line portion 33 in the side cross-sectional view including the rotation axis C of the steam turbine 1 has a central axis along the rotation axis C and a large-diameter conical shape on the downstream side. It may be formed in an annular shape or a flange shape extending in the radial direction of the rotor 2 from the downstream end of the second straight line portion 32 (see FIG. 5).
The length (S) of the third straight line portion 33 along the radial direction D may be uniformly formed in the circumferential direction R of the rotation axis C. That is, in the flow guide 20, the end portion on the large diameter side of the portion including the third straight line portion 33 in the side cross-sectional view including the rotation axis C of the steam turbine 1 has a circular (perfect circle) shape in the axial direction. It may be formed in.
In the flow guide 20 having the configuration including the first straight line portion 31, the second straight line portion 32, and the third straight line portion 33 described above, the first straight line portion 31 is upstream (uppermost flow) of the steam flow ST1 in the exhaust chamber 14. ) Side straight part (entrance side straight part). The third straight section 33 is a straight section (outlet side straight section) located on the downstream (most downstream) side of the steam flow ST1 in the exhaust chamber 14, and is a straight section of the steam flow ST1 that has passed through the final stage rotor blade 8A. It can function as a counterbore that suppresses interference between the main exhaust flow and the circulating flow ST2 that has passed through the downstream end 20A of the flow guide 20 and has a swirling component added. The second straight line portion 32 is an intermediate straight line portion that connects the first straight line portion 31 and the third straight line portion 33.

As described above, according to the configuration including the third straight line portion 33 in addition to the first straight line portion 31 and the second straight line portion 32, the main exhaust flow and the circulating flow ST2 of the steam flow ST1 after passing through the flow guide 20. Interference with can be suppressed. Therefore, although the configuration is simple, the exhaust chamber performance can be further improved while suppressing the man-hours for manufacturing the flow guide 20.

FIG. 6 is a side sectional view showing a configuration example of a flow guide including the fourth straight line portion and the fifth straight line portion in one embodiment. FIG. 7 is a side sectional view showing a configuration example of the flow guide including the fourth straight line portion and the fifth straight line portion in one embodiment, and the fourth straight line portion and the fifth straight line portion are formed by chamfering the passage forming surface. It is a schematic diagram which shows the state.
As illustrated in FIGS. 6 and 7, in some embodiments, in the configuration including the third straight line portion 33, the passage forming surface 22 of the flow guide 20 is the rotation axis of the steam turbine 1. A fourth straight line portion 34 extending linearly from the downstream end 31A of the first straight line portion 31 toward the upstream end 32B of the second straight line portion 32 in a side sectional view including C, and is a first straight line portion. In a side cross-sectional view including the fourth straight line portion 34 shorter than the 31 and the second straight line portion 32 and the rotation axis C of the steam turbine 1, the downstream end 32A of the second straight line portion 32 to the upstream end of the third straight line portion 33. The fifth straight line portion 35 extending linearly toward 33B may further include a second straight line portion 32 and a fifth straight line portion 35 shorter than the third straight line portion 33.

In the fourth straight line portion 34, for example, as shown in FIG. 6, the portion of the flow guide 20 in which the passage forming surface 22 on the inner peripheral side is composed of the first straight line portion 31 and the passage forming surface 22 on the inner peripheral side are It may be the inner peripheral surface of the enlarged diameter portion formed in a conical (or truncated cone) shape so as to connect the portion formed by the second straight portion 32. Similarly, in the fifth straight line portion 35, the portion of the flow guide 20 in which the passage forming surface 22 on the inner peripheral side is composed of the second straight portion 32 and the passage forming surface 22 on the inner peripheral side are the third straight portion 33. It may be an inner peripheral surface of a diameter-expanded portion formed in a conical (or truncated cone) shape so as to connect a portion composed of.
In addition, only one of the 4th straight line portion 34 and the 5th straight line portion 35 may be provided.

As described above, according to the configuration including the fourth straight line portion 34 and the fifth straight line portion 35, the fourth straight line portion 34 between the first straight line portion 31 and the second straight line portion 32 and the second straight line portion 32 Of the passage forming surfaces 22 that define the diffuser passage 18 by the fifth straight portion 35 between the first straight portion 33 and the third straight portion 33, the connecting portion between the first straight portion 31 and the fourth straight portion 34 and the fourth straight portion Fluidly convex to the connecting portion between the 34 and the second straight portion 32, the connecting portion between the second straight portion 32 and the fifth straight portion 35, and the connecting portion between the fifth straight portion 35 and the third straight portion 33. The convex portion 40 of the shape is formed. Then, when the exhaust passes through these convex portions 40, an expansion wave is generated in each convex portion 40. As a result, the exhaust (fluid) can be deflected at supersonic speed to improve the followability of the fluid to the flow guide shape. Therefore, the development of the boundary layer is suppressed and the performance deterioration due to the reduction of the effective flow path area is suppressed. Can be done.
In the fourth straight line portion 34, for example, as shown in FIG. 7, the corner on the passage forming surface 22 side at the joint portion between the first straight line portion 31 and the second straight line portion 32 is linear in the side cross-sectional view. It may be a chamfered portion. Similarly, the fifth straight line portion 35 is a chamfered portion in which, for example, the corner on the passage forming surface 22 side at the joint portion between the second straight line portion 32 and the third straight line portion 33 is chamfered linearly in the above side cross-sectional view. You may.

In some embodiments, in the configuration including the fourth straight line portion 34 and the fifth straight line portion 35 described above, the fourth straight line portion 34 and the fifth straight line portion 35 in the side sectional view including the rotation axis C of the steam turbine 1 The length may be 20 mm or more and 70 mm or less, respectively (see, for example, FIG. 8).
That is, when the lengths of the fourth straight line portion 34 and the fifth straight line portion 35 along the rotation axis C direction are t ₄ and t ₅ , respectively, 20 mm ≤ t ₄ ≤ 70 mm and 20 mm ≤ t ₅ ≤ 70 mm. Fulfill. As long as such a range is satisfied, t ₄ and t ₅ may have the same value or different values.

The expansion wave and supersonic deflection described above occur when passing through the convex portion 40 having a predetermined angle in the direction in which the cross-sectional area of the flow path expands, regardless of the size of the steam turbine 1. Therefore, when forming the convex portion 40 capable of causing such an expansion wave or supersonic deflection, if the dimensions of the fourth straight line portion 34 and the fifth straight line portion 35 are too large, the installation area of the exhaust chamber 14 increases, or It is not preferable because it causes a decrease in the effective flow path area, and conversely, if the dimensions of the fourth straight line portion 34 and the fifth straight line portion 35 are too small, a sufficient effect may not be obtained.
In this regard, by forming the fourth straight line portion 34 and the fifth straight line portion 35 within a range of 20 mm or more and 70 mm or less along the rotation axis C direction, an increase in the installation area of the exhaust chamber is suppressed. It is possible to provide the exhaust chamber 14 of the steam turbine 1 which can enjoy the benefits described in the above-described embodiment while having a configuration that is easy to process.

Subsequently, the configuration of the third straight line portion 33 in some embodiments will be described in more detail.
FIG. 9 is a schematic view illustrating an installation angle range of the third straight line portion in one embodiment.
In some embodiments, for example, as illustrated in FIGS. 4 and 6-9, in any one of the above configurations, the third straight section 33 extends along a direction orthogonal to the rotation axis C. It may be present.
In the present disclosure, the direction orthogonal to the rotation axis C includes not only 90 ° with respect to the rotation axis C but also a range of several degrees to a dozen degrees before and after the rotation axis C. For example, the third straight line portion 33 is provided in the range of -10 ° to 15 ° when the vertically upper side is defined as 0 °, the upstream side of the steam flow ST1 is defined as positive, and the downstream side is defined as negative in the side cross-sectional view. It may be (see FIG. 9). For example, in FIG. 9, with respect to the vertical direction, the allowable range of the inclination angle to the upstream side of the steam flow ST1 is θ ₃ , and the allowable range of the inclination angle to the downstream side is θ ₄ , and 0 ° ≤ θ ₃ ≤ An example is shown in which 15 ° and 0 ° ≤ θ ₄ ≤ 10 °.

As described above, according to the configuration in which the third straight line portion 33 of the flow guide 20 extends along the direction orthogonal to the rotation axis C of the steam turbine 1, the circulating flow ST2 flowing in a spiral shape after passing through the diffuser passage 18 Since it is possible to physically block the merging with the main exhaust flow ST1 discharged through the diffuser passage 18, it is possible to effectively suppress the interference between the main exhaust flow ST1 and the circulating flow ST2. .. Therefore, the exhaust efficiency can be improved.

FIG. 10 shows the length (S) of the third straight line portion in one embodiment and the distance (H) from the base end portion of the third straight line portion in the radial direction (D) to the inner wall surface (inner peripheral surface) of the casing. It is a graph which shows the relationship of the ratio (S / H) of.
In some embodiments, for example, as illustrated in FIGS. 4 and 10, in a configuration in which the third straight line portion 33 described above extends along a direction orthogonal to the rotation axis C, the bearing. The length (S) of the third straight portion 33 in the radial direction D of the cone 16 and the distance (S) from the base end portion 33A of the third straight portion 33 in the radial direction D to the inner wall surface 10A (inner peripheral surface) of the casing 10. The ratio (S / H) to H) may be 0.2 or more and 0.5 or less (that is, 0.2 ≦ (S / H) ≦ 0.5).

As a result of diligent research, the present inventors have made a configuration in which the above-mentioned third straight line portion 33 extends in a direction orthogonal to the rotation axis C, and the length of the third straight line portion 33 in the radial direction D of the bearing cone 16. The ratio (S / H) of (S) to the distance (H) from the base end portion 33A of the third straight line portion 33 to the inner peripheral surface 10A of the casing 10 in the radial direction D is 0.2 or more. Moreover, it was found that the exhaust efficiency can be improved when the range is 0.5 or less.
That is, the exhaust efficiency of the exhaust chamber 14 does not improve if the length of the third straight portion 33 is too long or too short, but as described above, the exhaust efficiency of the third straight portion 33 in the radial direction D of the bearing cone 16 The ratio (S / H) of the length (S) to the distance (H) from the base end portion 33A of the third straight line portion 33 to the inner peripheral surface 10A of the casing 10 in the radial direction D is 0.2 or more. In addition, by forming the third straight line portion 33 so as to be within the range of 0.5 or less, interference between the circulating flow ST2 and the main exhaust flow ST1 can be suppressed and the exhaust efficiency can be improved.

Subsequently, the configuration of the third straight line portion 33 in some embodiments will be described in more detail.
FIG. 11 is a schematic view in the direction of the rotation axis showing a configuration example of the third straight line portion in one embodiment. FIG. 12 is a graph showing the length distribution of the third straight line portion in one embodiment around the rotation axis.
In some embodiments, the flow guide 20 is along the radial direction D in a configuration that satisfies 0.2 ≦ (S / H) ≦ 0.5 as described above, for example, as illustrated in FIGS. 11 and 12. The length (S) of the third straight line portion 33 may be formed non-uniformly in the circumferential direction of the rotation axis C.
That is, the length S of the third straight line portion 33 in the direction along the radial direction D of the bearing cone 16 may have a different distribution in the circumferential direction R centered on the rotation axis C. In other words, the third straight line portion 33 is a second position in which the first position in the circumferential direction R and the position in the circumferential direction R are different from the first position, and the position in the radial direction D is different from the first position. It may include a second position having a different length or width.

In the circumferential direction R of the steam turbine 1, the length of the third straight line portion 33 along the radial direction D of the steam turbine 1 is secured long at a position where interference between the exhaust circulation flow ST2 and the main exhaust flow ST1 is relatively likely to occur. As a result, the interference between the circulating flow ST2 and the main exhaust flow ST1 can be suppressed and the exhaust efficiency can be improved. On the other hand, at a position where interference between the circulating flow ST2 and the main exhaust flow ST1 is relatively unlikely to occur in the circumferential direction R, the height of the third straight line portion 33 is lowered to suppress or reduce the manufacturing cost of the flow guide 20. be able to.
Therefore, for example, the length (S) of the third straight line portion 33 of the flow guide 20 along the radial direction D is set around the rotation axis C according to the likelihood of interference between the exhaust circulation flow ST2 and the main exhaust flow ST1. By forming the exhaust chamber 14 non-uniformly in the direction R, it is possible to provide the exhaust chamber 14 of the steam turbine 1 which can achieve both improvement of exhaust efficiency and cost reduction of manufacturing the flow guide 20.

In some embodiments, in a configuration in which the length of the third straight line portion 33 along the radial direction D described above is non-uniform in the circumferential direction of the rotation axis C, the flow guide 20 has a thirth along the radial direction D. Even if the length (S) of the three straight line portions 33 is formed so that the range of −90 to 90 ° is longer than the range of 90 to 270 °, with the vertical upper side as 0 ° in the direction of the rotation axis C of the steam turbine 1. Good (see, eg, FIGS. 11 and 12).
That is, the upper half of the third straight line portion 33 may be formed longer in the radial direction D than the lower half in the circumferential direction R centered on the rotation axis C.

In the circumferential direction R of the steam turbine 1, for example, if an exhaust outlet is provided in the lower part of the exhaust chamber 14 (lower exhaust) to exhaust the lower exhaust gas, the flow guide 20 is located below the circumferential direction R. Even if the length of the three straight portions 33 is short, the influence of exhaust interference is small. Therefore, according to the configuration in which the upper half of the third straight portion 33 is formed longer than the lower half in the radial direction D, it is applied to the exhaust chamber 14 adopting the configuration in which the exhaust gas is extracted from the lower portion of the exhaust chamber 14. An exhaust chamber 14 of a suitable steam turbine 1 can be provided.

FIG. 13 is a schematic view showing a modified example of the length distribution around the rotation center axis of the third straight line portion in one embodiment.
In some embodiments, for example, as illustrated non-limitingly in FIG. 13, the length of the third straight line portion 33 along the radial direction D described above is non-uniform in the circumferential direction of the rotation axis C, or the rotation axis. In the circumferential direction R centered on C, in the configuration in which the upper half of the third straight line portion 33 is formed longer in the radial direction D than the lower half, the flow guide 20 is the third straight line portion 33 along the radial direction D. The peak of the length (S) is configured to exist on the downstream side in the rotation direction (turning direction) of the moving blade 8 in the range of 0 to 90 ° with the vertical upper side as 0 ° in the circumferential direction R of the rotation axis C. May be done.
That is, in the third straight line portion 33, the angular position in the circumferential direction R at which the length S along the radial direction D of the third straight line portion 33 has a peak value (Smax) moves more than vertically above (0 °). It may be configured to be shifted to a position downstream of the blade 8 in the rotational direction and satisfying the upper half of the flow guide 20.

The interference between the circulating flow ST2 and the main exhaust flow ST1 that flow in a spiral after passing through the diffuser passage 18 is such that when the vertical upper direction is 0 ° in the circumferential direction R of the rotation axis C of the steam turbine 1, the moving blade 8 is more than 0 °. It tends to occur at a position shifted to the downstream side in the rotation direction.
Therefore, as described above, the peak of the length (S) of the third straight line portion 33 is the rotation of the rotor blade 8 in the range of 0 to 90 ° with the vertical upper side as 0 ° in the circumferential direction R of the rotation axis C. According to the configuration in which the flow guide 20 is configured so as to exist on the downstream side in the direction, the exhaust chamber 14 of the steam turbine 1 capable of achieving both improvement of exhaust efficiency and cost reduction of manufacturing the flow guide 20 is provided. Can be done.

FIG. 14 is a schematic view illustrating the angles of the fourth straight line portion and the fifth straight line portion in one embodiment.
In some embodiments, for example, as illustrated in FIG. 14, but in a configuration including the fourth straight section 34 described above (which may further include a fifth straight section 35), the steam turbine 1 In the side sectional view including the rotation axis C, the inclination angle θ ₆ of the second straight line portion 32 with respect to the fourth straight line portion 34 (more specifically, its virtual extension line) is 10 ° or more and 20 ° or less. May be good. That is, θ ₆ (tilt angle θ ₆ ), which is the difference between the inclination angle of the fourth straight line portion 34 with respect to the rotation axis C and the inclination angle of the second straight line portion 32 with respect to the rotation axis C, is 10 ° ≤ θ ₆ ≤ 20. Can meet °.

The exhaust gas passing near the inlet (upstream end side) of the exhaust chamber 14, that is, the exhaust gas (fluid) immediately after passing through the final stage rotor blade 8A has strong momentum, and if the flow direction is suddenly changed, peeling occurs. It is not preferable because it is generated and the exhaust efficiency is lowered.
In this respect, as described above, the second straight line portion 32 of the flow guide 20 is 10 ° or more with respect to the fourth straight line portion 34 arranged on the upstream side of the flow guide 20 with respect to the second straight line portion 32, and According to the configuration in which the inclination angle θ ₆ is 20 ° or less, the exhaust flow along the fourth straight line portion 34 is peeled off when passing through the joint portion between the fourth straight line portion 34 and the second straight portion 32. It is possible to suppress the occurrence and suppress the decrease in exhaust efficiency.

In some embodiments, for example, as illustrated in FIG. 14, in the configuration including the fifth straight line portion 35 described above (which may further include the fourth straight line portion 34), the rotation axis C of the steam turbine 1 is set. In the side sectional view including, the inclination angle θ ₇ of the fifth straight line portion 35 with respect to the second straight line portion 32 (more specifically, its virtual extension line) may be 10 ° or more and 20 ° or less. That is, θ ₇ (tilt angle θ ₇ ), which is the difference between the inclination angle of the fifth straight line portion 35 with respect to the rotation axis C and the inclination angle of the second straight line portion 32 with respect to the rotation axis C, is 10 ° ≤ θ ₇ ≤ 20 °. Can be met.

As described above, the fifth straight line portion 35 of the flow guide 20 is 10 ° or more and 20 ° or less with respect to the second straight line portion 32 arranged on the upstream side of the flow guide 20 with respect to the fifth straight line portion 35. According to the configuration in which the exhaust gas flows along the second straight line portion 32 continuously at the inclination angle θ ₇ , peeling occurs when the exhaust flow along the second straight line portion 32 passes through the joint portion between the second straight line portion 32 and the fifth straight line portion 35. Can be suppressed to suppress a decrease in exhaust efficiency.

In some embodiments, for example, as illustrated in FIG. 9, in any one of the above configurations, the first straight line portion 31 (more specifically, in a side sectional view including the rotation axis C of the steam turbine 1). The inclination angle θ ₁ of the second straight line portion 32 with respect to the virtual extension line) may be equal to or less than the inclination angle θ ₂ of the third straight line portion 33 with respect to the second straight line portion 32 (more specifically, the virtual extension line). .. That is, the inclination angle of the second straight line portion 32 with respect to the rotation axis C may be equal to or less than the difference between the inclination angle of the second straight line portion 32 with respect to the rotation axis C and the inclination angle of the third straight line portion 33 with respect to the rotation axis C. , The above θ ₁ and θ ₂ can satisfy θ ₁ ≤ θ ₂ .

As described above, the exhaust gas passing near the inlet of the exhaust chamber 14 (exhaust chamber inlet 14A) has a strong momentum, and if the flow direction is suddenly changed, peeling occurs and the exhaust efficiency is lowered, which is not preferable. On the other hand, the third straight line portion 33 existing on the outlet side (downstream) of the exhaust chamber 14 is guided by the second straight line portion 32 existing on the upstream side of the third straight line portion 33, and is directed toward the radial direction D. In addition to the exhaust flow being formed to some extent, the flow path area is wider than immediately after passing through the final stage rotor blade 8A, so that the exhaust momentum is weaker than immediately after passing through the final stage rotor blade 8A. Therefore, the inclination angle θ ₂ of the third straight line portion 33 with respect to the second straight line portion 32 can be made larger than the inclination angle θ ₁ of the second straight line portion 32 with respect to the first straight line portion 31.
Therefore, according to the configuration that satisfies θ ₁ ≤ θ ₂ as described above, it is possible to efficiently guide the exhaust gas and improve the exhaust efficiency while suppressing the occurrence of peeling.

According to at least one embodiment of the present disclosure, it is possible to provide an exhaust chamber of a steam turbine that can achieve both improvement of exhaust efficiency and cost reduction of flow guide production.

The present invention is not limited to the above-described embodiment, and includes a modified form of the above-described embodiment and a combination of these embodiments.

1 Steam turbine 2 Rotor (turbine rotor)
3 Steam inlet 6 Bearing part 8 Moving blade 8A Final stage moving blade 9 Static blade 10 Casing 10A Inner wall surface 11 Inner casing 12 Outer casing 14 Exhaust chamber 14A Exhaust chamber inlet 14B Exhaust chamber outlet 16 Bearing cone 16A Downstream end 18 Diffuser passage 20 Flow Guide 20A Downstream end 20B Upstream end 22 Passage forming surface 30 Straight section 31 First straight section (upstream straight section)
32 Second straight part (intermediate straight part)
33 Third straight section (downstream straight section / tsuitate)
33A Base end 34 4th straight line (upstream side surface)
35 5th straight line part (downstream side surface taking part)
40 Convex C Rotation axis (center axis)
D Radial direction H Distance from the base end of the third straight part in the radial direction to the inner peripheral surface of the casing R Circumferential direction S _Radial length of the third straight part S _{max Radial} length peak of the third straight part ST1 Steam flow (main exhaust flow)
ST2 swirl flow

Claims (12)

The exhaust chamber of a steam turbine
Casing and
A bearing cone provided in the casing and
A flow guide provided in the casing on the radial outer side of the bearing cone and having a passage forming surface for forming a diffuser passage together with the bearing cone.
The passage forming surface of the flow guide is
A first straight line portion arranged on the most upstream side of the flow guide in a side sectional view including the rotation axis of the steam turbine, which is parallel to the rotation axis or predetermined with respect to the rotation axis. A first straight line portion having an inclination angle and extending linearly so that the distance from the rotation axis increases toward the downstream side of the flow guide.
A second straight line portion arranged on the downstream side of the flow guide from the first straight line portion in a side cross-sectional view including the rotation axis of the steam turbine, and the first straight line portion with respect to the rotation axis. An exhaust chamber of a steam turbine including a second straight line portion having a larger inclination angle and extending linearly so that the distance from the rotation axis increases toward the downstream side of the flow guide. The passage forming surface of the flow guide is
A third straight line portion arranged on the downstream side of the flow guide from the second straight line portion in a side cross-sectional view including the rotation axis of the steam turbine, and the second straight line portion with respect to the rotation axis. The third aspect of claim 1, further comprising a third straight line portion having a larger inclination angle and extending linearly so that the distance from the rotation axis increases toward the downstream side of the flow guide. Exhaust chamber of steam turbine. The exhaust chamber of the steam turbine according to claim 2, wherein the third straight line portion extends along a direction orthogonal to the rotation axis. The passage forming surface of the flow guide is
A fourth straight line portion extending linearly from the downstream end of the first straight line portion to the upstream end of the second straight line portion in a side sectional view including the rotation axis of the steam turbine. The 1st straight section, the 4th straight section shorter than the 2nd straight section, and
A fifth straight line portion extending linearly from the downstream end of the second straight line portion to the upstream end of the third straight line portion in a side sectional view including the rotation axis of the steam turbine. The exhaust chamber of the steam turbine according to claim 2 or 3, further comprising a two straight section and a fifth straight section shorter than the third straight section. The exhaust chamber of the steam turbine according to claim 4, wherein the lengths of the fourth straight line portion and the fifth straight line portion in a side cross-sectional view including the rotation axis of the steam turbine are 20 mm or more and 70 mm or less. The ratio of the length (S) of the third straight line portion in the radial direction of the bearing cone to the distance (H) from the base end portion of the third straight line portion in the radial direction to the inner peripheral surface of the casing (H). The exhaust chamber of the steam turbine according to any one of claims 2 to 5, wherein the S / H) is 0.2 or more and 0.5 or less. The exhaust chamber of the steam turbine according to claim 6, wherein the flow guide is formed so that the length (S) of the third straight line portion along the radial direction is non-uniformly formed in the circumferential direction of the rotation axis. In the flow guide, the length (S) of the third straight line portion along the radial direction is 90 to 90 ° in the range of −90 to 90 °, with 0 ° vertically above in the direction of the rotation axis of the steam turbine. The exhaust chamber of the steam turbine according to claim 7, which is formed longer than the range of 270 °. In the flow guide, the peak of the length (S) of the third straight line portion along the radial direction is 0 ° vertically above in the circumferential direction of the rotation axis, and the moving blade is in the range of 0 to 90 °. The exhaust chamber of the steam turbine according to claim 7 or 8, which is configured to exist on the downstream side in the rotational direction of the above. According to any one of claims 4 to 9, the inclination angle of the second straight line portion with respect to the fourth straight line portion is 10 ° or more and 20 ° or less in a side sectional view including the rotation axis of the steam turbine. Exhaust chamber of the described steam turbine. According to any one of claims 4 to 10, the inclination angle of the fifth straight line portion with respect to the second straight line portion is 10 ° or more and 20 ° or less in a side sectional view including the rotation axis of the steam turbine. Exhaust chamber of the described steam turbine. Claim 2 in which the inclination angle of the second straight line portion with respect to the first straight line portion is equal to or less than the inclination angle of the third straight line portion with respect to the second straight line portion in a side sectional view including the rotation axis of the steam turbine. The exhaust chamber of the steam turbine according to any one of 1 to 11.

Images