Steam turbine exhaust chamber and steam turbine

Abstract

A steam turbine exhaust chamber is used to guide the steam that has passed through the moving blades of the last stage of the steam turbine to the outside of the steam turbine. It includes a housing, an outer bearing ring, and a flow guide member. The inner surface of the housing includes an inner circumferential surface that extends along the axial direction of the rotor on the outer circumferential side of the flow guide member, and a side wall surface that connects the inner circumferential surface and the outer bearing ring. On the side wall surface, above the horizontal plane containing the rotation axis of the rotor, a first protrusion that protrudes outward in the radial direction is formed along the circumferential direction. At least a part of the first protrusion in the circumferential direction is located at a position radially outside the rotor relative to the downstream end of the inner circumferential surface of the flow guide member.

Description

Technical Field

[0001] The present invention relates to a steam turbine exhaust chamber and a steam turbine.

[0002] This application claims priority based on Japanese Patent Application No. 2020-137367 filed with the Japan Patent Office on August 17, 2020, and incorporates its content herein. Background Art

[0003] In the exhaust flow path of a steam turbine exhaust chamber, when the steam flow counterflows along the bearing outer ring in the diffusion flow path formed between the bearing outer ring and the guide member, the effective flow path area of the diffusion flow path (the flow path area where the steam flows in the diffusion flow path without counterflowing toward the rotor side but toward the outlet direction) decreases, and the pressure loss increases, resulting in a reduction in the performance of the steam turbine exhaust chamber.

[0004] In Patent Document 1, it is described that a structure (guide plate) protruding radially inward from the wall surface of the steam turbine exhaust chamber is provided to suppress the counterflow of the steam flow along the bearing outer ring.

[0005] Prior Art Documents

[0006] Patent Document 1: Specification of U.S. Patent No. 6419448 Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] As a result of in-depth research by the inventors of the present application, it has been found that the counterflow of the steam flow along the bearing outer ring in the diffusion flow path between the bearing outer ring and the guide member is the main cause of the generation of longitudinal vortices flowing down from the upper part of the steam turbine exhaust chamber. Therefore, in order to improve the performance of the exhaust chamber, it is considered important to suppress the intrusion of the longitudinal vortices into the diffusion flow path.

[0009] In the structure for suppressing counterflow described in Patent Document 1, it is not possible to effectively suppress the intrusion of the above-mentioned longitudinal vortices into the diffusion flow path, and the effect of suppressing the increase in the pressure loss in the diffusion flow path is limited.

[0010] In view of the above circumstances, an object of the present invention is to provide a steam turbine exhaust chamber and a steam turbine capable of suppressing an increase in the pressure loss in the diffusion flow path between the bearing outer ring and the guide member.

[0011] Technical Means for Solving the Problems

[0012] In order to achieve the above object, a steam turbine exhaust chamber according to at least one embodiment of the present invention is configured to guide the steam that has passed through the last-stage moving blade of the steam turbine to the outside of the steam turbine.

[0013] The steam turbine exhaust chamber includes:

[0014] Housing;

[0015] An outer race of a bearing, disposed circumferentially within the above-described housing along the rotor of the steam turbine; and

[0016] A flow deflector, disposed circumferentially within the above-described housing on the outer circumferential side of the above-described outer race of the bearing, and a diffuser flow path is formed between the above-described flow deflector and the above-described outer race of the bearing,

[0017] The inner surface of the above-described housing includes: an inner circumferential surface, extending axially along the outer circumferential side of the above-described flow deflector; and side wall surfaces, connecting the above-described inner circumferential surface and the above-described outer race of the bearing,

[0018] On the above-described side wall surfaces, above a horizontal plane including the rotational axis of the above-described rotor, a first protrusion protruding outward in the radial direction of the above-described rotor is formed along the above-described circumferential direction,

[0019] At least a part of the above-described first protrusion in the above-described circumferential direction is located at a position radially outside the downstream end of the inner circumferential surface of the above-described flow deflector.

[0020] Advantages of the Invention

[0021] According to the present invention, there is provided a steam turbine exhaust chamber and a steam turbine capable of suppressing an increase in pressure loss in a diffuser flow path between an outer race of a bearing and a flow deflector. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a schematic cross-sectional view taken along the axial direction of a steam turbine 2 according to an embodiment.

[0023] Figure 2 is a view for explaining the effects of the protrusion 26 and the like.

[0024] Figure 3 is a view showing an example of the relationship between the position θ in the circumferential direction and the length L of the protrusion 26 (an example of the circumferential distribution of the length L of the protrusion 26).

[0025] Figure 4 is a view for explaining the definition of the position θ in the circumferential direction.

[0026] Figure 5 is a view for explaining the distances R, r, and the flow path width W.

[0027] Figure 6 is a view showing an example of the relationship between the position θ in the circumferential direction and the distance r between the base end 26a of the protrusion 26 and the rotational axis C (an example of the circumferential distribution of the distance r).

[0028] Figure 7It is a diagram schematically showing an example of the arrangement of a plurality of protrusions 26 (26A to 26D).

[0029] Figure 8 It is a diagram schematically showing an example of the arrangement of a plurality of protrusions 26 (26E to 26F).

[0030] Figure 9 It is a schematic diagram showing a cross-section along the axial direction of the exhaust chamber 8 according to another embodiment, taken along the axis of the steam turbine 2.

[0031] Figure 10 It is for explaining Figure 9 the operation and effect of the structure shown

[0032] Figure 11 It is a schematic diagram showing a cross-section along the axial direction of the steam turbine 2 according to another embodiment.

[0033] Figure 12 It is a diagram showing another example of the shape of the protrusion 26.

[0034] Figure 13 It is a diagram showing another example of the shape of the protrusion 26. Detailed Embodiments

[0035] Hereinafter, several embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the constituent parts described as embodiments or shown in the drawings are not intended to limit the scope of the invention thereto, but are merely illustrative examples.

[0036] For example, expressions indicating relative or absolute arrangements such as "in a certain direction", "along a certain direction", "parallel", "orthogonal", "center", "concentric", or "coaxial" not only strictly represent such arrangements, but also represent a state of relative displacement with a tolerance or an angle or distance to the extent that the same function can be obtained.

[0037] For example, expressions indicating the same state of things such as "identical", "the same", "homogeneous" not only represent a strictly identical state, but also represent a state with a tolerance or a difference to the extent that the same function can be obtained.

[0038] For example, expressions indicating shapes such as a quadrilateral shape or a cylindrical shape not only represent a quadrilateral shape or a cylindrical shape in a strictly geometric sense, but also represent a shape including concavo-convex portions or chamfered portions within the range where the same effect can be obtained.

[0039] On the other hand, expressions such as "comprising", "equipped with", "provided with", "including", "having" a constituent element are not exclusive expressions excluding the existence of other constituent elements.

[0040] Figure 1 is a schematic cross-sectional view along the axis of a steam turbine 2 according to an embodiment. The illustrated steam turbine 2 is an axial-flow turbine. The steam turbine 2 includes: a rotor 4 (turbine rotor); and an exhaust chamber 8 (steam turbine exhaust chamber) for guiding the steam that has passed through the last-stage moving blade 6 (turbine moving blade) of the rotor 4 to the outside of the steam turbine 2.

[0041] The steam that has passed through the last-stage moving blade 6 flows into the exhaust chamber 8 from the exhaust chamber inlet 7, passes through the inside of the exhaust chamber 8, and is discharged to the outside of the steam turbine 2 from the exhaust chamber outlet 9 provided on the lower side of the exhaust chamber 8. A condenser 27 is provided below the exhaust chamber 8, and the steam that has done work on the moving blade 6 in the steam turbine 2 flows into the condenser 27 from the exhaust chamber 8 via the exhaust chamber outlet 9.

[0042] Hereinafter, the axial direction of the rotor 4 will be simply referred to as the "axial direction", the circumferential direction of the rotor 4 will be simply referred to as the "circumferential direction", and the radial direction of the rotor 4 will be simply referred to as the "radial direction". In addition, the upstream and downstream in the flow direction of the steam will be simply referred to as the "upstream" and the "downstream", respectively.

[0043] The exhaust chamber 8 includes: a housing 10, an outer bearing ring 12, and a guide member 14.

[0044] The housing 10 is configured to house a part of the rotor 4, and the inner surface 16 of the housing 10 includes an inner circumferential surface 18, a side wall surface 20, and a protrusion 26 (structural body).

[0045] The inner circumferential surface 18 extends along the axial direction and the circumferential direction on the outer peripheral side of the guide member 14 at a position above the horizontal plane including the rotation axis C of the rotor 4 (i.e., in the upper half 8u of the exhaust chamber 8). In addition, the cross-sectional shape orthogonal to the axial direction of the inner circumferential surface 18 is configured to be substantially semicircular at a position above the horizontal plane including the rotation axis C.

[0046] The side wall surface 20 includes a side wall surface 20 that extends along the radial direction so as to connect the inner circumferential surface 18 and the downstream end 12a of the outer bearing ring 12. In the illustrated exemplary embodiment, the side wall surface 20 is formed along a plane orthogonal to the axial direction.

[0047] The outer bearing ring 12 surrounds a bearing 13 that rotatably supports the rotor 4. The outer bearing ring 12 is formed in a ring shape along the circumferential direction within the housing 10. The inner diameter and the outer diameter of the outer bearing ring 12 increase as they approach the downstream side in the axial direction.

[0048] The flow guide member 14 is formed on the outer peripheral side of the outer ring 12 of the bearing along the circumferential direction within the housing 10. The flow guide member 14 forms an annular diffuser flow path 22 between it and the outer ring 12 of the bearing. The inner diameter and the outer diameter of the flow guide member 14 each expand as they approach the downstream side in the axial direction. In the illustrated manner, at the downstream end 28a of the flow guide member 14 of the steam flow in the axial direction, a straightening plate 15 that extends radially outward from the downstream end 28a is connected, and the straightening plate 15 is formed along a plane orthogonal to the axial direction.

[0049] In addition, inside the exhaust chamber 8, on the opposite side of the diffuser flow path 22 across the flow guide member 14, an outer peripheral side space 24 is formed. The outer peripheral side space 24 is located on the outer peripheral side of the flow guide member 14.

[0050] The diffuser flow path 22 has a shape in which the flow path cross-sectional area gradually expands as it approaches the downstream side in the axial direction. When the high-speed steam flow that has passed through the last-stage moving blade 6 flows into the diffuser flow path 22, the steam flow decelerates, and its kinetic energy is converted into pressure (static pressure recovery).

[0051] The protrusion 26 is provided so as to protrude radially outward from the side wall surface 20 above the horizontal plane including the rotation axis C (i.e., in the upper half 8u of the exhaust chamber 8). The protrusion 26 protrudes in a manner that approaches the outside in the radial direction as it moves away from the side wall surface 20. The protrusion 26 is not provided below the horizontal plane including the rotation axis C. The protrusion 26 is formed along the circumferential direction, and within at least a part of the circumferential direction, it is located at a position radially outside the downstream end 28a of the inner circumferential surface 28 of the flow guide member 14. In several embodiments, it is also possible that the entire protrusion 26 is located at a position radially outside the downstream end 28a of the inner circumferential surface 28 of the flow guide member 14.

[0052] According to the above structure, as Figure 2 shown, since the longitudinal vortex Fv flowing down from the upper part (near the inner circumferential surface 18) of the exhaust chamber 8 is blocked by the protrusion 26, it is possible to suppress the intrusion of this longitudinal vortex into the diffuser flow path 22 between the flow guide member 14 and the outer ring 12 of the bearing. Therefore, it is possible to suppress a decrease in the performance of the exhaust chamber due to a reduction in the effective flow path area of the diffuser flow path 22 (the flow path area in the flow path area of the diffuser flow path 22 where the steam flows radially outward).

[0053] In addition, within at least a part of the circumferential direction, the protrusion 26 is located at a position radially outside the downstream end 28a of the inner circumferential surface 28 of the flow guide member 14. Therefore, it is possible to suppress the obstruction of the steam flow in the diffuser flow path 22 by the protrusion 26 itself, and it is possible to suppress an increase in the pressure loss in the diffuser flow path 22.

[0054] Figure 3This is a diagram showing an example of the relationship between the circumferential position θ and the length L of the protrusion 26 (an example of the circumferential distribution of the length L of the protrusion 26). Additionally, as Figure 2 shown, the length L of the protrusion 26 refers to the length of the protrusion 26 from the base end 26a to the front end 26b. Additionally, in this specification, as Figure 4 shown, regarding the circumferential position θ, the direction represented by the horizontal line H orthogonal to the rotation axis C is defined as 0 degrees and 180 degrees, and the position vertically above the rotation axis C is defined as 90 degrees. Each structure of the exhaust chamber 8 has a symmetric shape centered on the vertical plane containing the rotation axis C, and either of the two directions represented by the horizontal line orthogonal to the rotation axis C can be set as 0 degrees.

[0055] In several embodiments, for example, as Figure 3 shown, the length L of the protrusion 26 can also vary depending on the circumferential position. In the example Figure 3 shown, the length L of the protrusion 26 decreases as it approaches the upper side along the circumferential direction within at least a part of the circumferential range. In the example Figure 3 shown, within the range from 0 degrees to 180 degrees in the circumferential direction, as it approaches the 90 - degree position along the circumferential direction, the length L of the protrusion 26 smoothly decreases.

[0056] The inner circumferential surface 18 of the housing 10 is above the horizontal plane containing the rotation axis C of the rotor 4, and the cross - sectional shape orthogonal to the axial direction is configured to be substantially semi - circular. Strictly speaking, the distance R between the inner circumferential surface 18 and the rotation axis C (refer to Figure 5 ) becomes smaller as it approaches the 90 - degree position in the circumferential direction. Additionally, the distance between the inner circumferential surface 18 and the downstream end 28a becomes smaller as it approaches the 90 - degree position in the circumferential direction. Therefore, if the length L of the protrusion 26 is the same in the circumferential direction, in the upper part of the exhaust chamber 8 (near the 90 - degree position in the circumferential direction), the flow path width W (refer to Figure 5 ) between the inner circumferential surface 18 and the front end 16b of the protrusion 26 becomes smaller compared to other positions in the circumferential direction, and there is a case where the above - mentioned effect of providing the protrusion 26 is limited.

[0057] Therefore, as described above, by making the length L of the protrusion 26 decrease as it approaches the upper side along the circumferential direction within at least a part of the circumferential range, it is possible to suppress the non - uniformity of the flow path width W in the circumferential direction between the inner circumferential surface 18 and the front end 26b of the protrusion 26, and effectively induce the above - mentioned longitudinal vortex between the protrusion 26 and the side wall surface 20. As a result, it is possible to effectively suppress the reduction in the exhaust chamber performance caused by the reduction of the effective flow path area of the diffusion flow path 22.

[0058] In several embodiments, for example, as Figure 6As shown, the distance r between the base end 26a of the protrusion 26 and the rotation axis C may also vary depending on the circumferential position θ. In Figure 6 the example shown, the distance r between the base end 26a of the protrusion 26 and the rotation axis C decreases as it approaches upward in the circumferential direction within at least a part of the circumferential range. In Figure 6 the example shown, within the range of 0 degrees to 180 degrees in the circumferential direction, as it approaches the position of 90 degrees in the circumferential direction, the distance r smoothly decreases.

[0059] Thereby, it is possible to suppress the flow path width W between the inner peripheral surface 18 and the front end 26b of the protrusion 26 from becoming uneven in the circumferential direction, and it is possible to effectively induce the above-described longitudinal eddy current between the protrusion 26 and the side wall surface 20. Thereby, it is possible to effectively suppress a decrease in the performance of the exhaust chamber caused by a reduction in the effective flow path area of the diffusion flow path 22.

[0060] In several embodiments, for example, as Figure 7 shown, a plurality of protrusions 26 (26A to 26D) may also be provided on the side wall surface 20 of the housing 10.

[0061] In Figure 7 the example shown, on the side wall surface 20, above the horizontal plane (the horizontal plane including the 0-degree position and the 180-degree position) including the rotation axis C of the rotor 4, a plurality of protrusions 26 (26A to 26D) are provided. The plurality of protrusions 26 (26A to 26D) are composed of four protrusions 26A to 26D arranged at intervals in the circumferential direction. The plurality of protrusions 26 (26A to 26D) are provided only in a part of the range (local range) where the longitudinal eddy current is dominant in the range from 0 degrees to 180 degrees in the circumferential direction. Among the plurality of protrusions 26 (26A to 26D), the protrusions 26B and 26C are arranged at positions higher than the protrusions 26A and 26D. The protrusion 26B is arranged between the protrusion 26A and the 90-degree position, and the protrusion 26C is arranged between the protrusion 26D and the 90-degree position.

[0062] The plurality of protrusions 26 (26A to 26D) are respectively formed along the circumferential direction, as Figure 1 illustrated, and protrude outward in the radial direction. The plurality of protrusions 26 (26A to 26D) respectively protrude in such a manner that they approach the outside in the radial direction as they move away from the side wall surface 20. In addition, as Figure 1 illustrated, the plurality of protrusions 26 (26A to 26D) are respectively located at positions outside the radial direction of the downstream end 28a of the inner peripheral surface 28 of the guide member 14 within at least a part of the circumferential range. In several embodiments, it may also be that the entire plurality of protrusions 26 (26A to 26D) are located at positions outside the radial direction of the downstream end 28a of the inner peripheral surface 28 of the guide member 14.

[0063] As Figure 7 illustrated, by providing the protrusions 26 (26A to 26D) in a range where only the longitudinal eddy current is dominant in the range from 0 degrees to 180 degrees, compared with the case where the protrusions 26 are provided throughout the range from 0 degrees to 180 degrees, an increase in the pressure loss added by the protrusions 26 can be suppressed, and the intrusion of the longitudinal eddy current into the diffusion flow path 22 can be suppressed, thereby improving the exhaust chamber performance. In addition, compared with the case where the protrusions 26 are provided throughout the range from 0 degrees to 180 degrees, since the protrusions 26 are divided into a plurality of protrusions (26A to 26D), each protrusion 26 can be easily fixed to the side wall surface 20 by welding or the like.

[0064] In Figure 7 the example shown, at least a part of the plurality of protrusions 26 (26A to 26D) is provided in the range from 30 degrees to 150 degrees in the circumferential direction. In addition, two of the four protrusions 26 (26B, 26C) are provided in the range from 30 degrees to 150 degrees. Thus, by providing at least a part of the protrusions 26 in the range from 30 degrees to 150 degrees, the intrusion of the longitudinal eddy current into the diffusion flow path 22 can be effectively suppressed, thereby improving the exhaust chamber performance.

[0065] In several embodiments, it is also possible to make Figure 7 the lengths L (refer to Figure 2 ) of the plurality of protrusions 26 (26A to 26D) from the base end 26a to the front end 26b different from each other. For example, it is also possible to make the lengths L of the protrusions 26B and 26C arranged at positions higher than the protrusions 26A and 26D longer than the lengths L of the protrusions 26A and 26D.

[0066] In the upper part of the exhaust chamber 8 (near the above-mentioned 90-degree position), the influence of the longitudinal eddy current is greater than that at the horizontal positions (near the above-mentioned 0 degrees and 180 degrees). Therefore, as described above, by making the lengths L of the protrusions 26B and 26C arranged at relatively high positions longer than the lengths L of the protrusions 26A and 26D arranged at relatively low positions, the intrusion of the longitudinal eddy current into the diffusion flow path 22 can be effectively suppressed, thereby improving the exhaust chamber performance.

[0067] In several embodiments, for example, as Figure 8 illustrated, a plurality of protrusions 26 (26E, 26F) may also be provided on the side wall surface 20 of the housing 10.

[0068] In Figure 8In the example shown, on the side wall surface 20, above the horizontal plane (the horizontal plane including the 0-degree position and the 180-degree position) containing the rotation axis C of the rotor 4, a plurality of protrusions 26 (26E, 26F) are provided. The plurality of protrusions 26 (26E, 26F) are composed of two protrusions 26E and 26F arranged at intervals in the circumferential direction. In the example shown, the plurality of protrusions 26 (26E, 26F) are composed of the protrusion 26E and the protrusion 26F provided on the opposite side of the protrusion 26E with respect to the vertical plane including the rotation axis C. The protrusion 26E is formed in the range from 0 degrees to approximately 90 degrees in the circumferential direction, and the protrusion 26F is formed in the range from approximately 90 degrees to 180 degrees in the circumferential direction.

[0069] The plurality of protrusions 26 (26E, 26F) are respectively formed along the circumferential direction, as Figure 1 illustrated, protruding toward the outer side in the radial direction. The plurality of protrusions 26 (26E, 26F) respectively protrude in such a manner that they approach the outer side in the radial direction as they move away from the side wall surface 20. In addition, as Figure 1 illustrated, the plurality of protrusions 26 (26E, 26F) are respectively located at positions radially outside the downstream end 28a of the inner circumferential surface 28 of the flow guide member 14 within at least a part of the circumferential direction. In several embodiments, it is also possible that the entire plurality of protrusions 26 (26E, 26F) are located at positions radially outside the downstream end 28a of the inner circumferential surface 28 of the flow guide member 14.

[0070] In Figure 8 the example shown, recesses 30 that are recessed toward the inner side in the radial direction are formed at the upper ends 26u of the respective protrusions 26 (26E, 26F). The recesses 30 of the respective protrusions 26 (26E, 26F) are formed at the circumferential ends of the protrusions 26 (26E, 26F), and the recess 30 of the protrusion 26E and the recess 30 of the protrusion 26F are formed at positions facing each other.

[0071] At the upper ends 26u of the respective protrusions 26 (26E, 26F), the flow path width W (refer to Figure 5 ) between the inner circumferential surface 18 and the front end 26b of the protrusion 26 tends to become narrow. Therefore, by providing the recesses 30 as described above, the flow path width W can be ensured, and longitudinal vortices can be induced between the protrusion 26 and the side wall surface 20. As a result, the intrusion of longitudinal vortices into the diffusion flow path 22 can be effectively suppressed, and the exhaust chamber performance can be improved. In addition, since it is divided into a plurality of protrusions 26 (26E, 26F), each protrusion 26 can be easily fixed to the side wall surface 20 by welding or the like.

[0072] In several embodiments, for example, as Figure 9As shown, a cavity 32 that is recessed inward in the radial direction may also be formed on the outer peripheral surface 33 of the bearing outer ring 12. In Figure 9 In the manner shown, the cavity 32 is formed over the entire circumferential range at the position of the downstream end 12a of the bearing outer ring 12 and is formed in a ring shape. However, in other embodiments, the cavity 32 may also be provided only in a part of the circumferential range, for example, may be provided only above the horizontal plane including the rotation axis C (the upper half of the bearing outer ring 12).

[0073] According to Figure 9 the structure shown, as Figure 10 shown, a part Fs of the steam flow that collides with the side wall surface 20 is guided to the cavity 32. Therefore, the backflow of the steam flow along the bearing outer ring 12 can be suppressed, the flow caused by two-dimensional separation during low Mach operation can be suppressed, and the performance on the low Mach side can be improved. In addition, by blocking the longitudinal vortex Fv by the protrusion 26, the three-dimensional separation during high Mach operation can also be suppressed. Therefore, high robustness related to performance can be achieved with respect to the operating conditions.

[0074] In several embodiments, for example, as Figure 11 shown, the axial width d1 of the open end 32a of the cavity 32 may also be smaller than the axial width d2 of the bottom surface 32b of the cavity 32. The cavity 32 is formed over the entire circumferential range and is formed in a ring shape.

[0075] In addition, in Figure 11 the manner shown, the cavity 32 includes in the axial cross-section: a radial cavity portion 34 that extends inward in the radial direction from the open end 32a of the cavity 32; and an inclined cavity portion 36 that is connected to the inner circumferential end 34a of the radial cavity portion 34. The inclined cavity portion 36 extends in an inclined direction inclined with respect to the axial direction in such a manner that it approaches the inner side in the radial direction as it approaches the moving blade 6 side from the inner circumferential end 34a of the radial cavity portion 34. In addition, the position P1 on the bottom surface 32b of the cavity 32 that is closest to the moving blade 6 is located on the inner side in the radial direction compared to the position P2 on the bottom surface 32b that is farthest from the moving blade 6.

[0076] According to Figure 11 the structure shown, since the axial width d1 of the open end 32a of the cavity 32 is smaller than the axial width d2 of the bottom surface 32b of the cavity 32, the steam flowing into the cavity 32 can be prevented from flowing out of the cavity 32 again, and the effect of suppressing separation can be improved.

[0077] In addition, since the position P1 on the bottom surface 32b of the cavity 32 that is closest to the moving blade 6 is located on the inner side in the radial direction compared to the position P2 on the bottom surface 32b that is farthest from the moving blade 6, the steam flowing into the cavity 32 can be prevented from flowing out again toward the moving blade 6 side, and the effect of suppressing separation can be improved.

[0078] The present invention is not limited to the above-described embodiments, and also includes embodiments obtained by deforming the above-described embodiments and embodiments obtained by appropriately combining these embodiments.

[0079] In several embodiments, for example, as Figure 12 shown, the front end portion 26c of the protrusion 26 may also be bent toward the side wall surface 20. In Figure 12 the structure shown, the protrusion 26 includes: an inclined portion 40 that approaches the outer side in the radial direction as it moves away from the side wall surface 20 in the axial direction; and a front end portion 26c that extends from the front end of the inclined portion 40 toward the side wall surface 20 along the axial direction.

[0080] According to this structure, as Figure 12 shown, it is possible to suppress the outflow of the longitudinal eddy current Fv between the protrusion 26 and the side wall surface 20 toward the mainstream side (diffusion flow path 22 side). As Figure 12 shown, the front end portion 26c of the protrusion 26 may be bent toward the side wall surface 20 or may be smoothly bent toward the side wall surface 20.

[0081] In several embodiments, for example, as Figure 13 shown, the front end portion 26c of the protrusion 26 may also be bent toward the deflector 14 side. In Figure 13 the structure shown, the protrusion 26 includes: an inclined portion 40 that approaches the outer side in the radial direction as it moves away from the side wall surface 20 in the axial direction; a radial portion 42 that extends from the front end side of the inclined portion 40 toward the inner circumferential surface 18 side in the radial direction; and a front end portion 26c that bends and extends from the front end side of the radial portion 42 toward the deflector 14 side in the axial direction.

[0082] According to this structure, since the front end portion 26c of the protrusion 26 is bent toward the deflector 14 side in the axial direction, the steam flow Fg flowing out from the diffusion flow path 22 collides with the protrusion 26 and is guided in a direction away from the side wall surface 20. Therefore, it is possible to suppress the steam flow Fg from flowing into the diffusion flow path 22 again. Therefore, an increase in the pressure loss in the diffusion flow path 22 can be suppressed.

[0083] The contents described in the above embodiments are grasped as follows, for example.

[0084] (1) The steam turbine exhaust chamber according to the present invention (for example, the exhaust chamber 8 described above) is used to guide the steam that has passed through the last stage moving blade (for example, the moving blade 6 described above) of the steam turbine (for example, the steam turbine 2 described above) to the outside of the steam turbine.

[0085] The steam turbine exhaust chamber includes:

[0086] a housing (for example, the housing 10 described above);

[0087] The outer ring of the bearing (such as the outer ring 12 of the bearing described above) is arranged circumferentially within the above-mentioned housing along the rotor of the steam turbine (such as the rotor 4 described above); and

[0088] The flow guide member (such as the flow guide member 14 described above) is arranged on the outer circumferential side of the outer ring of the bearing along the above-mentioned circumferential direction within the above-mentioned housing, and a diffusion flow path (such as the diffusion flow path 22 described above) is formed between the flow guide member and the outer ring of the bearing.

[0089] The inner surface of the above-mentioned housing includes: an inner circumferential surface (such as the inner circumferential surface 18 described above), which extends axially along the rotor on the outer circumferential side of the flow guide member; and a side wall surface (such as the side wall surface 20 described above), which connects the inner circumferential surface and the outer ring of the bearing.

[0090] On the above-mentioned side wall surface, at a position above the horizontal plane including the rotation axis of the above-mentioned rotor, a first protruding portion (such as the protruding portion 26 described above) protruding radially outward of the above-mentioned rotor is formed along the above-mentioned circumferential direction.

[0091] At least a part of the above-mentioned first protruding portion in the above-mentioned circumferential direction is located at a position radially outside the downstream end (such as the downstream end 28a) of the inner circumferential surface (such as the inner circumferential surface 28 described above) of the above-mentioned flow guide member.

[0092] According to the steam turbine exhaust chamber described in the above (1), since the longitudinal vortex flowing down from the upper part (near the inner circumferential surface) of the steam turbine exhaust chamber is blocked by the first protruding portion, it is possible to suppress the intrusion of the longitudinal vortex into the diffusion flow path between the flow guide member and the outer ring of the bearing. Therefore, it is possible to suppress the reduction of the exhaust chamber performance due to the reduction of the effective flow path area of the diffusion flow path.

[0093] In addition, in at least a part of the range in the circumferential direction, the first protruding portion is located at a position radially outside the downstream end of the inner circumferential surface of the flow guide member, so it is possible to suppress the obstruction of the steam flow in the diffusion flow path by the first protruding portion itself, and it is possible to suppress the increase of the pressure loss in the diffusion flow path.

[0094] (2) In several embodiments, in the steam turbine exhaust chamber described in the above (1),

[0095] The front end portion (such as the front end portion 26c described above) of the above-mentioned first protruding portion is bent toward the side wall surface in the above-mentioned axial direction.

[0096] According to the steam turbine exhaust chamber described in the above (2), it is possible to suppress the outflow of the longitudinal vortex that intrudes between the first protruding portion and the side wall surface to the mainstream side.

[0097] (3) In several embodiments, in the steam turbine exhaust chamber described in the above (1),

[0098] The front end portion of the first protrusion (e.g., the front end portion 26c described above) bends toward the diffuser side in the above-mentioned axial direction.

[0099] In the steam turbine exhaust chamber according to the above (3), since the front end portion of the first protrusion bends toward the diffuser side in the axial direction, the steam flow flowing out from the diffuser flow path collides with the protrusion and is guided in a direction away from the side wall surface. Therefore, the re-inflow of the steam flow into the diffuser flow path can be suppressed. Thus, an increase in the pressure loss in the diffuser flow path can be suppressed.

[0100] (4) In several embodiments, in the steam turbine exhaust chamber according to any one of the above (1) to (3),

[0101] The length (e.g., the length L described above) of the first protrusion from the base end (e.g., the base end 26a described above) to the front end (e.g., the front end 26b described above) varies depending on the position in the above-mentioned circumferential direction.

[0102] In the steam turbine exhaust chamber according to the above (4), by appropriately setting the length of the first protrusion according to the position in the circumferential direction, it is possible to suppress the non-uniformity of the flow path width in the circumferential direction between the inner circumferential surface and the front end of the first protrusion, and to effectively guide the above-mentioned longitudinal vortex between the first protrusion and the side wall surface. Thereby, a decrease in the performance of the exhaust chamber due to the reduction of the effective flow path area of the diffuser flow path can be effectively suppressed.

[0103] (5) In several embodiments, in the steam turbine exhaust chamber according to the above (4),

[0104] The length of the first protrusion decreases as it approaches the upper side along the circumferential direction in at least a part of the range in the circumferential direction.

[0105] In the steam turbine exhaust chamber according to the above (5), it is possible to suppress the non-uniformity of the flow path width in the circumferential direction between the inner circumferential surface and the front end of the first protrusion, and to effectively guide the above-mentioned longitudinal vortex between the first protrusion and the side wall surface. Thereby, a decrease in the performance of the exhaust chamber due to the reduction of the effective flow path area of the diffuser flow path can be effectively suppressed.

[0106] (6) In several embodiments, in the steam turbine exhaust chamber according to any one of the above (1) to (5),

[0107] The distance (e.g., the distance r described above) between the base end of the first protrusion and the rotation axis varies depending on the position in the above-mentioned circumferential direction.

[0108] The steam turbine exhaust chamber described in (6) above can suppress the non-uniformity in the circumferential direction of the flow path width between the inner circumferential surface and the front end of the first protrusion by appropriately setting the distance between the base end of the first protrusion and the rotation axis according to the position in the circumferential direction, and can effectively guide the longitudinal vortex between the protrusion and the side wall surface. Thereby, it is possible to suppress the reduction in the performance of the exhaust chamber due to the reduction in the effective flow path area of the diffusion flow path.

[0109] (7) In several embodiments, in the steam turbine exhaust chamber described in (6) above,

[0110] The distance between the base end of the first protrusion and the rotation axis decreases as it approaches upward in the circumferential direction in at least a part of the range in the circumferential direction.

[0111] According to the steam turbine exhaust chamber described in (7) above, it is possible to suppress the non-uniformity in the circumferential direction of the flow path width between the inner circumferential surface and the front end of the first protrusion, and can effectively guide the longitudinal vortex between the protrusion and the side wall surface. Thereby, it is possible to effectively suppress the reduction in the performance of the exhaust chamber due to the reduction in the effective flow path area of the diffusion flow path.

[0112] (8) In several embodiments, in the steam turbine exhaust chamber described in any one of (1) to (7) above,

[0113] Regarding the position in the circumferential direction, when one side in the direction represented by the horizontal line orthogonal to the rotation axis is defined as 0 degrees and the position vertically above the rotation axis is defined as 90 degrees,

[0114] The first protrusion is provided only in a part of the range from 0 degrees to 180 degrees in the circumferential direction.

[0115] According to the steam turbine exhaust chamber described in (8) above, by providing the first protrusion in a part of the range from 0 degrees to 180 degrees where the longitudinal vortex is dominant, compared with the case where the protrusion is provided in the entire range from 0 degrees to 180 degrees, it is possible to suppress the increase in the pressure loss added by the first protrusion and suppress the intrusion of the longitudinal vortex into the diffusion flow path, thereby improving the performance of the exhaust chamber.

[0116] (9) In several embodiments, in the steam turbine exhaust chamber described in (8) above,

[0117] At least a part of the first protrusion is provided in the range from 30 degrees to 150 degrees in the circumferential direction.

[0118] According to the steam turbine exhaust chamber described in (9) above, it is possible to effectively suppress the intrusion of the longitudinal vortex into the diffusion flow path and improve the performance of the exhaust chamber.

[0119] (10) In several embodiments, in the steam turbine exhaust chamber according to any one of the above (1) to (9),

[0120] On the side wall surface, at a position above the horizontal plane including the rotation axis of the rotor and radially outside the rotor with respect to the downstream end of the inner peripheral surface of the deflector, a plurality of protrusions (such as the above-mentioned protrusions 26A to 26D or the above-mentioned protrusions 26E and 26F) protruding radially outward are provided.

[0121] The plurality of protrusions are arranged at intervals in the circumferential direction.

[0122] The plurality of protrusions include the first protrusion.

[0123] According to the steam turbine exhaust chamber described in the above (10), since the plurality of protrusions are arranged at intervals in the circumferential direction, it is easier to fix each protrusion to the side wall surface by welding or the like compared to the case where each protrusion is formed continuously in the circumferential direction. In addition, by providing each protrusion at a position where longitudinal vortices are dominant, an increase in pressure loss added by each protrusion can be suppressed, and intrusion of longitudinal vortices into the diffusion flow path can be suppressed, thereby improving the performance of the exhaust chamber.

[0124] (11) In several embodiments, in the steam turbine exhaust chamber described in the above (10),

[0125] The plurality of protrusions include a second protrusion (such as the above-mentioned protrusion 26B or 26C) arranged at a position higher than the first protrusion (such as the above-mentioned protrusion 26A or 26D).

[0126] The length from the base end to the front end of the second protrusion (such as the above-mentioned length L) is longer than the length from the base end to the front end of the first protrusion (such as the above-mentioned length L).

[0127] According to the steam turbine exhaust chamber described in the above (11), as described above, by making the length of the protrusion arranged at a relatively high position longer than the length of the protrusion arranged at a relatively low position, intrusion of longitudinal vortices into the diffusion flow path can be effectively suppressed, thereby improving the performance of the exhaust chamber.

[0128] (12) In several embodiments, in the steam turbine exhaust chamber described in the above (10),

[0129] A concave portion (such as the above-mentioned concave portion 30) is formed at the upper end of the first protrusion.

[0130] In the steam turbine exhaust chamber described in the above (12), at the upper end of the first protrusion, the flow path width between the inner peripheral surface and the front end of the first protrusion is liable to become narrow. Therefore, as described above, by providing the recess, the flow path width can be ensured and a longitudinal eddy can be guided between the first protrusion and the side wall surface. Thereby, the intrusion of the longitudinal eddy into the diffusion flow path can be effectively suppressed and the performance of the exhaust chamber can be improved.

[0131] (13) In several embodiments, in the steam turbine exhaust chamber described in the above (12),

[0132] The plurality of the above protrusions includes a second protrusion (for example, the protrusion 26F described above), and the second protrusion is provided on the side opposite to the first protrusion (for example, the protrusion 26E described above) with respect to the vertical plane including the above rotation axis.

[0133] A recess (for example, the recess 30 described above) is formed at the upper end of the second protrusion.

[0134] In the steam turbine exhaust chamber described in the above (13), at the upper ends of the first protrusion and the second protrusion, the flow path width between the inner peripheral surface and the front end of each protrusion is liable to become narrow. Therefore, as described above, by providing the recess, the flow path width can be ensured and a longitudinal eddy can be guided between the protrusion and the side wall surface. Thereby, the intrusion of the longitudinal eddy into the diffusion flow path can be effectively suppressed and the performance of the exhaust chamber can be improved. In addition, since the first protrusion and the second protrusion are provided on opposite sides with respect to the vertical plane including the rotation axis, each protrusion can be easily fixed to the side wall surface by welding or the like.

[0135] (14) In several embodiments, in the steam turbine exhaust chamber described in any one of the above (1) to (13),

[0136] A cavity (for example, the cavity 32 described above) is formed on the outer peripheral surface of the above bearing outer ring (for example, the outer peripheral surface 33 described above).

[0137] In the steam turbine exhaust chamber described in the above (14), since a part of the steam flow colliding with the side wall surface is guided to the cavity, the backflow of the steam flow along the bearing outer ring can be suppressed, the flow of the two-dimensional separation factor during low Mach operation can be suppressed, and the performance on the low Mach side can be improved. In addition, the three-dimensional separation during high Mach operation caused by the provision of the protrusion can also be suppressed, so that high robustness related to performance with respect to the operating conditions can be achieved.

[0138] (15) In several embodiments, in the steam turbine exhaust chamber described in the above (14),

[0139] The axial width (e.g., the width d1) of the open end of the cavity (e.g., the open end 32a) is smaller than the axial width (e.g., the width d2) of the bottom surface of the cavity (e.g., the bottom surface 32b).

[0140] In the steam turbine exhaust chamber described in the above (15), since the axial width of the open end of the cavity is smaller than the axial width of the bottom surface of the cavity, it is possible to suppress the steam flowing into the cavity from flowing out of the cavity again, and the effect of suppressing peeling can be improved.

[0141] (16) In several embodiments, in the steam turbine exhaust chamber described in the above (14) or (15),

[0142] The position (e.g., the position P1) on the bottom surface of the cavity closest to the moving blade is located at a position closer to the inner side in the radial direction than the position (e.g., the position P2) on the bottom surface of the cavity farthest from the moving blade.

[0143] In the steam turbine exhaust chamber described in the above (16), since the position on the bottom surface of the cavity closest to the moving blade is located at a position closer to the inner side in the radial direction than the position on the bottom surface of the cavity farthest from the moving blade, it is possible to suppress the steam flowing into the cavity from flowing out again toward the moving blade side, and the effect of suppressing peeling can be improved.

[0144] (17) The steam turbine according to at least one embodiment of the present invention includes:

[0145] The steam turbine exhaust chamber described in any one of the above (1) to (16); and

[0146] The rotor.

[0147] In the steam turbine described in the above (17), since it includes the steam turbine exhaust chamber described in any one of the above (1) to (16), it is possible to suppress an increase in pressure loss due to a reduction in the effective flow path area of the diffusion flow path, and it is possible to suppress a decrease in the performance of the exhaust chamber.

[0148] Description of reference numerals

[0149] 2 Steam turbine

[0150] 4 Rotor

[0151] 6 Moving blade

[0152] 7 Exhaust chamber inlet

[0153] 8 Exhaust chamber (steam turbine exhaust chamber)

[0154] 9 Exhaust chamber outlet

[0155] 10 Housing

[0156] 12 Bearing outer ring

[0157] 12a Downstream end

[0158] 13 Bearing

[0159] 14 Flow guide

[0160] 15 Rectifying plate

[0161] 16 Inner surface

[0162] 18 Inner peripheral surface

[0163] 20 Side wall surface

[0164] 22 Diffusion flow path

[0165] 24 Outer peripheral side space

[0166] 26(26A, 26B, 26C, 26D, 26E, 26F) Protrusion (First protrusion, Second protrusion)

[0167] 26a Base end

[0168] 26b Front end

[0169] 26u Upper end

[0170] 27 Condenser

[0171] 28 Inner peripheral surface

[0172] 28a Downstream end

[0173] 30 Recess

[0174] 32 Cavity

[0175] 32a Open end

[0176] 32b Bottom surface

[0177] 33 Outer peripheral surface

[0178] 34 Radial cavity part

[0179] 34a Inner peripheral end

[0180] 36 Inclined cavity part

[0181] 40 Inclined part

[0182] 42 Radial part.

Claims

1. A steam turbine exhaust chamber for guiding steam that has passed through the moving blades of the last stage of a steam turbine to the outside of the steam turbine. The steam turbine exhaust chamber includes: a housing; an outer bearing ring disposed circumferentially within the housing along the rotor of the steam turbine; and a deflector disposed circumferentially within the housing on the outer peripheral side of the outer bearing ring, with a diffuser flow path formed between the deflector and the outer bearing ring, The inner surface of the housing includes: an inner peripheral surface extending axially along the rotor on the outer peripheral side of the deflector; and side wall surfaces connecting the inner peripheral surface and the outer bearing ring, on the side wall surfaces, a first protrusion protruding radially outward of the rotor is formed circumferentially above a horizontal plane including the rotational axis of the rotor, at least a part of the first protrusion in the circumferential direction is located radially outside the downstream end of the inner peripheral surface of the deflector, the front end of the first protrusion is away from the side wall surface and the inner peripheral surface, the base end of the first protrusion is located radially inside the front end of the first protrusion with respect to the rotor and is fixed to the side wall surface.

2. The steam turbine exhaust chamber according to claim 1, wherein the front end of the first protrusion is bent toward the side wall surface in the axial direction.

3. The steam turbine exhaust chamber according to claim 1, wherein the front end of the first protrusion is bent toward the deflector in the axial direction.

4. The steam turbine exhaust chamber according to any one of claims 1 to 3, wherein the length of the first protrusion from the base end to the front end varies depending on the position in the circumferential direction.

5. The steam turbine exhaust chamber according to claim 4, wherein the length of the first protrusion decreases as it approaches upward along the circumferential direction in at least a part of the circumferential range.

6. The steam turbine exhaust chamber according to any one of claims 1 to 3, wherein the distance between the base end of the first protrusion and the rotational axis varies depending on the position in the circumferential direction.

7. The steam turbine exhaust chamber according to claim 6, wherein the distance between the base end of the first protrusion and the rotational axis decreases as it approaches upward along the circumferential direction in at least a part of the circumferential range.

8. The steam turbine exhaust chamber according to any one of claims 1 to 3, wherein with respect to the position in the circumferential direction, when one side in the direction represented by a horizontal line orthogonal to the rotational axis is defined as 0 degrees and the position vertically above the rotational axis is defined as 90 degrees, the first protrusion is provided only in a part of the range from 0 degrees to 180 degrees in the circumferential direction.

9. The steam turbine exhaust chamber according to claim 8, wherein at least a part of the first protrusion is provided in the range from 30 degrees to 150 degrees in the circumferential direction.

10. The steam turbine exhaust chamber according to any one of claims 1 to 3, wherein On the side wall surface, at a position above the horizontal plane including the rotation axis of the rotor and radially outside the rotor with respect to the downstream end of the inner peripheral surface of the guide member, a plurality of protrusions protruding radially outward are provided. The plurality of protrusions are arranged at intervals in the circumferential direction. The plurality of protrusions include the first protrusion.

11. The steam turbine exhaust chamber according to claim 10, wherein the plurality of protrusions include a second protrusion arranged at a position higher than the first protrusion, and the length of the second protrusion from the base end to the front end is longer than the length of the first protrusion from the base end to the front end.

12. The steam turbine exhaust chamber according to claim 10, wherein a recess is formed at the upper end of the first protrusion.

13. The steam turbine exhaust chamber according to claim 12, wherein the plurality of protrusions include a second protrusion provided on the opposite side of the first protrusion across the vertical plane including the rotation axis, and a recess is formed at the upper end of the second protrusion.

14. The steam turbine exhaust chamber according to any one of claims 1 to 3, wherein a cavity is formed on the outer peripheral surface of the bearing outer ring.

15. The steam turbine exhaust chamber according to claim 14, wherein the width in the axial direction of the open end of the cavity is smaller than the width in the axial direction of the bottom surface of the cavity.

16. The steam turbine exhaust chamber according to claim 14, wherein the position on the bottom surface of the cavity closest to the moving blade is located radially inward of the position on the bottom surface farthest from the moving blade.

17. A steam turbine, comprising: the steam turbine exhaust chamber according to any one of claims 1 to 16; and the rotor.

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