Exhaust chamber, steam turbine provided with exhaust chamber, and method for modifying exhaust chamber

Abstract

This exhaust chamber is provided with a diffuser that forms a diffuser space, an exhaust casing that forms an exhaust space that guides steam flowing in from the diffuser space to an exhaust port, a plurality of lining members that are disposed across the exhaust space from the diffuser space and are aligned in the circumferential direction, and support columns provided for each of the plurality of lining members. The exhaust casing has a downstream-side end plate that defines an edge on the downstream side of the axial line in the exhaust space. Each of the plurality of lining members extends from a position along an inner diffuser of the diffuser to a position along the downstream-side end plate. A first end of the support column is joined to the downstream-side end plate. The second ends of the support columns are joined to the lining members.

Description

Exhaust chamber, steam turbine equipped with said exhaust chamber, and method for modifying an exhaust chamber

[0001] This application claims priority to Japanese Patent Application No. 2024-064524, filed on April 12, 2024, the contents of which are incorporated herein by reference.

[0002] Patent Document 1 discloses a steam turbine having an exhaust duct. The exhaust duct serves to guide steam flowing out of the final row of moving blades of the turbine rotor to the outside. The exhaust duct includes a diffuser and an exhaust casing.

[0003] The diffuser is annular about the axis, which is the central axis of rotation of the rotor, and defines a diffuser space that gradually extends radially outward as it extends downstream in the axial direction. The diffuser has an outer diffuser that defines the radially outer edge of the diffuser space, and an inner diffuser that defines the radially inner edge of the diffuser space. Steam flowing out of the final row of blades of the turbine rotor flows into the diffuser space.

[0004] The exhaust casing has an exhaust port that opens radially outward. The exhaust casing communicates with the diffuser space, expands in the circumferential direction about the axis, and defines an exhaust space that guides steam that has flowed in from the diffuser space to the exhaust port.

[0005] Japanese Patent Application Laid-Open No. 2006-329148

[0006] In the exhaust chamber, pressure recovery is attempted for the steam that has flowed out from the final row of moving blades. The greater this pressure recovery, the lower the pressure of the steam immediately after it has flowed out from the final row of moving blades, improving turbine efficiency. In addition, in recent years, thermal power plants have been required to operate flexibly to absorb load fluctuations. To perform such flexible operation, it is necessary to operate at the design point, that is, at a partial load other than rated operation. When operating at a partial load, steam backflow occurs in parts of the diffuser space and exhaust space, increasing steam exhaust resistance and reducing pressure recovery.

[0007] Therefore, an object of the present disclosure is to provide a technology that can reduce the exhaust resistance of steam.

[0008] An exhaust duct as one aspect of the disclosure for achieving the above-mentioned object is an exhaust duct of a steam turbine that is capable of discharging steam flowing out from a final row of moving blades of a turbine rotor that rotates around an axis to the outside, and includes: a diffuser that forms a diffuser space into which the steam flowing out from the final row of moving blades can flow, the diffuser having an annular shape about the axis and gradually expanding radially outward relative to the axis as it moves downstream of the axis; an exhaust casing that has an exhaust port that opens radially outward, communicates with the diffuser space, expands in a circumferential direction about the axis, and forms an exhaust space that directs the steam that has flowed in from the diffuser space to the exhaust port; a plurality of lining members that are arranged across from the diffuser space and are aligned in the circumferential direction; and support pillars that are provided for each of the plurality of lining members. The diffuser has an inner diffuser that has an annular cross section perpendicular to the axis and gradually widens radially outward toward the downstream side of the axis, defining a radially inner edge of the diffuser space with respect to the axis. The exhaust casing has a downstream end plate that defines the downstream edge of the exhaust space with respect to the axis. The downstream end plate widens in the circumferential direction and in a direction including a radial component with respect to the axis. The radially inner edge of the downstream end plate is connected to the downstream edge of the inner diffuser with respect to the axis. Each of the multiple lining members extends from a position along a space side surface that defines the radially inner edge of the diffuser space at the inner diffuser, gradually extending radially outward toward the downstream side of the axis, to a position along a space side surface that defines the exhaust space at the downstream end plate. The support pillar for each of the multiple lining members has a first end and a second end. The first end of the support strut is joined to the inner diffuser or the downstream end plate, and the second end of the support strut is joined to one of the lining members, and none of the lining members is joined to the inner diffuser or the downstream end plate.

[0009] A steam turbine according to one aspect of the disclosure for achieving the above object includes the exhaust chamber according to the above aspect, the turbine rotor, and a body casing that covers an outer peripheral side of the turbine rotor.

[0010] According to one aspect of the disclosure for achieving the above object, there is provided a method for modifying an exhaust duct of a steam turbine capable of directing steam flowing from a final row of moving blades of a turbine rotor rotating about an axis to the outside, the exhaust duct comprising: a diffuser forming a diffuser space into which steam flowing from the final row of moving blades of the turbine rotor rotating about the axis can flow, the diffuser having an annular shape about the axis and gradually widening radially outward relative to the axis as it extends downstream along the axis; and an exhaust casing having an exhaust port opening radially outward, communicating with the diffuser space, widening in a circumferential direction about the axis, and forming an exhaust space for directing the steam flowing from the diffuser space to the exhaust port. The diffuser has an inner diffuser having an annular cross section perpendicular to the axis, gradually widening radially outward relative to the axis as it extends downstream along the axis, and defining a radially inner edge of the diffuser space. The exhaust casing has a downstream end plate that defines an axially downstream edge of the exhaust space, the downstream end plate extending in the circumferential direction and in a direction including a radial component relative to the axis, and the radially inner edge of the downstream end plate is connected to the axially downstream edge of the inner diffuser. This exhaust chamber modification method includes a preparation step of preparing a plurality of lining members and support columns for each of the plurality of lining members, a first joining step of joining first ends of the support columns to the inner diffuser or the downstream end plate so that the support columns for each of the plurality of lining members are spaced apart in the circumferential direction, and a second joining step of joining each of the plurality of lining members to the second end of one of the support columns so that the plurality of lining members are aligned in the circumferential direction and all of the plurality of lining members extend from a position along an outer surface of the inner diffuser that defines the radially inner edge of the diffuser space to a position along a side surface of the downstream end plate that defines the exhaust space as it moves radially outward, gradually toward the downstream side of the axis.

[0011] According to one aspect of the present disclosure, it is possible to reduce steam exhaust resistance and also to reduce welding distortion in the inner diffuser and the downstream end plate.

[0012] FIG. 1 is a perspective view of a steam turbine according to an embodiment of the present disclosure. FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 1. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 3. FIG. 5 is a perspective view of a lining member and a support pillar as viewed from the opposite side of the lining member according to an embodiment of the present disclosure. FIG. 6 is a perspective view of a lining member and a support pillar as viewed from the side of the lining member opposite the space according to an embodiment of the present disclosure. FIG. 7 is a flowchart showing a procedure for modifying an exhaust chamber according to an embodiment of the present disclosure. FIG. 8 is a perspective view of a lining member and a support pillar after a first joining process and before a second joining process according to an embodiment of the present disclosure. FIG. 9 is an explanatory diagram showing the flow of steam in an exhaust chamber before modification according to an embodiment of the present disclosure. FIG. 10 is an explanatory diagram showing the flow of steam in an exhaust chamber after modification according to an embodiment of the present disclosure. FIG. 11 is a cross-sectional view of an exhaust chamber according to a comparative example.

[0013] An embodiment of a steam turbine according to the present disclosure will be described in detail below.

[0014] Embodiment An embodiment of a steam turbine according to the present invention will be described with reference to FIGS. 1 to 11. FIG.

[0015] The steam turbine in this embodiment is a two-flow exhaust steam turbine. Therefore, as shown in Figures 1 and 2, this steam turbine includes a first steam turbine section 10a and a second steam turbine section 10b. As shown in Figure 2, each of the first steam turbine section 10a and the second steam turbine section 10b includes a turbine rotor 11 that rotates about an axis Ar, a casing 20 that covers the turbine rotor 11, a plurality of stator blade rows 17 fixed to the casing 20, and a steam inlet pipe 19. Hereinafter, the circumferential direction about the axis Ar will be simply referred to as the circumferential direction Dc, and the radial direction relative to the axis Ar will be referred to as the radial direction Dr. Furthermore, the side of the radial direction Dr that is closer to the axis Ar will be referred to as the radially inner side Dri, and the opposite side will be referred to as the radially outer side Dro.

[0016] The first steam turbine section 10a and the second steam turbine section 10b share a steam inlet pipe 19. In the first steam turbine section 10a, components other than the steam inlet pipe 19 are disposed on one side of the steam inlet pipe 19 in the axial direction Da relative to the steam inlet pipe 19. In the second steam turbine section 10b, components other than the steam inlet pipe 19 are disposed on the other side of the steam inlet pipe 19 in the axial direction Da relative to the steam inlet pipe 19. In the following description of each steam turbine section 10a, 10b, the side of the steam inlet pipe 19 in the axial direction Da is referred to as the axial upstream side Dau, and the opposite side is referred to as the axial downstream side Dad.

[0017] The first steam turbine section 10a and the second steam turbine section 10b have basically the same configuration, and therefore, the following description will mainly focus on the first steam turbine section 10a.

[0018] The turbine rotor 11 has a rotor shaft 12 extending in an axial direction Da centered on the axis Ar, and a plurality of moving blade rows 13 attached to the rotor shaft 12. The turbine rotor 11 is supported by bearings 18 so as to be rotatable about the axis Ar. The plurality of moving blade rows 13 are aligned in the axial direction Da. Each moving blade row 13 is composed of a plurality of moving blades aligned in the circumferential direction Dc. The turbine rotor 11 of the first steam turbine section 10a and the turbine rotor 11 of the second steam turbine section 10b are located on the same axis Ar, are connected to each other, and rotate integrally about the axis Ar.

[0019] The casing 20 has a body casing 21 and an exhaust chamber 25. The body casing 21 forms a substantially conical space centered on the axis Ar and covers the outer periphery of the turbine rotor 11. The multiple rotor blade rows 13 of the turbine rotor 11 are arranged in this conical space. The multiple stator blade rows 17 are arranged in the axial direction Da and in this conical space. Each of the multiple stator blade rows 17 is arranged on the axial upstream side Dau of one of the multiple rotor blade rows 13. The multiple stator blade rows 17 are fixed to the body casing 21.

[0020] As shown in FIG. 3 , the exhaust chamber 25 has a diffuser 26 , an exhaust casing 30 , a plurality of lining members 40 , and support columns 45 for each of the plurality of lining members 40 .

[0021] The diffuser 26 is annular with respect to the axis Ar and defines a diffuser space 26s that gradually widens toward the radially outer side Dro as it extends toward the axial downstream side Dad. Steam flowing out from the final blade row 13a of the turbine rotor 11 flows into the diffuser space 26s. The final blade row 13a is the blade row 13 located furthest downstream along the axis Dad among the multiple blade rows 13. The diffuser 26 includes an outer diffuser (or steam guide, flow guide) 27 that defines the edge of the radially outer side Dro of the diffuser space 26s, and an inner diffuser (or bearing cone) 29 that defines the edge of the radially inner side Dri of the diffuser space 26s. The outer diffuser 27 has an annular cross section perpendicular to the axis Ar and gradually widens toward the radially outer side Dro as it extends toward the axial downstream side Dad. The inner diffuser 29 also has an annular cross section perpendicular to the axis Ar, and gradually widens toward the radially outer side Dro as it extends toward the axial downstream side Dad. The outer diffuser 27 is connected to the body casing 21.

[0022] The exhaust casing 30 has an exhaust port 31. This exhaust port 31 opens from the interior radially outward Dro and vertically downward. A condenser Co that converts steam back into water is connected to this exhaust port 31. Therefore, the steam turbine of this embodiment is a downward exhaust type condensing steam turbine. Here, in a direction perpendicular to the axis Ar, the side on which the exhaust port 31 is located with reference to the axis Ar is referred to as the exhaust side Dpe, and the side opposite to the exhaust side Dpe is referred to as the non-exhaust side Dpu. Note that, as described above, since the steam turbine of this embodiment is a downward exhaust type condensing steam turbine, the exhaust side Dpe is on the vertically lower side, and the non-exhaust side Dpu is on the vertically upper side.

[0023] The exhaust casing 30 forms an exhaust space 30s that communicates with the diffuser 26. This exhaust space 30s extends around the outer periphery of the diffuser 26 in the circumferential direction Dc relative to the axis Ar, and guides steam that has flowed in from the diffuser space 26s to the exhaust port 31. The exhaust casing 30 has a downstream end plate 32, an upstream end plate 34, and an outer peripheral plate 36.

[0024] As shown in FIGS. 1 to 3 , the downstream end plate 32 defines the edge of the axial downstream side Dad of the exhaust space 30s. This downstream end plate 32 extends in a direction including a component of the radial direction Dr and in the circumferential direction Dc, and is substantially perpendicular to the axis Ar. The portion of the downstream end plate 32 above the axis Ar is approximately semicircular. On the other hand, the portion of the downstream end plate 32 below the axis Ar is approximately rectangular. However, a circular opening is formed in the downstream end plate 32, the center of which is the axis Ar. The edge of this circular opening forms the edge of the radially inner side Dri of the downstream end plate 32. The edge of the radially inner side Dri of the downstream end plate 32 is connected to the edge of the axial downstream side Dad of the inner diffuser. The lower edge of this downstream end plate 32 forms part of the edge of the exhaust port 31.

[0025] The outer peripheral plate 36 defines the edge of the radially outer side Dro of the exhaust space 30s. This outer peripheral plate 36 extends in the axial direction Da and in a direction including a component in the circumferential direction Dc about the axis Ar. This outer peripheral plate 36 has a semi-cylindrical shape with an upper side forming a semi-cylindrical cylinder. An edge on the axial downstream side Dad of this outer peripheral plate 36 is connected to the downstream end plate 32. In addition, the lower edge of this outer peripheral plate 36 forms part of the edge of the exhaust port 31.

[0026] The upstream end plate 34 defines the edge of the exhaust space 30s on the upstream side Dau in the axial direction. The upstream end plate 34 is disposed on the upstream side Dau in the axial direction of the diffuser 26. The upstream end plate 34 extends from the outer peripheral surface of the body casing 21 toward the radially outward side Dro. The upstream end plate 34 is substantially perpendicular to the axis Ar. Thus, the upstream end plate 34 faces the downstream end plate 32 with a gap in the axial direction Da. The lower edge of the upstream end plate 34 forms part of the edge of the exhaust port 31. The portion of the radially outward edge Dro of the upstream end plate 34, excluding the portion that forms the edge of the exhaust port 31, is connected to the outer peripheral plate 36.

[0027] The exhaust casing 30 of the first steam turbine section 10a and the exhaust casing 30 of the second steam turbine section 10b are connected to each other and integrated together.

[0028] 3 and 4 , the multiple lining members 40 are arranged only on the non-exhaust side Dpu with respect to the axis Ar and are lined up in the circumferential direction Dc. Each of the multiple lining members 40 is arranged straddling from the diffuser space 26s to the exhaust space 30s. Each of the multiple lining members 40 extends from a position along a space side surface 29p that defines the edge of the radially inner side Dri of the diffuser space 26s in the inner diffuser 29, gradually toward the radially outer side Dro, and then gradually toward the axial downstream side Dad, to a position along a space side surface 32p that defines the exhaust space 30s in the downstream end plate 32.

[0029] As described above, a support column 45 is provided for each of the plurality of lining members 40. Therefore, the number of support columns 45 is the same as the number of the plurality of lining members 40. Each support column 45 has a first end 45a and a second end 45b. The second end 45b of each support column 45 is joined by welding to the lining member 40 corresponding to that support column 45. The first end 45a of each support column 45 is joined by welding to the downstream end plate 32.

[0030] As shown in FIGS. 5, 6 and 8, the lining member 40 has a lining plate 41 and a plurality of ribs 43.

[0031] The interior panel 41 has a space side surface 41p and an anti-space side surface 41pa that are back-to-back, and a circular opening 42. The space side surface 41p faces the radially outward direction Dro, and the anti-space side surface 41pa faces the radially inward direction Dri. The edge of the space side surface 41p and the edge of the anti-space side surface 41pa each have an arc-shaped or linear outer edge 41o, an arc-shaped or linear inner edge 41i, and a pair of side edges 41s. The inner edge 41i is back-to-back with respect to the outer edge 41o. The length of the inner edge 41i is shorter than the length of the outer edge 41o. The pair of side edges 41s are back-to-back with respect to each other. The lengths of the pair of side edges 41s are the same. The opening 42 penetrates the interior panel 41 from the space side surface 41p to the anti-space side surface 41pa at a midpoint between the pair of side edges 41s.

[0032] The multiple ribs 43 include a first rib 43a disposed on one of the pair of side edges 41s and a second rib 43b disposed on the other side edge 41s, based on the position of the opening 42 in the lining panel 41. The first rib 43a and the second rib 43b both extend from the outer edge 41o to the inner edge 41i along the anti-space side surface 41pa of the lining panel 41. The distance between the first rib 43a and the second rib 43b gradually increases from the inner edge 41i toward the outer edge 41o.

[0033] A second end 45b of the support post 45 is inserted into the opening 42 of the interior panel 41, and this second end 45b is joined to the edge of the opening 42 by welding.

[0034] Of the lining plates 41 in each of the multiple lining members 40, the radial dimension Lre of the lining plate 41 located on the exhaust side Dpe in the circumferential direction Dc is smaller than the radial dimension Lru of the lining plate 41 located on the non-exhaust side Dpu in the circumferential direction Dc. Specifically, in this embodiment, the radial dimension Lr of the lining plates 41 arranged in the circumferential direction Dc gradually decreases as they are positioned closer to the exhaust side Dpe in the circumferential direction Dc.

[0035] Next, a method for modifying the exhaust chamber 25 will be described with reference to the flowchart shown in Fig. 7. The modification method here is a method for providing a plurality of lining members 40 and a plurality of support columns 45 to an exhaust chamber 25a (shown in Fig. 9) that does not already have a plurality of lining members 40 and a plurality of support columns 45.

[0036] First, the above-described plurality of lining members 40 and the plurality of support columns 45 are prepared (preparation step S1).

[0037] Next, the first end 45a of each support pillar 45 is welded to the space side surface 32p of the downstream end plate 32 so that the multiple support pillars 45 are arranged at intervals from each other in the circumferential direction Dc (first joining step S2).

[0038] Next, as shown in Figure 8, the second end 45b of the support post 45 fixed to the downstream end plate 32 is inserted into the opening 42 of the lining member 40, and this second end 45b is joined to the lining member 40 by welding (second joining step S3). At this time, the space side surface 41p of the lining plate 41 faces the radially outer side Dro, and the anti-space side surface 41pa of the lining plate 41 faces the radially outer side Dro. The outer edge 41o of the lining plate 41 is located radially outer Dro relative to the outer edge 41o of the lining plate 41. The lining plate 41 gradually extends from a position along the space side surface 29p of the inner diffuser 29 toward the radially outer side Dro, gradually toward the axial downstream side Dad, to a position along the space side surface 32p of the downstream end plate 32. When joining the second end 45b of the support pillar 45 to the lining member 40, the lining member 40 is rotated slightly around the central axis of the support pillar 45 to adjust the angle of the lining member 40 around the central axis of the support pillar 45. After this adjustment is completed, the edge of the opening 42 of the lining member 40 and the support pillar 45 are joined by welding.

[0039] This completes the modification of the exhaust chamber 25a.

[0040] When the modification of the exhaust chamber 25a is completed, none of the multiple lining members 40 is joined to the inner diffuser 29 or the downstream end plate 32. That is, as shown in Fig. 3, the outer edge 41o of the lining plate 41 is not connected to the spatial side surface 32p of the downstream end plate 32, and a gap c exists between the outer edge 41o and the spatial side surface 32p of the downstream end plate 32. Also, the inner edge 41i of the lining plate 41 is not connected to the spatial side surface 29p of the inner diffuser 29, and a gap c exists between the inner edge 41i and the spatial side surface 29p of the inner diffuser 29. Furthermore, as shown in Fig. 4, adjacent lining members 40 in the circumferential direction Dc are not joined to each other, and a gap c also exists between adjacent lining members 40 in the circumferential direction Dc.

[0041] As described above, in the modification method of this embodiment, the support pillars 45 are first joined to the downstream end plate 32, and then the lining member 40 is attached to the diffuser space 26s and the exhaust space 30s from the radially outer side Dro toward the radially inner side Dri. This makes it possible to easily join the lining member 40 to the support pillars 45. Furthermore, in this embodiment, since the support pillars 45 are cylindrical and the openings 42 of the lining member 40 are circular, the lining member 40 can be rotated slightly around the central axis of the support pillars 45 to adjust the angle of the lining member 40 around the central axis of the support pillars 45.

[0042] Next, the effects of the modified exhaust chamber 25 will be described.

[0043] 9 , in the exhaust chamber 25a before modification, steam that flows out from the final blade row 13a of the turbine rotor 11 to the axial downstream side Dad flows into the diffuser space 26s. This steam flows inside the diffuser space 26s toward the axial downstream side Dad and then toward the radially outer side Dro, and then flows into the exhaust space 30s.

[0044] Within the region of the non-exhaust side Dpu with respect to the axis Ar, steam that has flowed into the exhaust space 30s along the space side surface 27p of the outer diffuser 27 flows in the direction of a tangent at the end of the radially outer side Dro of this space side surface 27p, i.e., in the tangential direction. When this steam collides with the outer peripheral plate 36, part of it flows along the outer peripheral plate 36 to the axial upstream side Dau, and the other part flows along the outer peripheral plate 36 in the circumferential direction Dc to the exhaust side Dpe.

[0045] The steam that flows along the outer peripheral plate 36 to the axial upstream side Dau gradually changes its flow direction to the circumferential direction Dc and flows to the exhaust side Dpe along the inner peripheral surface of the outer peripheral plate 36. The steam that flows along the outer peripheral plate 36 to the exhaust side Dpe is exhausted from the exhaust port 31.

[0046] Furthermore, within the region of the non-exhaust side Dpu with respect to the axis Ar, steam that flows into the exhaust space 30s along the spatial side surface 29p of the inner diffuser 29 collides with the downstream end plate 32, and a portion of the steam flows along the downstream end plate 32 to the radially outer side Dro. The steam that flows to the radially outer side Dro collides with the outer peripheral plate 36 and flows along the outer peripheral plate 36 in the circumferential direction Dc to the exhaust side Dpe. This steam is exhausted from the exhaust port 31.

[0047] The remaining steam that flows along the side surface 29p of the inner diffuser 29 and collides with the downstream end plate 32 flows radially inward Dri along the downstream end plate 32, and then flows toward the axial upstream side Dau along the side surface 29p of the inner diffuser 29. This steam joins with the steam that has flowed out from the final blade row 13a of the turbine rotor 11 to the axial downstream side Dad, and flows within the diffuser space 26s toward the axial downstream side Dad and the radially outward side Dro.

[0048] That is, a backflow of steam occurs in the region at the boundary between the diffuser space 26s and the exhaust space 30s, along the inner diffuser 29 and the downstream end plate 32. When a backflow of steam occurs, the exhaust resistance of the steam increases, and the amount of pressure recovery decreases.

[0049] On the other hand, within the region of the exhaust side Dpe with respect to the axis Ar, the flow direction of steam that has flowed into the exhaust space 30s along the spatial side surface 27p of the outer diffuser 27 includes a directional component approaching the exhaust port 31, which is a tangent to the end of the radially outer side surface Dro of the spatial side surface 27p, and a directional component approaching the exhaust port 31 in the circumferential direction Dc relative to the axis Ar. This is because steam containing a large amount of the circumferential direction Dc component from the region of the non-exhaust side Dpu in the exhaust chamber 25 flows into the region of the exhaust side Dpe. As described above, the flow direction component of steam that has flowed into the exhaust space 30s along the spatial side surface 27p of the outer diffuser 27 includes a component approaching the exhaust port 31, and therefore steam that has flowed into the exhaust space 30s along the spatial side surface 27p of the outer diffuser 27 is exhausted from the exhaust port 31 without flowing back.

[0050] Furthermore, within the region of the exhaust side Dpe with respect to the axis Ar, steam that flows into the exhaust space 30s along the spatial side surface 29p of the inner diffuser 29 collides with the downstream end plate 32 and flows entirely toward the radially outer side Dro, which is the side of the exhaust port 31. This is because the directional component of the steam flowing along the spatial side surface 29p of the inner diffuser 29 includes a directional component toward the exhaust port 31. As a result, steam that flows into the exhaust space 30s along the spatial side surface 29p of the inner diffuser 29 is exhausted from the exhaust port 31 without flowing back.

[0051] In the case of low-load operation where the steam flow rate into the steam turbine is low or when the condenser Co is at a low vacuum, the directional component of the flow direction of the steam flowing out from the final blade row 13a of the turbine rotor 11 is a circumferential component Dc about the axis Ar, i.e., a swirling component, which is larger than the directional component toward the axial downstream side Dad. Therefore, in this case, the steam flowing out from the final blade row 13a of the turbine rotor 11 tends to drift radially outward Dro within the diffuser space 26s. Therefore, of the steam flowing into the diffuser space 26s, the flow rate of the steam on the outer diffuser 27 side is greater than the flow rate of the steam on the inner diffuser 29 side. In other words, in the case of low-load operation or when the condenser Co is at a low vacuum, the steam flows more along the inner circumferential surface of the outer diffuser 27. Therefore, in the pre-modification exhaust chamber 25, in the non-exhaust side Dpu based on the axis Ar, when operating at low load or when the condenser Co has a low degree of vacuum, the amount of steam that flows back within this area increases, increasing the steam exhaust resistance and reducing the amount of pressure recovery.

[0052] Even within the region of the non-exhaust side Dpu relative to the axis Ar, the region where steam flows back gradually becomes smaller as the region approaches the exhaust side Dpe in the circumferential direction Dc. This is because, as the region approaches the exhaust side Dpe in the circumferential direction Dc, the flow direction component of the steam that flows into the exhaust space 30s along the spatial side surface 29p of the inner diffuser 29 toward the exhaust port 31 gradually increases. Furthermore, within the exhaust space 30s, steam containing a large circumferential direction Dc component flows from the region of the non-exhaust side Dpu in the circumferential direction Dc.

[0053] 10 , in the modified exhaust chamber 25, as in the unmodified exhaust chamber 25a, steam that flows out from the final blade row 13a of the turbine rotor 11 to the axial downstream side Dad flows into the diffuser space 26s. This steam flows through the diffuser space 26s toward the axial downstream side Dad and then toward the radially outer side Dro, and then flows into the exhaust space 30s.

[0054] Within the region of the non-exhaust side Dpu relative to the axis Ar, similar to the exhaust chamber 25a before modification, steam that has flowed into the exhaust space 30s along the space side surface 27p of the outer diffuser 27 flows in the direction of a tangent to the end of the radially outer side Dro of this space side surface 27p. When this steam collides with the outer peripheral plate 36, part of it flows along the outer peripheral plate 36 to the axial upstream side Dau, and the other part flows along the outer peripheral plate 36 in the circumferential direction Dc to the exhaust side Dpe.

[0055] The steam that flows along the outer peripheral plate 36 to the axial upstream side Dau gradually changes its flow direction to the circumferential direction Dc and flows to the exhaust side Dpe along the inner peripheral surface of this outer diffuser 27. The steam that flows along the outer peripheral plate 36 to the exhaust side Dpe is exhausted from the exhaust port 31.

[0056] Furthermore, within the region of the non-exhaust side Dpu with respect to the axis Ar, steam flows along the space side surface 29p of the inner diffuser 29, then flows along the space side surface 41p of the lining member 40, and then collides with the downstream end plate 32. Substantially all of the steam that collides with the downstream end plate 32 flows along the downstream end plate 32 to the radially outer side Dro. The steam that has flowed to the radially outer side Dro collides with the outer peripheral plate 36 and flows along the outer peripheral plate 36 in the circumferential direction Dc to the exhaust side Dpe. This steam that has flowed along the outer peripheral plate 36 to the exhaust side Dpe is exhausted from the exhaust port 31.

[0057] As described above, in the modified exhaust chamber 25, steam that flows along the spatial side surface 29p of the inner diffuser 29 does not substantially flow back within the non-exhaust side Dpu relative to the axis Ar. This is mainly due to the following reasons: (1) The spatial side surface 41p of the lining member 40 is located radially outward Dro of the inner diffuser 29, so the flow rate of steam flowing along the lining member 40 is greater than the flow rate of steam flowing along the inner diffuser 29. (2) The spatial side surface 41p of the lining member 40 is located radially outward Dro of the inner diffuser 29, so no pocket is formed, such as the corner between the inner diffuser 29 and the downstream end plate 32, as in the exhaust chamber 25a before the modification. (3) The angle between the space side surface 41p of the lining member 40 and the space side surface 32p of the downstream end plate 32 is larger than the angle between the space side surface 29p of the inner diffuser 29 and the space side surface 32p of the downstream end plate 32, so that the collision angle of the steam flowing along the lining member 40 with the downstream end plate 32 is shallower.

[0058] On the other hand, within the region of the exhaust side Dpe based on the axis Ar, as in the exhaust chamber 25a before the modification, steam that flows into the exhaust space 30s along the space side surface 27p of the outer diffuser 27 is exhausted from the exhaust port 31 without flowing back.

[0059] Furthermore, within the region of the exhaust side Dpe based on the axis Ar, as in the exhaust chamber 25a before modification, steam that flows into the exhaust space 30s along the space side surface 29p of the inner diffuser 29 is exhausted from the exhaust port 31 without flowing back.

[0060] As described above, in the modified exhaust chamber 25 of this embodiment, the occurrence of backflow of steam in the diffuser space 26s and the exhaust space 30s can be suppressed, and the exhaust resistance of steam can be reduced.

[0061] In this embodiment, as described above, the radial dimension Lre of the lining plate 41 located on the exhaust side Dpe in the circumferential direction Dc is smaller than the radial dimension Lru of the lining plate 41 located on the non-exhaust side Dpu in the circumferential direction Dc among the lining plates 41 of each of the multiple lining members 40. This is because, as described above, even within the region of the non-exhaust side Dpu relative to the axis Ar, the region through which steam backflows gradually becomes smaller as the region approaches the exhaust side Dpe in the circumferential direction Dc. Therefore, in this embodiment, it is possible to reduce the amount of plate material used to manufacture the lining member 40.

[0062] Furthermore, the effects of the modified exhaust chamber 25 of this embodiment will be described in comparison with an exhaust chamber 25b shown in FIG. 10 as a comparative example.

[0063] The exhaust chamber 25b of this comparative example has multiple lining members 40, similar to the modified exhaust chamber 25 of the present embodiment. Similar to the modified exhaust chamber 25 of the present embodiment, the multiple lining members 40 are arranged across the diffuser space 26s and the exhaust space 30s, and are aligned in the circumferential direction Dc. Each of the multiple lining members 40 extends from the space side surface 29p of the inner diffuser 29 toward the radially outer side Dro, gradually toward the axial downstream side Dad, and to the space side surface 32p of the downstream end plate 32. The multiple lining members 40 and the inner diffuser 29 are connected by welding. The multiple lining members 40 and the downstream end plate 32 are also connected by welding. Furthermore, the multiple lining members 40 are also connected to each other by welding.

[0064] In this comparative example, welding distortion occurs in the inner diffuser 29 during the process of welding the multiple lining members 40 to the inner diffuser 29. Furthermore, welding distortion occurs in the downstream end plate 32 during the process of welding the multiple lining members 40 to the downstream end plate 32. If welding distortion occurs in the inner diffuser 29 or the downstream end plate 32, the weldability of the lining members 40 to be welded subsequently will decrease. Furthermore, if the inner diffuser 29 or the downstream end plate 32 is distorted, turbulence will occur in the steam flow at the distorted parts, increasing the steam exhaust resistance.

[0065] In addition, in this comparative example, since the multiple lining members 40 are connected to each other by welding, the difference in thermal expansion of the multiple lining members 40 between when steam is flowing in the exhaust chamber 25 and when steam is not flowing in the exhaust chamber 25 causes thermal stress in the multiple lining members 40, increasing the possibility of damage to the multiple lining members 40.

[0066] On the other hand, in the modified exhaust chamber 25 of this embodiment, when one lining member 40 is fixed inside the exhaust chamber 25, welds are generated only on the downstream end plate 32, and the area of ​​the welds can be made much smaller than in the comparative example. This makes it possible to suppress the occurrence of welding distortion in the downstream end plate 32. Furthermore, in the modified exhaust chamber 25 of this embodiment, when one lining member 40 is fixed inside the exhaust chamber 25, no welds are generated on the inner diffuser 29, so no welding distortion occurs in the inner diffuser 29. Therefore, in the modified exhaust chamber 25 of this embodiment, the welding workability of the lining member 40 is improved compared to the comparative example. Furthermore, because distortion of the inner diffuser 29 and the downstream end plate 32 is suppressed, an increase in steam exhaust resistance can be suppressed.

[0067] Furthermore, in this embodiment, the multiple lining members 40 are not in contact with the inner diffuser 29, and there is a gap c between them and the inner diffuser 29. Therefore, in this embodiment, even if the lining members 40 undergo thermal expansion, stress generation in the lining members 40 and the inner diffuser 29 due to this thermal expansion can be suppressed.

[0068] In this embodiment, the plurality of lining members 40 are not in contact with the downstream end plate 32, and a gap c is formed between the lining members 40 and the downstream end plate 32. Therefore, in this embodiment, even if the lining members 40 thermally expand, stress generated in the lining members 40 and the downstream end plate 32 due to this thermal expansion can be suppressed.

[0069] Furthermore, in this embodiment, the multiple lining members 40 are not connected to each other by welding, and there are gaps c between them. Therefore, even if each of the multiple lining members 40 thermally expands, stress generation in the lining members 40 due to this thermal expansion can be suppressed.

[0070] "Modification" In the exhaust chamber 25 of the above embodiment, the lining member 40 is not provided on the exhaust side Dpe of the axis Ar. However, the lining member 40 may also be provided on the exhaust side Dpe of the axis Ar. However, because the effect of the lining member 40 is small on the exhaust side Dpe of the axis Ar, it is preferable to determine whether or not to provide the lining member 40 on the exhaust side Dpe of the axis Ar, taking cost-effectiveness into consideration.

[0071] In the above embodiment, the radial dimension Lre of the lining plate 41 located on the exhaust side Dpe in the circumferential direction Dc is smaller than the radial dimension Lru of the lining plate 41 located on the non-exhaust side Dpu in the circumferential direction Dc. However, the radial dimensions of all the lining plates 41 may be the same.

[0072] In the above embodiment, the first end 45 a of the support column 45 is welded to the downstream end plate 32. However, the first end 45 a of the support column 45 may be connected to the inner diffuser 29. However, because the side surface 29 p of the inner diffuser 29 is a curved surface, from the viewpoint of welding, it is preferable to weld the first end 45 a to the side surface 32 p of the downstream end plate 32, which is flat.

[0073] The present disclosure is not limited to the embodiments described above, and various additions, modifications, substitutions, partial deletions, etc. are possible within the scope of the conceptual idea and spirit of the present invention as derived from the content defined in the claims and their equivalents.

[0074] [Additional Notes] The exhaust chamber 25 in the above embodiment can be understood as follows, for example.

[0075] (1) The exhaust chamber 25 in the first embodiment is an exhaust casing (30) having an exhaust port (31) opening toward the radially outer side (Dro), the exhaust casing (30) communicating with the diffuser space (26s), the exhaust casing (30) widening in a circumferential direction (Dc) relative to the axis Ar, and the exhaust space (26s) for guiding the steam flowing in from the diffuser space (26s) to the exhaust port (31); a plurality of lining members (40) arranged astride the diffuser space (26s) and the exhaust space (30s), the lining members (40) being aligned in the circumferential direction (Dc); and support columns (45) provided for each of the plurality of lining members (40). The diffuser 26 has an inner diffuser 29 that has an annular cross section perpendicular to the axis Ar, gradually widens toward the radially outer side Dro as it moves toward the axial downstream side Dad, and defines a radially inner edge Dri of the diffuser space 26s with respect to the axis Ar. The exhaust casing 30 has a downstream end plate 32 that defines the axially downstream side Dad edge of the exhaust space 30s. The downstream end plate 32 widens in a direction that includes a radial direction Dr component with respect to the axis Ar and in the circumferential direction Dc. The radially inner edge Dri of the downstream end plate 32 is connected to the axially downstream side Dad edge of the inner diffuser 29. Each of the multiple lining members 40 extends from a position along a space side surface 29p that defines the edge of the radially inner side Dri of the diffuser space 26s in the inner diffuser 29, gradually toward the axial downstream side Dad as it moves toward the radially outer side Dro, to a position along a space side surface 32p that defines the exhaust space 30s in the downstream end plate 32. The support pillar 45 for each of the multiple lining members 40 has a first end portion 45a and a second end portion 45b. The first end portion 45a of the support pillar 45 is joined to the inner diffuser 29 or the downstream end plate 32.The second end 45b of the support pillar 45 is joined to any one of the plurality of lining members 40. None of the plurality of lining members 40 is joined to the inner diffuser 29 or the downstream end plate 32.

[0076] First, a comparative example 1 of the present embodiment will be described. The exhaust chamber 25a of the comparative example 1 is an exhaust chamber obtained by omitting the plurality of lining members 40 and the support columns 45 for each of the plurality of lining members 40 from the exhaust chamber 25 of the present embodiment.

[0077] In this comparative example 1, steam that flows out from the final blade row 13 a of the turbine rotor 11 to the axial downstream side Dad flows into the diffuser space 26 s. This steam flows inside the diffuser space 26 s toward the axial downstream side Dad and toward the radially outer side Dro, and then flows into the exhaust space 30 s.

[0078] The steam that flows into the exhaust space 30s along the space side surface 29p of the inner diffuser 29 collides with the downstream end plate 32, and a portion of the steam flows radially outward Dro along the downstream end plate 32. The steam that flows radially outward Dro collides with the outer peripheral plate 36 and flows along the outer peripheral plate 36 in the circumferential direction Dc to the exhaust side Dpe. This steam that flows along the outer peripheral plate 36 to the exhaust side Dpe is exhausted from the exhaust port 31.

[0079] The remaining steam that flows along the side surface 29p of the inner diffuser 29 and collides with the downstream end plate 32 flows radially inward Dri along the downstream end plate 32, depending on the situation, and then flows toward the axial upstream side Dau along the side surface 29p of the inner diffuser 29. This steam joins with the steam that has flowed out from the final blade row 13a of the turbine rotor 11 toward the axial downstream side Dad, and flows toward the radially outward Dro within the diffuser space 26s while heading toward the axial downstream side Dad.

[0080] That is, in Comparative Example 1, a backflow of steam may occur in the region at the boundary between the diffuser space 26s and the exhaust space 30s, along the inner diffuser 29 and the downstream end plate 32. When a backflow of steam occurs, the exhaust resistance of the steam increases, and the amount of pressure recovery decreases.

[0081] In the exhaust chamber 25 of this embodiment, similarly to the exhaust chamber 25 of Comparative Example 1, steam that flows out from the final blade row 13a of the turbine rotor 11 to the axial downstream side Dad flows into the diffuser space 26s. This steam flows through the diffuser space 26s toward the axial downstream side Dad and toward the radially outer side Dro, and then flows into the exhaust space 30s.

[0082] In this embodiment, the steam flows along the space side surface 29p of the inner diffuser 29, then flows along the space side surface 41p of the lining member 40, and then collides with the downstream end plate 32. Substantially all of the steam that collides with the downstream end plate 32 flows along the downstream end plate 32 to the radially outer side Dro. The steam that has flowed to the radially outer side Dro collides with the outer peripheral plate 36 and flows along the outer peripheral plate 36 in the circumferential direction Dc to the exhaust side Dpe. This steam that has flowed along the outer peripheral plate 36 to the exhaust side Dpe is exhausted from the exhaust port 31.

[0083] In this embodiment, the steam that flows along the space side surface 29p of the inner diffuser 29 does not substantially flow back. This is mainly due to the following reasons: (1) The space side surface 41p of the lining member 40 is located radially outward Dro of the inner diffuser 29, so the flow rate of steam flowing along the lining member 40 is greater than the flow rate of steam flowing along the inner diffuser 29. (2) The space side surface 41p of the lining member 40 is located radially outward Dro of the inner diffuser 29, so a pocket such as the corner between the inner diffuser 29 and the downstream end plate 32 is not formed, as in the exhaust chamber 25a before the modification. (3) The angle between the space side surface 41p of the lining member 40 and the space side surface 32p of the downstream end plate 32 is larger than the angle between the space side surface 29p of the inner diffuser 29 and the space side surface 32p of the downstream end plate 32, so the collision angle of the steam that flows along the lining member 40 with the downstream end plate 32 is shallower.

[0084] As described above, in this embodiment, the occurrence of backflow of steam can be suppressed, and the exhaust resistance of steam can be reduced.

[0085] Next, Comparative Example 2 of the present embodiment will be described. The exhaust chamber 25b in Comparative Example 2 has multiple lining members 40, similar to the exhaust chamber 25 of the present embodiment. Similar to the exhaust chamber 25 of the present embodiment, the multiple lining members 40 are arranged across the diffuser space 26s and the exhaust space 30s, and are aligned in the circumferential direction Dc. Each of the multiple lining members 40 extends from the space side surface 29p of the inner diffuser 29 toward the radially outer side Dro, gradually toward the axially downstream side Dad, and to the space side surface 32p of the downstream end plate 32. The multiple lining members 40 and the inner diffuser 29 are connected by welding. The multiple lining members 40 and the downstream end plate 32 are also connected by welding. Furthermore, the multiple lining members 40 are also connected to each other by welding.

[0086] In Comparative Example 2, welding distortion occurs in the inner diffuser 29 during the process of welding the multiple lining members 40 to the inner diffuser 29. Furthermore, welding distortion occurs in the downstream end plate 32 during the process of welding the multiple lining members 40 to the downstream end plate 32. If welding distortion occurs in the inner diffuser 29 or the downstream end plate 32, the weldability of the lining members 40 to be welded subsequently will decrease. Furthermore, if the inner diffuser 29 or the downstream end plate 32 is distorted, turbulence will occur in the steam flow at the distorted parts, increasing the steam exhaust resistance.

[0087] On the other hand, in the exhaust chamber 25 of this embodiment, when one lining member 40 is fixed, welding is performed only on the downstream end plate 32 or the inner diffuser 29, and the area of ​​the welding can be made much smaller than in Comparative Example 2. This makes it possible to suppress the occurrence of welding distortion in the downstream end plate 32 and the inner diffuser 29. Therefore, in the exhaust chamber 25 of this embodiment, the welding workability of the lining member 40 is improved compared to Comparative Example 2. Furthermore, because distortion in the inner diffuser 29 and the downstream end plate 32 is suppressed, an increase in steam exhaust resistance can be suppressed.

[0088] (2) The exhaust chamber 25 according to the second embodiment is the exhaust chamber 25 according to the first embodiment, wherein the plurality of lining members 40 are not in contact with the inner diffuser 29 .

[0089] In this embodiment, even if the lining member 40 undergoes thermal expansion, stresses generated in the lining member 40 and the inner diffuser 29 due to this thermal expansion can be suppressed.

[0090] (3) The exhaust chamber 25 in a third aspect is the exhaust chamber 25 in the first or second aspect, wherein the plurality of lining members 40 are not in contact with the downstream end plate 32 .

[0091] In this embodiment, even if the lining member 40 undergoes thermal expansion, stresses occurring in the lining member 40 and the downstream end plate 32 due to this thermal expansion can be suppressed.

[0092] (4) In the exhaust chamber 25 according to a fourth aspect, in the exhaust chamber 25 according to any one of the first to third aspects, the plurality of lining members 40 are not in contact with each other.

[0093] In this embodiment, even if each of the plurality of lining members 40 thermally expands, the generation of stress in the lining members 40 due to this thermal expansion can be suppressed.

[0094] (5) In the fifth aspect, the exhaust chamber 25 is an exhaust chamber 25 in any one of the first to fourth aspects, in which the multiple lining members 40 are arranged at least on the non-exhaust side Dpu of the exhaust side Dpe where the exhaust port 31 is located and the non-exhaust side Dpu opposite the exhaust side Dpe, based on the axis Ar.

[0095] The backflow of steam described in the comparative example 1 is likely to occur on the non-exhaust side Dpu relative to the axis Ar. Therefore, by arranging multiple lining members 40 at least on the non-exhaust side Dpu, it is possible to efficiently suppress the occurrence of backflow of steam throughout the exhaust chamber 25.

[0096] (6) In the sixth aspect, the exhaust chamber 25 is an exhaust chamber 25 in any one of the first to fourth aspects, in which the multiple lining members 40 are arranged only on the non-exhaust side Dpu, of the exhaust side Dpe where the exhaust port 31 is located and the non-exhaust side Dpu opposite the exhaust side Dpe, with respect to the axis Ar.

[0097] The backflow of steam described in Comparative Example 1 above is likely to occur on the non-exhaust side Dpu relative to the axis Ar. Therefore, by arranging multiple lining members 40 only on the non-exhaust side Dpu, it is possible to prevent backflow of steam throughout the exhaust chamber 25. Furthermore, by arranging them only on the non-exhaust side Dpu, it is possible to reduce the material costs and installation costs of the lining members 40.

[0098] (7) In the seventh aspect, in the exhaust chamber 25 in any one of the first to sixth aspects, of the multiple lining members 40 arranged in the circumferential direction Dc, the radial length Dr of the lining member 40 located on the non-exhaust side Dpu opposite the exhaust side Dpe where the exhaust port 31 is located is longer than the radial length Dr of the lining member 40 located on the exhaust side Dpe than the lining member 40 located on the non-exhaust side Dpu.

[0099] The region where the steam flows back, as described in the comparative example 1, gradually becomes smaller as it approaches the exhaust side Dpe in the circumferential direction Dc. Therefore, in this embodiment, the amount of material used to manufacture the lining member 40 can be reduced while suppressing the steam flow back.

[0100] (8) An eighth aspect of the exhaust chamber 25 is the exhaust chamber 25 of any one of the first to seventh aspects, wherein the support pillar 45 is cylindrical. Each of the multiple lining members 40 has a lining plate 41 that extends from a position along the spatial side surface 29p of the inner diffuser 29 toward the radially outer side Dro, gradually toward the axial downstream side Dad, and to a position along the spatial side surface 32p of the downstream end plate 32. A circular opening 42 is formed in the lining plate 41. The second end 45b of the support pillar 45 fits into the opening 42 of the lining plate 41 and is joined to an edge of the opening 42.

[0101] In this embodiment, when joining the second end 45b of the support pillar 45 to the lining member 40, the lining member 40 can be rotated slightly around the central axis of the support pillar 45, making it possible to easily adjust the angle of the lining member 40 around the central axis of the support pillar 45.

[0102] (9) In a ninth aspect, the exhaust chamber 25 is an exhaust chamber 25 in any one of the first to seventh aspects, wherein each of the plurality of lining members 40 has a lining plate 41 that extends from a position along the space side surface 29p of the inner diffuser 29 toward the radially outer side Dro, gradually toward the axial downstream side Dad, to a position along the space side surface 32p of the downstream end plate 32, and one or more ribs 43 joined to an anti-space side surface 41pa of the lining plate 41 that faces the radially inner side Dri.

[0103] In this embodiment, deformation of the lining member 40 can be suppressed.

[0104] (10) In a tenth aspect, the exhaust chamber 25 of the ninth aspect has one or more ribs 43 including a first rib 43a disposed on one side in the circumferential direction Dc and a second rib 43b disposed on the other side in the circumferential direction Dc, based on a joint position between the lining plate 41 and the support pillar 45. The first rib 43a and the second rib 43b each extend along the anti-space side surface 41pa, gradually toward the axial downstream side Dad as they move toward the radially outer side Dro.

[0105] (11) In the exhaust chamber 25 of the eleventh aspect, in the exhaust chamber 25 of the tenth aspect, the distance in the circumferential direction Dc between the first rib 43a and the second rib 43b gradually widens toward the axial downstream side Dad.

[0106] The steam turbines in the above embodiments can be understood, for example, as follows: (12) A steam turbine in a twelfth aspect includes the exhaust chamber 25 in any one of the first to eleventh aspects, the turbine rotor 11, and a body casing 21 covering the outer periphery of the turbine rotor 11.

[0107] The steam turbine of this aspect includes the exhaust chamber 25 of the first aspect, so that the occurrence of backflow of steam can be suppressed, and the exhaust resistance of steam can be reduced. Furthermore, in the steam turbine of this aspect, the occurrence of welding distortion in the downstream end plate 32 and the inner diffuser 29 can be suppressed.

[0108] The method for modifying the exhaust duct in the above embodiments can be understood as follows, for example. (13) A method for modifying an exhaust duct in a thirteenth aspect is a method for modifying an exhaust duct 25a of a steam turbine that can guide steam flowing out from a final row of moving blades 13a of a turbine rotor 11 that rotates about an axis Ar to the outside, the exhaust duct 25a comprising: a diffuser 26 that is annular about the axis Ar and forms a diffuser space 26s into which the steam flowing out from the final row of moving blades 13a of the turbine rotor 11 that rotates about the axis Ar can flow, the diffuser 26 having an annular shape about the axis Ar and gradually widening radially outward Dro relative to the axis Ar as it extends toward the axial downstream side Dad; and an exhaust casing 30 that has an exhaust port 31 that opens toward the radially outward side Dro, communicates with the diffuser space 26s, widens in a circumferential direction Dc relative to the axis Ar, and forms an exhaust space 30s that guides the steam that flows in from the diffuser space 26s to the exhaust port 31. The diffuser 26 has an inner diffuser 29 that has an annular cross section perpendicular to the axis Ar, gradually widens toward the radially outer side Dro as it moves toward the axial downstream side Dad, and defines a radially inner edge Dri of the diffuser space 26s with respect to the axis Ar. The exhaust casing 30 has a downstream end plate 32 that defines the axially downstream side Dad edge of the exhaust space 30s. The downstream end plate 32 widens in a direction that includes a radial direction Dr component with respect to the axis Ar and in the circumferential direction Dc. The radially inner edge Dri of the downstream end plate 32 is connected to the axially downstream side Dad edge of the inner diffuser 29.The method for modifying the exhaust chamber 25a includes a preparation step S1 of preparing a plurality of lining members 40 and support columns 45 for each of the plurality of lining members 40; a first joining step S2 of joining the first end 45a of each of the support columns 45 to the inner diffuser 29 or the downstream end plate 32 so that the support columns 45 for each of the plurality of lining members 40 are arranged at intervals in the circumferential direction Dc; and a second joining step S3 of joining the first end 45a of each of the support columns 45 to the inner diffuser 29 or the downstream end plate 32 so that the plurality of lining members 40 are arranged in the circumferential direction Dc and the plurality of lining members 40 are arranged in the circumferential direction Dc. and a second joining step S3 of joining each of the plurality of lining members 40 to the second end 45b of any one of the support columns 45 so that each of the members 40 extends from a position along a space outer surface that defines an edge of the radially inner side Dri of the diffuser space 26s in the inner diffuser 29, gradually toward the axial downstream side Dad as it moves toward the radially outer side Dro, to a position along a space side surface 32p that defines the exhaust space 30s in the downstream end plate 32. In the second joining step S3, the plurality of lining members 40 are not joined to the inner diffuser 29 or the downstream end plate 32.

[0109] In the exhaust chamber 25 modified by the modification method of this aspect, the occurrence of steam backflow can be suppressed and steam exhaust resistance can be reduced, similar to the exhaust chamber 25 of the first aspect. Furthermore, in the exhaust chamber 25 modified by the modification method of this aspect, the occurrence of welding distortion in the downstream end plate 32 and the inner diffuser 29 can be suppressed.

[0110] Furthermore, in the modification method of this aspect, the support columns 45 are first joined to the inner diffuser 29 or the downstream end plate 32, and then the lining member 40 is joined to the support columns 45 from the radially outer side Dro to the radially inner side Dri within the diffuser space 26s and the exhaust space 30s. Therefore, in this aspect, the lining member 40 can be easily joined to the support columns 45.

[0111] According to one aspect of the present disclosure, it is possible to reduce steam exhaust resistance and also to reduce welding distortion in the inner diffuser and the downstream end plate.

[0112] DESCRIPTION OF SYMBOLS 10a: First steam turbine section 10b: Second steam turbine section 11: Turbine rotor 12: Rotor shaft 13: Row of moving blades 13a: Last row of moving blades 17: Row of stator blades 18: Bearing 19: Steam inlet pipe 20: Casing 21: Body casing 25, 25a, 25b: Exhaust chamber 26: Diffuser 26s: Diffuser space 27: Outer diffuser 27p: Space side surface 29: Inner diffuser 29p: Space side surface 30: Exhaust casing 30s: Exhaust space 31: Exhaust port 32: Downstream end plate 32p: Space side surface 34: Upstream end plate 36: Outer peripheral plate 40: Lining member 41: Lining plate 41p: Space side surface 41pa: Anti-space side surface 41o: Outer edge 41i: Inner edge 41s: Side edge 42: Opening 43: Rib 43a: First rib 43b: Second rib 45: Support column 45a: First end 45b: Second end Co: Condenser Ar: Axis Da: Axial direction Dau: Axial upstream side Dad: Axial downstream side Dc: Circumferential direction Dr: Radial direction Dri: Radially inner side Dro: Radially outer side Dpu: Non-exhaust side Dpe: Exhaust side

Claims

1. An exhaust chamber of a steam turbine capable of directing steam flowing out from a final row of moving blades of a turbine rotor rotating about an axis to the outside, comprising: a diffuser forming a diffuser space into which the steam flowing out from the final row of moving blades can flow, the diffuser having an annular shape about the axis and gradually widening radially outward relative to the axis as it moves downstream of the axis; an exhaust casing having an exhaust port opening radially outward, communicating with the diffuser space, widening in a circumferential direction about the axis, and forming an exhaust space for directing the steam flowing in from the diffuser space to the exhaust port; a plurality of lining members arranged across the diffuser space and aligned in the circumferential direction; and support pillars provided for each of the plurality of lining members; wherein the diffuser has an inner diffuser having an annular cross section perpendicular to the axis and gradually widening radially outward relative to the axis as it moves downstream of the axis, defining a radially inner edge of the diffuser space; an exhaust casing having a downstream end plate that defines an axially downstream edge of the exhaust space, the downstream end plate extending in the circumferential direction and in a direction that includes a radial component relative to the axis; the radially inner edge of the downstream end plate being connected to the axially downstream edge of the inner diffuser; each of the plurality of lining members extending from a position along a space side surface that defines the radially inner edge of the diffuser space at the inner diffuser, gradually extending radially outward toward the axially downstream side, to a position along a space side surface that defines the exhaust space at the downstream end plate; a support pillar for each of the plurality of lining members having a first end and a second end, the first end of the support pillar being joined to the inner diffuser or the downstream end plate, and the second end of the support pillar being joined to any one of the plurality of lining members; and 2. An exhaust chamber according to claim 1, wherein the plurality of lining members are not in contact with the inner diffuser.

3. An exhaust chamber according to claim 1, wherein the plurality of lining members are not in contact with the downstream end plate.

4. An exhaust chamber according to claim 1, wherein the plurality of lining members are not in contact with each other.

5. An exhaust chamber according to claim 1, wherein the plurality of lining members are arranged on at least the non-exhaust side of the exhaust side where the exhaust port is located and the non-exhaust side opposite the exhaust side, with respect to the axis.

6. An exhaust chamber according to claim 1, wherein the plurality of lining members are arranged only on the non-exhaust side of the exhaust side where the exhaust port is located and the non-exhaust side opposite the exhaust side, with respect to the axis.

7. An exhaust chamber as described in claim 1, wherein, of the plurality of lining members arranged in the circumferential direction, the radial length of the lining member located on the non-exhaust side opposite the exhaust side where the exhaust port is located is longer than the radial length of the lining member located on the exhaust side than the lining member located on the non-exhaust side.

8. An exhaust chamber as claimed in claim 1, wherein the support pillar is cylindrical, and each of the plurality of lining members has a lining plate that extends from a position along the spatial side surface of the inner diffuser, gradually towards the downstream side of the axis as it moves radially outward, to a position along the spatial side surface of the downstream end plate, and a circular opening is formed in the lining plate, and the second end of the support pillar fits into the opening in the lining plate and is joined to the edge of the opening.

9. An exhaust chamber as claimed in claim 1, wherein each of the plurality of lining members comprises a lining plate extending from a position along the space side surface of the inner diffuser, gradually moving radially outward and downstream along the axis, to a position along the space side surface of the downstream end plate, and one or more ribs joined to the lining plate on the side opposite to the space side surface facing radially inward.

10. An exhaust chamber as claimed in claim 9, wherein the one or more ribs comprise a first rib arranged on one side in the circumferential direction and a second rib arranged on the other side in the circumferential direction, based on the joint position between the lining plate and the support pillar, and both the first rib and the second rib extend along the anti-space side surface so as to gradually move towards the downstream side of the axis as they move radially outwards.

11. An exhaust chamber according to claim 10, wherein the circumferential distance between the first rib and the second rib gradually increases toward the downstream side of the axis.

12. A steam turbine comprising: the exhaust chamber according to any one of claims 1 to 11; the turbine rotor; and a body casing covering the outer peripheral side of the turbine rotor.

13. A method for modifying an exhaust duct of a steam turbine capable of directing steam flowing out from the final row of moving blades of a turbine rotor rotating about its axis to the outside, wherein the exhaust duct comprises: a diffuser that forms a diffuser space into which steam flowing out from the final row of moving blades of a turbine rotor rotating about its axis can flow, the diffuser having an annular shape about the axis and gradually widening radially outward relative to the axis as it extends downstream along the axis; and an exhaust casing that has an exhaust port that opens radially outward, communicates with the diffuser space, widens circumferentially relative to the axis, and forms an exhaust space through which steam flowing in from the diffuser space is directed to the exhaust port; the diffuser has an annular cross section perpendicular to the axis and an inner diffuser that gradually widens radially outward relative to the axis as it extends downstream along the axis, defining a radially inner edge of the diffuser space relative to the axis; and the exhaust casing has a downstream end plate that determines the downstream edge of the exhaust space along the axis. the downstream end plate extends in the circumferential direction and in a direction including a radial component relative to the axis, and a radially inner edge of the downstream end plate is connected to an edge of the inner diffuser downstream of the axis, the method for modifying an exhaust chamber comprising: a preparation step of preparing a plurality of lining members and support posts for the plurality of lining members; a first joining step of joining, of first end portions and second end portions of the support posts, the first end portions to the inner diffuser or the downstream end plate so that the support posts for the plurality of lining members are arranged at intervals from each other in the circumferential direction; a second joining step of joining each of the plurality of lining members to the second end part of any one of the support columns so that the plurality of lining members are arranged in the circumferential direction and all of the plurality of lining members extend from a position along an outer surface of a space that defines the radially inner edge of the diffuser space at the inner diffuser, gradually toward the axial downstream side as they move radially outward, to a position along a space side surface that defines the exhaust space at the downstream end plate, wherein in the second joining step, the plurality of lining members are not joined to the inner diffuser or the downstream end plate.

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