Steam turbine and oil draining device

Abstract

This steam turbine comprises a rotor, a bearing, and an oil draining device. The oil draining device has an oil draining body formed in an annular shape, and a plurality of fin parts capable of coming into sliding contact with the outer peripheral surface of the rotor. The plurality of fin parts include a first fin part, a second fin part, a third fin part, and a fourth fin part that are arranged in the stated order starting from a position close to the bearing. The oil draining body opens between the third fin part and the fourth fin part in the axial direction and has a gas supply hole. In the third fin part and the fourth fin part, a fin side surface facing the axial direction is formed only by a flat surface extending in the radial direction from the inner surface to the distal end.

Description

Steam Turbine and Oil Separation Device

[0001] The present disclosure relates to a steam turbine and an oil separation device. This application claims priority from Japanese Patent Application No. 2025-024970 filed in Japan on February 19, 2025, the content of which is incorporated herein by reference.

[0002] The steam turbine includes a rotor (turbine rotor) disposed within a casing, a row of moving blades provided on the outer side in the radial direction of the rotor, and a row of stationary blades provided on the inner side in the radial direction of the casing. In such a steam turbine, the rotor is rotatably supported by bearings in a state lubricated with lubricating oil. Thereby, the rotor is rotatable with respect to the casing through the bearings in a state where friction is reduced.

[0003] In such a steam turbine, an oil separation device is arranged to suppress leakage of the lubricating oil used in the bearings. As the structure of such an oil separation device, for example, Patent Document 1 describes a structure in which an air pipe for supplying air to an oil separation seal portion provided with seal fins is provided.

[0004] Japanese Patent Application Laid-Open No. 2002-30903

[0005] By the way, the oil separation device of the steam turbine as described above has a structure in which a plurality of fins formed as separate members are combined, a structure for suppressing intrusion of oil, etc., and has a complicated structure. Therefore, it is required to maintain appropriate oil separation performance with a simple structure.

[0006] The present disclosure provides a steam turbine and an oil separation device capable of simplifying the structure while maintaining the oil separation performance.

[0007] The steam turbine according to this disclosure comprises a rotor rotatable about an axis, a bearing that rotatably supports the rotor, and an oil cutter device arranged to cover the outer circumferential surface of the rotor and to suppress leakage of lubricating oil from the bearing, wherein the oil cutter device has an oil cutter body whose inner surface is arranged radially away from the outer circumferential surface of the rotor and centered on the axis, and is formed in an annular shape around the axis so as to surround the rotor, and a plurality of fin portions that protrude radially inward from the inner surface of the oil cutter body and whose tips are capable of sliding contact with the outer circumferential surface of the rotor, wherein the plurality of fin portions extend along the axis The oil cutter body has a first fin section, a second fin section, a third fin section, and a fourth fin section, which are arranged apart from each other in the axial direction and are located in order from the position closest to the bearing in the axial direction. The oil cutter body has a gas supply hole that opens on its inner surface in the axial direction so as to communicate with the space between the third fin section and the fourth fin section, extends radially from the inner surface toward the outer surface, and is capable of supplying exhaust gas toward the outer circumferential surface of the rotor. In the third fin section and the fourth fin section, the fin side surface facing the axial direction is formed only by a plane that extends radially from the inner surface to the tip.

[0008] Furthermore, the oil cut-off device according to this disclosure is an oil cut-off device that can be arranged to cover the outer circumferential surface of a steam turbine rotor and suppresses the leakage of lubricating oil, and comprises an oil cut-off body formed in an annular shape with respect to an axis, and a plurality of fin portions that protrude radially inward from the inner surface of the oil cut-off body toward the axis, with their tips sliding in contact with the outer circumferential surface of the rotor, and the plurality of fin portions are arranged apart from each other in the axial direction in which the axis extends, and are arranged in order from one side in the axial direction as a first fin portion, a second fin portion, a third fin portion, and a fourth fin portion The oil cutter body has a gas supply hole that opens on its inner surface in the axial direction to communicate with the space between the third fin portion and the fourth fin portion, extends radially from the outer surface of the oil cutter body toward the inner surface, and is capable of supplying exhaust gas. The third fin portion and the fourth fin portion have fin sides facing the axial direction formed by a plane that extends radially from the inner surface to the tip, and the oil cutter body has a structure that can be divided vertically into upper and lower halves with a virtual horizontal plane passing through the axis as the dividing surface.

[0009] The steam turbine and oil-cutting device of this disclosure allow for a simplified structure while maintaining oil-cutting performance.

[0010] This is a schematic diagram showing the overall configuration of the steam turbine according to this embodiment. This is a cross-sectional view showing the oil cut-off device. This is a schematic diagram of the oil cut-off device viewed from the axial direction.

[0011] The following describes embodiments for implementing the steam turbine 1 and oil cut-off device 8 according to this disclosure, with reference to the attached drawings. However, this disclosure is not limited to these embodiments.

[0012] (Steam Turbine) As shown in Figure 1, the steam turbine 1 of this embodiment includes a rotor 2 that is rotatable about an axis O, a casing 3 that rotatably covers the rotor 2, a stationary blade 4 fixed to the casing 3, and a bearing base 5 that supports the rotor 2.

[0013] For the purposes of the following explanation, the direction in which the axis O extends will be referred to as the axial direction Da. One side of the axial direction Da will be the first side (upstream side in the steam flow direction of the steam turbine 1) Da1, and the other side of the axial direction Da will be the second side (downstream side in the steam flow direction of the steam turbine 1) Da2. Furthermore, the radial direction of the rotor 2 with respect to the axis O will simply be referred to as the radial direction Dr. The side of this radial direction Dr that approaches the axis O will be referred to as the inner side Dri of the radial direction Dr, and the side of this radial direction Dr opposite to the inner side Dri will be referred to as the outer side Dr of the radial direction Dr. Furthermore, the circumferential direction of the rotor 2 centered on the axis O will simply be referred to as the circumferential direction Dc.

[0014] (Rotor) As shown in Figure 1, the rotor 2 has a rotor shaft 21 and a plurality of rotor blade rows 22A.

[0015] The rotor shaft 21 is rotatable about axis O relative to the casing 3. The rotor blades 22 are fixed to the rotor shaft 21, arranged in the circumferential direction Dc relative to the rotor shaft 21. Multiple rotor blades 22 arranged in the circumferential direction Dc constitute a single rotor blade row 22A. Multiple rotor blade rows 22A are arranged at intervals in the axial direction Da of the rotor shaft 21.

[0016] (Casing) The casing 3 covers the rotor 2 on its radially outer side Dr. The casing 3 is formed to cover the rotor shaft 21 and the multiple rotor blades 22 from their radially outer sides Dr. A flow path for steam to circulate is formed inside the casing 3. The casing 3 is structured to be separable into upper and lower parts with respect to a horizontal plane passing through the axis O.

[0017] (Stator vanes) The stator vanes 4 are fixed to the casing 3. The stator vanes 4 are positioned at the first side Da1, which is upstream of the rotor blades 22 in the axial direction Da. Multiple stator vanes 4 arranged in the circumferential direction Dc constitute one stator vane row 4A. Multiple stator vane rows 4A are arranged at intervals in the axial direction Da of the rotor shaft 21.

[0018] (Bearing base) The bearing base 5 is installed on the floor surface and supports both ends of the rotor 2. The bearing base 5 supports the rotor 2 outside the casing 3. The bearing base 5 of this embodiment has a first bearing base 51 and a second bearing base 52.

[0019] The first bearing base 51 supports the first side Da1 end of the rotor 2 in the axial direction Da. The first bearing base 51 is positioned on the floor surface of the casing 3 at the first side Da1 in the axial direction Da.

[0020] The second bearing base 52 supports the end of the rotor 2 on the second side Da2 in the axial direction Da. The second bearing base 52 is located on the opposite side of the casing 3 from the first bearing base 51 in the axial direction Da. The second bearing base 52 is located on the floor surface on the second side Da2 in the axial direction Da relative to the casing 3.

[0021] Furthermore, the bearing base 5 (first bearing base 51 and second bearing base 52) includes a bearing 6, a bearing casing 7, and an oil draining device 8.

[0022] (Bearing) The bearing 6 rotatably supports the rotor 2. In this embodiment, the bearing 6 rotatably supports the rotor shaft 21 about the axis O. The bearing 6 is fixed in a state where it is housed within the bearing casing 7. The position of the bearing 6 in the axial direction Da is set to be separate from (and not overlapping with) the position of the casing 3 in the axial direction Da. In other words, the bearing 6 is located outside the casing 3 in the axial direction Da. The bearing 6 has a structure that can be divided vertically with respect to a horizontal plane passing through the axis O. The bearing 6 has a first bearing 61 and a second bearing 62.

[0023] The first bearing 61 is positioned on the first bearing base 51. The first bearing 61 supports the rotor 2 using lubricating oil. The first bearing 61 in this embodiment has a journal bearing 66 and a thrust bearing 67 that utilize lubricating oil. The journal bearing 66 receives a radial load Dr acting on the rotor shaft 21. The thrust bearing 67 receives an axial load Da acting on the rotor shaft 21. The thrust bearing 67 is positioned on one side of the journal bearing 66 in the axial direction Da.

[0024] The second bearing 62 is positioned on the second bearing base 52. The second bearing 62 supports the rotor 2 using lubricating oil. The second bearing 62 in this embodiment has a journal bearing 66 that utilizes lubricating oil. The journal bearing 66 of the second bearing 62 is the same as the journal bearing 66 of the first bearing 61.

[0025] (Bearing Casing) The bearing casing 7 covers a portion of the rotor 2 from the outside Dr in the radial direction Dr. The bearing casing 7 houses the bearing 6 and the oil cut-off device 8 inside. The bearing 6 and the oil cut-off device 8 are fixed to the bearing casing 7 at a distance from each other in the axial direction Da. The bearing casing 7 has a structure that can be divided vertically with respect to a horizontal plane passing through the axis O. The bearing casing 7 is connected to the casing 3 via a flexible plate 79. The bearing casing 7 of this embodiment has a first bearing casing 71 and a second bearing casing 72. The first bearing casing 71 is positioned on the first bearing base 51. The first bearing casing 71 houses the first bearing 61 inside. The second bearing casing 72 is positioned on the second bearing base 52. The second bearing casing 72 houses the second bearing 62 inside.

[0026] (Oil Cut-off Device) The oil cut-off device 8 suppresses leakage of lubricating oil from the bearing 6. The oil cut-off device 8 is positioned to cover the outer circumferential surface of the rotor 2. The oil cut-off device 8 is positioned on the first bearing base 51 and the second bearing base 52. In the axial direction Da, the oil cut-off device 8 is positioned close to the casing 3 relative to the bearing 6. As shown in Figure 3, the oil cut-off device 8 has a structure that can be divided vertically with respect to a horizontal plane passing through the axis O. Here, in order to explain in detail, the oil cut-off device 8 positioned on the first bearing base 51 will be given as an example. The oil cut-off device 8 positioned on the second bearing base 52 has the same structure as the oil cut-off device 8 positioned on the first bearing base 51, except for the orientation in which it is installed.

[0027] As shown in Figure 2, the oil draining device 8 of this embodiment has an oil draining body 81, a plurality of fin sections 82, and a guide plate 83.

[0028] The oil cutter body 81 is formed in an annular shape with axis O as the center so as to surround the rotor 2. The oil cutter body 81 is structured to be separable vertically with respect to a horizontal plane passing through axis O. The oil cutter body 81 of this embodiment has an inner surface 811, an outer surface 812, a body side surface 813, and an oil cutter position determination part 817.

[0029] The inner surface 811 is a smooth surface in the oil cutter body 81 that faces inward Dr in the radial direction Dr. The inner surface 811 is an annular curved surface centered on axis O. The inner surface 811 extends in the axial direction Da. The inner surface 811 is positioned away from the outer circumferential surface of the rotor shaft 21 in the radial direction Dr. The inner surface 811 faces the outer circumferential surface of the rotor shaft 21 in the radial direction Dr.

[0030] The outer surface 812 is a smooth surface on the oil cutter body 81 that faces outward in the radial direction Dr, opposite to the inner surface 811. The outer surface 812 is an annular curved surface centered on axis O. The outer surface 812 extends in the axial direction Da, parallel to the inner surface 811. The outer surface 812 is in contact with the casing contact surface 75 of the bearing casing 7. The casing contact surface 75 is a surface on the bearing casing 7 that faces inward in the radial direction Dr, so as to contact the outer surface 812 of the oil cutter body 81. The outer surface 812 is formed as a surface without any irregularities other than the oil cutter position determination portion 817. In other words, only the oil cutter position determination portion 817 is formed on the outer surface 812 as a protrusion projecting in the radial direction Dr.

[0031] The oil cut position determination section 817 restricts the axial position Da of the oil cut device 8 relative to the bearing casing 7. The oil cut position determination section 817 is fitted into the casing position determination section 76 with its movement in the axial direction Da restricted. Here, the casing position determination section 76 is the region that engages with the oil cut position determination section 817. The casing position determination section 76 is formed on the casing contact surface 75. The casing position determination section 76 is recessed radially Dr relative to the casing contact surface 75. The casing position determination section 76 is formed as a rectangular cross-sectional recess that is recessed radially outward Dr from the casing contact surface 75. In other words, the bearing casing 7 has a casing contact surface 75 and a casing position determination section 76 as a structure for fixing the oil cut device 8.

[0032] The oil cut position determination portion 817 protrudes radially in the Dr direction relative to the outer surface 812. The oil cut position determination portion 817 is formed as a rectangular cross-sectional convex portion that protrudes from the outer surface 812 toward the inner side Dr in the radial direction Dr. The axial length Da of the oil cut position determination portion 817 is set to be approximately the same as the axial length Da of the casing position determination portion 76. Specifically, the axial length Da of the oil cut position determination portion 817 is set based on the amount of axial movement Da of the oil cut device 8 that is permissible relative to the bearing casing 7.

[0033] The main body side surface 813 is a smooth surface facing the axial direction Da on the oil cutter body 81. The main body side surfaces 813 are arranged in pairs as planes facing the first side Da1 and the second side Da2 in the axial direction Da, respectively. The main body side surfaces 813 extend radially Dr so as to connect the inner surface 811 and the outer surface 812.

[0034] Multiple fin portions 82 protrude from the inner surface 811 of the oil cutter body 81 toward the inner surface Dr in the radial direction Dr. The tips of the multiple fin portions 82 are capable of sliding contact with the outer circumferential surface of the rotor 2. In other words, the multiple fin portions 82 form a labyrinth seal-like structure that seals the space between the outer surface 812 and the outer circumferential surface of the rotor 2. Each of the multiple fin portions 82 has a pair of fin side surfaces 820 facing the axial direction Da. The fin side surfaces 820 in this embodiment do not have any irregularities. The fin side surface 820 is formed as a plane that extends straight in the vertical direction Dv from the inner surface 811 to the tip. Note that the fin side surface 820 is not limited to being a plane that extends perpendicular to the axis O, but may be inclined with respect to the axis O as long as it is a smooth surface without irregularities. The multiple fin portions 82 are not detachable from the oil cutter body 81. The multiple fin portions 82 are formed as an integral structure with the oil cutter body 81 by machining a single component. In other words, the multiple fin portions 82 are made of the same material as the oil cutter body 81 and are not connected by welding or other adhesives or fixing members. The multiple fin portions 82 in this embodiment have a first fin portion 821, a second fin portion 822, a third fin portion 823, and a fourth fin portion 824.

[0035] The first fin portion 821, the second fin portion 822, the third fin portion 823, and the fourth fin portion 824 are arranged apart from each other in the axial direction Da. The first fin portion 821, the second fin portion 822, the third fin portion 823, and the fourth fin portion 824 are positioned in order from the position closest to the bearing 6 in the axial direction Da.

[0036] The first fin portion 821 is positioned closest to the bearing 6 (journal bearing 66) in the axial direction Da among the multiple fin portions 82. The fin side surface 820 of the first side Da1 of the first fin portion 821 in the axial direction Da is formed to be on the same plane as the main body side surface 813 facing the first side Da1 in the axial direction Da. The fin side surface 820 of the second side Da2 of the first fin portion 821 in the axial direction Da is formed as a plane that extends straight in the vertical direction Dv from the inner surface 811 to the tip. Therefore, in the first fin portion 821, the fin side surfaces 820 on both sides in the axial direction Da are formed only by planes that extend straight in the vertical direction Dv from the inner surface 811 to the tip.

[0037] The second fin portion 822 is positioned at a distance from the first fin portion 821 on the second side Da2 in the axial direction Da. The fin sides 820 on both sides of the second fin portion 822 in the axial direction Da are formed only by planes that extend straight in the vertical direction Dv from the inner surface 811 to the tip. The length of the second fin portion 822 in the radial direction Dr (distance from the inner surface 811 to the tip) is the same as the length of the first fin portion 821 in the radial direction Dr. The width of the second fin portion 822 in the axial direction Da (width of the widest part in the axial direction Da) is the same as the width of the first fin portion 821 in the axial direction Da.

[0038] The tips of the first fin portion 821 and the second fin portion 822 are capable of sliding contact with a projection 211 that partially protrudes radially outward in the rotor shaft 21. The width of the projection 211 in the axial direction Da is larger than the width of the first fin portion 821 and the second fin portion 822 in the axial direction Da. Specifically, the width of the projection 211 in the axial direction Da is larger than the maximum value of the thermal expansion of the rotor 2 in the axial direction Da due to the operation of the steam turbine 1. The width of the first fin portion 821 and the second fin portion 822 in the axial direction Da is, for example, several millimeters.

[0039] The third fin portion 823 is positioned away from the second fin portion 822 on the second side Da2 in the axial direction Da. In other words, in the axial direction Da, the second fin portion 822 is positioned between the first fin portion 821 and the third fin portion 823. The fin sides 820 on both sides of the third fin portion 823 in the axial direction Da are formed only by planes that extend straight in the vertical direction Dv from the inner surface 811 to the tip.

[0040] The fourth fin portion 824 is positioned away from the third fin portion 823 on the second side Da2 in the axial direction Da. Among the multiple fin portions 82, the fourth fin portion 824 is positioned furthest from the bearing 6 (journal bearing 66) in the axial direction Da. The fin side surface 820 of the fourth fin portion 824 on the second side Da2 in the axial direction Da is formed to be in the same plane as the main body side surface 813 facing the second side Da2 in the axial direction Da. The fin side surface 820 of the fourth fin portion 824 on the first side Da1 in the axial direction Da is formed as a plane that extends straight in the vertical direction Dv from the inner surface 811 to the tip. Therefore, in the fourth fin portion 824, the fin side surfaces 820 on both sides in the axial direction Da are formed only by planes that extend straight in the vertical direction Dv from the inner surface 811 to the tip, similar to the other fin portions 82. The length of the fourth fin portion 824 in the radial direction Dr is the same as the length of the third fin portion 823 in the radial direction Dr. The length of the fourth fin portion 824 in the radial direction Dr is shorter than the lengths of the first fin portion 821 and the second fin portion 822 in the radial direction Dr. In other words, the fourth fin portion 824 and the third fin portion 823 extend to a position in the axial direction Da that overlaps with the projection portion 211. The tips of the fourth fin portion 824 and the third fin portion 823 are capable of sliding contact with the outer circumferential surface of the rotor shaft 21, rather than with the projection portion 211.

[0041] Furthermore, the oil cutter body 81 also has a gas supply hole 814, a gas discharge hole 815, and a discharge hole 816.

[0042] The gas supply hole 814 is capable of ejecting sealing gas (for example, nitrogen gas) toward the outer circumferential surface of the rotor 2. The gas supply hole 814 is formed to communicate with the space between the outer circumferential surface and the inner surface 811 of the rotor 2. The gas supply hole 814 opens on the inner surface 811. The gas supply hole 814 extends radially Dr from the outer surface 812 toward the inner surface 811. The gas supply hole 814 communicates with the space between the third fin portion 823 and the fourth fin portion 824 in the axial direction Da. In other words, the gas supply hole 814 opens on the inner surface 811 between the third fin portion 823 and the fourth fin portion 824 in the axial direction Da. The gas supply hole 814 opens at an intermediate position between the third fin portion 823 and the fourth fin portion 824 in the axial direction Da. Furthermore, as shown in Figure 3, the gas supply hole 814 in this embodiment extends linearly only in the vertical direction Dv from the inner surface 811 to the outer surface 812 at the apex (uppermost end) of the oil cutter body 81 in the vertical direction Dv. Therefore, the gas supply hole 814 is one of the through holes that penetrate the oil cutter body 81.

[0043] As shown in Figure 2, the gas discharge hole 815 is configured to discharge the sealing gas supplied from the gas supply hole 814 toward the outer circumferential surface of the rotor 2 to the outside of the bearing base 5 (oil cut-off device 8). The gas discharge hole 815 is formed to communicate with the space between the outer circumferential surface and the inner surface 811 of the rotor 2. The gas discharge hole 815 opens on the inner surface 811. The gas discharge hole 815 extends radially in the direction Dr from the inner surface 811 toward the outer surface 812. The gas discharge hole 815 communicates with the space between the third fin portion 823 and the fourth fin portion 824 in the axial direction Da. In other words, the gas discharge hole 815 opens on the inner surface 811 between the third fin portion 823 and the fourth fin portion 824 in the axial direction Da. The gas discharge hole 815 opens at a position closer to the fourth fin portion 824 than to the third fin portion 823 in the axial direction Da. Furthermore, the gas discharge hole 815 in this embodiment extends linearly only in the vertical direction Dv from the inner surface 811 to the outer surface 812 at the lowest end of the oil drain body 81. The gas discharge hole 815 is one of the through holes that penetrate the oil drain body 81.

[0044] The discharge hole 816 allows the lubricating oil accumulated in the space between the outer peripheral surface of the rotor 2 and the inner surface 811 to be discharged to the outside of the bearing base 5 (oil drain device 8). The discharge hole 816 is formed so as to communicate with the space between the outer peripheral surface of the rotor 2 and the inner surface 811. The discharge hole 816 opens at the inner surface 811. The discharge hole 816 is formed at a position axially distant from the gas supply hole 814 in the axial direction Da. The discharge hole 816 extends in the radial direction Dr from the inner surface 811 toward the outer surface 812. As shown in FIG. 3 when viewed in the axial direction Da, the discharge hole 816 of the present embodiment opens only at the inner surface 811 at the lowermost end in the vertical direction Dv of the oil drain body 81 so as to overlap with the gas discharge hole 815. The discharge hole 816 has a first discharge hole 816A and a second discharge hole 816B that are axially separated from each other.

[0045] The first discharge hole 816A discharges the lubricating oil accumulated in the space between the first fin portion 82‎1 and the second fin portion 82‎2. The first discharge hole 816A communicates with the space between the first fin portion 82‎1 and the second fin portion 82‎2 in the axial direction Da. That is, the first discharge hole 816A opens at the inner surface 811 between the first fin portion 82‎1 and the second fin portion 82‎2 in the axial direction Da. Further, the first discharge hole 816A of the present embodiment linearly extends only in the vertical direction Dv from the inner surface 811 at the lowermost end of the oil drain body 81 to the outer surface 812. The first discharge hole 816A is one of the through holes penetrating the oil drain body 81.

[0046] The second discharge hole 816B discharges the lubricating oil accumulated in the space between the second fin portion 822 and the third fin portion 823. The second discharge hole 816B communicates with the space between the second fin portion 822 and the third fin portion 823 in the axial direction Da. In other words, the second discharge hole 816B opens on the inner surface 811 between the first fin portion 82 and the third fin portion 823 in the axial direction Da. The second discharge hole 816B is connected to the first discharge hole 816A. In this embodiment, the second discharge hole 816B extends straight in the vertical direction Dv from the inner surface 811 at the lowest end in the vertical direction Dv of the oil cutter body 81, then bends at a right angle and extends in the axial direction Da to the side surface 813 of the body. In other words, the second discharge hole 816B is formed by connecting a recess extending linearly in the vertical direction Dv from the inner surface 811 and a recess extending linearly in the axial direction Da from the side surface 813 of the body. The second discharge hole 816B is one of the through holes that penetrate the oil cutter body 81.

[0047] The guide plate 83 suppresses splashing of lubricating oil discharged from the opening 812 on the outer surface of the discharge hole 816. In other words, the guide plate 83 prevents lubricating oil discharged from the discharge hole 816 from scattering. The guide plate 83 is fixed to the oil cutter body 81. The length of the circumferential direction Dc of the guide plate 83 is such that it can cover the opening 812 on the outer surface of the first discharge hole 816A, and is sized to allow the attachment of a fixing member for fixing it to the oil cutter body 81. For example, as shown in Figure 3, when viewed from the axial direction Da, the guide plate 83 covers only a range of ±30° or less centered on the axis O with respect to the discharge hole 816. When viewed from the axial direction Da, it is preferable that the length of the circumferential direction Dc of the guide plate 83 be as short as possible. The guide plate 83 of this embodiment has a guide body 831 and a shielding plate portion 832.

[0048] The guide body 831 is formed in a plate shape so as to project downward in the vertical direction Dv with respect to the outer surface 812 of the oil separation body 81. That is, in the vertical direction Dv, the lower end of the guide body 831 is arranged at a position separated downward from the outer surface 812. The guide body 831 is fixed to the body side surface 813 facing the first side Da1 in the axial direction Da of the oil separation body 81. The guide body 831 is fixed to the oil separation body 81 via a fixing member such as a bolt. At that time, it is preferable that the fixing member fixes the guide body 831 and the oil separation body 81 by being inserted into the opening of the second discharge hole 816B formed in the body side surface 813.

[0049] The shielding plate portion 832 is formed in a plate shape so as to extend in the axial direction Da from the end portion of the guide body 831 separated from the outer surface 812 in the vertical direction Dv. The shielding plate portion 832 is arranged so as to cover the opening of the outer surface 812 of the first discharge hole 816A from the outside Dro.

[0050] (Method for replacing the oil separation device) When removing the above-described oil separation device 8, first, in the bearing base 5 with the rotor 2 inserted therethrough, the upper half of the bearing casing 7 is removed from the lower half of the bearing casing 7. Thereafter, the upper half of the oil separation body 81 placed on the lower half of the bearing casing 7 is removed. Further, the lower half of the oil separation body 81 in a state where the upper half has been removed is rotated about the axis O with respect to the lower half of the bearing casing 7, so as to be moved upward in the vertical direction Dv with respect to the rotor 2 main body. In this state, the lower half of the oil separation body 81 placed on the rotor shaft 21 is removed. Thereby, the oil separation device 8 can be removed without moving the rotor 2. Further, when attaching a new oil separation device 8, the above-described removal procedure is performed in reverse. Thereby, the oil separation device 8 can be replaced without moving the rotor 2.

[0051] (Effects) In the steam turbine 1 with the above configuration, the third fin portion 823 and the fourth fin portion 824 have fin side surfaces 820 facing the axial direction Da formed only by a plane extending radially Dr from the inner surface 811 to the tip. In particular, in this embodiment, in all fin portions 82, including the first fin portion 821 and the second fin portion 822, the fin side surfaces 820 are formed only by a plane extending straight radially Dr from the inner surface 811 to the tip. As a result, the shape of the fin portion 82 can be simplified, and the machinability of the fin portion 82 can be improved without impairing the performance of the fin portion 82. This makes it possible to simplify the structure while maintaining oil drainage performance.

[0052] Furthermore, the multiple fin sections 82 are formed as a single structure that cannot be detached from the oil-cutting body 81 by machining them from a single material. Therefore, there is no need to form fixing members or fixing structures such as welding to fix the multiple fin sections 82 to the oil-cutting body 81. Consequently, the number of parts and shape of the oil-cutting device 8 can be reduced and simplified. This allows for a simpler structure while maintaining oil-cutting performance.

[0053] Furthermore, the outer surface 812 of the oil cutter body 81 has only the oil cutter position determination portion 817 formed as a convex portion, and is formed as a plane extending in the inner axis direction Da of the uneven surface. As a result, the number of processed parts on the outer surface 812 of the oil cutter body 81 is reduced, and the shape of the oil cutter body 81 can be simplified. This makes it possible to simplify the structure while maintaining oil cutter performance.

[0054] Furthermore, the first discharge hole 816A and the second discharge hole 816B are formed to open only on the inner surface 811 at the lowest end in the vertical direction Dv of the oil cutter body 81. Lubricating oil accumulated in the space between the pair of fin portions 82, such as the first fin portion 821 and the second fin portion 822 or the second fin portion 822 and the third fin portion 823, the outer circumferential surface of the rotor 2, and the inner surface 811 is drawn by gravity and accumulates facing the inner surface 811 at the lowest end in the vertical direction Dv of the oil cutter body 81. Therefore, by opening on the inner surface 811 at the lowest end in the vertical direction Dv of the oil cutter body 81, the lubricating oil can be flowed into the first discharge hole 816A and the second discharge hole 816B with high precision and discharged. Furthermore, by having the first discharge hole 816A and the second discharge hole 816B open only on the inner surface 811 at the lowest end, the number of locations where through holes for discharging the lubricating oil can be formed is reduced. Therefore, while ensuring the performance of the first discharge hole 816A and the second discharge hole 816B, the time and cost required to process the first discharge hole 816A and the second discharge hole 816B can be reduced.

[0055] Furthermore, when viewed from the axial direction Da, the guide plate 83 covers only a range of ±30° around the axis O, with the first discharge hole 816A as the reference point. In other words, the shape of the guide plate 83 can be kept small. Therefore, the time and cost of manufacturing the guide plate 83 can be reduced while ensuring the performance of the guide plate 83.

[0056] Furthermore, the gas supply hole 814, the gas discharge hole 815, and the first discharge hole 816A are formed to extend linearly only in the vertical direction Dv. The second discharge hole 816B is formed by connecting a recess extending linearly in the vertical direction Dv from the inner surface 811 and a recess extending linearly in the axial direction Da from the side surface 813 of the main body. Therefore, all through holes penetrating the oil cutter body 81 are formed only by holes extending linearly with respect to the axial direction Da and the radial direction Dr. In other words, all through holes penetrating the oil cutter body 81 are not formed by holes that are oblique to the axial direction Da or the radial direction Dr, or by curved holes. As a result, the time and cost of machining the through holes penetrating the oil cutter body 81 can be reduced.

[0057] (Other Embodiments) Although embodiments of the present disclosure have been described in detail above with reference to the drawings, the specific configuration is not limited to these embodiments and may include design changes and the like that do not depart from the gist of the present disclosure.

[0058] For example, the steam turbine 1 is not limited to a structure in which oil-cutting devices 8 of the same structure are arranged on the first bearing base 51 and the second bearing base 52, as in this embodiment. Oil-cutting devices 8 of different structures may be arranged on the first bearing base 51 and the second bearing base 52.

[0059] <Note> The steam turbine 1 described in the embodiment can be understood, for example, as follows.

[0060] (1) The steam turbine 1 according to the first embodiment comprises a rotor 2 that is rotatable about an axis O, a bearing 6 that rotatably supports the rotor 2, and an oil cut-off device 8 that is arranged to cover the outer circumferential surface of the rotor 2 and suppresses leakage of lubricating oil from the bearing 6, wherein the oil cut-off device 8 has an inner surface 811 that is spaced apart from the outer circumferential surface of the rotor 2 in the radial direction Dr about the axis O, and is formed in an annular shape about the axis O so as to surround the rotor 2, and has a plurality of fin portions 82 that protrude from the inner surface 811 of the oil cut-off body 81 toward the inner Dr in the radial direction Dr, and whose tips are capable of sliding contact with the outer circumferential surface of the rotor 2, wherein the plurality of fin portions 82 are arranged in the axial direction Da in which the axis O extends The oil cutter body 81 has a first fin portion 821, a second fin portion 822, a third fin portion 823, and a fourth fin portion 824, which are spaced apart and located in order from the position closest to the bearing 6 in the axial direction Da. The oil cutter body 81 has a gas supply hole 814 that opens on the inner surface 811 so as to communicate with the space between the third fin portion 823 and the fourth fin portion 824 in the axial direction Da, extends radially Dr from the inner surface 811 toward the outer surface 812, and can supply exhaust gas toward the outer circumferential surface of the rotor 2. In the third fin portion 823 and the fourth fin portion 824, the fin side surface 820 facing the axial direction Da is formed only by a plane that extends radially Dr from the inner surface 811 to the tip.

[0061] With this configuration, the shape of the fin portion 82 can be simplified, and the machinability of the fin portion 82 can be improved without impairing its performance. As a result, the structure can be simplified while maintaining oil drainage performance.

[0062] (2) The steam turbine 1 according to the second embodiment is the steam turbine 1 of (1), wherein the plurality of fin portions 82 are not detachable from the oil cutter body 81 and are formed as an integral structure with the oil cutter body 81 by machining a single member.

[0063] With this configuration, there is no need to form fixing members or fixing structures such as welding to fix the multiple fin sections 82 and the oil-cutting body 81. Therefore, the number of parts and shape of the oil-cutting device 8 can be reduced and simplified. As a result, the structure can be further simplified while maintaining oil-cutting performance.

[0064] (3) The steam turbine 1 according to the third embodiment is the steam turbine 1 of (1) or (2), further comprising a bearing casing 7 that covers a part of the rotor 2 from the outer side Dr in the radial direction Dr and houses the bearing 6 and the oil cut-off device 8, wherein the bearing casing 7 has a casing contact surface 75 that contacts the outer surface 812 of the oil cut-off body 81 and a casing position determination portion 76 that is recessed in the radial direction Dr relative to the casing contact surface 75, the oil cut-off body 81 has an oil cut-off position determination portion 817 that protrudes in the radial direction Dr relative to the outer surface 812 so that it is fitted into the casing position determination portion 76 with its movement in the axial direction Da restricted, the outer surface 812 is a plane that extends in the axial direction Da and has only the oil cut-off position determination portion 817 formed as a convex portion that protrudes in the radial direction Dr.

[0065] With this configuration, the number of machining points on the outer surface 812 of the oil drain body 81 is reduced, and the shape of the oil drain body 81 can be simplified. As a result, the structure can be further simplified while maintaining oil draining performance.

[0066] (4) The steam turbine 1 according to the fourth embodiment is any one of the steam turbine 1 of (1) to (3), wherein the oil cutter body 81 has an inner surface 811 that opens in the axial direction Da so as to communicate with the space between the first fin portion 821 and the second fin portion 822, and has a discharge hole 816 that extends downward in the vertical direction Dv from the inner surface 811 and is connected to the outside, and the discharge hole 816 is formed to open only at the inner surface 811 at the lowest end of the oil cutter body 81 in the vertical direction Dv.

[0067] With this configuration, the lubricating oil accumulated in the space between the fin portion 82, the outer circumferential surface of the rotor 2, and the inner surface 811 is drawn by gravity to the inner surface 811 at the lowest end of the oil cutter body 81 in the vertical direction Dv. Therefore, because the oil cutter body 81 has an opening at the inner surface 811 at the lowest end of the vertical direction Dv, the lubricating oil can be flowed into the discharge hole 816 with high precision and discharged. Furthermore, because the discharge hole 816 is opened only at the lowest end of the inner surface 811, the number of through holes required for discharging the lubricating oil can be reduced. Thus, the performance of the discharge hole 816 can be ensured while reducing the time and cost required to manufacture the discharge hole 816.

[0068] (5) The steam turbine 1 according to the fifth embodiment is the steam turbine 1 of (4), wherein the oil cut-off device 8 further comprises a guide plate 83 fixed to the oil cut-off body 81 and suppressing splashing of the lubricating oil discharged from the opening of the outer surface 812 of the discharge hole 816, the guide plate 83 having a guide body 831 fixed to the body side 813 of the oil cut-off body 81 facing the axial direction Da and formed in the shape of a plate so as to protrude downward in the vertical direction Dv relative to the outer surface 812, and a shielding plate portion 832 arranged so as to cover the opening of the outer surface 812 of the discharge hole 816 from the outside Do and formed in the shape of a plate so as to extend in the axial direction Da from the end of the guide body 831 which is separated in the vertical direction Dv relative to the outer surface 812, the guide plate 83 covers only a range of ±30° centered on the axis O with respect to the discharge hole 816 when viewed from the axial direction Da.

[0069] This configuration allows the shape of the guide plate 83 to be kept small. Therefore, the time and cost of processing the guide plate 83 can be reduced while ensuring the performance of the guide plate 83.

[0070] (6) The steam turbine 1 according to the sixth embodiment is any one of the steam turbines 1 from (1) to (5), wherein the through hole penetrating the oil cutter body 81 extends linearly with respect to the axial direction Da or the radial direction Dr.

[0071] With this configuration, all of the through holes penetrating the oil cutter body 81 are formed only by holes that extend linearly with respect to the axial direction Da and the radial direction Dr. In other words, none of the through holes penetrating the oil cutter body 81 are formed by holes that are oblique or curved with respect to the axial direction Da or the radial direction Dr. As a result, the time and cost of machining the through holes penetrating the oil cutter body 81 can be reduced.

[0072] (7) The oil cut-off device 8 according to the sixth embodiment is an oil cut-off device 8 that can be arranged to cover the outer circumferential surface of the rotor 2 of the steam turbine 1 and suppresses leakage of lubricating oil, and has an annular oil cut-off body 81 formed around an axis O, and a plurality of fin portions 82 that protrude from the inner surface 811 of the oil cut-off body 81 toward the inner Dri in the radial direction Dr centered on the axis O, and whose tips are capable of sliding contact with the outer circumferential surface of the rotor 2, and the plurality of fin portions 82 are arranged apart from each other in the axial direction Da extending from the axis O, and have a first fin portion 821, a second fin portion 822, a third fin portion 823, and a fourth fin portion 824 located in order from one side of the axial direction Da The oil cutter body 81 has an opening on its inner surface 811 that communicates with the space between the third fin portion 823 and the fourth fin portion 824 in the axial direction Da, and has a gas supply hole 814 that extends radially Dr from the outer surface 812 toward the inner surface 811 toward the inner surface 811 and can supply exhaust gas. The third fin portion 823 and the fourth fin portion 824 have a fin side surface 820 facing the axial direction Da formed by a plane that extends radially Dr from the inner surface 811 toward the tip, and the oil cutter body 81 is structured to be divisible into upper and lower parts in the vertical direction Dv with a virtual horizontal plane passing through the axis O as the dividing surface.

[0073] With this configuration, the shape of the fin portion 82 can be simplified, and the machinability of the fin portion 82 can be improved without impairing its performance. As a result, the structure can be simplified while maintaining oil drainage performance.

[0074] The steam turbine and oil-cutting device of this disclosure allow for a simplified structure while maintaining oil-cutting performance.

[0075] 1 Steam turbine O Axis 2 Rotor 21 Rotor shaft 22 Rotor blades 22A Rotor blade row 211 Protrusion 3 Casing 4 Stationary blades 4A Stationary blade row 5 Bearing base 51 First bearing base 52 Second bearing base 6 Bearing 61 First bearing 62 Second bearing 66 Journal bearing 67 Thrust bearing 7 Bearing casing 71 First bearing casing 72 Second bearing casing 75 Casing contact surface 76 Casing position determination part 79 Flexible plate 8 Oil cut-off device 81 Oil cut-off body 811 Inner surface 812 Outer surface 813 Side surface of body 814 Gas supply hole 815 Gas discharge hole 816 Discharge hole 816A First discharge hole 816B Second discharge hole 817 Oil cut-off position determination part 82 Fin part 820 Fin side 821 First fin section 822 Second fin section 823 Third fin section 824 Fourth fin section 83 Guide plate 831 Guide body 832 Shielding plate section Da Axial direction Da1 First side Da2 Second side Dr Radial direction Dr Outer side Dri Inner side Dv Vertical direction Dc Circumferential direction

Claims

1. The device comprises a rotor rotatable about an axis, a bearing that rotatably supports the rotor, and an oil cut-off device arranged to cover the outer circumferential surface of the rotor and to suppress leakage of lubricating oil from the bearing, wherein the oil cut-off device has an oil cut-off body whose inner surface is arranged radially away from the outer circumferential surface of the rotor and centered on the axis, and is formed in an annular shape around the axis so as to surround the rotor, and has a plurality of fin portions that protrude radially inward from the inner surface of the oil cut-off body and whose tips are capable of sliding contact with the outer circumferential surface of the rotor, wherein the plurality of fin portions are arranged apart from each other in the axial direction in which the axis extends, and have a first fin portion, a second fin portion, a third fin portion, and a fourth fin portion located in order from the position closest to the bearing in the axial direction, and the oil cut-off body has a gas supply hole that opens on the inner surface so as to communicate with the space between the third fin portion and the fourth fin portion in the axial direction, extends radially from the inner surface toward the outer surface, and is capable of supplying exhaust gas toward the outer circumferential surface of the rotor. In the third fin portion and the fourth fin portion, the fin side surface facing the axial direction is formed only by a plane extending radially from the inner surface to the tip, in a steam turbine.

2. The steam turbine according to claim 1, wherein the plurality of fin portions are not detachable from the oil cutter body and are formed as an integral structure with the oil cutter body by machining a single component.

3. The steam turbine according to claim 1 or 2, further comprising a bearing casing that covers a part of the rotor from the radially outer side and houses the bearing and the oil cut-off device, wherein the bearing casing has a casing contact surface that contacts the outer surface of the oil cut-off body and a casing positioning portion that is recessed radially relative to the casing contact surface, the oil cut-off body has an oil cut-off positioning portion that protrudes radially relative to its outer surface so as to be fitted into the casing positioning portion with its movement in the axial direction restricted, and the outer surface has only the oil cut-off positioning portion formed as a convex portion protruding radially and is a plane extending in the axial direction.

4. The steam turbine according to claim 1 or 2, wherein the oil cutter body has a discharge hole that opens on its inner surface in the axial direction so as to communicate with the space between the first fin portion and the second fin portion, extends vertically downward from the inner surface and connects to the outside, and the discharge hole is formed to open only on the inner surface at the lowest vertical end of the oil cutter body.

5. The steam turbine according to claim 4, wherein the oil cut-off device further comprises a guide plate fixed to the oil cut-off body and suppressing splashing of the lubricating oil discharged from the opening on the outer surface of the discharge hole, the guide plate having: a guide body fixed to the side surface of the oil cut-off body facing the axial direction and formed in the shape of a plate so as to protrude downward in the vertical direction relative to the outer surface; and a shielding plate portion arranged to cover the opening on the outer surface of the discharge hole from the outside and formed in the shape of a plate so as to extend in the axial direction from the end of the guide body which is separated from the outer surface in the vertical direction, the guide plate covers only a range of ±30° around the axis with respect to the discharge hole when viewed from the axial direction.

6. The steam turbine according to claim 1 or 2, wherein the through hole penetrating the oil cutter body extends linearly with respect to the axial or radial direction.

7. An oil cut-off device that can be positioned to cover the outer circumferential surface of a steam turbine rotor and suppresses leakage of lubricating oil, comprising: an oil cut-off body formed in an annular shape with respect to an axis; a plurality of fin portions that protrude radially inward from the inner surface of the oil cut-off body toward the axis, with their tips sliding against the outer circumferential surface of the rotor, wherein the plurality of fin portions are spaced apart from each other in the axial direction in which the axis extends, and have a first fin portion, a second fin portion, a third fin portion, and a fourth fin portion located sequentially from one side in the axial direction; the oil cut-off body has a gas supply hole that opens on its inner surface in the axial direction so as to communicate with the space between the third fin portion and the fourth fin portion, and extends radially from the outer surface of the oil cut-off body toward the inner surface, and is capable of supplying exhaust gas; the third fin portion and the fourth fin portion have a fin side surface facing the axial direction formed by a plane extending radially from the inner surface to the tip. The oil-cutting body is an oil-cutting device having a structure that allows it to be divided vertically into upper and lower sections using a virtual horizontal plane passing through the axis as the dividing surface.

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