JP6695195B2 - Sensor cover, sensor, and steam turbine - Google Patents

Description

  The present invention relates to a sensor cover, a sensor, and a steam turbine.

  The steam turbine is used for machine driving and has a rotatably supported rotor and a casing that covers the rotor. The steam turbine is rotationally driven by supplying steam as a working fluid to the rotor. In a steam turbine, a rotor is provided with a rotor blade, and a stator blade is provided with a casing that covers the rotor. In the steam flow path of the steam turbine, a plurality of stages of moving blades and stationary blades are alternately arranged. When the steam flows in the steam flow path, the flow of the steam is rectified by the stationary blades, and the rotor is rotationally driven via the moving blades.

  In such a steam turbine, water droplets (drain) are generated in the steam flowing through the steam flow path. When the steam containing the water drops flows in the steam flow path and the water drops collide with a structure such as a moving blade arranged in the steam flow path, erosion that erodes the surface occurs.

  Therefore, it is necessary to take measures against erosion, especially at the leading edge portion of the moving blade where erosion is likely to occur. For example, Patent Document 1 describes, as a countermeasure against erosion, a blade in which the blade cross-sectional shape of the leading edge portion of the blade is formed to have an acute angle and the collision angle of water droplets on the blade surface is changed.

  By the way, various sensors are arranged in the steam flow path in addition to the moving blades. Such a sensor is arranged at a position where it is exposed to the steam flowing through the steam flow path, so that the water droplets collide with the surface. As a result, the sensor is greatly affected by erosion. Therefore, there is a structure in which the sensor is embedded in the inner surface of the casing so that the surface of the sensor is not exposed to steam.

JP-A-5-195702

  However, in order to improve the sensor characteristics, it is preferable to arrange the sensor in the vapor flow path. Therefore, there is a demand to suppress the influence of erosion while arranging the sensor in the vapor flow path.

  The present invention has been made to meet the above-mentioned demand, and an object of the present invention is to provide a sensor cover, a sensor, and a steam turbine that can suppress the influence of erosion.

In order to solve the above problems, the present invention proposes the following means.
The sensor cover according to the first aspect of the present invention includes a rotor that rotates about an axis, a casing that surrounds the rotor from the outer peripheral side, and defines a steam flow path through which steam flows between the rotor and the casing. A sensor cover of a sensor in a steam turbine, comprising: a cover main body extending in a radial direction centered on the axis from the casing toward the outer peripheral surface of the rotor in the steam flow passage, the cover main body comprising: A main body having a convex curved surface that is convex and curved outward in a cross-section that intersects the radial direction, and a protrusion that gradually narrows from the main body toward the upstream side in the flow direction of the steam. And a first surface extending from the convex curved surface toward the upstream side in a cross section intersecting with the radial direction, and the protruding portion extending from the convex curved surface toward the upstream side. possess a second surface which forms a corner and intersects the one side, the cover body is rotatably supported by the imaginary line around which extends in the radial direction with respect to the casing, intersecting the radial direction In the cross-section, there is a downstream projecting portion projecting from the main body portion toward the downstream side in the flow direction of the steam, and the amount of projecting in the flow direction is larger than that of the projecting portion .

According to such a configuration, the steam flowing from the upstream side can be made to flow along the first surface and the second surface by the corners without vertically colliding with the surface of the sensor cover. Since the steam flowing along each of the first surface and the second surface is in contact with the convex curved surface while being inclined, the steam flows to the downstream side of the main body portion without colliding vertically with the convex curved surface. As a result, the amount of water droplets that collide with the surface of the sensor cover can be reduced, and erosion can be less likely to occur.
Also, even if the flow direction of steam is unknown or the flow of steam changes, the downstream projection receives steam and rotates the cover body, so that the projection is directed to the upstream side. You can With this, the protrusion can be directed to the upstream side in the flow direction with high accuracy regardless of the flow direction of the steam in the steam flow path. Therefore, the influence of erosion on the sensor cover can be suppressed with high accuracy.
Further, in the sensor cover according to the second aspect of the present invention, in the first aspect, the downstream projecting portion has a third surface extending from the convex curved surface toward the downstream side in a cross section intersecting with the radial direction. , A fourth surface extending from the convex curved surface toward the downstream side and intersecting with the third surface to form a downstream corner portion.
With such a configuration, even if steam is received at the downstream protrusion, the steam can be sent to the downstream side of the cover body without disturbing the flow of steam. Therefore, the loss when rotating the cover body can be suppressed, and the cover body can be rotated according to the flow direction of the steam.

Further, in the sensor cover according to the third aspect of the present invention, in the first or second aspect, the first surface and the second surface form a tangent to the convex curved surface in a cross section that intersects the radial direction. May be connected as follows.

  According to such a configuration, the steam flowing along the first surface and the second surface can flow along the convex curved surface without colliding with the convex curved surface when reaching the convex curved surface. Therefore, the amount of water droplets that collide with the convex curved surface can be reduced, and erosion on the convex curved surface can be made less likely to occur.

Further, in the sensor cover according to the fourth aspect of the present invention, in any one of the first to third aspects , the first surface and the second surface are inward in a cross section intersecting the radial direction. It may be formed by a curved surface that is concave toward the side.

  According to such a configuration, the flowing direction of the steam flowing along the first surface and the second surface can be gently changed. This makes it more difficult for water drops in the steam to collide with the first surface and the second surface.

Further, in the sensor cover according to the fifth aspect of the present invention, in any one of the first to fourth aspects, the protruding portion may have a smaller angle formed by the corner portion as the protrusion portion is separated from the casing. Good.

  According to such a configuration, the steam flowing from the upstream side does not collide with the first surface and the second surface of the region of the protruding portion that is far from the casing and is easily exposed to the steam, respectively. Can easily flow along. Therefore, the erosion countermeasure can be focused on the portion that is easily affected by the erosion.

The sensor according to the sixth aspect of the present invention has the sensor cover according to any one of the first to fifth aspects.

  With such a configuration, the sensor cover can suppress the influence of erosion and prolong the life of the sensor.

Further, the steam turbine in the seventh aspect of the present invention is a rotor that rotates around an axis, and a casing that surrounds the rotor from the outer peripheral side and that defines a steam flow path through which steam flows between the rotor and the rotor. And the sensor of the sixth aspect.

  With such a configuration, the sensor can have a long life and the frequency of sensor replacement can be reduced. Therefore, it is possible to reduce the frequency of stopping the steam turbine and operate the steam turbine efficiently.

  According to the present invention, the influence of erosion can be suppressed.

It is a schematic diagram which shows the structure of the steam turbine in embodiment of this invention. It is a schematic diagram explaining arrangement | positioning of the sensor in the steam turbine of 1st embodiment of this invention. It is a perspective view explaining the sensor cover in a first embodiment of the present invention. It is sectional drawing explaining the sensor cover in 1st embodiment of this invention. It is sectional drawing explaining the sensor cover in 2nd embodiment of this invention. It is a perspective view explaining the sensor cover in a third embodiment of the present invention. It is sectional drawing explaining the VII-VII cross section at the casing side of the sensor cover in FIG. It is sectional drawing explaining the VIII-VIII cross section on the moving blade side of the sensor cover in FIG. It is sectional drawing explaining the sensor cover in 4th embodiment of this invention. It is sectional drawing explaining the sensor cover in 5th embodiment of this invention.

<< First embodiment >>
Embodiments according to the present invention will be described below with reference to the drawings.
The steam turbine 100 is a rotary machine that extracts the energy of the steam S as rotary power. As shown in FIG. 1, the steam turbine 100 of this embodiment includes a casing 1, a stationary blade 2, a rotor 3, a bearing portion 4, and a sensor 5.

  In the following, the direction in which the axis Ac of the rotor 3 extends is defined as the axial direction Da, the circumferential direction Dc around the axis Ac is simply the circumferential direction Dc, and the radial direction around the axis Ac is simply the radial direction Dr. .. The circumferential direction Dc is a direction including the rotation direction of the rotor 3.

  The casing 1 and the rotor 3 define a steam flow path 13 through which the steam S flows. The casing 1 surrounds the rotor 3 from the outer peripheral side which is the outer side in the radial direction Dr. In the casing 1, a steam inlet 11 that guides the steam S into the casing 1 is formed on the front side which is one side of the axial direction Da. The casing 1 is provided with a steam outlet 12 for discharging the steam S passing through the casing 1 to the outside on the rear side which is the other side in the axial direction Da. The steam flow path 13 is formed inside the casing 1 so as to communicate with the steam inlet 11 and the steam outlet 12.

  A plurality of the stationary vanes 2 are provided side by side along the circumferential direction Dc of the rotor 3 on the inner surface of the casing 1 facing inward in the radial direction Dr. The stationary blades 2 are arranged at intervals in the radial direction Dr with respect to the rotor 3. The stationary blades 2 are arranged at intervals in the axial direction Da with the moving blades 32 described later.

The rotor 3 rotates about the axis Ac. The rotor 3 has a rotor body 31 and moving blades 32.
The rotor body 31 extends in the axial direction Da so as to penetrate the casing 1. The rotor main body 31 has an intermediate portion in which the moving blades 32 are provided housed inside the casing 1. Both ends of the rotor body 31 project outside the casing 1. Both ends of the rotor body 31 are rotatably supported by the bearing portion 4.

  A plurality of rotor blades 32 are arranged side by side in the circumferential direction Dc of the rotor body 31. The plurality of moving blades 32 are annularly arranged on the outer peripheral surface of the rotor body 31. The moving blade 32 is arranged in the steam flow path 13. The rotor blade 32 receives the steam S flowing in the steam flow path 13 in the axial direction Da and rotates the rotor body 31 around the axis Ac. The moving blade 32 of the present embodiment has a blade main body 32a extending in the radial direction Dr, and a shroud portion 32b provided at the outer tip of the blade main body 32a in the radial direction Dr. The rotor blade 32 is arranged so that the surface of the shroud portion 32b facing outward in the radial direction Dr faces the inner surface of the casing 1 facing the steam passage 13 with a gap.

  The bearing portion 4 supports the rotor 3 rotatably around the axis Ac. The bearing portion 4 includes journal bearings 41 provided at both ends of the rotor body 31, and a thrust bearing 42 provided at one end side of the rotor body 31.

  The sensor 5 is arranged so as to project into the vapor flow path 13. The sensor 5 of this embodiment is attached so as to protrude inward in the radial direction Dr from the inner surface of the casing 1. The sensor 5 is provided at a position corresponding to the moving blade 32 arranged on the most rear side in the steam flow path 13. The sensor 5 measures a physical quantity related to the operating condition of the steam turbine 100. Specifically, the sensor 5 of the present embodiment detects the clearance between the inner surface of the casing 1 and the shroud portion 32b by measuring the distance from the moving blade 32. As shown in FIG. 2, the sensor 5 has a sensor body 51 that measures the distance to the surface of the shroud portion 32b that faces the outside in the radial direction Dr, and a sensor cover 6 that houses the sensor body 51 therein.

  The sensor main body 51 is not limited to the measuring instrument that measures the distance as in the present embodiment, but may be a measuring instrument that detects the physical quantity of the steam S. For example, the sensor body 51 may be a known pressure sensor or temperature sensor.

  The sensor cover 6 can accommodate the sensor main body 51 inside. The sensor cover 6 includes a cover body 60 that extends in the radial direction Dr from the casing 1 toward the outer peripheral surface of the rotor 3 in the steam flow path 13. The cover body 60 is arranged so as to be exposed to the flow of the steam S in the steam flow path 13. As shown in FIG. 3, the cover body 60 extends along an imaginary line O1 extending in the radial direction Dr. The cover body 60 has a bottomed cylindrical shape centered on the imaginary line O1. The cover body 60 is attached to the casing 1. The cover body 60 extends from the casing 1 so that the bottom portion is arranged in the steam flow path 13. The cover body 60 of the present embodiment has a body portion 61 and a protruding portion 62.

  The main body 61 has a space formed therein for accommodating the sensor main body 51. The main body portion 61 has a convex curved surface 611 that is convex and curved outward in a cross section that intersects the radial direction Dr. The main body 61 of the present embodiment has a substantially cylindrical shape centered on the imaginary line O1. That is, the convex curved surface 611 has an arc shape centered on the imaginary line O1 in the circumferential direction Dc cross section orthogonal to the radial direction Dr. One end of the main body 61 on which the imaginary line O1 extends (upper surface of FIG. 3) is fixed to the inner surface of the casing 1.

  The main body 61 is not limited to the structure having a substantially cylindrical shape centered on the virtual line O1 as in the present embodiment. For example, the main body portion 61 may be formed in a tubular shape such that the convex curved surface 611 has an elliptic arc shape in the circumferential direction Dc cross section orthogonal to the radial direction Dr.

  The protruding portion 62 protrudes from the main body portion 61 toward the upstream side in the flow direction Df of the steam S so as to become gradually thinner. The protrusion 62 of this embodiment is formed integrally with the main body 61. As shown in FIG. 4, the projecting portion 62 is tapered so that the cross section in the circumferential direction Dc has a substantially triangular shape. The projecting portion 62 is formed so as to cover approximately half of the convex curved surface 611 facing the upstream side in the flow direction Df in the circumferential direction Dc cross section. The protrusion 62 has a first surface 621 and a second surface 622.

  Here, the flow direction Df of the steam S is the direction in which the steam S flows at the position where the sensor 5 is arranged in the steam flow path 13. The flow direction Df of the steam S in the present embodiment is the rotation direction in which the rotor 3 rotates. Therefore, the upstream side in the flow direction Df is one side in the circumferential direction Dc and is the rear side in the rotation direction of the rotor 3. The downstream side in the flow direction Df is the other side in the circumferential direction Dc and is the front side in the rotation direction of the rotor 3.

  The first surface 621 extends from the convex curved surface 611 toward the upstream side in a cross section that intersects the radial direction Dr. Here, in the cross section of the cover body 60 in the circumferential direction Dc, a virtual line orthogonal to the virtual line O1 and extending in the flow direction Df is referred to as a virtual center line O2. The first surface 621 is formed on one side in the direction orthogonal to the flow direction Df (on the left side of the paper surface of FIG. 4) with respect to the virtual centerline O2 in the cross section in the circumferential direction Dc. In the circumferential direction Dc cross section, the first surface 621 extends from the convex curved surface 611 so as to approach the virtual center line O2 toward the upstream side. That is, the first surface 621 is provided so as to be inclined with respect to the flow direction Df. The first surface 621 of the present embodiment is a flat surface connected to the convex curved surface 611 so as to form a tangent to the convex curved surface 611 in the circumferential direction Dc cross section. The first surface 621 is connected to the convex curved surface 611 such that the line connecting the connecting portion with the convex curved surface 611 and the virtual line O1 forms an angle of about 30 ° with respect to the virtual center line O2 in the circumferential direction Dc cross section. ing.

  The second surface 622 extends from the convex curved surface 611 toward the upstream side in a cross section that intersects the radial direction Dr. The second surface 622 is formed on the other side (right side of the paper surface of FIG. 4) in the direction orthogonal to the flow direction Df with respect to the virtual centerline O2 in the circumferential direction Dc cross section. The second surface 622 intersects with and is connected to the first surface 621 to form a corner portion 623. The second surface 622 is connected to the first surface 621 on the virtual center line O2. The second surface 622 of the present embodiment is a plane formed symmetrically with the first surface 621 with the virtual center line O2 as a boundary. The second surface 622 extends in the circumferential direction Dc section so as to approach the virtual center line O2 toward the upstream side. That is, the second surface 622 is provided so as to be inclined with respect to the flow direction Df. The second surface 622 is connected to the convex curved surface 611 so as to form a tangent line to the convex curved surface 611 in the circumferential direction Dc cross section. The second surface 622 is connected to the convex curved surface 611 such that the line connecting the connecting portion with the convex curved surface 611 and the virtual line O1 forms an angle of about 30 ° with respect to the virtual center line O2 in the circumferential direction Dc cross section. ing.

  The corner portion 623 is a connecting portion between the first surface 621 and the second surface 622. In the cross section in the circumferential direction Dc, the corner portion 623 of the present embodiment is formed on the virtual center line O2 on the upstream side of the main body portion 61 in the flow direction Df. The angle of the corner portion 623 in the circumferential direction Dc cross section is an obtuse angle.

  In the steam turbine 100 as described above, the sensor 5 is arranged in the steam flow path 13 in which the steam S flows. In the steam S, water drops (drain) are generated as the pressure decreases. Especially in the vicinity of the last stage, the pressure in the steam flow path 13 is lowered, so that water droplets are easily generated. Therefore, as the rotor blades 32 rotate, the water droplets in the steam S flowing with the flow direction Df set to the direction along the circumferential direction Dc flow toward the sensor 5 and collide with the sensor cover 6.

  However, according to the sensor 5 having the sensor cover 6 as described above, the corner 623 is separated from the main body 61 by the first surface 621 and the second surface 622 extending from the convex curved surface 611 toward the upstream side. Is formed on the virtual center line O2. Therefore, the steam S flowing from the upstream side contacts the sensor cover 6 from the corner portion 623. As a result, the corners 623 allow the steam S to flow along the first surface 621 and the second surface 622 respectively without causing the steam S to impinge perpendicularly on the surfaces such as the first surface 621 and the second surface 622. It can be distributed. The steam S flowing along each of the first surface 621 and the second surface 622 is in contact with the convex curved surface 611 while being inclined, so that the steam S of the main body portion 61 does not vertically collide with the convex curved surface 611. It flows to the downstream side. As a result, it is possible to reduce the amount of water droplets that collide with the surface of the sensor cover 6 and prevent erosion from occurring. Thereby, the influence of erosion on the sensor cover 6 can be suppressed.

  Further, in the cross section in the circumferential direction Dc, the first surface 621 and the second surface 622 are connected so as to be tangent to the convex curved surface 611. Therefore, the steam S flowing along the first surface 621 and the second surface 622 can flow along the convex curved surface 611 without colliding with the convex curved surface 611 when reaching the convex curved surface 611. Therefore, the amount of water droplets that collide with the convex curved surface 611 can be reduced, and erosion on the convex curved surface 611 can be made less likely to occur.

  Further, according to the sensor 5 having such a sensor cover 6, it is possible to prevent the sensor cover 6 from being chipped due to erosion and exposing the sensor body 51 to the steam S. Therefore, the sensor cover 6 can suppress the influence of erosion and prolong the life of the sensor 5.

  Further, the sensor cover 6 as described above is used for the sensor 5 arranged at a position facing the tip of the moving blade 32 on the most rear side. Therefore, it is possible to protect the sensor 5 arranged in the area having the lowest pressure in the steam flow path 13 and the most water droplets in the steam S from erosion.

  Further, according to the steam turbine 100 using such a sensor 5, it is possible to achieve a long service life of the sensor 5 and reduce the frequency of replacement of the sensor 5. Therefore, the frequency of stopping the steam turbine 100 can be reduced and the steam turbine 100 can be operated efficiently.

<< Second embodiment >>
Next, the sensor cover of the second embodiment will be described with reference to FIG.
In the second embodiment, the same components as those in the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted. The sensor cover 6A of the second embodiment differs from that of the first embodiment in the configuration of the protruding portion 62A.

  The projecting portion 62A of the cover body 60A of the second embodiment projects from the body portion 61 toward the upstream side in the flow direction Df of the steam S such that the projecting portion 62A becomes gradually thinner, as in the first embodiment. In the projecting portion 62A, the first surface 621A and the second surface 622A are formed by curved surfaces that are concave toward the inside in a cross section that intersects the radial direction Dr, as shown in FIG. In the protruding portion 62A of the second embodiment, the first surface 621A and the second surface 622A are formed such that the angle formed by the first surface 621A and the second surface 622A becomes smaller toward the upstream side in the flow direction Df. Is curved. Similar to the first embodiment, the protruding portion 62A is formed so as to cover approximately half of the convex curved surface 611 facing the upstream side in the flow direction Df.

  The first surface 621A of the second embodiment is a concave curved surface that is recessed so as to approach the virtual center line O2 toward the upstream side in the flow direction Df in the circumferential direction Dc cross section. The first surface 621A extends from the same position as the first embodiment toward the upstream side with respect to the convex curved surface 611.

  The second surface 622A of the second embodiment is a concave curved surface that is recessed so as to approach the virtual center line O2 toward the upstream side in the flow direction Df in the circumferential direction Dc cross section. The second surface 622A is connected to the first surface 621A on the virtual center line O2. The second surface 622A of the second embodiment is connected to the first surface 621A at a position distant from the convex curved surface 611 to the upstream side as compared with the first embodiment. The second surface 622A is a concave curved surface formed symmetrically with the first surface 621A with the virtual center line O2 as a boundary. The second surface 622A extends toward the upstream side from the same position as in the first embodiment with respect to the convex curved surface 611.

  The corner portion 623A of the second embodiment is formed at an angle (for example, an acute angle) smaller than that of the corner portion 623A of the first embodiment. The corner portion 623A is located upstream of the corner portion 623A of the first embodiment on the virtual center line O2.

  According to the sensor cover 6A of the second embodiment, the first surface 621A and the second surface 622A are formed as concave curved surfaces, so that the steam S flowing along the first surface 621A and the second surface 622A flows. The direction can be changed gently. This makes it more difficult for the water droplets in the steam S to collide with the first surface 621A and the second surface 622A. Therefore, the influence of erosion on the sensor cover 6A can be further suppressed.

  Further, since the corner portion 623A is formed with a small angle such as an acute angle, the steam S flowing from the upstream side can easily flow along the first surface 621A and the second surface 622A without colliding with each other. be able to. Therefore, the influence of erosion on the sensor cover 6A can be further suppressed.

<< Third Embodiment >>
Next, the sensor cover of the third embodiment will be described with reference to FIGS. 6 to 8.
In the third embodiment, the same components as those in the first and second embodiments are designated by the same reference numerals, and detailed description thereof will be omitted. The sensor cover 6B of the third embodiment differs from the first and second embodiments in the configuration of the protruding portion 62B.

  In the protruding portion 62B of the cover body 60B of the third embodiment, as shown in FIG. 6, the angle formed by the corner portion 623B becomes smaller as the distance from the casing 1 increases. Specifically, in the protruding portion 62B of the second embodiment, the protruding amount from the main body portion 61 to the upstream side is larger on the outer side in the radial direction Dr closer to the casing 1 and on the inner side in the radial direction Dr closer to the shroud portion 32b. Different. Specifically, the projecting portion 62B projects toward the upstream side as it extends from the outside in the radial direction Dr toward the inside in the radial direction Dr. Similar to the first embodiment, the protruding portion 62B protrudes from the main body portion 61 toward the upstream side in the flow direction Df of the steam S so as to become gradually thinner. The protruding portion 62B is formed so as to cover about half of the convex curved surface 611 facing the upstream side in the flow direction Df.

  In the circumferential direction Dc cross section, the first surface 621B of the third embodiment extends so as to approach the virtual center line O2 toward the upstream side. The first surface 621B is a flat surface connected to the convex curved surface 611 in the circumferential direction Dc cross section. As shown in FIGS. 7 and 8, the first surface 621B is inclined so that the angle with respect to the virtual center line O2 in the cross section in the circumferential direction Dc becomes smaller as it extends in the radial direction Dr away from the casing 1. There is. That is, the first surface 621B is formed so as to extend toward the upstream side as it approaches the shroud portion 32b from the casing 1. The first surface 621B near the casing 1 has a line connecting the connecting portion with the convex curved surface 611 and the virtual line O1 at an angle of about 30 ° with respect to the virtual center line O2 in the circumferential direction Dc cross section. It is connected to the convex curved surface 611. The first surface 621B is connected to the convex curved surface 611 so that this angle increases as the distance from the casing 1 increases.

  In the circumferential direction Dc cross section, the second surface 622B of the third embodiment extends so as to approach the virtual center line O2 toward the upstream side. The second surface 622B is inclined such that the angle with respect to the virtual center line O2 in the circumferential direction Dc cross section becomes smaller as it extends in the radial direction Dr away from the casing 1. That is, the second surface 622B is formed so as to extend toward the upstream side as it approaches the shroud portion 32b from the casing 1. The second surface 622B is connected to the first surface 621B on the virtual center line O2. The second surface 622B is a plane formed symmetrically with the first surface 621B with the virtual center line O2 as a boundary. The second surface 622B at a position close to the casing 1 has a line connecting the connecting portion with the convex curved surface 611 and the virtual line O1 at an angle of about 30 ° with respect to the virtual center line O2 in the circumferential direction Dc cross section. It is connected to the convex curved surface 611. The second surface 622B is connected to the convex curved surface 611 so that this angle increases as the distance from the casing 1 increases.

  The corner portion 623B is formed so as to be located on the upstream side on the virtual center line O2 so as to be separated from the main body portion 61 as it is separated from the casing 1. That is, the corner portion 623B is formed such that the angle in the circumferential direction Dc cross section becomes smaller as it approaches the shroud portion 32b from the casing 1.

  According to the sensor cover 6B of the third embodiment, the angle of the corner portion 623B is formed to be smaller toward the inner side in the radial direction Dr. Therefore, the steam S flowing from the upstream side collides with the first surface 621B and the second surface 622B with respect to the region inside the radial direction Dr of the protrusion 62B that is separated from the casing 1 and is easily exposed to the steam S. It is possible to make it easy to flow along each without doing. Therefore, the erosion countermeasure can be focused on the portion that is easily affected by the erosion. Therefore, the influence of erosion on the sensor cover 6B can be effectively suppressed.

<< Fourth Embodiment >>
Next, the sensor cover of the fourth embodiment will be described with reference to FIG.
In the fourth embodiment, the same components as those in the first to third embodiments are designated by the same reference numerals, and detailed description thereof will be omitted. The sensor cover 6C of the fourth embodiment is rotatable with respect to the casing 1 and differs from the first embodiment in that it has a downstream protrusion 7.

  The cover main body 60C of the sensor cover 6C of the first embodiment is rotatably supported with respect to the casing 1 around the virtual line O1. The cover body 60C of the present embodiment is rotatable with respect to the casing 1 and the sensor body 51 in a state where the sensor body 51 is housed inside. The cover main body 60C has a main body 61C, a protrusion 62, and a downstream protrusion 7.

  The main body 61C accommodates the sensor 5 therein. The main body 61C is rotatable about the imaginary line O1 with respect to the inner surface of the casing 1. As shown in FIG. 9, the body 61C of the fourth embodiment has the same shape as the body 61 of the first embodiment.

  The protrusion 62 of the fourth embodiment is formed integrally with the main body 61C. The protrusion 62 has the same structure as the protrusion of the first embodiment.

  The downstream projecting portion 7 projects from the main body portion 61C toward the downstream side in the flow direction Df of the steam S in the cross section intersecting the radial direction Dr. The downstream protrusion 7 is formed such that the protrusion amount in the flow direction Df is larger than that of the protrusion 62. In the circumferential direction Dc cross section, the downstream projecting portion 7 of the present embodiment projects along the virtual center line O2 on the side opposite to the projecting portion 62 with respect to the main body portion 61C. The downstream protruding portion 7 has a plate shape and protrudes from the main body portion 61C. That is, the downstream protruding portion 7 has a rectangular shape centered on the virtual center line O2 in the circumferential direction Dc cross section. The amount of protrusion of the downstream protrusion 7 from the main body 61C to the downstream side is larger than the amount of protrusion of the protrusion 62 from the main body 61C to the upstream side.

  According to the sensor cover 6C of the fourth embodiment, the main body 61C is rotatably supported by the casing 1 around the imaginary line O1, so that the main body 61C can be rotated by receiving the flow of the steam S. In addition, since the downstream projecting portion 7 is formed to project beyond the projecting portion 62, when the flow of the steam S is received, the downstream projecting portion 7 can be directed to the downstream side. Therefore, even if the flow direction Df of the steam S is unknown or the flow of the steam S changes, the downstream projection 7 receives the steam S and rotates the cover main body 60C, so that the projection 62 can be directed upstream. As a result, the protrusion 62 can be directed to the upstream side in the flow direction Df with high accuracy regardless of the flow direction Df of the steam S in the steam flow path 13. Therefore, the influence of erosion on the sensor cover 6C can be suppressed with high accuracy.

<< Fifth Embodiment >>
Next, the sensor cover of the fifth embodiment will be described with reference to FIG.
In the fifth embodiment, the same components as those in the first to fourth embodiments are designated by the same reference numerals, and detailed description thereof will be omitted. The sensor cover 6D of the fifth embodiment differs from the fourth embodiment in the downstream protrusion 7D.

  The downstream projecting portion 7D of the cover body 60D of the fifth embodiment projects from the body portion 61 toward the downstream side so as to become gradually thinner. The downstream protrusion 7D is formed integrally with the main body 61. The downstream projecting portion 7D is tapered so that the circumferential direction Dc cross section has a substantially triangular shape. The downstream projecting portion 7D is formed so as to cover approximately half of the convex curved surface 611 facing the downstream side in the flow direction Df. The amount of protrusion of the downstream protruding portion 7D from the main body portion 61 to the downstream side is larger than the amount of protrusion of the protruding portion 62 from the main body portion 61 to the upstream side, as in the fourth embodiment. The protrusion 62 has a third surface 73 and a fourth surface 74.

  The third surface 73 extends from the convex curved surface 611 toward the downstream side in the cross section intersecting the radial direction Dr. The third surface 73 is formed on one side (on the left side of the paper surface of FIG. 10) in the circumferential direction Dc section in a direction orthogonal to the flow direction Df with respect to the virtual center line O2. In the circumferential direction Dc cross section, the third surface 73 extends from the convex curved surface 611 so as to approach the virtual center line O2 toward the downstream side. That is, the third surface 73 is provided so as to be inclined with respect to the flow direction Df. The third surface 73 is a flat surface connected to the convex curved surface 611 so as to form a tangent line to the convex curved surface 611 in the circumferential direction Dc cross section.

  The fourth surface 74 extends from the convex curved surface 611 toward the downstream side in a cross section that intersects the radial direction Dr. The fourth surface 74 is formed on the other side (on the right side of the paper surface in FIG. 10) in the direction orthogonal to the flow direction Df with respect to the virtual center line O2 in the circumferential direction Dc cross section. The fourth surface 74 intersects and is connected to the third surface 73 to form a downstream corner 75. The fourth surface 74 is connected to the third surface 73 on the virtual center line O2. The fourth surface 74 of the present embodiment is a plane that is formed symmetrically with the third surface 73 with the virtual center line O2 as a boundary. The fourth surface 74 extends in the circumferential direction Dc section so as to approach the virtual center line O2 toward the downstream side. That is, the fourth surface 74 is provided so as to be inclined with respect to the flow direction Df. The fourth surface 74 is connected to the convex curved surface 611 so as to form a tangent line to the convex curved surface 611 in the circumferential direction Dc cross section.

  The downstream corner 75 is a connecting portion between the third surface 73 and the fourth surface 74. The downstream side corner portion 75 of the present embodiment is formed on the virtual center line O2 on the downstream side of the main body portion 61 in the flow direction Df in the circumferential direction Dc cross section. The downstream corner 75 has an obtuse angle whose angle in the circumferential direction Dc cross section is smaller than the angle of the upstream corner 623.

  According to the sensor cover 6D of the fifth embodiment, even if the steam S is received by the downstream protruding portion 7D, the steam S can be sent to the downstream side of the cover body 60D without disturbing the flow of the steam S. Therefore, it is possible to suppress loss when rotating the cover body 60D and rotate the cover body 60D in accordance with the flow direction Df of the steam S.

  As described above, the embodiments of the present invention have been described in detail with reference to the drawings. However, each configuration and the combination thereof in each of the embodiments are examples, and addition and omission of the configurations are included without departing from the spirit of the present invention. , Substitutions, and other changes are possible. Also, the invention is not limited to the embodiments, but only by the claims.

  It should be noted that the sensor 5 is not limited to being arranged only on the rearmost side as in the present embodiment. For example, the sensor 5 may be arranged on the most front side, and a plurality of the sensors 5 may be arranged apart from the vapor flow path 13 in the axial direction Da.

100 ... Steam turbine S ... Steam Ac ... Axial line Da ... Axial direction Dc ... Circumferential direction Dr ... Radial direction 1 ... Casing 11 ... Steam inlet 12 ... Steam outlet 13 ... Steam flow path 2 ... Stationary blade 3 ... Rotor 31 ... Rotor body 32 ... moving blade 32a ... blade main body 32b ... shroud part 4 ... bearing part 41 ... journal bearing 42 ... thrust bearing 5 ... sensor 51 ... sensor body 6, 6A, 6B, 6C, 6D ... sensor cover 60, 60A, 60B, 60C, 60D ... Cover body O1 ... Virtual line 61, 61C ... Body part 611 ... Convex curved surface 62, 62A, 62B ... Projection part Df ... Flow direction O2 ... Virtual center line 621, 621A, 621B ... First surface 622, 622A, 622B ... Second surface 623, 623A, 623B ... Corner portion 7, 7D ... Downstream protruding portion 73 ... Third surface 74 ... Fourth surface 75 ... Downstream side corner portion

Claims (7)

A sensor cover for a sensor in a steam turbine, comprising: a rotor that rotates about an axis; and a casing that surrounds the rotor from the outer peripheral side and that defines a steam flow path through which steam flows between the rotor and the rotor. ,
From the casing in the steam flow path toward the outer peripheral surface of the rotor, a cover main body extending in a radial direction around the axis is provided,
The cover body is
A main body portion having a convex curved surface that is convex and curved outward in a cross section that intersects the radial direction;
A projecting portion projecting from the main body portion toward the upstream side in the flow direction of the steam so as to become gradually thinner,
In the cross section that intersects the radial direction, the protrusion extends from the convex curved surface toward the upstream side, and from the convex curved surface toward the upstream side, and intersects the first surface. possess a second surface forming the corner,
The cover body is
The casing is rotatably supported around an imaginary line extending in the radial direction,
A sensor cover that has a downstream protrusion that protrudes from the main body toward the downstream side in the flow direction of the steam and that has a larger protrusion amount in the flow direction than the protrusion in a cross section that intersects the radial direction . The downstream projecting portion, in a cross section that intersects the radial direction, a third surface that extends from the convex curved surface toward the downstream side, and a third surface that extends from the convex curved surface toward the downstream side and intersects the third surface. The sensor cover according to claim 1 , further comprising a fourth surface that forms a downstream corner portion. The sensor cover according to claim 1 or 2 , wherein the first surface and the second surface are connected so as to form a tangent to the convex curved surface in a cross section that intersects the radial direction. The sensor cover according to any one of claims 1 to 3, wherein the first surface and the second surface are formed by curved surfaces that are concave inward in a cross section that intersects the radial direction. .. The sensor cover according to any one of claims 1 to 4 , wherein an angle formed by the corners of the protrusions is reduced as the protrusions are separated from the casing. A sensor comprising the sensor cover according to any one of claims 1 to 5 . A rotor that rotates around the axis,
While enclosing the rotor from the outer peripheral side, a casing that defines a steam flow path through which steam flows between the rotor and the rotor,
A steam turbine comprising: the sensor according to claim 6 .

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