JP2010265826A - Nozzle box for steam turbine and steam turbine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nozzle box for steam turbine in which steam can be guided to a first stage nozzle with pressure loss reduced when the steam flows between reinforcing members circumferentially arranged in a given direction for reinforcing the structure, and to provide a steam turbine equipped with the nozzle box for the steam turbine. <P>SOLUTION: The nozzle box 10 is configured so that the steam introduced from a steam inlet tube 220 to inflow into a steam flow passage 20 circumferentially extending is allowed to pass between bridges 30 and is guided to the first nozzle 213a. Among a plurality of the bridges 30 circumferentially arranged in a uniform direction, on the upstream side of the first nozzle 213a, part of one lateral side 33a ranging from the front edge 32 to the rear edge 34 of at least one bridge 30 is equipped with a flow disturbing mechanism 50 for disturbing the steam flow. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a steam turbine nozzle box installed in a steam turbine and a steam turbine including the steam turbine nozzle box.

  BACKGROUND ART An axial flow rotary machine such as a steam turbine used in a thermal power plant or the like includes a cascade composed of a combination of a plurality of stages of nozzles with stationary flow paths through which a working fluid passes and rotating rotor blades. ing. In the case of a steam turbine, it is generally classified into a high-pressure part, an intermediate-pressure part, and a low-pressure part based on the conditions of steam as a working fluid. In each blade row, in order to improve work efficiency by the working fluid, the flow path between the blade rows needs to be designed in a shape that allows the working fluid to flow smoothly.

Conventionally, in order to effectively use energy resources and reduce CO ₂ emissions, it is important to improve the efficiency of power generation equipment. In order to improve the efficiency of the steam turbine, for example, it is possible to effectively convert the given energy into mechanical work. One countermeasure is to reduce various internal losses.

  Internal losses in steam turbines include profile loss due to blade shape, secondary loss due to secondary flow, leakage loss due to leakage of working fluid outside the cascade, and drains specific to the final blade group. There are losses in the steam turbine cascade, such as due to wet loss. Further, there are a steam valve, a passage portion for introducing steam to a certain blade row, a loss in a passage portion from a certain blade row to the next blade row, an exhaust loss in the low-pressure final stage, and the like.

  In order to reduce the pressure loss of the passage portion connecting the blade rows, the technology for guiding the steam to the blade rows as uniformly as possible is disclosed. For example, a steam turbine is disclosed that includes a guide for controlling the flow of steam in order to guide steam as uniformly as possible to the cascade (see, for example, Patent Document 1). In addition, in order to guide steam as uniformly as possible to the cascade, a steam turbine (for example, see Patent Document 2) having a honeycomb material or a perforated plate at the cascade inlet, or a uniform flow by tilting the cascade in the circumferential direction (For example, refer to Patent Document 3).

  Here, the configuration of the conventional nozzle box will be described. FIG. 7 is a view when a cross section perpendicular to the turbine rotor of the conventional nozzle box 300 is viewed from the first stage nozzle 303 side. FIG. 8 is a diagram showing a cross section taken along the line AA of FIG. In addition, although the turbine rotor is penetrated in the center, illustration of the turbine rotor is omitted here.

  As shown in FIG. 7, the nozzle box 300 is divided into two upper and lower spaces, and steam 301 from a boiler (not shown) is introduced into each space by two steam inlet pipes 302. As shown in FIG. 8, the steam 301 introduced into the nozzle box 300 passes through a bridge 304 provided to reinforce the structure of the nozzle box 300 and is guided to the first stage nozzle 303. The passage section is connected to the entire circumference downstream of the first stage nozzle 303, and the steam 301 that has passed through the first stage nozzle 303 is guided to a first stage rotor blade (not shown).

  FIG. 9 is a diagram schematically showing the flow of the steam 301 when the steam 301 introduced into the space of the nozzle box 300 from the steam inlet pipe 302 flows between the bridges 304. FIG. 9 is a circumferential cross-sectional development schematic diagram in which the circumferential cross-section (circumferential cross-section) of the bridge 304 and the first stage nozzle 303 is developed on a plane, and the vertical direction in FIG. (Circumferential direction), and the horizontal direction is the turbine rotor axial direction.

  As shown in FIG. 9, all the bridges 304 are configured in the same shape, and are arranged at equal intervals in the circumferential direction in a certain direction. The bridge 304 has a shape in which the center line 305 is a straight line, and the center line 305 is installed so as to be parallel to the turbine rotor shaft. Here, α shown in FIG. 9 is an inflow angle of the steam 301 between the bridges 304. This inflow angle α corresponds to a straight line parallel to an extension line of the center line 305 at an end portion on the most upstream side of the bridge 304 (hereinafter referred to as a leading edge 304a) and a stream line of the steam 301 at the steam inflow portion between the bridges 304. Is the angle between

  As shown in FIG. 9, the larger the inflow angle α, the more easily the vortex 306 is generated in a part of the flow of the steam 301 flowing between the bridges 304, and the pressure loss is more likely to occur. In addition, the steam 301 flowing in between the bridges 304 in this way flows into the first stage nozzle 303 installed on the downstream side of the bridge 304 in a turbulent state.

  Here, FIG. 10 is a diagram showing the inflow angle α at the circumferential angle indicating the circumferential position of the bridge 304. FIG. 7 shows a position corresponding to this circumferential angle. The inflow angle α shown in FIG. 10 is obtained by three-dimensional thermal fluid analysis in a steady state using CFD (Computational Fluid Dynamics). In the inflow angle α shown on the vertical axis in FIG. 10, for example, when the inflow angle α is 0 degree, the flow direction of the steam 301 is parallel to the extension direction of the center line 305 at the front edge 304 a of the bridge 304. Become. In this case, the steam 301 flows between the bridges 304 in parallel to the center line 305 of the bridge 304 and is guided to the first stage nozzle 303.

  As shown in FIG. 10, the inflow angle α varies greatly in the circumferential direction angle. Further, when the inflow angle α is large, the vortex 306 is generated as described above, a pressure loss is generated, and the efficiency of the steam turbine is lowered.

  FIG. 11 is a view when a cross section perpendicular to the turbine rotor of the conventional nozzle box 300 having a configuration in which the steam 301 is introduced into the nozzle box 300 by two steam inlet pipes 302 is viewed from the first stage nozzle 303 side. . FIG. 12 is a diagram showing the inflow angle α at the circumferential angle indicating the circumferential position of the bridge 304 in the shape of the nozzle box 300 shown in FIG. 11. The shape of the bridge 304 is the same as that shown in FIG. Similarly to the inflow angle α shown in FIG. 10, the inflow angle α shown in FIG. 12 is obtained by three-dimensional thermal fluid analysis in a steady state using CFD (Computational Fluid Dynamics). is there.

  As shown in FIG. 12, also in this nozzle box 300, the inflow angle α varies greatly in the circumferential angle. Further, at a position having a large inflow angle α, the vortex 306 is generated as described above, a pressure loss is generated, and the efficiency of the steam turbine is reduced.

Japanese Patent Laid-Open No. 2003-1932809 US Pat. No. 6,196,793 US Pat. No. 7,207,773

  As described above, in the conventional nozzle box 300, there is a region between the bridges 304 where the steam 301 flows with a large inflow angle α. As a result, there is a problem that pressure loss occurs and the efficiency of the steam turbine decreases.

  Accordingly, the present invention has been made to solve the above-described problems, and reduces pressure loss when steam flows between reinforcing members arranged in a circumferential direction at predetermined intervals in a certain direction. It is an object of the present invention to provide a steam turbine nozzle box capable of guiding steam to the first stage nozzle and a steam turbine including the steam turbine nozzle box.

  In order to achieve the above object, according to one aspect of the present invention, the reinforcing members that are arranged from the steam inlet pipe and flow into the steam flow path that extends in the circumferential direction are arranged in a certain direction in the circumferential direction. A steam turbine nozzle box configured to lead to the first stage nozzle through the blade, wherein the plurality of reinforcing members arranged upstream of the first stage nozzle have a leading edge and a trailing edge. A flow disturbance mechanism that disturbs the flow of steam is provided on a part of one side surface extending from the front edge to the rear edge direction of at least one of the plurality of reinforcing members. A featured nozzle box for a steam turbine is provided.

  Moreover, according to one aspect of the present invention, the first stage nozzle passes the steam introduced from the steam inlet pipe and flowing into the steam flow path extending in the circumferential direction between the reinforcing members arranged in a certain direction in the circumferential direction. There is provided a steam turbine including a nozzle box for a steam turbine configured to guide the steam turbine, wherein the nozzle box is the nozzle box for a steam turbine described above.

  According to the steam turbine nozzle box of the present invention and the steam turbine provided with the steam turbine nozzle box, when steam flows between the reinforcing members arranged in the circumferential direction at predetermined intervals in a certain direction. The pressure loss can be reduced and the steam can be led to the first stage nozzle.

It is the figure which showed the cross section in the upper half casing part of the steam turbine provided with the nozzle box which concerns on this invention. It is a figure when the section perpendicular to the turbine rotor of the nozzle box of a 1st embodiment concerning the present invention is seen from the 1st stage nozzle side. It is the figure which showed typically the installation structure of the bridge | bridging and 1st stage nozzle in the nozzle box of 1st Embodiment which concerns on this invention. It is a perspective view of a bridge provided with a flow disturbance mechanism. It is a perspective view of a bridge provided with a flow disturbance mechanism of other composition. It is a perspective view of the bridge | bridging provided with the nozzle box of 2nd Embodiment which concerns on this invention which has a flow disturbance mechanism. It is a figure when the cross section perpendicular | vertical to the turbine rotor of the conventional nozzle box is seen from the 1st stage nozzle side. It is a figure which shows the AA cross section of FIG. It is the figure which showed typically the flow of the vapor | steam when the vapor | steam introduced into the space of the nozzle box from the vapor | steam inlet pipe | tube flows in between bridges. It is the figure which showed inflow angle (alpha) in the circumferential angle which shows the position of the circumferential direction of a bridge. It is a figure when the cross section perpendicular | vertical to the turbine rotor of the conventional nozzle box provided with the structure which introduce | transduces a steam into a nozzle box with two steam inlet pipes is seen from the 1st stage nozzle side. It is the figure which showed inflow angle (alpha) in the circumferential direction angle which shows the position of the circumferential direction of a bridge | bridging in the shape of the nozzle box shown by FIG.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a view showing a cross section of an upper half casing portion of a steam turbine 200 including a nozzle box 10 according to the present invention.

  As shown in FIG. 1, the steam turbine 200 includes, for example, a double-structure casing that includes an inner casing 210 and an outer casing 211 provided outside the inner casing 210. Further, a turbine rotor 212 in which a moving blade 214 is implanted is provided in the inner casing 210. The turbine rotor 212 is rotatably supported by a rotor bearing (not shown).

  In addition, nozzles 213 are arranged on the inner surface of the inner casing 210 so as to alternate with the moving blades 214 in the axial direction of the turbine rotor 212. Between the turbine rotor 212 and each casing, ground labyrinth portions 215a, 215b, 215c, and 215d are provided to prevent leakage of steam, which is a working fluid, to the outside.

  Further, the steam turbine 200 is provided with a steam inlet pipe 220 penetrating the outer casing 211 and the inner casing 210, and an end of the steam inlet pipe 220 is a nozzle that guides steam toward the moving blade 214 side. The box 10 is connected in communication. The nozzle box 10 includes a steam flow path 20 in which steam introduced from the steam inlet pipe 220 spreads in the circumferential direction. The nozzle box 10 also includes a bridge 30 that guides the steam introduced into the steam flow path 20 to the first stage nozzle 213a.

  The steam that has flowed into the nozzle box 10 through the steam inlet pipe 220 spreads in the steam flow path 20, passes through the bridge 30, is guided to the first stage nozzle 213 a, and is ejected toward the first stage rotor blade 214 a. The The jetted steam passes through the steam path between the nozzle 213 and the moving blade 214 in each stage, and rotates the turbine rotor 212. Further, most of the steam that has performed expansion work is exhausted, and flows into a boiler (not shown) through, for example, a low-temperature reheat pipe (not shown). In addition, a part of the steam ejected from the first stage nozzle 213a toward the first stage rotor blade 214a is, for example, in the ground labyrinth portion 215a between the turbine rotor 212 and the inner casing 210 on the nozzle box 10 side. It flows outward along the axial direction of the turbine rotor 212 and flows out between the inner casing 210 and the outer casing 211. And it is guide | induced between the inner casing 210 and the outer casing 211 as a cooling vapor | steam, and is discharged | emitted from the exhaust route which exhausts most of the grand labyrinth part 215b or the vapor | steam which carried out the expansion work.

  Note that the configuration of the steam turbine 200 is not limited to the above-described configuration, and may be any steam turbine having a configuration in which steam flows into the nozzle box 10 via the steam inlet pipe 220.

  Next, the nozzle box 10 according to the present invention will be described.

(Nozzle box of the first embodiment)
FIG. 2 is a view when a cross section perpendicular to the turbine rotor 212 of the nozzle box 10 of the first embodiment according to the present invention is viewed from the first stage nozzle 213a side. In addition, although the turbine rotor 212 is penetrated in the center, illustration of the turbine rotor 212 is abbreviate | omitted and shown here. FIG. 3 is a diagram schematically showing an installation configuration of the bridge 30 and the first stage nozzle 213a in the nozzle box 10 of the first embodiment according to the present invention. Note that FIG. 3 is a circumferential cross-sectional development schematic diagram in which the circumferential cross-section (circumferential cross-section) of the bridge 30 and the first stage nozzle 213a is developed on a plane, and the vertical direction in FIG. (Circumferential direction), and the horizontal direction is the turbine rotor axial direction.

  Here, as illustrated in FIG. 2, the configuration of the nozzle box 10 that is separated into two upper and lower spaces and into which steam is introduced into each space by two steam inlet pipes will be described as an example. The nozzle box 10 is not limited to this configuration. For example, the nozzle box 10 may be a nozzle box configured to introduce steam through two steam inlet pipes as shown in FIG.

  As shown in FIG. 2, the nozzle box 10 is separated into two upper and lower spaces, and for example, steam S from a boiler (not shown) is introduced into each space by two steam inlet pipes 220.

  As shown in FIG. 3, a plurality of bridges 30 and a plurality of first-stage nozzles 213 a are arranged at predetermined intervals in the circumferential direction corresponding to the steam flow paths 20 of the nozzle box 10. The bridge 30 functions as a reinforcing member, and in order to reinforce the structure of the nozzle box 10, the plurality of bridges 30 are upstream of the first stage nozzle 213 a, that is, the steam channel 20 than the first stage nozzle 213 a. On the side, the first stage nozzle 213a is lined up in a certain direction at a predetermined interval. As shown in FIG. 3, the bridge 30 is configured in an airfoil shape having a leading edge 32 and a trailing edge 34, for example. Moreover, the cross-sectional shape by the side of the front edge 32 of the bridge | bridging 30 is comprised so that it may become a semicircle and an ellipse, for example, as shown in FIG. Here, all the bridges 30 are configured such that a center line 31 (hereinafter referred to as the center line 31 of the bridge 30) from the front edge 32 to the rear edge 34 in the circumferential cross section of the bridge 30 is a straight line. The center line 31 of the bridge 30 is arranged so as to be parallel to the axial direction of the turbine rotor.

  The steam S introduced from the steam inlet pipe 220 and spreading into the steam flow path 20 flows into the passage formed between the bridges 30 according to the circumferential angle of the steam flow path 20 as shown in FIG. The angle is different. That is, the angle between the straight line parallel to the extension line of the center line 31 of the bridge 30 and the straight line parallel to the streamline direction of each steam flowing between the bridges differs between the bridges 30. Here, the angle formed by the extension of the center line 31 of the bridge 30 and the streamline of steam at the front edge 32 of the bridge 30 is defined as the inflow angle β.

  In FIG. 3, the flow path center line of the flow path for guiding the steam S from one of the four steam inlet pipes 220 between the bridges 30 is the center between the bridge 30c and the bridge 30d. The circumferential direction cross-section expansion schematic diagram of the part which passes is illustrated. Moreover, in FIG. 3, the inflow angle in each bridge | bridging 30a-30f is each shown as (beta) a- (beta) f.

  These inflow angles βa to βf are different depending on the bridges 30a to 30f, as shown in FIG. Here, inflow angles βa to βc formed clockwise (clockwise) with respect to the center line 31 of the bridge 30 are positive angles, and counterclockwise (counterclockwise) with respect to the center line 31 of the bridge 30. ) Are formed as negative angles.

  For example, the absolute values of the inflow angle βc of the bridge 30c and the inflow angle βd of the bridge 30d, which are close to the above-described flow path center line, are small, and as the distance from the bridges 30c and 30d in the circumferential direction increases, The value increases. And as shown in FIG. 10, inflow angle (beta) shows a positive or negative peak value in a predetermined circumferential direction angle.

  In the bridges 30a to 30f in the nozzle box 10 according to the first embodiment of the present invention, the inflow angles βa to βf are in the range of ± 5 degrees, that is, other than the bridge 30 in the range of −5 degrees to 5 degrees. As shown in FIG. 3, the bridge 30 is provided with a flow disturbance mechanism 50. Here, the description will be made assuming that the inflow angle βc of the bridge 30c and the inflow angle βd of the bridge 30d are within a range of ± 5 degrees. Therefore, in the range shown in FIG. 3, the flow disturbance mechanism 50 is provided in the bridges 30a, 30b, 30e, and 30f where the inflow angle β exceeds the range of ± 5 degrees.

  Here, FIG. 4 is a perspective view of the bridge 30e including the flow disturbance mechanism 50. FIG. The flow turbulence mechanism 50 expresses a function of disturbing the flow of steam flowing along the flow turbulence mechanism 50.

  This flow disturbance mechanism 50 is provided on a part of one side surface 33a extending from the front edge 32 to the rear edge 34 of the bridges 30a, 30b, 30e, 30f. As shown in FIG. 3, the side surface 33a on which the flow turbulence mechanism 50 is provided is an introduction portion for introducing steam from the steam inlet pipe 220, which is divided by the center line 31 of the bridges 30a, 30b, 30e, and 30f. This is a side surface different from the side surface 33b on the opposite side. In other words, each of the bridges 30a, 30b, 30e, and 30f is a side surface that is far from the flow path center line of the flow path that guides the steam S from the steam inlet pipe 220 between the bridges 30 described above.

  Here, the range in the direction of the trailing edge 34 where the flow turbulence mechanism 50 is provided is set corresponding to the shape of the bridges 30a, 30b, 30e, and 30f, for example. For example, the flow turbulence mechanism 50 is preferably provided corresponding to a region where the separation of the flow easily occurs on the side surface 33a on the front edge 32 side of the bridges 30a, 30b, 30e, and 30f. Moreover, as shown in FIG. 4, the flow disturbance mechanism 50 is provided over the height direction of the bridges 30a, 30b, 30e, and 30f. That is, the flow turbulence mechanism 50 is provided from the root part to the tip part of the bridges 30a, 30b, 30e, and 30f.

  In addition, it is preferable to provide the flow turbulence mechanism 50 in the bridge 30 where the inflow angle β exceeds the range of ± 5 degrees. When the inflow angle β is in the range of ± 5 degrees, the leading edge of the bridge 30 is provided. This is because separation of the flow hardly occurs on the 32 side. On the other hand, when the inflow angle β exceeds the range of ± 5 degrees, flow separation is likely to occur on the front edge 32 side of the bridge 30, and vortices are generated in a part of the flow of the steam S flowing between the bridges 30. This is because the pressure loss is increased.

  In the flow turbulence mechanism 50, for example, the surface roughness of the side surface 33a of the portion that should constitute the flow turbulence mechanism 50 is set to be greater than the surface roughness of the surfaces of the bridges 30a, 30b, 30e, 30f that do not include the flow turbulence mechanism 50. Is also made larger. Further, it is preferable that the surface roughness is gradually increased as the inflow angle β increases. Specifically, in the bridge 30a and the bridge 30b, the surface roughness of the flow disturbance mechanism 50 of the bridge 30a is configured to be larger than the surface roughness of the flow disturbance mechanism 50 of the bridge 30b. Further, in the bridge 30e and the bridge 30f, the surface roughness of the flow disturbance mechanism 50 of the bridge 30f is configured to be larger than the surface roughness of the flow disturbance mechanism 50 of the bridge 30e. Further, the inflow angle β increases in the order of the bridge 30b and the bridge 30a, while the inflow angle β decreases (the absolute value of the inflow angle β increases) in the order of the bridge 30e and the bridge 30f, as shown in FIG. , Shows a positive or negative peak value at a predetermined circumferential angle. It is preferable to gradually increase the surface roughness of the flow turbulence mechanism 50 up to the bridge 30 at the position showing each of these peak values. That is, the flow turbulence mechanism 50 provided in the bridge 30 at the position showing each peak value has the largest surface roughness, in other words, the flow turbulence provided in the bridge 30 at the position showing each peak value. It is preferable that the surface roughness of the control mechanism 50 be configured so as to exhibit a peak value.

  Here, from the bridge 30b to the bridge 30 at the position showing the positive peak value, and from the bridge 30e to the bridge 30 at the position showing the negative peak value, for example, the surface roughness is 1S at the maximum height (Rz). To 20S, it can be configured to gradually increase. Note that 1S is a length obtained by extracting a reference length from the roughness curve in the direction of the average line, and adding the height from the average line to the highest peak and the depth to the lowest valley at the extracted part. Means 1 μm. Also, 20S is a length obtained by extracting a reference length from the roughness curve in the direction of the average line, and adding the height from the average line of the extracted portion to the highest peak and the depth to the lowest valley bottom. Means 20 μm.

  The side surfaces of the bridges 30a, 30b, 30e, and 30f that do not include the flow turbulence mechanism 50 and the side surfaces of the bridges 30a and 30b constitute, for example, a smooth surface having a maximum height (Rz) of about 1S. It is processed as follows.

  Here, an example of gradually increasing the surface roughness of the flow turbulence mechanism 50 from the bridge 30b to the bridge 30 at a position showing a positive peak value and from the bridge 30e to the bridge 30 at a position showing a negative peak value. However, the surface roughness may be changed in the flow disturbance mechanism 50 of one bridge 30.

  For example, in the flow disturbance mechanism 50, the surface roughness may be gradually reduced from the front edge 32 to the rear edge 34 side of the bridge 30a. By configuring in this way, the flow along the side surface 33a on the front edge 32 side, where flow separation is particularly likely to occur, is actively disturbed, and the side surface on the rear edge 34 side where flow separation is less likely to occur than on the front edge 32 side. The surface friction with the steam S in 33a can be reduced.

  Next, the action of the steam S flowing between the bridges 30a, 30b, 30c, 30d, 30e, and 30f shown in FIG. 3 will be described.

  The steam S that is led out from the steam inlet pipe 220 and spreads in the steam flow path 20 flows between the bridges 30a, 30b, 30c, 30d, 30e, and 30f at a predetermined inflow angle β. At this time, for example, the steam S that flows between the bridge 30c and the bridge 30d that does not include the flow turbulence mechanism 50 is formed between the bridge 30c and the bridge 30d in a state where the surface friction on the side surfaces of the bridge 30c and the bridge 30d is small. And flows into the first stage nozzle 213a. In this case, since the surface friction with the steam S on the surface of the bridge 30 is small, the pressure loss can be reduced.

  On the other hand, the steam flowing along the flow disturbance mechanism 50 of the bridges 30a, 30b, 30e, and 30f is disturbed in the boundary layer near the flow disturbance mechanism 50. Therefore, it becomes difficult for the flow to separate and the formation of vortices is suppressed. Thereby, the pressure loss can be reduced. And the vapor | steam in which formation of the vortex was suppressed flows in into the 1st stage nozzle 213a.

  In addition, the passage portion is connected to the entire circumference downstream of the first stage nozzle 213a, and the steam S that has passed through the first stage nozzle 213a is guided to the first stage moving blade 214a.

  As described above, according to the nozzle box 10 of the first embodiment, flow turbulence is generated on a part of the side surface 33a extending from the front edge 32 to the rear edge 34 of the bridge 30 where flow separation is likely to occur. By providing the mechanism 50, flow separation and vortex generation on the front edge 32 side of the bridge 30 can be suppressed. Thus, the steam can be smoothly guided to the first stage nozzle 213a, the pressure loss between the bridges 30 can be suppressed, and the efficiency of the steam turbine can be improved.

  The flow turbulence mechanism 50 is not limited to being configured by increasing the surface roughness of a part of one side surface 33a extending from the front edge 32 to the rear edge 34 of the bridge 30 described above. Absent. FIG. 5 is a perspective view of a bridge 30e provided with a flow disturbance mechanism 50 having another configuration. Here, the bridge 30e is described as an example, but the other bridges 30a, 30b, and 30f including the flow turbulence mechanism 50 have the same configuration.

  As shown in FIG. 5, the flow turbulence mechanism 50 provided on a part of the side surface 33 a extending from the front edge 32 to the rear edge 34 of the bridge 30 e, where flow separation is likely to occur, includes a plurality of protrusions 60. May be. The plurality of protrusions 60 are provided so as to protrude from the side surface 33a at predetermined intervals. Note that at least one protrusion 60 may be provided.

  Here, the protrusion 60 is not particularly limited, and is configured by, for example, a cone such as a cone, a triangular pyramid, or a quadrangular pyramid, or a column such as a cylinder, a triangular prism, or a quadrangular prism. Further, the flow turbulence mechanism 50 may be configured by joining a protrusion 60 formed as a separate body to the side surface 33a. However, in order to prevent separation from the side surface 33a, the side surface 33a is subjected to machining or the like. Therefore, it is preferable to be integrated with the side surface 33a.

  In addition, as in the case of the flow turbulence mechanism 50 configured by increasing the surface roughness of a part of the side surface 33a extending from the front edge 32 to the rear edge 34 of the bridge 30 described above, It is preferable that the height of the protrusion 60 is gradually increased with the increase. Specifically, in the bridge 30a and the bridge 30b, the height of the protrusion 60 of the flow disturbance mechanism 50 of the bridge 30a is configured to be higher than the height of the protrusion 60 of the flow disturbance mechanism 50 of the bridge 30b. . Further, in the bridge 30e and the bridge 30f, the height of the protrusion 60 of the flow disturbance mechanism 50 of the bridge 30f is configured to be higher than the height of the protrusion 60 of the flow disturbance mechanism 50 of the bridge 30e. Further, the inflow angle β increases in the order of the bridge 30b and the bridge 30a, while the inflow angle β decreases (the absolute value of the inflow angle β increases) in the order of the bridge 30e and the bridge 30f, as shown in FIG. , Shows a positive or negative peak value at a predetermined circumferential angle. It is preferable to gradually increase the height of the protrusion 60 of the flow turbulence mechanism 50 to a position showing each of these peak values. That is, the flow provided in the bridge 30 at the position indicating the peak value is set so that the height of the protrusion 60 of the flow disturbance mechanism 50 provided in the bridge 30 at the position indicating each peak value is the highest. It is preferable that the height of the protrusion 60 of the disturbing mechanism 50 be configured to show a peak value.

  Here, the height of the protrusion 60 is, for example, from 0.1 mm to 2 mm from the bridge 30 b to the bridge 30 at a position showing a positive peak value and from the bridge 30 e to the bridge 30 at a position showing a negative peak value. It can be configured to gradually increase within the range.

  Here, an example is shown in which the height of the protrusion 60 is gradually increased from the bridge 30b to the bridge 30 at a position showing a positive peak value, and from the bridge 30e to the bridge 30 at a position showing a negative peak value. For example, in the flow disturbance mechanism 50 of one bridge 30, the height of the protrusion 60 may be changed.

  For example, in the flow disturbance mechanism 50, the height of the protrusion 60 may be gradually decreased from the front edge 32 to the rear edge 34 side of the bridge 30a. By configuring in this way, the flow along the side surface 33a on the front edge 32 side, where flow separation is particularly likely to occur, is actively disturbed, and the side surface on the rear edge 34 side where flow separation is less likely to occur than on the front edge 32 side. The surface friction with the steam S in 33a can be reduced.

  In this way, by configuring the flow disturbance mechanism 50 with the protrusion 60, the surface roughness of a part of the side surface 33a extending from the front edge 32 to the rear edge 34 of the bridge 30 is increased. The same effect as that provided with the flow turbulence mechanism 50 can be obtained.

  That is, the flow disturbance mechanism 50 is provided on a part of the side surface 33a extending from the front edge 32 to the rear edge 34 of the bridge 30 where flow separation is likely to occur, so that the flow on the front edge 32 side of the bridge 30 is reduced. Separation and vortex generation can be suppressed. Thus, the steam can be smoothly guided to the first stage nozzle 213a, the pressure loss between the bridges 30 can be suppressed, and the efficiency of the steam turbine can be improved. Further, since the height of the protrusion 60 can be configured in the above-described range, the flow can be disturbed beyond the boundary layer region formed on the flow disturbing mechanism 50.

(Nozzle box of the second embodiment)
The nozzle box 10 of the second embodiment according to the present invention has the same configuration as the nozzle box 10 of the first embodiment described above except that the configuration of the flow disturbance mechanism 50 of the bridge 30 is different. Therefore, here, the flow disturbing mechanism 50 of the bridge 30 in the nozzle box 10 of the second embodiment will be mainly described.

  Note that the nozzle box 10 of the second embodiment according to the present invention will also be described with reference to FIG. 3 in the same manner as the nozzle box 10 of the first embodiment, and here again the inflow angle βc of the bridge 30c. In the following description, it is assumed that the inflow angle βd of the bridge 30d is within a range of ± 5 degrees. Therefore, in the range shown in FIG. 3, the flow disturbance mechanism 50 is provided in the bridges 30a, 30b, 30e, and 30f where the inflow angle β exceeds the range of ± 5 degrees.

  FIG. 6 is a perspective view of a bridge 30e having a flow turbulence mechanism 50 provided in the nozzle box 10 according to the second embodiment of the present invention. Here, the bridge 30e is described as an example, but the other bridges 30a, 30b, and 30f including the flow turbulence mechanism 50 have the same configuration.

  The flow turbulence mechanism 50 provided in the bridge 30e of the nozzle box 10 of the second embodiment includes an airflow generation device 70 that generates an airflow in a predetermined direction by converting a part of the surrounding gas into plasma. Is done.

  The airflow generation device 70 includes a solid dielectric 71, a first electrode 72 provided on one surface 71 a of the dielectric 71, and the first electrode 72 in the vicinity of the other surface 71 b of the dielectric 71. And a second electrode 73 provided in an opposing manner. Further, the first electrode 72 and the second electrode 73 are disposed with the dielectric 71 interposed therebetween without being in direct contact. The first electrode 72 and the second electrode 73 are connected to a discharge power source (not shown) for applying a voltage between the electrodes, for example, via a cable.

  Here, the airflow generating device module in which the airflow generating devices having a plurality of the above-described configurations are integrally formed is a recess formed on a part of one side surface 33a extending from the front edge 32 to the rear edge 34 of the bridge 30e. A configuration in which the joint is fitted and joined is illustrated. Note that the airflow generation device module only needs to include at least one airflow generation device having the above-described configuration.

  Since the airflow generation device 70 is used in a high temperature environment, the dielectric 71 is preferably composed of a ceramic material whose main component is, for example, aluminum nitride, alumina, zirconia, hafnia, titania, silica, or the like.

  The first electrode 72 and the second electrode 73 have a thin plate shape, for example, and are appropriately selected from known conductive materials according to the environment in which the airflow generation device 70 is used. In addition, as a material constituting the first electrode 72 and the second electrode 73, for example, stainless steel, Inconel (trade name), Hastelloy (trade name), titanium, platinum, tungsten, molybdenum, nickel, copper, gold, silver Examples thereof include metals such as chromium, alloys containing these metal elements as main components, and good inorganic conductors such as conductive ceramics. From these conductive materials, it can be appropriately selected and used according to the environment in which the airflow generator 70 is used.

  In particular, when a heat-resistant or corrosion-resistant metal such as Inconel, Hastelloy, or titanium is used for the conductor, it is possible to realize an electrode that can be used for a long time even in a high-corrosion atmosphere such as high temperature and high humidity and oxidation. it can.

  In the example shown in FIG. 6, one surface of the first electrode 72 is configured to be flush with the one surface 71 a of the dielectric 71, but the first electrode 72 is a dielectric. It may be configured to be embedded in 71. In addition, for example, when the bridge 30e is made of metal, the second electrode 73 is preferably configured to be embedded in the dielectric 71 in order to prevent contact with the bridge 30e.

  Next, the operation of the airflow generation device 70 will be described.

  When a voltage is applied between the first electrode 72 and the second electrode 73 from a discharge power source (not shown) and a potential difference equals or exceeds a certain threshold value, the first electrode 72 and the second electrode 73 Discharge occurs during A discharge plasma is generated along with this discharge. Here, since the dielectric 71 is interposed between the first electrode 72 and the second electrode 73, the dielectric barrier can be maintained stably without arc discharge even at high temperatures. Discharge occurs. The dielectric barrier discharge is a creeping discharge formed along one surface 71 a of the dielectric 71. This dielectric barrier discharge generates an air flow 74 in a predetermined direction.

  Here, by changing the installation position of the first electrode 72 and the second electrode 73 of the airflow generation device 70, the voltage applied between the first electrode 72 and the second electrode 73, etc., the bridge The air flow 74 generated on the side surface 33a of the bridge 30e may be generated in the direction from the front edge 32 side to the rear edge 34 side of the bridge 30e or in the direction from the rear edge 34 side to the front edge 32 side of the bridge 30e. it can. Therefore, the direction of the air flow 74 generated on the side surface 33a of the bridge 30e can be appropriately changed according to the method for controlling the flow of the steam S flowing along the side surface 33a of the bridge 30e.

  Here, an airflow generation device module in which a plurality of airflow generation devices each including the dielectric 71, the first electrode 72, and the second electrode 73 is integrally formed is connected from the front edge 32 to the rear edge 34 of the bridge 30e. Although the structure which fits into the recessed part formed in a part of side 33a over a direction and joined is illustrated, it is not restricted to this structure. For example, the bridge 30e may be made of a dielectric made of the above ceramic material. In this case, for example, the first electrode 72 is provided on a part of the side surface 33a extending from the front edge 32 to the rear edge 34 of the bridge 30e. Further, the second electrode 73 is embedded, for example, at a position facing the first electrode 72 in the bridge 30e.

  Next, the action of the steam S flowing between the bridges 30a, 30b, 30c, 30d, 30e, and 30f of the nozzle box 10 of the second embodiment will be described with reference to FIGS.

  The steam S that is led out from the steam inlet pipe 220 and spreads in the steam flow path 20 flows between the bridges 30a, 30b, 30c, 30d, 30e, and 30f at a predetermined inflow angle β. At this time, for example, the steam S that flows between the bridge 30c and the bridge 30d that does not include the flow turbulence mechanism 50 is formed between the bridge 30c and the bridge 30d in a state where the surface friction on the side surfaces of the bridge 30c and the bridge 30d is small. And flows into the first stage nozzle 213a. In this case, since the surface friction with the steam S on the surface of the bridge 30 is small, the pressure loss can be reduced.

  On the other hand, when the airflow generation device 70 is configured so that the airflow 74 flowing from the front edge 32 side to the rear edge 34 side of the bridge 30e is generated, it is generated by applying a voltage to the airflow generation device 70. The airflow 74 suppresses the deceleration of the steam S in the vicinity of the side surface 33a of the bridges 30a, 30b, 30e, and 30f. Therefore, it becomes difficult for the flow to separate and the formation of vortices is suppressed. Thereby, the pressure loss can be reduced. Further, when the airflow generation device 70 is configured so that the airflow 74 flowing from the rear edge 34 side to the front edge 32 side of the bridge 30e is generated, it is generated by applying a voltage to the airflow generation device 70. The air flow 74 disturbs the flow in the boundary layer. Therefore, it becomes difficult for the flow to separate and the formation of vortices is suppressed. Thereby, the pressure loss can be reduced. And the vapor | steam in which formation of the vortex was suppressed flows in into the 1st stage nozzle 213a.

  In addition, the passage portion is connected to the entire circumference downstream of the first stage nozzle 213a, and the steam S that has passed through the first stage nozzle 213a is guided to the first stage moving blade 214a.

  As described above, according to the nozzle box 10 of the second embodiment, the flow is disturbed on a part of the side surface 33a extending from the front edge 32 to the rear edge 34 of the bridge 30 where flow separation is likely to occur. By providing the mechanism 50, flow separation and vortex generation on the front edge 32 side of the bridge 30 can be suppressed. Thus, the steam can be smoothly guided to the first stage nozzle 213a, the pressure loss between the bridges 30 can be suppressed, and the efficiency of the steam turbine can be improved.

  Although the present invention has been specifically described above with reference to the embodiments, the present invention is not limited to these embodiments, and various modifications can be made without departing from the scope of the invention.

  DESCRIPTION OF SYMBOLS 10 ... Nozzle box, 30, 30a, 30b, 30c, 30e, 30f ... Bridge, 20 ... Steam flow path, 31 ... Center line, 32 ... Front edge, 33a, 33b ... Side, 34 ... Rear edge, 50 ... Flow disturbance , 60 ... protrusion, 70 ... air flow generator, 71 ... dielectric, 71a, 71b ... surface, 72 ... first electrode, 73 ... second electrode, 74 ... air flow, 200 ... steam turbine, 210 ... inside Casing 211 211 Outer casing 212 Turbine rotor 213 Nozzle 213a First stage nozzle 214 Rotor blade 214a First stage rotor blade 215a 215b Grand labyrinth section 220 Steam inlet pipe

Claims (8)

Steam turbine nozzle configured to guide the steam introduced from the steam inlet pipe and flowing into the steam flow path extending in the circumferential direction to the first stage nozzle through the reinforcing members arranged in a certain direction in the circumferential direction A box,
The plurality of reinforcing members arranged in the upstream side of the first stage nozzle are configured in an airfoil shape having a leading edge and a trailing edge, and the front of at least one of the reinforcing members among the plurality of reinforcing members. A nozzle box for a steam turbine, comprising a flow turbulence mechanism for disturbing a flow of steam at a part of one side surface extending from an edge toward a rear edge.   Among the plurality of reinforcing members, when the reinforcing member has a reinforcing member in which the inflow angle of the steam introduced from the steam inlet pipe at the front edge of the reinforcing member is within a range of ± 5 degrees, the reinforcement other than the reinforcing member The steam turbine nozzle box according to claim 1, wherein the member is provided with the flow disturbance mechanism.   The side surface on which the flow disturbing mechanism is provided is different from the side surface facing the introduction portion for introducing steam from the steam inlet pipe, which is divided by a center line from the front edge to the rear edge of the reinforcing member. The nozzle box for a steam turbine according to claim 1, wherein the nozzle box is a side surface on the side.   The flow turbulence mechanism is configured by making the surface roughness of the side surface to be provided with the flow turbulence mechanism larger than the surface roughness of the side surface of the reinforcing member not having the flow turbulence mechanism. The nozzle box for a steam turbine according to any one of claims 1 to 3.   In the reinforcing members arranged in the circumferential direction, when the change in the inflow angle of the steam introduced from the steam inlet pipe at the front edge of the reinforcing member is shown in the circumferential direction, the inflow angle is positive or 5. The nozzle box for a steam turbine according to claim 4, wherein a surface roughness of a side surface of a portion constituting the flow turbulence mechanism is gradually increased toward the reinforcing member exhibiting a negative peak value.   The steam turbine nozzle box according to any one of claims 1 to 3, wherein the flow turbulence mechanism includes one or a plurality of protrusions.   In the reinforcing members arranged in the circumferential direction, when the change in the inflow angle of the steam introduced from the steam inlet pipe at the front edge of the reinforcing member is shown in the circumferential direction, the inflow angle is positive or The nozzle box for a steam turbine according to claim 6, wherein the height of the protrusion gradually increases toward the reinforcing member exhibiting a negative peak value. Steam turbine nozzle configured to guide the steam introduced from the steam inlet pipe and flowing into the steam flow path extending in the circumferential direction to the first stage nozzle through the reinforcing members arranged in a certain direction in the circumferential direction A steam turbine with a box,
A steam turbine, wherein the nozzle box is the nozzle box for a steam turbine according to any one of claims 1 to 7.

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