JP5926888B2 - Steam turbine nozzle segment having an arcuate joint - Google Patents

Description

  The subject matter disclosed herein relates to a steam turbine nozzle assembly or diaphragm stage. Specifically, the subject matter disclosed herein relates to a steam turbine nozzle assembly having a plurality of nozzle segments having arcuate or “conical” (eg, arcuate concave, arcuate convex) joints. .

  A steam turbine includes a fixed nozzle (or “airfoil”) segment that directs a flow of working fluid into a turbine bucket coupled to a rotating rotor. The complete assembly of nozzle segments is commonly referred to as the steam turbine diaphragm stage. One way to assemble the diaphragm stage is to weld (or alternatively braze) multiple single airfoils (“fixed nozzle blades” or “singlets”) with integral side walls to the inner and outer rings. It is. Each of these singlets has joints (in the form of inner and outer rings) to which adjacent singlets are welded or brazed. These joints include an axial leading edge section (or “pressure side” section) oriented parallel to the axis of the steam turbine and an inclined trailing edge section (or “pressure side” section). While current singlet designs with angled joint sections allow tight fits between individual segments, these angled joints make it almost impossible to remove and repair individual segments.

US Pat. No. 7,427,187

  A steam turbine nozzle segment having a conical joint is disclosed. In one embodiment, the steam turbine stationary nozzle blade includes an airfoil, an inner side wall integral with the first side of the airfoil, and an outer side wall integral with the second side of the airfoil. The side wall and the outer side wall each include a pressure side having an arcuate concave surface extending substantially the entire length of the side wall, and a suction side having an arcuate convex surface extending substantially the entire length of the side wall.

  A first aspect of the present invention includes a steam turbine stationary nozzle blade, the steam turbine stationary nozzle blade including an airfoil, an inner side wall integral with the first side of the airfoil, and an airfoil first. Two side surfaces and an integral outer sidewall, each of the inner and outer sidewalls having a pressure side having an arcuate concave surface extending substantially the entire length of the sidewall and an arcuate shape extending substantially the entire length of the sidewall. And a suction side having a convex surface.

  A second aspect of the invention includes a steam turbine diaphragm assembly that includes an outer diaphragm ring, an inner diaphragm ring, and a fixed nozzle blade disposed between the inner diaphragm ring and the outer diaphragm ring. Each of the fixed nozzle blades includes an airfoil, an inner side wall integral with the first side of the airfoil, and an outer side wall integral with the second side of the airfoil, The inner and outer sidewalls each include a pressure side having an arcuate concave surface extending substantially the entire length of the side wall, and a suction side having an arcuate convex surface extending substantially the entire length of the side wall; At least one of the fixed nozzle blades is removably attached to another one of the fixed nozzle blades.

  A third aspect of the present invention includes a steam turbine diaphragm assembly, the steam turbine diaphragm assembly comprising an outer diaphragm ring, an inner diaphragm ring, and a fixed nozzle blade disposed between the inner diaphragm ring and the outer diaphragm ring. And a plurality of pairs of removable weld joints, each pair of which substantially removably secures one of the stationary nozzle blades to one of the outer diaphragm ring or the inner diaphragm ring, Each stationary nozzle blade includes an airfoil, an inner side wall integral with the first side of the airfoil, and an outer side wall integral with the second side of the airfoil, wherein the inner side wall and the outer side wall are each A pressure side having an arcuate concave surface extending over substantially the entire length of the side wall; and an arcuate convex surface extending over substantially the entire length of the side wall. And a suction side having, at least one fixed nozzle blade mounted removably in the axial direction with respect to another one of the static nozzle blades.

  These and other features of the present invention will be more readily understood from the following detailed description of various aspects of the invention, taken in conjunction with the accompanying drawings which illustrate various embodiments of the invention. .

FIG. 3 is a top plan view of the steam turbine nozzle assembly. 3 is a three-dimensional perspective view of a steam turbine nozzle assembly. FIG. FIG. 3 is a partial three-dimensional perspective view of a steam turbine diaphragm assembly. The three-dimensional perspective view of the steam turbine fixed nozzle blade by embodiment. 3 is a three-dimensional perspective view of a plurality of steam turbine fixed nozzle blades according to an embodiment. FIG. 3 is a three-dimensional perspective view of a plurality of steam turbine fixed nozzle blades according to an embodiment. FIG. FIG. 3 is a partial three-dimensional perspective view of a steam turbine diaphragm assembly according to an embodiment.

  It should be noted that the drawings of the present invention are not to scale. The drawings are only intended to illustrate exemplary embodiments of the invention and therefore should not be considered as limiting the scope of the invention. In the drawings, like numbering represents like elements between the drawings.

  As indicated above, aspects of the present invention provide a steam turbine nozzle segment having a conical joint. Specifically, aspects of the present invention provide a steam turbine nozzle assembly with a plurality of nozzle segments having arcuate or “conical” (eg, arcuate concave, arcuate convex) joints. These arcuate joints can allow for removal and / or repair of individual nozzle segments while maintaining the structural integrity of the nozzle assembly.

  Referring to the drawings, FIGS. 1-2 show a nozzle assembly 100 for a steam turbine (not shown). FIG. 1 shows a plan view of the nozzle assembly 100, while FIG. 2 shows a three-dimensional schematic view of the nozzle assembly 100. The nozzle assembly 100 includes a stationary nozzle blade 10 with at least one airfoil 12 having an inner side wall 14 and an outer side wall 16. The nozzle assembly 100 further includes an inner ring 18 and an outer ring 20. As used herein, inner and outer refer to radial positions relative to a rotor (not shown) to which the inner end of the airfoil 12 is coupled via an inner ring 18. Yes. Inner ring 18 and inner side wall 14 (and similarly outer ring 20 and outer side wall 16) are joined together at a joint, which is the entire area where the rings and side walls are adjacent and joined. Please understand that it means. Inner ring 18 and inner side wall 14 (and similarly outer ring 20 and outer side wall 16) are welded together (or alternatively brazed) at several points in joint 80 (FIG. 1). It should be understood that brazing can be performed as an alternative to welding, as described herein. As is known in the art, welding and brazing can be used to join metals together. As is further known in the art, welding can be performed by melting the metals and fusing the metals together, and usually by adding a filler material. On the other hand, brazing usually does not require melting of the base materials to be joined and is usually performed at a lower temperature than welding. Although the metal joints are described herein as “welded joints”, it should be understood that the metal joints can alternatively be described as “brazed joints”.

  Referring to FIG. 1, the multiple weld regions of the welded joints on both the inlet (front) side of the airfoil 12 and the outlet (rear surface) side of the airfoil 12 are shown in FIGS. The entirety is shown as a welded joint 90. The joints 80 between the rings 18, 20 and the side walls 14, 16 can each include a mechanical radial stop 19 that holds the airfoil 12 in the correct radial position and prevents weld shrinkage during the welding process. Each joint 80 may further include a mechanical axial stop 17 that holds the airfoil 12 in the correct axial position and controls the weld depth. These mechanical stops 17, 19 include a series of male stepped interconnections engaged with corresponding female stepped portions of the complementary portion as described in more detail herein.

  Turning to FIG. 3, the nozzle assembly 100 of FIG. 2 is shown, and the nozzle assembly 100 is further disposed within a portion of the diaphragm assembly (the complete assembly is omitted for clarity). A plurality of fixed nozzle blades 10 are included. As shown, the side walls 14, 16 of the fixed nozzle blade 10 can include a slanted joint 34 (eg, a “dog leg” joint with two surfaces oriented at an obtuse angle). These inclined joints 34 may allow a plurality of fixed nozzle blades to be placed in the nozzle assembly 100 with substantially close contact with each other. As illustrated, the plurality of fixed nozzle blades 10 are held in the inner and outer rings 18, 20 by a plurality of welds 90.

  Turning to FIG. 4, a steam turbine stationary nozzle blade 110 according to an embodiment is shown. The fixed nozzle blade 110 can include an airfoil 112, an inner side wall 114, and an outer side wall 116. As shown, the inner side wall 114 can be integral with the first side of the airfoil 112 (eg, by machining from a forging or block, welding, casting, brazing, etc.) The outer sidewall 116 can also be integral with the second side of the airfoil 112 (eg, by machining from a forging or block, welding, casting, brazing, etc.). Inner sidewall 114 and outer sidewall 116 can each include a pressure side 124 and a suction side 126. The terms “pressure side” and “pressure side” correspond to the pressure side and suction side of the airfoil 112, respectively. As is known in the art, the pressure side of the airfoil 112 is a high pressure side designed to guide the flow of working fluid through the fixed nozzle blade 110. As is known in the art, the suction side of the airfoil 112 is a lower pressure side that is generally opposite the pressure side. Each pressure side 124 can have an arcuate concave surface 134 and each suction side 126 can have an arcuate convex surface 136. In one embodiment, the arcuate concave surface 134 can extend substantially the entire length L of the side walls 114, 116, respectively, and the arcuate convex surface 136 can extend the entire length L of the side walls 114, 116, respectively. be able to. In one embodiment, the arcuate concave surface 134 of the inner sidewall 114 has an arc radius that is approximately equal to the arcuate convex surface 136 of the inner sidewall 114. Further, in this embodiment, the arcuate concave surface 134 of the outer sidewall 116 and the arcuate convex surface 136 of the outer sidewall 116 can have approximately equal arc radii. In addition, in this embodiment, arcuate concave surface 134 of inner sidewall 114 and outer sidewall 116, respectively, can have an arc length that is approximately equal to the arcuate convex surface 136 of inner sidewall 114 and outer sidewall 116, respectively. .

  With continued reference to FIG. 4, in one embodiment, the arcuate concave surface 134 of the inner side wall 114 and the arcuate concave surface 134 of the outer side wall 116 are the arcuate convex surface 136 of the inner side wall 114 and the arcuate convex surface 136 of the outer side wall 116, respectively. Complements (and is complementary to) the arcuate convex surface 136. That is, in a configuration with more than one steam turbine stationary nozzle blade 110 (FIGS. 5-7), the arcuate convex surface 136 of the inner sidewall 114 of the first steam turbine stationary nozzle blade 110 is the second Complementary to the arcuate concave surface 134 of the inner side wall 114 on the (other) similar steam turbine stationary nozzle blade 110. Similarly, the arcuate convex surface 136 of the outer side wall 116 of the first steam turbine stationary nozzle blade 110 is complementary to the arcuate concave surface 134 of the outer side wall 116 of the second similar steam turbine stationary nozzle blade 110. . As used herein, the term “complementary” refers to a relationship between surfaces that allows portions of those surfaces to be placed in close contact with each other. For example, in one embodiment, the pressure side (arched concave) surface and the suction side (arched convex) surface of each (inner, outer) arcuate concave surface of the first steam turbine stationary nozzle blade 110. Each can be positioned within the steam turbine diaphragm assembly such that it is in close contact with the respective (inner, outer) arcuate convex surface of the second steam turbine stationary nozzle blade 110 (FIG. 7). The relationship between the pressure side surface and the suction side surface will be further described with reference to FIGS.

  Turning to FIGS. 5 and 6, a configuration with a plurality of substantially similar steam turbine stationary nozzle blades 110 is shown. In these configurations, the steam turbine stationary nozzle blades 110 can be arranged such that their complementary surfaces (the arcuate concave surface 134 and the arcuate convex surface 136, respectively) are in close contact with each other. This makes it possible, among other things, to efficiently deliver steam and obtain mechanical stability across the airfoil 112. FIG. 5 shows a configuration with a plurality of steam turbine stationary nozzle blades 110 of FIG. 4 and additional substantially similar blades to form part of the steam turbine diaphragm assembly (diaphragm rings are omitted). ). As described with respect to FIG. 5 and more clearly shown in FIG. 6, a portion of the steam turbine diaphragm assembly is formed by placing complementary conical surfaces of the steam turbine stationary nozzle blade 110 in close contact with each other. be able to. Referring to FIG. 7, in a more complete diaphragm assembly, a plurality of steam turbine stationary nozzle blades 110 can be removably attached to one another in the axial direction (referenced “A”). This removable attachment provides one or more steam turbine stationary nozzle blades 110 from the assembly without substantially compromising the structural integrity (eg, welded joint 190) of the remainder of the assembly. Can be removed in the axial direction.

  Turning to FIG. 7, a portion of a steam turbine diaphragm assembly 200 according to an embodiment is shown. A portion of the steam turbine diaphragm assembly 200 may include a plurality of fixed steam turbine nozzle blades 110 with complementary surfaces disposed in generally close contact as described with respect to FIGS. Further, a portion of the steam turbine diaphragm assembly 200 can include an inner diaphragm ring 118 and an outer diaphragm ring 120 that are shown and described with respect to FIGS. 1-3. Can be substantially similar to their inner and outer rings (18 and 20). In a complete diaphragm assembly (not shown for clarity), a plurality of steam turbine stationary nozzle blades 110 can form an annulus between the inner diaphragm ring 118 and the outer diaphragm ring 120. . In this configuration, the plurality of steam turbine fixed nozzle blades 110 can be detachably attached to each other. Further, the plurality of steam turbine stationary nozzle blades 110 may be substantially removably secured to at least one of the inner diaphragm ring 118 and the outer diaphragm ring 120 by a plurality of removable weld joints 190. That is, if the steam turbine stationary nozzle blade 110 is not secured to at least one of the inner diaphragm ring 118 and the outer diaphragm ring 120, the steam turbine stationary nozzle blade 110 may have one or more adjacent steams. The weld joint 190 of the turbine fixed nozzle blade 110 can be removed from the steam turbine diaphragm assembly 200 without removal.

  In the nozzle assembly 100 of FIG. 3, when the complete annular band of the fixed nozzle blades 10 is assembled and welded (or alternatively brazed), each fixed nozzle blade 10 includes a plurality of nozzle blades 10 (and their nozzle blades 10). It cannot be removed from the assembly 100 without removing the corresponding welded joint 90 or brazed joint). This is the reason why the movement of the adjacent blades 10 is hindered by the inclined joints 34 (FIG. 3) of the plurality of blades 10 even when the welded joint 90 is removed. Specifically, as shown in FIG. 3, the inclined joint portions 34 of the plurality of blades 10 prevent the blades from moving in the axial direction (“A”). In contrast, the plurality of steam turbine stationary nozzle blades 110 of the embodiment (eg, FIG. 7) are removably attached to each other. That is, each steam turbine fixed nozzle blade 110 that is not fixed to one of the inner diaphragm ring 118 and the outer diaphragm ring 120 has two fixed (eg, welded) steam turbine fixed nozzles in the axial direction (A). It can be removed from between the blades 110 or inserted between the two fixed (eg, welded) steam turbine fixed nozzle blades 110. In other words, in the steam turbine diaphragm assembly 200, each steam turbine fixed nozzle blade 110 can be removably attached in an axial direction to an adjacent steam turbine fixed nozzle blade 110. Further, in one embodiment, each steam turbine fixed nozzle blade 110 is attached to at least one of the inner diaphragm ring 118 and the outer diaphragm ring 120 by only a plurality of removable weld joints 190 (or alternatively, brazed joints). On the other hand, it is fixed substantially removably.

  Steam turbine fixed nozzle blades 110 with a conical (arched concave, arcuate convex) joint as described herein are those removable weld joints associated with the individual blades to be removed. Removing individual blades 110 from an assembly (eg, steam turbine diaphragm assembly 200) by removing only 190 (or brazed joints) (eg, grinding, machining and / or heating). to enable. This can enable, among other things, quicker and more efficient repair, replacement and / or enhancement of individual steam turbine stationary nozzle blades 110.

  The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, an expression without a numeral is intended to also include a plurality of forms unless the context clearly indicates otherwise. Further, as used herein, the terms “include” and / or “include” specify the presence of the described feature, number, step, operation, element, and / or component, but one It should be understood that this does not exclude the presence or addition of other features, times, steps, steps, operations, elements, components and / or groups thereof.

  This written description uses examples, including the best mode, to disclose the invention, and to enable any person skilled in the art to make and use any device or system and perform any embedded method. It also makes it possible to do. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are where they have structural elements that do not differ from the language of the claims, or where they contain equivalent structural elements that have non-essential differences from the language of the claims. Is intended to fall within the scope of the claims.

DESCRIPTION OF SYMBOLS 10 Fixed nozzle blade 12 Airfoil part 14 Inner side wall 16 Outer side wall 17 Mechanical axial stopper 18 Inner ring 19 Mechanical radial stopper 20 Outer ring 34 Inclined joint 80 Joint 90 Weld joint 100 Nozzle assembly 110 Fixed nozzle blade 112 Airfoil 114 Inner Side Wall 116 Outer Side Wall 118 Inner Diaphragm Ring 120 Outer Diaphragm Ring 124 Pressure Side 126 Suction Side 134 Arcuate Concave Surface 136 Arcuate Convex Surface 190 Removable Weld Joint 200 Steam Turbine Diaphragm Assembly L Sidewall Total length A Axial direction

Claims (7)

A steam turbine diaphragm assembly (200), comprising:
An outer diaphragm ring (120);
An inner diaphragm ring (118);
An annular band of fixed nozzle blades (110) disposed between the inner diaphragm ring (118) and the outer diaphragm ring (120);
A plurality of pairs of removable, each pair of which substantially removably secures one of the fixed nozzle blades (110) to one of the outer diaphragm ring (120) or the inner diaphragm ring (118). A welded joint (190);
Including
Each fixed nozzle blade (110)
An airfoil (112);
An inner sidewall (114) integral with a first side of the airfoil (112);
An outer sidewall (116) integral with a second side of the airfoil (112);
Including
The inner sidewall (114) and the outer sidewall (116) are each
A pressure side (124) having an arcuate concave surface (134) extending over substantially the entire length (L) of the side wall;
A suction side (124) having an arcuate convex surface (136) extending over substantially the entire length (L) of the side wall;
Including
At least one of the fixed nozzle blades (110) is removably attached to another one of the fixed nozzle blades (110) in the axial direction (A) of the fixed nozzle blade (110);
Steam turbine diaphragm assembly (200).   The steam turbine diaphragm assembly (200) of claim 1, wherein each pair of removable weld joints (190) substantially retains an axial position of the fixed removable fixed nozzle blade (110). ).   The steam turbine diaphragm set of claim 1 or 2, wherein the arcuate concave surface (134) of the inner sidewall (114) and the arcuate convex surface (136) of the inner sidewall (114) have substantially equal arc radii. Solid (200).   Steam according to any of claims 1 to 3, wherein the arcuate concave surface (134) of the outer side wall (116) and the arcuate convex surface (136) of the outer side wall (116) have substantially equal arc radii. Turbine diaphragm assembly (200).   The arcuate concave surface (134) of the inner side wall (114) and the arcuate concave surface (134) of the outer side wall (116) are respectively the arcuate convex surface (136) and the outer side wall of the inner side wall (114). A steam turbine diaphragm assembly (200) according to any of the preceding claims, wherein the steam turbine diaphragm assembly (200) is complementary to the arcuate convex surface (136) of (116).   The arcuate concave surface (134) of the inner side wall (114) and the arcuate convex surface (136) of the inner side wall (114) have substantially equal arc lengths. Steam turbine diaphragm assembly (200). The arcuate concave surface (134) of the outer side wall (116) and the arcuate convex surface (136) of the outer side wall (116) have substantially equal arc lengths. Steam turbine diaphragm assembly (200).