JP7106552B2 - A steam turbine with an airfoil (82) having a backside camber. - Google Patents

Description

This application and the resulting patent relate generally to any type of axial flow turbine, and more specifically to controlled flow runners for steam turbines.

Generally speaking, a steam turbine or the like may have a predetermined steam path that includes a steam inlet, a turbine section, and a steam outlet. Leakage of steam flowing out of or into the steampath from areas of higher pressure to areas of lower pressure can adversely affect the operating efficiency of the steam turbine. For example, steam path leakage within the steam turbine between the rotating shaft and the surrounding turbine casing can reduce the overall efficiency of the steam turbine.

Steam generally flows through several turbine stages, generally arranged in series, passing through the guides and blades (or nozzles and buckets) of the first stage and then through the guides and blades of subsequent stages of the turbine. In this way, the guides can direct steam to the respective blades to rotate the blades and drive loads such as generators. Steam can be contained by a circumferential shroud surrounding the blades, which can also help direct the steam or combustion gases along the path. As such, the turbine guides, blades, and shrouds can be exposed to high temperatures caused by the steam, which can result in the formation of hot spots and high thermal stresses in these components. . Since the efficiency of a steam turbine depends on its operating temperature, components located along the steam or hot gas path have continual requirements that they can withstand higher and higher temperatures without failure or reduction in service life. I have a request.

Certain turbine blades may be formed with an airfoil shape. The blade can be attached to the tip and root, and the root is used to connect the blade to the disk or drum. The shape and dimensions of turbine blades result in certain profile losses, secondary losses, leakage losses, mixing losses, etc., which can adversely affect the efficiency and/or performance of the steam turbine.

U.S. Patent Application Publication No. 2016/0237833

This application and the resulting patent provide a controlled flow runner for use in steam turbines. Examples of controlled flow runners include a tip shroud and a blade adjacent to the tip shroud and having a top width, an intermediate width, and a bottom width, the intermediate width being less than the top width and the bottom width; Root attachments below may also be included.

This application and the resulting patent further provide a method of using a steam turbine controlled flow runner. The method may include providing a root for the controlled flow runner, coupling a blade for the controlled flow runner to the root, the blade including a top width, a middle width, and a bottom width. The intermediate width can be less than the top and bottom widths, and the method includes coupling the tip to the blade.

This application and the resulting patent further provide a steam turbine with a controlled flow runner. The steam turbine may include a disk, a first controlled flow guide attached to the inner casing, and a first controlled flow runner coupled to the disk adjacent the first controlled flow guide. can. A first controlled flow runner can include a first blade. The first blade may have a top width at a first radial distance from the disk, an intermediate width at a second radial distance from the disk, and a bottom width at a third radial distance from the disk. The intermediate width may be less than the top width and the bottom width, and the second radial distance may be greater than the first radial distance and less than the third radial distance.

These and other features and improvements of the present application and the resulting patent will become apparent to those of ordinary skill in the art, by considering the following detailed description in conjunction with the several drawings and the appended claims. will become clear to

1 is a schematic diagram of a steam turbine; FIG. 2 is a schematic diagram of part of a turbine that can be used in the steam turbine of FIG. 1, showing several turbine stages; FIG. 3 is a front view of a turbine blade that can be used in the turbine of FIG. 2; FIG. 1 is a cross-sectional side view of a portion of a steam turbine with controlled flow runners as described herein; FIG. 1A-1D show various perspective and side views of controlled flow runners described herein. 1 schematically illustrates an example view of a portion of a turbine and a back deflection angle, according to one embodiment of the present disclosure; FIG.

Referring now to the drawings, like numerals refer to like elements throughout the several views, FIG. 1 shows a schematic diagram of an example steam turbine 10 . Generally described, steam turbine 10 may include high pressure section 15 and intermediate pressure section 20 . Other pressures in other sections can also be used here. A shell or casing 25 can be axially split into an upper half 30 and a lower half 35 . A central portion 40 of casing 25 may include a high pressure steam inlet 45 and an intermediate pressure steam inlet 50 . Within casing 25 , high pressure section 15 and intermediate pressure section 20 may be centered about rotor or disk 55 . Disk 55 may be supported by several bearings 60 . A steam seal unit 65 may be positioned inside each bearing 60 . An annular section divider 70 may extend radially inward from the central portion 40 toward the disc. Compartment 70 may include several packing casings 75 . Other components and other configurations are also possible.

In operation, high pressure steam inlet 45 receives high pressure steam from a steam source. Steam is directed through high pressure section 15 such that work is extracted from the steam by rotation of disk 55 . After exiting the high pressure section 15, the steam can be returned to the steam source for reheating. The reheated steam can then be re-directed to the inlet 50 of the intermediate pressure section. Steam may be returned to intermediate pressure section 20 at a lower pressure than the steam entering high pressure section 15 and at a temperature approximately equal to the temperature of the steam entering high pressure section 15 . Therefore, since the operating pressure in the high pressure section 15 can be higher than the operating pressure in the intermediate pressure section 20, the steam in the high pressure section 15 will have a possible leakage path between the high pressure section 15 and the intermediate pressure section 20. through the medium pressure section 20 . One such leak path may extend through the packing casing 75 around the disc shaft 55 . Other leaks can occur at steam seal unit 65 and elsewhere.

FIG. 2 shows a schematic diagram of a portion of steam turbine 10 including a number of stages 52 arranged in a steam or hot gas path 54 of steam turbine 10 . The first stage 56 may include a plurality of circumferentially-spaced first stage guides 58 and a number of circumferentially-spaced first stage blades 60 . The first stage 56 may also include a first stage shroud 62 that extends circumferentially and surrounds the first stage blades 60 . The first stage shroud 62 may include several shroud segments arranged adjacent to each other in an annular arrangement. Similarly, the second stage 64 may include a number of second stage guides 66 , a number of second stage blades 68 , and a second stage shroud 70 surrounding the second stage blades 68 . . Any number of steps and corresponding guides and runners can be included. Other embodiments may have different configurations.

FIG. 3 shows a turbine bucket 80 that may be used in one of the stages 52 of turbine 10 . For example, buckets 80 may be used in second stage 64 or later stages of turbine 10 . Generally described, turbine bucket 80 may include blade 82 , dovetail or root 84 , and platform 86 positioned between blade 82 and root 84 . As mentioned above, a number of blades or buckets 80 may be circumferentially arranged within the stages 52 of the turbine 10 . In this manner, the blades 82 of each bucket 80 may extend radially with respect to the central axis of the turbine 10 and the platforms 86 of each bucket 80 may extend circumferentially with respect to the central axis of the turbine 10. .

Blades 82 may extend radially outward from root 84 to an optional tip shroud 88 disposed about tip end 90 of bucket 80 . In some embodiments, tip shroud 88 may be integrally formed with blade 82 . Root 84 may extend radially inward from platform 86 to root end 92 of bucket 80 such that platform 86 generally defines the interface between blade 82 and root 84 . As shown, platform 86 may be formed to extend generally parallel to the central axis of turbine 10 during its operation. Root 84 may be formed to define a root structure, such as a dovetail, configured to secure bucket 80 to a turbine disk or drum of turbine 10 . During operation of the turbine 10 , the flow of steam or combustion gases 35 travels along the steam or hot gas path 54 over the platform 86 , which along with the outer circumference of the turbine disk is radially aligned with the steam or hot gas path 54 . Form the inner boundary. Accordingly, the flow of steam or combustion gases 35 is directed against the blades 82 of the buckets 80 so that the surfaces of the blades 82 are exposed to very high temperatures.

4 and 5, a steam turbine 100 with guides and runners as described herein is shown in one embodiment. Steam turbine 100 may include a first controlled flow guide 120 for the first stage and a first controlled flow runner 130 for the first stage. A first controlled flow runner 130 may be positioned adjacent to the first controlled flow guide 120 . First controlled flow guide 120 and first controlled flow runner 130 may be coupled to disk or drum 110 . The steam turbine guide may be a controlled flow guide and the runner may be a controlled flow runner. Steam turbine 100 may include a second controlled flow guide 140 for the second stage and a second controlled flow runner 150 for the second stage. Second controlled flow guide 140 may be a controlled flow guide and second controlled flow runner 150 may be a controlled flow runner. Any number of stages and/or controlled flow guides and controlled flow runners can be included.

One or more of the controlled flow runners, specifically first controlled flow runner 130 and second controlled flow runner 150, may include tips, blades, and roots. Roots can be configured to couple runners to disk 110 . A blade may be positioned between the root and the tip. In some embodiments, a tip shroud may be coupled to the tip.

The blades of first controlled flow runner 130 may have curved configuration 132 . Specifically, the blades of first controlled flow runner 130 may have a reduced axial width around the center of first controlled flow runner 130 . As shown in FIG. 4, the blade of first controlled flow runner 130 can include top width 134 , middle width 136 , and bottom width 138 . The width may be an axial width. Top width 134 may be the axial width of the top of first controlled flow runner 130 . The top width 134 may be the width of the portion of the first controlled flow runner 130 radially outward from the disk 110, more specifically the blade. Intermediate width 136 may be the axial width of the first controlled flow runner 130 or the blade of the first controlled flow runner 130 determined or measured around the center of the blade. The bottom width 138 may be the axial width of the first controlled flow runner 130 at the bottom, which may be adjacent to the blades or the disk or drum 110 .

The second controlled flow runner 150 may also have an axial width that varies at different distances measured from the root of the second controlled flow runner 150 or turbine disk. For example, second controlled flow runner 150 can have a top axial width 152 , a middle axial width 154 , and a bottom axial width 156 . Bottom axial width 156 may be the axial width of second controlled flow runner 150 measured at first radial distance 158 from disk 110 . Intermediate axial width 154 may be the axial width of second controlled flow runner 150 measured at a second radial distance 160 from disk 110 . Second radial distance 160 may be greater than first radial distance 158 . Top axial width 152 may be the axial width of second controlled flow runner 150 measured at a third radial distance 162 from disk 110 . Third radial distance 162 may be greater than first radial distance 158 and second radial distance 160 . A middle axial width 154 of the second controlled flow runner 150 may be reduced relative to the top axial width 152 and bottom axial width 156 to reduce profile loss. As shown in FIG. 4, second controlled flow runner 150 may have a height that is greater than the height of first controlled flow runner 130 .

In some embodiments, the intermediate widths of one or more or all of the runners of steam turbine 100, such as first controlled flow runner 130 and second controlled flow runner 150, are equal to the respective top and bottom widths. It can be smaller than the width. As such, the runner may be in a curved configuration. The intermediate width of runners of steam turbine 100 may be sized to reduce profile losses. For example, profile losses of steam turbine 100 may be reduced by sizing the middle width to be smaller than the top width and/or bottom width. In some embodiments, the bottom width of each runner may be greater than the top width. Accordingly, a controlled flow runner may be configured to accelerate guide wakes and reduce mixing losses in steam turbine 100 . In some embodiments, a steam turbine may include multiple stages with respective pairs of controlled flow guides and controlled flow runners corresponding to respective turbine stages.

In FIG. 5, a blade portion 164 of the controlled flow runner described herein is shown in perspective view. Blade portion 164 may have an airfoil shape 162 with a curved configuration 160 on the trailing edge. The bottom 166 of blade portion 164 may have a different center of gravity than the top or middle portion of blade portion 164 .

The controlled flow runner may have a curved stack configuration 160 in which the tips, blades, and roots are stacked off-center of gravity. Specifically, the first center of gravity of the tip of the runner may be offset from the second center of gravity of the blade. The second center of gravity of the blade may be offset from the third center of gravity of the root. The curved trailing edge and/or aperture/pitch distribution of the blades may create a controlled flow vortex distribution as the gas passes through the controlled flow runner. FIG. 5 further illustrates the blade in top perspective view 170, front view 180, and side view 190 showing the curved central portion 192 of the blade.

FIG. 6 schematically illustrates an exemplary embodiment of a portion of turbine 200 . Turbine 200 may include a number of blades 202 arranged adjacent to each other to form stages. In some cases, blades 202 may form the final stage of turbine 200 . Any number of blades 202 may be used herein to form any stage of turbine 200 . For example, blades 202 may form the first stage, the last stage, or any stage therebetween. The blades 202 may be attached to the disc and circumferentially spaced from each other. Each of blades 202 may include a leading edge 208 , a trailing edge 210 , a pressure side 212 and a suction side 214 . Passages 216 may be formed between adjacent blades 202 . Passageway 216 may include a throat region 218 . Throat region 218 is the shortest distance from trailing edge 210 to suction surface 214 of the adjacent blade 202 . The back of the blade may have a very large amount of warpage. In some embodiments, the back surface bow may be greater than a threshold, such as about 10 degrees, or between about 5 degrees and about 25 degrees.

FIG. 6 further schematically illustrates the difference in average cross-section between the controlled flow runner described herein and another runner (indicated by dashed lines). The difference in shape is indicated by the change in position of the respective suction and pressure surfaces 220, 222 and 228, 230, as well as the leading edge-to-edge spacing 226 and the trailing edge-to-edge spacing 224. FIG.

The tip difference between the controlled flow runner described herein and another runner (indicated by dashed lines) is also shown in FIG. As shown, differences in placement and spacing of suction surfaces 240, 242 and 246, 248, which may be minimal, may result in increased strength and decreased losses. FIG. 6 further shows an example of backside bow, denoted δ, which indicates uncontrolled flow turning at the suction side, tangent to the suction side at the throat point and The angle between the tangents drawn at the trailing edge circle blend point.

A method of using a controlled flow runner as described herein may include providing a route for a controlled flow runner of a steam turbine and coupling blades of the controlled flow runner to the route. , the blade has a top width, a middle width and a bottom width, the middle width being smaller than the top width and the bottom width. The method may include coupling the tip to the blade.

As a result of the controlled flow runners described herein, the steam turbine stage efficiency improvement may be about 0.20%, with reduced profile losses in the controlled flow runners and reduced secondary losses. and improved positive incidence. Certain embodiments may be used to retrofit existing steam turbines. Certain embodiments may provide lightweight runners with consistent mechanical reliability while maintaining cost. Thus, a controlled flow runner can increase stage efficiency while maintaining or improving mechanical reliability without increasing the cost or complexity of the steam turbine. Emissions may be reduced.

It is clear that the foregoing relates only to certain embodiments of the present application and the resulting patent. Numerous changes and modifications can be made herein by those skilled in the art without departing from the general spirit and scope of the invention as defined by the following claims and equivalents thereof. .

10 Steam turbine 15 High pressure section 20 Medium pressure section 25 Casing 30 Upper half 35 Lower half, combustion gas 40 Middle section 45 High pressure steam inlet 50 Medium pressure steam inlet, medium pressure section inlet 52 Stage 54 Hot gas path 55 Disk, disk shaft 56 first stage 58 first stage guide 60 bearing, first stage blade 62 first stage shroud 64 second stage 65 steam seal unit 66 second stage guide 68 second stage blade 70 section divider; second stage shroud 75 packing casing 80 turbine bucket 82 blades 84 root 86 platform 88 tip shroud 90 tip end 92 root end 100 steam turbine 110 disk or drum 120 first controlled flow guide 130 first controlled curved configuration 134 top width 136 middle width 138 bottom width 140 second controlled flow guide 150 second controlled flow runner 152 top axial width 154 middle axial width 156 bottom axial width 158 second 1 radial distance 160 second radial distance, curved stack configuration 162 third radial distance, airfoil shape 164 blade portion 166 bottom 170 top perspective view 180 front view 190 side view 192 midsection 200 turbine 202 blades 208 Leading edge 210 Trailing edge 212 Pressure side 214 Suction side 216 Passage 218 Throat region 220 Suction side 222 Suction side 224 Spacing 226 Spacing 228 Pressure side 230 Pressure side 240 Suction side 242 Suction side

Claims (10)

A steam turbine (10 , 100) comprising a high pressure section (15) and an intermediate pressure section (20), comprising :
at least one of the high pressure section (15) and the intermediate pressure section (20) comprises a plurality of rotor blades;
each of the plurality of rotor blades includes a leading edge (208), a trailing edge (210), a pressure side (212), and a suction side (214);
a passage (216) is formed between adjacent rotor blades and includes a throat region (218) that is the shortest distance from said trailing edge (210) to said suction surface (214) of an adjacent rotor blade;
each of the plurality of rotor blades further comprising:
tip,
Adjacent said tip and having a top width (134), an intermediate width (136) and a bottom width (138), said intermediate width (136) being said top width (134) and said bottom width (138) a smaller airfoil (82) and a root (84) adjacent said airfoil (82);
including
said airfoil (82) having a backside camber (δ);
the backside bow (δ) is the angle between a tangent to the suction surface (214) at the throat point and a tangent drawn at the trailing edge circle blend point of the suction surface (214);
A steam turbine (10 , 100), wherein said back surface warp (δ) is greater than 10 degrees . The steam turbine (10, 100) of claim 1, wherein said backside bow (δ) is between 10 and 25 degrees. The steam turbine (10, 100) of claim 1, wherein said blades (82) comprise a curved stack configuration (132) . The steam turbine (10 , 100) of any preceding claim, wherein a first center of gravity of said blades (82) is offset from a second center of gravity of said root (84). The steam turbine (10, 100) of claim 4 , wherein said first center of gravity is offset from said tip third center of gravity. The steam turbine (10 , 100) of any preceding claim, wherein the trailing edge (210) of the blade (82) comprises a curved configuration (132). The steam turbine (10 , 100) of any preceding claim, wherein the bottom width (138) is greater than the top width (134). The steam turbine (10 , 100) of any preceding claim, further comprising a tip shroud (88) coupled to said tip, said upper width (134) adjacent said tip shroud (88). . The steam turbine (10 , 100) of any preceding claim, wherein the root (84) is coupled to the disk (110) and the bottom width (138) adjoins the root (84). The steam turbine (10 , 100) of any preceding claim, wherein the plurality of rotor blades are arranged adjacent to a plurality of flow guides (120, 140).

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