CN103485844B - Turbine and method for mitigating out of roundness effects of turbine - Google Patents

Abstract

A turbine and a method of mitigating out-of-roundness effects at a turbine are disclosed. An inner turbine shell and an outer turbine shell of the turbine are provided. The inner turbine shell is coupled to the outer turbine shell by using a ring insert. The ring insert is segmented into a plurality of ring insert segments (302) that reduce a transfer of load from the outer turbine shell to the inner turbine shell to mitigate out-of-roundness of the inner turbine shell.

Description

Turbine and method for reducing the effects of out-of-round turbine

technical field

The invention relates to a device and a method for reducing the effects of out-of-roundness on an inner turbine casing of a gas turbine.

Background technique

Several turbine section designs include an inner turbine casing that provides a flow path for working gases to pass through the turbine, and an outer turbine casing that surrounds the inner turbine casing. Generally, a rotor having a plurality of blades is disposed within the inner turbine casing and rotates as the working gas passes through the turbine. The spacing between the inner turbine casing and the plurality of turbine blades determines turbine efficiency and power production, and may be affected by deviations of the inner turbine casing from circular cross-sections, also referred to as out-of-roundness. Due to the connection between the inner turbine casing and the outer turbine casing, loads due to various operating stresses are generally transferred from the outer turbine casing to the inner turbine casing and cause distortion of the inner turbine casing, which Distortion is a condition known as out-of-roundness. Therefore, it is desirable to design turbine casings that reduce the effects of out-of-roundness. The present invention provides a method and apparatus for reducing the transfer of loads between an outer turbine casing and an inner turbine casing to reduce out-of-round effects.

Contents of the invention

According to one aspect, the present invention provides a method of reducing the effects of out-of-roundness on a turbomachine, the method comprising: providing an inner turbine casing of the turbomachine within an outer turbine casing of the turbomachine; The inner turbine casing is connected to the outer turbine casing, the annular insert is divided into a plurality of annular insert segments in order to reduce load transfer from the outer turbine casing to the inner turbine casing, thereby slowing down Out-of-roundness of the inner turbine casing.

According to another aspect, the present invention provides a turbomachine comprising: an outer turbine casing; an inner turbine casing; and an annular insert configured for connecting the inner turbine casing to The outer turbine casing, and is divided into a plurality of annular insert segments to reduce load transfer from the outer turbine casing to the inner turbine casing.

These and other advantages and features will become more apparent from the following description taken in conjunction with the accompanying drawings.

Description of drawings

The above-mentioned and other features and advantages of the present invention can be clearly understood through the following detailed description in conjunction with the accompanying drawings, in which:

Figure 1 shows a side cross-sectional view of an exemplary inner turbine casing of a turbogenerator in one embodiment of the invention;

Figure 2 shows a cross-section of the inner turbine casing shown in Figure 1 including the thrust collar;

Figure 3 shows a cross-sectional view of an exemplary shell sector in an exemplary embodiment; and

4 and 5 show plots of the circumference of an exemplary inner turbine casing of the present invention at various times during an exemplary turbine operating cycle.

The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings.

detailed description

FIG. 1 shows a side cross-sectional view of an exemplary inner turbine casing 100 of a gas turbine in one embodiment of the invention. The exemplary inner turbine casing 100 provides a hollow casing extending along a longitudinal axis 102 and having an inlet 104 at a first end of the longitudinal axis and a second end of the longitudinal axis. Exit 106 on the end. The turbine casing is generally rotationally symmetric about its longitudinal axis 102 . A rotor having a plurality of turbine blades (not shown) is disposed within the inner turbine casing 100 generally along the longitudinal axis 102 . Working gas injected into the inner turbine casing 100 at the inlet 104 displaces the turbine blades, causing the turbine blades to rotate, thereby causing the rotor to rotate to generate electricity. In various embodiments, the inner turbine casing 100 is composed of two or more parts, also referred to herein as casing sectors, that fit together to form the inner turbine Shell 100. Exemplary shell sectors generally span selected azimuthal angles about the longitudinal axis 102 . Two or more shell sectors are fitted together at interface 110 via bolts 112 . Cooperating casing sectors provide cooling holes or air passages 114 through the inner turbine casing 100 to provide air to nozzles (not shown) assembled thereon. The inner turbine casing is connected to the outer turbine casing at a thrust collar 116 of the inner turbine casing 100 . The inner turbine casing includes a thrust ring 116 .

FIG. 2 shows a cross-section of the inner turbine casing shown in FIG. 1 including the thrust ring 116 . In various embodiments, the thrust ring 116 is segmented. The segmented thrust ring 116 of the inner turbine casing includes a slot 118 into which an annular insert can be inserted. The annular insert connects the inner turbine casing to the outer turbine casing to support the inner turbine casing. The annular insert provides a contact area between the inner turbine casing and the outer turbine casing. In an exemplary embodiment, the annular insert is divided into a plurality of annular insert segments, the plurality of annular insert segments being spaced apart from each other so as to provide a gap between the segments along the circumference. Thus, the plurality of annular insert segments have a total angle as opposite sides of less than 360 degrees.

FIG. 3 shows a section through a shell sector in an exemplary embodiment of the invention. The exemplary inner turbine casing is composed of four casing sectors that each constitute a quarter of the inner turbine casing 300 . Shown is an exemplary shell sector 315 . Shown is an annular insert segment 302 on the exemplary shell sector 315 . The annular insert segment 302 extends along the circumference of the sector 315 from a first azimuthal location 304 to a second azimuthal location 306 , as opposite sides of a corner 320 . In one embodiment, angle 320 is less than 90 degrees. In another embodiment, the angle 320 is between about 15 degrees and 85 degrees. In yet another embodiment, the angle 320 is between about 30 degrees and about 70 degrees. In an exemplary embodiment, the annular insert segment 302 is evenly disposed between the first mating interface 310 and the second mating interface 312 of the shell sector 315 such that between the first azimuthal position 304 and the The distance between the first mating interface 310 is substantially the same as the distance between the second azimuth position 306 and the second mating interface 312 . Thus, the contact area between the outer turbine casing and the inner turbine casing is less than 360 degrees. This reduced contact area results in a reduced load transfer area between the outer turbine casing and the inner turbine casing. In alternative embodiments, the exemplary shell sector 315 may include two or more annular segments spaced apart from each other.

In one aspect, the length of the annular insert segment can be determined using a processor. An exemplary processor may perform simulations to determine lengths of the annular insert segments when the inner turbine casing is out-of-round according to selected criteria. The processor may simulate various operating cycles of the turbine and determine out-of-roundness of the inner turbine casing at various times during the cycles.

Alternatively, a turbine may be constructed and operated with the exemplary annular insert segments. Sensors may be placed at various locations on the inner turbine casing and the inner turbine casing may be observed for out-of-roundness as the turbine runs through various operating cycles. Accordingly, annular insert segment lengths and spacing can be determined by observing the effect of various annular insert segment lengths on reducing the effect of out-of-roundness.

In one aspect, the length of the ring segment is selected when the out-of-circle meets the selected criteria. In various embodiments, a suitable segment is selected when the length of the annular segment is such that the out-of-roundness of the inner turbine casing is within an acceptable tolerance level. In another embodiment, the selected criterion may be an out-of-round tolerance over a selected time frame.

4 shows a plot of the circumference of an exemplary inner turbine casing of the present invention at various times during operation of an exemplary turbine. The plot of FIG. 4 is output from an analytical model in terms of radial displacement measurements of the circumference, such measurements being made approximately every 5 degrees around the circumference. Alternatively, a plot can be obtained substantially using about 10 sensors placed around the circumference to test the constructed shell, obtaining radial measurements at various times indicated by reference numeral 401 (after activation 1654 seconds), 402 (2374 seconds), 403 (2874 seconds), 404 (4174 seconds), 405 (100000 seconds), and 406 (100967 seconds) indications. FIG. 5 shows a plot of the circumference of the exemplary inner turbine casing of FIG. 4 at a later time. Radial measurements were taken at various times indicated by 501 (105618 seconds), 502 (114400 seconds), 503 (116055 seconds), 504 (116271 seconds), 505 (116775 seconds) and 506 (214400 seconds) . The exemplary inner turbine housing generally operates through one or more cycles of increasing and decreasing electrical output. The circumference of the inner turbine casing generally increases by heating and decreases by cooling. An earlier time (ie, time 401 ) shows an inner turbine casing having a generally circular cross-section. The turbines are shown operating at high output levels (ie times 404, 405 and 406). Specifically, time 404 shows the inner turbine casing having a greater out-of-round effect at high output levels. The circles are shown as times 503 and 504 of the operating cycle to drop to a lower output level. Various degrees of out-of-roundness are shown. The circle is shown as time 506 of the operating cycle is raised again to a high output level. As shown in FIG. 5, at time 506, the shell is relatively lightly out of round. When the out-of-round effect is within acceptable tolerances, the operator may select ring segments for use in the turbine.

Accordingly, in one aspect, the present invention provides a method of reducing the effects of out-of-roundness on a turbomachine, the method comprising: providing an inner turbine casing of the turbomachine within an outer turbine casing of the turbomachine; and using an annular insert A member connects the inner turbine casing to the outer turbine casing, the annular insert is divided into a plurality of annular insert segments to reduce load transfer from the outer turbine casing to the inner turbine casing, Out-of-roundness of the inner turbine casing is thereby mitigated. In one embodiment, said plurality of annular insert segments comprises four annular insert segments. At least one of the annular insert segments is opposite an angle measured from the longitudinal axis of the inner turbine casing selected from one of the following: (i) less than 90 degrees; ( ii) between about 15 degrees and about 85 degrees; and (iii) between about 30 degrees and about 70 degrees. A processor may be used to determine the length and position of the annular insert segment when the out-of-roundness of the inner turbine casing meets selected criteria. The length of the annular insert segment is selected to reduce the load path between the outer turbine casing and the inner turbine casing. In various embodiments, the load is from thermal stress on the outer turbine casing. The annular insert segments are disposed on the thrust ring of the inner turbine casing at equidistant positions around the circumference of the inner turbine casing. In various embodiments, the inner turbine casing is composed of at least two azimuthal casing sectors.

A turbomachine comprising: an outer turbine casing; an inner turbine casing; and an annular insert configured to connect the inner turbine casing to the outer turbine casing and divide into a plurality of annular Insert segments to reduce load transfer from the outer turbine casing to the inner turbine casing. In an exemplary embodiment, the annular insert is divided into four annular insert segments. At least one of said annular insert segments has as its opposite an angle selected from one of: (i) less than 90 degrees; (ii) between about 15 degrees and 85 degrees; and (iii) between about 30 degrees and Between about 70 degrees. A processor running a program on a model of the turbine may be used to determine the length of the annular insert. The length of the annular insert segment is generally selected so as to reduce a load path between the outer turbine casing and the inner turbine casing. The loads generally relate to thermal stress on the outer turbine casing. In an exemplary embodiment, the annular insert segments are evenly spaced around the circumference of the inner turbine casing. In various embodiments, the inner turbine casing is comprised of at least two casing sectors extending in selected azimuthal angles.

While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention may be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are consistent with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.

Claims (16)

1. A method for reducing the effects of out-of-round turbines, comprising: An inner turbine casing of the turbine is disposed within an outer turbine casing of the turbine, the inner turbine casing comprising a plurality of casing sectors forming corners opposite thereto and meeting at mating interfaces connection; and The inner turbine casing is connected to the outer turbine casing using a plurality of annular insert segments to reduce load transfer from the outer turbine casing to the inner turbine casing thereby lowering the inner turbine casing Out-of-roundness of the shell, wherein one annular insert segment is associated with one of said shell sectors and the angle subtended by the annular insert segment is smaller than the angle subtended by said shell sectors. 2. The method of claim 1, wherein the plurality of annular insert segments further comprises four annular insert segments. 3. The method of claim 2, wherein at least one said annular insert segment is opposite an angle measured from the longitudinal axis of said inner turbine casing, said angle being selected from one of the following: (i ) is less than 90 degrees; (ii) is between 15 degrees and 85 degrees; and (iii) is between 30 degrees and 70 degrees. 4. The method of claim 1, further comprising using a processor to determine the length of the annular insert segment when the out-of-roundness of the inner turbine casing meets selected criteria. 5. The method of claim 1, wherein the length of the annular insert segment is selected to reduce a load path between the outer turbine casing and the inner turbine casing. 6. The method of claim 1, wherein the transferred load is caused by thermal stress on the outer turbine casing. 7. The method of claim 1, wherein the annular insert segments are disposed equidistantly around the circumference of the inner turbine casing on a thrust ring of the inner turbine casing. 8. The method of claim 1, wherein the inner turbine casing is comprised of at least two azimuthal casing sectors. 9. A turbine comprising: outer turbine casing; an inner turbine casing disposed within the outer turbine casing, the inner turbine casing comprising a plurality of casing sectors forming corners opposite thereto and connected at mating interfaces; and a plurality of annular insert segments configured to connect the inner turbine casing to the outer turbine casing so as to reduce the flow from the outer turbine casing to the inner turbine casing wherein one annular insert segment is associated with one said shell sector and the angle subtended by the annular insert segment is smaller than the angle subtended by said shell sector. 10. The turbine of claim 9, wherein the plurality of annular insert segments is divided into four annular insert segments. 11. A turbine as claimed in claim 10, wherein at least one of said annular insert segments has as its opposite an angle selected from one of: (i) less than 90 degrees; (ii) between 15 degrees and 85 degrees and (iii) between 30° and 70°. 12. The turbine of claim 9, wherein the length of the annular insert segment is determined using a processor running a model program of the turbine. 13. The turbine of claim 9, wherein the length of the annular insert segment is selected to reduce a load path between the outer turbine casing and the inner turbine casing. 14. The turbine of claim 9, wherein said load involves thermal stress on said outer turbine casing. 15. The turbine of claim 9, wherein said annular insert segments are evenly spaced around the circumference of said inner turbine casing. 16. The turbine of claim 9, wherein said inner turbine casing is comprised of at least two casing sectors extending at a selected azimuthal angle.