SYSTEMS AND METHODS FOR AN IMPROVED STATOR
In an embodiment, a system includes a rotary machine. The rotary machine includes a rotor having a plurality of blades and a segmented stator having a plurality of stator segments arranged circumferentially about the plurality of blades. Each adjacent pair of first and second segments of the plurality of stator segments includes a recess extending circumferentially across an intermediate joint between the first and second segments. Furthermore, each recess includes at least one eccentricity control insert configured to mitigate eccentricity of an inner circumference of the segmented stator due to thermal expansion or thermal contraction of the segmented stator.
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The subject matter disclosed herein relates to casings for use in various types of rotary systems such as compressors and gas turbines.
Rotary systems, such as compressors and turbines, may generally include a rotor portion that rotates about an axis during the operation of the system as well as a stator portion (e.g., casing, shroud, etc.) that remains substantially immobile during system operation. For example, in a compressor, the rotor portion may include a number of blades disposed about a shaft. During operation of the compressor, this shaft may rotate, causing the attached blades to rotate within a stationary casing (i.e., the stator) surrounding the rotor. However, since the temperature present within the compressor may be high (e.g., in excess of 1000° C.), portions of the rotor and/or casing of the compressor may warm and expand during operation. This expansion may change the clearance between these portions of the rotor and/or casing during operation of the compressor, which may affect the ability of the compressor to properly function and/or operate efficiently.
BRIEF DESCRIPTION OF THE INVENTIONCertain embodiments commensurate in scope with the originally claimed invention are summarized below. These embodiments are not intended to limit the scope of the claimed invention, but rather these embodiments are intended only to provide a brief summary of possible forms of the invention. Indeed, the invention may encompass a variety of forms that may be similar to or different from the embodiments set forth below.
In an embodiment, a system includes a rotary machine. The rotary machine includes a rotor having a plurality of blades and a segmented stator having a plurality of stator segments arranged circumferentially about the plurality of blades. Each adjacent pair of first and second segments of the plurality of stator segments includes a recess extending circumferentially across an intermediate joint between the first and second segments. Furthermore, each recess includes at least one eccentricity control insert configured to mitigate eccentricity of an inner circumference of the segmented stator due to thermal expansion or thermal contraction of the segmented stator.
In another embodiment, a system includes an eccentricity control insert configured to mount in a recess at an intermediate joint between an adjacent pair of first and second segments of a segmented stator of a rotary machine. Furthermore, the eccentricity control insert is configured to mitigate eccentricity of an inner circumference of the segmented stator due to thermal expansion or thermal contraction of the segmented stator.
In another embodiment, a system includes a segmented stator including a plurality of stator segments arranged circumferentially about a rotational axis of a rotary machine. Each adjacent pair of first and second segments of the plurality of stator segments includes a recess extending circumferentially across an intermediate joint between the first and second segments. Furthermore, each recess includes at least one eccentricity control insert configured to mitigate eccentricity of an inner circumference of the segmented stator due to thermal expansion or thermal contraction of the segmented stator.
These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:
One or more specific embodiments of the present invention will be described below. In an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.
When introducing elements of various embodiments of the present invention, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.
As set forth above, the temperature of the gases present within a rotary system (e.g., a compressor, turbine of a gas turbine system, steam turbine, pump, or similar rotary system) may be relatively high and/or fluctuate during certain points during the operation of the system. These elevated and fluctuating temperatures in the rotary system may cause portions the casing (i.e., stator) encircling the rotor to warm and expand or cool and contract during system operation. Additionally, since a casing of a rotary system may include a number of coupled segments, then the expansion/contraction of the casing at or near the joints may not be the same as the expansion in the middle of the casing segments. This may generally result in the casing (e.g., the inner circumference of the casing) becoming less round (e.g., more eccentric) as a result of the thermal expansion. As such, if, for example, the casing of a rotary system (e.g., a compressor or turbine) expands and/or contracts in a certain manner during operation, then portions of rotor and casing may contact one another, resulting in premature wear, vibration, and/or cracking in the rotary system. If, by further example, the casing of the rotary system expands and/or contracts in another manner during operation, then clearance between the rotor and the casing may be too great, resulting in reduced efficiency of the rotary system. Accordingly, it may be generally desirable to improve the casing (i.e., stator) design to control the clearance between the rotor and the casing by mitigating the eccentricity of the casing at it warms and/or cools during operation of the rotary system. The disclosed embodiments employ inserts in recesses along each joint between casing segments, thereby helping to maintain roundness of the casing (e.g., an inner surface of the casing) despite thermal expansion or contraction.
With the foregoing in mind,
As mentioned, the illustrated compressor 16 and turbine 22 include casings (i.e., stators or shrouds) that have been modified in order to reduce the potential of the casings to expand or contract out of roundness (e.g., become eccentric) during operation of the system 10. In particular, disclosed embodiments generally have portions of each of the segments of the case absent or removed near the joints (e.g., removed portions where the individual segments of the case meet). For example, in certain embodiments, the removed portions of the segments near the joints may take the form of a recess, a groove, or a slot. Furthermore, the disclosed embodiments utilize an insert that may be disposed within the groove or recess to generally control the clearance between the blades of the rotor and the casing of the rotary machine (e.g., compressor 16 or turbine 22). While the various aspects of the modified casing embodiments are described below with respect to the compressor 16, it should be appreciated that the presently disclosed casing embodiments are applicable to the gas turbine 22 or any rotary system where uniform and/or minimized clearance between the rotor and stator are desirable.
Accordingly,
Accordingly, the casing 56 of the compressor 16 has at least one recess 60 that supports at least one insert 62 in accordance with aspects of the present technique. Generally speaking, the recess 60 extends into the interior surface of the casing 56 in the radial direction 40 (i.e., having a radial depth 51 into the wall of the casing 56). In certain embodiments, the recess 60 may be formed by grinding or turning down a portion of the casing 56 after manufacturing. In other embodiments, the recess 60 may be formed during the manufacturing of the casing 56 (e.g., as an element defined by the mold used to cast the casing 56). Regardless, the recess 60 is an area of the casing in which a portion of the casing material (e.g., steel or other suitable metal or alloy) is absent or has been removed (e.g., via grinding or turning). For example, in certain embodiments, the recess 60 may be in the form of a groove, a slot, a channel, or other similar recess 60. Additionally, as discussed below with respect to
Additionally, in the illustrated compressor 16, an insert 62 is disposed within the recess 60. As illustrated, the insert 62 may slightly protrude radially 40 from the recess 60 into the clearance space 58. For example, the insert 62 may extend between approximately 20 mm and 60 mm beyond the inner surface 53 of the casing 56. The illustrated insert 62 also includes at least two layers: a substrate layer 64 and an abradable surface coating 66. In certain embodiments, the substrate layer 64 of the insert 62 may be manufactured from the same material (e.g., metal or alloy) as the casing 56. For example, in certain embodiments, the insert 62 and the casing 56 may both be manufactured from steel. In other embodiments, the substrate layer 64 of the insert 62 may be manufactured from a different material (e.g., metal or alloy) than the casing 56. For example, in certain embodiments, the substrate layer 64 of the insert 62 may be a different type of steel (e.g., higher carbon steel) than the casing 56. Furthermore, the material used for the substrate layer 64 of the insert 62 may be selected based on the thermal expansion properties of the material. That is, the substrate layer 64 of the insert 62 may have slightly different thermal expansion properties from the casing 56 such that the insert 62 and the casing 56 may not expand or contract at the same rate as they are heated and cooled (e.g., during operation of the compressor 16).
Moreover, the insert 62 is disposed within the recess 60 such that the abradable surface coating 66 is facing the blades 52 of the rotor 54. The abradable surface coating 66 may be any surface coating that may be preferentially removed upon contact with the blades 52 of the rotor 54, rather than remove material from the rotor blades 52 or the casing 56. That is, while the blades 52 of the rotor 54 are generally configured not to contact the casing 56, the aforementioned thermal expansion of the casing 56 during operation of the compressor may cause the blades 52 of the rotor 54 to temporarily contact the abradable surface coating 66 of the insert 62 (e.g., rather than the substrate 64 of the insert 62 or the casing 56). Therefore, the abradable surface coating 66 may generally allow for tighter clearance 58 while protecting the tips of the blades 52. Additionally, the abradable surface coating 66 may generally be considered a self-adjusting coating as it may be slightly by the tips of the blades 52 until the desired clearance 58 is achieved. In certain embodiments, the abradable surface coatings 66 may be an alumina, silica, titania, chrome carbines, or other suitable abradable surface coating 66. In general, materials for the abradable surface coating 66 may be selected according to a relative hardness of the abradable surface coating 66 compared to the casing 56 and the blades 52 of the rotor 54. For example, in certain embodiments, the abradable surface coating 66 may be manufactured from a material that is 10%, 20% 50%, 75%, or 95% softer than the material used to manufacture the casing 56 and/or the blades 52. Additionally, as set forth below with respect to
Accordingly, the inserts 62 disposed within each of the recesses 60 similarly are thicker in the portions that are disposed near the joints 70 and 72 and thinner in portions that are disposed away from the joints. Furthermore, in certain embodiments, a one-piece or integral insert 62 may be disposed in the each of the recesses 60, and each of these inserts 62 may occupy the entire recess 60 that extends circumferentially 38 into both segments 74 and 76 of the compressor casing 56. In the illustrated embodiment, recesses 60 include a recess portion 63 and a recess portion 65 that are each loaded with an insert 62. That is, each recess 60 of the illustrated casing 56 includes a first insert 62 (e.g., disposed within the recess portion 63 of the recess 60 in segment 74) and a second insert 62 (e.g., disposed within the recess portion 65 of the recess 60 in segment 76).
Additionally, the illustrated casing 56 of the compressor 16 is substantially round (i.e., circular). Furthermore, it should be appreciated that, as the casing 56 warms or cools during operation of the compressor 16, the portions of the segments 74 and 76 near the joints 70 and 72 may not expands or contract as much as the portions of the segments 74 and 76 away from the joints 70 and 72. That is, since the casing 56 may generally have more freedom to move near the joints 70 and 72, the casing 56 generally push outwardly 67 or pull inwardly 69 (e.g., center 73 of the casing 56), deforming at the joints 70 and 72 (e.g., shift out of roundness and/or become eccentric). Moreover, the illustrated casing 56 has the recesses 60 with the inserts 62 disposed within. Accordingly, as the casing 56 begins to thermally expand, the recesses 60 and the inserts 62 enable the casing 56 of the compressor to thermally expand without becoming substantially eccentric. That is, the recesses 60 and the inserts 62 generally enable the clearance 58 between the blades 52 of the rotor 54 to remain substantially uniform throughout the operation of the compressor 16. For example, in certain embodiments, the recesses 60 and inserts 62 may cooperate to provide a uniform clearance 58 (e.g., circumferentially 38 between the rotor blades 52 and the casing 56 and insert 62) of between 1 mm and 50 mm, between 5 mm and 30 mm, between 8 mm and 20 mm, or approximately 10 mm at the joints 70 and 72.
Furthermore, the illustrated insert 62 is substantially thicker 75 near the joint 70. That is, both the substrate 64 and the abradable coating 66 of the illustrated insert 62 are substantially thicker 75 near the joint 70 and gradually taper along the segment 76 (i.e., moving away from the joint 70 circumferentially 42), where the substrate 64 and the abradable coating 66 of the illustrated insert 62 are thinner 77. Accordingly, when the blades 52 of the rotor 54 are rotating during operation of the compressor 16, the groove 60 and the insert 62 may provide a uniform circumferential clearance 58 such that the compressor 16 may efficiently function.
Technical effects of the present embodiments include mitigating the eccentricity of stators in rotor/stator system (e.g., casings for compressors, gas turbines, steam turbines, pumps, or other rotary machines) in order to control the clearance between the rotor and the stator as the system expands and/or contracts during heating and/or cooling. By controlling the clearance between the rotor and the casing of the compressor or gas turbine, present embodiments enable the compressor or gas turbine to continue to properly and efficiently function, even as the casing expands and contracts during operation. Accordingly, present embodiments may reduce maintenance costs by reducing the likelihood of contact between the rotor blades in the casing and by providing an abradable coating that may be preferentially removed to preserve the integrity of the rotor blades and/or casing in case of contact. Furthermore, present embodiments enable the compressor or gas turbine to maintain efficiency during operation, limiting energy costs and waste.
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. 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 intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.
Claims
1. A system, comprising:
- a rotary machine, comprising: a rotor comprising a plurality of blades; and a segmented stator comprising a plurality of stator segments arranged circumferentially about the plurality of blades, wherein each adjacent pair of first and second segments of the plurality of stator segments includes a recess extending circumferentially across an intermediate joint between the first and second segments, and each recess includes at least one eccentricity control insert configured to mitigate eccentricity of an inner circumference of the segmented stator due to thermal expansion or thermal contraction of the segmented stator.
2. The system of claim 1, wherein the at least one eccentricity control insert comprises an abradable portion disposed over a base portion.
3. The system of claim 2, wherein the abradable portion comprises alumina or a chrome carbine.
4. The system of claim 2, wherein the abradable portion has a first non-uniform thickness in a circumferential direction about a rotational axis of the rotor, the base portion has a second non-uniform thickness in the circumferential direction, or a combination thereof.
5. The system of claim 2, wherein the at least one eccentricity control insert comprises an arcuate shaped body having the abradable portion disposed over the base portion, wherein an arc length of the at least one eccentricity control insert extends less than approximately 60 degrees in a circumferential direction about a rotational axis of the rotor.
6. The system of claim 1, wherein the recess of each adjacent pair of first and second segments comprises a first recess portion disposed in the first segment and a second recess portion disposed in the second segment, and the at least one eccentricity control insert comprises a first insert portion disposed in the first recess portion and a second insert portion disposed in the second recess portion.
7. The system of claim 1, wherein a radial depth of the first and second recess portions gradually decreases circumferentially away from the intermediate joint.
8. The system of claim 1, wherein a radial thickness of the first and second insert portions gradually decreases circumferentially away from the intermediate joint.
9. The system of claim 1, wherein the recess comprises a T-shaped slot and the at least one eccentricity control insert comprises at least one T-shaped insert configured to mount into the T-shaped slot in a circumferential direction about a rotational axis of the rotor.
10. The system of claim 1, wherein the rotary machine comprises a compressor or a turbine.
11. A system, comprising:
- an eccentricity control insert configured to mount in a recess at an intermediate joint between an adjacent pair of first and second segments of a segmented stator of a rotary machine, wherein the eccentricity control insert is configured to mitigate eccentricity of an inner circumference of the segmented stator due to thermal expansion or thermal contraction of the segmented stator.
12. The system of claim 11, wherein an arc length of the eccentricity control insert extends less than approximately 60 degrees in a circumferential direction about a rotational axis of the rotary machine, the eccentricity control insert comprises an arcuate shaped body having an abradable portion disposed over a base portion, and at least one of the abradable portion or the base portion has a non-uniform thickness in the circumferential direction.
13. The system of claim 11, wherein the eccentricity control insert comprises an abradable material configured to abrade away to protect a plurality of rotary blades of the rotary machine.
14. The system of claim 11, wherein an arc length of the eccentricity control insert extends less than approximately 60 degrees in a circumferential direction about a rotational axis of the rotary machine.
15. The system of claim 11, wherein a radial thickness of the eccentricity control insert progressively increases from a first end portion to a second end portion in a circumferential direction about a rotational axis of the rotary machine.
16. The system of claim 11, wherein the eccentricity control insert comprises a neck portion and a mounting base portion that extend in a lengthwise direction along the eccentricity control insert, and the mounting base portion is wider than the neck portion in a crosswise direction relative to the lengthwise direction.
17. The system of claim 11, comprising the rotary machine having a compressor or a turbine.
18. A system, comprising:
- a segmented stator comprising a plurality of stator segments arranged circumferentially about a rotational axis of a rotary machine, wherein each adjacent pair of first and second segments of the plurality of stator segments includes a recess extending circumferentially across an intermediate joint between the first and second segments, and each recess includes at least one eccentricity control insert configured to mitigate eccentricity of an inner circumference of the segmented stator due to thermal expansion or thermal contraction of the segmented stator.
19. The system of claim 18, wherein an arc length of the eccentricity control insert extends less than approximately 60 degrees in a circumferential direction about the rotational axis, and the eccentricity control insert comprises an abradable material configured to abrade away to protect a rotating component of the rotary machine.
20. The system of claim 18, comprising the rotary machine having a compressor or a turbine.
Type: Application
Filed: Mar 9, 2012
Publication Date: Sep 12, 2013
Applicant: General Electric Company (Schenectady, NY)
Inventor: James Adaickalasamy (Bangalore)
Application Number: 13/416,982
International Classification: F01D 9/04 (20060101);