Patent Application
20130177413
The subject matter disclosed herein relates to turbines. More particularly, the subject matter relates to an assembly of turbine static structures.
In turbine engines, such as steam or gas turbine engines, static or non-rotating structures may have certain clearances when placed adjacent to one another. The clearances between adjacent structures allow for movement caused by temperature changes or pressure changes. For instance, in a gas turbine engine, a combustor converts chemical energy of a fuel or an air-fuel mixture into thermal energy. The thermal energy is conveyed by a fluid, often air from a compressor, to a turbine where the thermal energy is converted to mechanical energy. High combustion temperatures and/or pressures in selected locations, such as the combustor and turbine nozzle areas, may enable improved combustion efficiency and power production. In some cases, high temperatures and/or pressures in certain turbine structures may cause relative movement of adjacent structures, which can cause contact and friction that lead to stress and wear of the structures. For example, stator structures, such as rings or casing, are circumferentially joined about the turbine case and are exposed to high temperatures and pressure as the hot gas flows along the stator.
It is desirable to improve turbine performance by reducing turbine clearances. In some cases reducing clearances requires accounting for eccentricity, out of roundness and part variation.
According to one aspect of the invention, a turbine assembly includes a first static structure and a second static structure radially outward of the first static structure. The assembly also includes a support member placed in a recess of the second static structure, wherein the support member includes first and second curved surfaces to contact the first and second static structures, respectively, and wherein the support member includes a biasing structure to retain the support member in the recess.
According to another aspect of the invention, a method for supporting turbine components includes positioning an inner turbine shell substantially concentric with a rotor and surrounding the inner turbine shell with an outer turbine shell. The method also includes supporting the inner turbine shell with respect to the outer turbine shell with a support member, wherein the support member includes a biasing structure configured to maintain a position of the support member when the support member is not in contact with one of the inner or outer turbine shell.
These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings.
The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:
and
The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings.
Embodiments of the present invention include a clearance control system that adjusts the position of an inner turbine shell with respect to a rotor and/or an outer turbine shell. In doing so, the system addresses several parameters to reduce operating clearance between rotating and stationary components in the turbine to improve performance in a cost-effective manner. The key parameters include friction, eccentricity, out of roundness, muscle, cost, and ease-of-use. They system may further include clearance control structures and methods to control the temperature, and thus the expansion and contraction, of the inner turbine shell. Although various embodiments of the present invention may be described and illustrated in the context of a turbine, one of ordinary skill in the art will understand that the principles and teachings of the present application apply equally to type of turbine having rotating and stationary components in close proximity.
The inner turbine shells 14 completely surround at least a portion of the rotor 12. As shown in
As shown in
As used herein, “downstream” and “upstream” are terms that indicate a direction relative to the flow of working fluid through the turbine. As such, the term “downstream” refers to a direction that generally corresponds to the direction of the flow of working fluid, and the term “upstream” generally refers to the direction that is opposite of the direction of flow of working fluid. The term “radial” refers to movement or position perpendicular to an axis or center line. It may be useful to describe parts that are at differing radial positions with regard to an axis. In this case, if a first component resides closer to the axis than a second component, it may be stated herein that the first component is “radially inward” of the second component. If, on the other hand, the first component resides further from the axis than the second component, it may be stated herein that the first component is “radially outward” or “outboard” of the second component. The term “axial” refers to movement or position parallel to an axis. Finally, the term “circumferential” refers to movement or position around an axis. Although the following discussion primarily focuses on turbines, the concepts discussed are not limited to turbines and may apply to any rotating machinery.
As shown in
A support member assembly 38 provides support between the inner turbine shell 14 and the outer turbine shell 16. In the case of an inner turbine shell 14 comprising a single-piece construction, the assembly 38 may be located between the inner turbine shell 14 and the outer turbine shell 16 on opposite sides at approximately the vertical midpoint (i.e., approximately half of the distance between the top and bottom of the inner turbine shell 14) of the inner turbine shell 14. In other embodiments having multi-piece inner turbine shell 14, the system may include multiple support member assemblies 38 evenly spaced around the periphery of the inner turbine shell 14. In an embodiment, the outer turbine shell 14 includes shelf members 70 configured to contact the support member assembly 38.
The depicted embodiment of the support member assembly 38 reduces the friction between two independent static turbine structures, such as the inner turbine shell 14 and outer turbine shell 16. As shown in
The exemplary support member 40 comprises a substantially square block with round edges. The support member 40 is a stiff structure that is able to roll or rotationally move 58 as the inner and outer shell structures 14 and 16 move relative to each other. The support member 40 includes biasing members 48 and 52 to support the block. In an embodiment, the biasing members 48 and 52 are springs positioned proximate corners of the support member 40. Specifically, the biasing members 48 are positioned in the recess 42 and contact support surface 46 and lateral surfaces 50 to retain the support member 40 when the member is not in contact with the support surface 44. In an example, by retaining the support member 40 within the recess 42, the position and orientation of the support member 40 is maintained. Further, the biasing members 48 are configured to have a selected stiffness to allow the rotational movement 58 of the support member 40 during relative movement of the shell structures 14, 16. The biasing members 52 provide support and enable the support member 40 to maintain the desired orientation when forces, such as gravity, cause the curved surface 54 to contact the support surface 44.
Relative movement of the shell structures 14, 16 causes the support member 40 to roll and rotate a small angle 60. For example, a relative movement between the inner shell structure 14 and outer shell structure 16 of about 0.200 inches may result in a rotation of about 4 degrees for the small angle 60. In addition, curved surfaces 54 and 56 contact support surfaces 44 and 46, respectively, to allow rotational movement 58 with reduced friction. The exemplary curved surfaces 54, 56 comprise a high strength material, such as high strength stainless steel or high nickel alloy. In embodiments, the entire support member 40 may comprise the high strength material or may have the block portion comprise a different material, such as carbon steel or other suitable stainless steel. Reduced friction provided by the support member assembly 38 enables reduced clearances between adjacent turbine parts, such as shell structures 14, 16, to improve performance and efficiency. Further, the reduced friction provided by the support member 40 reduces eccentricity and out of roundness for components while reducing costs.
In an embodiment, two or more support members are placed at each support member assembly 38 location (as shown in
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 can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate 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.
