Mounting System for Impingement Cooling Manifold
A manifold mounting system for mounting an impingement cooling manifold to a casing of a turbine including a mounting pin affixed to a shroud pin of the turbine wherein the mounting pin extends through the impingement cooling manifold wherein the mounting pin comprises a securing device operable for securing the mounting pin to the impingement cooling manifold, and a leveling support leg affixed to the impingement cooling manifold wherein the mounting pin, securing device, and leveling support leg are operable for adjusting the gap distance between the impingement cooling manifold and the casing of the turbine.
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This is a continuation-in-part of U.S. application Ser. No. 11/548,791, filed Oct. 12, 2006, entitled “Turbine Case Impingement Cooling for Heavy Duty Gas Turbines” now pending. That application is incorporated herein by reference.
TECHNICAL FIELDThis application relates generally to the field of impingement cooling manifolds for heavy-duty turbines and more particularly to mounting systems for impingement cooling manifolds for heavy-duty turbines.
BACKGROUND OF THE INVENTIONAir impingement cooling has been used to manage the casing temperature of small gas turbines and to reduce and maintain the clearances between rotating blades and accompanying interior casing surfaces. One problem for air impingement cooling systems on heavy-duty gas turbines is the ability to achieve a uniform heat transfer coefficient across large non-uniform non-standard casing surfaces. On small gas turbines, small impingement holes and short nozzle to surface distances are normally applied. These factors produce the required higher heat transfer coefficients on the casing. One detrimental impact of applying small of impingement cooling holes is the need for operating with high differential pressure drop across the holes. This results in the requirement for undesirable high cooling air supply pressures which negatively impacts net efficiency.
Impingement cooling has been applied to aircraft engines as a method of turbine clearance control. However, the impingement systems used on aircraft engines cannot be used in heavy-duty turbine applications. The systems applied to aircraft engines utilize air extracted from the compressor as the cooling medium. It is not feasible to use compressor extraction air on heavy-duty gas turbines because the design heat transfer coefficients require cooler air temperatures. Heavy-duty gas turbines have a significantly larger, non-uniform casing surface that requires an intricate manifold design as compared to aircraft engines. Also, the casing thickness and casing thickness variations are considerably greater on heavy-duty gas turbines.
Accordingly, there is a need in the art for a mounting system for impingement cooling manifolds on heavy-duty gas turbines.
The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will convey the scope of the invention to those skilled in the art.
Referring to
A key contributor in the efficiency of heavy-duty gas turbines is the amount of air/exhaust gas leakage through the blade tip to casing clearance 128. Due to the different thermal growth characteristics of the turbine blades 122 and turbine casing 120, clearances 128 significantly change as the turbine transitions through transients from ignition to a base-load steady state condition. A clearance control system, including its operating sequence may be implemented to address the specific clearance characteristics during all operating conditions. Incorrect design and/or sequencing of the control system may lead to excessive rubbing of the turbine blade 123 tips with the casing shrouds 126, which can result in increased clearances and reduced performance.
As illustrated in the exemplary embodiment of
Referring to the exemplary embodiment illustrated in
The impingement holes 148 may be positioned in an array. In an exemplary embodiment, the impingement holes 148 may be spaced in the range from 1.25 to 2.5 inches. In an exemplary embodiment, the individual impingement holes 148 may be sized between 0.12 and 0.2 inches. The varying hole sizes and spacing are required to compensate for the non-uniformity of the turbine casing geometry. The size and positioning of the impingement holes 148 on the lower plate 146 produce a uniform heat transfer coefficient across the casing targeted by the impingement air-cooling system. However, the impingement holes are not limited to these sizes or spacings. The distance between the upper 142 and lower plates 146 also may be dimensioned to minimize internal pressure variations, which results in uniform cooling hole pressure ratios.
The gap distance 147 between impingement cooling manifold lower plates 146 and the turbine casing 120 effects the heat transfer coefficient. Too large of a gap distance 147 can result in a non-optimum heat transfer coefficient. Too little of a gap distance 147 can result in both non-optimum and a non-uniform heat transfer coefficient. In an exemplary embodiment, a gap of between 0.5 and 1.0 inch provides a suitable heat transfer coefficient. However, the gap distance 147 in not limited to this range and may be any distance that provides a suitable heat transfer coefficient.
An exemplary embodiment may include a plurality of impingement cooling manifolds 140. The plurality of impingement cooling manifolds 140 may be affixed to the casing 120 of the turbine directly above target cooling area. The impingement cooling manifolds 140 may be positioned such that there is ample spacing between their edges and any protrusions off of the casing. The spacing provides a free path for the air passing through the impingement holes 148 to exhaust from under the impingement cooling manifold 140 to the environment. In an exemplary embodiment, the spacing between two adjacent impingement cooling manifolds may be between 1 to 30 inches and is dependent on casing protrusions and flanged joints. The spacing are not limited to these dimensions and may be at any suitable distance. The impingement cooling manifolds 140 also may provide impingement cooling to any of the axial flanges, including a horizontal split joint.
Mounting the ManifoldsThe manifold 140 may be mounted to the casing 120 of the turbine without machining the casing 120. The manifold 140 should maintain a substantially uniform distance from the casing 120 across the entire surface of the manifold 140 for the most efficient and productive air flow across the casing 120. However, turbine casings 120 from unit to unit have wide variations in geometries.
As shown in the exemplary embodiment of
The mounting system also may include at least one leveling support leg 170 to adjust the manifold 140 to create a substantially uniform gap distance 147 between the casing 120 and the manifold 140. The leveling support leg 170 may be affixed to the manifold 140 and positioned against the casing 120. The leveling support leg 170 may be positioned at any location on the manifold 140. In an exemplary embodiment, the at least one leveling support leg 170 may be positioned near the perimeter of the manifold 140. As shown in the exemplary embodiment of
A plurality of mounting pins 150 and a plurality of leveling support legs 170 may be included to mount a manifold 140 and set the gap distance 147. In the exemplary embodiment of
Many modifications and other embodiments of the invention will come to mind to one skilled in the art to which this invention pertains having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the invention is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in generic and descriptive sense only and not for purposes of limitation.
Claims
1. A manifold mounting system for mounting an impingement cooling manifold to a casing of a turbine comprising:
- a mounting pin affixed to a shroud pin of the turbine wherein the mounting pin extends through the impingement cooling manifold wherein the mounting pin comprises a securing device operable for securing the mounting pin to the impingement cooling manifold; and
- a leveling support leg affixed to the impingement cooling manifold wherein the mounting pin, securing device, and leveling support leg are operable for adjusting the gap distance between the impingement cooling manifold and the casing of the turbine.
2. The system of claim 1 wherein the securing device comprises a setting nut to adjust the gap distance between the impingement cooling manifold and the casing of the turbine.
3. The system of claim 1 wherein the leveling support leg comprises a leveling screw and a leveling nut.
4. The system of claim 1 wherein the leveling support leg is affixed to a flange of the impingement cooling manifold.
5. The system of claim 1 comprising a plurality of mounting pins and a plurality of leveling support legs.
6. A mounting system for an impingement cooling manifold cooling system for heavy duty turbines comprising:
- an impingement cooling manifold affixed to a casing of the turbine, wherein the impingement cooling manifold comprises a plurality of impingement holes in the surface of the impingement cooling manifold;
- a blower that provides air flow across the plurality of impingement holes of the impingement cooling manifold to cool the casing of the heavy-duty turbine to control the clearance between a tip of a turbine blade and a shroud of the heavy-duty turbine;
- a mounting pin affixed to a shroud pin of the turbine wherein the mounting pin extends through the impingement cooling manifold wherein the mounting pin comprises a securing device operable for securing the mounting pin to the impingement cooling manifold; and
- a leveling support leg affixed to the impingement cooling manifold wherein the mounting pin, securing device, and leveling support leg are operable for adjusting the gap distance between the impingement cooling manifold and the casing of the turbine.
7. A method for mounting an impingement cooling manifold system to a casing of a turbine comprising:
- affixing a mounting pin to an existing shroud pin of the turbine wherein the mounting pin extends through the impingement cooling manifold;
- securing the impingement cooling manifold to the mounting pin wherein the mounting pin comprises a securing device operable to adjust a gap distance between the impingement cooling manifold and the casing of the turbine; and
- affixing a leveling support leg to the impingement cooling manifold operable to adjust the gap distance between the impingement cooling manifold and the casing of the turbine.
8. The method of claim 7 further comprising:
- adjusting the gap distance between the impingement cooling manifold and the casing of the turbine using the mounting pin, securing device of the mounting pin, and/or the leveling support legs.
Type: Application
Filed: Mar 27, 2007
Publication Date: Mar 12, 2009
Applicant: General Electric Company (Schenectady, NY)
Inventors: Dean Erickson (Simpsonville, SC), Hua Zhang (Greer, SC), Mitch Orza (Roswell, GA)
Application Number: 11/691,668
International Classification: F01D 25/28 (20060101);