TECHNICAL FIELD

[0101] The present application relates generally to gas turbine engines and more particularly relates to a steam manifold positioned about a transition piece of a combustor so as to provide power augmentation and dynamics damping.

BACKGROUND OF THE INVENTION

[0102] Using a lean fuel air mixture is a known method of decreasing NOx emissions and currently is in use in multiple designs of gas turbine combustion systems. The lean fuel air mixture includes an amount of fuel premixed with a large amount of excess air. Although such a lean mixture reduces the amount of NO _x emissions, high frequency combustion instabilities may result. Such instabilities may be referred to as combustion dynamics. These instabilities may be caused by burning rate fluctuations and may create damaging pressure oscillations that may impact on gas turbine durability. As a result of these instabilities, damping or resonating devices may be used with the combustor.

[0103] Providing additional mass flow into a gas turbine is a known method of enhancing overall gas turbine engine power output and efficiency. Steam injection is commonly used for this purpose. For instance, about a five percent (5%) steam addition to a gas turbine combined cycle system may result in about a ten percent ( 10%) output increase.

Issues may arise, however, because the steam may impact on flame stability and freeze CO oxidation in the combustor. As such, the use of steam injection may limit overall emissions and turndown capabilities of gas turbines. [0104] There is therefore a desire for improved combustion dynamics damping as well as power augmentation systems and methods. Preferably, such systems and methods may increase overall system performance and efficiency while reducing combustion dynamics.

SUMMARY OF THE INVENTION

[0105] The present application thus provides a power augmentation system for a gas turbine engine. The power augmentation system may include a transition piece of a combustor and a steam manifold positioned about the transition piece. The transition piece may include a number of transition piece passageways therethrough and the steam manifold may include a number of manifold passageways therethrough. The manifold passageways may align with the transition piece passageways.

[0106] The present application further provides a power augmentation system for a gas turbine engine. The power augmentation system may include a transition piece of a combustor and a steam manifold positioned about the transition piece. The transition piece may include a number of apertures extending therethrough and the steam manifold may include a number of tubes extending therethrough such that the apertures align with the tubes. The tubes may include a predetermined size based upon the frequency of the combustor.

[0107] The present application further provides a power augmentation system for a gas turbine engine. The power augmentation system may include a combustor and a steam manifold positioned about the combustor. The combustor may include a number of apertures extending therethrough and the steam manifold may include a number of tubes extending therethrough. The tubes may include a predetermined size based upon the frequency of the combustor. [0108] These and other features and improvements of the present application will become apparent to one of ordinary skill in the art upon review of the following detailed description when taken in conjunction with the several drawings and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0109] Fig. 1 is a schematic view of a gas turbine engine.

[0110] Fig. 2 is a perspective view of a steam manifold system as is described herein. [0111] Fig. 3 is a side cross-sectional view of the steam manifold system of Fig. 2. [0112] Fig. 4 is a further side cross-sectional view of the steam manifold system of

Fig. 2.

DETAILED DESCRIPTION

[0113] Referring now to the drawings, in which like numbers refer to like elements throughout the several views, Fig. 1 shows a schematic view of a gas turbine engine 10. As is known, the gas turbine engine 10 may include a compressor 20 to compress an incoming flow of air. The compressor 20 delivers the compressed flow of air to a combustor 30. The combustor 30 mixes the compressed flow of air with the compressed flow of fuel and ignites the mixture. (Although only a single combustor 30 is shown, the gas turbine engine 10 may include any number of combustors 30.) The hot combustion gases are in turn delivered to a turbine 40. The hot combustion gases drive the turbine 40 so as to produce mechanical work.

The mechanical work produced in the turbine 40 drives the compressor 20 and an external load 50 such as an electrical generator and the like. The gas turbine engine 10 may use natural gas, various types of syngas, and other types of fuel. The gas turbine engine 10 may have many other configurations and may use other types of components. Multiple gas turbine engines 10, other types of turbines, and other types of power generation equipment may be used herein together.

[0114] Figs 2-4 show a power augmentation system with dynamics damping or a steam manifold system 100 as is described herein. The steam manifold system 100 may be positioned at an end 1 10 of a transition piece 120 of the combustor 30. The transition piece 120 directs a stream of hot exhaust gases 125 from the combustor 30 to the turbine 40 as is described above. The transition piece 120 may have a number of apertures 1 30 positioned about the end 1 10 thereof. Any number of the apertures 130 may be used. Some of the apertures 1 30 may be positioned at an angle with respect to the direction of the stream of hot exhaust gases 125 through the combustor 30. The angle may be about 30 to about 60 degrees, although any desired angle may be used herein. The apertures 130 may have any desired size or shape as is described in more detail below.

[0115] The steam manifold system 100 may include a steam manifold 140 positioned about the end 1 10 of the transition piece 120 in the vicinity of the apertures 1 30. The steam manifold 140 may have any desired size or shape. The steam manifold 140 may include an internal cavity 150. The ₍ cavity 1 50 may surround the end 1 10 of the transition piece 120. The steam manifold 140 may have a number of tubes 160 on one end thereon. The tubes 160 may be in communication with the apertures 130 of the transition piece 120. Any number of the tubes 160 may be used. The tubes 160 also may be positioned at an angle with respect to the stream of hot exhaust gases 125. As above, the angle may be about 30 to about 60 degrees although any angle may be used. The tubes 160 may have any desired size or shape as is described in more detail below. The steam manifold 140 also may have a number of purge holes 1 70 positioned therein. Any number of the purge holes 170 may be used herein. The purge holes 170 may have any desired size or shape.

[0116] The steam manifold system 100 may have a steam passage 1 80. The steam passage 180 may be in communication with the cavity 150 of the steam manifold 140. The steam passage 180 may have a valve 190 mounted thereon. The steam passage 180 may be mounted on an aft frame 200 of the transition piece 120. Other positions may be used herein. The steam passage 1 80 may provide a volume of steam 210 to the cavity 1 50 of the steam manifold 140. The quality and characteristics of the steam 210 may vary.

[0117] In use, the steam 210 from the steam passage 180 may pass into the cavity 150 of the steam manifold 140. Most of the volume of the steam 210 passes through the tubes 160 of the steam manifold 140, through the apertures 130 of the transition piece 120 and into the stream of hot exhaust gases 125 towards the turbine 40. A small volume of the steam 21 0 may pass through the purge holes 170 and into a compressor discharge zone, mix with compressor airflow and then pass into combustor, thus reducing NOx emission.

[0118] In a secondary mode of operation, the valve 190 of the steam passage 1 80 may be closed. Air from the compressor discharge zone thus may pass through the purge holes 170, the cavity 1 50 the tubes 160 of the steam manifold 140, and through the apertures 130 of the transition piece 1 20.

[0119] The steam manifold system 100 may be used on a MS6001 V combustor offered by General Electric Company of Schenectady, New York. The steam manifold system 100 may be installed on any type of can, annular, or can-annular type combustion system at the aft end of the transition piece 1 20 or otherwise. [0120] Injection of the steam 210 just upstream of the turbine 40 thus provides for enhanced power output and efficiency. The positioning of the steam manifold 140 about the end 1 10 of the transition piece 120 ensures that the steam 210 is injected downstream of the reaction zone of the combustor 30 and just upstream of the turbine 40. The injection 40 of the steam 210 thus does not impact on the reaction temperature of the combustor 30 such that CO emissions should not increase. The impact on flame stability also is lessened.

[0121] The steam manifold system 100 also may act as a type of a Helmholtz resonator. A Helmholtz resonator provides a cavity having a sidewall with openings therethrough. The fluid inertia of the gasses within the pattern of the apertures 130 and the tubes 160 may be reacted by the volumetric stiffness of the closed cavity 150 so as to produce a resonance in the velocity of the flow of the steam 210 therethrough. The number, length, diameter, shape, position of the apertures 130, the tubes 160, and the volume of the cavity 1 50 may vary with respect to the damping frequency range. Specifically, the design criteria may include the size of the apertures 130 and the tubes 160, the diameter of the apertures 1 30 and the tubes 160, the number of the apertures 130 and the tubes 1 60, the mass flow rate through the cavity 1 50, and the volume of the cavity 1 50.

[0122] The dynamic pulsation spectrum of the combustor 30 may be determined from known testing methods. The apertures 130 and the tubes 160 are sized to allow low velocity steam to discharge into combustor 30. As such, the dynamic pressure pulsations at any frequency may be dampened by the steam manifold system 100. Further, the frequencies may be dampened without the use of a separate resonator. Any number of steam manifolds 140 may be used herein such that a number of different frequencies can be dampened. [0123] The steam manifold system 100 thus provides power augmentation to the gas turbine engine 10 with minimal impact on increasing CO emissions or flame stability. Likewise, the steam manifold system 100 may effectively damp dynamic pulsations in the combustor 30 so as to improve operability and lessen durability risks. The steam manifold system 100 thus generally increases power output while also decreasing forced outages and combustion inspection intervals. As such, the steam manifold system 100 may reduce repair and operation costs.

[0124] It should be apparent that the foregoing relates only to certain embodiments of the present application and that numerous changes and modifications may be made herein by one of ordinary skill in the art without departing from the general spirit and scope of the invention as defined by the following claims and the equivalents thereof.

POWER AUGMENTATION SYSTEM WITH DYNAMICS DAMPING

gas turbine engine

compressor

combustor

turbine

external load

steam manifold system

end

transition piece

exhaust gases

apertures

steam manifold

cavity

tubes

purge holes

steam passage

valve

aft frame

steam