FIELD OF THE INVENTION
The disclosure relates generally to a venturi for a dry low nitric oxides (NOx) emissions combustor, and more particularly to a leakage reducing venturi for a dry low nitric oxides (NOx) emissions combustor.
BACKGROUND OF THE INVENTION
The riveted joints located at the venturi of current dry low nitric oxides (NOx) emissions combustor (DLN combustors) allow a variable air leakage into the combustion chamber. This air leakage has been identified as a key contributor to combustion emissions, as well as combustor-to-combustor variation. Accordingly, a leakage reducing means for associating the venturi with the liner of DLN combustors would be desirable.
SUMMARY
Disclosed is a leakage reducing venturi for a dry low nitric oxides (NOx) emissions combustor, the venturi including a substantially annular outer liner, a substantially annular inner liner, a venturi channel defined by the annular inner liner and the annular outer liner, the venturi channel including a forward end and an aft end, a forward weld disposed in proximity to the forward end of the venturi channel, the forward weld being configured to connect the annular outer liner with the annular inner liner, and an aft weld disposed in proximity to the aft end of the venturi channel, the aft weld being configured to connect the annular outer liner with the annular inner liner.
BRIEF DESCRIPTION OF THE DRAWINGS
The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike:
FIG. 1 is a simplified representation of a cross section of a combustor including an exemplary embodiment of a leakage reducing venturi; and
FIG. 2 is a simplified cross section of the leakage reducing venturi of the combustor of FIG. 2.
DETAILED DESCRIPTION OF THE INVENTION
Referring of FIG. 1, a portion of a dry low nitric oxides (NOx) emissions combustor 10 (“dry low NOx” meaning less than 9 ppm NOx) for a gas turbine is illustrated. The combustor 10 includes generally a combustion chamber 12, fuel nozzles 14 (some gas turbines, as illustrated here, employ multiple nozzles in each combustor), an annual premixing chamber 16, and a leakage reducing venturi 18 (the venturi being described in greater detail below). A turbine compressor (which is not shown) provides airflow into the premixing chamber 16. Fuel 20 is provided to the chamber 16 via the fuel nozzles 14, which are controlled a fuel flow controller 26. Air is introduced to the chamber 16 via one or more entry ports 28.
The combustion chamber 12 is generally cylindrical in shape about a combustor centerline 30, and is enclosed by a wall 32 and a parent liner or wall 34. The fuel-air mix that enters the combustion chamber 12 from the premixing chamber 16 travels in a downstream direction, as indicated by arrows 36. Upon leaving the premixing chamber 16, the fuel-air mix is constricted by convergent/divergent walls 38 and 40 of the venturi 18. The flow re-circulation introduced by the venturi 18 acts as a bluff body flame holder. This causes the fuel-air mix to accelerate into the combustion chamber 12, where it will combust and create enormous amounts of heat flux on the venturi 18.
As shown in FIGS. 1 and 2, the leakage reducing venturi 18 includes a substantially annular outer liner 42, a substantially annular inner liner 44, which are integrated into the parent liner 34 of the combustor 10. The outer liner 42 and inner liner 44 define a venturi channel 46, which includes a forward end 48 and an aft end 50. The venturi channel 46 is designed to ingest cooling air (compressed air) through inlets 51 that are disposed in the outer liner 44, and in fluid communication with the venturi channel 46. This cooling/compressed air is provided by the turbine compressor (which is not illustrated), and creates a cooling effect on the venturi 18. It should be appreciated that, for purposes of this disclosure, the venturi 18 is defined to include the extents of the venturi channel 46 (i.e. the forward end 48 of the channel 46 to aft end 50 of the channel 46) as illustrated in FIGS. 1 and 2.
Referring to FIG. 2 in particular, the venturi 18 also includes a forward weld 52 and an aft weld 54. The forward weld 52 is disposed at the forward end 48 of the venturi channel 46, such that a forward extent of the channel 46 terminates at the forward weld 52. Conversely, the aft weld 54 is disposed at the aft end 50 of the venturi channel 46, such that and aft extent the channel 46 terminates at the forward weld 52. Thus, in the exemplary embodiment of FIGS. 1 and 2, the forward weld 52 and aft weld 54 are disposed at opposite ends of the venturi channel 46. In addition, both the forward weld 52 and aft weld 54 connect the annular outer liner 42 with the annular inner liner 44. In the exemplary embodiment of FIGS. 1 and 2, the forward weld 52 and aft weld 54 provide these connections via a welding of the inner annular liner 42 and outer annular liner 44 to a forward y-joint 60 and aft y-joint 62 respectively. The y-joints 60 and 62 allow for a continuous leak free path in the channel 46, which minimizes air leakage through venturi joints, provides a cavity for impingement cooling, and allows the venturi 18 to be constructed with acceptable stresses. As is shown in the Figures, these y-joints 60 and 62 include a generally “y” like shape, which includes three prongs 70, 72, and 74. Prongs 70 and 72 connect the joints 60 and 62 to the two walls of the channel 46 (via welds 52 and 54), while prong 74 connects each joint 60 and 62 to the parent liner 34. Associating the venturi 18 with the parent liner 34 of the combustor 10 via these forward and aft welds 52 and 54 (and y-joints 60 and 62) renders any riveted venturi joints unnecessary, and minimizes air leakage variation from combustor to combustor. This welding thus reduces emissions causing leakage into the combustion chamber 12.
It will be noted that while the invention has been described with reference to an exemplary embodiment, it should be understood that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or substance to the teachings of the invention without departing from the scope thereof. Therefore, it is important that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the apportioned claims. Moreover, it will be further noted that unless specifically stated any use of the terms first, second, etc. do not denote any order or importance, but rather the terms first, second, etc. are used to distinguish one element from another.
Patent Application
20090053054
