Power plants – Combustion products used as motive fluid – Combustion products generator
Reexamination Certificate
1999-01-11
2001-06-12
Freay, Charles G. (Department: 3746)
Power plants
Combustion products used as motive fluid
Combustion products generator
C060S748000
Reexamination Certificate
active
06244051
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to burners for combustion chambers of gas turbines.
BACKGROUND OF THE INVENTION
One example of a gas turbine burner is disclosed by German Patent Application P 44 44 961.
Accordingly, there are needs for reduction of pollutants that arise when burning kerosene in combustion chambers of aircraft engines is a constant development goal. The pollutant-reduced combustion chambers. Components of the combustion chamber must be optimized for realizing the pollutant-reduced combustion concepts. Thus, for example, it is important to atomize the fuel as finely as possible in all operating ranges and blend it with the combustion air. This fuel processing is accomplished with air atomizer nozzles in combustion chambers of modern aircraft gas turbines. According to their function principle, the fuel flows on a cylindrical surface to the end thereof, where the atomization begins due to the air shearing forces. In order to avoid undesired enrichments of fuel in the combustion space of the combustion chamber that can lead to soot, the air stream through the atomizer nozzle is divided into a primary and secondary flow channels and oppositely twisted, so that oppositely directed rotation eddies are generated in the combustion space. To this end, a twist mechanism radially impacted by the flow is allocated to each flow channel. A high twist factor of the air stream also leads to a recirculation turbulence at the back wall of the combustion space, which is intended to achieve a homogeneous burning. In order to avoid a premature blending of the two air streams, which would in turn lead to a reduction of the circumferential velocity in the secondary air stream, the atomizer lip that separates the primary from the secondary air stream is implemented optimally long, up to the discharge of the atomizer nozzle at the side of the combustion space. With such atomizer nozzles and convergent-divergently implemented flow channels, however, the atomization does not take place
Furthermore, the mass stream of the secondary air stream must be greater than that of the primary air stream, so that the circumferential impulse of the secondary air stream is not completely dismantled in the short distance from the end of the atomizer lip up to the entry into the combustion space and the creation of the recirculation turbulence is jeopardized. However, not that the distribution of the air-fuel relationship at the nozzle discharge does not exhibit the desired homogeneity because the primary air stream, which mainly participates in the mixing process, is less than the secondary air stream.
SUMMARY OF THE INVENTION
GB 2 272 756 A discloses an injection device for a combustion chamber that comprises an atomizer, a plurality of channels and a pre-mixing path, whereby the fuel is first atomized at baffled elements with atomizer lips surrounding the channels and is subsequently mixed in the pre-mixing path is with the air streams form the channels that discharge into pre-mixing path. The pre-mixing path is convergent-divergently fashioned in order to assure a good mixing of the atomized fuel with the air streams.
GB 1 099 959 and GB 2 094 464 A discloses a burner for solid or liquid fuels, whereby the fuel is mixed with a plurality of air streams and, whose channels are formed by concentrically arranged pipes with divergent discharge nozzles. Upon utilization of liquid fuels, this is atomized in an atomizer means at the point of entry into the nozzle space.
The present invention provides a burner that enables a far-reaching homogeneous distribution of the air-fuel mixture in the combustion space.
The present invention pertains to burners for combustion chambers of gas turbines. The burner has an atomizer nozzle for atomizing fuel in the combustion air that flows through a primary and secondary flow channel upstream of the combustion space of the combustion chamber. The flow channels discharge into the combustion space and are separated by a first component part that is concentrically arranged with respect to a burner access and has a sleeve-shaped atomizer lip that proceeds cylindrically or conically tapering. The outer, secondary flow channel is radially outwardly limited by a concentrically arranged, annular second component part with a convergent-divergently proceeding inside wall. The second component part forms a location of a narrowest flow cross-section at an axial height or upstream therefrom the radially inwardly arranged, first component part with the atomizer lip ends. An air stream flows through the flow channels with an isodirectional twist.
The invention has the advantage that, due to the isodirectional twist of the two air streams and, a mixing thereof before entry into the combustion space a high circumferential velocity can be maintained and the mass stream relationship can also be selected independently of the twist of the streams in order to be able to homogeneously fashion the distribution of the air-fuel mixture. The twist factor of the air stream can also be varied disregarding a mixing of the two streams in order to set a detached or a wall-adjacent flow condition in the combustion space. As a result of positioning the atomizer lip at the narrowest flow crossection in the atomizer nozzle or shortly therebefore, the atomization of the fuel can ensue in an area of the maximum air shearing forces, so that the atomization can ensue optimally.
REFERENCES:
patent: 5285631 (1994-02-01), Bechtel, II et al.
patent: 5373693 (1994-12-01), Zarzalis et al.
patent: 5623827 (1997-04-01), Monty
patent: 5647538 (1997-07-01), Richardson
patent: 5765376 (1998-06-01), Zarzalis et al.
patent: 5836163 (1998-11-01), Lockyear et al.
patent: 1099959 (1968-01-01), None
patent: 2 094 464 (1982-09-01), None
patent: 2 272 756 (1994-05-01), None
Glaeber Bernhard
Ripplinger Thomas
Simon Burkhard
Zarzalis Nikolaos
Freay Charles G.
Schiff & Hardin & Waite
Torrente David J.
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