Combustion – Fuel disperser installed in furnace – Plural feed means extending to common wall opening of furnace
Reexamination Certificate
2000-02-14
2001-12-04
Lazarus, Ira S. (Department: 3743)
Combustion
Fuel disperser installed in furnace
Plural feed means extending to common wall opening of furnace
C239S422000, C239S424500
Reexamination Certificate
active
06325618
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the field of combustion technology, as used in particular in gas turbines. It relates to a fuel lance for spraying liquid and/or gaseous fuels into a combustion chamber.
BACKGROUND OF THE INVENTION
Publication DE-A1-43 26 802 discloses a fuel lance, for spraying liquid or gaseous fuels into a combustion chamber. The fuel lance is part of an secondary or tertiary burner, around which a combustion air jet flows in a main flow direction, and comprises inside an outer lance shell a liquid-fuel passage for supplying liquid fuel, a gas passage surrounding the liquid-fuel passage and intended for supplying gaseous fuel, and an air passage surrounding the gas passage and intended for supplying cooling or atomizing air, and first means for the radial spraying of the liquid fuel from the liquid-fuel passage into the combustion chamber, and second means for the radial spraying of the gaseous fuel from the gas passage into the combustion chamber see publications U.S. Pat. Nos. 5,431,018, 5,626,017 and EP-A1-0 620 362). In this case, the nozzles for gaseous fuel and liquid fuel (oil, etc.) are combined.
In the publication referred to, the spraying of the liquid fuel is effected according to the so-called air-blast principle, i.e. the fuel applied as a film to an atomizer lip is atomized in the shearing zone of the surrounding air flow and is admixed to the combustion air as a fuel mist. If the spraying is effected transversely to the flow direction of the combustion air, the penetration depth is determined solely by the air impulse. The natural impulse of the liquid fuel is merely utilized for producing the film but not for assisting the fuel jet.
To produce as homogenous an air/fuel mixture as possible, it is necessary for the fuel from the wake of the nozzle to be distributed in the cross section of the combustion air. During high transverse flows, a correspondingly high jet impulse is necessary. This high jet impulse cannot be achieved with the atomizing air alone. Therefore the natural impulse of the sprayed liquid fuel (or the gaseous fuel) is to be utilized in an assisting manner. The disintegration of the fuel jet is effected by jet instabilities after a few jet diameters of running length.
SUMMARY OF THE INVENTION
The object of the invention is therefore to provide a fuel lance for the, spraying of liquid fuel and/or gaseous fuel into a secondary or tertiary burner, which fuel lance avoids the abovedescribed disadvantages of previous lances and permits in particular a reduction in the retention time of the liquid fuel in the premix section and thus a reduction in the admixed proportion of water.
The object is achieved by spraying the liquid fuel as a plain jet radially to the main flow direction by means of a suitable guide-tube arrangement. The result of this type of spraying is that the retention time of the liquid fuel in the premix section is reduced and thus less water has to be added in order to prevent a flame flashback. A further advantage is the improved air/fuel mixture due to this arrangement. In particular, the existing air-flow zone, already optimized for the gas spraying, of the main flow may thus also be utilized for the atomizing and mixing of the liquid fuel.
Especially favorable flow conditions result if, in a first preferred embodiment of the fuel lance according to the invention, the two guide tubes end flush with the inner contour of the lance shell.
The spraying of the gaseous fuel and of the surrounding air sheath is of especially favorable configuration if, in a second preferred embodiment, the second guide tube, in the region of the air passage, narrows conically in outside diameter toward the orifice, and the first guide tube, in the region of the gas passage, narrows conically in outside diameter toward the orifice.
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patent: 4854127 (1989-08-01), Vinson et al.
patent: 5101633 (1992-04-01), Keller et al.
patent: 5431018 (1995-07-01), Keller
patent: 5487659 (1996-01-01), Eroglu et al.
patent: 5626017 (1997-05-01), Sattelmayer
patent: 5857846 (1999-01-01), Sattelmayer et al.
patent: 43 26 802 (1995-02-01), None
patent: 195 35 370 (1997-03-01), None
patent: 0 597 221 (1994-05-01), None
patent: 0 620 362 (1994-10-01), None
patent: 0580078008 (1983-05-01), None
Benz Urs
Eroglu Adnan
Joos Franz
Alstom (Switzerland) Ltd.
Burns Doane Swecker & Mathis L.L.P.
Clarke Sara
Lazarus Ira S.
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