Power plants – Combustion products used as motive fluid – Combustion products generator
Patent
1998-04-21
2000-04-18
Gartenberg, Ehud
Power plants
Combustion products used as motive fluid
Combustion products generator
60737, 239463, F23C 700
Patent
active
060500964
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates to a fuel injector arrangement for a combustion apparatus utilising fluid fuel. It is concerned particularly, but not exclusively, with such an injector arrangement for a turbine, especially a gas turbine, but it is also suitable for use with liquid fuels and in combustion apparatus other than turbines.
Various fuel injectors have been described in the art. For example in EP 0 660 038 there is described a fuel injection apparatus in which fuel is supplied to an annular lip on an annular member and the fuel is then atomised, as it flows from the lip, by first and second coaxial airflows created by first and second arrays of swirler vanes.
Various arrangements of introducing fuel into an air flow have been described, e.g. in WO 95/02789 gas injectors are shown provided in swirl vanes. Further, curved swirl vanes have been described (see e.g. EP 0393 484).
SUMMARY OF THE INVENTION
Environmental considerations per se, as well as legislation in the environmental field mean that it has become essential to ensure that the levels of pollutant emission from all combustion apparatus and in particular the emission of the nitrogen oxides (NO.sub.x) is reduced to as low levels as possible. One way of reducing such emission is to ensure efficient mixing of the air/fuel mixture to thereby obtain efficient combustion. Various injection and mixing arrangements have been described which purport to give efficient mixing but in practice it has been found difficult to ensure such mixing over the wide range of fuel-air ratios encountered in practice, and especially ratios encountered under low-power conditions, i.e. close to flame extinction.
It is an object of the present invention to provide a fuel injection arrangement, e.g. for a turbine, which gives efficient mixing and combustion over a wide range of fuel-air ratios and thereby ensures low NO.sub.x emissions over a range of operating conditions.
According to the invention there is provided a fuel injector arrangement for a combustion apparatus, comprising at least one passage for the flow of fluid, said passage being of substantially annular cross-section, being defined by a radially inner wall and a radially outer wall and having an inlet region and an outlet region, wherein the inlet region incorporates a plurality of vanes adapted to modify a flow pattern of a fluid entering said inlet region, such that fluid passing from the inlet region to the outlet region has a composite flow pattern having both an axial component and a component rotational about the longitudinal axis of the passage wherein each vane is provided with a root and a mid-region and a tip, the vane being contoured such that an existing axial flow of fluid entering said inlet region continues substantially unaffected at the root and tip but is partly converted into a rotational flow as it flows past the mid-region.
In a preferred arrangement the root and/or the tip are of reduced width relative to the mid-region.
It is further preferred that the vanes are adapted to provide a continuous radial variation in said axial and rotational components.
It is particularly contemplated that progressively between the root and the mid-region and between the tip and the mid-region, the fluid is given a rotational component whereby the fluid is caused to spiral along the passage.
Each vane may be set at an angle to a longitudinal axis of the injector arrangement.
In one embodiment it is provided that, in use, air enters the inlet region and fuel enters the annular passage at at least one position between the inlet region and the outlet region; fuel may enter the annular passage through at least one hole in a wall of the annular passage, and/or fuel may enter the annular passage through at least one hole in a said vane.
Each vane may have a straight leading edge and a curved trailing edge and the trailing edge may be of convex or concave form as viewed in the direction of an axial fluid flow component.
Alternatively the leading edge may be curved.
The trailing edge
REFERENCES:
patent: 2752753 (1956-07-01), Dooley
patent: 5251447 (1993-10-01), Joshi et al.
patent: 5274995 (1994-01-01), Horner et al.
patent: 5658358 (1997-08-01), Chyou et al.
European Gas Turbines Ltd.
Gartenberg Ehud
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