Combustion – Fuel disperser installed in furnace – Plural feed means extending to common wall opening of furnace
Patent
1995-03-24
1997-09-23
Price, Carl D.
Combustion
Fuel disperser installed in furnace
Plural feed means extending to common wall opening of furnace
431181, 110261, 110263, 239553, F23D 100
Patent
active
056697660
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention concerns burner nozzles of the kind which direct streams of mixed fossil fuel and air into a combustion chamber, where the mix is burned so as to heat water and generate steam for the purpose of power generation.
BACKGROUND OF THE INVENTION
Such nozzles may be of circular or rectangular cross sectional shape, and in both cases comprise co-axial, nested passages which are fed from a common fuel/air input conduit, plus a further, outer passage for a flow of air per se.
U.S. Pat. No. 4,654,001 discloses a circular fuel burner nozzle which comprises an outer tubular housing having a stabiliser located therein to define coaxial passages. Members are provided intermediate the housing and the stabilizer to mix the fuel passing through the passages. Discharge vanes are disposed in the end region of the nozzle between the stabilizer and the tubular housing to reduce the turbulence of the mixed fuel as it emerges from the nozzle.
Although the fuel burner nozzle disclosed in U.S. Pat. No. 4,654,001 reduces NOx formation it is desirable to create conditions wherein once the fuel/air mix ignited, a flame attaches to the outlet plane of the nozzle and stays attached for the duration of the primary flow. In known arrangements, bluff members are provided about the outlet which enable the said attachment.
If the flow of fuel/air varies, problems arise by way of the flame detaching from the nozzle outlet. Rectangular nozzles suffer less from this phenomenon than do circular nozzles. In the latter type, swirl vanes have been incorporated in the outer fuel/air subsidiary flow passages and have reduced but not obviated the tendency of the flame to detach. Such vanes cannot be used in rectangular nozzles. Consequently some detachment occurs in both types of burner nozzle.
The present invention seeks to provide an improved fossil fuel/air burner nozzle.
According to the present invention a fossil fuel/air burner nozzle comprises a primary nozzle having nested, coaxial passages connected to a common supply conduit for the receipt of a flow of mixed fossil fuel and air and wherein the outer one of the nested passages is provided at its inlet end with a wall which lies in a plane normal to its axis, characterised in that the said wall has apertures therein which are spaced about said axis in symmetrical manner, and within its outlet end said passage is provided with a peripheral equi angular array of bluff members each of which is axially aligned with a respective aperture.
The cross sectional shape of a burner in accordance with the present invention may be circular or rectangular.
In one embodiment of the present invention the apertures are substantially triangular in profile, the apex or quasi apex thereof being at the radially outward portion of each aperture.
In a second embodiment of the present invention the apertures are trapezoidal in profile, the narrower end being radially outward of the wider end.
A burner in accordance with the present invention may include a further aperture wall arranged in face to face sliding engagement with said apertured wall, so as to enable variable overlapping of said apertures for achievement of aperture area variation.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described by way of example and with reference to the accompanying drawings in which:
FIG. 1 is an axial cross sectional part view of a fossil fuel burner nozzle in accordance with one embodiment of the present invention.
FIG. 2 is a view on line 2--2 in FIG. 1.
FIG. 3 is a view in the direction of arrow 3 in FIG. 1.
FIG. 4 is a fuel/air flow velocity diagram.
FIG. 5 is an end view of a fossil fuel burner nozzle in accordance with a further aspect of the present invention.
FIG. 6 is a further aspect of the present invention.
FIGS. 7 and 8 depict still further embodiments of the present invention.
FIG. 9 is a cross-sectioned part view in the direction of arrows 9--9 in FIG. 7.
FIGS. 10 and 11 depict other modifications applied to the fossil fuel burner of FIG. 7.
DE
REFERENCES:
patent: 1342135 (1920-06-01), Schmidt
patent: 4654001 (1987-03-01), LaRue
patent: 4930430 (1990-06-01), Allen et al.
patent: 5299512 (1994-04-01), Olsen
patent: 5347937 (1994-09-01), Vatsky
Price Carl D.
Rolls-Royce Power Engineering plc
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