Combustion – Combustion bursts or flare-ups in pulses or serial pattern
Patent
1993-05-18
1995-10-03
Price, Carl D.
Combustion
Combustion bursts or flare-ups in pulses or serial pattern
122 24, F23C 1104
Patent
active
054547113
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a burner for pulsating combustion with an explosion chamber which on the inlet side connects to a supply tube for combustion air and a supply tube for fuel and on the outlet side is connected to one or more discharge tubes for the combustion gases, as described in the Netherlands patent application NL-A-89 01416 of applicant.
2. Description of the Prior Art
In such a burner as described in Netherlands patent application NL-A-89 01416, the explosion chamber and the supply and discharge tubes serving as resonance tubes are dimensioned such that the frequency of the periodic ignitions of the combustible mixture in the explosion chamber corresponds with the natural frequency of the gas mass in these tubes and the explosion chamber.
Due to the inertia of the gases flowing in the discharge tube there results an underpressure in the explosion chamber after combustion, whereby on the one side fuel and air are drawn in and on the other side hot combustion gases flow back to the explosion chamber which ignite the combustible mixture that has flowed in. A cyclic process hereby results which pulsates with a frequency substantially dependent on the dimensions of the explosion chamber, the supply and discharge tubes and the nature of the fuel.
Such devices are employed for heating, drying, concentration by evaporation, driving gas turbines, etc. and have the advantage of a high heat transfer coefficient, whereby the device can take a compact form while a practically complete combustion is obtained at an air factor 1 with almost no emission of CO and very little formation of NO.sub.x.
In non-damped embodiments the explosion of the fuel produces a great deal of noise (between 90 and 140 db(A)), which produces a nuisance for the surrounding area.
SUMMARY OF THE INVENTION
The invention has for its object to provide a burner for pulsating combustion which produces considerably less noise than the known devices.
According to the invention this object is achieved by providing the explosion chamber with a widening on the outlet side and connecting the discharge tube(s) to this widening at or close to the periphery thereof. In this widening, which preferably extends perpendicularly of the centre line of the explosion chamber, explosion waves are reflected back and forth between the walls of this widening whereby the noise emission is markedly decreased.
The widening preferably has a shape such that the sound waves of successive explosions are shifted a half phase or an odd number of half phases relative to each other. The explosion noise is hereby suppressed by antinoise in counter phase. Use of the invention results in a noise reduction of 15 to 20 db(A).
Further advantages of the invention lie in the enlargement of the heat transfer surface in the high temperature zone, whereby less heating surface can suffice and it is possible to embody the outlet tubes shorter than in the known constructions without this widening.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is further elucidated with reference to the embodiments shown in the drawings, wherein:
FIG. 1 shows a longitudinal section of a boiler for heating liquid, which is provided with a burner according to the invention;
FIG. 2 shows a longitudinal section through a boiler wherein the outlet tubes of the burner form part of the widening and the device is further provided with inspection windows for observing the explosive combustion that occurs;
FIG. 3 shows a cut away perspective view of a further embodiment of the boiler according to the invention;
FIG. 4 shows a burner head in cross section; and
FIG. 5 shows another embodiment of a burner head in cross section.
DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS
For the sake of clarity functionally equivalent components are designated as far as possible in all the figures with the same reference numerals.
The boilers 17 and 18 respectively shown in FIGS. 1 and 2 contain an explosion chamber 1 which forms part of an air feed
REFERENCES:
patent: 2911957 (1959-11-01), Kumm
patent: 3166904 (1965-01-01), Meleneic
patent: 4568264 (1986-02-01), Mullen et al.
patent: 4762487 (1988-08-01), Zappa
patent: 4919085 (1990-04-01), Ishiguro
patent: 4968244 (1990-11-01), Movassaghi
patent: 4993938 (1991-02-01), Thrasher et al.
De Stichting Impuls
Petersen Maxwell J.
Price Carl D.
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