Combustion – Process of combustion or burner operation – In a porous body or bed – e.g. – surface combustion – etc.
Patent
1990-01-24
1993-06-01
Price, Carl D.
Combustion
Process of combustion or burner operation
In a porous body or bed, e.g., surface combustion, etc.
431326, F23D 1410
Patent
active
052154572
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to a process and equipment to obtain efficient combustion of gas by means of an atmospheric burner.
BACKGROUND OF THE PRIOR ART
Burners for gaseous fuels are generally divided into fan-assisted burners and atmospheric burners.
In general, in using atmospheric burners an imperfect combustion may occur, with harmful emissions of carbon monoxide and nitric oxides which can cause atmospheric pollution.
EP-A-0009831 refers to an atmospheric burner (POLIDORO) in which the perforated surface of a cylindrical burner diffuser consists of transverse groups comprising subgroups of slots spaced out 2 mm in a transverse direction, with pilot holes at each end. Each sub-group consists of a densely-packed series of parallel transverse slot with center distance of only 1.2 mm, in order to obtain a "single flame front" from each group, i.e., a big vertical flame, with the aim of reducing burner noise and providing high thermal power.
Also known, per EP-A-0217470, is an atmospheric burner (NEFIT) in which the primary air-gas mixture, drawn in through a Venturi tube, is then directed downwards at the outlet of this tube. The flow is then fed back, up at the side with turbulence reduced to a minimum, to feed the slots in a perforated diffuser. The purpose is to obtain combustion which is as uniform as possible, "without any disturbing noise being produced". In fact (see figures) the surfaces of the diffuser of the body present groups of slots similar to EP-A-0009831.
Also, DE-A-2132968 (FOGLIANI, PANINI and VECCHI), teaches covering of an atmospheric burner equipped with small groups of slots arranged close together and/or rows of holes, aligned transversely, with the relative pilot holes at the ends. The burner body has a polygonal cross-section, in particular featuring a diffuser with two angled sides which, as shown in FIG. 2, have slots across the joint between these sides, creating a double-horned flame on a transverse plane of the diffuser itself. The flame in this burner is more stable and noise level is reduced.
However, prior art does not envisage the reduction of harmful emissions of nitrogen oxides and carbon monoxide. This may be justified by the fact it was considered impossible to solve the problem of reducing pollutant emissions from atmospheric burners simply by acting on the combustion method or on the proportioning of the burner itself.
SUMMARY OF THE DISCLOSURE
The object of this invention is to provide a process and an atmospheric burner to obtain gas combustion having very low levels of harmful emissions.
This and related objects are realized by providing a combustion process, in a novel atmospheric burner.
The novel process involves the steps of:
aspiring, by means of a Venturi tube, an amount of primary air equal to at least 80% of the air stoichiometrically required for combustion;
enabling a flow of secondary air to contact the gas-primary air mixture immediately after ignition to bring the total air involved to a level above the stoichiometric value; and
starting and completing combustion within the thickness of a blade of a wing-shaped flame providing a luminous emission of violet color within the visible spectrum, at a wavelength below 0.42 micron, from the combustion of natural gases.
BRIEF DESCRIPTION OF THE DRAWING
The present invention is described on the basis of some exemplary embodiments illustrated in the attached drawings, in which:
FIG. 1 shows a longitudinal sectional view of a burner;
FIG. 2 shows a cross-sectional view along the line A--A in FIG. 1;
FIG. 3a and 3b show of possible variations in the slot groups;
FIG. 4 shows a view of a possible arrangement of the slot groups;
FIG. 5 shows a variant of FIG. 4;
FIG. 6 shows a plan view of the upper part of a burner;
FIG. 7 shows a plan view of a variant of the burner in FIG. 6;
FIGS. 8 and 9 show variants of FIG. 2;
FIGS. 10a, 10b, 10c and 10d show views of possible variants of the sub-groups of holes in which the mutual positions of a sub-group of slots and a sub-group of holes is
REFERENCES:
patent: 3829279 (1974-08-01), Qualley et al.
patent: 4156591 (1979-05-01), Anderson
patent: 4915621 (1990-04-01), Schilling et al.
Price Carl D.
Worgas Bruciatori S.r.l.
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