Combustion – Burner having electrical heater or igniter – Spark electrode in front of or adjacent fuel discharger
Patent
1994-01-18
1995-07-18
Dority, Carroll B.
Combustion
Burner having electrical heater or igniter
Spark electrode in front of or adjacent fuel discharger
431351, F23Q 300
Patent
active
054336015
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a burner for generating hot gas comprising a burner pipe, a nozzle arranged in the burner pipe and having an outlet in its front face, a fuel jet exiting through the outlet, a shield arranged near the nozzle for subdividing the burner pipe into a precombustion chamber located upstream and accommodating the nozzle and a combustion chamber located downstream, a central passage arranged in the shield for the fuel jet exiting from the outlet and a plurality of openings surrounding the passage in the shield, combustion air passing through the openings from the precombustion chamber into the combustion chamber.
Burners of this type are known, for example, from EP-A-0 175 875.
The disadvantage of these burners is in the fact that a heat contact exists between the nozzle and the front face of the nozzle so that the nozzle is warmed up by the hot shield and, in particular, after the burner has been switched off, the oil cracks outside the nozzle or also in the interior of the nozzle and forms clogging soot deposits and/or oil carbon deposits on the nozzle ducts or on the outlet of the nozzle so that the burner becomes inoperable.
Thus, the object of the invention is to improve a burner of the generic type such that deposits are no longer formed therein.
This object is accomplished in accordance with the invention, in a burner of the type described at the outset, in that an air gap is provided between the shield and the nozzle for combustion air to pass through the air gap from the precombustion chamber through the passage and into the combustion chamber, and that a rim of the passage is provided with a flow disruption edge for the combustion air flowing through the air gap.
By means of the solution according to the invention, on the one hand, a thermal contact is eliminated between the heated shield and the nozzle, in particular, the front face of the nozzle and, in addition, it is ensured by the flow disruption edge that the air flowing through the passage frees the air gap, on the one hand, and the passage itself, on the other hand, from adhering deposits.
It is particularly favourable when the passage is provided with wall surfaces extending conically in the direction of the combustion chamber, since such a design of the wall surfaces prevents an interference of the fuel jet, particularly, of the spray cone formed by the fuel jet. With respect to the position of the flow disruption edge, no
further details have been given as yet. In fact, it has proven to be particularly advantageous for the flow disruption edge to be located on the side of the conically extending wall surfaces facing the front face of the nozzle, so that the flow disruption edge represents the narrowest point of the opening.
Particularly expedient conditions result when the flow disruption edge lies in a plane which extends vertically to an axis of the nozzle.
In addition to this, the air gap and the effect of the flow disruption edge can be optimally designed when an annular surface adjoins the flow disruption edge on the upstream side of the shield in radial direction to the passage, i.e. in particular, to the axis of the nozzle.
It is particularly advantageous when the annular surface is plane and extends essentially at right angles to axis of the nozzle.
This is realized in a particularly easy, constructive manner when the plane annular surface lies essentially in a plane which is defined by the upstream surface of the shield.
The air gap is realized in a particularly easy manner in one of the embodiments described above, when a front side of the front face of the nozzle is arranged upstream at a distance from the flow disruption edge in axial direction of the nozzle. In this case, it is ensured that even a slight leakage of oil from the front face of the nozzle will not lead to a conglutination in the area of the flow disruption edge.
Moreover, it is a further advantage when the front face of the nozzle is arranged upstream at a distance from the annular surface in axial direction to the nozzle, so that the air gap
REFERENCES:
patent: 3720496 (1973-03-01), Briggs
patent: 4171199 (1979-10-01), Henriques
patent: 4427367 (1984-01-01), Yagisawa
patent: 4547147 (1985-10-01), Suzuki et al.
patent: 4629414 (1986-12-01), Buschulte et al.
Adis Erich
Bader Manfred
Buschulte Winfried
Deutsche Forschungsanstalt fuer Luft - und Raumfahrt e.V.
Dority Carroll B.
Lipsitz Barry R.
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