EP0589226B1 - Burner for liquid ot gaseous fuels - Google Patents

Burner for liquid ot gaseous fuels Download PDF

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Publication number
EP0589226B1
EP0589226B1 EP93113542A EP93113542A EP0589226B1 EP 0589226 B1 EP0589226 B1 EP 0589226B1 EP 93113542 A EP93113542 A EP 93113542A EP 93113542 A EP93113542 A EP 93113542A EP 0589226 B1 EP0589226 B1 EP 0589226B1
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EP
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Prior art keywords
baffle plate
air
mixing tube
combustion
nozzles
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EP93113542A
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German (de)
French (fr)
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EP0589226A1 (en
Inventor
Uwe Dr.-Ing. Wiedemann
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Koerting Hannover GmbH
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Koerting Hannover GmbH
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23D—BURNERS
    • F23D11/00—Burners using a direct spraying action of liquid droplets or vaporised liquid into the combustion space
    • F23D11/36—Details, e.g. burner cooling means, noise reduction means
    • F23D11/40—Mixing tubes or chambers; Burner heads
    • F23D11/402—Mixing chambers downstream of the nozzle

Definitions

  • the invention relates to a low-NO x burner for liquid or gaseous fuels, with a mixing tube as a passage for the combustion air and with a baffle plate arranged in the front region of the mixing tube, which is perpendicular to the axis of the mixing tube and is axially displaceable in the mixing tube, wherein the baffle plate is provided with a central opening for introducing part or all of the fuel and a first part of the combustion air (core air) into the combustion chamber and with radial oblique slots for the tangential introduction of a second part of the combustion air (swirl air) into the combustion chamber and a collar has on its outer circumference, between which and the inner wall of the mixing tube, a third part of the combustion air (axial air) can be introduced into the combustion chamber.
  • a baffle plate is provided with a central opening for introducing part or all of the fuel and a first part of the combustion air (core air) into the combustion chamber and with radial oblique slots for the tangential introduction of
  • the baffle plate is arranged within the mixing tube so that the combustion air hits the baffle plate from behind, partly through the central opening, partly through the radial oblique slots and partly through the space between the collar on the outer periphery of the baffle plate and the mixing tube into the combustion chamber reached.
  • the mixing tube tapers inwards, so that the baffle plate is axially displaced within the Mixing tube, the distance between the baffle plate collar and the conically tapered front end of the mixing tube, and thus the amount of air supplied, can be varied.
  • the arrangement of the baffle plate in the combustion air space has the purpose of stabilizing the flame and ensuring good mixing of fuel and air and thus achieving the most complete possible combustion of the fuel with a stable flame shape.
  • This intermixing is brought about on the one hand by the proportion of combustion air introduced tangentially through the radial oblique slots and on the other hand by a backflow which forms behind the baffle plate and through which combustion gases are returned to the flame root.
  • a burner is known in which the baffle plate is firmly installed in a guide tube, in such a way that a fixed, small annular gap remains between these two components.
  • the guide tube forms, together with the baffle plate, the fuel line, etc., a structural unit which is held coaxially and displaceably in the flame tube by means of elastic spacers.
  • a second, variable annular gap is formed between the outside diameter of the guide tube and the inside diameter of the mouth of the flame tube.
  • DE-A-28 09 933 describes another burner whose baffle plate has a central opening, but which only serves to pass the fuel, and is sealed off from the combustion air.
  • the mixing tube of this burner is bent radially inwards in the region of its mouth and then obliquely outwards upstream, as a result of which a hollow cylinder is formed.
  • In the jacket of this hollow cylinder in the vicinity of the mouth of the mixing tube, there are several radial bores distributed over the circumference intended.
  • the upstream end of the hollow cylinder runs out as a diverging end cone.
  • the total air flow flows to the combustion zone via the annular gap, the radial bores in the hollow cylinder and the swirl slots in the baffle plate.
  • the invention has for its object to design a mixing device of the type described above so that the pollutants in the exhaust gas, in particular the NO x content, are significantly reduced.
  • the object is achieved by means of a burner of the type mentioned in that a conically tapering annular body is arranged between the collar of the baffle plate and the inner wall of the mixing tube, which divides the third part of the combustion air into two partial flows, and that in the way of between the annular body and the partial flow of the mixing tube, a plurality of nozzles are arranged in an end face of the mixing tube.
  • the inner partial flow is fed as axial air between the baffle plate collar and the inner surface of the ring body of the primary combustion zone, in addition, part of the remaining combustion air also reaches the primary zone as radial air via the radial annular gap between the end surface of the ring body and the inner surface of the mixing tube end surface.
  • the radial flow accelerated radially in the annular gap constricts the swirl flow formed from core, swirl and axial air, which increases the return of hot, largely burned-out exhaust gases. This causes the fuel to heat up more quickly and the oxygen content in the fuel-rich primary zone to be reduced, thereby reducing the fuel and thermal NO x .
  • the remaining combustion air is fed to the secondary zone as stage air via the nozzles in the face of the mixing tube, axially or slightly inclined inwards. Due to the high axial impulse of the individual jets, exhaust gas is sucked out of the combustion chamber and mixed into the air jet in such a way that air and exhaust gas are largely mixed before entering the secondary zone.
  • the division between the axial and radial air can be adjusted by axially displacing the annular body, as a result of which the inflow angle of the mixture of axial and radial air can be adjusted.
  • a higher proportion of radial air intensifies the constriction and reduces the NO x emission via the stronger internal backflow. It may be appropriate that the annular gap between the ring body and the inner edge of the mixing tube face is inclined forward.
  • nozzles are arranged in the end face of the mixing tube, which extend axially or are inclined slightly inwards, so that the air flowing out of them is directed towards the center line of the mixing device.
  • the arrangement of the ring body makes it possible to pull the end face of the mixing tube inward beyond the diameter of the baffle plate without the inside of the end face being hit by oil droplets in an oil burner.
  • an attachment pipe for targeted exhaust gas recirculation is preferably provided in front of the mixing pipe.
  • a throttle chamber with an adjustable inlet area on the inflow side of the baffle plate in order to reduce the pressure in front of the baffle plate at higher blower pressures.
  • a throttle device between the baffle plate and the sinker body in order to reduce the speed of the axial air at high fan pressures.
  • the drawing shows a mixing tube 1 which tapers slightly conically at the front end 2 and opens into an end face 15 and in which a fuel lance 3 with a fuel nozzle 4 is arranged centrally, for example in the case of liquid fuel.
  • a baffle plate 6 is fastened with struts 5, which is axially displaceable with the fuel lance in the mixing tube 1, and which is provided with a collar 7 on its circumference in a known manner.
  • the baffle plate 6 has in the usual way a central opening 8 as a passage for part or all of the fuel and a first part 9 of the combustion air, which is also referred to as core air. Ignition also takes place in the area of the core air.
  • This swirl air in conjunction with the blockage by the baffle plate, stabilizes the flame immediately in front of the baffle plate by recirculating hot combustion gases.
  • the invention now provides an annular body 13 between the collar 7 of the baffle plate and the inner surface of the mixing tube 1, which divides the third part 12 of the combustion air into two partial flows.
  • One partial flow runs as an axial air 14 between the baffle plate collar 7 and the conically tapering inner surface of the body 13 into the primary combustion chamber, the baffle plate 6 being axially displaceable in order to meter the axial air 14 and to adapt it to the burner's required output.
  • the other partial flow 17 runs outside the ring body 13.
  • the end face of the ring body 13 forms with the inside of the mixing tube end face 15 a radial annular gap 18, through which a part 17a of the air flow is accelerated radially.
  • the remaining combustion air approximately 30 to 70%, preferably 50% of the stoichiometric amount of air, passes in individual jets 17b through the nozzles 16 into the secondary combustion zone.
  • the ring body 13 is axially displaceably mounted in a guide in the mixing tube 1, so that the division between the axial air 14 and the radial air for a specific baffle plate position 17a, and thus the inflow angle, of the total flow 14 and 17a can be set. In extreme cases, the axial or radial air can be completely reduced.
  • the inner edge of the end face 15 is sufficiently far outside with respect to the central opening 8 of the baffle plate, so that e.g. with liquid fuels there is no danger of droplets hitting the inside of the end face.
  • the inner edge of the end face 15 can therefore also be pulled in further than shown.
  • the radial air flow 17a increases the internal recirculation, while the air jets 17b enter the secondary zone at high speed as step air, the exhaust gases sucked in from the combustion chamber being mixed into the air jets before they reach the flame.
  • the two air streams 17a and 17b thus provide for a reduction in the oxygen content in the primary zone and for a large decrease in temperature in the secondary zone, thereby increasing fuel NO x and thermal NO, by increasing the internal backflow in the primary zone and the external backflow of exhaust gas x strongly reduced.
  • a recirculation tube 19 can be provided in a known manner on the outside in front of the mixing tube 1, which reduces the oxygen content of the exhaust gases that are sucked back and increases the momentum exchange, which results in high efficiency because the amount of exhaust gas penetrates the flame early.
  • a throttle chamber 20 can be arranged with which the pressure on the baffle plate is reduced and thus the ignition and flame stability are improved at high blower pressures.
  • the pressure can be made adjustable by changing the entry surface into the chamber.
  • a throttle 21 can be provided on the baffle plate collar 7 in order to reduce the speed of the axial air at high blower pressures.
  • the nozzles 16 do not have to be inclined inwards, but that their axes can also run parallel to the central axis of the mixing tube 1. In addition, it is possible to align only a part of the nozzles parallel to the axis and to arrange the remaining nozzles at an incline.
  • the invention is not limited to oil burners, but can also be used in burners for gaseous fuels.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Pressure-Spray And Ultrasonic-Wave- Spray Burners (AREA)
  • Hydrogen, Water And Hydrids (AREA)

Abstract

Burner with a mixing pipe as passage for the combustion air and a baffle plate arranged in the front region of the mixing pipe, the combustion air being introduced into the combustion space as core air through a central opening in the baffle plate, as twisted air via oblique slots in the baffle plate and as axial air past the baffle plate on the outside. According to the invention, there is provided between the collar (7) of the baffle plate (6) and the inner wall of the mixing pipe (1) an annular body (13) which divides the combustion air portion flowing between baffle plate and mixing pipe into two part flows (14, 17), and a number of nozzles (16) are arranged in an end face (15) of the mixing pipe in the path of the part flow (17) running between the annular body (13) and the mixing pipe. Air jets (17b) pass through the nozzles (16) into the flame at high speed, and a radial air flow (17a) is formed through the gap (18) between the annular body (13) and the end face (15). As a result, a stepped combustion with a substoichiometric primary zone with intensified inner recirculation and a superstoichiometric secondary zone rich in waste gas is achieved and thus the formation of fuel and thermal NOx is reduced considerably. <IMAGE>

Description

Die Erfindung bezieht sich auf einen NOx-armen Brenner für flüssige oder gasförmige Brennstoffe, mit einem Mischrohr als Durchlaß für die Verbrennungsluft und mit einer im vorderen Bereich des Mischrohres angeordneten Stauscheibe, die senkrecht zur Achse des Mischrohres liegt und axial im Mischrohr verschiebbar ist, wobei die Stauscheibe mit einer zentralen Öffnung zur Einführung eines Teils oder des gesamten Brennstoffs und eines ersten Teils der Verbrennungsluft (Kernluft) in den Verbrennungsraum und mit radialen Schrägschlitzen zur tangentialen Einführung eines zweiten Teils der Verbrennungsluft (Dralluft) in den Verbrennungsraum versehen ist sowie einen Kragen an ihrem Außenumfang aufweist, zwischen dem und der Innenwand des Mischrohres ein dritter Teil der Verbrennungsluft (Axialluft) in den Verbrennungsraum einleitbar ist.The invention relates to a low-NO x burner for liquid or gaseous fuels, with a mixing tube as a passage for the combustion air and with a baffle plate arranged in the front region of the mixing tube, which is perpendicular to the axis of the mixing tube and is axially displaceable in the mixing tube, wherein the baffle plate is provided with a central opening for introducing part or all of the fuel and a first part of the combustion air (core air) into the combustion chamber and with radial oblique slots for the tangential introduction of a second part of the combustion air (swirl air) into the combustion chamber and a collar has on its outer circumference, between which and the inner wall of the mixing tube, a third part of the combustion air (axial air) can be introduced into the combustion chamber.

Einen solchen Aufbau weisen heute die meisten Gebläsebrenner auf. Die Stauscheibe ist dabei innerhalb des Mischrohres so angeordnet, daß die Verbrennungsluft von hinten auf die Stauscheibe trifft und dabei teils durch die zentrale Öffnung, teils durch die radialen Schrägschlitze und teils durch den Zwischenraum zwischen dem Kragen am Außenumfang der Stauscheibe und dem Mischrohr in den Verbrennungsraum gelangt. Im Bereich des Kragens der Stauscheibe verjüngt sich das Mischrohr nach innen, so daß durch axiale Verschiebung der Stauscheibe innerhalb des Mischrohres der Abstand zwischen dem Stauscheibenkragen und dem konisch verjüngten vorderen Ende des Mischrohres, und damit die zugeführte Luftmenge, variiert werden kann.Most forced draft burners today have such a structure. The baffle plate is arranged within the mixing tube so that the combustion air hits the baffle plate from behind, partly through the central opening, partly through the radial oblique slots and partly through the space between the collar on the outer periphery of the baffle plate and the mixing tube into the combustion chamber reached. In the region of the collar of the baffle plate, the mixing tube tapers inwards, so that the baffle plate is axially displaced within the Mixing tube, the distance between the baffle plate collar and the conically tapered front end of the mixing tube, and thus the amount of air supplied, can be varied.

Die Anordnung der Stauscheibe im Verbrennungsluftraum hat den Zweck, die Flamme zu stabilisieren und eine gute Durchmischung von Brennstoff und Luft sicherzustellen und damit eine möglichst vollkommene Verbrennung des Brennstoffs bei stabiler Flammenform zu erreichen. Diese Durchmischung wird einerseits durch den tangential durch die radialen Schrägschlitze eingeführten Verbrennungsluftanteil und andererseits durch eine sich hinter der Stauscheibe ausbildende Rückströmung bewirkt, durch die Verbrennungsgase zur Flammenwurzel zurückgeführt werden.The arrangement of the baffle plate in the combustion air space has the purpose of stabilizing the flame and ensuring good mixing of fuel and air and thus achieving the most complete possible combustion of the fuel with a stable flame shape. This intermixing is brought about on the one hand by the proportion of combustion air introduced tangentially through the radial oblique slots and on the other hand by a backflow which forms behind the baffle plate and through which combustion gases are returned to the flame root.

Aus DE-A-37 02 359 ist ein Brenner bekannt, bei dem die Stauscheibe fest in ein Führungsrohr eingebaut ist, und zwar so, daß zwischen diesen beiden Bauteilen ein fixer, kleiner Ringspalt verbleibt. Das Führungsrohr bildet zusammen mit der Stauscheibe, der Brennstoffleitung etc. eine Baueinheit, die über elastische Abstandshalter koaxial und verschiebbar im Flammrohr gehaltert ist. Zwischen dem Außendurchmesser des Führungsrohres und dem Innendurchmesser der Mündung des Flammrohres ist ein zweiter, variabler Ringspalt gebildet. Bei diesem Brenner strömt der Gesamt-Luftstrom der Verbrennungszone über eine zentrale Öffnung in der Stauscheibe, sowie über den fixen und den variablen Ringspalt zu.From DE-A-37 02 359 a burner is known in which the baffle plate is firmly installed in a guide tube, in such a way that a fixed, small annular gap remains between these two components. The guide tube forms, together with the baffle plate, the fuel line, etc., a structural unit which is held coaxially and displaceably in the flame tube by means of elastic spacers. A second, variable annular gap is formed between the outside diameter of the guide tube and the inside diameter of the mouth of the flame tube. With this burner, the total air flow to the combustion zone flows through a central opening in the baffle plate, as well as via the fixed and the variable annular gap.

In DE-A-28 09 933 ist ein weiterer Brenner beschrieben, dessen Stauscheibe zwar eine zentrale Öffnung aufweist, die aber lediglich dem Durchlaß des Brennstoffs dient, und gegen die Verbrennungsluft abgeschottet ist. Das Mischrohr dieses Brenners ist im Bereich seiner Mündung radial einwärts und dann stromauf schräg nach außen gebogen, wodurch ein Hohlzylinder ausgebildet ist. Im Mantel dieses Hohlzylinders sind in Nähe der Mündung des Mischrohres mehrere auf den Umfang verteilt angeordnete Radialbohrungen vorgesehen. Das stromauf liegende Ende des Hohlzylinders läuft als divergierender Endkegel aus. Zwischen diesem Endkegel und dem Kragen der Stauscheibe besteht ein Ringspalt, der durch Verschieben der Stauscheibe geöffnet oder geschlossen werden kann. Der Gesamt-Luftstrom fließt der Verbrennungszone über den Ringspalt, die Radialbohrungen im Hohlzylinder sowie die Drallschlitze in der Stauscheibe zu.DE-A-28 09 933 describes another burner whose baffle plate has a central opening, but which only serves to pass the fuel, and is sealed off from the combustion air. The mixing tube of this burner is bent radially inwards in the region of its mouth and then obliquely outwards upstream, as a result of which a hollow cylinder is formed. In the jacket of this hollow cylinder, in the vicinity of the mouth of the mixing tube, there are several radial bores distributed over the circumference intended. The upstream end of the hollow cylinder runs out as a diverging end cone. There is an annular gap between this end cone and the collar of the baffle plate, which can be opened or closed by moving the baffle plate. The total air flow flows to the combustion zone via the annular gap, the radial bores in the hollow cylinder and the swirl slots in the baffle plate.

Die beschriebenen Mischeinrichtungen haben sich in der Praxis bewährt, jedoch hat sich gezeigt, daß mit der herkömmlichen Bauart der Stauscheibe und des Mischrohres die immer schärfer werdenden Forderungen hinsichtlich der Schadstoffbegrenzung der Abgase kaum noch erfüllt werden können.The mixing devices described have proven themselves in practice, but it has been shown that with the conventional design of the baffle plate and the mixing tube, the increasingly stringent requirements with regard to the limitation of pollutants in the exhaust gases can hardly be met.

Der Erfindung liegt die Aufgabe zugrunde, eine Mischeinrichtung der eingangs beschriebenen Art so auszubilden, daß die Schadstoffe im Abgas, insbesondere der NOx-Gehalt, wesentlich vermindert werden.The invention has for its object to design a mixing device of the type described above so that the pollutants in the exhaust gas, in particular the NO x content, are significantly reduced.

Die gestellte Aufgabe wird mittels eines Brenners der eingangs genannten Art dadurch gelöst, daß zwischen dem Kragen der Stauscheibe und der Innenwand des Mischrohres ein sich konisch verjüngender Ringkörper angeordnet ist, der den dritten Teil der Verbrennungsluft in zwei Teilströme aufteilt, und daß im Wege des zwischen dem Ringkörper und dem Mischrohr verlaufenden Teilstroms mehrere Düsen in einer Stirnfläche des Mischrohres angeordnet sind.The object is achieved by means of a burner of the type mentioned in that a conically tapering annular body is arranged between the collar of the baffle plate and the inner wall of the mixing tube, which divides the third part of the combustion air into two partial flows, and that in the way of between the annular body and the partial flow of the mixing tube, a plurality of nozzles are arranged in an end face of the mixing tube.

Der innere Teilstrom wird als Axialluft zwischen dem Stauscheibenkragen und der Innenfläche des Ringkörpers der primären Verbrennungszone zugeführt, zusätzlich gelangt ein Teil der verbleibenden Verbrennungsluft über den radialen Ringspalt zwischen der Stirnfläche des Ringkörpers und der Innenfläche der Mischrohr-Stirnfläche als Radialluft ebenfalls in die Primärzone. Durch die in dem Ringspalt radial beschleunigte Radialluft wird die aus Kern-, Drall- und Axialluft gebildete Drallströmung eingeschnürt, wodurch die Rückführung heißer, weitgehend ausgebrannter Abgase verstärkt wird. Dies bewirkt eine schnellere Aufheizung des Brennstoffs und eine Verringerung des Sauerstoffgehalts in der brennstoffreichen Primärzone und dadurch eine Reduzierung von Brennstoff- und thermischem NOx.The inner partial flow is fed as axial air between the baffle plate collar and the inner surface of the ring body of the primary combustion zone, in addition, part of the remaining combustion air also reaches the primary zone as radial air via the radial annular gap between the end surface of the ring body and the inner surface of the mixing tube end surface. The radial flow accelerated radially in the annular gap constricts the swirl flow formed from core, swirl and axial air, which increases the return of hot, largely burned-out exhaust gases. This causes the fuel to heat up more quickly and the oxygen content in the fuel-rich primary zone to be reduced, thereby reducing the fuel and thermal NO x .

Die restliche Verbrennungsluft wird als Stufenluft über die Düsen in der Mischrohr-Stirnfläche axial oder leicht nach innen geneigt der Sekundärzone zugeführt. Durch den hohen Axialimpuls der Einzelstrahlen wird Abgas aus dem Feuerraum angesaugt und in den Luftstrahl so eingemischt, daß Luft und Abgas bereits vor Eindringen in die Sekundärzone weitgehend vermischt sind.The remaining combustion air is fed to the secondary zone as stage air via the nozzles in the face of the mixing tube, axially or slightly inclined inwards. Due to the high axial impulse of the individual jets, exhaust gas is sucked out of the combustion chamber and mixed into the air jet in such a way that air and exhaust gas are largely mixed before entering the secondary zone.

Durch axiale Verschiebung des Ringkörpers kann die Aufteilung zwischen Axial- und Radialluft eingestellt werden, wodurch der Zuströmwinkel des Gemisches aus Axial- und Radialluft einstellbar ist. Ein höherer Radialluftanteil verstärkt die Einschnürung und senkt über die stärkere innere Rückströmung die NOx-Emission. Dabei kann es zweckmäßig sein, daß der Ringspalt zwischen dem Ringkörper und dem Innenrand der Mischrohrstirnfläche schräg nach vorn geneigt ist.The division between the axial and radial air can be adjusted by axially displacing the annular body, as a result of which the inflow angle of the mixture of axial and radial air can be adjusted. A higher proportion of radial air intensifies the constriction and reduces the NO x emission via the stronger internal backflow. It may be appropriate that the annular gap between the ring body and the inner edge of the mixing tube face is inclined forward.

Vorzugsweise sind in der Mischrohr-Stirnfläche etwa fünf bis zehn Düsen angeordnet, die axial verlaufen oder leicht einwärts geneigt sind, so daß die aus ihnen ausströmende Luft in Richtung auf die Mittellinie der Mischeinrichtung gelenkt wird.Preferably, about five to ten nozzles are arranged in the end face of the mixing tube, which extend axially or are inclined slightly inwards, so that the air flowing out of them is directed towards the center line of the mixing device.

Durch die Anordnung des Ringkörpers ist es möglich, die Stirnfläche des Mischrohrs über den Durchmesser der Stauscheibe hinaus einwärts zu ziehen, ohne daß die Innenseite der Stirnfläche bei einem Ölbrenner von Öltröpfchen getroffen wird.The arrangement of the ring body makes it possible to pull the end face of the mixing tube inward beyond the diameter of the baffle plate without the inside of the end face being hit by oil droplets in an oil burner.

Vorzugsweise ist in an sich bekannter Weise vor dem Mischrohr ein Vorsatzrohr für eine gezielte Abgasrückführung vorgesehen.In a manner known per se, an attachment pipe for targeted exhaust gas recirculation is preferably provided in front of the mixing pipe.

Ferner ist es zweckmäßig, auf der Anströmseite der Stauscheibe eine Drosselkammer mit einstellbarer Eintrittsfläche vorzusehen, um bei höheren Gebläsedrücken den Druck vor der Stauscheibe zu reduzieren. Außerdem ist es von Vorteil, zwischen der Stauscheibe und dem Rinkörper eine Drosseleinrichtung vorzusehen, um bei hohen Gebläsedrücken die Geschwindigkeit der Axialluft zu reduzieren.Furthermore, it is expedient to provide a throttle chamber with an adjustable inlet area on the inflow side of the baffle plate in order to reduce the pressure in front of the baffle plate at higher blower pressures. In addition, it is advantageous to provide a throttle device between the baffle plate and the sinker body in order to reduce the speed of the axial air at high fan pressures.

Die Erfindung wird nachfolgend anhand eines in der Zeichnung dargestellten Ausführungsbeispiels eines Ölbrenners näher erläutert.The invention is explained in more detail below using an exemplary embodiment of an oil burner shown in the drawing.

Die Zeichnung zeigt ein Mischrohr 1, das sich am vorderen Ende 2 leicht konisch verjüngt und in eine Stirnfläche 15 mündet, und in dem zentral, z.B. bei flüssigem Brennstoff, eine Brennstofflanze 3 mit einer Brennstoffdüse 4 angeordnet ist. An der Brennstoff-lanze 3 ist mit Streben 5 eine Stauscheibe 6 befestigt, die mit der Brennstofflanze im Mischrohr 1 axial verschiebbar ist, und die an ihrem Umfang in bekannter Weise mit einem Kragen 7 versehen ist. Die Stauscheibe 6 besitzt in üblicher Weise eine zentrale Öffnung 8 als Durchlaß für einen Teil oder den gesamten Brennstoff und einen ersten Teil 9 der Verbrennungsluft, die auch als Kernluft bezeichnet wird. Im Bereich der Kernluft erfolgt z.B. auch die Zündung. Ferner sind in üblicher Weise zwischen der zentralen Öffnung 8 und dem Außenrand der Scheibe radiale Schlitze vorgesehen, die durch flügelartige Vorsprünge 10 gebildet werden, und die durch einen Drückvorgang in der Scheibe 6 angebracht werden. Dadurch wird ein zweiter Teil des Verbren-nungsluftstroms in tangentialer Richtung als Dralluft 11 in den Verbrennungsraum geleitet.The drawing shows a mixing tube 1 which tapers slightly conically at the front end 2 and opens into an end face 15 and in which a fuel lance 3 with a fuel nozzle 4 is arranged centrally, for example in the case of liquid fuel. On the fuel lance 3, a baffle plate 6 is fastened with struts 5, which is axially displaceable with the fuel lance in the mixing tube 1, and which is provided with a collar 7 on its circumference in a known manner. The baffle plate 6 has in the usual way a central opening 8 as a passage for part or all of the fuel and a first part 9 of the combustion air, which is also referred to as core air. Ignition also takes place in the area of the core air. Furthermore, between the central opening 8 and the outer edge of the Disc radial slots are provided, which are formed by wing-like projections 10, and which are made in the disc 6 by a pressing process. As a result, a second part of the combustion air flow is directed into the combustion chamber in the tangential direction as swirl air 11.

Diese Dralluft sorgt in Verbindung mit der Versperrung durch die Stauscheibe für die Stabilisierung der Flamme unmittelbar vor der Stauscheibe durch Rückführung heißer Verbrennungsgase.This swirl air, in conjunction with the blockage by the baffle plate, stabilizes the flame immediately in front of the baffle plate by recirculating hot combustion gases.

Die Erfindung sieht nun zwischen dem Kragen 7 der Stauscheibe und der Innenfläche des Mischrohres 1 einen Ringkörper 13 vor, der den dritten Teil 12 der Verbrennungsluft in zwei Teilströme aufteilt. Der eine Teilstrom verläuft als Axialluft 14 zwischen Stauscheibenkragen 7 und der sich konisch verjüngenden Innenfläche des Körpers 13 in den primären Verbrennungsraum, wobei die Stauscheibe 6 axial verschiebbar ist, um die Axialluft 14 zu dosieren und an die jeweils geforderte Leistung des Brenners anzupassen. Der andere Teilstrom 17 läuft außen am Ringkörper 13 vorbei.The invention now provides an annular body 13 between the collar 7 of the baffle plate and the inner surface of the mixing tube 1, which divides the third part 12 of the combustion air into two partial flows. One partial flow runs as an axial air 14 between the baffle plate collar 7 and the conically tapering inner surface of the body 13 into the primary combustion chamber, the baffle plate 6 being axially displaceable in order to meter the axial air 14 and to adapt it to the burner's required output. The other partial flow 17 runs outside the ring body 13.

Die Stirnseite des Ringkörpers 13 bildet mit der Innenseite der Mischrohr-Stirnfläche 15 einen radialen Ringspalt 18, über den ein Teil 17a des Luftstroms radial beschleunigt wird.The end face of the ring body 13 forms with the inside of the mixing tube end face 15 a radial annular gap 18, through which a part 17a of the air flow is accelerated radially.

Die restliche Verbrennungsluft, etwa 30 bis 70 %, vorzugsweise 50 % der stöchiometrischen Luftmenge, tritt in Einzelstrahlen 17b durch die Düsen 16 in die sekundäre Verbrennungszone.The remaining combustion air, approximately 30 to 70%, preferably 50% of the stoichiometric amount of air, passes in individual jets 17b through the nozzles 16 into the secondary combustion zone.

Der Ringkörper 13 ist axial verschiebbar in einer Führung im Mischrohr 1 gelagert, so daß für eine bestimmte Stauscheibenposition die Aufteilung zwischen Axialluft 14 und Radialluft 17a, und damit der Zuströmwinkel, des Gesamtstromes 14 und 17a eingestellt werden kan. Im Extrem kann die Axial- bzw. die Radialluft vollständig reduziert werden.The ring body 13 is axially displaceably mounted in a guide in the mixing tube 1, so that the division between the axial air 14 and the radial air for a specific baffle plate position 17a, and thus the inflow angle, of the total flow 14 and 17a can be set. In extreme cases, the axial or radial air can be completely reduced.

Die Innenkante der Stirnfläche 15 liegt ausreichend weit außen in bezug auf die zentrale Öffnung 8 der Stauscheibe, so daß z.B. bei flüssigen Brennstoffen keine Gefahr besteht, daß Tröpfchen auf die Innenseite der Stirnfläche aufprallen.The inner edge of the end face 15 is sufficiently far outside with respect to the central opening 8 of the baffle plate, so that e.g. with liquid fuels there is no danger of droplets hitting the inside of the end face.

Die Innenkante der Stirnfläche 15 kann daher auch noch weiter als dargestellt nach innen gezogen werden.The inner edge of the end face 15 can therefore also be pulled in further than shown.

Ferner ist es möglich, zur Abschwächung der Einschnürung den radialen Ringspalt durch Neigung der Stirnflächen von Ringkörper und Mischrohr schräg auszugestalten.It is also possible, in order to weaken the constriction, to design the radial annular gap obliquely by inclining the end faces of the annular body and the mixing tube.

Wie zuvor erwähnt, wird durch den radialen Luftstrom 17a die innere Rezirkulation verstärkt, während die Luftstrahlen 17b als Stufenluft mit hoher Geschwindigkeit in die Sekundärzone gelangen, wobei die Einmischung der aus dem Feuerraum angesaugten Abgase in die Luftstrahlen erfolgt, bevor diese die Flamme erreichen. Die beiden Luftströme 17a und 17b sorgen somit durch Vergrößerung der inneren Rückströmung in der Primärzone und der äußeren Rückströmung von Abgas in die Sekundärzone für eine Reduzierung des Sauerstoffgehalts in der Primärzone und für eine starke Temperaturabsenkung in der Sekundärzone, wodurch Brennstoff-NOx und thermisches NOx starkt reduziert werden.As previously mentioned, the radial air flow 17a increases the internal recirculation, while the air jets 17b enter the secondary zone at high speed as step air, the exhaust gases sucked in from the combustion chamber being mixed into the air jets before they reach the flame. The two air streams 17a and 17b thus provide for a reduction in the oxygen content in the primary zone and for a large decrease in temperature in the secondary zone, thereby increasing fuel NO x and thermal NO, by increasing the internal backflow in the primary zone and the external backflow of exhaust gas x strongly reduced.

Zur Verbesserung der äußeren Abgasrückführung kann in bekannter Weise außen vor dem Mischrohr 1 ein Rezirkulationsrohr 19 vorgesehen werden, das den Sauerstoffgehalt der zurückgesaugten Abgase reduziert und den Impulsaustausch erhöht, wobei sich eine hohe Effizienz ergibt, weil die Abgasmenge früh in die Flamme eindringt. Ferner kann in Strömungsrichtung vor der Stauscheibe eine Drosselkammer 20 angeordnet werden, mit der der Druck an der Stauscheibe reduziert und damit bei hohen Gebläsedrücken die Zündung sowie die Flammenstabilität verbessert werden. Dabei kann der Druck durch Änderung der Eintrittsfläche in die Kammer einstellbar gemacht werden.In order to improve the external exhaust gas recirculation, a recirculation tube 19 can be provided in a known manner on the outside in front of the mixing tube 1, which reduces the oxygen content of the exhaust gases that are sucked back and increases the momentum exchange, which results in high efficiency because the amount of exhaust gas penetrates the flame early. Furthermore, in front of the baffle plate in the direction of flow a throttle chamber 20 can be arranged with which the pressure on the baffle plate is reduced and thus the ignition and flame stability are improved at high blower pressures. The pressure can be made adjustable by changing the entry surface into the chamber.

Ferner kann auf dem Stauscheibenkragen 7 eine Drossel 21 vorgesehen werden, um die Geschwindigkeit der Axialluft bei hohen Gebläsedrücken zu reduzieren.Furthermore, a throttle 21 can be provided on the baffle plate collar 7 in order to reduce the speed of the axial air at high blower pressures.

Schließlich sei erwähnt, daß die Düsen 16 nicht einwärts geneigt sein müssen, sondern daß ihre Achsen auch parallel zur Mittelachse des Mischrohrs 1 verlaufen können. Darüber hinaus ist es möglich, nur einen Teil der Düsen achsparallel auszurichten und die restlichen Düsen geneigt anzuordnen.Finally, it should be mentioned that the nozzles 16 do not have to be inclined inwards, but that their axes can also run parallel to the central axis of the mixing tube 1. In addition, it is possible to align only a part of the nozzles parallel to the axis and to arrange the remaining nozzles at an incline.

Die Erfindung ist nicht auf Ölbrenner beschränkt, sondern auch bei Brennern für gasförmige Brennstoffe anwendbar.The invention is not limited to oil burners, but can also be used in burners for gaseous fuels.

Claims (9)

  1. Burner for liquid or gaseous fuels with a mixing tube (1) as a passage for the combustion air and with a baffle plate (6) which is arranged in the forward area of the mixing tube (1), lies perpendicular to the axis of the mixing tube (1) and can be displaced axially in the mixing tube (1), the baffle plate (6) being provided with a central opening for the introduction of part or all of the fuel and a first part of the combustion air (core air) (9) into the combustion space and with radial oblique slots (10) for the tangential introduction of a second part of the combustion air (swirl air) (11) into the combustion space, and having a collar (7) at its outer circumference, between which and the inner wall of the mixing tube (1) a third part of the combustion air (axial air) can be introduced into the combustion space, a conically tapering annular body (13) which divides the third part of the combustion air (12) into two part-streams (14, 17) being arranged between the collar (7) of the baffle plate (6) and the inner wall of the mixing tube (1), and a plurality of nozzles (16) being arranged in an end face (15) of the mixing tube (1) in the path of the part-stream (17) running between the annular body (13) and the mixing tube (1).
  2. Burner according to Claim 1, characterized in that the annular body (13) is mounted in axially displaceable fashion in the mixing tube (1).
  3. Burner according to Claim 1 or 2, characterized in that the annular gap (18) between the annular body (13) and the inner edge of the mixing-tube end face (15) is inclined obliquely forwards.
  4. Burner according to one of Claims 1 to 3, characterized in that the end face (15) of the mixing tube contains about 5 to 10 nozzles (16) and the nozzles are dimensioned in such a way that 30 to 70%, preferably 50%, of the stoichiometric combustion air flows through the nozzles.
  5. Burner according to Claim 4, characterized in that the nozzles (16) extend axially or are inclined slightly inwards at the same angle.
  6. Burner according to one of the preceding claims, characterized in that the end face (15) of the mixing tube (1) is drawn inwards beyond the diameter of the baffle plate.
  7. Burner according to one of the preceding claims, characterized in that a tubular attachment (19) for exhaust-gas recirculation in a specifically intended manner is provided on the outside in front of the mixing tube (1) in a manner known per se.
  8. Burner according to one of the preceding claims, characterized in that a restriction chamber (20) with an adjustable inlet area is provided on the inlet side of the baffle plate (6, 7).
  9. Burner according to one of the preceding claims, characterized in that a restrictor device (21) is provided between the baffle plate (6, 7) and the annular body (15) in order to reduce the speed of the axial air (14) at high fan pressures.
EP93113542A 1992-09-23 1993-08-25 Burner for liquid ot gaseous fuels Expired - Lifetime EP0589226B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE4231788A DE4231788A1 (en) 1992-09-23 1992-09-23 Burners for liquid or gaseous fuels
DE4231788 1992-09-23

Publications (2)

Publication Number Publication Date
EP0589226A1 EP0589226A1 (en) 1994-03-30
EP0589226B1 true EP0589226B1 (en) 1997-03-05

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EP93113542A Expired - Lifetime EP0589226B1 (en) 1992-09-23 1993-08-25 Burner for liquid ot gaseous fuels

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EP (1) EP0589226B1 (en)
AT (1) ATE149661T1 (en)
DE (2) DE4231788A1 (en)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AT400259B (en) * 1993-11-29 1995-11-27 Schwarz A & Co MIXING DEVICE FOR OIL OR GAS BURNERS
DE19509854C2 (en) * 1994-09-28 2001-01-04 Abig Werke Carry Gross Gmbh Heating device for burning supplied fuel
EP0754908B2 (en) † 1995-07-20 2001-04-18 DVGW Deutscher Verein des Gas- und Wasserfaches -Technisch-wissenschaftliche Vereinigung- Method and apparatus for suspressing flame and pressure vibrations in a furnace
WO1997040315A1 (en) 1996-04-20 1997-10-30 Joh. Vaillant Gmbh U. Co. COMBUSTION DEVICE AND METHOD FOR OPERATING A COMBUSTION DEVICE FOR LOW-NOx AND LOW-CO COMBUSTION
DE29912362U1 (en) * 1999-07-15 2001-01-11 Viessmann Werke Kg Blue burner for boilers

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2809933A1 (en) * 1978-03-08 1979-09-20 Hermann Dipl Ing Kopp Burner for liq. or gaseous fuel - has cup shielding primary flame from radially inwards flowing air and contg. interchangeable nozzles
CH670297A5 (en) * 1986-02-13 1989-05-31 Schilling Siegfried W

Also Published As

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DE59305583D1 (en) 1997-04-10
EP0589226A1 (en) 1994-03-30
ATE149661T1 (en) 1997-03-15
DE4231788A1 (en) 1994-03-24

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