EP0809070B1 - Burner with exhaust gas recirculation - Google Patents

Burner with exhaust gas recirculation Download PDF

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Publication number
EP0809070B1
EP0809070B1 EP96107956A EP96107956A EP0809070B1 EP 0809070 B1 EP0809070 B1 EP 0809070B1 EP 96107956 A EP96107956 A EP 96107956A EP 96107956 A EP96107956 A EP 96107956A EP 0809070 B1 EP0809070 B1 EP 0809070B1
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EP
European Patent Office
Prior art keywords
exhaust gas
gas recirculation
mixing duct
burner
burner according
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EP96107956A
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German (de)
French (fr)
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EP0809070A1 (en
Inventor
Jakob Keller
Bruno Zumstein
Ulrich Leemann
Philipp Hanimann
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Oertli Technique Thermique
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Oertli Technique Thermique
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Priority to AT96107956T priority Critical patent/ATE204972T1/en
Priority to EP96107956A priority patent/EP0809070B1/en
Priority to DE59607583T priority patent/DE59607583D1/en
Publication of EP0809070A1 publication Critical patent/EP0809070A1/en
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
    • F23C9/00—Combustion apparatus characterised by arrangements for returning combustion products or flue gases to the combustion chamber
    • F23C9/006—Combustion apparatus characterised by arrangements for returning combustion products or flue gases to the combustion chamber the recirculation taking place in the combustion chamber
    • 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
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23D—BURNERS
    • F23D17/00—Burners for combustion conjointly or alternatively of gaseous or liquid or pulverulent fuel
    • F23D17/002—Burners for combustion conjointly or alternatively of gaseous or liquid or pulverulent fuel gaseous or liquid fuel
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
    • F23C2202/00—Fluegas recirculation
    • F23C2202/30—Premixing fluegas with combustion air

Definitions

  • the invention relates to a burner with exhaust gas recirculation according to Preamble of claim 1.
  • EP-A-0 430 011 and EP-491 079 are burners known in which exhaust gas into the primary combustion zone by means of air nozzles is returned. In these cases, the mixing of fresh air and Exhaust and primary combustion take place in the same area. It is also over EP-A-0 394 800 a burner is known which consists of partial cone bodies there are tangential combustion air inlet channels, in which air and recirculated exhaust gas mixed before the actual combustion process become. After mixing incoming air with recirculated exhaust gas finds a premix of liquid or in a conical cavity gaseous fuel with the previously generated exhaust gas-air mixture instead. A A sufficiently high temperature of the exhaust gas / air mixture also enables Pre-evaporation of the liquid fuel. The latter property is for the blue color of the flame when the burner is operating with liquid fuel responsible.
  • a furnace is also described also has a device for recycling exhaust gases.
  • nozzles At the Inside the burner tube are nozzles to accelerate the Combustion air or formation of a low pressure behind the said nozzles intended.
  • In the wall of the burner tube there are openings for Injection of combustion products in the low pressure range and one Baffle plate is provided for swirling the primary air.
  • the gas mixture had a swirl around the burner axis To give.
  • the invention is based on the object constructively a burner of the type mentioned at the beginning simplify and expand to pollutant emissions and the need for external energy for each company minimize this both when operating with liquid as well as with gaseous fuels. According to the invention this is due to the features listed in claim 1 reached.
  • Burners are a major advantage of the invention to see that a particularly intimate mixture of exhaust gas and air even before the fuel injection takes place. It will also be an excellent one Pre-evaporation and premixing of the fuel achieved.
  • the construction of the present invention significantly simpler than, for example, that from EP-A-0 394,800 known.
  • Another advantage of the invention lies in the good efficiency of the annular jet pump, which exhaust gases are entrained by the fresh air flow. Man can improve this efficiency even more by using the Fresh air entering the mixing duct in a number of separate Splits inlet openings. Thanks to its high Jet pump efficiency and its low back pressure after the jet pump can the burner proposed here operated with a conventional single-stage blower become. In addition, if necessary, the otherwise at Exhaust gas recirculation burners do not have the usual start-up measures become.
  • Another advantage of the invention lies in the possibility of special flame stabilization. If the outer shell closes after the narrowing a suitably dimensioned diffuser, can the flame front in the one generated by the jet pump Do not migrate the vortex flow back to the fuel injection. This will not only be the desired premix and pre-evaporation achieved, but it also succeeds in that Fuel injection before sooting and overheating protect. This property contributes to the susceptibility to failure to reduce the burner.
  • Possible exemplary embodiments are in the figures 1, 2, 3 and 4 are shown schematically. Like the figures 1, 3 and 4 clarify, there is the burner body from an essentially rotationally symmetrical outer shell 1 and an inner shell arranged concentrically to it 2.
  • the outer shell 1 has a striking narrowing 3 and a diffuser part 4.
  • a mixing channel 5 is of a part 6 of the outer shell 1 and a part 7 of the Inner shell 2 limited, the course of the shell parts 6 and 7 is chosen so that the cross-sectional area the jet pump mixing section 5 via a in the main flow direction (i.e. parallel to the burner axis) Length of at least two times the radial gap width of the Mixing section remains largely constant. It starts the mixing channel 5 immediately after the merger of Air and exhaust gas.
  • the mixing channel 5 preferably cylindrical.
  • a fuel nozzle 8 ensures the supply of liquid fuel 9, a spray cone 11 through a central atomizing bore 10 is generated.
  • Distributor ring 13 fed gaseous fuel 14.
  • the gaseous fuel passes from the distributor ring 13 14 through a regular arrangement of gas injection holes 15, which preferably radially outwards are directed to the entrance of the jet pump mixing section 5.
  • burner configurations can be made For reasons of space, an axial gas injection (not shown) to be favoured.
  • the fresh air 16 passes through a annular arrangement of air holes 17 in the mixing room 5 a, the axes of the air holes 17 in the case a cylindrical mixing chamber 5 preferably skewed should lie to burner axis A.
  • the air holes chosen in case of a non-cylindrical mixing room 5 would be the alignment the air holes chosen so that their axes with a slight adjustment in the circumferential direction and parallel run to the middle surface of the mixing chamber.
  • a easy adjustment of the axes of the air holes 17 in tangential direction creates a vortex flow at which the flow around the inner shell 2 and Stabilization of the flame 18 guaranteed.
  • Exhaust gas is in the Case of the embodiment shown in Fig. 1 through an annular and regular arrangement of exhaust gas inlet openings 19 sucked into the mixing chamber 5.
  • Guide vanes 20 issue the incoming exhaust gas flow 21 a twist, which together with that of the oblique oriented air holes 17 caused air swirl a swirl of the exhaust gas-air mixture in and after the Mixing section 5 generated.
  • it can be either air swirl or exhaust gas swirl to be dispensed with.
  • the ideal exhaust gas recirculation rate is about 40% up to 70%, based on the fresh air mass flow.
  • the exhaust gas recirculation rate is chosen so that the adiabatic combustion temperature in the flame zone 18 at about 1350 Degrees Celsius. This can reduce both the NOx emissions as well as the CO and UHC emissions kept low become.
  • the jet pump efficiency must be sufficiently high.
  • the recirculated exhaust gas 21 should the highest possible axial speed component be torn into the mixing section 5.
  • FIG. 3 shows an exemplary embodiment, its feeding geometry is special enables high jet pump efficiency.
  • the narrowing 3 of the outer shell should be relative be small so that the back pressure that the Jet pump must overcome, kept as low as possible can be.
  • the returned occurs Exhaust gas 21 swirled into the mixing channel 5, and the Twisting of the gas mixture is caused either by the Fresh air flow or through (not shown) guide vanes generated in the mixing channel.
  • the cross-sectional area of all air holes 17 should preferably be about 10% to 20% of the Cross-sectional area of the mixing room 5. All burner parts, which is on the right side of the boiler wall 22 and thus located inside the boiler are natural exposed to high thermal stress.

Abstract

The recirculated exhaust gases are mixed with the fresh air (16) in a mixing channel (5) formed as a ring-shaped jet pump with a device for causing the gas mixture to twist round the burner axis as it moves in a main flow direction parallel to the burner axis. The mixing channel is defined by two conical shells with the inner shell ending in the main flow direction in front of a restriction (3) in the outer shell. The outer shell widens out after the restriction to a diffusor. Several openings are provided for the fresh air to enter the mixing channel in order to form several individual separate suction jet pumps to recirculate the exhaust gases.

Description

Technisches GebietTechnical field

Die Erfindung betrifft einen Brenner mit Abgasrückführung gemäss Oberbegriff des Anspruchs 1.The invention relates to a burner with exhaust gas recirculation according to Preamble of claim 1.

Stand der TechnikState of the art

Aus den Schriften EP-A-0 430 011 und EP-491 079 sind Brenner bekannt, in welchen mittels Luftdüsen Abgas in die primäre Verbrennungszone zurückgeführt wird. In diesen Fällen finden die Vermischung von Frischluft und Abgas und die Primärverbrennung im gleichen Bereich statt. Ausserdem ist aus EP-A-0 394 800 ein Brenner bekannt geworden, der aus Teilkegelkörpern mit tangentialen Verbrennungslufteintrittskanälen besteht, in welchen Luft und rückgeführtes Abgas vor dem eigentlichen Verbrennungsprozess vermischt werden. Nach der Vermischung von eintretender Luft mit rückgeführtem Abgas findet in einem kegeligen Hohlraum eine Vormischung von flüssigem oder gasförmigem Brennstoff mit dem zuvor erzeugten Abgas-Luftgemisch statt. Eine ausreichend hohe Temperatur des Abgas-Luftgemisches ermöglicht zudem eine Vorverdampfung des flüssigen Brennstoffes. Die letztgenannte Eigenschaft ist für die blaue Farbe der Flamme im Betrieb des Brenners mit flüssigem Brennstoff verantwortlich.From the documents EP-A-0 430 011 and EP-491 079 are burners known in which exhaust gas into the primary combustion zone by means of air nozzles is returned. In these cases, the mixing of fresh air and Exhaust and primary combustion take place in the same area. It is also over EP-A-0 394 800 a burner is known which consists of partial cone bodies there are tangential combustion air inlet channels, in which air and recirculated exhaust gas mixed before the actual combustion process become. After mixing incoming air with recirculated exhaust gas finds a premix of liquid or in a conical cavity gaseous fuel with the previously generated exhaust gas-air mixture instead. A A sufficiently high temperature of the exhaust gas / air mixture also enables Pre-evaporation of the liquid fuel. The latter property is for the blue color of the flame when the burner is operating with liquid fuel responsible.

In DE-U-89 09 288 ist weiterhin eine Feuerung beschrieben, die ebenfalls eine Einrichtung zum Rückführen von Abgasen aufweist. An der Innenseite des Brennerrohres sind Düsen zur Beschleunigung der Verbrennungsluft bzw. Bildung eines Niederdruckes hinter den besagten Düsen vorgesehen. In der Wandung des Brennerrohres befinden sich Öffnungen zur Injektion von Verbrennungsprodukten in den Niederdruckbereich und eine Stauscheibe ist zur Verwirbelung der Primärluft vorgesehen. Es werden jedoch keine Mittel offenbart, die dem Gasgemisch einen Drall um die Brennerachse erteilen.In DE-U-89 09 288 a furnace is also described also has a device for recycling exhaust gases. At the Inside the burner tube are nozzles to accelerate the Combustion air or formation of a low pressure behind the said nozzles intended. In the wall of the burner tube there are openings for Injection of combustion products in the low pressure range and one Baffle plate is provided for swirling the primary air. However, there will be no means revealed that the gas mixture had a swirl around the burner axis To give.

Die Vorzüge eines Brenners mit Abgasrückführung bestehen darin, dass die grösstmögliche Verbrennungstemperatur, bei guter Vermischung von Luft und Abgas vor der Verbrennung und bei ausreichender Kühlung des rückgeführten Abgases, stark abgesenkt wird. Als direkte Folge der Absenkung der maximalen Verbrennungstemperatur wird die Emission der Stickoxide (NOx) abgesenkt. Bei guter Vorverdampfung und Vormischung wird die Verbrennungstemperatur ausserdem sehr gleichförmig. Damit können gleichzeitig auch die Emissionen von Kohlenmonoxid (CO) und unverbrannten Kohlenwasserstoffen (UHC) gering gehalten werden. Schliesslich kann dank guter Vorverdampfung und Vormischung die Entstehung von Russ vermieden werden.The advantages of a burner with exhaust gas recirculation are that the highest possible combustion temperature with good mixing of Air and exhaust gas before combustion and with sufficient cooling of the recirculated exhaust gas, is greatly reduced. As a direct result of the lowering the maximum combustion temperature, the emission of nitrogen oxides (NOx) lowered. With good pre-evaporation and premixing, the combustion temperature also very uniform. So that can emissions of carbon monoxide (CO) and unburned hydrocarbons (UHC) kept low become. Finally, thanks to good pre-evaporation and premixing the formation of soot can be avoided.

Der Erfindung liegt die Aufgabe zugrunde, einen Brenner der eingangs genannten Art konstruktiv zu vereinfachen und zu erweitern, um die Schadstoffemissionen und den Bedarf an Fremdenergie bei jedem Betrieb zu minimieren, dies sowohl bei einem Betrieb mit flüssigen als auch mit gasförmigen Brennstoffen. Erfindungsgemäss wird dies durch die im Anspruch 1 aufgezählten Merkmale erreicht.The invention is based on the object constructively a burner of the type mentioned at the beginning simplify and expand to pollutant emissions and the need for external energy for each company minimize this both when operating with liquid as well as with gaseous fuels. According to the invention this is due to the features listed in claim 1 reached.

Gegenüber den eingangs erwähnten, vorbekannten Brennern ist ein wesentlicher Vorteil der Erfindung darin zu sehen, dass eine besonders innige Vermischung von Abgas und Luft schon vor der Brennstoffeindüsung stattfindet. Damit werden auch eine ausgezeichnete Vorverdampfung und Vormischung des Brennstoffs erreicht. Ausserdem ist die Konstruktion der vorliegenden Erfindung entscheidend einfacher als beispielsweise die aus EP-A-0 394 800 bekannte. Ein weiterer Vorteil der Erfindung liegt im guten Wirkungsgrad der ringförmigen Strahlpumpe, welche Abgase durch den Frischluftstrom mitreisst. Man kann diesen Wirkungsgrad noch verbessern, indem man den Frischlufteintritt in den Mischkanal in eine Anzahl getrennter Einlassöffnungen aufteilt. Dank seinem hohen Strahlpumpenwirkungsgrad und seinem niedrigen Gegendruck nach der Strahlpumpe kann der hier vorgeschlagene Brenner mit einem herkömmlichen einstufigen Gebläse betrieben werden. Ausserdem kann gegebenenfalls auf die sonst bei Abgasrückführbrennern üblichen Starthilfemassnahmen verzichtet werden.Compared to the previously known ones Burners are a major advantage of the invention to see that a particularly intimate mixture of exhaust gas and air even before the fuel injection takes place. It will also be an excellent one Pre-evaporation and premixing of the fuel achieved. In addition, the construction of the present invention significantly simpler than, for example, that from EP-A-0 394,800 known. Another advantage of the invention lies in the good efficiency of the annular jet pump, which exhaust gases are entrained by the fresh air flow. Man can improve this efficiency even more by using the Fresh air entering the mixing duct in a number of separate Splits inlet openings. Thanks to its high Jet pump efficiency and its low back pressure after the jet pump can the burner proposed here operated with a conventional single-stage blower become. In addition, if necessary, the otherwise at Exhaust gas recirculation burners do not have the usual start-up measures become.

Wird der Brenner mit flüssigem Brennstoff betrieben, so sorgt die erhöhte Temperatur des Abgas-Luftgemisches in Kombination mit der Flammstabilisierung im Bereich des Brenneraustrittes dafür, dass ein Gemisch von Frischluft, Abgas und vorverdampftem Brennstoff der Verbrennung zugeführt wird. Die aufgrund der Abgasrückführung erreichte Optimierung des Gemisches beeinflusst auch die Flammentemperatur im Brennraum in der Weise, dass dort keine lokalen Temperaturspitzen auftreten können, welche zu erhöhter NOx-Bildung führen würden. Anderseits vermeidet die Vormischung des Brennstoffs das Auftreten von Flammzonen mit zu niedriger Temperatur, die zu erhöhter CO- und UHC-Emission führen würden. Obwohl beim Betrieb mit gasförmigem Brennstoff keine Vorverdampfung erforderlich ist, kommen dabei ansonsten die gleichen Vorteile zum Tragen wie beim Betrieb mit flüssigem Brennstoff.If the burner is operated with liquid fuel, this is what the increased temperature of the exhaust gas / air mixture ensures in combination with flame stabilization in Area of the burner outlet for a mixture of Fresh air, exhaust gas and pre-evaporated combustion fuel is fed. The due to the exhaust gas recirculation achieved optimization of the mixture also affects the flame temperature in the combustion chamber in such a way that no local temperature peaks can occur there, which would lead to increased NOx formation. On the other hand premixing the fuel prevents occurrence of flame zones with too low temperature, those too high CO and UHC emissions would lead. Although in operation no pre-evaporation required with gaseous fuel otherwise the same advantages come with it to wear as when operating with liquid fuel.

Ein weiterer Vorteil der Erfindung liegt in der Möglichkeit einer besonderen Flammstabilisierung. Wenn sich nämlich die Aussenschale nach der Verengung zu einem passend dimensionierten Diffusor verbreitert, kann die Flammenfront in der von der Strahlpumpe erzeugten Wirbelströmung nicht bis zur Brennstoffeindüsung zurückwandern. Damit wird nicht nur die gewünschte Vormischung und Vorverdampfung erreicht, sondern es gelingt auch, die Brennstoffeindüsung vor Verrussung und Überhitzung zu schützen. Diese Eigenschaft trägt dazu bei, die Störanfälligkeit des Brenners zu vermindern.Another advantage of the invention lies in the possibility of special flame stabilization. If the outer shell closes after the narrowing a suitably dimensioned diffuser, can the flame front in the one generated by the jet pump Do not migrate the vortex flow back to the fuel injection. This will not only be the desired premix and pre-evaporation achieved, but it also succeeds in that Fuel injection before sooting and overheating protect. This property contributes to the susceptibility to failure to reduce the burner.

Vorteilhafte und zweckmässige Weiterbildungen der erfindungsgemässen Aufgabenlösung sind in den weiteren abhängigen Ansprüchen gekennzeichnet. Im folgenden werden anhand der Zeichnungen drei Ausführungsbeispiele der Erfindung erläutert. Alle für das unmittelbare Verständnis der Erfindung nicht erforderlichen Elemente sind fortgelassen. Die Strömungsrichtung der verschiedenen Medien sind mit Pfeilen angegeben. In den verschiedenen Figuren sind jeweils gleiche Elemente mit den gleichen Bezugszeichen versehen. Advantageous and practical training the task solution according to the invention are in the further dependent claims marked. Hereinafter are three embodiments with reference to the drawings of the invention explained. All for immediate understanding are not necessary elements of the invention omitted. The flow direction of the different media are indicated by arrows. In the different figures are the same elements with the same reference numerals Mistake.

Es zeigt:

  • Fig. 1 eine schematische Darstellung einer ersten Ausführungsvariante des kompletten Brenners,
  • Fig. 2 ein Bild des zur Brennerachse senkrecht verlaufenden Schnittes der ersten Ausführungsvariante am Ende der Lufteintrittsbohrungen,
  • Fig. 3 eine schematische Darstellung einer zweiten Ausführungsvariante des kompletten Brenners, und
  • Fig. 4 eine schematische Darstellung einer dritten Ausführungsvariante des kompletten Brenners.
    • It shows:
  • 1 is a schematic representation of a first embodiment of the complete burner,
  • 2 shows an image of the section of the first embodiment variant running perpendicular to the burner axis at the end of the air inlet bores,
  • Fig. 3 is a schematic representation of a second embodiment of the complete burner, and
  • Fig. 4 is a schematic representation of a third embodiment of the complete burner.

    • Mögliche Ausführungsbeispiele sind in den Figuren 1, 2, 3 und 4 schematisch dargestellt. Wie die Figuren 1, 3 und 4 verdeutlichen, besteht der Brennerkörper aus einer im wesentlichen rotationssymmetrischen Aussenschale 1 und einer konzentrisch dazu angeordneten Innenschale 2. Die Aussenschale 1 weist eine markante Verengung 3 und ein Diffusorteil 4 auf. Ein Mischkanal 5 wird von einem Teil 6 der Aussenschale 1 und einem Teil 7 der Innenschale 2 begrenzt, wobei der Verlauf der Schalenteile 6 und 7 so gewählt ist, dass die Querschnittsfläche der Strahlpumpenmischstrecke 5 über eine in Hauptströmungsrichtung (d.h. parallel zur Brennerachse) gemessenen Länge von wenigstens zwei mal die radiale Spaltbreite der Mischstrecke weitgehend konstant bleibt. Dabei beginnt der Mischkanal 5 unmittelbar nach der Zusammenführung von Luft und Abgas. Wie in den Ausführungsbeispielen in Fig. 1, Fig. 3 und Fig. 4 gezeigt ist, wird der Mischkanal 5 vorzugsweise zylindrisch ausgeführt. Es ist jedoch denkbar in bestimmten Fällen aus Platzgründen eine z.B. kegelförmige Mischstrecke zu bevorzugen. Eine Brennstoffdüse 8 sorgt für die Zufuhr des flüssigen Brennstoffes 9, wobei ein Sprühkegel 11 durch eine zentrale Zerstäuberbohrung 10 erzeugt wird. Über eine Zuleitung 12 wird einem Verteilerring 13 gasförmiger Brennstoff 14 zugeführt. Aus dem Verteilerring 13 gelangt der gasförmige Brennstoff 14 durch eine regelmässige Anordnung von Gaseindüsungsbohrungen 15, die vorzugsweise radial nach aussen gerichtet sind, zum Eintritt der Strahlpumpenmischstrecke 5. Bei bestimmten. Brennerkonfigurationen kann jedoch aus Platzgründen eine (nicht gezeigte) axiale Gaseindüsung bevorzugt werden. Die Frischluft 16 tritt durch eine ringförmige Anordnung von Luftbohrungen 17 in den Mischraum 5 ein, wobei die Achsen der Luftbohrungen 17 im Falle eines zylindrischen Mischraumes 5 vorzugsweise windschief zur Brennerachse A liegen sollten. Im Falle eines nicht-zylindrischen Mischraumes 5 würde die Ausrichtung der Luftbohrungen dergestalt gewählt, dass ihre Achsen mit einer leichten Anstellung in Umfangsrichtung und parallel zur Mittelfläche der Mischkammer verlaufen. Eine leichte Anstellung der Achsen der Luftbohrungen 17 in tangentialer Richtung trägt zur Erzeugung einer Wirbelströmung bei, welche die Umströmung der Innenschale 2 und Stabilisierung der Flamme 18 garantiert. Abgas wird im Falle des in Fig. 1 dargestellten Ausführungsbeispiels durch eine ringförmige und regelmässige Anordnung von Abgaseintrittsöffnungen 19 in den Mischraum 5 eingesaugt. Leitschaufeln 20 erteilen der eintretenden Abgasströmung 21 einen Drall, welcher zusammen mit der von den schräg orientierten Luftbohrungen 17 verursachten Luftverdrallung einen Drall des Abgas-Luftgemisches in und nach der Mischstrecke 5 erzeugt. Es kann jedoch fallweise entweder auf die Luftverdrallung oder auf die Abgasverdrallung verzichtet werden. Je nach Temperatur des angesaugten Abgases 21 beträgt die ideale Abgasrückführrate etwa 40% bis 70%, bezogen auf den Frischluftmassenstrom. Die Abgasrückführrate wird so gewählt, dass die adiabate Verbrennungstemperatur in der Flammenzone 18 bei etwa 1350 Grad Celsius liegt. Damit können sowohl die NOx-Emissionen als auch die CO- und UHC-Emissionen klein gehalten werden. Bei hohen Temperaturen des rückgeführten Abgases 21, und entsprechend hohen Abgasrückführraten, muss der Strahlpumpenwirkungsgrad ausreichend gross sein. Zu diesem Zweck sollte das rückgeführte Abgas 21 mit einer möglichst hohen axialen Geschwindigkeitskomponente in die Mischstrecke 5 gerissen werden.Possible exemplary embodiments are in the figures 1, 2, 3 and 4 are shown schematically. Like the figures 1, 3 and 4 clarify, there is the burner body from an essentially rotationally symmetrical outer shell 1 and an inner shell arranged concentrically to it 2. The outer shell 1 has a striking narrowing 3 and a diffuser part 4. A mixing channel 5 is of a part 6 of the outer shell 1 and a part 7 of the Inner shell 2 limited, the course of the shell parts 6 and 7 is chosen so that the cross-sectional area the jet pump mixing section 5 via a in the main flow direction (i.e. parallel to the burner axis) Length of at least two times the radial gap width of the Mixing section remains largely constant. It starts the mixing channel 5 immediately after the merger of Air and exhaust gas. As in the exemplary embodiments in 1, 3 and 4, the mixing channel 5 preferably cylindrical. However, it is conceivable in certain cases for reasons of space, e.g. to prefer a conical mixing section. A fuel nozzle 8 ensures the supply of liquid fuel 9, a spray cone 11 through a central atomizing bore 10 is generated. Via a feed line 12 Distributor ring 13 fed gaseous fuel 14. The gaseous fuel passes from the distributor ring 13 14 through a regular arrangement of gas injection holes 15, which preferably radially outwards are directed to the entrance of the jet pump mixing section 5. With certain. However, burner configurations can be made For reasons of space, an axial gas injection (not shown) to be favoured. The fresh air 16 passes through a annular arrangement of air holes 17 in the mixing room 5 a, the axes of the air holes 17 in the case a cylindrical mixing chamber 5 preferably skewed should lie to burner axis A. in case of a non-cylindrical mixing room 5 would be the alignment the air holes chosen so that their axes with a slight adjustment in the circumferential direction and parallel run to the middle surface of the mixing chamber. A easy adjustment of the axes of the air holes 17 in tangential direction creates a vortex flow at which the flow around the inner shell 2 and Stabilization of the flame 18 guaranteed. Exhaust gas is in the Case of the embodiment shown in Fig. 1 through an annular and regular arrangement of exhaust gas inlet openings 19 sucked into the mixing chamber 5. Guide vanes 20 issue the incoming exhaust gas flow 21 a twist, which together with that of the oblique oriented air holes 17 caused air swirl a swirl of the exhaust gas-air mixture in and after the Mixing section 5 generated. However, it can be either air swirl or exhaust gas swirl to be dispensed with. Depending on the temperature of the intake exhaust gas 21 the ideal exhaust gas recirculation rate is about 40% up to 70%, based on the fresh air mass flow. The exhaust gas recirculation rate is chosen so that the adiabatic combustion temperature in the flame zone 18 at about 1350 Degrees Celsius. This can reduce both the NOx emissions as well as the CO and UHC emissions kept low become. At high temperatures the recirculated Exhaust gas 21, and correspondingly high exhaust gas recirculation rates, the jet pump efficiency must be sufficiently high. For this purpose, the recirculated exhaust gas 21 should the highest possible axial speed component be torn into the mixing section 5.

    Zu diesem Zweck zeigt Figur 3 ein Ausführungsbeispiel, dessen Zuführungs-Geometrie einen besonders hohen Strahlpumpenwirkungsgrad ermöglicht. In diesem Fall sollte die Verengung 3 der Aussenschale relativ klein bemessen sein, damit der Gegendruck, den die Strahlpumpe überwinden muss, möglichst gering gehalten werden kann. In dieser Ausführung tritt das rückgeführte Abgas 21 unverdrallt in den Mischkanal 5 ein, und die Verdrallung des Gasgemisches wird entweder durch den Frischluftstrom oder durch (nicht gezeigte) Leitschaufeln im Mischkanal erzeugt. Die Querschnittsfläche aller Luftbohrungen 17 sollte vorzugsweise etwa 10% bis 20% der Querschnittsfläche des Mischraumes 5 betragen. Alle Brennerteile, die sich auf der rechten Seite der Kesselwand 22 und damit im Innern des Kessels befinden, sind naturgemäss einer hohen thermischen Belastung ausgesetzt. Im Falle der Flüssigbrennstoffdüse 8 können übermässig hohe Temperaturen, insbesonders nach der Abschaltung des Brenners, zu Brennstoffverkokungsproblemen führen. Zum thermischen Schutz der Brennstoffdüse 8 weisen die in der Figur 1 gezeigten Ausführungsbeispiele daher einen luftdurchströmten Abschirmring 23 auf. Der ebenfalls luftdurchströmte Spülring 24 erzeugt zusammen mit dem Abschirmring einen Luftschleier, der die Brennstoffdüse 8 gegen rückströmenden Brennstoff und heisse Gase abschirmt. Ausserdem sorgt dieser Luftschleier beim Start des Brenners für ideale Zündbedingungen in unmittelbarer Nähe der Zerstäuberbohrung 10. In Figur 3 ist eine weitere Möglichkeit aufgezeigt, in welcher durch einen Umlenkkanal ein Teil der Frischluft in den stromwärts liegenden Teil des Mischkanals geführt wird und dadurch die Innenkontur kühlt. Die in Fig. 4 dargestellte Ausführungsvariante zeigt eine weitere Möglichkeit der thermischen Abschirmung der Brennstoffdüse 8. Anstatt des Abschirmkanales 23 ist hier zur Kühlung die gesamte Innenschale 2 mit Effusions-Kühlbohrungen 25 versehen. Damit können sowohl die Innenschale 2.als auch die Brennstoffdüse 8 auf niedriger Temperatur gehalten werden.For this purpose, FIG. 3 shows an exemplary embodiment, its feeding geometry is special enables high jet pump efficiency. In this Case, the narrowing 3 of the outer shell should be relative be small so that the back pressure that the Jet pump must overcome, kept as low as possible can be. In this version, the returned occurs Exhaust gas 21 swirled into the mixing channel 5, and the Twisting of the gas mixture is caused either by the Fresh air flow or through (not shown) guide vanes generated in the mixing channel. The cross-sectional area of all air holes 17 should preferably be about 10% to 20% of the Cross-sectional area of the mixing room 5. All burner parts, which is on the right side of the boiler wall 22 and thus located inside the boiler are natural exposed to high thermal stress. in the The case of the liquid fuel nozzle 8 can be excessively high Temperatures, especially after the burner has been switched off, lead to fuel coking problems. For thermal Protection of the fuel nozzle 8 have the in the figure 1 therefore show an air flow Shield ring 23 on. The air flow Flushing ring 24 produces together with the shielding ring an air curtain that connects the fuel nozzle 8 shields against backflowing fuel and hot gases. This air curtain also ensures the start of the burner for ideal ignition conditions in the immediate Near the atomizer bore 10. In Figure 3 is another Possibility shown in which through a deflection channel part of the fresh air in the upstream Part of the mixing channel is guided and thereby the inner contour cools. The embodiment shown in Fig. 4 shows another possibility of thermal shielding the fuel nozzle 8. Instead of the shielding channel 23 is here the entire inner shell 2 for cooling Effusion cooling holes 25 are provided. So that both the inner shell 2. as well as the fuel nozzle 8 on lower Temperature are maintained.

    Claims (10)

    1. Exhaust gas recirculation burner for hot gas production with feed lines for liquid and/or gaseous fuels, with a mixing duct (5) limited by two concentric shells (1, 2) rotationally symmetrical to the burner axis for mixing recirculated exhaust gases with fresh air upstream of the introduction of fuel, the mixing duct (5) being formed as an annular jet pump, the exhaust gases being sucked in through the fresh air duct and the inner shell (2) in the main flow direction terminating upstream of a constriction of the outer shell (1), characterised in that the mixing duct (5) has means for imparting a twist about the burner axis (A) to the gas mixture moving in a main flow direction parallel to the burner axis (A).
    2. Exhaust gas recirculation burner according to claim 1, characterised in that the outer shell (1) broadens after the constriction (3) into a diffuser (4).
    3. Exhaust gas recirculation burner according to claim 1 or 2, characterised by a plurality of apertures (17) for the entry of fresh air (16) into the mixing duct (5) which are designed in order to form a plurality of individual, separate sucking jet pumps for recirculation of the exhaust gases (21).
    4. Exhaust gas recirculation burner according to one of the preceding claims, characterised in that the mixing duct (5) has a length of at least twice its mean annular gap width.
    5. Exhaust gas recirculation burner according to one of the preceding claims, characterised in that the mixing duct (5) has a substantially constant flow cross-section.
    6. Exhaust gas recirculation burner according to one of claims 3 to 5, characterised in that the inlet apertures (17) for fresh air (16) into the mixing duct (5) have means to impart a twist to the flow in the mixing duct (5).
    7. Exhaust gas recirculation burner according to one of the preceding claims, characterised in that the inlet apertures (19) for exhaust gases (21) into the mixing channel (5) have means (20) to impart a twist to the flow in the mixing duct (5).
    8. Exhaust gas recirculation burner according to one of the preceding claims, characterised by one or more atomiser nozzles (8) for liquid fuel (9) arranged in the main flow direction downstream of the mixing duct (5)
    9. Exhaust gas recirculation burner according to one of the preceding claims, characterised by a feed line (12) which is provided in order to introduce gaseous fuel (14) into the mixing duct (5) through a plurality of annularly arranged holes (15).
    10. Exhaust gas recirculation burner according to one of the preceding claims, characterised by an adjustable throttle in order to control the exhaust gas stream (21) flowing into the mixing duct (5) as a function of the furnace geometry and/or of the operating state of the burner.
    EP96107956A 1996-05-19 1996-05-19 Burner with exhaust gas recirculation Expired - Lifetime EP0809070B1 (en)

    Priority Applications (3)

    Application Number Priority Date Filing Date Title
    AT96107956T ATE204972T1 (en) 1996-05-19 1996-05-19 BURNER WITH EXHAUST GAS RECIRCULATION
    EP96107956A EP0809070B1 (en) 1996-05-19 1996-05-19 Burner with exhaust gas recirculation
    DE59607583T DE59607583D1 (en) 1996-05-19 1996-05-19 Burner with exhaust gas recirculation

    Applications Claiming Priority (1)

    Application Number Priority Date Filing Date Title
    EP96107956A EP0809070B1 (en) 1996-05-19 1996-05-19 Burner with exhaust gas recirculation

    Publications (2)

    Publication Number Publication Date
    EP0809070A1 EP0809070A1 (en) 1997-11-26
    EP0809070B1 true EP0809070B1 (en) 2001-08-29

    Family

    ID=8222794

    Family Applications (1)

    Application Number Title Priority Date Filing Date
    EP96107956A Expired - Lifetime EP0809070B1 (en) 1996-05-19 1996-05-19 Burner with exhaust gas recirculation

    Country Status (3)

    Country Link
    EP (1) EP0809070B1 (en)
    AT (1) ATE204972T1 (en)
    DE (1) DE59607583D1 (en)

    Cited By (1)

    * Cited by examiner, † Cited by third party
    Publication number Priority date Publication date Assignee Title
    US11187408B2 (en) 2019-04-25 2021-11-30 Fives North American Combustion, Inc. Apparatus and method for variable mode mixing of combustion reactants

    Families Citing this family (4)

    * Cited by examiner, † Cited by third party
    Publication number Priority date Publication date Assignee Title
    KR100478085B1 (en) * 1999-12-22 2005-03-24 주식회사 포스코 Gas burner with oxygen supply
    DE102006049875A1 (en) * 2006-10-23 2008-04-24 Robert Bosch Gmbh Air/fuel-mixture forming device, has doser supplying liquid into area, in which gas is supplied to another area for producing mixture, and turbulent flow producing device producing flow to mix mixture with another mixture in latter area
    DE102012110506B4 (en) * 2012-11-02 2017-04-27 Webasto SE Hochdruckzerstäubungsbrenneranordnung
    DE102016001893A1 (en) * 2016-02-17 2017-08-17 Eisenmann Se Burner unit and device for tempering objects

    Family Cites Families (6)

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    Publication number Priority date Publication date Assignee Title
    DE3822004A1 (en) * 1988-06-30 1990-01-04 Babcock Werke Ag BURNER
    CH678100A5 (en) * 1989-03-10 1991-07-31 Oertli Waermetechnik Ag
    DE8909288U1 (en) * 1989-07-14 1989-11-30 Electro-Oil Gmbh, 2057 Reinbek, De
    EP0483520A3 (en) * 1990-10-02 1992-10-14 Vereinigte Aluminium-Werke Aktiengesellschaft Method and apparatus for the combustion of gaseous and liquid fuels generating a low emission of noxious products
    DE9213737U1 (en) * 1992-10-12 1992-12-10 Meku Metallverarbeitungs-Gmbh, 7735 Dauchingen, De
    DE4238529C2 (en) * 1992-11-14 1999-02-04 Deutsch Zentr Luft & Raumfahrt Burners for hot gas generation

    Cited By (1)

    * Cited by examiner, † Cited by third party
    Publication number Priority date Publication date Assignee Title
    US11187408B2 (en) 2019-04-25 2021-11-30 Fives North American Combustion, Inc. Apparatus and method for variable mode mixing of combustion reactants

    Also Published As

    Publication number Publication date
    EP0809070A1 (en) 1997-11-26
    ATE204972T1 (en) 2001-09-15
    DE59607583D1 (en) 2001-10-04

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