EP1279898B1 - Premix burner with high flame stability - Google Patents

Premix burner with high flame stability Download PDF

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Publication number
EP1279898B1
EP1279898B1 EP02405615A EP02405615A EP1279898B1 EP 1279898 B1 EP1279898 B1 EP 1279898B1 EP 02405615 A EP02405615 A EP 02405615A EP 02405615 A EP02405615 A EP 02405615A EP 1279898 B1 EP1279898 B1 EP 1279898B1
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EP
European Patent Office
Prior art keywords
mesh
burner according
premixing burner
premixing
wire
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP02405615A
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German (de)
French (fr)
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EP1279898A2 (en
EP1279898A3 (en
Inventor
Timothy Griffin
Peter Jansohn
Thomas Ruck
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General Electric Technology GmbH
Original Assignee
Alstom Technology AG
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Filing date
Publication date
Priority claimed from DE10136313A external-priority patent/DE10136313A1/en
Priority claimed from DE10164097A external-priority patent/DE10164097A1/en
Application filed by Alstom Technology AG filed Critical Alstom Technology AG
Publication of EP1279898A2 publication Critical patent/EP1279898A2/en
Publication of EP1279898A3 publication Critical patent/EP1279898A3/en
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    • 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 
    • F23C7/00—Combustion apparatus characterised by arrangements for air supply
    • F23C7/002—Combustion apparatus characterised by arrangements for air supply the air being submitted to a rotary or spinning motion
    • 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
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23D—BURNERS
    • F23D14/00—Burners for combustion of a gas, e.g. of a gas stored under pressure as a liquid
    • F23D14/46—Details, e.g. noise reduction means
    • F23D14/72—Safety devices, e.g. operative in case of failure of gas supply
    • F23D14/74—Preventing flame lift-off
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23M—CASINGS, LININGS, WALLS OR DOORS SPECIALLY ADAPTED FOR COMBUSTION CHAMBERS, e.g. FIREBRIDGES; DEVICES FOR DEFLECTING AIR, FLAMES OR COMBUSTION PRODUCTS IN COMBUSTION CHAMBERS; SAFETY ARRANGEMENTS SPECIALLY ADAPTED FOR COMBUSTION APPARATUS; DETAILS OF COMBUSTION CHAMBERS, NOT OTHERWISE PROVIDED FOR
    • F23M20/00—Details of combustion chambers, not otherwise provided for, e.g. means for storing heat from flames
    • F23M20/005—Noise absorbing means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23R—GENERATING COMBUSTION PRODUCTS OF HIGH PRESSURE OR HIGH VELOCITY, e.g. GAS-TURBINE COMBUSTION CHAMBERS
    • F23R3/00—Continuous combustion chambers using liquid or gaseous fuel
    • F23R3/02—Continuous combustion chambers using liquid or gaseous fuel characterised by the air-flow or gas-flow configuration
    • F23R3/04—Air inlet arrangements
    • F23R3/10—Air inlet arrangements for primary air
    • F23R3/12—Air inlet arrangements for primary air inducing a vortex
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23R—GENERATING COMBUSTION PRODUCTS OF HIGH PRESSURE OR HIGH VELOCITY, e.g. GAS-TURBINE COMBUSTION CHAMBERS
    • F23R3/00—Continuous combustion chambers using liquid or gaseous fuel
    • F23R3/28—Continuous combustion chambers using liquid or gaseous fuel characterised by the fuel supply
    • F23R3/286—Continuous combustion chambers using liquid or gaseous fuel characterised by the fuel supply having fuel-air premixing devices
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23R—GENERATING COMBUSTION PRODUCTS OF HIGH PRESSURE OR HIGH VELOCITY, e.g. GAS-TURBINE COMBUSTION CHAMBERS
    • F23R3/00—Continuous combustion chambers using liquid or gaseous fuel
    • F23R3/28—Continuous combustion chambers using liquid or gaseous fuel characterised by the fuel supply
    • F23R3/36—Supply of different fuels
    • 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 
    • F23C2900/00—Special features of, or arrangements for combustion apparatus using fluid fuels or solid fuels suspended in air; Combustion processes therefor
    • F23C2900/07002—Premix burners with air inlet slots obtained between offset curved wall surfaces, e.g. double cone burners
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23R—GENERATING COMBUSTION PRODUCTS OF HIGH PRESSURE OR HIGH VELOCITY, e.g. GAS-TURBINE COMBUSTION CHAMBERS
    • F23R2900/00—Special features of, or arrangements for continuous combustion chambers; Combustion processes therefor
    • F23R2900/00014—Reducing thermo-acoustic vibrations by passive means, e.g. by Helmholtz resonators

Definitions

  • the invention relates to a premix burner for a heat generator, in particular for use in a gas turbine plant, according to the preamble of claim 1.
  • Premix burners have become known in which a combustion air flow is introduced tangentially into a burner interior via a swirl generator and mixed with fuel.
  • Gaseous fuels for example natural gas
  • liquid fuels such as heating oil
  • At the burner exit the resulting vortex flow bursts at a cross-sectional jump, inducing a return flow zone which serves to stabilize a flame during operation of the burner.
  • a mixing section can be arranged downstream of the swirl generator, by means of which an improved premixing of fuels of various types is ensured.
  • thermoacoustic vibrations occur, which can lead to undesirable effects, such as high mechanical stress, increased NO x emissions by inhomogeneous combustion and even extinguishment of the flame.
  • an increasing proportion of air through the burner itself is passed, reduces the sound-absorbing effect of the inflowing into the combustion chamber cooling air, which is why especially in such modern gas turbines associated with undesirable vibrations problems occur more.
  • the object of the present invention is to improve the stability of lean premix combustion of modern burners of the type mentioned at the outset, as used in particular in the combustion chambers of gas turbines.
  • An essential increase in the combustion temperature must be avoided in order to continue to ensure low-emission operation.
  • the basic idea of the invention is to equip a mixing section of a premix burner with a net-like structure extending at least approximately completely over the flow cross-section of the mixing section.
  • the net-like structure consists of a wire mesh or a plurality of mutually spaced layers of wire mesh.
  • the arrangement of five to 100, in particular ten to 20, at least approximately perpendicular to the longitudinal axis of the burner aligned wire mesh has proven to be advantageous.
  • the net-like structure consists of a porous body integrated in the burner cavity made of a foamed material.
  • the reticulated structure is preferably to be designed so that it causes no appreciable pressure loss or local vortices, which could permanently affect the flow in the mixing section. This is ensured in a wire mesh-based embodiment in that wire size and mesh size are matched in their dimensions to one another that the largest possible open screen surface, preferably in the order of more than 90%, remains.
  • the reticulated structure is equipped with a catalytically active surface to assist combustion.
  • thermoacoustic behavior of the material is due to a reticular structure extending over the entire flow cross section Burner is changed in a positive manner and as a result, a reduction in the vibration tendency of the burner and thus a stabilization of the flame are recorded.
  • This positive effect is obviously due to the property of the mesh structure to isolate and attenuate sound waves propagating in the combustion chamber. Pressure waves from the combustion chamber in the direction of gas injection are partially damped by the structure and partly isolated, that is, transmitted or radiated again in a changed frequency. Due to the much shorter length of the reflected back into the combustion chamber sound waves, the excitation of pressure oscillations in the combustion chamber is shifted to other frequency ranges and reduced. Material and dimensioning of the network structure influence their damping and isolation behavior.
  • This stabilizing effect of the network structure is additionally enhanced by the oxidation-promoting catalytic activity of its surface.
  • the invention is applicable to premix burners, which are well known and familiar to those skilled in the art from the cited prior art.
  • the invention can be readily combined with all disclosed in the writings cited therein and further developed from these writings, the skilled worker familiar burner types, which in the variety the possible embodiments are only partially reflected by the preferred variants specified in the subclaims.
  • FIG. 1 gives in a highly schematic way the essence of the invention again.
  • a swirl generator (100) is operative, which may be a prior art premix burner, as described, inter alia, in the publications cited in this disclosure.
  • These exemplarily quoted burners are all based on a common principle. They have an axially extending, at least approximately rotationally symmetrical cavity (102) into which combustion air flows via inlet slots (101) extending preferably parallel to the longitudinal axis (106). Due to the tangential orientation of these more or less slit-shaped inlet openings (101), the combustion air receives a strong tangential velocity component from which, in interaction with the axial direction towards the burner port, a swirling flow (103) results through said interior space (102).
  • the enrichment of the combustion air with fuel takes place alternatively or additionally via means (104) on the housing jacket near the combustion air inlet slots (101) and / or via central feed means (105) in the burner axis (106).
  • these burners have in common that the flow cross-section in the direction of the burner outlet steadily widened in order to maintain approximately constant flow conditions with the increasing mass flow.
  • the burners exemplified in this document are based on the described unitary principle, the invention should not be restricted to this particular type of swirl burners, but should include any type of premix burners whose flame stability is to be increased while the emission of pollutants remains consistently low.
  • a net-like structure (201) is now arranged in a downstream region of the burner within the mixing section (200) of the combustion air with the fuel (s).
  • This network structure (201) consists of at least one wire mesh (202) spanning the flow cross section (203).
  • the wire mesh or fabrics (202) have a mesh size in a range of 250 ⁇ m to 1000 ⁇ m and a wire thickness of 100 ⁇ m to 500 ⁇ m. In order not to adversely affect the flow conditions, these parameters of the wire mesh (202) are coordinated so that the largest possible open screen surface, preferably in the order of more than 90%, remains. If a plurality of wire meshes (202) spanning the flow cross-section (203) are arranged, their spacing should correspond at least to the wire thickness.
  • the network structure (201) has a positive effect on the thermoacoustic behavior of the burner.
  • Known occurs in burners of the generic type, the not negligible problem of shear layer formation between located in the combustion chamber hot combustion gases and the exiting mixture of combustion air and fuels.
  • These shear layers initiate the so-called Kelvin-Helmholtz waves, from which, under operating conditions, reaction rate fluctuations and, as a result, thermoacoustic oscillations of typical frequency result.
  • the pressure waves propagating in the combustion chamber (300) strike the wire mesh (202) and cause it to vibrate.
  • vibration energy is partially absorbed by the tissue (202) and partially reflected back to the other frequency ranges downstream in the combustion chamber (300) or forwarded upstream for gas injection.
  • the wire mesh (202) may additionally have a catalytic coating promoting the combustion process according to a supplementary embodiment variant.
  • Suitable catalysts are the materials known per se, such as noble metals (Pd, Pt, Rh, etc.), metal oxides (MnO 2 , NiO, etc.), alone or in admixture with a cocatalyst.
  • metallic materials are the requirements in terms of vibration reduction and carrier properties for catalysts best meet. Good results have been achieved with materials based on aluminum-containing or aluminum-treated iron or steel alloys. If these materials contain a sufficiently high proportion of aluminum, oxidation on the surface forms aluminum whiskers which give rise to a rough and chemically active surface, which is very suitable as a carrier for a catalytically active coating material. According to a favorable embodiment, the steel mesh is coated with a porous ceramic material containing the catalyst material.
  • connection of the net structure (201) to the surrounding housing wall (205) can be made in any suitable way. Depending on the specific conditions of the application, a number of possibilities are open to the person skilled in the art. Two favorable embodiments are based on the embodiments according to Fig. 2 and 3 explained.
  • the Fig.2 and 3 show the realization of the invention with reference to a premix burner, as he from the EP 0 780 629 has become known.
  • the burner consists essentially of a swirl generator (100) for a combustion air stream, which is formed from at least two conical body parts, which are arranged with their axes relative to the burner axis (106) as well as mutually laterally offset. Due to this lateral offset of the partial bodies, tangential inlet slots (101) are formed between the partial bodies. Through the tangential inlet slots (101) flows a combustion air flow substantially tangentially into the interior (102) of the swirl generator (100).
  • a swirling flow (103) is formed in succession, the axial flow component of which points towards the downstream mouth of the swirl generator (100).
  • the split bodies are attached to a retaining ring (107) at the downstream end of the swirl generator (100).
  • a transition element (108) is further arranged in the retaining ring (107). This is provided with a number of transition channels (109) which convert the swirl flow (103) generated in the swirl generator (100) from the incoming combustion air into the mixing section (200) without sudden changes in cross section.
  • This mixing section (200) is used to produce a homogeneous mixture of combustion air and fuels of various kinds.
  • the mixing section (200) allows a lossless flow control, without a backflow can form.
  • the mixing section (200) Over the length of the mixing section (200) can influence the mix quality for all fuel types.
  • the combustion chamber (300) closes, wherein at the transition point a cross-sectional jump is present, behind which a central remindströmzone (301) is formed, which has the properties of a flame holder.
  • a flame from the premixed fuel / air mixture can stabilize. Due to the good premixing of air and fuel, this flame can be operated with a fairly high excess air - usually you will find on the burner itself air figures of two and above. Due to the comparatively cool combustion temperatures, very low nitrogen oxide emissions can be achieved with such burners without expensive exhaust aftertreatment.
  • the housing (205) surrounding the mixing section (200) is segmentally composed of individual tube sections (206), at the connection points (207) of which the wire meshes (202) are incorporated.
  • This variant shown schematically in Fig.2 , characterized by a smooth exchange of used tissues (202).
  • An alternative embodiment, shown in FIG Figure 3 consists of assembling the housing (205) of individual segments (206), wherein at least one segment (208) was equipped with the wire meshes (202) in a preceding working process.

Description

Technisches GebietTechnical area

Die Erfindung betrifft einen Vormischbrenner für einen Wärmeerzeuger, insbesondere für den Einsatz in einer Gasturbinenanlage, gemäss dem Oberbegriff des Anspruchs 1.The invention relates to a premix burner for a heat generator, in particular for use in a gas turbine plant, according to the preamble of claim 1.

Stand der TechnikState of the art

Aus der EP 0 321 809 , aus der WO 9317279 , sowie aus der EP 0 945 677 sind Vormischbrenner bekanntgeworden, bei denen ein Verbrennungsluftstrom über einen Drallerzeuger tangential in einen Brennerinnenraum eingebracht und mit Brennstoff vermischt wird. Gasförmige Brennstoffe, beispielsweise Erdgas, werden entlang den tangentialen Lufteintrittsschlitzen in den Verbrennungsluftstrom eingedüst, wohingegen flüssige Brennstoffe, wie Heizöl, vozugsweise über eine zentrale Düse am Brennerkopf eingedüst werden. Am Brenneraustritt platzt die entstehende Wirbelströmung an einem Querschnittssprung auf, wodurch eine Rückströmzone induziert wird, welche im Betrieb des Brenners zur Stabilisierung einer Flamme dient.From the EP 0 321 809 , from the WO 9317279 , as well as from the EP 0 945 677 Premix burners have become known in which a combustion air flow is introduced tangentially into a burner interior via a swirl generator and mixed with fuel. Gaseous fuels, for example natural gas, are injected into the combustion air flow along the tangential air inlet slots, whereas liquid fuels, such as heating oil, are preferably injected via a central nozzle at the burner head. At the burner exit the resulting vortex flow bursts at a cross-sectional jump, inducing a return flow zone which serves to stabilize a flame during operation of the burner.

Um unter den Bedingungen des Einsatzes in Gasturbinen auch bei Verwendung von Brennstoffen unterschiedlicher Provenienz und Zusammensetzung Störungen des Strömungsfeldes zu vermeiden und damit stets eine betriebssichere Flammenpositionierung zu erreichen, kann gemäss der Lehre der EP 0 780 629 stromab des Drallerzeugers eine Mischstrecke angeordnet werden, durch welche eine verbesserte Vormischung von Brennstoffen verschiedener Art gewährleistet wird.In order to avoid disturbances of the flow field under the conditions of use in gas turbines even when using fuels of different provenance and composition and thus always to achieve a reliable flame positioning, can according to the teaching of EP 0 780 629 downstream of the swirl generator, a mixing section can be arranged, by means of which an improved premixing of fuels of various types is ensured.

Wiewohl derartig konzipierte Brenner einen Betrieb mit sehr niedrigen Schadstoffemissionen ermöglichen, operieren sie oft gefährlich nahe an der Löschgrenze der Flamme: Übliche realisierte Flammentemperaturen mit den mageren Vormischflammen derartiger Brenner liegen um 1700K bis 1750K. Unter bestimmten Betriebsbedingungen kann die Löschgrenze der Flammen schon bei 1650K erreicht sein. Dieser Wert ist vergleichsweise hoch. Dies liegt in der Brennstoffarmut des Brennstoff-Luft-Gemisches begründet. Diese reduziert die Flammengeschwindigkeit, was letztlich in einer räumlich ausgedehnteren und daher instabileren Flammenfront resultiert.Although such designed burners enable operation with very low pollutant emissions, they often operate dangerously close to the extinguishing limit of the flame: common realized flame temperatures with the lean premix flames of such burners are around 1700K to 1750K. Under certain operating conditions, the extinguishing limit of the flames may already be reached at 1650K. This value is comparatively high. This is due to the fuel poverty of the fuel-air mixture. This reduces the flame speed, which ultimately results in a spatially extended and therefore more unstable flame front.

Eine stärkere Anfettung des Gemisches würde jedoch die Schadstoffemissionen nach oben treiben und den Einsatz magerer Vormischbrenner ad absurdum führen.Increased enrichment of the mixture, however, would increase pollutant emissions and render absurd the use of lean premix burners.

Des weiteren ist es bekannt, dass in Brennkammern von Gasturbinen häufig thermoakustische Schwingungen auftreten, die zu unerwünschten Effekten, wie etwa zu einer hohen mechanischen Beanspruchung, erhöhten NOx-Emissionen durch eine inhomogene Verbrennung und sogar zum Verlöschen der Flamme führen können. Da bei modernen Gasturbinen zum Zwecke der Erzielung niedriger NOx-Emissionen ein zunehmender Anteil Luft durch die Brenner selbst geleitet wird, reduziert sich die schalldämpfende Wirkung der in die Brennkammer einströmenden Kühlluft, weshalb gerade in solchen modernen Gasturbinen die mit unerwünschten Schwingungen verbundenen Probleme verstärkt auftreten.Furthermore, it is known that combustors of gas turbines often thermoacoustic vibrations occur, which can lead to undesirable effects, such as high mechanical stress, increased NO x emissions by inhomogeneous combustion and even extinguishment of the flame. As in modern gas turbines for the purpose of achieving low NO x emissions, an increasing proportion of air through the burner itself is passed, reduces the sound-absorbing effect of the inflowing into the combustion chamber cooling air, which is why especially in such modern gas turbines associated with undesirable vibrations problems occur more.

Darstellung der ErfindungPresentation of the invention

Der vorliegenden Erfindung liegt die Aufgabe zugrunde, die Stabilität der mageren Vormischverbrennung moderner Brenner der eingangs genannten Art, wie sie insbesondere in den Brennkammern von Gasturbinen eingesetzt werden, zu verbessern. Dabei ist eine essentielle Anhebung der Verbrennungstemperatur zu vermeiden, um weiterhin einen schadstoffarmen Betrieb zu gewährleisten.The object of the present invention is to improve the stability of lean premix combustion of modern burners of the type mentioned at the outset, as used in particular in the combustion chambers of gas turbines. An essential increase in the combustion temperature must be avoided in order to continue to ensure low-emission operation.

Erfindungsgemäss wird diese Aufgabe durch einen Vormischbrenner der im Anspruch 1 genannten Art gelöst. Vorteilhafte Ausführungsformen eines solchen Brenners geben die abhängigen Ansprüche wieder.According to the invention this object is achieved by a premix burner of the type mentioned in claim 1. Advantageous embodiments of such a burner give the dependent claims again.

Der Grundgedanke der Erfindung besteht darin, eine Mischstrecke eines Vormischbrenners mit einer sich zumindest annähernd vollständig über den Strömungsquerschnitt der Mischstrecke erstreckenden netzartigen Struktur auszurüsten.The basic idea of the invention is to equip a mixing section of a premix burner with a net-like structure extending at least approximately completely over the flow cross-section of the mixing section.

Nach einer bevorzugten Ausführungsform besteht die netzartige Struktur aus einem Drahtgewebe oder einer Mehrzahl zueinander beabstandet angeordneter Lagen von Drahtgewebe.
Als vorteilhaft hat sich dabei die Anordnung von fünf bis 100, insbesondere zehn bis 20, zumindest annähernd senkrecht zur Brennerlängsachse ausgerichteter Drahtgewebe erwiesen.According to a preferred embodiment, the net-like structure consists of a wire mesh or a plurality of mutually spaced layers of wire mesh.
In this case, the arrangement of five to 100, in particular ten to 20, at least approximately perpendicular to the longitudinal axis of the burner aligned wire mesh has proven to be advantageous.

Nach einer alternativen Ausführungsform besteht die netzartige Struktur aus einem in den Brennerhohlraum integrierten porösen Körper aus einem geschäumten Werkstoff.According to an alternative embodiment, the net-like structure consists of a porous body integrated in the burner cavity made of a foamed material.

Das netzartige Struktur ist vorzugsweise so zu auszulegen, dass sie keinen nennenswerten Druckverlust oder lokale Wirbelbildungen verursacht, die die Strömung in der Mischstrecke nachhaltig beeinträchtigen könnten.
Dies wird bei einer auf Drahtgewebe basierenden Ausführungsform dadurch gewährleistet, dass Drahtstärke und Maschenweite in ihrer Dimensionierung so aufeinander abgestimmt werden, dass eine möglichst grosse offene Siebfläche, vorzugsweise in einer Grössenordnung von über 90%, verbleibt.The reticulated structure is preferably to be designed so that it causes no appreciable pressure loss or local vortices, which could permanently affect the flow in the mixing section.
This is ensured in a wire mesh-based embodiment in that wire size and mesh size are matched in their dimensions to one another that the largest possible open screen surface, preferably in the order of more than 90%, remains.

Durch eine Variation der offenen Siebfläche über den Querschnitt bietet sich die Möglichkeit, die Strömungsverhältnisse in der Mischstrecke gezielt zu beeinflussen.
In diesem Zusammenhang hat es sich als vorteilhaft erwiesen, durch eine Erhöhung der offenen Siebfläche zur Randzone hin die Randströmung zu fördern.By varying the open screen area over the cross section, it is possible to specifically influence the flow conditions in the mixing section.
In this context, it has proved to be advantageous to promote the edge flow by increasing the open screen surface towards the edge zone.

Eine ausreichende Widerstandsfähigkeit gegen die herrschenden thermischen und chemischen Beanspruchungen weisen Materialien auf der Basis metallischer oder keramischer Werkstoffe auf, wobei metallischen Werkstoffen, insbesondere aluminiumhaltigen oder -behandelten Eisen- oder Stahllegierungen, im Hinblick auf eine Reduzierung der Brennkammerschwingungen der Vorzug eingeräumt wird.Sufficient resistance to the prevailing thermal and chemical stresses has materials based on metallic or ceramic materials, with preference given to metallic materials, in particular aluminum-containing or treated iron or steel alloys, with a view to reducing the combustion chamber vibrations.

In einer ergänzenden, besonders bevorzugten Ausführungsvariante ist die netzartige Struktur mit einer katalytisch wirksamen Oberfläche zur Unterstützung der Verbrennung ausgerüstet.In a supplementary, particularly preferred embodiment, the reticulated structure is equipped with a catalytically active surface to assist combustion.

Es hat sich gezeigt, dass durch eine sich über den gesamten Strömungsquerschnitt erstreckende netzartige Struktur das thermoakustische Verhalten des Brenners in positiver Weise verändert wird und in deren Folge eine Reduzierung der Schwingungsneigung des Brenners und damit eine Stabilisierung der Flamme zu verzeichnen sind. Diese positve Wirkung ist offensichtlich auf die Eigenschaft der Netzstruktur zurückzuführen, die sich in der Brennkammer ausbreitenden Schallwellen zu isolieren und zu dämpfen.
Druckwellen aus der Brennkammer in Richtung Gaseindüsung werden durch die Struktur zum Teil gedämpft und zum Teil isoliert, das heisst in einer geänderten Frequenz durchgelassen oder wieder abgestrahlt. Durch die wesentlich kürzere Lauflänge der zurück in die Brennkammer reflektierten Schallwellen wird die Anregung von Druckschwingungen in der Brennkammer zu anderen Frequenzbereichen hin verschoben und vermindert.
Material und Dimensionierung der Netzstruktur beeinflussen deren Dämpfungsund Isolationsverhalten.It has been shown that the thermoacoustic behavior of the material is due to a reticular structure extending over the entire flow cross section Burner is changed in a positive manner and as a result, a reduction in the vibration tendency of the burner and thus a stabilization of the flame are recorded. This positive effect is obviously due to the property of the mesh structure to isolate and attenuate sound waves propagating in the combustion chamber.
Pressure waves from the combustion chamber in the direction of gas injection are partially damped by the structure and partly isolated, that is, transmitted or radiated again in a changed frequency. Due to the much shorter length of the reflected back into the combustion chamber sound waves, the excitation of pressure oscillations in the combustion chamber is shifted to other frequency ranges and reduced.
Material and dimensioning of the network structure influence their damping and isolation behavior.

Dieser Stabilisierungseffekt der Netzstruktur wird zusätzlich verstärkt durch die oxidationsfördernde katalytische Wirksamkeit ihrer Oberfläche.This stabilizing effect of the network structure is additionally enhanced by the oxidation-promoting catalytic activity of its surface.

Aus den genannten Effekten resultieren Synergismen, die letztendlich die Löschgrenze zu tieferen Flammentemperaturen hin verschieben und damit bei gleicher Verbrennungstemperatur durch Vergrösserung des Abstandes zwischen Flammen- und Löschgrenzentemperatur die Flammenstabilität verbessern.The effects mentioned result in synergisms which ultimately shift the quenching limit to lower flame temperatures and thus improve the flame stability at the same combustion temperature by increasing the distance between flame and quenching boundary temperature.

Ein weiteres hervorzuhebendes Merkmal der Erfindung liegt darin, dass bestehende Brenner mit geringem Aufwand nachrüstbar sind.Another feature of the invention to be emphasized is that existing burners can be retrofitted with little effort.

Die Erfindung ist anwendbar in Vormischbrennern, welche aus dem eingangs zitierten Stand der Technik dem Fachmann als solche wohlbekannt und geläufig sind. Die Erfindung kann ohne weiteres mit allen in den dort zitierten Schriften offenbarten und den aus diesen Schriften weitergebildeten, dem Fachmann an sich geläufigen Brennerbauarten kombiniert werden, welche in der Vielgestalt der möglichen Ausführungsformen durch die in den Unteransprüchen angegebenen Vorzugsvarianten nur unvollständig reflektiert werden.The invention is applicable to premix burners, which are well known and familiar to those skilled in the art from the cited prior art. The invention can be readily combined with all disclosed in the writings cited therein and further developed from these writings, the skilled worker familiar burner types, which in the variety the possible embodiments are only partially reflected by the preferred variants specified in the subclaims.

Kurze Beschreibung der ZeichnungShort description of the drawing

Weitere Merkmale, Vorteile und Einzelheiten der Erfindung seien nachfolgend in einem Ausführungsbeispiel anhand schematischer Zeichnungen näher erläutert. Es werden nur die für die Erfindung wesentlichen Elemente dargestellt. Gleiche oder einander entsprechende Elemente figurieren unter den gleichen Bezugszeichen.Further features, advantages and details of the invention are explained in more detail below in an exemplary embodiment with reference to schematic drawings. Only the elements essential to the invention are shown. Identical or corresponding elements are shown under the same reference numerals.

Weg zur Ausführung der ErfindungWay to carry out the invention

Figur 1 gibt in stark schematisierter Weise das Wesen der Erfindung wieder. Anfänglich ist ein Drallerzeuger (100) wirksam, bei dem es sich um einen an sich bekannten Vormischbrenner handeln kann, wie er unter anderem in den in dieser Darlegung zitierten Veröffentlichungen beschrieben ist. Diese beispielhaft zitierten Brenner beruhen allesamt auf einem gemeinsamen Prinzip. Sie weisen einen sich axial erstreckenden, wenigstens annähernd rotationssymmetrischen Hohlraum (102) auf, in den über vorzugsweise parallel zur Längsachse (106) verlaufende Einlassschlitze (101) Verbrennungsluft einströmt. Durch die tangentiale Ausrichtung dieser mehr oder weniger schlitzförmigen Einlassöffnungen (101) erhält die Verbrennungsluft eine starke tangentiale Geschwindigkeitskomponente, aus der in Wechselwirkung mit der zur Brennermündung hin gerichteten axialen Komponente eine Drallströmung (103) durch den besagten Innenraum (102) resultiert. Die Anreicherung der Verbrennungsluft mit Brennstoff erfolgt alternativ oder ergänzend über Mittel (104) am Gehäusemantel nahe den Verbrennungslufteinlassschlitzen (101) und/oder über zentrale Zuführmittel (105) in der Brennerachse (106). FIG. 1 gives in a highly schematic way the essence of the invention again. Initially, a swirl generator (100) is operative, which may be a prior art premix burner, as described, inter alia, in the publications cited in this disclosure. These exemplarily quoted burners are all based on a common principle. They have an axially extending, at least approximately rotationally symmetrical cavity (102) into which combustion air flows via inlet slots (101) extending preferably parallel to the longitudinal axis (106). Due to the tangential orientation of these more or less slit-shaped inlet openings (101), the combustion air receives a strong tangential velocity component from which, in interaction with the axial direction towards the burner port, a swirling flow (103) results through said interior space (102). The enrichment of the combustion air with fuel takes place alternatively or additionally via means (104) on the housing jacket near the combustion air inlet slots (101) and / or via central feed means (105) in the burner axis (106).

Ferner ist diesen Brennern gemein, dass sich der Strömungsquerschnitt in Richtung zum Brenneraustritt hin stetig erweitert, um mit dem zunehmenden Massenstrom annähernd konstante Strömungsbedingungen aufrechtzuerhalten.
Obgleich die in dieser Schrift beispielhaft genannten Brenner auf dem geschilderten einheitlichen Prinzip beruhen, soll die Erfindung nicht auf diese besondere Gattung von Drallbrennern beschränkt sein, sondern jegliche Art von Vormischbrennern umfassen, deren Flammenstabilität bei gleichbleibend niedriger Schadstoffemission erhöht werden soll.Furthermore, these burners have in common that the flow cross-section in the direction of the burner outlet steadily widened in order to maintain approximately constant flow conditions with the increasing mass flow.
Although the burners exemplified in this document are based on the described unitary principle, the invention should not be restricted to this particular type of swirl burners, but should include any type of premix burners whose flame stability is to be increased while the emission of pollutants remains consistently low.

Erfindungsgemäss ist nun in einem stromabwärtigen Bereich des Brenners innerhalb der Mischstrecke (200) der Verbrennungsluft mit dem oder den Brennstoffen eine netzartige Struktur (201) angeordnet. Diese Netzstruktur (201) besteht aus mindestens einem den Strömungsquerschnitt (203) überspannenden Drahtgewebe (202).
Das oder die Drahtgewebe (202) weisen dabei eine Maschenweite in einem Bereich von 250 µm bis 1000 µm und eine Drahtstärke von 100 µm bis 500 µm auf. Um die Strömungsverhältnisse nicht in nachteiliger Weise zu beeinträchtigen, sind diese Parameter des Drahtgewebes (202) dabei so aufeinander abzustimmen, dass eine möglichst grosse offene Siebfläche, bevorzugt in einer Grössenordnung von über 90%, verbleibt. Bei Anordnung mehrerer den Strömungsquerschnitt (203) überspannender Drahtgewebe (202) sollte deren Abstand mindestens der Drahtstärke entsprechen.According to the invention, a net-like structure (201) is now arranged in a downstream region of the burner within the mixing section (200) of the combustion air with the fuel (s). This network structure (201) consists of at least one wire mesh (202) spanning the flow cross section (203).
The wire mesh or fabrics (202) have a mesh size in a range of 250 μm to 1000 μm and a wire thickness of 100 μm to 500 μm. In order not to adversely affect the flow conditions, these parameters of the wire mesh (202) are coordinated so that the largest possible open screen surface, preferably in the order of more than 90%, remains. If a plurality of wire meshes (202) spanning the flow cross-section (203) are arranged, their spacing should correspond at least to the wire thickness.

Wie an anderer Stelle bereits ausgeführt, übt die Netzstruktur (201) eine positive Wirkung auf das thermoakustische Verhalten des Brenners aus. Bekanntlich tritt bei Brennern der gattungsgemässen Art das nicht zu vernachlässigende Problem der Scherschichtbildung zwischen den sich in der Brennkammer befindlichen heissen Verbrennungsgasen und dem austretenden Gemisch aus Verbrennungsluft und Brennstoffen auf. Diese Scherschichten initiieren die sog. Kelvin-Helmholtz-Wellen, aus denen unter Betriebsbedingungen Reaktionsratenschwankungen und daraus resultierend thermoakustische Oszillationen von typischer Frequenz resultieren. Im Zusammenwirken mit den Eigenschwingungen des Aggregats erwachsen aus diesen thermoakustischen Oszillationen erhebliche Probleme für den Brennerbetrieb, die bis hin zum Erlöschen der mager betriebenen Flamme führen können.
Die sich in der Brennkammer (300) ausbreitenden Druckwellen treffen auf das Drahtgewebe (202) und regen es zu Schwingungen an. Dabei wird Schwingungsenergie teilweise von dem Gewebe (202) absorbiert und teilweise unter Verschiebung zu anderen Frequenzbereichen hin stromab in die Brennkammer (300) zurückgeworfen oder stromauf zur Gaseindüsung weitergeleitet.
Diese Dämpfungs- und Isolationseffekte des Gewebes (202) tragen zu einer Schwingungsstabilisierung des Verbrennungsprozesses bei.As already stated elsewhere, the network structure (201) has a positive effect on the thermoacoustic behavior of the burner. Known, occurs in burners of the generic type, the not negligible problem of shear layer formation between located in the combustion chamber hot combustion gases and the exiting mixture of combustion air and fuels. These shear layers initiate the so-called Kelvin-Helmholtz waves, from which, under operating conditions, reaction rate fluctuations and, as a result, thermoacoustic oscillations of typical frequency result. In conjunction with the natural vibrations of the unit arise from these thermoacoustic oscillations significant problems for the burner operation, which can lead to the extinction of the lean-burned flame.
The pressure waves propagating in the combustion chamber (300) strike the wire mesh (202) and cause it to vibrate. In this case, vibration energy is partially absorbed by the tissue (202) and partially reflected back to the other frequency ranges downstream in the combustion chamber (300) or forwarded upstream for gas injection.
These damping and insulating effects of the fabric (202) contribute to vibration stabilization of the combustion process.

Zur Unterstützung der Flammenstabilität kann nach einer ergänzenden Ausführungsvariante das Drahtgewebe (202) darüber hinaus eine den Verbrennungsvorgang fördernde katalytische Beschichtung aufweisen. Als Katalysator kommen die an sich bekannten Materialien in Frage, wie Edelmetalle (Pd, Pt, Rh usw.), Metalloxide (MnO2, NiO usw.), allein oder in Mischung mit einem Kokatalysator.To support the flame stability, the wire mesh (202) may additionally have a catalytic coating promoting the combustion process according to a supplementary embodiment variant. Suitable catalysts are the materials known per se, such as noble metals (Pd, Pt, Rh, etc.), metal oxides (MnO 2 , NiO, etc.), alone or in admixture with a cocatalyst.

Obgleich prinzipiell eine Vielzahl an sich bekannter hochtemperaturbeständiger metallischer und keramischer Werkstoffe für diesen Einsatzzweck in Frage kommen, werden metallische Werkstoffe den Anforderungen im Hinblick auf Schwingungsreduzierung und Trägereigenschaften für Katalysatoren am besten gerecht. Gute Ergebnisse wurden mit Materialien auf der Basis aluminiumhaltiger oder aluminiumbehandelter Eisen- oder Stahllegierungen erzielt. Enthalten diese Materialien einen genügend hohen Anteil an Aluminium, so bilden sich bei der Oxidation auf der Oberfläche Aluminium-Whisker aus, die eine rauhe und chemisch aktive Oberfläche entstehen lassen, welche sich sehr gut als Träger für ein katalytisch wirksames Überzugsmaterial eignet.
Nach einer günstigen Ausführungsvariante ist das Stahlgewebe mit einem porösen keramischen Material überzogen werden, welches das Katalysatormaterial enthält.Although in principle a variety of known high-temperature resistant metallic and ceramic materials for this purpose come into question, metallic materials are the requirements in terms of vibration reduction and carrier properties for catalysts best meet. Good results have been achieved with materials based on aluminum-containing or aluminum-treated iron or steel alloys. If these materials contain a sufficiently high proportion of aluminum, oxidation on the surface forms aluminum whiskers which give rise to a rough and chemically active surface, which is very suitable as a carrier for a catalytically active coating material.
According to a favorable embodiment, the steel mesh is coated with a porous ceramic material containing the catalyst material.

Die Verbindung der Netzstruktur (201) mit der umgebenden Gehäusewandung (205) kann in jeder geeigneten Weise erfolgen. In Abhängigkeit von den konkreten Bedingungen des Anwendungsfalls erschliesst sich dem Fachmann eine Reihe von Möglichkeiten. Zwei günstige Ausführungsvarianten sind anhand der Ausführungsformen gemäss Fig. 2 und 3 erläutert.The connection of the net structure (201) to the surrounding housing wall (205) can be made in any suitable way. Depending on the specific conditions of the application, a number of possibilities are open to the person skilled in the art. Two favorable embodiments are based on the embodiments according to Fig. 2 and 3 explained.

Die Fig.2 und 3 zeigen die Realisierung der Erfindung anhand eines Vormischbrenners, wie er aus der EP 0 780 629 bekanntgeworden ist.
Der Brenner besteht im wesentlichen aus einem Drallerzeuger (100) für einen Verbrennungsluftstrom, welcher aus wenigstens zwei kegelförmigen Teilkörpern gebildet ist, die mit ihren Achsen gegenüber der Brennerachse (106) wie auch gegenseitig lateral versetzt angeordnet sind. Aufgrund dieses lateralen Versatzes der Teilkörper sind zwischen den Teilkörpern tangentiale Einlassschlitze (101) ausgebildet. Durch die tangentialen Einlassschlitze (101) strömt ein Verbrennungsluftstrom im wesentlichen tangential in den Innenraum (102) des Drallerzeugers (100) ein. Im Inneren des Drallerzeugers (100) bildet sich in Folge eine Drallströmung (103) aus, deren axiale Strömungskomponente zur stromabwärtigen Mündung des Drallerzeugers (100) hin weist. Die Teilkörper sind am stromabwärtigen Ende des Drallerzeugers (100) auf einem Haltering (107) befestigt. In dem Haltering (107) ist weiterhin ein Übergangselement (108) angeordnet. Dieses ist mit einer Anzahl von Übergangskanälen (109) versehen, welche die im Drallerzeuger (100) aus der einströmenden Verbrennungsluft generierte Drallströmung (103) ohne plötzliche Querschnittsänderungen in die Mischstrecke (200) überführen. Diese Mischstrecke (200) dient der Herstellung eines möglichst homogenen Gemischs aus Verbrennungsluft und Brennstoffen verschiedener Art. Die Mischstrecke (200) ermöglicht eine verlustfreie Strömungsführung, ohne dass sich eine Rückströmzone ausbilden kann. Über die Länge der Mischstrecke (200) kann auf die Mischungsgüte für alle Brennstoffarten Einfluss genommen werden. Am stromabwärtigen Ende der Mischstrecke (200) schliesst sich die Brennkammer (300) an, wobei an der Übergangsstelle ein Querschnittssprung vorhanden ist, hinter welchem sich eine zentrale Rückströmzone (301) ausbildet, welche die Eigenschaften eines Flammenhalters aufweist. Im Bereich der Rückströmzone (301) kann sich eine Flamme aus dem vorgemischten Brennstoff-/Luftgemisch stabilisieren. Aufgrund der guten Vormischung von Luft und Brennstoff kann diese Flamme mit einem recht hohen Luftüberschuss - in der Regel findet man am Brenner selbst Luftzahlen von zwei und darüber - betrieben werden. Aufgrund der vergleichsweise kühlen Verbrennungstemperaturen können mit derartigen Brennern sehr geringe Stickoxidemissionen ohne aufwendige Abgasnachbehandlung erreicht werden. Aufgrund der guten Vormischung des Brennstoffs mit der Verbrennungsluft und einer guten Flammenstabilisierung durch die Rückströmzone (301) kommt es weiterhin trotz der geringen Verbrennungstemperaturen zu einem guten Ausbrand und damit auch zu geringen Emissionen an Teil- und Unverbranntem, insbesondere an Kohlenmonoxid und unverbrannten Kohlenwasserstoffen, aber auch an anderen unerwünschten organischen Verbindungen.The Fig.2 and 3 show the realization of the invention with reference to a premix burner, as he from the EP 0 780 629 has become known.
The burner consists essentially of a swirl generator (100) for a combustion air stream, which is formed from at least two conical body parts, which are arranged with their axes relative to the burner axis (106) as well as mutually laterally offset. Due to this lateral offset of the partial bodies, tangential inlet slots (101) are formed between the partial bodies. Through the tangential inlet slots (101) flows a combustion air flow substantially tangentially into the interior (102) of the swirl generator (100). In the interior of the swirl generator (100), a swirling flow (103) is formed in succession, the axial flow component of which points towards the downstream mouth of the swirl generator (100). The split bodies are attached to a retaining ring (107) at the downstream end of the swirl generator (100). In the retaining ring (107), a transition element (108) is further arranged. This is provided with a number of transition channels (109) which convert the swirl flow (103) generated in the swirl generator (100) from the incoming combustion air into the mixing section (200) without sudden changes in cross section. This mixing section (200) is used to produce a homogeneous mixture of combustion air and fuels of various kinds. The mixing section (200) allows a lossless flow control, without a backflow can form. Over the length of the mixing section (200) can influence the mix quality for all fuel types. At the downstream end of the mixing section (200), the combustion chamber (300) closes, wherein at the transition point a cross-sectional jump is present, behind which a central Rückströmzone (301) is formed, which has the properties of a flame holder. In the region of the return flow zone (301), a flame from the premixed fuel / air mixture can stabilize. Due to the good premixing of air and fuel, this flame can be operated with a fairly high excess air - usually you will find on the burner itself air figures of two and above. Due to the comparatively cool combustion temperatures, very low nitrogen oxide emissions can be achieved with such burners without expensive exhaust aftertreatment. Due to the good premixing of the fuel with the combustion air and a good flame stabilization by the Rückströmzone (301) continues to come despite the low combustion temperatures to a good burnout and thus low emissions of partial and unburned, in particular carbon monoxide and unburned hydrocarbons, but also on other unwanted organic compounds.

Über den Strömungsquerschnitt (203) der Mischstrecke (200) herrscht ein Geschwindigkeitsprofil mit einem ausgeprägten Maximum auf der Mittelachse (106). In Richtung auf die Randzone (204) ist ein signifikanter Rückgang der Axialgeschwindigkeit zu verzeichnen. Um die Gefahr einer Rückzündung auch für diesen Bereich (204) sicher auszuschliessen, sieht der Stand der Technik eine Anzahl von Durchtrittskanälen (210) vor, durch welche eine zusätzliche Luftmenge in die Mischstrecke (200) eingeführt wird, und zwar dergestalt, dass sie entlang der strömungsbegrenzenden Wand (205) filmbildend eine Erhöhung der axialen Strömungsgeschwindigkeit in dieser Randzone (204) induziert.
Gemäss einer ergänzenden Ausführungsform der Erfindung, dargestellt in Fig.4b, besitzt das Drahtgewebe (202) im Bereich dieser Randzone (204) eine gegenüber dem radial inneren Bereich erhöhte offene Siebfläche. Diese Massnahme fördert die Randströmung und trägt damit zu einer Stärkung der Ringstabilisation der Rückströmzone (301) und zu einer Verringerung der Gefahr einer Rückzündung bei.There is a velocity profile with a pronounced maximum on the central axis (106) via the flow cross section (203) of the mixing section (200). In the direction of the edge zone (204), a significant decrease in the axial velocity can be observed. In order to safely exclude the risk of backfire also for this area (204), the prior art provides a number of passageways (210) through which an additional amount of air is introduced into the mixing section (200) in such a way that they pass along the flow-limiting wall (205) induces a film-forming increase in the axial flow velocity in this edge zone (204).
According to a supplementary embodiment of the invention, shown in FIG 4b , has the wire fabric (202) in the region of this edge zone (204) has a relation to the radially inner region increased open screen area. This measure promotes the edge flow and thus contributes to a strengthening of the ring stabilization of the backflow zone (301) and to a reduction in the risk of backfire.

Zum Zwecke der Befestigung der Drahtgewebe (202) ist das die Mischstrecke (200) umgebende Gehäuse (205) segmentartig aus einzelnen Rohrschüssen (206) zusammengesetzt, an deren Verbindungsstellen (207) die Drahtgewebe (202) eingebunden sind. Diese Variante, schematisch wiedergegeben in Fig.2, zeichnet sich durch einen problemlosen Austausch verbrauchter Gewebe (202) aus.
Eine alternative Ausführungsform, dargestellt in Fig.3, besteht darin, das Gehäuse (205) aus einzelnen Segmenten (206) zusammenzusetzen, wobei wenigstens ein Segment (208) in einem vorgeschalteten Arbeitsprozess mit den Drahtgeweben (202) ausgerüstet wurde.For the purpose of attaching the wire mesh (202), the housing (205) surrounding the mixing section (200) is segmentally composed of individual tube sections (206), at the connection points (207) of which the wire meshes (202) are incorporated. This variant, shown schematically in Fig.2 , characterized by a smooth exchange of used tissues (202).
An alternative embodiment, shown in FIG Figure 3 consists of assembling the housing (205) of individual segments (206), wherein at least one segment (208) was equipped with the wire meshes (202) in a preceding working process.

Die oben dargestellten Ausführungsbeispiele sind keinesfalls in einem für die Erfindung einschränkenden Sinne zu verstehen. Im Gegenteil, sind sie instruktiv und als Abriss der Mannigfaltigkeit der im Rahmen der in den Ansprüchen gekennzeichneten Erfindung möglichen Ausführungsformen zu verstehen.The exemplary embodiments presented above are by no means to be understood in a sense restricting the invention. On the contrary, they are instructive and to be understood as an outline of the diversity of possible embodiments within the scope of the invention as claimed.

Die vorstehenden Ausführungen dienen dem Fachmann als illustrative Beispiele für die Vielzahl möglicher Ausführungsformen des erfindungsgemässen und in den Ansprüchen gekennzeichneten Brenners und für dessen vorteilhafte Betriebsweisen: Sie sind nicht beschränkend zu verstehen.The above explanations serve to illustrate to the skilled person as illustrative examples of the multiplicity of possible embodiments of the burner according to the invention and characterized in the claims and for its advantageous modes of operation: they are not to be understood as limiting.

BezugszeichenlisteLIST OF REFERENCE NUMBERS

100100
Drallerzeugerswirl generator
101101
tangentiale Einlassschlitzetangential inlet slots
102102
Innenraum des DrallerzeugersInterior of the swirl generator
103103
Drallströmungswirl flow
104104
Mittel zur BrennstoffeindüsungFuel injection means
105105
zentrale Brennstoffdüsecentral fuel nozzle
106106
BrennerlängsachseBrenner axis
107107
Halteringretaining ring
108108
ÜbergangselementTransition element
109109
ÜbergangskanäleTransition ducts
200200
Mischstreckemixing section
201201
netzartige Strukturnet-like structure
202202
Drahtgewebewire cloth
203203
StrömungsquerschnittFlow area
204204
Randzoneborder zone
205205
Mischstrecke (200) umgebendes GehäuseMixing section (200) surrounding housing
206206
Gehäuseschuss, -segmentHousing section, segment
207207
Verbindungsstelle zwischen den GehäuseschüssenJoint between the housing shots
208208
mit netzartiger Struktur (201) ausgerüstetes Gehäusesegmenthousing segment equipped with reticulated structure (201)
209209
Austrittsgeometrie der Mischstrecke (200)Exit geometry of the mixing section (200)
210210
DurchtrittskanälePassageways
300300
Brennkammercombustion chamber
301301
Rückströmzonebackflow
302302
Brennkammerwandcombustion chamber wall

Claims (20)

  1. Premixing burner with high flame stability for use in a heat generator, preferably a gas turbine, essentially comprising a swirl generator (100) with means (101) for tangential introduction of a combustion air flow into an internal area (102) of the swirl generator (100) as well as means (104) for introduction of at least one fuel into the combustion air flow forming a swirl flow with an axial movement component towards the burner mouth and a mixing path (200) which is positioned downstream from the swirl generator (100), for premixing of the combustion air with the at least one fuel, characterized in that a mesh-like structure (201) which extends at least approximately over the entire flow cross section (203) is arranged within the mixing path (200).
  2. Premixing burner according to Claim 1, characterized in that the mesh-like structure (201) is composed of one or more layers, which are arranged separated from one another, of individual wire mesh (202).
  3. Premixing burner according to Claim 1 or 2, characterized in that the mesh-like structure (201) has a mesh width of 250 µm to 1000 µm, and a wire thickness of 100 µm to 500 µm.
  4. Premixing burner according to Claim 2, characterized in that the mesh-like structure (201) comprises five to 100, preferably 10 to 20, wire meshes (202) which are separated from one another and are aligned at least approximately at right angles to the burner longitudinal axis (106).
  5. Premixing burner according to Claim 1, characterized in that the mesh-like structure (201) is a porous body composed of a foamed metal material or of a foamed ceramic material.
  6. Premixing burner according to Claim 1, characterized in that the mesh-like structure (201) is arranged close to the outlet geometry (209) of the mixing path (200).
  7. Premixing burner according to Claim 2, characterized in that the individual wire meshes (202) are arranged essentially parallel and with uniform distances between them.
  8. Premixing burner according to Claim 7, characterized in that the axial distance between the individual wire meshes (202) corresponds at least to the wire thickness.
  9. Premixing burner according to Claim 1, characterized in that the mesh-like structure (201) is based on a high-temperature-resistant metallic material.
  10. Premixing burner according to Claim 9, characterized in that the mesh-like structure (201) is based on a steel alloy.
  11. Premixing burner according to Claim 10, characterized in that the mesh-like structure (201) is composed of a steel alloy containing aluminium.
  12. Premixing burner according to Claim 1, characterized in that the mesh-like structure (201) is based on a ceramic material.
  13. Premixing burner according to Claim 12, characterized in that the mesh-like structure (201) is based on a silicon, zirconium or aluminium compound.
  14. Premixing burner according to Claim 1, characterized in that at least one wire mesh (202) of the mesh-like structure (201) has a catalytically active surface.
  15. Premixing burner according to Claim 14, characterized in that the wire mesh is composed of a steel alloy and has a porous ceramic coating equipped with a catalytic material.
  16. Premixing burner according to Claim 1, characterized in that the housing (205) which surrounds the mixing path (200) is composed of individual fillings (206), and one or more layers of wire mesh (202) of the mesh structure (201) is or are included in an interlocking or force-fitting manner in the connecting points (207) between the individual fillings (206).
  17. Premixing burner according to Claim 1, characterized in that the mesh structure (201) is integrated in a replaceable filling (208) of the housing (205) which surrounds the mixing path (200).
  18. Premixing burner according to Claim 1, characterized in that the open sieve area of the mesh-like structure (201) increases radially from the inside outwards over the flow cross section (203) of the mixing path (200).
  19. Premixing burner according to Claim 18, characterized in that the mesh-like structure (201) has an annular edge area (204) with an open sieve area which is larger than the inner area.
  20. Premixing burner according to one of Claims 1 to 19, for operation in a combustion chamber of a gas turbine installation.
EP02405615A 2001-07-26 2002-07-18 Premix burner with high flame stability Expired - Lifetime EP1279898B1 (en)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
DE10136313 2001-07-26
DE10136313A DE10136313A1 (en) 2001-07-26 2001-07-26 Premixing burner comprises a twisting arrangement having tangential inlets for introducing a combustion air stream into the inner chamber of the twisting arrangement, and devices for introducing a fuel into the combustion air stream
DE10164097A DE10164097A1 (en) 2001-12-24 2001-12-24 Premixing burner comprises a twisting arrangement having tangential inlets for introducing a combustion air stream into the inner chamber of the twisting arrangement, and devices for introducing a fuel into the combustion air stream
DE10164097 2001-12-24

Publications (3)

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EP1279898A2 EP1279898A2 (en) 2003-01-29
EP1279898A3 EP1279898A3 (en) 2003-04-16
EP1279898B1 true EP1279898B1 (en) 2008-09-10

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EP1279898A2 (en) 2003-01-29
US20030031972A1 (en) 2003-02-13
US6834504B2 (en) 2004-12-28
EP1279898A3 (en) 2003-04-16
DE50212753D1 (en) 2008-10-23

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