EP0391858B1 - Apparatus for flue gas recirculation in oil and gas burners - Google Patents

Apparatus for flue gas recirculation in oil and gas burners Download PDF

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Publication number
EP0391858B1
EP0391858B1 EP90810274A EP90810274A EP0391858B1 EP 0391858 B1 EP0391858 B1 EP 0391858B1 EP 90810274 A EP90810274 A EP 90810274A EP 90810274 A EP90810274 A EP 90810274A EP 0391858 B1 EP0391858 B1 EP 0391858B1
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Prior art keywords
tube
flame
adapter
pipe
recirculation
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EP90810274A
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German (de)
French (fr)
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EP0391858A1 (en
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Benno Balsiger
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23L—SUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERAL ; VALVES OR DAMPERS SPECIALLY ADAPTED FOR CONTROLLING AIR SUPPLY OR DRAUGHT IN COMBUSTION APPARATUS; INDUCING DRAUGHT IN COMBUSTION APPARATUS; TOPS FOR CHIMNEYS OR VENTILATING SHAFTS; TERMINALS FOR FLUES
    • F23L7/00—Supplying non-combustible liquids or gases, other than air, to the fire, e.g. oxygen, steam
    • 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
    • F23C9/08—Combustion apparatus characterised by arrangements for returning combustion products or flue gases to the combustion chamber for reducing temperature in combustion chamber, e.g. for protecting walls of 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

Definitions

  • the present invention relates to a device according to the preamble of patent claim 1.
  • nitrogen oxides NO x contribute to the formation of acid rain and ozone.
  • nitrogen monoxide NO is primarily responsible for the formation of ozone.
  • the emission of nitrogen oxides correlates directly with the level of the flame temperature.
  • the air components nitrogen and oxygen combine according to the so-called Zeldovich mechanism at temperatures above 1200 ° C to NO x .
  • exhaust gas recirculation is used to reduce pollutants.
  • the fuel is injected into the flame space through a central opening of a disk-shaped stabilizer which also acts as a baffle plate and is also referred to as a baffle plate.
  • Combustion air is supplied through a combustion air pipe around the fuel supply in front of the stabilizer. This passes into a flame tube in the area of the stabilizer.
  • the flue gas is added from the fuel supply behind the stabilizer with an adapter that encloses the combustion air supply in a sleeve-like manner.
  • the flame space is often divided into complicated chambered combustion zones provided with microprocessor-controlled flap mechanisms.
  • the existing burners have to be replaced by complicated, more expensive burners. In this way, not only retrofitting, but also maintenance is complicated and costly.
  • US Pat. No. 3,868,211 describes a device for recirculating flue gases in burners, comprising a burner which has a fuel supply provided with a fuel nozzle, a combustion air pipe and a flame pipe, a flame chamber to which an exhaust pipe is connected, and one connected to the exhaust pipe and leading into an adapter flue gas return duct, in which the adapter housing (17), adapter pipe and adapter pipe shoulder (84) at least partially surround the flame pipe (81, 104).
  • this device Since this device is intended to reduce nitrogen oxide emissions as well as carbon monoxide, carbon and other particles of the exhaust gases, a complicated stratified charge system is provided in which an internal combustion zone with air deficiency and exhaust gases and low combustion temperatures to avoid the formation of nitrogen oxides, and in one outer combustion zone with excess air for the complete oxidation of carbon, carbon monoxide and other particles. Due to the complicated process, such a device is of complex construction and can therefore be used in an economically sensible manner at most in industrial burners.
  • the addition of the flue gases only lowers the flame temperature even in small burners to such an extent that the nitrogen oxide emissions are reduced without the complete combustion of carbon and carbon monoxide being prevented.
  • the slidable adapter tube in connection with the inlet openings in the flame tube enables the flue gas flows in and around the flame tube to be changed in the simplest way.
  • FIG. 1 shows a schematic representation of a burner for solid, liquid and gaseous fuels with an exhaust gas recirculation system according to the invention.
  • Fuel is passed through a fuel pipe 1 via a fuel nozzle 1a injected into the flame space 6 and thus generates a flame F.
  • a mostly circular disk is arranged on the fuel nozzle 1 a by means of flanges 4 a, which acts as a stabilizer for the flame and is referred to below as stabilizer 4.
  • the combustion air tube 2 merges into the flame tube 3, which has a conically shaped shoulder 3a in front of the stabilizer 4.
  • the exhaust gases are discharged through an exhaust pipe 7 into a chimney, not shown in the figure.
  • An exhaust gas recirculation duct 8 leads from the exhaust pipe 7 into an adapter housing 10.
  • An exhaust gas blower 9 is provided in the exhaust gas recirculation duct 8 for better recirculation of the exhaust gas. Furthermore, the exhaust gas flow can be regulated with a valve 16. From the adapter housing 10 leads an adapter tube part 12a which surrounds the combustion air tube 2 and which, via a conically increasing adapter tube shoulder 11, transfers into an adapter tube part 12b which is provided with a larger diameter and surrounds the flame tube 3.
  • the adapter tube 12a, 12b is mounted in the adapter housing 10 and at the entry point into the flame space 6 so as to be longitudinally displaceable.
  • the shoulder 3a of the flame tube 3 is provided with openings 3b arranged in a ring, the function of which is explained below.
  • the openings could also optionally be provided in the combustion air tube 2 in the area of the adapter housing 10 or adapter tube part 12a.
  • the shoulders can also be arranged in the adapter tube 12a, 12b and in the flame tube (3,3a) or in the combustion air tube 2 in front of the stabilizer or, if no stabilizer is used, in front of the mouth of the fuel nozzle 1a.
  • the fuel is injected into the flame chamber 6 through the fuel pipe 1.
  • combustion air can flow into the flame chamber 6 through the combustion air pipe 2, which surrounds the fuel pipe.
  • the exhaust gases resulting from the combustion process are discharged into the chimney via the exhaust pipe 7.
  • a part of the exhaust gases - usually about 20% at full load - are conducted into the adapter housing 10 via the exhaust gas recirculation channel 8.
  • the exhaust gas fan 9 supports the return of the exhaust gases.
  • Part of the exhaust gases 15 flows through the annular space formed between the flame tube 3 and adapter tube 12a, 12b and the other part passes through the openings 3b of the shoulder 3a of the flame tube 3.
  • the openings are in arranged in such a way that the exhaust gas component flowing in here passes around the stabilizer 4 into the flame chamber 6.
  • the ratio of the exhaust gas component 14 flowing into the flame tube 3 to the exhaust gas component 15 flowing around the flame tube 3 must be varied in order to achieve an optimal result.
  • movable or rotatable (e.g. ring-shaped) regulating diaphragms can also be provided, optionally as additional regulating devices, with which the clearing of the openings 3b of the flame tube shoulder 3a can be changed.
  • an activator In the case of such an activator, a small part of the combustion air is passed through an aqueous electrolyte solution using a metering pump and is supplied to the combustion air and / or exhaust gases in the form of an aerosol.
  • the electrolytic solution contains alkali and / or alkaline earth salts and optionally 2 to 12%, preferably about 5%, methyl alcohol.
  • the air or exhaust gas activated in this way is mixed with aerosol particles which evaporate in the flame space and dissociate into ions. The ions are involved in the oxidation process, accelerate the ignition and significantly reduce the formation of soot, CO and other pollutants. At this point it should be pointed out that such an activator contains no heavy metals.
  • a recirculation ring 13 can be attached to the stabilizer 4 in front of the fuel nozzle 1a, as shown in FIG. This can be fastened to the stabilizer 4 by means of a holder 13a and has a diameter which is smaller than half the diameter of the stabilizer 4.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Combustion Of Fluid Fuel (AREA)
  • Incineration Of Waste (AREA)

Abstract

The invention serves to reduce the formation of nitrogen oxides in the operation of burners for solid, liquid and gaseous fuels with the aid of flue gas recirculation. In this connection, the flue gases are admitted into a combustion chamber (6), through openings (3b) provided in the region of a stabiliser (4), via a flame pipe and optionally also around the flame pipe (3). Preferably, both the combustion air and the waste gases are activated with an activator aerosol. The recirculation of the waste gases takes place via a longitudinally displaceable adaptor pipe (12a, 12b) and adaptor-pipe shoulder (11), which surrounds the flame pipe (3) at least partially. Regulation of the waste gas flows (14, 15) takes place by means of displacing the adaptor pipe (12a, 12b) and the adaptor pipe shoulder (11). <IMAGE>

Description

Die vorliegende Erfindung betrifft eine Vorrichtung gemäss Oberbegriff des Patentanspruchs 1.The present invention relates to a device according to the preamble of patent claim 1.

Ein steigendes Umweltbewusstsein führt zu einer ständigen Verschärfung der Vorschriften hinsichtlich Schadstoffausstoss bei Oel- und Gasbrennern. Ein besonderes Augenmerk richtet sich auf die Abgabe von Stickoxiden NOx. Diese tragen u.a. zur Bildung von saurem Regen und Ozon bei. Für die Entstehung von Ozon ist beispielsweise in erster Linie Stickstoffmonoxid NO verantwortlich. Der Ausstoss an Stickoxiden korreliert direkt mit der Höhe der Flammtemperatur. Die Luftkomponenten Stickstoff und Sauerstoff verbinden sich nach dem sog. Zeldovich-Mechanismus bei Temperaturen oberhalb von 1200°C zu NOx.Increasing environmental awareness leads to a constant tightening of regulations regarding pollutant emissions from oil and gas burners. Particular attention is paid to the release of nitrogen oxides NO x . These contribute to the formation of acid rain and ozone. For example, nitrogen monoxide NO is primarily responsible for the formation of ozone. The emission of nitrogen oxides correlates directly with the level of the flame temperature. The air components nitrogen and oxygen combine according to the so-called Zeldovich mechanism at temperatures above 1200 ° C to NO x .

Aufgrund dieser Erkenntnis werden zur Schadstoffreduktion Abgasrückführungen eingesetzt. Hierdurch wird einerseits eine Flammkühlung bewirkt und andererseits durch Beimischung von inertem Abgas der Sauerstoffpartialdruck minimiert, welcher für die Bildung von NOx Voraussetzung ist.Based on this knowledge, exhaust gas recirculation is used to reduce pollutants. On the one hand, this results in flame cooling and, on the other hand, the addition of inert exhaust gas minimizes the oxygen partial pressure, which is a prerequisite for the formation of NO x .

Bei den handelsüblichen Brennern wird der Brennstoff durch eine zentrale Oeffnung eines als Stauelement wirkenden auch als Stauscheibe bezeichneten, scheibenförmigen Stabilisators in den Flammraum injiziert. Um die Brennstoffzufuhr herum wird noch vor dem Stabilisator durch ein Verbrennungsluftrohr Verbrennungsluft zugeführt. Dieses geht im Bereiche des Stabilisators in ein Flammrohr über. Die Beimengung von Rauchgas erfolgt von der Brennstoffzufuhr aus gesehen hinter dem Stabilisator mit einem die Verbrennungsluftzufuhr manschettenförmig umschliessenden Adapter. Zur Verbesserung der Wirkung wird der Flammraum vielfach in komplizierte, mit mikroprozessorgesteuerten Klappenmechanismen versehene abgekammerte Brennzonen aufgeteilt. Infolgedessen müssen beim Einbau von Abgasrückführungen die vorhandenen Brenner durch komplizierte, teurere Brenner ersetzt werden. Auf diese Weise wird nicht nur die Umrüstung, sondern auch deren Wartung kompliziert und kostspielig.In the case of the commercially available burners, the fuel is injected into the flame space through a central opening of a disk-shaped stabilizer which also acts as a baffle plate and is also referred to as a baffle plate. Combustion air is supplied through a combustion air pipe around the fuel supply in front of the stabilizer. This passes into a flame tube in the area of the stabilizer. The flue gas is added from the fuel supply behind the stabilizer with an adapter that encloses the combustion air supply in a sleeve-like manner. In order to improve the effect, the flame space is often divided into complicated chambered combustion zones provided with microprocessor-controlled flap mechanisms. As a result, when installing exhaust gas recirculation systems, the existing burners have to be replaced by complicated, more expensive burners. In this way, not only retrofitting, but also maintenance is complicated and costly.

In der US-Patentschrift 3 868 211 wird eine Vorrichtung zur Rückführung von Rauchgasen bei Brennern beschrieben, die einen Brenner, der eine mit einer Brennstoffdüse versehene Brennstoffzufuhr, ein Verbrennungsluftrohr und ein Flammrohr aufweist, einen Flammraum, an den ein Abgasrohr angeschlossen ist, und einen mit dem Abgasrohr verbundenen und in einen Adapter mündenden Rauchgasrückführkanal, bei dem das Adaptergehäuse (17), Adapaterrohr und Adapterrohrschulter (84) das Flammrohr (81,104) wenigsten teilweise umschliessen, aufweist.US Pat. No. 3,868,211 describes a device for recirculating flue gases in burners, comprising a burner which has a fuel supply provided with a fuel nozzle, a combustion air pipe and a flame pipe, a flame chamber to which an exhaust pipe is connected, and one connected to the exhaust pipe and leading into an adapter flue gas return duct, in which the adapter housing (17), adapter pipe and adapter pipe shoulder (84) at least partially surround the flame pipe (81, 104).

Da mit dieser Vorrichtung sowohl der Stickoxidausstoss als auch Kohlenmonoxid, Kohlenstoff und andere Partikel der Abgase reduziert werden soll, ist ein kompliziertes Schichtladungssystem vorgesehen, in dem in einer inneren Verbrennungszone mit Luftunterschuss und Abgasen und geringen Verbrennungstemperaturen zur Vermeidung der Entstehung von Stickoxiden, und in einer äusseren Verbrennungszone mit Luftüberschuss zur möglichst vollständigen Oxidation von Kohlenstoff, Kohlenmonoxid und sonstiger Partikel gearbeitet wird. Durch den komplizierten Vorgang bedingt, ist eine solche Vorrichtung aufwendig gebaut und kann deshalb ökonomisch sinnvoll höchstens bei Industriebrennern eingesetzt werden.Since this device is intended to reduce nitrogen oxide emissions as well as carbon monoxide, carbon and other particles of the exhaust gases, a complicated stratified charge system is provided in which an internal combustion zone with air deficiency and exhaust gases and low combustion temperatures to avoid the formation of nitrogen oxides, and in one outer combustion zone with excess air for the complete oxidation of carbon, carbon monoxide and other particles. Due to the complicated process, such a device is of complex construction and can therefore be used in an economically sensible manner at most in industrial burners.

Gemäss der vorliegenden Erfindung wird hingegen durch die Beimischung der Rauchgase die Flammentemperatur auch bei Kleinbrennern nur so weit vermindert, dass der Stickoxidausstoss vermindert wird, ohne dass die vollständige Verbrennung von Kohlenstoff und Kohlenmonoxid verhindert wird.According to the present invention, however, the addition of the flue gases only lowers the flame temperature even in small burners to such an extent that the nitrogen oxide emissions are reduced without the complete combustion of carbon and carbon monoxide being prevented.

Es ist Aufgabe der Erfindung, eine Vorrichtung zu beschreiben, mit welcher der Stickoxidausstoss bei den meisten bekannten Gas- und Oelbrennern mit einfachen Mitteln wirksam reduziert werden kann.It is the object of the invention to describe a device with which the nitrogen oxide emissions in most known gas and oil burners can be effectively reduced by simple means.

Die Lösung der Aufgabe ergibt sich aus dem kennzeichnenden Teil der Patentansprüche 1 - 6.The solution to the problem results from the characterizing part of claims 1-6.

Das verschiebbare Adapterrohr in Verbindung mit den Einlassöffnungen im Flammrohr ermöglicht die Aenderung der Rauchgasströme im und um das Flammrohr herum in einfachster Weise.The slidable adapter tube in connection with the inlet openings in the flame tube enables the flue gas flows in and around the flame tube to be changed in the simplest way.

Die Ergänzung mit einem Aktivator, der keinerlei Sehwermetalle enthält, erlaubt eine weitere Senkung auch der übrigen Schadstoffe.The addition of an activator that does not contain any visual metals allows a further reduction of the other pollutants.

Nachstehend wird die Erfindung anhand einer Zeichnung beispielsweise näher erläutert. Es zeigen:

Fig. 1
eine schematische Darstellung eines Brenners mit einem erfindungsgemässen Abgasrückführsystem;
Fig. 2
eine Detaildarstellung des Adapterrohres in einer extremen Position;
Fig. 3
einen Stabilisator mit Rezirkulationsring.
The invention is explained in more detail below with reference to a drawing, for example. Show it:
Fig. 1
a schematic representation of a burner with an exhaust gas recirculation system according to the invention;
Fig. 2
a detailed view of the adapter tube in an extreme position;
Fig. 3
a stabilizer with a recirculation ring.

Figur 1 zeigt eine schematische Darstellung eines Brenners für feste, flüssige und gasförmige Brennstoffe mit einem erfindungsgemässen Abgasrückführungssystem. Durch ein Brennstoffrohr 1 wird Brennstoff über eine Brennstoffdüse 1a in den Flammraum 6 injiziert und so eine Flamme F erzeugt. An der Brennstoffdüse 1a ist mittels Flanschen 4a eine zumeist kreisförmige Scheibe angeordnet, welche als Stabilisator für die Flamme wirkt und nachstehend als Stabilisator 4 bezeichnet wird. Das Verbrennungsluftrohr 2 geht in das Flammrohr 3 über, welches vor dem Stabilisator 4 eine konisch geformte Schulter 3a aufweist. Die Abgase werden über ein Abgasrohr 7 in einen in der Figur nicht dargestellten Kamin entlassen. Vom Abgasrohr 7 führt ein Abgasrückführkanal 8 in ein Adaptergehäuse 10. Im Abgasrückführkanal 8 ist zur besseren Rückförderung des Abgases ein Abgasgebläse 9 vorgesehen. Ferner kann der Abgasstrom mit einem Ventil 16 geregelt werden. Aus dem Adaptergehäuse 10 führt ein das Verbrennungsluftrohr 2 umschliessendes Adapterrohrteil 12a, das über eine konisch ansteigende Adapterrohrschulter 11 in einen mit einem grösseren Durchmesser versehenen, das Flammrohr 3 umschliessenden Adapterrohrteil 12b überführt. Das Adapterrohr 12a,12b ist im Adaptergehäuse 10 und an der Eintrittsstelle in den Flammraum 6 längsverschieblich gelagert. Die Schulter 3a des Flammrohres 3 ist mit ringförmig angeordneten Oeffnungen 3b versehen, deren Funktion nachstehend erläutert wird. Die Oeffnungen könnten auch gegebenenfalls zusätzlich im Verbrennungsluftrohr 2 im Bereiche des Adaptergehäuses 10 oder Adapterrohrteils 12a vorgesehen sein. Auch können die Schultern im Adapterrohr 12a, 12b und im Flammrohr (3,3a) bzw. im Verbrennungsluftrohr 2 vor dem Stabilisator oder falls kein Stabilisator verwendet wird, vor der Mündung der Brennstoffdüse 1a angeordnet sein.Figure 1 shows a schematic representation of a burner for solid, liquid and gaseous fuels with an exhaust gas recirculation system according to the invention. Fuel is passed through a fuel pipe 1 via a fuel nozzle 1a injected into the flame space 6 and thus generates a flame F. A mostly circular disk is arranged on the fuel nozzle 1 a by means of flanges 4 a, which acts as a stabilizer for the flame and is referred to below as stabilizer 4. The combustion air tube 2 merges into the flame tube 3, which has a conically shaped shoulder 3a in front of the stabilizer 4. The exhaust gases are discharged through an exhaust pipe 7 into a chimney, not shown in the figure. An exhaust gas recirculation duct 8 leads from the exhaust pipe 7 into an adapter housing 10. An exhaust gas blower 9 is provided in the exhaust gas recirculation duct 8 for better recirculation of the exhaust gas. Furthermore, the exhaust gas flow can be regulated with a valve 16. From the adapter housing 10 leads an adapter tube part 12a which surrounds the combustion air tube 2 and which, via a conically increasing adapter tube shoulder 11, transfers into an adapter tube part 12b which is provided with a larger diameter and surrounds the flame tube 3. The adapter tube 12a, 12b is mounted in the adapter housing 10 and at the entry point into the flame space 6 so as to be longitudinally displaceable. The shoulder 3a of the flame tube 3 is provided with openings 3b arranged in a ring, the function of which is explained below. The openings could also optionally be provided in the combustion air tube 2 in the area of the adapter housing 10 or adapter tube part 12a. The shoulders can also be arranged in the adapter tube 12a, 12b and in the flame tube (3,3a) or in the combustion air tube 2 in front of the stabilizer or, if no stabilizer is used, in front of the mouth of the fuel nozzle 1a.

Durch das Brennstoffrohr 1 wird der Brennstoff in den Flammraum 6 injiziert. Zugleich lässt man durch das Verbrennungsluftrohr 2, welches das Brennstoffrohr umschliesst, Verbrennungsluft in den Flammraum 6 einströmen. Die durch den Verbrennungsvorgang entstehenden Abgase werden über das Abgasrohr 7 in den Kamin abgeführt. Ein Teil der Abgase - bei Vollast in der Regel ungefähr 20% - werden über den Abgasrückführkanal 8 in das Adaptergehäuse 10 geleitet. Die Rückförderung der Abgase wird durch das Abgasgebläse 9 unterstützt. Ein Teil der Abgase 15 strömt durch den zwischen Flammrohr 3 und Adapterrohr 12a, 12b gebildeten Ringraum und der andere Teil gelangt durch die Oeffnungen 3b der Schulter 3a des Flammrohres 3. Die Oeffnungen sind in der Weise angeordnet, dass der hier einströmende Abgasanteil um den Stabilisator 4 herum in den Flammraum 6 gelangt.The fuel is injected into the flame chamber 6 through the fuel pipe 1. At the same time, combustion air can flow into the flame chamber 6 through the combustion air pipe 2, which surrounds the fuel pipe. The exhaust gases resulting from the combustion process are discharged into the chimney via the exhaust pipe 7. A part of the exhaust gases - usually about 20% at full load - are conducted into the adapter housing 10 via the exhaust gas recirculation channel 8. The exhaust gas fan 9 supports the return of the exhaust gases. Part of the exhaust gases 15 flows through the annular space formed between the flame tube 3 and adapter tube 12a, 12b and the other part passes through the openings 3b of the shoulder 3a of the flame tube 3. The openings are in arranged in such a way that the exhaust gas component flowing in here passes around the stabilizer 4 into the flame chamber 6.

Diese Art der Aufteilung hat verschiedene Vorteile gegenüber den herkömmlichen Abgasrückführsystemen. Auf der einen Seite kann mit einfachen Mitteln auch im Nachhinein eine Stickoxid reduzierende Abgasrückführung eingebaut werden. Dank der Verschiebbarkeit des Adapterrohres 12a, 12b und Adapterrohrschulter 11 können die unterschiedlichsten Brennertypen beispielsweise mit Flammenumkehr- oder Dreizugkessel mit demselben einfachen Adaptersystem nachgerüstet werden. In den meisten Fällen kann, sofern - wie im Ausführungsbeispiel geschildert - ein Brenner verwendet wird, dessen Flammrohr eine konische Schulter aufweist - als Adapterrohr 12a, 12b und Adapterrohrschulter 11 ein herkömmliches Flammrohr grösseren Kalibers verwendet werden. Dieses wird über Verbrennungsluftrohr 2 und das Flammrohr 3 gestülpt und mit einem Adaptergehäuse 10 versehen, das am Abgasrückführkanal 8 angeschlossen ist, und ermöglicht auf diese Weise eine besonders kostengünstige Nachrüstung.This type of division has several advantages over conventional exhaust gas recirculation systems. On the one hand, nitrogen oxide reducing exhaust gas recirculation can be installed afterwards with simple means. Thanks to the displaceability of the adapter tube 12a, 12b and adapter tube shoulder 11, the most varied of burner types can be retrofitted, for example with a flame reversing or three-pass boiler, using the same simple adapter system. In most cases, if - as described in the exemplary embodiment - a burner is used whose flame tube has a conical shoulder - a conventional flame tube of larger caliber can be used as adapter tube 12a, 12b and adapter tube shoulder 11. This is put over the combustion air tube 2 and the flame tube 3 and provided with an adapter housing 10 which is connected to the exhaust gas recirculation duct 8, and in this way enables a particularly cost-effective retrofit.

Je nach Brenner muss das Verhältnis des in das Flammrohr 3 einströmenden Abgasanteils 14 zum um das Flammrohr 3 strömenden Abgasanteil 15 variiert werden, um ein optimales Resultat zu erzielen. Infolgedessen ist es vorteilhaft, das Adapterrohr längsverschieblich zu lagern, so dass der Spalt zwischen den Schultern 3a und 11 variiert werden kann. Falls dieser, wie in der Figur 2 veranschaulicht, ganz geschlossen ist, gelangt kein Rauchgas mehr in den ringförmigen Raum zwischen Flammrohr 3 und Adapterrohr 12a, 12b, sondern ausschliesslich um den Stabilisator 4.Depending on the burner, the ratio of the exhaust gas component 14 flowing into the flame tube 3 to the exhaust gas component 15 flowing around the flame tube 3 must be varied in order to achieve an optimal result. As a result, it is advantageous to mount the adapter tube in a longitudinally displaceable manner, so that the gap between the shoulders 3a and 11 can be varied. If this is completely closed, as illustrated in FIG. 2, no more flue gas enters the annular space between the flame tube 3 and adapter tube 12a, 12b, but only around the stabilizer 4.

In einer Ausführungsvariante können auch - gegebenenfalls als zusätzliche Regeleinrichtungen - verschiebbare oder drehbare (z.B. ringförmige) Regelblenden vorgesehen werden, mit denen die Lichtung der Oeffnungen 3b der Flammrohrschulter 3a verändert werden kann.In one embodiment variant, movable or rotatable (e.g. ring-shaped) regulating diaphragms can also be provided, optionally as additional regulating devices, with which the clearing of the openings 3b of the flame tube shoulder 3a can be changed.

Da mit dem geschilderten Abgasrückführsystem die Verbrennung verzögert und die Flammtemperatur gesenkt wird, hat dies einen erhöhten Ausstoss an Russ und Kohenmonoxid zur Folge. Deshalb empfiehlt es sich in den meisten Fällen zusätzlich einen Aktivator vorzusehen. Bei einem solchen Aktivator wird mit einer Dosierpumpe ein geringer Teil der Verbrennungsluft durch eine wässrige Elektrolytlösung geführt und in Form eines Aerosols der Verbrennungsluft und/oder Abgase zugeleitet. Die Elektrolytlösung enthält Alkali- und/oder Erdalkalisalze und gegebenenfalls 2 bis 12%, vorzugsweise etwa 5%, Methylalkohol. Die auf diese Weise aktivierte Luft bzw. das aktivierte Abgas ist mit Aerosolpartikeln versetzt, die im Flammraum verdampfen und zu Ionen dissoziieren. Die Ionen sind am Oxidationsvorgang beteiligt, beschleunigen die Zündung und mindern deutlich die Bildung von Russ, CO und anderen Schadstoffen. An dieser Stelle sei noch darauf hingewiesen, dass ein solcher Aktivator keine Schwermetalle enthält.Since the described exhaust gas recirculation system delays combustion and lowers the flame temperature, this results in increased soot and carbon monoxide emissions. That is why it is recommended in most cases additionally provide an activator. In the case of such an activator, a small part of the combustion air is passed through an aqueous electrolyte solution using a metering pump and is supplied to the combustion air and / or exhaust gases in the form of an aerosol. The electrolytic solution contains alkali and / or alkaline earth salts and optionally 2 to 12%, preferably about 5%, methyl alcohol. The air or exhaust gas activated in this way is mixed with aerosol particles which evaporate in the flame space and dissociate into ions. The ions are involved in the oxidation process, accelerate the ignition and significantly reduce the formation of soot, CO and other pollutants. At this point it should be pointed out that such an activator contains no heavy metals.

Es hat sich als ausserordentlich vorteilhaft erwiesen, auch das rückgeführte Abgas in der genannten Weise zu aktivieren. Aus diesem Grunde ist es wichtig, dass ein möglichst homogenes Gemisch von Verbrennungsluft, Abgas und Aktivatorpartikeln erzielt wird. Um die Homogenisierung des Gemisches noch zu fördern, kann gemäss Figur 3 vor der Brennstoffdüse 1a am Stabilisator 4 ein Rezirkulationsring 13 befestigt werden. Dieser kann mittels Halterung 13a am Stabilisator 4 befestigt werden und weist einen Durchmesser auf, der kleiner als der halbe Durchmesser des Stabilisators 4 ist.It has proven to be extremely advantageous to also activate the recirculated exhaust gas in the manner mentioned. For this reason it is important that a mixture of combustion air, exhaust gas and activator particles that is as homogeneous as possible is achieved. In order to further promote the homogenization of the mixture, a recirculation ring 13 can be attached to the stabilizer 4 in front of the fuel nozzle 1a, as shown in FIG. This can be fastened to the stabilizer 4 by means of a holder 13a and has a diameter which is smaller than half the diameter of the stabilizer 4.

Bei der Kombination mit dem Aktivator ist es im Gegensatz zu den herkömmlichen Verfahren möglich, auch Grossanlagen bei Vollast laufen zu lassen, und dadurch den Schadstoffausstoss in vertretbaren Grenzen zu halten.In combination with the activator, in contrast to the conventional methods, it is also possible to run large systems at full load, thereby keeping pollutant emissions within reasonable limits.

Claims (6)

  1. An apparatus for the recirculation of flue gases in burners for solid, liquid and gaseous fuels, with a burner which has a fuel supply system provided with a fuel nozzle (1a), a combustion air tube (2) and a flame tube (3) with a shoulder (3a), with a flame compartment (6) to which there is joined an exhaust pipe (7), and with a flue gas recirculation duct (8) connected to the exhaust pipe (7) and leading into an adapter, with an adapter casing (10), an adapter tube (12a, 12b) and an adapter tube shoulder (11) which surround the flame tube (3), in which arrangement the flame tube (3) and, if required the combustion air tube (2), are provided with openings (3b) through which the exhaust gases can be introduced into the flame tube (3), characterized in that a gap is formed between the two shoulders (3a and 11 respectively) and that the adapter tube (12a, 12b) is mounted for longitudinal displacement, so that the gap width and thus the ratio of the proportions of the exhaust gases which can be introduced into the annular apace formed between the flame tube (3) and the adapter tube (12a, 12b) and of the proportions of the exhaust gases which can be introduced into the openings (3b) of the flame tube (3) can be varied by the displacement of the adapter tube (12a, 12b) in the longitudinal direction.
  2. An apparatus according to claim 1, characterized in that the adapter has an adapter tube (12a, 12b) surrounding the flame tube (3) and leading into the flame compartment (6), so that an annular space is formed which passes into the flame compartment (6), through which a proportion of the recirculated exhaust gases can be fed into the flame compartment (6).
  3. An apparatus according to claim 1 and 2, characterized in that the adapter tube (12a, 12b) is a flame tube with a wider opening than the flame tube (3) of the burner.
  4. An apparatus according to one of claims 1 to 3, characterized in that in the zone of the fuel nozzle (1a) provision is made for a stabilizer (4) and behind it, for a recirculation ring (13).
  5. An apparatus according to one of claims 1 - 4, characterized in that the diameter of the recirculation ring (13) is smaller than half the diameter of the stabilizer (4).
  6. An apparatus according to one of claims 1 to 5, characterized in that for the purpose of activating the combustion air and/or the recirculated exhaust gases, the burner is connected to an apparatus which produces an aqueous aerosol which contains alkalis and/or alkaline earth salts and if required, 2 to 12%, preferably approximately 5%, methyl alcohol.
EP90810274A 1989-04-07 1990-04-05 Apparatus for flue gas recirculation in oil and gas burners Expired - Lifetime EP0391858B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CH133489 1989-04-07
CH1334/89 1989-04-07

Publications (2)

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EP0391858A1 EP0391858A1 (en) 1990-10-10
EP0391858B1 true EP0391858B1 (en) 1995-01-04

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EP90810274A Expired - Lifetime EP0391858B1 (en) 1989-04-07 1990-04-05 Apparatus for flue gas recirculation in oil and gas burners

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EP (1) EP0391858B1 (en)
AT (1) ATE116732T1 (en)
DE (1) DE59008164D1 (en)
DK (1) DK0391858T3 (en)
ES (2) ES2028504A6 (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN210462982U (en) * 2019-06-28 2020-05-05 浙江先创能源科技股份有限公司 Flue gas forced internal circulation boiler

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3868211A (en) * 1974-01-11 1975-02-25 Aqua Chem Inc Pollutant reduction with selective gas stack recirculation
DE2511500C2 (en) * 1975-03-15 1983-08-11 Smit Nijmegen B.V., Nijmegen Burners for burning liquid fuel
DE2751524C2 (en) * 1977-11-18 1986-08-21 Deutsche Forschungs- und Versuchsanstalt für Luft- und Raumfahrt e.V., 5000 Köln Blue-burning oil burner
DE3327597A1 (en) * 1983-07-30 1985-02-07 Deutsche Babcock Werke AG, 4200 Oberhausen METHOD AND BURNER FOR BURNING LIQUID OR GASEOUS FUELS WITH REDUCED NOX PRODUCTION
EP0202262B1 (en) * 1984-11-16 1989-10-04 BALSIGER, Benno Device for activating the combustion process
DE3509896A1 (en) * 1985-03-19 1986-09-25 Klamke-Record Öl- und Gasbrenner GmbH, 5200 Siegburg Oil burner
DE3618987A1 (en) * 1986-06-05 1987-12-10 Walter Swoboda Combustion method
IT1201611B (en) * 1986-12-19 1989-02-02 Liddo Angelo Nicola Di BURNING LIQUID TO CATALIZE COMBUSTION IN BURNERS, INTERNAL COMBUSTION ENGINES OR SIMILAR
DE3713408A1 (en) * 1987-04-21 1988-11-03 Weishaupt Max Gmbh METHOD FOR REDUCING NO (ARROW DOWN) X (ARROW DOWN) VALUES IN OIL- OR GAS-OPERATED COMBUSTION SYSTEMS

Also Published As

Publication number Publication date
EP0391858A1 (en) 1990-10-10
ATE116732T1 (en) 1995-01-15
DK0391858T3 (en) 1995-05-15
ES2069053T3 (en) 1995-05-01
DE59008164D1 (en) 1995-02-16
ES2028504A6 (en) 1992-07-01

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