EP0003000A1 - Burner head for a combustion chamber - Google Patents

Burner head for a combustion chamber Download PDF

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Publication number
EP0003000A1
EP0003000A1 EP78810027A EP78810027A EP0003000A1 EP 0003000 A1 EP0003000 A1 EP 0003000A1 EP 78810027 A EP78810027 A EP 78810027A EP 78810027 A EP78810027 A EP 78810027A EP 0003000 A1 EP0003000 A1 EP 0003000A1
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EP
European Patent Office
Prior art keywords
combustion
pot
gas
fuel
diameter
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EP78810027A
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German (de)
French (fr)
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EP0003000B1 (en
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Herbert Hazard
Vincenzo Recchi
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
    • 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
    • F23C7/004—Combustion apparatus characterised by arrangements for air supply the air being submitted to a rotary or spinning motion using vanes
    • 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
    • F23D11/404—Flame tubes
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
    • F23C2202/00—Fluegas recirculation
    • F23C2202/40—Inducing local whirls around flame
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23D—BURNERS
    • F23D2900/00—Special features of, or arrangements for burners using fluid fuels or solid fuels suspended in a carrier gas
    • F23D2900/00016—Preventing or reducing deposit build-up on burner parts, e.g. from carbon

Definitions

  • the flame resulting from the combustion of a fluid fuel in the presence of a gas whose oxygen concentration is significantly lower than that of air becomes much less stable.
  • the liquid fuel pulverized in this swirling flow is subjected, by this fact, to centrifugal forces, so that fuel droplets are projected against the wall of the chamber combustion. Since the temperature of this wall is lower than the final distillation temperature of the pulverized fuel, a deposit of coke and soot is formed at the outlet of the burner.
  • burners for fluid fuels the outlet of which opens into a flame pot placed in the combustion chamber.
  • the purpose of these flame pots is to avoid contact of the fuel with the walls of the combustion chamber cooled from the outside and to limit most of the combustion process to a reduced space in which the temperature can reach a higher level.
  • This is notably the case of US patents 3,319,692, 2,606,604 and 40,414,639 as well as DE-OS 2,250,766 in which the wall of the flame pot is metallic, while in US patents 2,806,517 and FR 2.226.056 the pots are made of refractory material.
  • the object of the present invention is to remedy, at least in part, the above-mentioned drawbacks.
  • the subject of the invention is a combustion head intended for a combustion chamber and comprising a nozzle for injecting a fluid fuel, in particular liquid, connected to a source of this fuel under pressure and a conduit for supply of a gas connected to a gas source under pressure containing oxygen, the downstream end of which opens into a generally cylindrical combustion space.
  • This combustion head is characterized in that the communication opening between said duct and said space is dimensioned to create a pressure drop during the passage of said gas, comprised between 75 and 150 mm of water column, that the diameter of this space is between 2 and 6 times the diameter of said opening, a disc is disposed at the outlet of said combustion space, r at a distance between 3.5 and 5.5 times the diameter of said opening, and that the diameter of this disc is chosen to create a pressure drop of between 15 and 50 mm of water column, at the outlet of said combustion space.
  • the single figure of the appended drawing illustrates, schematically and by way of example, a combustion head according to the invention, seen in axial section, mounted at the inlet of a combustion chamber.
  • the combustion head illustrated comprises all the elements of a burner, namely, a fuel injection nozzle 1, arranged coaxially in a supply duct 2 of a mixture of air and combustion gases.
  • This duct 2 constitutes the outlet of a spiral cover 3 fixed to the cover 4 of a combustion chamber 5 and ends in this combustion chamber by a cylindrical pot 6 constituting the combustion head proper, about which additional details will be given later.
  • a fixed blade 7, forming a crown, can be arranged at the outlet of the spiral cover 3.
  • the inclination of this blade is chosen to impart, to the mixture of oxygen-carrying gas introduced into the combustion chamber 5, a slight helical movement called "swirl" defined by a number.
  • This number of "swirls" G 4 / rG x is given by the ratio between the flow of angular momentum G, communicated to the gas and the product of the radius of the distribution opening of the burner r by the flux of axial momentum G.
  • This number x is preferably chosen to be less than 0.2 and in all cases less than the threshold from which a toroidal vortex is created under the effect of the swirl.
  • the mixture of oxygen-carrying gas can be introduced into the cylindrical pot 6 without any helical innovation.
  • the duct 2 going from the vanes 7 to the nozzle 1 can be divided in two by a partition 9, and the vanes 7, on either side of this partition 9, can be inclined in opposite direction from each other, so as to form two flows animated by helical movements of opposite directions, which mix at the time of being injected into the pot 6.
  • These two helical flows tend to cancel out by mixing. Therefore, it is quite possible to significantly exceed the number of swirls of 0.2 indicated previously, for each flow, the total number of swirls should then not exceed approximately 0.2 to 0.3.
  • This variant has the advantage of creating an additional mixture when the two flows are combined.
  • the pot 6 in which most of the combustion takes place has an inlet opening 6a as well as an annular outlet opening 6b formed around a disc 6c, fixed concentrically to the cylindrical pot 6 by radial arms 6d.
  • the dimensions of the various elements of the cylindrical pot 6 are important for obtaining a combustion practically free of soot and of CO, operating with an excess of air of 5 to 15% and a recirculation of approximately 50% of the gases. exhaust, and so that combustion is stable, that there is no deposit of coke and that ignition is easy.
  • the oxygen-carrying gas introduced into the cylindrical pot 6 must be driven at a high speed in order to produce a high level of turbulence necessary for obtaining intense combustion.
  • Tests have shown that the diameter of opening 6a must be dimensioned to produce a pressure drop of 75 to 150 mm of water column. Below this limit, combustion is poor and beyond, ignition is difficult.
  • the pot can be sized from the diameter of the opening 6a. Its length must be chosen between 3.5 and 5.5 times this diameter. In fact this length is chosen so that the central body I of the gas flow introduced into the pot 6 does not touch the disc 6c. However, the length of this central body is of the order of 4 to 5 times the diameter of the opening 6a depending on the amount of swirl. If the disc 6c is too close to the opening 6a, the body I of the injected cold gas meeting this disc extends radially outwards from the latter while cooling it. If, on the contrary, the disc 6c is placed too far from the opening 6a, the flame becomes unstable. At the optimal position of the disc, the flame is stable and the disc is hot enough to avoid the formation of carbon or coke deposits.
  • This disc 6c is not necessarily placed at the end of the pot 6. It can be either slightly inside or outside this pot 6, depending on the shape that one wishes to give to the flame coming out of the pot 6 through the annular opening 6b.
  • this annular opening 6b is chosen to induce recirculation behind the disc 6c so to ensure the combustion of residual fuel and to reach CO levels as low as possible.
  • the diameter of the disc 6c is chosen so that the annular opening generates a pressure drop of the order of 15 to 30 mm of water column.
  • the diameter of the cylindrical portion of this pot 6 is between 2 and 6 times the diameter of the opening 6a.
  • the figure in the drawing shows the different flow modes in the cylindrical pot 6 as well as at the outlet of this pot.
  • the angle of the fuel spraying cone II is preferably between 60 and 95 degrees.
  • a recirculation III is formed around a turbulent zone IV surrounding the central body I of the air jet.
  • This recirculation III makes it possible to heat the wall of the cylindrical pot 6 to a temperature of 600 0 to 800 0 , at which the pot becomes bright red, a temperature which is higher than the final temperature of the distillation curve of a light fuel oil. , so that no deposit by accumulation of coke can occur.
  • This annular recirculation III also has the effect of bringing the combustion products to the base of the air jet leaving the orifice 6a, thereby improving the stability of the flame.
  • this recirculation III in the form of a toroidal vortex has a direction of rotation, indicated by arrows, contrary to the direction of rotation which would be induced by an intense swirl.
  • This direction of rotation is important, since, in the case of the jet, the direction of rotation induced causes a recirculation of the hot combustion gases which heat the wall of the pot 6.
  • the opposite direction of rotation to that illustrated sends cold gases leaving the opening 6a against the wall of the pot 6, hence the formation of carbon and coke deposits.

Abstract

Cette invention se rapporte à une tête de combustion pour un combustible fluide, notamment liquide, brûlé en présence notamment d'un gaz dont la concentration d'oxygène est sensiblement inférieure à celle de l'air. Cette tête comporte, adjacent au brûleur proprement dit, un pot (6) de forme générale cylindrique, présentant une ouverture d'entrée (6a) destinée à créer une perte de charge sensible pour injecter le gaz porteur d'oxygène dans le pot et un disque (6c) situé à la sortie du pot et dimensionné pour créer une seconde perte de charge plus faible. La combustion intense produite dans le pot (6) chauffe ses parois à une température située sensiblement au-dessus du point final de la courbe de distillation du fuel pour empêcher le dépôt de coke.This invention relates to a combustion head for a fluid fuel, in particular a liquid fuel, burned in the presence in particular of a gas whose oxygen concentration is substantially lower than that of air. This head comprises, adjacent to the burner proper, a pot (6) of generally cylindrical shape, having an inlet opening (6a) intended to create a significant pressure drop for injecting the oxygen-carrying gas into the pot and a disc (6c) located at the outlet of the pot and sized to create a second lower pressure drop. The intense combustion produced in the pot (6) heats its walls to a temperature situated substantially above the end point of the fuel distillation curve to prevent the deposition of coke.

Description

Les avantages, liés à la combustion utilisant comme gaz porteur d'oxygène une certaine proportion de gaz de combustion mélange à de l'air, sont bien connus. Cette recirculation permet d'augmenter les débits massiques de gaz de combustion, tout en fixant le taux d'excès d'air à un niveau très bas. La dilution de l'oxygène nécessaire, dans une plus grande masse de gaz, abaisse la température de la flamme. Ce type de combustion permet de réduire la production de NOx ainsi que celle de suie. L'augmentation du débit massique de gaz, due à la recirculation des gaz de combustion, permet d'accroître le rendement des échanges thermiques et de réduire le débit massique à la cheminée.The advantages associated with combustion using a certain proportion of combustion gas mixed with air as the oxygen-carrying gas are well known. This recirculation makes it possible to increase the mass flow rates of combustion gases, while fixing the rate of excess air at a very low level. The dilution of the necessary oxygen, in a larger mass of gas, lowers the temperature of the flame. This type of combustion reduces the production of NO x as well as that of soot. The increase in the mass flow of gas, due to the recirculation of the combustion gases, makes it possible to increase the efficiency of the heat exchanges and to reduce the mass flow at the chimney.

Par contre, la flamme résultant de la combustion d'un combustible fluide en présence d'un gaz dont la concentration d'oxygène est sensiblement plus faible que celle de l'air, devient beaucoup moins stable. Pour remédier à ce défaut, il a été proposé d'introduire le gaz porteur d'oxygène en lui communiquant un fort mouvement tourbillonnaire. Cette quantité de mouvement tourbillonnaire nécessaire pour stabiliser la flamme est d'autant plus forte que la concentration d'oxygène est faible. Or, le combustible liquide pulvérisé dans cet écoulement tourbillonnaire est soumis, de ce fait, à des forces centrifuges, de sorte que des gouttelettes de combustible sont projetées contre la paroi de la chambre de combustion. Etant donné que la température de cette paroi est inférieure à la température finale de distillation du combustible pulvérisé, un dépôt de coke et de suie se forme à la sortie du brûleur.By cons, the flame resulting from the combustion of a fluid fuel in the presence of a gas whose oxygen concentration is significantly lower than that of air, becomes much less stable. To remedy this defect, it has been proposed to introduce the oxygen-carrying gas by imparting to it a strong vortex movement. This amount of vortex movement required to stabilize the flame is greater the lower the oxygen concentration. However, the liquid fuel pulverized in this swirling flow is subjected, by this fact, to centrifugal forces, so that fuel droplets are projected against the wall of the chamber combustion. Since the temperature of this wall is lower than the final distillation temperature of the pulverized fuel, a deposit of coke and soot is formed at the outlet of the burner.

Il existe des brûleurs pour combustibles fluides dont la sortie débouche dans un pot de flamme placé dans la chambre de combustion. Ces pots de flamme ont pour but d'éviter la mise en contact du combustible avec les parois de la chambre de combustion refroidies de l'extérieur et de limiter l'essentiel du processus de combustion à un espace réduit dans lequel la température peut atteindre un niveau plus élevé. C'est notamment le cas des brevets US 3.319.692, 2.606.604 et 40.414.639 ainsi que du DE-OS 2.250.766 dans lesquels la paroi du pot de flamme est métallique, tandis que dans les brevets US 2.806.517 et FR 2.226.056 les pots sont en matériau réfractaire.There are burners for fluid fuels, the outlet of which opens into a flame pot placed in the combustion chamber. The purpose of these flame pots is to avoid contact of the fuel with the walls of the combustion chamber cooled from the outside and to limit most of the combustion process to a reduced space in which the temperature can reach a higher level. This is notably the case of US patents 3,319,692, 2,606,604 and 40,414,639 as well as DE-OS 2,250,766 in which the wall of the flame pot is metallic, while in US patents 2,806,517 and FR 2.226.056 the pots are made of refractory material.

A part les brevets US 2.606.604 et 3.319.692, tous ces documents proposent d'augmenter la durée de séjour du mélange de gaz porteur d'oxygène et de combustible dans le pot de flamme, en leur communiquant un mouvement tourbillonnaire suffisamment important pour engendrer en son centre une dépression génératrice d'un vortex toroidal allongeant ainsi la longueur du parcourt de ce mélange de gaz dans le pot de flamme. Toutefois, comme on l'a déjà mentionné précédemment, ce fort mouvement tourbillonnaire projette des gouttelettes du combustible pulvérisé contre les parois du pot de flamme. En outre, la recirculation interne, induite par le vortex annulaire engendré par le tourbillon de gaz porteur d'oxygène amène le gaz froid introduit dans ce pot, directement contre sa paroi et la refroidit. De ce fait, sa température s'abaisse et empêche la combustion complète du combustible projeté contre sa surface de sorte que ces résidus de combustible forment un dépôt de coke qui s'accumule. Il résulte de ces documents que si l'on a déjà proposé que l'essentiel du processus de combustion se déroule dans un pot dont les parois ne sont pas refroidies de l'extérieur comme celles des chambres de combustion classiques, les solutions proposées ne remplissent que partiellement leur objectif dans la mesure où les parois sont refroidies de-l'intérieur sous l'effet de l'écoulement tourbillonnaire du mélange de gaz porteur d'oxygène.Apart from US Patents 2,606,604 and 3,319,692, all of these documents propose increasing the residence time of the mixture of oxygen-carrying gas and fuel in the flame pot, by communicating to them a sufficiently large vortex movement to generate in its center a depression generating a toroidal vortex thus lengthening the length of the path of this mixture of gases in the flame pot. However, as already mentioned previously, this strong vortex movement projects droplets of the atomized fuel against the walls of the flame pot. In addition, the internal recirculation, induced by the annular vortex generated by the vortex of oxygen-carrying gas brings the cold gas introduced into this pot, directly against its wall and cools it. As a result, its temperature is lowered and prevents the complete combustion of the fuel projected against its surface so that these fuel residues form a deposit of coke which accumulates. It follows from these documents that if it has already been proposed that the main part of the combustion process takes place in a pot whose walls are not cooled from the outside like those of conventional combustion chambers, the solutions proposed only partially fulfill their objective insofar as the walls are cooled from the inside under the effect of the vortex flow of the oxygen-carrying gas mixture.

Quant aux brevets US 2.606.604 et 3.319.692 dans lesquels l'air est introduit sans tourbillon dans le pot, le premier • de ces documents utilise une succession de déflecteurs percés, disposés transversalement à l'axe du pot pour retenir le mélange combustible afin que la chaleur provenant de la combustion réchauffe le mélange au fur et à mesure de son introduction et améliore la combustion. Toutefois, aucune précision n'est donnée sur le mode d'écoulement du mélange combustible dans ce pot et donc sur le déroulement de la combustion. Enfin, dans le second de ces brevets US, aucune disposition particulière n'est prise pour augmenter le temps de séjour du mélange combustible dans le pot, seule une recirculation extérieure à ce pot étant induite.As for US Patents 2,606,604 and 3,319,692 in which air is introduced without vortex into the pot, the first • of these documents uses a succession of pierced deflectors, arranged transversely to the axis of the pot to retain the combustible mixture so that the heat from the combustion heats the mixture as it is introduced and improves the combustion. However, no details are given on the flow mode of the fuel mixture in this pot and therefore on the course of combustion. Finally, in the second of these US patents, no particular provision is made to increase the residence time of the combustible mixture in the pot, only recirculation outside this pot being induced.

Il apparaît qu'aucune de ces solutions ne permet de résoudre de manière satisfaisante, le problème de la combustion d'un combustible fluide, notamment liquide, avec recirculation externe de gaz d'échappement de manière que la combustion soit complète et stable, tout en fonctionnant avec un très faible taux d'excès d'air.It appears that none of these solutions makes it possible to solve in a satisfactory manner, the problem of the combustion of a fluid fuel, in particular liquid, with external recirculation of exhaust gases so that the combustion is complete and stable, while operating with a very low rate of excess air.

Le but de la présente invention est de remédier, au moins en partie, aux inconvénients susmentionnés.The object of the present invention is to remedy, at least in part, the above-mentioned drawbacks.

A cet effet, l'invention a pour objet une tête de combustion destinée à une chambre de combustion et comprenant une buse d'injection d'un combustible fluide, notamment liquide, reliée à une source de ce combustible sous pression et un conduit d'alimentation d'un gaz relié à une source de gaz sous pression contenant de l'oxygène, dont l'extrémité aval débouche dans un espace de combustion de forme générale cylindrique. Cette tête de combustion est caractérisée par le fait que l'ouverture de communication entre ledit conduit et ledit espace est dimensionnée pour créer une chute de pression lors du passage dudit gaz, comprise entre 75 et 150 mm de colonne d'eau, que le diamètre de cet espace est compris entre 2 et 6 fois le diamètre de ladite ouverture, qu'un disque est disposé à la sortie dudit espace de combustion, r à une distance comprise entre 3,5 et 5,5 fois le diamètre de ladite ouverture, et que le diamètre de ce disque est choisi pour créer une chute de pression comprise entre 15 et 50 mm de colonne d'eau, à la sortie dudit espace de combustion.To this end, the subject of the invention is a combustion head intended for a combustion chamber and comprising a nozzle for injecting a fluid fuel, in particular liquid, connected to a source of this fuel under pressure and a conduit for supply of a gas connected to a gas source under pressure containing oxygen, the downstream end of which opens into a generally cylindrical combustion space. This combustion head is characterized in that the communication opening between said duct and said space is dimensioned to create a pressure drop during the passage of said gas, comprised between 75 and 150 mm of water column, that the diameter of this space is between 2 and 6 times the diameter of said opening, a disc is disposed at the outlet of said combustion space, r at a distance between 3.5 and 5.5 times the diameter of said opening, and that the diameter of this disc is chosen to create a pressure drop of between 15 and 50 mm of water column, at the outlet of said combustion space.

La figure unique du dessin annexé illustre, schématiquement et à titre d'exemple, une tête de combustion selon l'invention, vue en coupe axiale, montée à l'entrée d'une chambre de combustion.The single figure of the appended drawing illustrates, schematically and by way of example, a combustion head according to the invention, seen in axial section, mounted at the inlet of a combustion chamber.

La tête de combustion illustrée comporte tous les éléments d'un brûleur, à savoir, une buse 1 d'injection de fuel, disposée coaxialement dans un conduit d'alimentation 2 d'un mélange d'air et de gaz de combustion. Ce conduit 2 constitue la sortie d'une bâche spirale 3 fixée au couvercle 4 d'une chambre de combustion 5 et se termine dans cette chambre de combustion par un pot cylindrique 6 constituant la tête de combustion proprement dite au sujet de laquelle des détails supplémentaires seront donnés par la suite.The combustion head illustrated comprises all the elements of a burner, namely, a fuel injection nozzle 1, arranged coaxially in a supply duct 2 of a mixture of air and combustion gases. This duct 2 constitutes the outlet of a spiral cover 3 fixed to the cover 4 of a combustion chamber 5 and ends in this combustion chamber by a cylindrical pot 6 constituting the combustion head proper, about which additional details will be given later.

Un aubage fixe 7, formant une couronne, peut être disposé à la sortie de la bâche spirale 3. L'inclinaison de cet aubage est choisie pour imprimer, au mélange de gaz porteur d'oxygène introduit dans la chambre de combustion 5, un léger mouvement hélicoïdal appelé "swirl" défini par un nombre. Ce nombre de "swirl" G4/r.Gx est donné par le rapport entre le flux de moment cinétique G, communiqué au gaz et le produit du rayon de l'ouverture de distribution du brûleur r par le flux de quantité de mouvement axial G . Ce nombre x est choisi de préférence inférieur à 0,2 et dans tous les cas inférieur au seuil à partir duquel un vortex toroidal se crée sous l'effet du swirl.A fixed blade 7, forming a crown, can be arranged at the outlet of the spiral cover 3. The inclination of this blade is chosen to impart, to the mixture of oxygen-carrying gas introduced into the combustion chamber 5, a slight helical movement called "swirl" defined by a number. This number of "swirls" G 4 / rG x is given by the ratio between the flow of angular momentum G, communicated to the gas and the product of the radius of the distribution opening of the burner r by the flux of axial momentum G. This number x is preferably chosen to be less than 0.2 and in all cases less than the threshold from which a toroidal vortex is created under the effect of the swirl.

En variante, le mélange de gaz porteur d'oxygène peut être introduit dans le pot cylindrique 6 sans aucun inouvement hélicoïdal.As a variant, the mixture of oxygen-carrying gas can be introduced into the cylindrical pot 6 without any helical innovation.

Selon une autre variante illustrée en traits mixtes, le conduit 2 allant des aubes 7 à la buse 1 peut être divisé en deux par une cloison 9, et les aubes 7, de part et d'autre de cette cloison 9, peuvent être inclinées en sens contraire les unes des autres, de manière à former deux écoulements animés de mouvements hélicoïdaux de sens contraires, qui se mélangent au moment d'être injectés dans le pot 6. Ces deux écoulements hélicoïdaux tendent à s'annuler en se mélangeant. De ce fait, il est tout à fait possible de dépasser notablement le nombre de swirl de 0,2 indiqué précédemment, pour chacun des écoulements, le nombre total de swirl ne devant alors pas dépasser environ 0,2 à 0,3. Cette variante présente l'intérêt de créer un mélange supplémentaire lors de la réunion des deux écoulements.According to another variant illustrated in dashed lines, the duct 2 going from the vanes 7 to the nozzle 1 can be divided in two by a partition 9, and the vanes 7, on either side of this partition 9, can be inclined in opposite direction from each other, so as to form two flows animated by helical movements of opposite directions, which mix at the time of being injected into the pot 6. These two helical flows tend to cancel out by mixing. Therefore, it is quite possible to significantly exceed the number of swirls of 0.2 indicated previously, for each flow, the total number of swirls should then not exceed approximately 0.2 to 0.3. This variant has the advantage of creating an additional mixture when the two flows are combined.

Le pot 6 dans lequel se produit la majeure partie de la combustion présente une ouverture d'entrée 6a ainsi qu'une ouverture de sortie annulaire 6b ménagée autour d'un disque 6c, fixé concentriquement au pot cylindrique 6 par des bras radiaux 6d.The pot 6 in which most of the combustion takes place has an inlet opening 6a as well as an annular outlet opening 6b formed around a disc 6c, fixed concentrically to the cylindrical pot 6 by radial arms 6d.

Les dimensions des différents éléments du pot cylindrique 6 sont importants pour obtenir une combustion pratiquement exempte de suie et de CO, fonctionnant avec un excès d'air de 5 à 15 % et une recirculation d'environ 50 % des gaz d'échappement, et pour que la combustion soit stable, qu'il ne se produise aucun dépôt de coke et que l'allumage soit facile.The dimensions of the various elements of the cylindrical pot 6 are important for obtaining a combustion practically free of soot and of CO, operating with an excess of air of 5 to 15% and a recirculation of approximately 50% of the gases. exhaust, and so that combustion is stable, that there is no deposit of coke and that ignition is easy.

A cet effet, le gaz porteur d'oxygène introduit dans le pot cylindrique 6 doit être animé d'une haute vitesse afin de produire un niveau de turbulence élevé nécessaire pour obtenir une combustion intense. Les essais ont montré que le diamètre de l'ouverture 6a doit être dimensionné pour produire une chute de pression de 75 à 150 mm de colonne d'eau. En deça de cette limite la combustion est mauvaise et au-delà, l'allumage est difficile.To this end, the oxygen-carrying gas introduced into the cylindrical pot 6 must be driven at a high speed in order to produce a high level of turbulence necessary for obtaining intense combustion. Tests have shown that the diameter of opening 6a must be dimensioned to produce a pressure drop of 75 to 150 mm of water column. Below this limit, combustion is poor and beyond, ignition is difficult.

Le pot peut être dimensionné à partir du.diamètre de l'ouverture 6a. Sa longueur doit être choisie entre 3,5 et 5,5 fois ce diamètre. En fait cette longueur est choisie pour que le corps central I de l'écoulement de gaz introduit dans le pot 6 ne touche pas le disque 6c. Or, la longueur de ce corps central est de l'ordre de 4 à 5 fois le diamètre de l'ouverture 6a suivant la quantité de swirl. Si le disque 6c est trop près de l'ouverture 6a, le corps I du gaz froid injecté rencontrant ce disque s'étend radialement vers l'extérieur de celui-ci en le refroidissant. Si, au contraire, le disque 6c est placé trop loin de l'ouverture 6a, la flamme devient instable. A la position optimale du disque, la flamme est stable et le disque est assez chaud pour éviter la formation de dépôts de carbone ou de coke.The pot can be sized from the diameter of the opening 6a. Its length must be chosen between 3.5 and 5.5 times this diameter. In fact this length is chosen so that the central body I of the gas flow introduced into the pot 6 does not touch the disc 6c. However, the length of this central body is of the order of 4 to 5 times the diameter of the opening 6a depending on the amount of swirl. If the disc 6c is too close to the opening 6a, the body I of the injected cold gas meeting this disc extends radially outwards from the latter while cooling it. If, on the contrary, the disc 6c is placed too far from the opening 6a, the flame becomes unstable. At the optimal position of the disc, the flame is stable and the disc is hot enough to avoid the formation of carbon or coke deposits.

Ce disque 6c n'est pas obligatoirement placé à l'extrémité du pot 6. Il peut se trouver soit légèrement en dedans, soit en dehors de ce pot 6, suivant la forme que l'on désire donner à la flamme sortant du pot 6 par l'ouverture_annulaire 6b.This disc 6c is not necessarily placed at the end of the pot 6. It can be either slightly inside or outside this pot 6, depending on the shape that one wishes to give to the flame coming out of the pot 6 through the annular opening 6b.

La dimension de cette ouverture annulaire 6b est choisie pour induire une recirculation derrière le disque 6c afin d'assurer la combustion du combustible résiduel et pour atteindre des niveaux de CO aussi bas que possible. A cet effet, le diamètre du disque 6c est choisi pour que l'ouverture annulaire engendre une chute de pression de l'ordre de 15 à 30 mm de colonne d'eau.The size of this annular opening 6b is chosen to induce recirculation behind the disc 6c so to ensure the combustion of residual fuel and to reach CO levels as low as possible. To this end, the diameter of the disc 6c is chosen so that the annular opening generates a pressure drop of the order of 15 to 30 mm of water column.

Le diamètre de la portion cylindrique de ce pot 6 est compris entre 2 et 6 fois le diamètre de l'ouverture 6a.The diameter of the cylindrical portion of this pot 6 is between 2 and 6 times the diameter of the opening 6a.

La figure du dessin montre les différents modes d'écoulement dans le pot cylindrique 6 ainsi qu'à la sortie de ce pot. L'angle du cône II de pulvérisation du fuel est de préférence compris entre 60 et 95 degrés. Comme on le voit, une recirculation III est formée autour d'une zone turbulente IV entourant le corps central I du jet d'air. Cette recirculation III permet de chauffer la paroi du pot cylindrique 6 jusqu'à une température de 6000 à 8000, à laquelle le pot devient rouge vif, température qui est supérieure à la température finale de la courbe de distillation d'un fuel léger, de sorte qu'aucun dépôt par accumulation de coke ne peut se produire. Cette recirculation annulaire III a aussi pour effet d'amener les produits de combustion à la base du jet d'air sortant de l'orifice 6a, améliorant de ce fait la stabilité de la flamme.The figure in the drawing shows the different flow modes in the cylindrical pot 6 as well as at the outlet of this pot. The angle of the fuel spraying cone II is preferably between 60 and 95 degrees. As can be seen, a recirculation III is formed around a turbulent zone IV surrounding the central body I of the air jet. This recirculation III makes it possible to heat the wall of the cylindrical pot 6 to a temperature of 600 0 to 800 0 , at which the pot becomes bright red, a temperature which is higher than the final temperature of the distillation curve of a light fuel oil. , so that no deposit by accumulation of coke can occur. This annular recirculation III also has the effect of bringing the combustion products to the base of the air jet leaving the orifice 6a, thereby improving the stability of the flame.

Il est à noter que cette recirculation III en forme de vortex toroïdal présente un sens de rotation, indiqué par des flèches, contraire au sens de rotation qui serait induit par un swirl intense. Ce sens de rotation est important, étant donné que, dans le cas du jet, le sens de la rotation induite provoque une recirculation des gaz de combustion chauds qui réchauffent la paroi du pot 6. Au contraire, dans le cas d'un vortex toroidal induit par un swirl, le sens de rotation contraire à celui illustré envoie des gaz froids sortant de l'ouverture 6a contre la paroi du pot 6, d'où la formation de dépôts de carbone et de coke.It should be noted that this recirculation III in the form of a toroidal vortex has a direction of rotation, indicated by arrows, contrary to the direction of rotation which would be induced by an intense swirl. This direction of rotation is important, since, in the case of the jet, the direction of rotation induced causes a recirculation of the hot combustion gases which heat the wall of the pot 6. On the contrary, in the case of a toroidal vortex induced by a swirl, the opposite direction of rotation to that illustrated sends cold gases leaving the opening 6a against the wall of the pot 6, hence the formation of carbon and coke deposits.

Claims (3)

1. Tête de combustion destinée à une chambre de combustion et comprenant une buse d'injection d'un combustible fluide, notamment liquide, reliée à une source de ce combustible sous pression et un conduit d'alimentation d'un gaz relié à une source de gaz sous pression contenant de l'oxygène, dont l'extrémité aval débouche dans un espace de combustion de forme générale cylindrique, caractérisée par le fait que l'ouverture de communication entre ledit conduit et ledit espace est dimensionnée pour créer une chute de pression lors du passage dudit gaz, comprise entre 75 et 150 mm de colonne d'eau, que le diamètre de cet espace est compris entre 2 et 6 fois le diamètre de ladite ouverture, qu'un disque est disposé à la sortie dudit espace de combustion, à une distance comprise entre 3,5 et 5,5 fois le diamètre de ladite ouverture, et que le diamètre de ce disque est choisi pour créer une chute de pression comprise entre 15 et 50 mm de colonne d'eau, à la sortie dudit espace de combustion.1. Combustion head intended for a combustion chamber and comprising a nozzle for injecting a fluid fuel, in particular a liquid fuel, connected to a source of this pressurized fuel and a gas supply duct connected to a source of pressurized oxygen-containing gas, the downstream end of which opens into a generally cylindrical combustion space, characterized in that the communication opening between said duct and said space is dimensioned to create a pressure drop during the passage of said gas, comprised between 75 and 150 mm of water column, that the diameter of this space is comprised between 2 and 6 times the diameter of said opening, that a disc is disposed at the outlet of said combustion space , at a distance between 3.5 and 5.5 times the diameter of said opening, and the diameter of this disc is chosen to create a pressure drop between 15 and 50 mm of water column, at the outlet of said combustion space. 2. Tête de combustion selon la revendication 1, caractérisée par le fait qu'un générateur de swirl est ménagé dans ledit conduit d'alimentation, ce générateur étant agencé pour que le swirl produit soit inférieur au seuil à partir duquel un vortex toroldal se crée sous l'effet de l'écoulement hélicoïdal dudit gaz.2. Combustion head according to claim 1, characterized in that a swirl generator is arranged in said supply duct, this generator being arranged so that the swirl produced is less than the threshold from which a toroldal vortex is created under the effect of the helical flow of said gas. 3. Tête de combustion selon la revendication 1, caractérisée par le fait que ledit conduit d'alimentation est divisé en deux parties annulaires coaxiales, chacune munie d'un générateur de swirl de nombre et/ou de sens différent, choisis pour que le nombre total de swirl soit inférieur au seuil à partir duquel un vortex toroidal se crée sous l'effet de l'écoulement hélicoïdal dudit gaz.3. Combustion head according to claim 1, characterized in that said supply duct is divided into two annular coaxial parts, each provided with a swirl generator of different number and / or direction, chosen so that the number total swirl is less than the threshold from which a toroidal vortex is created under the effect of the helical flow of said gas.
EP78810027A 1977-12-23 1978-12-04 Burner head for a combustion chamber Expired EP0003000B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CH1597477A CH617998A5 (en) 1977-12-23 1977-12-23
CH15974/77 1977-12-23

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EP0003000A1 true EP0003000A1 (en) 1979-07-11
EP0003000B1 EP0003000B1 (en) 1981-08-05

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EP78810027A Expired EP0003000B1 (en) 1977-12-23 1978-12-04 Burner head for a combustion chamber

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US (1) US4225305A (en)
EP (1) EP0003000B1 (en)
JP (1) JPS5494127A (en)
CA (1) CA1115200A (en)
CH (1) CH617998A5 (en)
DE (1) DE2860921D1 (en)
DK (1) DK577278A (en)
ES (1) ES476240A1 (en)
IT (1) IT7831195A0 (en)
NO (1) NO147615C (en)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4431403A (en) * 1981-04-23 1984-02-14 Hauck Manufacturing Company Burner and method
FR2536505A1 (en) * 1982-11-24 1984-05-25 Danfoss As GASIFICATION BURNER FOR LIQUID FUELS
US5466148A (en) * 1992-11-20 1995-11-14 Witteveen; Gustaaf J. Low NOX combustor
EP1363071A1 (en) * 2002-05-14 2003-11-19 Webasto Thermosysteme International GmbH Burner for a heating device
US10953643B2 (en) 2016-05-12 2021-03-23 The Boeing Company Methods and apparatus to form venting channels on a panel for a decorative layer

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JPS5827616U (en) * 1981-08-17 1983-02-22 三洋電機株式会社 combustion device
US4443182A (en) * 1981-11-10 1984-04-17 Hauck Manufacturing Company Burner and method
DE10019198A1 (en) 2000-04-17 2001-10-18 Webasto Thermosysteme Gmbh Atomizing burner especially for stand-alone heater in motor vehicle has impingement plate located inside combustion chamber in fuel atomizing direction and in flame zone, and provided with collar to form approximate shape of cup
WO2008154275A2 (en) * 2007-06-06 2008-12-18 North Carolina State University Process for combustion of high viscosity low heating value liquid fuels
US9982886B2 (en) 2012-07-06 2018-05-29 Honeywell International Inc. Flue gas recycle system with fixed orifices

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US2606604A (en) * 1946-04-27 1952-08-12 Eureka Williams Corp Oil burner of the pressure type
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US2606604A (en) * 1946-04-27 1952-08-12 Eureka Williams Corp Oil burner of the pressure type
FR1014072A (en) * 1950-03-08 1952-08-08 Chantier Et Ateliers De Saint High turbulence air distributor
US2806517A (en) * 1950-11-16 1957-09-17 Shell Dev Oil atomizing double vortex burner
US3319692A (en) * 1965-06-01 1967-05-16 Iit Res Inst Oil burner
FR1595206A (en) * 1967-12-19 1970-06-08
DE2250766A1 (en) * 1972-10-17 1974-04-18 Volkswagenwerk Ag BURNERS, IN PARTICULAR FOR VEHICLES
FR2226056A5 (en) * 1973-04-16 1974-11-08 Zink Co John
DE2365186A1 (en) * 1973-12-29 1975-07-10 Elco Oelbrennerwerk Ag Liquid fuel combustion with blue, soot-free flame - obtained by feeding flue gas controllably to fresh air intake
FR2300964A1 (en) * 1975-02-12 1976-09-10 Fascione Pietro ALI PROCESS
US4014639A (en) * 1975-04-10 1977-03-29 Minnesota Mining And Manufacturing Company Recirculating vortex burner
FR2342462A1 (en) * 1976-02-27 1977-09-23 Fascione Pietro FLUID FUEL BURNER

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4431403A (en) * 1981-04-23 1984-02-14 Hauck Manufacturing Company Burner and method
FR2536505A1 (en) * 1982-11-24 1984-05-25 Danfoss As GASIFICATION BURNER FOR LIQUID FUELS
US5466148A (en) * 1992-11-20 1995-11-14 Witteveen; Gustaaf J. Low NOX combustor
EP1363071A1 (en) * 2002-05-14 2003-11-19 Webasto Thermosysteme International GmbH Burner for a heating device
US10953643B2 (en) 2016-05-12 2021-03-23 The Boeing Company Methods and apparatus to form venting channels on a panel for a decorative layer

Also Published As

Publication number Publication date
ES476240A1 (en) 1979-10-01
NO784338L (en) 1979-06-26
IT7831195A0 (en) 1978-12-21
US4225305A (en) 1980-09-30
CH617998A5 (en) 1980-06-30
JPS5494127A (en) 1979-07-25
NO147615B (en) 1983-01-31
CA1115200A (en) 1981-12-29
DK577278A (en) 1979-06-24
NO147615C (en) 1983-05-11
DE2860921D1 (en) 1981-11-05
EP0003000B1 (en) 1981-08-05

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