FR2800844A1

FR2800844A1 - Arrangement, for improving combustion of air pulse fuel burner used for heater, comprises sleeve having thin wall and frontal orifice of dimension slightly greater to that of nose of burner

Info

Publication number: FR2800844A1
Application number: FR9914391A
Authority: FR
Original assignee: Muller et Cie SA
Current assignee: Muller et Cie SA
Priority date: 1999-11-08
Filing date: 1999-11-08
Publication date: 2001-05-11
Anticipated expiration: 2019-11-08
Also published as: FR2800844B1

Abstract

The device comprises a sleeve (3) for recirculation of burnt gas, in a tubular form, which is coaxial to the burner and disposed in front of the nose (2) of the latter, this sleeve having a thin wall and a frontal orifice of dimension slightly greater to that of the nose of the burner. The distance between the front orifice and the nose of the burner, and also the length L and the diameter D in front of this burner is determined as a function of the form and the volume of the combustion chamber (1), of the power of the burner and the angle of atomization of the fuel.

Description

DISPOSITIF POUR AMELIORER LA COMBUSTION D'UN BRULEUR A FIOUL A AIRPULSE La présente invention a trait aux brûleursà fioul à air pulsé et vise plus particulièrementà améliorer la combustion en favorisant une combustion plus complète et moins émettrice d'oxydes d'azote et de carbone. DEVICE TO IMPROVE THE COMBUSTION OF A BURNER A FIOUL A AIR PULSE The present invention relates to burners to fuel to pulsed air and more particularly aims to improve combustion by promoting a more complete combustion and less emitting oxides of nitrogen and carbon.

A cet effet, l'invention a pour objet un dispositif pour améliorer la combustion d'un brûleurà fioul à air pulsé, caractérisé en ce qu'il est constitué d'une bague de recirculation des gaz brûlés, de forme tubulaire, coaxiale au brûleur et disposée devant le nez de ce dernier, ladite bague présentant une paroi mince et un orifice amont de dimensions sensiblement supérieuresà celles du nez du brûleur, la distance entre ledit orifice amont et le nez du brûleur, ainsi que la longueur et le diamètre amont de ladite bague étant déterminés en fonction de la forme et du volume de la chambre de combustion, de la puissance du brûleur et de l'angle de pulvérisation, du gicleur de fioul. For this purpose, the invention relates to a device for improving the combustion of a burner to oil to pulsed air, characterized in that it consists of a recirculating ring burnt gases, tubular, coaxial with the burner and disposed in front of the nose of the latter, said ring having a thin wall and an upstream orifice of substantially larger dimensions to those of the nose of the burner, the distance between said upstream orifice and the nose of the burner, as well as the length and the upstream diameter of said ring being determined according to the shape and the volume of the combustion chamber, the burner power and spray angle, oil nozzle.

Sur la figure1 des dessins annexés, on a illustré le principe de réalisation du dispositif de l'invention. In Figure 1 of the accompanying drawings, the principle of embodiment of the device of the invention is illustrated.

En1 est schématisée la chambre de combustion d'un générateur de chaleurà fioul à brûleurà air puisé dont le nez du brûleur est schématisé en 2. La chambre1 ainsi que le nez 2 sont cylindriques et coaxiaux. In 1 is shown schematically the combustion chamber of a heat generator to fuel to burner to air drawn from which the nose of the burner is schematized in 2. The chamber 1 as well as the nose 2 are cylindrical and coaxial.

Conformémentà l'invention, il est prévu légèrement en avant du nez de brûleur 2 et coaxialement à celui-ci une bague de recirculation 3 de forme générale cylindrique età paroi mince, réalisée en tous matériaux appropriés tels que matériaux réfractaires, métalliques ou céramiques. Le diamètre de la bague3 est sensiblement supérieurà celui du nez 2 en sorte que les gaz brûlés puissent être (flèches 4) réintroduits en partie en amont de la bague3 à l'intérieur de celle-ci, dans le pied de flamme5, ces gaz brûlés étant mélangésà l'air neuf pénétrant dans la bague. According to the invention, it is provided slightly in front of the burner nose 2 and coaxially to it a recirculation ring 3 of cylindrical general shape and to thin wall, made of any suitable materials such as refractory materials, metallic or ceramic. The diameter of the ring 3 is substantially greater than that of the nose 2 so that the burned gases can be (arrows 4) reintroduced partly upstream of the ring 3 to the inside of it, in the foot of flame 5, these burned gases being mixed to the fresh air penetrating the ring .

Avantageusement et comme illustré par la figure 2 montrant en coupe la bague de recirculation 3, cette dernière présente un bord amont en forme de bourrelet annulaire6 à section aérodynamique sensiblement en goutte d'eau, le diamètre intérieur de l'extrémité amont de la bague3 n'étant pas réduit mais au contraire légèrement évasé pour supprimer les turbulencesà l'entrée et permettre,à section équivalente d'améliorer sensiblement le débit de recyclage (flèches 4) arrivant en pied de flamme5. Advantageously and as illustrated in FIG. 2, showing in section the recirculation ring 3, the latter has an upstream edge in the form of an annular bead 6 with an aerodynamic section substantially in droplet. water, the inner diameter of the upstream end of the ring 3 not being reduced but on the contrary slightly flared to remove the turbulence to the inlet and allow, to equivalent section significantly improve the recycling flow (arrows 4) arriving at the bottom of the flame 5.

La bague3 est également munie d'une série d'orifices7 de réintroduction partielle des gaz brûlés (flèches8) à l'intérieur de la bague pour accélérer le refroidissement de la flamme schématisée par les flèches9, entourée par la bague3. Cette accélération du refroidissement de la flamme viseà réduire la formation d'oxydes d'azote tout en complétant la combustion par l'oxygène résiduel qu'ils contiennent. The ring 3 is also equipped with a series of orifices 7 of partial reintroduction of flue gases (arrows 8) to inside the the ring to accelerate the cooling of the flame schematized by the arrows 9, surrounded by the ring 3. This acceleration of the cooling of the flame aims to reduce the formation of nitrogen oxides while completing the combustion with the residual oxygen they contain.

La figure3 illustre diverses formes et implantations des orifices7 qui sont répartisà intervalles réguliers dans un plan perpendiculaireà l'axe de la bague3 de préférence dans la demi-partie aval de cette dernière. Figure 3 illustrates various shapes and locations of 7 holes that are spread to regular intervals in a perpendicular plane to the axis of the ring 3 preferably in the downstream half-part of the latter.

Les orifices7 peuvent être circulaires (repère10), elliptiques ou ovales (repère11) ou rectangulaires (repère12). Ils peuvent être réalisés par emboutissage en direction du centre de la bague (repère13) le plan des orifices étant parallèleà la paroi de la bague3, ou encore réalisés de façonà former un canal 14 d'introduction en sifflet (flèche15) à l'intérieur de la bague3. Holes 7 may be circular ( 10), elliptical or oval ( 11) , or rectangular ( 1 </ B) > 2). They can be made by stamping towards the center of the ring (mark 13) the plane of the orifices being parallel to the wall of the ring 3, or even made to form a whistle introduction channel 14 (arrow 15) to inside the ring 3.

Les dimensions de la bague de reciréulation 3 ainsi que sa distance ou éloignementd par rapport au nez du brûleur 2 sont, comme illustré par la figure 4, déterminées,à savoir le diamètreD, la longueur L, ledit éloignementd ainsi que la distance1 entre le bord aval de la bague3 et l'alignement des orifices7, en fonction de la forme et du volume de la chambre de combustion 1, de la puissance du brûleur et de l'angle de pulvérisation du gicleur de fioul. Avantageusement, la bague3 peut comporter comme illustré par la figure5 un bord aval sinusoïdal16, la période de la sinusoïde correspondantà l'écartement entre deux orifices7 consécutifs et les pointes arrondies17 dudit bord aval se trouvant en regard d'un intervalle entre deux orifices7. The dimensions of the recirculation ring 3 as well as its distance or distance d from the nose of the burner 2 are, as illustrated in FIG. 4, determined, to know the diameter D, the length L, said distance d as well as the distance 1 between the downstream edge of the ring 3 and the alignment of holes 7, depending on the shape and volume of the burner 1, burner capacity and the spray angle of the fuel nozzle. Advantageously, the ring 3 can comprise as illustrated by the figure 5 a sinusoidal downstream edge 16, the period of the corresponding sinusoid to the distance between two consecutive 7 holes and the rounded ends 17 of the said downstream edge lying opposite an interval between two orifices 7.

Ces pointes arrondies17 créent des points chauds uniformément répartisà l'extrémité aval de la bague et qui contribuentà réduire le taux d'oxyde de carbone. La forme sinusoïdale ainsi que sa disposition par rapport aux orifices7 sont déterminées pour que lesdits points chauds(17) ne soient pas influencés par l'effet refroidissant des orifices7. These rounded tips 17 create uniformly distributed hot spots at the downstream end of the ring and help to reduce the carbon. The sinusoidal shape and its arrangement with respect to the 7 holes are determined so that the said hot spots (17) are not influenced by the cooling effect of the orifices 7.

Suivant encore une autre caractéristique du dispositif de l'invention, illustré par lafigure6, la zone annulaire18 de la bague3 munie des orifices7 est avantageusement légèrement rétreinte, un tel étranglement de la bague favorisant l'aspiration des gaz brûlés (flèches 4). According to yet another characteristic of the device of the invention, illustrated by the f igure 6, the annular zone 18 of the ring 3 with holes 7 is advantageously slightly shrunken, such a throttling of the ring favoring the aspiration of flue gas (arrows 4).

La bague3 peut par ailleurs avoir une forme ondulée en section comme illustré par la figure7, ou avoir une forme de révolution avec un diamètre en s'élargissant de l'amont vers l'aval, comme illustré par la figure8. The ring 3 can also have a wavy shape in section as illustrated by the figure 7, or have a shape of revolution with a widening diameter upstream downstream, as shown in Figure 8.

La bague3 peut aussi, quelle que soit sa forme, comporter intérieurement des nervures radiales19 comme illustré par la figure9, de préférence régulièrement distribuées.The ring 3 can also, whatever its shape, have internally radial ribs 19 as illustrated by the figure 9, preferably regularly distributed .

Claims

REVEN DI CATI ONS 1. Device for improving the combustion of a burner to fuel to pulsed air, characterized in that it is constituted of a ring (B) (3) of flue gas recirculation, of tubular form, coaxial with the burner and arranged in front of the nose (2) of the latter, said ring (3) having a thin wall and an upstream orifice of dimensions substantially greater than those of the nose (2) of the burner, the distance (d) between said upstream orifice and the nose ( 2) of the burner, as well as the length (L) and the diameter (D) upstream of said ring being determined according to the shape and volume of the combustion chamber (1) , of the burner power and the spray angle of the oil nozzle. 2. Device according to claim 1, characterized in that the recirculation ring (3) comprises an alignment of orifices (7) regularly distributed, to a specified distance (1) from the downstream edge of the (3) ring. 3. Device according to claim 2, characterized in that said orifice alignment (7) is arranged in the downstream half-portion of the ring (3). 4. Next device one of claims 2 or 3, characterized in that the orifices (7) have one of the following sections : circular, oval or rectangular. 5. Device according to one of claims 2 to 4, characterized in that the orifices (7) are arranged in a manner to constitute channels (14) for reintroducing the burnt gas whistle in the ring (3). 6. Device according to one of claims 2 to 5, characterized in that the (Il 8) area of the (7) hole alignment is a necking area. 7. Device according to one of claims 1 to 6, characterized in that the section of the ring (3) is corrugated. 8. device according to one of claims 1 to 7, characterized in that the ring (3) has a form of revolution. 9. Device according to one of claims 1 to 8, characterized in that the inner wall of the ring (3) comprises ribs Radial (Il 9). 10. Device according to one of claims 1 to 9, characterized in that the upstream edge of the ring (3) is shaped as a bead (6) aerodynamic section without reducing the upstream diameter of said ring. 11. Device according to one of claims 2 to 10, characterized in that the downstream edge of the ring (3) has a shape sinusoidal (16) each rounded tip (17) of said edge corresponding substantially to a gap between two orifices (7) consecutive ,