EP0009831B1 - Atmospheric gas burner with groups of vents for the passage of the mixture of combustible gas and combustion air - Google Patents

Description

The subject of the invention is an atmospheric gas burner and in particular for liquefied gas comprising a hollow elongate element as a gas-tight burner body at one of its ends and comprising a gas and primary air inlet at the other end. mixture consisting of gas and primary air passing through a gas supply tube narrower than the hollow elongate element and extending in said element to which it is fixed in a gas-tight manner, the upper convex part of the hollow elongate member having several slots oriented perpendicular to its longitudinal axis and each having a width of 0.5 mm, said slots being arranged parallel to each other in rows perpendicular to the longitudinal axis with the same spacing and forming axially separated groups, each group comprising several sub-groups and each row of slots also comprising holes.

Such burners are known from the publication GB-A-1462985. The primary difficulty in designing atmospheric gas burners is to provide the burners with groups of slots for the passage of a gas-air mixture for primary combustion which are closely related to each other and which are established very small dimensions thus ensuring a uniform flame front and avoiding any vibration thereof and at the same time eliminating a very painful factor of acoustic discomfort and giving the flames a greater regularity which will lead in the end to a better performance specific combustion.

According to another characteristic of the invention, particularly advantageous when using combustible gases at low flame propagation speed, in particular when high flame power is required, which causes a high speed of exit of the gas-air mixture. primary, pilot flames must be provided through an empty space formed between an outer sheet perforated at the level of the flame passage and the sheet which forms the body of the burner, the latter comprising groups of relatively close openings established at small dimensions for the passage of the fuel mixture.

The above-mentioned empty space is supplied with a primary gas-air mixture which leaves the passage holes of reduced section at low speed, thus producing great stability of the flame.

In general, specific high-power gas burners provide numerous openings for the gas outlet, each of these forming an independent flame front independent of the others. Very often these openings are brought together in groups to ensure a satisfactory supply of the flame with secondary air. Until now, due to technological difficulties, the center distance between the openings is never less than 2 mm, so that the phenomenon of flame vibration appears which produces a very annoying noise.

This noise frequency can be very high and for this reason extraordinarily unbearable and can also destroy the places where noise is produced.

The object of the invention is to provide a burner dimensioned for large flame powers without producing unpleasant vibrations for the human ear.

The solution to this problem according to the invention consists in that the hollow elongate element is cylindrical, the gas supply tube is a venturi tube and the slots in a group in the direction of the burner axis have a distance between -axis of 1.2 mm and that the spacing between the slots, of two neighboring subgroups positioned on the convex upper part of the cylinder, in the direction of its circumference, is 2 mm, that the holes being exclusively positioned at each end of a row of slots in the circumferential direction.

It appears from the experiments carried out that such a burner does not produce an unpleasant noise, which eliminates all the acoustic disadvantages immediately.

It has also been found that there is a considerable flame stabilization factor which regulates the flame itself so that combustion is more efficient.

Furthermore, by the present invention the prejudice that the slots could not be brought closer than with a spacing of 2 mm has been overcome.

The pilot flames supplied through the lateral empty spaces contribute very significantly to the stabilization of the main flames, even at very high flame powers. There is also obtained the non-negligible advantage of significant cooling of the sheet which forms the main body of the burner, this cooling being provided by the mixture which feeds the pilot flames through the lateral empty spaces.

• Figure 1 est une vue de côté avec arrachement, montrant une première forme de réalisation du brûleur suivant l'invention.
• Figure 2 est une vue en plan par dessus représentant à échelle agrandie une partie de ce brûleur.
• Figure 3 est une coupe schématique illustrant la formation d'un éventail de flamme en vis-à-vis d'un groupe d'ouvertures du brûleur.
• Figure 4 est une vue de côté analogue à celle de fig. 1, mais correspondant à une autre forme de réalisation du brûleur suivant l'invention.
• Figure 5 est une vue en plan à échelle agrandie d'une partie de la paroi du brûleur suivant fig. 4.
• Figure 6 est une coupe transversale suivant le plan indiqué en VI-VI en fig. 5.

The attached drawings show examples of the invention which make it possible to specify the additional advantages of the invention.

• Figure 1 is a side view with cutaway, showing a first embodiment of the burner according to the invention.
• Figure 2 is a plan view from above showing on an enlarged scale a part of this burner.
• Figure 3 is a schematic section illustrating the formation of a flame fan opposite a group of burner openings.
• Figure 4 is a side view similar to that of FIG. 1, but corresponding to another embodiment of the burner according to the invention.
• Figure 5 is a plan view on an enlarged scale of part of the wall of the next burner fig. 4.
• Figure 6 is a cross section along the plane indicated in VI-VI in fig. 5.

In the first embodiment illustrated in FIG. 1 to 3, the burner comprises a cylindrical body 1 which is supplied with combustible gas by a nozzle 2 forming Venturi and associated with a nozzle 3, and with primary combustion air through passages 4.

The lateral surface of the cylindrical body 1 is pierced with openings for the flow of the mixture, these openings being grouped into several groups of slots 5 (fig. 2) having a minimum width and a reduced length, which slots are arranged parallel to each other. coast by forming subgroups.

Each slot 5 has a width of 0.5 mm and a length of 6 mm with a center distance of 1.2 mm, the sub-groups being spaced 2 mm apart; at each end of the lines formed by these sub-groups is provided a series of pilot openings 6, respectively 7, which are intended to ensure the stabilization of the flames. The groups of openings are spaced from each other by a distance of about 15 mm.

In any event, the arrangement indicated above makes it possible to produce a range of flames 8 (fig. 3) having a dark blue color, the flame front 9 of which, in bright blue tint, is unique for all of the openings. or group slots, with the advantages indicated above in addition to a very high primary aeration rate.

In the variant embodiment illustrated in FIG. 4 to 6, the burner also comprises a cylindrical body, here referenced 11 (fig. 4), which has on its upper wall groups of slots 12 very close together, in the same arrangement as that previously described with reference to fig. 1 to 3.

On the upper part of the body 11 is welded a sheet 13 cut out of openings 14 through which pass the flames which come from the individual groups of slots 12 intended for the emission of the combustible mixture. Particularly advantageously, the sheet 13 can in fact be constituted by the sheet itself which forms the body 11, the latter being simply extended in its circumferential development by means of folds 15 and 16 (fig. 6) formed on the sides of the raised part. of said sheet. In such a case, welds 17 and 18 are provided, for example by spots, on the edges of the sheet immediately adjacent to the folds 15 and 16 mentioned above.

Openings 19 and 20 of relatively reduced amplitude are formed on the bottom wall of the sheet metal which constitutes the body 11 of the burner, these openings being intended to allow the supply of combustible mixture at low space flow speed. empty intermediate between the sheet or body 11 and the sheet 13. This mixture supplies the pilot flames emitted through the openings 14 to lick the sides of the main flames coming out of the slots 12.

Here again, great stability of the main flames is obtained, the characteristics of which are identical to those indicated with reference to FIG. to 3.

As indicated at the beginning of the present document, another advantage obtained lies in the secondary effect of cooling the upper part of the sheet which forms the body 11 of the burner, and this in particular in the parts adjacent to the groups of slits 12 which are licked by the mixture from the openings 19 and 20 and circulating in the free space formed between the sheets 11 and 13. The useful life of the burner is thus considerably increased.

Claims (2)

1. Atmospheric gas burner, in particular for liquid gas, the burner body being a long extended hollow element (1, 11) which is gas-tight on its one end and disposing of an open gas admission (entry) on its opposite end, the burner body being supplied with a mixture of primary air and gas passing through a gas-feed-tube (2) being narrower than the long extended hollow element (1, 11) and reaching into said element with a gas-tight connection thereto, the convex upper part of the long extended hollow element (1, 11) comprising a number of vents (5) being situated perpendicularly on its longitutinal axis, each having a width of 0,5 mm and being arranged in parallel manner in the perpendicular rows on the longitudinal axis with equal distances between the individual vents and forming groups axially separated, each group comprising a number of sub-groups and each row of vents (5) comprising additional holes (6, 7), characterised in that the long extended hollow element (1, 11) being a cylinder, the gas-fee-tube (2) being a venturi tube and the vents (5) in a group having a distance of 1,2 mm and the distance between the vents (5) of the two annexed sub-groups situated on the convex upper part of the cylinder in the direction of his circumference being 2 mm, the holes (6, 7) being arranged only on each end of a row of vents (5) in direction of the circumference of the cylinder.

2. Gas burner according to claim 1, characterised in that an additional metal sheet (13) comprising openings (14) being situated above the upper convex part of the cylinder (11) which covers the pilot holes (6, 7) and uncovers the groups of vents (5).

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