EP0586676B1 - Gas burner having a plurality of combustion heads - Google Patents

Abstract

A gas burner provided with a plurality of combustion heads and comprising at least one induced air inlet (2) in an air circulation enclosure (1), wherein said enclosure is divided into a number of compartments defined by spaced-apart walls (6a, 6b) extending through part of the vertical direction of the enclosure so that air can flow around and between said walls and into said compartments by passing around the free wall ends. Each compartment has an inverted combustion head (7a, 7b) with a mixing chamber (9a) communicating with said compartment and having a gas inlet (11a, 11b) and a combustion grate (8a, 8b).

Description

The invention relates to a gas burner with several combustion heads.

Generally, it is sought to increase the power of the gas burners, in particular for heating boilers. However, the maximum power has limits due to technical problems inherent in the manufacture of the burners themselves which must withstand extreme heating conditions, in particular temperature, pressure, ...

These power limits also appear due to the large loads on the heat exchanger.

In addition, a reduced diameter chimney to which the boilers are often connected, leads to overpressures at start-up, which does not make it easier.

It has also already been imagined burners with several heads, such as for example those described in FR-A-2 135 673, or even in FR-A-1 409 850, or US-A-4,614,491.

On the idea of a burner provided, as mentioned above, with several combustion heads and further comprising at least one forced air inlet in an air circulation enclosure, the inventor imagined a burner which is remarkable in that said enclosure is divided into several compartments produced by spaced walls which extend over part of the height of the enclosure so that air can circulate around and between said walls and reach said compartments bypassing the free ends of the walls, each compartment having its own inverted combustion head provided with a mixing chamber which communicates with said compartment and which is provided with a gas inlet pipe and a combustion grate.

Unlike the first two documents cited, the combustion heads are inverted and the enclosure is divided into compartments between the walls of which air can circulate. As for the aforementioned US document, this does not describe an air circulation enclosure, but a separate supply by combustion head.

According to one embodiment, the air circulation enclosure is formed by a cover through which the pipes pass. gas inlet, a side casing provided with at least one air inlet cuff, and a base forming a support for all the combustion grids of the combustion heads while the walls forming the compartments are cylindrical and s 'extend from the cover to the base while providing a space for the passage of air in said compartments.

Advantageously, the burner includes a general gas supply to which the gas inlet pipes of the combustion heads are branched.

Preferably, the gas inlet pipes, with the possible exception of one of them, are each provided with a solenoid valve so as to allow controlled ignitions of the various heads.

In this way, the invention makes it possible to design a burner easy to modulate in power, since it suffices to light the desired number of heads. In addition, starting is greatly facilitated since it is sufficient at the start to light a single head.

An advantageous embodiment of the invention is remarkable in that one of the combustion heads, called the ignition head, is provided with an ignition system and with a flame control system while the others so-called peripheral combustion heads are arranged around the ignition head in such a way that the combustion grids of the peripheral heads are each adjacent at least one location on the combustion grate of the ignition head so that the ignition of the peripheral heads is carried out by the flame of the ignition head and that it is therefore sufficient to light and control all the heads, of the only ignition system and of the only flame control system of said head d 'ignition.

Of course, it is always possible to imagine several heads each provided with a flame control system (or even a separate gas supply). In addition, if the gas supply prohibits isolating one or more heads from the immediate vicinity of a controlled head, then the aforementioned embodiment is not compulsory.

Many possibilities are conceivable and one can consider for example a burner comprising two heads arranged side by side, an ignition head and a peripheral head, or an ignition head arranged in line between two peripheral heads, or even a central ignition head around which several peripheral heads are concentrically arranged.

• la figure 1 montre en coupe partielle et en élévation un mode de réalisation d'un brûleur selon l'invention à deux têtes,
• la figure 2 est une vue de dessus du brûleur de la figure 1,
• la figure 3 montre en élévation renversée l'enceinte de circulation d'air de la figure 1,
• la figure 4 est une vue de dessus de la figure 3,
• la figure 5 montre en plan de dessus une alimentation de gaz pour un brûleur selon les figures 1 à 4,
• les figures 6 et 7 schématisent d'autres modes de réalisation respectivement à trois et cinq têtes,
  Sur les figures 1 à 4, on peut voir une enceinte 1 de circulation d'air pourvue d'une manchette 2 d'arrivée d'air.

The invention will be clearly understood on reading the description which follows and which refers to the appended drawings in which:

• FIG. 1 shows in partial section and in elevation an embodiment of a burner according to the invention with two heads,
• FIG. 2 is a top view of the burner of FIG. 1,
• FIG. 3 shows in inverted elevation the air circulation enclosure of FIG. 1,
• FIG. 4 is a top view of FIG. 3,
• FIG. 5 shows in top plan a gas supply for a burner according to FIGS. 1 to 4,
• FIGS. 6 and 7 show diagrams of other embodiments with three and five heads respectively,
  In Figures 1 to 4, one can see an enclosure 1 for air circulation provided with a sleeve 2 for air intake.

The enclosure 1 is formed by a cover 3 (below in FIG. 3), a side wall 4, and a base 5 (FIG. 1).

In enclosure 1, several compartments are arranged formed by spaced cylindrical walls, here two, 6a, 6b, which extend from said cover 3 towards the base 5 without touching it, and in each compartment is provided a combustion head. respectively 7a, 7b, called reverse. Each head is, for example, of a type similar to that described in FR-A-2 593 270, if we consider only said head itself, each of them being, as already said, fitted in a separate and separate compartment.

Each combustion head comprises an annular combustion grid such as 8a and 8b for the heads 7a and 7b, the grids being fixed to the base 5.

In addition, each head has a mixing chamber such as 9a into which a gas inlet pipe 11a, 11b opens and which communicates by a chimney 10a with the space of the compartment of the head considered.

The pulsed air which arrives through the cuff 2 in a substantially tangential manner (FIG. 2) in the enclosure 1 will circulate around the walls 6a, 6b and between them, while it may pass below said walls bypassing their ends. free to reach into said mixing chambers such as chamber 9a.

As shown in FIG. 2, the cover 3 has openings 12 and 13 for respectively an ignition electrode and an ionization flame control electrode which will be discussed below (not visible in FIG. 1 due to the cutting plane) and openings 14a, 14b for the passage of the aforementioned gas pipes.

The combustion head 7b provided with the ignition and flame control electrodes is hereinafter called the ignition head and the other head 7a, the peripheral head, these expressions being especially useful when there are more than two heads such as in the other embodiments which will be discussed below.

FIG. 5 shows an interesting distribution of gas on a burner of the type of that of the preceding figures provided with two combustion heads.

The gas comes from a general supply pipe 15 which arrives directly at the ignition head, therefore ending in the gas inlet pipe 11b and to which the gas inlet pipe 11a of the other head.

As still shown in FIG. 5, the pipe 11a is further provided with a solenoid valve 16.

It is understood from Figure 1 that the combustion grates of the heads 7a and 7b are adjacent. We can clearly see the grid 8a and we guess the location of the grid of the other head. Besides the partitions 6a and 6b (Figure 4) are almost tangent.

Consequently, if the head 7b is supplied with gas and its ignition electrode is put into operation, said head 7b will light up and may light up by its vicinity the head 7a as soon as the solenoid valve 16 will be opened.

It is thus possible to light one or two heads at will and to facilitate starting, delay the opening of the solenoid valve 16 in order to obtain successive ignitions of said heads.

It is understood that then only the head 7b requires flame control given the vicinity of the two heads.

For more than two heads, it is thus possible to provide a real cascade ignition.

To allow only one control electrode and only one ignition electrode to be provided, it suffices to place the peripheral head or heads in the vicinity, at least in one place, of the so-called ignition head.

By way of example, FIG. 6 shows an oblong envelope 1 ′ and diagrammatically shows an ignition head 7′b between two aligned peripheral heads 7′a and 7′c.

Figure 7 shows a circular envelope 1˝ and shows schematically an ignition head 7˝b surrounded by four substantially concentric peripheral heads 7˝a, 7˝c, 7˝d and 7˝e.

The ignition heads 7′b and 7˝b are recognized by the passages for the ignition and flame control electrodes.

In the case of FIGS. 6 and 7 it is obviously very easy to imagine the gas supply from FIG. 5.

However, it will also be understood that the head 7′a of FIG. 6 for example could be the ignition head and be the only one to have ignition and control electrodes insofar as it would be impossible to open the arrival of gas from head 7′c before that of head 7′b and closing the arrival of head 7′b before that of head 7′c.

In addition, other arrangements can be made with a sufficient number of ignition and / or control electrodes.

Finally, variants or other elements are not specially described here, such as secondary air inlets, baffles facilitating the air-gas mixture, ...

Claims (8)

1. Gas burner provided with a plurality of combustion heads and comprising at least one induced air inlet (2) in an air circulation enclosure (1, 1′, 1˝), characterised in that said enclosure is divided into a plurality of compartments formed by spaced walls (6a, 6b) which extend over a part of the height of the enclosure such that the air can circulate around and between said walls and reach said compartments by passing around the free ends of the walls, each compartment having its own inverted combustion head (7a, 7b, 7′a-7′c; 7˝a-7˝e) provided with a mixing chamber (9a) which communicates with said compartment and which is provided with a gas inlet pipe (11a, 11b) and a combustion grate (8a, 8b).
2. Burner according to claim 1, characterised in that the air circulation enclosure (1) is formed by a cover (3) through which pass the gas inlet pipes (11a, 11b), a side jacket (4) provided with at least one air inlet sleeve (2), and a base (5) forming a support for all the combustion grates (8a) of the heads (7a, 7b) while the walls (6a, 6b) forming the compartments are cylindrical and extend from the cover (3) towards the base (5), leaving a space for the passage of the air into said compartments.
3. Burner according to one of claims 1 and 2, characterised in that it comprises a general gas supply (15) off which branch the gas inlet pipes (11a, 11b) of the combustion heads.
4. Burner according to claim 3, characterised in that the gas inlet pipes (11a), with the exception of one (11b) of them, are each provided with an electromagnetic valve (16) so as to permit controlled ignition of the various heads.
5. Burner according to one of claims 1 to 4, characterised in that one of the combustion heads, referred to as the ignition head (7b; 7′b; 7˝b), is provided with an ignition system and a flame monitoring system while the other combustion heads, referred to as peripheral combustion heads (7a; 7′a, 7′c; 7˝a, 7˝c-7˝e), are disposed around the ignition head so that the combustion grates of the peripheral heads are each close to at least one location of the combustion grate of the ignition head such that the ignition of the peripheral heads is effected by the flame from the ignition head and that it is thus sufficient to ignite and monitor all the heads with the single ignition system and the single flame monitoring system of said ignition head.
6. Burner according to claim 5, characterised in that it comprises two heads (7a, 7b) disposed side by side, an ignition head (7b) and a peripheral head (7a).
7. Burner according to claim 5, characterised in that it comprises one ignition head (7′b) disposed in line between two peripheral heads (7′a, 7′c).
8. Burner according to claim 5, characterised in that it comprises one central ignition head (7˝b) around which a plurality of peripheral heads (7˝a, 7˝c, 7˝d, 7˝e) are disposed concentrically.

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