EP1172607A1 - Gas burner with increased power - Google Patents

Abstract

The burner (10), comprising a body (12) with a support (14) having main flame outlets (17) and a feed system for a mixture of fuel gas and oxidant air, incorporates an auxiliary combustion system with one or more injectors (32) for more or less pure gas, producing secondary turbulent jet flames. The support (14) has a head (15) of circular section, and the auxiliary injectors are positioned concentrically round it.

Description

The field of the invention is that of gas mixture burners fuel and combustion air, in particular with air induction and partial premixing of gas and air, such as burners for industrial or private ranges.

In this area, we already know burners of the type comprising a body equipped with at least one flame support means provided with openings for the passage through them of ignited gases in order to form main flames, and a mixture supply system of combustible gas and combustion air connected to the flame support means. These very typical burners like those with circular blue flames (or crown) with atmospheric air induction and partial premix, have various drawbacks notably linked to their surface yield often insufficient (in particular in professional use) and / or pollution (discharge of polluting gases). The evolution of market demand leads to a share in wanting to increase the maximum power of these burners while retaining their size, i.e. the ratio power / dimensions, and on the other hand to increase the range of use (called "flexibility") which is the ratio between the maximum power and the minimum power available on the burner. Given the constraints standards in terms of polluting emissions (CO in particular), operational safety constraints and the state of the art there becomes difficult to increase the power density for a dimension (diameter for example) of given burner.

WO-A-98 30838 describes an improvement to this type of burner, the burner further comprising means combustion auxiliaries to send a gas flow substantially in direction of said main flames with the ignited gases of which it mixes to create secondary flames that develop between main flames, or as a result thereof, so as to bring about an increase of power by means of flame support with which the means combustion auxiliaries cooperate.

This association of two means of heat production is simple to implement and allows a gain of power at the level of mixture of main and secondary flames.

However, the invention aims to obtain a power density at level of main burner flames, much higher than that provided by a burner, as described in WO-A-98 30838, combining two means of different combustion through which escapes the same mixture gaseous.

It also aims to offer a simple, reliable, practical solution and inexpensive. To do this, it proposes that the auxiliary means of combustion include at least one fuel gas injector substantially pure giving rise to secondary jet-shaped flames turbulent.

The turbulent jet thus created in the immediate environment of main flames allows improved combustion due to its speed which results in better mixing of the surrounding air. Other said, burning the secondary flames and burning the mixture of combustible gas and combustion air interact, which increases the power density provided by a combustible air mixture burner and oxidizing gas for a given level of pollution. In addition, the air circulation increases the heat transfer coefficient to the container heat (pan for example).

• des moyens pour déclencher l'ouverture de l'alimentation en gaz combustible des moyens auxiliaires de combustion uniquement lorsque les moyens support de flammes sont à puissance maximum, et
• des moyens pour déclencher la fermeture de l'alimentation en gaz combustible des moyens auxiliaires de combustion lorsque la puissance du moyen support de flammes passe sensiblement sous ladite puissance maximum.

In order to optimize the ignition of the auxiliary combustion means, it is provided that the burner supply system includes:

• means for triggering the opening of the supply of combustible gas to the auxiliary combustion means only when the flame support means are at maximum power, and
• means for triggering the closure of the supply of combustible gas to the auxiliary combustion means when the power of the flame support means passes substantially below said maximum power.

Thus, the auxiliary combustion means will not start only works when the power of the main burner is reached, so that "boost" this burner all at once, for example to increase very quickly power under a pan of water to heat, all without increase the size of the burner.

For reasons related to the flexibility of use and the ease of design and manufacture of the burner, it is intended that the support means of flames are constituted by a combustion head supplied by a power mixture source adjustable in power, the main flames being then modular and then developing around the periphery of this head, at level of the openings for the passage of ignited gases, and that the means combustion auxiliaries are then all or nothing type adjustment (open closed).

In particular, for a better distribution of the flames, the head combustion will preferably be circular and the injectors will be then placed on a concentric circle with the combustion head and inclined at a non-zero angle with the vertical, the radius of the circle and the angle of inclination then being chosen so that the injectors point in the direction of the end of the main flames coming out of the combustion head. The injectors may in particular be four in number regularly distributed in a circle and they will point to the exit ports of the head circular of the burner, more precisely towards the end of the flames main coming out of this head so that the pure gas coming out of injectors is propelled towards the end of said main flames.

According to an alternative embodiment, the combustion head may be annular and have suitable gas mixture passage openings so that the main flames develop towards the center of said head, and the injectors will then preferably be located inside this ring and oriented centrifugally, towards the main flames, at the level from their end. This structure further reduces the size of the burner because the injectors are arranged inside the head.

In particular, for the sake of compactness of the device, the head of combustion can directly integrate the injectors of the auxiliary means combustion.

The invention also relates to a cooking appliance (such as a stove) or heating (water heater) equipped with a burner as described, with its auxiliary combustion means.

• la figure 1 est une vue en perspective d'un brûleur conforme à l'invention,
• la figure 2 est une vue du dessus du brûleur de la figure 1,
• la figure 3 est une vue de côté de la figure 1,
• la figure 4 est un schéma d'alimentation en mélange de gaz pour le brûleur des figures précédentes, et
• la figure 5 est une vue en coupe d'une variante de réalisation de la figure 1.

The invention and its implementation will appear even more clearly with the aid of the description which follows, made with reference to the drawings in which:

• FIG. 1 is a perspective view of a burner according to the invention,
• FIG. 2 is a top view of the burner of FIG. 1,
• FIG. 3 is a side view of FIG. 1,
• FIG. 4 is a diagram of the supply of gas mixture for the burner of the preceding figures, and
• FIG. 5 is a sectional view of an alternative embodiment of FIG. 1.

As can be seen in FIG. 1, the invention relates to a gas mixture burner 10 comprising a body 12, typically made of metal (for example in cast aluminum) on which a means 14 is mounted flame support in the form of a substantially 15 combustion head horizontal, for example in brass, provided with a cap 16. This head combustion 15 is for example here of circular section with center A, as we can see it more precisely on figure 2. It is also pierced several lateral orifices 17 (see FIG. 3) adapted to allow the passage of a premix of ignited gases (natural gas and air) for the formation of main F (or primary) flames which develop in crown shape around the head. The burner 10 also includes a supply system 20 connected in particular to the combustion head. It is described in more detail later using Figure 4.

As can be seen, the burner 10 is also provided with auxiliary (or secondary) combustion means 30 presented under the form of one or more injectors 32 projecting from the body. These injectors 32, for example four in number arranged concentrically around the combustion head in a circle with center A and radius R, are supplied with substantially pure combustible gas (i.e. does not substantially comprising only combustible gas, or at least no gas oxidizer) at a preferably constant pressure. They are independent of the combustion head 15 and operate all or nothing, while the combustion head combustion is on the contrary adjustable in power so as to give birth of modular flames F. These injectors 32 cooperate closely with the combustion head 15 so that a localized additional power when desired. For this, the injectors 32 are provided to send a flow of pure gas directed towards the gases in combustion forming the flames emerging from the combustion head, and in particular towards point H, at the end of the main flames (see figure 5).

It can be noted that the injectors 32 can be tilted by making a non-zero angle α (positive or negative) with the vertical, for example if we move the injectors a little further from the center of the head by increasing the radius R of the circle they are on. It is best to always choose a circle diameter and an angle α of inclination such as the gas jet leaving the injectors 32 point towards the combustion gases forming the flames main so that it mixes with these, and preferably towards the end point of said main flames so that secondary flames F 'can be created correctly following or between the main flames, by interignition with them (main flames then become "pilot" flames of secondary flames).

In the alternative embodiment of FIG. 5, the injectors 32 are directly mounted on the combustion head 15 and no longer on the body 12. In this case, the head 15 is preferably annular and the main flames are directed towards the center A of the head, while the injectors are placed in the middle of this ring and directed preferably, as for the solution preceding, in direction, from the end point of the main flames. The injectors 32 may also be inclined at an angle α with the vertical, and a minimum distance from the peripheral orifices of the head must still be respected for questions of performance.

In Figure 4, there is shown a descriptive diagram of the system burner supply. This system 20 includes a first line 21 gas supply (natural gas for example) which supplies the mixing device (atmospheric air + natural gas) of the head combustion 15 and which is controlled by a safety valve 22 linked to a thermocouple 23. A second line 24 derives from the first line 22 of so as to supply the injectors 32 with pure gas. The gas inlet to the injectors 32 is controlled by the user using a solenoid valve 26 and an on-off switch 25. To ensure maximum safety, the admission of gas to the injectors is only authorized when the head of combustion is at full flow thanks to a pressure switch 27 connected to the line main 21. The on / off button can therefore only be pressed when the pressure switch has detected that the combustion head is at maximum power.

The operation of this improved burner, which can example be mounted on a traditional gas stove (for housing) or professional (industrial kitchen), is very simple. When the user wish to quickly increase the heating power of the burner under a dish or saucepan, it first puts the medium flame support in the maximum power by turning an adjustment knob provided for this effect. Then it activates the solenoid valve 26 and the on-off switch 25 (of type "all or nothing" therefore). This has the effect of injecting pure gas into direction of the main flame crown. It then creates a jet turbulent gas which mixes with the burning gas flames main, causing the creation of secondary flames F 'which come add to main flames. The interignition which is created between the main flames and secondary flames helps stabilize the assembly and ensure high efficiency and emission combustion reduced pollutant (CO, Nox). At the place of the main flames, there is therefore a significant increase in power which allows, without increasing the dimensions of the combustion head, to heat a very quickly. The heat density present under the container is therefore markedly increased compared to the burners of the prior art.

Once the container and its contents are warm enough, just slightly reduce the power of the combustion head. The pressure switch detecting a pressure drop below the maximum pressure, it automatically cuts off the gas inlet to the injectors, and the burner works again in normal mode, the effect "occasional increase of power "disappearing. Of course, the user can, if he wishes, control the injectors themselves using the start / stop button.

For example, for a combustion head having a maximum power of 5.2 kW and a minimum power of 1.5 kW, it has been possible, using the injectors presented above, a power maximum of 7.5 kW with flexibility increasing from 3.4 to 5, a time of temperature rise reduced by 30% and a standard output rising from 55% to more than 60%. This is particularly due to the fact that the gas flow pure fuel coming out of the injectors is turbulent, which has the effect increase the heat transfer coefficient towards the container to heat.

This burner is therefore extremely simple to use as well as design. It is adaptable to many types of cooking appliances or heating (not shown), whether stoves, space heaters gas, water heaters or other appliances with premix burners partial or total which may require an increase in power easy to get.

Furthermore, the additional cost of manufacturing such a burner is very weak, it can be cleaned or dismantled as easily as a burner normal, it works in a safe and reliable way, it is little polluting. Finally he has increased flexibility of use.

Of course, the invention is in no way limited to the modes of achievements presented as an example. So the head, and therefore the burner at complete, may have a shape other than circular or annular. The number and position of the injectors can also vary, in particular depending on the shape of the head. Other gases can also be used for the place of natural gas such as petroleum gases or manufactured gases, for example.

Claims (7)

Burner (10) comprising: a body (12) equipped with at least one flame support means (14) provided with orifices (17) for the passage through them of a mixture of ignited gases in order to form main flames (F), and a supply system (20) for a mixture of combustible gas and combustion air connected to the flame support means (14), auxiliary combustion means (30) for sending a gas flow (G) substantially in the direction of said main flames with the ignited gases from which it mixes to create secondary flames (F ') which develop between the main flames (F), or as a result thereof, so as to provide an additional power by means (14) flame support with which the auxiliary combustion means (30) cooperate, characterized in that the auxiliary combustion means (30) comprise at least one injector (32) of substantially pure combustible gas giving rise to the secondary flames (F ') in the form of a turbulent jet. Burner (10) according to claim 1, characterized in that the supply system (20) comprises: means (25, 26, 27) for triggering the opening of the fuel gas supply to the combustion auxiliary means (30) only when the flame support means (14) are at maximum power, and means (25, 26, 27) for triggering the closure of the supply of combustible gas to the auxiliary combustion means (30) when the power of the flame support means (14) drops substantially below said maximum power. Burner (10) according to any one of the preceding claims, characterized in that : the flame support means (14) consist of a combustion head (15) supplied by a source of mixture of combustible gas and oxidizing air adjustable in power, the main flames (F) then being modular and then developing on the periphery of this head, at the orifices (17) for passage of the mixture of ignited gases, and the auxiliary combustion means (30) are of all or nothing type. Burner (10) according to claim 3, characterized in that : the combustion head (15) is of circular section, the injectors (32) are arranged concentrically with the combustion head in a circle having a radius (r) and they are inclined at an angle (α) with the vertical, and the radius (r) of the circle and the angle (α) of inclination are chosen so that the injectors (32) point towards the end point (H) of the main flames (F). Burner (10) according to claim 4, characterized in that the combustion head (15) is of the annular type and has orifices (17) for the passage of the gas mixture suitable for the main flames (F) to develop towards the center (A) of said head (15), and the injectors (32) are located inside the ring and oriented centrifugally, towards the end point (H) of the main flames (F). Burner (10) according to any one of claims 3 to 5, characterized in that the combustion head (15) directly integrates the injectors (32) of the auxiliary combustion means (30). Cooking or heating appliance equipped with a burner (10) according to any one of the preceding claims.

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