EP2041492A2

EP2041492A2 - Burner the direction and/or size of the flame of which can be varied, and method of implementing it

Info

Publication number: EP2041492A2
Application number: EP07823552A
Authority: EP
Inventors: Bernard Zamuner; Nicolas Docquier; Bernard Labegorre; Thomas Lederlin; Thierry Poinsot; Vincent Faivre
Original assignee: Centre National de la Recherche Scientifique CNRS; Air Liquide SA; LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
Current assignee: Centre National de la Recherche Scientifique CNRS; Air Liquide SA; LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
Priority date: 2006-07-06
Filing date: 2007-07-05
Publication date: 2009-04-01
Anticipated expiration: 2027-07-05
Also published as: WO2008003908A3; ES2604078T3; JP5221532B2; BRPI0714153A2; US20100068666A1; PL2041492T3; EP2041492B1; WO2008003908A2; CN101484752B; RU2433343C2; FR2903479A1; RU2009103903A; CN101484752A; JP2009543012A

Abstract

Burner comprising at least one passage (10) for injecting at least a primary jet, such as a jet of oxidant and/or fuel and/or of a premix of oxidant and fuel, and means (21) of injecting at least one secondary jet of fluid (2) opening into said passage, the interaction between the primary jet and the at least one secondary jet making it possible to vary the direction and/or the size of the flame. Use of said burner for heating a charge with the variable-direction and/or variable-size flame.

Description

Flame burner with direction and / or variable opening and method of implementation

The present invention relates to a burner for varying the direction and / or the opening of the flame, said burner comprising at least one injection channel of at least one main or primary jet and at least one injection channel. an actuator or secondary jet. The primary jet is typically a jet of oxidant and / or fuel and / or a comburent-fuel premix.

It also relates to the use of said burner to vary the direction and or the opening of a flame. It also relates to a method of heating a load with the aid of this burner in which the direction and / or the opening of the flame is varied.

Context of the invention

The majority of industrial furnaces or boilers use burners that operate in non-premixed combustion mode, ie in which the oxidant and the fuel arrive separately to the combustion site. The mixture of the fuel and the oxidant is then carried out, in part (attachment of the flame in a quarry block or a prechamber) or in whole, inside the combustion chamber. This mixture is controlled by the design and operating parameters of the burner, and determines the performance of the burner (operating range, heat transfer to the load to be heated, emission of pollutants, etc.). In practice, the burner design determines the interaction conditions of the different jets or flows of oxidant and fuel used by the burner. Once the burner is completed, only the operating conditions can be modified. This is also true for so-called "premix" burners in which the oxidant / fuel mixture is produced in the burner upstream of the furnace. The reagents are then injected by a single tube. The operating conditions of industrial combustion processes may change over time. This is by nature the case of intermittent processes but it is also the case of continuous processes for which the characteristics of the charges to be heated can vary according to the production needs. This is more generally the case for any production unit subjected to aging or sensitive to the variable conditions of their environment. To adapt the performance of the burners to varying operating conditions, the operator usually has only two parameters: the operating power of the burner and the level of excess oxidant (oxygen surstœchiometry).

Some combustion technologies allow discrete modes and in very limited number of operation. This is for example the case of so-called "double pulse" burners that use two different injection systems depending on whether one wants to operate the burner at low or high impulse. These two modes of operation make it possible to increase the range of operation or use of the burner or to modify for a given operating point the length of the flame.

However, the modifications of the point and / or the mode of operation are most often insufficient to optimize under all conditions the performance of the burners or processes using these burners. For example, the cyclic introduction into a solid-temperature melting furnace at ambient temperature will cause the operator (or the control system) to increase the heating power so as to obtain the fastest possible melting (with a view to 'increase productivity', but without degrading the melt load (product quality) or overheating the oven (equipment life). This compromise between productivity and quality and / or life depends in particular on the ability of the system to transfer energy to the load, avoiding local overheating thereof or furnace refractories. This compromise results in a melting time below which any productivity gain will be counterbalanced by a degradation of the quality of the product or by reducing the life of the oven. It is known from WO-A-9744618 a burner having a central jet of fuel first surrounded by a plurality of primary oxidant jets, then a plurality of secondary oxidizer jets. It is thus possible in operation to change the position of the flame. However, the maximum deflection of the flame is in practice limited to about 15 ° from the median position to the extreme position (not more than 30 °), not allowing the incident flame to scan a large surface of a charge and the construction of the corresponding burner is relatively heavy since it requires a plurality of orifices for the primary oxidant jets and a plurality of orifices for the secondary oxidant jets.

In addition, the properties of the flame change according to its position since the properties of the mixture vary with the angle of incidence ("external" mixture to the burner block), which induces a variation of the polluting emissions, the quality of the radiative transfer (flame brightness) and flame length (heat release peak position).

Object of the invention

The invention relates to a burner allowing a large variation in the direction and / or the opening of the flame and this without having to interrupt the operation of the burner or oven. The invention also aims to allow such variation with an optimized robust burner.

Brief description of the invention

The invention proposes to control the direction and / or the opening of a flame by the interaction of a jet of fluid (called primary jet or main jet) with at least one other jet of fluid (called secondary jet or jet actuator), the interaction between the jets occurring inside the means delivering this main jet (tube, aperture, etc.) before said main jet emerges from said means. The burner according to the invention comprises a passage for bringing a primary jet towards a main outlet opening. The primary jet is typically a jet containing fuel, oxidant or a fuel-oxidant premix. The burner also has at least one secondary pipe for the injection of a secondary jet. The fluid injected by the secondary jet may or may not belong to the same category as the fluid of the primary jet. The fluid injected by the secondary jet may or may not be different from the fluid of the primary jet. The secondary jet may especially be an inert jet such as water vapor or combustion products, such as recycled fumes.

The at least one secondary pipe opens on the passage of the primary jet through a secondary opening located upstream of the main outlet opening. The secondary pipe is positioned relative to the passage so that at the point of interaction (center of inertia of the imaginary surface common to the two flows) between the secondary jet from this secondary pipe (hereinafter called: jet corresponding secondary jet) and the primary jet, the angle θ between the axis of the corresponding secondary jet and the plane perpendicular to the axis of the primary jet is greater than or equal to 0 ° and less than 90 °, preferably from 0 ° to 80 °, more preferably from 0 ° to 45 °. When the angle θ = 0 °, which is preferable, the axis of the corresponding secondary jet is located in a plane perpendicular to the axis of the primary jet. The at least one secondary opening is spaced from the main opening by a distance L less than or equal to ten times the square root of the section s of the main outlet opening, preferably L <5 ^* Vs, preferably L <3 ^* Vs.

The Proceedings of FEDSM'02 US Joint ASME-European Fluid Engineering Division Summer Meeting of JuIy 14-18, 2002 and the article "Experimental and numerical investigations of jet active control for combustion applications" by V. Faivre are known. and Th. Poinsot, Journal of Turbulence, Volume 5, No. 1, March 2004, p. 25, to use a specific configuration of four secondary jets around a main jet to stabilize a flame through the interaction between the secondary jets and the primary jet. A wider dispersion angle is found. According to the invention, the burner is provided with means for controlling the pulse of the at least one secondary jet. As explained in more detail below, the invention thus makes it possible to vary the direction and / or the opening of the flame coming from the burner by modifying the pulse of at least one secondary jet with said means. Preferably, the means for controlling the pulse of the at least one secondary jet are means for controlling the ratio between the pulse of the secondary jet and the pulse of the primary jet.

The invention thus makes it possible to achieve a large variation in the direction and / or opening of a flame without resorting to mechanical means, potential sources of malfunction, especially in hostile environments, such as high temperature fireplaces and / or polluted or corrosive atmosphere.

The control means allow in particular an active or dynamic control of the pulse of the at least one secondary jet, that is to say, they allow to vary the pulse or pulses without interrupting the burner operation / without interruption of the flame. The apparatus according to the invention thus allows an equally dynamic variation of the direction and / or the opening of the flame. Preferably, the number of secondary jets interacting with the primary jet to obtain the desired effect on the flame will be minimized so as to limit the complexity and the cost of manufacturing the burner but also the complexity and the cost of the feed system and fluid flow control if piloting the secondary jets independently. For example, a one-way effect can be achieved with a single secondary jet. Among the terms used in the present description, some deserve to be more precisely defined within the scope of the invention in order to better delimit their scope:

The direction of a jet / flame is defined as a unit vector normal to the fluid / flame passage section and oriented in the direction of flow, i.e. upstream to downstream.

• The "thickness e" means the dimension of the secondary pipe in the direction of flow of the primary jet (according to the arrow in figure 1). In the particular case of this FIG. 1, e therefore represents the diameter of the secondary pipe 21 at the secondary opening 31 since this secondary pipe 21 is cylindrical in this example.

The "opening" of a jet / flame designates, for a jet / flame emerging from a cylindrical passage such as 10 in FIG. 1, the angle between the longitudinal axis of the passage and the generator. on the surface of the jet / flame leaving the passage. In the absence of interaction with a secondary jet the generatrix is inclined by about 10 to 15 ° with respect to this axis, this inclination being able to reach 70 ° and more according to the invention (see FIG. 9A). By extension, the term "opening" will refer to the angle between the direction of flow in the passage, when it has no circular section, and the generator.

Detailed description of the invention

The various characteristics of the embodiments of the burner according to the invention and its use will appear more clearly from the following detailed description, reference being made to the figures which show, schematically, embodiments, given in a non-limiting manner, and more especially:

Figure 1: schematic diagram of a burner (premix) according to the invention for the control of a flame by interaction of jets.

Figure 2: control of a burner according to the invention mounted on a fireplace. FIGS. 3A and B: burner for controlling the direction of the flame, FIG. 3A being a cross-section and FIG. 3B a longitudinal section of a burner comprising four secondary jets disposed respectively at 90 ° from each other and coming into perpendicular to the direction of the primary jet.

3C, D and E: use of a pellet for converting a nozzle with primary and secondary jets parallel to a burner according to the invention. Figures 4A and B: longitudinal and transverse section of a burner for controlling the opening of a resulting jet.

- Figure 5: use of a burner to vary a flame by means of two jets (resulting), a jet of fuel and an oxidant jet. - Figure 6: burner type "tube in tube" with a quarl.

- Figures 7A, B and C: separate jet burner.

Figure 8: density of heat flux of the flame as a function of the distance to the injection point, under different incidences. - Figures 9A and B: alternative embodiments of the control of the opening of the flame.

- Figures 1OA and B: impact of a control parameter on the deviation of the flame and the heat transfer to a load.

- Figure11: opening angle of the flame according to the jet pulse ratio.

Figure 12: an example of application of the system of the invention to the heating of a load with change of incidence of the flame. Figure 13: Use of the invention to heat a load by moving the flame laterally. - Figure 14: application of the variable opening of a flame to drive the gases of an oven.

- Figure 15: level of emission of a flame according to a control parameter.

Figure 16: Protection of the end of the burner by a quarl. - Figure 17: protection of the end of the burner by a sleeve.

In the following, the same reference numbers are used, on the one hand, to designate the primary jet and the passage in which it flows and, on the other hand, to designate the secondary jet or actuator and the secondary line. in which this secondary jet flows.

In Figure 1 is shown a schematic diagram of the method of controlling a flame in a burner according to the invention.

The burner comprises a passage 10 which makes it possible to bring the primary jet towards a main outlet opening 11. The primary jet is led through the passage 10 and comes to interact with the secondary jet coming from the secondary pipe 21 so as to create downstream of the outlet opening 11 a flame 1 direction and / or opening different from the direction and / or the opening of the flame in the absence of secondary jet. At least one secondary pipe 21 for injecting a secondary jet opens onto the passage 10 through a secondary opening 31. This secondary pipe 21 is positioned relative to the passage 10 in such a way that at the point of interaction between the jet corresponding secondary and the primary jet, the angle θ between the axis of the secondary jet 21 and the plane perpendicular to the axis of the primary jet 10 is greater than or equal to 0 ° and less than 90 °. (θ = 0 ° in Figure 1). The secondary aperture 31 is spaced from the main aperture 11 a distance L, L being less than or equal to 10 x Vs (s = section of the main aperture 11). The distance L makes it possible to influence the impact of the secondary jets on the primary jet with identical respective pulses. For example, to maximize the directional effect, we will try to minimize this distance. As a general rule for oxygen burners and developed powers of the mega-watt range, the length L is less than or equal to 20 cm, more preferably less than or equal to 10 cm.

The burner has means for controlling the pulse of the secondary jets. These means can advantageously be chosen from mass flow control devices, pressure drop control, passage section control, but also temperature control devices, control of the chemical composition of the fluid or pressure control. These means are preferably means for controlling the ratio between the pulse of the secondary jet and the pulse of the primary jet.

The control means enable to activate and deactivate one or more secondary jets (flow or no flow of the secondary jet concerned) so as to dynamically vary the direction and / or the opening of the flame. The control means preferably also dynamically increase and decrease the pulse (non-zero) of one or more jets or increase and decrease the ratio between the pulse of a secondary jet and the pulse of the primary jet.

The burner can be fed with fuel and with oxidant by an oxidant injection channel and at least one fuel injection channel, arranged concentrically, or by an oxidant injection channel and at least one injection channel fuel separated from each other and preferably parallel to each other.

The burner advantageously comprises a block of material 5, such as a block of refractory material, in which at least a portion of the passage 10 is located, the main outlet opening 11 being located on one of the faces or surfaces of the block. : front face 6.

In Figure 1, the secondary jet is conveyed by a secondary pipe

21 which passes through the block 5, the secondary jet preferably emerging substantially perpendicular to the primary jet. The interaction between the primary jet and the secondary jet takes place at a distance L from the front face 6 of the block from which the passage 10 of the primary jet opens, this distance L being able to vary as indicated above.

According to an embodiment for varying the direction of the flame illustrated in Figures 3A and 3B, the burner comprises at least one secondary pipe 321, 322, 323 and 324 which is positioned relative to the passage 310 of the primary jet of such at the level of the corresponding secondary opening 331, 332, 333 and 334 (that is to say the secondary opening through which the secondary pipe in question leads to the passage), the axis of the primary jet and the axis of the corresponding secondary jet are secant or quasi-secant.

Such an arrangement between the passage and the secondary pipe makes it possible to vary the angle between the axis of the flame and the axis of the primary jet upstream of the secondary opening by changing the pulse of at least one secondary jet corresponding.

If, in the absence of an actuator jet, the flame issuing from the main outlet opening 311 is perpendicular to the plane of FIG. 3A, the injection of a jet by the secondary channel 323, allows a deviation of the flame to the right in FIG. 3A, ie in the same direction as the direction of flow of the jet coming from 323. If at the same time, there is injection of a jet secondary by the secondary pipe 324, according to the relative amounts of movement of the jets from 323 and 324, can be obtained a deflected flame in a direction (projected in the plane of Figure 3A) which can vary continuously between the directions of the jets from 323 and 324 (to the right and down in Figure 3A). The burner preferably comprises at least two secondary lines which are positioned relative to the passage 310 so that, on the one hand, the two corresponding secondary openings are situated on the same cross section of the passage 310 and that, on the other hand, on the other hand, at these two secondary openings, the axes of the corresponding secondary jets are intersecting or quasi-intersecting with the axis of the primary jet. In this case, the two corresponding secondary openings may, in a useful manner, be located on either side of the axis of the primary jet (right and left for the openings 331 and 333, at the bottom and at the top for the openings 332 and 334), the two secondary openings and the axis of the primary jet being preferably located in a single plane (horizontal for the openings 331 and 333, vertical for the openings 332 and 334).

According to another useful configuration, at the two corresponding secondary openings, the plane defined by the axis of the primary jet and one of the two corresponding secondary openings is perpendicular to the plane defined by the axis of the primary jet and the other of two corresponding openings. For example, the horizontal plane defined by the axis of the passage 310 and the secondary opening 331 is perpendicular to the vertical plane defined by this axis and the secondary opening 332.

It is also possible to combine these two forms of execution. In this case, as illustrated in FIGS. 3A and 3B, the burner comprises at least four secondary lines 321, 322, 323 and 324 which are positioned relative to the passage 310 in such a way that: (1) the four corresponding secondary openings 331, 332, 333, 334 are located on the same cross section of the passage 310, and (2) two of these corresponding secondary openings 331 and 333 define a first plane with the axis of the primary jet and are located on either side of this axis, the other two secondary openings 332 and

334 defining a second plane with the axis of the primary jet, the first plane being preferably perpendicular to the second plane. This arrangement makes it possible to vary the direction of the flame according to the first and the second plane (for example in the horizontal plane and in the vertical plane) and to choose one or the other of the two secondary openings located in each plan (for example, to the left and to the right in the horizontal plane, and upwards and downwards in the vertical plane) and, as explained above, to any intermediate direction. At the level of the four corresponding secondary openings 331 to 334, the axes of the four corresponding secondary jets are preferably located in the same plane perpendicular to the axis of the primary jet 310.

The invention also allows an interaction between the primary jet and one or more secondary jets so as to generate, maintain or enhance a rotation of the fluid jet resulting from this interaction and therefore the flame around its axis. Such an interaction makes it possible to vary the opening of the flame.

As illustrated in FIGS. 4A and 4B, the burner may be provided with at least one secondary pipe 421 to 424 which is positioned relative to the passage 410 of the primary jet in such a way that at the corresponding secondary opening 431 to 434, the axis of the corresponding secondary jet 421 to 424 is not coplanar or substantially coplanar with the axis of the primary jet 410, this at least one secondary pipe 421 to 424 opening preferably tangentially on the passage 410 of the primary jet. In this way, the interaction between the primary jet and the secondary jet gives the primary jet a rotational pulse. The burner may, in a useful manner, comprise two secondary lines 421 and 422 positioned relative to the passage 410 of the primary jet such that at the two corresponding secondary openings 431, 432, the axes of the two corresponding secondary jets 421 and 422 are not coplanar with the axis of the primary jet 410, the two secondary jets being oriented in the same direction of rotation about the axis of the primary jet. The two secondary jets thus contribute to the rotational pulse imparted to the flame. The two secondary openings are advantageously located on the same cross section of the passage 410 / in the same plane perpendicular to the axis of the primary jet. They can be located on either side of the axis of the primary jet (openings 431 and 433 or 432 and 434). They may also be located in such a way that the plane defined by the axis of the primary jet and one of the two secondary openings 431 is perpendicular to the plane defined by the axis of the primary jet and the other of the two secondary openings 432 .

According to one embodiment, the burner comprises at least four secondary lines 421 to 424 which are positioned relative to the passage 410 of the primary jet so that at the corresponding secondary openings 431 to 434, the axes of the secondary jets corresponding are not substantially coplanar with the axis of the primary jet. Two of the corresponding secondary openings 431 and 433 are substantially coplanar with the axis of the primary jet 410 in a first plane and located on either side of the axis of the primary jet. The two other corresponding secondary openings 432 and 434 are substantially coplanar with the axis of the primary jet 410 in a second plane and also located on either side of the primary axis, the four corresponding secondary jets being oriented in the same direction of rotation around the axis of the primary jet. The first and the second plane may in particular be perpendicular to each other. It is also preferable that the four corresponding secondary openings are on the same cross section of the passage 410. In order to give the primary jet a rotational impulse, and thus to change the opening of the flame, it will preferably be ensured that at the level of the secondary opening in which the primary jet and the corresponding secondary jet interact, on the one hand , the axis of the secondary jet belongs to the plane perpendicular at this location to the axis of the primary jet, and secondly, the angle between the axis of the secondary jet and the tangent to the secondary opening (or more exactly at the imaginary surface of the passage of the primary jet at the level of the secondary opening) in this plane is between 0 and 90 °, preferably between 0 and 45 °. Figures 4a and b show an exemplary embodiment for controlling the opening of a flame. The primary jet (which flows from the left to the right in the passage 410 in Figure 4a) meets the secondary jets from the secondary lines 421, 422, 423 and 424 (shown in Figure 4b which is a cross section on plan AA of figure 4a). These secondary jets impact the primary jet tangentially to the passage 410, thus allowing, according to the pulses of these different jets, "to open" more or less the flame. This opening effect is essentially due to the fact that the secondary jets and the primary jet have axes that do not intersect, although the jets have physical interaction with each other. This causes a rotation of the resulting jet and therefore the flame on its axis.

It is also possible to combine in a single burner the embodiment for varying the direction of the flame according to any of the embodiments described above with any of the embodiments described above. above to generate, maintain or enhance a rotation of the resulting jet and thus to vary the opening of the flame.

To obtain both a directional and a rotational effect, we will combine the teaching of the preceding paragraphs. To obtain a dynamic variation of the directional and rotational effects, it will be possible, for example, to provide several secondary jet injection systems.

By providing separate secondary lines with secondary jet pulse control means, such as supply valves, it is thus possible to change, continuously or discontinuously, the shape and direction of the resulting jet by simply actuating said regulating means (valves).

To allow the secondary jet to act as effectively as possible on the primary jet, it is necessary to inject the actuator jet substantially perpendicular to the direction of the main jet.

For optimized operation, the burner may comprise at least one secondary pipe 21 positioned relative to the passage 10 of the primary jet so that at the corresponding secondary opening 31, this pipe has a thickness e and a height I , such that I ≥ 0.5xe and preferably: 0.5xe ≤ I ≤ 5.0xe (see Figure 1). A minimum height greater than or equal to 0.5xe makes it possible to achieve an optimized interaction between the corresponding secondary jet and the primary jet. For example, in order to achieve in practice a secondary jet such that at the point of interaction between the secondary jet and the primary jet, the angle θ between the axis of the secondary jet and the plane perpendicular to the axis of the primary jet or 0 °, it will be preferred that before the corresponding secondary opening, the secondary pipe has a direction substantially perpendicular to the axis of the primary jet over a length I which will preferably be between 0.5 and 5 times the thickness e (dimension in the direction of the flow of the main fluid) e of said pipe (e is the diameter of the pipe when it is cylindrical). Of course, it is also possible that this length I is greater than 5e, but this does not bring any additional effect of significant impact of the secondary jet on the primary jet. For example, for a burner with an injection of gaseous hydrocarbons at ambient conditions and an injection of oxygen, at least I = 5 mm for a burner of 100 KW and I = 50 mm for a burner of 10 MW.

The burner may comprise a quarney or a prechamber combustion (for example ceramic) disposed at the end of the passage, at least one secondary pipe being at least partially disposed within the quarl / pre-chamber. The passage of the primary jet may consist, in whole or for at least part of it, in a primary pipe for the injection of the primary jet. This primary channel leads to a primary opening. This primary opening may coincide with the main outlet opening of the passage.

When, as illustrated in FIGS. 3c, d and e and in FIG. 6, the primary line 308, 608 ends before the main outlet opening 311, 611, the primary opening 309, 609 is positioned upstream of the main opening. main opening 311, 611. In this case, at least one secondary opening 334, 632, 634 may be located between the primary opening 309, 609 of the primary pipe 308, 608 and the main opening 311, 611 of the passage. Figure 6 shows more particularly an embodiment of the invention in a tube-tube burner having a prechamber attached to the burner inside a ceramic opening in which the flame is stabilized (as for example described in patent applications No. US-A-5772427 and US-A-5620316 in the name of the Applicant and marketed by the Applicant) under the trade name ALGLASS. In the figure, the starter block 605 has a cavity 671 (or prechamber) into which the bi-tube opens. The passage 610 of the primary jet thus consists of a primary channel 608 opening through a primary opening 609 on the cavity 671, cavity which opens through the main outlet opening 611 located on the front face of the opening downstream of the opening primary 609. In the opening (block) 605 of the burner are drilled a plurality of secondary lines 622, 624 opening substantially perpendicular to the axis of symmetry X-X of the burner on the passage 610, and more particularly on the cavity, respectively by the secondary openings 632 and 634 located at a distance L from the main outlet opening 611. The bi-tube itself is schematically constituted of a central fuel injection tube (preferably), surrounded by a concentric tube wherein the oxidant is injected, the two fluids mixing in the cavity 671. In this embodiment, there is, upstream of the secondary openings 632, 634, a mixture of oxidants and fuels (and possibly combustion products) injected coaxially by the tubes. The direction and / or the opening of the flame are then regulated by the action, and more particularly by the controlled pulse, of at least one actuator jet 622, 624.

For optimal operation of the burner according to the invention, the passage of the primary jet will have at the level of the at least one secondary opening a fluid passage unobstructed or at least substantially unobstructed in the extension of the at least one secondary pipe corresponding, in order to allow effective interaction between the at least one corresponding secondary jet and the primary jet. Typically, the cross section of the passage of the primary jet will define an unobstructed or at least substantially unobstructed fluid passage at the at least one secondary opening. This is illustrated in Figure 6 where the central tube bringing the fuel ends at the primary opening and therefore well before the secondary openings.

Figures 3c, d and e show another embodiment of the burner, in which the primary pipe 308 terminates before the main outlet opening 311.

FIG. 3c represents an alternative embodiment similar to FIG. 3B, with however an embodiment in which two parallel channels (primary duct 308 and secondary duct 324) are arranged in a nozzle 345, the two ducts 308 and 324 opening on the front face of the nozzle. On this front face, there is reported a pellet 342 which directs the secondary jet of the secondary pipe 324 to the primary jet leaving the primary pipe 308, and more particularly perpendicular or substantially perpendicular to the primary jet. In this way, the flame can be deflected, for example in the direction indicated by arrow 344 in FIG. 3c. (The direction 344 of the flame will depend on the ratio of the pulses of the primary and secondary jets.) It is thus possible, by varying the pulse of the secondary jet with the aid of the control means, to obtain a variable flame direction for scanning with the flame a whole surface, such as the surface of a liquid bath to be heated. FIG. 3d is an exploded view of the nozzle 345 on which the pellet 342 is fixed (by means not shown in this figure), in the form here of a hollow lateral cylindrical portion 350 which will come to rest on the end of the nozzle 345, while the opening 346 in the pellet is positioned where opens the primary pipe 308. Figure 3e shows the bottom (inside) of the pellet 342 whose inner face 349 has a cavity 347 in which the secondary jet coming from the secondary pipe 324 will be distributed then come to meet substantially perpendicularly the primary jet from the primary pipe 308 through the slot 348 above the main outlet opening 346. The flame 344 (Figure 3c) resulting from this opening 346 will thus be deflected downwards (with respect to FIGS. 3c, d and e). It should be noted that the possibility of using a pellet to give the desired orientation to one or more secondary jets before their respective interaction points with the primary jet, is not limited to the secondary jets oriented so as to vary the direction of the flame, but also applies to the secondary jets described above to vary the opening of the flame.

The invention also relates to a method for dynamically or actively controlling the performance of a combustion system or burner with the aid of one or more secondary jets, impinging on a primary jet in order to modify the flow. of the jet and to produce a flame whose direction and / or the opening can be modified according to the characteristics (in particular direction and momentum) of the primary and / or secondary jets. This method can be used to regulate the closed loop or open loop performance of a combustion system implementing injections of fluid jets (liquid, gas or solid dispersion). FIG. 2 represents a method of regulating the performance of a burner according to the invention 210, mounted on a hearth 212. The sensors 214, 216 and 217 respectively measure quantities characterizing the products of combustion, the operating conditions of the combustion or combustion chamber and the operation of the burner. These measurements are transmitted using the lines 218, 219 and 220 to the controller 215. The latter, according to instructions given for these characteristic quantities, determines the operating parameters of the secondary jets so as to maintain the characteristic quantities at their values. setpoint and transmits using the line 221 these parameters to the control members 211 of the burner. The burner according to the invention advantageously comprises means for controlling the pulses of the primary and / or secondary jets, or means for controlling the ratio of the pulses of the primary jet and the secondary jet (s). This ratio is a function of the ratio of the section of the primary jet passage and the sections of the secondary pipes, the ratio of the flows in the secondary pipes to the flow of the resulting jet supplying the flame and the ratio of the densities of the fluids of the primary jet and secondary jet (s). (In the following paragraphs, when considering the variation of one of these ratios, the other two are considered constant.) The higher the ratio value of the passage section and the section of a secondary pipe at the level of the corresponding secondary opening increases, more (at constant respective rates) the secondary jet corresponding to a significant impact on the primary jet. Preferably, a ratio of sections of between 5 and 50, more preferably between 15 and 30, will be chosen. The ratio of the flow rate of the set of secondary jets to the total flow rate will typically vary between 0 (absence of secondary jets) and 0.5 and preferably between 0 and 0.3; more preferably between 0 and 0.15; knowing that the higher the flow ratio, the greater the deviation and / or the opening of the flame. The ratio of the density of each fluid constituting the secondary jets to the density of the fluid of the primary jet makes it possible to control the impact of the secondary jets. The lower the value of this ratio, the greater the effect of the secondary jet on the primary jet, at constant flow. For practical reasons, the same fluid will often be used in the secondary jets and in the primary jet (ratio equal to unity). To increase (at constant mass flow) the effects of the secondary jets, a fluid of lower density will be used than that of the fluid in the primary jet. The nature of the fluid in the secondary jets will be chosen according to the intended application. For example, to control the deflection of an air jet, it is possible to use a mixture of air and helium (of lower density) or to increase the entrainment of the products of combustion in a flame whose fuel is propane, control the main jet of fuel and / or oxidizer with a secondary jet of water vapor. In general, the ratio of densities (or densities) of the densest fluid to the least dense fluid can vary between 1 and 20, preferably between 1 and 10, more preferably between 1 and 5. Geometry the injection section of the passage and / or secondary channels, may be of various shapes and in particular circular, square, rectangular, triangular, oblong, multi-lobes, etc. The geometry of these injection sections influences the development of the instabilities of the resulting jet / flame. For example, a jet output of a triangular shaped injector will be more unstable than that from a circular injector, this instability promoting the mixing of the resulting jet with the surrounding medium. Similarly, an oblong injector will favor in a field near the injector the non-symmetrical development of the jet unlike a circular or square injector.

With respect to the physicochemical properties of the fluid used to make the secondary streams, they may be chosen to control certain properties of the resulting flow. For example, the reactivity of a mixture of main jet fuel (eg natural gas), oxidant (eg air) by use of oxygen (or other oxidant), and / or hydrogen ( or other fuel). If the tip of the passage of the primary jet, just before the point of interaction of the primary and secondary jets, is provided with a nozzle comprising a convergent / divergent (also called a Laval nozzle in the literature), it will be possible at the exit of the divergent to obtain (in a manner known per se in the literature) a jet of primary fluid and a resulting jet, for example an oxygen jet, supersonic which can then be of variable direction (possibly variable opening but generally losing its supersonic speed, which allows to alternate speeds subsonic and supersonic in some processes). The Laval nozzle can also be disposed on the resulting jet before the main exit opening. According to a variant of the method, at least two secondary jets are used, so as to obtain a variation of the direction of the flame in a plane (for example, to the left and the right, or to the top and the bottom). It is also possible to use at least two secondary jets so as to obtain a variation of the direction of the flame in at least two secant planes. These two variants, alone or in combination, can scan at least a portion of a surface, such as the surface of a load. By using a secondary jet whose axis is not secant or quasi-secant with the axis of the primary jet, the opening of the flame above the charge can be varied, alone or in combination with a scan. Means for controlling the momentum of the primary jet and / or the at least one secondary jet are preferably provided.

It should be noted that, although in the foregoing, the burner and the process have been illustrated above with reference to one form of implementation with a single primary jet that is made to interact with one or more secondary jets. it is obvious that the present invention also covers such a burner to create one or more flames whose opening and / or direction are variable from a multitude of primary jets which interact with one or more secondary jets.

FIG. 5 illustrates how the burner according to the invention makes it possible to produce a variable flame from two primary jets: a primary jet of fuel and a primary jet of oxidant. Each primary jet interacts with one or more secondary streams. The two resulting jets from the burner, and thus also the flame, having a direction and / or a variable opening through this interaction. FIG. 5a schematically shows the resulting jet of fuel 61 surmounted by the resulting jet of oxidant 62, in the situation where none of these jets is controlled by an interaction with one or more secondary jets. Figure 5b shows these same streams, but in a situation where they are controlled or deflected in opposition (jets convergent). The jet 60 is deflected downwards by the secondary jet 62 while the jet 61 is deflected upwards by the secondary jet 63, directed from below upwards (unlike 61). FIG. 5c shows the results in a situation where these jets are controlled or deflected in the same direction (upwards in the figure): the secondary jets 63 and 65 act from bottom to top respectively on the main jets 61 and 60, which generates resultant jets both directed upwards. These three examples make it possible to obtain very different directional and morphological flames (length, flattening, etc.). The flame 64 will be very wide in the median horizontal plane of the two jets, while the flame 67 will be sharply deflected upwards.

According to the invention, at the point of interaction between the secondary jet and the primary jet, the axis of the secondary jet makes with the plane perpendicular to the axis of the primary jet an angle which is less than 90 °, and preferably equal to at 0 °. However, as illustrated in FIGS. 3C and D, for reasons of space, the channels feeding these jets are most often substantially parallel. To reorient the secondary flow at the interaction zone of the two flows, can be fixed at the end of a parallel channel burner, an end piece hereinafter called injection pad whose function is to transform the direction of the secondary jet initially parallel to the primary jet, a secondary jet impinging the primary jet, the axis of said secondary jet being preferably located in a plane perpendicular to the axis of the primary jet. However, the use of the burner for very high temperature processes (T> 1000 ^° C.) can lead to overheating and degradation of the injection pellet.

To overcome this type of problem, we will seek in the dimensioning of the injection pellet to reduce the frontal surface of the burner subjected to radiation in the enclosure at high temperature. For this, we will try to limit the ratio 4 /.

It is also possible to use one of the two solutions illustrated in FIGS. 16 and 17. The first solution (FIG. 16) consists in placing the burner 500 in a refractory part 501 whose geometry and the relative position burner / aperture will protect the first one from a too much radiation. The position or the removal of the burner in the quarl must be sufficient to protect it from the radiation but must not limit the directional amplitude of the flame.

For this, it will be possible to modify the geometry of the quarl by eliminating a portion thereof along line 160 in dashed lines in FIG. 16 according to the angle α.

Preferably, the ratio λ A will be in the range 0.3 to 3, while

the angle α will belong to the interval [0 °, 60 °].

The second solution is to bring a refractory sleeve-type directly on the nose of the burner (where is the main outlet opening) as shown in Figure 17. This solution eliminates the presence of a quarry to complex geometry. The dimensions of the sleeve are such that it does not limit the directional amplitude of the injector. This means in particular that the thickness f of the sleeve is small (less than the diameter of the main jet) or that the material used to make this sleeve with a very low thermal conductivity. For example, alumina will be chosen.

The invention also relates to a method for heating a load using a burner, wherein the direction (and / or opening) of the flame relative to the load is varied. As already mentioned above, the invention makes it possible in particular to use one or at least two secondary jets, so as to obtain a variation of the direction of the flame in a plane (for example, to the left and the right, or up and down). It is also possible to use at least two secondary jets so as to obtain a variation of the direction of the flame in at least two secant planes. These two variants, alone or in combination, can scan at least a portion of the surface of the load. According to one embodiment, the heating of the charge is such that, in a first phase, the flame is directed towards the charge and that, in a second phase, the flame is directed substantially parallel to the charge. In particular, during the first phase, the injection angle of the flame can be between about 90 ° and 5 °, typically between about 90 ° and 10 °. During the second phase the injection angle of the flame is typically between about 5 ° and 0 °. Preferably, the injection angle of the flame during the first phase is between 5 ° and 75 °, more preferably 25 ° to 45 °.

Figure 8 shows three heat flux profiles transferred by a flame to a charge according to the angle of incidence of the flame on the charge as a function of the injection point distance of the flame reactants. A very large increase in the heat flux transferred to the load is observed with the increase in the incidence of the flame. For a zero incidence (α = 0 - see Figure 12), the heat flux is substantially constant over the entire length of the flame; for an incidence of 15 °, the transferred flow increases very rapidly, then a little slower from point A, whereas for a flame incidence of 30 °, the transferred flow increases extremely rapidly to point B, then less quickly to substantially point A, from which the transfer decreases.

FIGS. 9A and B represent the opening angle of the flame as a function of the ratio of the flow rate of the secondary jets (actuators) to the flow rate of the primary jet (main jet). In FIG. 9A, the curves C1 and C2 respectively represent the opening angle as a function of the ratio of the actuator / main jet flows. C1 relates to a CONF1 configuration in which the actuators are perpendicular to the main jet and open at a distance h from the main exit opening and C2 corresponds to a configuration identical to CONF1, but with a distance of 2xh instead of h between the secondary openings and the main exit opening. These two curves show that the opening of the flame is larger when the impact between the actuators and the main jet is closer to the main exit opening. FIG. 9b illustrates the variations of the opening angle as a function of the ratio of the flow rates of the actuators and the main jet: the curve C3 corresponds to the configuration CONF3 with actuators impacting the main jet at 90 ° (ie ie in a plane perpendicular to the axis of the main jet: θ = 0 °), at a distance 2xh from the main exit opening (similar to CONF2), while the curve C4 corresponds to the configuration CONF4 identical to CONF3 , with the exception of the angle of incidence α of the actuators which is 45 ° to the axis of the main jet (ie the angle θ between the axis of the actuators and the plane perpendicular to the axis of the main jet = 90 ° - α = 45 °). Note that when the actuator jets are perpendicular to the main jet (CONF3: θ = 0 °), we obtain, all things being equal, a larger opening of the flame than when the angle of incidence α of the actuator jets is lower (here 45 °) (CONF4: θ = 45 °).

FIG. 9 represents the deflection angle (in degrees) as a function of the ratio of the flow of the actuator jets and the flow rate of the main jet, expressed as a percentage. FIG. 10A shows four curves, all other things being equal, for which the flow rate of the main jet is respectively 200 ϋ / min, 150 ϋ / min, 100 ϋ / min and 50 ϋ / min. Note that these four curves are almost identical, which shows that the deflection of the flame is not a function of the flow of the main jet.

FIG. 10B shows the transfer of heat to a load: heat flow delivered by a burner according to the invention, in which the ratio of the flow rate of the actuator jets to the flow rate of the main jet is varied (represented here also as a percentage of the flow rate of the main jet), both for the fuel jet and for the oxidant jet (separate injection burner). Each jet initially injected parallel to the load is progressively deflected towards the load, which increases the heat transfer to the load. Figure 11 shows a curve of the opening angle of the flame according to the jet pulse ratio. This curve reports all the experimental data obtained for the control of the opening. The measured aperture angle is plotted against the physical parameter J which is the ratio of the specific pulses of the actuator jets and the main jet. This ratio is written as the product of the ratio of the densities (fluid on the main fluid) and the ratio of the square of the speed of the actuator jets and the square of the speed of the main jet). The main fluid is the same for all the experiments, while different fluids have been used for the actuators. These fluids differ mainly in their density (from the density of the largest to the lowest: CO2, Air, Air Helium mixture). It is observed that all the experimental points (whatever the flow rates and the fluids used) are aligned on a line. This shows that the physical parameter that controls the opening is the ratio of the specific pulses defined above.

Examples

The following examples provide a better understanding of the invention and how it can be used.

In Figure 7 an example of a burner with separate injections of different fluids is shown in more detail. The burner with separate injections 101 has a top row of oxygen injectors 112 in the form of jets and natural gas injectors.

(fuel) 125 in the form of jets, the set of injectors being in the refractory mass 121 (FIG. 7C).

The usually metallic portion 102 of the burner 101 is situated on the right-hand part of FIG. 7A and is extended by the oxygen gas injection tubes 107 and 109, on the one hand, and natural gas injection tubes 207 and 209, on the other hand. on the left of Figure 7A.

In this figure, there are provided two independent supplies of oxygen (or any oxidant) 104 and 106 respectively supplying the boxes 103 and 105 respectively connected to the tubes 109 and 107, the oxygen flowing through the tubes 110 and 108.

The end 111 of the tubes is enlarged in FIG. 7B, with the aid of which is explained the interaction of the main jets 108 and the actuator 110. tubes 107 and 109 is arranged a channel 127 extending the flow channel 110 of the actuator jet. The wall 109 is extended by the walls 113, inclined upwards, 114, horizontal and vertical 115 (in the figure), while a central volume 126 delimits a channel 127 first inclined upwards, horizontal then vertical (that is to say 90 ° relative to the gaseous flow channel 108 and opening therein through the opening 120). The vertical portion of the channel 127 has a height L, defined above, to ensure the orthogonality of the jets 110 and 108 at 120 (of course, if we choose an angle of intersection of the jets different from 90 °, the channel 127 will have the desired inclination and its length L remaining within the limits provided above). The metal part of the burner ends with a wall 123, vertical in this case, bordering the channel 127, metal part exposed to the heat radiation of the fireplace in use. To ensure the longevity of this end of the injection tubes, it will be possible to provide a protective element, for example alumina, resistant to high temperatures, coming, for example, to fit on this metal end to protect it and having a opening equal to the opening 112 (Figure 7C).

The fuel supply system 204, 206, 203, 205 is similar to the oxidizer feed system described above with a main channel 207, an actuator channel 209 defining main fuel jets 208 and fuel actuators 210, all housed in a cylindrical opening 222 of the opening 221 (similar to 122 for the oxidant). The ends 124 and 125 are similar to 123 and 112. The same fuel actuator jet injection system is provided at the end of 207 and 209 as shown in FIG. 7B, sized according to the characteristics of the fuel.

In general, however, it will be preferable to provide only one jet injector jet on the fluid having the highest pulse (generally the oxidizer in the case of a burner), the jet thus deflected itself causing the deflection of the other jet outside the burner. In such a case of course, the highest pulse jet (or row of jets) will generally be disposed above the lower impulse jet, so that without the action of the jet actuator on the jet of highest impulse, the burner delivers a directed flame generally horizontally, whereas when the jet actuator (coming to act up and down on the main jet of higher momentum) acts on the main jet, it is directed, as explained above, downwards (progressively, according to the ratio of the pulses) and carries with it the second lower pulse jet (here the fuel) forming a flame which can thus pass from a horizontal position to an inclined position towards the load to be heated, under the burner flame. By adding an actuating jet on either side of the main jet at 90 ° (or any other angle between 0 ° and 180 °) of said actuator jet illustrated in FIG. 7a, (that is to say on a horizontal at the level of 123 in Figure 7c, perpendicular to AA) this then allows to move the flame on the load to be heated from left to right or right to left, thus covering substantially the entire surface to be heated. According to the invention, the actuator jet makes with the main jet an angle which is greater than zero. For reasons of space, the two channels leading these jets are usually fed by a co-axial feed system (parallel channels - see Figure 7).

The invention will hereinafter be illustrated in the case of a burner useful for heating any load which may be a metal charge or any other charge which must be melted and / or brought to a high temperature and then maintained at that temperature. ci, for example a charge of ferrous or non-ferrous metal, solid materials for the production of glass, for that of cement or on the contrary a charge which must be dried from a liquid bath.

In particular, it is possible to use the invention on a tool for treating steel in an electric arc furnace, for example as follows: this type of tool generally comprises a flame (usually subsonic) which makes it possible to heat the metal, melt it, especially at the beginning of a merger. This flame, as explained in the present application, may be of variable direction by equipping each main jet (oxidizer, fuel, premix) or at least one main jet of a jet actuator which varies its direction and / or its opening, so as to move this flame on the load without requiring heavy mechanical means that change the direction of the burner body. These tools are often also equipped with injection sprays of pulverized coal, usually injected with carrier gas in a lance. By providing this lance with an injection pipe of a secondary jet, for example a gas identical to the "thruster" gas of the pulverized coal, it will be possible to vary the direction (also the opening of the jet as for any which fluid) of the jet of pulverized coal (or of pulverized liquid fuel oil) in order to promote a rapid meeting of the jet of fuel sprayed with the flame or, on the contrary, to move the jet away from the flame.

The following examples relate to the control of the heat transfer by a burner according to the invention to a load, for example metallic, in a process for melting a filler.

An aluminum smelting furnace is generally equipped with one or more burners on one or more of the side walls surrounding the furnace smelter, disposed above the waterline when the metal is fully melted (liquid ). The axis of the flame, when it is horizontal, is located at a height of 10 and 100 cm from this waterline, preferably between 40 and 80 cm.

• Example 1: case of solid material in the oven:

Burners according to the invention are used so that the flame incidence is variable. (Incidence is defined as the angle of the flame to the horizontal). When the incidence is zero, the flame is horizontal. When the incidence is non-zero, the flame is inclined below the horizontal and directed towards the bottom of the melting basin of the furnace.

The burners inject each jet of fluid into the furnace chamber, but this type of injector can be used only for the higher impulse fluid (oxidant or fuel) when it can interact with the one of the least impulse. to obtain the desired deviation of the flame, typically, the oxidant in the case of an air burner / gaseous fuel, or oxygen / gaseous fuel.

In the first part of the aluminum melting cycle, when the metal is predominantly present in the solid state, the direction of the flame is adjusted so that the latter has a non-zero incidence (axis of the flame between 5 ° and 75 °, preferably between 25 ° and 45 °). This adjustment considerably improves the thermal transfer of the burner and thus reduces the duration of the melting (as explained using Figure 10). When most of the solid metal blocks are melted, the direction of the flame is adjusted to have a zero angle of incidence. The flame is therefore parallel to the waterline of the liquid metal. This setting makes it possible to continue transferring energy to the charge and to complete the melting of the metal or to refine it by limiting the heating of the already molten metal and consequently its oxidation by the flame or the products of combustion.

Between the extreme positions of the flame described above (free incidence and zero incidence), it is also possible during the first part of the cycle to adopt an intermediate, static setting, where the incidence of the flame is between 5 ° and 30 ° preferably between 10 ° and 25 °, to obtain a compromise between covering the furnace charge by the flame (projected area of the flame on the bath) and intensity of the heat transfer. Figure 12 illustrates the extreme positions of the flame with respect to the load.

Figure 12a is a top view of an aluminum melting furnace equipped with two burners according to the invention producing two flames positioned above the metal bath.

The chimney of the oven allows the evacuation of the fumes produced by the flames.

Figures 12b and 12c show a side view of the same furnace, at the flame.

In FIG. 12b, the flame is inclined at an angle α with respect to the horizontal, preferably when solid metal is still present on the metal bath, while in Figure 12c, the flame is positioned at zero incidence (α = 0).

Between the extreme positions of the flame (free incidence and zero incidence), it is also possible during the first part of the cycle periodically vary the angle of incidence of the flame. For example, the oven operator can vary the incidence between 0 ° to 45 ° and then return to 0 °. Preferably, the burner will be controlled with a control unit making it possible to periodically modulate the burner control ratio, that is to say the ratio of the pulses of the main and actuator jets and consequently the incidence of the flame on the bath. The control signal of the control box may be sinusoidal, triangular, square, etc. with a variable frequency of 0.05 Hz to 100 Hz, preferably triangular at a frequency of 0.1 to 10 Hz. The periodic variation of the position of the flame makes it possible to homogenize the transfer of heat inside the oven and thus to melt more quickly the solid elements.

• Example 2: homogenize the transfer of energy to the load:

Burners according to the invention are used so that the orientation of the flame in a horizontal plane can be modified on demand according to the control ratio of each burner as illustrated in FIG. 13.

Each jet of fluid is injected into the furnace chamber by means of a burner according to the invention, but for jets located in the same horizontal plane or horizontal planes closely spaced from each other (from one to two jet diameters), we can only use these injectors for the peripheral jets when they can interact with the other jets to deviate. The variation of the horizontal orientation can be done in both the left and right directions either by equipping each main jet with two lateral actuator jets, or by equipping each main main jet with a single jet actuator, capable of actuating the main jet. in the horizontal direction but in opposite directions to each other. It is also possible to offset the main injector so that at a zero control ratio, the flame is naturally deflected (to the right or to the left) with respect to the X-X 'axis of the burner in FIG. so vary the orientation of the flame by gradually increasing the control ratio of the control system (ie obtain a jet along the X - X 'axis with a non-zero control ratio).

The use of one or more burners with variable flame orientation increases the load coverage by moving the flame in a horizontal plane.

(The expression control ratio used above is defined as the ratio of the flows of the actuator jet and the main jet, knowing that the pulse of a jet of fluid can be controlled simply by the variation of the opening of the jet. a valve, increasing the opening of a valve being proportional to the increase in the flow of the jet, all things being equal). When the control ratios of the burner (s) are zero, the orientation of the flame is located in the natural axis of the burner and the flame covers a portion of the load. When one of the control ratios is non-zero, the position of the flame is deflected and the flame covers another portion of the load.

Figure 13 illustrates an example of horizontal displacement of a flame over a load; each main jet 130, 132 (oxidizer or fuel) is provided with an actuator jet 131, 133; in FIG. 13a, the control ratio CR of the jet 130 is zero, ie no fluid is injected into the channel 131; the control ratio CR of the jet 132 is on the other hand positive, which means that since 133 acts from bottom to top in FIG. 13a, the actuating jet 133 deflects the main jet 132 upwards in the figure, ie to the left with respect to the X - X 'axis of the burner. In FIG. 13b, the control ratios of the two main jets 130 and 132 being zero, (CR = 0), there are no actuator jets in action and the flame propagates along the axis X - X '.

In FIG. 13c, contrary to FIG. 13a, the control ratio CR of the jet 130 and the jet is positive, which causes the flame to be shifted downwards in the figure (towards the right in a view from above), the main jet 132 and the actuator jet 133 having a zero control ratio (no jet 133). Thus, each burner can cover a larger portion of the charge favoring the homogeneity of the heat transfer and making it possible to limit the possible formation of hot spots if refractory materials are in the bath (for example residues based on alumina, recycled or in course of formation by oxidation of the metal being melted), and to promote overall heat transfer to accelerate the constant power melting process, or reduce energy consumption constant melting time.

• Example 3: flame with variable incidence on the load and which sweeps the load laterally.

• Example 4: closed-loop control:

This exemplary embodiment of the invention makes it possible to control the movement of the flame both horizontally and vertically, as a function, for example, of various operating parameters of the furnace, given by various types of sensors installed on the furnace, and in particular sensors of flow of heat, temperature, or possibly chemical composition (for example laser diode TDL type).

A regulation loop whose sensor is a measurement device making it possible to obtain an image of the heat transfer to the charge or of the oxidation of the aluminum bath, this information making it possible to reduce or increase the transfer to the charge by acting on the flow of the actuator jet, as explained above.

- A control loop of the flame position based on the measurement of the bath temperature, when at least a portion of the bath is present in the liquid state. As long as the bath temperature is less than a Tc value, between 650 and 750 ^° C., for example for aluminum, the flame must remain in non-zero incidence on the bath to maximize the heat transfer. When approaching the Tc value, the flame is progressively raised away from the bath, especially as the target value is reached, in order to limit the risk of oxidation of the load. The incidence of the flame is then controlled to maintain the temperature at its target value. A loop for regulating the position of the flame based on the measurement of the heat flow: this heat flow can possibly be evaluated by means of a temperature difference read between two thermocouples immersed in the bath at two different depths but on a same generator perpendicular to the hearth of the oven.

The heat flow can also be deduced from the heat transfer calculated through the oven floor, always by measuring the temperature difference within it. Given the greater resistivity of the hearth, made of refractory materials, it is easier to obtain a significant temperature gradient. The heat flow can also be monitored by means of a flow meter disposed for example in the vault of the melting chamber. Indeed, all things being equal, any decrease in the flow perceived by the vault and observed by the flow meter, will at least partially correspond to an increase in the heat flow transmitted to the load. (We are less interested in the absolute value of the heat flux transmitted to the load (or losses at the walls) than in the temporal evolution of the corresponding signal).

The melting of the charge will start with a flame with a clear incidence on the charge, this incidence being maintained as long as the flux transmitted to the load will remain high. As soon as this flow decreases, indicating an increase in the temperature of the charge and the reduction of its heat absorption capacity, the flame is progressively raised away from the bath, in order to limit the risks of oxidation. or overheating the load. - A regulation loop of the position of the flame based on the measurement of the composition of the smoke at the exit of the oven or inside the oven, for example before the collector of the fumes of the oven, above the bath, between the flame in incidence and the aluminum bath, etc. for the detection of one or more species indicative of oxidation of the aluminum bath such as CO: a. The composition of the fumes can be measured in a manner known per se by extraction and analysis (conventional analyzers, TDL or other) or in-situ by absorption (laser diode or other) or electrochemical probe. b. The fusion starts with a flame with a clear incidence on the charge, and this incidence is preserved as long as the tracer of the oxidation of the charge is stable and in small quantity. As soon as the concentration of the tracer of the oxidation increases, the flame is progressively raised to remove it from the bath, in order to limit the concentration of the tracer (s), and thus the oxidation of the charge, by acting on the main jet via the jet actuator as explained above. vs. In addition, the position of the flame can be set to reach a setpoint and then maintain a precise setpoint concentration oxidation tracer. It is indeed possible to set a concentration threshold that must not be exceeded and to adjust the flame incidence continuously to achieve this.

It should be noted in all cases that when the load is composed at least in part of cold solid, it can direct the flame positively impacting the load since as the temperatures remain modest, for example less than 600 ⁰ C for the aluminum oxidation rate remains low. When the charge has become essentially liquid, the regulation used becomes important to avoid the rise in temperature of the metal and the oxidation thereof. For an application of the invention to the heating of a material other than aluminum, for example for heating a glass bath, etc., the same principles of regulation apply, for temperatures and criteria that are different from one material to another, but are in themselves well known to those skilled in the art.

• Example 5: Emissions control: All primary techniques for reducing nitrogen oxide emissions from burners or industrial fireplaces use the local properties of fluid or flame flows to limit their formation. In particular they aim to reduce the temperature or the concentrations of the reagents (fuel, oxygen) or the residence time of the reactants in the flame and / or in the products of combustion. One of these techniques involves driving enough flue gas into the reagents or into the flame to lower the temperatures, the concentration of reagents or reduce the residence time. For this purpose the burner is dimensioned so as to obtain fuel jets and / or oxidant at high speed (high pulse) and sufficiently distant to obtain the maximum rate of entrainment or recirculation of flue gas compatible with good stabilization of the flame. The stabilization limit is detected at the occurrence of unburned in combustion products such as carbon monoxide for hydrocarbons. Under certain conditions it is possible to obtain a "flameless" combustion regime that is particularly favorable to the reduction of emissions.

The limitation of this technique and the combustion technologies that use it is that the flue gas entrainment rate is set by the burner dimensions and the operating conditions. As a consequence, the emissions performance can deteriorate very significantly as soon as these conditions are removed, but also when fuel is changed, or when the furnace or furnace-specific flows contribute significantly to the emissions. properties of the flames.

The invention makes it possible to adapt in operation the properties of the flames and in particular the rate of recirculation of burnt gases, which makes it possible to minimize in all circumstances emissions of pollutants and ultimately optimize the performance of burners.

• Example 6: premix burner consisting of an injector placed in a fireplace.

Actuator jets as described above are used to modify in operation the opening angle of the main fluid jet (or several jets). In this case, the main jet is a gaseous premix of fuel and oxidizer. The opening of the jet measures the level of entrainment of the ambient environment by the latter, it can be measured by the angle between the axis of the jet and the line tangent to the boundary between the jet and the ambient environment. (This boundary can be defined as the place in the jet where the concentration of the injected fluid becomes zero).

The opening of the jet is controlled by the ratio between the flow of the jet actuator and the total flow of the resulting jet. When this control ratio is zero, a transmission level N1 is measured (FIG. 15). This control ratio is actually the ratio of jet pulses as explained above.

The control parameter is then increased so as to increase the entrainment of burnt gases in the jet and thus dilute the injected fuel mixture. This dilution will lead to, on the one hand, reducing the temperature and, on the other hand, the concentration of the reagents in the flame. NOx emissions will therefore decrease to N2 (Figure 15). If the value of the control parameter is further increased, the temperature and the concentrations of the reactants become too low to ensure a good stabilization of the flame: unburnt appear in the combustion products. Emissions of nitrogen oxides are then at an N3 level and unburnt emissions at a level 13 too high. The control parameter is then reduced until the optimal level of NO and IO emissions (intersection of the NOx and unbreated curves in Figure 15) is reached. This optimum can be obtained manually (passive control) or preferably by a control device active. This device integrates sensors for the measurement of emissions of nitrogen oxides and unburnt, an automat using the control logic explained above and the control devices of the flows of the main jet and the jet (s) actuator (s) at least one injector. The controller will determine the value of the control parameter that minimizes emissions of nitrogen oxides and unburnt. The active control becomes indispensable as soon as the number of parameters to be optimized is greater than or equal to two. For example one can at the same time want to minimize pollutant emissions by increasing the rate of dilution of the flame by the flue gases and maximize the transfer to the load by inclination of the flame to the load.

• Example 6: burner in non-premixed combustion If the combustion technology is of non premixed type then the control can be exerted indifferently on the fuel, the oxidant or both in a similar way to the example 5.

If necessary, the effects of opening (entrainment of the ambient environment) and deflection of the jets (divergent fuel and oxidant jet) will be combined, in particular to increase the impact of the dilution of the flame and to maximize the reduction of emissions.

Claims

claims

1 - Burner comprising:

A passage for bringing a primary jet of oxidant or fuel or an oxidizing-fuel premix to a main outlet opening,

At least one secondary pipe for the injection of a secondary jet, in which:

The at least one secondary pipe leads to the passage through a secondary opening located upstream of the main opening and is positioned relative to the passage so that at the point of interaction between the corresponding secondary jet and the primary jet the angle θ between the axis of the corresponding secondary jet and the plane perpendicular to the axis of the primary jet is greater than or equal to 0 ° and less than 90 °, preferably from 0 ° to 80 °, more preferably from 0 ° to 45 ° and in that

The at least one secondary opening is spaced from the main opening by a distance L less than or equal to ten times the square root of the section s of the main opening, preferably L ≤ 5 ^* Vs, more preferably L <3 ^* Vs, characterized in that:

The burner comprises means for regulating the pulse of each corresponding secondary jet, said burner making it possible to vary the direction and / or the opening of the flame by changing the pulse of at least one corresponding secondary jet.

2 - Burner according to claim 1, wherein the regulating means controls the ratio between the pulse of each corresponding secondary jet and the pulse of the primary jet.

3 - Burner according to one of the preceding claims, comprising at least one secondary pipe positioned relative to the passage in such a way that at the corresponding secondary opening, the axes of the jet primary and said secondary jet are intersecting or quasi-secant in order to be able to vary the angle of the flame at the outlet of the burner with respect to the axis of the primary jet upstream of the corresponding secondary opening.

4 - burner according to claim 3, comprising at least two secondary pipes positioned relative to the passage so that the two corresponding secondary openings are located in the same plane perpendicular to the axis of the primary jet and at the level of these two corresponding secondary openings, the axes of the corresponding secondary jets are intersecting or quasi-intersecting with the axis of the primary fluid jet.

5 - burner according to claim 4, wherein the two corresponding secondary openings are coplanar with the axis of the primary jet at the two secondary openings and located on either side of this axis of the primary jet.

6 - Burner according to claim 4, wherein the plane defined by the axis of the primary jet at the two corresponding secondary openings and one of the two corresponding secondary openings is perpendicular to the plane defined by the axis of the primary jet and the other of the two corresponding secondary openings.

7 - Burner according to one of claims 4 to 6, comprising at least four secondary pipes positioned relative to the passage so that the four corresponding secondary openings are in the same plane perpendicular to the axis of the primary jet and that at these four secondary openings the axes of the corresponding secondary jets are intersecting or quasi-intersecting with the axis of the primary jet, two of these corresponding secondary openings being coplanar with the axis of the primary jet in a first plane and located on the and other of this axis, the two other corresponding secondary openings being coplanar with the axis of the primary jet in a second plane and located on either side of this axis. 8 - Burner according to one of the preceding claims, wherein at least one secondary pipe is positioned relative to the passage in such a way that at the corresponding secondary opening the axis of the corresponding secondary fluid jet is not substantially coplanar with the axis of the primary fluid jet to be able to generate, maintain or enhance a rotation of the resulting fluid jet about its axis, and thus to vary the flame opening at the burner outlet.

9 - burner according to claim 8, comprising at least two secondary pipes positioned relative to the passage so that the axes of the corresponding secondary jets are not substantially coplanar with the axis of the primary jet and the corresponding secondary jets are oriented in the same direction of rotation around the axis of the primary jet.

10 - Burner according to claim 9, wherein the two corresponding secondary openings are located on either side of the axis of the primary jet.

11 - Burner according to one of the preceding claims, wherein at least one secondary pipe is positioned relative to the passage so that at the corresponding secondary opening the secondary pipe has a thickness e and a height t, the height is greater than or equal to 0.5 times the thickness e, preferably between 0.5 xe and 5 x e.

12 - Burner according to one of the preceding claims, comprising means for controlling the ratio of the pulses of the main fluid jet and the secondary fluid jet. 13 - Burner according to one of the preceding claims, comprising a block of material in which at least a portion of the passage is located, the main opening being located on one of the faces or surfaces of the block.

14 - Burner according to one of the preceding claims, comprising means for controlling the pulses of the primary and / or secondary jets.

15 - Burner according to any one of the preceding claims, comprising a small hole disposed at the end of the passage and at least one secondary pipe opening on the passage through a secondary opening in the quarl.

16 - Process for heating a charge by means of a flame, said flame being produced using a burner according to one of the preceding claims.

17 - The method of claim 16, wherein the direction and / or opening of the flame is varied by interacting a primary jet with at least one secondary jet.

18 - The method of claim 17, wherein the primary jet is a jet containing oxidant or fuel or a premix of oxidant and fuel.

19 - Method according to one of claims 16 to 18, wherein the direction of the flame is varied to scan at least a portion of the surface of the load.

20 - The method of claim 19, wherein the direction of the flame is varied in at least two secant planes to scan at least a portion of the surface of the load. 21 - Process according to any one of claims 16 to 20, wherein in a first phase, the flame is directed towards the load and in a second phase, directs the flame substantially parallel to the load.