Method for heating a glass melting furnace, and corresponding burner arrangement

Abstract

According to a method for carrying out a step-wise combustion in a glass melting furnace, a low-oxygen region with high carbon monoxide concentration is formed between the burner stage and the glass melt. According to the invention, temporal and / or local fluctuations in carbon monoxide concentration are deliberately brought about in this region. The continuous variation in carbon monoxide concentration allows foam formation in the glass melt to be controlled more effectively.

Description

[0001] Method for heating a glass melting furnace and burner arrangement therefor

[0002] The invention relates to a method for heating a glass melting furnace. The invention further relates to a burner arrangement suitable for carrying out the method.

[0003] A well-known method for reducing NOx emissions in combustion processes is staging the combustion air. In this process, the combustion air is fed to the flame in two or more partial streams from spatially separated positions. A portion of the combustion air is thus withheld from the main combustion zone, which generally leads to a substoichiometric combustion reaction and thus to strong carbon monoxide (CO) production. The resulting comparatively low adiabatic combustion temperature in the main combustion zone reduces the formation of thermal NOx. In addition, the carbon monoxide produced also directly reduces locally present NOx. The unburned components of the fuel are afterburned by a secondary air stream at a certain distance from the main combustion zone.The most prominent examples of this type of combustion are boxer combustion systems in power plants, where the combustion air is even divided into primary, secondary and tertiary air.

[0004] Because this type of staged combustion requires a lot of space, only large combustion chambers (e.g., steam boilers in power plants) are suitable; they are generally unsuitable for use in, for example, glass melting furnaces. Furthermore, the local production of large quantities of carbon monoxide is not always desirable for safety reasons, but also due to the associated disadvantages in product properties.

[0005] In contrast to air burners, oxygen burners (oxyfuel burners) use technically high-purity oxygen as an oxidizer. Especially in the case of high-temperature oxygen burners, such as those used in glass melting furnaces, where combustion chamber temperatures of 1450°C and higher are required, very high concentrations of nitrogen oxides arise due to residual nitrogen in the oxidizer or the introduction of false air into the furnace chamber. It has therefore already been proposed to apply the principle of staged combustion to such combustion processes as well. Due to the significantly reduced volume flow rates, oxygen burners are significantly smaller and more compact than air burners, which makes the installation or subsequent installation of complex gas distribution systems for staging the oxygen significantly more difficult.

[0006] EP 0 762 050 A1 and EP 3 366 994 A1 disclose methods for performing staged combustion using oxyfuel burner assemblies. The burner assemblies described therein comprise a flat flame burner with an oval outlet opening, from which at least one further, likewise oval-shaped outlet lance for secondary oxygen is arranged at a vertical distance. Such a multiple oxygen supply allows, on the one hand, the total oxygen flow introduced to be distributed between the burner and outlet lance(s), thus directing the oxygen input away from the center of the furnace chamber toward the exterior, and, on the other hand, the oxygen concentration in the furnace chamber to be adjusted in a region below, or below and / or above, the flame.Particularly in glass production, a reduced oxygen concentration below the flame proves to be advantageous, as a carbon monoxide-rich atmosphere develops locally there, which counteracts foam formation in the glass melt and can also reduce foam that has already formed.

[0007] The invention is based on the object of providing a method for heating a glass melting furnace in which little NOx is generated and which further reduces the foaming of a glass melt.

[0008] This object is achieved by a method having the features of patent claim 1. Advantageous embodiments of the invention are specified in the subclaims.

[0009] A method for heating a glass melting furnace is carried out according to the invention using staged combustion in a furnace chamber, in which a carbon-containing fuel stream, such as natural gas, coal dust or oil, and a primary oxygen stream which is substoichiometric to the fuel stream are introduced into the furnace chamber by means of a burner arrangement and are burned together there to form a flame, and a secondary oxygen stream is likewise introduced into the furnace chamber by means of the burner arrangement in such a way that an oxygen-rich atmosphere is generated in an upper region of the furnace chamber and an oxygen-poor and carbon monoxide-rich atmosphere is generated in a lower region of the furnace chamber adjacent to a glass melt located in the furnace chamber, wherein the carbon monoxide content is continuously varied in at least a partial region of the oxygen-poor and carbon monoxide-rich atmosphere generated in the lower region of the furnace chamber.

[0010] A “burner arrangement” is understood here to mean a device for heating a glass melting furnace which enables staged combustion in the furnace chamber. This generally requires at least one fuel supply and at least two oxygen supplies for introducing primary and secondary oxygen. The oxygen supplies can be arranged in a common housing together with at least one fuel supply, for example coaxially thereto, and thus form a burner with the fuel supply(s), and / or the oxygen supplies or at least one oxygen supply can be spatially separated from the fuel supply(s) in the form of lances opening into the furnace chamber. The oxygen can also be in the form of an oxygen-containing gas, such as air or oxygen-enriched air (with an oxygen content of >21 vol.-%), are introduced into the furnace chamber.

[0011] An “oxygen burner” is understood here to mean a burner that is designed and suitable for combusting a solid, gaseous or liquid, carbon-containing fuel, such as natural gas, oil or coal dust, with an oxidant whose oxygen content is at least 90 vol.%. A gas with an O2 content of at least 90 vol.% is also referred to below as “pure oxygen”. The process according to the invention preferably uses at least one oxygen burner in which primary oxygen is used as the oxidant. A “high-impulse burner” is understood here to mean an oxygen burner that is designed such that the fuel and / or oxygen flow out of a burner mouth of the high-impulse burner opening into the furnace chamber at an exit velocity of at least 50 m / s, preferably at least 100 m / s, particularly preferably at least 150 m / s.The high-impulse burner design leads to intensive recirculation in the furnace chamber, which lowers the flame temperature and thus inhibits the formation of NOx. Furthermore, the high exit velocities favor flow conditions that lead to temporally and spatially fluctuating concentrations of certain gases in the vicinity of the flame. As explained in more detail below, this circumstance proves advantageous for the process according to the invention.

[0012] An "oxygen lance" is understood here to mean a device by means of which oxygen or an oxygen-containing gas can be introduced into the furnace chamber in a jet. The oxygen lances are preferably designed as high-impulse lances, from which the oxygen is ejected at a speed of at least 50 m / s, preferably at least 100 m / s, and particularly preferably at least 150 m / s.

[0013] According to the invention, staged combustion occurs in which the fuel flow and the primary oxygen flow are in a substoichiometric ratio to each other, and an amount of oxygen that is stoichiometric to the fuel flow is introduced only through the addition of secondary oxygen. The process according to the invention initially follows the approach known from the prior art, according to which a low-oxygen, carbon monoxide-rich atmosphere induced by staged combustion in a lower region of the furnace chamber, i.e., adjacent to the glass melt, suppresses foam formation in the glass melt or reduces foam that has already formed.

[0014] For example, a carbon monoxide content of over 100 vpm, preferably over 1000 vpm, has proven advantageous for reducing foam formation. Surprisingly, it has now been found that the suppression of foam formation and / or the reduction of foam already formed in the glass melt can be further improved by continuously changing the carbon monoxide content, at least in a partial region of this atmosphere, i.e., by continuously increasing, decreasing, or fluctuating spatially and / or temporally. Based on the previously mentioned values ​​of a carbon monoxide content of at least 100 vpm, preferably at least 1000 vpm, the carbon monoxide content in a given spatial region should change by at least 10% to 100% within a period of no more than 10 minutes, preferably less than 1 minute.In the case of turbulent flows leading to fluctuations in the carbon monoxide content, a change of this magnitude can also occur very quickly, within a few seconds, whereby the intensity and range of fluctuation depend on the respective conditions of the furnace chamber and the burner arrangement used.

[0015] Preferably, the carbon monoxide content in at least a portion of the atmosphere generated in the lower region of the furnace chamber is changed by inducing a temporal and / or spatial variation in the flow(s) of fuel and / or primary oxygen and / or secondary oxygen introduced into the furnace chamber. This can be achieved, for example, by varying the total oxygen flow supplied to the furnace chamber or by dividing an overall constant oxygen flow between the primary and secondary oxygen supplies (and / or between different secondary oxygen supplies) in a time-varying manner.Alternatively or additionally, the carbon monoxide content can be changed by pivoting or rotating a flame generated in the furnace chamber and / or by a pulsed or otherwise time-varying introduction of one or more of the gas streams (fuel and / or primary and / or secondary oxidant) introduced into the furnace chamber. In all of these cases, this results in a change in the chemical composition of the atmosphere in a given spatial area, which usually also changes the carbon monoxide content in that area.

[0016] A particularly preferred embodiment of the process according to the invention provides that the fuel flow and / or the primary oxygen flow and / or the secondary oxygen flow is / are introduced into the furnace chamber at a speed of at least 50 m / s, preferably at least 150 m / s, particularly preferably at least 250 m / s. The high flow velocities lead to intensive recirculation of the combustion gases present in the furnace chamber. For reasons that are not yet fully understood, this leads to turbulent flow phenomena which result in the lower region of the furnace chamber not forming an atmosphere that is stationary in its composition, i.e. one that is essentially constant in space and time. Rather, this region is continuously subject to temporal and spatial fluctuations, particularly in its carbon monoxide content.Thus, with this embodiment, it is possible to effect a continuous change in the carbon monoxide content in a spatial region of the furnace chamber without the gas flows introduced into the furnace chamber having to be varied temporally or spatially; rather, with this embodiment of the invention, a uniform introduction of fuel, primary and secondary oxygen can also take place, provided the introduction occurs at a sufficiently high flow velocity.

[0017] A preferred burner arrangement for carrying out the method according to the invention has the features of patent claim 5. The burner arrangement is equipped with a fuel channel for introducing a carbon-containing fuel into a furnace chamber of a glass melting furnace, an oxygen supply for supplying primary oxygen into the furnace chamber and an oxygen supply for supplying secondary oxygen in an upper region of the furnace chamber, as well as with means for continuously changing the carbon monoxide content of an atmosphere forming below a horizontal burner plane defined by the burner mouth.

[0018] The supply of secondary oxygen into an upper region of the furnace chamber enables staged combustion, whereby, under overall stoichiometric conditions, an oxygen-poor, carbon monoxide-rich atmosphere develops in a lower region of the furnace chamber. The continuous change in the carbon monoxide content results in a particularly efficient reduction of foam formation on the molten glass. The oxidant used in the burner arrangement according to the invention is preferably pure oxygen. The burner arrangement according to the invention preferably comprises a burner in which the fuel channel and the oxygen supply for primary oxygen are arranged coaxially to one another in a common housing, which opens into the furnace chamber at a burner mouth.The oxygen supply for secondary oxygen is preferably designed as an oxygen lance which opens into the furnace chamber above a horizontal plane (“burner plane”) of the burner which runs through a flame forming in front of the burner mouth.

[0019] For example, the means for continuously changing the carbon monoxide-rich atmosphere forming below the burner level comprise means for temporally or spatially changing the mass flow(s) of fuel and / or primary oxygen and / or secondary oxygen introduced into the furnace chamber, such as, for example, corresponding control devices for controlling the corresponding gas flow and / or a distribution device by means of which an overall constant oxygen flow supplied to the furnace chamber is divided between the primary and secondary oxygen supplies with time-varying proportions.

[0020] Alternatively or additionally, means for pivoting and / or rotating the flame can be used, as known, for example, from EP 1 821 036 A1. Rotating or pivoting the flame generally also changes the carbon monoxide concentration in a given area.

[0021] In yet another embodiment of the invention, the burner of the burner arrangement is a high-impulse burner and / or the at least one oxygen supply for secondary oxygen is a high-impulse lance as defined above, in which the supplied gas is introduced at a speed of at least 50 m / s, preferably at least 100 m / s, particularly preferably at least 150 m / s. Due to the high recirculation of furnace gases in the furnace chamber when using such high-impulse burners or high-impulse lances, as already explained above, turbulent flows lead to a continuous change in the chemical composition of the atmosphere below a burner level defined by the flame, and thus to a continuous change in the carbon monoxide content in this area.

[0022] The fuel channel and the oxygen supply of the high-impulse burner are preferably substantially cylindrical in shape and arranged coaxially with one another, wherein the fuel channel can be arranged within the oxygen supply or, conversely, the oxygen supply can be arranged within the fuel supply. To increase the exit velocity, the fuel channel and / or the oxygen supply can be conically shaped at their respective exit openings at the burner mouth. The high-impulse burner is preferably guided through the burner block horizontally or at an inclination of less than 10° relative to the horizontal. The at least one oxygen lance, which is preferably guided through the burner block axially parallel to the high-impulse burner, opens out of the burner block from a geodetic perspective above the high-impulse burner, ieinto the furnace chamber and can be guided through the burner block at a shallow angle of less than 15° (ascending or descending) relative to the axis of the high-impulse burner. Like the high-impulse burner, the at least one oxygen lance preferably has a circular or nearly circular cross-section.

[0023] A useful further development of the invention is characterized by at least one additional oxygen supply for secondary oxygen, which opens vertically into the furnace chamber below the burner mouth. This allows the chemical composition of the atmosphere below the flame to be directly influenced.

[0024] An embodiment of the invention will be explained in more detail with reference to the drawings. The schematic views show:

[0025] Fig. 1 : A burner arrangement according to the invention in longitudinal section,

[0026] Fig. 2: The burner arrangement from Fig. 1 in a front view, seen from

[0027] Direction B in Fig. 1 ,

[0028] Fig. 3: A burner assembly equipped with the burner assembly shown in Fig. 1 , 2

[0029] Glass melting furnace. The burner assembly 1 shown in Fig. 1 has a high-impulse burner 2, which is accommodated in a passage 3 of a burner quarl 4. In the example shown here, the high-impulse burner 2 has a central fuel channel 5 for supplying a carbon-containing fuel and an oxygen supply 6 arranged coaxially around the central fuel channel 5 for supplying primary oxygen. The fuel channel 5 and the oxygen supply 6 are arranged in a common housing 7, which opens into a furnace chamber 8 at a burner mouth 9. The high-impulse burner 2 is designed so that fuel and primary oxygen are introduced into the furnace chamber at a flow velocity of at least 50 m / s, preferably at least 100 m / s, particularly preferably at least 150 m / s.In such a high-impulse burner 2, the high flow velocity of the introduced gases leads to an intensive recirculation of the combustion gases present in the furnace chamber, which, among other things, leads to a reduction in the temperature of a flame forming in the furnace chamber 8 (not shown here).

[0030] To enable staged combustion, the burner arrangement 1 has oxygen lances 10, 11 for introducing secondary oxygen, which in the exemplary embodiment are arranged axially parallel to the burner axis 12 of the high-impulse burner 2 and at a distance from it. The oxygen lance 10 is arranged vertically above a horizontal plane running through the axis of the high-impulse burner 2 (burner plane 13), while the oxygen lance 11 is arranged vertically below the burner plane 13. The vertical distance of the oxygen lances 10, 11 from the high-impulse burner 2 (measured from the respective axes) should in each case be at least 1.8 times, preferably at least 2.5 times the diameter of the high-impulse burner 2 at the burner mouth 9.

[0031] In the exemplary embodiment, the oxygen lances 10, 11 are also high-impulse introduction systems, i.e. the oxygen flow introduced into the furnace chamber 8 by the oxygen lances 10, 11 has a speed of at least 50 m / s, preferably at least 100 m / s, particularly preferably at least 150 m / s. In the exemplary embodiment shown here, the oxygen lances 10, 11 and the high-impulse burner 2 are arranged one above the other in a vertical plane 14. Within the scope of the invention, however, it is also conceivable for a plurality of oxygen lances 10, 11 (not shown here) to be provided above and / or below the burner 2; these can open into the furnace chamber 8, for example, along a horizontal line or in another way, for example in a ring around the high-impulse burner 2.

[0032] The fuel channel 5 is connected to a fuel source (not shown here) via a fuel line 15. The oxygen supply 6 and the oxygen lances 10, 11 are connected to an oxygen line 19 via connecting lines 16, 17, 18, which in turn is connected to a source of an oxidant (also not shown here), for example, pure oxygen with an oxygen content of at least 90 vol.%.

[0033] A distribution device 20 is provided in the oxygen line 19, by means of which the distribution of an oxygen flow supplied via the oxygen line 19 to the connecting lines 16, 17, 18 and thus to the oxygen supply 6 and the oxygen lances 10, 11 can be controlled. This distribution device 20 exists independently of a control device (not shown here) which is nevertheless present and by means of which the total flows of fuel and oxygen supplied to the furnace chamber 8 via the fuel line 15 or the oxygen line 19 can be regulated. The distribution device 20 can be controlled by means of a controller 21, which can be a mechanical or electronic controller, as explained in more detail below by way of example.

[0034] Fig. 3 shows a glass melting furnace 23 equipped with the burner assembly 1 according to the invention. In the illustrated embodiment, the burner assembly 1 opens into the furnace chamber 8 of the glass melting furnace 23 at a side wall 24 of the glass melting furnace 23, above a molten glass 25 present in the glass melting furnace 23. Furthermore, the glass melting furnace 23 has a flue 26 through which the flue gases generated in the glass melting furnace 23 can escape.

[0035] During operation of the burner assembly 1, a fuel stream is introduced into the furnace chamber 8 via the fuel line 15 and the fuel channel 5 at the high velocity described above. A hydrocarbon-containing gas, such as natural gas, is used as the fuel, for example. At the same time, an oxygen stream is supplied via the oxygen line 19, which is preferably stoichiometric or slightly superstoichiometric to the fuel stream. The supplied oxygen stream is distributed entirely between the connecting lines 16, 17, 18 in the manner described in more detail below in the distribution device 20 and reaches the furnace chamber 8 via the oxygen supply 6 or the oxygen lances 10, 11. There, it is ignited with the fuel stream, whereupon a flame 27 forms in the furnace chamber 8.

[0036] The following operating modes are preferred: a) The majority of the oxygen is directed to the oxygen supply 6. The flows of fuel and primary oxygen introduced into the furnace chamber 8 at the burner mouth 9 of the high-impulse burner 2 are therefore at least nearly stoichiometric to one another. No oxygen is introduced via the oxygen lances 10, 11, or at most a small oxygen flow is introduced, which merely serves to cool the oxygen lances 10, 11 and does not contribute significantly to the combustion of the fuel in the furnace chamber 8. This operating mode is preferred, for example, when starting the high-impulse burner 2 or for heating up the furnace chamber 2. b) At least a majority of the oxygen is introduced evenly into the furnace chamber 8 via both oxygen lances 10, 11 (two-stage combustion).Any small residual flow is passed through the oxygen supply 6 solely to stabilize the flame forming in front of the burner mouth 9 and to cool the high-impulse burner 2. Given suitable geometric conditions in the glass melting furnace 25, the supply of oxygen via the oxygen supply can even be eliminated entirely. In this operating mode, the high-impulse burner 2 is therefore operated significantly substoichiometrically, with the majority of the oxygen required for combustion being introduced as secondary oxygen. The combustion process thus takes place largely at the outer edges of the flame, which overall lowers the flame temperature and reduces the formation of NOx compounds. c) A large portion of the oxygen is introduced into the furnace chamber 8 via the upper oxygen lance 10 (single-stage combustion).A small residual flow is introduced via the oxygen supply 6 solely for the purpose of stabilizing a flame forming in front of the burner mouth 9 and cooling the high-impulse burner. No oxygen is introduced via the oxygen lances 11, or at most a small oxygen flow, which primarily serves to cool the oxygen lance 11 and does not contribute significantly to the combustion of the fuel in the furnace chamber 8. In this operating mode, an atmosphere 28 with a significant oxygen excess forms in the area above the burner level 13. In contrast, combustion below the burner level 13 is overall substoichiometric. The atmosphere 29 forming in this area is very low in oxygen. Therefore, increased carbon monoxide is formed in this area, which, when the burner arrangement 1 is in use, suppresses the formation of foam on the molten glass 25 or reduces foam that has already formed.

[0037] Surprisingly, it has been found that in this operating mode c) with the aforementioned high exit velocities of fuel and oxygen, the excess carbon monoxide occurring below the burner level 32 in the atmosphere 29 present there does not form a stationary formation, even with a uniform introduction of fuel and oxygen, but rather fluctuates in time and space. This effect, which—without limiting the invention in any way—is possibly attributable to turbulent flow processes at the interfaces between the introduced oxygen and fuel streams and the strongly recirculating furnace gases in the furnace chamber 8, is all the more pronounced the higher the velocity of the gases introduced into the furnace chamber 8.However, the temporal and spatial fluctuation of the carbon monoxide content in the furnace chamber 8 below the burner level 12 leads to an improved reduction of foam formation in a glass melt 25 located in the furnace chamber 8.

[0038] List of reference symbols

[0039] 1 burner arrangement

[0040] 2 high-impulse burners

[0041] 3 Implementation

[0042] 4 burner stone

[0043] 5 Fuel channel

[0044] 6 Oxygen supply

[0045] 7 housings

[0046] 8 Furnace room

[0047] 9 Brenner mouth

[0048] 10 oxygen lance

[0049] 11 Oxygen lance

[0050] 12 burner axis

[0051] 13 Brenner level

[0052] 14 Vertical plane

[0053] 15 Fuel line

[0054] 16 connecting line

[0055] 17 connecting line

[0056] 18 connecting line

[0057] 19 Oxygen line

[0058] 20 Distribution device

[0059] 21 Control

[0060] 22 -

[0061] 23 glass melting furnace

[0062] 24 side wall

[0063] 25 glass melt

[0064] 26 Smoke extractor

[0065] 27 Flame

[0066] 28 Atmosphere

[0067] 29 Atmosphere

Claims

Patent claims 1. A method for heating a glass melting furnace using staged combustion in a furnace chamber (8), in which a carbon-containing fuel stream and a primary oxygen stream which is substoichiometric to the fuel stream are introduced into the furnace chamber (8) by means of a burner arrangement (1) and are combusted together there to form a flame (27), and in which a secondary oxygen stream is introduced into the furnace chamber (8) by means of the burner arrangement (1) in such a way that an oxygen-rich atmosphere (28) is generated in an upper region of the furnace chamber (8) and an oxygen-poor and carbon monoxide-rich atmosphere (29) is generated in a lower region of the furnace chamber (8), characterized in that the carbon monoxide content is continuously varied in at least a partial region of the oxygen-poor and carbon monoxide-rich atmosphere (29) generated in the lower part of the furnace chamber (8).

2. Method according to claim 1, characterized in that the variation of the carbon monoxide content in at least a partial region of the atmosphere (29) generated in the lower region of the furnace chamber (8) is brought about by a temporal and / or spatial variation of the mass flow(s) of fuel and / or primary oxygen and / or secondary oxygen introduced into the furnace chamber (8).

3. Method according to claim 2, characterized in that the temporal and / or spatial variation of the mass flow(s) of fuel and / or primary oxygen and / or secondary oxygen introduced into the furnace chamber (8) is brought about by pivoting or rotating the flame (27) and / or by a pulsed introduction of the fuel flow, the primary oxygen flow, and / or the secondary oxygen flow.

4. Method according to one of the preceding claims, characterized in that the variation of the carbon monoxide content in at least a partial region of the atmosphere (29) generated in the lower region of the furnace chamber (8) is brought about by the fuel flow and / or the primary oxygen flow and / or the secondary oxygen flow being introduced into the furnace chamber (8) at a speed of at least 50 m / s, preferably at least 150 m / s, particularly preferably at least 250 m / s.

5. Burner arrangement for carrying out a method according to one of the preceding claims, with a fuel channel (5) for introducing a carbon-containing fuel into a furnace chamber (8), an oxygen supply (6) for supplying primary oxygen into the furnace chamber (8) and an oxygen supply for supplying secondary oxygen in an upper region of the furnace chamber (8), and with means for continuously changing the carbon monoxide content of an atmosphere (29) forming in a lower region of the furnace chamber (8).

6. Burner arrangement according to claim 5, characterized in that the fuel channel (5) and the oxygen supply (6) for primary oxygen are arranged in a housing (7) of a burner which opens into the furnace chamber (8) at a burner mouth (9), and the oxygen supply for secondary oxygen is designed as an oxygen lance (10) which opens into the furnace chamber (8) vertically above a burner plane (13) of the burner.

7. Burner arrangement according to claim 5 or 6, characterized in that the means for continuously changing the carbon monoxide-rich atmosphere (29) forming in the lower region of the furnace chamber (8) comprise means for temporally or spatially changing the mass flow(s) of fuel and / or primary oxygen and / or secondary oxygen introduced into the furnace chamber (8).

8. Burner arrangement according to claim 5 to 7, characterized in that the means for continuously changing the carbon monoxide content of the atmosphere (29) forming below the burner plane comprise means for pivoting and / or rotating the flame (27).

9. Burner arrangement according to one of claims 5 to 8, characterized in that the burner is a high-impulse burner (2) and / or the at least one oxygen lance (10, 11) is a high-impulse lance, in which the supplied gas is introduced at a speed of at least 50 m / s, preferably at least 100 m / s, particularly preferably at least 150 m / s.

10. Burner arrangement according to one of claims 5 to 9, characterized by at least one oxygen supply for secondary oxygen, which opens vertically below the burner mouth (9) into the furnace chamber (8).

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