Method and device for treating and neutralizing waste gas harmful and / or toxic to environment

Abstract

The invention relates to a method for treating and neutralizing an environmentally harmful and / or toxic exhaust gas from an industrial process plant by thermally converting or thermally decomposing the exhaust gas in a combustion chamber. The aim of the invention is to create an efficient method for treating and neutralizing the exhaust gases harmful and / or toxic to the environment, said method being used simultaneously to reduce the consumption of combustible gases and to reduce the emissions of CO / CO2 / NOx. The solution for this purpose is that the exhaust gas is mixed in the combustion chamber (1) with heated air (17) generated remotely from a separate air heater (21), the temperature being higher than the ignition temperature of the exhaust gas, and after ignition of the exhaust gas, the air supplied by the air heater is continuously fed at a temperature lower than the ignition temperature of the exhaust gas while continuing thermal decomposition. Air (17) remotely outside the combustion chamber (1) is temporarily heated in an air heater (21) to a temperature above the exhaust gas ignition temperature, i.e. To about 700 DEG C to 900 DEG C.

Description

Technical Field

[0001] The present invention relates to a method and apparatus for treating and neutralizing environmentally harmful and / or toxic waste gases from industrial process equipment. Background Art

[0002] For example, semiconductor manufacturing processes such as CVD, LP-CVD, plasma CVD, and plasma etching generate exhaust gases, which are purified by various methods. In most cases, the exhaust gases are burned and / or thermally decomposed. This produces gaseous, solid, or soluble, but harmless, reaction products. The latter pass through a scrubber, where the solid and / or soluble reaction products are scrubbed from the exhaust gases using an adsorbent. Water is typically used as the adsorbent.

[0003] An example of such an exhaust gas purification system is disclosed in WO 96 / 23173. This system comprises a combustion chamber with a burner, into which combustible gas (such as hydrogen and oxygen or air) and process exhaust gas to be decomposed are introduced. A scrubbing chamber is located above the combustion chamber and has an injection device for injecting an adsorbent. The combustion chamber is located within an outer tube and is bounded by an inner tube, wherein the outer tube also surrounds the scrubbing chamber located above the combustion chamber.

[0004] The reaction products generated in the combustion chamber enter the scrubbing chamber between the inner tube and the outer tube and are discharged into the ambient air through the exhaust system.

[0005] This type of exhaust gas purification system can efficiently treat a variety of gases, such as SiH4, PH3, B2H6, and TEOS (tetraethoxysilane) from CVD processes, and C2F6, CF4, CH3F, Cl2, and BCl3 from dry etching and other processes. This requires adjusting the exhaust gas purification system parameters based on the type and volume of the gas or vapor to be purified to ensure combustion with an excess of oxygen, or thermal decomposition by burning combustible gases and oxygen.

[0006] Another example of an exhaust gas purification device is found in EP 1 796 820 B1, which provides a reactor chamber formed by an outer wall and an inner wall, wherein the inner wall tapers downwardly in a funnel-like manner. The reactor chamber is equipped with a device for thermally treating the exhaust gas, which seals the reactor chamber upward and allows the introduction of combustible gases such as oxygen and hydrogen, as well as exhaust gas, into the reactor chamber. The tapering reactor chamber is further provided with an adsorbent overflow port at its upper edge to form a uniform downward-flowing water film within the reactor chamber. The outer wall and the downward-tapering inner wall are connected by an annular plate, and the gap is filled with adsorbent.

[0007] The lower end of the reactor chamber is provided with an exhaust gas outlet and terminates in a water tank, which is used to receive water flowing down from the reactor chamber. This water is also used to flush away the solid reaction products.

[0008] The exhaust gas outlet is connected to a scrubber next to the reactor chamber, which is filled with filling material so that the heat-treated reaction exhaust gas can be post-treated, that is, the water-soluble components in the reaction exhaust gas are removed through a nozzle, and the spray direction of the nozzle is opposite to the direction of the rising air flow.

[0009] A similar exhaust gas purification device is found in US20200018630 ​​A1.

[0010] Furthermore, EP 1 129 763 B1 describes a method for extinguishing pyrophoric gases in a gas stream, which method comprises introducing preheated damping air having a relative humidity of up to 90% and a maximum temperature of 300 to 500° C. into the gas stream and introducing it into a container to extinguish the pyrophoric gases.

[0011] A heating element in the form of fins is provided in the container for heating the damping air, wherein water is sprayed into the container to reduce solid deposition. Summary of the Invention

[0012] An object of the present invention is to provide an effective method and apparatus for treating and neutralizing environmentally harmful and / or toxic waste gases, which method is simultaneously used to reduce the consumption of combustible gases and to lower CO / CO2 / NOx emissions.

[0013] The solution used to achieve this object is a method for treating and neutralizing environmentally harmful and / or toxic waste gases from process equipment by thermal conversion or thermal decomposition of the waste gases in a combustion chamber, wherein the waste gases are mixed with heated air generated remotely from an independent air heater in the combustion chamber to a temperature above the ignition temperature of the waste gases, and after ignition of the waste gases, the air supplied by the air heater continues to be fed at a temperature below the ignition temperature of the waste gases while the thermal decomposition continues.

[0014] As a further development of the invention, the air heated remotely outside the combustion chamber is heated at least briefly in the air heater to a temperature above the exhaust gas ignition temperature, ie to approximately 700° C. to 900° C.

[0015] Furthermore, after the exhaust gases have been ignited in the combustion chamber, the remote heating air can continue to be supplied at a reduced temperature of approximately 200°C, at least as long as the flame burning in the combustion chamber is still burning. This allows the thermal treatment of the exhaust gases to be carried out with the lowest possible energy consumption.

[0016] In order to completely convert the exhaust gases into harmless components, the air heater should be supplied with an amount of ambient air that, when mixed with the exhaust gases, creates a stoichiometric excess of oxygen in the combustion chamber.

[0017] To ensure adequate mixing of the exhaust gas and the air, the exhaust gas and the remote heating air should be fed into the combustion chamber in essentially parallel streams but at different flow rates.

[0018] If the remote heating air is swirled together with the exhaust gases being fed into the combustion chamber, a better mixing of the exhaust gases and the heating air is achieved.

[0019] Another technical solution of the present invention is characterized in that: in order to convert difficult-to-burn or non-flammable exhaust gases in the combustion chamber, when supplying such exhaust gases, combustible gas is additionally injected through one or more combustible gas nozzles, wherein the additionally injected combustible gas is mixed with the air injected simultaneously from the air heater in the sense of external mixed combustion.

[0020] Preferably, hydrogen is injected as an additional combustible gas, but other combustible gases such as acetylene, ammonia, propane, propylene or methane are also suitable.

[0021] A device for implementing a method for treating and neutralizing environmentally harmful and / or toxic waste gases from process equipment in the semiconductor industry by thermal conversion or thermal decomposition of such waste gases in a combustion chamber, the device being equipped with a feed device for feeding air and waste gases and terminating in the combustion chamber. In terms of this device, a solution for achieving one of the objects of the invention is provided in that a central air nozzle is provided for feeding heated air into the combustion chamber, the air nozzle being connected on the one hand to an air heater outside the combustion chamber via the feed device and on the other hand being provided with a swirling device on the inlet side facing the combustion chamber, the swirling device being formed by a circular insert with a baffle and an air channel, the insert being arranged centrally at the outlet of the central air nozzle so as to swirl the air supplied by the air heater and the air entering the combustion chamber in a mixing zone to form a flame cone.

[0022] The circular insert is preferably a stamped sheet metal part having baffles arranged in parallel and spaced apart on at least one plane and air channels or an array of through holes between the baffles.

[0023] Furthermore, the baffle has a V-shaped, U-shaped or semicircular cross section, wherein the opening direction is always opposite to the flow direction of the heating air flowing therethrough.

[0024] As a further development of the invention, a plurality of exhaust gas nozzles are provided on the inlet side facing the combustion chamber, which surround the central air nozzle for feeding remote heating air in a circular shape, wherein the exhaust gas is introduced obliquely to the center of the combustion chamber or to the axis of symmetry.

[0025] As an alternative, instead of a single exhaust gas nozzle, an annular gap can be provided which concentrically surrounds the central air nozzle and is interrupted once or several times as required.

[0026] Preferably, the exhaust gas nozzles or one or more annular gaps arranged in a circle around the central air nozzle are oriented obliquely at an angle of 40° to 60°, but preferably at an angle of approximately 45°, to the center of the combustion chamber.

[0027] In order to safely convert non-combustible exhaust gases or non-combustible exhaust gas components, additional combustible gas nozzles are provided, which are arranged around the exhaust gas nozzles in the combustion chamber cover, around the exhaust gas nozzles or the annular gaps, or between the exhaust gas nozzles or between the annular gaps, and inject the additional combustible gas hydrogen into the combustion chamber at a flat angle.

[0028] The flat angle is between 70° and 88° relative to the horizontal, but is preferably approximately 84.5°.

[0029] By using the method and related devices according to the present invention, all industrial waste gases, especially semiconductor industry waste gases, can be converted in an environmentally friendly manner while reducing energy costs and combustible gases, and reducing CO / CO2 / NOx emissions.

[0030] In particular, the present invention greatly saves hydrogen. Taking the semiconductor industry as an example, in many processes, the use time of combustible gas accounts for 90% to 95% of the total process time. Therefore, during this period, it is only necessary to provide heated air to the exhaust gas for combustion, and hydrogen is only needed during the remaining very short process time used to implement the purification and etching procedures, which accounts for 5% to 10% of the total process time.

[0031] Furthermore, because the flame temperature is well below 1000°C for most of the time, far less nitrogen oxides are produced. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The present invention will be explained in more detail below in the form of embodiments. As shown in the accompanying drawings:

[0033] Figure 1 : General view of a device for treating and neutralizing environmentally harmful and / or toxic waste gases, the device comprising a combustion chamber which tapers downwards and is open at the bottom, a cover provided on top of the combustion chamber, a feed device for feeding heated air and waste gases, the combustion chamber being provided at least partially with an overflow opening through a cylindrical container for containing an adsorption liquid, so as to form a liquid film on the inner surface of the combustion chamber, wherein the lower end of the combustion chamber is connected via a transfer conduit to a scrubber for wet purification of the thermally pretreated waste gases;

[0034] Figure 2 :according to Figure 1 A partial cross-sectional view of a feed device for feeding remotely heated air and exhaust gas and a combustion chamber in an apparatus;

[0035] Figure 3 :according to Figure 2 A device that provides additional flammable gas injection;

[0036] Figure 4 : Details of air heaters with heating rods or heating coils in the feed arrangement for feeding heated air and exhaust gases;

[0037] Figure 5 : an air heater provided with baffles and air passages between the baffles in the air outlet to the combustion chamber and at the exhaust gas and combustible gas feed;

[0038] Figure 6 : Detail of the air outlet to the combustion chamber, which has a circular insert with a baffle, and

[0039] Figure 7 : Bottom view of the air outlet to the combustion chamber. DETAILED DESCRIPTION

[0040] Figure 1 The present invention is a general view showing an apparatus for treating and neutralizing environmentally harmful and / or toxic waste gases from process equipment in the semiconductor industry or similar industries and process equipment that generates such toxic waste gases.

[0041] Such waste gases, for example, originate from semiconductor manufacturing process modules in the microelectronics or photovoltaics sectors, such as CVD, LP-CVD, plasma CVD, plasma etching, and similar processes. These are often highly toxic or at least environmentally harmful. Thermal processes, such as oxidation or other conversions in high-temperature flames, are typically used to neutralize them, rendering them harmless to health or the environment. However, the high temperatures involved in these conversion processes have a disadvantage: starting at combustion temperatures of approximately 1000°C, they generate significant amounts of environmentally harmful NOx, CO, and CO2. NOx formation increases exponentially with increasing temperature.

[0042] This known device is formed by a combustion chamber 1 which is open at the bottom and oriented vertically, which tapers conically downwards and is closed at the top by a cover 2 ( Figure 1 、 Figure 2 The cover 2 is provided with a feeding device 3 for feeding air and exhaust gas into the combustion chamber 1. In addition, the combustion chamber 1 is at least partially surrounded by a container 4 for containing an adsorption liquid 5, such as water, and having an overflow port 6 at the top thereof ( Figure 4 、 Figure 5 ), the overflow port faces the interior of the combustion chamber 1 and is used to form a liquid film 8 that flows downward along the tapered inner surface 7 of the combustion chamber 1. As is known, the function of this liquid film 8 is to prevent solid reaction products from being deposited on the inner surface 7 of the combustion chamber 1. The container 4 surrounding the combustion chamber 1 also serves to cool the combustion chamber.

[0043] The lower end of the combustion chamber 1 ends at a liquid tank 9, which is connected to a washing tower 11 located next to the combustion chamber 1 through a transfer pipe 10. The liquid tank is used to receive the liquid discharged from the combustion chamber 1, and the washing tower is used to perform wet purification / post-treatment on the exhaust gas that has been thermally pretreated in the combustion chamber 1 ( Figure 1 In the scrubbing tower 11, which is usually multi-stage, the exhaust gas flows upward through a plurality of nozzles (not shown) stacked up and down. Figure 1 ) by which solid components and / or washable or soluble components still present in the exhaust gas or formed during the thermal conversion process are removed from the exhaust gas in a countercurrent manner. The cleaned exhaust gas is ultimately discharged from the top of the scrubber 11 into the environment via a pipeline and filter device or exhaust system 12.

[0044] The water discharged from the combustion chamber 1 and the water discharged from the scrubber 11 via the transfer pipe 10 are collected in the liquid tank 9 until the predetermined liquid level 13 is reached. In addition, the liquid tank 9 is connected to the container 4 via a return pipe 14 and a filter with a pump 15 (not shown), thereby forming a circuit for the adsorption liquid 5 together with the overflow port 6 leading to the combustion chamber 1 ( Figure 4 、 Figure 5 ).

[0045] The novelty of the present invention is that the feed means 3 in the cover 2 terminates in a central air nozzle 16 for feeding remotely heated air 17 into the combustion chamber 1 ( Figure 2 、 Figure 3 ), at the same time, the compressed fresh ambient air 18 is provided to the feeding device 3 through the side channel compressor 17' not shown in the figure. In addition, there are multiple exhaust gas nozzles 19 surrounding the central air nozzle 16. The exhaust gas nozzles are directed to the interior of the combustion chamber 1 and are used to feed the exhaust gas to be heat-treated from different process modules into the combustion chamber 1 ( Figure 2 ).

[0046] The exhaust gas nozzles 19 are arranged in one or more concentric rings around the central air nozzle 16, wherein Figure 1 For example, four or more exhaust gas nozzles 19 are provided. Instead of a single exhaust gas nozzle 19, an annular gap 20 can also be provided, which concentrically surrounds the central air nozzle 16 and is interrupted once or several times as required ( Figure 6 ).

[0047] In order to quickly and thoroughly mix the heated air entering the combustion chamber 1 from the air heater 21 in the feed device 3 via the central air nozzle 16 with the exhaust gas fed from the exhaust gas nozzle 19, it is best to feed the air heated outside the combustion chamber 1 and the exhaust gas into the combustion chamber 1 at different flow rates, or at least feed the heated air into the combustion chamber 1 through the swirl device 22 ( Figure 6 、 Figure 7), which is formed by a circular insert 24 with a baffle 23, which is centrally arranged at the outlet of the central air nozzle 16 ( Figure 6 、 Figure 7 The insert 23 is, for example, a stamped sheet material having, on at least one plane, parallel, spaced-apart baffles 23 and air passages 23' between the baffles. In principle, an array of stamped through-holes (not shown) could also be provided on the insert in place of the baffles 23.

[0048] The cross section of the baffle 23 may be V-shaped, U-shaped or semicircular, and its angle / direction is opposite to the flow direction of the heated air ( Figures 4 to 6 ), that is, the opening direction of the cross section is opposite to the flow direction of the fed remote heated air 17. In this way, the heated air 17 toward the baffle 23 will swirl particularly strongly and enter the combustion chamber 1 in the form of an air vortex in the mixing zone 25.

[0049] The swirl device 22 has two functions. First, it acts as a flow resistance in the central air nozzle 16 so as to generate an overpressure in front of the circular insert 24, that is, in the air heater 21, as viewed in the direction of air flow, thereby accelerating the heated air 17 from the central air nozzle 16 into the combustion chamber 1; second, it causes the air flowing through the circular insert 24 to be strongly swirled before or during the process of leaving the central air nozzle 16 ( Figure 6 ).

[0050] The swirling heated air fed into the combustion chamber 1 in this manner is fully mixed with the exhaust gas to be treated in the combustion chamber 1. The exhaust gas is tangentially mixed with the injected heated air in the mixing zone 25 through the exhaust gas nozzle 19. In this way, the exhaust gas can be ignited by the heated air and chemically converted, forming a flame cone 26 ( Figure 3 ).

[0051] Mixing of the heated air and the supplied exhaust gas can also be improved if the exhaust gas nozzles 19, arranged in a ring around the central air nozzle 16, are tilted at an angle of approximately 40° to 60°, preferably approximately 45°, relative to the center of the combustion chamber 1. Alternatively, the exhaust gas nozzles 19 can be tilted in the same direction relative to the axis of symmetry of the combustion chamber 1, thereby causing the exhaust gas to swirl further under the action of multiple exhaust gas nozzles 19. This further accelerates the mixing of the centrally supplied heated air and exhaust gas. The heated air and exhaust gas can also be fed at different flow rates. According to Bernoulli's principle, this generates transverse forces at the interface between the gases, which also promote mixing.

[0052] The heated air is generated in a separate air heater 21 in the feed device 3, which is remotely generated outside or above the combustion chamber 1. The outlet side of the air heater 21 is connected to the central air nozzle 16, and the inlet side is connected to an air compressor (not shown) (for example, a side channel compressor), which draws in cold ambient air 18 ( Figure 4 ).

[0053] In order to heat the air drawn into the air heater 21, heating means 27 are provided, for example heating rods, which are arranged side by side in one or more planes in the air heater 21 and transversely to the flow direction of the fed ambient air 18 ( Figure 3 ), for this purpose, commercially available electric heating rods or halogen heating rods ( Figure 3 ) However, the heating rods 27 can also be arranged in the air heater 21 along the fed ambient air 18 , or a heating coil can be used.

[0054] It is important that the air drawn into the air heater 21 can be heated at least briefly to 700° C. to 900° C. by the heating device 27 and injected into the combustion chamber 1 in a swirling manner at this temperature.

[0055] To thermally decompose the exhaust gas (also known as feed gas) entering combustion chamber 1 via exhaust gas nozzles 19 and convert it into washable products, air heated to approximately 900°C is simultaneously introduced into combustion chamber 1 via central air nozzles 16 and mixed with the exhaust gas. The exact temperature of the air supplied as a combustible gas depends on the current ignition temperature of the exhaust gas or exhaust gas mixture entering combustion chamber 1. In other words, the heated air supplied must at least reach this current ignition temperature. Preheating the exhaust gas before entering combustion chamber 1 also improves thermal conversion.

[0056] Typically, the combustible waste gas from the coating process burns and forms a flame, at which time the temperature of the air heated in the air heater 21 can be reduced to 200° C., thereby saving a lot of energy.

[0057] As soon as the flame goes out, the exhaust gas supply must be stopped immediately and the fed air must be reheated to 900°C or the ignition temperature so that the heat treatment can continue after the exhaust gas supply is interrupted.

[0058] For a safe and thorough thermal conversion of the exhaust gases in the combustion chamber 1 , the oxygen supplied with the ambient air must be fed in a stoichiometric excess.

[0059] A particular advantage of arranging the air heater 21 outside the combustion chamber 1 is that the electric heater 27 in the air heater 21 is only flushed by ambient air, thereby ensuring that no disruptive deposits form on the heating rods or heating coils of the electric heater 27 .

[0060] Many processes in the semiconductor industry include coating and cleaning steps. When performing the cleaning step, combustible gases are often used, which can be handled as described above.

[0061] However, the purification step uses gases that are usually non-flammable and / or require particularly high temperatures for their conversion. In order to achieve such high temperatures in the combustion chamber 1, when supplying such exhaust gases, one or more additional combustible gas nozzles 28 are provided, preferably hydrogen or another suitable combustible gas, which are arranged around the exhaust gas nozzle 19 in the cover 2 of the combustion chamber 1 ( Figure 2 、 Figure 4 、 Figure 5 ), and the combustible gas is injected into the combustion chamber 1 at an angle of 70° to 88° to the horizontal plane, preferably at an angle of 84.5°, that is, very steeply. Here, the mixing of the combustible gas with the swirling air injected simultaneously from the air heater 21 is an external mixed combustion, thereby eliminating the reaction to the feed device 3.

[0062] For example, the temperature required for the conversion in the combustion chamber 1 can be reached by using hydrogen as the combustible gas and injecting air from the air heater 21 into the combustion chamber 1 in parallel. Of course, other combustible gases such as acetylene, ammonia, propane, propylene or methane can also be used instead of hydrogen.

[0063] In order to be able to monitor whether a flame is present in the combustion chamber 1 which is required for the thermal conversion of the exhaust gases in any case, a flame monitoring system is provided.

[0064] Reference Signs List

[0065] 1 combustion chamber

[0066] 2 lids

[0067] 3 Feeding device

[0068] 4 Containers

[0069] 5. Adsorption liquid

[0070] 6 Overflow

[0071] 7 Inner surface

[0072] 8 Liquid film

[0073] 9 Liquid Tank

[0074] 10 Transfer pipeline

[0075] 11 Scrubber

[0076] 12 Filter / Exhaust System

[0077] 13 Liquid Level

[0078] 14 Return pipeline

[0079] 15 pumps

[0080] 16 central air nozzles

[0081] 17 Heating the air

[0082] 17' Side Channel Compressor / Compressor

[0083] 18 Ambient air

[0084] 19 Exhaust nozzle

[0085] 20 Annular gap

[0086] 21 Air heater

[0087] 22 Spinning device

[0088] 23 Baffle

[0089] 23' air channel

[0090] 24 round inserts

[0091] 25 Mixed Zone

[0092] 26 Cone of Flame

[0093] 27 Heating device

[0094] 28 Combustible gas nozzle

Claims

1. A method and apparatus for treating and neutralizing environmentally harmful and / or toxic waste gases from industrial process equipment by thermal conversion or thermal decomposition of said waste gases in a combustion chamber (1), characterized in that: In the combustion chamber (1), the exhaust gas is mixed with heated air (17) remotely generated from an independent air heater (21) to a temperature higher than the ignition temperature of the exhaust gas. After the exhaust gas is ignited, the air supplied by the air heater (21) is continuously fed at a temperature lower than the ignition temperature of the exhaust gas while the thermal decomposition is continued.

2. A method as claimed in claim 1, wherein the heating air (17) which is heated remotely outside the combustion chamber (1) is heated in the air heater (21) at least briefly to a temperature above the ignition temperature of the exhaust gas, i.e. to approximately 700° C. to 900° C.

3. The method according to claim 1, wherein after the ignition of the exhaust gases in the combustion chamber (1), the remote heating air (17) is continued to be supplied at a temperature of about 200°C.

4. The method according to claim 1 , wherein the air heater ( 21 ) is supplied with an amount of ambient air ( 18 ) such that, when mixed with the exhaust gas, a stoichiometric excess of oxygen is generated in the combustion chamber ( 1 ).

5. The method according to claim 1, wherein the exhaust gas and the remote heating air (17) are fed into the combustion chamber (1) in substantially parallel flows or at different flow rates.

6. A method according to any one of claims 11 to 4, wherein the remotely located heated air (17) is swirled when entering the combustion chamber (1).

7. A method as claimed in any one of claims 1 to 6, wherein in order to convert difficult-to-burn or non-flammable exhaust gases in the combustion chamber (1), combustible gas is additionally injected through one or more combustible gas nozzles (28) when supplying the exhaust gas, wherein the additionally injected combustible gas is mixed with the air injected simultaneously from the air heater (21) in the sense of external mixed combustion.

8. The method according to claim 7, wherein hydrogen, acetylene, ammonia, propane, propylene or methane is injected as the additional combustible gas.

9. A device for carrying out a method for treating and neutralizing environmentally harmful and / or toxic waste gases from industrial process plants by thermal conversion or thermal decomposition of said waste gases in a combustion chamber (1), said device being equipped with a feed device (3) for feeding air and waste gases and terminating in the combustion chamber (1), characterized in that A central air nozzle (16) is provided, which is connected to an air heater (21) outside the combustion chamber (1) via the feed device (3) on the one hand, and is provided with a swirling device (22) on the inlet side facing the combustion chamber (1), the swirling device (22) being formed by a circular insert (24), which is provided with baffles (23) and air channels (23') located between the baffles (23) and is arranged centrally at the outlet of the central air nozzle (16) so that the air supplied by the air heater (21) and the air entering the combustion chamber (1) are swirled in a mixing zone (25) to form a flame cone (26).

10. The device according to claim 9, wherein the circular insert (24) is a sheet stamping, which is provided with the baffles (23) arranged in parallel and spaced apart on at least one plane and the air channels (23') or through-hole arrays located between the baffles (23).

11. The device according to claim 10, wherein the baffle (23) has a V-shaped or U-shaped or semicircular cross section, wherein the opening direction is opposite to the flow direction of the heated air.

12. An apparatus as claimed in claim 9, wherein a plurality of exhaust gas nozzles (19) are provided on the inlet side facing the combustion chamber (1), the exhaust gas nozzles (19) being arranged in a circular ring around the central air nozzle (16) for feeding remote heated air, wherein the exhaust gas is introduced obliquely to the center of the combustion chamber (1) or to the axis of symmetry.

13. The device as claimed in claim 12, wherein an annular gap (20) is provided instead of a single exhaust gas nozzle (19), said annular gap (20) concentrically surrounding the central air nozzle (16) and being interrupted once or several times as required.

14. A device as claimed in any one of claims 9 to 13, wherein the exhaust gas nozzles (19) or one or more of the annular gaps (20) arranged in a ring around the central air nozzle (16) are oriented at an angle of 40° to 60°, preferably at an angle of about 45°, to the center of the combustion chamber (1).

15. The device as claimed in claim 9, wherein a combustible gas nozzle (28) is provided for supplying an additional combustible gas, wherein the combustible gas nozzle (28) is arranged in the cover (2) of the combustion chamber (1) around the exhaust gas nozzle (19) or the annular gap (20) and injects the additional combustible gas, i.e. hydrogen or another suitable combustible gas, into the combustion chamber (1) at an acute angle.

16. The device of claim 15, wherein the acute angle is 70° to 88°, preferably about 84.5°.

Images