Method and device for treating and neutralising environmentally harmful and / or toxic exhaust gases

Abstract

The invention relates to a method for treating and neutralising environmentally harmful and / or toxic exhaust gases from industrial process facilities by thermally reacting or splitting the exhaust gases in a combustion chamber. The invention aims to create an effective method for treating and neutralising environmentally harmful and / or toxic exhaust gases in which simultaneously the consumption of combustible gases and the emission of CO / CO2 / NOx are reduced. This is achieved in that the exhaust gases in the combustion chamber (1) are mixed with remotely generated heated air (17) from a separate air heater (21) to a temperature which is above the ignition temperature of the exhaust gases, and that after ignition of the exhaust gases, the air supplied from the air heater (21) is supplied further at a temperature which is below the ignition temperature of the exhaust gases while the thermal splitting continues. The air (17) heated remotely outside the combustion chamber (1) is heated in the air heater (21) at least temporarily to a temperature above the ignition temperature of the exhaust gases, i.e. to approximately 700 °C to 900 °C.

Description

[0001] The invention relates to a method and a device for the treatment and neutralization of environmentally harmful and / or toxic exhaust gases from industrial process plants.

[0002] Various processes have been developed for the purification of exhaust gases, for example, those originating from semiconductor manufacturing processes such as CVD, LP-CVD, plasma-CVD, plasma etching, or similar processes. In the majority of cases, processes are used in which the exhaust gases are burned and / or thermally decomposed. This produces gaseous, solid, or soluble, but harmless reaction products. The latter are passed through a scrubber, where the solid and / or soluble reaction products are washed out of the exhaust gases using a sorbent. Water is usually used as the sorbent.

[0003] An example of such an exhaust gas purification device is known from WO 96 / 23173. This device contains a combustion chamber with a burner, to which fuel gas, such as hydrogen and oxygen or air, as well as the process exhaust gas to be decomposed are fed. Above the combustion chamber is a scrubbing chamber with a spray device for spraying the sorbent. The combustion chamber is located within an outer tube and is delimited by an inner tube, with the outer tube also enclosing the scrubbing chamber located above the combustion chamber.

[0004] The reaction products produced in the combustion chamber are passed between the inner and outer pipes into the wash chamber and from there into the ambient air via an extraction system.

[0005] With such an exhaust gas purification system, a wide variety of gases, such as SiH4, PH3, B2H6, TEOS (tetraethoxysilane) from CVD processes, C2F6, CF4, CH3F, Cl2, BCl3 from dry etching and other processes, can be disposed of with very high efficiency. The prerequisite is that the exhaust gas purification system parameters are tailored to the type and quantity of gases or vapors to be purified, ensuring that combustion or thermal decomposition occurs through the combustion of fuel gas and oxygen in excess oxygen.

[0006] Another example of an exhaust gas purification device is disclosed in EP 1 796 820 B1, which includes a reactor chamber comprising an outer and an inner wall, the inner wall tapering downwards in a funnel shape. Located on top of the reactor chamber is a device for thermally treating exhaust gases, closing the reactor chamber at the top. The device is provided with inlets for the combustion gases oxygen and hydrogen, as well as for the exhaust gases into the reactor chamber. The tapered reactor chamber is further provided at its upper edge with an overflow for a sorbent, allowing a uniformly downward-flowing water film to form on the inside of the reactor chamber. The outer and the downwardly tapered inner walls are connected to one another by an annular plate, and the space between them is filled with the sorbent.

[0007] The lower end of the reactor chamber is provided with an exhaust outlet and ends in a water tank to collect the water flowing down into the reactor chamber, which at the same time flushes out solid reaction products.

[0008] The exhaust gas outlet is connected to a washing column arranged next to the reactor chamber and filled with a filling material, so that the already thermally treated reaction exhaust gases can be post-treated by removing the water-soluble components from the reaction exhaust gas by means of spray nozzles whose spray direction is directed against the ascending gas flow.

[0009] A similar exhaust gas purification device is described in US 20200018630 ​​A1.

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

[0011] The tank contains heating elements in the form of fins to heat the damping air, while water is sprayed into the tank to reduce the deposition of solids.

[0012] DE 33 18 796 A1 describes an afterburner device particularly suitable for connection to laboratory furnaces from which gases or vapors are to be extracted and largely afterburned. The device comprises a heating element mounted in a central cavity of an insulating tube. The front face of the cavity has a conical inlet opening into which a flow tube extends with its outlet opening. The device enables the extraction of gases or vapors from a laboratory furnace by creating a slight negative pressure. The gases or vapors are mixed with fresh air and then combusted almost completely.

[0013] The invention is based on the object of creating an effective method and a device for the treatment and neutralization of environmentally harmful and / or toxic exhaust gases, which simultaneously achieves a reduction in the consumption of fuel gases and a reduction in the emission of CO / CO2 / NOx.

[0014] This is achieved by a process for the treatment and neutralisation of environmentally harmful and / or toxic exhaust gases from process plants by thermal conversion or splitting of the exhaust gases in a combustion chamber. The exhaust gases are mixed in the combustion chamber with remotely generated heated air from a separate air heater to a temperature which is above the ignition temperature of the exhaust gases and that after the ignition of the exhaust gases the air supplied from the air heater is fed further at a temperature which is below the ignition temperature of the exhaust gases while the thermal splitting is continued.

[0015] In a continuation of the invention, the air heated remotely outside the combustion chamber is heated in the air heater at least briefly to a temperature above the ignition temperature of the exhaust gases, ie to approximately 700 °C to 900 °C.

[0016] Furthermore, after the exhaust gases have been ignited, the remotely heated air can be fed into the combustion chamber at a reduced temperature of approximately 200 °C, at least as long as the flame in the combustion chamber remains intact. This allows the thermal treatment of the exhaust gases to be carried out with the lowest possible energy consumption.

[0017] In order to achieve complete conversion of the exhaust gases into harmless components, ambient air should be supplied to the air heater in such a quantity that a stoichiometric oxygen surplus is created in the combustion chamber when it mixes with the exhaust gases.

[0018] To ensure that exhaust gases and air mix sufficiently, the exhaust gas and the remotely heated air should be fed into the combustion chamber in essentially parallel flow, but with different flow velocities.

[0019] Better mixing of the exhaust gases with the heated air is achieved when the remotely heated air is swirled with the supplied exhaust gas as it enters the combustion chamber.

[0020] A further embodiment of the invention is characterized in that, in order to convert exhaust gases which are difficult or non-flammable to ignite in the combustion chamber, an additional injection of fuel gas takes place via one or more fuel gas nozzles during the supply of such exhaust gases, wherein the mixing of the additionally injected fuel gas with the simultaneously injected air from the air heater takes place in the sense of an external mixing combustion.

[0021] Hydrogen is preferably injected as an additional fuel gas, although other fuel gases such as acetylene, ammonia, propane, propylene or methane, etc. are also suitable.

[0022] The object underlying the invention is also achieved in a device for carrying out the method for treating and neutralising environmentally harmful and / or toxic waste gases from process plants in the semiconductor industry by thermal conversion or splitting of the waste gases in a combustion chamber which is provided with a supply device for air and waste gases and ends in the combustion chamber, in that a central air nozzle is provided for supplying heated air into the combustion chamber, which on the one hand is connected via the supply device to an air heater outside the combustion chamber and on the other hand is equipped on the inlet side of the combustion chamber with a swirling device which consists of a round insert provided with baffles and air outlets, which is arranged centrally in the outlet of the central air nozzle,to swirl the air supplied from the air heater and the air entering the combustion chamber in a mixing area to form a flame cone.

[0023] Preferably, the round insert is a stamped sheet metal part which is provided with parallel, spaced-apart baffles and air passages therebetween or an array of passage openings in at least one plane.

[0024] Furthermore, the baffles have a V-shaped, U-shaped or semicircular cross-section, with the opening direction being directed opposite to the flow direction of the heated air flowing past.

[0025] In a further development of the invention, several exhaust gas nozzles are provided on the inlet side of the combustion chamber, which surround the central air nozzle for the remotely heated air on a circular ring and wherein the exhaust gas is introduced obliquely to the center of the combustion chamber or obliquely to the axis of symmetry.

[0026] Alternatively, instead of the individual exhaust nozzles, an annular gap can be provided that concentrically surrounds the central air nozzle and may be interrupted once or several times.

[0027] Preferably, the exhaust gas nozzles arranged on a circular ring around the central air nozzle or the annular gap(s) are aligned obliquely to the center of the combustion chamber at an angle of 40° to 60°, but preferably at 45°.

[0028] For the safe conversion of incombustible exhaust gases or incombustible exhaust gas components, additional fuel gas nozzles are provided which are arranged around the exhaust gas nozzles in the cover of the combustion chamber around the exhaust gas nozzles or the annular gaps or between them and which inject the additional fuel gas, hydrogen, into the combustion chamber at a shallow angle.

[0029] The flat angle is 70° to 88°, but preferably around 84.5° to the horizontal.

[0030] With the method according to the invention and the associated device, all exhaust gases from industry and in particular from the semiconductor industry can be converted with reduced energy costs and less fuel gas and in an environmentally friendly manner with lower CO / CO2 / NOx emissions.

[0031] In particular, the invention achieves a considerable saving of hydrogen, since, for example, in the semiconductor industry, combustible gases are used in many processes during 90 - 95 % of the total process time, so that during this time it is sufficient to supply heated air to the exhaust gases for combustion, whereas hydrogen is only required in the remaining very short process time during cleaning and etching processes, i.e. 5 - 10 % of the total process time.

[0032] In addition, significantly less nitrogen oxide is produced because the flame temperature is well below 1,000 °C most of the time.

[0033] The invention is explained in more detail below using an exemplary embodiment. The accompanying drawing figures show: Fig. 1: an overview of a device for the treatment and neutralization of environmentally harmful and / or toxic exhaust gases, consisting of a downwardly tapering and bottom-open combustion chamber, which is equipped at the top with a cover with a supply device for supplying heated air and the exhaust gases, which is at least partially provided by a cylindrical container for a sorption liquid with an overflow for forming a liquid film on the inner surface of the combustion chamber, wherein the lower end of the combustion chamber is connected via a transfer line to a scrubber column for wet cleaning of the thermally pretreated exhaust gases; Fig. 2: the device according to Fig. 1 with a partial sectional view of the supply device for remotely heated air and exhaust gases, as well as the combustion chamber; Fig. 3: the device according to Fig. 2 with additional fuel gas injection; Fig. 4: Details of the air heater equipped with heating rods or heating coils in the supply device for heated air and the exhaust gases; Fig. 5: The air heater with baffle plates and air passages in between in the air outlet to the combustion chamber, as well as the exhaust gas and fuel gas supply; Fig. 6: A detailed view of the air outlet to the combustion chamber with a round insert equipped with baffle plates, and Fig. 7: The air outlet to the combustion chamber seen from below.

[0034] Fig. 1 shows an overview of a device for the treatment and neutralization of environmentally harmful and / or toxic exhaust gases from process plants in the semiconductor industry or similar industries, as well as process plants in which such toxic exhaust gases are generated.

[0035] Such exhaust gases, which originate from process modules in the production of semiconductors, for example for microelectronics, or photovoltaics, such as CVD, LP-CVD, plasma-CVD, plasma etching or similar processes, are generally extremely toxic or at least harmful to the environment and are generally neutralized by thermal processes such as oxidation or other conversion in a flame at high temperatures to such an extent that there is no longer any danger to health or the environment. The high temperatures during the conversion of the exhaust gases, however, have the disadvantage that above a combustion temperature of around 1,000 °C, environmentally harmful NOx, CO and CO2 are produced in significant quantities. The formation of NOx increases exponentially with increasing temperature.

[0036] Such a known device consists of a combustion chamber 1 which is open at the bottom and vertically aligned, which tapers conically towards the bottom and which is closed at the top with a cover 2 ( Fig. 1 , 2 ). The cover 2 is equipped with a supply device 3 for supplying air and the exhaust gases into the combustion chamber 1. Furthermore, the combustion chamber 1 is at least partially surrounded by a container 4 for holding a sorption liquid 5, such as water, which is provided at the top with an overflow 6 directed into the combustion chamber 1 ( Fig. 4, 5 ) for forming a liquid film 8 running down the conically tapered inner surface 7 of the combustion chamber 1. This liquid film 8 is known to have the task of preventing deposits of solid reaction products on the inner surface 7 of the combustion chamber 1. The container 4 surrounding the combustion chamber 1 simultaneously serves to cool it.

[0037] The lower end of the combustion chamber 1 ends in a liquid tank 9 for receiving the liquid flowing down from the combustion chamber 1 and is connected via a transfer line 10 to a scrubber column 11 located next to the combustion chamber 1 for wet cleaning / aftertreatment of the exhaust gases thermally pretreated in the combustion chamber 1 ( Fig. 1 ). With the generally multi-stage scrubber column 11, the solid and / or washable or soluble components still present in the exhaust gas or those formed during the thermal conversion are removed from the exhaust gas in countercurrent by directing the exhaust gas upwards in the scrubber column 11 past several spray nozzles (not shown) arranged one above the other ( Fig. 1 ). The cleaned exhaust gas is finally released into the environment from the top of the scrubber column 11 via pipes and a filter device or exhaust system 12.

[0038] In the liquid tank 9, both the water flowing down from the combustion chamber 1 and the water from the scrubber column 11 are collected via the transfer line 10 up to a predetermined level 13. Furthermore, the liquid tank 9 is connected to the container 4 via a return line 14 and a filter (not shown) with a pump 15, so that together with the overflow 6 into the combustion chamber 1, a circuit of the sorption liquid 5 is formed ( Fig. 4, 5 ).

[0039] It is essential to the invention that the supply device 3 in the cover 2 is provided with a central air nozzle 16 for supplying remotely heated air 17 into the combustion chamber 1 ( Fig. 2 , 3) ends by supplying fresh and compressed ambient air 18 to the supply device 3 simultaneously via a side channel compressor 17' (not shown). Furthermore, several exhaust gas nozzles 19 are provided surrounding the central air nozzle 16, which are directed into the combustion chamber 1 and which serve to supply exhaust gases to be thermally treated, including from different process modules, into the combustion chamber 1 ( Fig. 2 ).

[0040] The exhaust nozzles 19 surround the central air nozzle 16 in one or more concentric rings, in which Fig. 1 e.g. four or more exhaust nozzles 19 are provided. Instead of the individual exhaust nozzles 19, an annular gap 20 concentrically surrounding the central air nozzle 16 and possibly interrupted once or several times may be provided ( Fig. 6 ).

[0041] In order to achieve sufficient and rapid mixing of the heated air supplied via the central air nozzle 16 from an air heater 21 in the supply device 3 into the combustion chamber 1 with the exhaust gases supplied via the exhaust gas nozzles 19, it is expedient to supply the air heated outside the combustion chamber 1 and the exhaust gases either with different flow velocities to the combustion chamber 1 or at least the heated air via a swirling device 22 ( Fig. 6, 7 ), the latter consisting of a round insert 24 provided with baffles 23, which is arranged centrally in the outlet of the central air nozzle 16 ( Fig. 6, 7 ). The insert 23 is, for example, a stamped sheet metal part provided with parallel, spaced-apart baffles 23 and air passages 23' between them in at least one plane. In principle, it is also possible to provide an array of stamped passages (not shown) in the insert instead of the baffles 23.

[0042] The baffles 23 can have a V-, U-shaped or semicircular cross-section, which are angled / directed against the flow direction of the heated air ( Fig. 4 bis 6 ), i.e., the opening of the cross-section is directed against the flow direction of the supplied remotely heated air 17. In this way, the heated air 17 directed toward the baffle plates 23 is swirled particularly strongly and enters the mixing area 25 of the combustion chamber 1 as an air vortex.

[0043] The swirling device 22 fulfils two tasks, namely, firstly, to act as a flow resistance in the central air nozzle 16, so that, viewed in the direction of air flow, an overpressure is created in front of the insert 24 and thus in the air heater 21, so that the heated air 17 emerges at an accelerated rate from the central air nozzle 16 into the combustion chamber 1, and secondly, to strongly swirl the air passing through the central insert 24 before it emerges from the air nozzle 16 or during the exit from the air nozzle 16 ( Fig. 6 ).

[0044] The heated and swirled air fed into the combustion chamber 1 in this way is intensively mixed with the exhaust gas to be treated, which is fed tangentially to the injected heated air via the exhaust nozzles 19, in the mixing area 25, so that the exhaust gas is ignited by the heated air and can be chemically converted, forming a flame cone 26 ( Fig. 3 ).

[0045] The mixing of the heated air with the supplied exhaust gases can also be improved if the exhaust nozzles 19, 20 arranged on a circular ring around the central air nozzle 16 are aligned obliquely to the center of the combustion chamber 1 at an angle of approximately 40° to 60°, preferably approximately 45°. Alternatively, the exhaust nozzles 19, 20 can also be aligned in the same direction obliquely to the axis of symmetry of the combustion chamber 1, so that the exhaust gas is additionally swirled by the plurality of exhaust nozzles 19, 20. This achieves even faster mixing of the centrally supplied heated air with the exhaust gas. The heated air and the exhaust gases can also be supplied at different flow velocities so that, according to Bernoulli's law, transverse forces arise at the interfaces between the gases, which likewise promote their mixing.

[0046] The heated air is generated in a separate air heater 21 in the supply device 3 remotely outside or above the combustion chamber 1. The air heater 21 is connected on the output side to the central air nozzle 16 and on the input side to an air compressor (not shown), e.g. a side channel compressor, which sucks in cold ambient air 18 ( Fig. 4 ).

[0047] To heat the air sucked into the air heater 21, a heating device 27 is provided, e.g. heating rods, which are arranged in the air heater 21 in one or more levels, each next to each other and transverse to the flow direction of the supplied ambient air 18 ( Fig. 3 ), whereby commercially available electric or halogen heating elements can be used ( Fig. 3 ). However, the heating rods 27 can also be arranged longitudinally to the supplied ambient air 18 in the air heater 21, or heating coils can be used.

[0048] It is important that it is possible to heat the air sucked into the air heater 21 with the heating device 27 to 700 to 900 °C, at least briefly, and to inject it into the combustion chamber 1 at this temperature in a swirling manner.

[0049] In order to thermally decompose the exhaust gases, also referred to as raw gas, introduced into the combustion chamber 1 via the exhaust nozzles 19, 20 and convert them into washable products, air heated to approximately 900 °C is simultaneously fed to the combustion chamber 1 via the central air nozzle 16 and mixed with the exhaust gases. The exact required temperature of the supplied air as fuel gas depends on the current ignition temperature of the exhaust gases or exhaust gas mixture introduced into the combustion chamber 1, i.e. the heated air supplied must have at least the current ignition temperature. The thermal conversion can also be improved if the exhaust gases are also preheated before being introduced into the combustion chamber 1.

[0050] If the exhaust gases are combustible, which often originate from coating processes, they ignite and a flame forms, whereupon the temperature of the air heated in the air heater 21 can be reduced to as low as 200 °C, thereby saving considerable energy.

[0051] If the flame goes out, the supply of exhaust gas must be stopped immediately and the supplied air must be heated again to 900 °C or the ignition temperature so that the thermal treatment can be continued after the exhaust gas supply has been interrupted.

[0052] For complete and safe thermal conversion of the exhaust gases in the combustion chamber 1, the oxygen supplied with the ambient air must be supplied in stoichiometric excess.

[0053] The particular advantage of arranging the air heater 21 outside the combustion chamber 1 is that the electrical heating device 27 in the air heater 21 is only surrounded by ambient air, thus ensuring that no disturbing deposits can form on the heating rods or heating coils of the electrical heating device 27.

[0054] Many processes in the semiconductor industry consist of a coating and a cleaning step. During the cleaning step, flammable gases are often used, which can be treated as described above.

[0055] However, during cleaning steps, gases are used that are often non-flammable and / or that require a particularly high temperature for conversion. To achieve this high temperature in the combustion chamber 1, an additional fuel gas injection 28, preferably hydrogen, or another suitable fuel gas, is provided with one or more fuel gas nozzles during the supply of such exhaust gases, which are arranged around the exhaust gas nozzles 19, 20 in the cover 2 of the combustion chamber 1 ( Fig. 2 , 4, 5 ) and which inject the fuel gas at an angle of 70° to 88°, preferably at an angle of 84.5° to the horizontal, i.e. very steeply, into the combustion chamber 1. The mixing of the fuel gas with the simultaneously centrally injected and swirled air from the air heater 21 takes place here in the sense of external mixing combustion, so that repercussions on the feed device 3 can be excluded.

[0056] The temperature required for the conversion in the combustion chamber 1 can be achieved, for example, by using hydrogen as the fuel gas and the air injected into the combustion chamber 1 from the air heater 21. It is understood that other fuel gases such as acetylene, ammonia, propane, propylene, or methane can also be used instead of hydrogen.

[0057] In order to be able to monitor the existence of the flame in the combustion chamber 1, which is necessary for the thermal conversion of the exhaust gases in any case, a flame monitoring system is provided. Bezugszeichenliste

[0058] 1 Combustion chamber 2 Lid 3 Feed device 4 Vessel 5 Sorption liquid 6 Overflow 7 Inner surface 8 Liquid film 9 Liquid tank 10 Transfer line 11 Scrubber column 12 Filter device / exhaust system 13 Level 14 Return line 15 Pump 16 Central air nozzle 17 Heated air 17 Side channel blower / compressor 18 Ambient air 19 Exhaust nozzles 20 Annular gap 21 Air heater 22 Swirling device 23 Baffle plate 23 Air passage 24 Round insert 25 Mixing area 26 Flame cone 27 Heating device 28 Fuel gas nozzles

Claims

1. A method for treating and neutralizing environmentally harmful and / or toxic exhaust gases from industrial process plants through thermal conversion or splitting of the exhaust gases in a combustion chamber, wherein the exhaust gases in the combustion chamber (1) are mixed with remotely generated heated air (17) from a separate air heater (21) to a temperature above the ignition temperature of the exhaust gases, and wherein, after ignition of the exhaust gases, the air fed from the air heater (21) continues to be fed at a temperature below the ignition temperature of the exhaust gases so as to continue the thermal splitting.

2. The method as claimed in claim 1, wherein the air (17) heated remotely outside the combustion chamber (1) is at least temporarily heated to a temperature above the ignition temperature of the exhaust gases, that is to say to approx. 700°C to 900°C, in the air heater (21).

3. The method as claimed in claim 1 or 2, wherein, after ignition of the exhaust gases in the combustion chamber (1), the remotely heated air (17) continues to be fed at a temperature of approx. 200°C.

4. The method as claimed in one of claims 1 to 3, wherein ambient air (18) is fed to the air heater (21) in such an amount that stoichiometrically an excess of oxygen is established in the combustion chamber (1) upon mixing with the exhaust gas.

5. The method as claimed in one of claims 1 to 4, wherein the exhaust gas and the remotely heated air (17) are fed to the combustion chamber (1) in substantially parallel flow or at different flow rates.

6. The method as claimed in one of claims 1 to 5, wherein the remotely heated air is swirled when entering the combustion chamber (1).

7. The method as claimed in one of claims 1 to 6, wherein, in order to convert hardly flammable or nonflammable exhaust gases in the combustion chamber (1), an additional injection of fuel gas is effected by way of one or more fuel gas nozzles (28) during the feed of such exhaust gases, wherein the additionally injected fuel gas is mixed with the simultaneously injected air from the air heater (21) within the meaning of external-mixing combustion.

8. The method as claimed in claim 7, wherein the additional fuel gas injected is hydrogen, acetylene, ammonia, propane, propylene or methane.

9. An apparatus for carrying out the method for treating and neutralizing environmentally harmful and / or toxic exhaust gases from industrial process plants through thermal conversion or splitting of the exhaust gases in a combustion chamber, said apparatus being provided with a feed apparatus for air and exhaust gases, wherein the feed apparatus ends in the combustion chamber, and wherein a central air nozzle (16) is provided, characterized in that the central air nozzle (16), on the one hand, is connected to an air heater (21) outside the combustion chamber (1) by way of the feed apparatus (3) and, on the other hand, is equipped on the inlet side to the combustion chamber (1) with a swirl-inducing device (22) consisting of a round insert (24) which is provided with baffle plates (23) and air passages (23') therebetween and is arranged centrally in the outlet of the central air nozzle (16), in order to swirl the air fed from the air heater (21) and air entering the combustion chamber (1) in a mixing region (25) to form a cone of flame (26).

10. The apparatus as claimed in claim 9, characterized in that the insert (24) is a pressed sheet-metal part which is provided with the parallel baffle plates (23) arranged at a distance relative to one another and the air passages (23') therebetween or an array of passage openings in at least one plane.

11. The apparatus as claimed in claim 10, characterized in that the baffle plates (23) have a V-shaped or U-shaped or semicircular cross section, wherein the opening direction is directed counter to the flow direction of the heated air.

12. The apparatus as claimed in claim 9, characterized in that a plurality of exhaust gas nozzles (19) are provided on the inlet side to the combustion chamber (1) and surround the central air nozzle (16) for the remotely heated air on a circular ring, and wherein the exhaust gas is introduced obliquely with respect to the center of the combustion chamber (1) or obliquely with respect to the axis of symmetry.

13. The apparatus as claimed in claim 12, characterized in that, instead of individual exhaust gas nozzles (19), an annular gap (20) which concentrically surrounds the central air nozzle (16) and is possibly interrupted once or multiple times is provided.

14. The apparatus as claimed in one of claims 9 to 13, characterized in that the exhaust gas nozzles (19) arranged on a circular ring around the central air nozzle (16) or the annular gap or gaps (20) are oriented obliquely with respect to the center of the combustion chamber (1) at an angle of 40° to 60°, preferably about 45°.

15. The apparatus as claimed in one of claims 9 to 14, characterized in that fuel gas nozzles (28) for additional fuel gas are provided, which are arranged in the cover (2) of the combustion chamber (1) around the exhaust gas nozzles (19) or the annular gaps (20) and inject the additional fuel gas, namely hydrogen or another suitable fuel gas, at an acute angle into the combustion chamber (1).

16. The apparatus as claimed in claim 15, characterized in that the acute angle is from 70°-88°, preferably about 84.5°.

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