Methods and apparatus for treating and neutralizing exhaust gases harmful to the environment and / or toxic to the environment

Abstract

The present invention relates to a method for treating and neutralizing environmentally harmful and / or toxic exhaust gases from industrial process plants by thermal conversion or decomposition of the exhaust gases in a combustion chamber. The present invention aims to develop an effective method for treating and neutralizing environmentally harmful and / or toxic exhaust gases that simultaneously reduces fuel gas consumption and CO / CO2 / NOx emissions. This is achieved by mixing the exhaust gas (1) in the combustion chamber with air (17) remotely generated and heated by a separate air heater (21) to a temperature exceeding the ignition temperature of the exhaust gas, and by continuing to supply air from the air heater (21) at a temperature lower than the ignition temperature of the exhaust gas after ignition of the exhaust gas, so that thermal decomposition is sustained. The air (17) remotely heated outside the combustion chamber (1) is heated in the air heater (21) at least temporarily to a temperature higher than the ignition temperature of the exhaust gas, i.e., approximately 700°C to 900°C.

Description

Technical Field

[0001] The present invention relates to a method and an apparatus for treating and neutralizing environmentally harmful and / or toxic exhaust gases from industrial process plants.

Background Art

[0002] For example, various methods have been disclosed for cleaning exhaust gases generated from semiconductor manufacturing processes such as CVD, LP-CVD, plasma CVD, and plasma etching. In most cases, methods of burning or thermally decomposing the exhaust gases are used. This produces gaseous or solid or soluble and harmless reaction products. The latter is carried out by a scrubber, where the solid and / or soluble reaction products are removed from the exhaust gas by scrubbing with an adsorbent. Water is usually preferably used as the adsorbent.

[0003] An example of such an exhaust gas cleaning apparatus is disclosed in Patent Document 1. This apparatus includes a combustion space provided with a burner to which a fuel gas such as hydrogen and oxygen or air and a process exhaust gas to be decomposed are supplied. A cleaning space provided with a spraying device for spraying an adsorbent is located above the combustion space. In this case, the combustion space is arranged inside an outer tube and is separated by an inner tube, and the outer tube surrounds the cleaning space arranged above the combustion space.

[0004] The reaction products generated in the combustion space are led through the space between the inner tube and the outer tube to the cleaning space and then from there to the surrounding air through suction removal means.

[0005] Such exhaust gas scrubbing systems are used to process a variety of gases with very high efficiency, including SiH4, PH3, B2H6, and TEOS (tetraethoxysilane) generated from CVD processes, and C2F6, CF4, CH3F, C12, and BCl3 generated from dry etching processes and other processes. The parameters of the exhaust gas scrubbing system are predicated on being adapted to the type and amount of gas or vapor being scrubbed in each case, so that combustion or pyrolysis is reliably achieved by the combustion of fuel gas and oxygen in an oxygen-rich state.

[0006] Another example of an exhaust gas cleaning device is described in Patent Document 2, which includes a reaction chamber composed of an outer wall and an inner wall, the inner wall of which is funnel-shaped and narrows downwards. An exhaust gas treatment device is placed in the reaction chamber to close the reaction chamber from above, and is provided with a supply port for supplying fuel gas, oxygen and hydrogen, and exhaust gas to a supply chamber. The tapered reaction chamber is provided with an overflow for adsorbent at its upper end, thereby forming a uniformly flowing water film inside the reaction chamber. The outer wall and the inner wall which tapers downwards are connected to each other by an annular plate, and the intermediate space is filled with adsorbent.

[0007] An exhaust gas outlet is provided at the lower end of the reaction chamber and is connected to a water tank that contains the water flowing down within the reaction chamber, thereby simultaneously washing away solid reaction products.

[0008] The exhaust gas outlet is positioned adjacent to the reaction chamber and connected to a packing material-filled washing column, thereby enabling post-treatment of the already thermally treated reaction exhaust gas by removing water-soluble components from the reaction exhaust gas using a spray nozzle, with the spray direction being opposite to the upward gas flow.

[0009] A similar exhaust gas cleaning device is described in Patent Document 3.

[0010] Furthermore, Patent Document 4 describes a method for removing spontaneously combustible gases from a gas flow, which includes introducing preheated moist air with a relative humidity of up to 90% and a maximum temperature of 300-500°C into the gas flow in a container from which the spontaneously combustible gases are to be removed.

[0011] A fin-shaped heating element for heating moist air is placed in the container, and water is sprayed into the container to reduce solid buildup. [Prior art documents] [Patent Documents]

[0012] [Patent Document 1] International Publication No. 96 / 23173 [Patent Document 2] European Patent No. 1796820 [Patent Document 3] U.S. Patent Application Publication No. 2020 / 0018630 [Patent Document 4] European Patent No. 1129763 [Overview of the project]

[0013] The present invention aims to provide effective methods and apparatus for treating and neutralizing environmentally harmful and / or toxic exhaust gases. This will simultaneously achieve a reduction in fuel gas consumption and CO / CO2 / NOx emissions.

[0014] This is achieved by a method for treating and neutralizing environmentally harmful and / or toxic exhaust gases from a process plant by thermal conversion or splitting of the exhaust gases in a combustion chamber, characterized in that the exhaust gases in the combustion chamber are mixed with air heated remotely from a separate air heater to a temperature exceeding the ignition temperature of the exhaust gases, and after ignition of the exhaust gases, the air supplied from the air heater continues to be supplied at a temperature lower than the ignition temperature of the exhaust gases so that thermal splitting is sustained.

[0015] In an advanced form of the present invention, air heated remotely outside the combustion chamber is heated in an air heater to a temperature at least temporarily exceeding the ignition temperature of the exhaust gas, in other words, to approximately 700°C to 900°C.

[0016] Furthermore, after the exhaust gases ignite in the combustion chamber, remotely heated air continues to be supplied at a reduced temperature of approximately 200°C, at least as long as the flame combustion in the combustion chamber is not extinguished. In this way, the exhaust gases can be thermally treated with the lowest possible energy consumption.

[0017] To achieve the complete conversion of exhaust gases into harmless components, the ambient air should be supplied in such an amount that a stoichiometric excess of oxygen is present in the combustion chamber when mixed with the exhaust gases.

[0018] To ensure sufficient mixing of exhaust gas and air, the exhaust gas and remotely heated air should be supplied to the combustion chamber in substantially parallel flows, but at different flow rates.

[0019] Good mixing of exhaust gas and heated air is achieved when the remotely heated air swirls with the supplied exhaust gas as it enters the combustion chamber.

[0020] A further improvement of the present invention is characterized in that, in order to convert flame-retardant or non-combustible exhaust gases in the combustion chamber, an additional fuel gas is injected through one or more fuel gas nozzles during the supply of such exhaust gases, and the additionally injected fuel gas is mixed with air simultaneously injected from an air heater in the sense of external mixed combustion.

[0021] Preferably, the additional fuel gas injected is hydrogen, but other fuel gases such as acetylene, ammonia, propane, propylene, or methane are also suitable.

[0022] The object of the present invention is also achieved in an apparatus for carrying out a method for treating and neutralizing environmentally harmful and / or toxic exhaust gases from a process plant in the semiconductor industry by means of thermal conversion or decomposition of the exhaust gases in a combustion chamber, the apparatus comprising a supply device for air and exhaust gases, which is connected to the combustion chamber, and a central air nozzle for supplying heated air to the combustion chamber, the nozzle being connected on the one hand via the supply device to an air heater outside the combustion chamber and on the other hand, at the inlet side of the combustion chamber, having a baffle plate and an air passage therebetween and a vortex induction device arranged at the central part of the outlet of the central air nozzle for swirling the air supplied from the air heater and the air flowing into the combustion chamber in a mixing region to form a conical flame.

[0023] Preferably, the circular insert is a press-formed metal plate part having parallel baffle plates spaced apart from each other in at least one plane and air passages therebetween, or an array of passage openings.

[0024] Furthermore, the baffle plates have a V-shaped or U-shaped or semi-circular cross-section, and the opening directions are respectively directed opposite to the direction in which the heated air flows.

[0025] In a further development of the present invention, a plurality of exhaust gas nozzles are provided on the inlet side to the combustion chamber, and surround the central air nozzle for remotely heated air in an annular shape, and the exhaust gas is introduced obliquely with respect to the center of the combustion chamber or obliquely with respect to the axis of symmetry.

[0026] Alternatively, instead of individual exhaust gas nozzles, an annular gap may be provided that concentrically surrounds the central air nozzle and is interrupted one or more times as the case may be.

[0027] Preferably, the exhaust gas nozzles arranged annularly around the central air nozzle or around one or more annular gaps are arranged obliquely at an angle of 40° to 60°, but preferably at an angle of about 45°, with respect to the center of the combustion chamber.

[0028] For reliable conversion of non-combustible exhaust gases or non-combustible exhaust gas components, multiple additional fuel gas nozzles are provided, which are positioned around the multiple exhaust gas nozzles in the combustion chamber cover around or between multiple annular gaps, and inject additional fuel gas, hydrogen, into the combustion chamber at an oblique angle.

[0029] The angle of inclination is 70° to 88° with respect to the horizontal, but preferably about 84.5°.

[0030] The method and related apparatus of the present invention enable the conversion of all industrial emissions, particularly those from the semiconductor industry, in an environmentally friendly manner with reduced energy costs, less fuel gas, and lower CO / CO2 / NOx emissions.

[0031] In particular, the present invention significantly reduces hydrogen consumption. For example, in the semiconductor industry, flammable gases are used for 90-95% of the total process time in many processes, so at this point it is sufficient to simply supply heated air to the exhaust gas for combustion purposes. Hydrogen, on the other hand, is only required for the remaining very short process time between the cleaning and etching processes, in other words, for 5-10% of the total process time.

[0032] Furthermore, since the flame temperature remains well below 1000°C for most of the time, the amount of nitrogen oxides produced is significantly reduced. [Brief explanation of the drawing]

[0033] The present invention will be described in more detail in relation to exemplary embodiments. The accompanying drawings show the following:

[0034] [Figure 1]This is a schematic diagram of an apparatus for treating and neutralizing exhaust gases harmful to the environment and / or toxic, comprising a downwardly tapered combustion chamber, at least partially comprising a cylindrical container for an adsorbent with an overflow for forming a liquid film on the inner surface of the combustion chamber, and having a cover with an open bottom and a supply device at the top for supplying heated air and exhaust gases, the lower end of the combustion chamber is connected by a transfer line to a washing column for wet washing the thermally pretreated exhaust gases. [Figure 2] This figure shows the apparatus according to Figure 1, which includes a supply device for remotely heated air and exhaust gas, and an explanatory diagram of a partial cross-section of the combustion chamber. [Figure 3] This figure shows the apparatus relating to Figure 2, which has additional fuel gas injection. [Figure 4] This diagram shows details of an air heater equipped with a heating rod or heating coil in a supply device for heated air and exhaust gas. [Figure 5] This diagram shows an air heater equipped with baffle plates and air passages between them at the air outlet to the combustion chamber, and exhaust gas and fuel gas supply. [Figure 6] This is a detailed diagram illustrating an air outlet to a combustion chamber having a circular insert equipped with a baffle plate. [Figure 7] This diagram shows the air outlet to the combustion chamber as viewed from below. [Modes for carrying out the invention]

[0035] Figure 1 shows a schematic diagram of a process plant in the semiconductor industry or equivalent industries, and equipment for treating and neutralizing environmentally harmful and / or toxic emissions from process plants that produce toxic exhaust gases.

[0036] Such exhaust gases, for example, originate from process modules (CVD, LP CVD, plasma CVD, plasma etching, or similar processes) for the manufacture of semiconductors for microelectronics or solar power generation, and are generally highly toxic or at least harmful to the environment. They are usually neutralized by thermal treatment, such as oxidation in a high-temperature flame or some other conversion, until they no longer pose a health or environmental risk. However, the high temperatures used to convert the exhaust gases have the disadvantage of producing significant amounts of environmentally harmful NOx, CO, and CO2 from combustion temperatures of approximately 1000°C. NOx formation increases exponentially with increasing temperature.

[0037] Such known devices consist of a vertically positioned combustion chamber that is open at the bottom, narrows conically downwards, and is closed at the top by a cover 2 (Figures 1 and 2). The cover 2 is equipped with a supply device 3 for supplying air and exhaust gas to the combustion chamber 1. Furthermore, the combustion chamber 1 is at least partially surrounded by a container 4 for receiving an adsorbent liquid 5 such as water, and the container is equipped with an overflow 6 at its top to form a liquid film 8 that flows down toward the combustion chamber 1 onto the conically narrowed inner surface 7 of the combustion chamber 1 (Figures 4 and 5). As is known, this liquid film 8 serves to prevent the accumulation of solid reaction products on the inner surface 7 of the combustion chamber 1. The container 4 surrounding the combustion chamber 1 is also used for its cooling.

[0038] 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 cleaning column 11 located next to the combustion chamber 1 for wet cleaning / post-treatment of the exhaust gas preheated in the combustion chamber 1 (Figure 1). In a typical multi-stage cleaning column 11, solid and / or components that can be removed or dissolved by cleaning are removed from the exhaust gas by backflow as the exhaust gas passes through multiple injection nozzles (not shown) arranged vertically within the cleaning column 11, either remaining in the exhaust gas or formed during thermal conversion (Figure 1). The cleaned exhaust gas is ultimately released at the top from the cleaning column 11 into the environment via a pipeline and filter device or exhaust gas system 12.

[0039] Both the water flowing down from the combustion chamber and the water from the washing column 11 are collected in the liquid tank 9 via the transfer line 10 until they reach a predetermined liquid level 13. Furthermore, the liquid tank 9 is connected to a container 4 via a filter (not shown) equipped with a return line 14 and a pump 15, thereby forming a circuit for the adsorbent liquid 5 together with the overflow 6 to the combustion chamber 1 (Figures 4 and 5).

[0040] It is essential to the present invention that the supply device 3 in cover 2 is connected to a central air nozzle 16 to supply remotely heated air 17 to the combustion chamber 1 (Figures 2 and 3). This is because fresh, compressed ambient air 18 is simultaneously supplied to the supply device 3 via a side channel compressor 17' (not shown). Furthermore, a plurality of exhaust gas nozzles 19 are provided surrounding the central air nozzle 16, which are directed into the combustion chamber 1 and used to supply exhaust gas to be thermally treated to the combustion chamber 1 from different process modules as well (Figure 2).

[0041] The exhaust gas nozzles 19 surround the central air nozzle 16 with one or more concentric rings, and for example, four or more exhaust gas nozzles 19 are provided in Figure 1. Instead of individual exhaust gas nozzles 19, an annular gap 20 may be provided that concentrically surrounds the central air nozzle 16 and is interrupted once or more times (Figure 6).

[0042] For the heated air supplied from the air heater 21 of the supply device 3 to the combustion chamber 1 via the central air nozzle 16 to mix sufficiently and quickly with the exhaust gas supplied via the exhaust gas nozzle 19, it is desirable that the heated air and exhaust gas outside the combustion chamber 1 are supplied to the combustion chamber 1 at different flow rates, or at least the heated air is supplied via the vortex induction device 22 (Figures 6 and 7), the latter consisting of a circular insert 24 equipped with a baffle plate 23 and positioned in the center of the outlet of the central air nozzle 16 (Figures 6 and 7). The insert 23 is, for example, a press-formed metal sheet component comprising parallel baffle plates 23 spaced apart from each other in at least one plane and an air passage 23' positioned between them. In principle, instead of the baffle plate 23, an array of press-formed passage openings (not shown) can also be provided in the insert.

[0043] The baffle plate 23 may have a V-shaped, U-shaped, or semicircular cross-sectional shape that is tilted / directed in the opposite direction to the direction of the heated air flow (Figures 4-6), in other words, the opening of the cross-section is directed in the opposite direction to the direction of the supplied remotely heated air flow 17. As a result, the heated air 17 directed onto the baffle plate 23 receives a particularly strong vortex and flows into the mixing region 25 of the combustion chamber 1 as an air vortex.

[0044] The vortex induction device 22 performs two functions. Firstly, it acts as a flow resistance within the central air nozzle 16, creating an overpressure upstream of the insert 24 and within the air heater 21 in the direction of airflow, causing the heated air 17 to be accelerated and discharged from the central air nozzle 16 to the combustion chamber 1. Secondly, it creates a strong vortex in the air passing through the central insert 24 either before it leaves the air nozzle 16 or while it is leaving the nozzle 16 (Figure 6).

[0045] The heated and swirling air supplied to the combustion chamber 1 in this manner is vigorously mixed with the exhaust gas to be treated in the mixing region 25 within the combustion chamber 1, which has the exhaust gas supplied tangentially to the injected heated air via the exhaust gas nozzle 19. As a result, the exhaust gas is ignited by the heated air and chemically converted, forming a conical flame 26 (Figure 3).

[0046] The mixing of heated air and supplied exhaust gas can be improved if exhaust gas nozzles 19 and 20, arranged in a ring around the central air nozzle 16, are inclined at an angle of approximately 40° to 60°, preferably approximately 45°, with respect to the center of the combustion chamber 1. Alternatively, the exhaust gas nozzles 19 and 20 may be inclined in the same direction with respect to the axis of symmetry of the combustion chamber 1, thereby allowing the exhaust gas to generate further vortices through the multiple exhaust gas nozzles 19 and 20. This achieves even more rapid mixing of the heated air supplied to the center and the exhaust gas. The heated air and exhaust gas may be supplied at different flow rates, which, according to Bernoulli's principle, also generates lateral forces at the interface between the gases, promoting their mixing.

[0047] The heated air is generated in a separate air heater 21 located in a supply device 3 positioned remotely outside or above the combustion chamber 1. The air heater 21 is connected at the outlet side to a central air nozzle 16 and at the inlet side to an air compressor (not shown), such as a side-channel compressor, which draws in cold ambient air 18 (Figure 4).

[0048] A heating device 27 is provided to heat the air drawn into the air heater 21. For example, heating rods are arranged in the air heater 21 perpendicular to the flow direction of the supplied ambient air 18, adjacent to each other in one or more planes (Figure 3). Conventional electric or halogen heating rods are used for this purpose (Figure 3). The heating rods 27 may also be arranged in the air heater 21 longitudinally with respect to the supplied ambient air 18, or heating coils may be used.

[0049] It is important that the air drawn into the air heater 21 is heated to at least 700-900°C temporarily by the heating device 27, and that it can be injected into the combustion chamber 1 in a vortex at this temperature.

[0050] The exhaust gas introduced into the combustion chamber 1 via exhaust gas nozzles 19 and 20, also called untreated gas, is converted into products that can be thermally decomposed and removed by washing. Therefore, air heated to approximately 900°C is simultaneously supplied to the combustion chamber 1 via the central air nozzle 16 and mixed with the exhaust gas. The precisely required temperature of the air supplied as fuel gas depends on the ignition temperature of each flow of exhaust gas or exhaust gas mixture introduced into the combustion chamber 1; that is, the heated and supplied air must be at least at the flow ignition temperature. Thermal conversion can also be improved if the exhaust gas is preheated before being introduced into the combustion chamber 1.

[0051] If these are flammable exhaust gases, and often originate from the painting process, they can ignite and form flames, which can reduce the temperature of the air heated in the air heater 21 to 200°C, resulting in a significant reduction in energy consumption.

[0052] If the flame goes out, the exhaust gas supply must be immediately stopped, and the supplied air must be reheated to 900°C or the ignition temperature so that the heat treatment can be continued after the exhaust gas supply is interrupted.

[0053] For complete and reliable heat conversion within the combustion chamber 1, the oxygen supplied by the ambient air must be supplied in a stoichiometric excess.

[0054] A particular advantage of placing the air heater 21 outside the combustion chamber 1 is that only ambient air flows around the electric heating device 27 in the air heater 21, and therefore no obstructive deposits form on the heating rod or heating coil of the electric heating device 27.

[0055] Many processes in the semiconductor industry consist of coating and cleaning processes. During the cleaning process, flammable gases that can be treated as described above are often used.

[0056] However, in the cleaning process, non-flammable gases and / or gases that require particularly high temperatures for conversion are often used. To achieve this high temperature within the combustion chamber, an additional injection 28 of fuel gas, preferably hydrogen or another suitable fuel gas, is provided through one or more fuel gas nozzles during the supply of such exhaust gases, the fuel gas nozzles being positioned around the exhaust gas nozzles 19, 20 in the cover 2 of the combustion chamber 1 (Figures 2, 4, and 5), injecting the fuel gas into the combustion chamber 1 at an angle of 70° to 88° with respect to the horizontal, preferably 84.5°, in other words, at a very steep gradient. The fuel gas, in this case, is mixed with the swirling air simultaneously injected into the center from the air heater 21 in the sense of external mixed combustion, thereby eliminating any influence on the supply device 3.

[0057] The temperature required for conversion in the combustion chamber 1 can be achieved, for example, by using hydrogen as the fuel gas and air injected into the combustion chamber 1 in parallel from the air heater 21. Of course, other fuel gases such as acetylene, ammonia, propane, propylene, or methane can also be used instead of hydrogen.

[0058] A flame monitoring system is provided so that the presence of a flame required for the heat conversion of exhaust gas in each case can be monitored in the combustion chamber 1. [Explanation of symbols]

[0059] 1 Combustion Chamber 2 Covers 3 Feeding device 4 containers 5 Adsorption liquid 6 Overflow 7. Inner self 8 Liquid film 9 liquid tanks 10 Transfer Line 11 Washing column 12. Filtering device / exhaust gas system 13 Liquid level 14. Return Line 15 pumps 16 Central air nozzle 17. Heated air 17' Side Channel Compressor / Compressor 18. Surrounding air 19 Exhaust gas nozzle 20 Annular gap 21 Air heater 22. Evortex induction devices 23 Baffle board 23' Air passage 24 circular inserts 25 Mixed area 26 Cone-shaped flame 27 Heating device 28 Fuel gas nozzle

Claims

1. A method for treating and neutralizing environmentally harmful and / or toxic exhaust gases from an industrial process plant by thermal conversion or decomposition of the exhaust gases in a combustion chamber, characterized in that the exhaust gases in the combustion chamber (1) are mixed with air (17) remotely generated and heated by a separate air heater (21) to a temperature exceeding the ignition temperature of the exhaust gases, and after ignition of the exhaust gases, the air supplied from the air heater (21) continues to be supplied at a temperature lower than the ignition temperature of the exhaust gases so that thermal decomposition is sustained.

2. The method according to claim 1, characterized in that the air (17) heated remotely outside the combustion chamber (1) is heated in an air heater (21) to a temperature at least temporarily higher than the ignition temperature of the exhaust gas, i.e., approximately 700°C to 900°C.

3. The method according to claim 1, characterized in that after the ignition of the exhaust gas in the combustion chamber (1), remotely heated air (17) is continuously supplied at a temperature of approximately 200°C.

4. The method according to any one of claims 1 to 3, characterized in that ambient air (18) is supplied to the air heater (21) in such an amount that, when mixed with exhaust gas, it becomes a stoichiometrically excess amount of oxygen in the combustion chamber (1).

5. The method according to claim 1, characterized in that exhaust gas and remotely heated air (17) are supplied to the combustion chamber (1) in substantially parallel flows or at different flow velocities.

6. The method according to any one of claims 1 to 5, characterized in that the remotely heated air is swirled when it enters the combustion chamber (1).

7. The method according to any one of claims 1 to 6, characterized in that, in order to convert flame-retardant or non-combustible exhaust gas in a combustion chamber (1), additional fuel gas is injected through one or more fuel gas nozzles (28) during the supply of such exhaust gas, and the additionally injected fuel gas is mixed with air simultaneously injected from an air heater (21) in the sense of external mixed combustion.

8. The method according to claim 7, characterized in that the additional fuel gas injected is hydrogen, acetylene, ammonia, propane, propylene, or methane.

9. Apparatus for performing a method of treating and neutralizing environmentally harmful and / or toxic exhaust gases from an industrial process plant by thermal conversion or decomposition of the exhaust gases in a combustion chamber, wherein the apparatus comprises a supply device for air and exhaust gases connected to a combustion chamber, a central air nozzle (16) provided, on the one hand connected to an air heater (21) outside the combustion chamber (1) via a supply device (3), and on the other hand, a vortex induction device (22) comprising a baffle plate (23) and an air passage (23') between them and a circular insert (24) positioned in the center of the outlet of the central air nozzle (16) to cause a vortex in a mixing region (25) between the air supplied from the air heater (21) and the air flowing into the combustion chamber (1) to form a conical flame (26).

10. The apparatus according to claim 9, characterized in that the insert (24) is a press-formed metal sheet component comprising parallel baffle plates (23) spaced apart from each other in at least one plane and an array of air passages (23') or passage openings between them.

11. The apparatus according to claim 10, characterized in that the baffle plate (23) has a V-shaped, U-shaped, or semicircular cross-section, and the opening direction is oriented opposite to the direction in which heated air flows.

12. The apparatus according to claim 9, characterized in that a plurality of exhaust gas nozzles (19) are provided on the inlet side to the combustion chamber (1), surround a central air nozzle (16) for remote heating air in an annular shape, and the exhaust gas is introduced obliquely to the center of the combustion chamber (1) or obliquely to the axis of symmetry.

13. The apparatus according to claim 12, characterized in that, instead of individual exhaust gas nozzles (19), a central air nozzle (16) is concentrically surrounded by an annular gap (20) which is interrupted once or more times, in some cases.

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

15. The apparatus according to claim 9, characterized in that an additional fuel gas nozzle (28) for additional fuel gas is provided, which is located on the cover (2) of the combustion chamber (1) around an exhaust gas nozzle (19) or a plurality of annular gaps (20) and for injecting additional fuel gas, i.e., hydrogen or other suitable fuel gas, into the combustion chamber (1) at an acute angle.

16. The apparatus according to claim 15, characterized in that the acute angle is 70° to 88°, preferably about 84.5°.

Images