Device and method for the disposal of harmful gases by combustion

Abstract

The invention relates primarily to a combustion reactor (100) for the combustion of harmful gases or exhaust gases containing hydrogen and ammonia, in particular harmful gases from the semiconductor industry, comprising a burner (8), a reactor cover (1) having multiple preferably cylindrical tubes guided through the reactor cover and comprising a protective tube (2), a ventilation tube (3), an outer combustion tube (4) and an inner combustion tube (5), a feed for oxidant (oxidising agent) (10, 11), a feed for harmful gas (12), wherein the burner (8) is a hydrogen CDA burner with a centered additional CDA injector (13).

Description

[0001] Title: Device and method for the disposal of pollutant gases by combustion

[0002] The present invention relates to a method, a combustion reactor (reactor), and a device for the disposal of pollutants by combustion, in particular pollutants containing H2 and NH3. The device according to the invention can be operated without scrubbing water and results in only low nitrogen oxide emissions.

[0003] Harmful gases within the meaning of the present invention are toxic or otherwise reactive gases, such as H2- and NH3-containing gases, which are produced in particular as exhaust gases during the manufacture of semiconductors, since hydrogen and also ammonia are used as process gases in this process.

[0004] The semiconductors in question are primarily MOCVD I-II-V semiconductors (e.g., GaN and SiC), which are required for the production of LEDs, pLEDs, photovoltaic and photolithography materials, and transistors. The resulting toxic gases are, in the prior art, preferably disposed of by combustion and pyrolysis processes, which generally require large quantities of wash water. The following competing technologies are used, each with its own specific advantages and disadvantages.

[0005] This includes burner-scrubber technology, in which ammonia and hydrogen are combusted with a pilot flame. A large portion of the ammonia ends up in the wash water, and high NOx emissions can be observed at the same time.

[0006] In wet scrubber systems with subsequent dilution, the ammonia is completely transferred into the wash water. This usually requires the addition of acid to regulate the pH value. Furthermore, in these systems, the hydrogen contained in the exhaust gas or process gas must be transported through the device without ignition.

[0007] In catalytic systems, the decomposition temperature of ammonia is lowered, and sufficient heat is generated through electrical heating and the oxidation of hydrogen to decompose the ammonia into nitrogen and hydrogen. Disadvantages of these catalytic systems include high power consumption, the large space requirements of the equipment, and potentially a limited lifespan of the catalysts.

[0008] Examples of such devices and methods can be found, for example, in DE 10 2012 102 248 A1, which relates to the combustion of pollutant gases using a heated pyrolysis tube. Furthermore, CN 10 2644928 B discloses a device for the thermal treatment of exhaust gases in a combustion chamber with a conical cross-section, a double-walled lid, and a baffle plate to increase turbulence.

[0009] EP 1 291 069 describes a combustion device with a central flame area and a surrounding flame area, wherein the pollutant gas is supplied between these areas. Finally, EP 1 877 701 B1 should be mentioned, which relates to a method for burning ammonia, wherein the method includes the optional addition of hydrogen to the exhaust gas to ensure the most complete combustion possible.

[0010] It follows that the devices and methods known in the prior art for the processing of pollutants, in particular pollutants from the semiconductor industry, are in need of improvement in various respects.

[0011] The object of the present invention was therefore to provide a device and a method for treating process exhaust gases or pollutants in general, in particular NH3- and H2-containing exhaust gases from the semiconductor industry, which avoids or largely minimizes the disadvantages known from the prior art. The device and method should have the highest possible pollutant capacity and be able to reduce NOx emissions to less than 100 mg / m3.

[0012] The problem is solved by the device described and claimed below, as well as by a method for treating pollutants, which is characterized in particular by the use of the device according to the invention. The essential element of the device according to the invention is the combustion reactor (reactor) with its specific configuration.

[0013] The device consists of a combustion reactor connected to an exhaust gas cooler. The treated gas is extracted from the exhaust gas cooler, resulting in a lower pressure in the combustion reactor compared to the surrounding environment. A fan can be installed downstream of the exhaust gas cooler to facilitate extraction.

[0014] The process exhaust gas is introduced into the combustion reactor, which has several feed points for oxidants / oxidizing agents. A burner is used to maintain the flame in the combustion reactor; this burner preferably uses hydrogen as the fuel gas and air as the oxidizing agent.

[0015] In principle, other combustion gases, e.g., LNG or PG, and oxygen as an oxidizer are also possible. The reactor's combustion chamber is divided into at least two zones, which one

[0016] Allow combustion of the process exhaust gas first with oxygen deficiency and then combustion with oxygen excess.

[0017] The reactor has a reactor lid and several preferably concentrically arranged cylindrical tubes: an outer protective tube, an air guide tube, and an outer combustion tube. An inner combustion tube may also be provided to further reduce nitrogen oxide emissions.

[0018] The outer and inner combustion tubes are tightly connected to the reactor lid. The inner combustion tube is preferably shorter than the outer combustion tube. The inner combustion tube may be equipped with a baffle plate at its lower end. The baffle plate reduces the outlet cross-section of the inner combustion tube and thus reduces the mixing of gas from the area outside the inner combustion tube. The baffle plate therefore helps to separate the reactor into two areas with different oxygen concentrations. The outer combustion tube widens towards its lower end and is connected at its lower end to the air guide tube and the reactor outlet for treated gas. The outer combustion tube has openings at its lower end through which air can enter the combustion chamber, the openings preferably being wedge-shaped slots with the apex at the upper end.

[0019] The containment tube is tightly connected to the reactor lid and has an inlet opening at its lower end. The air guide tube is positioned at a distance from the reactor lid, allowing air to flow through the gap between the guide tube and the lid into the space between the guide tube and the outer combustion tube. Air is thus drawn upwards from the surrounding environment within the containment tube, deflected at the reactor lid, and then guided downwards through the air guide tube before entering the combustion chamber through the openings of the outer combustion tube. Glow plugs may be installed in or near these openings, which ignite incompletely combusted gas mixtures to induce afterburning.

[0020] The burner is centrally located in the reactor lid at the top of the reactor and opens into the combustion chamber inside the inner combustion tube.

[0021] The burner generates a preferably annular flame. The process exhaust gas is preferably fed through a channel inside the annular flame. Alternatively, several feeds of pollutant gas can be fed separately into the combustion chamber through several channels evenly spaced inside the annular flame. A central air inlet is located at the center of the process exhaust gas feed. This central air inlet preferably terminates in an element for reducing the outflow velocity and for the uniform lateral distribution of low-impulse air, e.g., a porous body or a diffuser.

[0022] Outside the burner, air supply nozzles open into the combustion chamber in the inner combustion tube.

[0023] To monitor the flame, a sensor for flame detection, preferably an optical sensor, can be installed in the reactor lid.

[0024] As an ignition device for igniting the flame, a pilot burner with an integrated ignition electrode can be positioned near the burner and open into the combustion chamber. Alternatively, an ignition electrode can be placed in front of the burner's combustion gas openings, which generates ignition sparks between the ignition electrode and the burner using a high-voltage generator.

[0025] The reactor lid can preferably be double-walled, at least in its central area. This reduces heat transfer from the combustion chamber to the outside. Simultaneously, the cavity in the lid can be used to supply air to the air supply nozzles. The supplied air is preheated and cools the lid. An airflow measurement can be provided in the air gap between the containment tube and the air duct. This area is advantageous for measurement because the air flows largely laminarly there and has not yet been heated. The measurement can be performed as a differential pressure measurement across a cross-sectional constriction in the air gap.

[0026] The entire device, including the reactor, exhaust gas cooler, and any necessary fans and other technically required components, can be housed in a closed enclosure with defined air inlet openings. The air drawn into the reactor is thus extracted from the enclosure. The enclosure can have defined openings for controlled air supply. Since the air volume is monitored, ventilation of the enclosure can be ensured and monitored simultaneously. This prevents the formation of explosive mixtures in the event of leaks in fuel gas-carrying components.

[0027] The exhaust gas cooler can preferably be an air-to-water heat exchanger.

[0028] The heat exchanger can be a shell-and-tube heat exchanger. Preferably, the exhaust gas to be cooled is passed through the tube bundles. A space-saving design provides that the exhaust gas is guided through one half of the tube bundle in one direction and then redirected at the end of the tube bundle and passed through the other half of the tube bundle in the opposite direction. A controllable fan can be provided downstream of the heat exchanger to control the negative pressure in the reactor. Optionally, an air inlet with a controllable cross-section can be provided upstream of the fan. For example, air from outside the system can be mixed into the exhaust gas stream via a pipe on the heat exchanger. Simultaneously, the amount of air drawn into the reactor through the casing can be reduced. Preferably, this air supply can be connected in the area where the exhaust gas is redirected on the heat exchanger.The air supplied through the pipe can be drawn from another area, e.g., from a non-air-conditioned area, to save energy on air conditioning. This additional air supply can also help to lower the temperature of the exhaust air.

[0029] The method according to the invention is described in more detail below using the device according to the invention.

[0030] To dispose of the pollutant gas mixture, hydrogen and oxidant / oxidizing agent are fed into the annular burner, and the burner flame is ignited by the ignition device. The flame is maintained by a continuous supply of hydrogen and oxidant for as long as pollutant gas is being introduced into the combustion chamber. A flame sensor monitors that the flame remains lit for the duration of the pollutant gas disposal process. It also monitors that combustion ceases when the burner is switched off. As soon as pollutant gas is introduced into the combustion chamber, a predetermined quantity of air is simultaneously drawn into the combustion chamber through the air supply nozzles and the central air intake.

[0031] A pre-combustion zone (I) forms in the inner combustion tube, where the oxygen concentration can be precisely controlled. The inner combustion tube, and optionally the baffle plate, prevent the mixing of oxygen-rich gas from the subsequent combustion stages. Less air is supplied to the pre-combustion zone via the air supply nozzles (9) and the central air supply (19) than is required for complete combustion of the exhaust gas.

[0032] This suppresses the formation of nitrogen oxides even when ammonia is added to the pollutant gas.

[0033] The central introduction of air into the pollutant gas stream also causes a reaction to take place inside the pollutant gas stream, which rapidly increases the temperature of the pollutant gas and contributes to the splitting of ammonia into nitrogen and hydrogen.

[0034] When the gas exits the inner combustion tube through the openings of the baffle plate, turbulence occurs, which can stabilize the formation of a flame. A transition zone (II) forms below the inner combustion tube, into which oxygen from the lower reactor area can penetrate, but where oxygen deficiency may still prevail.

[0035] In the area of ​​the preferably wedge-shaped slots (ventilation slots) in the lower part of the outer combustion tube, an afterburning zone (I II) forms. Due to the negative pressure in the reactor, air from the air supply pipe flows through the slots into the afterburning zone.

[0036] The wedge-shaped design of the slots offers an advantage in distributing the air supply, with a small amount at the top and a large amount at the bottom. This ensures that the hot gas from the upper combustion zone is only slowly diluted with air, allowing any unburned components to reignite at the top of the slots. Optionally, glow plugs in the air-mixing area can be used to ensure and stabilize the afterburning process. The widening of the outer combustion tube towards the bottom reduces the flow velocity in this area, thus shortening the flame. The total amount of incoming air is adjusted to ensure that even the highest concentration of pollutants is completely combusted.

[0037] Measuring the amount of air supplied ensures that it is always greater than the amount required for complete combustion of the pollutant gas. The exhaust gas from the reactor is routed through the reactor outlet to the heat exchanger, where it is cooled to a defined temperature. The temperature of the exhaust gas can be further reduced by adding air to the heat exchanger.

[0038] Further objectives, advantages, features, and applications of the present invention will become apparent from the following description of an exemplary embodiment with reference to the drawings. All features described and / or illustrated, individually or in any meaningful combination, constitute the subject matter of the present invention, even independently of their inclusion in the claims or their cross-references. The drawings show preferred variants without limiting the present invention to these variants.

[0039] This shows

[0040] Figure 1 shows a schematic representation of a combustion reactor according to the invention, in which the construction of the burner is not shown in detail;

[0041] Figure 2 shows the upper part of the combustion reactor from Fig. 1 with a preferred embodiment of the burner and other technical components;

[0042] Figure 3 shows a schematic representation of the different combustion zones of the reactor and

[0043] Figure 4 shows an embodiment of a device according to the invention with combustion reactor, heat exchanger, fan and air supply upstream of the fan.

[0044] Fig. 1 shows the combustion reactor 100 with reactor lid 1 and the following concentrically arranged tubes: protective tube 2, ventilation tube 3, outer combustion tube 4, inner combustion tube 5; Furthermore, the dust disc 6, reactor outlet 7, burner 8, air supply nozzles 9, wedge-shaped ventilation slots 17 in the outer combustion tube 4 and an air volume sensor 18 in the protective tube 2. Fig. 2 shows the combustion reactor 100 from Fig. 1 with further features, in particular a preferred arrangement or design of the pipes or supply lines leading to the burner 8: supply for fuel gas or oxidizer 10 and 11, supply for pollutant gas 12, central air supply 13 (CDA: clean dry air, quality standard for compressed air in the semiconductor industry), further supply for air 14, as well as a flame sensor 15, an ignition device 16 and a porous body 19 at the outlet of the central supply for air (13).

[0045] Fig. 3 shows again the combustion reactor 100 in a highly schematic form with the 3 different areas for pre-combustion I, the transition area II and the after-combustion III and also the reactor outlet 7.

[0046] Additional explanations regarding some features:

[0047] The burner 8 according to the invention is preferably a hydrogen CDA burner with a centered additional CDA injection 13 (CDA: Clean Dry Air, a quality standard for compressed air in the semiconductor industry). This results in a higher temperature near the exhaust gas outlet, which promotes the decomposition of the ammonia into hydrogen and nitrogen. The CDA / air is injected uniformly into the flame center through the porous body / sintered body 19. The CDA quantities are varied according to the quantities of exhaust gases. The use of a perforated baffle plate serves to stabilize the flame root. A special feature of the present invention lies in the stabilization and spatial separation of areas with different oxygen concentrations in the combustion reactor. This air staging can also be achieved by controlled CDA injection into different flame and reactor areas.This measure allows for the targeted creation of hot and colder areas for effective pyrolysis and afterburning.

[0048] The triangular slot in the lower section of the outer combustion tube 4 gradually increases the ambient air supply with increasing distance from the combustion head through this uniform enlargement of the opening. The sharp edge of the slots stabilizes the flame through turbulence, and the increased cross-sectional area reduces the flame velocity. This measure ensures the supply of high volumes of ambient air and achieves a high combustion capacity for the overall device.

[0049] In summary, the essential features and properties of the combustion reactor and the (overall) device according to the invention can be described as follows:

[0050] - Combustion reactor with hydrogen CDA burner with centered additional CDA injection to achieve low NOx emissions, - Staged combustion with spatial separation via a perforated baffle plate to achieve low NOx emissions or alternatively with targeted air staging via CDA nozzles,

[0051] - Slotted liner (outer combustion tube) to achieve a high H2 combustion capacity through stabilized intake of ambient air,

[0052] - Effective disposal of ammonia without using wash water for chemical binding and

[0053] - Parallel use of the combustion air CDA as a heat insulator in an annular gap at the reactor head.

[0054] Reference symbol list

[0055] 1 reactor lid

[0056] 2 protective tubes

[0057] 3 ventilation pipes

[0058] 4 outer combustion tube

[0059] 5 inner combustion tube

[0060] 6 baffle plate

[0061] 7 Reactor outlet

[0062] 8 burners

[0063] 9 air supply nozzles

[0064] 10 Supply of fuel gas / oxidizing agent

[0065] 1 1 Supply of fuel gas / oxidizing agent

[0066] 12. Supply of pollutant gas

[0067] 13 central air supply

[0068] 14 additional air supply

[0069] 15 Flame sensor

[0070] 16 Ignition device

[0071] 17 wedge-shaped ventilation slots

[0072] 18 Air flow sensor

[0073] 19 porous bodies

[0074] 20 cavity

[0075] 21 Exhaust gas coolers

[0076] 22 fans, 3 air inlets

[0077] 24 cases

[0078] 25 air inlets

[0079] 26 Exhaust air connection 100 Combustion reactor

[0080] 200 Device

[0081] I Pre-combustion

[0082] II Transitional area

[0083] III Afterburner

Claims

AMENDED CLAIMS received by the International Bureau on 30 March 2026 (30.03.26) Patent claims 1. Combustion reactor (100) for the combustion of pollutant gases or exhaust gases containing hydrogen and ammonia, in particular pollutant gases from the semiconductor industry, comprising a burner (8), a reactor lid (1) with several preferably cylindrical tubes passing through the reactor lid, comprising a protective tube (2), a ventilation tube (3) and an outer combustion tube (4), oxidant supply (10, 11) and pollutant supply (12), wherein the burner (8) is a hydrogen CDA burner with a centered additional CDA injection (13).

2. Combustion reactor (100) according to claim 1, characterized in that the reactor (100) additionally has an inner combustion tube (5) which is shorter than the outer combustion tube (4).

3. Reactor (100) according to claim 2, characterized in that the inner combustion tube (5) has a baffle plate (6) at its end extending into the reactor (100).

4. Reactor (100) according to one of claims 1 to 3, characterized in that the outer combustion tube (4) widens at its lower end projecting into the reactor (100) and AMENDED SHEET (ARTICLE 19) via the lower end with the ventilation pipe (3) and the reactor outlet (7) is connected.

5. Reactor (100) according to one of claims 1 to 4, characterized in that the outer combustion tube (4) has openings (17) at its end through which air can enter the combustion chamber (I, II, III).

6. Reactor (100) according to claim 5, characterized in that the openings (17) of the outer combustion tube (4) are designed as wedge-shaped slots (17) with the tip pointing towards the reactor lid (1 ).

7. Reactor (100) according to one of claims 1 to 6, characterized in that the burner (8) is arranged centrally on the reactor lid (1 ) at the upper end of the reactor (100) and opens into the combustion chamber (I, II, III) of the reactor (100) inside the inner combustion tube (5), which has air supply nozzles (9) in the reactor lid (1 ).

8. Reactor (100) according to one of claims 1 to 7, characterized in that the central air supply (13) of the burner (8) terminates in the combustion chamber (I, II, I II) in an element for reducing the outflow velocity and for the uniform lateral distribution of the air (19), preferably in a porous body (19). AMENDED SHEET (ARTICLE 19) 9. Reactor (100) according to one of claims 1 to 8, characterized in that it has an ignition device (16), an air quantity sensor (18) and a flame sensor (15).

10. Reactor (100) according to one of claims 1 to 9, characterized in that the reactor lid (1 ) has a cavity (20) through which the air is directed to the air supply nozzles (9). 1 1 . Device (200) for the disposal of H2 and NH3-containing exhaust gases comprising a combustion reactor (100) according to one of claims 1 to 10.

12. Device (200) according to claim 1 1 further comprising an exhaust gas cooler (21 ) and a fan (22).

13. Use of a reactor (100) or a device (200) according to any one of claims 1 to 12 for the treatment of H2- and NH3- containing pollutant gases.

14. Method for treating H2- and NH3-containing pollutant gases using a reactor (100) or a device (200) according to any one of claims 1 to 12. AMENDED SHEET (ARTICLE 19)

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