DEVICE AND METHOD FOR PURCHASING A PROCESS GAS CONTAINING AT LEAST ONE HARMFUL GAS

Description

[0001] The present invention relates to a device and a method for purifying a process gas containing at least one pollutant gas.

[0002] Pyrophores and / or toxic gases, which contribute to global warming, are generated in various chemical processes. However, due to their harmful properties, they often require complex treatment and must be rendered as harmless as possible. Several solutions are known from the prior art: DE 20 2005 021 057 U1 discloses a gas pollutant removal system as a burner-scrubber system for reacting gases, in which the required temperature for the (de)reaction of such gases is generated in a combustion chamber. The disadvantages of this system are the high acquisition costs and, due to the energy-intensive treatment, also the high maintenance costs.

[0003] EP 1 070 532 A1 discloses a flow separation system with mixing chambers, which features a complexly designed mixing chamber with internal pipes, inlets, and channels. This makes it complicated and therefore expensive to manufacture, and applicable only to a relatively limited number of applications. EP 1 129 763 A1 discloses another system in which water is introduced into a gas stream or the gas stream is mixed with preheated air. This system also has a complex design, which makes the processes carried out with such a system complicated and requiring expensive control.

[0004] US 2003 / 0054288 A1 discloses a system for exhaust gas treatment in which gas is burned in a combustion device. EP 3 254 745 A1 discloses a vacuum pump with which pollutant gases can be rendered harmless.

[0005] CN 102 049 183 A discloses a device for treating pyrophoric gas with a cyclone. Similarly, EP 1 023 932 A1 also discloses a device for purifying gas using a cyclone.

[0006] The present invention therefore aims to propose a device and a method that avoids the aforementioned disadvantages, and thus enables the efficient neutralization of a harmful gas.

[0007] This problem is solved according to the invention by a device and a method according to the independent claims. Advantageous embodiments and further developments are described in the dependent claims.

[0008] A device for purifying or neutralizing a process gas containing at least one harmful gas (where the process gas itself can also be the harmful gas) comprises a reactor vessel designed as a centrifugal separator, which has a cylindrical or hollow cylindrical section and a tapered section. Oxygen or an oxygen-containing gas can be introduced into the reactor vessel as a reaction gas through at least one gas inlet located on the cylindrical section and discharged from the reactor vessel through at least one gas outlet located on the tapered section. The at least one gas inlet is arranged and configured to introduce a defined volume flow of the reaction gas tangentially to a surface of the cylindrical section into the reactor vessel.A contaminant gas inlet is also arranged on the cylindrical section. This inlet is designed to introduce a defined volume flow of the process gas containing at least one contaminant gas into the reactor vessel, so that the contaminant gas and the reaction gas mix together in the direction of the gas outlet and react chemically with each other as they pass through the reactor vessel. The gas outlet is designed to discharge process gas that has not reacted during the chemical reaction and reaction products from the reactor vessel.

[0009] This device enables a simple reactor design, allowing for a reproducible and verifiable chemical reaction through the controlled introduction of various gases. Its design as a centrifugal separator (also known as a cyclone, cyclone separator, or vortex separator) not only ensures reliable intake of the gases involved in the chemical reaction and their transfer to the gas outlet, but also, due to the gas inlet arrangement, guarantees a flow-optimized design. This typically results in immediate and complete mixing of the gases, rather than mere dilution of the pollutant gas. In simpler terms, the device, the process carried out with it, and its application are optimized, ensuring a controlled and safe reaction.Oxidation enables this process to protect the environment and reduce costs compared to the state of the art. Simultaneously, an improved product is obtained; that is, instead of dilution, the actual reaction of the pollutant gas occurs, resulting in a reduction of pollutant emissions. This makes it possible to select and reuse the reaction products based on their purity.

[0010] To adjust the defined volume flow rate, the device is provided with a flow rate adjustment mechanism, allowing the defined volume flow rate of the process gas containing at least one pollutant gas and the defined volume flow rate of the reaction gas to be adjusted before they are introduced into the reactor vessel. Typically, this volume flow rate is between 300 m³ / hr and 2600 m³ / hr, preferably between 600 m³ / hr and 1300 m³ / hr. Alternatively or additionally, the device can also include a compressor to introduce the process gas and / or the reaction gas into an interior space of the reactor vessel.

[0011] A temperature sensor can be provided at or within the gas outlet to measure the temperature of the typically exothermic chemical reaction in the reactor vessel. The measured temperature can be transmitted to the flow control device to adjust the defined flow rate accordingly, thus enabling control and, if necessary, regulation of the reaction. This temperature sensor is typically located centrally within the gas outlet.

[0012] Alternatively or additionally, a flow velocity sensor can be located in or at the gas inlet and / or in or at the pollutant gas inlet. The measured flow velocity of the respective gas can also be transmitted to the device for adjusting the volume flow and used as a control parameter.

[0013] To carry out oxidation for cleaning, in addition to oxygen, an ambient air mixture can also be used as an oxygen-containing reaction gas, which makes the entire process easier to carry out.

[0014] To support the chemical reaction, a heating device can be arranged in or on the reactor vessel. This heating device is preferably designed as an electric resistance heater and can optionally also be controlled or regulated by the device for adjusting the volume flow.

[0015] The reactor vessel itself is typically made of stainless steel, with standardized pipes and ISO flanges generally used for the gas inlet, gas outlet, and contaminant outlet to keep the design simple and cost-effective. The reactor vessel is typically sealed at the gas inlet, gas outlet, and contaminant outlet, i.e., designed to be gas-tight or fluid-tight, respectively.

[0016] The pollutant gas inlet is located on an end face, i.e., on the circular surface of the cylindrical area, to ensure direct mixing with the tangentially flowing reaction gas.

[0017] The tapering region is typically designed as a conically tapered area. However, the tapering can also be described, in principle, by a polynomial function and the resulting solid of revolution.

[0018] The gas outlet is generally curved in an arc to provide a defined geometry for the efficient discharge of the gas mixture located inside the reactor vessel. Preferably, the gas outlet is curved at a 90° angle.

[0019] The pollutant gas inlet is located opposite the gas outlet. The pollutant gas inlet is designed so that the pollutant gas is introduced into the reactor vessel rotationally symmetrical to a longitudinal axis of the gas outlet, usually to a central axis of the gas outlet.

[0020] A filter element, a scrubber and / or a collection container for reaction products can be detachably attached to the gas outlet, i.e., removable and / or attachable, in order to safely collect and remove the reaction products.

[0021] Silanes and / or diboranes can be treated as pollutant gases in a particularly advantageous manner using the described device.

[0022] A typical residence time of the pollutant gas in the reactor vessel is between 0.3 and 5.0 seconds, preferably between 0.7 and 2.0 seconds. Typical process temperatures can range from 20 °C to 300 °C, preferably between 40 °C and 200 °C.

[0023] In a process for purifying a process gas containing at least one pollutant gas, a defined volume flow of oxygen or an oxygen-containing gas is introduced into a reactor vessel designed as a centrifugal separator, which has a cylindrical section and a tapered section. This flow is introduced tangentially to a surface of the cylindrical section via at least one gas inlet located on the cylindrical section. A defined volume flow of the process gas containing the pollutant gas is introduced into the reactor vessel via a pollutant gas inlet located on the cylindrical section. The pollutant gas and the process gas are mixed together, react chemically with each other as they pass through the reactor vessel, and any unreacted process gas and reaction products are discharged from the reactor vessel through the gas outlet.The pollutant gas inlet is located on an end face of the cylindrical area of ​​the reactor vessel and is positioned opposite the gas outlet and designed to introduce the pollutant gas into the reactor vessel in a rotationally symmetrical manner relative to a longitudinal axis of the gas outlet.

[0024] The described procedure can be carried out with the described device, i.e., the described device is set up to carry out the described procedure.

[0025] Exemplary embodiments of the invention are shown in the drawings and are described below with reference to the Figures 1 to 4 explained. It shows: Fig. 1 a schematic side view of a device for cleaning a process gas containing at least one pollutant; Fig. 2 a opposite Figure 1 View of the device rotated by 90°; Fig. 3 shows a schematic flow path through the device according to the Figure 1 and2 ; and Fig. 4 a schematic flow pattern in perspective view.

[0026] Figure 1 Figure 1 shows a schematic side view of an embodiment of a device for purifying a process gas containing at least one pollutant. Ambient air, as the reaction gas, can flow into the device via one or more intake or inlet ports 1. From the inlet ports 1, the reaction gas flows through angle valves 2, through one or more inlet tubes 3, and past measuring connections through a bend to ambient gas mixture connections 12. The inlet ports 1, the angle valves 2, and the inlet tubes 3, together with the ambient gas mixture connections 12, thus form the gas inlets into the reactor vessel, which has a hollow cylindrical section 5 and a conically tapered section 9. Measuring connections for various measuring instruments can also be arranged on the inlet tubes 3.

[0027] The ambient gas mixture connections 12 are arranged tangentially to the straight, i.e., cylindrical, section 5 of the reactor vessel, which is designed as a cyclone or centrifugal separator. Above the cylindrical section 5 of the reactor vessel, the reactor vessel is sealed gas-tight by a reactor plate 6 or a reactor lid, on which several pollutant gas inlets 8 are arranged. In the Figure 1In the illustrated embodiment, three of these contaminant gas inlets 8 are visible; the fourth contaminant gas inlet 8 is concealed in this view by the centrally located inlet. Behind the centrally located contaminant gas inlet 8, an inspection opening with a cover 7 is visible. This means that the contaminant gas inlets 8 are arranged concentrically around the cover 7 on a flow-optimized circle. Thus, the contaminant gas inlets 8 are rotationally symmetrical about a longitudinal axis or the central axis of the transition from the tapered section 9 to the 90° arc 10. In further embodiments, measuring instruments or scrapers can be inserted into an interior of the reactor vessel through the opening closed by the cover 7, or the opening can be used for maintenance purposes. A conically tapered section 9 of the reactor vessel adjoins the cylindrical section 5 below.Following this cone of the cyclone is the 90° bend 10, which forms a transition to the connection at the exhaust 11 and thus the gas outlet. The ambient gas mixture connections 12 are arranged tangentially to the reactor plate 6 at a distance. After a short, straight pipe, these connections, in the example shown, continue downwards in a 90° bend, perpendicular to the surface, and terminate at the angle valves 2 with spring return, the outlets of which again run parallel to the surface. A straight, obliquely cut circular cylinder is arranged at this outlet, serving as the intake or inlet port 1 and increasing the inflow cross-section. This facilitates the flow of gas into the inlet. Through-threads can be arranged in the vertical pipes to accommodate, for example, measuring instruments such as a pitot tube or other volume or velocity sensors.The size of these threads is usually chosen depending on the system, but they are standardized to be screwed airtight to a blind cover.

[0028] In the Figure 1In the illustrated embodiment, the device is arranged vertically, i.e., the reactor vessel is oriented such that one vertical axis is perpendicular to the ground. The reactor vessel itself has a cylindrical section 5 at its upper end, the end furthest from the ground, which transitions into a frustoconical, tapered section 9 towards the ground. The device terminates at the exhaust 11 in an outer frame structure (not shown for clarity) that supports the device. In the illustrated embodiment, the contaminant gas inlets 8 are arranged vertically on the reactor plate 6, but in other embodiments, they can also open into the reactor plate 6 at different angles or be curved. Typically, the contaminant gas inlets 8 are designed as KF flanges to facilitate easy sealing during transport and to provide a standardized connection.

[0029] Through the in Figure 1 The device shown enables the cost-effective and stable purification and / or reaction of pollutant gases. Chemical compounds such as silane or diborane are inherently highly reactive, but require appropriate support to decompose from the gaseous state into dust or particles that can then be subsequently separated or captured. With the presented device and its optimized flow, which will be explained in more detail below, this process can be controlled and monitored, ultimately leading to purification results that are improved compared to the prior art.

[0030] The device for oxidizing a pollutant gas in a reactor that can be sealed from its environment enables a flow-optimized inflow of the ambient gas mixture, typically air. By allowing the gas to flow in tangentially to the cylindrical surface in the section 5 and utilizing the cyclone principle, a comparatively long residence time in the reactor vessel, and thus a thorough reaction, is achieved without a complex design. For this purpose, the reaction gas flows from the inner wall of the reactor vessel in a vortex of defined volume through a continuous gas stream towards the gas outlet or exhaust 11. The reactor chamber itself tapers conically in the direction of flow towards the exhaust 11. Because the pollutant gas inlet 8 is oriented at the end face such that the vertical axis is...Since the longitudinal axis of the entire device is perpendicular to the surface and thus parallel to the acting gravitational force, the process gas 22 containing the pollutant gas also flows into the reactor vessel in the direction of gravity, is drawn in by the vortex of the cyclone, and consequently flows in a kind of screw or spiral motion towards the gas outlet. It is in constant contact with the surrounding gas mixture and reacts with it without losing heat through the reactor wall in an exothermic reaction or falling below a necessary minimum concentration due to excessive dilution. Ideally, the pollutant gas reacts completely inside the reactor vessel until just before the exhaust 11.This exothermic reaction is ideally controlled by regulating and adjusting the volume flows, which can be done by controlling valves at the gas inlet and the pollutant inlet 8 by a device for adjusting a volume flow (not shown for clarity), for example a computer.

[0031] For this purpose, a temperature sensor 13 can also be arranged centrally in the exhaust stream, which continuously measures the temperature and transmits it as a control parameter to this device for adjusting the volume flow. Additionally, in the Figure 1 In the illustrated embodiment, it is also provided that the flow velocity or volume flow rate in at least one inlet pipe is measured and transmitted to the aforementioned device as a control parameter. This measurement is preferably performed using a Pitot tube or a dynamic pressure probe in the direction of flow.

[0032] The inlet for the ambient gas mixture is located in the Figure 1 In the illustrated embodiment, the device is designed as a standardized pipe; preferably, the reactor vessel or reaction vessel and all connections are made of stainless steel and can be connected to a pipe system via KF flanges (small flange) or ISO flanges (International Organization for Standardization), without being limited to this. In further embodiments, a compressor can also be included in the device to allow the ambient gas mixture or the process gas to flow in in a controlled manner.

[0033] In a further embodiment, the reactor plate 6 has at least two connections, one of which is the pollutant gas inlet 8 and the other for inserting a heating element that initiates a surface reaction of pollutant gases at a reaction temperature above ambient temperature, in particular room temperature (20 °C). This initiates a preset or control of the exothermic reaction at this surface. When sufficiently high temperatures are reached within the reactor vessel, i.e., the centrifugal separator or cyclone, the heating element can be deactivated, and the reaction is monitored via the temperature sensor 13 in the exhaust 11 and / or another temperature detector located inside the reactor vessel. The gas outlet is located opposite the reactor plate 6, which can also be referred to as the reactor lid, at the point in the tapered section 9 where it has its smallest diameter.

[0034] In a corresponding process for the oxidation of pollutant gases such as silane, SiH₄, or diborane, B₂H₆, the reaction gas initially flows into the reactor vessel through the corresponding inlets, creating a cyclone screw motion within the reactor vessel that extends from the inlet to the gas outlet. This cyclone screw motion is accelerated, particularly by the tapered section 9, in the direction of the gas outlet 11. Ambient air is drawn in as the process gas through the gas inlet, for example, by a fan. Preferably, the pollutant gas flows in through the pollutant gas inlet 8, which is positioned, for example, on the inner side of the cyclone screw motion, by being entrained or drawn in by this screw motion.The pollutant gas also performs a screw motion on this inner surface, similar to that of the reaction gas, as a result of which a contact zone is formed in the reactor vessel in which the pollutant gas and the reaction gas 21 react as reaction partners before mixing below the minimum concentration occurs, for example less than 2 percent volume fraction of the gas mixture in the case of silane (whereby a minimum concentration of the pollutant gas is maintained).

[0035] The mixing of the reactants initiates a chain reaction that, along the cyclone's screw motion, leads to the complete reaction of the pollutant gas. After the reaction, the two reactants are replaced by a gas stream containing a substance, preferably a powder-like or dust-like material. This gas mixture is accelerated, particularly after entering the cone. This gas stream can be collected, separated, filtered, or scrubbed. For this purpose, a collection container and / or a suitable filter element or scrubber can be attached to the exhaust 11. For example, reacted products can be filtered as suspended matter or scrubbed by passing them through the scrubber. Preferably, a highly pure substance is filtered and blown into the collection container for reuse and further processing.If the developing cyclone motion is stable, which can be determined, for example, by using a time constant and / or by evaluating measured variables such as differential pressure, volume flow rate, or flow velocity, the process gas is drawn in through the contaminant gas inlet 8. The process gas, including the contaminant gas (e.g., silane as residual charge from gas cylinders), can also be limited by a mass flow controller if necessary. Typically, however, the contaminant gas should have a minimum concentration upon entering the contact zone, which, depending on the specific contaminant gas, corresponds to a critical quantity for a self-sustaining chain reaction. During the reaction, heat is usually released, which in turn supports the reaction and thus promotes complete reaction.This is made possible by the minimum concentration and residence time in the reactor vessel, as well as by the insufficient dilution of the reactants, which are only mixed in the contact zone inside the reactor vessel. After the reaction, the two reactants have become a gas stream consisting of air laden with silicon dioxide, which can be separated by the filter unit if necessary. The filter unit can then blow this charge into an attached collection container, so that a highly pure substance is collected and the filter unit's filter can be reused multiple times, allowing the air to be released into the environment without any pollutants.

[0036] A heating element or heat source can be used to initiate the described (chain) reaction when the reactants are mixed. Once the reaction has stabilized (which may occur, for example, after a predetermined time or by monitoring and evaluating process parameters such as the gas flow temperature), the heating element is switched off. The heating element can be positioned in the contact zone or in the immediate vicinity of the corrosive gas inlet, i.e., close to the corrosive gas inlet 8 (typically no more than one diameter of the respective corrosive gas inlet 8 from its edge), or even within the corrosive gas inlet 8 itself. This additional heating device is typically used to initiate the reaction with diborane, as diborane itself does not react spontaneously with oxygen.Even once the reaction has started, the heating device can be switched off. Although silane and diborane are mentioned as examples, the device and the process can of course also be used for other harmful gases.

[0037] Figure 2 shows a schematic side view, which, however, is now opposite the one in Figure 1The view shown is rotated by 90°, and the device is shown from the rear without supporting structures. Recurring features in this figure, as well as in the following figures, are identified by identical reference numerals. In particular, the temperature sensor 13, located centrally in the exhaust stream, is now more clearly visible. As before, the device comprises a cyclone or centrifugal separator with at least two inlets, each for a reactant, which reacts during the residence time in the reactor to form less harmful or reusable substances, thus no longer endangering the environment. The process can also be shut off from the environment in the event of an accident by means of safety devices and is reproducible, controllable, and monitored. At least one spring-return valve, safety valve, limit switch, or generally a valve that is closed when not actuated can be provided as a safety device.Typically, several of the aforementioned safety devices are used, and different types can also be used in combination.

[0038] Figure 3 shows the flow pattern in a schematic view (in the left part of the figure in a Figure 1 corresponding view, in the right part of the figure in a Figure 2 (corresponding view). The reaction gas 21, for example an ambient gas mixture, enters the reactor vessel via the intake or inlet nozzles 1. An inflow 23 is guided in the inlet tubes 3 to the inlet 24 in the reactor vessel, where a cyclone screw motion 25 develops, which draws in the pollutant gas via the pollutant gas inlets 8. The gas stream flows over the 90° bend 10 as an exhaust stream 26 into the exhaust 11.

[0039] As in Figure 4As shown in a schematic perspective view, the reaction gas 21 enters the reactor vessel tangentially via the ambient gas mixture connections 12. Inside, the cyclone screw motion 25 then develops, flowing helically or in constant rotation downwards until it reaches the outlet, the 90° bend 10 and the exhaust 11, as an exhaust gas stream 26. The cyclone screw motion 25, or cyclone flow, draws in the pollutant gas or process gas 22 via the pollutant gas inlets 8, and the contact zone 27 forms between the two. Figure 4 The denser lines decrease in the direction of the exhaust gas flow, indicating the minimum concentration decrease, i.e., the reaction process.

[0040] Only features of the various embodiments disclosed in the exemplary embodiments can be combined and claimed individually.

Claims

1. A device for purifying a process gas (22) containing at least one pollutant gas, with a reactor vessel which is designed as a centrifugal separator and which has a cylindrical region (5) and a tapering region (9) and into which oxygen or an oxygen-containing gas can be introduced as a reaction gas (21) into at least one gas inlet (1, 2, 3, 12) arranged on the cylindrical region (5) and can be discharged through at least one gas outlet (10, 11) arranged on the tapering region (9), wherein the at least one gas inlet (1, 2, 3, 12) is arranged and formed to introduce a defined volumetric flow of the reaction gas (21) into the reactor vessel tangentially to a circumferential surface of the cylindrical region (5), and a pollutant gas inlet (8) which is arranged on the cylindrical region (5) and is designed to introduce a defined volumetric flow of the process gas (22) containing at least one pollutant gas into the reactor vessel, so that the at least one pollutant gas and the reaction gas (21) are mixed with each other in the direction of the gas outlet (10, 11) and chemically react with each other on their way through the reactor vessel, and the gas outlet (10, 11) is arranged and configured to discharge process gas that has not undergone chemical reaction and reaction products of the chemical reaction from the reactor vessel, wherein the pollutant gas inlet (8) is arranged on an end face (6) of the cylindrical region (5) of the reactor vessel, wherein the pollutant gas inlet is arranged opposite the gas outlet (10, 11) and is configured to introduce the pollutant gas (22) into the reactor vessel in a rotationally symmetrical manner relative to a longitudinal axis of the gas outlet (10, 11) into the reactor vessel, characterised by a device for adjusting the defined volumetric flow, which is configured to adjust the defined volumetric flow of the process gas (22) containing at least one pollutant gas and the defined volumetric flow of the reaction gas (21) before introduction into the reactor vessel.

2. The device according to claim 1, characterised in that a temperature sensor (13) is / are arranged on or in the gas outlet (10, 11) and / or a flow velocity sensor is / are arranged in or on at least the gas inlet (1, 2, 3, 12) or the pollutant gas inlet (8).

3. The device according to any one of the preceding claims, characterised in that a heating device is arranged in or on the reactor vessel for supporting the chemical reaction.

4. The device according to any one of the preceding claims, characterised in that the tapering region (9) of the reactor vessel is formed as a conically tapering region.

5. The device according to one of the preceding claims, characterised in that the gas outlet (10, 11) is curved in an arcuate manner, preferably curved by 90°.

6. The device according to any one of the preceding claims, characterised in that a filter element, a scrubber and / or a collecting container for reaction products is removably attachable to the gas outlet (10, 11).

7. A method for purifying a process gas containing at least one pollutant gas, wherein a defined volumetric flow of oxygen or of an oxygen-containing gas as reaction gas (21) is introduced tangentially to a circumferential surface of the cylindrical region (5) into the reactor vessel via at least one gas inlet (1, 2, 3, 12) arranged on the cylindrical region (5), which reactor vessel is configured as a centrifugal separator and has a cylindrical region (5) and a tapering region (9), and a defined volumetric flow of the process gas (22) containing the pollutant gas is introduced into the reactor vessel via a pollutant gas inlet (8) arranged on the cylindrical region (5), wherein the pollutant gas(22) and the reaction gas (21) are mixed together, react chemically with each other on their way through the reactor vessel, and process gas that has not been converted in the chemical reaction and reaction products of the chemical reaction are discharged from the reactor vessel through the gas outlet (10, 11), wherein the pollutant gas inlet (8) is arranged on an end face (6) of the cylindrical region (5) of the reactor vessel and the pollutant gas inlet (8) is arranged opposite the gas outlet (10, 11) and is configured to introduce the pollutant gas (22) into the reactor vessel in a rotationally symmetrical manner relative to a longitudinal axis of the gas outlet (10, 11).