Harmless treatment device and method for SF6 waste gas degradation by atmospheric pressure microwave plasma

Abstract

This invention discloses a harmless treatment device and method for SF6 waste gas degradation using atmospheric pressure microwave plasma. The device includes a plasma generator, a plasma reactor, a tail gas treatment device, and a gas distribution system. The gas distribution system is connected to the plasma generator, mixing SF6 with an auxiliary gas and transmitting the mixture to the plasma generator for ionization to obtain a plasma torch. The plasma torch is then ejected into the plasma reactor in the desired direction. A porous active solid material within the reactor contacts and is heated. The porous active solid material spontaneously reacts with molecules / ions in the plasma torch, generating solid reactants and non-alkaline tail gas, which undergo a secondary reaction to achieve harmless treatment. This invention solves the technical problems of low flow rates and difficulty in suppressing harmful byproducts in related technologies for SF6 degradation, achieving convenient, efficient, reliable, and low-cost degradation treatment of SF6 waste gas.

Description

Technical Field

[0001] This invention relates to the field of power grid equipment exhaust gas treatment technology, and in particular to a harmless treatment device and method for degrading SF6 exhaust gas under normal pressure microwave plasma. Background Technology

[0002] Sulfur hexafluoride (SF6) is widely used in power, medical, and semiconductor industries. The power industry alone uses approximately 8,000 tons of SF6 gas annually, accounting for about 70% of total production. Currently, over 100,000 tons of SF6 are stored in operating gas-insulated equipment, making it one of the most widely used insulating media for electrical equipment. However, SF6 is a potent greenhouse gas, with a greenhouse effect 25,200 times that of carbon dioxide (CO2), and an atmospheric lifetime of up to 3,200 years. To alleviate the environmental pressure caused by SF6 use and emissions and to comply with international emission reduction obligations, environmental protection departments, power companies, SF6 gas producers, and other SF6 users worldwide are continuously researching measures to reduce SF6 emissions into the atmosphere.

[0003] Sulfur hexafluoride (SF6) inevitably generates waste gas during the operation and maintenance of power equipment, posing emission risks. On the one hand, during the operation and maintenance of GIS (Gas-Insulated Switchgear) and high-voltage electrical equipment, the SF6 gas status, such as trace amounts of water and oxygen concentration, needs to be regularly monitored. The small volume of gas per test and the frequent testing result in a large amount of SF6 waste gas. On the other hand, during the purification process at provincial SF6 gas recovery and treatment centers or mobile treatment equipment, approximately 2% of the SF6 waste gas cannot be purified. The cost of recovering this large amount of scattered SF6 waste gas is enormous, and closed-loop disposal is difficult.

[0004] For the degradation treatment of sulfur hexafluoride (SF6) waste gas from high-voltage power equipment, traditional technologies such as pyrolysis and catalysis require high temperatures above 1100℃ or precious metal catalysts, resulting in high energy consumption (>100 kWh / m³). 3 SF6, large equipment (>1.5 tons), and a degradation rate of only 60-80%, with an overly harsh operating environment, make it difficult to meet the needs of SF6 waste gas treatment for widely distributed high-voltage gas insulation equipment.

[0005] The dielectric barrier discharge (DBD) technology, proposed in recent years, uses plasma discharge to treat sulfur hexafluoride (SF6) waste gas. It boasts advantages such as simple structure, flexible processing, and high energy utilization, improving the treatment capacity of SF6 waste gas. However, DBD utilizes dielectric barrier discharge, which is susceptible to corrosion. The single-reaction tube has a low processing flow rate; at a discharge power of 1 kW, the processing flow rate for 2% SF6 waste gas is only 150 mL / min, equivalent to a SF6 treatment capacity of 0.18 L / h. Furthermore, the degradation rate decreases significantly with increasing SF6 concentration, making it difficult to meet the degradation requirements of large quantities of SF6. Moreover, it generates numerous harmful byproducts, and conventional alkaline washing methods are very slow, failing to match the SF6 degradation rate. The low processing flow rate and difficulty in suppressing harmful byproducts result in low SF6 degradation treatment efficiency. Summary of the Invention

[0006] Based on this, the present invention provides an apparatus and method for harmless treatment of SF6 waste gas using atmospheric pressure microwave plasma, so as to at least solve the problems of low treatment flow rate and difficulty in suppressing harmful by-products in the related technologies for SF6 degradation.

[0007] According to one aspect of the present invention, a harmless treatment device for degrading SF6 waste gas under normal pressure microwave plasma is provided, comprising: a plasma generator, a plasma reactor, a tail gas treatment device, and a gas distribution system.

[0008] The gas distribution system is used to mix SF6 with an auxiliary gas. The plasma generator, connected to the gas distribution system, ionizes the mixture of SF6 and the auxiliary gas to obtain a plasma torch, which is then ejected into the plasma reactor in the ejection direction. The plasma reactor contains a porous active solid material, which contacts and is heated by the plasma torch to generate solid reactants and non-alkaline tail gas. The non-alkaline tail gas undergoes a secondary reaction in a tail gas treatment device to achieve harmless treatment. The porous active solid material and the plasma torch form a chemical reaction system, and the free energy change of the chemical reaction system before and after the reaction is described. satisfy: In the formula, ΔH is the enthalpy change of the chemical reaction system, ΔS is the entropy change of the chemical reaction system, and T is the absolute temperature of the chemical reaction system, and 0 <T<4000K。

[0009] As an alternative, the plasma generator includes a nozzle and a waveguide device; the nozzle is connected to the gas distribution system and is used to eject the mixed gas into the effective range of the waveguide device, which is used to ionize and heat the mixed gas to obtain a plasma torch; wherein the ejection direction of the nozzle is toward the location where the porous active solid material is placed.

[0010] As an alternative, the nozzle is disposed at the inlet of the plasma reactor; the waveguide device is disposed on the plasma reactor near the inlet, such that the edge of the effective area of ​​the waveguide device corresponds to the position of the nozzle, and the waveguide device is used to ionize the mixed gas ejected from the nozzle within the plasma reactor.

[0011] As an alternative, the waveguide device is a rectangular waveguide.

[0012] As an alternative, the nozzle is a multi-gas-channel nozzle, in which multiple gas channels independently eject the mixed gas.

[0013] As an alternative, the nozzle includes a nozzle base, a gradient portion, and a tip portion; the nozzle base is fixed to the inlet of the plasma reactor, the gradient portion is connected to the nozzle base, the size of the gradient portion gradually decreases along the ejection direction, the tip portion is connected to the smaller end of the gradient portion, and the size of the tip portion remains constant along the ejection direction.

[0014] As an alternative, the tip is provided with a gas channel; the gradient portion is provided with multiple gas channels, which are evenly distributed on the gradient portion around the gas channel of the tip.

[0015] As an alternative, the plurality of gas channels include a first gas channel for transmitting SF6, a second gas channel for transmitting auxiliary gas, and a third gas channel for transmitting pressurized gas.

[0016] As an alternative, the plasma reactor is further provided with a discharge tube, which is mounted on the waveguide device; one end of the discharge tube is configured as the input port, and the other end of the discharge tube is connected to the reaction section, which is used to place the porous active solid material.

[0017] As an alternative, the discharge tube is a cylindrical tube, the interior of which is used to house the plasma torch; the length of the cylindrical tube is not less than half the length of the plasma torch, the length of which is the dimension of the flame beam of the plasma torch along the ejection direction.

[0018] As an alternative, the discharge tube is a double-layered cylindrical tube, which includes an outer tube and an inner tube. The waveguide device is disposed on the outer tube, and the nozzle is disposed at one end of the inner tube to house the plasma torch in the inner tube.

[0019] As an alternative, the double-layered columnar tube has a dimension of 160mm-220mm in the ejection direction; the inner tube has a dimension of 40mm-50mm in the radial direction.

[0020] As an alternative, in the radial direction of the outer tube, the size of the reaction section is larger than the size of the outer tube, and the reaction section is connected to the outer tube.

[0021] As an alternative, the reaction section is spherical with a diameter of 350mm-450mm, and the outer tube has a radial dimension of 60mm-80mm.

[0022] As an alternative, the reaction section has an outlet located away from the nozzle in the ejection direction; the reaction section also has a mesh fixing device at the outlet for permeable placement of the porous active solid material in the reaction section.

[0023] As an alternative, the mesh fixing device is a porous plate, which is fixed on the reaction section; the nozzle direction is from top to bottom, the nozzle is located above the reaction section, the porous active solid material is located on the porous plate, and the output port is located below the porous plate.

[0024] As an alternative, the porous active solid material is a spherical solid material; the diameter of the spherical solid material is 3-5 mm.

[0025] As an alternative, the spherical solid material is a mesoporous material, which has a hierarchical pore structure containing micron-sized and nano-sized pores, with a porosity of 30-70%, and mesopores are present in the hierarchical pore structure, with a diameter of 1 nm-20 nm.

[0026] As an alternative, the plasma torch includes HF, SO2, and SOF ion / molecular products, and the main component of the porous active solid material is a metal oxide; the metal oxide includes at least one of the following: iron oxide, Al2O3, MgO, and CaO.

[0027] As an alternative, the metal oxide is CaO and / or MgO.

[0028] As an alternative, the gas distribution system includes an SF6 gas source, an auxiliary gas source, and an air compressor; a first gas path of the auxiliary gas source is connected to the air compressor through a first pressurized gas path, and the first gas path is also merged with a second gas path of the SF6 gas source to form an output gas path; the output gas path is further connected to the air compressor through a second pressurized gas path; the output gas path is connected to a nozzle of the plasma generator.

[0029] As an alternative, the auxiliary gas is water vapor, and the auxiliary gas source is a water vapor generator.

[0030] As an alternative, the gas distribution system further includes a controller; solenoid valves and flow meters are provided in the second gas path, the first pressurized gas path, and the second pressurized gas path; the solenoid valves, the flow meters, and the water vapor generator are all connected to the controller.

[0031] As an alternative, the tail gas treatment device is an alkali washing device; an input port of the alkali washing device is connected to an output port of the plasma reactor, and an output port of the alkali washing device is open to the atmosphere.

[0032] According to another aspect of the present invention, there is also provided a method for harmless treatment of SF6 waste gas degraded by atmospheric pressure microwave plasma, including: mixing SF6 and an auxiliary gas through a gas distribution system and inputting them into a plasma generator; mixing the SF6 and the auxiliary gas by the plasma generator, spraying them in a predetermined spraying direction, and ionizing them to form a plasma torch; adsorbing the plasma torch by a porous active solid material arranged in the spraying direction of the plasma torch and performing a chemical reaction to generate solid reactants and non-alkaline tail gas, wherein the porous active solid material and the plasma torch form a chemical reaction system, and the free energy change of the chemical reaction system before and after the reaction satisfies: , where ΔH is the enthalpy change of the chemical reaction system, ΔS is the entropy change of the chemical reaction system, T is the absolute temperature of the chemical reaction system, and 0 < T < 4000K; transmitting the non-alkaline tail gas to a tail gas treatment device, and performing a secondary reaction through an alkaline solution in the tail gas treatment device to achieve harmless treatment.

[0033] As an alternative, mixing SF6 and an auxiliary gas through a gas distribution system and inputting them into a plasma generator includes: transmitting SF6 and water vapor through independent gas paths to a first gas channel and a second gas channel of a multi-gas channel nozzle of the plasma generator; pressurizing through an air compressor so that the multi-gas channel nozzle mixes while spraying SF6 and water vapor.

[0034] As an alternative, pressurization is performed using an air compressor, including: pressurizing the water vapor by introducing air at a preset pressure into the first air passage through the first pressurization air passage of the air compressor, wherein the first pressurization air passage is connected to the first air passage and the first air passage is connected to the second gas channel; or, inputting the air into the third gas channel of the multi-gas channel nozzle through the second pressurization air passage of the air compressor, thereby drawing out SF6 and water vapor under negative pressure while spraying them out.

[0035] As an alternative, a plasma generator will eject the mixed gas in a predetermined ejection direction and ionize it to form a plasma torch, including: ionizing the ejected mixed gas through a waveguide device to form a plasma torch; and beaming the plasma torch through a discharge tube of a double-layered cylindrical tube.

[0036] As an alternative, after beaming the plasma torch through the discharge tube of the double-layered cylindrical tube, the method further includes: if the end of the plasma torch does not touch the porous active solid material, increasing the output pressure of the air compressor and raising the microwave power of the microwave source of the waveguide device to lengthen the plasma torch so that it can touch the porous active solid material; or, if the diameter of the plasma torch touching the porous active solid material exceeds a preset parameter, reducing the output pressure of the air compressor and lowering the microwave power of the microwave source to shorten the plasma torch.

[0037] As an alternative, a porous active solid material disposed in the ejection direction of the plasma torch is used to adsorb and chemically react with the plasma torch, generating solid reactants and non-alkaline tail gas. This includes: adsorbing and reacting SOF ion / molecular products of the plasma torch through a porous active solid material whose main component is metal oxide to generate solid inorganic salts and corresponding tail gas, the tail gas including O2 and H2O; unreacted SOF ion / molecular products are decomposed into SO2, SO3, and HF at high temperature; the SO2, SO3, and HF are mixed with the tail gas to form the non-alkaline tail gas.

[0038] As an alternative, after the unreacted SOF ion / molecular products are decomposed into SO2, SO3, and HF at high temperature, the method further includes: adsorbing and reacting the SO2, SO3, and HF through a porous active solid material whose main component is metal oxide to generate solid inorganic salt and H2O; and mixing the unreacted SO2, SO3, and HF with the tail gas and H2O to form the non-alkaline tail gas.

[0039] As an alternative, the non-alkaline exhaust gas is transferred to an exhaust gas treatment device, where it undergoes a secondary reaction in an alkaline solution to achieve harmless treatment. This includes: reacting acidic gases in the non-alkaline exhaust gas with the alkaline solution in an alkaline washing device to generate water and inorganic salts, wherein the acidic gases include SO2, SO3, and HF; and dissolving neutral gases in the non-alkaline exhaust gas, wherein the neutral gases include O2 and H2O.

[0040] As an alternative, after reacting the acidic gas in the non-alkaline tail gas with the alkaline solution of the alkaline washing device to generate water and inorganic salts, the method further includes: extracting the solid inorganic salts on the porous active solid material and the inorganic salts in the alkaline solution; and manufacturing industrial concrete using the extracted solid inorganic salts and the inorganic salts.

[0041] The present invention has the following technical effects:

[0042] 1. SF6 and auxiliary gas are mixed through a gas distribution system. The plasma generator ionizes the mixture of SF6 and auxiliary gas to obtain a plasma torch, which is then ejected into the plasma reactor in the ejection direction. Inside the plasma reactor, a porous active solid material comes into contact with the plasma torch and is heated, spontaneously reacting with molecules / ions in the plasma torch to generate solid reactants and non-alkaline tail gas. The non-alkaline tail gas undergoes secondary reaction treatment by a tail gas treatment device to achieve harmless treatment. This solves the problem of difficult suppression of harmful byproducts.

[0043] 2. This invention first solidifies the particles related to harmful byproduct gases in the plasma torch and then treats them harmlessly using a tail gas treatment device. Compared to existing technologies that only use alkaline washing devices, this significantly improves the treatment efficiency and suppression effect of harmful byproducts, thereby enabling higher flow rates for ion treatment. Compared to the existing SF6 treatment flow rate of 0.18 L / h, this invention substantially increases the treatment flow rate, solving the problem of low treatment flow rates for SF6 degradation in existing technologies.

[0044] 3. The present invention uses atmospheric pressure microwave plasma technology to achieve convenient, efficient, reliable and low-cost degradation treatment of SF6 waste gas. Its treatment device has a simple structure and small overall size. The size of the equipment is in the decimeter range. Compared with the existing DBD treatment equipment, which is at least several meters in size, it has obvious portability, higher flexibility of use and is more suitable for the treatment needs of sulfur hexafluoride SF6 waste gas in widely distributed high-voltage gas insulation equipment. Attached Figure Description

[0045] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention, and those skilled in the art can obtain other embodiments based on these drawings without creative effort.

[0046] Figure 1 This is a schematic diagram of a harmless treatment device for degrading SF6 waste gas under normal pressure using microwave plasma, according to an embodiment of the present invention.

[0047] Figure 2 This is a schematic diagram of the structure of a nozzle according to an embodiment of the present invention.

[0048] Figure 3 This is a schematic diagram of the structure of a plasma reactor according to an embodiment of the present invention.

[0049] Figure 4 This is a flowchart of a method for harmlessly treating SF6 waste gas by degrading it using atmospheric pressure microwave plasma, according to an embodiment of the present invention.

[0050] Figure 5 This is a schematic diagram of microwave plasma degradation of a mixed gas according to an embodiment of the present invention.

[0051] Figure 6 This is a schematic diagram of the reaction between a plasma torch and a porous active solid material according to an embodiment of the present invention.

[0052] Figure 7 This is a schematic diagram of the high-temperature decomposition and re-reaction of the plasma torch according to an embodiment of the present invention.

[0053] Figure 8 This is a schematic diagram illustrating the harmless treatment of non-alkaline exhaust gas according to an embodiment of the present invention.

[0054] Figure 9 This is a schematic diagram showing the component detection results in the final emitted gas of an embodiment of the present invention.

[0055] In the diagram: 1. Gas distribution system; 101. SF6 gas bag; 102. Air compressor; 103. Steam generator; 104. First flow meter; 105. Second flow meter; 106. Third flow meter; 2. Atmospheric pressure microwave plasma treatment system; 21. Plasma generator; 22. Plasma reactor; 201. Rectangular waveguide; 202. Porous active solid material; 203. Porous partition; 204. Nozzle base; 205. SF6 gas channel; 206. Gradient section; 207. Tip section; 208. Auxiliary gas channel; 209. Inner tube; 210. Outer tube; 3. Exhaust gas treatment device. Detailed Implementation

[0056] Embodiments of the present invention will now be described in more detail with reference to the accompanying drawings. While some embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the present invention. It should be understood that the drawings and embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0057] Atmospheric pressure microwave plasma technology employs electrodeless discharge and high energy density. The electron temperature of the plasma (average 5-15 eV) is higher than that of DBD (average 2-5 eV), resulting in stronger bombardment capability and higher plasma ionization, which better promotes the effective degradation of sulfur hexafluoride (SF6) and its intermediate products. Furthermore, microwave plasma is a high-enthalpy plasma with a higher particle temperature than DBD, thus exhibiting high reactivity. This provides a new method for the degradation treatment of SF6 waste gas that is highly energy-efficient (greater than 0.8 L / kWh) and has a high degradation efficiency (degradation rate greater than 0.8 L / h at 1 kW power). This embodiment provides a harmless treatment device and method for the degradation of SF6 waste gas using atmospheric pressure microwave plasma, aiming to solve the problems of low flow rate and difficulty in suppressing harmful byproducts in SF6 degradation treatment, and to achieve convenient, efficient, reliable, and low-cost degradation treatment of SF6 waste gas.

[0058] Example 1

[0059] According to one aspect of the present invention, a harmless treatment device for the degradation of sulfur hexafluoride (SF6) waste gas by atmospheric pressure microwave plasma is provided, such as... Figure 1 As shown, the device includes: a plasma generator 21, a plasma reactor 22, a tail gas treatment device 3, and a gas distribution system 1. The plasma generator 21 and the plasma reactor 22 can be collectively referred to as the atmospheric pressure microwave plasma treatment system 2.

[0060] Gas distribution system 1 is connected to plasma generator 21. Gas distribution system 1 is configured to distribute sulfur hexafluoride (SF6) with an auxiliary gas. Plasma generator 21 is connected to gas distribution system 1 and is configured to ionize the mixture of SF6 and auxiliary gas to obtain a plasma torch, which is then ejected into plasma reactor 22 in the ejection direction. Simultaneously with the plasma reaction, the porous active solid material 202 is heated by the plasma torch to increase the reaction rate between the porous active solid material 202 and the molecules or ions in the plasma torch.

[0061] The plasma reactor 22 is provided with a porous active solid material 202. The porous active solid material 202 contacts with the plasma torch and is heated. The porous active solid material and the plasma torch form a chemical reaction system. And the change in free energy of the chemical reaction system before and after the reaction satisfies: , where ΔH is the enthalpy change of the chemical reaction system, ΔS is the entropy change of the chemical reaction system, T is the absolute temperature of the chemical reaction system, and 0 < T < 4000K. That is, within the absolute temperature range of 0 - 4000K, the molecules or examples of the porous active solid material 202 and the plasma torch can undergo a spontaneous reaction without a catalyst.

[0062] The plasma torch after the ionization of sulfur hexafluoride SF6 and the auxiliary gas reacts with the porous active solid material to generate solid reactants and non - alkaline tail gas. The non - alkaline tail gas is subjected to a secondary reaction by the tail gas treatment device 3 to achieve harmless treatment.

[0063] Specifically, after the sulfur hexafluoride SF6 gas and the auxiliary gas are ionized, reactions occur in the plasma torch to generate sulfur dioxide SO2 and molecules or ions of S - O - F sulfur - oxygen - fluorine. For example, neutral molecules containing sulfur oxides and fluorides, including: sulfuryl difluoride SOF2, sulfur tetrafluoride oxide SOF4, sulfuryl fluoride SO2F2, sulfur dioxide SO2, oxygen difluoride OF2, etc. Some ions, including: SOF3 + sulfur trioxide fluoride ion, SOF + sulfur fluoride oxide ion, SF3 + sulfur trifluoride ion, SF5 + sulfur pentafluoride ion, F - fluoride ion, SF7 - sulfur heptafluoride anion. And some free radicals and reactive intermediates.

[0064] These products can be adsorbed by the porous active solid material 202 and further decomposed to generate active ions, mainly some free radicals and reactive intermediates. They can form a chemical reaction system with the porous active solid material 202 and further undergo a chemical reaction to generate solid compounds of fluorine F and sulfur S, thereby solidifying the ions forming harmful by - products on the porous active solid material 202, reducing the formation of harmful by - product gases. This can not only greatly increase the efficiency of by - product treatment, but in combination with the tail gas treatment device 3, can achieve better harmless treatment.

[0065] It should be noted that the main component of the material of the above - mentioned porous active solid material 202 needs to form a chemical reaction system with the molecules / ions in the plasma torch, and its change in free energy satisfies: In the formula, ΔH is the enthalpy change of the chemical reaction system, ΔS is the entropy change of the chemical reaction system, and T is the absolute temperature of the chemical reaction system, and 0 <T<4000K。

[0066] In other words, the main components of the porous active solid material 202 can spontaneously react with the molecules / ions in the plasma torch to form a chemical reaction system, with the reaction occurring at temperatures ranging from 0 to 4000 K. Furthermore, the products tend to exist in a solid state. Combined with the properties of porous materials, this allows for the rapid and efficient solidification of ions that would otherwise form harmful byproducts when adsorbing molecules / ions from the plasma torch. This not only improves processing efficiency but also increases the processing flow rate.

[0067] Furthermore, it avoids the ions of harmful byproducts from undergoing secondary reactions to generate harmful gaseous byproducts when forming gaseous products. This further improves the treatment efficiency of sulfur hexafluoride (SF6).

[0068] The exhaust gas treatment device 3 is connected to the output port of the plasma reactor, and an alkaline solution is provided inside the exhaust gas treatment device 3. Since the harmful by-product gases are generally acidic gases of fluorine oxides and sulfur oxides, the alkaline solution can fully react the small amount of gas that has not reacted with the porous active solid material 202, thereby achieving harmless treatment.

[0069] As an alternative, the plasma generator includes a nozzle and a waveguide device; the nozzle is connected to a gas distribution system and is configured to eject a mixed gas into the effective range of the waveguide device, which is configured to ionize and heat the mixed gas to obtain a plasma torch; the ejection direction of the nozzle is toward the location where the porous active solid material is placed.

[0070] The plasma generator 21 is mainly used for microwave plasma conversion of sulfur hexafluoride (SF6) and auxiliary gas to generate a plasma torch. There are many ways to excite plasma, such as direct current discharge, radio frequency plasma, microwave plasma, and pulsed discharge plasma. To ensure the decomposition efficiency of SF6, this embodiment uses microwave plasma for decomposition, which can completely decompose SF6.

[0071] The aforementioned waveguide device is used to transmit microwaves to the nozzle location to perform plasma conversion on the ejected sulfur hexafluoride (SF6) and auxiliary gas mixture. That is, the nozzle needs to be connected to the gas distribution system and configured to eject the mixed gas into the effective range of the waveguide device. While ejecting the mixed gas, the nozzle is simultaneously plasma-generated by the microwaves from the waveguide device, forming a plasma torch, such as... Figures 1 to 3 As shown.

[0072] The nozzle's ejection direction is directed towards the location of the porous active solid material, allowing the plasma torch to simultaneously spray plasma particles onto the porous active solid material 202 within the plasma reactor 22 during the plasma reaction, thereby improving adsorption and reaction efficiency. Furthermore, heating the porous active solid material 202 by the plasma torch raises the reaction temperature between the plasma torch's molecules / ions and the porous active solid material 202, further increasing the reaction rate.

[0073] As an alternative, the nozzle is positioned at the inlet of the plasma reactor; the waveguide is positioned on the plasma reactor near the inlet so that the edge of the waveguide's active area corresponds to the position of the nozzle, and the waveguide is configured to ionize the mixed gas ejected from the nozzle within the plasma reactor.

[0074] The plasma reactor 21 described above can utilize a hardware structure to position the nozzle and waveguide device, ensuring the nozzle is within the effective range of the waveguide device and thus guaranteeing effective ionization of the mixed gas. In this embodiment, a glass tube can be used as the aforementioned hardware structure. The glass tube not only allows for effective observation of the internal reaction but also concentrates the mixed gas ejected from the nozzle, making the plasma torch more focused and achieving higher ionization efficiency.

[0075] The nozzle is positioned at the inlet of the glass tube, and the waveguide device is mounted on the glass tube near the inlet, effectively placing the nozzle within the effective area of ​​the waveguide device. Preferably, in this embodiment, the edge of the effective area of ​​the waveguide device corresponds to the position of the nozzle, that is, the nozzle is positioned at the edge of the effective area of ​​the waveguide device. This allows the gas ejected from the nozzle to pass through a wider microwave range, thereby improving ionization efficiency and degree, and ensuring complete ionization of the gas mixture.

[0076] As an alternative, the waveguide device is a rectangular waveguide.

[0077] like Figure 1 As shown, a rectangular waveguide is essentially a hollow metal tube with a rectangular cross-section. It achieves low-loss transmission through the reflection of electromagnetic waves within the cavity. It boasts advantages such as low transmission loss, high power capacity, and good shielding. Its high-power microwave transmission capability offers even better performance in plasma ionization scenarios.

[0078] The rectangular waveguide is installed at the inlet of the glass tube, and the entire interior of its hollow metal tube is within the effective range. The nozzle is set flush with the upper wall of the rectangular waveguide, so that the mixed gas ejected from the nozzle has a longer ionization range within the effective range, thereby improving the degree of ionization and efficiency.

[0079] As an alternative, the nozzle is a multi-gas-channel nozzle, with multiple gas channels independently ejecting the mixed gas.

[0080] The nozzle is connected to the gas distribution system 1, which allows for the mixing and pressurization of sulfur hexafluoride (SF6) and auxiliary gas in a specific ratio. Alternatively, a fixed ratio of SF6 and auxiliary gas can be pressurized in the gas distribution system 1 and transmitted to the nozzle for mixing during ejection. The first method involves a more complex gas distribution system, and incomplete mixing may occur during the gas mixing process, affecting the ionization effect.

[0081] Therefore, in this embodiment, sulfur hexafluoride (SF6) and an auxiliary gas are pressurized and mixed simultaneously during the injection through a nozzle. The pressurized gas has higher energy, allowing for more uniform mixing during injection, thereby improving the ionization effect.

[0082] Configure the nozzle as a multi-gas-channel nozzle, with multiple independent gas channels ejecting a single sulfur hexafluoride (SF6) or auxiliary gas. For example... Figure 2 As shown, there are three gas channels. The middle gas channel is the sulfur hexafluoride (SF6) gas channel 205, which sprays out sulfur hexafluoride (SF6). The other two gas channels are auxiliary gas channels 208, which spray out auxiliary gas.

[0083] As an alternative, such as Figure 2 As shown, the nozzle includes a nozzle base 204, a gradient portion 206, and a tip portion 207. The nozzle base 204 is fixed to the inlet of the plasma reactor 21. The gradient portion 206 is connected to the nozzle base 204. The size of the gradient portion 206 gradually decreases along the ejection direction. The tip portion 207 is connected to the smaller end of the gradient portion 206. The size of the tip portion 207 remains fixed along the ejection direction.

[0084] The nozzle base 204 is fixed to the inlet of the plasma reactor 21. This ensures that after the mixed gas is ejected, there is sufficient space and distance within the plasma reactor 21 for ionization, thereby improving the ionization effect of the mixed gas.

[0085] The gradient section 206 gradually decreases in size along the ejection direction, forming a cone shape, which allows the mixed gas to have a better aggregation effect during ejection. Preferably, the rate at which the size of the gradient section 206 decreases along the ejection direction gradually increases, and a concave curved surface structure is formed on the surface of the gradient section 206. This allows the gas channels located at different locations to mix the gas more evenly after ejection.

[0086] The tip 207 is connected to the smaller end of the gradient section 206. The size of the tip 207 is fixed along the ejection direction, which can further guide the ejection direction of the mixed gas, so that the plasma torch can be targeted to the porous active solid material 202 for adsorption and reaction.

[0087] As an alternative, the tip 207 is provided with a gas channel; the gradient part 206 is provided with multiple gas channels, which are evenly distributed on the gradient part 206 around the gas channel of the tip 207.

[0088] The gas channel provided on the tip 207 can guide the ejection direction. The multiple gas channels on the gradient section 206 surrounding the tip 207 can mix better with each other while being ejected, and can also mix better with the gas channels on the tip 207 while being ejected in the ejection direction.

[0089] As an alternative, the multiple gas channels include a first gas channel for transmitting sulfur hexafluoride (SF6), a second gas channel for transmitting auxiliary gas, and a third gas channel for transmitting pressurized gas.

[0090] Since the nozzle needs to eject gas, pressurization can be applied to the gas distribution system 1 to improve mixing and ejection distance. During pressurization, one or a portion of the gas can be pressurized; upon ejection, the higher air velocity reduces the external air pressure of the nozzle, drawing other gases out of the gas channel and mixing them. Alternatively, all gases can be pressurized, resulting in better mixing; however, gas pressurization requires pressurization equipment, increasing system complexity and leading to a larger overall device size.

[0091] To facilitate portability and considering the relatively small amount of sulfur hexafluoride (SF6) in gas bag applications, this embodiment only pressurizes the auxiliary gas, using an air compressor. This results in air being mixed into the gas distribution system. As an alternative embodiment, the air compressor can directly input the pressurized air into the nozzle, eliminating the need for auxiliary gas pressurization and further simplifying the gas path.

[0092] In this case, multiple gas channels include a first gas channel for transmitting sulfur hexafluoride (SF6), a second gas channel for transmitting auxiliary gas, and a third gas channel for transmitting pressurized gas. The first gas channel can be located on the tip 207, and the second and third gas channels can be located on the transition section 206.

[0093] As an alternative, the plasma reactor is also equipped with a discharge tube, which is mounted on a waveguide device; one end of the discharge tube is set as an input port, and the other end of the discharge tube is connected to the reaction section, which is configured to hold porous active solid materials.

[0094] As described above, the plasma reactor 21 mainly includes a nozzle and a waveguide device. However, although the mixed gas ejected from the nozzle has a certain direction, gas leakage still occurs when the space is open, affecting the ionization effect. The glass tube is set as a discharge tube and installed on the waveguide device. The waveguide device has a hole to accommodate the discharge tube. The shape of the discharge tube matches the shape of the hole to avoid gaps that could cause microwaves to be reflected outside the waveguide device.

[0095] One end of the discharge tube is also the inlet of the plasma reactor 21. To prevent harmful byproduct gases from escaping from the plasma torch, the discharge tube is connected to the reaction section to form a closed reaction space. For example, as... Figure 1 and Figure 3 As shown, the reaction section is spherical and connected to the discharge tube set in the rectangular waveguide above, forming a closed plasma generation space and reaction space.

[0096] The reaction section is equipped with a porous active solid material 202 and an outlet. The gas after the reaction can be transmitted to the exhaust gas treatment device 3 through the outlet for final harmless treatment.

[0097] As an alternative, the discharge tube is a cylindrical tube, and the interior of the discharge tube is used to house the plasma torch; the length of the cylindrical tube is not less than half the length of the plasma torch, and the length of the plasma torch is the dimension of the plasma torch's flame beam along the ejection direction.

[0098] like Figure 1 and Figure 3 As shown, the discharge tube is a cylindrical tube, preferably a columnar tube. The cylindrical tube can form a longer converging space along the ejection direction, which allows the mixed gas to be fully mixed and ionized inside, further improving the ionization effect of the mixed gas.

[0099] In order to effectively beam the plasma torch and increase the degree of reaction so as to effectively reach the porous active solid material 202, the length of the column tube is set to at least half the length of the plasma torch.

[0100] As an alternative, the discharge tube is a double-layered cylindrical tube, which includes an outer tube 210 and an inner tube 209. A waveguide device is disposed on the outer tube 210, and a nozzle is disposed at one end of the inner tube 209 to accommodate the plasma torch in the inner tube 209.

[0101] Because there is a significant size difference between the single-layer discharge tube and the nozzle, gas backflow can easily occur near the nozzle, affecting the ionization effect of the mixed gas. To address this, the discharge tube can be a double-layer cylindrical tube, consisting of an outer tube 210 and an inner tube 209. The waveguide device is mounted on the outer tube 210 to meet the installation requirements. The nozzle is located at one end of the inner tube 209, housing the plasma torch within it. The size of the inner tube 209 is closer to that of the nozzle, eliminating gas backflow and allowing the gas ejected from the nozzle to continue mixing and ionizing, thus improving the ionization effect. Simultaneously, it also provides a better jetting effect for the plasma torch.

[0102] It should be noted that similar multi-layered tubes, such as three-layered tubes, four-layered tubes, etc., can also achieve the same technical effect. The channel between the inner tube 209 and the outer tube 210 can prevent the backflow of particles from the plasma torch.

[0103] The inner tube 209 of the double-layer discharge tube confines the plasma to enhance the concentration of microwave energy, while the outer tube 210 isolates the high temperature from the waveguide. This maintains the high enthalpy stability of the plasma to improve degradation efficiency and avoids resonant frequency drift caused by waveguide thermal deformation.

[0104] As an alternative, the double-layered cylindrical tube has a dimension of 160mm-220mm in the ejection direction; the inner tube has a dimension of 40mm-50mm in the radial direction.

[0105] In specific implementation, such as Figure 1 and Figure 3 As shown, the nozzle has a single outlet diameter of 3 mm, generating a 250 mm long plasma torch at the upper end of the double-layered discharge tube. The discharge tube is a double-layered cylindrical structure. The outer tube 210 has a diameter Φ = 60 mm, 70 mm, or 80 mm, and its length in the ejection direction is 200 mm, 210 mm, 220 mm, or 230 mm. The inner tube 209 has a diameter Φ = 40 mm, 45 mm, or 50 mm, and its length in the ejection direction is 150 mm, 160 mm, 170 mm, or 180 mm. The outer tube 210 is connected to the upper end of the expanded structure reactor. This design allows the discharge tube to better confine the plasma torch and ensures that the length of the plasma torch can reach 220 mm, 230 mm, 240 mm, 250 mm, or 260 mm.

[0106] As an alternative, the size of the reaction section is larger than the size of the outer tube in the radial direction, and the reaction section is connected to the outer tube.

[0107] like Figure 1 and Figure 3As shown, the reaction section needs to accommodate a large amount of porous active solid material 202 for the reaction to take place. Therefore, a large space is required, and the heating and ejection effects of the plasma torch must be taken into account. The reaction section cannot be too far from the plasma torch in the ejection direction, otherwise it may not be able to participate in the reaction. Therefore, the radial dimension of the reaction section in the outer tube is set to be larger than the dimension of the outer tube, typically twice the dimension of the outer tube.

[0108] This allows more porous active solid material 202 to participate in the reaction, further improving the reaction rate and the adsorption and reaction efficiency of particles that form harmful byproducts.

[0109] As an alternative, the reaction part is spherical with a diameter of 350mm-450mm and the outer tube has a radial dimension of 60mm-80mm.

[0110] like Figure 3 As shown, the reaction section of the microwave plasma reactor is an ellipsoidal expanded structure made of quartz glass. The upper diameter Φ = 60 mm, 70 mm, 80 mm, or possibly 90 mm or 100 mm, and it is connected to the lower end of the outer tube 210. The maximum lateral diameter of the expanded section Φ = 300 mm, 350 mm, 400 mm, or 450 mm, and its height is 350 mm, 400 mm, or 450 mm. The lower end of the expanded structure is a cylindrical structure with a diameter Φ = 40 mm, 45 mm, or 50 mm. The porous active solid material has dimensions of 3 mm, 4 mm, or 5 mm.

[0111] In this size scenario, the reaction section can accommodate enough porous active solid material to participate in the reaction, and when the radial diameter of the outer tube is 80mm, 90mm or 100mm, it can be ensured that the porous active solid material in the reaction section can be effectively heated by the plasma torch and react with the particles in the plasma torch.

[0112] As an alternative, the reaction section has an outlet located away from the nozzle in the ejection direction; the reaction section also has a mesh fixing device at the outlet, configured to allow the porous active solid material to be permeably disposed in the reaction section.

[0113] like Figure 1 and Figure 3 As shown, the reaction section has an outlet at the bottom for transporting and further processing unreacted harmful byproduct gases, as well as harmless gases produced by the reaction, such as oxygen and water. To ensure air permeability, a porous active solid material is placed on a grid fixing device. This grid fixing device can be a grid that cannot participate in the reaction, or a porous plate.

[0114] As an alternative, the grid fixing device is a porous plate, which is fixed on the reaction section; the nozzle direction is from top to bottom, the nozzle is located above the reaction section, the porous active solid material is placed on the porous plate; the output port is located below the porous plate.

[0115] The porous plate offers greater stability and effectively supports the porous active solid material. With the nozzle pointing downwards (from top to bottom) and the porous active solid material positioned below it, gravity on the gas further assists in its ejection direction, thus enhancing reaction and adsorption efficiency.

[0116] In other embodiments, the nozzle direction can also be horizontal, or even from bottom to top, as long as the plasma torch can be directed toward the porous active solid material and effectively heat and react with it.

[0117] As an alternative, the porous active solid material is a spherical solid material; the diameter of the spherical solid material is 3-5 mm.

[0118] Spherical solid materials can form large gaps between themselves, thus providing sufficient space for adsorption and reaction of particles in the plasma torch. This results in better adsorption and reaction effects.

[0119] In other embodiments, the porous active solid material may also be in the form of regular or irregular blocks, and its size may also vary to meet the need for easy acquisition.

[0120] If the gaps between porous active solid materials are too small, it will affect the entry of particles into the plasma torch, resulting in lower adsorption and reaction rates. If the gaps between porous active solid materials are too large, turbulence will form inside the particle flow, which will affect the ion movement rate of the plasma torch and also lead to a decrease in adsorption and reaction rates.

[0121] Preferably, the diameter of the spherical solid material is 3-5 mm. It can be 3 mm, 4 mm, or 5 mm. At this size, a certain gap can be formed between the spherical solids, which satisfies the ion entry requirements of the plasma torch without significantly affecting the particle flow rate.

[0122] As an alternative, the spherical solid material is a mesoporous material. Mesoporous materials possess a hierarchical pore structure containing micron- and nanopores, with a porosity of 30-70%, specifically 30%, 40%, 50%, 60%, or 70%. Mesopores exist within the hierarchical pore structure, with diameters ranging from 1 nm to 20 nm. Specifically, these can be 1 nm, 2 nm, 3 nm, 5 nm, 7 nm, 9 nm, 10 nm, 12 nm, 15 nm, 18 nm, 20 nm, etc.

[0123] Mesoporous materials are a class of materials with a regular pore structure at the nm level. Due to their high specific surface area, adjustable pore size and surface chemical properties, they have good performance in adsorption scenarios, which facilitates reaction with particles in a plasma torch to generate solid compounds to solidify particles that generate harmful byproduct gases.

[0124] Preferably, the porosity is 45-65% and the mesopore diameter is 2nm-12nm. It exhibits good adsorption and reaction efficiency for particulate products of sulfur hexafluoride (SF6) and auxiliary gases.

[0125] As an alternative, the plasma torch includes hydrogen fluoride (HF), sulfur dioxide (SO2), and sulfur-oxygen-fluorine (SOF) ion / molecular products. The main component of the porous active solid material is a metal oxide. The metal oxide includes at least one of the following: iron oxide, aluminum oxide (Al2O3), magnesium oxide (MgO), and calcium oxide (CaO).

[0126] The aforementioned iron oxides can be ferrous oxide (FeO), ferric oxide (Fe₂O₃), or iron(III) oxide (Fe₃O₄). Since the harmful byproduct gases produced in the plasma torch of sulfur hexafluoride (SF₆) are mainly F and S elements, and the oxides and hydrides of these two elements are acidic, they can react with metal oxides to form solid inorganic metal salts. Therefore, using the aforementioned iron oxides, aluminum oxide (Al₂O₃), magnesium oxide (MgO), and calcium oxide (CaO) can all achieve the curing function.

[0127] Specifically, in one alternative, a combination of ferrous oxide (FeO), aluminum oxide (Al₂O₃), magnesium oxide (MgO), and calcium oxide (CaO) can be used. This combination has lower requirements for raw materials, resulting in lower manufacturing costs for the porous active solid material. In another alternative, a combination of aluminum oxide (Al₂O₃), magnesium oxide (MgO), and calcium oxide (CaO) can be used. Because ferrous oxide (FeO) is absent, the other metal oxides exhibit better reactivity than FeO, resulting in better adsorption performance compared to the first option.

[0128] Another alternative is to use a combination of magnesium oxide (MgO) and calcium oxide (CaO). This approach not only further increases the reaction rate but also takes into account raw material costs. Another alternative is to use either calcium oxide (CaO) or magnesium oxide (MgO) alone. This approach offers the highest reaction rate, thereby allowing for a further increase in the processing flow rate of sulfur hexafluoride (SF6).

[0129] As an alternative, the metal oxide is calcium oxide (CaO) and / or magnesium oxide (MgO).

[0130] Because calcium (Ca) and magnesium (Mg) have relatively stable fluorides and sulfides, especially calcium (Ca), whose fluorides and sulfides are relatively stable, they are more suitable as porous active solid materials to participate in the reaction and effectively solidify fluorine (F) and sulfur (S).

[0131] As an optional solution, the gas distribution system 1 includes a sulfur hexafluoride (SF6) gas source, an auxiliary gas source, and an air compressor 102; the first gas path of the auxiliary gas source is connected to the air compressor through a first pressurized gas path, and the first gas path is also combined with the second gas path of the SF6 gas source to form an output gas path; the output gas path is also connected to the air compressor through a second pressurized gas path; the output gas path is connected to the nozzle of the plasma generator.

[0132] like Figure 1 As shown, the sulfur hexafluoride (SF6) gas source can be the SF6 gas bag 101, which can be easily collected from power equipment for processing. The components of the entire device are relatively simple, and the overall device is very convenient compared to some large-scale centralized SF6 processing equipment. It can be moved and used to process SF6 as needed.

[0133] The first gas path of the auxiliary gas source is connected to the air compressor 102 via a first pressurization gas path. This allows the air compressor to pressurize the auxiliary gas or directly input pressurized air into the nozzle. The first gas path also merges with the second gas path of the sulfur hexafluoride (SF6) gas source to form an output gas path, where the gases are mixed to form a mixed gas. Of course, this output gas path can also refer to a simple merger of the first and second gas paths, meaning that the first and second gas paths only overlap in their paths, and the internal gases remain independent.

[0134] The output air path is also connected to the air compressor via a second pressurized air path. The output air path can also be connected to the air compressor 102, which provides compensating pressurization or secondary pressure regulation. This further improves the stability of air pressure control.

[0135] As an optional solution, the auxiliary gas is water vapor, and the auxiliary gas source is water vapor generator 103.

[0136] The auxiliary gases for the plasma degradation of SF6 can include reactive gases, inert diluent gases, and mixed gases. Reactive gases can include oxygen (O2), hydrogen (H2), and water vapor (H2O). Inert diluent gases can include argon (Ar) and nitrogen (N2). Mixed gases are mixtures of reactive and inert diluent gases, such as a mixture of oxygen (O2) and nitrogen (N2), or a mixture of water vapor (H2O) and argon (Ar).

[0137] Water vapor, as an auxiliary gas, promotes the complete mineralization of sulfur hexafluoride (SF6). Through the generation of hydroxyl radicals and hydrogen atoms, water vapor drives the decomposition of SF6 into acidic sulfur dioxide (SO2), hydrogen fluoride (HF), and a small amount of sulfur trioxide (SO3), preventing the accumulation of toxic intermediates (such as sulfur tetrafluoride (SF4) and thionyl fluoride (SOF2)). The final products, sulfur dioxide (SO2) and hydrogen fluoride (HF), can be absorbed by alkaline solutions, such as calcium hydroxide (Ca(OH)2), and neutralized to form calcium sulfate (CaSO4) and calcium fluoride (CaF2).

[0138] It can also enhance plasma activity. Water vapor dissociates in the plasma to generate active species, significantly improving oxidation capacity. The oxidation potential of hydroxyl radicals (2.8 V) is much higher than that of oxygen (O2), which can efficiently attack carbon-fluorine bonds (CF) and sulfur-fluorine bonds (SF). Moreover, when water vapor (H2O) mixes with oxygen (O2), the active oxygen species in the plasma (oxygen radicals (O·) and ozone (O3)) work synergistically with hydroxyl radicals to accelerate the decomposition of sulfur hexafluoride (SF6).

[0139] It can also inhibit the formation of toxic byproducts and reduce sulfur tetrafluoride (SF4) and thionyl fluoride (SOF2). Water vapor, by providing hydrogen atoms, blocks the decomposition chain reaction of sulfur hexafluoride (SF6) and low-fluoride sulfur (X-sulfur fluoride) in the process. X The formation of sulfur (S8) (common in pure argon (Ar) or nitrogen (N2) plasmas can be prevented by introducing water vapor (H2O) to avoid sulfur precipitation.

[0140] Water vapor can also optimize energy utilization efficiency. The presence of water vapor can reduce plasma breakdown voltage (because the ionization energy of water vapor H2O is lower than that of sulfur hexafluoride SF6), thus reducing energy consumption. The generated hydrogen fluoride HF can be treated through subsequent absorption, which, compared to directly generating corrosive intermediates such as SF4, can reduce corrosion of the reactor and extend equipment life.

[0141] Finally, water vapor is environmentally friendly and economical. The sulfur dioxide (SO2) and hydrogen fluoride (HF) produced by plasma decomposition of water vapor with sulfur hexafluoride (SF6) are conventional industrial waste gases that can be easily neutralized with lime slurry (producing gypsum and calcium fluoride), resulting in no secondary pollution. Water vapor is inexpensive and readily available, requiring no complex gas pretreatment.

[0142] As an optional solution, the gas distribution system also includes a controller; the second gas path, the first pressurized gas path, and the second pressurized gas path are all equipped with solenoid valves and flow meters; the solenoid valves, flow meters, and steam generators are all connected to the controller.

[0143] Setting the position of the solenoid valve can also be used to install flow meters and barometers, which are connected to the controller to monitor relevant data in the corresponding air path, providing a basis for subsequent operations. Specifically, for example... Figure 1As shown, a first flow meter 104, a third flow meter 106, and a second flow meter 105 are respectively installed on the second air path, the first pressurized air path, and the second pressurized air path.

[0144] As an optional solution, the exhaust gas treatment device 3 is an alkaline scrubbing device; the inlet of the alkaline scrubbing device is connected to the outlet of the plasma reactor, and the outlet of the alkaline scrubbing device is open to the atmosphere.

[0145] The exhaust gas treatment device 3 is an alkaline scrubbing device, which mainly includes a gas distribution system and an alkaline scrubbing device. The output port of the plasma reactor 22 decomposes the gases that have completed the reaction and those that have not participated in the reaction, mainly the exhaust gas generated by the reaction, including oxygen O2, water vapor H2O, and unreacted sulfur-oxygen-fluorine SOF ion / molecule products, into sulfur dioxide SO2, sulfur trioxide SO3, and hydrogen fluoride HF through high temperature.

[0146] Preferably, the alkaline solution in the alkaline washing device can be of the same composition as the aqueous solution of metal oxidation, which is the main component of porous active solid material, and ultimately a metal inorganic salt of the same composition as the solidified material, which can be used as a raw material for industrial concrete.

[0147] Example 2

[0148] This embodiment provides a harmless treatment device for the degradation of sulfur hexafluoride (SF6) waste gas by atmospheric pressure microwave plasma, including a gas distribution system 1, an atmospheric pressure microwave plasma treatment system 2, and an alkaline scrubbing emission system. The alkaline scrubbing emission system is also an optional solution for the exhaust gas treatment device 3.

[0149] like Figure 1 As shown, the gas distribution system uses a sulfur hexafluoride (SF6) gas bag 101, an air compressor 102, and a steam generator 103 to distribute the reactant gases (SF6 gas / dilution gas / active gas). The SF6 gas bag is made of high-pressure resistant flexible material, with a maximum capacity of 70 L and an operating pressure range of 0.1-0.3 MPa. The corresponding second gas path is equipped with a first flow meter 104 to control the SF6 intake volume. The air compressor 102 is equipped with two flow meters: a third flow meter 106 on the first pressurized gas path and a second flow meter 105 on the second pressurized gas path. The steam generator 103 can output saturated steam at 100℃ by heating or output room temperature steam by ultrasonic means.

[0150] The air compressor 102 compresses air to pressurize water vapor, that is, mixes air into water vapor. In this embodiment, the mixed gas is mainly water vapor, and also includes auxiliary gases such as nitrogen (N2) and oxygen (O2) as air components.

[0151] SF6 air bag 101 outputs air at a flow rate of 1 L / h. Air compressor 102 provides air at a flow rate of 10 L / min, and steam generator 13 uses heating to stably produce air at 2 L / min at 100°C. The three air paths are delivered to the three-channel conical nozzle through branch pipes.

[0152] The atmospheric pressure microwave plasma processing system includes an atmospheric pressure microwave plasma generator and a microwave plasma reactor.

[0153] The atmospheric pressure microwave plasma generator comprises a rectangular waveguide, a nozzle, and a discharge tube. The rectangular waveguide is a BJ22 or BJ26 waveguide, outputting 2.45 GHz, 500-3000 W adjustable microwaves. A plasma torch, 150-300 mm long, is excited through a three-channel conical nozzle at the top. The nozzle has a single outlet diameter of 2-5 mm and is located at the upper end of the double-layered discharge tube. The discharge tube is a double-layered cylindrical structure made of quartz glass. The outer layer has a diameter Φ=60-80 mm and a length of 200-250 mm, while the inner layer has a diameter Φ=40-50 mm and a length of 150-180 mm. It is heat-resistant to ≥1500℃. The outer discharge tube is connected to the microwave plasma reactor.

[0154] This embodiment uses a BJ22 rectangular waveguide to output 1000 W, 2.45 GHz microwaves. The nozzle for the input gas and the discharge tube for generating plasma are both placed inside the rectangular waveguide. Figure 2 As shown, the nozzle has a single outlet diameter of 3 mm, which generates a 250 mm long plasma torch at the upper end of the double-layered discharge tube. The discharge tube is a double-layered cylindrical structure made of quartz glass. The outer tube 210 has a diameter of Φ=90 mm and a length of 220 mm, while the inner tube 209 has a diameter of Φ=45 mm and a length of 160 mm. The outer tube 210 is connected to the upper end of the expanded structure reactor.

[0155] The microwave plasma reactor is an elliptical, spherical, expanded structure made of quartz glass, resistant to temperatures ≥1500℃. The upper diameter is Φ=60-80 mm, and the remaining outer discharge tubes are of the same size and connected to the lower ends of the outer discharge tubes. The maximum lateral diameter of the expanded section is Φ=300-400 mm, and the height is 400-500 mm. The lower end of the expanded structure is a cylindrical structure with a diameter Φ=40-50 mm, connected to the alkaline washing discharge system via branch pipes. The interior of this expanded structure is filled with one or more porous active solid materials such as calcium oxide (CaO), magnesium oxide (MgO), aluminum oxide (Al2O3), or ferric oxide (Fe2O3) with a diameter of Φ3-6 mm. The pore size of the porous active solid material is 1 nm-100 nm, preferably 5-50 nm, and the porosity is 0.5-0.8 cm⁻¹. 3 / g, with a mass ratio of 1:1, and a filling amount of 200-500 g. A porous baffle at the lower end of the expanded structure separates the porous active solid material from the reactor end. The plasma torch penetrates 50-150 mm into the porous active solid material. An internal thermocouple monitors the reactor temperature in real time at 800-1400℃.

[0156] like Figure 3 As shown, the upper end of the expanded structure has a diameter of Φ=90 mm and is connected to the lower end of the outer discharge tube. The maximum lateral dimension of the expanded part is a diameter of Φ=350 mm and a height of 450 mm. The lower end of the expanded structure is a cylindrical structure with a diameter of Φ=45 mm, which is connected to the alkaline washing discharge system through a gas pipe. The interior of the expanded structure is filled with two porous active solid materials, calcium oxide (CaO) and magnesium oxide (MgO), with a diameter of Φ=4 mm. The porous active solid materials have mesopores with a pore size of 10 nm and a porosity of 0.6 cm. 3 / g, with a mass ratio of 1:1, and a filling amount of 400 g. A porous baffle at the lower end of the expanded structure separates the porous active solid material from the reactor end. The plasma torch penetrates 100 mm into the porous active solid material. An internal thermocouple monitors the reactor temperature in real time at 1200℃.

[0157] The alkaline scrubbing discharge system contains 5-10 L of a mixed solution of sodium hydroxide (NaOH) and calcium hydroxide (Ca(OH)₂), with NaOH concentrations of 0.5-0.8 mol / L and Ca(OH)₂ concentrations of 0.2-0.5 mol / L. This is because Ca(OH)₂ is only slightly soluble in water, which results in a low reaction rate with acidic gases. Adding water-soluble NaOH can increase the reaction rate.

[0158] Sodium hydroxide (NaOH) reacts with hydrogen fluoride (HF) to form sodium fluoride (NaF). Sodium fluoride (NaF) can further react with calcium hydroxide (Ca(OH)₂) in a metathesis reaction (ion exchange reaction) to form precipitated calcium fluoride (CaF). Similarly, sodium hydroxide (NaOH) reacts with sulfur dioxide (SO₂) and sulfur trioxide (SO₃) to form sodium sulfate (NaSO₄). Sodium sulfate (NaSO₄) can further react with calcium hydroxide (Ca(OH)₂) in a metathesis reaction (ion exchange reaction) to form precipitated calcium sulfate (CaSO₄). Ultimately, both precipitated calcium fluoride (CaF) and calcium sulfate (CaSO₄) are solidified.

[0159] Some solid particles are placed in the solution to disperse the gas in the alkaline solution. The gas-liquid contact time is ≥10 s. The exhaust port integrates a pH sensor (range 0-14, accuracy ±0.1) and is discharged into the atmosphere.

[0160] Preferably, the alkaline scrubbing emission system contains an 8L mixed solution of sodium hydroxide (NaOH) and calcium hydroxide (Ca(OH)2), with a NaOH concentration of 0.6 mol / L and a Ca(OH)2 concentration of 0.3 mol / L. Some solid particles are placed in the solution to disperse the gas within the alkaline solution. The gas-liquid contact time is 12 s, and a pH sensor (range 0~14, accuracy ±0.1) is integrated at the exhaust port.

[0161] This embodiment utilizes a microwave plasma torch to degrade sulfur hexafluoride (SF6) gas. The degradation products enter the expanded structure at the end of the microwave plasma reactor along with the plasma. Under the action of the plasma, the active solid material is heated and undergoes a spontaneous reaction to generate solid byproducts of harmful substances, achieving efficient degradation of SF6 and effective suppression of harmful byproducts. The processing flow rate can reach 0.5-40 L / h, the SF6 degradation efficiency is ≥99.0%, and the amount of harmful byproducts (such as SO2, HF, etc.) generated is ≤0.1%.

[0162] Example 3

[0163] Figure 4 This is a flowchart illustrating a method for the harmless treatment of SF6 waste gas by degradation using atmospheric pressure microwave plasma, as described in an embodiment of the present invention. Figure 4 As shown, according to another aspect of the present invention, a method for harmlessly treating SF6 waste gas by degradation using atmospheric pressure microwave plasma is also provided, comprising the following steps:

[0164] In step S401, sulfur hexafluoride (SF6) is mixed with auxiliary gas through a gas mixing system and then input into the plasma generator.

[0165] In step S402, sulfur hexafluoride (SF6) is mixed with an auxiliary gas using a plasma generator, ejected in a predetermined ejection direction, and ionized to form a plasma torch.

[0166] Step S403: A porous active solid material positioned in the direction of plasma torch ejection adsorbs and reacts with the plasma torch to generate solid reactants and non-alkaline exhaust gas. The porous active solid material and the plasma torch form a chemical reaction system, and the free energy change of the chemical reaction system before and after the reaction is described. satisfy: In the formula, ΔH is the enthalpy change of the chemical reaction system, ΔS is the entropy change of the chemical reaction system, and T is the absolute temperature of the chemical reaction system, and 0 <T<4000K。

[0167] In step S404, the non-alkaline exhaust gas is transferred to the exhaust gas treatment device 3, where it undergoes a secondary reaction in the alkaline solution within the device to achieve harmless treatment.

[0168] The aforementioned method for the harmless treatment of sulfur hexafluoride (SF6) waste gas by atmospheric pressure microwave plasma degradation involves a gas distribution system that mixes SF6 with an auxiliary gas. A plasma generator ionizes the mixture of SF6 and the auxiliary gas to create a plasma torch, which is then ejected into a plasma reactor. Inside the plasma reactor, a porous active solid material contacts and is heated by the plasma torch, spontaneously reacting with molecules / ions within the torch to generate solid reactants and non-alkaline tail gas. This non-alkaline tail gas undergoes a secondary reaction in the tail gas treatment device 3 to achieve harmless treatment. This method significantly improves the treatment efficiency and suppression effect of harmful byproducts, enabling higher flow rates for ion treatment. It solves the problems of low flow rates and difficulty in suppressing harmful byproducts in existing SF6 degradation treatment methods. The atmospheric pressure microwave plasma technology achieves convenient, efficient, reliable, and low-cost degradation treatment of SF6 waste gas.

[0169] The free energy changes before and after the chemical reaction between the main components of the porous active solid material and the relevant ions of sulfur (S) and fluorine (F) elements in the plasma torch. satisfy: In other words, the main components of the porous active solid material 202 form a chemical reaction system with the molecules / ions in the plasma torch. This system can spontaneously react at temperatures ranging from 0-4000K, and the products tend to exist in a solid state. Combined with the properties of porous materials, this allows for the rapid and efficient solidification of ions that would otherwise form harmful byproducts when adsorbing molecules / ions from the plasma torch. This not only improves processing efficiency and thus increases the flow rate, but also prevents the ions of harmful byproducts from easily undergoing secondary reactions to generate harmful gaseous byproducts when forming gaseous products. This further improves the treatment efficiency of sulfur hexafluoride (SF6).

[0170] Finally, the exhaust gas is connected to the output port of the plasma reactor via the exhaust gas treatment device 3, which contains an alkaline solution. Since the harmful byproduct gases are generally acidic gases of fluorine oxides and sulfur oxides, the alkaline solution can fully react the small amount of gas that has not reacted with the porous active solid material 202, thus achieving harmless treatment.

[0171] As an alternative, SF6 is mixed with auxiliary gas through a gas mixing system and input into the plasma generator. This includes: transmitting SF6 and water vapor through independent gas paths to the first and second gas channels of the multi-gas channel nozzle of the plasma generator; and pressurizing the mixture by an air compressor so that the multi-gas channel nozzle mixes the SF6 and water vapor while ejecting the mixture.

[0172] Pressurized sulfur hexafluoride (SF6) and water vapor are transported through independent gas paths and mixed simultaneously when ejected from the first and second independent gas channels of a multi-channel nozzle. This results in better mixing and thus improves the plasma reaction effect. It also avoids uneven mixing within the gas path, which could alter the plasma reaction path and negatively impact the plasma reaction outcome.

[0173] The auxiliary gas is water vapor, which is transmitted to the nozzle through an independent gas path and mixed while being ejected. The pressurized gas has higher energy and can be mixed more evenly while being ejected, thereby improving the ionization effect.

[0174] In addition, water vapor, as an auxiliary gas, can not only prevent the accumulation of toxic intermediates and effectively inhibit the formation of toxic byproducts, but also enhance plasma activity, accelerate the decomposition of sulfur hexafluoride (SF6), and reduce energy consumption and costs.

[0175] As an alternative, pressurization is performed using an air compressor, including: pressurizing water vapor by introducing air at a preset pressure into the first air passage through the first pressurization air passage of the air compressor, wherein the first pressurization air passage is connected to the first air passage and the first air passage is connected to the second gas passage; or, inputting the air into the third gas passage of the multi-gas-channel nozzle through the second pressurization air passage of the air compressor, thereby drawing out SF6 and water vapor under negative pressure while spraying them out.

[0176] When the air compressor is pressurizing, water vapor can be directly pressurized with air, which saves on gas lines and simplifies the structure. Alternatively, the high-pressure air from the air compressor can be input into an independent third gas channel through a second pressurization gas line and a multi-gas-channel nozzle. While the high-pressure air is being ejected, the sulfur hexafluoride (SF6) and water vapor in the first and second gas channels are drawn out under negative pressure and mixed. In this way, both SF6 and water vapor can be continuously and stably ejected and effectively mixed during ejection, improving ionization and plasma reaction efficiency.

[0177] It should be noted that after the high-pressure air is ejected, the sulfur hexafluoride (SF6) and water vapor are drawn out under negative pressure, which is equivalent to indirectly pressurizing the sulfur hexafluoride (SF6) and water vapor, allowing them to be ejected more quickly.

[0178] In another feasible implementation where sulfur hexafluoride (SF6) and water vapor are mixed and transported, the second gas path of SF6 and the first gas path of water vapor can be combined into a mixed gas path before being transported to the nozzle. In this feasible implementation, the air compressor can either directly pressurize the mixed gas path or use a direct nozzle to indirectly pressurize the gas by simultaneously applying negative pressure to the mixed gas of SF6 and water vapor in the mixed gas path during spraying.

[0179] In other embodiments, an air compressor can also pressurize sulfur hexafluoride (SF6). However, considering the limited content of SF6 in the gas bag, simply pressurizing SF6 without sufficient auxiliary gas can directly affect the plasma degradation effect, easily leading to incomplete SF6 reaction. This would also reduce efficiency and increase the likelihood of incomplete reaction when solidifying harmful byproduct gas particles. Therefore, in this embodiment, pressurizing the auxiliary gas is prioritized to ensure sufficient auxiliary gas participates in the reaction and thoroughly degrades SF6.

[0180] As an alternative, the mixed gas is ejected in a predetermined ejection direction by a plasma generator and ionized to form a plasma torch, including: ionizing the ejected mixed gas through a waveguide device to form a plasma torch; and beaming the plasma torch through a discharge tube of a double-layer cylindrical tube.

[0181] The waveguide device can ionize plasma using ambient pressure microwaves, achieving a relatively small size. It ionizes the ejected mixed gas to form a plasma torch. This is then combined with a double-layered cylindrical discharge tube to beam the plasma torch, ensuring that the plasma particles collide and mix thoroughly within the discharge tube, and then react fully before reaching the porous active solid material.

[0182] The double-layered cylindrical tube comprises an outer tube 210 and an inner tube 209. A waveguide device is mounted on the outer tube 210 to meet installation requirements. A nozzle is located at one end of the inner tube 209 to house the plasma torch. The inner tube 209's dimensions are closer to the nozzle, eliminating gas backflow and allowing the gas ejected from the nozzle to mix and ionize, thus improving the ionization effect. Simultaneously, it also provides a better jetting effect on the plasma torch.

[0183] The plasma torch is precisely directed to heat and react with the porous active solid material. The reaction rate is increased to ensure sufficient reaction between plasma particles and the porous active solid material, minimizing the transfer of unreacted harmful byproduct gases to the exhaust gas treatment device 3. This avoids increasing the processing pressure of the exhaust gas treatment device 3.

[0184] As an alternative, after beaming the plasma torch through the discharge tube of the double-layer cylindrical tube, the method further includes: if the end of the plasma torch does not touch the porous active solid material, increasing the output pressure of the air compressor and raising the microwave power of the microwave source of the waveguide device to lengthen the plasma torch so that it can touch the porous active solid material; or, if the diameter of the porous active solid material touched by the plasma torch exceeds a preset parameter, decreasing the output pressure of the air compressor and lowering the microwave power of the microwave source of the waveguide device to shorten the plasma torch.

[0185] It should be noted that in addition to degrading sulfur hexafluoride (SF6), the high temperature generated by the plasma torch can also be used to heat porous active solid materials, thereby increasing the reaction rate. Therefore, the plasma torch needs to be able to reach the porous active solid material. If the plasma torch is short, it can be extended by pressurizing it with an air compressor. To match the increased gas flow rate after pressurization, the microwave source of the waveguide device also needs to have its microwave power increased accordingly to ensure the efficiency and extent of plasma degradation.

[0186] plasma sustaining power P maintain To meet the requirements for ionization and excitation, its relationship with gas pressure p can be:

[0187] P maintain ∝n e ⋅E collision ∝p⋅f(E / p), where n e E is the electron density. collision E represents the collision energy loss, E represents the electric field strength, and f() is the plasma characteristic function of sulfur hexafluoride (SF6) and water vapor, used to describe the effect of the ratio of electric field strength E to gas pressure p on plasma characteristics.

[0188] When the gas pressure increases, if the power remains unchanged while the gas pressure is adjusted, it may lead to plasma instability and insufficient electron energy. The power needs to be increased simultaneously to compensate for the higher collision energy loss and maintain ionization balance.

[0189] As an alternative, a porous active solid material positioned in the direction of plasma torch ejection is used to adsorb and chemically react with the plasma torch, generating solid reactants and non-alkaline exhaust gas. This includes: adsorbing and reacting SOF ion / molecular products from the plasma torch through a porous active solid material whose main component is metal oxide to generate solid inorganic salts and corresponding exhaust gas, which includes O2 and H2O; unreacted SOF ion / molecular products are decomposed into SO2, SO3, and HF at high temperature; SO2, SO3, and HF are mixed with the exhaust gas to form non-alkaline exhaust gas.

[0190] The types of sulfur-oxygen-fluorine (SOF) ionic / molecular products are numerous. When reacting with metal oxides, they generate corresponding inorganic metal salts. Intermediate products are generally harmless oxygen (O2) and water vapor (H2O). Taking sulfur difluoride (sulfonyl difluoride) SO2F2 and calcium oxide (CaO) as an example, sulfur difluoride (sulfonyl difluoride) SO2F2 is decomposed under plasma irradiation to form active particles, which then react with calcium oxide (CaO). The overall chemical reaction equation is: The reaction process is as follows: , , .

[0191] The final intermediate products are mainly oxygen (O2) and water vapor (H2O). Although hydrogen fluoride (HF) is also a gas, it can further participate in the reaction to produce calcium fluoride (CaF2) and water (H2O). Even if some does not participate in the reaction, it can be rendered harmless by the alkaline solution in the tail gas treatment device 3.

[0192] As an alternative, after the unreacted SOF ion / molecular products are decomposed into SO2, SO3, and HF at high temperature, the method further includes: adsorbing and reacting SO2, SO3, and HF through a porous active solid material whose main components are metal oxides to generate solid inorganic salts and H2O; and mixing the unreacted SO2, SO3, and HF with the tail gas and H2O to form non-alkaline tail gas.

[0193] Microwave plasma is a high-enthalpy plasma. The sulfur-oxygen-fluorine (SOF) ion / molecular products in the plasma torch can be further decomposed at high temperatures into sulfur dioxide (SO2), sulfur trioxide (SO3), and hydrogen fluoride (HF). HF and SO2 can directly participate in the above reactions. At high temperatures, SO3 can partially decompose into SO2 and O2, a reversible endothermic reaction. The chemical equation is as follows: It can also participate in the reaction. However, unreacted sulfur trioxide (SO3) or sulfur dioxide generated in the reverse reaction can be rendered harmless by the alkaline solution in the tail gas treatment device 3.

[0194] As an alternative, the non-alkaline exhaust gas is transferred to an exhaust gas treatment device, where it undergoes a secondary reaction in an alkaline solution to achieve harmless treatment. This includes: reacting acidic gases in the non-alkaline exhaust gas with the alkaline solution in the alkaline washing device to produce water and inorganic salts, where the acidic gases include SO2, SO3, and HF; and dissolving neutral gases in the non-alkaline exhaust gas, where the neutral gases include O2 and H2O.

[0195] The alkaline solution in the alkaline washing device reacts with the acidic gases in the non-alkaline tail gas to produce water and inorganic salts. The acidic gases include hydrogen fluoride (HF), sulfur trioxide (SO3), and sulfur dioxide (SO2). The alkaline solution also dissolves the neutral gases in the non-alkaline tail gas, which include oxygen (O2) and water vapor (H2O). The inorganic salts are used to manufacture industrial concrete.

[0196] The aforementioned non-alkaline exhaust gas includes neutral oxygen (O2) and water vapor (H2O) which dissolve the acidic hydrogen fluoride (HF), sulfur trioxide (SO3), and sulfur dioxide (SO2) in the alkaline solution to produce water and inorganic salts, thus completing the solidification of sulfur (S) and fluorine (F) elements that have not reacted with the porous active solid material.

[0197] As an alternative, the method further includes reacting the acidic gas in the non-alkaline tail gas with the alkaline solution of the alkaline washing device to generate water and inorganic salts, and then extracting the solid inorganic salts on the porous active solid material and the inorganic salts in the alkaline solution; and manufacturing industrial concrete using the extracted solid inorganic salts and inorganic salts.

[0198] The resulting inorganic salts can also be used in the manufacture of industrial concrete. For this purpose, the metal cations in the alkaline solution can be consistent with the metal cations in the metal oxide, allowing the final inorganic metal salts to aggregate and be used together as raw materials for industrial concrete. Further recycling of the harmless treatment products avoids resource waste, improves the system's energy-saving and environmental performance, and generates certain economic benefits.

[0199] Example 4

[0200] Based on the harmless treatment device for degrading sulfur hexafluoride (SF6) waste gas by atmospheric pressure microwave plasma according to Example 2, a harmless treatment method for degrading sulfur hexafluoride (SF6) waste gas by atmospheric pressure microwave plasma is also provided, including the following steps.

[0201] The sulfur hexafluoride (SF6) gas bag 101, air compressor 102, and steam generator 103 control the flow meter to deliver the SF6 gas, dilution gas, and active gas to the nozzle in the rectangular waveguide in proportion through the branch pipe.

[0202] The nozzle emits a mixture of reactive gas and sulfur hexafluoride (SF6) through multiple outlets. Under the action of a strong electric field at the tip, the mixture is efficiently ionized and ignited into a plasma torch. This plasma continuously absorbs microwave energy, which enhances its own energy and causes more SF6 and reactive gas to ionize, generating more charged particles. This process continuously increases the number and energy of particles, thereby promoting the efficient ionization and degradation of SF6.

[0203] The inner tube 209 of the double-layer discharge tube confines the plasma to enhance the concentration of microwave energy, while the outer tube 210 of the double-layer discharge tube is a glass tube that isolates the high temperature from the waveguide. This maintains the high enthalpy stability of the plasma to improve degradation efficiency and avoids resonant frequency drift caused by waveguide thermal deformation.

[0204] Sulfur hexafluoride (SF6) gas undergoes microwave plasma degradation in a discharge tube. An expanded structure is filled with one or more porous active solid materials such as calcium oxide (CaO) and magnesium oxide (MgO). The end of the plasma torch contacts the active material, heating it. The degradation products of SF6 enter the expanded region filled with porous active material via the plasma torch, passing through the high-temperature porous active material layer at a relatively slow speed. This high reaction temperature increases the reaction rate between the degradation products and the active material, and ensures that the degradation products are fully adsorbed and react with the active material, thus preventing the formation of harmful byproducts. Unreacted degradation products (sulfur-oxygen-fluorine SOF-like substances) are fully decomposed into harmful gases (sulfur dioxide (SO2), hydrogen fluoride (HF), etc.) under the combined action of plasma and the high temperature within the reactor. These gases further react with the active material to generate calcium sulfate, calcium fluoride, magnesium sulfate, etc. A small amount of unreacted harmful gases (sulfur dioxide (SO2), hydrogen fluoride (HF), etc.) are transported to the alkaline solution discharge system through a branch pipe.

[0205] In the alkaline discharge system, sodium hydroxide (NaOH) and calcium hydroxide (Ca(OH)2) solutions react with trace amounts of harmful gases (sulfur dioxide (SO2), hydrogen fluoride (HF), etc.) that have not been completely absorbed, achieving harmless discharge.

[0206] Preheat the steam generator to 150°C and stabilize the steam production. Then, simultaneously turn on the air compressor 12 and the sulfur hexafluoride SF6 gas bag to pre-stabilize the gas path for 30 seconds.

[0207] By gradually increasing the microwave power to 1000 W, a mixture of reactive gas and sulfur hexafluoride (SF6) is ejected from multiple nozzle outlets. Under the action of the locally enhanced electric field at the tip, the reactive gas is efficiently ionized, successfully igniting and forming plasma. This plasma then effectively absorbs microwave energy, enabling plasma growth and promoting efficient ionization of SF6.

[0208] The outer glass tube of the double-layer discharge tube isolates the high-temperature discharge region from the rectangular waveguide, reducing heat loss in the discharge tube region. This maintains the stability of the plasma and its high enthalpy properties, improving the degradation efficiency and energy utilization efficiency of sulfur hexafluoride (SF6). On the other hand, it prevents the compressed waveguide from absorbing too much heat and undergoing large size and shape changes, which would cause a large drift in the resonant frequency. The interior of the inner tube is the plasma reaction zone, confining the plasma to a small area. Microwave energy is completely absorbed by the confined plasma, further enhancing the concentration of microwave energy and achieving efficient ionization of the gas.

[0209] Figure 5 This is a schematic diagram illustrating the microwave plasma degradation of a mixed gas according to an embodiment of the present invention, as shown below. Figure 5As shown, sulfur hexafluoride (SF6) gas enters the expanded structure connected to the outer glass tube of the discharge tube. In the plasma-affected zone, it is degraded by microwave plasma. By rationally selecting process conditions, the reaction pathway of SF6 degradation and product formation can be regulated by allowing the SF6 dissociation intermediates or primary degradation products to react with the active gas, thereby weakening the conditions in the plasma that are conducive to the formation of harmful byproducts.

[0210] Figure 6 This is a schematic diagram illustrating the reaction between a plasma torch and a porous active solid material according to an embodiment of the present invention, as shown below. Figure 6 As shown, the degradation products of the plasma torch enter the expansion zone filled with porous active material with the gas flow, and pass through the porous active material layer at a relatively slow speed. On the one hand, this ensures that harmful byproducts are fully adsorbed on the surface of the active material and react with it; on the other hand, heating the active material increases the reaction rate between the harmful byproducts and the active material. Before the intermediate products of sulfur hexafluoride (SF6) undergo chemical reactions to generate harmful byproducts such as oxygen difluoride (OF2) and sulfur-oxygen-fluorine (SOF), they react with active substances such as calcium oxide (CaO) to generate more stable solid substances such as calcium fluoride (CaF2) and calcium sulfate (CaSO4), thus blocking the formation of harmful byproducts.

[0211] Taking sulfur difluoride (sulfonyl difluoride) SO2F2 and calcium oxide CaO as examples, sulfur difluoride (sulfonyl difluoride) SO2F2 is cracked under the action of plasma to form active particles, which then react with calcium oxide CaO. The overall chemical reaction equation is shown in Equation 1, and the reaction process is shown in Equations 2-4.

[0212] Formula 1

[0213] Formula 2

[0214] Formula 3

[0215] Formula 4

[0216] The basic thermodynamic data for each substance in this reaction were obtained with reference to the "Practical Handbook of Thermodynamic Data for Inorganic Substances".

[0217] Enthalpy of calcium sulfate (CaSO4)

[0218] Entropy of calcium sulfate (CaSO4)

[0219] Enthalpy of calcium oxide (CaO)

[0220] Entropy of calcium oxide (CaO)

[0221] Enthalpy of calcium fluoride (CaF2)

[0222] Entropy of calcium fluoride (CaF2)

[0223] Enthalpy of sulfuryl difluoride SO2F2

[0224] Entropy of sulfuryl difluoride SO2F2

[0225] Therefore, the change in free energy before and after the reaction can be calculated according to Equation 1 above. , The condition holds true consistently within the temperature range of 0-4000 K, indicating that under the influence of plasma, fluorine (F) and sulfur (S) elements tend to exist in the form of calcium fluoride (CaF2) and calcium sulfate (CaSO4). Therefore, it is thermodynamically feasible to use active solids such as calcium oxide (CaO) to consume fluorine (F) and sulfur (S) elements in plasma to inhibit the formation of harmful byproducts.

[0226] also, Figure 7 This is a schematic diagram of the high-temperature decomposition and re-reaction of the plasma torch according to an embodiment of the present invention, as shown below. Figure 7 As shown, the thermodynamic stability of the generated solid material and the high enthalpy property of microwave plasma ensure that the formation of harmful byproducts can be effectively suppressed through the method of "enhancing the adsorption and re-decomposition of harmful byproducts". That is, the harmful byproducts (sulfur-oxygen-fluorine SOF substances) that have not reacted with the solid active material are fully decomposed into harmful gases (sulfur dioxide SO2, hydrogen fluoride HF, etc.) under the combined action of plasma and high temperature in the reactor.

[0227] Figure 8 This is a schematic diagram illustrating the harmless treatment of non-alkaline exhaust gas according to an embodiment of the present invention, as shown below. Figure 8 As shown, some harmful gases are absorbed by solid active materials, and the small amount of harmful gases that do not react with the active materials (sulfur dioxide SO2, hydrogen fluoride HF, etc.) are introduced into the alkaline discharge system through the branch pipe to react with sodium hydroxide NaOH and calcium hydroxide Ca(OH)2 solution to complete the terminal treatment, thus achieving green emission of sulfur hexafluoride SF6 waste gas.

[0228] Figure 9 This is a schematic diagram showing the component detection results in the final emission gas of an embodiment of the present invention, as shown below. Figure 9 As shown, Fourier transform infrared spectroscopy results indicate that no sulfur hexafluoride (SF6) component was detected in the SF6 degradation products. Testing proved that with a SF6 treatment flow rate of 1 L / h, the degradation efficiency reached 100%, and the generation of harmful byproducts (such as sulfur dioxide (SO2) and hydrogen fluoride (HF)) was ≤0.1%.

[0229] Compared to related technologies such as dielectric barrier discharge (DBD), the dielectric is easily corroded, and the single-reaction tube has a low processing flow rate. At a discharge power of 1 kW, the processing flow rate for 2% sulfur hexafluoride (SF6) waste gas is only 150 mL / min, equivalent to a SF6 processing capacity of 0.18 L / h. Furthermore, the degradation rate decreases significantly with increasing SF6 concentration, making it difficult to meet the degradation requirements of large quantities of SF6. The SF6 processing flow rate of this embodiment is 5-10 times that of related technologies, offering better processing flow rate and degradation efficiency, thus meeting the degradation requirements of much larger quantities of SF6.

[0230] It should be noted that the term "comprising" and its variations used in the embodiments of this invention are open-ended, meaning "including but not limited to". The term "based on" means "at least partially based on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments". The modifications of "one" and "a plurality" mentioned in the embodiments of this invention are illustrative and not restrictive, and those skilled in the art should understand that unless explicitly indicated otherwise in the context, they should be understood as "one or more".

[0231] The steps described in the method embodiments provided by the present invention can be performed in different orders and / or in parallel. Furthermore, the method embodiments may include additional steps and / or omit the steps shown. The scope of protection of the present invention is not limited in this respect.

[0232] The term "embodiment" in this specification refers to a specific feature, structure, or characteristic described in connection with an embodiment that may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily imply the same embodiment, nor does it imply independence or alternativeity from other embodiments. The various embodiments in this specification are described in a related manner, with reference to each other for similar or identical parts. In particular, for apparatus, device, and system embodiments, since they are substantially similar to method embodiments, the description is relatively simple, and relevant details are referred to in the description of the method embodiments.

[0233] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of protection. It should be noted that those skilled in the art can make various modifications and improvements without departing from the inventive concept of the present invention, and these all fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. A harmless treatment device for decomposing SF6 waste gas by atmospheric microwave plasma, characterized in that, The application relates to a plasma generator, a plasma reactor, a tail gas treatment device and a gas distribution system. The gas distribution system is used for distributing SF6 and auxiliary gas. The plasma generator is connected with the gas distribution system, used for ionizing the mixed gas of SF6 and auxiliary gas to obtain a plasma torch, and spraying the plasma torch to the plasma reactor according to a spraying direction. The plasma generator comprises a nozzle and a waveguide device; the nozzle is a multi-gas-channel nozzle, and multiple gas channels independently spray mixed gas; the nozzle comprises a nozzle base, a gradually-changing part and a tip part; the nozzle base is fixed on an input port of the plasma reactor, the gradually-changing part is connected with the nozzle base, the size of the gradually-changing part gradually decreases along the spraying direction, the tip part is connected with the smaller end of the gradually-changing part, and the size of the tip part is fixed along the spraying direction; the tip part is provided with one gas channel; the gradually-changing part is provided with multiple gas channels, and the multiple gas channels are uniformly arranged on the gradually-changing part around the gas channel of the tip part. The plasma reactor is provided with porous active solid material, the porous active solid material is in contact with the plasma torch and is heated to generate solid-state reactants and non-basic tail gas, and the non-basic tail gas is subjected to secondary reaction by the tail gas treatment device to realize harmless treatment. In the formula, Delta H is the enthalpy change of the chemical reaction system, Delta S is the entropy change of the chemical reaction system, T is the absolute temperature of the chemical reaction system, and 0 < T < 4000 K. wherein the porous active solid material forms a chemical reaction system with the plasma torch, and the free energy change of the chemical reaction system before and after the reaction satisfies: ； 2. The harmless treatment device for normal-pressure microwave plasma degradation of SF6 waste gas according to claim 1, wherein the nozzle is connected with the gas distribution system and used for spraying the mixed gas to the action range of the waveguide device, and the waveguide device is used for ionizing and heating the mixed gas to obtain a plasma torch. The spraying direction of the nozzle is towards the setting position of the porous active solid material. The nozzle is arranged on the input port of the plasma reactor. The waveguide device is arranged on the plasma reactor close to the input port, so that the edge of the action area of the waveguide device corresponds to the setting position of the nozzle, and the waveguide device is used for ionizing the mixed gas sprayed by the nozzle in the plasma reactor.

3. The apparatus according to claim 2, wherein The waveguide device is a rectangular waveguide. The multiple gas channels comprise a first gas channel used for transmitting SF6, a second gas channel used for transmitting auxiliary gas and a third gas channel used for transmitting pressurized gas.

4. The apparatus according to claim 3, wherein The plasma reactor is further provided with a discharge tube, and the discharge tube is arranged on the waveguide device.

5. The apparatus for harmless treatment of SF6 waste gas by atmospheric microwave plasma degradation according to claim 1, characterized in that, One end of the discharge tube is arranged as the input port, and the other end of the discharge tube is connected with a reaction part used for placing the porous active solid material.

6. The apparatus for harmless treatment of SF6 waste gas by atmospheric microwave plasma degradation according to claim 3, characterized by The discharge tube is a columnar tube, and the discharge tube is used for containing the plasma torch. ​ 7. The apparatus according to claim 6, wherein ​ The length of the columnar tube is not less than half of the length of the plasma torch, and the length of the plasma torch is the size of the plasma torch flame along the ejection direction.

8. The apparatus according to claim 6, wherein The discharge tube is a double-layer columnar tube, which comprises an outer tube and an inner tube, the waveguide device is arranged on the outer tube, and the nozzle is arranged at one end of the inner tube to accommodate the plasma torch in the inner tube.

9. The apparatus according to claim 8, wherein The size of the double-layer columnar tube in the ejection direction is 160-220 mm. The size of the inner tube in the radial direction is 40-50 mm.

10. The apparatus for harmless treatment of SF6 waste gas by atmospheric microwave plasma degradation according to claim 8, characterized by In the radial direction of the outer tube, the size of the reaction part is greater than that of the outer tube, and the reaction part is connected with the outer tube.

11. The apparatus for harmless treatment of SF6 waste gas by atmospheric microwave plasma degradation according to claim 10, characterized by, The reaction part is spherical, the diameter of the reaction part is 350-450 mm, and the size of the outer tube in the radial direction is 80-100 mm.

12. The apparatus for harmless treatment of SF6 waste gas by atmospheric microwave plasma degradation according to claim 6, characterized by, The output port is arranged at a position away from the nozzle in the ejection direction. The reaction part is further provided with a grid fixing device at the output port, and the porous active solid material is arranged in the reaction part in a breathable manner.

13. The apparatus for harmless treatment of SF6 waste gas by atmospheric microwave plasma degradation according to claim 12, characterized by, The grid fixing device is a porous plate fixed on the reaction part. In the nozzle direction from top to bottom, the nozzle is arranged above the reaction part, the porous active solid material is arranged on the porous plate, and the output port is arranged below the porous plate.

14. The apparatus for harmless treatment of SF6 waste gas by atmospheric microwave plasma degradation according to claim 1, characterized by, The porous active solid material is a spherical solid material, and the diameter of the spherical solid material is 3-5 mm.

15. The apparatus for harmless treatment of SF6 waste gas by atmospheric microwave plasma degradation according to claim 14, characterized in that, The spherical solid material is a mesoporous material, which has a hierarchical pore structure comprising micropores and nanopores, a porosity of 30-70%, and mesopores with a diameter of 1-20 nm.

16. The apparatus for harmless treatment of SF6 waste gas by atmospheric microwave plasma degradation according to claim 1, characterized by, The plasma torch comprises HF, SO2, and S-O-F ion / molecular products, and the main component of the porous active solid material is a metal oxide. The metal oxide comprises at least one of iron oxide, Al2O3, MgO, and CaO.

17. The apparatus for harmless treatment of SF6 waste gas by atmospheric microwave plasma degradation according to claim 16, characterized by, The metal oxide is CaO and / or MgO.

18. The apparatus for harmless treatment of SF6 waste gas by atmospheric microwave plasma degradation according to claim 1, characterized by, The gas supply system comprises an SF6 gas source, an auxiliary gas source, and an air compressor. A first gas path of the auxiliary gas source is connected to the air compressor through a first pressurized gas path, and the first gas path is combined with a second gas path of the SF6 gas source into an output gas path. The output gas path is further connected to the air compressor through a second pressurized gas path. The output gas path is connected to the nozzle of the plasma generator.

19. The apparatus for harmless treatment of SF6 waste gas by atmospheric microwave plasma degradation according to claim 18, characterized in that, The auxiliary gas is water vapor, and the auxiliary gas source is a water vapor generator.

20. The apparatus for harmless treatment of SF6 waste gas by atmospheric microwave plasma degradation according to claim 19, characterized by The gas supply system further comprises a controller. The second gas path, the first pressurized gas path, and the second pressurized gas path are each provided with a solenoid valve and a flow meter. The solenoid valve, the flow meter, and the water vapor generator are connected to the controller.

21. The apparatus for harmless treatment of SF6 waste gas by atmospheric microwave plasma degradation according to claim 1, characterized in that, The tail gas treatment device is an alkali washing device. The input port of the alkali washing device is connected to the output port of the plasma reactor, and the output port of the alkali washing device is open to the atmosphere.

22. A method for harmless treatment of SF6 waste gas by atmospheric microwave plasma degradation, applied to the harmless treatment device for SF6 waste gas by atmospheric microwave plasma degradation according to any one of claims 1 to 21, characterized in that, Comprise: SF6 and the auxiliary gas are mixed by a gas distribution system and input into a plasma generator; The SF6 and the auxiliary gas are mixed by the plasma generator, sprayed in a predetermined spraying direction, ionized, and formed into a plasma torch; The plasma torch is adsorbed and chemically reacted by a porous active solid material arranged in the plasma torch ejection direction, to generate solid reaction products and non-basic tail gas, wherein the porous active solid material forms a chemical reaction system with the plasma torch, and the free energy change of the chemical reaction system before and after the reaction satisfies: ΔG < 0 ​ ； In the formula, ΔH is the enthalpy change of the chemical reaction system, ΔS is the entropy change of the chemical reaction system, T is the absolute temperature of the chemical reaction system, and 0 < T < 4000 K; The non-alkaline tail gas is transported to a tail gas treatment device, and a secondary reaction is performed on the non-alkaline tail gas by an alkaline solution in the tail gas treatment device to achieve harmless treatment.

23. The method of claim 22, wherein the method is performed at atmospheric pressure. SF6 and the auxiliary gas are mixed by a gas distribution system and input into a plasma generator, including: SF6 and water vapor are transported to the first gas channel and the second gas channel of the multi-gas channel nozzle of the plasma generator through independent gas channels; The multi-gas channel nozzle is pressurized by an air compressor to mix the SF6 and the water vapor when spraying.

24. The method of claim 23, wherein the method is performed at atmospheric pressure. The mixed gas is sprayed in a predetermined spraying direction by the plasma generator and ionized to form a plasma torch, including: The sprayed mixed gas is ionized by a waveguide device to form a plasma torch; The plasma torch is beamed by a discharge tube of a double-layer cylindrical tube.

25. The method of claim 24, wherein the method is performed at atmospheric pressure. After the plasma torch is beamed by the discharge tube of the double-layer cylindrical tube, the method further includes: When the end of the plasma torch does not reach the porous active solid material, the output pressure of the air compressor is increased, the microwave power of the microwave source of the waveguide device is increased, and the plasma torch is lengthened to enable the plasma torch to reach the position of the porous active solid material; Or, when the diameter of the plasma torch that reaches the porous active solid material exceeds a preset parameter, the output pressure of the air compressor is reduced, the microwave power of the microwave source is reduced, and the plasma torch is shortened.

26. The method of claim 22, wherein the method is performed at atmospheric pressure. The plasma torch is adsorbed and chemically reacted by the porous active solid material arranged in the spraying direction of the plasma torch to generate solid reaction products and non-alkaline tail gas, including: The S-O-F ion / molecular product of the plasma torch is adsorbed and reacted by the porous active solid material mainly composed of metal oxides to generate solid inorganic salts and corresponding tail gas, and the tail gas includes O2 and H2O; The unreacted S-O-F ion / molecular product is decomposed into SO2, SO3, and HF at high temperature; The SO2, SO3, and HF are mixed with the tail gas to form the non-alkaline tail gas.

27. The method of claim 26, wherein the method is performed at atmospheric pressure. After the unreacted S-O-F ion / molecular product is decomposed into SO2, SO3, and HF at high temperature, the method further includes: The SO2, SO3, and HF are adsorbed and reacted by the porous active solid material mainly composed of metal oxides to generate solid inorganic salts and H2O; The unreacted SO2, SO3, and HF are mixed with the tail gas and H2O to form the non-alkaline tail gas.

28. The method of claim 26, wherein the method is performed at atmospheric pressure. The non-alkaline tail gas is transported to a tail gas treatment device, and a secondary reaction is carried out by an alkaline solution in the tail gas treatment device to achieve harmless treatment, including: The acid gas in the non-alkaline tail gas is reacted by the alkaline solution of the alkali washing device to generate water and inorganic salt, and the acid gas includes SO2, SO3, and HF; The neutral gas in the non-alkaline tail gas is dissolved, and the neutral gas includes O2 and H2O.

29. The method of claim 28, wherein the atmospheric microwave plasma decomposes SF6 waste gas. After the acid gas in the non-alkaline tail gas is reacted by the alkaline solution of the alkali washing device to generate water and inorganic salt, the method further includes: The solid inorganic salt on the porous active solid material and the inorganic salt in the alkaline solution are extracted; Industrial concrete is manufactured by the extracted solid inorganic salt and the inorganic salt.

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