Silicone rubber vulcanization system and method based on sf6 waste gas plasma reduction treatment

Abstract

The application discloses a vulcanization system and method for silicone rubber based on SF6 waste gas plasma reduction treatment. In the system, a mixed gas chamber, a discharge system, a vulcanization system, a separation gas chamber and a collection gas bottle are sequentially connected by gas paths, the separation gas chamber is connected with the mixed gas chamber through a dilution gas chamber, flow meters and electromagnetic valves are arranged between the mixed gas chamber and the discharge system, between the mixed gas chamber and the dilution gas chamber, and between the separation gas chamber and the dilution gas chamber, and an ultraviolet light source is used for providing light for the discharge system and the vulcanization system, wherein a catalyst is arranged in the discharge system, SF6 waste gas, hydrogen and dilution gas can be introduced into the mixed gas chamber. The application can efficiently utilize S elements in SF6 waste gas, degrades SF6 through catalysis, realizes vulcanization treatment of silicone rubber base material in real time by taking S as a vulcanizing agent while depositing S in the form of an element, finally converts S elements in SF6 waste gas into vulcanized silicone rubber in the form of vulcanization crosslinking, and achieves the purpose of resource utilization of S elements in SF6 waste gas.

Description

Technical Field

[0001] This invention belongs to the field of environmental protection treatment of sulfur hexafluoride (SF6) waste gas, and is related to the technical scope of rubber processing, specifically involving a silicone rubber vulcanization system and method based on plasma reduction of SF6 waste gas. Background Technology

[0002] Sulfur hexafluoride (SF6) is an excellent insulating gas widely used in the power industry. However, SF6 is also a potent greenhouse gas, with a greenhouse effect value 23,500 times that of the same volume of CO2. In recent years, the consumption and emissions of SF6 in my country's power industry have accounted for more than 80% of the total industry output, and China's SF6 emissions exceed half of global emissions. Under my country's strategic goal of "peaking carbon and achieving carbon neutrality" and the requirements of building a new power system, the gradual reduction of SF6 emissions is an inevitable national requirement.

[0003] SF6 degradation and resource utilization are the most direct and effective means to reduce SF6 emissions. However, most existing degradation technologies focus on the completeness of SF6 dissociation, with very limited attention paid to the reuse process after the dissociation of sulfur and fluorine elements. Among the mainstream degradation methods, high-temperature pyrolysis requires maintaining a high reaction temperature, resulting in low energy efficiency; thermocatalysis can lower the reaction temperature by adding a catalyst, but at the cost of sacrificing some degradation rate; low-temperature plasma methods can achieve efficient SF6 dissociation at room temperature and atmospheric pressure, but the product control process is relatively difficult.

[0004] Regarding SF6 degradation, recent Chinese invention patents CN113082952A "A sulfur hexafluoride degradation treatment device and method based on sliding arc discharge" and CN115554823A "Sulphur hexafluoride degradation device based on thermal plasma" disclose degradation methods based on sliding arc discharge and thermal plasma torches. CN115999358A "A sulfur hexafluoride degradation device" and CN115845600A "A harmless treatment system for sulfur hexafluoride waste gas in electrical insulators" disclose degradation treatment devices based on thermocatalytic cycles or series connections, improving the SF6 degradation process in terms of degradation efficiency, energy efficiency, and degradation sufficiency. However, in the above methods and other related methods, the main toxic products generated after degradation are mostly absorbed by alkaline materials and converted into low-economic-value salts. Furthermore, the utilization of elemental sulfur is not mentioned, resulting in serious waste of the element. Summary of the Invention

[0005] To address at least one of the problems existing in current technologies, this invention proposes a silicone rubber vulcanization system and method based on SF6 waste gas plasma reduction. This system utilizes low-temperature plasma catalytic reduction of SF6 to achieve silicone rubber material vulcanization, efficiently utilizing sulfur (S) from the SF6 waste gas. Through plasma catalytic degradation of SF6, S is deposited in elemental form while simultaneously acting as a vulcanizing agent to vulcanize the silicone rubber base material in real time. Ultimately, the S element from the SF6 waste gas is converted into the vulcanized silicone rubber through vulcanization crosslinking, achieving the goal of resource utilization of S from SF6 waste gas. This invention features high degradation efficiency, good stability, low carrier gas consumption, complete SF separation, and full utilization of S.

[0006] To achieve the aforementioned objectives, this invention provides an SF6 waste gas degradation and silicone rubber vulcanization system based on microwave plasma, comprising a mixing chamber, a discharge system, a vulcanization system, a separating chamber, a collecting cylinder, a dilution chamber, and an ultraviolet light source.

[0007] The mixing chamber, discharge system, sulfidation system, separation chamber, and collection cylinder are connected sequentially by gas paths. The separation chamber is connected to the mixing chamber through a dilution chamber. Flow meters and solenoid valves are installed between the mixing chamber and the discharge system, between the mixing chamber and the dilution chamber, and between the separation chamber and the dilution chamber. An ultraviolet light source is used to provide illumination for the discharge system and the sulfidation system. The discharge system is equipped with a catalyst. SF waste gas, hydrogen, and dilution gas can be introduced into the mixing chamber.

[0008] Furthermore, it is equipped with an SF6 exhaust gas source, an H2 hydrogen gas source, and a dilution gas source. The SF6 exhaust gas source is pre-treated or pre-treated by conventional exhaust gas purification methods and is connected to the mixing chamber. The H2 hydrogen gas source is directly connected to the mixing chamber. The dilution gas source is connected to the mixing chamber through a flow meter and a solenoid valve, and is connected in parallel with the dilution gas chamber in the gas path.

[0009] Furthermore, it also includes a washing chamber and a drying chamber, which are connected in sequence with the mixing chamber. A flow meter and a solenoid valve are installed between the drying chamber and the mixing chamber.

[0010] Acidic impurities, water vapor, and solid particles in SF6 exhaust gas can be removed by conventional methods such as alkaline adsorbents and wet scrubbing. The gas flow is pretreated before being introduced into the mixing chamber.

[0011] Furthermore, in the aforementioned SF6 waste gas purification pretreatment, the alkaline solution can be NaOH, KOH, Ca(OH)2, NaHCO3, etc., used to treat common impurity gases in the SF6 waste gas source such as SO2, SOF, H2S, and CS2. Solid particles such as activated alumina and activated carbon can absorb the small amount of moisture washed from the SF6 waste gas source. Gas path deposition can remove the small amount of solid particles carried in the gas flow. The SF6 waste gas source entering the mixing chamber should have a high SF6 purity (>99.9%).

[0012] Furthermore, the diluting gas is either Ar or He.

[0013] Furthermore, in the mixing chamber, the SF6:H2 ratio is set between 6.5 and 7.0, the SF6 concentration is controlled between 2 and 10%, and the remainder is dilution gas.

[0014] SF6 gas is connected to the mixing chamber via a first flow meter and a first solenoid valve, where SF6, H2, and Ar are mixed. The SF6:H2 ratio is set between 6.5 and 7.0, and the SF6 concentration is controlled between 2% and 10%, with 5% generally recommended. The remainder is used as a dilution gas. Rare gases such as Ar or He are recommended for the dilution gas; N2 is generally not recommended because it participates in the discharge dissociation of SF6 in small amounts, generating NF. x Greenhouse gases such as (x<4). If the SF6 concentration is selected as the recommended value of 5%, then the H2 concentration should be controlled between 32.5% and 35%, and the dilution gas concentration should be controlled between 60.0% and 62.5%. The concentration ratio of the ternary mixed gas can be prepared according to the actual flow rate using a flow meter.

[0015] Furthermore, the plasma generation method in the discharge system is any one of microwave discharge, sliding arc discharge, or dielectric barrier discharge.

[0016] Furthermore, the inner walls of the discharge system, sulfidation system, and gas collection cylinder that come into contact with the gas are all equipped with anti-corrosion coatings or anti-corrosion materials.

[0017] Furthermore, in the discharge system, the temperature of the plasma discharge region is not lower than 800℃, in order to reach the thermal decomposition temperature of SF6, and the input power of the discharge equipment is 2 to 5 kW.

[0018] Furthermore, the discharge system is connected to the sulfidation system via a gas path, with the sulfidation system positioned below the discharge system in a physical sense to facilitate the deposition of elemental sulfur.

[0019] Furthermore, in the discharge system, it is recommended to use a metal-supported catalyst, with alumina or titanium oxide as the support and non-precious metals such as copper or nickel as the supporting metal. The catalyst particle size is recommended to be in the cm range.

[0020] Furthermore, for the discharge system and the vulcanization system, the device walls are made of quartz glass or other transparent, high-temperature resistant materials. Ultraviolet light sources with a wavelength range of 180–320 nm are placed 5–20 cm outside the two devices to promote the activation and degradation of SF6 and the vulcanization reaction of the silicone rubber prepolymer, respectively, thereby accelerating the reaction and improving energy efficiency. The inlet and outlet of the discharge system are connected to the mixing chamber and the vulcanization system, respectively.

[0021] Furthermore, in the vulcanization system, the filling mass of the silicone rubber prepolymer is controlled according to the deposition rate of elemental sulfur and the vulcanization time of the silicone rubber. The mass fraction of elemental sulfur is controlled at 3 to 4 parts, and it is directly vulcanized with the silicone rubber prepolymer for 6 to 8 hours.

[0022] Furthermore, the vulcanization system includes vulcanization devices such as flat vulcanizing machines.

[0023] Furthermore, a distillation column is installed in the gas separation chamber, and a temperature control device is also provided.

[0024] Furthermore, a compression pump is installed inside the dilution chamber, and the introduced gas is temporarily stored at 1.5 to 2 atmospheres. The mixed gas is then introduced into the mixing chamber through a flow meter and a pressure reducing valve, so as to realize the recycling of the dilution gas.

[0025] The top of the separation chamber has an outlet, which is connected to the dilution chamber via a flow meter and a solenoid valve. A gas compression pump is installed in the dilution chamber to collect and compress the Ar and H2S produced in the separation chamber, maintaining the pressure in the dilution chamber at 1.5–2.0 atmospheres. The other side of the dilution chamber is connected to the mixing chamber via a flow meter and a solenoid valve to enable the recycling of the dilution gas and ensure that the H2S byproducts in the system participate in the next round of SF6 reduction reaction.

[0026] This invention provides a method for vulcanizing silicone rubber based on SF6 waste gas plasma reduction treatment, comprising the following steps:

[0027] SF6 exhaust gas is mixed with H2 and dilution gas in a preset ratio in the mixing chamber and then introduced into the discharge system for reduction by plasma discharge.

[0028] The products after discharge treatment include elemental sulfur, HF and a small amount of H2S. There may also be trace amounts of SF6 and H2 remaining in the system, with the rest being dilution gases.

[0029] The product enters the vulcanization system, which contains silicone rubber prepolymer. In the vulcanization system, elemental sulfur is deposited from the gas phase to the solid phase, and elemental sulfur is added as a vulcanizing agent in the vulcanization process of silicone rubber.

[0030] The exhaust gas from the sulfurization system is fed into the separation chamber, where the temperature is controlled. By utilizing the difference in liquefaction temperature of different gases, HF is liquefied and deposited, and then fed into the collection chamber for collection. The dilution gas, a small amount of H2S, and residual SF6 and H2 gases are recycled through the dilution chamber.

[0031] The elemental sulfur produced by the discharge degradation of SF6 is continuously vulcanized with the silicone rubber prepolymer under the promotion of ultraviolet light, and finally vulcanized silicone rubber is obtained.

[0032] Compared with the prior art, the present invention can achieve at least the following beneficial effects:

[0033] (1) This invention is based on a low-temperature plasma-coupled catalyst to achieve high-efficiency dissociation of SF6, which promotes the efficient and complete reaction of SF6 / H2 and achieves effective separation of SF elements.

[0034] (2) The S element reduced and deposited in this invention is used as a vulcanizing agent in the vulcanization process of silicone rubber, which can realize the resource utilization of S element.

[0035] (3) Part of the heat source in the discharge system of the present invention can be input into the subsequent vulcanization system through airflow to provide heat source for the vulcanization system and achieve the purpose of saving energy consumption.

[0036] (4) By adding an ultraviolet light source, the present invention utilizes the optical properties of SF6 dissociation and silicone rubber vulcanization / interface reaction to achieve a dual promoting effect, reduce the energy consumption of SF6 degradation and vulcanization treatment, and improve the reaction efficiency.

[0037] (5) The present invention can obtain high-purity HF gas based on the distillation process to realize the resource recovery of F element. H2S can participate in the SF6 reduction and degradation process again through the circulating gas path to ensure the full reduction and solidification of S element and the utilization efficiency of H element as a reducing agent.

[0038] (6) The present invention can add a catalyst to promote the degradation of SF6. After degradation, the gas directly participates in S deposition and silicone rubber vulcanization, thereby improving the heat (energy) utilization efficiency. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of a silicone rubber vulcanization system based on SF6 waste gas plasma catalytic reduction, provided as an embodiment of the present invention.

[0040] Figure 2This is a schematic diagram of a silicone rubber vulcanization system using microwave discharge in an embodiment of the present invention.

[0041] Figure 3 This is a schematic diagram of the processing flow in an embodiment of the present invention.

[0042] In the diagram: 1. Mixing chamber; 2. First flow meter; 3. First solenoid valve; 4. Discharge system; 5. Vulcanization system; 6. Separating chamber; 7. Collecting cylinder; 8. Second solenoid valve; 9. Second flow meter; 10. Dilution chamber; 11. Third flow meter; 12. Third solenoid valve; 13. Ultraviolet light source; 14. Washing chamber; 15. Drying chamber; 16. Fourth flow meter; 17. Fourth solenoid valve. Detailed Implementation

[0043] The technical solution of the present invention will be further described in detail below through embodiments and in conjunction with the accompanying drawings.

[0044] Please see Figure 1 This invention provides a silicone rubber vulcanization system based on SF6 waste gas plasma reduction treatment, which can use elemental sulfur generated from the plasma reduction of SF6 waste gas as a vulcanizing agent to achieve silicone rubber vulcanization. The system includes a mixing chamber 1, a discharge system 4, a vulcanization system 5, a separating chamber 6, a collecting gas cylinder 7, a dilution chamber 10, an ultraviolet light source 13, and gas path control devices such as solenoid valves and flow meters. SF6 waste gas, pure H2 gas, and dilution gas (such as Ar) can be introduced into the mixing chamber 1.

[0045] The mixing chamber 1, discharge system 4, vulcanization system 5, separation chamber 6, and collection cylinder 7 are connected in sequence, with the discharge system 4 located above the vulcanization system 5. The separation chamber 6 is also connected to the dilution chamber 10 through a pipe, and the dilution chamber 10 is connected to the mixing chamber 1 through a pipe. A first flow meter 2 and a first solenoid valve 3 are installed on the pipe between the mixing chamber 1 and the discharge system 4. A second solenoid valve 8 and a second flow meter 9 are installed on the pipe between the separation chamber 6 and the dilution chamber 10. A third flow meter 11 and a third solenoid valve 12 are installed on the pipe between the mixing chamber 1 and the dilution chamber 10. An ultraviolet light source 13 is used to provide the necessary illumination for the operation of the discharge system 4 and the vulcanization system 5.

[0046] The mixing chamber 1 is also connected to the H2 gas source.

[0047] The pre-purified SF6 waste gas is introduced into the inlet of the mixing chamber 1. The mixing chamber 5 is connected to the first solenoid valve 3, the H2 gas source, and the third solenoid valve 12, allowing the pre-treated SF6 waste gas, pure H2 gas, and dilution gas to be introduced and mixed in a preset ratio. In some embodiments of the present invention, the volume of the mixing chamber 1 is not less than 100L, the SF6:H2 ratio is controlled at 6.5–7, the SF6 concentration is controlled at 2–10%, and the remainder is filled with dilution gas Ar. After mixing, the gas is controlled by the first flow meter 2 and the third solenoid valve 3 to flow into the discharge system 4. The total flow rate of SF6 / H2 / dilution gas is controlled at 10–30 L / min.

[0048] In some embodiments of the present invention, a corrosion-resistant fan is provided inside the mixing chamber 1 to promote uniform mixing of gases.

[0049] The discharge system 4 includes a discharge reactor and its grounding system, a power supply, a reaction gas path, and a heat dissipation device. The specific components of the discharge system can be purchased as finished equipment from domestic manufacturers. The high-voltage and low-voltage ends of the power supply are connected to the high-voltage electrode of the discharge reactor and the grounding system, respectively, providing the high-voltage input required for discharge. The heat dissipation device is located around the discharge reactor and the plasma power supply. In some embodiments of this invention, air cooling is the primary form of heat dissipation, used to maintain the operating temperature of the plasma power supply and regulate the ambient temperature of the discharge reactor. The discharge reactor is a plasma reactor.

[0050] The discharge system can employ microwave discharge, sliding arc discharge, or dielectric barrier discharge, etc. In some embodiments of the present invention, microwave discharge, which has a higher reaction temperature, is preferred. The microwave discharge region has a high temperature (reaching 1500-5000K), and the high-temperature energy can be fully utilized for the thermal degradation of SF6.

[0051] The discharge reactor contains metal-loaded oxide catalyst solid particles; the discharge system 4 is placed above the sulfidation system 5 in a physical sense. The inlet of the discharge system 4 is connected to the mixing chamber 1, and the outlet of the discharge system 4 is connected to the top inlet of the sulfidation system 5 through a large-diameter gas pipe (in some embodiments of the present invention, the diameter is not less than 10 mm), ensuring that the elemental S solid powder generated by the violent discharge reduction of SF6 in the discharge system 4 can enter the sulfidation system 5 through the reaction gas path with the high-speed gas flow.

[0052] In some embodiments of the present invention, metal oxide-supported metal catalyst particles are added to the discharge reactor. The support can be alumina or titanium oxide, etc., which have a high dielectric constant to promote discharge and have good corrosion resistance. The supporting metal can be non-precious metals such as copper and nickel. The particle size is recommended to be in the cm range to ensure sufficient porosity for airflow and prevent it from hindering the sedimentation process of elemental sulfur.

[0053] In some embodiments of the present invention, during the discharge process, the flow rate of the SF6 / H2 / dilution gas mixture is controlled at 10–30 L / min, depending on the SF6 / H2 / dilution gas flow rate. 6的 The initial concentration is determined, and the input power is 0.5-1kW. Taking 5% SF6 and a total flow rate of 15L / min as an example, if all SF6 is degraded, theoretically 293g of SF6 waste gas can be treated within 1 hour, converting it into 64.3g of elemental sulfur.

[0054] The inner wall of the vulcanization system 5 is coated to prevent corrosion from fluorine-containing gases, and a temperature control system is provided on the vulcanization system 5. In some embodiments of the present invention, the coated film is made of Teflon or incubator rubber, etc. The temperature of the vulcanization system 5 is maintained at approximately 160°C by the temperature control system.

[0055] The vulcanization system 5 is the site where the silicone rubber undergoes vulcanization treatment. The air inlet of the vulcanization system 5 is connected to the discharge system 4, and the air outlet is connected to the separation chamber 6.

[0056] In some embodiments of the present invention, the vulcanization system is a flat vulcanizing machine.

[0057] In vulcanization system 5, the mass fraction of sulfur deposited in elemental sulfur can be controlled at 3-4 parts. It is directly vulcanized with the prepolymer at a vulcanization temperature of 160°C for 6-8 hours to obtain the vulcanized silicone rubber product. In some embodiments of the present invention, a predetermined mass of silicone rubber prepolymer (the product after rubber compounding) is pre-placed in vulcanization system 12, and the mass fraction of elemental sulfur in the vulcanization treatment is 3 (out of a total of 100). Vulcanization system 12 performs direct vulcanization at a vulcanization temperature of 160°C for 6-8 hours to obtain the vulcanized silicone rubber product.

[0058] Due to the excessively high reaction temperature in discharge system 4, elemental sulfur (S) flows out in a gaseous state through the reaction gas path and can directly contact the silicone rubber prepolymer. The vulcanization system 5 is equipped with a temperature control device, which uses gas flow to obtain the heat generated in discharge system 4, maintaining the system temperature around 160℃. The main products after discharge degradation are elemental sulfur, H2S, HF, and the remaining H2 and SF6. Adjusting the SF6:H2 ratio ensures that the remaining H2 and SF6 gases are at low concentrations. H2S is generated when excess H2 is added, leading to excessive reduction of S. At the aforementioned high gas velocity, elemental sulfur can rapidly solidify during the prepolymer purging process, and the remaining gases are introduced into the subsequent separation chamber 6. Among the remaining gases, only HF has some reactivity, but its gaseous state and high gas velocity limit its reaction with the silicone rubber prepolymer. Furthermore, the small amount of fluorination on the silicone rubber surface helps improve its surface hydrophilicity and charge dissipation properties, having no significant negative impact on the overall vulcanization process.

[0059] In some embodiments of the present invention, the silicone rubber prepolymer is obtained by plasticizing, mixing, extrusion / calendering, etc., using raw silicone rubber and auxiliary materials. The above-mentioned pretreatment technologies are all basic processes for rubber processing and can be easily obtained in related fields.

[0060] The separation chamber 6 is connected to the top of the sulfidation system 5 via a gas path. The interior of the separation chamber 6 is a distillation column equipped with a temperature control device. In some embodiments of the invention, the separation chamber 6 can operate at atmospheric pressure, controlling the temperature between -20°C and 0°C, causing hydrogen fluoride HF (liquefaction temperature 19.54°C, 1 atm) to liquefy at the bottom, while dilution gases Ar (liquefaction temperature -185.8°C, 1 atm) and H2S (liquefaction temperature -60.28°C, 1 atm) exist as gases at the top, achieving gas separation. Ar and a small amount of H2S are introduced from the top of the separation chamber 6 into the dilution chamber 10 through the second solenoid valve 8 and the second flow meter 9.

[0061] The dilution chamber 10 is connected to the separation chamber 6 on one side and to the mixing chamber 1 on the other side. A compression pump is installed in the dilution chamber 10 to collect the remaining dilution gas and a small amount of H2S gas after discharge, and to compress the collected Ar and H2S, maintaining the pressure at 1.5 to 2 atmospheres. The mixture is connected to the mixing chamber 1 through the third flow meter 11 and the third solenoid valve 12, so that the mixed gas can be introduced into the mixing chamber 1 to realize the recycling of Ar. H2S has reducing properties and can react with SF6 to generate HF and S elemental deposits, thus being added to the reduction reaction of SF6 to achieve secondary treatment with H2S.

[0062] The gas flow in the vulcanization system 5 enters the inlet located on the side of the separation chamber 6 through the outlet. The upper / top and lower / bottom of the separation chamber 6 are connected to the dilution chamber 10 and the collection bottle 7 through gas passages, respectively. The gas flow that interacts with the vulcanization system 5 after discharge enters the separation chamber 6, including HF, Ar, a small amount of H2S, and a very small amount of H2 and SF6. The separation chamber 6 contains a gas distillation column. By controlling the liquefaction temperature of various gases, the separation of Ar (-185.8℃, 1atm), HF (19.54℃, 1atm), and H2S (-60.28℃, 1atm) is achieved. Among them, Ar and a small amount of H2S are introduced into the dilution chamber 10 in gaseous state from the top for storage, and HF is separated at the bottom and introduced into the collection bottle 7 in liquefied form for storage.

[0063] In some embodiments of the present invention, during operation, an ultraviolet light source 13 is placed approximately 5-20 cm away from the discharge system 4 and the sulfidation system 5. The light source is kept on during the SF6 gas discharge degradation and sulfidation system treatment, providing ultraviolet light in the 180-320 nm wavelength band, with a light source power of 6000 uW / cm². 2 It can promote the activation and degradation of SF6 and the vulcanization reaction of silicone rubber prepolymer, thereby accelerating the reaction and improving energy efficiency.

[0064] In one embodiment of the present invention, a microwave plasma device is used as a typical plasma processing device. This embodiment provides an implementation example of silicone rubber vulcanization based on microwave plasma reduction treatment of SF6 to deposit elemental sulfur. The system of the embodiment is as follows: Figure 2 As shown. The system also includes a washing chamber 14 and a drying chamber. The washing chamber 14, drying chamber 15, and mixing chamber 1 are connected in sequence. A fourth flow meter 16 and a fourth solenoid valve 17 are installed on the pipe between the drying chamber 15 and the mixing chamber 1. Please refer to... Figure 2 and Figure 3 The specific processing procedure of this system is as follows:

[0065] (1) Pretreatment of SF6 exhaust gas: SF6 exhaust gas is introduced into scrubbing chamber 14 for wet scrubbing, which contains 40L of saturated Ca(OH)2 solution. After scrubbing, the SF6 exhaust gas is introduced into drying chamber 2, where activated alumina adsorbs and removes moisture from the gas stream. During the treatment process, the flow rate of SF6 exhaust gas is controlled by the fourth flow meter 16 and the fourth solenoid valve 17, and the flow rate is controlled at 0.75L / min.

[0066] (2) Preparation of SF6 mixed gas: H2 gas source and dilution gas Ar gas source are supplied to the mixing chamber 1. SF6:H2 = 1:7. The flow rate of H2 is controlled at 5.25 L / min, the flow rate of Ar is 24 L / min, the total flow rate at the outlet of the mixing chamber 1 is about 30 L / min, and the SF6 concentration is about 5%.

[0067] (3) SF6 discharge reduction treatment: Controlling the first flow meter 2 and the first solenoid valve 3, the SF6 / H2 / Ar mixed gas is introduced into the discharge system 4, i.e., the microwave discharge reactor. The microwave discharge in the microwave discharge reactor is driven by a microwave generator, with the input power controlled at 5kW. The center temperature of the microwave discharge reactor is approximately 2000K. The upper part of the microwave discharge reactor is filled with catalyst particles, which can be supported by high-temperature resistant quartz wool or ceramic porous baffles. In the microwave discharge reactor, SF6 is reduced by H2 to elemental S and HF, as well as a small amount of H2S. The SF degradation rate is not less than 99%. The discharge gas flow is injected from the top to the bottom of the microwave discharge reactor, and the exhaust gas after the reaction is introduced into the sulfidation system 5 through the bottom gas path of the microwave discharge reactor. During the discharge degradation, the ultraviolet light source 13 is kept on at a distance of 15cm and provides illumination in the 180-320nm wavelength band.

[0068] (4) Silicone rubber vulcanization treatment: The vulcanization system 5 includes a flat vulcanizing machine. A total of 6430g of silicone rubber prepolymer is pre-placed according to the following conditions: 192.9g of elemental sulfur (sulfur) and 3 parts by weight of sulfur vulcanizing agent. The prepolymer is vulcanized at 160℃ for 6–8 hours to obtain the vulcanized silicone rubber product. During discharge degradation, the ultraviolet light source 13 is kept on at a distance of 10cm and provides illumination in the 180–320nm wavelength range.

[0069] (5) The treated tail gas in the sulfurization system 5, including gaseous products such as Ar, HF, and H2S, is separated and discharged into the separation chamber 6. The separation chamber 6 has a built-in distillation column to maintain the temperature of the separation chamber 6 at -20℃. HF, due to its higher liquefaction temperature, liquefies and deposits at the bottom of the separation chamber 6. Ar, a small amount of H2S, residual SF6, and H2 remain in a gaseous state due to their low liquefaction temperature and are discharged from the top of the separation chamber 6. The gas is then controlled by the second solenoid valve 8 and the second flow meter 9 to flow into the dilution chamber 10. The remaining liquid HF gas is injected into the anti-fluorine coating collection cylinder 7 for storage.

[0070] (6) Dilution Gas and Byproduct Circulation: A compression pump is installed in the dilution chamber 10 to pump and compress the Ar, H2S, and other gases discharged from the separation chamber 6. After collection, the pressure of the dilution chamber 10 is maintained at a level not lower than 1.5 atmospheres, and is controlled by the third flow meter 11 and the third solenoid valve 12 to flow into the mixing chamber 5. This ensures that, apart from the Ar gas source being supplied during the initial operation phase, the Ar in the system mainly comes from the recycled Ar stored and collected in the dilution chamber 15. The ratio of H2S, SF6, and H2 can be controlled to keep it at extremely low levels, generally below 1% for H2S and below 0.1% for SF6 and H2, so that their impact on the gas preparation in the mixing chamber is negligible.

[0071] In the aforementioned embodiments of the present invention, SF6 is reduced to elemental sulfur (S) and HF via H2 through purification pretreatment, proportional gas mixing, and discharge reduction. The gaseous S is deposited through a vulcanization system and used as a vulcanizing agent in the vulcanization reaction of the silicone rubber prepolymer. The resulting cross-linked silicone rubber product is obtained through vulcanization treatment. The remaining gases are liquefied and separated based on differences in liquefaction temperature, ultimately achieving the reuse of elemental S deposition, recovery of the HF liquid phase, and recycling of the dilution gas and byproduct H2S.

[0072] The specific embodiments described herein are merely illustrative examples of the principles and methods of the present invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to replace them, such as changing the form of low-temperature plasma discharge, reactor geometry, type of tail gas absorption medium and absorption treatment sequence, sample introduction method and mixing ratio, etc., and changing the type of prepolymer, temperature and pressure conditions and vulcanization time of silicone rubber vulcanization, etc., but without departing from the spirit of the present invention or exceeding the scope defined by the appended claims.

Claims

1. A silicone rubber vulcanization system based on SF6 waste gas plasma reduction treatment, characterized in that, It includes a mixing chamber (1), a discharge system (4), a sulfidation system (5), a separating chamber (6), a collecting cylinder (7), a dilution chamber (10), and an ultraviolet light source (13). The mixing chamber (1), discharge system (4), vulcanization system (5), separation chamber (6), and collection cylinder (7) are connected in sequence. The separation chamber (6) is connected to the mixing chamber (1) through the dilution chamber (10). Flow meters and solenoid valves are installed between the mixing chamber (1) and the discharge system (4), between the mixing chamber (1) and the dilution chamber (10), and between the separation chamber (6) and the dilution chamber (10). The ultraviolet light source (13) is used to provide illumination for the discharge system (4) and the vulcanization system (5). The discharge system (4) is equipped with a catalyst. SF6 waste gas, hydrogen and dilution gas can be introduced into the mixing chamber (1). During operation, silicone rubber prepolymer is installed in the vulcanization system (5). The deposition of elemental sulfur from the gas phase to the solid phase is realized in the vulcanization system (5). Elemental sulfur is added as a vulcanizing agent in the vulcanization process of silicone rubber.

2. The silicone rubber vulcanization system based on SF6 waste gas plasma reduction treatment according to claim 1, characterized in that, The diluting gas is either Ar or He.

3. The silicone rubber vulcanization system based on SF6 waste gas plasma reduction treatment according to claim 1, characterized in that, The plasma generation form in the discharge system (8) is any one of microwave discharge, sliding arc discharge, or dielectric barrier discharge.

4. The silicone rubber vulcanization system based on SF6 waste gas plasma reduction treatment according to claim 1, characterized in that, The inner walls of the discharge system (4), the sulfidation system (5), and the gas collection cylinder (7) that come into contact with the gas are all equipped with anti-corrosion coatings or anti-corrosion material devices.

5. The silicone rubber vulcanization system based on SF6 waste gas plasma reduction treatment according to claim 1, characterized in that, In the mixing chamber (1), the SF6:H2 ratio is set between 6.5 and 7.0, the concentration of SF6 is controlled between 2 and 10%, and the remainder is dilution gas.

6. The silicone rubber vulcanization system based on SF6 waste gas plasma reduction treatment according to claim 1, characterized in that, In the discharge system (8), the temperature of the plasma discharge region is not lower than 800°C, so as to reach the thermal decomposition temperature of SF6.

7. The silicone rubber vulcanization system based on SF6 waste gas plasma reduction treatment according to claim 1, characterized in that, In the vulcanization system (5), the filling mass of the silicone rubber prepolymer is controlled according to the deposition rate of element S and the vulcanization time of silicone rubber. The mass of element S deposition is controlled at 3 to 4 parts, and it is directly vulcanized with the silicone rubber prepolymer for 6 to 8 hours.

8. The silicone rubber vulcanization system based on SF6 waste gas plasma reduction treatment according to claim 1, characterized in that, The ultraviolet light source (13) is set at a predetermined distance outside the two devices, the discharge system (4) and the sulfidation system (5). The ultraviolet light source (13) has a wavelength range of 180~320nm.

9. A silicone rubber vulcanization system based on SF6 waste gas plasma reduction treatment according to any one of claims 1-8, characterized in that, The gas separation chamber (6) is equipped with a distillation column and a temperature control device.

10. A method for vulcanizing silicone rubber based on SF6 waste gas plasma reduction treatment, characterized in that, Based on the system implementation of any one of claims 1-9, the method includes the following steps: SF6 exhaust gas is mixed with H2 and dilution gas in a preset ratio in the mixing chamber (1) and then introduced into the discharge system (4) for plasma discharge reduction; The products after discharge treatment include elemental sulfur, HF and a small amount of H2S. There may also be trace amounts of SF6 and H2 remaining in the system, with the rest being dilution gases. The product enters the vulcanization system (5), which contains silicone rubber prepolymer. In the vulcanization system (5), S element is deposited from the gas phase to the solid phase, and S element is added as a vulcanizing agent in the vulcanization process of silicone rubber. The treated tail gas in the sulfurization system (5) is introduced into the separation gas chamber (6). The temperature is controlled in the separation gas chamber (6). By utilizing the difference in liquefaction temperature of different gases, HF is liquefied and deposited and introduced into the collection gas cylinder (7) for collection. The dilution gas, a small amount of H2S, residual SF6 and H2 gas are recycled through the dilution gas chamber (10). The elemental sulfur produced by the discharge degradation of SF6 is continuously vulcanized with the silicone rubber prepolymer under the promotion of ultraviolet light, and finally vulcanized silicone rubber is obtained.

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